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RF anechoic chamber test facilities
Microsoft Academic Search
Radio frequency anechoic test chamber design is discussed. Radar absorbing materials are described. Electromagnetic compatibility testing in anechoic chambers is introduced. Special purpose chambers, e.g., for investigating a compact frequency range are considered.
B. F. Lawrence
An anechoic chamber facility for investigating aerodynamic noise
NASA Technical Reports Server (NTRS)
The aerodynamic noise facility was designed to be used primarily for investigating the noise-generating mechanisms of high-temperature supersonic and subsonic jets. The facility consists of an anechoic chamber, an exhaust jet silencer, instrumentation equipment, and an air heater with associated fuel and cooling systems. Compressed air, when needed for jet noise studies, is provided by the wind tunnel compressor facility on a continuous basis. The chamber is 8.1 m long, 5.0 m wide, and 3.0 m high. Provisions have been made for allowing outside air to be drawn into the anechoic chamber in order to replenish the air that is entrained by the jet as it flows through the chamber. Also, openings are provided in the walls and in the ceiling for the purpose of acquiring optical measurements. Calibration of the chamber for noise reflections from the wall was accomplished in octave bands between 31.2 Hz and 32 kHz.
Massier, P. F.; Parthasarathy, S. P.
Deficiency of anechoic\\/semi-anechoic chambers
There is a perceived problem with the anechoic chamber facility, i.e., significant deviations from the ōstandardö open site attenuation performance have been observed at the lower end of the frequency range. The possible mechanisms leading to the observed behaviour are described and the analysis presented confirms the expected performance of such a chamber. The modelling approach, using both free-space electromagnetic
Y. Huang; D. J. Edwards
Anechoic Aeroacoustic Test Facility.
National Technical Information Service (NTIS)
The University of Florida has completed the construction of an advanced aeroacoustics testbed to facilitate both existing and future Air Force/ DoD research projects. The proposed facility consists of a versatile anechoic chamber processing a test volume ...
L. N. Cattafesta P. Hubner M. Sheplak B. Carroll
Anechoic chamber wideband antenna measurements
The method is considered which consists of measurements of output antenna signals on a number of frequencies and Fourier transformation of data into time domain for separation of own antenna field and interference fields. The results of testing at serial facility for antenna measurements in an anechoic chamber are presented as for diagnosis of scattered fields, as for improvement of
A. V. Kalinin
The semi-open anechoic chamber of the MBB antenna test facility
The MBB antenna test facility designed for measurements on aerospace antennas tested either on full scale or scaled down models is described. The heart of the main test range is the anechoic chamber with inner dimensions of 8.8 m x 8.6 m x 8.3 m. There measurements can be made in the frequency range of about 120 MHz to 30
K. A. Koob; B. H. C. Liesenkoetter
Experimental evaluation of anechoic chambers
Antenna gain and radiation patterns, as well as radar cross sections of objects are measured in anechoic chambers. The chambers are used for convenience and to eliminate, as far as practical, sources of unwanted reflections. It would be useful if anechoic chambers could be categorized by a figure of merit which would predict their performance when antenna measurements are made.
W. Kummer; A. Villeneuve
Procurement and Evaluation of an Anechoic Chamber.
This report discusses methods to evaluate and to calibrate an anechoic chamber (indoor antenna range) and brings out the pitfalls that can be encountered in the procurement of an anechoic chamber. Procurement specifications for an anechoic chamber are als...
B. D. Rethmeyer W. A. Price
Anechoic chamber for VHF and UHF bands
NASA Astrophysics Data System (ADS)
Built in 1969, the anechoic chamber of CRL has been used to the fullest by researchers in many fields such as EMI, EMC, antenna design, standard of electric field intensity, and type approval testing. In particular, in the early days of space development in Japan, many satellite-born antennas were developed in this anechoic chamber. However, a quarter of a century has passed since its construction and deteriorated performance due to superannuation sometimes caused difficulties in experiments conducted in the chamber. In 1993, CRL constructed a Measuring Facility for Radio Research (MFRR) and the anechoic chamber for VHF-UHF bands was remodeled as one of the sub-facilities of MFRR. The remodeling work included full replacement of the electromagnetic shielding, absorbers and measurement system. Since the remodeled anechoic chamber is being used not only for EMI tests but also for other purposes, a full-anechoic chamber has been adopted. In addition the chamber has been designed for the frequency range between 30 MHz and 10 GHz. After the remodeling work, the performance of the chamber is greatly improved. The average shielding factor is better than 85 dB for all frequency ranges and the unwanted reflection characteristic is -30 dB for frequencies above 1 GHZ. This paper summarizes the remodeling work, and the specifications and performance of the remodeled anechoic chamber.
Morikawa, Takao; Sugiura, Akira; Harima, Katsushige; Masuzawa, Hiroshi
Anechoic Chamber Simulation and Verification.
This project considers an electromagnetic field simulation of an anechoic chamber with verification measurements. The simulation is a Geometric Optics (Ray Tracing) mathematical model of the direct path between two antennae and interfering scattering. The...
R. M. Taylor
Anechoic chamber qualification at ultrasonic frequencies
Qualifying an anechoic chamber for frequencies that extend into the ultrasonic range is necessary for research work involving airborne ultrasonic sound. For example, an anechoic chamber allows for measurements of the direct sound radiated by an object without reflections from walls. The ANSI S12.55/ISO 3745 standard which covers anechoic chamber qualification does not extend into the ultrasonic frequency range, nor have others discussed this frequency range in the literature. An increasing number of technologies are employing ultrasound; hence the need to develop facilities to conduct basic research studies on airborne ultrasound. This presentation will discuss the challenges associated with chamber qualification and present the results for qualification of a chamber at Brigham Young University. [This work has been funded by the Los Alamos National Laboratory
Jenny, Trevor; Anderson, Brian
Characteristics of a Tapered Anechoic Chamber.
The characteristic features of a tapered anechoic chamber are described. The smooth illumination amplitude in the chamber makes it usable as an indoor range for antenna pattern measurements, even at low frequencies. Variations in the transmission attenuat...
H. E. King F. I. Shimabukuro J. L. Wong
Synthesizing realistic environments in an anechoic chamber
We present an experimental setup in anechoic chamber that synthesizes realistic frequency selective fading properties. Antennas for S-band mobile TV applications are tested in that synthesized environment.
L. Rudant; C. Delaveaud; M. AbouElAnouar
Characteristics of a tapered anechoic chamber
The characteristic features of a tapered anechoic chamber are described. The smooth illumination amplitude in the chamber makes it usable as an indoor range for antenna pattern measurements, even at low frequencies. Variations in the transmission attenuation in the chamber as compared to free space require careful interpretation of absolute gain and cross section data.
H. King; F. Shimabukuro; J. Wong
Diagonal horn improves anechoic chamber tests
It is pointed out that whereas anechoic chambers have been improved, this is not true of their source antenna. The diagonal horn is seen as offering a high-performance alternative that can be of particular help in radar cross section (RCS) measurements. To approach the maximum RCS measurement accuracy that a given chamber with a particular radar-absorbent material (RAM) can achieve,
S. J. Foti; D. D. McGahey
The ARL/FED anechoic chamber
This report documents the design and acoustic characteristics of the Applied Research Laboratory Department anechoic chamber. It is located on the above-console deck of the Garfield Thomas Water Tunnel situated so as to allow its use in conjunction with the Axial Flow Research Fan (AFRF). The internal free dimensions of the chamber are 2.74 x 3.05 x 1.98 meters (9 x 10 x 6.5 ft.). The sound absorbing walls are composed of polyurethane foam acoustic wedges, air voids, embossed acoustic foam wall lining, plywood and wood frame members. Air intake ducts, baffled and lined with a lead-foam sheet, provide an adequate air volume for the AFRF. Based on measurements of transmission loss and inverse square law, the chamber is considered anechoic for frequencies above 230 Hz and semi-anechoic for lower frequencies.
Marboe, R. C.; Fitzgerald, J. M.
Almond test body. [for microwave anechoic chambers
The invention is an almond shaped test body for use in measuring the performance characteristics of microwave anechoic chambers and for use as a support for components undergoing radar cross-section measurements. The novel aspect of this invention is its shape, which produces a large dynamic scattered field over large angular regions making the almond valuable for verifying the performance of microwave anechoic chambers. As a component mount, the almond exhibits a low return that does not perturb the measurement of the component and it simulates the backscatter characteristics of the component as if over an infinite ground plane.
Dominek, Allen K. (inventor); Wood, Richard M. (inventor); Gilreath, Melvin C. (inventor)
Anechoic Chamber Evaluation at 85 GHZ,
The anechoic chamber of the Telecommunications Laboratory of the Technical Research Center of Finland (12 x 12 x 17 m sup 3) was evaluated at the frequency of 85 GHz. The reflectivity level was measured by using the free space voltage standing wave ratio ...
A. Lehto J. Tuovinen H. Valmu A. Raeisaenen
Acoustic Qualification of an Anechoic Chamber.
The aim of the work was to determine the working space and frequency range limits of an anechoic sound chamber for accurate measurements of source sound power and directivity. This was achieved by following guidelines in British Standard 4196 and noting t...
D. J. Hendy
The ARL/FED Anechoic Chamber.
This report documents the design and acoustic characteristics of the Applied Research Laboratory Department anechoic chamber. It is located on the above-console deck of the Garfield Thomas Water Tunnel situated so as to allow its use in conjunction with t...
R. C. Marboe J. M. Fitzgerald
Modeling semi-anechoic electromagnetic measurement chambers
Previous studies developed a model to predict theoretically the low-frequency plane-wave reflection coefficient of an array of pyramid cone absorbers such as those used to line anechoic electromagnetic measurement chambers. The present authors apply this model in a geometrical optics approach to predict the electromagnetic field in a chamber lined with cone absorbers in the frequency range of 30-300 MHz.
Christopher L. Holloway; Edward F. Kuester
The ARL\\/FED anechoic chamber
This report documents the design and acoustic characteristics of the Applied Research Laboratory Department anechoic chamber. It is located on the above-console deck of the Garfield Thomas Water Tunnel situated so as to allow its use in conjunction with the Axial Flow Research Fan (AFRF). The internal free dimensions of the chamber are 2.74 x 3.05 x 1.98 meters (9
R. C. Marboe; J. M. Fitzgerald
Upgrade of foam equipped semi anechoic chambers to fully anechoic chambers by the use of ferrite tiles
Different standard boards are developing EMC standards that allow a fully anechoic chamber being used for radiated EMC testing. In this paper an investigation is done on foam equipped semi anechoic chambers, that do not fulfil the requirements to become accredited for EMC emission testing. Additional absorbers are mounted on the ground plane to change the chambers to fully anechoic
J. Haala; W. Wiesbeck
Simulation of the Field Uniformity of Anechoic Chamber
The absorber materials used in anechoic and semi-anechoic chambers and the field uniformity are described in this paper. The field uniformity of anechoic chamber is simulated with software HFSS 10.0, Ansoft. A low frequency model for absorber-arrays is obtained using the method of homogenization. The simulation result testifies the method is feasible.
Chen Jiakui; Wen Yinghong
Antenna diversity measurement system in anechoic chamber
This paper presents theoretical and experimental results to demonstrate the capabilities of an antenna-diversity measurement set-up installed in an anechoic chamber. A numerical model of the set-up has been developed and provides theoretical results on the accuracy and limitations of the system. Experimental tests have been performed with dipole antennas in space-diversity with good agreement with the simulations.
L. Dussopt; L. Descroix
Reflectivity level of radio anechoic chambers
A comparison between the antenna-pattern comparison technique and the free-space voltage standing-wave ratio technique for evaluating the reflectivity level of radio anechoic chambers is presented. Based on an analysis of the two techniques, it is pointed out which parameters influence the measured value of the reflectivity level. The comparison is illustrated with experimental results and it is explained why inconsistent
J. Appel-Hansen
Radiated immunity tests: reverberation chamber versus anechoic chamber results
This paper concerns the comparison between reverberation chamber (RC) and anechoic chamber (AC) measurements: In particular, the case of an immunity test is considered. A two-wire transmission line is adopted as a device under test (DUT), and the current induced on the line by the external field is monitored to construct a possible susceptibility profile. Both the averaged current over
Roberto De Leo; Valter Mariani Primiani
Anechoic chamber design using ray tracing and theory of images
A ray-tracing technique which was used to help find the best possible anechoic chamber design in the frequency range of 30 MHz to 300 MHz is discussed. The electromagnetic fields due to a source inside the chamber are calculated. The scattered field is compared to the free space field to calculate the performance of the anechoic chamber in free space.
M. K. Mansour; J. Jarem
Anechoic chamber in industrial plants. [construction materials and structural design
A light anechoic chamber for routine acoustical measurements in the machine building industry is reported. The outer housing of the chamber consists of modules cast in glass fiber reinforced polyester resin; the inner housing consists of pyramidal modules cut out of sound absorbing slates. The parameters of this anechoic chamber facilitate acoustical measurements according to ISO and CAEM recommendations.
Halpert, E.; Juncu, O.; Lorian, R.; Marfievici, D.; Mararu, I.
Rational comparison of field strength between semi-anechoic chamber and fully anechoic chamber
In this article the validation of a fully anechoic chamber adopted to perform an EMI compliance test is explored by conducting test and theoretical analysis, and a preferred limit which is correlated to the present limit based on OATS is provided.
Ruoting Chang
A low cost conversion of semi-anechoic chamber to fully-anechoic chamber for RF antenna measurements
The commonly use of semi-anechoic chambers (SAC) is for electromagnetic interference emission (EMI) measurements. This paper suggests a simple technique to extend the EMI chamber capability to a low-cost fully anechoic chamber (FAC) to characterize the antenna performance. The dimensions of the absorbing cones placed o the reflecting ground surface are based on the Fresnel's zone concept. The receiving antenna
C. Kinezos; Vichate Ungvichian
It is pointed out that whereas anechoic chambers have been improved, this is not true of their source antenna. The diagonal horn is seen as offering a high-performance alternative that can be of particular help in radar cross section (RCS) measurements. To approach the maximum RCS measurement accuracy that a given chamber with a particular radar-absorbent material (RAM) can achieve, the antenna pattern shape must compensate for the fact that the reflection suppression of the RAM degrades at wide angles from normal incidence. The electric field configuration in the aperture of a diagonal horn is shown as the superposition of two coexisting orthogonal TE(10) modes. The diagonal horn described here has an aperture size of 8 in. square and a radiating section flare angle of 21 deg.
Foti, S. J.; McGahey, D. D.
Anechoic chamber evaluation using the matrix pencil method
A new method for evaluation of an anechoic chamber using the matrix pencil method is presented. A signal measured between two antennas placed in an anechoic chamber is sliced into small frequency intervals and is processed using the matrix pencil method. In each interval, the measured signal is decomposed into its propagating-wave components, which correspond to a direct propagation between
B. Fourestie; Z. Altman; M. Kanda
TEM wave propagation in a parallel, four wire anechoic chamber enclosure
Propagation of a TEM wave in a four-wire anechoic chamber facility is considered. The electromagnetic fields of the four-wire system are given when anechoic chamber material is and is not present. The analysis of this problem is divided into two main parts: the first part analyzes how a TEM wire propagates in a four-wire system that is surrounded by four
John M. Jarem
Time-domain modeling, characterization, and measurements of anechoic and semi-anechoic electromagnetic test chambers
We present time-domain techniques for modeling, characterizing, and measuring anechoic and semi-anechoic chambers used for emission and immunity testing of digital devices. The finite difference time-domain (FDTD) approach is used to model and characterize these chambers. In the FDTD model presented here, we discuss methods used to eliminate the need to spatially resolve the fine detail of the absorbing structures;
Christopher L. Holloway; Paul M. McKenna; Roger A. Dalke; Rodney A. Perala; Charles L. Devor
Advanced design considerations of semi-anechoic chambers
Designing an efficient, user-friendly semi-anechoic chamber, while achieving the specified performance and controlling the project cost requires significant planning. Additionally, many choices now exist in regard to features and accessories available for the chamber. This paper provides an overview of chamber performance, design features, and techniques to assist the chamber design team during the planning stage for a new chamber.
Darryl P. Ray
Characteristics of an anechoic chamber for fan noise testing
Acoustical and mechanical design features of NASA Lewis Research Center's engine fan noise facility are described. Acoustic evaluation of the 1420-m (50,000-ft) chamber, which is lined with an array of stepped wedges, is described. Results from the evaluation in terms of cut-off frequency and non-anechoic areas near the walls are detailed. Fan models with 0.51-m (20-in) diameters are electrically driven to 20,600 rpm in either the inlet mode (drawing air from the chamber) or exhaust mode (discharging air into the chamber) to facilitate study of both fore and aft fan noise. Inlet noise characteristics of the first fan tested, the JT8D Refan, are discussed and compared to full-scale levels. Turbulence properties of the inlet flow and acoustic results are compared with and without a turbulence reducing screen over the fan inlet.
Wazyniak, J. A.; Shaw, L. M.; Essary, J. D.
An Anechoic Chamber with Blanket-Wedge Construction.
The performance of a small anechoic chamber of inexpensive construction is described. The chamber was built within another room, and acoustic absorption material was also mounted in the outer room. The room rests on a concrete slab which is supported on h...
G. E. Peterson G. A. Hellwarth H. K. Dunn
Numerical analysis and optimization of anechoic chambers for EMC testing
Anechoic chambers for EMC testing in the frequency range from 30 MHz to 1 GHz have to fulfil stringent requirements before they are accepted for standardized emission and immunity measurements. In Europe, these requirements will lead to the exclusion of about 90% of the existing and 50% of the new chambers from accreditation due to the formerly lower standards. This
Christian Bornkessel; Wemer Wiesbeck
View of antenna test activity in Anechoic Chamber, bldg 14
View of antenna test activity in the Anechoic Chamber, bldg 14, JSC. The chamber walls are completely covered with foam pyramids for absorbing stray radiation during spacecraft antenna radiation pattern tests. The subject, in a extravehicular mobility units (EMU) is perched atop the maneuverable tower lift, which is part of the test set up for lunar surface extravehicular activity (EVA) antenna studies.
Design and construction of a multipurpose wideband anechoic chamber
An electromagnetic anechoic chamber has been constructed at the Multimedia University. It is designed to operate over a very wide frequency range from 30 MHz through 18 GHz. It can be used for electromagnetic compatibility (EMC) tests, antenna measurements, radar cross section (RCS) measurements, testing RF transceivers, calibration of scatterometers, and other electromagnetic research experiments. The geometry of the chamber
B. K. Chung; H. T. Chuah
Electromagnetic field analysis of a four-wire anechoic chamber
The electromagnetic field characteristics and plane-wave generating ability of a parallel four-wire anechoic chamber which is to be operated in the VHF range is analyzed. The analysis considers three cases: the first is a four-wire chamber when only a thin layer of absorber material covers the chamber walls, the second is a four-wire chamber when only free space surrounds the
Acoustical and mechanical design features of NASA Lewis Research Center's engine fan noise facility are described. Acoustic evaluation of the chamber, which is lined with an array of stepped wedges, is described. Results from the evaluation in terms of cut-off frequency and non-anechoic areas near the walls are detailed. Fan models are electrically driven to 20,600 RPM in either the inlet mode or exhaust mode to facilitate study of both fore and aft fan noise. Inlet noise characteristics of the first fan tested are discussed and compared to full-scale levels. Turbulence properties of the inlet flow and acoustic results are compared with and without a turbulence reducing screen over the fan inlet.
Wuzyniak, J. A.; Shaw, L. M.; Essary, J. D.
Comparison of anechoic and reverberation chamber coupling data as a function of directivity pattern
This paper compares coupling data from an external field to an internal probe for anechoic and reverberation chamber tests as a function of the directivity pattern of a test article and the test conditions for both chambers. The investigation uses an extensive measurement data base from both anechoic and reverberation chambers. In an ideal anechoic chamber test, the test article
Gustav J. Freyer; M. G. Backstrom
A microwave anechoic chamber for radar-cross section measurement
A microwave anechoic chamber has been developed at the Department of Electrical Engineering, University of Malaya, for monostatic and bistatic radar-cross-section measurements. The structure of the chamber is a quarter-section geodesic dome, with a 12 foot radius, and raised three feet above the floor. An antenna railing system is installed inside the chamber. The antennas can be moved along the
B. K. Chung; H. T. Chuah; J. W. Bredow
Two Dimensional Finite Difference Time Domain Analysis of the Quiet Zone Fields of an Anechoic Chamber.
Prediction of anechoic chamber performance is a difficult problem. Electromagnetic anechoic chambers exist for a wide range of frequencies but are typically very large when measured in wavelengths. Three dimensional finite difference time domain (FDTD) mo...
D. A. Ryan R. J. Luebbers T. X. Nguyen K. S. Kunz D. J. Steich
Figure of merit for low frequency anechoic chambers based on absorber reflection coefficients
Return loss as a function of frequency and angle of incidence is studied to determine the effectiveness of the absorbing material used in an anechoic chamber. This alone is not enough to determine a figure of merit for an anechoic chamber or to compare the figure of merit for one anechoic chamber to that of another. While the information gained
R. R. DeLyser; C. L. Holloway; R. T. Johnk; A. R. Ondrejka; M. Kanda
Finite Element Analysis Of Wedges Used In Anechoic Chambers
Wedges are often used in lining the internal surfaces of the anechoic chambers. The design of these wedges has invariably been based on extensive experimentation. In this paper, a finite element model for predicting the reflection characteristics of a wedge in an impedance tube is proposed. This model is based on the bulk reaction concept, thus accounting for the wave
V. Easwaran; M. L. Munjal
Apparent distance of sounds recorded in echoic and anechoic chambers
With miniature microphones inserted into the external ear canals of a model and the sound source 90░ to left of midline, low-pass, and high-pass, broadband noise bursts were picked up and recorded on magnetic tape. The bursts were generated in 2 highly contrasting acoustic environments: an anechoic and an echoic chamber. The taped sounds were played back monaurally and binaurally
Robert A. Butler; Elena T. Levy; William D. Neff
Low-Frequency Model for Rectangular Semi-Anechoic Chambers
An efficient and accurate method to compute the electromagnetic field inside a rectangular semi-anechoic chamber from 30 to 100 MHz is provided. A modal analysis method is used to develop the homogeneous and inhomogeneous solution. They are then combined with a generalized circuital analysis to take into account the effect of the several layers of ferrite and dielectrics on the
I. M. Perez; L. Nuno; Fernando Daniel Quesada Pereira; Juan V. Balbastre Tejedor
Evaluation of 10 m semi-anechoic chamber characteristics
A 10 m semi-anechoic chamber constructed at Matsushita Communication Ind. Co., Ltd. in August 1997 was evaluated. It has wider space than conventional 10 m chambers. By securing nonreflecting object area required by CISPR16-1 at a whole EUT setting area on the 6 m diameter turntable, the influence of absorbers lining the walls could be suppressed in the frequency range
K. Osabe; T. Komatsuzaki
Comparison of electromagnetic absorber used in anechoic and semi-anechoic chambers for emissions and immunity testing of digital devices
The absorber used in anechoic and semi-anechoic chambers employed for emissions and immunity testing of digital devices is examined. Using reflectivities obtained by the method of homogenization, the advantages and disadvantages of urethane pyramids, twisted-pyramids, wedges, as well as ferrite tiles, ferrite grids, and ōhybridö combinations of urethanes and ferrites, are determined. General reflectivity guidelines are also presented for comparing
Christopher L. Holloway; Ronald R. DeLyser; Robert F. German; Paul McKenna; Motohisa Kanda
Evaluation of anechoic chamber characteristics using an optically driven imitated equipment
This report describes the characteristics of an anechoic chamber when imitated equipment under test (EUT) is used. Radiated emission measurements revealed that the use of optically driven EUT enhanced the repeatability of the measurement set compared to coaxial cable driven ones. Measured emission levels in the fully anechoic chamber are used to estimate those for the semi anechoic case. Estimated
T. Kawashima; J. C. Aquino; M. Tokuda
Evaluation of anechoic chamber characteristics using optically driven equipment under test
The characteristics of an anechoic chamber lined with a foamed ferrite that can be composed as fully and semi-anechoic is evaluated using optically driven equipment under test (EUT). Measurement of the radiated emission from the developed EUT are performed for both fully and semi-anechoic dispositions of the chamber. The difference between measured values of normalized site attenuation (NSA) for the
J. C. Aquino; T. Kawashima; M. Tokuda
Site attenuation characteristics of anechoic chamber using foamed ferrite as new absorbing material
The anechoic chamber built in the Kyushu Institute of Technology in 1998 can be configured as a semi-anechoic chamber as well as a fully anechoic one in the frequency range of from 30 MHz to 10 GHz, having a thickness of about 10 cm by using a foamed ferrite as the new absorbing material. The normalized site attenuation (NSA) of
M. Tokuda; K. Simada; H. Ishii
Reflectivity level of RF shielded anechoic chamber
The reflectivity level of an RF shielded rectangular chamber with a non-uniform absorber lining has been investigated using the geometrical optics approach. The excitation antennas considered are the Hertzian dipole, a halfwave dipole and a pyramidal horn. A simple model is employed for the reflectivity of the absorber lining for normal incidence
S. V. K. Shastry; S. K. Nagesh; D. Binu
A comparison of reverberation chamber and semi-anechoic chamber testing for automotive susceptibility
This paper describes a set of elementary measurements made to determine the level of correlation that may be expected between susceptibility testing in a reverberation chamber and in an anechoic chamber. The measurements are simple and well defined. A test object was placed in both chambers and illuminated with a test field of 75 V\\/m. The box was measured with
K. Slattery; J. Neal
Analysis and design of 4-wire antenna for anechoic chamber excitation
In order to illuminate a uniform field at a target area in an anechoic chamber over a wide frequency range, a 4-wire antenna is proposed. This antenna consists of two V-antennas spreading away from each other from the feed point. Antenna parameters are determined for a given dimension of the anechoic chamber. Numerical analysis shows that the 4-wire antenna has
Valdis V. Liepa; Changyul Cheon
Efficient detection of resonances in anechoic chambers using the matrix pencil method
In a previous paper we have presented a method for evaluating the performance of anechoic chambers by analyzing the S-parameters of a system comprising two antennas facing each other in an anechoic chamber using the matrix pencil method. In this work, we present an improvement of this resonance detection technique using only the transmission parameter S21. The propagating components of
BenoŅt Fourestiķ; Zwi Altman; Motohisa Kanda
Reflectivity measurements in anechoic chambers in the microwave to millimeter range
A voltage standing-wave ratio (VSWR) measurement method and ensuing reflectivity characteristics are presented for anechoic chambers in the range 1-76.5 GHz. The free space VSWR measurements are performed using a composite antenna technique. By making use of two different anechoic chambers, the dependency of the reflectivity characteristics upon direction in the horizontal plane and absorber's height is analyzed.
Hithoshi Togawa; Kennichi Hatakeyama; Kenji Yamauchi
Evaluation of applicability for semi-anechoic chamber as test site above 1 GHz
Free space condition is required of test site for EMI measurement above 1 GHz. The users of semi-anechoic chambers currently used below 1 GHz take notice of the applicability to use them above 1 GHz. We characterized conventional semi-anechoic chambers of 3 m and 10 m methods and investigated the requirements to realize free space condition, for example the requirement
Y. Hayashi; T. Shinozuka; K. Ishino; R. Sato
Conversion and Comparison of the Test Results in Fully and Semi-Anechoic Chamber
This paper illustrates the test method of the radiated emission in Semi-Anechoic Chamber (SAC), and the radiated power in Fully Anechoic Chamber (FAC) between 30 MHz and 1 GHz. The test results are conversed and compared by analysis, while the correction factors that influence the performance are given.
Zhou Yu; Tao Hongbo; Wang Wenjian; Li Shufang
Performance of A 90-Foot Quasi-Tapered Anechoic Chamber: 120 Mhz To 93 Ghz.
The performance of the ninety foot anechoic chamber at The Aerospace Corporation is summarized. This chamber is a quasi-taper design which tapers from a large rectangular test section to a smaller transmitting section. This design combines the attractive ...
R. B. Dybdal H. E. King J. L. Wong C. O. Yowell
Comparison of Ergodic Capacities From Wideband MIMO Antenna Measurements in Reverberation Chamber and Anechoic Chamber
It has previously been shown that ergodic mul- tiple-input-multiple-output (MIMO) capacity of a multiport antenna system can be conveniently determined from channel measurements in a reverberation chamber. In this letter, we compare such MIMO capacity results to results based on mea- surements in an anechoic chamber of the embedded far-field functions and efficiencies at all antenna ports. The comparison is
Xiaoming Chen; Per-Simon Kildal; Jan Carlsson; Jian Yang
Criteria for absorber's reflectivity lined in semi-anechoic chambers using ray-tracing technique
Semi-anechoic chambers are used for EMC measurement from 30 MHz to 1000 MHz. Criteria for absorber's reflectivity lined in semi-anechoic chambers are discussed based on a ray-tracing analysis. The absorber's reflectivity of -15 dB and -20 dB for normal incidence is sufficient to satisfy a standard in 3 m and 10 m measurement methods, respectively. The dimensions of the chamber
Y. Naito; H. Anzai; T. Yamazaki; T. Mizumoto
Remodeling a 10-meter semi-anechoic chamber - a case history
Remodeling a 10-meter semi-anechoic chamber is not necessarily a simple matter of removing the old style polyurethane pyramidal cones and attaching new ferrite and polystyrene (or polyurethane) based absorbing material. This paper describes the key experiences encountered during a recent refurbishment of a 10-meter semi-anechoic chamber. The construction issues encountered, various chamber upgrades and the final normalized site attenuation (NSA)
Study on anechoic chamber for EMI measurement. 2. Measurement and evaluation of chamber characteristics
For pt.1 see IEEE 1989 Int. Symp. on EMC, p.149-53 (1989). It is pointed out that site attenuation of a semi-anechoic chamber must be measured in the same manner as for an open-field test site. Absorbers generate strong reflections at some frequencies, necessitating swept frequency measurements. It is noted, however, that reliable reference values of site attenuation for wideband biconical
A. Maeda; K. Osabe
Numerical methodologies for optimizing and predicting the low frequency behavior of anechoic chambers.
This paper presents a description of the use of simplified numerical methodologies for the optimization of the low cut-off frequency of anechoic and hemi-anechoic chambers. The anechoic chamber is modeled as a cavity with proper surface impedance boundary conditions. First, the shape of the wedges is optimized by means of a minimization-based procedure of a finite element model of such elements in a "virtual" impedance tube for a plane wave field. An equivalent surface impedance of the wedges is determined from those data. An analytical procedure is then used to determine the complex reflection coefficient for spherical waves at oblique incidence. Finally, a complex image source approach is used to predict the sound field within the chamber. The methodology is applied to two anechoic chambers and the results are compared in terms of sound decay along fixed directions and surface pressure distributions. PMID:23862806
Bonfiglio, Paolo; Pompoli, Francesco
Analysis of semi-anechoic chamber using ray-tracing technique
A semi-anechoic chamber is known to be useful for EMC measurements in a frequency range from 30 MHz to 1000 MHz. The analysis using a ray-tracing technique is investigated to evaluate a normalized site attenuation in the semi-anechoic chamber which is used for EMC measurements in a 3 m or 10 m method. The validity of the analysis is verified
Hiroki Anzai; T. Kishimoto; T. Yamazaki; Y. Naito; T. Mizumoto
Maintain and validate radiated emissions measurements in a 10 meter semi-anechoic chamber
In this paper, the authors describe the methods and procedures used to maintain and validate a 10 meter semi-anechoic chamber used for radiated emissions measurements. Included are a list of monthly, semi-annual, annual, and as needed checks and an approach for measurement software\\/hardware validation. Finally, they discuss a method by which to verify that a semi-anechoic chamber's measurement system is
Patrick Rose; Michael Luvara
The New Anechoic Shielded Chambers Designed for Space and Commercial Applications at LIT
The main objective of this paper is to present the capabilities of the new anechoic shielded rooms designed for space and commercial applications as part of the Integration and Testing Laboratory (LIT, Laboratorio de Integracao e Testes) in Brazil. A new anechoic shielded room named CBA2 has been in full operation since March 2007 and a remodeled chamber CBA1 is planned to be ready by the end of 2008, replacing an old facility which was in operation for the last 18 years. The Brazilian Space Program started with very small and simple satellites and the old CBA1 chamber was conceived in 1987 to accomplish the EMI/EMC tests not requiring significant volumes. Since the very beginning this facility was also used by the private sector for other applications mainly due to the absorption of digital electronics in all kind of products. The intense use of this facility during the last years, operating three shifts a day, caused a normal degradation and imposed several limitations. Therefore, a new totally remodeled chamber was designed considering the state of the art in terms of absorbers and associated instrumentation. On the other hand the facility CBA2 was conceived, designed and implemented to test large satellites taking into account the advance of the technology in terms of RF frequencies, power level, testing methodologies and several other factors. A very interesting and unique aspect of this project was the partnership between the private sector and governmental institution. As a result, the total investment was shared between several companies and consequently a time-sharing use of the facility as well.
da Silva, Benjamim; Galvao, M. C.; Pereira, Clovis Solano
Ambient measurements in a semi-anechoic chamber
In order to develop the automotive system control modules required in modern vehicles, an engineering department must have access to test and measurement facilities. These facilities must deliver, in a timely manner, data that truly reflects the spectral characteristics of the modules submitted for test. For that to happen, the engineers in charge of the test chambers must have a
J. Neal; K. P. Slattery; S. V. Smith
Anechoic chamber qualification: Traverse method, inverse square law analysis method, and nature of test signal
Qualification of anechoic chambers is intended to demonstrate that the chamber supports the intended free-field environment within some permissible tolerance bounds. Key qualification issues include the method used to obtain traverse data, the analysis method for the data, and the use of pure tone or broadband noise as the chamber excitation signal. This paper evaluates the relative merits of continuous
Kenneth A. Cunefare; Van B. Biesel; John Tran; Ryan Rye; Aaron Graf; Mark Holdhusen; Anne-Marie Albanese
Comparison between radiation efficiencies of phone antennas and radiated power of mobile phones measured in anechoic chambers and reverberation chamber
Chalmers University and Bluetest AB have developed a reverberation chamber that can be used to measure radiation efficiency of phone antennas and the radiated power of mobile phones. This paper describes the verification of the reverberation chamber measurements by comparison with two anechoic chambers. The total radiated power of each of ten different mobile phone models was measured. In addition,
Nikolay Serafimov; Per-Simon Kildal; T. Bolin
Inlet noise on 0.5-meter-diameter NASA QF-1 fan as measured in an unmodified compressor aerodynamic test facility and in an anechoic chamber
Narrowband analysis revealed grossly similar sound pressure level spectra in each facility. Blade passing frequency (BPF) noise and multiple pure tone (MPT) noise were superimposed on a broadband (BB) base noise. From one-third octave bandwidth sound power analyses the BPF noise (harmonics combined), and the MPT noise (harmonics combined, excepting BPF's) agreed between facilities within 1.5 db or less over the range of speeds and flows tested. Detailed noise and aerodynamic performance is also presented.
Gelder, T. F.; Soltis, R. F.
Comparison of anechoic and reverberation chamber coupling data as a function of directivity pattern. II
This paper extends previous work on comparing data from anechoic and reverberation chamber tests. Since the test electromagnetic environment in the two techniques are different, one-to-one comparisons of equipment responses are difficult. Responses in both anechoic and reverberation tests depend on equipment directivity but in different ways. The expected results also have different dependencies on variations in test conditions (e.g.,
Gustav J. Freyer; Mats G. Backstrom
Anechoic chambers are used for both emission and immunity testing but the ferrite tiles used to line the inside of the chamber are extremely expensive.This paper describes a method of reducing the number of tiles, whilst ensuring a reliable test environment. In this paper, the ray-tracing method for waves propagation is used for evaluation of the reflectivity level of an
Sayed Mohammad Javad Razavi; Mohammad Khalaj-Amirhosseini
Optimisation guidelines for a partially lined semi-anechoic chamber using CEM
Electromagnetic interference measurements (EMI) for EMC qualification of products have to be made in normalized test sites such as an open area test site or a semi-anechoic chamber. Site validation is defined by European and international standards for the frequency range between 30 MHz and 1 GHz. Using Computational ElectroMagnetics (CEM), it is now possible to predict chamber performance. The
G. Dun; J.-F. Rosnarho; P. Gelin; F. Le Pennec
Numerical and experimental analysis of the field to enclosure coupling in reverberation chamber and comparison with anechoic chamber
This paper presents a study of coupling between an external field and a metallic enclosure with a long aperture in the frequency range which includes several box resonances. A reverberation chamber (RC) and an anechoic chamber (AC) are considered as a field generation structure. In both cases, a customized FDTD code is used to calculate the current induced by the
G. Gradoni; F. Moglie; A. P. Pastore; V. M. Primiani
Microwave field-to-wire coupling measurements in anechoic and reverberation chambers
Knowledge of the differences in radiated susceptibility (RS) testing in anechoic (AC) and reverberation chambers (RC) is essential for analysis of the susceptibility of electronic systems to microwave radiation. We have studied microwave field-to-wire coupling for some basic wire geometries above a ground plane in ACs and RC. Results for receiving parameters such as the antenna receiving cross section ?
