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  • 101
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 269-290 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The controllability and observability properties of a singular system are extensively studied. The definitions of controllability,R-controllability, and impulse controllability are introduced via characteristics of the original state vector. Analogous definitions are presented for the case of observability. The criteria established for controllability and observability are simple rank criteria related to the Markov parameters from the inputs to the states and from the initial conditions to the outputs, respectively. The present results can be considered as the direct extension of Kalman's controllability and observability criteria to the case of singular systems. Finally, the controllability and observability subspaces are derived from the image and the kernel of the controllability and the observability matrices, respectively.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 431-442 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Given a stationary time seriesX and another stationary time seriesY (with a different power spectral density), we describe an algorithm for constructing a stationary time series Z that contains exactly the same values asX permuted in an order such that the power spectral density ofZ closely resembles that ofY. We call this methodspectral mimicry. We prove (under certain restrictions) that, if the univariate cumulative distribution function (CDF) ofX is identical to the CDF ofY, then the power spectral density ofZ equals the power spectral density ofY. We also show, for a class of examples, that when the CDFs ofX andY differ modestly, the power spectral density ofZ closely approximates the power spectral density ofY. The algorithm, developed to design an experiment in microbial population dynamics, has a variety of other applications.
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  • 103
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 479-487 
    ISSN: 1531-5878
    Schlagwort(e): Cramér-Rao bounds ; direction-of-arrival estimation ; unknown noise
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The deterministic and stochastic direction estimation Cramér-Rao bounds (CRBs) are studied in the presence of one signal and spatially uncorrelated sensor noise with unknown nonequal variances in array sensors. The explicit CRB expressions are obtained, and their relationship is studied showing some typical properties inherent in the nonidentical noise case.
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  • 104
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 457-477 
    ISSN: 1531-5878
    Schlagwort(e): Nonlinear circuit theory ; co-content ; functional minimization ; image processing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The solutions of many physical-mathematical problems can be obtained by minimizing proper functionals. In the literature, some methods for the synthesis of analog circuits (mainly cellular neural networks) are presented that find the solution of some of these problems by implementing the discretized Euler-Lagrange equations associated with the pertinent functionals. In this paper, we propose a method for defining analog circuits that directly minimize (in a parallel way) a class of discretized functionals in the frequently occurring case where the solution depends on two spatial variables. The method is a generalization of the one presented in Parodi et al.,Internat. J. Circuit Theory Appl., 26, 477–498, 1998. The analog circuits consist of both a (nonlinear) resistive part and a set of linear capacitors, whose steady-state voltages represent the discrete solution to the problem. The method is based on the potential (co-content) functions associated with voltage-controlled resistive elements. es an example, we describe an application in the field of image processing: the restoration of color images corrupted by additive noise.
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  • 105
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 14 (1995), S. 669-674 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The stochastic likelihood function [(STO)LF] associated with the narrowband signal processing problem can be concentrated with respect to the signal covariance matrix elements and the noise power. Although this is a known fact, no clear-cut derivation of the concentrated (STO)LF appears to be available in the literature. In this short paper we provide a simple, complete proof of the concentrated (STO)LF formula.
    Materialart: Digitale Medien
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  • 106
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 14 (1995), S. 725-734 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We give bounds on the self-sustained limit cycles in fixed-poin implementations of state-variable-form digital filters having general stable system matrices. These bounds, which are period independent and which concern limit cycles due to quantization errors in physical realizations of digital filters, are given in closed form for second-order sections. A numerical comparison shows that the bounds are smaller than corresponding ones reported in the literature. This is due to our use of real similarity transformations.
