A system and method for generating a multidimensional navigation solution utilizes Global Positioning System (GPS) data to obtain highly reliable and accurate navigational solutions in high interference and dynamic environments, at a performance level which has been heretofore unattainable. Additional sensors such as inertial (gyros and accelerometers), altimeters, radars, etc. may be employed in a deeply integrated configuration. The approach taken in the present invention differs from that of previous techniques through its exploitation of nonlinear filtering methods; as a result, the navigation system architecture and processes employed yield significant improvements in navigation system performance, both in code tracking and reacquisition, and in carrier tracking and reacquisition. The improvements are particularly significant at low signal/noise ratios, where conventional approaches are especially susceptible to loss of code lock or carrier lock.

Contemporary navigation systems commonly employ satellite navigation data derived from radio navigation receivers to determine the location of a navigation platform. The satellite data is often augmented by data from additional sensors in order to improve navigation system performance in situations where satellite data may be available only intermittently or may be degraded by intentional or unintentional interference. For example, data from inertial sensors (accelerometers and gyros) may be used to allow full navigation solutions (position, velocity and attitude) to be maintained in the presence of satellite data dropouts over extended periods of time. Radio navigation data is generated by receivers specifically designed to receive and process radio signals transmitted from a plurality of space-based or ground-based terminals. The navigation sensors are generally, but need not be, collocated on the same navigation platform. Depending on the application, the navigation system objective may be to determine position only, position and velocity, or a larger set of parameters which may include navigation platformn attitude. If required, the satellite navigation data can be used to perform error calibration of the other sensors, thereby reducing navigation system errors when the satellite data are temporarily unavailable or corrupted by interference.
Radio navigation data are processed in order to determine the line-of-sight distance of the navigation base from each transmitter in view of the receiver. This is accomplished by measuring the time of arrival of each signal, and comparing it to the known time of transmission, using a common time reference.
Contemporary radio navigation receivers used for this purpose generally include an antenna for receiving the radio signals, a front-end for amplifying, down-converting and bandpass-filtering the received signals, an analog-to-digital converter, and a signal processor. It is common practice in such receivers to generate in-phase (I) and quadrature (Q) baseband signals, which are then processed to remove noise and interference.
Noise and interference are often reduced significantly by means of spread spectrum techniques in which the transmitted signal is modulated by a known pseudo-random code. The receiver correlates the received signal with a locally-generated replica of the code and performs code tracking by varying the estimated time delay to maintain the correlation at or near its peak value. In this manner, a significant improvement in signal-to-noise ratio is obtained. If the input signal-to-noise ratio is sufficiently high, then it is possible to perform carrier phase tracking. Successful carrier tracking yields navigation accuracies which are greater than those achievable using code tracking only.
The NAVSTAR Global Positioning System (GPS), developed by the United States Government, is an example of a contemporary radio navigation system. A constellation of up to 24 satellites, positioned in precisely-known orbits, transmit pseudo-random ranging signals used by specially-designed receivers to calculate line-of-sight distance from the user receiver to any satellite in view of the receiver. Based on this information, a navigation solution can be obtained.
In modern GPS-based navigation systems, interference can have adverse effects on GPS receiver code and carrier tracking, resulting in degraded navigation system performance. Interference can be intentional or unintentional. Examples of unintentional interference include: (1) out-of-band signals from nearby transmitters with inadequate radio-frequency (rf) filtering, (2) harmonic or intermodulation products of various ground and airborne transmitters, (3) active or passive intermodulation products of signals or local oscillators on the same platform as the GPS receiver or on nearby platforms, (4) pulsed interference from radar signals in nearby frequency bands, (5) accidental interference from unlicensed transmitters. The results of interference are a reduction in signal-to-noise ratio (SNR) at the receiver input. The transmitted GPS signal may be further attenuated by trees, buildings, etc., resulting in a further reduction of SNR. Sources of intentional interference include narrowband and wideband jammers specifically designed to reduce SNR at the receiver input.
Current GPS satellites transmit on two frequencies, L1=1575.42 MHZ and L2=1227.6 MHZ. The satellites transmit their signals using spread spectrum techniques and employ two different spreading functions: (1) a 1.023 MHZ coarse/acquisition (C/A) code on L1 only and (2) a 10.23 MHZ precision P(Y) code on both L1 and L2. The minimum signal power for received GPS signals is specified as follows; for L1, C/A=xe2x88x92160 dBW (decibels with respect to one Watt), P=xe2x88x92163 dBW; for L2, P=xe2x88x92166 dBW. A typical value of equivalent received thermal noise power is xe2x88x92131 dBW. Thus, recovery of the GPS signal, even with no interference, cannot be accomplished without special design techniques such as spread spectrum.
As described above, the GPS signal is broadcast using standard spread spectrum techniques in which the narrow bandwidth signal is spread to a much larger bandwidth by using a pseudo-random code. By correlating the received signal with a known replica of the pseudo-random code and then bandpass filtering the result over the narrow signal bandwidth, the effects of interference are significantly reduced. The gain in SNR due to spread spectrum processing is on the order of 53 dB for P(Y)-code and 43 dB for C/A code in a 50 Hz bandwidth.
Outputs from other navigation sources, (for example inertial navigation system (INS) outputs, radars, altimeters, etc. . . . ) are often combined with GPS navigation system outputs to provide navigation solutions which are improved over those resulting from systems which employ either one used independently. These outputs assist in maintaining an accurate navigation solution over limited time intervals during periods of GPS dropout. The INS is also used to aid the GPS receiver in the presence of large platform accelerations, enabling narrow tracking filter bandwidths.
Current GPS-based navigation system architectures can be categorized generally as xe2x80x9cloosely coupledxe2x80x9d or xe2x80x9ctightly coupledxe2x80x9d. A loosely coupled system, for example, may combine the navigation solution generated by a GPS receiver (position, velocity, time) with the navigation solution provided by an INS navigation system (position, velocity, attitude) using a weighting scheme generally based on a Kalman filter. A minimum of four satellites are required to obtain the GPS navigation solution. A tightly-coupled system computes pseudorange and, deltarange (integral of Doppler velocity) measurements obtained by a GPS receiver, and for example, combines them with the INS navigation solution. A tightly-coupled system offers the advantage of obtaining a navigation solution with less than four satellites in view.
Vulnerability of current GPS receivers to interference has resulted in various designs for interference suppression which generally involve the use of patch antennas and/or specialized signal processors placed in front of the receiver input. Another approach uses aiding signals from inertial and/or other sensors to allow carrier/code tracking at narrow bandwidths in highly dynamic regimes such as aircraft. These methods may be regarded as ad hoc, since they only attempt to modify current systems at easily accessible points within the system. As a result, current systems are far from optimal in terms of interference rejection and navigation accuracy. There is a need for a fully integrated design which achieves near-optimal performance.
The present invention is directed to an apparatus and method for obtaining reliable and accurate GPS-based navigation solutions (optimal estimates of current position, time and/or other parameters such as velocity and attitude, as appropriate to the problem at hand) in high interference and dynamic environments, at a performance level which has heretofore been unobtainable.
The philosophy of the approach taken in the present invention differs from that of previous techniques; as a result, the navigation system architecture and processes employed yield significant improvements in navigation system performance, both in code tracking and reacquisition, and in carrier tracking and reacquisition. The improvements are particularly significant at low signal/noise ratios, where conventional approaches are especially susceptible to loss of code lock or carrier lock.
The present invention approaches the problem as a navigation problem, where the overall goal is to calculate an optimal, or xe2x80x9cbestxe2x80x9d, estimate of the components of a specified navigation state vector, given an initial estimate of the state vector and the past history of measurements. The measurements to be used are referred to herein as xe2x80x9crawxe2x80x9d measurements, consisting of a least in-phase (I) and quadrature (Q) data obtained from one or more correlators operating on received GPS signals. Additional navigation sensors may be used, depending on the application at hand, to enhance navigation system performance. These sensors include, but are not limited to, inertial sensors (gyros and accelerometers), altimeters, radars and electro-optical devices. By using the xe2x80x9crawxe2x80x9d measurements from all of the sensors, potential loss of information due to preprocessing operations is prevented.
In a preferred embodiment, the xe2x80x9cbestxe2x80x9d estimate is the minimum variance estimate, which is the conditional mean of the state vector, conditioned on the past measurement history.
The state vector estimate is updated based on the use of nonlinear stochastic differential equations for propagating the first two conditional moments of the state vector, given the past measurement history. Determination of the first conditional moment, otherwise referred to as the conditional mean, requires knowledge of the second conditional moment, which is represented by the estimation error covariance matrix. The conditional mean and error covariance matrix estimates are calculated recursively in real time in the navigation filter described herein.
The technique of the present invention is not dependent in any manner on a priori notions of tracking filters, phase lock loops, delay lock loops, and the like, which are commonly used. Instead, the navigation system architecture and processes flow naturally from the problem description and the characterization of the measurements from GPS and other sensors. This leads to an architecture which is amenable to single processor integration, eliminating the modular (and sub-optimal) architectures of current designs.
The resulting navigation filter processes are significant departures from traditional Kalman and extended Kalman filter algorithms generally used for GPS-based navigation. The differences arise principally from the fact that the measurement functions are highly nonlinear. Whereas previous designs rely on linearization techniques, the present invention takes full account of measurement nonlinearities. As a result, the error covariance matrix is driven by the measurements and the state vector gain matrix is a nonlinear function of the estimated error covariance matrix.
A bank of correlators and a processing architecture based on nonlinear estimation techniques are employed to maintain code track: through extremely high jamming environments. The number of correlators are optionally extendable, to allow for optimal code loop reacquisition following GPS signal dropout, eliminating the need for time-consuming reacquisition as employed by conventional direct-search techniques. The outputs of each correlator in the correlator bank are preferably weighted to provide a fully optimized navigation solution.
The present invention extends the range of delay error beyond the linear range through the use of multiple correlators. The number of correlators is arbitrary. The need for moding logic, which depends on estimated carrier/noise (C/N0) ratio is eliminated. Current receivers employ fixed gain filters, depending on the mode of operation. The present invention, however, allows for seamless operation at any C/N0 ratio, and therefore, mode switching logic is not required.
In a first embodiment, the present invention is directed to a system for determining a multidimensional navigation state for a navigation platform based on radio navigation data transmitted by external terminals. A radio navigation data receiver receives and amplifies the radio navigation data, which arrives embedded in noise. An extended-range bank of correlators extract the radio navigation data from the noise over an extended range of delay error. The correlators process the radio navigation data and noise to generate output functions indicative of the degree of correlation for each correlator in the extended-range bank between the radio navigation data and a known internally-generated replica signal. An estimator estimates the radio navigation data signal power and noise power from the correlator output functions. A measurement update unit updates the navigation state estimate based on the estimated radio navigation data signal and noise power estimates and the correlator outputs.