Stefan Silfverski÷ld; Mats Bõckstr÷m; J÷rgen Lorķn
Experimental study on direction dependency of reflection coefficients of microwave electromagnetic anechoic chamber
For measurements of reflection coefficients in an anechoic chamber by the free-space voltage standing wave ratio (VSWR) method, the composite antenna technique, using a combination of two antennas, is proposed. Reliable data on reflection coefficients can be obtained by this technique, with respect to reflected waves from arbitrary directions. Using the measurement results, the direction dependency of reflection coefficients is
K. Hatakeyama; H. Togawa; T. Kawamura; Y. Sato
Effects of RF absorbers on measurements of small antennas in small anechoic chambers
In this work, the influence of resistive absorbers in the vicinity of small antennas was investigated, in order to define a lower limit for the size of a small anechoic chamber for antenna calibration and radiation pattern measurements, with respect to the distance between the antenna under test (AUT) and the RF absorbers lining the walls. Furthermore, the influence of
C. Icheln; J. Ollikainen; P. Vainikainen
Experimental evaluation of a SAGE algorithm for ultra wideband channel sounding in an anechoic chamber
The paper presents the results of experiments in an anechoic chamber that assessed the reliability of a UWB channel sounding system based on a deterministic approach with a SAGE algorithm. The system could resolve and detect waves separated by 10░ in the angle domain, which was near the resolution limit. In the delay domain, waves separated by 0.67 ns could
K. Haneda; J. I. Takada; T. Kobayashi
Reducing the computational domain for FDTD scattering simulation using the sawtooth anechoic chamber ABC
A novel absorbing boundary condition (ABC), to be used with finite difference electromagnetic scattering simulation is described. This new ABC is based on modeling lossy anechoic chamber foam pyramids as a lattice terminating layer. The advantage of this absorbing boundary is that it prevents reflections from much wider incident angles than most currently used techniques, yet is conceptually straightforward, simple
Carey M. Rappaport; Tolga Gurel
New imitated equipment with optical powering system for evaluating anechoic chamber characteristics
In order to evaluate the characteristics of an anechoic chamber, a new optically driven imitated equipment with optical powering system is developed. The optical powering system consists of high power laser diode, optical fiber and photovoltaic cells. This serves as the electric power source which does not use any metal cables and operates for a much longer period of time
Takahiro NANGO; T. Kawashina; Junichi OHWAKI; Masamitsu TOKUDA
Numerical modeling of a stripline antenna in a large semi-anechoic chamber
Stripline antennas are used for automotive immunity testing in semi-anechoic chambers at low frequencies (<30 MHz). In order to investigate the behavior of such devices, a numerical model of the radiating elements of such a system has been developed using a 3D field modeling technique (TLM). The field distribution beneath this structure has also been measured for comparison with the
Alastair R. Ruddle; David D. Ward; Simon C. Pomeroy
The ARL/FEU (Fluids Engineering Unit) Semi-Anechoic Chamber.
This memorandum documents the design and acoustic characteristics of the ARL/Fluids Engineering Unit semi-anechoic chamber. It is located on the first floor of the Garfield Thomas Water Tunnel and has internal dimensions of 11 x 12 x 8 feet. The sound abs...
G. C. Lauchle E. Wong
Conversion of radiated field strength at different distance in semi-anechoic chamber
The conversion of radiated field strength at different distance in semi-anechoic chamber is analyzed. Firstly, the empirical model based on the logarithmic distance path loss is introduced. Secondly, theoretical models of radiation field in the same site or the different site at different distance are obtained through calculating the difference of normalized site attenuation (NSA) with different transmit \\/ receive
Luo-quan Hu
Study of Semi-Anechoic Chamber Evaluation by Array Signal Processing
This research aims at evaluating the scattering waves intensity inside a RF semi-anechoic chamber and measure the spatial distribution of the eld by implementing SAGE (space-alternating generalized expectation-maximization) algorithm. Some theoretical analysis and an initial bemforming simulation necessary to process the real data from experiment will be described in this paper.
Karlisa Priandana; Jun-Ichi Takada; Masanobu Hirose; Satoru Kurokawa
A two dimensional finite difference time domain analysis of the quiet zone fields of an anechoic chamber
Prediction of anechoic chamber performance is a difficult problem. Electromagnetic anechoic chambers exist for a wide range of frequencies but are typically very large when measured in wavelengths. Three dimensional finite difference time domain (FDTD) modeling of anechoic chambers is possible with current computers but at frequencies lower than most chamber design frequencies. However, two dimensional FDTD (2D-FTD) modeling enables much greater detail at higher frequencies and offers significant insight into compact anechoic chamber design and performance. A major subsystem of an anechoic chamber for which computational electromagnetic analyses exist is the reflector. First, an analysis of the quiet zone fields of a low frequency anechoic chamber produced by a uniform source and a reflector in two dimensions using the FDTD method is presented. The 2D-FDTD results are compared with results from a three dimensional corrected physical optics calculation and show good agreement. Next, a directional source is substituted for the uniform radiator. Finally, a two dimensional anechoic chamber geometry, including absorbing materials, is considered, and the 2D-FDTD results for these geometries appear reasonable.
Ryan, Deirdre A.; Luebbers, Raymond J.; Nguyen, Truong X.; Kunz, Karl S.; Steich, David J.
In this paper, a site attenuation model for semi-anechoic chambers using ray-tracing technique is developed. The proposed model considers multi-re?ection rays, and allows the true radiation pattern of difierent antennas to be included. Thus, this model can be used in the site attenuation measurement prediction performed for all types of electromagnetic compatibility (EMC) antennas in various chambers. The efiect of
Comparison of Methods to Evaluate Semi-anechoic Chamber Performance Understanding how to evaluate a 3-m semi-anechoic chamber is critical for the adequate control of chamber performance
Procurement of a state-of-the-art 3-m semi-anechoic chamber requires a thorough understanding of the two methods commonly used to evaluate chamber performance. The first method compares chamber performance to a theoretical model that employs free-space antenna factors, and the second method directly compares a chamber to the measured performance of a near-ideal open area test site (OATS). Both of these methods
Reduction of fan noise in an anechoic chamber by reducing chamber wall induced inlet flow disturbances
The difference between the flight and ground static noise of turbofan engines presents a significant problem in engine noise testing. The additional noise for static testing has been attributed to inlet flow disturbances or turbulence interacting with the fan rotor. In an attempt to determine a possible source of inflow disturbances entering fans tested in the Lewis Research Center anechoic chamber, the inflow field was studied using potential flow analysis. These potential flow calculations indicated that there was substantial flow over the wall directly behind the fan inlet that could produce significant inflow disturbances. Fan noise tests were run with various extensions added to the fan inlet to move the inlet away from this backwall and thereby reduce the inlet flow disturbances. Significant noise reductions were observed with increased inlet length. Over 5 db reduction of the blade passage tone sound power level was observed between the shortest and longest inlets at 90% fan speed and the first overtone was reduced 9 db. High frequency broadband noise was also reduced.
Dittmar, J. H.; Mackinnon, M. J.; Woodward, R. P.
The difference between the flight and ground static noise of turbofan engines has been identified as a significant problem in engine noise testing. The additional noise for static testing has been attributed to inlet flow disturbances or turbulence interacting with the fan rotor. In an attempt to determine a possible source of inflow disturbances entering fans tested in the Lewis Research Center anechoic chamber the inflow field was studied using potential flow analysis. These potential flow calculations indicated that there was substantial flow over the wall directly behind the fan inlet that could produce significant inflow disturbances. Fan noise tests were run with various extensions added to the fan inlet to move the inlet away from this backwall and thereby reduce the inlet flow disturbances. Significant noise reductions were observed with increased inlet length. Over 5 dB reduction of the blade passage tone sound power level was observed between the shortest and longest inlets at 90% fan speed and the first overtone was reduced 9 dB. High frequency broadband noise was also reduced.
Management of EMC semi-anechoic facilities by an independent laboratory
In this paper, the management of EMC semi-anechoic facilities is discussed from the perspective of an independent laboratory. Successful management of semi-anechoic facilities by third-party test labs requires a strategy where they become the clear choice by clients over open area test sites. Cost versus performance is the criteria most clients use to select test facilities. To keep pricing competitive,
Greg Kiemel
Reflectivity level of double-bounce rays in rectangle anechoic chamber
The reflectivity level of double-bounce rays of a mini rectangular anechoic chamber with a uniform absorber lining has been investigated by using the geometrical optics approach. The influence of the reflectivity level of the double-bounce rays has been analyzed in Hertzian dipole excitation antennas as compared with that of single-reflection specular rays from the side walls including the ceiling and floor. The result shows that the effect of the double-bounce rays on the total reflectivity level is relatively unimportant and can be ignored at excitation frequency range from 500MHz to 8GHz for the chamber.
Liu, Rubing; Liu, Haitao; Chen, Zhigang; Lin, Qi
Wideband numerical modelling and performance optimisation of arbitrarily-shaped anechoic chambers via an unconditionally stable time-domain technique
A 3-D curvilinear alternating-direction implicit finite-difference time-domain (ADI-FDTD) algorithm for the broadband analysis and optimised design of anechoic and semi-anechoic chambers with arbitrary shape is presented in this paper. The unconditionally stable and frequency-dependent method develops a new family of spatial\\/temporal forms which reduce the critical dispersion errors of existing approaches and allow the precise performance evaluation of essential components
Nikolaos V. Kantartzis; Theodoros D. Tsiboukis
An open-boundary quad-ridged guide horn antenna for use as a source in antenna pattern measurement anechoic chambers
The present paper introduces a new antenna design to be used in anechoic chambers. When measuring three-dimensional patterns, the receiving antenna in the anechoic chamber must be able to sense the two orthogonal components of the field that exist in the far field. This can be accomplished by mechanically rotating the source horn in the chamber. A better and faster
Vicente Rodriguez
Radiated immunity testing of a device with an external wire: repeatability of reverberation chamber results and correlation with anechoic chamber results
We present the experimental radiated immunity results of an electronic device with an external wire obtained in reverberation and anechoic chambers. Repeatability and reproducibility of reverberation chamber measurements are investigated by repeating the test in three reverberation chambers with different characteristics. We show how the current state of the art allows a statistical control of RC measurement repeatability within an
L. Musso; F. Canavero; B. Demoulin; V. Berat
Different Results of Radiated Emissions in Fully and Semi-Anechoic Chamber due to Influence of EUTĒs Vertical Cables Termination
Influence of EUT's vertical cables termination in fully and semi-anechoic chamber has been investigated. Numerical calculation and experimental results are presented for end-driven wire model (EDW) of equipment under test (EUT) with one cable. The investigation shows comparable results in different type of chambers for EUTs with cables terminated with absorbing clamp
G. Kova; R. Lapuh
Acoustic noise caused by a.c. corona on conductors: Results of an experimental investigation in the anechoic chamber
The paper describes an experimental research performed in the anechoic chamber with the aim of investigating the qualitative and quantitative characteristics of the acoustic noise caused by a.c.corona on conductors. Conductors of different type and size, smooth and stranded, with and without surface treatment, were tested dry and wet within a large range of voltage gradients. On the basis of
M. Sforzini; R. Cortina; G. Sacerdote; R. Piazza
Applications of time-gating method to improve the measurement accuracy of antenna radiation inside an anechoic chamber
In order to increase the quiet zone space, reduce the multi-path interferences and increase the measurement accuracy in an existing anechoic chamber, a time gating method (TGM) is incorporated into the measurement system. The TGM transforms the frequency domain (FD) response into time domain (TD) using a Fourier transform and filters out the late time pulses, which are caused by
Yu-Ting Hsiao; Yo-Yi Lin; Yu-Cheng Lu; Hsi-Tseng Chou
Fading characterization in a semi-anechoic chamber with artificial scatterers for Mean Effective Gain measurements of wireless handheld terminals
This paper presents the methodology and corresponding analysis of the scattered field measurements in a semi- anechoic ferrite-lined chamber. The focus is on recreating a Rayleigh fading environment with realistic cross-polarization ratio (XPR) with the purpose of measuring the mean effective gain (MEG) of mobile handheld terminal operating in the 900 MHz GSM band. The emulated XPR was similar in
Andres Alayon Glazunov; Andreas F. Molisch; Fredrik Tufvesson
Filtering environmental reflections in far-field antenna measurement in semi-anechoic chambers by an adaptive pattern strategy
A method to perform antenna far-field measurements in semi-anechoic chamber is presented. The method requires the measurement of the amplitude and phase of the pattern of the antenna under test in different spatial positions. The data are elaborated to estimate the direction of arrival of the reflected signals and to synthesize a receiving pattern with s in these directions. Experimental
M. D. Migliore
ATS 6 EMI field measurements techniques and results. [anechoic chamber scale model testing
At the present time 'Applications Technology Satellite (ATS)-6' is the world's largest communication satellite. It handles telecommunications in the frequency range of 40 - 30,000 MHz. Power levels on board the spacecraft range from -110 dBm to 52.5 dBw. Consequently considerable care was required in the design and test of this spacecraft, in order to provide assurances that the spacecraft would perform properly in its own RF environments. The testing was performed first by placing the earth viewing module (EVM) in a specially constructed 'small' anechoic chamber with an overhead parabolic reflector section, of 8' in diameter, instead of the 30' reflector of the full scale design. The near field analysis of this paper proves that this test configuration leads to a desirable overtest for the spacecraft. The test requirements, procedure and results are also explained.
Afifi, M. S.; Keiser, B. E.
Specifying and procuring a 10 meter semi-anechoic EMC chamber
The procurement of a large EMC chamber is generally a major investment of resources for any firm desiring to own such a facility. Due to the large dollar amounts typically involved in such projects it becomes very important to develop a chamber specification that captures the full and complete technical description of the desired new chamber. Towards that goal this
M. Barron
Investigation on High Performance of 10m Semi Anechoic Chamber by using Open-Top Hollow Pyramidal Hybrid EM Wave Absorber
The emission radiated from electric and electronic equipments is evaluated through OATS. Recently, it is not fully prepared the environment for OATS because of a variety of communication radiation sources (e.g., digital television broadcast and cellular phone station). Therefore, the EM anechoic chambers are becoming more and more important as EMI test site. On the other hand, the EM anechoic
Hiroshi Kurihara; Toshifumi Saito; Yoshikazu Suzuki; Atsuhiro Nishikata; Osamu Hashimoto
Effect of inflow control on inlet noise of a cut-on fan. [in an anechoic chamber
The control of turbulence and other inflow disturbances in anechoic chambers for static turbofan noise studies was studied. A cut-on, high tip speed fan stage was acoustically tested with three configurations of an inflow control device in an anechoic chamber. Although this was a cut-on design, rotor inflow interaction appeared to be a much stronger source of blade passing tone radiated from the inlet than rotor stator interaction for the 1.6 mean rotor chord separation. Aft external suction applied to the area where the inflow control device joined the inlet produced a further reduction in blade passing tone, suggesting that disturbances in the forward flow on the outside of the inlet were superimposed on the inlet boundary layer and were a significant source of tone noise.
Woodward, R. P.; Glaser, F. W.
Realization of 3 m Semi Anechoic Chamber by Using Crossed-Wedge Shaped Hybrid EM Wave Absorber Consisting of Thin Corrugated Dielectric Lossy Sheet
This letter proposes a new hybrid EM wave absorber with the crossed-wedge shape, which can be applied to 3m semi anechoic chambers. In this study, we designed a new hybrid EM wave absorber with the crossed-wedge shape, which consisted of the inorganic and organic thin corrugated dielectric lossy sheet containing organic conductive fibers. Then the 3m semi anechoic chamber is
Toshifumi Saito; Yoshikazu Suzuki; Hiroshi Kurihara
Considerations about Radiated Emission Tests in Anechoic Chambers that do not fulfil the NSA Requirements
In this paper, some critical issues concerning the measurement of radiated emissions of products in an electromagnetic compatibility test stage are dealt with. In particular, an approach is proposed to evaluate the adequacy of anechoic enclosures that do not fulfil the requirements regarding the normalized site attenuation (NSA) factor. The purpose is to suggest a test method that can be
M. Borsero; A. Dalla Chiara; C. Pravato; A. Sona; M. Stellini; A. Zuccato
Accurate and continuous non-contact vital signs monitoring using phased array antennas in a clutter-free anechoic chamber.
Continuous and accurate monitoring of human vital signs is an important part of the healthcare industry, as it is the basic means by which the clinicians can determine the instantaneous status of their patients. Doppler-based noncontact vital signs (NCVS) sensor systems can monitor the heart and respiration rates without touching the patient, but it has been observed that that the accuracy of these NCVS sensors can be diminished by reflections from background clutters in the measurement environment, and that high directivity antennas can increase the sensing accuracy. Therefore, this work explores a NCVS sensor with continuous data taken inside an anechoic chamber where the background cluttering is negligible. In addition, a high directivity custom-made beam-steerable phased array antenna system is used to improve the performance and functionality of the 2.4GHz NCVS sensor we have built. We believe this work is the 1st systematic study using Doppler-based phased array systems for NCVS sensing performed in a clutter-free anechoic chamber. PMID:24110324
Boothby, A; Das, V; Lopez, J; Tsay, J; Nguyen, T; Banister, R E; Lie, D Y C
Calibration and Demonstration of the New Virginia Tech Anechoic Wind Tunnel
A unique new removable anechoic system and new acoustic treatment for the Virginia Tech Stability Wind Tunnel is described. The new system consists of a Kevlar-walled acoustic test section flanked by two anechoic chambers. In its new configuration the facility is closed aerodynamically and open acoustically, allowing far-field acoustic measurements with a flow quality comparable to that of a hard-
Marcel C. Remillieux; Erin D. Crede; Hugo E. Camargo; Ricardo A. Burdisso; William J. Devenport; Matthew Rasnick; Philip Van Seeters; Amanda Chou
Low frequency correlation of radiated emission measurements between a semi-anechoic chamber and an OATS or a weather protected sites
This paper documents the results of a measurement study to determine if low frequency radiated electric field emissions (10 kHz-30 MHz) and radiated magnetic field emissions (60 Hz-30 MHz) can be suitably measured in a 10 meter absorber lined (semi-anechoic) chamber.
C. E. Jones; D. Schramm
Measurements of the Induced Power in a Shape Shifting Transmission Line According to Immunity Tests in Reverberation and Semi Anechoic Chamber
Measurements of the induced power in a shape shifting transmission line are performed in the semi anechoic and reverberation chamber. The test setups are according to immunity tests. The device under test is a bar antenna, seen as transmission line, which is investigated for 3 geometric constellations. The differences between the measurement results in both test environments are pointed out.
Martin Obholz; Dirk Peier
Effectiveness of an inlet flow turbulence control device to simulate flight fan noise in an anechoic chamber
A hemispherical inlet flow control device was tested on a 50.8 cm. (20-inch) diameter fan stage in the NASA-Lewis Anechoic Chamber. The control device used honeycomb and wire mesh to reduce turbulence intensities entering the fan. Far field acoustic power level results showed about a 5 dB reduction in blade passing tone and about 10 dB reduction in multiple pure tone sound power at 90% design fan speed with the inlet device in place. Hot film cross probes were inserted in the inlet to obtain data for two components of the turbulence at 65 and 90% design fan speed. Without the flow control device the axial intensities were below 1.0%, while the circumferential intensities were almost twice this value. The inflow control device significantly reduced the circumferential turbulence intensities and also reduced the axial length scale.
Woodward, R. P.; Wazyniak, J. A.; Shaw, L. M.; Mackinnon, M. J.
Effectiveness of an inlet flow turbulence control device to simulate flight noise fan in an anechoic chamber
A hemispherical inlet flow control device was tested on a 50.8 cm. (20-inch) diameter fan stage in the NASA-Lewis anechoic chamber. The control device used honeycomb and wire mesh to reduce turbulence intensities entering the fan. Far field acoustic power level results show about a 5 db reduction in blade passing tone and about 10 dB reduction in multiple pure tone sound power at 90% design fan speed with the inlet device in place. Hot film cross probes were inserted in the inlet to obtain data for two components of the turbulence at 65 and 90% design fan speed. Without the flow control device, the axial intensities were below 1.0%, while the circumferential intensities were almost twice this value. The inflow control device significantly reduced the circumferential turbulence intensities and also reduced the axial length scale.
National Ignition Facility Target Chamber
On June 11, 1999 the Department of Energy dedicated the single largest piece of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. The ten (10) meter diameter aluminum target high vacuum chamber will serve as the working end of the largest laser in the world. The output of 192 laser beams will converge at
R W Wavrik; J R Cox; P J Fleming
Improved fire resistant radio frequency anechoic materials
Protective, flameproof foam covering improves the resistance to fire and surface contamination of low-cost radio frequency absorbing and shielding anechoic materials. This promotes safety of operating personnel and equipment being tested in an otherwise combustible anechoic chamber.
Robinson, D. A.
This letter proposes a new hybrid EM wave absorber with the crossed-wedge shape, which can be applied to 3m semi anechoic chambers. In this study, we designed a new hybrid EM wave absorber with the crossed-wedge shape, which consisted of the inorganic and organic thin corrugated dielectric lossy sheet containing organic conductive fibers. Then the 3m semi anechoic chamber is constructed in the size of 9.0m ū 6.0m ū 5.7m (L ū W ū H) using these absorbers, and also the normalized site attenuation (NSA) is measured according to ANSI C63.4 in the frequency range of 30MHz to 1GHz. As a result, the measured NSA is obtained within ▒3dB of the theoretical one.
Saito, Toshifumi; Suzuki, Yoshikazu; Kurihara, Hiroshi
Analysis of synthetic cylindrical array beam-forming in presence of the elements position-error for semi-anechoic chamber evaluation
This paper describes the study of synthetic cylindrical array beam-forming for narrowband signals, under the influence of antenna elements position-error. The required side-lobe level and the physical dimensions of the array are presumed based on the requirements and limitations to evaluate a RF semi-anechoic chamber. Dolph-Chebyshev algorithm is used for beam-forming because of its optimal beam-width for a predefined uniform
K. Priandana; M. Ghorashi; J.-I. Takada; M. Ameya; S. Kurokawa; M. Hirose
Directivity of equipment and its effect on testing in mode-stirred and anechoic chamber
If radiated susceptibility testing in a mode-stirred chamber (MSC) is used to test equipment that in its real operation may become irradiated by plane waves it is necessary to increase the test level, i.e. add a margin. In order to find out typical magnitudes of this margin coupling measurements to the interior of several objects have been carried out both
Leif Jansson; Mats Backstrom
Comparison of correlation algorithms between GTEM cell and semi anechoic chamber
The main purpose of GTEM cell as an alternative facility for EMC compliance testing is to accurately measure the radiated emission generated from an equipment-under-test (EUT). The open area test site (OATS) is the standard test facility for radiated emission measurements, thus the GTEM cell data have to be correlated to the OATS results. The correlation algorithms between GTEM cell
Jong-Hwa Kwon; Hyun Ho Park; Ae-Kyoung Lee; Hyung-Do Choi
Supervised Self-Organizing Classification of Superresolution ISAR Images: An Anechoic Chamber Experiment
The problem of the automatic classification of superresolution ISAR images is addressed in the paper. We describe an ane- choic chamber experiment involving ten-scale-reduced aircraft models. The radar images of these targets are reconstructed using MUSIC-2D (multiple signal classification) method coupled with two additional processing steps: phase unwrapping and symme- try enhancement. A feature vector is then proposed including Fourier
Emanuel Radoi; Andr ┤ e Quinquis; Felix Totir
STRIDE's 3 meters EMC semi-anechoic chamber design considerations and compliance to standards
This paper discuss the design considerations of a semianechoic chamber (SAC) for Science and Technology Research Institute for Defense's (STRIDE) to cater for electromagnetic compatibility (EMC) measurements in compliance to military and commercial standards. The SAC size is limited to the available space at STRIDE premise of 13.8 meters length, 5.88 meters width and 6.9 meters height. Similarly the size
A. F. A. Ghafar; M. R. M. Yassin; W. S. W. Hassan
Airframe noise measurements on a small-scale model of a supersonic transport concept in an anechoic flow facility
Airframe noise has been measured on a .015 scale model of an advanced supersonic transport concept (AST-100) in an anechoic flow facility. The model was equipped with leading- and trailing-edge flaps, nose and main landing gears, and engine nacelles. Each of these components was deployed, individually and collectively, to determine their contribution to the noise field. Results are presented which show that in the clean configuration the aircraft displays a symmetric dipole directivity, whereas in the more complex landing-approach configuration the directivity peaks in the forward quadrant. It was found that the landing-approach noise was due chiefly to the landing gear, the trailing edge flaps, and the aeroacoustic interaction between the two
Preisser, J. S.
Three dimensional model based on image theory for low frequency correction factors evaluation in semi-anechoic chambers
The need to study the radiated emissions from electric and electronic devices whose main energy content is below 50 MHz calls for the prediction of correction factors that allows one to correlate the direct electromagnetic field radiated by the device to the total measured field inside a test chamber due to the reflections on all the chamber's walls. A three-dimensional
G. Antonini; A. Orlandi
X-43A Undergoing Controlled Radio Frequency Testing in the Benefield Anechoic Facility at Edwards Ai
The X-43A Hypersonic Experimental (Hyper-X) Vehicle hangs suspended in the cavernous Benefield Aenechoic Facility at Edwards Air Force Base during radio frequency tests in January 2000. Hyper-X, the flight vehicle for which is designated as X-43A, is an experimental flight-research program seeking to demonstrate airframe-integrated, 'air-breathing' engine technologies that promise to increase payload capacity for future vehicles, including hypersonic aircraft (faster than Mach 5) and reusable space launchers. This multiyear program is currently underway at NASA Dryden Flight Research Center, Edwards, California. The Hyper-X schedule calls for its first flight later this year (2000). Hyper-X is a joint program, with Dryden sharing responsibility with NASA's Langley Research Center, Hampton, Virginia. Dryden's primary role is to fly three unpiloted X-43A research vehicles to validate engine technologies and hypersonic design tools as well as the hypersonic test facility at Langley. Langley manages the program and leads the technology development effort. The Hyper-X Program seeks to significantly expand the speed boundaries of air-breathing propulsion by being the first aircraft to demonstrate an airframe-integrated, scramjet-powered free flight. Scramjets (supersonic-combustion ramjets) are ramjet engines in which the airflow through the whole engine remains supersonic. Scramjet technology is challenging because only limited testing can be performed in ground facilities. Long duration, full-scale testing requires flight research. Scramjet engines are air-breathing, capturing their oxygen from the atmosphere. Current spacecraft, such as the Space Shuttle, are rocket powered, so they must carry both fuel and oxygen for propulsion. Scramjet technology-based vehicles need to carry only fuel. By eliminating the need to carry oxygen, future hypersonic vehicles will be able to carry heavier payloads. Another unique aspect of the X-43A vehicle is the airframe integration. The body of the vehicle itself forms critical elements of the engine. The forebody acts as part of the intake for airflow and the aft section serves as the nozzle. The X-43A vehicles were manufactured by Micro Craft, Inc., Tullahoma, Tennessee. Orbital Sciences Corporation, Chandler, Arizona, built the Pegasus rocket booster used to launch the X-43 vehicles. For the Dryden research flights, the Pegasus rocket booster and attached X-43 will be air launched by Dryden's B-52 'Mothership.' After release from the B-52, the booster will accelerate the X-43A vehicle to the established test conditions (Mach 7 to 10) at an altitude of approximately 100,000 feet where the X-43 will separate from the booster and fly under its own power and preprogrammed control.
The trials and tribulations of building a modern EMC facility
A modern EMC facility featuring a 10-meter semi-anechoic chamber can be designed to be versatile, user friendly and feature rich. The design task is made easier given the history of numerous 10-meter semi-anechoic chambers successfully meeting the specified normalized site attenuation (NSA) performance requirements. Thus the EMC engineers can shift their primary focus from concerns of the chamber performance to
D. P. Ray; J. Green
Binaural Simulation Experiments in the NASA Langley Structural Acoustics Loads and Transmission Facility.
A location and positioning system was developed and implemented in the anechoic chamber of the Structural Acoustics Loads and Transmission (SALT) facility to accurately determine the coordinates of points in three-dimensional space. Transfer functions wer...
F. W. Grosveld
Better RCS data with anechoic absober characterization
An adequate understanding of the performance of the absorber material is critical in achieving optimum performance levels of compact ranges or conventional anechoic chambers. The conventional testing technique, the NLR arch method, used for the free-space testing of absorbers is first reviewed, and its flaws are examined. Consideration is then given to new measurement techniques that eliminate the problems of
Steve Brumley
Calibration of fully anechoic rooms and correlation with OATS measurements
Fully anechoic rooms may gradually replace open area test sites as the preferred type of testing facility for the measurement of radiated emissions. The fully anechoic room offers several advantages over the open area test site. Immunity to high ambient signal levels, the capability of being located in metropolitan areas close to the customer base, more uniform field over a
R. A. McConnell; C. Vitek
Target area chamber system design for the National Ignition Facility
The National Ignition Facility (NIF) is a proposed Department of Energy facility which will contribute to the resolution of important Defense Program and inertial fusion energy issues for energy production in the future. The NIF will consist of a laser system with 192 independent beamlets transported to a target chamber. The target chamber is a multipurpose structure that provides the interface between the target and the laser optics. The chamber must be capable of achieving moderate vacuum levels in reasonable times; it must remain dimensionally stable within micron tolerances, provide support for the optics, diagnostics, and target positioner; it must minimize the debris from the x ray and laser light environments; and it must be capable of supporting external neutron shielding. The chamber must also be fabricated from a low activation material. The fusion reaction in the target gives off neutrons, x rays, and gamma rays. The x rays and gamma rays interact with the interior of the target chamber wall while neutrons penetrate the wall. In order to minimize the neutron activation of components outside the target chamber and to absorb gammas emitted from the activated chamber, shielding will be placed immediately outside the chamber. The target chamber contains the target positioner. The target positioner moves the target from outside the chamber to the center of the chamber and positions the target at the focal spot of the laser beams. The target positioner must be survivable in a harsh radioactive environment. The materials used must be low activation and have a high stiffness to weight ratio to maintain target stability. This paper describes the conceptual design of the target chamber, target positioner, and shielding for the NIF.
Wavrik, R.; Boyes, J.; Olson, C.; Dempsey, F.; Garcia, R.; Karpenko, V.; Anderson, A.; Tobin, M.; Latkowski, J.
SciTech Connect
The National Ignition Facility (NIF) is a proposed Department of Energy facility which will contribute to the resolution of important Defense Program and inertial fusion energy issues for energy production in the future. The NIF will consist of a laser system with 192 independent beamlets transported to a target chamber. The target chamber is a multi-purpose structure that provides the interface between the target and the laser optics. The chamber must be capable of achieving moderate vacuum levels in reasonable times; it must remain dimensionally stable within micron tolerances, provide support for the optics, diagnostics, and target positioner; it must minimize the debris from the x-ray and laser light environments; and it must be capable of supporting external neutron shielding. The chamber must also be fabricated from a low activation material. The fusion reaction in the target gives off neutrons, x-ray and gamma rays. The x-rays and gamma rays interact with the interior of the target chamber wall while neutrons penetrate the wall. In order to minimize the neutron activation of components outside the target chamber and to absorb gammas emitted from the activated chamber, shielding will be placed immediately outside the chamber. The target chamber contains the target positioner. The target positioner moves the target from outside the chamber to the center of the chamber and positions the target at the focal spot of the laser beams. The target positioner must be survivable in a harsh radioactive environment. The materials used must be low activation and have a high stiffness to weight ratio to maintain target stability. This paper describes the conceptual design of the target chamber, target postioner, and shielding for the NIF.
Wavrik, R.; Boyes, J.; Olson, C.; Dempsey, F.; Garcia, R. [Sandia National Labs., Albuquerque, NM (United States); Karpenko, V.; Anderson, A.; Tobin, M.; Latkowski, J. [Lawrence Livermore National Lab., CA (United States)
Design, construction and performance of a small, low cost anechoic measuring system for research applications
A low cost anechoic measuring system has been designed, constructed and evaluated. It consists of a small anechoic chamber, designed specifically for measurements of high performance feed horns within the range 18-30 GHz, and a simple antenna positioner. The chamber features hinged sides to ease relocation and improve access and is characterised by a simple aid low cost design in
D. Green; D. Smith
Radiated emissions conversion from anechoic environment to OATS using a hybrid genetic algorithm-gradient method
A novel method for predicting the equivalent OATS radiated emissions of a DUT from anechoic chamber measurements is presented. This method allows the use of a single environment (the anechoic chamber) for both radiated emissions and immunity tests. It is based on the substitution of the DUT by an equivalent set of elemental dipoles (using a hybrid genetic algorithm-gradient method)
J.-R. Regue; M. Ribo; Josep-Maria Garrell
This paper addresses EMI (ElectroMagnetic Interference) chamber performance in the frequency range between 30 and 200MHz, which is where chambers exhibit their deficiencies. The difference between attenuation in an open area test site (OATS), called Normalized Site Attenuation (NSA) and this same measure in the test chamber gives the performances. The European EN50147-2 (1) and American ANSI C63-4 standards (2)
LEST-ENST Bretagne
Conversion of semi to fully anechoic rooms per CENELEC prEN50147-3
Many small to medium sized EMC anechoic chambers today are built as fully-anechoic rooms (FAR). The current draft prEN50147-3 standard by CENELEC TC210A\\/WG4 defines FAR validation and product measurement methods. The feasibility of converting a standard full-sized 3 m semi-anechoic room (SAR) to a compliant FAR is examined in this paper
M. A. K. Wiles; W. Mullner
A comparison of methods and results using the semi-anechoic and reverberation chamber radiated RF susceptibility test procedures in RTCA\\/DO160D, Change One
RTCA\\/DO-160D, Environmental Conditions and Test Procedures for Airborne Equipment, defines a series of minimum standard environmental and electromagnetic compatibility test conditions (categories) and applicable laboratory test procedures for airborne equipment. Change One, issued in December, 2000, includes a complete revision of Section 20- Radio Frequency Susceptibility (Radiated and Conducted), which contains two different radiated RF susceptibility test procedures: reverberation chamber
E. J. Borgstrom
Design and engineering of a large shielded semi-anechoic chamber meeting the volumetric NSA requirements at 3 and 10 m transmission length
A large shielded semianechoic chamber meeting the validation requirements for alternative test sites as specified in ANSI C63.4-1991 (and equivalent CISPR and EN drafts) has been realized at the CESI EMC Laboratory, Milan, Italy. The authors discuss the problems of integration in a preexisting building of the semianechoic performance with all the hardware that makes the site practically useable, such
B. Audone; L. Bolla; G. Costa; A. Manara; H. Pues
Theoretical procedure to convert anechoic radiated emission measurements to OATS equivalent results for arbitrary radiators
In the last years, there has been certain interest in unifying installations for radiated immunity tests (which require a completely anechoic environment) and radiated emission tests (OATS). The possibility of making radiated emission tests in completely anechoic chambers has been suggested. Such a possibility poses the problem of obtaining equivalent results with the new system to those obtained with the
J. Carpio; J. C. Molina; R. Guirado
EMC test facilities at UME
In this work, we present electromagnetic compatibility (EMC) facilities at National Metrology Institute (UME) in Turkey. At UME for EMC test and measurements, 10 meter open area test site (OATS), 10 meter anechoic chamber and four screened rooms were constructed. OATS with a normalized site attenuation (NSA) value less than ▒1 dB is used for antenna calibration and radiated emission
R. Hamid; M. Cetintas; H. Karacadag
Electromagnetic Radiation (EMR) coupling to complex systems : aperture coupling into canonical cavities in reverberant and anechoic environments and model validation.
Mode-stirred chamber and anechoic chamber measurements were made on two sets of canonical test objects (cylindrical and rectangular) with varying numbers of thin slot apertures. The shielding effectiveness was compared to determine the level of correction needed to compensate the mode-stirred data to levels commensurate with anechoic data from the same test object.
Charley, Dawna R.; Higgins, Matthew B.
Perceived Noisiness under Anechoic, Semi-Reverberant and Earphone Listening Conditions.
Magnitude estimates by each of 31 listeners were obtained for a variety of noise sources under three methods of stimuli presentation: loudspeaker presentation in an anechoic chamber, loudspeaker presentation in a normal semi-reverberant room, and earphone...
