The authors investigate Smith-Purcell radiation due to a relativistic sheet-electron beam propagating parallel to a reflection grating composed of sinusoidally corrugated conducting surface. A self-consistent analysis...
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The authors investigate Smith-Purcell radiation due to a relativistic sheet-electron beam propagating parallel to a reflection grating composed of sinusoidally corrugated conducting surface. A self-consistent analysis of the method and instability is developed using the mode-matching method. The precise numerical results for the dispersion relation of eigenmodes supported by the two-dimensional system are presented over the frequency range from the spontaneous emission regime to the stimulated emission regime.< >
An on-line scheme to fault detection in adaptive control systems is proposed by introducing Kullbaek Discrimination Information (KDI) as a detection index. When a physical parameter change due to a failure has occurre...
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An on-line scheme to fault detection in adaptive control systems is proposed by introducing Kullbaek Discrimination Information (KDI) as a detection index. When a physical parameter change due to a failure has occurred in a system under adaptive control, the failure effect will hardly be visible in the output performance because of the adaptation mechanism. Such a parameter change is also difficult to detect by monitoring the regulator parameters, which are determined by a recursive identification based on the direct approach. Since the failure effect is reflected as a change in the predictor model used for the adaptive control design, the fault detection leads to a model discrimination problem. It has been shown that the KDI can be used as an effective distortion measure for the model discrimination and the index can be applied in a modified form to detect a fault on-line. Simulation studies on a second order damped oscillatory system have been carried out to demonstrate the efficiency of the method.
The paper presents performance results for the SHINPADS serial data bus operating in the environment of a modern, frigate-class ship using a combination of point-to-point links for certain major applications systems a...
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The paper presents performance results for the SHINPADS serial data bus operating in the environment of a modern, frigate-class ship using a combination of point-to-point links for certain major applications systems and the shared, SHINPADS bus for others. The traffic model used is representative of experience in the design of new ships of this type. It is shown that the bus has adequate performance for the expected traffic load. In addition it is shown that, as traffic increases, delay problems will show up in the application processor environment before there is any significant degradation of the performance of the bus. The value of the provision of several classes of priority on the bus is also investigated.
The scattering of a beam mode by a circular conducting cylinder coated with an axially magnetized ferrite is considered. A complex-source-point method introduced by Deschamps and developed by Felsen and his collaborat...
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The scattering of a beam mode by a circular conducting cylinder coated with an axially magnetized ferrite is considered. A complex-source-point method introduced by Deschamps and developed by Felsen and his collaborators is used. Numerical results are presented for the scattering patterns of a lowest-order mode by a conducting circular cylinder covered with an unmagnetized ferrite. The effects of the spot size and the location of the waist of the beam on the scattered field are discussed. A comparison between the scattering of a beam mode and that of a plane wave is presented. The scattering patterns for a magnetized ferrite-coated conducting cylinder are also calculated and compared with those for an unmagnetized ferrite coating. Finally we calculate the scattering patterns in the resonance region of a magnetized ferrite.
The problem of wave guidance in thin-film dielectric waveguides is formulated using the mode-matching method in the sense of least squares. The result is applied to analysis of the first-order Bragg interactions in a ...
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The problem of wave guidance in thin-film dielectric waveguides is formulated using the mode-matching method in the sense of least squares. The result is applied to analysis of the first-order Bragg interactions in a three-layered dielectric waveguide having a sinusoidal surface corrugation. The precise numerical results of the dispersion relation near the first-order stopband are presented for both of the lowest TE and TM modes and compared with those obtained by a conventional perturbation approximation.
The reflection of electromagnetic plane waves incident obliquely upon a semibounded, maxwellian plasma is investigated based on the kinetic theory. The perturbed velocity distribution function is assumed to satisfy th...
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The reflection of electromagnetic plane waves incident obliquely upon a semibounded, maxwellian plasma is investigated based on the kinetic theory. The perturbed velocity distribution function is assumed to satisfy the boundary condition of a diffuse scattering at the surface of the plasma. The numerical results of the reflection coefficients are presented for both cases of incidence of TM and TE waves. It is shown that as the temperature of plasma increases, the reflected energy from the diffuse scattering boundary is significantly reduced, especially within the frequency range of usual total reflection. This phenomenon is discussed at some length and is brought out to be closely related to a collisionless energy absorption by the surface charges which couple resonantly to the incident wave.
When a Gaussian wave beam propagates through an inhomogeneous random medium where the intensity and scale size of turbulence vary as functions of propagation distance, the coherence function is expressed in a compact ...
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When a Gaussian wave beam propagates through an inhomogeneous random medium where the intensity and scale size of turbulence vary as functions of propagation distance, the coherence function is expressed in a compact form. It agrees entirely with the exact coherence functions for plane and spherical waves in the limiting cases where the minimum spot size of the wave beam tends to infinity and zero. Some expressions presented here are useful for many practical applications of the coherence function.
The characteristics of a three‐mode coupling in a dielectric slab waveguide attached doubly periodic surface corrugations are investigated. The coupled‐mode equations governing the first‐order Bragg interactions of...
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The characteristics of a three‐mode coupling in a dielectric slab waveguide attached doubly periodic surface corrugations are investigated. The coupled‐mode equations governing the first‐order Bragg interactions of three TE modes are systematically derived with the help of perturbation procedure. For the case where the waveguide is symmetric and the three TE modes are lowest even modes, the coupled‐mode equations are solved to obtain the reflection and transmission characteristics of the periodic waveguide of finite length. The results are compared with those of the two related two‐mode couplings in a dielectric slab waveguide with a singly periodic surface corrugation.
Consider a collection of disjoint polygons in the plane containing a total of n edges. We show how to build, in O(n2) time and space, a data structure from which in O(n) time we can compute the visibility polygon of a...
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Consider a collection of disjoint polygons in the plane containing a total of n edges. We show how to build, in O(n2) time and space, a data structure from which in O(n) time we can compute the visibility polygon of a given point with respect to the polygon collection. As an application of this structure, the visibility graph of the given polygons can be constructed in O(n2) time and space. This implies that the shortest path that connects two points in the plane and avoids the polygons in our collection can be computed in O(n2) time, improving earlier O(n2 log n) results.
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