In a second embodiment, the present invention is directed to a system for determining a multidimensional navigation state for a navigation platform based on radio navigation data transmitted by external terminals and based on inertial data indicative of the inertial behavior of the platform. A radio navigation data receiver receives and amplifies the radio navigation data, which arrives embedded in noise. An extended-range bank of correlators extract the radio navigation data from the noise over an extended range of delay error. The correlators process the radio navigation data and noise to generate correlator output functions indicative of the degree of correlation for each correlator in the extended-range bank between the radio navigation data and a known internally-generated replica signal. An estimator estimates the radio navigation data signal power and noise power from the correlator output functions. An inertial sensor unit generates inertial data indicative of the inertial behavior of the platform. A measurement update unit updates the navigation state based on the estimated radio navigation data signal power and noise power, the correlator outputs, and the inertial data.
The radio navigation data preferably comprises Global Positioning System (GPS) data, and the radio navigation data receiver comprises a GPS receiver. The system preferably further includes a propagator for applying sensed inertial data to a dynamic model based on a recently updated navigation state to generate updated inertial data, which is in turn provided to the measurement update unit. The multidimensional navigation state may include, for example, information related to platform position, velocity, and attitude, receiver clock errors, inertial sensor errors, propagation delays, and satellite errors.
In a preferred embodiment, the measurement update unit updates the navigation state by calculating the conditional moments of the navigation state based on the estimated radio navigation data signal power and noise power, the correlator outputs, and the inertial data.
The conditional moments may comprise a first conditional moment comprising a conditional mean, and a second conditional moment comprising a conditional error covariance matrix. The conditional moments are preferably calculated to include measurement non-linearities.
The estimator preferably comprises a signal power estimator for determining radio navigation data signal power based on a nonlinear conditional moment of the navigation state, and a noise power estimator for estimating noise power based on a nonlinear conditional moment of the navigation state, and the signal power estimate.
In a third aspect, the present invention is directed to a system for determining a multidimensional navigation state for a navigation platform based on radio navigation data transmitted by external terminals. A radio navigation data receiver receives and amplifies the radio navigation data, which is embedded in noise. A bank of correlators extract the radio navigation data from the noise over a range of delay error. The correlators process the radio navigation data and the noise to generate correlator output functions indicative of degree of correlation for each correlator between the radio navigation data and a known internally-generated replica signal. An estimator estimates the radio navigation data signal power and noise power from the correlator output functions. A measurement update unit updates the navigation state based on the conditional moments of the navigation state calculated as a function of the estimated radio navigation data signal power and noise power, and the correlator output functions.
In a preferred embodiment, the third aspect of the present invention further comprises an inertial sensor unit for generating inertial data indicative of the inertial behavior of the platform. In this embodiment, the conditional moments of the navigation state are preferably further calculated as a function of the inertial data. The conditional moments preferably comprise a first conditional moment comprising a conditional mean, and a second conditional moment comprising a conditional error covariance matrix. The conditional moments are preferably calculated to include measurement nonlinearities. The bank of correlators preferably comprise an extended-range bank of correlators for extracting the radio navigation data from the noise over an extended range of delay error.
In a fourth aspect, the present invention is directed to an estimator for estimating signal and noise power in a system for determining a multidimensional navigation state for a navigation platform based on radio navigation data embedded in noise. The radio navigation data signal is received by a radio navigation data receiver including a bank of correlators for extracting the radio navigation data from the noise over a range of delay error. The correlators process the radio navigation data and the noise to generate correlator output functions indicative of the degree of correlation for each correlator between the radio navigation data and a known internally-generated replica signal. The estimator includes a signal power estimator for determining radio navigation data signal power based on a conditional moment of the navigation state, a noise power estimator for estimating noise power based on a conditional moment of the navigation state, and the signal power estimate.
In a preferred embodiment of the fourth aspect of the present invention, the estimator further includes a bias estimator for determining a bias estimate of each correlator in the bank. In this arrangement, the signal power estimate and noise power estimate are further based on the bias estimate. The bias estimator preferably comprises a smoothing function for updating the bias estimate of each correlator according to a smoothing time constant; and a minimum function for determining the bias estimate as the minimum value of the smoothed bias estimates.
The conditional moment preferably comprises a first conditional moment comprising a conditional mean, calculated by means of a nonlinear filter. The resulting noise power estimate preferably comprises a vector, such that an independent noise power estimate is calculated for each correlator in the correlator bank. The bank of correlators preferably comprises an extended-range bank of correlators for extracting the radio navigation data from the noise over an extended range of delay error. An inertial sensor unit is preferably included for generating inertial data indicative of the inertial behavior of the platform. The conditional moment of the navigation state is preferably further calculated as a function of the inertial data.
In a fifth aspect, the present invention is directed to a measurement update unit for updating the navigation state and error covariances of the navigation state for a navigation platform based on radio navigation data embedded in noise. The radio navigation data signal is received by a radio navigation data receiver including a bank of correlators for extracting the radio navigation data from the noise over a range of delay error. The correlators process the radio navigation data and the noise to generate correlator output functions indicative of degree of correlation for each correlator between the radio navigation data and a known internally-generated replica signal. A state update unit updates the navigation state as a function of the correlator output functions weighted by state gain functions. The state gain functions are based on conditional moments of nonlinear functions of the navigation state, and an inertial data propagation of a previous error covariance of the navigation state. An error covariance matrix update unit updates the error covariance of the navigation state based on conditional moments of nonlinear functions of the navigation state, and further based on estimates of the radio navigation data signal power and noise power.
In a preferred embodiment, the conditional moments comprise statistical expectations of nonlinear functions of the line-of-sight position error for each satellite in view.
According to the fifth aspect, the bank of correlators preferably comprises an extended-range bank of correlators for extracting the radio navigation data from the noise over an extended range of delay error. The radio navigation data signal power estimate and noise power estimate are preferably calculated by an estimator comprising a signal power estimator for determining radio navigation data signal power based on a conditional moment of the navigation state; and a noise power estimator for estimating noise power based on a conditional moment of the navigation state, and the signal power estimate.
In a sixth aspect, the present invention is directed to a measurement update unit for updating the navigation state and error covariances of the navigation state for a navigation platform based on radio navigation data carried on a radio navigation data carrier signal embedded in noise. The radio navigation data signal is received by a radio navigation data receiver including a bank of correlators for extracting the radio navigation data from the noise over a range of delay error. The correlators process the radio navigation data and the noise to generate correlator output functions indicative of degree of correlation for each correlator between the radio navigation data and a known replica signal. The bank of correlators include a prompt correlator for processing radio navigation data signals near the radio navigation data code offset. The measurement update unit comprises, a state update unit and an error covariance matrix update unit. The state update unit updates the navigation state as a function of the prompt correlator output function weighted by state gain functions. The state gain functions are based on conditional moments of a non-linear function of line-of-sight error of the radio navigation data, and an error covariance matrix. The error covariance matrix update unit updates the error covariances of the navigation state based on the state gain functions.
In a preferred embodiment of the sixth aspect of the present invention, the state gain functions are further based on estimates of the radio navigation data carrier signal power and noise power, a data bit estimate, an inertial data propagation of a previous navigation state, and an error covariance matrix. Noise power is preferably calculated based on the average noise power and at least two non-prompt correlator output functions. The state update unit and error covariance matrix update unit preferably operate linearly for a relatively large radio navigation data carrier signal power to noise power ratio and operate non-linearly for a relatively small radio navigation data carrier signal power to noise power ratio.
In a seventh aspect, the present invention is directed to a measurement update unit for updating the navigation state and error covariances of the navigation state for a navigation platform based on radio navigation data embedded in noise. The radio navigation data signal is received by a radio navigation data receiver including a bank of correlators for extracting the radio navigation data from the noise over a range of delay error. The correlators process the radio navigation data and the noise to generate correlator output functions indicative of degree of correlation for each correlator between the radio navigation data and a known replica signal. The measurement update unit comprises a state update unit, an error covariance matrix update unit, and an integrity management unit. The state update unit updates the navigation state as a function of the correlator output functions weighted by state gain functions. The state gain functions are based on conditional moments of a non-linear function of line-of-sight error of the radio navigation data, an internal data propagation of a previous navigation state, and an error covariance matrix. The error covariance matrix update unit updates the error covariances of the navigation state based on conditional moments of a non-linear function of line-of-sight error. The integrity management unit maintains the integrity of the navigation state and the error covariance.
In a preferred embodiment of the seventh aspect, the state gain functions and error covariances of the navigation state are further based on estimates of the radio navigation data signal power and noise power. The conditional moments preferably comprise non-linear functions of a line-of-sight error variance, in turn a function of the error covariance of the navigation state, and the integrity management unit preferably monitors and limits the signal and noise power values. The integrity management unit preferably further limits growth rate of the error covariances. Inertial data is preferably sensed by inertial data sensors and the growth rate of the error covariances are limited to an upper bound based on estimated accuracy of the inertial sensors. The integrity management unit may further monitor and maintain the positive-definiteness of the error covariance matrix, and may further limit estimated change of the navigation state.
The invention is amenable to a variety of commercial applications that rely on GPS navigation, including airliners, nautical vessels, personnel, and automobiles.