F. R. Clarke K. D. Kryter
Scale model helicopter antenna pattern measurements at ASU's EMAC Facility
The ElectroMagnetic Anechoic Chamber (EMAC) facility has been in operation at Arizona State University (ASU) since 1988. In addition to providing experimental verification for theoretical prediction of radiation and scattering targets, this multi-purpose facility acts as a testbed for a unique, semicompact antenna test range. Antenna patterns of a scale model helicopter have been measured at 500 MHz and compared
C. R. Birtcher; W. Sun; C. A. Balanis; G. C. Barber
Meeting the NSA Requirement for CISPR 16-1-4 in a MIL-STD-461E Type Semi Anechoic Room
The radiated emissions measurements require different types of anechoic chambers for civil and military EMC standards. An anechoic chamber constructed according to the requirements of MIL-STD-46IE may not meet the requirements in CISPR 16-1-4. Instead of constructing a new semi anechoic room (SAR), an investigation on the possible use of a SAR originally constructed for MIL-STD-461E tests to perform the
F. Ustuner; C. Cosar; E. Demirel; A. Dagdeviren
GPS antenna characterization in an anechoic chamber
This paper is part of a continuing work with the FAA to develop an antenna testing methodology to characterize antenna performance in a multipath environment. This paper presents a case study to determine the characterization of two GPS antennas of varying performance in real world deployment. Power and phase measurements were acquired at the Wireless and Electromagnetic Compliance and Design
Nick J. LaSorte; Hazem H. Refai; John E. Fagan
Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow base line and suppressor nozzles. Summary report. [conducted in the Boeing large anechoic test chamber and the NASA-Ames 40by 80-foot wind tunnel
A test program was conducted in the Boeing large anechoic test chamber and the NASA-Ames 40- by 80-foot wind tunnel to study the near- and far-field jet noise characteristics of six baseline and suppressor nozzles. Static and wind-on noise source locations were determined. A technique for extrapolating near field jet noise measurements into the far field was established. It was determined if flight effects measured in the near field are the same as those in the far field. The flight effects on the jet noise levels of the baseline and suppressor nozzles were determined. Test models included a 15.24-cm round convergent nozzle, an annular nozzle with and without ejector, a 20-lobe nozzle with and without ejector, and a 57-tube nozzle with lined ejector. The static free-field test in the anechoic chamber covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K. The wind tunnel flight effects test repeated these nozzle test conditions with ambient velocities of 0 to 92 m/s.
Jaeck, C. L.
Measurement of Low-Gain Antennas in Non-Anechoic Test Sites through Wideband Channel Characterization and Echo Cancellation [Measurements Corner
The measurement of an antenna in a reverberant or semi-anechoic chamber, or even in an anechoic chamber with non-ideal absorbing material, will include the effects of multipath propagation, which will be evident in a distorted radiation pattern. In those situations, an improvement of the measurement can be achieved through removal or compensation of the undesired contributions. A simple technique to
S. Loredo; G. Leon; S. Zapatero; F. Las-Heras
A Facility for Long-Term Mars Simulation Experiments: The Mars Environmental Simulation Chamber (MESCH)
We describe the design, construction, and pilot operation of a Mars simulation facility comprised of a cryogenic environmental chamber, an atmospheric gas analyzer, and a xenon\\/mercury discharge source for UV generation. The Mars Environmental Simulation Chamber (MESCH) consists of a double-walled cylindrical chamber. The double wall provides a cooling mantle through which liquid N2 can be circulated. A load-lock system
Lars Liengaard Jensen; Jonathan Merrison; Aviaja Anna Hansen; Karina Aarup Mikkelsen; Tommy Kristoffersen; Per N°rnberg; Bente Aagaard Lomstein; Kai Finster
Evaluation of Gas-filled Ionization Chamber Method for Radon Measurement at Two Reference Facilities
For quality assurance, gas-filled ionization chamber method was tested at two reference facilities for radon calibration: EML (USA) and PTB (Germany). Consequently, the radon concentrations estimated by the ionization chamber method were in good agreement with the reference radon concentrations provided by EML as well as PTB.
Ishikawa, Tetsuo; Tokonami, Shinji; Kobayashi, Yosuke; Sorimachi, Atsuyuki; Yatabe, Yoshinori; Miyahara, Nobuyuki [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan)
Atmospheric chemistry of potential emissions from fuel conversion facilities. A smog chamber study. Final report
The atmospheric chemistry of chemical species that may be emitted from fuel conversion facilities were studied in smog chambers. Of 17 compounds assessed for ozone-forming potential, 6 compounds were selected along with a control species, propylene, for testing in the presence of nitrogen oxides in four outdoor smog chambers. Selected compounds were furan, pyrole, thiophene, methanethiol, methyl sulfide, and methyl
J. E. II Sickles; L. A. Ripperton; W. C. Eaton; R. S. Wright
Comparison between Two Outdoor Smog Chamber Facilities: Matched Experiments
While it is not prudent to make definitive statements based on such a small number of experiments, the data which have been presented support the belief that the 4 RTI and the 2 UNC outdoor smog chambers display very similar chemical behavior. It is likely that this is the result of their identical wall material and the similarity of the
Robert S. Wright; Richard M. Kamens; Joseph E. Sickles II; Harvey E. Jeffries; W. Cary Eaton
The Kevlar-walled anechoic wind tunnel
The aerodynamic and acoustic performance of an anechoic wind tunnel test section with walls made from thin Kevlar cloth have been measured and analyzed. The Kevlar test section offers some advantages over a conventional free-jet arrangement. The cloth contains the bulk of the flow but permits the transmission of sound with little loss. The containment results in smaller far-field aerodynamic corrections meaning that larger models can be tested at higher Reynolds numbers. The containment also eliminates the need for a jet catcher and allows for a much longer test section. Model-generated noise is thus more easily separated from facility background using beamforming. Measurements and analysis of acoustic and aerodynamic corrections for a Kevlar-walled test section are presented and discussed, along with benchmark trailing edge noise measurements.
Devenport, William J.; Burdisso, Ricardo A.; Borgoltz, Aurelien; Ravetta, Patricio A.; Barone, Matthew F.; Brown, Kenneth A.; Morton, Michael A.
Mode-Stirred Method Implementation for HIRF Susceptibility Testing and Results Comparison with Anechoic Method
This paper describes the implementation of mode-stirred method for susceptibility testing according to the current DO-160D standard. Test results on an Engine Data Processor using the implemented procedure and the comparisons with the standard anechoic test results are presented. The comparison experimentally shows that the susceptibility thresholds found in mode-stirred method are consistently higher than anechoic. This is consistent with the recent statistical analysis finding by NIST that the current calibration procedure overstates field strength by a fixed amount. Once the test results are adjusted for this value, the comparisons with the anechoic results are excellent. The results also show that test method has excellent chamber to chamber repeatability. Several areas for improvements to the current procedure are also identified and implemented.
Nguyen, Truong X.; Ely, Jay J.; Koppen, Sandra V.
An Absorbing Boundary Condition Based on Anechoic Absorber For EM Scattering Computation
A novel absorbing boundary condition (ABC), to be used with finite difference and finite element electromagnetic radiation and scattering problems is described. It is based on anechoic chamber absorber foam geometry, with specified complex permittivity and permeability. The advantage of this absorbing boundary is that it prevents reflections from much wider incident angles than currently used lattice termination conditions. Since
C. M. Rappaport; L. J. Bahrmasel
The crop growth research chamber: A ground-based facility for CELSS research
A ground based facility for the study of plant growth and development under stringently controlled environments is being developed by the Closed Ecological Life Support System (CELSS) program at the Ames Research Center. Several Crop Growth Research Chambers (CGRC) and laboratory support equipment provide the core of this facility. The CGRC is a closed (sealed) system with a separate recirculating atmosphere and nutrient delivery systems. The atmospheric environment, hydroponic environment, systems controls, and data acquisition are discussed.
Bubenheim, David L.
EPA Science Inventory
The atmospheric chemistry of chemical species that may be emitted from fuel conversion facilities were studied in smog chambers. Of 17 compounds assessed for ozone-forming potential, 6 compounds were selected along with a control species, propylene, for testing in the presence of...
Anechoic wind tunnel study of turbulence effects on wind turbine broadband noise
This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility
B. Loyd; W. L. Harris
Characterization of the Reverberation Chamber at the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility
In 2011 the noise generating capabilities in the reverberation chamber of the Structural Acoustic Loads and Transmission (SALT) facility at NASA Langley Research Center were enhanced with two fiberglass reinforced polyester resin exponential horns, each coupled to Wyle Acoustic Source WAS-3000 airstream modulators. This report describes the characterization of the reverberation chamber in terms of the background noise, diffusivity, sound pressure levels, the reverberation times and the related overall acoustic absorption in the empty chamber and with the acoustic horn(s) installed. The frequency range of interest includes the 80 Hz to 8000 Hz one-third octave bands. Reverberation time and sound pressure level measurements were conducted and standard deviations from the mean were computed. It was concluded that a diffuse field could be produced above the Schroeder frequency in the 400 Hz one-third octave band and higher for all applications. This frequency could be lowered by installing panel diffusers or moving vanes to improve the acoustic modal overlap in the chamber. In the 80 Hz to 400 Hz one-third octave bands a successful measurement will be dependent on the type of measurement, the test configuration, the source and microphone locations and the desired accuracy. It is recommended that qualification measurements endorsed in the International Standards be conducted for each particular application.
Grosveld, Ferdinand W.
A Concept for a Low Pressure Noble Gas Fill Intervention in the IFE Fusion Test Facility (FTF) Target Chamber
An engineering evaluation has been initiated to investigate conceptual engineering methods for implementing a viable gas shield strategy in the Fusion Test Facility (FTF) target chamber. The employment of a low pressure noble gas in the target chamber to thermalize energetic helium ions prior to interaction with the wall could dramatically increase the useful life of the first wall in
C. A. Gentile; W. R. Blanchard; T. A. Kozub; M. Aristova; C. McGahan; S. Natta; K. Pagdon; J. Zelenty
A Large Hemi-Anechoic Enclosure for Community-Compatible Aeroacoustic Testing of Aircraft Propulsion Systems
A large hemi-anechoic (absorptive walls and acoustically hard floor) noise control enclosure has been erected around a complex of test stands at the NASA Lewis Research Center in Cleveland, Ohio. This new state-of-the-art Aeroacoustic Propulsion Laboratory (APL) provides an all-weather, semisecure test environment while limiting noise to acceptable levels in surrounding residential neighborhoods. The 39.6 m (130 ft) diameter geodesic dome structure houses the new Nozzle Aeroacoustic Test Rig (NATR), an ejector-powered M = 0.3 free jet facility for acoustic testing of supersonic aircraft exhaust nozzles and turbomachinery. A multi-axis, force-measuring Powered Lift Facility (PLF) stand for testing of Short Takeoff Vertical Landing (STOVL) vehicles is also located within the dome. The design of the Aeroacoustic Propulsion Laboratory efficiently accomodates the research functions of two separate test rigs, one of which (NATR) requires a specialized environment for taking acoustic measurements. Absorptive fiberglass wedge treatment on the interior surface of the dome provides a hemi-anechoic interior environment for obtaining the accurate acoustic measurements required to meet research program goals. The APL is the first known geodesic dome structure to incorporate transmission-loss properties as well as interior absorption into a free-standing, community-compatible, hemi-anechoic test facility.
Cooper, Beth A.
Electromagnetic radiation test facilities evaluation of reverberation chambers located at NSWC (Naval Surface Weapons Center), Dahlgren, Virginia
The facilities were developed for use in measuring and analyzing the electromagnetic susceptibility/vulnerability (EMS/V) of weapon systems and the shielding effectiveness of enclosures and shielding materials. A brief description of each facility is given including the instrumentation used for performing the evaluation and calibration of the facilities by the National Bureau of Standards (NBS). Conclusions given indicate that the Naval Surface Weapons Center (NSWC) chambers can be used at frequencies down to approximately 150 MHz. Estimates are given of the measurement uncertainties derived empirically from the test results.
Crawford, M. L.; Koepke, G. H.
Prompt doses from x-rays generated as result of laser beam interaction with target material are calculated at different locations inside the National Ignition Facility (NIF). The maximum dose outside a Target Chamber diagnostic port is {approx} 1 rem for a shot utilizing the 192 laser beams and 1.8 MJ of laser energy. The dose during a single bundle shot (8 laser beams) drops to {approx} 40 mrem. Doses calculated outside the Target Bay doors and inside the Switchyards (except for the 17 ft.-6 in. level) range from a fraction of mrem to about 11 mrem for 192 beams, and scales down proportionally with smaller number of beams. At the 17ft.-6 in. level, two diagnostic ports are directly facing two of the Target Bay doors and the maximum doses outside the doors are 51 and 15.5 mrem, respectively. Shielding each of the two Target Bay doors with 1/4 in. Pb reduces the dose by factor of fifty. One or two bundle shots (8 to 16 laser beams) present a small hazard to personnel in the Switchyards.
Khater, H Y; Brereton, S J; Singh, M S
Anechoic aquarium for ultrasonic neural telemetry.
PubMed Central
An acoustic neural telemetry tag has been developed for recording from free-swimming aquatic animals. Microwire electrodes were implanted into the VIIIth nerve of the toadfish, Opsanus tau, and interfaced to the subdermally implanted tag. The telemetry tag frequency modulates the neural signal, converting it into a varying frequency, which is amplified and transmitted acoustically (centre frequency of 90 kHz and a 20 kHz bandwidth). This acoustic signal is detected by a receiver hydrophone, and the receiver reconstructs the full neural waveform from the acoustic signal. However, due to the multipath environment in the experimental aquarium, the acoustic signal is quickly degraded as the hydrophone is moved away from the source. In order to receive the signal independent of fish position, an anechoic aquarium was designed. Streams of microbubbles (ca. 70 microm diameter) were generated to produce a curtain of sound-absorptive material along the walls and water surface of the aquarium. Microbubble generation significantly reduced the multipath artefacts, and allowed signal discrimination independent of fish and hydrophone position. The anechoic aquarium will allow the recording of neural activity from free-swimming fishes in quasi-natural habitats, thus allowing better understanding of the neural mechanisms of behaviour.
Mensinger, A F; Deffenbaugh, M
University of Missouri-Rolla cloud simulation facility - Proto II chamber
The design and supporting systems for the cooled-wall expansion cloud chamber, designated Proto II, are described. The chamber is a 10-sided vertical cylinder designed to be operated with interior wall temperatures between +40 and -40 C, and is to be utilized to study microphysical processes active in atmospheric clouds and fogs. Temperatures are measured using transistor thermometers which have a range of + or - 50 C and a resolution of about + or - 0.001 C; and pressures are measured in the chamber by a differential strain gauge pressure transducer. The methods used for temperature and pressure control are discussed. Consideration is given to the chamber windows, optical table, photographic/video, optical attenuation, Mie scattering, and the scanning system for the chamber. The system's minicomputer and humidifier, sample preparation, and chamber flushing are examined.
White, Daniel R.; Carstens, John C.; Hagen, Donald E.; Schmitt, John L.; Kassner, James L.
Design features for free-field qualification of a new semi-anechoic room, and qualification performance
Precision qualification of a semi-anechoic room requires careful attention to the sound source and traversing method. Prior work, with test sources mounted above the reflecting floor of such a room, has indicated the potential for image source problems in the resulting field. To address such shortcomings, the new Georgia Tech semi-anechoic room was constructed with a recessed enclosure in the center of the floor. This enclosure permits the implementation of test sources coincident with the reflecting plane of the floor. In addition, prior work in an anechoic room has indicated the inadequacy of qualification traverses implemented at large spacings. To address this issue, hard-points were designed and implemented within the room to permit installation of traverse cables extending radially from the in-floor source enclosure out to the walls and corners. These traverse cables are an integral component of a custom continuous traverse system. The design features of the chamber which facilitate chamber qualification will be presented, along with the broadband and pure tone results of the qualification performed on the chamber.
Cunefare, Kenneth A.; Biesel, Van; Holdhusen, Mark; Shoemaker, Austin
Management of unconverted light for the National Ignition Facility target chamber
The NIF target chamber beam dumps must survive high x-ray, laser, ion, and shrapnel exposures without excessive generation of vapors or particulate that will contaminate the final optics debris shields, thereby making the debris shields susceptible to subsequent laser damage. The beam dumps also must be compatible with attaining and maintaining the required target chamber vacuum and must not activate
A. T. Anderson; K. Bletzer; A. K. Burnham; S Dixit; F. Y. Genin; W. Hibbard; J. Norton; J. M. Scott; P. K. Whitman
Pamela A. Whitman; A. K. Burnham; Mary A. Norton; Francois Y. Genin; J. M. Scott; Wilthea J. Hibbard; K. Bletzer; Andrew T. Anderson; Sham N. Dixit
Evaluation of Radiated Transfer Functions of a Fuselage Model in an Anechoic and in a Reverberating Radio Frequency Environment
In an anechoic chamber and in a reverberation chamber Radio Frequency (RF) fields are generated to illuminate a fuselage model. The fields coupled into the fuselage model are assessed. This is done by measurement and numerical computer modelling. For the numerical com- puter modelling fundamentally different approaches are applied with entirely independent model generation. The experimental and numerical results for the two different RF Environments are provided and compared. Aim is to characterize both RF environments for a radiated trans- fer function task and compare experimental and different numerical results to each other.
Rasek, G. A.; Loos, S. E.; Neubauer, M.; Junqua, I.; Schr÷der, A.; Pascual-Gil, E.
Simulation and Analysis of EMC Chambers by Ray Tracing Method
The ray tracing method in conjunction with image theory was used in this study to establish an analysis tool for evaluating the properties of EMC chambers. Computer codes were written in Matlab for simulating the normalized site attenuation (NSA), field uniformity (FU), and normalized site transmission loss (NSTL). By the simulation program, NSAs of semi-anechoic chamber and NSTLs of fully
Ming-Shing Lin; Jia-Ming Ji; C.-I. G. Hsu; Han-Chang Hsieh
Mars and Lunar Vacuum Chamber Testing Facilities and Vacuum Rated Drill Systems
Martian and Lunar low pressure and vacuum conditions, respectively, greatly affect the performance of the drilling mechanics and drill hardware. For this reason, it is imperative to test planetary sampling and coring drills under these specific environments. Honeybee Robotics acquired an 11ft vacuum chamber that is currently being used to test drills to 1m depth and more. A separate cooling
K. Zacny; G. Paulsen; J. Craft; M. Maksymuk; C. Santoro; J. Wilson
Basic features of electromagnetic pulse generated in a laser-target chamber at 3-TW laser facility PALS
We describe the radiofrequency emission taking place when 300 ps laser pulses irradiate various solid targets with an intensity of 1016 W/cm2. The emission of intense electromagnetic pulses was observed outside the laser target chamber by two loop antennas up to 1 GHz. Electromagnetic pulses can be 800 MHz transients, which decay from a peak electromagnetic field of E0 ? 7 kV/m and H0 ? 15 A/m. The occurrence of these electromagnetic pulses is associated with generation of hard x-rays with photon energies extending beyond 1 MeV. This contribution reports the first observation of this effect at the PALS facility.
De Marco, M.; Pfeifer, M.; Krousky, E.; Krasa, J.; Cikhardt, J.; Klir, D.; Nassisi, V.
A facility for the test of large-area muon chambers at high rates
Operation of large-area muon detectors at the future Large Hadron Collider (LHC) will be characterized by large sustained hit rates over the whole area, reaching the range of kHzcm?2. We describe a dedicated test zone built at CERN to test the performance and the aging of the muon chambers currently under development. A radioactive source delivers photons causing the sustained
S. Agosteo; S. Altieri; G. Belli; A. Bonifas; V. Carabelli; L. Gatignon; N P Hessey; M. Maggi; J.-P Peigneux; H. Reithler; Marco Silari; P. Vitulo; M. Wegner
Martian and Lunar low pressure and vacuum conditions, respectively, greatly affect the performance of the drilling mechanics and drill hardware. For this reason, it is imperative to test planetary sampling and coring drills under these specific environments. Honeybee Robotics acquired an 11ft vacuum chamber that is currently being used to test drills to 1m depth and more. A separate cooling system is used to maintain low temperature of planetary analog formations such as ice, soil, icy-soils, and rocks. The low temperature increases the strength of these formations and in turn reduces drilling efficiency. The chamber also has a numerous feed troughs that can be used to transfer thermal data from thermocouples embedded inside the drilled sample, and the drill bits. The thermal data is useful to determine the temperature the sample reaches during the drilling process. The drill systems include rotary, rotary-percussive, and rotary-sonic. The latter two, in particular, offer superior performance in hard formations due to impacts and/or vibrations that enhance penetration rate. All the drill systems are vacuum rated and hence can be used as test platforms for vacuum testing.
Zacny, K.; Paulsen, G.; Craft, J.; Maksymuk, M.; Santoro, C.; Wilson, J.
Venus Pressure Chamber: A Small Testing Facility Available to the Community
Venus is an inhospitable planet where the surface mean. temperature is approximately 740K and the global mean pressure is approximately 95 bars. The atmosphere is comprised mostly of CO2 (approximately 96.5%) and N2 (approximately3.5%) with trace amounts of CO and other reactive gases. Although Venus is very similar in size and mass with the Earth and is Earth's nearest planetary neighbor, it has not received many visitors from Earth, especially those that can land on the surface. The challenge most often cited for this scarcity of surface probes is the workability/survivability of instruments and equipment in Venus' harsh environment. In order to overcome this obstacle, a small pressure chamber has been acquired for use by the scientific community. It is housed at Goddard Space. Flight Center in Maryland and is available to the community for testing of small flight components, instruments and short-term experiments that require high temperatures and pressures.
Johnson, Natasha M.; Wegel, D. C.
Intercomparison of active, passive and continuous instruments for radon and radon progeny measurements in the EML chamber and test facility
Results are presented from the Fifth Intercomparison of Active, Passive and Continuous Instruments for Radon and Radon Progeny Measurements conducted in the EML radon exposure and test facility in May 1996. In total, thirty-four government, private and academic facilities participated in the exercise with over 170 passive and electronic devices exposed in the EML test chamber. During the first week of the exercise, passive and continuous measuring devices were exposed (usually in quadruplicate) to about 1,280 Bq m{sup {minus}3} {sup 222}Rn for 1--7 days. Radon progeny measurements were made during the second week of the exercise. The results indicate that all of the tested devices that measure radon gas performed well and fulfill their intended purpose. The grand mean (GM) ratio of the participants` reported values to the EML values, for all four radon device categories, was 0.99 {plus_minus} 0.08. Eighty-five percent of all the radon measuring devices that were exposed in the EML radon test chamber were within {plus_minus}1 standard deviation (SD) of the EML reference values. For the most part, radon progeny measurements were also quite good as compared to the EML values. The GM ratio for the 10 continuous PAEC instruments was 0.90 {plus_minus} 0.12 with 75% of the devices within 1 SD of the EML reference values. Most of the continuous and integrating electronic instruments used for measuring the PAEC underestimated the EML values by about 10--15% probably because the concentration of particles onto which the radon progeny were attached was low (1,200--3,800 particles cm{sup {minus}3}). The equilibrium factor at that particle concentration level was 0.10--0.22.
Scarpitta, S.C.; Tu, K.W.; Fisenne, I.M.; Cavallo, A.; Perry, P.
Archiving Quality Control Tests in the PHENIX Resistive Plate Chamber Assembly Facility
The PHENIX collaboration at RHIC studies polarized proton-proton collisions to better understand the spin structure of the proton. PHENIX is in the process of upgrading the muon trigger to improve our capabilities of selecting the muons from the decay of W-bosons which are produced more readily at a high transverse momentum than other muon sources. By triggering on single, high transverse momentum muons, new observations on the spin asymmetries of a proton can be obtained. The trigger upgrade will consist of four stations of Resistive Plate Chambers (RPCs), with stations on each side of the interaction region. Each RPC consists of two Bakelite gas gaps, a copper signal plane, an aluminum case, and several layers of mylar and copper. With all of these parts comes the need to archive the manufacturing and quality assurance information along with test results performed on them. This information is kept in a Postgresql Database in the RPC factory and is maintained, modified, and read out through several PHP web pages. A new output page has been produced that will make all of this information much more accessible. This poster will focus on what data is archived, how it is stored, and how it can be easily retrieved and put to use.
Andrews, Keller
Modelling of Echo Reduction by Alberich Anechoic Coatings.
The aim of the present report is to perform numerical modeling of echo reduction by Alberich anechoic coating with two different methods; the Riccati method and the finite difference (FD) method. Both methods model the sound scattering by the cavities exp...
S. Ivansson L. F. Lund
Total scattering cross section improvements from electromagnetic reverberation chambers modeling and stochastic formalism
This article is dedicated to deterministic and stochastic improvements for TSCS computations. Firstly, the To- tal Scattering Cross Section (TSCS) measurements are achieved in a numerical Reverberation Chamber (RC) for different targets. From a theoretical point of view, a free-space environment (for instance an anechoic chamber modeled numerically by absorbing boundary conditions) jointly with plane waves stimulations are needed to
Sebastien Lallechere; Ibrahim El Baba; Pierre Bonnet; Francoise Paladian
This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility with the aid of biplanar grids of various sizes. The spectra and the intensity of the aerodynamic broadband noise have been studied as a function of parameters which characterize the turbulence and of wind turbine performance parameters. Specifically, the longitudinal integral scale of turbulence, the size scale of turbulence, the number of turbine blades, and free stream velocity were varied. Simultaneous measurements of acoustic and turbulence signals were made. The sound pressure level was found to vary directly with the integral scale of the ingested turbulence but not with its intensity level. A theoretical model based on unsteady aerodynamics is proposed.
Loyd, B.; Harris, W. L.
Inlet turbulence and fan noise measured in an anechoic wind tunnel and statically with an inlet flow control device
Turbulence and acoustic measurements were taken in the NASA-Lewis anechoic wind tunnel - a facility which has demonstrated the blade passage tone cutoff phenomena with forward velocity. Turbulence data were taken in a subsonic inlet at various fan speeds under static and forward velocity conditions. A honeycomb/screen flow control device was placed over the inlet during static tests to modify the inflow in an attempt to simulate flight conditions. Acoustic levels of the blade passage tone along with transverse turbulence intensities were reduced with forward velocity. The flow control device reduced the blade passage tone to an intermediate level between those levels associated with static and forward velocity operation.
Shaw, L. M.; Woodward, R. P.; Glaser, F. W.; Dastoli, B. J.
[Technology of hyperbaric chambers].
Technical requirements for hyperbaric chambers are subject to permanent change. Medical gas supplies, the chamber hulls, control systems, medical equipment as well as the security check-up modalities have been constantly adapted according to the most recent technical developments. Moreover, different subtypes of hyperbaric chambers such as treatment facilities, chambers used for training purposes or facilities set up for primary experimental use require specific technical outfit. Keeping in mind some recent tragic accidents in hyperbaric facilities, chamber security is of foremost importance. Alarm- as well as technical monitoring systems, fire-fighting equipment, deluge systems and pressure locks are absolute requirements for any hyperbaric chamber. In chambers used for therapeutic purposes the possibility of invasive and noninvasive patient monitoring as well as hygienic standards have to be ensured. PMID:11315411
Smolle-J³ttner, F M
CFD Simulation on the J-2X Engine Exhaust in the Center-Body Diffuser and Spray Chamber at the B-2 Facility
A computational fluid dynamic (CFD) code is used to simulate the J-2X engine exhaust in the center-body diffuser and spray chamber at the Spacecraft Propulsion Facility (B-2). The CFD code is named as the space-time conservation element and solution element (CESE) Euler solver and is very robust at shock capturing. The CESE results are compared with independent analysis results obtained by using the National Combustion Code (NCC) and show excellent agreement.
Wang, Xiao-Yen; Wey, Thomas; Buehrle, Robert
Simulation of flight-type engine fan noise in the NASA-Lewis 9 x 15 anechoic wind tunnel
A major problem in the measurement of aircraft engine fan noise is the difficulty of simulating, in a ground-based facility, the noise that occurs during flight. Flight-type noise as contrasted to the usual ground-static test noise exhibits substantial reductions in both (1) the time unsteadiness of tone noise and (2) the mean level of tones calculated to be nonpropagating or cut-off. A model fan designed with cut-off of the fundamental tone was acoustically tested in the anechoic wind tunnel under both static and tunnel flow conditions. The properties that characterize flight-type noise were progressively simulated with increasing tunnel flow. The distinctly lobed directivity pattern of propagating rotor/stator interaction modes was also observed. The results imply that the excess noise attributed to the ingestion of the flow disturbances that prevail near most static test facilities was substantially reduced with tunnel flow. The anechoic wind tunnel appears to be a useful facility for applied research on aircraft engine fan noise under conditions of simulated flight.
Heidmann, M. F.; Dietrich, D. A.
Capabilities, Design, Construction and Commissioning of New Vibration, Acoustic, and Electromagnetic Capabilities Added to the World's Largest Thermal Vacuum Chamber at NASA's Space Power Facility
NASA s human space exploration plans developed under the Exploration System Architecture Studies in 2005 included a Crew Exploration Vehicle launched on an Ares I launch vehicle. The mass of the Crew Exploration Vehicle and trajectory of the Ares I coupled with the need to be able to abort across a large percentage of the trajectory generated unprecedented testing requirements. A future lunar lander added to projected test requirements. In 2006, the basic test plan for Orion was developed. It included several types of environment tests typical of spacecraft development programs. These included thermal-vacuum, electromagnetic interference, mechanical vibration, and acoustic tests. Because of the size of the vehicle and unprecedented acoustics, NASA conducted an extensive assessment of options for testing, and as result, chose to augment the Space Power Facility at NASA Plum Brook Station, of the John H. Glenn Research Center to provide the needed test capabilities. The augmentation included designing and building the World s highest mass capable vibration table, the highest power large acoustic chamber, and adaptation of the existing World s largest thermal vacuum chamber as a reverberant electromagnetic interference test chamber. These augmentations were accomplished from 2007 through early 2011. Acceptance testing began in Spring 2011 and will be completed in the Fall of 2011. This paper provides an overview of the capabilities, design, construction and acceptance of this extraordinary facility.
Motil, Susan M.; Ludwiczak, Damian R.; Carek, Gerald A.; Sorge, Richard N.; Free, James M.; Cikanek, Harry A., III
Flow chamber
A flow chamber having a vacuum chamber and a specimen chamber. The specimen chamber may have an opening through which a fluid may be introduced and an opening through which the fluid may exit. The vacuum chamber may have an opening through which contents of the vacuum chamber may be evacuated. A portion of the flow chamber may be flexible, and a vacuum may be used to hold the components of the flow chamber together.
Morozov, Victor (Manassas, VA) [Manassas, VA
Modeling of RF Absorber for Application in the Design of Anechoic Chamber
AbstractŚA proper model of RF absorber must be developed based on information such as absorber reflectivity, in magnitude and phase, for various angles of incidence, and for parallel and perpendicular polarizations. Unfortunately, these data are not available due to the practical limitations of the test fixtures to measure the RF absorber performance. Manufacturer data sheets normally specify only the magnitude
B.-K. Chung; H.-T. Chuah
Anechoic chamber having multi-layer electromagnetic wave absorbers of sintered ferrite and ferrite composite membrane
The structure of the multi-layer electromagnetic wave absorber composed of sintered ferrite and ferrite composite membrane is proposed to improve radiowave absorbing characteristics. The absorption characteristics of the multi-layer absorber can be largely extended compared with the single sintered ferrite layer. Moreover, it is shown that the site attenuation characteristics satisfy the FCC standard for 3 m and 10 m
K. Naito; Tetsuya Mizumoto; Michiharu Takahashi; Sumio Kunieda
Oblique scattering from lossy periodic surfaces with applications to anechoic chamber absorbers
Plane wave scattering from lossy, periodic surfaces with periodicity in one direction is considered for arbitrary polarization and incidence angles. The material is assumed to be homogeneous and characterized by complex values of permittivity and permeability. Muller-type coupled integral equations are derived for the surface electric and magnetic currents. The power reflection coefficient is defined in terms of the scattered
Ramakrishna Janaswamy
Analysis of compact electromagnetic anechoic chamber performance using finite difference time domain methods
The feasibility of modeling compact range performance using the FDTD (finite difference time domain) method is discussed. The advantages of the FDTD method, such as excitation waveform, material, and geometric generality are considered. The limitations, including staircasing errors (which can be reduced or eliminated at the expense of increased computation) and a maximum computation frequency based on computer resource limitations,
R. Luebbers; D. Steich; D. Ryan; K. Kunz
A parametric UWB propagation channel estimation and its performance validation in an anechoic chamber
This paper presents an ultrawide-band (UWB) channel sounding scheme with a parametric channel estimation to seek accurate probing of the propagation channel. The channel sounder consists of a vector network analzer and synthetic array to measure spatial transfer functions. The measured data are then applied to a maximum-likelihood (ML)-based estimator. The concepts implemented in the ML-based parametric channel estimation are:
Katsuyuki Haneda; Jun-Ichi Takada; Takehiko Kobayashi
NSA and resonance in a semi-anechoic chamber in low frequency
As a result of the continuing growth of high speed electronic systems and equipment in the world, EMI (electromagnetic interference) is becoming a big problem. Specifications for the purpose of imposing maximum acceptable levels of noise that can be radiated from electronic systems and equipment have been published. Almost all the electronic products in the world should be tested to
Liu Chen; Wen Yinghong; Zhang Lincheng
Semi anechoic chamber homogeneity according to IEC 1000-4-3
This paper presents the results of the measurements of the field homogeneity according to the electromagnetic compatibility (EMC) standard IEC 1000-4-3 in a semianechoic shielded room with different kinds of absorbers on the floor. Comparison is made between four configurations on the floor: ground plane, pyramid foam filled with carbon (0.6 m long), ferrite panels, ferrite panels and pyramid foam
S. Bigot; J. Delaballe
Real performance of semi-anechoic chambers depending on absorber technology
Standardized measurement procedures for field homogeneity restrict themselves to antennas which have simple and stable radiation characteristics. However, the complicated radiation patterns of real devices might react with a greater sensitivity to their surroundings. In such a case larger errors in the field strength determination arise than are suggested by standardized compliance tests of alternate test sites. The demonstration of
A. Enders
Realization of compact semi- and fully anechoic chambers using a new developed composite absorber
The shape of a composite absorber consisting of ferrite and dielectric lossy material was investigated to reduce the length of the absorber and improve the reflection coefficient in the low frequency range by effectively changing the cross section of the dielectric lossy materials towards the direction of the length. It was found that the most suitable change of cross section
Ken Ishino; Takao Morikawa; Toshifumi Saito; Yasuo Hashimoto; Yasutaka Shimizu
Infrared Scene Projector System Design Description for Installed Infrared Sensor Testing in an Anechoic Chamber Environment.
The OSD, Central Test and Evaluation Program (CTEIP) is tasked to provide a coordinated process for making joint investments in defense T&E to offset the challenges presented by declining investments in test assets and increasing test requirements. Under ...
M. Manzardo M. Gulley T. Joyner K. Thiem
A Robust Method to Count and Locate Audio Sources in a Stereophonic Linear Anechoic Mixture
We propose a new method, called DEMIX anechoic, to estimate the mixing conditions, i.e. number of audio sources plus attenuation and time delay of each sources, in an underdetermined anechoic mixture. The method relies on the assumption that in the neighborhood of some time-frequency points, only one source contributes to the mixture. Such time-frequency points, located with a local confidence
Simon Arberet; Remi Gribonval; F. Bimbot
Simulation of Flight-Type Engine Fan Noise in the NASA-Lewis 9X15 Anechoic Wind Tunnel
Flight type noise as contrasted to the usual ground static test noise exhibits substantial reductions in the time unsteadiness of tone noise, and in the mean level of tones calculated to be nonpropagating or cut-off. A model fan designed with cuttoff of the fundamental tone was acoustically tested in the anechoic wind tunnel under both static and tunnel flow conditions. The properties that characterize flight type noise were progressively simulated with increasing tunnel flow. The distinctly lobed directivity pattern of propagating rotor/stator interaction modes was also observed. Excess noise attributed to the ingestion of the flow disturbances that prevail near most static test facilities is substantially reduced with tunnel flow.
Ultra-light duct for an anechoic wind tunnel
A tunnel ultra-light (or TUL) is a duct composed of acoustically transparent cloth designed to transform an open-jet wind tunnel into a closed-jet wind tunnel. This concept is of interest (a priori) for anechoic wind tunnels because it improves the aerodynamic quality without hindering the measurement of sound in the far field. A full scale device designed for the 3 m diameter test section of CEPRA 19 was described. The apparatus installation did not develop any significant problems, and the mechanical support turned out to be excellent. Aerodynamic and acoustic tests are discussed. Certain imperfections in the installation as tested - instabilities above 25 m/s and acceptable cloth transmission up to 4kHz were revealed. The system as tested could eventually be used in certain applications, for example, in ground based transport. However, the concept of TUL must be developed further to arrive at a reliable mechanism for use in a large number of applications.
Lambourion, J.; Lewy, S.; Papirnyk, O.; Rahier, G.; Remandet, J.-N.
