A method and apparatus for placing objects on a storage device of a storage system and reconstructing data of objects in the storage device. The storage system stores data as objects and implements a RAID architecture including a plurality of the storage devices, and a disk controller for processing Object-based Storage Device (OSD) commands. Each object includes data and attribute. Parity data is calculated for reconstructing an object upon occurrence of a storage device failure. Each storage device includes plural stripes each having a predetermined length. Each object is stored in a stripe wherein an attribute is stored in the head of the stripe and data is stored after the attribute. When the object size exceeds the stripe length, the remainder of the object is stored in the next stripe, and when another object is to be stored, an attribute is stored at a head of a further next stripe and data is stored just after the attribute.

The present invention relates generally to placing and reconstructing data in a storage system. More particularly the present invention relates to a method, apparatus and computer program for placing and reconstructing data in an object-based storage system.
Recent storage systems that are used in the high-end or mid-range computer systems usually adopt the Redundant Array of Inexpensive Disks (RAID) architecture. The RAID architecture provides various levels including, for example, RAID levels 1-5 defined as follows:
RAID 1: uses "mirroring" techniques.
RAID 2: stores each bit of each word of data, plus Error Detection and Correction (EDC) bits for each word, such as a Hamming Code, on separate disk drives. This is also known as "bit striping".
RAID 3: is based on the concept that each disk drive storage unit has internal means for detecting a fault or data error. Therefore, it is not necessary to store extra information to detect the location of an error. Thus, a simpler form of parity-based error correction can be used. In this approach, the contents of all storage units subject to failure are "Exclusively OR-ed" (XOR) to generate parity information. The resulting parity information is stored in a single redundant storage unit. If a storage unit fails, the data on the redundant storage unit can be reconstructed onto a replacement storage unit by XOR-ing the data from the remaining storage units with the parity information.
RAID 4: uses the same parity error correction concept of the RAID 3 architecture, but improves on the performance of the RAID 3 architecture with respect to random reading of small files by using block-level interleaving. The RAID 4 architecture reads and writes a larger minimum amount of data, typically a disk sector, to each disk. This is also known as block striping. A further aspect of the RAID 4 architecture is that a single storage unit is designated as the parity unit.
RAID 5: uses the same parity error correction concept of the RAID 4 architecture and independent actuators, but improves on the writing performance of the RAID 4 architecture by distributing the data and parity information across all of the available disk drives. Typically, "N+1" storage units in a set, also known as a "redundancy group," are divided into a plurality of equally sized address areas referred to as blocks. Each storage unit generally contains the same number of blocks. Blocks from each storage unit in a redundancy group having the same unit address ranges are referred to as "stripe group". Each stripe group has N blocks of data, plus one parity block on one storage unit containing parity for the remainder of the blocks. Further, each stripe group has a parity block, wherein the parity blocks are distributed on different storage units. Parity updating activity associated with every modification of data in a redundancy group is therefore distributed over the different storage units. No single storage unit is burdened with all of the parity update activity.
As described above, the current RAID techniques generate redundant information on either one of a bit, byte, or block basis.
Recently another technological trend has begun, where data is stored into the storage devices such as magnetic disks on an object basis, not a block basis. Such a storage device or system which stores data as an object is called an Object-Based Storage Device (OSD).
Each object as defined includes data and an attribute. The Attribute includes information such as the size of the data, user identification (ID) information, etc. Since the attribute maintains the size of the data in the object, the object size is variable, different from current storage devices such as Hard Disk Drives (HDDs) which use fixed-length blocks. These objects can be used to store a variety of data, including files, database records and e-mail. The combination of data and attribute allows an OSD to make decisions on data layout or quality of service on a per-object basis, thereby improving performance, flexibility and manageability.
The disadvantage of RAID architectures is that they take a large amount of time to reconstruct data of a failed disk drive, because the storage system adopting the RAID architecture reads all data blocks in the disk drives that are associated with the failed disk drive. The data reconstruction process of the RAID architecture has to be performed on all data blocks of the disk drives even if only a small amount of data stored in the disk drives require reconstruction. Such is partly due to traditional RAID systems not maintaining information regarding the location of data or files in the disk drives.
OSD maintains information indicating where each object is stored in the OSD. However, current OSD standards do not take into consideration the functionalities necessary to implement a RAID architecture in an OSD. Particularly, the current OSD standards do not provide a method for the placement and reconstruction of data in an OSD which implements a RAID architecture.
U.S. Pat. No. 5,208,813 discloses a method for reconstructing data of failed storage devices in redundant arrays. However, the method disclosed in U.S. Pat. No. 5,208,813 is only applied to data reconstruction of all data blocks in the failed storage devices implementing a RAID architecture.
ANSI T-10 Working Draft discloses the concept of OSD (ANSI T-10 Working Draft). However, this draft does not consider the functionalities or features necessary to apply OSD technology to RAID storage systems.
Therefore, a need exists for a method and apparatus for placing objects on an RAID storage system and reconstructing data in the RAID storage system.

Method and apparatus for reconstructing data in object-based storage arrays


An inflatable wrap for promoting venous or arterial blood flow enhancement in the human hand. The wrap comprises an inflatable bag fastened to a backing material. The bag is shaped to fit against the palm of the hand and portions of the back of the hand. The backing material comprises a base portion substantially corresponding to the palm of the hand and two or more interengageable lobes that may be fastened together across the back of the hand to retain the inflatable bag securely against the hand such that upon inflation of the bag a pumping pressure is applied positively to the hand to promote the venous or arterial flow enhancement.

A venous pump mechanism is known in the region of the hand essentially including the proximal phalanges of the digits and thumb and the adjacent regions of the palm and dorsum; this mechanism is naturally brought into operation upon a tight doubling of the fist whereupon venous return flow ensues from the entire arm.
It has been established that by periodically squeezing this region without requiring a patient to double his fist, i.e., by external application of squeezing essentially local to this region, venous return flow may be efficiently stimulated even in the case of a degree of venous obstruction in the wrist or elsewhere in the involved arm.
Additionally, it has been established that such externally applied squeezing pressure can also be accompanied by an improvement in arterial flow in the involved arm.
In European Patent No. 0 228 768 there is disclosed an inflatable mitt for engaging the promimal phalanxes of the fingers and thumb of the hand and adjacent regions such that upon periodic pressurization, localized application of a squeezing force may be applied to those parts to stimulate venous flow.
In related European patent application No. 89305062.5 there is disclosed a circumferentially tying inflatable bag shaped for radially inward active engagement solely with a human hand which may be cyclically inflated, the squeezing pressure then being held for a short time to stimulate arterial flow.
A further similar medical appliance is disclosed in "The Return of Blood to the Heart" (Second Edition) by Gardner and Fox (Published by John Libbey), on page 130, FIG. 69 depicts a pneumatically compressible mitten, the mitten body being formed of slitted Neoprene and enclosing an inflation pad wherein Velcro straps are provided externally to direct the force of inflation towards the hand.
All these medical appliances suffer the disadvantage that although an efficacious increase in venous or arterial blood flow is achieved, all require that a glove or mitten-like structure be worn over the affected hand.
In cases to be treated by medical appliances of these types, the affected hand is likely to be painfully swollen and considerably less mobile than usual.
It is, therefore, clear, that where the fingers of the hand must be maneuvered through particular finger holes in a glove, or where the hand must be maneuvered through the appropriate holes in a mitten, the fitting process is likely to be both time consuming from the point of view of the medical practitioner and painful from the point of view of the patient, and may in some cases be impossible.
A further necessity, of course, will be the requirement that a wide range of sizes of such medical appliances be kept to fit the range of sizes of hand encountered, both in terms of normal variation and degree of swelling.


A digital signal decoding device according to an aspect of the present invention is a digital signal decoding device for generating a binary code sequence by maximum likelihood estimation from a convolutionally encoded input signal sequence, includes an add-compare-select unit configured to compare only two metric values one unit time before the calculation time of a predetermined branch metric value calculated from the input signal sequence at two successive times at each time, to add the predetermined branch metric value to the two metric values independently of the compare process, to select one of the two sums in accordance with the comparison result of the two metric values, and to output the selected value as a metric value to be used at the next time.