Deeply-integrated adaptive GPS-based navigator with extended-range code tracking

The Charles Stark Draper Laboratory, Inc.


MRI images are selectively resized or "zoomed" by zero padding the time domain data. Fourier Transformation of the time domain data after zero padding provides spatial domain data which when displayed provide an image that is resized relative to images provided from the time domain data without zero padding. A "zoom" or magnification factor can be selected and the quantity of padded zeros varied in response to the zoom factor to provide different zoom ratios. Restricting zoom factors to certain values permits the fast Fourier Transform to be used in Fourier Transformation.

It is often desirable to "zoom in" on or otherwise change the size of an MRI image (e.g., to provide more detailed views of structures of interest). Such "zooming" is not generally straight-forward or easy to accomplish, however, due to a correspondence between the number of time domain (raw data) samples within the time domain data set and the number of pixels defined by the spatial (image) domain data resulting from Fourier Transformation.
The fundamentals of the MRI experiment are well known. Briefly (and hopefully without undue oversimplification), in a typical MRI system an object 10 (see FIG. 1) to be imaged (e.g., a portion of the human body) is placed in an external static magnetic field gradient. Protons within the object tend to align their spins in accordance with the magnetic field direction. The object is excited by one or more RF excitation pulses of appropriate frequency, timings and durations (as one example, so-called "spin-echo" type pulse sequences may be used). The RF excitation pulses generated at the Larmour frequency cause the protons to precess their spins. When each RF pulse is switched off, the nucleii precess back toward their equilibrium position and in this relaxation process emit an NMR response that can be detected by an RF receiver.
In most imaging applications the NMR responses are spatially encoded by applying different magnetic field gradients during excitation, readout and in between. For example, two-dimensional spatial encoding may be provided using the so-called "spin warp" technique in which frequency information within the NMR responses store spatial information in one dimension (e.g., the x direction), and the phase component of the NMR responses store spatial information in the other dimension (e.g., the z direction). Using this technique, a readout gradient (e.g., Gx) is switched on during readout to frequency encode the spatial information in the one dimension (e.g., x); and another gradient (e.g., Gz) is switched on during the so-called "evolution" period (between the excitation period and the readout period) to phase encode the NMR pulses in the other dimension (e.g., z). The amplitude or duration of the phase encoding gradient is typically changed during a scan to provide different variations in phase angle for each NMR signal detected.
During the readout period, the NMR signal is typically sampled at regular time intervals .tau. to provide a time domain raw data set of Fourier coefficients S(t.sub.O, .tau.), S(t.sub.O, 2.tau.), S(t.sub.O, 3 .tau.) . . . S(t.sub.O, n.tau.)--the value of .tau. being chosen to conform to the sampling theorem (i.e., the sampling rate is at least twice the highest frequency component present in the signal). A sampling rate that is too low will generally result in a frequency interval that is too coarse--causing the object to fill only a small portion of the image field. Too high a sampling rate will result in aliasing the high frequency signals (thus folding them back into the low frequency part of the spectrum). The total number of sample points (Fourier coefficients) determines the spatial resolution after Fourier transformation (typically in two dimensions) and is usually chosen to be a power of 2 in order to take advantage of FFT (fast Fourier Transform) techniques. The resulting set of raw NMR time-domain data is generally symmetrical in both dimensions (e.g., x and z) and thus constitutes an N.times.N array of time-domain values.
The time domain data set may be further manipulated in a well known manner for a variety of reasons (e.g., to correct for instrumentation error, to improve signal-to-noise ratio, etc.)
The term "reconstruction" describes the process by which the acquired time-domain data set is converted into an image of the object. A two-dimensional Fourier transform (FT) is applied to the time-domain data set as described above to extract the frequency and phase information (and thus the spatial encoding) to develop spatial domain data (see FIG. 1). This spatial domain data may then be further processed using conventional techniques to provide an image on an electronic display and/or stored in a data file for later retrieval and imaging.
The sampling interval .tau. used during image acquisition generally establishes spatial resolution (i.e., the number of pixels) of the spatial domain data set--since sampling interval determines the spatial distribution corresponding to the Fourier coefficients and thus establishes the coordinate points of a "grid" of slice-volumes defined within the object space. Thus, in general it has been necessary to gather a 256.times.256 raw data array in order to provide a reconstructed image comprising 256.times.256 pixels. It was known in the past, however, to alter in a limited manner this essentially one-to-one correspondence between number of acquired time-domain samples and the number of values in the spatial domain.
For example, it is known to add zero values to the raw data set (a technique called "zero filling") in one or more dimensions to take advantage of the resulting improvement in image "resolution" (i.e., to increase the total number of pixels per line in images) without a concomitant increase in acquisition time. This technique involves adding zero "high frequency" components (i.e , zero values around the "outside" of the time domain data set array). This zero filling technique was also used to reduce acquisition time by increasing the signal-to-noise ratio of "high frequency" image components without degrading image "resolution" or computation time. See Batholdi et al, 11 Journal of Magnetic Resonance 9 (1973).
Many in the past have sought to provide "zooming" capability for MRI. The following is a non-exhaustive listing of prior issued U.S. Patents relating to advantages of and techniques for MRI image "zooming":
U.S. Pat. No. 4,703,271 to Loeffler et al; PA1 U.S. Pat. No. 4,644,280 to Paltiel; and PA1 U.S. Pat. No. 4,593,247 to Glover.
Many prior art zooming techniques provided altered RF pulse sequences and/or other acquisition parameters. For example, the Glover patent discloses a technique in which NMR signals are band-limited prior to conversion by the A/D converter so as to band limit the NMR signal in the X and Y axis directions. "Zooming" in on off center regions is accomplished by shifting the receiver frequency. The technique disclosed in the Paltiel patent avoids aliasing artifacts to allow image zooming by using a pseudo spin echo sequence.
The technique of "interpolation" may also be used to accomplish "zooming." Interpolation permits values of the image at coordinate points different from those imposed by the sampling interval to be ascertained. Such image interpolation techniques are extremely useful in allowing greater flexibility in changing image appearance without requiring new data to be acquired. Interpolation may be used in conjunction with resampling to "zoom" in on an image (i.e., to provide an image in which there is more than one pixel for each time-slice imposed by the sampling interval). Unfortunately, interpolation techniques may sometimes add artifacts to the "zoomed in" image.
Interpolating an image generally involves fitting a continuous function to the discrete points in the digital image so that values are defined at coordinate points other than those predetermined by the sampling interval. The continuous function may then be resampled at arbitrary points of interest. Interpolation and sampling can be combined so that the signal is interpolated only at those points which will be sampled during the resampling process.
But interpolation and resampling can sometimes introduce troublesome artifacts that cause the zoomed image to lose clarity. For example, the assignee of the subject application has in the past provided zooming capability through a technique of linear interpolation of spatial domain (image) data followed by resampling the interpolated data so as to provide more pixel values than were provided by the sampling interval used during data acquisition. While this technique can provide a "zoomed in" image (i.e., an image that is enlarged in size with respect to the original image provided without interpolation), the interpolation/resampling process can introduce image artifacts (see FIG. 7A for example). Much work has been done in the past toward finding better interpolating functions to use in MRI. Parker et al in "Comparison of MI-2, No. 2, IEEE Transactions on Medical Imaging (March 1983) survey a variety of different interpolating functions and discuss the advantages and disadvantages of each. See also Maeland, "On the Comparison of Interpolation Methods", Vol. 7, No. 3 IEEE Transactions on Medical Imaging (Sept. 1988). While better interpolation techniques might possibly be used to reduce such artifacts, such better interpolation techniques may also introduce computational complexity requiring additional processing resources and/or longer processing time. More computationally-efficient yet flexible techniques for resizing MRI images would therefore be highly advantageous.
A different approach to interpolation is described in a commonly assigned now allowed patent application Ser. No. 07/293,859 of Kaufman et al filed 5 Jan. 1989 entitled "3D Image Reconstruction Method for Placing 3D Structure Within Common Oblique or Contoured Slice-Volume Without Loss of Volume Resolution". That commonly-assigned patent application discloses a Fourier Transformation image reconstruction interpolation technique in which the boundaries of a slice-volume can effectively be shaped in three dimensions. The Kaufman et al technique involves applying the Fourier Shift theorem to time-domain data during Fourier Transformation to result in pixel shifts in the spatial domain.
The present invention is directed to a further improvement in Fourier Transformation MRI image reconstruction techniques, and more specifically, provides an interpolation technique which changes the size of the MRI image that can be produced from a given time domain data set without suffering from the disadvantages which arise from interpolating and resampling spatial domain data.
In accordance with one aspect of this invention, a two-dimensional array of MRI "raw data" time domain data set (e.g., digitized NMR signals acquired by an analog-to-digital converter) is conceptually defined within a larger two-dimensional array in which all points within the larger array not defined by the time domain data set are set to a zero value (i.e., higher frequency components than those acquired by the sampling are defined and set to zero). The size of the larger array is selected to provide a desired "zoom factor." The larger array (including the "zero padded" values) are then processed using Fourier transformation techniques (e.g., Fourier transformation in two dimensions) to produce spatial domain data. The resulting spatial domain data defines an image which is resized with respect to an image produced if the original time domain data set had been processed in the normal manner using Fourier Transformation.
In accordance with one feature of the present invention, the "raw data" time domain data set generated during acquisition is Fourier Transformed without "zero padding" to produce spatial domain data. The spatial domain data may be displayed to provide an "original" image. The spatial domain data is stored, and the "raw data" time domain data set is discarded. If a magnified ("zoomed", "enlarged" or "blown up") view of a structure of interest within the "original" image is desired, the operator selects a zoom factor and initiates a zooming function. Spatial domain data is subjected to inverse Fourier Transformation (e.g., in two dimensions) to regenerate a time domain data set. The regenerated time domain data set is then "zero padded" and Fourier transformed (e.g., Fourier transformed in two dimensions with the limits of the Fourier Transformation being set to be larger than the actual extents of the time domain data set by an amount determined in response to the operator-selected "zoom factor") to provide new spatial domain data. The new spatial domain data resulting from the Fourier Transformation may then be displayed to provide an "enlarged" view--with the amount of magnification as compared with the "original" image depending upon the selected limits for the Fourier Transformation.
In accordance with another embodiment of the present invention, the original time domain data set provided by the analog-to-digital converter is not discarded after Fourier Transformation (as is the normal practice) but is instead stored for later use if magnification is required. If desired, the time domain data set may be processed using Fourier Transformation in the conventional manner for display; and the resulting spatial domain data and the time domain data set may both be stored. If display of the conventionally sized image is desired at a later time, that display may be generated from the spatial domain data. If, on the other hand the operator wishes to display a resized image, the zero padding/Fourier Transformation technique described above is applied to the stored time domain data set to produce a resized image.
A further aspect of the present invention involves selecting a zoom factor value (e.g., by an operator on an interactive basis) and calculating a size for the zero-padded time domain data array based on the selected zoom factor. The zoom factor value and resulting corresponding zero padded time domain array size may thus be varied at will (e.g., on an interactive basis) to provide different sized images.
A further aspect of the present invention relates to restricting zoom factor values so as to minimize computation time. In accordance with this further feature of the present invention, only certain zoom factors are preferably used so as to permit use of the fast Fourier Transform (FFT). Assume that the size of the larger "zero padded" array is M.times.M where M is an integer. If M=2.sup.n (i.e., M is a power of 2), it is possible to use FFT to process the zero padded time domain data set. However, being restricted to M being a power of 2 may be somewhat inflexible for some applications since it limits the number of different zoom factors that may be used. In accordance with a further aspect of this invention, certain additional integer values for M may also permit use of FFT. For example, M may be in the form of M=2 .sup.p 3.sup.q ; M=2.sup.p 5.sup.q ; or M=2.sup.p 3.sup.q 5.sup.r where p, q (and r) are each integers. Each of these forms for M also permits use of FFT for fourier transformation of the zero padded time domain data set--thus providing additional flexibility in selecting zoom factors while nevertheless also providing the increase in computational efficiency offered by FFT.