Experimental evaluation of the conversion of emission results obtained from a Reverberation Chamber measurement and a SAR measurement
The reverberation chamber (RC) method has many advantages above the semi anechoic room (SAR) method. The RC method is specifically useful to measure emissions at high frequencies (>1 GHz). This is an important property when we consider the trend of increasing operating frequencies of products and wireless applications. Furthermore, the RC method is useful for immunity tests, where we only
Nico van Dijk; Konika Banerjee
Binaural Simulation Experiments in the NASA Langley Structural Acoustics Loads and Transmission Facility
A location and positioning system was developed and implemented in the anechoic chamber of the Structural Acoustics Loads and Transmission (SALT) facility to accurately determine the coordinates of points in three-dimensional space. Transfer functions were measured between a shaker source at two different panel locations and the vibrational response distributed over the panel surface using a scanning laser vibrometer. The binaural simulation test matrix included test runs for several locations of the measuring microphones, various attitudes of the mannequin, two locations of the shaker excitation and three different shaker inputs including pulse, broadband random, and pseudo-random. Transfer functions, auto spectra, and coherence functions were acquired for the pseudo-random excitation. Time histories were acquired for the pulse and broadband random input to the shaker. The tests were repeated with a reflective surface installed. Binary data files were converted to universal format and archived on compact disk.
Grosveld, Ferdinand W.; Silcox, Richard (Technical Monitor)
Precision qualification of a semi-anechoic room requires careful attention to the sound source and traversing method. Prior work, with test sources mounted above the reflecting floor of such a room, has indicated the potential for image source problems in the resulting field. To address such shortcomings, the new Georgia Tech semi-anechoic room was constructed with a recessed enclosure in the
Kenneth A. Cunefare; Van Biesel; Mark Holdhusen; Austin Shoemaker
Exposure chamber
A chamber for exposing animals, plants, or materials to air containing gases or aerosols is so constructed that catch pans for animal excrement, for example, serve to aid the uniform distribution of air throughout the chamber instead of constituting obstacles as has been the case in prior animal exposure chambers. The chamber comprises the usual imperforate top, bottom and side walls. Within the chamber, cages and their associated pans are arranged in two columns. The pans are spaced horizontally from the walls of the chamber in all directions. Corresponding pans of the two columns are also spaced horizontally from each other. Preferably the pans of one column are also spaced vertically from corresponding pans of the other column. Air is introduced into the top of the chamber and withdrawn from the bottom. The general flow of air is therefore vertical. The effect of the horizontal pans is based on the fact that a gas flowing past the edge of a flat plate that is perpendicular to the flow forms a wave on the upstream side of the plate. Air flows downwardly between the chamber walls and the outer edges of the pan. It also flows downwardly between the inner edges of the pans of the two columns. It has been found that when the air carries aerosol particles, these particles are substantially uniformly distributed throughout the chamber.
Moss, Owen R. (Kennewick, WA)
Echo identification and cancellation techniques for antenna measurement in non-anechoic test sites
This paper focuses on the measurement of the antenna radiation patterns when fully anechoic conditions are not available and, as consequence, some undesirable echoes are initially present in the measure. Two techniques are analyzed and compared, which - starting from data measured in the frequency domain - allow the echo contributions to be identified and the antenna radiation pattern to
S. Loredo; M. R. Pino; F. Las-Heras; T. K. Sarkar
Design, Characterization, and Optimization of a Broadband Mini Exposure Chamber for Studying Catecholamine Release From Chromaffin Cells Exposed to Microwave Radiation: Finite-Difference Time-Domain Technique
A free-space in vitro exposure system for identifying specific microwave (MW) parameters in the frequency range of 1-6 GHz that can induce nonthermal effects on exocytosis, which is the process by which neurotransmitter release occurs, has been designed, constructed, characterized, and optimized. The exposure system is placed within an anechoic chamber and incorporates continuous online monitoring of basal and stimulated
Jihwan Yoon; I. Chatterjee; D. McPherson; G. L. Craviso
Underdetermined Anechoic Blind Source Separation via ellq-Basis-Pursuit With q<<1
In this paper, we address the problem of under-determined Blind Source Separation (BSS) of anechoic speech mixtures. We propose a demixing algorithm that exploits the sparsity of certain time-frequency expansions of speech signals. Our algorithm mergesq-basis-pursuit with ideas based on the degenerate unmixing estimation technique (DUET) (1). There are two main novel components to our approach: (1) Our algorithm makes
Rayan Saab; Ozgur Yilmaz; Martin J. Mckeown; Rafeef Abugharbieh
Optimising flat-walled multi-layered anechoic linings using evolutionary algorithms
Previous investigations indicated that a flat-walled, multi-layered anechoic lining system, with an overall thickness slightly less than a quarter of a wavelength, could be used to achieve a required cut-off frequency. However, the work proved to be tedious and time consuming because of the numerous trial-and-error measurements involved. On the other hand, the successful application of a method of calculating
Jingfeng Xu; Joseph Nannariello; Fergus R. Fricke
Anechoic sphere phantoms for estimating 3-D resolution of very-high-frequency ultrasound scanners
Two phantoms have been constructed for assessing performance of high-frequency ultrasound imagers. They also allow for periodic quality assurance tests and training technicians in the use of higher-frequency scanners. The phantoms contain eight blocks of tissue-mimicking material; each block contains a spatially random distribution of suitably small anechoic spheres having a small distribution of diameters. The eight mean sphere diameters
E. L. Madsen; G. R. Frank; M. M. McCormick; M. E. Deaner; T. A. Stiles
Subjective evaluation of auralizations created from multi-channel anechoic recordings of a talker in motion
A high degree of speech intelligibility is very important in educational environments. When designing such spaces, like classrooms, auralizations can be used to subjectively assess the degree of speech intelligibility and clarity. Auralizations are most commonly made by convolving the impulse response (IR) of an omni-directional source with a single channel anechoic speech recording. This paper explores the idea of using multi-channel recordings to create the auralizations, using a female talker in motion. An omni-directional source is split into quadrants and the IR is calculated for each section. These IR's are convolved with the appropriate channel of the anechoic recording and then the four auralizations are mixed to create one final auralization. The auralizations were made using four-channel anechoic recordings of a person walking on a platform while talking. Subjective tests were conducted to determine the ease with which subjects could identify the direction of the movement of the source in rooms with varying amounts of absorption. This method can be used to create more realistic classroom auralizations, as teachers typically move around the room as they teach. [Work supported by the National Science Foundation.
Vigeant, Michelle C.; Wang, Lily M.
Ionization chamber
An ionization chamber has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionize the gas.
Walenta, Albert H. (Port Jefferson Station, NY)
Research and test facilities
A description is given of each of the following Langley research and test facilities: 0.3-Meter Transonic Cryogenic Tunnel, 7-by 10-Foot High Speed Tunnel, 8-Foot Transonic Pressure Tunnel, 13-Inch Magnetic Suspension & Balance System, 14-by 22-Foot Subsonic Tunnel, 16-Foot Transonic Tunnel, 16-by 24-Inch Water Tunnel, 20-Foot Vertical Spin Tunnel, 30-by 60-Foot Wind Tunnel, Advanced Civil Transport Simulator (ACTS), Advanced Technology Research Laboratory, Aerospace Controls Research Laboratory (ACRL), Aerothermal Loads Complex, Aircraft Landing Dynamics Facility (ALDF), Avionics Integration Research Laboratory, Basic Aerodynamics Research Tunnel (BART), Compact Range Test Facility, Differential Maneuvering Simulator (DMS), Enhanced/Synthetic Vision & Spatial Displays Laboratory, Experimental Test Range (ETR) Flight Research Facility, General Aviation Simulator (GAS), High Intensity Radiated Fields Facility, Human Engineering Methods Laboratory, Hypersonic Facilities Complex, Impact Dynamics Research Facility, Jet Noise Laboratory & Anechoic Jet Facility, Light Alloy Laboratory, Low Frequency Antenna Test Facility, Low Turbulence Pressure Tunnel, Mechanics of Metals Laboratory, National Transonic Facility (NTF), NDE Research Laboratory, Polymers & Composites Laboratory, Pyrotechnic Test Facility, Quiet Flow Facility, Robotics Facilities, Scientific Visualization System, Scramjet Test Complex, Space Materials Research Laboratory, Space Simulation & Environmental Test Complex, Structural Dynamics Research Laboratory, Structural Dynamics Test Beds, Structures & Materials Research Laboratory, Supersonic Low Disturbance Pilot Tunnel, Thermal Acoustic Fatigue Apparatus (TAFA), Transonic Dynamics Tunnel (TDT), Transport Systems Research Vehicle, Unitary Plan Wind Tunnel, and the Visual Motion Simulator (VMS).
Magma chambers
Recent observational and theoretical investigations of terrestrial magma chambers (MCs) are reviewed. Consideration is given to the evidence for MCs with active convection and crystal sorting, problems of direct MC detection, theoretical models of MC cooling, the rheology and dynamics of solidification fronts, crystal capture and differentiation, convection with solidification, MC wall flows, and MC roof melting. Diagrams, graphs, and a list of problems requiring further research are provided.
Marsh, Bruce D.
Time Domain Antenna Measurements in Compact Ranges and Small Anechoic Chambers: Practice and Modelling, Pattern Error Correction and Antenna Diagnostics.
The research work in this thesis focuses on three main areas (1) the practice and modeling of time domain antenna measurements, (2) pattern error correction and (3) antenna diagnostics. The new measurement approach has been implemented in a compact antenn...
A. J. Marti Canales
Improved low-frequency performance of pyramid-cone absorbers for application in semi-anechoic chambers
A mathematical model, developed by the authors to describe the low-frequency reflection properties of arrays of pyramid-cone absorbers, is used to improve the design of these cones in the range of 30 to 300 MHz. The model shows that at frequencies such that the transverse spacing of the cones is small compared to a wavelength, a reflecting wave is not
Edward F. Kuester; Christopher L. Holloway
Multipath effects in semi-anechoic chambers at low frequencies: a simplified prediction model based on image theory
The multipath effects due to radiating sources inside a shielded room can not be neglected when the frequency of the harmonic components of the electromagnetic field are below the frequency threshold of the absorber lined walls. This paper deals with the prediction of the total radiated field by an electric dipole source inside a shielded room, taking into account the
A. Orlandi
A novel evaluation method for semi-anechoic chamber using zero biased optical devices and time-domain analysis
We propose an optical fiber link electromagnetic interference measurement system that consists of a transmitting optical fiber link module, a receiving optical fiber link module, and a vector network analyzer. Using our proposed optical system, we can measure S21 (?) and calculate S21 (t) for the radiated electromagnetic interference measurement. We show experimental results of S21S between a small biconical
S. Kurokawa; M. Ameya; M. Hirose
Backscattering analysis of flat plate and dihedral corner reflectors using PO and comparison with RCS measurements in anechoic chamber
Physical Optics (PO) is used to calculate Radar Cross Section (RCS) of flat plate and dihedral corner reflectors. The numerical results obtained via simulation are used to compare the RCS measured for these targets recovered and non-recovered with Radar Absorbing Materials (RAM). All simulations and experiments are effectuated in a frequency of 10 GHz. Experimental measurements using Radar Cross Section
L. A. Andrade; E. L. Nohara; G. G. Peixoto; M. C. Rezende; I. M. Martin
Chamber B Thermal/Vacuum Chamber: User Test Planning Guide
Test process, milestones and inputs are unknowns to first-time users of Chamber B. The User Test Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their test engineering personnel in test planning and execution. Material covered includes a roadmap of the test process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, test article interfaces, and inputs necessary to define test scope, cost, and schedule are included as an appendix to the guide.
Montz, Mike E.
Quality assurance procedures for environmental control and monitoring in plant growth facilities. Report of the North Central Regional 101 Committee on Growth Chamber Use
This report includes procedures for ensuring the quality of the environment provided for plant growth in controlled environment facilities. Biologists and engineers may use these procedures for ensuring quality control during experiments or for ensuring quality control in the design of plant growth facilities. Environmental monitoring prior to and during experiments is included in these procedures. Specific recommendations cover control, acquisition, and calibration for sensor types for the separate parameters of radiation (light), temperature, humidity, carbon dioxide, and air movement.
Tibbitts, T. W. (Principal Investigator)
Numerical design of Alberich anechoic coatings with superellipsoidal cavities of mixed sizes.
Thin rubber coatings with cavities in a doubly periodic lattice are able to reduce reflections of underwater sound by redistributing normally incident energy such that absorption in the surrounding rubber is enhanced. For spherical scatterers, the anechoic effect can be studied numerically by the layer-multiple-scattering (LMS) method. In comparison to more flexible but also more computer intensive methods, such as finite-element method modeling, there are two important advantages. An improved physical understanding of the anechoic effect can be achieved by simplified semianalytical analysis, and the high computational speed allows modern global optimization techniques to be applied for coating design. In this paper, the flexibility of the LMS method is improved by combination with an efficient algorithm for numerical computation of transition matrices for superellipsoidal scatterers. (A superellipsoid is a generalization of an ellipsoid, allowing more box-filling shapes, for example.) Extensions to mixtures of nonspherical scatterers of different types are also considered, in order to enhance the broadband performance. Symmetry properties are used to reduce the size of the pertinent equation systems. Examples of numerical coating design for underwater acoustic applications are presented, using differential evolution algorithms for the optimization. PMID:19062837
Ivansson, Sven M
Markov-chain Monte Carlo identification of favorable design choices with application to anechoic coatings.
Global optimization methods can be used to numerically determine optimal design parameters for an object. However, this does not by itself give a good appreciation of other parameter choices that may be almost as good and even preferable from other points of view. In the present paper, Markov-chain Monte Carlo methods are used to go beyond the optimal solution and create an ensemble of object models in parameter space that covers a set of favorable models uniformly. In direct analogy with applications to Bayesian inversion with determination of an unknown posterior probability density, projections of the model ensemble onto parameter axes and planes are used to exhibit parameter sensitivities and dependencies. Design of anechoic rubber coatings, with cylinder cavities having axes in a lateral direction, is considered as a particular application. The anechoic effect is evaluated by the efficient layer-multiple-scattering method, which is extended to handle cylinder scatterers of noncircular cross sections and mixed types. As anticipated by computed scattering and absorption cross sections for an isolated cavity, the favorable coatings have oblate cavity cross-section shapes, which is useful to achieve good low-frequency reflection reduction with a thin coating. PMID:24907797
Performance of the high speed anechoic wind tunnel at Lyon University
The characteristics of the feed duct, the wind tunnel, and the experiments run in the convergent-divergent anechoic wind tunnel at Lyon University are described. The wind tunnel was designed to eliminate noise from the entrance of air or from flow interactions with the tunnel walls so that noise caused by the flow-test structure interactions can be studied. The channel contains 1 x 1 x 0.2 m glass and metal foil baffles spaced 0.2 m apart. The flow is forced by a 350 kW fan in the primary circuit, and a 110 kW blower in the secondary circuit. The primary circuit features a factor of four throat reductions, followed by a 1.6 reduction before the test section. Upstream and downstream sensors permit monitoring of the anechoic effectiveness of the channel. Other sensors allow modeling of the flow structures in the tunnel. The tunnel was used to examine turbulent boundary layers in flows up to 140 m/sec, tubulence-excited vibrations in walls, and the effects of laminar and turbulent flows on the appearance and locations of noise sources.
Sunyach, M.; Brunel, B.; Comte-Bellot, G.
New correlation algorithm between FAC and OATS\\/SAC
This paper proposes the new correlation algorithm between the fully anechoic chamber (FAC) and the test facilities with ground plane such as open area test site (OATS), semi-anechoic chamber (SAC), etc. in order to use the FAC as an alternative test facility. The approach is to model the EUT as an equivalent set of multipoles. Assuming the EUT is electrically
Jong Hwa Kwon; Hyun H. Park; Hyung Do Choi
'Flight effect' analysis of turbojet and turbofan nozzle models in the CEPRA 19 anechoic wind tunnel at the CEP
Measurements have been obtained at the Centre d'Essais des Propulseurs CEPRA 19 anechoic wind tunnel using turbojet and turbofan nozzle models in order to study the effect of flight velocity on jet noise. The present results are found to be in good general agreement with both theoretical results and flight test data. It is suggested that noise spectra anomalies noted
C. Fayot; D. Gely
D0 central tracking chamber performance studies
The performance of the completed DO central tracking chamber was studied using cosmic rays at the State University of New York at Stony Brook. Also studied was a prototype tracking chamber identical in design to the completed DO tracking chamber. The prototype chamber was exposed to a collimated beam of 150 GeV pions at the Fermilab NWA test facility. Results indicate an R{Phi} tracking resolution compatible with the limitations imposed by physical considerations, excellent 2 track resolution, and a high track reconstruction efficiency along with a good rejection power against {gamma} {yields} e {sup +} e{sup {minus}} events.
Pizzuto, D.
Portable Hyperbaric Chamber
A portable, collapsible hyperbaric chamber was developed. A toroidal inflatable skeleton provides initial structural support for the chamber, allowing the attendant and/or patient to enter the chamber. Oval hatches mate against bulkhead rings, and the hyperbaric chamber is pressurized. The hatches seal against an o-ring, and the internal pressure of the chamber provides the required pressure against the hatch to maintain an airtight seal. In the preferred embodiment, the hyperbaric chamber has an airlock to allow the attendant to enter and exit the patient chamber during treatment. Visual communication is provided through portholes in the patient and/or airlock chamber. Life monitoring and support systems are in communication with the interior of the hyperbaric chamber and/or airlock chamber through conduits and/or sealed feed-through connectors into the hyperbaric chamber.
Schneider, William C. (Inventor); Locke, James P. (Inventor); DeLaFuente, Horacio (Inventor)
Operating manual for the radon-daughter chamber
A radon-daughter chamber was constructed at the US Department of Energy (DOE) Grand Junction Projects Office (GJPO) facility for the purpose of calibrating, testing and evaluating radon and radon-daughter measuring instruments used in support of DOE remedial action programs. The chamber is an environmentally controlled cylindrical vessel through which air containing radon can be circulated. Environmental parameters within the chamber
G. H. Jr. Langner; T. Nelson
The absorption characteristics of anechoic coating embedding mixed-cavity structure with single or double shell backing
Rubber sheets embedding air cavities are wide used as anechoic coatings to reduce the energy of sound waves reflected by underwater structures, with a great military and use benefit to underwater vehicle sound stealth. According to the backing type, it can be divided into two kinds, namely rubber sheets-steel-air and rubber sheets-steel-water-steel-air, called the single and double shell backing coatings
Chao Shang; Ying-jie Wei; Jia-zhong Zhang
Array antenna characterization technique based on evanescent reactive-near-field probing in an ultra-small anechoic box
This paper presents a new technique in which small array antenna performance is characterized based on reactive-near-field probing in an ultra-small anechoic box and with a multi-probe. Unlike conventional far- or near-field measurement methods, the radiation patterns in the proposed approach are computed from the currents only at discrete points picked up in the evanescent region of an array antenna's
Qing Han; Keizo Inagaki; Takashi Ohira
Transabdominal Ultrasonography of the Small Bowel After Oral Administration of a Non-absorbable Anechoic Solution: Comparison with Barium Enteroclysis
AIM: The aim of this study was to determine if oral administration of a non-absorbable anechoic solution conveys any benefit during abdominal ultrasound (US), with special reference to its accuracy.MATERIALS AND METHODS: Fifty-three adult out-patients scheduled for small bowel barium enema (SBE) were included. The day before SBE all patients underwent abdominal US before and after oral administration of an
Giuseppe Cittadini; Veronica Giasotto; Giacomo Garlaschi; Enzo de Cicco; Alessandra Gallo; Giorgio Cittadini
Field chambers for assessing crop loss from air pollutants
A new field fumigation facility has been developed for determining effects of air pollutants on crops. The permanent facility consists of closed-top, octagonal chambers 2.1 m tall by 2.5 m across. Each chamber is supplied with air via underground ducting from two centralized blowers, one charcoal-filtered and the other nonfiltered. Individual chambers can be adjusted to 100% filtered air for
R. C. Musselman; P. M. McCool; R. J. Oshima; R. R. Teso
APS Storage Ring vacuum chamber fabrication
The 1104-m circumference Advanced Photon Source Storage Ring Vacuum System is composed of 240 individual sections, which are fabricated from a combination of aluminum extrusions and machined components. The vacuum chambers will have 3800 weld joints, each subject to strict vacuum requirements, as well as a variety of related design criteria. The vacuum criteria and chamber design are reviewed, including a discussion of the weld joint geometries. The critical fabrication process parameters for meeting the design requirements are discussed. The experiences of the prototype chamber fabrication program are presented. Finally, the required facilities preparation for construction activity is briefly described. 6 refs., 6 figs., 1 tab.
Goeppner, G.A.
Aerospike Thrust Chamber Program.
An existing, but damaged, 25,000-pound thrust, flightweight, oxygen/hydrogen aerospike rocket thrust chamber was disassembled and partially repaired. A description is presented of the aerospike chamber configuration and of the damage it had suffered. Tech...
J. Campbell S. M. Cobb
Hyperphysics: The Cloud Chamber
NSDL National Science Digital Library
This Hyperphysics webpage contains a short description of the Wilson cloud chamber and two photographs by Wilson himself of cloud chamber tracks. Links provides information about various methods of detecting radiation and also about the muon, an elementary particle that was first detected in a cloud chamber. The text on this page is written at a level of a student of introductory physics.
Nave, Carl R.
Two chamber reaction furnace
A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700.degree. and 800.degree. C.) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800.degree. to 950.degree. C. to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product.
Blaugher, Richard D. (Evergreen, CO)
A vertical two chamber reaction furnace is described. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 C and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.
Blaugher, R.D.
TRU waste characterization chamber gloveboxes.
Argonne National Laboratory-West (ANL-W) is participating in the Department of Energy's (DOE) National Transuranic Waste Program in support of the Waste Isolation Pilot Plant (WIPP). The Laboratory's support currently consists of intrusive characterization of a selected population of drums containing transuranic waste. This characterization is performed in a complex of alpha containment gloveboxes termed the Waste Characterization Gloveboxes. Made up of the Waste Characterization Chamber, Sample Preparation Glovebox, and the Equipment Repair Glovebox, they were designed as a small production characterization facility for support of the Idaho National Engineering and Environmental Laboratory (INEEL). This paper presents salient features of these gloveboxes.
Duncan, D. S.
Medical altitude chamber
US Patent & Trademark Office Database
The medical altitude chamber is constituted by a pressuretight therapeutic chamber communicating with a source of a gas medium under pressure. It also incorporates apparatus for moistening the gas medium in the therapeutic chamber, said apparatus comprising a liquid reservoir whose lower part communicates through an adjustable throttle with the internal space of the jet pump nozzle, and a pressure regulator which has an inlet for communication with the source of the gas medium, a setting inlet for communication with the therapeutic chamber, and an outlet for communication with the upper part of the liquid reservoir.
BOREAS TGB-1 NSA SF6 Chamber Flux Data
The BOREAS TGB-1 team made several chamber and tower measurements of trace gases at sites in the BOREAS NSA. This data set contains sulfur hexafluoride (SF6) dark chamber flux measurements at the NSA-OJP and NSA-YJP sites from 16-May through 13-Sep-1994. Gas samples were extracted approximately every 7 days from dark chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.
Crill, Patrick; Varner, Ruth K.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)
High resolution drift chambers
High precision drift chambers capable of achieving less than or equal to 50 ..mu..m resolutions are discussed. In particular, we compare so called cool and hot gases, various charge collection geometries, several timing techniques and we also discuss some systematic problems. We also present what we would consider an ''ultimate'' design of the vertex chamber. 50 refs., 36 figs., 6 tabs.
Va'vra, J.
The Mobile Chamber
A document discusses a simulation chamber that represents a shift from the thermal-vacuum chamber stereotype. This innovation, currently in development, combines the capabilities of space simulation chambers, the user-friendliness of modern-day electronics, and the modularity of plug-and-play computing. The Mobile Chamber is a customized test chamber that can be deployed with great ease, and is capable of bringing payloads at temperatures down to 20 K, in high vacuum, and with the desired metrology instruments integrated to the systems control. Flexure plans to lease Mobile Chambers, making them affordable for smaller budgets and available to a larger customer base. A key feature of this design will be an Apple iPad-like user interface that allows someone with minimal training to control the environment inside the chamber, and to simulate the required extreme environments. The feedback of thermal, pressure, and other measurements is delivered in a 3D CAD model of the chamber's payload and support hardware. This GUI will provide the user with a better understanding of the payload than any existing thermal-vacuum system.
Scharfstein, Gregory; Cox, Russell
The Cloud Chamber
This web "booklet" from the University of Cambridge provides a description of the experiments of physicist Charles Thomson Rees Wilson that led to the first succesful cloud chamber, a powerful tool for nuclear and elementary particle physics. The site offers interactive graphics to help show how these chambers work. Photos and excerpts from some of Wilson's first publications are also included as well.
Scarf inlet aeroacoustics study/scarf inlet with Boeing ICD
Photographs shows the Langley 12 inch ADP fan equipped with an inflow control device (ICD) borrowed from the Boeing company. The fan and ICD are inside the anechoic chamber of the ANRF. Photographed in building 1218A, the Anechoic Noise Research Facility.
Photographs shows the Langley 12 inch ADP fan equipped with an inflow control device (ICD) borrowed from the Boeing company. The fan and ICD are inside the anechoic chamber of the ANRF. Lorenzo R. Clark is in the photograph. Photographed in building 1218A, the Anechoic Noise Research Facility.
Ion chambers for fluorescence and laboratory EXAFS detection
It is possible to design gas ionization chambers with a noise equivalence of 10/sup 3/ photons per second for 10 keV x-radiation. With such a low noise level, ion detectors can be used for laboratory EXAFS facilities and fluorescence detectors at national synchrotron facilities where the detected signal is above 10/sup 3/ photons/s. In such use the ion chambers are limited by statistical noise and produce as good a signal to noise as counting detectors. The advantages of ion chambers are simplicity, high linearity at high counting rates, and large detecting area.
Stern, E.A.; Elam, W.T.; Bunker, B.A.; Lu, K.; Heald, S.M.
The Mars Chamber
NASA Video Gallery
The Mars chamber is a box about the size of a refrigerator that re-creates the temperatures, pressures, and atmosphere of the Martian surface, essentially creating a Mars environment on Earth! Scie...
Slurry-Mixing Chamber
Paddles and water jets create uniform, continuous flow. Slurry-mixing chamber on hydrojet-jaw mining machine ensures uniform, continuously flowing slurry of coal particles in water. By mixing coal and water at high speed and keeping resulting slurry in constant motion, chamber prevents slurry from becoming dry semisolid that blocks flow. Also prevents coal particles from settling and caking in bends, corners, and other locations where flow changes in direction or speed.
Lewis, E. V.
RTCA\\/DO-160D, Environmental Conditions and Test Procedures for Airborne Equipment, defines a series of minimum standard environmental and electromagnetic compatibility test conditions (categories) and applicable laboratory test procedures for airborne equipment. Change One, issued in December, 2000, includes a complete revision of Section 20 - Radio Frequency Susceptibility (Radiated and Conducted), which contains two different radiated RF susceptibility test procedures: reverberation
A comparison of radiated emissions testing to European Directive 95\\/54\\/EC using an open field test site and a semi-anechoic chamber
Most automotive component level testing, and in particular European Directive 95\\/54 requires that under some (in practice most) conditions radiated emissions measurements from electrical\\/electronic sub-assemblies (ESAs) are made with the ESA under test mounted on an elevated ground plane 1 m high on a wooden table. It is shown that how this ground plane is connected to the test sites
P. Miller
Sleeve reaction chamber system
A chemical reaction chamber system that combines devices such as doped polysilicon for heating, bulk silicon for convective cooling, and thermoelectric (TE) coolers to augment the heating and cooling rates of the reaction chamber or chambers. In addition the system includes non-silicon-based reaction chambers such as any high thermal conductivity material used in combination with a thermoelectric cooling mechanism (i.e., Peltier device). The heat contained in the thermally conductive part of the system can be used/reused to heat the device, thereby conserving energy and expediting the heating/cooling rates. The system combines a micromachined silicon reaction chamber, for example, with an additional module/device for augmented heating/cooling using the Peltier effect. This additional module is particularly useful in extreme environments (very hot or extremely cold) where augmented heating/cooling would be useful to speed up the thermal cycling rates. The chemical reaction chamber system has various applications for synthesis or processing of organic, inorganic, or biochemical reactions, including the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction.
Northrup, M. Allen (Berkeley, CA); Beeman, Barton V. (San Mateo, CA); Benett, William J. (Livermore, CA); Hadley, Dean R. (Manteca, CA); Landre, Phoebe (Livermore, CA); Lehew, Stacy L. (Livermore, CA); Krulevitch, Peter A. (Pleasanton, CA)
The smog chamber facilities of the University of California, Riverside were used to collect experimental data to assess the effects of multi-day irradiations on photochemical oxidant formation. This volume contains the printouts of all the data that were collected in the study. T...
Boeing Infrared Sensor (BIRS) Calibration Facility.
A new large calibration facility, Boeing Infrared Sensor (BIRS), at the Boeing Kent Space Center near Seattle (U.S.) is described. The BIRS facility provides environmental simulation for calibration of endoatmospheric sensors, with sensor chamber temperat...
J. C. Murphy L. V. Scorsone
Automated Electrostatics Environmental Chamber
The Mars Electrostatics Chamber (MEC) is an environmental chamber designed primarily to create atmospheric conditions like those at the surface of Mars to support experiments on electrostatic effects in the Martian environment. The chamber is equipped with a vacuum system, a cryogenic cooling system, an atmospheric-gas replenishing and analysis system, and a computerized control system that can be programmed by the user and that provides both automation and options for manual control. The control system can be set to maintain steady Mars-like conditions or to impose temperature and pressure variations of a Mars diurnal cycle at any given season and latitude. In addition, the MEC can be used in other areas of research because it can create steady or varying atmospheric conditions anywhere within the wide temperature, pressure, and composition ranges between the extremes of Mars-like and Earth-like conditions.
Calle, Carlos; Lewis, Dean C.; Buchanan, Randy K.; Buchanan, Aubri
Electrostatic Levitator Vacuum Chamber
Optical ports ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (beam passes through the window at left), positioning lasers (one port is at center), and lamps to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.
Optical testing cryogenic thermal vacuum facility
The construction of a turnkey cryogenic vacuum test facility was recently completed. The facility will be used to measure and record the surface profile of large diameter and 540 kg optics under simulated space conditions. The vacuum test chamber is a vertical stainless steel cylinder with a 3.5 diameter and a 7 m tangent length. The chamber was designed to
Patrick W. Dohogne; Warren A. Carpenter
Characterization of the spatial resolution of different high-frequency imaging systems using a novel anechoic-sphere phantom
The spatial resolution of high-frequency ultrasound (HFU, >20 MHz) imaging systems is usually determined using wires perpendicular to the beam. Recently, two tissue-mimicking phantoms (TMPs) were developed to estimate the three-dimensional (3D) resolution. Each of the TMPs consist of nine, 1 cm wide slabs of tissue-mimicking material containing randomly distributed anechoic spheres. All anechoic spheres in one slab have the same dimensions, and their diameter is increased from 0.1 mm in the first slab to 1.09 mm in the last. The scattering background for one set of slabs was fabricated using 3.5 Ąm glass beads, while those of the second set were 6.4 Ąm. The ability of a HFU system to detect these spheres against a speckle background provides a realistic estimation of its 3D spatial resolution. In the present study, these TMPs were used with HFU systems using single-element transducers, linear arrays and annular arrays. The TMPs were immersed in water and each slab was scanned using a VisualSonicsÖ Vevo 770 and Vevo 2100, and a custom HFU system based on a 5-element annular array. The annular array had a nominal center frequency of 40 MHz, a focal length of 12 mm, and a total aperture of 6 mm. A synthetic-focusing algorithm was used to form images with an increased depth-of-field. The penetration depth was increased by using a linear-chirp signal spanning 15 to 65 MHz over 4 Ąs. Results obtained with the custom system were compared to those of the Vevo systems (40 MHz probes RMV-704 and MS-550D) in terms of sphere detection, i.e., 3D spatial resolution, and contrast-to-noise ratio (CNR). Resulting B-mode images indicated that only the linear-array transducer failed to clearly resolve the 0.2 mm spheres, which showed that the 3D spatial resolution of the single-element and annular-array transducers was superior to that of the linear array. The single-element transducer could only detect these spheres over a narrow 1.5 mm depth-of-field, while the annular array was able to detect them to depths of at least 7 mm. For any size of the anechoic spheres, the annular array excited by a chirp-coded signal provided images of the highest contrast, with a maximum CNR of 1.8 at the focus, compared to 1.3 when using impulse excitation and 1.6 with the single-element transducer and linear array. This imaging configuration also provided CNRs above 1.2 over a wide depth range of 8 mm, while CNRs would quickly drop below 1 outside the focal zone of the other configurations.
Filoux, Erwan; Mamou, Jonathan; Aristizabal, Orlando; Ketterling, Jeffrey A.
Two-dimensional laser velocimetry for the study of dual-flow jets with flight effect in the CEPRA 19 anechoic wind tunnel
A feasibility study concerning the use of a two-dimensional laser velocimeter to study dual-flow jets with flight effect was performed in the CEPRA 19 anechoic wind tunnel. The measurement setup is described, and results are presented. Owing to the accuracy of the measurements obtained and the automation of the various processes involved, the two-dimensional laser velocimeter has been added to
Jacques Gatard; Didier Soulevant; Serge Aveline
Improved wire chamber
An improved gas mixture for use with proportional counter devices, such as Geiger-Mueller tubes and drift chambers. The improved gas mixture provides a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor. 2 figs.
Atac, M.
Flame-Test Chamber
Experimental chamber provides controlled environment for observation and measurement of flames propagating in expanding plume of flammable air/fuel mixture under atmospheric conditions. Designed to evaluate quenching capability of screen-type flame arresters in atmospheric vents of fuel cargo tanks aboard marine cargo vessels.
Bjorklund, R. A.
Review of straw chambers
This is a review of straw chambers used in the HRS, MAC, Mark III, CLEO, AMY, and TPC e{sup +}e{sup {minus}} experiments. The straws are 6--8 mm in diameter, operate at 1--4 atmospheres and obtain resolutions of 45--100 microns. The designs and constructions are summarized and possible improvements discussed.
Toki, W.H.
College/Chamber Synergy.
ERIC Educational Resources Information Center
Describes the relationship between Mt. Hood Community College and the local chamber of commerce. Stresses that both groups are concerned with mobilizing resources toward educational, social, and economic improvement. Highlights resulting programs, including breakfast seminars, community leadership programs, international forum series, a culturalģ
Keyser, John; Nicholson, R. Stephen
Bubble Chamber Site
This substantial site features a large number of photos of bubble chamber (BC) tracks, many with a discussion of the physics. There is a description of how the BC works and also useful tutorial on reading BC pictures. The high quality of the images and the explanations of the events that are shown make this site especially valuable.
Rocket Combustion Chamber Coating
A coating with the ability to protect (1) the inside wall (i.e., lining) of a rocket engine combustion chamber and (2) parts of other apparatuses that utilize or are exposed to combustive or high temperature environments. The novelty of this invention lies in the manner a protective coating is embedded into the lining.
Holmes, Richard R. (Inventor); McKechnie, Timothy N. (Inventor)
Research on Characteristics of Field Uniformity in Reverberation Chamber Using Two TX Antennas
This paper presents a method to improve field uniformity using two TX antennas in a reverberation chamber with less steps of a stirrer. A mode-stirred reverberation chamber (MSRC) is considered as an alternative to the semi-anechoic chamber for an electromagnetic compatibility test because it provides a large test volume, a statistically uniform field, and a high maximum electric field. To improve field uniformity, we introduce two transmitting antennas for excitation in an MSRC, and predict statistical distribution of the complex reflection coefficients (scattering parameters). To prove the validation of our theory and the reliability of measurement results, three kinds of stirrers with different shape and sizes were fabricated and their efficiencies were measured in an MSRC, and then field uniformities have been investigated for 1-3GHz frequency within the maximum number of independent samples that stirrers can provide. The measurement results show that the average received power is about 1.5 times as high as when using one transmitting antenna, and field uniformity is improved. Use of two transmitting antennas in an MSRC is regarded as a useful method to improve field uniformity at less stirrer steps, for radiated immunity tests.
Kim, Jung-Hoon; Jang, Tae-Heon; Lim, Sung-Kuk; Lee, Songjun; Yang, Sung-Il
Multi-chamber deposition system
A system for the simultaneous deposition of different coatings onto a thin web within a large volume vacuum chamber is disclosed which chamber is provided with a plurality of deposition chambers in which the different layers are deposited onto the film as its moves from a supply roll to a finished take-up roll of coated web. The deposition chambers provided within the large vacuum chamber are provided with separate seals which minimize back diffusion of any dopant gas from adjacent deposition chambers.
