A new general equivalence transformation for mixed lumped and nonuniform distributed networks with synthesis applications

Contents A new general equivalence transformation for cascades of lossless nonuniform transmission lines (NTL's) and lumped reactance two-ports (LRT's) is presented. Based on this transformation a new synthesis method for NTL's and NTL-LRT cascades is established, by means of which microwave filters and matching sections can be constructed on the basis of a rational function of the complex frequency. Thus, given specifications can practically be met arbitrarily well. In contrast to others the new method is at the same time exact and easy to handle. A synthesis example is given at the end.

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Eine neue allgemeine Äquivalenztransformation für gemischt-kon-zentriert-ungleichförmig-verteilte Netzwerke mit Syntheseanwendungen

Übersicht Es wird eine neue allgemeine Äquivalenztrans-formation für Kettenschaltungen aus (verlustlosen inhomogenen) Leitungen und (konzentrierten) Reaktanzzweitoren vorgestellt. Auf der Grundlage dieser Transformation wird ein neues Syntheseverfahren für Leitungen und Leitungs-Reaktanzzweitor-Kettenschaltungen begründet, mit Hilfe dessen Mikrowellenfilter und-anpassungsglieder auf der Grundlage einer rationalen Funktion der komplexen Frequenz konstruiert werden können. Somit können vorgegebene Spezifikationen praktisch beliebig genau realisiert werden. Im Gegensatz zu anderen ist das neue Verfahren gleichzeitig exakt und leicht zu handhaben. Am Schluß ist ein Synthesebeispiel angegeben.

     

Bücherschau

Ohne Zusammenfassung     

Implementation of 2-D pseudo-rotated digital filters using a forward lattice structure

The 1-D FDLS shows the localized feedback property and is suitable for modular and concurrent implementation. It is known that the 1-D FDLS shows interesting properties with respect to finite word-length effects. In this paper, a new result is given for the estimation of the lower and upper bound of the variance of the roundoff noise. It is presented how the FDLS can be incorporated to implement 2-D pseudo-rotated digital filters. The 1-D roundoff noise analysis is extended to the 2-D case. It is indicated how 2-D filter banks can be derived from the FDLS.     

Novel and efficient realizations of FIR digital filters

An FIR filter can usually be realized in the direct form or in cascade form. The Chebyshev-type structures, known for the 2-D FIR filter implementation, are generalized to the realization of arbitrary 1-D causal FIR filters. The new realizations show several attractive properties and can be implemented using modular pipelineable processor arrays     

Realization of 2-D denominator-separable digital filter transfer functions using complex arithmetic

In this paper the problem of realizing 2-D denominator-separable digital filter transfer functions is considered for processing of real sequences. The approach is based on expressing the given 2-D transfer function as a sum of two reduced-order rational transfer functions with complex coefficients. New structures are obtained for equivalent reduced-order, complex-coefficient, 2-D transfer functions. All the realizations are basically parallelform structures with minimum-norm, low round-off noise and freedom from overflow limit cycles. A comparison of the different structures is also made.     

Evaluation of the quantization error in denominator-separable 2-Drecursive filters

The evaluation of the quantization error in two-dimensional (2-D) digital filters involves the computation of the infinite square sum J=Σ^∞_m=φΣ ^∞_n=φy² (m, n). A simple method is presented for evaluating J based on partial fraction expansion and using the residue method provided the Z-transform Y(Z₁, Z₂) of the sequence y(m, n) having quadrant support is a causal bounded input, bounded output (BIBO) stable denominator-separable rational function. The value of J is expressed as a sum of simple integrals which can easily be evaluated. The simple integrals are tabulated for ready reference. The proposed method is suitable for analytical as well as numerical computation and can easily be programmed     

On the computational model of a kind of deconvolution problem

It is known that discretization of a continuous deconvolution problem can alleviate the ill-posedness of the problem. The currently used circulant matrix model, however, does not play such a role. Moreover, the approximation of deconvolution problems by circulant matrix model is rational only if the size of the kernel function is very small. We propose an aperiodic model of deconvolution. For discrete and finite deconvolution problems the new model is an exact one. In the general case, the new model can lead to a nonsingular system of equations that has a lower condition number than the circulant one, and the related computations in the deconvolution can be done efficiently by means of the DFT technique, as in the ease for circulant matrices. The rationality of the new model holds without regard to the size of the kernel and the image. The use of the aperiodic model is illustrated by gradient-based algorithms.     

Field approach to the three-dimensional boundary integral formulation

This paper addresses the problem of time-harmonic electromagnetic three-dimensional scattering in dissipative or dielectric media. A field approach to the well-known boundary integral formulation is derived from a general identity between two distinct electromagnetic states. The complete linear system of equations so obtained is overdetermined. A simple analysis of the regularity properties of the subsystems involved is shown.     

Regularization-based output-trajectory preshaping of a high-speed flexible beam against ill-conditioned stable inversion

In this paper we consider the problem of mitigating actuator high-frequency saturation due to ill-conditioned stable inversion for exact output tracking control of a high-speed flexible beam. For this purpose, the regularization-based frequency shaping approach is used to preshape the reference output-trajectory so that the calculated torque through stable inversion is smooth enough without high-frequency saturation. The output-trajectory preshaping task is formulated by the regularized output least square problem, from which a regularization-based preshaping filter is well-defined explicitly. To make the regularization-based preshaping approach viable, the practical implementation of a regularization-based preshaping filter, including the specification of the stabilizing functional and the choice of the regularization parameter, is discussed analytically. The time-domain computation for an output-trajectory preshaping task is also addressed. Numerical simulation studies are presented to assess the validity of the method proposed in this paper.     

Nonlinear observers for a class of continuous-time uncertain state delayed systems

This paper is concerned with the problem of observer design for a class of time-delay nonlinear systems with parameter uncertainties. The purpose of this problem is to design the gain-scheduled state observers such that, for the addressed nonlinearities as well as all admissible parameter uncertainties in state and output equations, the observation process remains globally exponentially stable, independently of the time delay. The nonlinearities are assumed to satisfy the global L ipschitz conditions, and the parameter uncertainties are allowed to be time varying, unstructured and norm bounded. An effective matrix inequality methodology is developed to solve the proposed problem. W e derive the conditions for the existence of the desired robust nonlinear observers, and then characterize the analytical expression of these observers. Two numerical examples demonstrate the validity and applicability of the present approach.