Resizing MRI images using fourier transformation

The Regents of the University of California


Dispersion compensation for an optical signal having a first frequency range is described. The optical signal is applied to a dispersion compensating material having a negatively refracting behavior within the first frequency range. The dispersion compensating material is tuned by application of a control signal that varies at least one characteristic of the dispersion compensating material associated with the negatively refracting behavior.

Fiber optic communication involves modulating optical signals at high bit rates and transmitting the modulated optical signals over optical fibers. For example, in a wavelength division multiplexed (WDM) fiber optic communications system, optical carrier signals at a sequence of distinct wavelengths are separately modulated by information channels and then multiplexed onto a single optical fiber. Efforts continue toward increasing the data capacity of fiber optic communications systems, as well toward increasing the practical transmission distance of fiber optic spans. Although the development of erbium-doped fiber amplifiers (EDFAs) has substantially eliminated optical fiber attenuation as an obstacle to achieving longer transmission distances, other adverse effects suffered by optical fibers continue to serve as limitations on achievable bandwidths and/or distances.
Chromatic dispersion, termed dispersion herein, is one effect that limits the performance of an optical fiber span. Dispersion refers to a loss of signal shape as different component wavelengths travel down the optical fiber at different speeds. In practice, dispersion effects limit the rate at which a light beam at a given wavelength may be modulated with information (thereby limiting system throughput), and limit the allowable spacing between regenerators in a fiber optic communications link (thereby increasing system cost). For one widely used type of single mode fiber, the dispersion is about 17 ps/nm/km at a typical WDM wavelength near 1500 nm, wherein light at a wavelength of 1500 nm travels down the fiber 17 ps/km faster than light at a wavelength of 1501 nm, and travels down the fiber 17 ps/km slower than light at a wavelength of 1499 nm. Because the dispersion value for an optical fiber is usually dependent on signal wavelength, the dispersion characteristic for any particular type of optical fiber is often expressed as a plot of dispersion versus wavelength.
Dispersion compensating fibers (DCFs) are often used to compensate for the dispersive effects of optical fibers. Because of a core diameter much smaller than that of an ordinary optical fiber, the dispersion characteristic of a typical DCF is highly negative. When placed after (or before) the optical fiber span, the highly negative dispersion of the DCF compensates (or pre-compensates) for the positive dispersion of the optical fiber, thereby restoring the signal shape. Issues that arise for many DCFs include limitations on the amount of dispersion compensation per unit length, the high attenuation caused by the narrow core, and tunability limitations.
Chirped fiber Bragg gratings (chirped FBGs) can also be used for dispersion compensation. Chirped FBGs comprise segments of optical fiber into which lengthwise periodic variations of refractive index are "written" or burned, the periodic variations being chirped between longer periods at a first end and shorter periods at the opposite end. In operation, the chirped FBG receives the optical signal at the first end, and then reflects the wavelengths of interest back out that same first end, the shorter wavelengths being delayed relative to the longer wavelengths, thereby achieving a highly negative dispersion to compensate for the positive dispersion of the fiber span. Issues that arise for many chirped FBGs include the lengths of FBG fiber needed to provide dispersion compensation over a sufficiently wide spectral bandwidth, difficulty of fabrication, sensitivity to thermal variations, tunability limitations, and group delay ripple that can be a source of system noise.
It would be desirable to provide dispersion compensation in a manner that avoids, addresses, or improves upon one of more of the above-described issues associated with DCFs and chirped FBGs. Other issues arise as would be apparent to one skilled in the art upon reading the present disclosure.

Hewlett-Packard Development Company, L.P.


A pair of upper and lower radius rods are connected at their rear ends to upper and lower portions of a swingable link system which includes a knuckle and upper and lower control arms, and have their front ends interconnected and pivotally connected to a vehicle body through an elastic support member for vertical swinging movement, and an included angle between two straight lines connecting the pivoted point and respective rear end of the radius rods is set to be an acute angle. This enables application of a force to the elastic support member between the radius rods and the vehicle body to be distinguished from (a) when a braking force has been applied to the wheel and (b) when the longitudinal load has been applied to a central portion of the wheel. Thus, it is possible to provide a larger longitudinal compliance while insuring a caster rigidity of the suspension system, thereby satisfying both (a) a straight advancing property during braking and (b) a shock absorbing property during travelling on a bad road surface. Moreover, it is possible to improve the riding comfort during braking.

1. Field Of The Invention
The field of the present invention is suspension systems for automobiles, and particularly, an improvement in the suspension system for automobiles comprising a pair of upper and lower control arms which are linked to a knuckle carrying a wheel and are pivotally connected at their base ends to a vehicle body for vertical swinging movement.
2. Description Of The Prior Art
A double wishbone type suspension system is widely known (for example, see Japanese Patent publication No. 28123/69).
In such a prior art suspension system, the base ends of the upper and lower control arms are pivotally connected to a horizontal shaft fixedly mounted on a vehicle body through elastic support members, respectively and hence, a longitudinal compliance and a caster rigidity during braking are governed by the spring constant of the elastic members.
In general, in order to prevent, a shock, produced when a wheel goes over a protrusion on a road surface, from being transmitted to the vehicle body. It is necessary to increase the longitudinal compliance of the suspension system. In addition, in order to insure a straight advancing property of the wheel, it is necessary to increase the caster rigidity of the suspension system.
In the above prior art suspension system, however, if the spring constant of the elastic member is set smaller to provide a larger longitudinal compliance, the caster rigidity is reduced to degrade the straight advancing property of the wheel. On the other hand, if the spring constant of the elastic member is set larger to provide a larger caster rigidity during braking, the longitudinal compliance is reduced, accompanied by an adverse deterioration of the riding comfort. Therefore, it is difficult to satisfy both of the longitudinal compliance and the caster rigidity during braking.
Even if a non-linear spring characteristic is provided to the elastic support members, it is impossible to insure longitudinal compliance during braking.