Jacobson, Richard L. (Roseville, MN); Jeffrey, Frank R. (Shoreview, MN); Westerberg, Roger K. (Cottage Grove, MN)
Combustor with fuel preparation chambers
An annular combustor having fuel preparation chambers mounted in the dome of the combustor. The fuel preparation chamber comprises an annular wall extending axially from an inlet to an exit that defines a mixing chamber. Mounted to the inlet are an air swirler and a fuel atomizer. The air swirler provides swirled air to the mixing chamber while the atomizer provides a fuel spray. On the downstream side of the exit, the fuel preparation chamber has an inwardly extending conical wall that compresses the swirling mixture of fuel and air exiting the mixing chamber.
Zelina, Joseph (Inventor); Myers, Geoffrey D. (Inventor); Srinivasan, Ram (Inventor); Reynolds, Robert S. (Inventor)
Three chamber negative ion source
A negative ion vessel is divided into an excitation chamber, a negative ionization chamber and an extraction chamber by two magnetic filters. Input means introduces neutral molecules into a first chamber where a first electron discharge means vibrationally excites the molecules which migrate to a second chamber. In the second chamber a second electron discharge means ionizes the molecules, producing negative ions which are extracted into or by a third chamber. A first magnetic filter prevents high energy electrons from entering the negative ionization chamber from the excitation chamber. A second magnetic filter prevents high energy electrons from entering the extraction chamber from the negative ionizing chamber. An extraction grid at the end of the negative ion vessel attracts negative ions into the third chamber and accelerates them. Another grid, located adjacent to the extraction grid, carries a small positive voltage in order to inhibit positive ions from migrating into the extraction chamber and contour the plasma potential. Additional electrons can be suppressed from the output flux using ExB forces provided by magnetic field means and the extractor grid electric potential.
Leung, Ka-Ngo (Hercules, CA); Ehlers, Kenneth W. (Alamo, CA); Hiskes, John R. (Livermore, CA)
Multiwire proportional chamber development
The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.
Doolittle, R. F.; Pollvogt, U.; Eskovitz, A. J.
Electrostatic Levitator Vacuum Chambers
Optical prots ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (the beam passes through the window at left), poisitioning lasers (one port is at center), and lamps (such as the deuterium arc lamp at right), and to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.
Optical prots ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (the beam passes through the window at left), poisitioning lasers (one port is at center), and lamps (arc lamp at right), and to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.
Electrostatic Levitator Vaccum Chamber
Optical ports ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (the beam passes through the window at left), positioning lasers (one port is at center), and lamps (such as the deuterium arc lamp at right), and to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.
Advanced thrust chamber designs
A regeneratively cooled thrust chamber has been designed and fabricated, consisting of an inner TD nickel liner which was spin formed, welded, and machined and an outer shell of electroformed nickel. Coolant channels were produced in the outer surface of the inner liner by the electric discharge machining process before electroforming the shell. Accessory manifolds and piping were attached by welding. Manufacturing processes employed are described.
Dietrich, F. J.; Leach, A. E.
Digital optical spark chambers
The authors constructed and tested a prototype digital readout system for optical spark chambers using a linear, solid-state charge-coupled-device detector array. Position resolution of 0.013 mm (sigma) over a 25-cm field of view has been demonstrated. It is concluded that this technique should permit the construction of economical, lightweight and low-power trajectory hodoscopes for use in cosmic-ray instrumentation on balloons and in spacecraft.
Evenson, Paul; Tuska, Evelyn
Recommendations for chamber quantification
Abstract Quantification of cardiac chamber size, ventricular mass and function ranks among,the most,clinically important,and most,frequently,requested,tasks of echocardiography. Over the last decades, echocardiographic methods and techniques haveimprovedandexpandeddramatically,duetotheintroductionofhigherfrequency transducers, harmonic imaging, fully digital machines, left-sided contrast agents, and other technological advancements. Furthermore, echocardiography due to its porta- bility and versatility is now used in emergency rooms, operating rooms, and intensive care units.
Roberto M. Lang; Michelle Bierig; Richard B. Devereux; Frank A. Flachskampf; Elyse Foster; Patricia A. Pellikka; Michael H. Picard; Mary J. Roman; James Seward; Jack Shanewise; Scott Solomon; Kirk T. Spencer; John Sutton; William Stewart
Engine combustion chamber structure
This patent describes a combustion chamber structure comprising an upper wall surface which is shaped like a pent-roof and into which an intake passage opens, a piston having on a head portion thereof a bulged portion conforming to the upper wall surface in shape, a first bowl portion which is formed substantially at the center of the bulged portion and which is substantially semispherical in shape, a pair of second bowl portions which respectively extend on opposite sides of the first bowl portion to the corresponding ends of the bulged portion of the piston along the edge of the bulged portion and are in communication with the first bowl portion, a swirl generating means which is adapted to generate a swirl of intake air in the combustion chamber when the engine load is light, and a spark plug disposed to substantially face the center of the first bowl portion from the upper wall surface; the swirl generating means being adapted to generate the swirl of intake air in a tangential direction in the combustion chamber; and the diameter of the first bowl portion being larger than the width of the second bowl portion.
Tanaka, H.
Vertical two chamber reaction furnace
A vertical two chamber reaction furnace is disclosed. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.
A critical assessment of the feasibility of IFE cham- bers has been initiated. This work seeks to define design windows and explore in detail the tradeoffs for various chamber concepts. The work is performed in an inte- grated and self-consistent manner by including all key elements of IFE chambers, including target physics, target injection and tracking, final optics interface, chamber
M. S. Tillack; F. Najmabadi; L. A. El-Guebaly; R. R. Peterson; D. T. Goodin; K. R. Schultz; W. R. Meier; J. Perkins; Lawrence Livermore; D. A. Petti; J. D. Sethian; L. M. Waganer
Effects of Chamber Geometry and Gas Properties on Hydrodynamic Evolution of IFE Chambers
The rep rate of an inertial fusion energy facility depends on the time-dependent response of the chamber environment between target ignitions. The fusion burn following the target ignition releases large quantities of energy into the chamber. This energy should be removed and the environment should be returned to a quiescent state so that the new fusion target can be positioned for the next cycle. Understanding the hydrodynamic transport of this energy through the chamber fill gas is essential because the multidimensional geometry effects become important on the long time scale, as the fluid interacts with the vessel wall containing various beam access ports. This interaction affects several different modes of the chamber species transport, including convection induced by shock waves and secondary flow, molecular diffusion, electron conductivity and radiation. In order to investigate these phenomena, we have developed SPARTAN code as an assembly of algorithms that were the most suitable for an accurate treatment of the computational problem, such as shock wave resolution and tracking, underlying flow physics and complex wall geometry. This study demonstrates that the geometry effects are critical in affecting the flow during the first 50 milliseconds following the target ignition. Thermal diffusion by molecules and free electrons has only a moderate effect in reducing the temperature extrema and is not sufficient to cool down the chamber to the equilibrium with the chamber wall within 100 ms. Radiation of the background plasma was identified as the only transport mechanism that has approached to this goal, making the chamber environment more suitable for inserting the next target.
Dragojlovic, Zoran; Najmabadi, Farrokh [University of California, San Diego (United States)
Multi-anode ionization chamber
The present invention includes a high-energy detector having a cathode chamber, a support member, and anode segments. The cathode chamber extends along a longitudinal axis. The support member is fixed within the cathode chamber and extends from the first end of the cathode chamber to the second end of the cathode chamber. The anode segments are supported by the support member and are spaced along the longitudinal surface of the support member. The anode segments are configured to generate at least a first electrical signal in response to electrons impinging thereon.
Bolotnikov, Aleksey E. (South Setauket, NY); Smith, Graham (Port Jefferson, NY); Mahler, George J. (Rocky Point, NY); Vanier, Peter E. (Setauket, NY)
LOX cooled thrust chamber technology developments
An experimental LOX heat-transfer study and a LOX-cooled thrust-chamber demonstration program are summarized. Heat transfer to supercritical oxygen was investigated at 17 to 34.5 MPa (2460 to 5000 psia), and heat fluxes up to 90 MW/sq m (55 Btu/sq in.-sec). Experimental data obtained previously were correlated along with these recent data, and a design equation was derived which correlates 95% of the data within + or - 30%. Liquid-oxygen-cooled thrust chambers have been designed using this correlation and are currently being fabricated. A test program is planned for evaluating the LOX-cooled design concept using NASA test facilities. The purpose of these tests is to verify the LOX cooling correlation in a high-pressure liquid rocket engine and to determine the effects of a LOX coolant leak.
Spencer, R. G.; Rousar, D. C.; Price, H. G.
Wire chambers revisited.
Detectors used for radioisotope imaging have, historically, been based on scintillating crystal/photomultiplier combinations in various forms. From the rectilinear scanner through to modern gamma cameras and positron cameras, the basic technology has remained much the same. Efforts to overcome the limitations of this form of technology have foundered on the inability to reproduce the required sensitivity, spatial resolution and sensitive area at acceptable cost. Multiwire proportional chambers (MWPCs) have long been used as position-sensitive charged particle detectors in nuclear and high-energy physics. MWPCs are large-area gas-filled ionisation chambers in which large arrays of fine wires are used to measure the position of ionisation produced in the gas by the passage of charged particles. The important properties of MWPCs are high-spatial-resolution, large-area, high-count-rate performance at low cost. For research applications, detectors several metres square have been built and small-area detectors have a charged particle resolution of 0.4 mm at a count rate of several million per second. Modification is required to MWPCs for nuclear medicine imaging. As gamma rays or X-rays cannot be detected directly, they must be converted into photo- or Compton scatter electrons. Photon-electron conversion requires the use of high atomic number materials in the body of the chamber. Pressurised xenon is the most useful form of "gas only" photon-electron convertor and has been used successfully in a gamma camera for the detection of gamma rays at energies below 100 keV. This camera has been developed specifically for high-count-rate first-pass cardiac imaging. This high-pressure xenon gas MWPC is the key to a highly competitive system which can outperform scintillator-based systems. The count rate performance is close to a million counts per second and the intrinsic spatial resolution is better than the best scintillator-based camera. The MWPC camera produces quantitative ejection fraction information of the highest quality. The detection of higher energy gamma rays has proved more problematical, needing a solid photon-electron convertor to be incorporated into the chamber. Several groups have been working on this problem with modest success so far. The only clinical detectors have been developed for positron emission tomography, where thin lead or lead-glass can provide an acceptable convertor for 511 keV photons. Two MWPC positron cameras have been evaluated clinically and one is now in routine use in clinical oncology. The problems of detection efficiency have not been solved by these detectors although reliability and large-area PET imaging have been proven.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8491229
Ott, R J
Anterior chamber keratinous horn.
A 14-year-old boy presented with a 6-month history of small white masses in his right eye. Examination revealed a white floating fluffy lesion and 2 vegetative hornlike white lesions originating at the periphery of the iris. On ultrasound biomicroscopy, a normal echogenic mass was detected on the inferior iris root and angle, with no posterior chamber or cilliary body involvement. Histopathology following an excisional biopsy revealed keratinous material. There was no recurrence during 10Āmonths of follow-up. PMID:24797250
Abrishami, Mojtaba; Ghassemi, Fariba; Vahedian, Zakieh
Automated protein crystal growth facility
A customer for the protein crystal growth facility fills the specially designed chamber with the correct solutions, fills the syringes with their quenching solutions, and submits the data needed for the proper growth of their crystal. To make sure that the chambers and syringes are filled correctly, a NASA representative may assist the customer. The data needed is the approximate growth time, the growth temperature, and the desired crystal size, but this data can be changed anytime from the ground, if needed. The chambers are gathered and placed into numbered slots in special drawers. Then, data is entered into a computer for each of the chambers. Technicians map out when each chamber's growth should be activated so that all of the chambers have enough time to grow. All of this data is up-linked to the space station when the previous growth session is over. Anti-vibrational containers need to be constructed for the high forces encountered during the lift off and the landing of the space shuttle, and though our team has not designed these containers, we do not feel that there is any reason why a suitable one could not be made. When the shuttle reaches the space station, an astronaut removes a drawer of quenched chambers from the growth facility and inserts a drawer of new chambers. All twelve of the drawers can be replaced in this fashion. The optical disks can also be removed this way. The old drawers are stored for the trip back to earth. Once inside the growth facility, a chamber is removed by the robot and placed in one of 144 active sites at a time previously picked by a technician. Growth begins when the chamber is inserted into an active site. Then, the sensing system starts to determine the size of the protein crystal. All during the crystal's growth, the customer can view the crystal and read all of the crystal's data, such as growth rate and crystal size. When the sensing system determines that the crystal has reached the predetermined size, the robot is told to pick up a syringe filled with the correct quenchant solution and inject it into the chamber to stop the crystal growth. The chamber is then removed from the active site and placed into its original storage slot. Another chamber is then placed into the active site and the process is repeated in all of the active sites until all of the chambers have complted their growth. After ninety days (the scheduled time between shuttle visits), the crystal growth is completed, and the old drawers are replaced with new ones. Once the customer extracts the crystals, the chambers are retrieved for future customers.
Donald, Stacey
A 'breadboard' biomass production chamber for CELSS
The Breadboard Project of the Controlled Ecological Life Support System (CELSS) Program is the first attempt by NASA to integrate the primary components of a bioregenerative life support system into a functioning system. The central component of this project is a Biomass Production Chamber (BPC). The BPC is under construction, and when finished will be sealed for the study of the flux of gases, liquids, and solids through the production module of a CELSS. Features of the CELSS breadboard facility will be covered as will design requirements for the BPC. Cultural practices developed for wheat for the BPC wil be discussed.
Prince, Ralph P.; Knott, William M., III; Hilding, Suzanne E.; Mack, Tommy L.
Validation of a Three-Dimensional Transmission Line Matrix (TLM) Model Implementation of a Mode-Stirred Reverberation Chamber
Reverberation chambers are attractive electromagnetic compatibility test facilities, both economically and technically. Careful design and analysis of these facilities are important, if the results obtained are to be treated with a high level of confidence. Numerical modeling is an important part of the process of reverberation chamber design and analysis. Hence, it is important that the modeling techniques to be
Alyse Coates; Hugh G. Sasse; Dawn E. Coleby; Alistair P. Duffy; Antonio Orlandi
Iran Chamber Society
In 2001, the Iran Chamber Society was created in order to provide a non-partisan, non-commercial, comprehensive source of information on Iran. The website's "About Us" section states that their aim is to "create a global awareness about Iranian society and eradicate the misunderstandings and misconceptions about Iranian society, and to play an educational role as well." Visitors will find the website divided up into "Art and Culture", "History", "Society" and "Iran's Guide". The "Exhibitions and Conferences" link on the right side of the homepage leads visitors to a number of exhibitions, including the fascinating "Artistic Murals of Tehran's Metro Stations", which offers a dozen pictures of the beautifully handcrafted murals made of pottery, metal, cement and other materials. The "History" section offers pictures and documents, including some disturbing graphic photos from the Iran-Iraq War in 1980-1988 that appear at the end of the Historic Periods and Events section.
Chambers's Book of Days
Subtitled A Miscellany of Popular Antiquities in connection with the Calendar, Chambers's Book of Days is essentially a collection of "On this Day" trivia, short pieces, and other interesting tidbits, including history, literature, biography, and "oddities of human life and character." Digitized by the University of Wisconsin-Madison Libraries, this electronic reprint may be browsed in page order or via a calendar navigator. The site offers a fun look into pop-history/ tabloid news of the late nineteenth century. For instance, I discovered that on the day of my birth in 1626 "a cod-fish was brought to Cambridge market, which upon being opened, was found to contain a book in its maw or stomach." An auspicious date to be born indeed.
The Juelich large Aerosol Chamber
The large Aerosol Chamber is designed for the investigation of nighttime atmospheric chemistry. The Aerosol Chamber is a dark chamber and is operated at ambient temperature and pressure conditions. It is constructed as a double wall system: a fully welded aluminum box (7m x 7m x 5.3m) and an equally sized fully heat sealed Teflon bag hanging from the ceiling.
Th. Mentel; A. Wahner; M. Folkers
Preparation, verification, and operational control of a large space-environment-simulation chamber for contamination sensitive tests
A 2-year program to prepare chamber A at the NASA Manned Spacecraft Center for Apollo telescope mount thermal-vacuum tests is discussed. This program covers modification to existing chamber systems, the development of facility and chamber operating procedures, the selection of chamber cleaning and control methods, and the development and evaluation of diagnostic instrumentation. Extensive efforts to ensure a minimum contamination environment for the Apollo telescope mount test series are illustrated. Recent thermal-vacuum tests of this chamber at progressive stages of cleanliness have demonstrated the success achieved in reducing the particulate and molecular contamination levels of the basic chamber interior.
Visentine, J. T.; Ogden, J. W.; Ritter, M. L.; Smith, C. F.
Aging tests of full scale CMS muon cathode strip chambers
Two CMS production Cathode Strip Chambers were tested for aging effects in the high radiation environment at the Gamma Irradiation Facility at CERN. The chambers were irradiated over a large area: in total, about 2.1 m{sup 2} or 700 m of wire in each chamber. The 40% Ar+50%CO{sub 2}+10%CF{sub 4} gas mixture was provided by an open-loop gas system for one of the chambers and by closed-loop recirculating gas system for the other. After accumulating 0.3-0.4 C per centimeter of a wire, which is equivalent to operation during about 30-50 years at the peak LHC luminosity, no significant changes in gas gain, chamber efficiency, and wire signal noise were observed for either of the two chambers. The only consistent signs of aging were a small increase in dark current from {approx}2 nA to {approx}10 nA per plane of 600 wires and a decrease of strip-to-strip resistance from 1000 G{Omega} to 10-100 G{Omega}. Disassembly of the chambers revealed deposits on the cathode planes, while the anode wires remained fairly clean.
D. Acosta et al.
Neutron Detection via Bubble Chambers
The results of a Pacific Northwest National Laboratory (PNNL) exploratory research project investigating the feasibility of fast neutron detection using a suitably prepared and operated, pressure-cycled bubble chamber are described. The research was conducted along two parallel paths. Experiments with a slow pressure-release Halon chamber at the Enrico Fermi Institute at the University of Chicago showed clear bubble nucleation sensitivity to an AmBe neutron source and insensitivity to the 662 keV gammas from a 137Cs source. Bubble formation was documented via high-speed (1000 frames/sec) photography, and the acoustic signature of bubble formation was detected using a piezo-electric transducer element mounted on the base of the chamber. The chamberÆs neutron sensitivity as a function of working fluid temperature was mapped out. The second research path consisted of the design, fabrication, and testing of a fast pressure-release Freon-134a chamber at PNNL. The project concluded with successful demonstrations of the PNNL chamberÆs AmBe neutron source sensitivity and 137Cs gamma insensitivity. The source response tests of the PNNL chamber were documented with high-speed photography.
Jordan, David V.; Ely, James H.; Peurrung, Anthony J.; Bond, Leonard J.; Collar, J. I.; Flake, Matthew; Knopf, Michael A.; Pitts, W. K.; Shaver, Mark W.; Sonnenschein, Andrew; Smart, John E.; Todd, Lindsay C.
The smog chamber facility of the University of North Carolina was used to provide experimental data for developing and testing kinetic mechanisms of photochemical smog formation. In this study, 128 pairs of experiments were performed using NOx and various hydrocarbons and hydroca...
An extensive aging study of bakelite Resistive Plate Chambers
We present recent results of an extensive aging test, performed at the CERN Gamma Irradiation Facility, on two bakelite Resistive Plate Chambers (RPC) detectors. With a method based on a model describing the behavior of an RPC exposed to a large particle flux, we have periodically measured the electrode resistivity ? of the two detectors over 3 years. We observed
G. Carboni; S. De Capua; D. Domenici; G. Ganis; R. Messi; G. Passaleva; E. Santovetti; M. Veltri
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
13. VIEW OF VACUUM CHAMBER AND WELDING EQUIPMENT IN MODULE E. PARTS WERE WELDED UNDER A VACUUM TO PREVENT CORROSION. (11/6/73) - Rocky Flats Plant, Plutonium Manufacturing Facility, North-central section of Plant, just south of Building 776/777, Golden, Jefferson County, CO
14. VIEW OF VACUUM COATING CHAMBER. THE SYSTEM USED TITANIUM VAPORS TO DEPOSIT TITANIUM COATING ONTO URANIUM PARTS UNDER A VACUUM. (1/11/83) - Rocky Flats Plant, Non-Nuclear Production Facility, South of Cottonwood Avenue, west of Seventh Avenue & east of Building 460, Golden, Jefferson County, CO
Chamber challenges: the necessity of objective observation.
the specialty of Allergy-Immunology has used human challenge testing procedures to test theories of causal relationships for decades. This includes highly characterized airborne allergens and chemicals with allergic sensitization potential. The utility of such testing to establish allergic sensitivity is well accepted. The causal relationship of chemical exposure and myriad clinical syndromes is a very contentious issue. The completion of the challenge chamber facility at EPA's Human Exposure Research Facility presents a grand opportunity for government investigators to work harmoniously with other government investigators in an effort to bring the redeeming spotlight of scientific discipline to the testy considerations of multiple chemical sensitivity, chronic fatigue, and Gulf War illness phenomena. PMID:8921562
Selner, J C
Results about HF production and bakelite analysis for the CMS Resistive Plate Chambers
The formation of reactive compounds in the gas mixture during Resistive Plate Chambers (RPCs) operation at the CERN Gamma Irradiation Facility (GIF) is studied. Results from two different types of chambers are discussed: 50ū50cm2 RPC prototypes and two final CMS-RB1 chambers. The RB1 detectors were also connected to a closed loop gas system. Gas composition and possible additional impurities have
M. Abbrescia; A. Colaleo; R. Guida; G. Iaselli; F. Loddo; M. Maggi; B. Marangelli; S. Natali; S. Nuzzo; G. Pugliese; A. Ranieri; F. Romano; G. Roselli; R. Trentadue; S. Tupputi; N. Cavallo; F. Fabozzi; P. Paolucci; D. Piccolo; G. Polese; C. Sciacca; G. Belli; M. Necchi; S. Ratti; C. Riccardi; P. Torre; P. Vitulo; T. Anguelov; V. Genchev; B. Panev; S. Piperov; G. Sultanov; P. Vankov; A. Dimitrov; L. Litov; B. Pavlov; P. Petkov
The smog chamber facilities of the University of California, Riverside were used to collect experimental data to assess the effects of multi-day irradiations on photochemical oxidant formation. This volume includes documentation on the computer-readable magnetic tape that contain...
A large high vacuum, high pumping speed space simulation chamber for electric propulsion
Testing high power electric propulsion devices poses unique requirements on space simulation facilities. Very high pumping speeds are required to maintain high vacuum levels while handling large volumes of exhaust products. These pumping speeds are significantly higher than those available in most existing vacuum facilities. There is also a requirement for relatively large vacuum chamber dimensions to minimize facility wall/thruster plume interactions and to accommodate far field plume diagnostic measurements. A 4.57 m (15 ft) diameter by 19.2 m (63 ft) long vacuum chamber at NASA Lewis Research Center is described. The chamber utilizes oil diffusion pumps in combination with cryopanels to achieve high vacuum pumping speeds at high vacuum levels. The facility is computer controlled for all phases of operation from start-up, through testing, to shutdown. The computer control system increases the utilization of the facility and reduces the manpower requirements needed for facility operations.
Grisnik, Stanley P.; Parkes, James E.
Interim Total Containment Test Fire Facility, Pantex Plant, Amarillo, Texas
This report documents the results of a test program conducted within a confinement chamber called the Interim Total Containment Test Fire Facility. The objective was to determine the effectiveness of the chamber to contain the blast loads and hazardous fragments generated by the largest high explosive (HE) charge expected to be fired within the chamber. 11 references, 7 figures, 5
A. G. Papp; J. L. Nunley; G. T. West
X-ray diagnostics for laser plasma interaction in the target chamber of the LIL
The main features of x ray diagnostics for laser plasma interaction in the target chamber of the LIL will be presented. The LIL facility(Ligne dIntķgration Laser) is located at CEA CESTA near Bordeaux in France. First laser shots at 3 w were beginning 2003. The x ray diagnostics are now being installed on the target chamber. They include: an x
Charles Reverdin; B. Angelier; J. L. Bourgade; J. Y. Boutin; M. Briat; G. Charles; A. Estadieu; D. Gontier; J. P. Le Breton; G. Lidove; B. Marchet; R. Marmoret; P. Millier; C. Remond; R. Rosch; G. Soullie; P. Stemmler; P. Troussel; B. Villette; R. Wrobel
Numerical study of a UWB dual-polarized feed design for enhanced tapered chambers
A tapered chamber is a facility to provide the quiet zone environment necessary for the accurate measurement of antenna radiation patterns and the radar cross sections (RCS) of targets. A crucial aspect to be considered in any tapered chamber design is that the launching field (feed) antenna should provide a uniform amplitude and phase distribution throughout the test zone. A
Kwan-ho Lee; Chi-Chih Chen; F. L. Teixeira; R. Lee
Fire safety in hyperbaric chambers
The effects of pressure upon combustion and equipment performance place severe requirements on fire protection systems that\\u000a might be suitable for use in manned hyperbaric chambers. Adequate systems do exist, however; and we can look for improvements\\u000a in these as the use of hyperbaric chambers grows in the years to come.
Lester A. Eggleston
A versatile flammability test chamber
Relatively inexpensive test chamber safely tests flammability of most materials while allowing constant observation of test. Chamber can be used at various pressures, under controlled atmosphere, and is equipped with probes to vary distance from heat source to test object or to move it for observation from several different angles.
Springfield, C. L.; Paton, W. J.; Jeter, J. D.
Spark chamber track finding program
A spark-chamber track-finding program has been written. The accuracy of the location of the track is good, and if the chamber contains many spurious sparks the computation time is much less than the time used by a least-squares fit routine. Multiple tracks can be found and interaction vertices can thereby be determined.
Arens, J. F.
Chamber Music: Skills and Teamwork.
Focuses on the benefits of participating in chamber music ensembles, such as the development of a heightened level of awareness, and considers the role of the music educator/conductor. Provides tools and exercises that teachers can introduce to chamber music players to improve their rehearsals and performances. (CMK)
Villarrubia, Charles
Anterior chamber depth during hemodialysis
Background Exacerbation of chronic glaucoma or acute glaucoma is occasionally observed in patients undergoing hemodialysis (HD) because of anterior chamber depth changes during this therapy. Purpose To evaluate anterior chamber depth and axial length in patients during HD sessions. Methods A total of 67 eyes of 35 patients were prospectively enrolled. Axial length and anterior chamber depth were measured using ultrasonic biometry, and these measures were evaluated at three different times during HD sessions. Body weight and blood pressure pre- and post-HD were also measured. Results There was no difference in the axial length between the three measurements (P = 0.241). We observed a significantly decreased anterior chamber depth (P = 0.002) during HD sessions. Conclusion Our results support the idea that there is a change in anterior chamber depth in HD sessions.
Gracitelli, Carolina Pelegrini Barbosa; Stefanini, Francisco Rosa; Penha, Fernando; Goes, Miguel Angelo; Draibe, Sergio Antonio; Canziani, Maria Eugenia; Junior, Augusto Paranhos
Space Simulation Facilities at IAL Space.
The thermal vacuum facilities of IAL SPACE were tailored for testing of the ESA payloads. They were progressively upgraded for cryogenic payloads including 4 K (liquid helium temperature) experiments. A detailed review of the three vacuum chambers, rangin...
M. Henrist A. Cucchiaro I. Domken J. P. Macau
Starting a High School Chamber Music Group.
Presents ideas on how to begin a chamber music ensemble. Discusses how to find time to accomplish chamber music playing in and around the school day. Presents short descriptions of chamber music that can be used with ensembles. Includes chamber music resources and additional chamber works. (CMK)
Rutkowski, Joseph
An altitude chamber rescue ensemble
Altitude chamber tests accomplished with the astronaut crews in the spacecraft at a simulated altitude of above 200,000 ft requires that a rescue team be provided in the event of an accident in the spacecraft. The rescue crew is stationed in an airlock maintained at an altitude of 18,000 ft. A protective ensemble provides the rescue crew with life support capabilities, communications, and protection in the event of an emergency. In the event of an emergency, repressurization of the chamber is initiated; as the chamber descends, the airlock ascends and the two meet at 25,000 ft. This phase of the emergency repressurization takes less than 30 sec.
Lloyd, R. P.
Computer Simulation of a Hyperbaric Chamber Environment.
A hyperbaric chamber environment is simulated using a FORTRAN computer program. This program allows the user to input data files of varying chamber conditions and provides a detailed output which can be used for design or chamber operations. Specifically,...
S. R. Lister
Cyclically controlled welding purge chamber
An arrangement for butt-welding cylindrical sections of large, thin-wall tanks includes a rotatable mandrel with side-by-side sets of radial position adjusters. Each set of adjusters bears on one of the tank sections adjacent the seam, to prevent the sections from sagging out-of-round. The mandrel rotates relative to the welder, so that a continuous seam is formed. A purge chamber is fixed in position behind the seam at the weld head, and is flushed with inert gas. The purge chamber includes a two-sided structure which is contiguous with the cylindrical sections and a circumferential vane to form an open-ended tube-like structure, through which the radial position adjusters pass as the mandrel and cylindrical workpiece sections rotate. The tube-like structure is formed into a chamber by a plurality of movable gates which are controlled to maintain a seal while allowing adjusters to progress through the purge chamber.
Gallagher, Robert L. (Inventor)
Extra Terrestrial Environmental Chamber Design
A vacuum chamber designed to simulate the dusty environment on the Moon or Mars has been built for Goddard Space Flight Center. The path from concept to delivery is reviewed, with lessons learned and pitfalls highlighted along the way.
Hughes, David W.
The Mark III vertex chamber
The design and construction of the new Mark III vertex chamber is described. Initial tests with cosmic rays prove the ability of track reconstruction and yield triplet resolutions below 50 ..mu..m at 3 atm using argon\\/ethane (50:50). Also performed are studies using a prototype of a pressurized wire vertex chamber with 8 mm diameter straw geometry. Spatial resolution of 35mm
J. Adler; T. Bolton; K. Bunnell; R. Cassell; E. Cheu; T. Freese; C. Grab; G. Mazaheri; R. Mir; A. Odian
Light diffusing fiber optic chamber
A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.
Maitland, Duncan J. (Lafayette, CA)
Investigation of the applicability of a special parallel-plate ionization chamber for x-ray beam dosimetry
Diagnostic x-rays are the greatest source of exposition to ionizing radiation of the population worldwide. In order to obtain accurate and lower-cost dosimeters for quality control assurance of medical x-ray facilities, a special ionization chamber was designed at the Calibration Laboratory of the IPEN, for dosimetry in diagnostic radiology beams. For the chamber characterization some tests were undertaken. Monte Carlo simulations were proposed to evaluate the distribution of the deposited energy in the sensitive volume of the ionization chamber and the collecting electrode effect on the chamber response. According to the obtained results, this special ionization chamber presents potential use for dosimetry of conventional diagnostic radiology beams.
Perini, Ana P.; P. Neves, Lucio; E. Caldas, Linda V.
A comparison of the acoustic and aerodynamic measurements of a model rotor tested in two anechoic wind tunnels
Two aeroacoustic facilities - the CEPRA 19 in France and the DNW in the Netherlands - are compared. The two facilities have unique acoustic characteristics that make them appropriate for acoustic testing of model-scale helicopter rotors. An identical pressure-instrumented model-scale rotor was tested in each facility and acoustic test results are compared with full-scale-rotor test results. Blade surface pressures measured in both tunnels were used to correlated nominal rotor operating conditions in each tunnel, and also used to assess the steadiness of the rotor in each tunnel's flow. In-the-flow rotor acoustic signatures at moderate forward speeds (35-50 m/sec) are presented for each facility and discussed in relation to the differences in tunnel geometries and aeroacoustic characteristics. Both reports are presented in appendices to this paper.
Boxwell, D. A.; Schmitz, F. H.; Splettstoesser, W. R.; Schultz, K. J.; Lewy, S.
Two aeroacoustic facilities--the CEPRA 19 in France and the DNW in the Netherlands--are compared. The two facilities have unique acoustic characteristics that make them appropriate for acoustic testing of model-scale helicopter rotors. An identical pressure-instrumented model-scale rotor was tested in each facility and acoustic test results are compared with full-scale-rotor test results. Blade surface pressures measured in both tunnels were used to correlated nominal rotor operating conditions in each tunnel, and also used to assess the steadiness of the rotor in each tunnel's flow. In-the-flow rotor acoustic signatures at moderate forward speeds (35-50 m/sec) are presented for each facility and discussed in relation to the differences in tunnel geometries and aeroacoustic characteristics. Both reports are presented in appendices to this paper. ;.);
Boxwell, D. A.; Schmitz, F. H.; Splettstoesser, W. R.; Schultz, K. J.; Lewy, S.; Caplot, M.
A radon-daughter chamber was constructed at the US Department of Energy (DOE) Grand Junction Projects Office (GJPO) facility for the purpose of calibrating, testing and evaluating radon and radon-daughter measuring instruments used in support of DOE remedial action programs. The chamber is an environmentally controlled cylindrical vessel through which air containing radon can be circulated. Environmental parameters within the chamber and their respective controllable ranges include radon concentration (1 to 1000 pCi/1), ventilation rate (0.25 to 10 air changes per hour), temperature (0 to 45/sup 0/C), dew point (-10/sup 0/C to saturated), and condensation-nuclei concentration (10 to 10/sup 6//cm/sup 3/).
Langner, G.H. Jr.; Nelson, T.
Emulsion Chamber Technology Experiment (ECT)
The experimental objective of Emulsion Chamber Technology (ECT) was to develop space-borne emulsion chamber technology so that cosmic rays and nuclear interactions may subsequently be studied at extremely high energies with long exposures in space. A small emulsion chamber was built and flown on flight STS-62 of the Columbia in March 1994. Analysis of the several hundred layers of radiation-sensitive material has shown excellent post-flight condition and suitability for cosmic ray physics analysis at much longer exposures. Temperature control of the stack was 20 +/-1 C throughout the active control period and no significant deviations of temperature or pressure in the chamber were observed over the entire mission operations period. The unfortunate flight attitude of the orbiter (almost 90% Earth viewing) prevented any significant number of heavy particles (Z greater than or equal to 10) reaching the stack and the inverted flow of shower particles in the calorimeter has not allowed evaluation of absolute primary cosmic ray-detection efficiency nor of the practical time limits of useful exposure of these calorimeters in space to the level of detail originally planned. Nevertheless, analysis of the observed backgrounds and quality of the processed photographic and plastic materials after the flight show that productive exposures of emulsion chambers are feasible in low orbit for periods of up to one year or longer. The engineering approaches taken in the ECT program were proven effective and no major environmental obstacles to prolonged flight are evident.
Gregory, John C.; Takahashi, Yoshiyuki
Plasma chemistry in wire chambers
The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.
Wise, J.