1. Field of the Invention
The present invention relates to a digital signal decoding device and digital signal decoding method, which are applied to a digital signal reproduction apparatus such as an optical disk apparatus or the like and, more particularly, to a digital signal decoding device and digital signal decoding method, which are applied to a signal reproduction circuit that exploits a PRML technique.
2. Description of the Related Art
As recording media that can record and reproduce digital data, optical disks represented by DVDs (Digital Versatile Disks) are known. A DVD-RAM as one of DVDs comprises a signal recording layer. When this recording layer is irradiated with a laser beam having appropriate energy, its crystal state changes. When the recording layer is irradiated with a laser beam of appropriate energy again, reflected light is obtained in a quantity corresponding to the crystal state of the recording layer. By detecting this reflected light, digital data recorded on the recording layer can be reproduced.
In recent years, a PRML technique is adopted to improve the recording density. Jpn. Pat. Appln. KOKAI Publication No. 9-17130 (reference 1) discloses the PRML technique. The contents of that technique will be briefly explained below.
Partial Response (PR) is a method of reproducing data while compressing a required signal band by positively utilizing intersymbol interference (interference between reproduction signals corresponding to bits which are recorded at neighboring positions). PR can be further categorized into a plurality of different classes depending on the way intersymbol interference is produced at that time. For example, in case of class 1, recorded data "1" is reproduced as 2-bit reproduction data "11", and intersymbol interference is produced for the subsequent 1 bit. A Viterbi decoding method (ML) is a kind of so-called maximum likelihood sequence estimation methods, and reproduces data on the basis of information of signal amplitudes at a plurality of times by effectively using the intersymbol interference rules of a reproduction waveform. For this process, synchronous clocks, which are synchronized with a reproduction waveform obtained from a recording medium, are generated, and the reproduction waveform itself is sampled using the clocks to be converted into amplitude information. After that, the amplitude information undergoes appropriate waveform equalization to be converted into a predetermined PR response waveform. A Viterbi decoder then outputs a maximum likely data sequence as reproduction data using old and current sample data. A combination of the aforementioned PR method and Viterbi decoding method (most likelihood decoding) is called a PRML method. PR can calculate a reproduction signal sequence by a convolution operation of an impulse response of a predetermined PR class with respect to a recorded data sequence. In other words, PR can express a process from recording to reproduction as an arbitrary finite state machine having N states (N=2m−1 where m is the response length of the predetermined PR). A two-dimensional graph that expresses (N) states at arbitrary time k of this finite state machine as nodes which line up in the vertical direction, and expresses transition from the respective states to those at time (k+1) as branches is called a trellis diagram. A Viterbi algorithm is used to obtain a recorded signal sequence from a reproduction signal sequence, i.e., to find the shortest path on this trellis diagram, and is equivalent to a dynamic programming problem with respect to a multistage decision process. A Viterbi decoder based on this algorithm is used to make most likelihood estimation of a transmission sequence in band-limited channels having intersymbol interference. That is, a code sequence that minimizes a distance metric (distance function) associated with a sequence of reception signals such as the sum total of square errors of the sequence of reception signals or the like is selected from possible code sequences. In order to put this PRML technique into practice, a high-precision adaptive equalization technique that obtains a reproduction signal as a response of a predetermined PR class, and a high-precision clock reproduction technique that supports the former technique are required.
A runlength limited code used in the PRML technique will be explained below. A PRML reproduction circuit generates clocks synchronized with a signal itself reproduced from a recording medium. In order to generate stable clocks, the polarity of a recorded signal must be inverted within a predetermined period of time. At the same time, the polarity of the recorded signal must be inhibited from being inverted during the predetermined period of time, so as to reduce the maximum frequency of the recorded signal. A maximum data length free from inversion of the polarity of the recorded signal is called a maximum runlength, and a minimum data length free from inversion of the polarity is called a minimum runlength. A modulation rule which has a maximum runlength of 8 bits and a minimum runlength of 2 bits is called (1, 7)RLL. Also, a modulation rule which has a maximum runlength of 8 bits and a minimum runlength of 3 bits is called (2, 7)RLL. As a typical modulation/demodulation method used in an optical disk, (1, 7)RLL and EFM Plus are known, and are disclosed in U.S. Pat. No. 5,696,505 (reference 2).
In recent years, the data reproduction speed of an optical disk apparatus and the like is increasing rapidly, and an operation speed of 500 MHz or higher is required. The consumption power of the data reproduction circuit increases in proportion to the operation speed. Also, an increase in recording linear density requires a PRML signal process of higher orders. Use of PRML of higher orders requires more complicated signal processes, and a larger-scale circuit. However, an optical disk apparatus with low consumption power is demanded due to prevalence of notebook type PCs, and the consumption power of a PRML reproduction circuit must be considerably reduced. Furthermore, a Viterbi decoder as a part of the PRML reproduction circuit bottlenecks an increase in processing speed since it executes feedback loop processes called ACS processes in addition to its complicated circuit.
In order to solve these problems, a technique that can simplify the circuit of a Viterbi decoder is disclosed in Jpn. Pat. No. 2,755,375 (reference 3). Furthermore, a technique that can improve the operation speed while suppressing an increase in circuit scale by adding a preload process called Radix-4 to the technique disclosed in this reference 3 is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-22840 (reference 4). Furthermore, a technique that can improve the operation speed of a Viterbi decoder is disclosed in "A New architecture for the fast Viterbi algorithm", Inkyu Lee, Sonntag, J. L., Global Telecommunications Conference, 2000, GLOBECOM '00. IEEE, Volume: 3, 2000, pp. 1664-1668 (reference 5).
According to the technique disclosed in reference 3, a circuit can be simpler than a Viterbi decoder using the general Viterbi algorithm, but the operation speed cannot be improved.
According to the technique disclosed in reference 4, the preload process results in an increase in operation word length, and increases the consumption power beyond the improved processing speed.
Furthermore, according to the technique disclosed in reference 5, add and compare processes unique to the Viterbi algorithm can be parallelly executed, and the operation speed can be improved. However, the circuit complexity increases considerably due to the parallel processes, resulting in an increase in consumption power.

Digital signal decoding device and digital signal decoding method


Provided is a method for fabricating a semiconductor device including the following steps. A silicon-containing conductive layer is formed on a substrate. Then, a dielectric layer is formed around the silicon-containing conductive layer. A portion of the dielectric layer is removed to expose a first sidewall of the silicon-containing conductive layer. A shielding structure is formed on a partial surface of the silicon-containing conductive layer, and the shielding structure exposes at least the first sidewall. A metal layer is formed on the substrate to cover the silicon-containing conductive layer not covered by the shielding structure. A salicide process is performed to form a silicide layer.

1. Field of the Invention
The invention relates to an electronic device and a method for fabricating the same, and more particularly, to a semiconductor device and a method for fabricating the same.
2. Description of Related Art
A silicide layer has the advantages of, for instance, high melting point, high stability, and low resistance, and is currently widely applied to integrated circuits. Due to the gradual miniaturization of integrated circuit techniques, the linewidth, the contact area, and the junction depth . . . etc. are gradually becoming smaller. To effectively increase the performance quality of the devices, lower resistance, and reduce signal transmission delay caused by resistance and capacitance, a polycide gate is often used to replace the known polysilicon gate such that a silicide layer can be used to effectively reduce junction resistance.
The current salicide process includes covering a metal layer on the surface and the sidewall of a patterned polysilicon such that the salicide process can be performed from three sides at the same time. However, the silicide layer formed by the method often generates necking or line bending on the contour. Therefore, the phenomenon of peeling or fracture readily occurs to the silicide layer. Moreover, although a uniform silicide layer can be formed by performing the salicide process on only the top surface, the thickness of the resulting silicide layer is too thin and is therefore unsatisfactory. The resistance of the silicide layers and the interface thereof formed by the two processes above is higher.
Moreover, when various semiconductor devices are integrated on the same chip, the silicide layers of the devices having various linewidths are also different from one another. For instance, in an integrated device having both a narrow linewidth and a wide linewidth, if a silicon-containing conductive layer having a narrow linewidth is completely silicidated, then poor silicide is generated for a silicon-containing conductive layer having a wide linewidth due to insufficient time of the salicide process. On the other hand, if the silicon-containing conductive layer having a wide linewidth is completely silicidated in a self-aligned manner, then necking or bending occurs to the silicon-containing conductive layer having a narrow linewidth due to over-silicidation, and the phenomenon of peeling or fracture may even occur. Therefore, how to completely silicidate silicon-containing conductive layers having different linewidths without causing necking or bending to the silicide layer or the generation of poor silicide is an issue that needs to be solved.

Semiconductor device and method for fabricating the same


A method and apparatus for in situ removal of biodegradable contaminants from ground water or soil , or both by injecting oxygen gas into ground water containing a biodegradable contaminant in a volume low enough to avoid migration or volatilization of the contaminant but high enough to enhance the rate of biodegradation of the contaminant are described.

