A number of fiber optic configurations for a new class of demand assignment multiple-access local area networks requiring a physical ordering among stations are proposed. In such networks, the data transmission and li...
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A number of fiber optic configurations for a new class of demand assignment multiple-access local area networks requiring a physical ordering among stations are proposed. In such networks, the data transmission and linear-ordering functions may be distinguished and be provided by separate data and control subnetworks. The configurations proposed for the data subnetwork are based on the linear, star, and tree topologies. To provide the linear-ordering function, the control subnetwork must always have a linear unidirectional bus structure. Due to the reciprocity and excess loss of optical couplers, the number of stations that can be accommodated on a linear fiber optic bus is severely limited. Two techniques are proposed to overcome this limitation. For each of the data and control subnetwork configurations, the maximum number of stations as a function of the power margin, for both reciprocal and nonreciprocal couplers, is computed.
A continuous layered medium is probed by sinusoidal spherical waves from a point harmonic source, and the reflection response of the medium is measured. By performing this experiment at two different source frequencie...
A continuous layered medium is probed by sinusoidal spherical waves from a point harmonic source, and the reflection response of the medium is measured. By performing this experiment at two different source frequencies, the separate density and sound‐speed profiles ρ(z) and c(z) are recovered. Two experimental configurations are considered: the case in which the inhomogeneous medium is confined between two infinite homogeneous half‐spaces and is probed from the upper half‐space, and the case in which the inhomogeneous medium is bounded above by a free‐surface, at which the source is located. Layer‐stripping fast algorithm solutions to both of these inverse problems are obtained and illustrated with examples. The algorithms are interpreted physically as constructing distributions of image sources that simulate the medium response at each depth.
A state observer driven by measurements of phase voltages and currents is developed for variable reluctance motors. The exponential stability of the observer error in a neighborhood of the origin is proven for the cas...
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Simulated annealing is a popular Monte Carlo algorithm for combinatorial optimization. The annealing algorithm simulates a nonstationary finite state Markov chain whose state space Ω is the domain of the cost functio...
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Simulated annealing is a popular Monte Carlo algorithm for combinatorial optimization. The annealing algorithm simulates a nonstationary finite state Markov chain whose state space Ω is the domain of the cost function to be minimized. We analyze this chain focusing on those issues most important for optimization. In all of our results we consider an arbitrary partition optimization {I, J} of Ω; important special cases are when I is the set of minimum cost states or a set of all states with sufficiently small cost. We give a lower bound on the probability that the chain visits I at some time less than or equal to k, for k = 1,2, .... This bound may be useful even when the algorithm does not converge. We give conditions under which the chain converges to I in probability and obtain an estimate of the rate of convergence as well. We also give conditions under which the chain visits I infinitely often, visits I almost always, or does not converge to I, with probability 1.
This paper considers the application of Kalman estimation theory to the problem of estimating two-dimensional isotropic random fields, whose equations are expressed in terms of the Laplacian, given some noisy observat...
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This paper considers the application of Kalman estimation theory to the problem of estimating two-dimensional isotropic random fields, whose equations are expressed in terms of the Laplacian, given some noisy observations on a finite disk. It is shown that this problem is equivalent to that of solving a countably infinite number of one-dimensional estimation problems. Markovian models for the one-dimensional processes are developed and the associated Kalman filters are shown to be asymptotically stable. The desired field estimate is then obtained by combining the smoothed estimates resulting from each of the one-dimensional problems weighted in an appropriate fashion.
The electrical failure of practical oil insulated apparatus often develops as a surface flashover along the interface of a solid dielectric support and the oil. While there is substantial reported information about br...
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The electrical failure of practical oil insulated apparatus often develops as a surface flashover along the interface of a solid dielectric support and the oil. While there is substantial reported information about breakdown and streamer propagation in plain oil gaps, there is little comparable information about the surface flashover case. The studies reported here concern measured surface flashover characteristics and mechanisms of a point-to-plane gap with a solid dielectric surface perpendicular to the plane bridging the gap. A nanosecond risetime step voltage was applied, and the currents and time to breakdown were determined by an electro-optic coupling method.
Highly purified water is being investigated for use as a high voltage dielectric due to its high permittivity, ε≈80ε ο , and relatively high resistivity, ρ≈60MΩ-cm at 6°C. Previous Kerr electro-optic field...
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Highly purified water is being investigated for use as a high voltage dielectric due to its high permittivity, ε≈80ε ο , and relatively high resistivity, ρ≈60MΩ-cm at 6°C. Previous Kerr electro-optic field mapping measurements using parallel plate electrodes have shown significant space charge distortion of the electric field in the dielectric. The sign and magnitude of the space charge injected into the dielectric was shown to be a function of the electrode materials and voltage polarity. For example, aluminum always injects negative space charge, while stainless steel generally injects positive charge but under some conditions has injected negative charge [1].
Modern pulse power machines commonly use deionized water in intermediate energy storage capacitors. Recent work has shown that charge injection phenomena can play an important role in determining the limits of perform...
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Modern pulse power machines commonly use deionized water in intermediate energy storage capacitors. Recent work has shown that charge injection phenomena can play an important role in determining the limits of performance of the dielectric [1]. For unipolar conduction, this anomalous behavior was shown to be due to injected charge that increases the effective ohmic conductivity σ to σ+qμ, where q was the time and space dependent charge density with mobility μ of the single charge carrier.
This paper is aimed at outlining a framework for analyzing local, oscillatory, electromechanical instabilities in electrical machines operating at nominally constant average speed. For Park-transformable machines in n...
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This paper is aimed at outlining a framework for analyzing local, oscillatory, electromechanical instabilities in electrical machines operating at nominally constant average speed. For Park-transformable machines in nominal constant-speed operation, the linearized models that predict the local behavior of interest are time invariant, as is well known. In this case, the contribution of this paper is to show that the behavior may be qualitatively and quantitatively analyzed in an illuminating manner via systematically obtained reduced-order models. The procedure is illustrated for the case of a permanent-magnet stepping motor, expanding an earlier study of this motor in the literature. For the more general case where the linearized models that govern local behavior are periodically varying, this paper briefly summarizes the key ideas of classical Floquet theory, which provides the tools needed for analysis in this general case.
We explore the fusion of expert control system analysis and design tools into a prototype computer environment. The use of expert systems technology allows the transfer of recent developments in control system design ...
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We explore the fusion of expert control system analysis and design tools into a prototype computer environment. The use of expert systems technology allows the transfer of recent developments in control system design to users who may not be experts in either theoretical developments or computer technology, in a vehicle which provides considerable design flexibility. The technology does not provide as general a framework as, for example, a command language based environment; however, in specific applications, such as system modeling and linear control systems, it is useful and appropriate. Criteria for such applications is that they have a mature theoretical basis, and that the user interaction influence the sequence of the design process.
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