Cone crusher chamber optimization using multiple constraints
The chamber geometry is one of the key factors that influences the performance of a cone crusher. The design of the chamber geometry should take product quality and crushing efficiency into account. In this paper the kinematics of rock material in a crushing chamber, as interparticle breakage occurs, has been analyzed and the chamber division is achieved. Based on the
Dong Gang; Huang Dongming; Fan Xiumin
Central and forward tracking chambers of CDF
The Collider Detector at Fermilab is currently studying 1.8 TeV pp interactions at the Fermilab Tevatron. This paper describes the design and construction of the detector's tracking chambers in the light of the measurement requirements dictated by physics goals. The chambers described are the Forward Tracking Chamber, the Central Tracking Chamber, the Central Drift Tubes, and the Vertex Time Projection
R. L. Wagner
Evaluation of Impinging Stream Vortex Chamber Concepts for Liquid Rocket Engine Applications
To pursue technology developments for future launch vehicles, NASA/Marshall Space Flight Center (MSFC) is examining vortex chamber concepts for liquid rocket engine applications. Past studies indicated that the vortex chamber schemes potentially have a number of advantages over conventional chamber methods. Due to the nature of the vortex flow, relatively cooler propellant streams tend to flow along the chamber wall. Hence, the thruster chamber can be operated without the need of any cooling techniques. This vortex flow also creates strong turbulence, which promotes the propellant mixing process. Consequently, the subject chamber concepts not only offer system simplicity, but also enhance the combustion performance. Test results have shown that chamber performance is markedly high even at a low chamber length-to-diameter ratio (LD). This incentive can be translated to a convenience in the thrust chamber packaging. Variations of the vortex chamber concepts have been introduced in the past few decades. These investigations include an ongoing work at Orbital Technologies Corporation (ORBITEC). By injecting the oxidizer tangentially at the chamber convergence and fuel axially at the chamber head end, Knuth et al. were able to keep the wall relatively cold. A recent investigation of the low L/D vortex chamber concept for gel propellants was conducted by Michaels. He used both triplet (two oxidizer orifices and one fuel orifice) and unlike impinging schemes to inject propellants tangentially along the chamber wall. Michaels called the subject injection scheme an Impinging Stream Vortex Chamber (ISVC). His preliminary tests showed that high performance, with an Isp efficiency of 9295, can be obtained. MSFC and the U. S. Army are jointly investigating an application of the ISVC concept for the cryogenic oxygen/hydrocarbon propellant system. This vortex chamber concept is currently tested with gel propellants at AMCOM at Redstone Arsenal, Alabama. A version of this concept for the liquid oxygen (LOX) hydrocarbon fuel (RP-1) system has been derived from the one for the gel propellant. An unlike impinging injector was employed to deliver the propellants to the chamber. MSFC is also conducting an alternative injection scheme, called the chasing injector, associated with this vortex chamber concept. In this injection technique, both propellant jets and their impingement point are in the same chamber cross-sectional plane. Long duration tests (approximately up to 15 seconds) will be conducted on the ISVC to study the thermal effects. This paper will report the progress of the subject efforts at NASA Marshall Space Flight Center. Thrust chamber performance and thermal wall compatibility will be evaluated. The chamber pressures, wall temperatures, and thrust will be measured as appropriate. The test data will be used to validate CFD models, which, in turn, will be used to design the optimum vortex chambers. Measurements in the previous tests showed that the chamber pressures vary significantly with radius. This is due to the existence of the vortices in the chamber flow field. Hence, the combustion efficiency may not be easily determined from chamber pressure. For this project, measured thrust data will be collected. The performance comparison will be in terms of specific impulse efficiencies. In addition to the thrust measurements, several pressure and temperature readings at various locations on the chamber head faceplate and the chamber wall will be made. The first injector and chamber were designed and fabricated based on the available data and experience gained during gel propellant system tests by the U.S. Army. The alternate injector for the ISVC was also fabricated. Hot-fire tests of the vortex chamber are about to start and are expected to complete in February of 2003 at the TS115 facility of MSFC.
Trinh, Huu P.; Bullard, Brad; Kopicz, Charles; Michaels, Scott
Holography in small bubble chambers
This chapter reports on an experiment to determine the total charm cross section at different incident momenta using the small, heavy liquid bubble chamber HOBC. Holography in liquid hydrogen is also tested using the holographic lexan bubble chamber HOLEBC with the aim of preparing a future holographic experiment in hydrogen. The high intensity tests show that more than 100 incident tracks per hologram do not cause a dramatic effect on the picture quality. Hydrogen is more favorable than freon as the bubble growth is much slower in hydrogen. An advantage of holography is to have the maximum resolution in the full volume of the bubble chamber, which allows a gain in sensitivity by a factor of 10 compared to classical optics as 100 tracks per hologram look reasonable. Holograms are not more difficult to analyze than classical optics high-resolution pictures. The results show that holography is a very powerful technique which can be used in very high resolution particle physics experiments.
Lecoq, P.
Annular-Cross-Section CFE Chamber
Proposed continuous-flow-electrophoresis (CFE) chamber of annular cross section offers advantages over conventional CFE chamber, and wedge-cross-section chamber described in "Increasing Sensitivity in Continuous-Flow Electrophoresis" (MFS-26176). In comparison with wedge-shaped chamber, chamber of annular cross section virtually eliminates such wall effects as electro-osmosis and transverse gradients of velocity. Sensitivity enhanced by incorporating gradient maker and radial (collateral) flow.
Sharnez, Rizwan; Sammons, David W.
This article describes the design, manufacture and treatment of the bending vacuum chamber (B-chamber) of the 3-GeV Taiwan Photon Source (TPS). The B-chamber is a aluminium-alloy chamber ~5 m long with an antechamber on the near side of the beam duct. The design of the B-chamber is aimed to diminish the power density and the photon-stimulated desorption (PSD) induced by
C. K. Chan; G. Y. Hsiung; C. C. Chang; Y. B. Chen; C. Y. Yang; C. L. Chen; H. P. Hsueh
Blogs are Echo Chambers: Blogs are Echo Chambers
In the last decade, blogs have exploded in number, popularity and scope. However, many commentators and researchers speculate that blogs isolate readers in echo chambers, cutting them off from dissenting opin- ions. Our empirical paper tests this hypothesis. Using a hand-coded sample of over 1,000 comments from 33 of the world's top blogs, we find that agreement out- numbers disagreement
Eric Gilbert; Tony Bergstrom; Karrie Karahalios
Laboratory Course on Drift Chambers
Drift chambers play an important role in particle physics experiments as tracking detectors. We started this laboratory course with a brief review of the theoretical background and then moved on to the the experimental setup which consisted of a single-sided, single-cell drift chamber. We also used a plastic scintillator paddle, standard P-10 gas mixture (90% Ar, 10% CH4) and a collimated 90Sr source. During the laboratory session the students performend measurements of the following quantities: a) drift velocities and their variations as function of the drift field; b) gas gains and c) diffusion of electrons as they drifted in the gas.
Garcia-Ferreira, Ix-B.; Garcia-Herrera, J.; Villasenor, L. [Institute of Physics and Mathematics, University of Michoacan, Bdg. C3-Ciudad Universitaria, Morelia, Michoacan, 58040 (Mexico)
Double window viewing chamber assembly
A viewing chamber which permits observation of a sample retained therein includes a pair of double window assemblies mounted in opposed openings in the walls thereof so that a light beam can directly enter and exit from the chamber. A flexible mounting arrangement for the outer windows of the window assemblies enables the windows to be brought into proper alignment. An electrical heating arrangement prevents fogging of the outer windows whereas desiccated air in the volume between the outer and inner windows prevents fogging of the latter.
Keller, V. W. (inventor); Owen, R. B. (inventor); Elkins, B. R. (inventor); White, W. T. (inventor)
USGS Publications Warehouse
A geologic and geochemical investigation of the Chambers Ferry Roadless Area, Texas was conducted. The area has probable mineral-resource potential for oil and gas and for lignite. No metallic or additional energy resources were identified in the investigation. Detailed analyses of well logs from the vicinity of the Chambers Ferry Roadless Area, in conjunction with seismic data, are necessary to determine if the subsurface stratigraphy and structure are favorable for the accumulation of oil and gas. A shallow drilling program involving coring on a close-space grid is necessary for determination of the rank and continuity of seams of lignitic sediments in the area.
Houser, B. B.; Ryan, George, S.
Thermal System Upgrade of the Space Environment Simulation Test Chamber
The paper deals with the refurbishing and upgrade of the thermal system for the existing thermal vacuum test facility, the Space Environment Simulator, at NASA's Goddard Space Flight Center. The chamber is the largest such facility at the center. This upgrade is the third phase of the long range upgrade of the chamber that has been underway for last few years. The first phase dealt with its vacuum system, the second phase involved the GHe subsystem. The paper describes the considerations of design philosophy options for the thermal system; approaches taken and methodology applied, in the evaluation of the remaining "life" in the chamber shrouds and related equipment by conducting special tests and studies; feasibility and extent of automation, using computer interfaces and Programmable Logic Controllers in the control system and finally, matching the old components to the new ones into an integrated, highly reliable and cost effective thermal system for the facility. This is a multi-year project just started and the paper deals mainly with the plans and approaches to implement the project successfully within schedule and costs.
Desai, Ashok B.
Lightweight Chambers for Thrust Assemblies
The Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) has successfully applied new materials and fabrication techniques to create actively cooled thrust chambers that operate 200-400 degrees hotter and weigh 50% lighter than conventional designs. In some vehicles, thrust assemblies account for as much as 20% of the engine weight. So, reducing the weight of these components and increasing their operating range will benefit many engines and vehicle designs, including Reusable Launch Vehicle (RLV) concepts. Obviously, copper and steel alloys have been used successfully for many years in the chamber components of thrust assemblies. Yet, by replacing the steel alloys with Polymer Matrix Composite (PMC) and/or Metal Matrix Composite (MMC) materials, design weights can be drastically reduced. In addition, replacing the traditional copper alloys with a Ceramic Matrix Composite (CMC) or an advanced copper alloy (Cu-8Cr-4Nb, also known as GRCop-84) significantly increases allowable operating temperatures. Several small MMC and PMC demonstration chambers have recently been fabricated with promising results. Each of these designs included GRCop-84 for the cooled chamber liner. These units successfully verified that designs over 50% lighter are feasible. New fabrication processes, including advanced casting technology and a low cost vacuum plasma spray (VPS) process, were also demonstrated with these units. Hot-fire testing at MSFC is currently being conducted on the chambers to verify increased operating temperatures available with the GRCop-84 liner. Unique CMC chamber liners were also successfully fabricated and prepared for hot-fire testing. Yet, early results indicate these CMC liners need significantly more development in order to use them in required chamber designs. Based on the successful efforts with the MMC and PMC concepts, two full size "lightweight" chambers are currently being designed and fabricated for hot-fire testing at MSFC in 2001. These "full size" chambers will be similar in size to those used on the X33 engine (RS2200). One will be fabricated with a MMC structural jacket, while the other uses a PMC jacket. Each will be designed for thrust levels of 15,000 pounds in an oxygen/hydrogen environment with liquid hydrogen coolant. Both chambers will use GRCop-84 for its channel wall liner. Each unit is expected to be at least 60% lighter than a conventional design with traditional materials. Hot-fire testing on the full size units in late 2001 will directly compare performance results between a conventional chamber design and these "lightweight" alternatives. The technology developed and demonstrated by this effort will not only benefit next generation RLV programs, but it can be applied to other existing and future engine programs, as well. Efforts were sponsored by the Advanced Space Transportation Program for RLV Focused Technologies. The task team was led by MSFC with additional members from NASA-Glenn Research Center and the Rocketdyne Division of The Boeing Company. Specific materials development and fabrication processes were provided by Aerojet, Lockheed Martin Astronautics, Composite Optics, Inc., Hyper-Therm, Ceramic Composites, Inc., MSE Technology Applications, and Plasma Processes, Inc.
Elam, Sandra K.; Lee, Jonathan; Holmes, Richard; Zimmerman, Frank; Effinger, Mike; Turner, James E. (Technical Monitor)
Space simulation facilities providing a stable thermal vacuum facility
CBI has recently constructed the Intermediate Thermal Vacuum Facility. Built as a corporate facility, the installation will first be used on the Boost Surveillance and Tracking System (BSTS) program. It will also be used to develop and test other sensor systems. The horizontal chamber has a horseshoe shaped cross section and is supported on pneumatic isolators for vibration isolation. The chamber structure was designed to meet stability and stiffness requirements. The design process included measurement of the ambient ground vibrations, analysis of various foundation test article support configurations, design and analysis of the chamber shell and modal testing of the chamber shell. A detailed 3-D finite element analysis was made in the design stage to predict the lowest three natural frequencies and mode shapes and to identify local vibrating components. The design process is described and the results are compared of the finite element analysis to the results of the field modal testing and analysis for the 3 lowest natural frequencies and mode shapes. Concepts are also presented for stiffening large steel structures along with methods to improve test article stability in large space simulation facilities.
Tellalian, Martin L.
Recent Enhancements to the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility
The Structural Acoustics Loads and Transmission (SALT) facility at the NASA Langley Research Center is comprised of an anechoic room and a reverberant room, and may act as a transmission loss suite when test articles are mounted in a window connecting the two rooms. In the latter configuration, the reverberant room acts as the noise source side and the anechoic room as the receiver side. The noise generation system used for qualification testing in the reverberant room was previously shown to achieve a maximum overall sound pressure level of 141 dB. This is considered to be marginally adequate for generating sound pressure levels typically required for launch vehicle payload qualification testing. Recent enhancements to the noise generation system increased the maximum overall sound pressure level to 154 dB, through the use of two airstream modulators coupled to 35 Hz and 160 Hz horns. This paper documents the acoustic performance of the enhanced noise generation system for a variety of relevant test spectra. Additionally, it demonstrates the capability of the SALT facility to conduct transmission loss and absorption testing in accordance with ASTM and ISO standards, respectively. A few examples of test capabilities are shown and include transmission loss testing of simple unstiffened and built up structures and measurement of the diffuse field absorption coefficient of a fibrous acoustic blanket.
Rizzi, Stephen A.; Cabell, Randolph H.; Allen, Albert R.
Eyelash in the anterior chamber.
We present the case of a patient who had surgery for cataract extraction by phacoemulsification method and that the first day after surgery one lash was found in the anterior chamber of the eye. The lash was removed the same day, the postoperative refraction being 1.0. Starting from this case, therapeutic attitude is presented in different intracameral foreign bodies. PMID:20361650
Vßmosi, P; Horvath, Karin
Simulation of Layered Magma Chambers.
The principles of magma addition and liquid layering in magma chambers can be demonstrated by dissolving colored crystals. The concepts of density stratification and apparent lack of mixing of miscible liquids is convincingly illustrated with hydrous solutions at room temperature. The behavior of interstitial liquids in "cumulus" piles can beģ
Cawthorn, Richard Grant
Injector/Chamber Scaling Evaluation.
This report describes the results of the testing performed at the Air Force Rocket Propulsion Laboratory. The purpose of this program was to demonstrate the performance, stability, injector/chamber compatibility and long-duration operation of low-cost sca...
R. A. Silver
Chamber Clearing First Principles Modeling
LIFE fusion is designed to generate 37.5 MJ of energy per shot, at 13.3 Hz, for a total average fusion power of 500 MW. The energy from each shot is partitioned among neutrons ({approx}78%), x-rays ({approx}12%), and ions ({approx}10%). First wall heating is dominated by x-rays and debris because the neutron mean free path is much longer than the wall thickness. Ion implantation in the first wall also causes damage such as blistering if not prevented. To moderate the peak-pulse heating, the LIFE fusion chamber is filled with a gas (such as xenon) to reduce the peak-pulse heat load. The debris ions and majority of the x-rays stop in the gas, which re-radiates this energy over a longer timescale (allowing time for heat conduction to cool the first wall sufficiently to avoid damage). After a shot, because of the x-ray and ion deposition, the chamber fill gas is hot and turbulent and contains debris ions. The debris needs to be removed. The ions increase the gas density, may cluster or form aerosols, and can interfere with the propagation of the laser beams to the target for the next shot. Moreover, the tritium and high-Z hohlraum debris needs to be recovered for reuse. Additionally, the cryogenic target needs to survive transport through the gas mixture to the chamber center. Hence, it will be necessary to clear the chamber of the hot contaminated gas mixture and refill it with a cool, clean gas between shots. The refilling process may create density gradients that could interfere with beam propagation, so the fluid dynamics must be studied carefully. This paper describes an analytic modeling effort to study the clearing and refilling process for the LIFE fusion chamber. The models used here are derived from first principles and balances of mass and energy, with the intent of providing a first estimate of clearing rates, clearing times, fractional removal of ions, equilibrated chamber temperatures, and equilibrated ion concentrations for the chamber. These can be used to scope the overall problem and provide input to further studies using fluid dynamics and other more sophisticated tools.
Loosmore, G
Measurement of ionization chamber absorbed dose k{sub Q} factors in megavoltage photon beams
Purpose: Absorbed dose beam quality conversion factors (k{sub Q} factors) were obtained for 27 different types of ionization chamber. The aim was to obtain objective evidence on the performance of a wide range of chambers currently available, and potentially used for reference dosimetry, and to investigate the accuracy of the k{sub Q} calculation algorithm used in the TG-51 protocol. Methods: Measurements were made using the {sup 60}Co irradiator and Elekta Precise linac facilities at the National Research Council of Canada. The objective was to characterize the chambers over the range of energies applicable to TG-51 and determine whether each chamber met the requirements of a reference-class instrument. Chamber settling, leakage current, ion recombination and polarity, and waterproofing sleeve effects were investigated, and absorbed dose calibration coefficients were obtained for {sup 60}Co and 6, 10, and 25 MV photon beams. Only thimble-type chambers were considered in this investigation and were classified into three groups: (i) Reference chambers (''standard''0.6 cm{sup 3} Farmer-type chambers and their derivatives traditionally used for beam output calibration); (ii) scanning chambers (typically 0.1 cm{sup 3} volume chambers used for beam commissioning with 3-D scanning phantoms); and (iii) microchambers (very small volume ion chambers ({<=}0.01 cm{sup 3}) used for small field dosimetry). Results: As might be expected, 0.6 cm{sup 3} thimble chambers showed the most predictable performance and experimental k{sub Q} factors were obtained with a relative uncertainty of 0.1%. The performance of scanning and microchambers was somewhat variable. Some chambers showed very good behavior but others showed anomalous polarity and recombination corrections that are not fully explained at present. For the well-behaved chambers, agreement between measured and calculated k{sub Q} factors was within 0.4%; for some chambers, differences of more than 1% were seen that may be related to the recombination/polarity results. Use of such chambers could result in significant errors in the determination of reference dose in the clinic. Conclusions: Based on the experimental evidence obtained here, specification for a reference-class ionization chamber could be developed that would minimize the error in using a dosimetry protocol with calculated beam quality conversion factors. The experimental k{sub Q} data obtained here for a wide range of thimble chambers can be used when choosing suitable detectors for reference dosimetry and are intended to be used in the upcoming update/addendum to the AAPM TG-51 dosimetry protocol.
McEwen, Malcolm R. [Institute for National Measurement Standards, National Research Council of Canada, Ottawa, Ontario K1A 0R6 (Canada)
Hydrostatic Hyperbaric Chamber Ventilation System
The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.
Sarguisingh, Miriam J.
A molecular beam epitaxy facility for in situ neutron scattering
A molecular beam epitaxy (MBE) facility has been built to enable in situ neutron scattering measurements during growth of epitaxial layers. While retaining the full capabilities of a research MBE chamber, this facility has been optimized for polarized neutron reflectometry measurements. Optimization includes a compact lightweight portable design, a neutron window, controllable magnetic field, deposition across a large 76 mm diameter sample with exceptional flux uniformity, and sample temperatures continuously controllable from 38 to 1375 K. A load lock chamber allows for sample insertion, storage of up to 4 samples, and docking with other facilities. The design and performance of this chamber are described here.
Dura, J. A.; LaRock, J. [NIST Center for Neutron Research, 100 Bureau Dr. MS 6102, Gaithersburg, Maryland 20899 6102 (United States)
Large coil test facility
Final design of the facility is nearing completion, and 20% of the construction has been accomplished. A large vacuum chamber, houses the test assembly which is coupled to appropriate cryogenic, electrical, instrumentation, diagnostc systems. Adequate assembly/disassembly areas, shop space, test control center, offices, and test support laboratories are located in the same building. Assembly and installation operations are accomplished with an overhead crane. The major subsystems are the vacuum system, the test stand assembly, the cryogenic system, the experimental electric power system, the instrumentation and control system, and the data aquisition system.
Nelms, L.W.; Thompson, P.B.
Contamination Control Assessment of the World's Largest Space Environment Simulation Chamber
The Space Power Facility s thermal vacuum test chamber is the largest chamber in the world capable of providing an environment for space simulation. To improve performance and meet stringent requirements of a wide customer base, significant modifications were made to the vacuum chamber. These include major changes to the vacuum system and numerous enhancements to the chamber s unique polar crane, with a goal of providing high cleanliness levels. The significance of these changes and modifications are discussed in this paper. In addition, the composition and arrangement of the pumping system and its impact on molecular back-streaming are discussed in detail. Molecular contamination measurements obtained with a TQCM and witness wafers during two recent integrated system tests of the chamber are presented and discussed. Finally, a concluding remarks section is presented.
Snyder, Aaron; Henry, Michael W.; Grisnik, Stanley P.; Sinclair, Stephen M.
Ionisation Chambers and Secondary Emission Monitors at the PROSCAN Beam Lines
PROSCAN, the dedicated new medical facility at PSI using proton beams for the treatment of deep seated tumours and eye melanoma, is now in the commissioning phase. Air filled ionisation chambers in several configurations are used as current monitors, profile monitors, halo, position and loss monitors at the PROSCAN beam lines. Similar monitors based on secondary emission are used for profile and current measurements in the regime where saturation deteriorates the accuracy of the ionisation chambers.
Doelling, Rudolf [Paul Scherrer Institut (PSI), CH-5232 Villigen-PSI (Switzerland)
Rocket Engine Thrust Chamber Assembly
A thrust chamber assembly for liquid fueled rocket engines and the method of making it wherein a two-piece mandrel wrapped with a silica tape saturated with a phenolic resin, the tape extending along the mandrel and covering the combustion chamber portion of the mandrel to the throat portion. The phenolic in the tape is cured and the end of the wrap is machined. The remainder of the mandrel is wrapped with a third silica tape. The resin in the third tape is cured and the assembly is machined. The entire assembly is then wrapped with a tow of graphite fibers wetted with an epoxy resin and, after the epoxy resin is cured, the graphite is machined to final dimensions.
Cornelius, Charles S. (Inventor); Counts, Richard H. (Inventor); Myers, W. Neill (Inventor); Lackey, Jeffrey D. (Inventor); Peters, Warren (Inventor); Shadoan, Michael D. (Inventor); Sparks, David L. (Inventor); Lawrence, Timothy W. (Inventor)
Heterogeneous ice nucleation in the AIDA chamber: a microphysical modelling study
In July 2002 a heterogeneous ice nucleation campaign was carried out in the highly instrumented AIDA cloud chamber facility at Forschungszentrum Karlsruhe. A variety of temperatures and pumping speeds (cooling rates) were investigated using two types of aerosol: spark generated soot and mineral dust. Detailed measurements of temperature, pressure, humidity, aerosol and hydrometeor characteristics (concentration and size) were made. The detailed observations of the chamber environment conditions allow us to critically test published heterogeneous ice nucleation parametrizations. We will present the results of a detailed microphysical model of the AIDA chamber runs.
Cotton, R.; Field, P.; Moehler, O.; Stetzer, O.; Connolly, P.; Mangold, A.; Kramer, M.; Schurath, U.
Self-Triggering Cylindrical Spark Chamber.
The operation possibility of the cylindrical spark chamber in combination with a cylindrical proportional chamber for the detection of recoil nuclei ( alpha particles) is shown. This detector had the property of an azimuthal symmetry of the recoil nuclei ...
A. S. Aleksanyan, G. K. Megrabyan, R. N. Pikhtelev
Laser Hydrogen High-Pressure Streamer Chamber.
The results of experimental investigations into a laser hydrogen streamer chamber at a hydrogen pressure increased up to 2 at are described. A structural flowsheet and main chamber parameters are considered. Photographs of diffraction pictures taken at 43...
A. Budzyak I. T. Ivanov V. A. Panyushkin I. V. Falomkin Z. Tsisek
Smog Chamber Validation Using Lagrangian Atmospheric Data.
A method was developed for validating outdoor smog chamber experiments as a means of determining the relationships between oxidant concentrations and its precursors - hydrocarbons and nitrogen oxides. When chamber experiments were performed in a manner th...
C. E. Feigley H. E. Jeffries M. A. Carpenter
Materials physically tested in variable- environment chamber
Controlled environment chamber for physical tests of crushable materials encloses both the test specimen and the devices for performing the tests. The chamber may be stepped through a range of changing environment.
Knoell, A. C.
Space Chambers for Crop Treatment
Vacuum chambers, operated by McDonnell Douglas Corporation to test spacecraft, can also be used to dry water-soaked records. The drying temperature is low enough to allow paper to dry without curling or charging. Agricultural crops may also be dried using a spinoff system called MIVAC, which has proven effective in drying rice, wheat, soybeans, corn, etc. The system is energy efficient and can incorporate a sanitation process for destroying insects without contamination.
Design and testing of a model CELSS chamber robot
A robot system for use in an enclosed environment was designed and tested. The conceptual design will be used to assist in research performed by the Controlled Ecological Life Support System (CELSS) project. Design specifications include maximum load capacity, operation at specified environmental conditions, low maintenance, and safety. The robot system must not be hazardous to the sealed environment, and be capable of stowing and deploying within a minimum area of the CELSS chamber facility. This design consists of a telescoping robot arm that slides vertically on a shaft positioned in the center of the CELSS chamber. The telescoping robot arm consists of a series of links which can be fully extended to a length equal to the radius of the working envelope of the CELSS chamber. The vertical motion of the robot arm is achieved through the use of a combination ball screw/ball spline actuator system. The robot arm rotates cylindrically about the vertical axis through use of a turntable bearing attached to a central mounting structure fitted to the actuator shaft. The shaft is installed in an overhead rail system allowing the entire structure to be stowed and deployed within the CELSS chamber. The overhead rail system is located above the chamber's upper lamps and extends to the center of the CELSS chamber. The mounting interface of the actuator shaft and rail system allows the entire actuator shaft to be detached and removed from the CELSS chamber. When the actuator shaft is deployed, it is held fixed at the bottom of the chamber by placing a square knob on the bottom of the shaft into a recessed square fitting in the bottom of the chamber floor. A support boot ensures the rigidity of the shaft. Three student teams combined into one group designed a model of the CELSS chamber robot that they could build. They investigated materials, availability, and strength in their design. After the model arm and stand were built, the class performed pre-tests on the entire system. A stability pre-test was used to determine whether the model robot arm would tip over on the stand when it was fully extended. Results showed the stand tipped when 50 Newtons were applied horizontally to the top of the vertical shaft while the arm was fully extended. This proved that it was stable. Another pre-test was the actuator slip test used to determine if there is an adequate coefficient of friction between the actuator drive wheels and drive cable to enable the actuator to fully extend and retract the arm. This pre-test revealed that the coefficient of friction was not large enough to prevent slippage. Sandpaper was glued to the drive wheel and this eliminated the slippage problem. The class preformed a fit test in the CELSS chamber to ensure that the completed robot arm is capable of reaching the entire working envelope. The robot was centered in the chamber and the arm was fully extended to the sides of the chamber. The arm was also able to retract to clear the drain pipes separating the upper and lower plant trays.
Davis, Mark; Dezego, Shawn; Jones, Kinzy; Kewley, Christopher; Langlais, Mike; Mccarthy, John; Penny, Damon; Bonner, Tom; Funderburke, C. Ashley; Hailey, Ruth
A thrust chamber assembly for liquid fueled rocket engines and the method of making it wherein a two-piece mandrel having the configuration of an assembly having a combustion chamber portion connected to a nozzle portion through a throat portion is wrapped with a silica tape saturated with a phenolic resin, the tape extending along the mandrel and covering the combustion chamber portion of the mandrel to the throat portion. The width of the tape is positioned at an angle of 30 to 50 deg. to the axis of the mandrel such that one edge of the tape contacts the mandrel while the other edge is spaced from the mandrel. The phenolic in the tape is cured and the end of the wrap is machined to provide a frusto-conical surface extending at an angle of 15 to 30 deg. with respect to the axis of the mandrel for starting a second wrap on the mandrel to cover the throat portion. The remainder of the mandrel is wrapped with a third silica tape having its width positioned at a angle of 5 to 20 deg. from the axis of the mandrel. The resin in the third tape is cured and the assembly is machined to provide a smooth outer surface. The entire assembly is then wrapped with a tow of graphite fibers wetted with an epoxy resin and, after the epoxy resin is cured, the graphite is machined to final dimensions.
Cornelius, Charles S. (Inventor); Counts, Richard H. (Inventor); Myers, W. Neill (Inventor); Lackey, Jeffrey D. (Inventor); Peters, Warren (Inventor); Shadoan, Michael (Inventor); Sparks, David L. (Inventor); Lawrence, Timothy W. (Inventor)
The crop growth research chamber
The Crop Growth Research Chamber (CGRC) has been defined by CELSS principle investigators and science advisory panels as a necessary ground-based tool in the development of a regenerative life support system. The focus of CGRC research will be on the biomass production component of the CELSS system. The ground-based Crop Growth Research Chamber is for the study of plant growth and development under stringently controlled environments isolated from the external environment. The chamber has importance in three areas of CELSS activities: (1) crop research; (2) system control and integration, and (3) flight hardware design and experimentation. The laboratory size of the CGRC will be small enough to allow duplication of the unit, the conducting of controlled experiments, and replication of experiments, but large enough to provide information representative of larger plant communities. Experiments will focus on plant growth in a wide variety of environments and the effects of those environments on plant production of food, water, oxygen, toxins, and microbes. To study these effects in a closed system, tight control of the environment is necessary.
Wagenbach, Kimberly
Flow-induced noise from wind tunnel turbulence reduction screens
Boeing is acquiring a new Low Speed Aeroacoustic Facility to simulate low speed flight conditions by adding a free jet to an existing anechoic chamber. The primary facility characteristics will be high flow quality and low background noise levels in the open jet test section. During the design phase, it was recognized that noise generated by flow through the turbulence
Richard M. Allen; Richard R. Gibbs; Patrick J. F. Clark
Experimental verification of correlation algorithm between FAC and open area test site\\/SAC
The main purpose of Fully Anechoic Chamber (FAC) as an alternative facility for EMC compliance testing is to accurately measure the radiated emission generated from equipment-under-test (EUT). The Open Area Test Site (OATS) is the standard test facility for radiated emission measurement, thus the FAC data have to be correlated to the OATS results. In this paper, it is statistically
Jong-Hwa Kwon; Hyung-Do Choi
Recent findings on confined vortex chamber flows
An analytical model directed toward studying selected fluid parameters in vortex chambers is presented. From the model, dimensionless quantities such as, core size, static pressure drop across the chamber, radial static pressure distribution, and radius of reversed flow at the exit, are shown to be functions of chamber geometry only. In addition, it is experimentally demonstrated that in the case of small contraction ratios, the static pressure drop across the chamber can be effectively lowered by plugging the exit flow.
Vatistas, G. H.; Lin, S.; Kwok, C. K.
Detection properties of the electret pulse chamber
The detection properties of the electret ionization chamber in the pulse mode are described for an air-filled chamber with parallel plate geometry. The chamber consists of an one-sided metallized PTFE electret connected with a charge sensitive preamplifier. Irradiation of the air volume with alpha-particles as well as of a polyethylene-walled chamber with fast neutrons gives rise to pulse generation. The
Gunter Pretzsch
Identification of source velocities on 3D structures in non-anechoic environments: Theoretical background and experimental validation of the inverse patch transfer functions method
In noise control, identification of the source velocity field remains a major problem open to investigation. Consequently, methods such as nearfield acoustical holography (NAH), principal source projection, the inverse frequency response function and hybrid NAH have been developed. However, these methods require free field conditions that are often difficult to achieve in practice. This article presents an alternative method known as inverse patch transfer functions, designed to identify source velocities and developed in the framework of the European SILENCE project. This method is based on the definition of a virtual cavity, the double measurement of the pressure and particle velocity fields on the aperture surfaces of this volume, divided into elementary areas called patches and the inversion of impedances matrices, numerically computed from a modal basis obtained by FEM. Theoretically, the method is applicable to sources with complex 3D geometries and measurements can be carried out in a non-anechoic environment even in the presence of other stationary sources outside the virtual cavity. In the present paper, the theoretical background of the iPTF method is described and the results (numerical and experimental) for a source with simple geometry (two baffled pistons driven in antiphase) are presented and discussed.
Aucejo, M.; Totaro, N.; Guyader, J.-L.
Experimental biomass burning emission assessment by combustion chamber
Biomass burning is a significant source of several atmospheric gases and particles and it represents an important ecological factor in the Mediterranean ecosystem. In this work we describe the performances of a recently developed combustion chamber to show the potential of this facility in estimating the emission from wildland fire showing a case study with leaves, small branches and litter of two representative species of Mediterranean vegetation, Quercus pubescens and Pinus halepensis. The combustion chamber is equipped with a thermocouple, a high resolution balance, an epiradiometer, two different sampling lines to collect organic volatile compounds (VOCs) and particles, a sampling line connected to a Proton Transfer Reaction Mass-Spectrometer (PTR-MS) and a portable analyzer to measure CO and CO2 emission. VOCs emission were both analyzed with GC-MS and monitored on-line with PTR-MS. The preliminary qualitative analysis of emission showed that CO and CO2 are the main gaseous species emitted during the smoldering and flaming phase, respectively. Many aromatics VOCs as benzene and toluene, and many oxygenated VOC as acetaldehyde and methanol were also released. This combustion chamber represents an important tool to determine the emission factor of each plant species within an ecosystem, but also the contribution to the emissions of the different plant tissues and the kinetics of different compound emissions during the various combustion phases. Another important feature of the chamber is the monitoring of the carbon balance during the biomass combustion.
Lusini, Ilaria; Pallozzi, Emanuele; Corona, Piermaria; Ciccioli, Paolo; Calfapietra, Carlo
Wire chamber degradation at the Argonne ZGS
Experience with multiwire proportional chambers at high rates at the Argonne Zero Gradient Synchrotron is described. A buildup of silicon on the sense wires was observed where the beam passed through the chamber. Analysis of the chamber gas indicated that the density of silicon was probably less than 10 ppM.
Haberichter, W.; Spinka, H.
Gas-phase smog chamber experiments are being performed at EPA in order to evaluate a number of current chemical mechanisms for inclusion in EPA regulatory and research models. The smog chambers are 9000 L in volume and constructed of 2-mil teflon film. One of the chambers is co...
Pneumatic micropumps with serially connected actuation chambers
This study presents a new pneumatic micropump featuring three membrane-enclosed air chambers with different volumes, such that serially connected actuation of these membranes can generate fluid movement. When compressed air fills the chambers, the membranes are pushed downward sequentially, resulting in the liquid in the underlying fluid channels being pumped forward peristaltically. Since the chambers are filled up sequentially with
Chun-Wei Huang; Song-Bin Huang; Gwo-Bin Lee
Major Parameters Affecting Temperature inside Inhalation Chambers.
These studies showed that stainless steel chamber walls were very effective at removing heat from an (380 l) inhalation chamber. Cooling the incoming air was not as effective in cooling the stainless steel chamber, because most of the heat transfer from t...
D. M. Bernstein R. T. Drew
Making a Fish Tank Cloud Chamber
The cloud chambers described here are large, made from readily available parts, simple to set up and always work. With no source in the chamber, background radiation can be observed. A large chamber means that a long rod containing a weakly radioactive material can be introduced, increasing the chance of seeing decays. Details of equipment andģ
Green, Frances
Convective Exchange between two Connected Chambers
High Rayleigh number convection is studied experimentally in a differentially heated cavity that consists of two connected chambers. We investigate how the circulation, the temperature field and the transport of heat and mass depend on the height of the barrier separating the chambers. We find that the tempera- ture fields in the chambers are very different and that a complex
M. A. Coman; G. O. Hughes; R. C. Kerr
Outdoor chamber study to test multi-day effects. Volume 2. Environmental chamber data tabulations. Final report, August 1982-August 1984
The smog chamber facilities of the University of California, Riverside were used to collect experimental data to assess the effects of multi-day irradiations on photochemical oxidant formation. This volume contains the printouts of all the data that were collected in the study. These data are suitable for use in developing and testing kinetic mechanisms of photochemical smog formation.
Carter, W.P.L.; Dodd, M.C.; Long, W.D.; Atkinson, R.
The membrane chamber: A new type of in vitro recording chamber
In vitro brain slice electrophysiology is a powerful and highly successful technique where a thin slice is cut from the brain and kept alive artificially in a recording chamber. The design of this recording chamber is pivotal to the success and the quality of such experiments. Most often one of two types of chambers is used today, the interface chamber
M. R. H. Hill; S. A. Greenfield
EPA's Human Studies Facility is distiguished by unique, state-of-the art exposure systems designed for studing the health effects of airborne pollutants. The chambers can deliver most gaseous pollutants at precise concentrations and atmospheric conditions. Instrumentation enable...
Fastrac Rocket Engine Combustion Chamber Acoustic Cavities
A three dimensional modal analysis was performed using finite fluid elements. The analysis shows four distinct modes of the Fastrac chamber plus cavities near the frequency of the chamber first tangential mode. The mode shapes illustrate the complexity of fluid oscillations in a three dimensional chamber and acoustic cavity. In addition, a first tangential forcing function was applied to the chamber with three different acoustic cavity fluid temperatures. It was observed that the acoustic cavity fluid temperature has a significant effect on the response of the chamber to first tangential mode oscillations.
Christensen, Eric; Nesman, Tom
A self-contained mechanical system for circulating nutrient fluid through 12 tissue culture chambers is described in detail. This system utilizes nonperforated cellophane membranes in the chambers which separate the circulating nutrient from the tissue culture environments. The nutrient, therefore, is dialyzed through the cellophane of each chamber; some cell products are retained in the microenvironment between the closely apposed cellophane and cover slip, whereas the other cell products move from chamber to chamber in the circulating nutrient. The resultant environmental conditions directed by the circumfusion systems are highly favorable for maintaining the differentiation of chick embryo tissues over protracted periods; a number of micrographs are shown.
Rose, George G.