Contamination of subsurface soil and ground water by petroleum products, including gasoline and fuel oils, is a recurring problem, particularly by leakage from underground storage tanks. In addition, spills and improper disposal of petroleum products cause many contaminated sites.
Among the diverse remediation technologies which have been developed to treat contaminated subsurface soil and ground water are the techniques of air sparging and bioremediation.
In general, air sparging involves the injection of high volumes of pressurized air into ground water through injection wells. The air flow through the ground water causes volatile contaminants to volatilize and migrate through the ground water and the vadose zone. To avoid contamination of the environment the ensuing vapors are directed to extraction wells and withdrawn from the wells under vacuum. The output of the withdrawal well is connected to a series of scrubbers, condensers and neutralizers which remove contaminants from the air stream.
Bioremediation relies on the ubiquitous microorganisms found in soil and ground water and in vadose zones which are capable of biodegrading the contaminants. Aerobic microorganisms convert hydrocarbon fuels into carbon dioxide and water. This method relies on oxygen availability and nutrients in the soil to support the microorganisms. Without enhancing the oxygen availability it is expensive and difficult to sustain a successful rate of biodegradation.
Combining the techniques of air sparging and bioremediation provides an integrated system which is capable of enhancing the bioremediation of the various zones of contamination underground by increased rates of biodegradation. Air contains 80% nitrogen and 20% oxygen and is not an efficient source of oxygen and requires high volumes of air to provide sufficient oxygen. This integrated system still causes the undesirable migration and volatilization of volatile contaminants through the vadose zone. Release of such vapors above ground must be controlled to meet air quality standards and this requires venting and extraction of the vapors. In addition high volume gas flow causes drying out of the zones and channeling which leads to progressively more leakage and escape of vapors and reduced efficiency of biodegradation. Drying out of the soil due to the air flow can render it biologically inactive. Channeling caused by high volume air flow reduces the efficiency of oxygen transfer to the aqueous phase and hence to the microorganisms. Maintaining a moist environment and avoiding channeling over the term of the operation are important for efficient biodegradation.
A pump-and-treat method of in situ bioremediation has been reported (Carter, S. R. and Clark, J. E.; Oxygen-Enhanced In Situ Bioremediation In A Sand And Gravel Aquifer, pp 551-558 of In Situ Aeration: Air Sparging, Bioventing, and Related Remediation Process, Ed. Robert E. Hinchee, Ross N. Miller and Paul C. Johnson. Battelle Press 1995). The remediation system included ground water recovery and oxygenation of the ground water in a packed-tower air stripper to remove volatiles and increase dissolved oxygen levels. The oxygenated water was injected back to the subsurface through horizontal injection galleries.
U.S. Pat. Nos. 5,221,159; 5,277,518 and 5,472,294 disclose methods and apparatuses for in situ removal of contaminants from soil or from ground water, or both by combination sparging and bioremediation techniques which volatilize and biodegrade the contaminants.
U.S. Pat. No. 5,277,518 discloses a method and apparatus for in situ removal of contaminants from soil or from ground water, or both by (col. 3, lines 46-54) establishing at least one injection well into the ground water; injecting oxygen-containing gas into the injection well to volatilize and biodegrade contaminants in the ground water and soil; and permitting upward migration of the volatilized and biodegraded contaminants without one or more venting conduits. In other words, no venting wells, venting laterals, or equivalent equipment is used. A sparger in the injection well introduces pressurized air into the aquifer so as to stimulate circulation of the air and mixture of the air and water. This remediation unit requires the use of air injection wells to volatilize contaminants which then migrate through the vadose zone and are vented to the atmosphere. Some of the contaminants are biodegraded by microorganisms in the soil and ground water. The air flow rates must be controlled so that the air quality standards are not exceeded by the fluids vented by the remediation unit.
U.S. Pat. No. 5,472,294 discloses a method and apparatus for in situ removal of contaminants from soil or from ground water, or both in a similar manner as disclosed in U.S. Pat. No. 5,277,518. In addition an apparatus (FIG. 11) is provided which allows the addition of supplemental oxygen-containing gas, including oxygen gas, at high pressure and low volume through a feed tube attached to the sparger. The feed tube provides the oxygen-containing gas to an expander to more widely disperse the gas into the contaminated zone.
It is an object of this invention to provide a method for the efficient removal of biodegradable contaminants from soil or ground water, or both without causing migration or volatilization of the contaminants.
It is an object of this invention to provide a method for the efficient removal of biodegradable contaminants from soil or ground water, or both without releasing the contaminants into the atmosphere.
It is an object of this invention to provide a method for the efficient removal of biodegradable contaminants from soil or ground water, or both by enhancing the rate of biodegradation of the contaminants by native microorganisms in the soil or ground water.
It is an object of this invention to provide a method for the efficient removal of biodegradable contaminants from soil or ground water, or both by ensuring complete dissolution of injected oxygen into the ground water.


Methods and apparatuses in a wireless communication system. A method of operating a base station (BS) includes receiving a set of uplink signals; estimating, based on a subset of the set of uplink signals, uplink channels; estimating a timing offset (TO) and a frequency offset (FO) for a subset of the estimated uplink channels; compensating, based on the estimated TO and FO, the subset of the estimated uplink channels to generate TO and FO compensated uplink channel estimates; and generating channel prediction information based on the compensated subset of the estimated uplink channels.

Massive MIMO (mMIMO) technology is an important technology to improve the spectral efficiency of 4th generation (4G) and 5G cellular networks. A number of antennas in mMIMO is typically much larger than the number of user equipment (UE), which allows base station (BS) to perform multi-user downlink (DL) beamforming to schedule parallel data transmission on the same time-frequency resources. However, performance of mMIMO depends heavily on the quality of CSI at a BS. It has been recently verified that the multi user-MIMO (MU-MIMO) performance degrades according to UE mobility.

Uplink timing and frequency offset estimation and compensation for CSI estimation and tracking


In a magnet system with two coil systems of different mean diameter arranged coaxially with respect to the longitudinal axis of the system defined by the direction of the field in the homogeneity region, which are rotationally symmetrical and are arranged symmetrically about the transverse median plane of the system perpendicular to the longitudinal axis and can carry exciting currents which result in overlapping magnetic fields that compensate, at least approximately, for the dipole fields of the two coil systems, an operating mode selector switch device (22) configured as a superconducting network is provided, by means of which the magnet system (10) can also be switched, as an alternative to the operating mode which provides considerable dipole-field compensation in the outer space of the magnet system (10), to that operating mode in which the magnetic fields generated by the two coil systems (11 and 12) at the center thereof are aligned in the same direction. In a special configuration, the ratio B.sub.0i :B.sub.0a between the values of the field strengths B.sub.0 1 and B.sub.a generated by the inner field coil (11) and the outer field coil (12) is equal to 3.

The invention relates to a magnet system with superconducting field coils for generating a constant magnetic field, suitable for NMR experiments, which has a high field strength in the experimental volume and sufficient homogeneity for NMR tomographic and/or spectroscopic experiments.
Such magnet systems, which have two coil systems of different mean diameters arranged coaxially with respect to the longitudinal axis defined by the field direction in the homogeneity region, which are rotationally symmetrical and are arranged symmetrically about the transverse median plane perpendicular to the longitudinal axis, and which can be excited with currents which generate magnetic fields that compensate, at least approximately, for the dipole fields of the two coil systems in the outer space of the magnet system, are known (for example from EP 0 138 270 A2, EP0 144 171 A1, DE 38 29 175 A1, and GB 2 206 242 A).
In the magnet system disclosed by EP 0 144 171 A1, the field coils whose (dipole) fields are intended to be largely compensated for in the outer space of the magnet system are permanently wired in series. In the magnet system disclosed by DE 38 29 175 A1, parallel wiring of the field coils which develop the two oppositely aligned magnetic moments is also disclosed as an alternative to series connection thereof. Although these known systems can be operated with currents of varying intensities without thereby significantly impairing the shielding effect in the outer space, the usable field strengths are nevertheless limited, by the fact that the magnetic field generated by the outer field coil is always aligned opposite to the magnetic field generated by the inner field coil, to a value that is less than the absolute field strength of the magnetic field generated by the inner field coil.
In contrast, the magnet systems of the aforesaid kind disclosed by EP 0 138 270 A2 and GB 2 206 242 A are configured in such a way that the two superconducting field coils can be energized with currents of different strengths, with at least one of the two field coils being energized inductively, and the two field coils each forming a self-contained current circuit. Depending on the current strength value to which the shield--i.e., outer--field coil is energized, it is then possible to vary the field strength that can be utilized for an experiment between a minimum value--which results when the outer, shielding field coil is energized to a maximum value for its operating current strength (assuming a predetermined charge of the inner field coil)--and a maximum value which results when the outer, shielding field coil is not energized.
The magnetic field strengths in the experimental volume that can be utilized with known magnet systems (i.e., those having active shielding provided by an external field coil in the outside space) are therefore two low for many experimental purposes, so that the known magnet systems appear to be suitable, at best, for tomographic experiments in which the primary requirement is good field homogeneity in the largest possible experimental volume, while high field strength is not of critical importance. However, the known magnet systems are therefore unsuitable for investigative purposes such as NMR spectroscopy experiments, in which less emphasis is placed on good homogeneity of the magnetic field in the largest possible experimental volume at moderate field strength, while the highest possible field strength--along with good field homogeneity in a relatively small experimental volume--is important.

Magnet system with superconducting field coils


The present invention provides a composite wall panel with good thermal insulation and sufficient strength for structural use which is designed for the fabrication of energy efficient building. The composite wall panel of the present invention comprises a foamed concrete core with sufficient compressive strength and low thermal conductivity which is sandwiched between two lightweight ductile fiber reinforced cementitious composite (FRCC) protective layers with low thermal conductivity, good barrier resistance to moisture/chloride ion/gas, multiple cracking as well as certain amount of steel reinforcements. These composite wall panels are useful in a variety of buildings in both cold and hot regions.