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  • 107
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 14 (1995), S. 787-815 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We consider the concept reachability for Polynomial Matrix Descriptions (PMDs); i.e., systems of the form ∑: A(ρ)β(t)=B(ρ)u(t),y(t)=C(ρ)β(t), whereρ:=d/dt the differential operator,A(ρ)=A0+A1 ρ+...+ Av ρ v εR r×r[ρ], AiεR r×r,i=0, 1,..., ν ≥ 1 with rank R A v ≤r B(ρ) =B 0+B 1ρ+...+B σρσ εR r×m[ρ], Bi εR r×m,i=0,1,...,σ ≥ 0 C(ρ)=C0+C1 ρ+...+Cσ1 ρ σ1 εR m1×r[ρ],C i εR m1×r ,i=0, 1,..., σ1 ≥ 0, β(t): (0−, ∞) →R r is the pseudostate of (∑),u(t): [0, ∞) →R m is the control input to (∑), and y(t) is the output of the system (∑). Starting from the fact that generalized state space systems, i.e., systems of the form ∑1: Ex(t)=Ax(t)+ Bu(t), y(t)=Cx(t), whereE εR r×r, rank R E 〈r, A εR r×r,B εR r×m,C εR m1×r represent a particular case of PMDs, we generalize various known results regarding the smooth and impulsive solutions of the homogeneous and the nonhomogeneous system (∑1) to the more general case of PMDs (∑). Relying on the above generalizations we develop a theory regarding the reachability of PMDs using time-domain analysis, which takes into account finite and infinite zeros of the matrix A(s)=L.[A(ρ)]. The present analysis extends in a general way many results previously known only for regular and generalized state space systems.
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  • 108
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 15 (1996), S. 137-144 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper presents an approach to estimate the directions-of-arrival (DOAs) of narrowband coherent (completely corrected) signals by an arbitrary geometry sensor array. The concept of focussing matrices is introduced to estimate the outputs of a virtual uniform linear array from the outputs of the real array in order to use spatial smoothing techniques. Unlike the work presented in [5], the proposed approach avoids multiple singular value decomposition (SVD) computations in the various sectors because it is not necessary to divide the field of view of the array into sectors. Simulation results are given to support the approach.
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  • 109
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 15 (1996), S. 213-231 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract An optimal deconvolution filter design method is proposed in this paper for signal transmission systems with small perturbation of parameters. The perturbative parameters of the transmission channel and noise model are of probabilistic structures. A realizable filter is derived to minimize the mean square estimation error from the viewpoint of frequency domain. The calculus of variation technique and the spectral factorization method are used in the design procedure. The design method is suitable for the deconvolution of both minimum-phase and nonminimum-phase perturbative transmission systems. The minimum mean square error of the optimal deconvolution filter is also discussed. Finally, an example is given to illustrate the simulation results of the proposed optimal deconvolution filter.
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  • 110
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 15 (1996), S. 291-311 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper we present a simple and practical algorithm for the estimation of uncertain parameters of linear systems. The uncertainty is twofold, involving random observation noise, and possible jumps in the parameter values. The jumps may occur at unknown points in time, and are of unknown magnitudes and directions. The algorithm is based on the Kalman filter, with a single-sample hypothesis test, which is used to employ a three-state decision rule (yes, no, maybe). The “maybe” choice invokes a fading memory Kalman filter. The overall algorithm contains the constant parameter filter, fading memory filter, and the set of tests and rules that enable it to switch back and forth between the two filters. Application examples are presented.
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  • 111
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 15 (1996), S. 361-376 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A novel approach that employs ordered binary decision diagrams (OBDDs) is contributed to factorize multi-level logic functions by requiring as few literals as possible. A logic function with PLA format is represented as an OBDD form first. A heuristic decision method of variable ordering, called theorder lookahead method, is derived for the construction of OBDDs. This method is based on the constant cofactor and the number of erasable logic terms for each input variable. The total execution time of the OBDD construction by the above ordering decisions is very fast for some MCNC benchmarks. With the above OBDDs, we introduce a simple yet effective graph manipulation, calledEXT, to obtain a minimal number of literals in the Boolean function. This greedyEXT algorithm consists mainly of two phases. The first phase, calledgraph analysis, identifies the similarities between nodes on the same level in the OBDD. The second phase, calledtree analysis, utilizes the above features to extract the common parts of the nodes. TheEXT procedure runs from the bottom level up to the top level of the OBDD. The computational complexity depends on the number of nodes in the OBDD. The results of simulations show thatEXT has a very fast CPU execution time and a competitive literal ratio with other methods for some MCNC benchmarks.EXT will produce the smallest literal number, especially for structured or symmetric circuits.
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  • 112
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 15 (1996), S. 467-480 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this study we explore the use of nonlinear embedding maps to expand the dimension of the input space. The efficacy of such maps to speed training and to enhance performance is illustrated through several examples. A natural connection to nonlinear synaptic interconnects is also developed.