[Taylor and Hill, Incorporated's JSC Cryo Chamber A
NASA commissioned construction of an environmental simulation test chamber which was completed in 1964 at Johnson Space Center (JSC) in Houston, Texas. The facility, Chamber A, was invaluable for testing spacecraft and satellites before deployment to space. By testing spacecraft in an environment similar to the one they would be functioning in, potential problems could be addressed before launch. A new addition to NASA's observatory inventory is called the James Webb Space Telescope (JWST), after a former Administrator of NASA. The new telescope will have 7 times the mirror area of the Hubble, with a target destination approximately one million miles from earth. Scheduled for launch in 2013, the JWST will allow scientists the ability to see, for the first time, the first galaxies that formed in the early Universe. Pre-launch testing of JWST must be performed in environments that approximate its final target space environment as closely as possible.
Morales, Rito
Hydrocarbon-fuel/combustion-chamber-liner materials compatibility
Results of material compatibility experiments using hydrocarbon fuels in contact with copper-based combustion chamber liner materials are presented. Mil-Spec RP-1, n- dodecane, propane, and methane fuels were tested in contact with OFHC, NASA-Z, and ZrCu coppers. Two distinct test methods were employed. Static tests, in which copper coupons were exposed to fuel for long durations at constant temperature and pressure, provided compatibility data in a precisely controlled environment. Dynamic tests, using the Aerojet Carbothermal Test Facility, provided fuel and copper compatibility data under realistic booster engine service conditions. Tests were conducted using very pure grades of each fuel and fuels to which a contaminant, e.g., ethylene or methyl mercaptan, was added to define the role played by fuel impurities. Conclusions are reached as to degradation mechanisms and effects, methods for the elimination of these mechanisms, selection of copper alloy combustion chamber liners, and hydrocarbon fuel purchase specifications.
Gage, Mark L.
Acoustic facilities for human factors research at NASA Langley Research Center: Description and operational capabilities
A number of facilities were developed which provide a unique test capability for psychoacoustics and related human factors research. The design philosophy, physical layouts, dimensions, construction features, operating capabilities, and example applications for these facilities are described. In the exterior effects room, human subjects are exposed to the types of noises that are experienced outdoors, and in the interior effects room, subjects are exposed to the types of noises and noise-induced vibrations that are experience indoors. Subjects are also exposed to noises in an echo-free environment in the anechoic listening room. An aircraft noise synthesis system, which simulates aircraft flyover noise at an observer position on the ground, is used in conjunction with these three rooms. The passenger ride quality apparatus, a device for studying passenger response to noise and vibration in aircraft, or in other vehicles, is described.
Hubbard, H. H.; Powell, C. A.
Studies with the Arapahoe smoke chamber
Samples of polymethyl methacrylate, polyvinyl chloride, polyester, and polystyrene were evaluated using the Arapahoe smoke chamber. These same materials had been previously evaluated using the National Bureau of Standards (NBS) smoke chamber. The percent smoke based on initial weight as determined using the Arapahoe smoke chamber appeared to correlate with the maximum specific optical density under flaming conditions as determined using the NBS smoke chamber. In addition, the percent smoke based on weight loss as determined using the Arapahoe smoke chamber appeared to correlate with the maximum specific optical density under nonflaming conditions as determined using the NBS smoke chamber. The Arapahoe smoke chamber also offers the advantage of high sample throughput and the possibility of related studies of smoke particulates.
Hilado, C. J.; Cumming, H. J.
A fully automated radon exposure chamber
A fully automated radon exposure chamber is described. The chamber is made of stainless steel and has a volume of 1.46 m 3. The chamber allows 222Rn, 220Rn or both to be injected from the bottom pipe-lines into the chamber in a 100% flow-through mode, 100% recirculate mode or flow-through/recirculate mode. Either atmospheric aerosol or monodisperse aerosol from aerosol generator can be injected into the chamber. The radon concentration; radon daughter concentration; unattached fraction of radon daughters; aerosol size distribution and activity size distribution of radon daughters in aerosols are continuously monitored by computers and feedback signals are used to maintain the specified condition. Though the chamber may be small when compared to walk-in type exposure room, it has the advantage of fast response to changes in the chamber condition and yet is large enough to preclude perturbations due to sampling or other activities.
Leung, John K. C.; Jia, D.; Tso, Man-yin W.
Chamber propagation physics for heavy ion fusion
Chamber transport is an important area of study for heavy ion fusion. Final focus and chamber-transport are high leverage areas providing opportunities to significantly decrease the cost of electricity from a heavy ion fusion power plant. Chamber transport in two basic regimes is under consideration. In the low chamber density regime ({approx_lt}0.003 torr), ballistic or nearly-ballistic transport is used. Partial beam neutralization has been studied to offset the effects of beam stripping. In the high chamber density regime ({approx_gt}.1 torr), two transport modes (pinched transport and channel transport) are under investigation. Both involve focusing the beam outside the chamber then transporting it at small radius ({approx} 2 mm). Both high chamber density modes relax the constraints on the beam quality needed from the accelerator which will reduce the driver cost and the cost of electricity.
Callahan, D.A.
Heat transfer in combustion chambers
This paper is dedicated to reviewing and assessing the various models, embodied in a calculation procedure, that are employed in order to calculate heat transfer characteristics (the flux models, the Spherical Harmonics model, the Discrete Ordinate model, etc). The calculation procedure solves the governing conservation equation of mass, momentum and energy, expressed in a finite difference form, and employs a two-equation turbulence model and a reaction model. Calculated results obtained using the flux and the Discrete Ordinate models were compared with experimental data for three furnaces. The resulting agreement promises greater economy and better performance in furnaces and combustion chambers.
Khalil, E. E.
Portable Ethylene Oxide Sterilization Chamber
A portable ethylene oxide sterilization chamber was designed, constructed, and tested for use in the sterilization of embolectomy catheters. The unit can accommodate catheters up to 40 inches (101.6 cm) in length and can be operated for less than 4 cents per cycle. A constant concentration of 500 mg of ethylene oxide per liter of space and holding periods of 4 and 6 hr at 43 and 22 C, respectively, were adequate when tested with B. subtilis spores. The estimated cost of construction was $165.00. If temperature control is unnecessary, the cost is approximately $80.00. Images
Songer, J. R.; Mathis, R. G.
Radiated emission measurements conducted in the AST semi-anechoic chamber dual polarization broadband gigahertz field simulator and their verification with the measurements done on the open area test site
This paper addresses an innovative method of measuring radiated emission, using a dual polarization, broadband gigahertz field (BGF) simulator. Verification of emission measurements conducted in the BGF simulator with the measurements done on an open area test site (OATS) is presented
A. S. Podgorski; J. Baran
Tubular copper thrust chamber design study
The use of copper tubular thrust chambers is particularly important in high performance expander cycle space engines. Tubular chambers have more surface area than flat wall chambers, and this extra surface area provides enhanced heat transfer for additional energy to power the cycle. This paper was divided into two sections: (1) a thermal analysis and sensitivity study; and (2) a preliminary design of a selected thrust chamber configuration. The thermal analysis consisted of a statistical optimization to determine the optimum tube geometry, tube booking, thrust chamber geometry, and cooling routing to achieve the maximum upper limit chamber pressure for a 25,000 pound thrust engine. The preliminary design effort produced a layout drawing of a tubular thrust chamber that is three inches shorter than the Advanced Expander Test Bed (AETB) milled channel chamber but is predicted to provide a five percent increase in heat transfer. Testing this chamber in the AETB would confirm the inherent advantages of tubular chamber construction and heat transfer.
Masters, A. I.; Galler, D. E.
30 CFR 77.305 - Access to drying chambers, hot gas inlet chambers and ductwork; installation and maintenance.
Code of Federal Regulations, 2010 CFR
...2010-07-01 2010-07-01 false Access to drying chambers, hot gas inlet chambers and ductwork; installation and maintenance...Thermal Dryers ┬¦ 77.305 Access to drying chambers, hot gas inlet chambers and ductwork;...
Code of Federal Regulations, 2013 CFR
...2013-07-01 2013-07-01 false Access to drying chambers, hot gas inlet chambers and ductwork; installation and maintenance...Thermal Dryers ┬¦ 77.305 Access to drying chambers, hot gas inlet chambers and ductwork;...
...2009-07-01 2009-07-01 false Access to drying chambers, hot gas inlet chambers and ductwork; installation and maintenance...Thermal Dryers ┬¦ 77.305 Access to drying chambers, hot gas inlet chambers and ductwork;...
Formation of crustal magma chambers in Iceland
Formation of crustal magma chambers in Iceland may be facilitated by the occurrence of stress barriers that lead to formation of thick sills. Such sills absorb the magma of all dikes that enter them and may evolve into magma chambers. Ideal sites for stress barriers, and hence for magma chambers, are rock formations where individual layers have different elastic properties. The rocks formed during the Pleistocene have notably different elastic properties, and when buried in the volcanic zones, they form more promising sites for magma chambers than the Tertiary rocks. This may explain why the number of magma chambers, indicated by the number of corresponding central volcanoes, during the late Pleistocene (i.e., during the past 0.7 m.y.) appears to be proportionally greater than the number of chambers (i.e., central volcanoes) active during Tertiary time.
Gudmundsson, A.
Formation of crystal magma chambers in Iceland
Formation of crustal magma chambers in Iceland may be facilitated by the occurrence of stress barriers that lead to formation of thick sills. Such sills absorb the magma of all dikes that enter them and may evolve into magma chambers. Ideal sites for stress barriers, and hence for magma chambers, are rock formations where individual layers have different elastic properties. The rocks formed during the Pleistocene have notably different elastic properties, and when buried in the volcanic zones, they form more promising sites for magma chambers than the Tertiary rocks. This may explain why the number of magma chambers, indicated by the number of corresponding central volcanoes, during the late Pleistocene (i.e., during the past 0.7 m.y.) appears to be proportionally greater than the number of chambers (i.e., central volcanoes) active during Tertiary time. *Present address: Nordic Volcanological Institute, University of Iceland, IS-101, Reykjavik, Iceland
Gudmundsson, ┼g·st
Neutron-chamber detectors and applications
Detector applications in Nuclear Safeguards and Waste Management have included measuring neutrons from fission and (alpha,n) reactions with well-moderated neutron proportional counters, often embedded in a slab of polyethylene. Other less-moderated geometries are useful for detecting both bare and moderated fission-source neutrons with good efficiency. The neutron chamber is an undermoderated detector design comprising a large, hollow, polyethylene-walled chamber containing one or more proportional counters. Neutron-chamber detectors are relatively inexpensive; can have large apertures, usually through a thin chamber wall; and offer very good detection efficiency per dollar. Neutron-chamber detectors have also been used for monitoring vehicles and for assaying large crates of transuranic waste. Our Monte Carlo calculations for a new application (monitoring low-density waste for concealed plutonium) illustrate the advantages of the hollow-chamber design for detecting moderated fission sources. 9 refs., 6 figs., 2 tabs.
Fehlau, P.E.; Atwater, H.F.; Coop, K.L.
A Fast Ionization Chamber for Fission Cross-Section Measurements at n_TOF
An ionization chamber with fast timing properties was built at CERN for measuring fission cross-sections of minor actinides at the n{_}TOF neutron beam. The design of this new chamber and of the front-end electronics was optimized to match the innovative features of the n{_}TOF facility, in particular the high instantaneous neutron flux and low background. For the most radioactive isotopes, a special version of the chamber, designed according to the ISO2919 standards, was built in order to comply with the radioprotection requirements at CERN. The detector and front-end electronics are here described, together with the simulated and measured response to fission fragments and {alpha}-particles. The performances of the chamber during the first measurement campaign at n{_}TOF are presented, focusing in particular on the fast time response, the good background rejection capability, low-background and high detection efficiency.
Calviani, M. [Laboratori Nazionali di Legnaro, Italy; Koehler, Paul Edward [ORNL; Collaboration, n_TOF [Collaboration affiliations
A fast ionization chamber for fission cross-section measurements at n_TOF
An ionization chamber with fast timing properties was built at CERN for measuring fission cross-sections of minor actinides at the n_TOF neutron beam. The design of this new chamber and of the front-end electronics was optimized to match the innovative features of the n_TOF facility, in particular the high instantaneous neutron flux and low background. For the most radioactive isotopes, a special version of the chamber, designed according to the ISO2919 standards, was built in order to comply with the radioprotection requirements at CERN. The detector and front-end electronics are here described, together with the simulated and measured response to fission fragments and ?-particles. The performances of the chamber during the first measurement campaign at n_TOF are presented, focusing in particular on the fast time response, the good background rejection capability, low-background and high detection efficiency.
N Tof Collaboration; Calviani, M.; Cennini, P.; Karadimos, D.; Ketlerov, V.; Konovalov, V.; Furman, W.; Goverdowski, A.; Vlachoudis, V.; Zanini, L.; n_TOF Collaboration
Ion chamber gamma burst detector
A gamma ray burst detector of x-ray photons 2 to 10 keV is designed to maximize area, 100 m/sup 2/, and sensitivity, 10/sup -10/ ergs cm/sup -2/ s/sup 1/2/ modest directionality, 2 x 10/sup -4/ sr, and minimize thickness, 3 mg cm/sup -2/, as a plastic space balloon ion chamber. If the log N - log S curve for gamma bursts extends as the -3/2 power, the sensitivity is limited by gamma-burst peak overlap in time so that the question of the size spectrum and isotropy is maximally tested. Supernova type I prompt x-ray bursts of congruent to 3-ms duration should be detected at a rate of several per day from supernova at a distance greater than 100 Mpc.
Colgate, S.A.
An airborne isothermal haze chamber
Thermal gradient diffusion cloud chambers (TGDCC) are used to determine the concentrations of cloud condensation nuclei (CCN) with critical supersaturations greater than or equal to about 0.2%. The CCN concentrations measured with the airborne IHC were lower than theoretically predicted by factors ranging between 7.9 and 9.0. The CCN concentrations measured with the airborne IHC were lower than the concentrations measured with the larger laboratory IHC's by factors ranging between 3.9 and 7.5. The bounds of the supersaturation ranges of the airborne IHC and the CSU-Mee TGDCC do not overlap. Nevertheless, the slopes of the interpolated data between the bounds agree favorably with the theoretical slopes.
Hindman, E. E.
Microstrip gas chambers on thin plastic supports
The authors describe the development of microstrip gas chambers manufactured on thin-foil plastic supports. They have used two supports, Kapton and Tedlar, that were suitable for microstrip chambers. Results are given for both materials. It was demonstrated that gaseous microstrip chambers with thin plastic supports can be operated at large proportional gains with good energy resolution for low rate 5.9-keV
R. Bouclier; J. J. Florent; J. Gaudaen; G. Million; L. Ropelewski; F. Sauli
Fluidized wall for protecting fusion chamber walls
Apparatus for protecting the inner wall of a fusion chamber from microexplosion debris, x-rays, neutrons, etc. produced by deuterium-tritium (DT) targets imploded within the fusion chamber. The apparatus utilizes a fluidized wall similar to a waterfall comprising liquid lithium or solid pellets of lithium-ceramic, the waterfall forming a blanket to prevent damage of the structural materials of the chamber.
Maniscalco, James A. (Danville, CA); Meier, Wayne R. (Livermore, CA)
Numerical simulation of magma chamber dynamics
Magma chambers are characterized by periodic arrivals of deep magma batches that give origin to complex patterns of magma convection and mixing, and modify the distribution of physical quantities inside the chamber. We simulate the transient, 2D, multi-component homogeneous dynamics in geometrically complex dyke+chamber systems, by means of GALES, a finite element parallel C++ code solving mass, momentum and energy
Antonella Longo; Paolo Papale; Chiara Paola Montagna; Melissa Vassalli; Salvatore Giudice; Andrea Cassioli
Signal propagation in long wire chambers
The propagation of signals in long proportional counters or multi-wire tracking chambers is simulated, using numerical solutions of the multi-wire telegraph equations. The results are compared to experimental data, recorded with a proportional counter and a multi-wire test chamber. The signal shape, the charge division ratio and, in the case of the drift chamber, also the cross talk between the
P Bock; J Engelfried; T Friedrich; J Heintze; P Lennert; M Russ; M Zimmer
Coupled reverberation chambers for emulating MIMO channels
This article describes a new experimental set up for emulating MIMO channels, based on two mode stirred reverberation chambers (MSRC), coupled together with a waveguide. This guide allows one to control the order of the channel diversity, the chambers generating a Rayleigh environment. This set up could thus be used to perform tests of MIMO communication systems in perfectly defined environments and thus under reproducible conditions. After a brief recall of the advantages and drawbacks of using a single reverberation chamber, we describe the theoretical approach and the experimental results for the analysis of two coupled chambers.
Delangre, Olivier; De Doncker, Philippe; Lienard, Martine; Degauque, Pierre
The Mark II Vertex Drift Chamber
We have completed constructing and begun operating the Mark II Drift Chamber Vertex Detector. The chamber, based on a modified jet cell design, achieves 30 {mu}m spatial resolution and <1000 {mu}m track-pair resolution in pressurized CO{sub 2} gas mixtures. Special emphasis has been placed on controlling systematic errors including the use of novel construction techniques which permit accurate wire placement. Chamber performance has been studied with cosmic ray tracks collected with the chamber located both inside and outside the Mark II. Results on spatial resolution, average pulse shape, and some properties of CO{sub 2} mixtures are presented. 10 refs., 12 figs., 1 tab.
Alexander, J.P.; Baggs, R.; Fujino, D.; Hayes, K.; Hoard, C.; Hower, N.; Hutchinson, D.; Jaros, J.A.; Koetke, D.; Kowalski, L.A.
The smog chamber facility of the University of North Carolina was used in a study to collect experimental data for developing and testing kinetic mechanisms of photochemical smog formation. Listings and plots of the 115 dual all-day experiments conducted in the study are containe...
An inhalation exposure facility was developed at the U.S. EPA, RTP, NC to conduct inhalation exposures of rodents and guinea pigs to dye mixtures used by the U.S. Army in the manufacture of smoke munitions. nitially, an evaluation of the prototype chamber aerosol homogeneity was ...
Final results from an extensive ageing test of bakelite Resistive Plate Chambers
We present the final results of an extensive aging test, performed at the CERN Gamma Irradiation Facility on two bakelite Resistive Plate Chambers (RPC) detectors. With a method based on a model describing the behaviour of an RPC under high particle flux conditions, we have periodically measured the electrode resistivity ? of the two RPC prototypes over 3 years. We
G. Carboni; G. Collazuol; S. de Capua; D. Domenici; R. Messi; G. Passaleva; E. Santovetti; M. Veltri
The paper discusses results of tests, conducted in the EPA large chamber facility, determining emissions and chemical degradation of volatile organic compounds (VOCs) from one electrical plug-in type pine-scented air freshener in the presence of ozone supplied by a device markete...
A promising method for monitoring ground emissions involves the use of an emission isolation flux chamber. The method is simple, easily available, and inexpensive. Applications would include RCRA and CERCLA facilities. To date, a uniform method operations does not exist. For this...
This research deals with the validation of the flux chamber method for measuring volatile organic emissions from liquid surfaces in treatment, storage and disposal facilities (TSDF). A simulated surface impoundment was constructed so that method precision and accuracy could be de...
The smog chamber facility of the Statewide Air Pollution Research Center has been employed in a study designed to provide experimental data required for the validation of kinetic computer models of chemical transformations in polluted atmospheres. A 5800-l, Teflon-coated, evacuab...
The NASA Ames Controlled Environment Research Chamber: Present status
The Controlled Environment Research Chamber (CERC) at the NASA Ames Research Center was created for early-on investigation of promising new technologies for life support of advanced space exploration missions. The CERC facility is being used to address the advanced technology requirements necessary to implement an integrated working and living environment for a planetary habitat. The CERC, along with a human-powered centrifuge, a planetary terrain simulator, advanced displays, and a virtual reality, is able to develop and demonstrate applicable technologies for future planetary exploration. There will be several robotic mechanisms performing exploration tasks external to the habitat that will be controlled through the virtual environment to provide representative workloads for the crew. Finally, there will be a discussion of innovative new multidisciplinary test facilities, and how effective they are to the investigation of the wide range of human and machine problems inherent in exploration missions.
Gross, Anthony R.; Korsmeyer, David J.; Harper, Lynn D.; Force, Edwin L.
The NASA Ames Controlled Environment Research Chamber - Present status
The Controlled Environment Research Chamber (CERC) at the NASA Ames Research Center was created for early-on investigation of promising new technologies for life support of advanced space exploration missions. The CERC facility is being used to address the advanced technology requirements necessary to implement an integrated working and living environment for a planetary habitat. The CERC, along with a human-powered centrifuge, a planetary terrain simulator, advanced displays, and a virtual reality capability, is able to develop and demonstrate applicable technologies for future planetary exploration. There will be several robotic mechanisms performing exploration taskes external to the habitat that will be controlled through the virtual environment to provide representative workloads for the crew. Finally, there will be a discussion of innovative new multidisciplinary test facilities, and how effective they are to the investigation of the wide range of human and machine problems inherent in exploration missions.
study on trace contaminants control assembly for sealed environment chamber
The biological and Physicochemical P C life support technologies are all important parts to establish a human Closed Ecological Life Support System CELSS for long-duration mission The latter has the advantages of lower power consumption lower mass and higher efficiency therefore researchers often incorporate the use of biological systems with P C life support technologies to continuously recycle air water and part of the solid waste stream generated such as the Russian BLSS and the NASA-sponsored Lunar-Mars Life Support Test Project LMLSTP In short these tests were very successful in integrating biological and P C life support technologies for long-duration life support Therefore we should use a combination of integrated biological with P C life support technologies in a human CELSS Human construction materials plants animals and soils release much trace toxic gases in a CELSS and they will inhibit plant growth and badly affect human health when their concentrations rise over their threshold levels The effect of biological trace contaminant control technologies is slower especially for a human sealed chamber because human produce much more methane and other contaminants A regenerative Trace Contaminant Control Subsystem TCCS with P C technology is a more important part in this case to control quickly the airborne contaminants levels and assure human in good condition in a sealed chamber This paper describes a trace contaminant control test facility incorporated a 8 m3 sealed environment chamber a regenerative TCCS with P C
Pang, L. P.; Wang, J.; Liu, L. K.; Liu, H.
Neutronics analysis of the Laboratory Microfusion Facility
The radiological safety hazards of the experimental area (EA) for the proposed Inertial Confinement Fusion (ICF) Laboratory Microfusion Facility (LMF) have been examined. The EA includes those structures required to establish the proper pre-shot environment, point the beams, contain the pellet yield, and measure many different facets of the experiments. The radiation dose rates from neutron activation of representative target chamber materials, the laser beam tubes and the argon gas they contain, the air surrounding the chamber, and the concrete walls of the experimental area are given. Combining these results with the allowable dose rates for workers, we show how radiological considerations affect access to the inside of the target chamber and to the diagnostic platform area located outside the chamber. Waste disposal and tritium containment issues are summarized. Other neutronics issues, such as radiation damage to the final optics and neutron heating of materials placed close to the target, are also addressed. 16 refs., 2 figs., 1 tab.
Tobin, M.T.; Singh, M.S.; Meier, W.R.
The JPL Molecular Contamination Investigation Facility
The Molecular Contamination Investigation Facility (MCIF) is discussed in terms of its use for improving the far-UV performance of a camera and its broader applications. The MCIF incorporates two independent vacuum systems with sample isolation chambers and regulated heat exchangers as well as three quartz-crystal microbalances (QCMs) and a residual gas analyzer. One cryogenic QCM is heat sunk into an LN2 heat exchanger, while the others are thermoelectrically controlled and are heat sunk into a regulated heat exchanger. Outgas accumulation can be measured at three surface temperatures between -180 and 80 C simultaneously, and results are presented for the testing of 34 samples in a large-chambered system and 22 samples in a system with a smaller chamber. The MCIF results provide a database for fabrication processes, material selection, maximum bakeout temperatures, and the development of an ultraclean bakeout chamber.
Taylor, Daniel M.; Soules, David; Osborn, David
Characterizing the acoustic properties of the Jet Lab at the National Center for Physical Acoustics
Aerodynamic noise has been a problem since the first use of the jet engine for military aircraft in World War II. For further uses of the jet engine to be possible, problems due to jet noise must be researched and addressed. Anechoic chambers were proposed as a testing facility for research in aerodynamic noise because of their supposed free-field characteristics. The international standard ISO 3745-1977 was introduced to determine whether the facilities could be considered anechoic, semi-anechoic, or neither. An experiment was designed to determine at what frequencies the National Center for Physical Acoustics' Jet Lab Facility is non-anechoic, semi-anechoic, or anechoic. To comply with the guidelines of ISO 3745- 1977, three sources were designed and tested at frequencies from 25 Hz to 16000 Hz. The voltages were acquired at each frequency to calculate the sound pressure level and determine if the calculated values are within the allowed tolerance of the inverse square law.
Lieblong, Joshua Anderson
Points represent facilities that are regulated by the EPA under the Resource Conservation and Recovery Act (RCRA). Facilities regulated under RCRA generate, dispose of, treate or transport hazardous waste. RCRA is a law enacted by Congress in 1976 and amended in 1984 to include ...
Ribbed Coolant Liners for Combustion Chambers
Coolant-carrying liner for combustion chambers runs cooler and tolerates high-temperature excursions without burning out. Hot gases flowing through core prevented by liner from damaging shell. Concept applicable to such high-temperature chambers as rocket pre-burners, turbojet cans, stationary-turbine combustors, oil burners, and high-pressure chemical reactors.
Wagner, W. R.
Development of bakelite based Resistive Plate Chambers
A Comparative study has been performed on Resistive Plate Chambers made of different grades of bakelite paper laminates, produced and commercially available in India. The chambers, operated in the streamer mode using argon : tetrafluroethane : isobutane in 34:59:7 mixing ratio, are tested with cosmic rays for the efficiency and the stability with cosmic rays. A particular grade of bakelite
S. Biswas; S. Bhattacharya; S. Bose; S. Chattopadhyay; S. Saha; M. K. Sharan; Y. P. Viyogi
Laurence Sherr: Chamber Music for Flute
Laurence Sherr is a contemporary American composer with his own unique and recognizable compositional voice. His three chamber works for flute, Dhammapada Verses (1990, rev. 2001) for soprano, flute, percussion, and piano; Journeys Within: Concerto for Flute and Chamber Ensemble (1994); and Duo Concertante for flute and percussion (2003), are valuable contributions to the repertoire that present a challenge to
Christina Maria Guenther
Wire Chamber Aging and Wire Material
Recent studies on wire chamber aging has shown surprising results indicating that anode wire material may have a strong influence on the useful life-time of a chamber or counter. The aging process discussed here is related to changes in the surface characteristics of the anode wires. Those changes may be due to an oxidation process involving molecules produced from the
Muzaffer Atac
Ionization chambers intended for slow-neutron flux measurements in ; nuclear reactors are described. They are 3.5 in. diameter, approximately 13.5 ; in. long and weigh 3.5 lb. The chambers may be operated at 200 deg C or less, ; even with low gas pressures, the limitation being due to collapsing of the outer ; aluminum case. Somewhat higher temperatures (150
Confinement Chamber for Radioactive Products or Waste.
The invention deals with a confinement chamber for radioactive products or wastes that are kept in tanks or in silos buried in the ground. The chamber comprises a combination of an impervious reinforced concrete (RC) support buried in the ground with an R...
Inflatable, Inert Gas-Purged, Welding Chamber.
An inflatable, inert-gas purged welding chamber assembly ideally suited for use in welding workpieces made of a metal (e.g., titanium), or of an alloy, which is susceptible to atmospheric contamination during welding. The welding chamber of the assembly i...
J. M. MacFarland
A very large multigap resistive plate chamber
We have built and tested a very large Multigap Resistive Plate Chamber (MRPC). We discuss the suitability of the multigap RPC for the construction of large area modules. We give details of the construction technique and results from a scan across the surface of the chamber. We also report on the implementation of æhalf-strip resolutionÆ, where we improve the spatial
E. Cerron-Zeballos; J. Choi; D. Hatzifotiadou; D. W Kim; J. Lamas-Valverde; S. C Lee; E. Platner; J. Roberts; M. C. S Williams; A. Zichichi
Multigap glass resistive plate chambers in HARP
Multi-gap glass resistive plate chambers served as time-of-flight measurement instruments in the large-angle acceptance region of the HARP spectrometer. The system comprised 46 chambers and covered an area of ś 8 m2. Mean system efficiencies of 97 98% and an average intrinsic time resolution of 127 ps have been reached, fulfilling the design goal.
V. Ammosov; I. Boyko; G. Chelkov; D. Dedovitch; F. Dydak; A. Elagin; M. Gostkin; V. Koreshev; Yu. Nefedov; K. Nikolaev; A. Zhemchugov; J. Wotschack
Controlled-Environment Sunlit Plant Growth Chambers
Controlled environment sunlit plant growth chambers have been built because of a great interest in plant responses to environmental variables under light intensities approaching those of natural sunlight conditions. Individual research projects have designed sunlit chambers that differ in size, structure, material, and environmental control systems dependent on the goals of the projects. Most literature describes plant organism responses to
L. Liu; G. Hoogenboom; K. T. Ingram
High-Pressure Promoted-Combustion Chamber
Proposed combustion-testing chamber burns specimens of materials in fully contained, high-pressure oxygen atmosphere. Test operator uses handles on threaded retaining rings to attach or remove top or bottom plates sealing combustion chamber. Tests conducted in static or flowing oxygen. Oxygen inlet and outlet far enough above burning specimen, little danger of entrainment of burning fragments in oxygen flowing out.
Rucker, Michelle A.; Stoltzfus, Joel M.
Hydrogen Outgassing in Stainless Steel Gun Chambers
Vacuum quality is an important aspect in electron guns. The hydrogen outgassing rate is a determinant of the vacuum quality in stainless steel gun chambers. A low outgassing rate allows for a better vacuum and therefore a longer photocathode lifetime. Low outgassing rates depend on thermal treatments of the chamber. The purpose of this project is to put together a
Melissa Ricketts
The propagation of signals in long proportional counters or multi-wire tracking chambers is simulated, using numerical solutions of the multi-wire telegraph equations. The results are compared to experimental data, recorded with a proportional counter and a multi-wire test chamber. The signal shape, the charge division ratio and, in the case of the drift chamber, also the cross talk between the wires, are well reproduced. Similar shapes for signals and their cross talk can be obtained with a properly chosen electrical termination. It is shown how data from a multi-wire chamber can then be corrected for cross talk. The effects limiting the precision of position measurements along the wires with the charge division method are discussed. The simulation was applied to the reconstruction of tracks measured with the OPAL JET chamber.
Bock, P.; Engelfried, J.; Friedrich, T.; Heintze, J.; Lennert, P.; Russ, M.; Zimmer, M.
Advanced tube-bundle rocket thrust chamber
An advanced rocket thrust chamber for future space application is described along with an improved method of fabrication. Potential benefits of the concept are improved cyclic life, reusability, and performance. Performance improvements are anticipated because of the enhanced heat transfer into the coolant which will enable higher chamber pressure in expander cycle engines. Cyclic life, reusability and reliability improvements are anticipated because of the enhanced structural compliance inherent in the construction. The method of construction involves the forming of the combustion chamber with a tube-bundle of high conductivity copper or copper alloy tubes, and the bonding of these tubes by an electroforming operation. Further, the method of fabrication reduces chamber complexity by incorporating manifolds, jackets, and structural stiffeners while having the potential for thrust chamber cost and weight reduction.
Kazaroff, John M.; Pavli, Albert J.
An atmospheric exposure chamber for small animals
The purpose of this project was to design a long-term environmental exposure chamber for small animals. This chamber is capable of producing hypoxic, normoxic and hyperoxic atmospheres which are closely regulated. The chamber, which is of the recycling type, is fashioned after clear plastic germ-free isolators. Oxygen concentration is set and controlled by a paramagnetic O2 analyzer and a 3-way solenoid valve. In this way either O2 or N2 may be provided to the system by way of negative O2 feedback. Relative humidity is maintained at 40-50 percent by a refrigeration type dryer. Carbon dioxide is absorbed by indicating soda lime. A diaphragm pump continuously circulates chamber gas at a high enough flow rate to prevent buildup of CO2 and humidity. This chamber has been used for numerous studies which involve prolonged exposure of small animals to various O2 concentrations.
Glaser, R. M.; Weiss, H. S.; Pitt, J. F.; Grimard, M.
SRMAFTE facility checkout model flow field analysis
The Solid Rocket Motor Air Flow Equipment (SRMAFTE) facility was constructed for the purpose of evaluating the internal propellant, insulation, and nozzle configurations of solid propellant rocket motor designs. This makes the characterization of the facility internal flow field very important in assuring that no facility induced flow field features exist which would corrupt the model related measurements. In order to verify the design and operation of the facility, a three-dimensional computational flow field analysis was performed on the facility checkout model setup. The checkout model measurement data, one-dimensional and three-dimensional estimates were compared, and the design and proper operation of the facility was verified. The proper operation of the metering nozzles, adapter chamber transition, model nozzle, and diffuser were verified. The one-dimensional and three-dimensional flow field estimates along with the available measurement data are compared.
Dill, Richard A.; Whitesides, Harold R.
Automated Transmission Loss Measurement in the Structural Acoustic Loads and Transmission Facility at NASA Langley Research Center
A technique to measure the radiated acoustic intensity and transmission loss of panels is documented in this paper. This facility has been upgraded to include a test fixture that scans the acoustic intensity radiated from a panel on the anechoic receiving room side of the transmission loss window. The acoustic intensity incident on the panel from the reverberant side of the transmission loss window is estimated from measurements made using six stationary microphones in the reverberant source room. From the measured incident and radiated intensity, the sound power transmission loss is calculated. The setup of the facility and data acquisition system are documented. A transmission loss estimate of a typical panel is shown. The measurement-to-measurement and setup-to-setup repeatability of the transmission loss estimate are assessed. Conclusions are drawn about the ability to measure changes in transmission loss due to changes in panel construction.
Klos, J.; Brown, S. A.
Influence of high rotational speeds on heat transfer and oil film thickness in aero-engine bearing chambers
Increasing the thermal loading of bearing chambers in modern aero-engines requires advanced techniques for the determination of heat transfer characteristics. In the present study, film thickness and heat transfer measurements have been carried out for the complex two-phase oil\\/air flow in bearing chambers. In order to ensure real engine conditions, a new test facility has been built up, designed for
S. Wittig; A. Glahn; J. Himmelsbach
A new gun facility dedicated to performing shock physics and terminal ballistics experiments
A new building has been constructed to house various powder and single-stage and two-stage gas guns at the Naval Surface Warfare Center, Indian Head Division. Guns previously located at the Naval Research Laboratory and the former White Oak Site of the Naval Surface Warfare Center have been relocated here. Most of the guns are mounted on moveable pedestals to allow them to be shot into various chambers. The facility includes a concrete blast chamber, a target chamber/catch tank for flyer plate experiments, and a target chamber outfitted for terminal ballistics measurements. This paper will discuss the capabilities of this new facility. .
Zakraysek, Alan J.; Sutherland, Gerrit T.; Sandusky, Harold D.; Strange, David
Radar cross section measurements (8-12 GHz) of flat plates painted with microwave absorbing materials
The aim of the present work is to present radar cross section measurements of flat plates painted with radar absorbing material (RAM) in the range of 8-12 GHz. The measurements were carried out in an anechoic chamber at Centro Tecnico Aeroespacial (CTA)-Ministerio da Defesa facilities, and the RAM coating was manufactured at Divisao de Materiais of Instituto de Aeronautica e
M. C. Rezende; I. M. Martin; M. A. S. Miacci; E. L. Nohara
Application of Impedance Loading to Geometric Transition Radar Absorbent Material
This paper describes a novel, lightweight technique for significantly improving the low-frequency reflectivity performance of conventional geometric transition radar absorbent materials as used typically in anechoic chamber facilities for electromagnetic compatibility testing. The improvement is achieved by the inclusion of impedance-loading elements within the base region of the absorber, and these are implemented in the form of one or more
Kenneth Lee Ford; Barry Chambers
The aeronautic, aerospace and automotive industries require improved noise reduction techniques to meet the current normative and increase the acoustic comfort at acceptable cost. The aim of this work is to investigate the capabilities of inverse methods for the noise source reconstruction of ducted acoustic sources in a laboratory acoustic facility installed in a semi anechoic chamber. Model-based inverse methods
Teresa Bravo; Cķdric Maury
Facility Planning.
This article reviews recommendations on policies for leasing surplus school space made during the Council of Educational Facility Planners/International conference. A case study presentation of a Seattle district's use of lease agreements is summarized. (MJL)
Graves, Ben E.
January 2008 LASP FACILTY Database Form 5.000 Issue Reporting Form This form is used to report data and/or program related issues regarding the FACILITY database, Supplemental, or the LASP Online Access System. Before submitting this form,
Health Facilities
Health facilities are places that provide health care. They include hospitals, clinics, outpatient care centers, and specialized care centers, such as birthing centers and psychiatric care centers. When you ...