With increasing concerns of the greenhouse gas emission arising from electricity consumption and the rising energy cost, the demand for better thermal insulation in the building enclosures has drastically increased over the past few years. To improve the thermal insulation of building envelope, increasing the wall thickness is one of the solutions. However, it is less practical than directly reducing the overall thermal conductivity (k) of the envelopes of buildings.
For a given wall thickness, the thermal insulation of building envelope could be improved if the wall is constructed with foamed concrete with low thermal conductivity instead of normal concrete. Foamed concrete is a porous cementitious material formed by entrapping homogeneous pores into cementitious matrix using appropriate method. At present, introduction of pores can be achieved through mechanical means either by preformed foaming or mix foaming (Nambiar & Ramaurthy; 2007). The foaming agent for preformed foaming includes both the protein-based and synthetic-based foaming agent. Previous studies show that the thermal conductivity of concrete is usually proportional to its density (Shrivastava, 1977), and a decrease of dry density by 100 kg/m3 results in a reduction of thermal conductivity by 0.04 W/mK for lightweight aggregate foamed concrete (Weigler & Karl, 1980). Jones and McCarthy (2003) showed that foamed concrete with a plastic density of 1000 kg/m3 exhibited a typical thermal conductivity of 0.23-0.42 W/mK.
Since the strength of foamed concrete also decreases with increasing porosity, the strength of foamed concrete with sufficiently low thermal conductivity is always below the strength level for structural use. It would be desirable to develop a foamed concrete composition with both sufficiently low thermal conductivity and sufficient strength for structural use.
When foamed concrete is used to replace normal concrete, the presence of the pores will promote the penetration of moisture, chloride ion and carbon dioxide into foamed concrete and the durability against corrosion of steel reinforcement may be a concern. Previous studies showed that both the transport properties (including water permeability and chloride diffusivity) and carbonation resistance of foamed concrete are similar to those of normal concrete of similar strength (Chandra & Berntsson, 2003; Osborne, 1995). One important point to highlight, however, is that the test results are based on measurements on foamed concrete members that are not loaded and therefore not cracked. However, in practice, due to the low toughness of foamed concrete, it is easy for cracks to form in both foamed concrete and its protective coating/surface treatment (if applied) under loading. While the formation of fine cracks should not affect structural performance (as the tensile load capacity of concrete is neglected anyways), it can severely degrade the transport properties and carbonation resistance of foamed concrete (Chandra & Berntsson, 2003). Experimental findings in those studies actually indicated severe steel rusting at the vicinity of cracks in foamed concrete. With such a view, lightweight high performance fiber reinforced cementitious composites (FRCC) layers could be used, as a protective layer, together with foamed concrete. As there are no coarse aggregates used, the structure of FRCC can be designed as dense as that of normal concrete and even high strength concrete. More importantly, lightweight high performance FRCC can be designed to show high ductility, strain hardening and multiple cracking behaviors, and crack control capability under loading (Wang & Li, 2003). Indeed, previous studies showed that high performance FRCC has the ability to control crack openings to below 0.05 mm under loading (Li & Leung, 1992; Lepech & Li, 2009). According to Wang et al (1997) and Djerbi et al (2008), the water permeability and chloride diffusivity of concrete will not be affected by cracks that are so fine. In addition, with low density and thermal conductivity of lightweight FRCC, the thermal insulation performance of lightweight FRCC layer would be compatible to that of foamed concrete. It is hence possible to use lightweight FRCC layer to protect foamed concrete from external environmental factors under both loading and unloading conditions.
U.S. Pat. No. 6,969,423 discloses lightweight high performance fiber reinforced cementitious composite (FRCC) showing low density, high ductility and strain hardening as well as multiple cracking behaviors. However, both the thermal conductivity and transport properties of the lightweight FRCC are not disclosed.
With such a view, it would be desirable to develop a lightweight high performance FRCC layer with good thermal insulation and sufficient barrier resistance to moisture/chloride ion/carbon dioxide penetration, as a protective layer for foamed concrete.

Composite wall panel with low thermal conductivity and sufficient strength for structural use

NANO AND ADVANCED MATERIALS INSTITUTE LIMITED


A flow valve is provided that comprises a valve chamber including first and second valve port openings in communication with first and second inlet/outlets. The valve further includes a shaft rotatably disposed in the valve chamber, and a first valve plate rotatably coupled to the shaft that is disposed in the valve chamber over the first valve port opening. The first valve plate has a first tapered slot positioned therein so as to align with the first valve port opening. The first valve plate is configured to rotate from its closed position covering the first valve port opening to an open position, where rotation of the first valve plate adjustably positions a wider or narrower portion of the first tapered slot over the first valve port opening. The valve further includes a second valve plate that is configured to rotate with the first valve plate, and to cover the second valve port opening.

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In a conventional refrigeration or HVAC system, flow control devices are typically utilized to control the flow of working fluids in a refrigeration system. In general, the refrigeration system would include a compressor that forces the particular refrigerant used in the system through a condensing coil, where the refrigerant vapor liquefies. The liquid refrigerant passes through a thermostatic expansion valve, expanding the high pressure liquid refrigerant to a low pressure vapor. The low pressure, low temperature refrigerant discharged from the thermostatic expansion valve is then directed through an evaporator coil for absorbing heat and thus refrigerating the space inside the container surrounding the evaporator coil.
The thermostatic expansion valve functions to meter the flow of refrigerant into the evaporator coil in proportion to the rate of evaporation of the refrigerant in the evaporator coil, and is responsive to the temperature and pressure of the refrigerant leaving the evaporator coil. In this manner, the thermostatic expansion valve is intended to control flow so that the refrigerant leaves the evaporator coil at a predetermined superheat. Generally, the superheat of the refrigerant is a measure of the heat contained in the refrigerant vapor above its heat content at the boiling point (saturated vapor temperature) at the existing pressure. Maintaining the refrigerant entering the suction line from the evaporator coil at a desired superheat level enhances the refrigeration system performance.
Thermal expansion valves are typically used, in conjunction with a suction regulator, to maintain a consistent evaporator coil pressure. In known systems, conventionally designed mechanical pressure regulators are used for this purpose. Conventional mechanical pressure regulators include a throttling element that, when moved, limits the flow of the refrigerant through the suction regulator to regulate the pressure. A diaphragm, or other sensing element, responds to variations in the inlet pressure and moves the throttling element accordingly. A reference pressure, typically exerted by a spring, is applied to one side of the diaphragm to bias the diaphragm in a desired position, or set point. High side inlet pressure is applied to the other side of the diaphragm to move the diaphragm against the spring, and thus, move the throttling element.
In many refrigeration system implementations, finer temperature control is desirable. Adjusting the setting of conventionally designed mechanical pressure regulators in such thermal expansion valves can be a time consuming, manual process. Moreover, if the refrigerant or desired temperature changes, the complicated process of manually adjusting the pressure regulator's set screw must be repeated.


A fluid control or actuation system providing selective recruiting of actuators antagonistic to one another to provide variable output power, such as that used to drive a load. The actuators are intended to comprise different sizes, and to be operable with one or more pressure control valves capable of providing displacement of a non-recruited actuator without requiring active input to cause such displacement. Being able to selectively recruit different sized actuators to drive the load, and being able to displace non-recruited without active input, effectively incorporates a gearing function into the fluid control system.