A first detector detects a value of a current or voltage generated by an auxiliary coil. A second detector detects a value of a current flowing through a power transmitting coil. A coupling coefficient estimator estimates a first coupling coefficient between the power transmitting coil and a power receiving coil, based on the value of the current or voltage generated by the auxiliary coil, and estimates a second coupling coefficient between the power transmitting coil and the power receiving coil, based on the value of the current flowing through the power transmitting coil. A control circuit controls a power supply circuit to stop power transmission to a power receiver apparatus when a difference between the coupling coefficients is greater than a threshold.

Contactless power transmission systems are known, which transmit power from a power transmitter apparatus to a power receiver apparatus in a contactless manner, an which is capable of detecting a foreign object located between the power transmitter apparatus and the power receiver apparatus (for example, see Patent Document 1).
According to Patent Document 1, a power receiver apparatus (electronic apparatus) calculates a ratio of magnitude of a current actually received by the power receiver apparatus, to a current value notified from a power transmitter apparatus (charger), and requests the power transmitter apparatus to stop power transmission when the ratio is less than a predetermined value.

This patent is subject to a terminal disclaimer.

Contactless power transmission system for transmitting power from power transmitter apparatus to power receiver apparatus, and detecting foreign object


A contact type image sensor has a driving circuit part which sequentially drives a plurality of photoelectric conversion elements of a photodetector in blocks which respectively have an arbitrary number of photoelectric conversion elements. The driving circuit part has a pair of shift registers, one for sequentially selecting the block and the other for sequentially selecting each of the photoelectric conversion elements within the selected block.

The present invention generally relates to contact type image sensors, and more particularly to a contact type image sensor for use in a document scanner and the like.
In a document scanner, the overall size of the document scanner inevitably becomes large when an image sensor requires an optical reduction system. Hence, there are document scanners which use a contact type image sensor having a size in correspondence with a maximum document size which is to be read. In other words, the contact type image sensor extends for a length corresponding to a maximum width or length of the document which is to be read, and there is no need to use an optical reduction system.
FIG. 1 shows a circuit construction of an example of a conventional contact type image sensor. A contact type image sensor 10 has a photodetector 2 made up of a plurality of photoelectric conversion elements 1, an analog switch part 3 made up of a plurality of switches, a buffer part 4 made up of a plurality of buffers, a driving circuit 5 and a signal processing circuit 9. First terminals of the photoelectric conversion elements 1 are connected to the corresponding switches of the analog switch part 3.
Each photoelectric conversion element 1 is shown as having a photodiode structure with a photodiode PD and a sensor capacitance CD connected in parallel. A switch of the switch part 3 and a buffer of the buffer part 4 are provided in correspondence with each photoelectric conversion element 1. The driving circuit 5 is constituted by a shift register and sequentially operates the switches of the analog switch part 3 responsive to clock signals .phi..sub.CLK and .phi..sub.CLK and a start pulse signal SP so as to selectively drive the photoelectric conversion elements 1. Each bit of the photodetector 2, that is, each photoelectric conversion element 1 corresponds to one bit of the shift register (5). Similarly, each switch of the analog switch part 3 corresponds to one bit of the shift register (5). MP denotes a power source voltage for the photodetector 2.
The signal processing circuit 9 is connected in common to second terminals of the photoelectric conversion elements 1. The signal processing circuit 9 has a current-to-voltage (C/V) converting circuit 6, a peak holding circuit 7 and an analog-to-digital (A/D) converter 8. For example, the C/V converting circuit 6 has operational amplifiers coupled in two stages. An output signal of the C/V converting circuit 6 is passed through the peak holding circuit 7 and the A/D converter 8, and an output digital data is obtained from the A/D converter 8. For example, the A/D converter 8 has an integrating circuit.
When reading a document image, all of the bits of the photodetector 2 are set to a high level and all of the sensor capacitances CD are charged. A light is irradiated on each bit of the photodetector 2 depending on black and white portions of the document image, and the sensor capacitances CD of those photoelectric conversion elements 1 which receive the light discharge. The driving circuit 5 sequentially turns ON the switches of the analog switch part 3 and a resulting current which flows through the photodiode PD is converted into a voltage in the C/V converting circuit 6. The peak holding circuit 7 reads a voltage dependent on the intensity of the light by holding the peak value of the output voltage of the C/V converting circuit 6. The A/D converter 8 converts the read voltage from the peak holding circuit 7 into a digital data describing gradation levels of the document image.
When the start pulse signal SP is applied to the driving circuit (shift register) 5, an output signal SO of the signal processing circuit 9 shown in FIG. 2(L) is sequentially obtained in synchronism with the clock signals .phi..sub.CLK and .phi..sub.CLK shown in FIGS. 2(A) and 2(B) because bit numbers "1" through "5" and "1725" through "1728" shown in FIGS. 2(C) through 2(K) are respectively outputted from the driving circuit 5. FIGS. 3(A) and 3(B) respectively show an output signal CVO of the C/V converting circuit 6 and an output signal PHO of the peak holding circuit 7. In other words, a voltage in correspondence with the intensity of the light is read by the peak holding circuit 7, and the output signal PHO of the peak holding circuit 7 is converted into the digital data (sensor output) SO describing the gradation levels of the document image.
FIG. 4 shows a perspective view of the conventional contact type image sensor 10. The photoelectric conversion elements 1 are arranged in a line on a transparent dielectric substrate 11 such as a silicon substrate so as to constitute the photodetector 2. The analog switch part 3, the buffer part 4 and the driving circuit 5 are formed on the substrate 11 to constitute a driving circuit part 12.
Each of the photoelectric conversion elements 1 have a sandwich structure shown in FIG. 5. A protection layer 13, an insulator layer 14 and a metal electrode layer 15 are successively formed on the substrate 11, and a semiconductor layer 16, a protection layer 17 and a transparent electrode layer 18 are further provided as shown. For example, the semiconductor layer 16 is made of amorphous Si including H or amorphous Si including OH.
On the other hand, the driving circuit part 12 has a metal oxide semiconductor (MOS) inverter structure using polysilicon for an activation layer (planar thin film transistor structure) as shown in FIGS. 6A and 6B, where FIG. 6A shows a plan view and FIG. 6B shows a cross sectional view of the driving circuit part 12. An activation layer 20 is patterned on the substrate 11, and a p.sup.+ -type diffusion layer 21 is formed on both sides of the activation layer 20. A gate oxide layer 22 is formed on the activation layer 20, and a gate electrode 23 is formed on the gate oxide layer 22. An insulator layer 24 covers the exposed gate oxide layer 22 and the like on the substrate 11. A contact hole 25 is formed in a portion of the insulator layer 24, and a metal electrode 26 is formed on the insulator layer 24 to electrically connect to the p.sup.+ -type diffusion layer 21 through the contact hole 25. Hence, the analog switch part 3 has a p-type MOS structure. The driving circuit 5 has an n-type MOS structure and is located adjacent to the analog switch part 3. The driving circuit 5 basically uses the same structure as the analog switch part 3 except that a portion corresponding to the p.sup.+ -type diffusion layer 21 is an n.sup.+ -type diffusion layer 27 in the driving circuit 5. The surface of the driving circuit part 12 is covered by a protection layer (not shown).
Therefore, the driving circuit 5 and the like of the contact type image sensor 10 are integrally formed on the transparent substrate 11 by use of thin film transistors or the like. However, in order to drive one photoelectric conversion element 1, that is, with respect to one bit of the photodetector 2, it is necessary to provide twenty or more thin film transistors. As a result, in the case of the contact type image sensor designed to read a document of A4 size, for example, it is necessary to provide a large number of photoelectric conversion elements 1 amounting to 1728 bits (=8 bits/mm.times.216 mm), and 34560 (=1728 bits.times.20) or more transistors are required to drive such a large number of photoelectric conversion elements 1.
But it is extremely difficult to form such a large number of transistors on the substrate 11 in a satisfactory state because it is difficult to form a perfectly uniform thin film on such a large area of the substrate 11 that is sufficient to provide the large number of transistors. For this reason, there is a problem in that the yield of the conventional contact type image sensor is poor. In addition, even when a single transistor of the driving circuit 5 fails, there is a problem in that the driving circuit 5 thereafter carries out an erroneous operation or the driving circuit 5 does not operate at all.

Rocoh Research Institute of General Electronics


A drinking vessel includes a timer coupled to a sidewall of the vessel and having an actuator protruding from the vessel which controls the timer.

