Recursive calculation of ladder circuit frequency functions

It is shown how the transfer function as well as the input impedance and admittance of any linear time-invariant ladder circuit can be determined in closed form as frequency functions dependent upon the network element parameters. All elements of the ladder circuit must be explicitly specified by their frequency characteristics. The results are achieved with the aid of recursive algorithms. The outcome is demonstrated by means of an example.     

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.     

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.

     

Canonical piecewise-linear networks

In this paper, mapping networks will be considered from the viewpoint of the piecewise-linear (PWL) approximation. The so-called canonical representation plays a kernel role in the PWL representation theory. While this theory has been researched intensively in the contents of mathematics and circuit simulations, little has been seen in the research area about the theoretical aspect of neural networks. This paper modifies this theory and applies it as a mathematical support for mapping networks. The main modification is a "higher-level" generalization of the canonical representation with proofs of its availability in the set of PWL functions. The modified theory will first be used to study the canonical PWL feature of the popular multilayer perceptron-like (MLPL) networks. Second, it will be seen that the generalized canonical representation is itself suitable for a network implementation, which is called the standard canonical PWL network. More generally, the family of (generalized) canonical PWL networks is defined as those which may take the canonical PWL representation as a mathematical model. This family is large and practically meaningful. The standard canonical PWL networks may be taken as representatives in the family. The modification of the PWL representation theory as well as the introduction of this theory in the theoretical study of mapping networks, which provide a new concept of mapping networks, i.e., the canonical PWL network family, may be regarded as the main contributions of the paper.     

The reduction of fire and explosion risks in a cuboidal tank making use of a system of vertical grounding rods

Contents The paper presents calculation results of the electric field in a cuboidal tank provided with a system of vertical grounding rods.The calculations made in the paper indicate that even at a relatively small space-charge density (q=100 C/m³), the values of the field intensity and electric potential are very large and may cause a spark discharge. The presented mathematical model and the results of field calculations can be applied to the reduction of fire and explosion risks in parallelepiped tanks storing inflammable liquids.

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Die Verminderung des Feuer- und Explosionsrisikos in kubischen Behältern mit einem System von vertikalen geerdeten Stäben

Übersicht Der Beitrag behandelt elektrische Felder in kubischen Behältern mit einem System von vertikalen geerdeten Stäben.Die Berechnungen zeigen, daß selbst bei relativ kelinen Werten der Raumladungsdichte (q=100 C/m³) die elektrische Feldstärke und das elektrische Potential sehr groß sind und einen Durchschlag verursachen können. Das dargestellte mathematische Modell und die Rechenergebnisse lassen sich als eine Methode verwenden für die Reduzierung des Feuer- und Explosionsrisikos in Behältern von der Form eines Parallelepipeds zur Speicherung leicht brennbarer Flüssigkeiten.

     

Bücherschau

Ohne Zusammenfassung     

Approximate Feedback Linearisation Using Multilayer Neural Networks

In this paper we introduce the approximate feedback linearisation using multilayer feedforward neural networks. We propose to approximate a basis of the one-dimensional codistribution of an affine nonlinear system with the derivative of a multilayer neural network [6] and form a change of coordinates with n multilayer neural networks [5]. In this paper we will prove that the transformation can define a local diffeomorphism, with which a local stabilising feedback law can be designed for a kind of non-linearisable nonlinear systems.     

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.     

Novel switched-capacitor generalised integrator

A novel circuit arrangement is proposed for a generalised integrator using the switched-capacitor (SC) technique. This generalised integrator (which integrates with respect to a dependent variable) can easily be constructed in IC form using MOS technology. It possesses some attractive features, for instance simplicity and low cost. It can find applications in many analogue systems such as curve-fitting devices, adaptive filters, RMS convertors etc.