Fluid control or servo systems, such as hydraulic or pneumatic systems, are well known and operate on the simple principle of transferring force from an applied location to an output location by means of a fluid. In hydraulic systems, the transfer is typically accomplished by means of an actuator cylinder having a piston contained therein pushing a substantially incompressible fluid through a fluid line to another cylinder, also having a piston, at a different location. One tremendous advantage to transferring force through a hydraulic system is that the fluid line connecting the two cylinders can be any length and shape, and can wind or bend as needed between the two pistons. The fluid line can also split into multiple other fluid lines thus allowing a master piston to drive multiple slave pistons. Another advantage of hydraulic systems is that it is very easy to increase or decrease the applied force at the output location through hydraulic multiplication, which is easily accomplished by changing the size of one piston relative to the other.
In most hydraulic systems, cylinders and pistons are connected through valves to a pump supplying high-pressure hydraulic fluid functioning as the substantially incompressible fluid. Spool valves are the most commonly used valves in hydraulic systems and can apply pressure to either the front or back faces of the piston inside the hydraulic actuators. When one side the actuator cylinder is pressurized, the spool valve simultaneously opens a return line to the opposite side of the actuator, allowing the substantially incompressible hydraulic fluid on the opposing side of the piston to bleed back into a return reservoir. This relieves any internal pressure that would oppose the movement of the actuator, and limits the work required by the actuator to only that which is needed to drive the external load. As a result, spool valves are ideally suited to hydraulic systems because they allow efficient control of the flow rate to achieve hydraulic force.
Still, in spite of the advantages of spool valves in hydraulic systems, existing spool valves have certain design limitations. Traditional spool valves have been designed to be actuated by either mechanical levers, electrical servos or internal control pressures called pilot pressures, which are provided by way of a pilot or control valve. Spool valves are commonly mounted in a cylindrical sleeve or valve housing with fluid ports extending through the housing, which can be opened or closed for fluid communication with each other by positioning the lands and recesses of the spool in appropriate locations within the sleeve. The working pressure is varied by displacing the valve spool to open or close the valve allowing varying amounts of pressurized fluid to flow from the supply reservoir.
In the case of electrical actuation, the valve is controlled by an electrical input current from an electrical source. The current may be related to the pressure in the system in that the greater the current supplied, the wider the pressure or supply port is opened allowing pressurized fluid to flow into and through the valve with less restriction. When the load pressure in the actuator finally equals the supply pressure then flow stops. In other words, a given current controls the size of the openings in the pressure or return ports, which in turn controls the flow rate of fluid into or away from the hydraulic actuator. In order for the system to operate correctly, there must a be constant pressure differential across the spool valve. Otherwise, as the load pressure approaches the supply reservoir pressure the valve loses linear response and its operation becomes unstable. Consequently, spool valves are typically operated in systems where the pressure of the source (i.e. the pressurized supply reservoir) is very high compared to the range of opposing load pressures, and the flow versus input current at a given pressure is linear in the usable region.
What this means is that the system, and particularly the load, is always in a pressurized state and cannot be freely moved by an external force or under its own weight. As such, the load cannot easily be moved without actual active input in the form of input pressurized fluid. In other words, the actuator cannot be passively back driven. This is true even for very small movements. Such a configuration is extremely inefficient, as active input in the form of pressurized fluid is required to displace or actuate a load, even in response to non-actuated forces, such as kinetic energy that may exist from the load under gravity or responding to momentum caused by one or more things, such as braking, impact by another object, etc. The use of pressurized fluid creates a significant energy loss as new pressurized fluid must always be supplied in order to facilitate movement within the fluid control system, such as movement and/or braking of the load.
In addition to the current flow problems of traditional spool valves, classical hydraulic systems are problematic for several other reasons. First, complex controllers are needed to control the cycle times of valves and pistons. Second, cycle times for moving pistons are often long because large amounts of fluid are required to move output pistons. Third, the large quantity of fluid needed to drive output pistons requires constant pressurization of large reservoirs of fluid accumulators. Consequently, hydraulic machines typically require large amounts of hydraulic fluid for operation and therefore require large external reservoirs to hold the difference in the volume of fluid displaced by the two sides of any cylinder.
Classical spool valve devices are also limited in application because when a controlled flow is induced through a valve it generally translates directly into a controlled velocity of the actuator's piston. Consequently, complex system feedback devices must be used to convert the hydraulic energy from velocity inputs into a system based on load position. Introducing feed back control devices into the system limits its response to the bandwidth of the feedback loop and the responsiveness of the valves such that the time delays between the feedback devices and the valves make the system unstable when a resistive force is applied.
Still other problems exist with classical servo valves operating in classical servo or fluid control systems. Due to the problems discussed above, these valves and systems are incapable of performing at high bandwidths without going unstable. In addition, significant amounts of energy may be lost due to leakage when not all of the valves in a multiple valve system are being used. Finally, the configuration of the spool can be limiting, with multiple lands and recesses formed in a single spool, and with the single spool functioning to open and close the pressure and return ports formed in the valve body.
As indicated, prior related fluid actuated or control systems, such as robotic and other hydraulic systems, typically require the use of active, pressurized fluid to actuate an actuator to drive or displace a load both actively, and in response to forces acting on the actuator, such as gravity, impacts and/or momentum. The use of active pressurized fluid to provide any movement of the actuators is recognized as a significant waste of energy and as being extremely inefficient. However, significant energy loss and reduced efficiency typically give way to design factors or criteria focused on increased power, which have been perceived as being more important, or at least more desirable. Therefore, the loss of energy and reduced efficiency, in many cases, has not been the foremost or principal design priority. In other words, large and expensive systems have been created for the specific purpose of providing large or high power output although these systems are extremely inefficient.
Another shortfall of prior related fluid control systems relates to the output power and subsequent movement of the load in relation to the needed amount of pressurized fluid to effectuate such movement. Typically, in order to generate high or large amounts of output power (often expressed in terms of linear force or torque) a large volume of pressurized fluid is needed. This is particularly the case when both high output power and high speeds are also desired. With such systems, large amounts of fluid are required to achieve the desired results, further contributing to the inefficiency of the system. This problem is encountered in some mechanical systems, such as those found in vehicles. However, various gearing systems have been designed and implemented to optimize the ratio of output power to speed, thus greatly improving the efficiency of the motors.

Fluid control system having selective recruitable actuators


A gear power transfer mechanism for driving a developing unit in an image forming apparatus wherein the developing unit is selectively located closely to and separated from a photoconductive drum unit in conjunction with opening and closing operations of a cover. This gear power transfer mechanism includes a first bevel gear provided on a rotation axis on a side of the photoconductive drum unit coupled with a drive motor, a second bevel gear always engaging with the first bevel gear, a third bevel gear provided on a rotating axis on a side of the developing unit, a fourth bevel gear always engaging with the third bevel gear and a rotation coupling device coupling the second bevel gear and fourth bevel gear. The rotation coupling device has a coupling structure which transfers rotation of the second bevel gear to the fourth bevel gear and allows movement of the fourth bevel gear relative to the second bevel gear when the developing unit is selectively located closely to and separated from the photoconductive drum unit.