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  • 113
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 14 (1995), S. 445-463 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper proposes a scaling and squaring geometric series method along with the inverse-geometric series method for finding discrete-time (continuous-time) structured uncertain linear models from continuous-time (discrete-time) structured uncertain linear systems. The above methods allow the use of well-developed theorems and algorithms in the discrete-time (continuous-time) domain to indirectly solve the continuous-time (discretetime) domain problems. Moreover, these methods enhance the flexibility in modeling and control of a hybrid composite system. It has been shown that the commonly used bilinear approximation model is a specific class of the proposed geometric series model.
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  • 114
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 14 (1995), S. 525-538 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Of concern is the undistorted propagation of pulse stress waves in long thin bodies. The primary signals are arbitrarily sharp pulses projected along thex-axis. It will be seen that these pulses travel close to the speed of sound in unbounded media. Secondary pulses follow representing interactive disturbances traveling along they-axis. But the process brings out certain anomalies in circuit realizability requirements. These issues, transmission parameters, and coupling between the various signals are studied in detail. The results are supported by experiments.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 15 (1996), S. 313-333 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We construct a general model of a nonlinear input-output system consisting of finitely many blocks whose variables are in extended spaces. This model encompasses all configurations used in control which have several feedback and feedforward loops. We show that such a system is essentially the traditional MI-MO feedback system. Moreover, assuming that one block of the system is a plant affected by perturbations, we derive conditions guaranteeing linear insensitivity and/or robust stability of the whole system. In particular, we consider systems whose variables are continuous, vector-valued functions on [0, ∞), and whose blocks are described by nonlinear Volterra operators. The applications of the results are illustrated by several examples of feedback-feedforward systems.
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  • 116
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 16 (1997), S. 611-624 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Feedback control designs are useful for removing the impulses that disturb the behavior of generalized state space systems. The aim of this paper is to detail the design of dynamic precompensators for the implementation of such feedback control designs. Necessary and sufficient conditions are given so that the resulting regulators are biproper. It is pointed out that these conditions are restrictive and that feedback control designs can lead to nonproper precompensators. To overcome this difficulty, a class of proper precompensators is proposed. These regulators, which result from an adaptation of the Silverman structure algorithm, remove the impulse behaviors that occur after the initial time by smoothing out the input vector.
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  • 117
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 16 (1997), S. 595-610 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper investigates the factorization properties of cyclotomic polynomials over the field of complex rational numbers. Based on this factorization and the Chinese remainder theorem, we analyze the mathematical structure of the associated algorithms for computing the cyclic convolution of data sequences. The relevant results pertaining to finite integer and complex integer rings are also summarized.Note: This work is being reported in two parts. In Part I, we analyze the structure of the cyclic convolution algorithms over the rational number system. In Part II, we describe complex cyclotomic polynomials and the structure of the resulting cyclic convolution algorithms over the complex rational number system.
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  • 118
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 16 (1997), S. 569-594 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The Chinese remainder theorem plays a central role in the design of fast algorithms for computing cyclic and acyclic convolution of data sequences. A mathematical analysis of the theorem and related aspects form the topic of this investigation. The focus is almost exclusively on cyclic convolution algorithms. The number system that is studied is the field of rational numbers. Several properties related to the mathematical structure of the algorithms are derived.Note: This work is being reported in two parts. In Part I, we analyze the structure of the cyclic convolution algorithms over the rational number system. In Part II, we describe complex cyclotomic polynomials and the structure of the resulting cyclic convolution algorithms over the complex rational number system.
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  • 119
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 335-360 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper, we present an improved-tableau polynomial matrix description for analyzing the dynamics of very large scale integrated circuits (VLSIs) and we compare the results with those proposed by Desoer and Gündes. Using this method in conjunction with fractional perturbations and the polynomial left coprime factorization technique, we study the exponential stability of a nominal VLSI and the associated perturbed VLSI, which may be regarded as an interconnected network or multiport, and we present necessary and sufficient conditions for robust exponential stability of the perturbed VLSI in two different ways. Some of these results are similar to those developed by Desoer and Gündes but are given in a much simpler form. Others are extensions of or dual to those given in the literature.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 401-419 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A hybrid control system is proposed for regulating an unknown nonlinear plant. The interface between the continuous-state plant and the discrete-event supervisor is designed using a fuzzy logic approach. The fuzzy logic interface partitions the continuous-state space into a finite number of regions. In each region, the original unknown nonlinear plant is approximated by a fuzzy logic-based linear model, then state-feedback controllers are designed for each linear model. A high-level supervisor coordinates (mode switching) the set of closed-loop systems in a stable and safe manner. The stability of the system is studied using nonsmooth Lyapunov functions. For illustration and verification purposes, this technique has been applied to the well-known inverted pendulum balancing problem.
