The analysis of marine mammal sounds has been a subject of considerable interest for a number of years. The tool of choice for revealing the timefrequency characteristics of these sounds has been the spectrogram (sono...
详细信息
The authors discuss the current control and pulse width modulation (PWM) pattern generation of a multilevel power converter which is capable of producing three levels of phase voltage. In the proposed current control,...
详细信息
The authors discuss the current control and pulse width modulation (PWM) pattern generation of a multilevel power converter which is capable of producing three levels of phase voltage. In the proposed current control, fast response is realized by introducing a converter model in the control algorithm and the effect of parameter difference between the model and an actual system is compensated for through proportional-plus-integral control of current difference. In PWM pattern generation, the balance of two capacitor voltages is taken into account. For the same sampling period, the current distortion factor of the proposed system can be approximately reduced to 60% of that of a conventional two-level power converter. The prototype was made using a digital signal processor, and simulation and experimental results were compared.< >
The authors discuss the formal description of a real time application, viz a fault management system (FMS) for the OSI environment, using O-Estelle. O-Estelle is an object oriented specification language that has been...
详细信息
The authors discuss the formal description of a real time application, viz a fault management system (FMS) for the OSI environment, using O-Estelle. O-Estelle is an object oriented specification language that has been proposed by the authors for describing real time applications (Prabhakaran and Ragahvan, 1990). O-Estelle is an Estelle based language with extended features. A distributed FMS is a set of fault managers running concurrently on several systems. It is the responsibility of the fault manager (FM) on each system to detect, isolate and possibly rectify the faults in the system. Management services are provided to the FM to perform its tasks and to communicate with FMs on other systems. The formal description of such a distributed application requires additional features in description languages like Estelle. O-Estelle description of the FMS can be used for protocol verification and semiautomatic generation of software for FMS.< >
A combined source encoding and modulation technique based on permutation codes is described. This combined system directly maps the source codewords into modulation symbols. This system offers improvement in terms of ...
详细信息
A combined source encoding and modulation technique based on permutation codes is described. This combined system directly maps the source codewords into modulation symbols. This system offers improvement in terms of better overall fidelity, reduced encoding delay, and robustness. Nearly optimal codes for Gaussian and Laplacian sources in the presence of an AWGN channel are obtained. The performance of these codes and the combined system is evaluated and compared with other existing systems.< >
A technique for associating an image is described in terms of the network constraint analysis. Pixels and their gray-values are called units and labels, respectively, and a set of n pixels called the unit constraint s...
详细信息
A technique for associating an image is described in terms of the network constraint analysis. Pixels and their gray-values are called units and labels, respectively, and a set of n pixels called the unit constraint set T provides the unit-label constraint set R for memorized images. Given an incomplete image X which can have occlusion, noise, distortion, etc., R receives screening by X to yield the reduced set R* (R* contained in R), since the elements of X constrain the elements in R. A dept. first search is then applied to the elements of R* to obtain consistent solutions, if any, which are associated images. The proposed technique is free from the interference among memorized images which other association techniques suffer from. An iterative technique is also proposed for speeding up the dept. first search. Performance of the proposed association technique is shown by the experiment employing 26 alphabetical letters.< >
A multifaceted approach to automation of the software fault localization process is proposed. The facets include the development of a conceptual process model derived from empirical studies; the implementation of a bl...
详细信息
A multifaceted approach to automation of the software fault localization process is proposed. The facets include the development of a conceptual process model derived from empirical studies; the implementation of a blackboard-based fault localization tool built on model underpinnings, and tool integration in a computer-aided software engineering (CASE) environment that will provide long term support for its functionality and expandability. The authors report on the progress in modeling studies and development of the tool architecture.< >
The authors study the ergodic control problem of switching diffusions of representing a typical hybrid system that arises in numerous applications such as fault-tolerant control systems and flexible manufacturing syst...
详细信息
The authors study the ergodic control problem of switching diffusions of representing a typical hybrid system that arises in numerous applications such as fault-tolerant control systems and flexible manufacturing systems. Under certain conditions, they establish the existence of a stable Markov nonrandomized policy which is almost certainly optimal for the pathwise long-run average cost criterion. They they study the corresponding Hamilton-Jacobi-Bellman (HJB) equation and establish the existence of a unique solution in a certain class. Using this, they characterize the optimal policy as a minimizing selector of the Hamiltonian associated with the HJB equations. They apply these results to a failure-prone manufacturing system and show that the optimal production rate is of the hedging point type.< >
Variations of the quantitative feedback technique (QFT) are applied to a multi-input-multi-output (MIMO) flight control problem with unstable, nonminimum phase plants. The authors present specialized techniques that e...
详细信息
Variations of the quantitative feedback technique (QFT) are applied to a multi-input-multi-output (MIMO) flight control problem with unstable, nonminimum phase plants. The authors present specialized techniques that enable the designer to achieve acceptable results for effective plants which are both unstable and non-minimum phase. The weighting matrix function is discussed, and a method of developing frequency dependent compensation is presented. The longitudinal control system, defined as a single-input-single-output (SISO) system, is designed using the loop transmission function. The limitations imposed by right-half-plane poles and zeros are discussed as the design is presented. A straightforward approach to designing a prefilter is also presented. Singular-G and optimal blending methods are used to improve the achievable stability characteristics of the lateral-directional (MIMO) effective plant. A brief discussion of the design of prefilters for a MIMO system is included.< >
A parallel version of the CKY-parsing algorithm for context-free grammar is presented. The algorithm uses parallel random access machine (PRAM) models of computation and parses a string (or sentence) of length n in pa...
详细信息
A parallel version of the CKY-parsing algorithm for context-free grammar is presented. The algorithm uses parallel random access machine (PRAM) models of computation and parses a string (or sentence) of length n in parallel time O(n log n), employing O(n/sup 2/) processors. The proposed algorithm uses a very simple procedure, and provides multiple parses for ambiguous languages.< >
A new technique is presented for evaluating the jitter performance of a symbol timing recovery (STR) subsystem for binary synchronous data transmission systems. The STR system consists of any even-symmetric zero-memor...
详细信息
A new technique is presented for evaluating the jitter performance of a symbol timing recovery (STR) subsystem for binary synchronous data transmission systems. The STR system consists of any even-symmetric zero-memory nonlinear device followed by a narrowband filter tuned to the pulse repetition frequency. The exact analytical expressions are derived for the mean and the mean-squared values of the timing wave, based on the high-order moments of the input signal. The root-mean-square jitter performance is then computed as a function of various system parameters such as the power series expansion of the zero-memory nonlinear device, prefiltering, and postfiltering. The numerical results obtained from some specific examples serve to illustrate several aspects of the timing recovery problem.< >
暂无评论