1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus which causes a developing unit to come close to or to be separated from a photoconductive drum unit in conjugation with the opening or closing operation of an upper frame, and, more particularly, to a gear power transfer mechanism for transmitting a rotating force of a drive motor to a side of the developing unit from a side of the photoconductive drum unit when the developing unit is caused to come close to the photoconductive drum unit.
2. Description of the Related Art
Image forming apparatus, such as laser printer or electronic copying machine are now widely used and these machines always require simplified operation procedures and stabilized printing quality.
Such image forming apparatus are structured so that an upper frame can be opened away from or closed toward a lower frame forming a boundary at an paper transfer path to reset a paper jam and to replace a developing unit and a photoconductive drum unit. Moreover, with such an opening or closing operation, the photoconductive drum unit provided within the upper frame is caused to come close to or to be separated from the developing unit and the power in the photoconductive drum unit is transferred to the developing unit via a power transmitting mechanism when the developing unit and photoconductive drum unit are caused to move close with each other.
FIG. 10A and FIG. 10B are structural diagrams schematically showing a typical example (Japanese unexamined patent Publication HEI 1-92776) of the image forming apparatus explained above.
This image forming apparatus divides the frame into an upper and a lower frame. The lower frame (hereinafter called a base) 1 is provided with a paper cassette setting part 11, a paper transfer path 12, a fixing unit 13 and a pick roller and a transfer roller (not illustrated). Meanwhile, the upper frame (hereinafter called a cover) 2 is provided with a photoconductive drum unit 3, a developing unit 4 and a link mechanism 5 and is rotatable around a rotating axis 14 relative to the base 1. At the dividing section of the base 1 and cover 2, a paper transfer path is formed.
Therefore, as shown in FIG. 10B, the cover 2 can be opened away from the base 1 at the boundary of the paper transfer path by rotation around the rotating axis 14.
The photoconductive drum unit 3 is fixed to the cover 2 and the developing unit 4 is swayably fixed to the cover 2. A mag roller (not illustrated) within a developing unit 41 can be moved closely to or separated from the photoconductive drum 31 through such swaying operation.
The link mechanism 5 sways the developing unit 4 in accordance with the closing and opening operation of cover 2, namely causes the developing unit 41 to come close to or separate from the photoconductive drum 31. For this purpose, the link mechanism 5 is composed of an L type rotatable arm 51, an L type transmitting arm 52 and a rotatable arm 53. The L type rotatable arm 51 has a guide hole 512 which engages with an engaging pin 511 provided on a base 1 at the one end thereof and rotates around the center axis 513 in accordance with the closing and opening operation of cover 2. The L type transmitting arm 52 couples the other end of the L type rotatable arm 51 and the one end of rotatable arm 53 to realize integrated operation of these arms. The rotatable arm 53 rotates around a rotating axis 531 and is provided, at the one end thereof, with a pushing mechanism 54 consisting of a plate spring to push the developing unit 4 toward the photoconductive drum unit 3.
Here, operations of link mechanism 5 will be explained.
First, the cover 2 shown in FIG. 10A is closed toward the base 1. In this case, the L type rotatable arm 51 of the link mechanism 5 is rotated around the rotating axis 513 simultaneously with depression in the direction of arrow mark A, thereby the transmitting arm 52 is pulled in the direction of arrow mark B and the rotatable arm 53 is driven to rotate counterclockwise around the rotating axis 531. Simultaneously, the pushing mechanism 54 integrated with the rotatable arm 53 is moved to the right side, pushing the developing unit 4 toward the photoconductive drum unit 3. As a result, the developing unit 41 and the photoconductive drum 31 are set in a closed condition. Since the developing unit 41 is provided with a pair of gap rollers 42 which are in contact with both end portions of an external circumference of the photoconductive drum 31, the magnetic roller and a photosensitive drum in the developing unit 41 are provided opposed with each other with a constant interval between them under such closed condition.
Next, the cover 2 shown in FIG. 10B is opened. Under this opened condition, the transmitting arm 52 of the link mechanism 2 is moved in the direction of arrow mark C and thereby a pushing force of the pushing mechanism 54 toward the developing unit 4 is eased. As a result, the developing unit 4 is separated from the photoconductive drum unit 3 with a recovery force of a spring (not illustrated) and, consequently, the photoconductive drum 31 is separated from the gap rollers 42.
Therefore, a large gap is generated, under this opened condition, between the developing unit 41 and the photoconductive drum 31 and, thereby a paper jam can be reset and replacement of the developing unit 41 and photoconductive drum 31 can be realized easily. Moreover, a surface of the photoconductive drum 31 can be protected from damage during the operations explained above.
As explained above, the image forming apparatus causes the developing unit 4 to come close to or to be separated from the photoconductive drum unit 3 in accordance with the opening and closing operations of the cover 2 and is also provided with a gear power transfer mechanism for transmitting the rotating force of a drive motor to a rotating part of developing unit 4 from the photoconductive drum unit 3 under the closed condition of these units explained above.
This gear power transfer mechanism 6 is composed, as shown in FIGS. 11A, 11B and FIG. 12, of a drive gear unit 62 coupled with the drive motor (not illustrated) on the side of photoconductive drum unit 3 and a driven gear unit 63 coupled with the rotating part of developing unit 41 (magnetic roller, developer agitating screw, etc.). The drive gear unit 62 is provided with three gears rotatably provided on a fixed substrate 61, namely a first intermediate gear 621 engaged with the drive motor, a second intermediate gear 622 always engaged with the first intermediate gear and a drive gear 623 always engaged with the second intermediate gear. The axis of first intermediate gear 621 is coupled with the drive mechanism of the photoconductive drum 31 and the second intermediate gear 622 is coupled with the rotating axis of a paper transfer roller (not illustrated).
On the other hand, the driven gear unit 63 is composed of a movable bracket 634 (hatched area in FIG. 12) provided movably in the direction of arrow mark to the fixed substrate 61 and three gears are rotatably provided on movable bracket 634. These three gears include a driven gear 631 engaging with the drive gear 623 on the side of photoconductive drum 31 when the developing unit 4 comes close to the photoconductive drum unit 3, a third intermediate gear 632 always engaging with the driven gear, and a fourth intermediate gear 633 always engaging with the third intermediate gear. The fourth intermediate gear 633 is provided with four pawls coupled with a coupling pawl gear on the side of developing unit 41 as shown in the figure. When these pawls couple, the magnetic roller and the developer agitating screw in the developing unit 41 are rotated. The gears explained above, although not limited thereto, may be manufactured through molding of the synthetic resin material.
Here, operations of this gear power transfer mechanism 6 will be explained.
First, the cover 2 shown in FIG. 11A is closed toward the base 1 and the developing unit 4 is moved toward the photoconductive drum unit 3. In this case, the driven gear 631 of the gear power transfer mechanism 6 engages with the drive gear 623 because both units are in the closed condition. As a result, a rotating force of the drive motor transmitted to the drive gear 623 through the first intermediate gear 621 and second intermediate gear 622 is further transferred sequentially to the driven gear 631, third intermediate gear 632 and fourth intermediate gear 633 from such drive gear 623 to rotate the magnetic roller within the developing unit 41. Therefore, the photoconductive drum 31 and developing unit 41 are driven by the single drive motor.
Next, the cover 2 shown in FIG. 11B is opened and thereby the developing unit 4 is separated from the photoconductive drum unit 3. In this case, the driven gear 631 of the gear power transfer mechanism 6 is separated from the drive gear 623 releasing the engagement and thereby the rotating force of drive motor is not transferred to the developing unit 41. Accordingly, the magnetic roller in the developing unit 41 is no longer rotated.
Meanwhile, in the image forming apparatus of the prior art explained above, the gap between the photoconductive drum 31 and developing unit 41 changes depending on a little deviation of a supporting axis of the gap rollers 42 and a rotating axis of photoconductive drum 31 which define such gap. Such change of gap has a large influence on the engagement between the drive gear 623 of the drive gear unit 62 and the driven gear 631 of driven gear unit 63. Namely, since positional relation between the drive gear unit 62 and driven gear unit 63 is determined with reference to the axis center of the gap rollers 42 of developing unit 4 and rotating center of the photoconductive drum 31. Even if the center positions are little deviated, adequate engagement between the drive gear 623 and driven gear 631 can no longer be attained.
Accordingly, here arises a problem wherein creak is generated between gears, for example, when engagement between the drive gear 623 and driven gear 631 becomes deep, or gear missing and gear skipping are generated when engagement becomes shallow, due to relative eccentricity of the rotating axes on the side of photoconductive drum unit 3 (rotating axes of the photoconductive drum 31 and drive gear) 623 and the driven axis axis on the side of developing unit 4 (supporting axis of gap rollers 42 and rotating axis of driven gear 631).
From such conditions, high level technique and longer processing time have been required for adjustment of the gap in order to attain adequate engagement between the drive gear 633 and driven gear 631. Thereby, the prior art has a disadvantage in that provision of gear power transfer mechanism 6 at the time of manufacturing the image forming apparatus and replacement of developing unit 4 and photoconductive drum 31 after manufacture of apparatus have been made ineffective. Therefore, it has also been difficult to prepare the gear power transfer mechanism 6 as a unit for maintenance work.


Ultra-low leakage current backside-illuminated semiconductor photodiode arrays are fabricated using a method of formation of a transparent, conducting bias electrode layer that avoids high-temperature processing of the substrate after the wafer has been gettered. As a consequence, the component of the reverse-bias leakage current associated with strain, crystallographic defects or impurities introduced during elevated temperature processing subsequent to gettering can be kept extremely low. An optically transparent, conductive bias electrode layer, serving as both an optical window and an ohmic backside equipotential contact surface for the photodiodes, is fabricated by etching through the polysilicon gettering layer and a portion of the thickness of heavily-doped crystalline silicon layer formed within, and near the back of, the substrate during the gettering process.