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  • 121
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 449-457 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract For many problems in classification, compensation, adaptivity, identification, and signal processing, results concerning the representation and approximation of nonlinear functions can be of particular interest to engineers. Here we consider a large class of functionsf that map ℝ n into the set of real or complex numbers, and we give bounds on the number of parameters of a certain approximation network so thatf can be approximated to within a prescribed degree of accuracy using an appropriate configuration of the network. We also describe related work in the neural networks literature.
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  • 122
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 575-589 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A discrete chaotic process passed through a linear filter can behave like a stochastic, 1/f process. A stochastic description for 1/f processes is shown to be convenient where high-dimensional nonlinear systems are involved. Linear filtering can hide simple nonlinear, chaotic deterministic dynamics, and a method is presented for recovering these dynamics.
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  • 123
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 637-652 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The problem of defining denumerable Markov chains by a countable infinity of weighted directed cycles is solved by using suitable Banach spacesl p on cycles and edges. Furthermore, it is showed that the transition probabilities of such chains may be described by Fourier series on orthonormal collections of homologic ingredients.
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  • 124
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 653-665 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We consider a large family of approximately-finite-memory causal time-invariant mapsG from an input setS to a set of ℝ-valued functions, with the members of both sets of functions defined on the nonnegative integers, and we give an upper bound on the error in approximating aG using a two-stage structure consisting of a tapped delay line followed by a static neural network. As an application, information is given concerning the long-standing problem of determining the order of a Volterra-series approximation so that a given quality of approximation can be achieved. We also give corresponding results for the approximation of not necessarily causal input-output maps with inputs and outputs that may depend on more than one variable. These results are of interest, for example, in connection with image processing.
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  • 125
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. i 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
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  • 126
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 111-130 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The cumulants defined in terms of moments are basic to the study of higher-order statistics (HOS) of a stationary stochastic process. This paper presents a concurrent systolic array system for the computation of higher-order moments. The system allows for the simultaneous computation of the second-, third-, and fourth-order moments. The architecture achieves good speedup through its excellent exploitation of parallelism, pipelining, and reusability of some intermediate results. The computational complexity and system performance issues related to the architecture are discussed. The concurrent system is designed with the CMOS VLSI technology and is capable of operating at 3.9 MHz.
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  • 127
    Digitale Medien
    Digitale Medien
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    Circuits, systems and signal processing 18 (1999), S. 183-187 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Necessary and sufficient conditions for the invertibility of a (not necessarily linear) operatorN between normed linear spaces are given. It is shown thatN is invertible precisely if a certain operator associated withN is a contraction.
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  • 128
    Digitale Medien
    Digitale Medien
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    Circuits, systems and signal processing 16 (1997), S. 655-661 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In the stability and sensitivity theory of general, nonlinear input-output systems we encounter a certain inequality concerning solely the nominal system that plays a central role in the whole theory. In particular, this “central inequality,” combined with other assumptions, implies (a) stability of the nominal system, (b) robustness, and (c) insensitivity of the input-output system. This paper presents conditions equivalent to this central inequality, and a further result on the stability-robustness problem.
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  • 129
    Digitale Medien
    Digitale Medien
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    Circuits, systems and signal processing 17 (1998), S. I 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
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  • 130
    Digitale Medien
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    Circuits, systems and signal processing 16 (1997), S. 703-718 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Discrete-time linear periodic single-input/single-output (SISO) systems having uniform relative degree are considered. A closed-form expression of the blocking input is derived and exploited to obtain a computationally advantageous characterization of the structural zeros. Indeed, it suffices to compute the eigenvalues of a suitably defined (n × n) matrix, wheren is the system order. It is shown that, in contrast to the general case studied in previous papers, the number of zeros of linear periodic SISO systems with uniform relative degree is always time invariant and equal to the difference between the system order and the relative degree. The new characterization is also used to provide a simple expression for the zeros of linear periodic systems described by input-output difference equations.