The present invention relates to drinking vessels and particularly to single-serving sized vessels, such as mugs, glasses, etc.
Conventional drinking vessels serve as receptacles for beverages. A typical drinking vessel is sized to hold an individual-sized quantity of a beverage. A conventional drinking vessel holds a beverage, but gives no information to the individual drinking the beverage as to his or her rate of consumption. A drinking vessel which automatically monitors the rate at which an individual consumes a beverage would be welcomed by consumers of beverages.
According to the present invention, a drinking vessel includes a stopwatch or timer having an actuator, which controls the functionality of the stopwatch.
In preferred embodiments, a drinking vessel includes a stopwatch or timer and a resting surface. The drinking vessel includes an actuator pin coupled to the stopwatch and protruding from the resting surface. The actuator is movable and starts and stops the stopwatch.
In preferred embodiments, the drinking vessel comprises a mug having a sidewall. The stopwatch includes a visual display coupled to the sidewall of the mug. Additionally, the stopwatch includes a programming panel coupled to the resting surface of the mug, which controls the functionality of the stopwatch (e.g., how the actuator pin starts, stops, resets, etc., the stopwatch).


A mesh network of interconnected wireless nodes in which each node independently manages a wireless connection to one or more other wireless nodes for transporting data, and stochastically refreshes and maintains internode connections in the wireless mesh network. A network overlay orchestrator in each node periodically validates the connections to other nodes in the mesh network based on a current topology of connected nodes to ensure the efficiency of current connections. Connection logic replaces, if a connection validation fails, the failed connection with a newly established connection from a set of available neighbor nodes, and replaces, if none of the current connections fail validation, a stochastically selected connection with a newly established connection from the set of available neighbor nodes for promoting perturbation in the current internode connections.

Mobile ad hoc networks (MANETs) based on wireless mesh protocols aim to provide connectivity to users without the requirements for existing infrastructure or prior network configuration. Such mesh networks employ a radio for providing the underlying network transport, and an end user device that may be a conventional end user computing device such as a smartphone or laptop, or a specialized device connected to a tactical radio. A number of radios in network proximity defines the mesh network operable for communications via the associated end user devices (EUDs).


A device for regulating and adjusting a distance between pairs of adjacent rollers in a peeling machine for almonds and similar dried fruits is provided, wherein the rollers are horizontally aligned at both sides of a central plane through which the product to be peeled is passed, the device including a movement transmission shaft coupled to each pair of adjacent rollers, a motor for operation of the movement transmission shaft, wherein the motor is coupled to one of the ends of the transmission shaft, a torque meter for measuring torque at various positions of the rollers, wherein the torque meter is coupled to a spin axis of at least one of the rollers in the pair, and a sensor for measuring and regulating a working distance between the rollers, wherein the sensor is coupled to at least the other roller in the pair.

In the current state of the art, there are several machines devoted to an extensive range of operations involved in the various processes related to handling and processing of almonds and other similar dried fruit. More specifically, peeling machines are designed for peeling and re-peeling of almonds, in which almonds, after being peeled and conditioned, follow a pre-determined course inside the machine to be subjected to some type of superficial friction. The friction determines the peeling of the nut skin and the collection of the skin in appropriate containers, which typically attract the skin due to a current of air or a similar procedure.
One of such known almond peeling devices is described in ES 200902283. This patent describes a peeling machine in which the skin peeling function is implemented by means of one or more pairs of rollers, which are vertically overlapping, each pair having an adjustable separation, which determine as a whole a central vertical plane for dropping almonds between the rollers. The sliding effect implemented by the rollers on the surface of almonds due to the difference in the rotating speed of each pair the rollers determines the peeling of the skin. The distance between rollers may vary, and, for that purpose, the machine has a hand wheel, which through a shaft or lead screw causes the rollers of each pair to come closer or further away from each other.
The machine described in ES 200902283 provided a substantial improvement over the nut peeling devices known in the art at that time. However, although this known peeling machine fully complies with the purpose for which it has been developed, it still suffers from a number of disadvantages. For example, the friction of the rollers on the almonds causes the manufacture material to wear out with time. Additionally, although this known machine includes detectors of such wear, another disadvantage is that the adjustment of the distance between the pressing rollers must be done manually with the help of an external wheel for each pair of rollers.
Therefore, the functional and productive characteristics of the machine described in ES 200902283 may be improved by providing a device that enables a precise adjustment of the working distance between the rollers in the operational range, which may be substantially small, preferably only a few millimeters, and more preferably around 4 mm. For this reason, given the small margin of the working range, a precise positional adjustment of the rollers is required, because a small variation due to the wear of the device or any other circumstance may have a considerable influence on the quality and/or efficiency of the peeling process.

Device for regulating and adjusting the position of rollers in peeling and re-peeling machines for almonds and similar dried fruits


A piston coupled to a crankshaft via pullrods presents challenges for coupling the piston to the crankshaft because the connections are provided outside the piston. A bridge is coupled to a piston skirt at the end of the piston away from the piston crown. The bridge structure includes: a central support structure, a first projection extending outwardly from the central support structure in a first radial direction, and a second projection extending outwardly from the central support structure in a second radial direction. The central support structure is substantially hollow with a series of internal braces to yield a lightweight piston.

Outer pistons in an opposed-piston engine, such as is shown in U.S. Pat. No. 6,170,443, are less conventional than inner pistons. In particular, the piston is coupled to the crankshaft via two connecting rods. And, the connecting rods, also called pullrods, are almost always operating in tension. An outer piston arrangement that is lightweight so as to reduce reciprocating mass is desired.


A wheel kit for use with a boat lift includes an upper member attachable to the boat lift, and a lower member slidably disposable within the upper member. The lower member contains an axle and a wheel assembly. A braking member includes a base plate with a first side and an opposing second side, a wedge portion outwardly extending from an upper end of the first side, and a tab outwardly extending from a lower end of the first side of the base plate. The braking member slidably disposes upon the axle via an aperture contained within the base plate. When positioning the lower member into the upper member to retract the wheel assembly, the wedge portion of the braking member contacts a closed terminal end of a slot contain within the upper member, outwardly urging the braking member against the wheel assembly to prevent rotation of the wheel assembly.

The present disclosure relates to boat lifts having retractable wheeled legs for transporting the boat lift in and out of water. More particularly, the present disclosure relates to a brake assembly connected to each leg to prevent the wheel from rotating when the leg, and thus the wheel, are positioned in an upright retracted position.
Boat lifts are known in the art as apparatuses that are placed in the water close to shore, especially near a dock, such that a boat can be floated thereover, and lifted out of the water when not in use. Placing the boat out of the water is a preferable way of storing the boat over extended periods of non-use, or to perform maintenance on the boat, without having to perform the extra work of entirely removing the boat out of the water via a boat trailer. However, the boat lift itself is sometimes required to be removed from the water. For example, in northern climates with freezing temperatures during the winter, it is often necessary to completely remove the boat lift from the water to avoid damage caused by freezing ice. To facilitate removal of the boat lift from the water, there exists in the art boat lifts having adjustable wheeled legs which allow the boat lift to be raised, supported by the wheels, and wheeled in and out of the water. When the boat lift is positioned in the water, the legs are retracted to position the wheel hub out of the water to prevent corrosion thereof. However, the tire of the wheel assembly, the lower portion of which is oftentimes in contact with the water, may still be allowed to rotate, urged by either the wind or lapping of waves. Over time, this rotation leads to mechanical wearing of the wheel's hub assembly, oftentimes requiring that the entire wheel assembly be replaced.
Attempts in the prior art have been made to prevent unwanted rotation of the wheel when in the retracted position. Such attempts, though, require use of a member protruding from, or near, the retractable leg, which can be obtrusive, especially when maneuvering the boat lift in and out of the water.
There therefore exists a need in the art to provide a non-obtrusive brake assembly to boat lifts having retractable wheeled legs which prevents movement of the wheel while in the retracted position.


A method and system of initiating a subscriber interface at a client subscriber device coupled to a server device. The method comprises receiving, at a memory of the server device, a specification identifying at least one sentiment parameter in association with the subscriber device, the sentiment parameter related to an expected result generated during execution of a sentiment community generation software application in the server device, generating, during execution of the sentiment community generation software application, a sentiment parameter task automaton representative of the sentiment parameter, monitoring, by the sentiment parameter task automaton, during concurrent execution with object code of the sentiment community software application, the expected result related to the sentiment parameter, and initiating, at the subscriber device, a subscriber interface that includes at least a notification of the at least one sentiment parameter in accordance with the monitoring during the concurrent execution.

Current techniques associate social connections of a user that can be used effectively for purposes such as promoting products and services or for making personalized interactions in a system. Such approaches may lack a system that can collect and interpret necessary information without limitations based literal interpretations of the information as collected, while respecting privacy rights of individuals.

Method and system for initiating an interface concurrent with generation of a transitory sentiment community


A furniture structure is described in which the component parts of the structure are disassembled to facilitate storage and shipment, Assembly of the unit is facilitated by convenient attachment pins or dowels and complementary slots in the respective components.