A typical photodiode array includes a semiconductor substrate of a first conductivity type, having a front side formed with an array of doped regions of a second, opposite conductivity type, and an opposing back side that includes a heavily-doped bias electrode layer of the first conductivity type. For simplicity, the frontside doped regions are referred to below as gates, independent of their function as anodes or cathodes. Similarly, the abbreviation BEL is used to denote the backside bias electrode layer.
To provide a framework for the discussion below, an example of a photodiode array is used below in which the frontside doped gate regions have p-type conductivity, the substrate is n-type, and the backside bias electrode layer is, accordingly, a heavily-doped n-type layer. All statements and claims herein are equally true if the conductivity types of all the layers are reversed and the corresponding changes are made to the polarities of the charge carriers, applied voltages and electric fields.
Typically, the gate and bias electrode layers are formed internally to the crystalline semiconductor substrate. They are therefore native to and homostructural with the substrate. In most implementations, an external gate contact, formed from one or more non-native, heterostructural, conducting layers external to the substrate, is formed over a portion of each of the frontside gates. Similarly, one or more non-native, heterostructural, external back contacts may be formed over all, or a portion of, the backside bias electrode layer. In the case of silicon substrates, the gate contacts are usually formed from one or more metals, metal-silicon intermetallic compounds, or deposited, heavily-doped polysilicon, or a combination of a plurality of these materials. In the present context, polysilicon is considered to be both non-native and heterostructural to the crystalline silicon substrate. Similarly, silicon dioxide (SiO2), the amorphous "native oxide" of silicon, is both non-native and heterostructural to the substrate in this context. Back contacts to silicon photodiode arrays may use the same materials or one or more transparent conducting materials such as indium-tin oxide, which is an amorphous typically non-stoichiometric mixture of indium oxide and tin oxide. In many applications, an array of readout circuits is also formed on the front surface of the substrate.
A potential difference, referred to as a reverse bias, can be applied between the gate and the bias electrode layer to produce a depletion region within the substrate extending into the substrate from the p-n junction between the gate on the front side and the substrate. Hence, a photodiode is effected by the gate, the substrate and the BEL. External gate contacts or back contacts are ancillary elements provided to facilitate electrical connections to the photodiode array, not essential components thereof.
Such a photodiode array may be configured either in a frontside-illuminated mode to receive photons from the front side or in a backside-illuminated mode to receive photons from the backside. The frontside-illuminated mode, however, usually results in a lower external quantum efficiency (ratio of photocarriers collected to incident photons) than the backside-illuminated mode, because the conducting elements of the gate contacts and the readout circuits (if provided) reduce the active photosensitive area of the array on the front side. In comparison, the entire back side can be used to collect incoming radiation when properly configured. All other factors being equal, enhanced photosensitivity results in increased signal-to-noise ratio. In single-particle radiation detection applications using either direct (intrinsic) detection in the substrate or indirect detection (e.g., using scintillators as discussed below), enhanced photosensitivity results in improved particle energy resolution. In addition, conducting lines and other physical features such as steps in dielectric thickness on the front side can scatter light into the photosensitive areas of adjacent photodiodes, thereby reducing image contrast. Contrast degradation modifies the modulation transfer function of the array and can reduce the useful spatial resolution of the array. Therefore, backside illuminated photodiode arrays are frequently used in imaging applications to improve photosensitivity, signal-to-noise ratio, particle energy resolution and spatial resolution.
In a backside-illuminated photodiode, photocurrent is typically generated by band-to-band absorption. Photons with energy greater than the bandgap of the semiconductor substrate enter the back of the substrate and are absorbed, producing electron-hole pairs. If an electron-hole pair is generated outside the depletion region of a gate, the minority carrier (a hole in the example above) may diffuse to the edge of the depletion region beneath one of the gates. The electric field within the depletion region "collects" the hole by accelerating it towards the gate. If, however, a photon is absorbed within the depletion region of a gate, the electric field "collects" the hole as above, but accelerates the electron towards the undepleted substrate, or, if the substrate is fully depleted below a gate, towards the backside bias electrode layer. In either case, the photocurrent will flow through the photodiode and the external circuitry that maintains the bias between the gate and the bias electrode layer. If readout circuitry is provided on same semiconductor substrate, the circuit elements associated with each gate will produce a signal that represents a mathematical function of the photocurrent, the quantity of charge caused by the photon absorption, or a combination of both.
In low light-level imaging applications such as night photography, nuclear medical imaging, photon medical imaging, x-ray computed tomography and ballistic photon detection, it is critical for photodiode arrays simultaneously to exhibit high external photon conversion efficiency (defined as the ratio of photocarriers collected to photons incident on the back surface of the substrate) and extremely low reverse-bias leakage currents. For brevity, "quantum efficiency" is used below to denote external photon conversion efficiency, and "leakage current" is used to denote reverse-bias leakage current.
In low light-level imaging systems, the input optical signal often is in the form of short pulses, a few nanoseconds to a few microseconds in duration. For these applications, it is highly beneficial for the photodiodes to have short pulse response times, often referred to collectively as transition times or, singly, as rise and fall times, in the rough order of magnitude range of 10 to 100 ns or less. The signal processing system associated with the photodiode arrays typically "shapes" the output pulse by integrating the photocurrent generated within a time window of fixed duration in the same order of magnitude as the length of the photopulse.
Photodiode arrays with one or more long transition times produce output photocurrent pulses significantly longer than the input photopulse. These long photocurrent pulses produce smaller output pulses from the signal processing electronics than do those from faster photodiode arrays. Therefore, slow photodiode arrays may may result in low output signals from the signal processing electronics and therefore degrade the signal-to-noise ratio of the image. In applications with higher photon flux rates, e.g., x-ray computed tomography, the signal processing electronics may respond to the average photocurrent collected by a pixel over a time interval of fixed duration, longer than the duration of a single optical pulse. For these applications, longer transition times than those required for efficient single pulse detection may be acceptable.
To achieve high quantum efficiency, the bias electrode layer should be thin enough to be transparent to the incident radiation, yet sufficiently conductive to provide an equipotential surface on the back surface of the substrate adequate to maintain uniform depletion over the entire area beneath each gate.
The bias electrode layer should also have a low density of crystallographic defects and be free from deep-level impurities. If these criteria are met, the BEL will exhibit long enough minority-carrier lifetimes to minimize recombination of photocarriers generated within the BEL, thereby maximizing the efficiency of collection of photocarriers generated therein The BEL will therefore not be an optical "dead layer."
The pulse response times of the photodiodes can be minimized by using semiconductor substrates of high resistivity in the approximate range of 5 to 25 kΩ-cm, operated under reverse bias conditions sufficient to fully deplete the substrate under the gates. Under such full-depletion conditions, the electric field of the depletion region extends to the bias electrode layer on the back side.
Achieving ultra-low leakage current densities, e.g., below about 1 nA/cm2 at room temperature, of the individual photodiodes requires reduction of the contributions to the total leakage current by (1) the substrate; (2) the back contact structure (including the bias electrode layer and any additional layers formed thereon); (3) the front surface regions between the gate regions and between the outer gates and the surrounding regions; and (4) the edges of the substrate, formed when the substrate is "diced" to form individual photodiode array chips.
The bulk generation current of the substrate may be reduced by "gettering," an elevated-temperature process, typically performed at 1000° C. or higher for silicon substrates, in which strained, damaged or heavily-doped layers, singly or in combination, on the back surface of the substrate attract and capture impurities or crystallographic defects. Crystallographic defects may also be annihilated by recombination during the gettering process. The strained, damaged or heavily-doped "gettering layer" or layers is subsequently removed, thereby removing the absorbed impurities and defects. Once the substrate has been gettered, further high-temperature processes should be avoided, to prevent introduction of new impurities or generation of additional defects. All subsequent chemical processing and handling of the substrate should be scrupulously clean to avoid re-contamination.
Front surface generation currents in silicon photodiode arrays are usually minimized by using silicon dioxide (SiO2) layers thermally grown under conditions known to produce low-leakage surfaces. These oxides are typically grown prior to, or concurrently with, the gettering process. Low-temperature (below 400° C.) treatments may be performed after gettering to optimize surface leakage.
Minimizing leakage currents associated with the back contact structure requires dealing with a number of contradictory requirements. As discussed above, the bias electrode layer must be thin enough to be transparent. Such thin layers, however, are easily damaged, and damaged regions may generate leakage current very efficiently. Under fully depleted conditions, the bias electrode layer must be contain enough electrically active (i.e., charged as opposed to neutral) dopant atoms to allow it to terminate the electric field of the depletion region. The back surface of the crystalline semiconductor substrate, or the interface between the substrate and overlayers formed upon the back surface of the substrate to enhance the backside conductivity or to reduce reflection of incident photons, is a region where the crystal structure of the substrate is imperfectly terminated. Such regions may be capable of generating high leakage currents. If the electric field penetrates the BEL and reaches such an interface, it will efficiently collect the current generated there. Similarly, the electric field will collect leakage current generated by impurities or defects within the BEL. Undepleted regions in the BEL typically are highly-doped and will not be efficient leakage generators. Deep level impurities and defects in depleted regions of the BEL, on the other hand, may generate large leakage currents. If the BEL does not exhibit long minority carrier lifetimes, the BEL may therefore degrade the leakage current of the photodiodes.
Edge leakage currents are usually suppressed by providing guard structures surrounding the array of pixels. These structures collect the leakage currents generated at the diced edges before it reaches the pixels themselves.

Fabrication of low leakage-current backside illuminated photodiodes


A diagnostic method for assessing how a hypercholesterolemic person's serum cholesterol level will respond to a low total fat and saturated fat diet. The method involves defining a target cholesterol level, measuring a baseline level, feeding for a term of 3-25 days a NCEP Step I diet of which at least 50% of the caloric intake is provided by a fortified, low-fat nutritional product, and comparing the post term cholesterol level to the defined goal to see if the target is met. If the target is met, the person is predicted to respond to dietary intervention. If the target is not met, the person is deemed a non-responder and is considered for drug therapy. A fortified, low-fat nutritional product supplies in about 1000 kcal (i) 100% of the adult RDI for vitamins and minerals; and (ii) total fat, saturated fat and cholesterol levels that are at or below the levels specified for a Step II diet. Preferably the total fat comprises 25% or less of total calories; and the saturated fat and cholesterol maximum levels are less than about 2-3% of total calories in the case of saturated fat, and less than about 30-50 mg per 1000 kcal in the case of cholesterol.

Coronary Heart Disease (CHD) causes nearly 500,000 deaths per year and is the single leading cause of death in America today. Elevated serum cholesterol levels constitute a major modifiable risk factor for CHD, and the results of numerous large-scale clinical trials have convincingly demonstrated that lowering serum cholesterol reduces prevalence of fatal and non-fatal myocardial infarction as well as total mortality. The major ongoing public health effort to reduce coronary heart disease in the United States was sparked by the alarmingly high incidence of morbidity and mortality that resulted from this chronic disease. Because of this, there have been intensive efforts to develop new and more potent strategies to reduce risk factors for CHD. There are two major strategies for preventing CHD by lowering serum cholesterol. One is a patient based approach that seeks to identify individuals at high risk who will benefit from intensive intervention efforts. The goal of this approach is to detect, treat, and monitor high-risk individuals who have elevated serum cholesterol. The other strategy is the public health approach that attempts to lower serum cholesterol levels in the entire population by promoting changes in dietary habits and physical activity levels. These two strategies are complementary and both are incorporated in the National Cholesterol Education Program (NCEP) of the National Institutes of Health Second Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults updated recommendations for cholesterol management. This invention relates to the patient- based approach of identifying individuals at high risk for CHD.
Dietary intervention is the cornerstone of cholesterol lowering. Three major dietary factors contribute to high levels of serum cholesterol; these are a high intake of saturated fat, a high intake of dietary cholesterol, and an imbalance between calorie intake and energy expenditure leading to obesity. The NCEP has suggested the use of Step I and Step II Diet guidelines to assist the individual in modifying their diets. Step I and Step II Diets emphasize the choice of fruits, vegetables, grains, cereals, and legumes as well as poultry, fish, lean meats and low fat diary products instead of foods high in saturated fat and cholesterol, such as whole-milk dairy products and high-fat meats. The Step I and Step II Diets will be described later in the description. Thus, the primary aim of dietary intervention is to reduce CHD risk by decreasing intakes of saturated fat and cholesterol and by restoring appropriate calorie balance, while simultaneously promoting good nutrition.
Not all individuals are equally sensitive to dietary modification and some subjects will have high cholesterol levels that are inherently resistant to dietary modification. The mechanisms for this resistance are not completely understood. Because these individuals can not achieve the cholesterol-lowering goal despite good adherence to a Step I or Step II Diet, drug therapy may be the only effective treatment for their high serum cholesterol. For most subjects, at least 6 months of intensive dietary intervention and counseling should be carried out before considering drug therapy. Some subjects may even require 12 or more months of dietary intervention before considering drug treatment. This represents a delay in implementing an effective cholesterol-lowering regimen.
Thus, primary care physicians and their hypercholesterolemic patients lack a convenient, accurate, rapid and economic diagnostic method to determine how a person's serum cholesterol level will respond to the implementation of a cholesterol-lowering diet. A feature of the present invention is to provide such a diagnostic method.