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  • 131
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    Circuits, systems and signal processing 17 (1998), S. 103-116 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A synthesis algorithm for a pipelined lattice implementation of cochlea-like digital filters is presented, based upon the properties of real, lossless lattice synthesis of ARMA filters. The algorithm operates on a simplified characterization of elementary lattice sections of degree one or degree two. This leads to a structure that is recursively designed and for which each lattice is precisely implemented by a pair of complex conjugate transmission zeros via Richard's function extractions. Except for zeros of transmission on the unit circle, all other types and multiplicities are allowed. Necessary and sufficient conditions are derived for the degree-two lattices to guarantee computability, i.e., realizability with no delay-free loops. In addition to being suitable for VLSI realization, the structure enables a systematic cochlea assessment from the scattering ear parameters.
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  • 132
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    Circuits, systems and signal processing 14 (1995), S. 187-211 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper investigates circuit Markov processes under the standpoint of duality principle.
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  • 133
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    Circuits, systems and signal processing 14 (1995), S. 237-254 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper, a high resolution technique for estimating DOAs of spatially close source signals is presented. It is observed that the array manifold over a sector of interest is rank deficient and the dimension of the array manifold space, which is the range space of the array manifold, is less than the number of sensors in the array. The true signal subspace is a subspace in the array manifold space. A novel technique is provided that searches for the signal subspace in this array manifold space. The resulting estimated signal subspace has minimum principal angles with the data signal subspace generated by eigen-decomposing the covariance matrix of the array data vector. It is proved that the proposed estimator is asymptotically consistent and the estimated signal subspace is closer to the true signal subspace than the data signal subspace formed by MUSIC. The proposed novel technique has better performance than the MUSIC algorithm. Its performance is comparable to MLE and MD-MUSIC yet it requires only one-dimensional searches and is computationally much less intense. Simulation results are presented to show the effectiveness of the proposed technique, and comparisons with MUSIC, MLE, and MD-MUSIC algorithms are also included.
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  • 134
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    Circuits, systems and signal processing 14 (1995), S. 351-400 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract High-level synthesis is becoming increasingly important in the area of VLSI CAD. During the last decade, much research has been carried out in this area and some results have been achieved. This paper presents a survey on the state-of-the-art of current high-level synthesis research and applications. Besides basic knowledge, a comprehensive overview has been conducted among the various theories, methods, algorithms, and applications of the existing systems. Their advantages, limitations, and feasibilities are also described. Finally, some points on current status and future directions of high-level synthesis are addressed.
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  • 135
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    Circuits, systems and signal processing 14 (1995), S. 401-414 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper introduces the running kernels that yield recursive structures for time-frequency distributions (TFDs). The running kernels offer important properties not possessed by the commonly used block distribution kernels. The introduced kernels allow an invariance in computations with respect to the extent of the kernel in the time or the lag variable. However, contrary to the wide class of block kernels that satisfy the desired timefrequency (t-f) properties, most recursive (running) time-frequency distributions (RTFDs) violate the marginal and the support properties. This paper considers both the direct and the indirect types of recursion and presents examples for illustration.
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  • 136
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    Circuits, systems and signal processing 14 (1995), S. 465-472 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper the dual topics of robust signal detection and robust estimation of a random variable are considered, where the data may be both dependent and nonstationary. We note that classical saddlepoint techniques for robustness do not readily apply in the dependent and/or nonstationary situation, and thus our results have application in a larger domain than what was feasible heretofore. In addition, our methods make possible the quantitative measurement of robustness and admit essentially arbitrary perturbations in an underlying joint statistical distribution away from the nominal. In particular, our methods show that the presence of dependency can result in a reduction of the robustness of the linear detector by approximately 50% and that appropriate censoring can improve this situation. We also show that, somewhat surprisingly, a weak amount of censoring can actually reduce robustness rather than increase it, even with dependent data that is “almost” independent. This calls into question the common practice, inspired by classical saddlepoint results for independent data, of employing censoring in cases where residual dependency is conceded. When applied to estimation, our work shows that for nominally Gaussian data, the conditional expectation estimator is optimal not only in terms of performance but also robustness (under appropriate performance measures), thus reinforcing the appeal of this estimator. On the other hand, for other performance measures, we also note that the conditional expectation estimator can be completely unrobust, regardless of whether the data is nominally Gaussian or not. Finally, our results establish a bound on estimator robustness.
