A multivariable feedback control system is designed for a submersible. The control variables are the bow, rudder, and differential stern control surfaces; these are dynamically coordinated so as to cause the vehicle t...
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A multivariable feedback control system is designed for a submersible. The control variables are the bow, rudder, and differential stern control surfaces; these are dynamically coordinated so as to cause the vehicle to follow independent and simultaneous commanded changes in yaw rate, depth rate, pitch attitude, and roll angle. Two designs were evaluated using a nonlinear submersible simulation. One used all four control variables so that active roll control was possible. The other used only three control variables, and active roll control was not employed. Both feedback systems were designed using the Linear Quadratic Gaussian (LQG) with Loop Transfer Recovery (LTR) design methodology so as to meet similar design specifications in the frequency domain. Both the linearized models, and the non-linear simulation have shown that active roll control yields a very significant improvement in submersible performance. Active roll control minimized unwanted depth changes in difficult commanded trajectory scenarios.
Preliminary Kerr electro-optic field and space charge mapping measurements are reported in weakly birefringent materials typically used in high voltage insulation applications. Measurements are reported in mineral tra...
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Preliminary Kerr electro-optic field and space charge mapping measurements are reported in weakly birefringent materials typically used in high voltage insulation applications. Measurements are reported in mineral transformer oil with and without creped paper and glue typically used in power transformers, silicone oil used as a retro-fill fluid for PCB contaminated transformers, liquid and gaseous sulfur hexafluoride used as high voltage insulation in compact power apparatus, and polymethylmethacrylate, both high voltage stressed and electron beam irradiated to high fields.
作者：
Adler, DavidMIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
Present and future markets for photovoltaic devices are discussed. It is pointed out that such devices are already a major industry rather than just a hope for the future. Existing commercial devices and other near-te...
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Present and future markets for photovoltaic devices are discussed. It is pointed out that such devices are already a major industry rather than just a hope for the future. Existing commercial devices and other near-term possibilities are described. Some companies involved in research, development, and/or commercial production associated with each class of material are identified.
Laser speckle is a prominent source of fluctuations in heterodyne-detection imaging and differential absorption lidar systems. This paper calculates the transverse and longitudinal degrees of coherence between pairs o...
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Laser speckle is a prominent source of fluctuations in heterodyne-detection imaging and differential absorption lidar systems. This paper calculates the transverse and longitudinal degrees of coherence between pairs of speckle intensities obtained, in different observation conditions, with a monostatic heterodyne-reception sensor.
作者：
Glass, James R.Zue, Victor W.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
The quantification of acoustic measures that characterize nasalized vowels is considered. The investigation derives from the fact that the detection of nasalized vowels is useful in speech recognition, since regions c...
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The quantification of acoustic measures that characterize nasalized vowels is considered. The investigation derives from the fact that the detection of nasalized vowels is useful in speech recognition, since regions can be identified in the speech signal where a nasal consonant may be present, and where the vocal tract resonances are distorted. The study consists of several steps. First, an acoustic study was performed using utterances from a large database in order to propose potential measures of nasality. Next, automatic algorithms were developed to extract these measures and their utilities were established through examination of a large amount of data. Finally, recognition experiments were performed using these measures. The system detected nasalized vowels with an accuracy of approximately 74%, when tested on one speaker at a time and trained on the speech of the remaining speakers in the database.
作者：
Feder, MeirWeinstein, EhudMIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
The authors have developed an algorithm for multiple source localization based on the estimate-maximize (EM) method. The EM method is an iterative algorithm that converges to the maximum-likelihood (ML) estimate of th...
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The authors have developed an algorithm for multiple source localization based on the estimate-maximize (EM) method. The EM method is an iterative algorithm that converges to the maximum-likelihood (ML) estimate of the unknown parameters by exploiting the stochastic system under consideration. In the case considered the algorithm will converge to the exact ML estimates of the various source location parameters, where each iteration increases the likelihood of those parameters.
The throughput of a combinational array multiplier is shown to be asymptotically suboptimal using performance measures derived from VLSI models of computation. Applying a systematic transformation called retiming, a c...
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The throughput of a combinational array multiplier is shown to be asymptotically suboptimal using performance measures derived from VLSI models of computation. Applying a systematic transformation called retiming, a class of asymptotically optimal pipelined array multipliers is obtained. The optimum circuit performance within this class must be determined empirically through repeated iterations of multiplier layout generation, circuit extraction, and electrical simulation. The structure of these pipelined multipliers facilitates such an empirical investigation by admitting very regular layouts that can be generated quickly and interactively.
作者：
Anderson, James C.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
A new relationship between filter detectors and the short-time Fourier transform magnitude is derived. The result provides a common basis for comparison of speech spectrograms, the sliding discrete Fourier transform, ...
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A new relationship between filter detectors and the short-time Fourier transform magnitude is derived. The result provides a common basis for comparison of speech spectrograms, the sliding discrete Fourier transform, average power spectrum estimation techniques, perception-based speech analysis systems, and channel vocoders.
作者：
Aull, Ann MarieZue, Victor W.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
The determination of lexical stress for isolated words from the acoustic signal is considered. The investigation derives from the suggestion that stressed syllables can provide islands of reliability where the phoneti...
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The determination of lexical stress for isolated words from the acoustic signal is considered. The investigation derives from the suggestion that stressed syllables can provide islands of reliability where the phonetic information is more robust. In addition, stress information has been found to help lexical access. The study consisted of three parts. First, it was established through a lexical study that stress information can indeed provide strong constraints for large vocabulary, isolated word speech recognition. Second, an acoustic study was conducted to determine the acoustic correlates of lexical stress. Finally, a system was developed to determine the lexical stress patterns from the speech signal. The system performance, evaluated on some 1600 words spoken by 11 talkers, indicated that the stressed syllable can be detected with a 2% error rate. The entire stress pattern can be determined with an error of 13%, with a significant amount of the error attributable to the system's failure to identify the proper number of syllables.
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