The controlled pointing of an Earth-orbiting astronomical telescope in the presence of time-dependent gravity-gradient torques is studied using recent techniques for the analysis and synthesis of time-varying linear s...
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The controlled pointing of an Earth-orbiting astronomical telescope in the presence of time-dependent gravity-gradient torques is studied using recent techniques for the analysis and synthesis of time-varying linear scalar dynamical systems. We present results which show that effective adaptive control of unstable motions due to gravity gradient torques can be accomplished, resulting in high pointing accuracy and stability for astronomical telescopes in both circular and elliptical orbits.
An approach is presented for efficiently designing and implementing FIR (finite impulse response) filter banks with equal passband bandwidths. The overall bank of L filters is generated from a prototype 2Lth-band filt...
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An approach is presented for efficiently designing and implementing FIR (finite impulse response) filter banks with equal passband bandwidths. The overall bank of L filters is generated from a prototype 2Lth-band filter with the aid of a few additional coefficients and adders. The attractive properties of these filter banks are that the sum of filter outputs is guaranteed to be a pure delay and the passband bandwidths are the same for all the filters.< >
A procedure for the reformulation of Chang's criterion (1981) for the absence of zero-input limit cycles in recursive digital filters is presented. The technique employs the standard bilinear transform to convert ...
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A procedure for the reformulation of Chang's criterion (1981) for the absence of zero-input limit cycles in recursive digital filters is presented. The technique employs the standard bilinear transform to convert a frequency-domain criterion into a polynomial form in terms of matrix transformations. The use of the method is illustrated with design examples applied to determine the stability region for certain single-quantizer recursive filter structures. The results can be utilized, e.g., in the design of an error feedback network for a given filter such that limit cycles are eliminated.< >
We describe the applicability of oxygen based Electron Cyclotron Resonance (ECR) etching of diamond for the purpose of fabricating electronic test structures and recessed gate field effect transistors. Boron doped hom...
We describe the applicability of oxygen based Electron Cyclotron Resonance (ECR) etching of diamond for the purpose of fabricating electronic test structures and recessed gate field effect transistors. Boron doped homoepitaxial diamond films grown in a microwave assisted CVD reactor were used for this study. Etch rates from 8 nm/min up to 0.5 μm/min. were achieved depending on etch parameters.
An adaptive VLSI neuroprocessor based on vector quantization algorithm has been developed for real-time high-ratio image compression applications. This VLSI neural-network-based vector quantization (NNVQ) module combi...
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An adaptive VLSI neuroprocessor based on vector quantization algorithm has been developed for real-time high-ratio image compression applications. This VLSI neural-network-based vector quantization (NNVQ) module combines a fully parallel vector quantizer with a pipelined codebook generator for a broad area of data compression applications. The NNVQ module is capable of producing good-quality reconstructed data at high compression ratios more than 20. The vector quantizer chip has been designed, fabricated, and tested. It contains 64 inner-product neural units and a high-speed extendable winner-take-all block. This mixed-signal chip occupies a compact silicon area of 4.6*6.8 mm/sup 2/ in a 2.0- mu m scalable CMOS technology. The throughput rate of the 2- mu m NNVQ module is 2 million vectors per second and its equivalent computation power is 3.33 billion connections per second.< >
The frequency-sensitive competitive learning (FSCL) algorithm and its associated VLSI neuroprocessor have been developed for adaptive vector quantisation (AVQ). Simulation results show that the FSCL algorithm is capab...
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The frequency-sensitive competitive learning (FSCL) algorithm and its associated VLSI neuroprocessor have been developed for adaptive vector quantisation (AVQ). Simulation results show that the FSCL algorithm is capable of producing a good-quality codebook for AVQ at high compression ratios of more than 20 in real time. This VLSI neural-network-based vector quantization design includes a fully parallel vector quantizer and a pipelined codebook generator to provide an effective data compression scheme. It provides a computing capability as high as 3.33 billion connections per second. Its performance can achieve a speedup of 750 compared with SUN-3/60 and a compression ratio of 33 at a signal-to-noise ratio of 23.81 dB.< >
The goal of this research is to develop a multi-layer feedforward neural network architecture which can distinguish targets (in this case, mines) from background clutter in sidescan sonar images. The network is to be ...
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The goal of this research is to develop a multi-layer feedforward neural network architecture which can distinguish targets (in this case, mines) from background clutter in sidescan sonar images. The network is to be implemented on a hardware neurocomputer currently in development at CSDL, with the goal of eventual real-time performance in the field. A variety of neural network architectures are developed, simulated, and evaluated in an attempt to find the best approach for this particular application. It has been found that classical statistical feature extraction is outperformed by a much less computationally expensive approach that simultaneously compresses and filters the raw data by taking a simple mean.< >
We give a characterization for the intractability of hyperelliptic discrete logarithm problem from a viewpoint of computational complexity theory. It is shown that the language of which complexity is equivalent to tha...
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Using plasma immersion ion implantation (PIII), sub-100 nm p+/n junctions were fabricated with SiF4 preamorphization followed by BF3 doping. With this technique, the dose rate can be as high as 1016/cm2 per second. Th...
A criterion for the absence of zero-input limit cycles in recursive digital filter structures that can be implemented with a single quantizer in the recursive loop is presented. The criterion can be applied with a rou...
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A criterion for the absence of zero-input limit cycles in recursive digital filter structures that can be implemented with a single quantizer in the recursive loop is presented. The criterion can be applied with a rounding or with a magnitude truncation quantizer and accounts for the use of error feedback as well. Additionally, a criterion for the elimination of constant-input limit cycles is formulated. The criteria are applied to several well-known filter structures. Since most of the structures have previously been analyzed in a multiquantizer implementation only, new results on their stability properties in the single-quantizer configuration are obtained.< >
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