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  • 137
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    Circuits, systems and signal processing 17 (1998), S. 421-448 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The fundamentals of technology diffusion are introduced in this paper. Mathematical and heuristic (loose) modeling are defined and illustrated with real data. Starting with the embryonic phase, diffusion undergoes growing and mature phases and ends in the aging phase. The cumulative adoption function (of time) denoting the total number of users of a certain product is the output of the diffusion model used to either predict future trends (e.g. sales) or estimate certain model parameters. Problems often encountered in mathematical modeling and analysis are presented. Some of these shortcomings can be alleviated through loose modeling. A case study of mobile telephone diffusion in Finland is presented to illustrate some of the modeling principles and analysis.
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  • 138
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    Circuits, systems and signal processing 14 (1995), S. 707-724 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Selection of test nodes is an important phase of the fault dictionary approach. It is demonstrated in this paper that the techniques used for this purpose in other approaches of analog fault diagnosis like fault analysis and fault verification are not in general suitable for the fault dictionary approach. The ambiguity set is a simple and effective concept for choosing test nodes in the context of dictionaries. These sets are formed such that each faulty condition lies in only one ambiguity set. Deviating from this thinking, overlapping ambiguity sets are proposed in this paper, giving rise to a generalized fault dictionary. These sets use information more fully and hence reduce the number of test nodes. The concept of hashing is applied in this paper for selecting test nodes. This gives a linear time algorithm (linear in the number of fault voltage specificationsf′) and it isf′ times faster than the existing methods. It is not possible to select test nodes faster than this. This technique can also be used to select test nodes by the process of elimination of nodes. This is also linear inf′ per node elimination. Even a group of nodes can be eliminated or selected within the same computation. This freedom is not possible with the existing methods.
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  • 139
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    Circuits, systems and signal processing 14 (1995), S. 689-705 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A major reason for the success of linear autoregressive (AR) modeling is that Kolmogrorov proved that every linear system could be represented by a linear AR model of infinite order. The computation of a finite order AR approximation is, of course, the practical goal. In this paper, we prove that every nonlinear system with a Volterra series expansion can be represented as a nonlinear AR model of infinite order. Our method shows how an approximation to any desired order and degree can be achieved.
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  • 140
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    Circuits, systems and signal processing 15 (1996), S. 453-466 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The design of a constant resistance multiplexer composed of three reactance ladder networks connected either in series or in parallel is a very practical problem. In this paper, an improvement on Norton's method and a set of necessary and sufficient conditions on the realizability of a Butterworth or elliptic constant resistance multiplexer are presented. Two illustrative examples are given to show the design procedure.
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  • 141
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    Circuits, systems and signal processing 16 (1997), S. 271-285 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We define the smooth observability of nonlinear DAE systems and give sufficient conditions for this property to hold locally in a neighborhood of a solution. The matrix rank conditions for observability are verifiable by a combination of symbolic and numerical linear algebra computations. These conditions generalize conditions that have appeared in the literature for observability of linear time-varying DAE systems. We indicate how the main result is potentially useful in studying a system's zero dynamics. Some relevant rank properties of Hessenberg DAE systems are established.
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  • 142
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    Circuits, systems and signal processing 14 (1995), S. 213-236 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper presents an improved direct control architecture for the on-line learning control of dynamical systems using backpropagation neural networks. The proposed architecture is compared with the other direct control schemes. In this scheme the neural network interconnection strengths are updated based on the output error of the dynamical system directly, rather than using a transformed version of the error employed in other schemes. The ill effects of the controlled dynamics on the on-line updating of the network weights are moderated by including a compensating gain layer. An error feedback is introduced to improve the dynamic response of the control system. Simulation studies are performed using the nonlinear dynamics of an underwater vehicle and the promising results support the effectiveness of the proposed scheme.
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  • 143
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    Circuits, systems and signal processing 14 (1995), S. 299-316 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The analysis of initial value problems associated with singular linear dynamic systems using spectral methods is discussed. These methods, though extensively studied in the literature, can be very sensitive to numerical errors and to the presence of noisy input data. Moreover, using piecewise constant functions, like Walsh or Block-Pulse, spectral methods have been shown to be unstable with respect to incorrect initial conditions. In this paper regularization techniques are used to reduce arbitrarily the sensitivity of the spectral methods, and at the same time to stabilize them. Although the regularized spectral methods maintain the structure of the original algorithm, they can also be rewritten in recursive form, leading to the definition of a class of discrete time filters. Finally, some applicative numerical examples are discussed in order to show the effectiveness of the proposed algorithms.