School Facilities.
Describes the building designs of eight school athletic and recreational facilities, including the educational contexts and design goals. Includes information on architects and designers, construction cost, size, and occupancy date. Also provides photographs. (EV)
Athletic Business, 2002
A Dedicated Facility to Perform Powder and Light Gas Gun Experiments
A new building has been constructed to house various powder, single and two-stage gas guns at the Naval Surface Warfare Center, Indian Head. Guns previously located at the Naval Research Laboratory and the former White Oak Site of the Naval Surface Warfare Center have been relocated. Most of the guns are mounted on movable pedestals to allow them to be shot into various chambers. These chambers are a concrete blast chamber, a target chamber/catch tank for flyer plate experiments, and a target chamber outfitted for terminal ballistics measurements. This paper will discuss the capabilities of this new facility.
Zakraysek, A. J.; Sutherland, G. T.; Sandusky, H. D.
Outdoor chamber study to test multi-day effects. Volume 3. Documentation for computer-readable environmental chamber data. Final report, August 1982-August 1984
The smog chamber facilities of the University of California, Riverside were used to collect experimental data to assess the effects of multi-day irradiations on photochemical oxidant formation. This volume includes documentation on the computer-readable magnetic tape that contains all the data collected in the study. The tape is suitable for use by modelers to develop and test kinetic mechanisms of photochemical smog formation.
The Japanese Radon and Thoron Reference Chambers
Passive detectors used for large-scale and long-term surveys are generally calibrated in a well-controlled environment such as a radon chamber. It has been also pointed out that some of them are sensitive to thoron. Thus it is necessary to check the thoron contribution to the detector response with the proposed or similar test before practical use. The NIRS accommodates radon/aerosol and thoron chambers for quality assurance and quality control of radon measurements. Thus both chambers work so well that they can supply us with the calibration technique and consequently, a good level of knowledge of the radon and thoron issue.
Tokonami, Shinji; Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Takahashi, Hiroyuki; Miyahara, Nobuyuki [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)
Performance of NIRS Thoron Chamber System
In order to carry out thoron sensitivity test for passive radon detectors, a thoron chamber system has been set up at NIRS, Japan. The thoron chamber system consists of four components: the exposure, monitoring, calibration, and humidity control systems, which was mounted in this study due to humidity dependence on the thoron concentration emanated from lantern mantles as the thoron source. The thoron concentration in the thoron chamber is controlled by humidity passed through the thoron source and the weight of the lantern mantle.
Sorimachi, Atsuyuki; Tokonami, Shinji; Takahashi, Hiroyuki; Kobayashi, Yosuke [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)
Tokonami, Shinji; Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Takahashi, Hiroyuki; Miyahara, Nobuyuki
[Anterior chamber intraocular lenses for aphakia correction].
The intraocular correction of aphakia in the anterior chamber currently consists of two options: an angle supported intraocular lens (IOL, Kelman Multiflex) and an iris fixated IOL (Artisan/Verisyse). The angle supported IOL is fixated with four haptic points in the anterior chamber and the iris fixated IOL is enclavated to the anterior iris surface. Acceptable results of both IOLs are reported in the literature; however both IOLs show some long-term complications in some eyes. Alternatives to these anterior chamber IOLs to correct aphakia are the retropupillary fixated Artisan and sclera fixated IOLs. PMID:24706252
Kohnen, T; Hengerer, F H
Construction of a fast ionization chamber for high-rate particle identification
A new gas-filled ionization chamber for high count rate particle identification has been constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). To enhance the response time of the ionization chamber, a design utilizing a tilted entrance window and tilted electrodes was adopted, which is modified from an original design by Kimura et al. [1]. A maximum counting rate of ~700,000 particles per second has been achieved. The detector has been used for several radioactive beam measurements performed at the HRIBF.
Chae, K. Y.; Ahn, S.; Bardayan, D. W.; Chipps, K. A.; Manning, B.; Pain, S. D.; Peters, W. A.; Schmitt, K. T.; Smith, M. S.; Strauss, S. Y.
11. Detail view west from airlock chamber of typical refrigerator ...
11. Detail view west from airlock chamber of typical refrigerator door into Trophic Chamber. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA
Thermal Design and Control of Space Simulation Chambers in Israel.
A set of space simulation chambers designed, manufactured, and constructed for Israeli space industry is considered. These chambers vary in size and in their thermal vacuum performances. Some of the thermal and control systems of these chambers are descri...
S. Gruntman E. Kochavi J. Oren E. Taragan M. Arad
Uniform Effusion Cooling Method for a Can Combustion Chamber.
A dome for a combustion chamber may have a plurality of effusion holes therein to provide efficient cooling while preventing carbon formation on the dome and chamber walls of the combustion chamber. Conventional dome cooling designs, using dome louvers, f...
L. D. Nguyen S. Kujala G. Walhhood L. Critchely G. O. Woodcock
21 CFR 880.5450 - Patient care reverse isolation chamber.
...2014-04-01 2014-04-01 false Patient care reverse isolation chamber. 880.5450...Therapeutic Devices ¦ 880.5450 Patient care reverse isolation chamber. (a) Identification. A patient care reverse isolation chamber is...
Rapid Evaluation of Mode-Stirred Chambers Using Impulsive Waveforms.
In this paper, the authors present an experimental technique for the rapid evaluation of mode-stirred (or reverberation) chambers. The measurement provides an estimate of the average chamber quality factor (Q) by measuring the chamber impulse response and...
J. M. Ladbury R. T. Johnk A. R. Ondrejka
46 CFR 197.332 - PVHO-Decompression chambers.
...2013-10-01 false PVHO-Decompression chambers. 197.332 Section 197.332 Shipping...Equipment ┬¦ 197.332 PVHOŌDecompression chambers. Each decompression chamber mustŌ (a) Meet the requirements of ┬¦...
33 CFR 183.112 - Flotation material and air chambers.
... false Flotation material and air chambers. 183.112 Section 183.112 ...183.112 Flotation material and air chambers. (a) Flotation materials must...in a sealed compartment. (b) Air chambers used to meet the flotation...
30 CFR 57.11054 - Communication with refuge chambers.
...2013-07-01 false Communication with refuge chambers. 57.11054 Section 57.11054...57.11054 Communication with refuge chambers. Telephone or other voice communication...provided between the surface and refuge chambers and such systems shall be...
Development of a EUV Test Facility at the Marshall Space Flight Center
This paper will describe a new EUV test facility that is being developed at the Marshall Space Flight Center (MSFC) to test EUV telescopes. Two flight programs, HiC - high resolution coronal imager (sounding rocket) and SUVI - Solar Ultraviolet Imager (GOES-R), set the requirements for this new facility. This paper will discuss those requirements, the EUV source characteristics, the wavelength resolution that is expected and the vacuum chambers (Stray Light Facility, Xray Calibration Facility and the EUV test chamber) where this facility will be used.
West, Edward; Pavelitz, Steve; Kobayashi, Ken; Robinson, Brian; Cirtain, Johnathan; Gaskin, Jessica; Winebarger, Amy
Characterization and testing of a new environmental chamber designed for emission aging studies
A 29 m3 Teflon chamber, designed for aging studies of combustion aerosols, at the University of Eastern Finland is described and characterized. The chamber belongs to a research facility, called Ilmari, where small-scale combustion devices, a dynamometer for vehicle exhaust studies, dilution systems, the chamber, as well as cell and animal exposure devices are side by side under the same roof. The small surface-to-volume ratio of the chamber enables reasonably long experiment times, with particle wall loss rate constants of 0.088, 0.080, 0.045, and 0.040 h-1 for polydisperse, 50, 100, and 200 nm monodisperse aerosols, respectively. The NO2 photolysis rate can be adjusted from zero to 0.62 min-1. The irradiance spectrum is centered at 365 nm and the maximum irradiance, produced by 160 blacklight lamps, is 29.7 W m-2, which corresponds to the UV irradiance in Central Finland at noon on a sunny day in the midsummer. The temperature inside the chamber is uniform and can be kept at 25 ▒ 1 ░C when half of the blacklights are on. The chamber is kept in an overpressure with a moving top frame, which prevents sample dilution and contamination from entering the chamber during an experiment. The functionality of the chamber was tested with oxidation experiments of toluene, resulting in secondary organic aerosol (SOA) yields of 33-44%, depending on the initial conditions, such as the NOx concentration. The highest gaseous oxidation product yields of 14.4-19.5% were detected with ions corresponding to 2-butenedial (m/z 73.029) and 4-oxo-2-pentenal (m/z 99.044). Overall, reasonable yields of SOA and gaseous reaction products, comparable to those obtained in other laboratories, were obtained.
Leskinen, A.; Yli-Pirilõ, P.; Kuuspalo, K.; Sippula, O.; Jalava, P.; Hirvonen, M.-R.; Jokiniemi, J.; Virtanen, A.; Komppula, M.; Lehtinen, K. E. J.
Three dimensional thrust chamber life prediction
A study was performed to analytically determine the cyclic thermomechanical behavior and fatigue life of three configurations of a Plug Nozzle Thrust Chamber. This thrust chamber is a test model which represents the current trend in nozzle design calling for high performance coupled with weight and volume limitations as well as extended life for reusability. The study involved the use of different materials and material combinations to evaluate their application to the problem of low-cycle fatigue in the thrust chamber. The thermal and structural analyses were carried out on a three-dimensional basis. Results are presented which show plots of continuous temperature histories and temperature distributions at selected times during the operating cycle of the thrust chamber. Computed structural data show critical regions for low-cycle fatigue and the histories of strain within the regions for each operation cycle.
Armstrong, W. H.; Brogren, E. W.
Moessbauer Spectroscopy with Multiwire Proportional Chambers.
This article introduces transmission type Moessbauer spectroscopy with multiwire proportional chambers, which is especially suited to fast sample analysis and consequently is advantageous towards increasing precision in measurement. The construction and p...
Zhang Yi Qun Zhu Jun Jie Wang Xiao Lian
Effect of Diethylhydroxylamine on Smog Chamber Irradiations.
The addition of diethylhydroxylamine (DEHA) to the urban atmosphere had been suggested as a means of preventing photochemical smog. Smog chamber studies were carried out to investigate the photochemical smog formation characteristics of irradiated hydroca...
L. T. Cupitt E. W. Corse
Spark Chamber Spectrometry and Space Radiation Studies.
Advances in instrumentation based on the spark-chamber technique for making charged particle studies of the aerospace environment have included the development of spark-discharge modules that are sealed against the space environment, a high-voltage genera...
G. T. Huetter R. Madey S. M. Yushak
Chambers Receives 2008 Geodesy Section Award
Don P. Chambers received the 2008 Geodesy Section Award at the 2008 AGU Fall Meeting Honors Ceremony, held 17 December in San Francisco, Calif. The award is given in recognition of major advances in geodesy.
Nerem, R. Steven; Chambers, Don P.
21 CFR 866.2120 - Anaerobic chamber.
... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices ┬¦ 866.2120 Anaerobic chamber. (a) Identification. An...
Cloud chamber visualization of primary cosmic rays
From 1948 until 1963, cloud chambers were carried to the top of the atmosphere by balloons. From these flights, which were begun by Edward P. Ney at the University of Minnesota, came the following results: discovery of heavy cosmic ray nuclei, development of scintillation and cherenkov detectors, discovery of cosmic ray electrons, and studies of solar proton events. The history of that era is illustrated here by cloud chamber photographs of primary cosmic rays.
Earl, James A. [Department of Astronomy, University of Maryland, College Park MD (United States)
Invention and History of the Bubble Chamber
Don Glaser won the 1960 Nobel Prize for Physics for his 1952 invention of the bubble chamber at Berkeley Lab, a type of particle detector that became the mainstay of high-energy physics research throughout the 1960s and 1970s. He discusses how, inspired by bubbles in a glass of beer, he invented the bubble chamber and detected cosmic-ray muons. His talk was presented July 12, 2006.
Don Glaser
The Linac Coherent Light Source (LCLS) will be the world's first x-ray free electron laser when it becomes operational in 2009. Synchrotron radiation will be produced by 33 undulators, each 3.4 meters long, with a fixed gap of 6.8 mm. Vacuum chambers for these undulators should have the maximum possible vertical aperture. Multiple vacuum chambers for insertion devices with 1-mm
Emil Trakhtenberg; Patric DenHartog; Mark Erdmann; Greg Wiemerslage
Large Volume Scintillation Chamber for Radon Counting
A 450-cc cylindrical Lucite chamber covered internally with ZnS(Ag) and viewed at each end by 5-in. photo-multiplier tubes with summed outputs has been used routinely as a low background (?0.8 counts per min for a new chamber) Rn scintillation counter. The counter is simple to construct and has operated reliably for about two years. The counting efficiency for Rn in
Hobart W. Kraner; Gerald L. Schroeder; Anthony R. Lewis; Robley D. Evans
Dual-chamber cardiac pacemaker tester.
To investigate the operation of dual-chamber cardiac pacemakers, a pacemaker tester is developed that is able to examine pacemaker parameters, demand modes and rate-adaptive modes. The tester generates simplified electrograms and responds to pacemaker pulses in a closed-loop simulation. The authors describe the hardware and the software algorithm of the tester. To demonstrate the capabilities of the tester, four tests are presented, together with their results on a rate-adaptive dual-chamber pacemaker. PMID:9684467
Galuschky, C W; Webster, J G
We have built and tested a very large Multigap Resistive Plate Chamber (MRPC). We discuss the suitability of the multigap RPC for the construction of large area modules. We give details of the construction technique and results from a scan across the surface of the chamber. We also report on the implementation of 'half-strip resolution', where we improve the spatial resolution by a factor 2 without increasing the number of read-out channels.
Cerron-Zeballos, E.; Choi, J.; Hatzifotiadou, D.; Kim, D. W.; Lamas-Valverde, J.; Lee, S. C.; Platner, E.; Roberts, J.; Williams, M. C. S.; Zichichi, A.
12. View north of Tropic Chamber. Natick Research & ...
12. View north of Tropic Chamber. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA
Development of sputtered techniques for thrust chambers
Techniques and materials were developed and evaluated for the fabrication and coating of advanced, long life, regeneratively cooled thrust chambers. Materials were analyzed as fillers for sputter application of OFHC copper as a closeout layer to channeled inner structures; of the materials evaluated, aluminum was found to provide the highest bond strength and to be the most desirable for chamber fabrication. The structures and properties were investigated of thick sputtered OFHC copper, 0.15 Zr-Cu, Al2O3,-Cu, and SiC-Cu. Layered structures of OFHC copper and 0.15 Zr-Cu were investigated as means of improving chamber inner wall fatigue life. The evaluation of sputtered Ti-5Al-2.5Sn, NASA IIb-11, aluminum and Al2O3-Al alloys as high strength chamber outer jackets was performed. Techniques for refurbishing degraded thrust chambers with OFHC copper and coating thrust chambers with protective ZrO2 and graded ZrO2-copper thermal barrier coatings were developed.
Mullaly, J. R.; Hecht, R. J.; Schmid, T. E.; Torrey, C. T.
High-pressure promoted combustion chamber
In the preferred embodiment of the promoted combusiton chamber disclosed herein, a thick-walled tubular body that is capable of withstanding extreme pressures is arranged with removable upper and lower end closures to provide access to the chamber for dependently supporting a test sample of a material being evaluated in the chamber. To facilitate the real-time analysis of a test sample, several pressure-tight viewing ports capable of withstanding the simulated environmental conditions are arranged in the walls of the tubular body for observing the test sample during the course of the test. A replaceable heat-resistant tubular member and replaceable flame-resistant internal liners are arranged to be fitted inside of the chamber for protecting the interior wall surfaces of the combustion chamber during the evaluation tests. Inlet and outlet ports are provided for admitting high-pressure gases into the chamber as needed for performing dynamic analyses of the test sample during the course of an evaluation test.
Rucker, Michelle A. (inventor); Stoltzfus, Joel M. (inventor)
Sandia National Laboratories' new high level acoustic test facility
A high intensity acoustic test facility has been designed and is under construction at Sandia National Laboratories in Albuquerque, NM. The chamber is designed to provide an acoustic environment of 154dB (re 20 {mu}Pa) overall sound pressure level over the bandwidth of 50 Hz to 10,000 Hz. The chamber has a volume of 16,000 cubic feet with interior dimensions of 21.6 ft {times} 24.6 ft {times} 30 ft. The construction of the chamber should be complete by the summer of 1990. This paper discusses the design goals and constraints of the facility. The construction characteristics are discussed in detail, as are the acoustic performance design characteristics. The authors hope that this work will help others in designing acoustic chambers. 12 refs., 6 figs.
Rogers, J. D.; Hendrick, D. M.
OKADA M. HAMASAKI T. and HAYASH! T. Temperature gradient chambers for research on global environment change. I. Thermal environment in a large chamber. BIOTRONICS 24, 85-97, 1995. Simple and low-cost temperature gradient chambers (TGC) have been developed to study the effects of temperature on field crops. Providing a continuous one-way air flow along the long axis of the TGC, the
Numerical models on shallow magma chamber formation
A magma chamber can be defined as a body within the crust that is either partially or totally molten which is injected with new magma from a deep-seated reservoir. A shallow magma chamber acts as a sink as it receives magma from the deeper reservoir, and as a source for volcanic eruptions. Most shallow magma chambers appear to develop from sills, and some, such as many mid-ocean ridge magma chambers, maintain the sill geometry through their lifetimes. For a sill to function as a magma chamber, certain conditions must be met: (1) The sill thickness must be in the order of tens of metres. This thickness is reached by either a) when a complex of thinner sills amalgamates or b) magma accumulates due to multiple dyke arrests at the contact with the sill. (2) The sill must receive a fairly constant magma replenishment so the chamber remains partially or (more rarely) totally molten. Here, we present numerical models based on geophysical data on how an individual sill can evolve into a magma chamber. Sills generally exhibit a concave-upward or straight geometry, although they may take other forms e.g. stepped, saucer-shaped, or concave-downward. Seismic studies suggest that many shallow ocean-ridge magma chambers have a moderately smooth geometry (ellipsoidal) rather than an irregular network of dykes and sills. Our numerical results indicate as follows: Firstly, the deflection of dykes into sills is most favoured in the upper crust where there are many layers generating stress barriers/delaminations due to elastic mismatch, that is, contrasting mechanical properties. Secondly, a sill grows primarily by elastic-plastic deformation of the host rock in which it is emplaced, while host rock anatexis/stoping may generate space for some large sills. The elastic-plastic expansion is partly reflected in upward bending of the overburden and partly in downward bending of the underburden. Thirdly, while the initial sill stays liquid or 'soft', subsequent dyke injections become arrested at the contact with the sill and their magmas become partly absorbed into the sill, which thereby grows. Fourthly, the sill must remain totally or at least partially molten, which requires a high injection rate of dykes feeding the sills to have a chance of developing into a shallow magma chamber. A high dyke injection rate is most likely to be reached at high extension rates, such as at fast-spreading ridges. This may be one reason for the common sill-like magma chambers being located at fast-spreading ridges.
Barnett, Zoe; Gudmundsson, Agust
Neutron imaging with bubble chambers for inertial confinement fusion
One of the main methods to obtain energy from controlled thermonuclear fusion is inertial confinement fusion (ICF), a process where nuclear fusion reactions are initiated by heating and compressing a fuel target, typically in the form of a pellet that contains deuterium and tritium, relying on the inertia of the fuel mass to provide confinement. In inertial confinement fusion experiments, it is important to distinguish failure mechanisms of the imploding capsule and unambiguously diagnose compression and hot spot formation in the fuel. Neutron imaging provides such a technique and bubble chambers are capable of generating higher resolution images than other types of neutron detectors. This thesis explores the use of a liquid bubble chamber to record high yield 14.1 MeV neutrons resulting from deuterium-tritium fusion reactions on ICF experiments. A design tool to deconvolve and reconstruct penumbral and pinhole neutron images was created, using an original ray tracing concept to simulate the neutron images. The design tool proved that misalignment and aperture fabrication errors can significantly decrease the resolution of the reconstructed neutron image. A theoretical model to describe the mechanism of bubble formation was developed. A bubble chamber for neutron imaging with Freon 115 as active medium was designed and implemented for the OMEGA laser system. High neutron yields resulting from deuterium-tritium capsule implosions were recorded. The bubble density was too low for neutron imaging on OMEGA but agreed with the model of bubble formation. The research done in here shows that bubble detectors are a promising technology for the higher neutron yields expected at National Ignition Facility (NIF).
Ghilea, Marian C.
The formation of reactive compounds in the gas mixture during Resistive Plate Chambers (RPCs) operation at the CERN Gamma Irradiation Facility (GIF) is studied. Results from two different types of chambers are discussed: 50ū50 cm2 RPC prototypes and two final CMS-RB1 chambers. The RB1 detectors were also connected to a closed loop gas system. Gas composition and possible additional impurities have been monitored in different gamma irradiation conditions both in open and closed loop modes using a gas chromatograph. Dedicated measurements for fluoride concentration in the exhausted gas line were performed at different irradiations and operation conditions using a specific electrode and a High-Performance Liquid Chromatograph. The efficiency of the purifiers system present in the closed loop in removing the F- and others impurities has also been investigated. Finally, the chemical composition of the RPC electrode surface has been analyzed using an electron microscope equipped with an EDS/X-ray.
Abbrescia, M.; Colaleo, A.; Guida, R.; Iaselli, G.; Loddo, F.; Maggi, M.; Marangelli, B.; Natali, S.; Nuzzo, S.; Pugliese, G.; Ranieri, A.; Romano, F.; Roselli, G.; Trentadue, R.; Tupputi, S.; Cavallo, N.; Fabozzi, F.; Paolucci, P.; Piccolo, D.; Polese, G.; Sciacca, C.; Belli, G.; Necchi, M.; Ratti, S.; Riccardi, C.; Torre, P.; Vitulo, P.; Anguelov, T.; Genchev, V.; Panev, B.; Piperov, S.; Sultanov, G.; Vankov, P.; Dimitrov, A.; Litov, L.; Pavlov, B.; Petkov, P.
The High Momentum Spectrometer drift chambers in Hall C at CEBAF
The multiwire drift chambers to be used in the High Momentum Spectrometer (HMS) at the Continuous Electron Beam Accelerator Facility (CEBAF) have been designed and constructed, and recently employed in initial data-taking runs. These chambers are used to reconstruct scattered charged particle momenta in the HMS using 12C and BeO 2 targets for incident electron energies up to 2.2 GeV. Offline analysis of the data indicate that these drift chambers have spatial resolution (per plane) of about 115 ?m (?) in rates approaching a kHz/wire/mm. It is expected that this performance will improve at higher momenta where multiple scattering contributions are smaller.
Baker, O. K.; Beaufait, J.; Carlini, R.; Cha, J.; Danagoulian, S.; Johnson, A.; Kross, B.; Majewski, S.; McCauley, A.; Naing, W.; Niculescu, G.; Niculescu, I.; Shin, T. S.; Vulcan, W.
The High Momentum Spectrometer Drift Chambers in Hall C at CEBAF
The mutiwire drift chambers to be used in the High Momentum Spectrometer (HMS) at the Continuous Electron Beam Accelerator Facility (CEBAF) have been designed and constructed, and recently employed in initial data-taking runs.These chambers are used to reconstruct scattered charged particle momenta in the HMS using 12C and BeO2 targets for incident electron energies up to 2.2 GeV.Offline analysis of the data indicate that these drift chambers have spatial resolution (per plane) of about 115 mu-m (sigma) in rates approaching a KHz/wire/mm.It is expected that this performance will improve at higher momenta where multiple scattering contributions are smaller.
Vulcan, William; Kross, Brian; Beaufait, Joseph; Baker, O.; Carlini, Roger; Majewski, Stanislaw; Johnson, A.; McCauley, A.; Niculescu, Gabriel; Niculescu, Maria-Ioana; Cha, Jinseok; Shin, Taeksu; Naing, Win; Danagoulian, Samuel
Asian Facilities
Asian underground facilities are reviewed. The YangYang underground Laboratory in Korea and the Kamioka observatory in Japan are operational and several astrophysical experiments are running. Indian Neutrino Observatory(INO) and China JinPing Underground Laboratory (CJPL) are under construction and underground experiments are being prepared. Current activities and future prospects at those underground sites are described.
Nakahata, M.
Focal Point Inside the Vacuum Chamber for Solar Thermal Propulsion
Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. The 20- by 24-ft heliostat mirror (not shown in this photograph) has dual-axis control that keeps a reflection of the sunlight on an 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. This photograph is a close-up view of a 4-in focal point inside the vacuum chamber at the MSFC Solar Thermal Propulsion Test facility. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.
Design characteristics of a heat pipe test chamber
LeRC has designed a heat pipe test facility which will be used to provide data for validating heat pipe computer codes. A heat pipe test chamber that uses helium gas for enhancing heat transfer was investigated. The conceptual design employs the technique of guarded heating and guarded cooling to facilitate accurate measurements of heat transfer rates to the evaporator and from the condenser. The design parameters are selected for a baseline heat pipe made of stainless steel with an inner diameter of 38.10 mm and a wall thickness of 1.016 mm. The heat pipe operates at a design temperature of 1000 K with an evaporator radial heat flux of 53 W/sq. cm.
Baker, Karl W.; Jang, J. Hoon; Yu, Juin S.
We present recent results of an extensive aging test, performed at the CERN Gamma Irradiation Facility, on two bakelite Resistive Plate Chambers (RPC) detectors. With a method based on a model describing the behavior of an RPC exposed to a large particle flux, we have periodically measured the electrode resistivity ? of the two detectors over 3 years. We observed a large increase of ? with time, from initial values of about 10 10 ? cm to more than 200ū10 10 ? cm . A corresponding degradation of the RPC rate capability, from about 3 kHz/cm2 to less than 200 Hz/cm2, was observed. The reversibility of the process, using a humid gas mixture, has also been studied.
Carboni, G.; De Capua, S.; Domenici, D.; Ganis, G.; Messi, R.; Passaleva, G.; Santovetti, E.; Veltri, M.
Cell culture in vivo by means of diffusion chamber system.
In a diffusion chamber (DC) system, cells are cultured in vivo - hence making it possible to minimize infection and foreign material contamination. In view of this merit, we devised a technique to combine a DC system and a scaffold to the end of incubating sufficient host cells for grafting. In the present study, PLGA sponge and rat bone marrow cells were encapsulated inside a DC and then placed inside the abdominal cavities of rats. DCs were removed at two or four weeks after grafting. At four weeks after grafting, fibrous and calcified tissue matching the shape of the PLGA sponge was formed. These results suggested that the PLGA sponge was an effective scaffolding material in inducing three-dimensional tissue formation and that combination with a DC system resulted in a cell mass matching the scaffold shape. In addition, the cells were cultured in vivo - which meant that DC culturing did not require special incubation facilities or technologies after grafting. PMID:19721273
Nakano, Kenjiro; Hayashi, Tatsuhide; Kawai, Hideki; Takei, Yukiko; Sato, Yosuke; Ando, Kimitoshi; Ono, Yuzo; Jinno, Satoshi; Kawakami, Toshiyuki; Maeda, Hatuhiko; Kawai, Tatsushi
Comments on settling chamber design for quiet, blowdown wind tunnels
Transfer of an existing continous circuit supersonic wind tunnel to Langley and its operation there as a blowdown tunnel is planned. Flow disturbance requirements in the supply section and methods for reducing the high level broad band acoustic disturbances present in typical blowdown tunnels are reviewed. Based on recent data and the analysis of two blowdown facilities at Langley, methods for reducing the total turbulence levels in the settling chamber, including both acoustic and vorticity modes, to less than one percent are recommended. The pertinent design details of the damping screens and honeycomb and the recommended minimum pressure drop across the porous components providing the required two orders of magnitude attenuation of acoustic noise levels are given. A suggestion for the support structure of these high pressure drop porous components is offered.
Beckwith, I. E.
Developing a fast ionization chamber for transfer reaction studies
Detection of beam and beam like recoils at far forward angles is often critical for radioactive beam measurements in inverse kinematics. Gas-filled ionization chambers are well suited for these applications, since they have moderately good energy resolution and can take prolonged exposure to beam compared to fragile semiconductor detectors. Conventional ion counters using a Frisch grid, however, have slow response times because the ionized electrons must travel long distances to the anodes. To reduce response times, a fast ion counter using a tilted window and tilted electrodes was developed and tested at ORNL's Holifield Radioactive Ion Beam Facility, modified from an original design by Kimura et al. [1]. The maximum counting rate and energy resolution, along with future plans for using the new ion counter, will be presented. [4pt] [1] K. Kimura et al., Nucl. Inst. Meth. Phys. Res. A 538, 608 (2005).
Chae, K. Y.; Bardayan, D. W.; Smith, M. S.; Schmitt, K. T.; Ahn, S. H.; Peters, W. A.; Strauss, S.
LOTIS facility initial operational capabilities: flexible user interfaces
The Large Optical Test and Integration Site (LOTIS) at the Lockheed Martin Space Systems Company in Sunnyvale, CA, has successfully reached Initial Operational Capability (IOC). LOTIS is designed for the verification and testing of optical systems. The facility consists of a large, temperature stabilized vacuum chamber that also functions as a class 10k cleanroom. Within this chamber and atop an advanced vibration-isolation bench are the 6.5 meter diameter LOTIS Collimator and Scene Generator, LOTIS alignment and support equipment. IOC included completion of the entire facility as well as operation of the LOTIS collimator in air. Wavefront properties of the collimator will be described as well as facility vibration isolation properties and turbulence levels within the collimator test chamber. User-specific test capabilities will also be addressed for two major areas of concern.
Hutchison, Sheldon B.; Bell, Raymond M., Jr.; Borota, Stephen A.; Cuzner, Gregor J.; Cochrane, Andrew T.
Centrifuge facility conceptual system study. Volume 2: Facility systems and study summary
The Centrifuge Facility is a major element of the biological research facility for the implementation of NASA's Life Science Research Program on Space Station Freedom using nonhuman species (small primates, rodents, plants, insects, cell tissues, etc.). The Centrifuge Facility consists of a variable gravity Centrifuge to provide artificial gravity up to 2 earth G's' a Holding System to maintain specimens at microgravity levels, a Glovebox, and a Service Unit for servicing specimen chambers. The following subject areas are covered: (1) Holding System; (2) Centrifuge System; (3) Glovebox System; (4) Service System; and (5) system study summary.
Synnestvedt, Robert (editor); Blair, Patricia; Cartledge, Alan; Garces-Porcile, Jorge; Garin, Vladimir; Guerrero, Mike; Haddeland, Peter; Horkachuck, Mike; Kuebler, Ulrich; Nguyen, Frank
Behavior of a Radial Time Projection Chamber
Using Gas Electron Multiplying (GEM) foils for amplification, the detector allows for three-dimensional representations of particle tracks through two half cylinders filled with gas. Developed for the Bound Nucleon Structure (BONUS) experiment at Jefferson Lab, the RTPC allows experimenters to study the quark composition of the neutron by scattering electrons from deuterium nuclei. The defining feature of the detector is that it allows for a complete view of the interaction of the electron and target gas, including the protons left over after a reaction on the neutron. This experiment seeks to understand the efficiency of the detector and its amplification (signal strength for a given ionization, as a function of detector gas and high voltage), by making a measurement of the amount of energy deposited in the chamber per unit length from cosmic radiation. In order to test each half of the Radial Time Projection Chamber we use an 85% Helium and 15% Dimethyl Ether (85/15 HeDME) and an 80/20 HeDME at optimal voltages to detect cosmic particles. The detector takes an electronic snapshot of the incident particle by examining the charge deposited as a function of time. The importance of this technology should not be underestimated. Radial Time Projection Chambers could, in some applications, replace current Time Projection Chambers and Wire Chambers.
Bradshaw, Peter
On-line noise monitoring at the Fast Flux Test Facility
An automated noise surveillance and diagnostics system (ANSDS) is being demonstrated at the Fast Flux Test Facility (FFTF). Three low-level, in-vessel fission chambers (LLFMs), three ex-vessel compensated ion chambers (CICs), and two accelerometers on the mechanism of one advanced absorber (ADVAB) control rod were monitored with an automated noise surveillance and diagnostic system (ANSDS) in late 1983.
Mullens, J.A.; Thie, J.A.; Campbell, L.R.
78 FR 76750 - Drawbridge Operation Regulation; Chambers Creek, Steilacoom, WA
Federal Register 2010, 2011, 2012, 2013
...Chambers Creek Railway Bridge across Chambers...locking out the power to the drive system while the work...Chambers Creek Railway Bridge across Chambers...bearing in the lift system, replacing lower...locking out the power to the drive...
BPSG boron spike generation investigated by chamber pressure monitoring
Mechanism of boron spike generation in BPSG film is discussed. Process chamber pressure traces are monitored when individual source gases are introduced. Changes in BPSG dopant profile due to differing chamber conditions can be identified by a simple method of monitoring the chamber pressure level. The mechanism of the boron spike is explained. The chamber conditions can be controlled by
Toshiya Yokota; Takamichi Yamaura; Kuniaki Orikasa; Masayuki Higashimoto; Akihiko Ishida
Spar buoy construction having production and oil storage facilities and method of operation
This patent describes a floating structure including oil storage capacity and production facilities and adapted to be anchored by catenary mooring lines at a subsea well location, the combination of: a vertical elongated hull means having means to maintain the hull means in vertical position; the hull means including a vertical oil storage chamber means for storing oil and extending for a major portion of the height of the floating structure; vertical variable ballast chamber means extending from the bottom of the storage chamber means to above the top of the oil storage chamber means and selectively filled with ballast to maintain the center of gravity of the structure a selected distance from the center of buoyancy of the structure; work chamber means in the hull means above the oil storage chamber means; means in the work chamber means and in the variable ballast chamber means for controlling the amount of ballast in the variable ballast means; means in the oil storage chamber means and in the work chamber means for feeding oil to the oil storage chamber means and for removing water therefrom as oil is introduced therein; a central longitudinal passageway through the hull means; a riser means extending into the passageway from the subsea well location and terminating at the work chamber means; means on the riser buoyant tank means and on the hull means in the central passageway for guiding relative movement between the hull means and the riser means.
Daniell, A.F.
Over the past thirty years, scientists at the Environmental Protection Agency's (EPA) Fluid Modeling Facility (FMF) have conducted laboratory studies of fluid flow and pollutant dispersion within three distinct experimental chambers: a meteorological wind tunnel, a water-channel ...
Outdoor smog chamber experiments to test photochemical models. Final report May 78-May 81
The smog chamber facility of the University of North Carolina was used in a study to provide experimental data for developing and testing kinetic mechanisms of photochemical smog formation. The smog chamber, located outdoors in rural North Carolina, is an A-frame structure covered with Teflon film. Because the chamber is partitioned into two sections, each with a volume of 156 cu m, two experiments can be conducted simultaneously. The dual chamber is operated under natural conditions of solar radiation, temperature, and relative humidity. In this study, 115 dual all-day experiments were conducted using NOx and a variety of organic species. The organic compounds investigated included various paraffins, olefins, aromatics and oxygenates, both singly and in mixtures of two or more components. In this report the data collected over the three-year period of the study are described. The experimental procedures and analytical methods used in this study and the limitations and uncertainties of the data are discussed. Guidance for modeling of the data is also given, including a detailed discussion of how to estimate photolytic rate constants from the available UV and total solar radiation data and how to treat such chamber artifacts as dilution, wall sources and losses of pollutants, and reactivity of the background air.
Feffries, H.E.; Kamens, R.M.; Sexron, K.G.; Gerhardt, A.A.
Measurements of a 1/4-scale model of an explosives firing chamber
In anticipation of increasingly stringent environmental regulations, Lawrence Livermore National Laboratory (LLNL) proposes to construct a 60-kg firing chamber to provide blast-effects containment for most of its open-air, high-explosive, firing operations. Even though these operations are within current environmental limits, containment of the blast effects and hazardous debris will further drastically reduce emissions to the environment and minimize the generated hazardous waste. The major design consideration of such a chamber is its overall structural dynamic response in terms of long-term containment of all blast effects from repeated internal detonations of high explosives. Another concern is how much other portions of the facility outside the firing chamber must be hardened to ensure personnel protection in the event of an accidental detonation while the chamber door is open. To assess these concerns, a 1/4-scale replica model of the planned contained firing chamber was designed, constructed, and tested with scaled explosive charges ranging from 25 to 125% of the operational explosives limit of 60 kg. From 16 detonations of high explosives, 880 resulting strains, blast pressures, and temperatures within the model were measured to provide information for the final design. Factors of safety for dynamic yield of the firing chamber structure were calculated and compared to the design criterion of totally elastic response. The rectangular, reinforced-concrete chamber model exhibited a lightly damped vibrational response that placed the structure in alternating cycles of tension and compression. During compression, both the reinforcing steel and the concrete remained elastic.
Pastrnak, J.W.; Baker, C.F.; Simmons, L.F.