Diagnostic method for assessing the serum cholesterol response to low diets


A power amplifier circuit (200) for amplifying a radio frequency (RF) signal received at an input (208) into an amplified RF signal at an output (210) includes a coupler circuit (222, 122), a second input (206), a power amplifier (218), and a level shifter (228). The coupler circuit (222, 122) is coupled to the output (210) to detect a level of the amplified RF signal. The second input (206) receives a control signal derived from the detected level. The power amplifier (218) includes a transistor (234/236) having a gate (238/240) coupled to the input (208) and a drain (242/244) coupled to the output (210). The level shifter (228) is coupled to the second input (206) and the gate (238/240) and, responsive to the control signal, supplies a biasing voltage (VGG) to the gate (238/240). The level shifter (228) includes circuitry (255) to minimize temperature sensitivity of the biasing voltage (VGG).

Power amplifiers are used in a communication device, such as a radiotelephone, for amplifying radio frequency (RF) signals for transmission. One type of radiotelephone operates in the GSM (Group Special Mobile) radiotelephone system. In the GSM system, up to 8 radiotelephones simultaneously share a single channel on which to broadcast. Each of the radiotelephones is limited to transmitting RF signals during an allocated time slot of approximately 577 .mu.s. The radiotelephone must quickly ramp up its power amplifier to the proper frequency, transmit the RF signals, and quickly ramp down the power amplifier within the 577 .mu.s window. As a result, the output power of the power amplifier must be controlled with great accuracy to meet system requirements and not interfere with the other radiotelephones sharing the same channel. This control may be accomplished by employing a closed loop feedback structure, such as that disclosed in U.S. Pat. No. 5,150,075 by Hietala et al., entitled "Power Amplifier Ramp Up Method and Apparatus", issued on Sep. 22, 1992, and assigned to Motorola, Inc.
One widely used power amplifier comprises depletion mode transistors, such as gallium arsenide (GaAs) MESFET (metal-semiconductor field effect transistor) devices. GaAs MESFETs are beneficial because they exhibit comparatively high electron mobility and provide good performance across a wide frequency range. Because the GaAs MESFET is a depletion mode transistor, it requires application of a negative bias voltage to its gate for active mode biasing. The negative bias voltage is typically supplied by a level shifter coupled to the gate of the GaAs MESFET. Because the gate threshold voltage of a GaAs MESFET varies with changes in temperature, the level shifter must be adjustable to accordingly vary the negative bias voltage so as to maintain accurate control of the output power of the power amplifier. One such level shifter is disclosed in U.S. Pat. No. 5,559,471 by Black et al., entitled "An Amplifier and Biasing Circuit Therefore", issued on Sep. 24, 1996, and assigned to Motorola, Inc. In addition to being adjustable, it would further be desirable to minimize the temperature sensitivity of the level shifter itself to achieve additional accuracy in output power control.
Thus, what is needed is a level shifter for use in a power amplifier circuit for a communication device employing a closed loop feedback system that is not sensitive to temperature variations.

Power amplifier circuit with temperature compensating level shifter


A holding unit and a vibration transmission system are disclosed. The holding unit comprising a holding plate is configured to be attached to the skin by means of magnetic attraction between a number of external magnets that are either:    a) integrated within the holding plate;    b) mechanically attached to the holding plate; or    c) constituting the holding plateand a number of internal magnets implanted under the skin of a hearing impaired person. The holding unit comprises a transmission member or plate member configured to transfer mechanical vibrations from a vibrator through the skin to the bone of the person. The transmission member or plate member is interconnected by a mechanical flexible coupling to the magnet(s) of the holding plate.

It is known to maintain pressure between the skin and the vibrator output element by means of magnets/magnetisable parts implanted subcutaneously and in the vibrator output part respectively. However, the constant pressurisation of the skin between the implanted parts and the vibrator may cause pressure wounds or irritation of the skin.
The prior art transcutaneous vibration transmission systems applies a relatively large plate with magnets facing the skin. This relatively large plate will act as a speaker membrane that will acoustically emit sound. This acoustical sound path has negative effects on feedback margins for the hearing aid system. This relatively large plate will have a relatively large mass that will create a mechanical impedance mismatch when transferring mechanical vibrations from the vibrator through the skin to the bone.
US 20130018218 A1 suggests several solutions to the problem (pressure wounds or irritation of the skin) of the constant pressurisation of the skin between the implanted parts and the vibrator: such as ameliorate the attraction power between external and internal parts by adjusting the distance between the skin surface and the external magnetic parts, or such as adding a soft cushioning layer between the magnetic parts and the skin or molding the parts abutting the skin by to follow the skin surface.
US 20130018218 A1 does not provide a solution to the problems caused by the transmission of the vibrations through the rather heavy magnets provided between the vibrator output and the skin surface.
Thus there is need for a transcutaneous vibration transmission system that reduces or even eliminates these drawbacks of the prior art.

Holding unit for a vibration transmitter and a vibration transmission system using it


A method for manufacturing small adaptive engines uses a battlefield repository having cloud services that is configured to enable additive manufacturing (AM) of engine parts and assemblies. The method also uses a compilation of recipes/signatures for building the engine parts and the assemblies using additive manufacturing (AM) processes and machine learning programs. An additive manufacturing system and an alloy powder suitable for performing the additive manufacturing (AM) processes can be provided. In addition, the engine parts can be built using the additive manufacturing (AM) system, the alloy powder, the battlefield repository and the compilation of recipes/signatures. A system for manufacturing small adaptive engines includes the battlefield repository, the compilation of recipes/signatures, a foundry system for providing the alloy powder and an additive manufacturing (AM) system configured to perform the additive manufacturing (AM) processes.

On-demand and low-cost, high-precision, adaptable manufacturing has been a driving need of many industries. Companies that do it well can create a greater depth of products offered at larger margins relative to competitive technology. Greater numbers of products and their capabilities can help provide 'capacitance' to sometimes aggressively switching markets. This in turn can create long-term survivability.
Similarly, in the defense business, direct access to high precision manufacturing at relatively low rates can increase the number of available fielded systems, which can positively affect the outcome of a conflict. Furthermore, adaptable manufacturing models allow engineers to innovate more quickly in both proactive and reactive ways. Likely greater than simply reducing cost to market (while retaining very high functionality) such a process would be another tool by which our defense community can more effectively respond to out-of-band threats.
This disclosure relates to a method and system for manufacturing small adaptive engines with low manufacturing costs that are not market-size dependent. In addition, the method and system replaces complicated and expensive machining processes with additive manufacturing (AM) processes to produce complex engine parts, such as turbine blades.

Method and system for manufacturing small adaptive engines


Disclosed is a method for aiding in the diagnosis of merosin deficiency-type congenital muscular dystrophy (CMD). The method is based on the discovery of a previously unidentified form of CMD which is characterized by a substantial reduction in the levels of merosin in skeletal muscle tissue containing normal levels of dystrophin and dystrophin-associated proteins.

Congenital muscular dystrophy (CMD), a very disabling muscle disease of early clinical onset, is the most frequent cause of severe neonatal hypotonia. Its manifestations are noticed at birth or in the first months of life and consist of muscle hypotonia, often associated with delayed motor milestones, severe and early contractures and joint deformities. Serum creatine kinase is raised, up to 30 times the normal values, in the early stage of the disease, and then rapidly decreases. The histological changes in the muscle biopsies consist of large variation in the size of muscle fibers, a few necrotic and regenerating fibers, marked increase in endomysial collagen tissue, and no specific ultrastructural features. The diagnosis of CMD has been based on the clinical picture and the morphological changes in the muscle biopsy, but it cannot be made with certainty, as other muscle disorders may present with similar clinico-pathological features.
Within the group of diseases classified as CMD, various forms have been individualized. The two more common forms are the occidental and the Japanese, the latter being associated with severe mental disturbances, and usually referred to as Fukuyama congenital muscular dystrophy (FCMD). The genetic lesion responsible for FCMD has recently been mapped to chromosome 9. It is unknown whether or not the rare cases of CMD associated with mental retardation or central nervous system abnormalities observed in occidental countries belong to the same disease entity. The determination of the gene (or genes) responsible for the various forms of CMD is required in order to clearly delineate specific members of the currently ill-defined genus.

Merosin deficiency-type congenital muscular dystrophy