Because of their necessary configuration, typical items of furniture such as chairs are one of the most awkward and bulky items for shipment. A typical chair for example, occupies a much larger volume for shipping purposes then its size would otherwise seem to require, largely due to the number of projecting surfaces which typify chairs and other such furniture. For example, a typical rocking chair is provided with a relatively high back which extends in one direction and a pair of rockers extending roughly at right angles to the back of the chair, in addition to the actual seating structure and any arms which may be present on the chair. Accordingly, the size of container, or even just the space that is necessary to accommodate such a chair during shipment, is considerable and contributes significantly to the cost and effort of shipping these items.
It is accordingly, an object of the present invention to provide a furniture structure, such as a chair, which can readily be disassembled into several convenient parts in order to significantly minimize the volume required to ship or otherwise transport the furniture structure either by itself or in a container such as a large box.
It is a further object of the present invention to provide a chair structure having attachment means for the various components parts of the structure which provide a convenient, easy to assemble, interlocking system.
Yet a further object of the invention is to provide a system for assembly of the component parts of a furniture structure which is both simple and inexpensive and does not diminish the strength of the assembled unit.


The muscle efficiency of a living animal is evaluated with apparatus comprising a nuclear magnetic resonance (NMR) analytical device that comprises a hollow electromagnet having a bore of sufficient size to receive the animal. A treadmill within the bore and beneath the animal is utilized to produce locomotion of the animal at different rates of work. The NMR analytical device is used to measure at different rates of work the following ratio within a locomotion-producing muscle mass of the animal: ##EQU1## where Pi is the concentration within the muscle mass of inorganic phosphate and PCr is the concentration within the muscle mass of phosphocreatine. Means is provided for relating the measured ##EQU2## values to the rates of work then being performed by the animal to provide an efficiency profile for the muscle mass.

One of the above referenced Chance et al, U.S. Pat. No. 4,452,250 is entitled "NMR System for the Non-Invasive Study of Phosphorus Metabolism." This patent provides detailed electrical information relating to the basic construction of NMR apparatus suitable for employment in conjunction with apparatus of the present invention.
The other patent, Chance U.S. Pat. No. 4,441,502--, discloses NMR apparatus for determining the relationship between the work output rate of an exercising human body member and the steady-state capability of oxidative phosphorylation in a muscle responsible for the exercise. In the U.S. Pat. No. (4,441,502), this latter capability is determined by measuring with the NMR apparatus the ratio of the phosphocreatine (PCr) in the muscle to the inorganic phosphate (Pi) at different times during prescribed exercises. This latter ratio is a measure of the muscle efficiency.
Specifically described in this U.S. Pat. No. 4,441,502, is NMR equipment that includes a cylindrical electromagnet and a Cybex ergometer positioned adjacent to the electromagnet and having an oscillatable input lever within the bore of the electromagnet. A human subject places one of his arms within the bore of the electromagnet in a uniform field region thereof and grasps the oscillatable input lever, while the usual transceiver probe coil of the NMR equipment is maintained in proximity to the subject's wrist flexor muscle. The subject them oscillates the input lever by flexing his wrist at prescribed intervals through controlled strokes. Wristflexor muscle output is measured by the ergometer, while PCr and pi relationships are measured by the NMR apparatus.
Effective operation of the patented equipment depends upon the subject's carefully following prescribed instructions for the exercises. This being the case, it is difficult to utilize such equipment for evaluating the musculature of non-human animals, particularly untrained animals. Moreover, the patented equipment permits muscle evaluation only during the performance of relatively simple exercises, such as the above-described repetitive motion of the wrist of the subject.

Nuclear magnetic resonance apparatus for evaluating muscle efficiency and maximum power of muscle of a living animal


A method for communication between inside and outside of a transmission medium using the transmission medium as a communication line, includes the steps of: receiving an electric signal having information related to a transmission medium from a plurality of sensors inside the transmission medium; conducting the electric signal to the transmission medium; and sensing the electric signal flowing to the outside of the transmission medium. Because a modulating unit is not necessary, a power consumption is minimized. In addition, since an electric signal is directly conducted to a medium, it is not necessary to use an antenna, and thus, degradation of a reception rate according to a directional property of the antenna can be prevented. Moreover, since the electric signal is directly generated in the medium and the medium is directly used as an electric conductor, the overall size of a transmitter is reduced.

1. Field of the Invention
The present invention relates to a method and apparatus for communication between inside and outside of a transmission medium using the transmission medium as a communication line, and more particularly, to a method and apparatus for communication between inside and outside of a transmission medium using the transmission medium as a communication line in which a transmitter is placed inside a transmission medium and conducts an electric signal through the transmission medium to a receiver for receiving the electric signal, to thereby improve a reception rate of a signal without doing a damage to the transmission medium.
2. Description of the Background Art
A conventional communication method between inside and outside of a transmission medium is that if the transmission medium is a human body, information related to human body obtained by sensors in the internal organs of human body by using a radio frequency signal in a frequency domain harmless to men is transmitted outside the human body.
The conventional method, however, has problems that since a low speed data is modulated to the RF signal of a few to scores of MHz and transmitted, its power consumption is great.
In addition, due to the directional property problem of an antenna, the reception rate of the RF signal can be easily changed and it is not easy to have a compact size antenna and RF circuit.

Method and apparatus for communication between inside and outside of transmission medium using transmission medium as communication line

Korea Institute of Science and Technology


Apparatus including a planar leg pivotally mounted adjacent its rear arcuate end to a wallet adjacent the wallet's transverse hinge. The leg includes a forward end extending beyond a right side of the wallet wherein the forward end includes a series of serrations for engagement of an interior side of an individual's pocket preventing inadvertent and unwarranted removal of the wallet from the pocket. Modifications of the invention inlcude resilient deformable portions positioned between the serrations to prevent unnecessary projection of the serrations into the pocket and further permitting a penetration of the serrations into the pocket upon an unwarranted attempt to remove the wallet from the pocket.

1. Field of the Invention
The field of the invention relates to wallet securement apparatus, and more particularly pertains to a new and improved wallet securement apparatus wherein the same includes a plate member to selectively secure a wallet into a pocket preventing unwarranted and unauthorized removal therefrom.
2. Description of the Prior Art
The prior art has provided apparatus to secure a wallet organization within a pocket. The prior art however has heretofore utilized cumbersome structure to effect this purpose or has alternatively included an organization relatively elaborate for achieving a locking of a wallet within a pocket to prevent unwarranted removal therefrom.
Examples of the prior art include U.S. Pat. No. 4,825,922 to ROLFS wherein a wallet includes a resilient tab extending from a forward wall of the pocket to attempt to engage an interior wall of the pocket preventing unauthorized removal therefrom.
U.S. Pat. No. 4,241,476 to CHRISTENSON et al utilizing a generally U-shaped resilient member formed through and secured to the hinge of an associated wallet with the legs of the U-shaped member projecting laterally of the wallet to engage side walls of the pocket preventing unwarranted removal.
U.S. Pat. No. 3,142,876 to ROBERTS illustrates a spring biased generally V-shaped member secured to interior portion of the wallet to engage adjacent ends of the pocket.
U.S. Pat. No. 4,051,123 to OKERELOM illustrates the use of a spring biased leg projecting exteriorly of a side wall of the wallet to engage an interior edge of the pocket preventing removal of the wallet.
U.S. Pat. No. 4,355,440 to JOHANSSON et al utilizes a further example of plural legs projecting laterally of a wallet to engage opposed side edges of a pocket to create abutments preventing unauthorized removal of the wallet from the pocket.
As such, it may be appreciated there continues to be a need for a new and improved wallet securement apparatus wherein the same addresses both the problems of effectiveness in construction as well as ease of application to existing wallet structure and in this respect, the present invention substantially fulfills this need.


A laser crystallization apparatus, which enables an observation of a high spatial resolution with several μm and a high temporal resolution with several nanoseconds, comprising a crystallization optical system to irradiate a laser light to a thin film provided on a substrate and to melt and crystallize the thin film, the laser crystallization apparatus comprises an illumination light source disposed out of an optical path of the laser light and emitting an illumination light for observation to illuminate the thin film, an illumination optical system comprising an annular optical element which has the optical path of the laser light in the center and which leads the illumination light from the illumination light source to the thin film along the optical path, and an observation optical system which displays a magnified image of the substrate including the thin film.

1. Field of the Invention
The present invention relates to a crystallization apparatus which irradiates laser light-to a thin film such as a semiconductor film and to a crystallization method, and more specifically to a laser crystallization apparatus and a laser crystallization method in which melting and crystallization process of the semiconductor film can be observed in a magnified image in real time.
2. Description of the Related Art
A laser crystallization technology has been developed, in which, for example, a high-energy short-pulse laser light is used to melt and crystallize a semiconductor thin film to make a non single-crystal thin film, for example, an amorphous or polycrystal semiconductor film into a crystallized thin film including an area with large crystal grains. This technology is used for crystallization of a non single-crystal semiconductor film used for a thin-film transistor for display devices such as liquid crystal display devices and organic electro luminescence display devices, for example.
Among such laser crystallization technologies, attention is focused on a Phase Modulated Excimer Laser Annealing (PMELA) which irradiates a phase-modulated excimer laser light for crystallization. The PMELA technology forms a homogenized excimer laser light into a laser light having a predetermined light intensity distribution. The laser light is phase-modulated by a phase modulating element, such as a phase shifter, for example, to have an inverse peak light intensity distribution. The laser light is irradiated through a crystallization optical system to a semiconductor film, for example, an amorphous or polycrystal silicon thin film formed on a glass substrate of large-area, such that the semiconductor film is melted and crystallized to form a semiconductor film having large crystal grains. According to the currently developed PMELA technology, an area of a size of about several mm square is melted and crystallized in one irradiation, such that a crystallized silicon thin film with high quality is formed which has relatively uniform and large crystal grains sized from several μm to about 10 μm. Details of which is described, for example, in "Amplitude and Phase Modulated Excimer-Laser Melt-Regrowth Method of Silicon Thin-Films—A New Growth Method of 2-D Position-Controlled Large-Grains-", published by Kohki Inoue, Mitsuru Nakata, Masakiyo Matsumura, in a thesis journal of Institute of Electronics, Information and Communication Engineers, Vol. J85-C, No. 8, pp. 624-629, 2002.
In the current PMELA technology, excimer laser light power varies from about 5% to 10% in a practical use. However, as compared with the stability of the excimer laser light, a process margin to form a crystallized silicon thin film having a predetermined quality is extremely narrow. Thus, to industrialize the EPMLA technology, the process margin needs to be increased to form the crystallized silicon thin film with a higher and stabilized quality. In response to this, there is a need to observe or measure a change of the silicon thin film through images or the like, in which the silicon thin film is melted in a small area and then crystallized, in real time with a high spatial resolution of several μm, and/or with a high temporal resolution of an order of nanoseconds (hereinafter referred as nsec) immediately after the laser light irradiation.
A method for evaluating crystallinity of a laser-annealed silicon thin film has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-257176. This method comprises applying observation light to a silicon thin film being crystallized, using a spectrophotometer to subject reflected light to, for example, Raman spectrometry, and thus evaluating the crystallinity of a polycrystal silicon thin film after crystallization.
In an ELA technology which does not perform phase modulation, an experimental example in which thermal characteristics of a melted and crystallized silicon thin film are in-situ-measured by in-situ-measuring means has been reported in M. Hatano, S. Moon, M. Lee, K. Suzuki, and C. Grigoropoulos; J. Applied Physics, Vol. 87, No. 1, pp. 36-43, 2000, "Excimer laser-induced temperature field in melting and resolidification of silicon thin films". This report regards measurement of thermal characteristics of the melted and crystallized silicon thin film with a high temporal resolution of an order of nsec. More specifically, helium-neon (He—Ne) laser light (wavelengths 633 nm and 1520 nm) as a probe light for observation is applied to melted and crystallized area obliquely from above. Reflected and/or transmitted light from the melted and crystallized area is detected by a high speed responsive indium-gallium-arsenide photodetector and/or by a silicon pn photodiode to measure the thermal characteristics of the silicon thin film.
Furthermore, an in-situ observation method of simultaneously irradiating crystallization laser light and observation light has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2002-176009. In the patent, an objective lens with hole is used both for irradiation of the crystallization laser light and for illumination and detection of the observation light. The crystallization laser light is excimer laser light which is not phase-modulated, and is irradiated to a film being processed through the hole provided to the objective lens. In an annealing process, the reflected light by the film being processed is detected though the objective lens with hole to measure in situ changes in reflectance, Raman spectrum and the like on, for example, of a sample surface. That is, crystallinity evaluation is executed from a physical property value of the crystallized area.
Problems in industrializing a mass production line for crystallization utilizing an ELA apparatus used here include improvement in yield of a crystallization process, and stabilization in quality control by monitoring the crystallization process by an operator due to instabilities of irradiating laser light, such as missing of a pulse and/or fluctuation in the intensity, for example. Where an irradiation period of a laser pulse for crystallization is very short, e.g., about 25 to 30 nsec. To solve these problems, there is a need to observe or measure, through images, a changing state or a crystallized area of the silicon thin film in situ and in real time with a high spatial resolution of several μm and with a high temporal resolution of the order of nsec immediately after laser light irradiation, wherein the silicon thin film is melted in a small area in a time period of about ten to several hundreds nsec and then crystallized.
The method in the Jpn. Pat. Appln. KOKAI Publication No. 2001-257176 described above is not suitable for the purpose of observing the crystallization of the silicon thin film through images. The method in the Jpn. Pat. Appln. KOKAI Publication No. 2002-176009 is available for observing through images, however it is not suitable for observing the changing silicon film from melting to crystallization through images with the high temporal resolution and/or high spatial resolution.
The method of M. Hatano et al. has high resolution in time, but is not applicable to an image observation system that satisfies both the high spatial resolution of several μm or less and the high temporal resolution of several nsec at the same time.
The present inventors have found out that, for a higher quality of the crystallized semiconductor thin film, it is desired to install an image observation system, that is, an optical system for observation, in a laser crystallization apparatus, for example, an excimer laser crystallization (ELA) apparatus. In which the semiconductor thin film is changing from a melted state to a crystallized state, and is observed through images with a high spatial resolution of several μm and with a high temporal resolution of the order of nsec, in real time or during laser melting, or the crystallization immediately after melting.
The present inventors have therefore studied incorporating a microscopic observation system capable of image observation into the ELA apparatus in order to enable the in-situ (real-time) observation. To incorporate a microscopic observation optical system into an optical system of the ELA apparatus, it is preferable to use an optical system in which aberration correction has been made simultaneously for excimer laser light for crystallization (ultraviolet light) and illumination light for observation (visible light). The microscopic observation optical system is capable to observe image of a melted and crystallized semiconductor film or a crystallized area, in situ (in real time).
The following problems additionally arise to solve problems described above and to satisfy desire described above. A high resolution (several μm) is preferable in the ELA apparatus, particularly in a projection type phase modulated (PM) ELA apparatus using a phase shifter. It is assumed that lenses practically used in the PMELA apparatus are used at a high light intensity, at high duty and in a large area for production efficiency. More specifically, the laser light intensity is preferably about 1 J/cm2 on a substrate to be crystallized. In order to obtain the high light intensity, the excimer laser light is used with a wide spectral bandwidth (0.5 nm), unlike in an aligner used for large-scale integrated circuit production. Due to the high-energy light, a lens configuration including pasted and laminated lenses such as microscopic lenses for visible light is not preferable in terms of heat resisting properties. Further, the excimer laser light to be used is, for example, krypton fluoride (KrF) or xenon chloride (XeCl), and their wavelengths are 248 nm and 308 nm, respectively. When the wavelengths of these laser lights are taken into account, lens materials that can preferably be used are limited to UV-grade synthetic quarts or calcium fluoride (CaF2), which reduces the freedom in lens designing. Moreover, for example, the correction of aberration, such as chromatic aberration and distortion aberration of the ultraviolet light, has to be made for the lens (group) used in the PMELA apparatus, for example, to transfer a mask pattern of the phase shifter onto the substrate in a reduced or equal size with a high resolution of about several μm.
When the excimer laser light and the microscopic observation visible light are used in this single optical system, the aberration correction has to be made simultaneously in two wavelength areas including the ultraviolet light and the visible light, which is a significantly difficult problem. Even if the chromatic aberration can be corrected, the number of lenses has to be increased, thus increasing the absorption of light by the lenses. This reduces the intensity of the laser light arriving onto the substrate, which goes against the demand to obtain a high light intensity preferred for crystallization.
Another problem is that the crystallization optical system adapted to the excimer laser light with the above-described performance reduces the resolution of the visible light when it transmits the visible light. Specifically, the resolution is proportional to the wavelength of light, so that in the case of the visible light (wavelength: 480 nm to 600 nm) having about double of the wavelength of the excimer laser light (wavelength: 248 nm, 308 nm), for example, a resolution of 2 μm is reduced to about 4 μm in the visible light, which is double the former. As a result, it cannot be obtained a resolution of 1 μm necessary to observe or measure the images of the crystallized area of several μm.
That is, the optical system that can accommodate such a demand need to be stably used for at least two different wavelengths: the excimer laser light for crystallization (e.g., wavelength 248 nm) having a high light intensity (e.g., 1 J/cm2 or higher on the substrate), a large irradiation area (e.g., 5.5 mm2 or larger) and high duty (e.g., a laser operating frequency of 100 Hz or higher), and the illumination light for observation being, for example, the visible light (e.g., wavelengths ranging from 480 nm to 650 nm).
As such an example, a high resolution UV laser condenser lens for microscopes, for example, model KVH20-8, Showa Optronics, is commercially available, in which chromatic aberration is corrected simultaneously in wavelength ranges of both the ultraviolet light and visible light. The condenser lens is designed to use one optical system to process a small area (e.g., 0.5 mm2 or less) with the excimer laser light and to observe with the visible light. The processing of the small area by the optical lens is intended to, for example, cut a part of wiring in an integrated circuit by irradiating the laser light. The lens sufficiently satisfies the desire with the spatial resolution (1 μm), but is not capable of an operation with the above-described high light intensity, large irradiation area and high duty.
Furthermore, an observation needs to be made with a high temporal resolution of an extremely short-time (nsec) to observe in real time through the images of the semiconductor film provided on the substrate in a melting and crystallizing state. It requires a high-luminance illumination light source for observation conforming to the short-time observation. If the visible light is applied as such illumination light for observation through a large number of optical lenses, this causes not only a problem of loss in amount of light but also a problem of an adverse effect on the imaging performance of the original ultraviolet light.
An object of the present invention is to provide a laser crystallization apparatus and a laser crystallization method in which images of an area of several μm on the semiconductor thin film melting and crystallizing in several hundreds nsec can be observed or measured in real time or immediately after that with a high spatial resolution of several μm or less and with a high temporal resolution.

Laser crystallization apparatus and laser crystallization method

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