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  • 144
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    Circuits, systems and signal processing 14 (1995), S. 415-425 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A complete solution is given to the problem of determining when a certain iteration will converge to the minimum of an important type of quadratic functional. It is shown that convergence occurs whenever the minimum exists, and that the iterates produced by the iteration will be unbounded for every starting point if the minimum does not exist. Applications are given concerning an adaptive filtering algorithm and nonharmonic series expansions.
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  • 145
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    Circuits, systems and signal processing 15 (1996), S. 1-22 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper presents a new interval Pade approximation method to convert a continuous-time (discrete-time) uncertain linear system to an equivalent discrete-time (continuous-time) uncertain model via interval arithmetic operations. Based on the inclusion theorem related to the interval arithmetic, the interval Pade's approximants and their associated interval error matrices with interval arguments are obtained via the Pade's approximants and their associated error matrices with degenerate (real) arguments, respectively. Tighter error bounds of various approximate uncertain models with respect to their exact uncertain models are determined and used to modify the obtained Pade's approximants, so that the resulting approximate uncertain models are able to tightly enclose the original uncertain systems. Thus, the analysis and design of the original uncertain systems can be indirectly carried out using the converted uncertain models in either the continuous-time or the discrete-time domain.
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  • 146
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    Circuits, systems and signal processing 15 (1996), S. 165-211 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Three new concepts — breakdown points, breakdown probabilities, and midpoint sensitivity curves — for stack filter analysis are introduced and analyzed in this paper. Breakdown points and probabilities can be used as measures of the robustness of stack filters. Midpoint sensitivity curves in turn give information on how sensitive the output of a stack filter is to the changes of a single value in the input window. The second major contribution of this paper is the extension of the current optimality theory of stack filters. This theory combines noise attenuation and different constraints on the filter's behavior. New constraints are introduced in this paper. A new optimization approach based on breakdown probability as a noise attenuation measure is also derived. In certain special cases it is shown that the optimal stack filter that achieves the best noise attenuation subject to given constraints can be obtained in closed form. An algorithm for finding this form is given in this paper, and its modification for finding a stack filter having (approximately) a required rank selection vector is presented.
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  • 147
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    Circuits, systems and signal processing 15 (1996), S. 275-290 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper considers the estimation of the parameters of a linear discrete-time system from noise-perturbed input and output measurements. The conditions imposed on the system are fairly general. In particular, the input and output noises are allowed to be auto-correlated and they may be cross-correlated as well. The proposed method makes use of an instrumental variable (IV)-vector to produce a covariance matrix that is pre- and postmultiplied by some prechosen weights. The singular vectors of the so-obtained matrix possess complete information on the system parameters. A weighted subspace fitting (WSF) method is then applied to the aforementioned singular vectors to consistently estimate the parameters of the system. The IV-WSF technique suggested herein is noniterative and easy to implement, and has a small computational burden. The asymptotic distribution of its estimation errors is derived and the result is used to motivate the choice of the weighting matrix in the WSF step and also to predict the estimation accuracy. Numerical examples are included to illustrate the performance achievable by the method.
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  • 148
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    Circuits, systems and signal processing 15 (1996), S. 649-669 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper considers a (J, J′)-spectral factorization of a signed spectral matrix associated with a discrete-time improper transfer matrix by using the descriptor system representation and the generalized algebraic Riccati equation (GARE). Under the assumption that the improper transfer matrix is stable, a numerical algorithm for (J, J′)-spectral factorization is developed based on solutions of the generalized eigenvalue problem (GEP) and a related matrix equation. For an unstable transfer matrix, aJ-unitary conjugation method is applied to obtain a stable transfer matrix generating the same signed spectral matrix. Then a Hankel norm model reduction problem is briefly discussed. A simple example is also included to illustrate the numerical procedure.
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  • 149
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    Circuits, systems and signal processing 15 (1996), S. 695-709 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract By means of norm,M-matrix, and matrix measure techniques, this paper estimates several restricted regions in the complex plane in which all eigenvalues of a class of discrete time-delay systems subjected to highly structured parametric perturbations are located. Both the stability and the instability conditions for these systems are also investigated via the proposed schemes. Two numerical examples are given to verify the correctness and demonstrate the applicability of the quantitative results.
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  • 150
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    Circuits, systems and signal processing 15 (1996), S. 749-762 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper, we discuss a unified approach and its simple algorithm for estimating and tracking the location of the desired talker in the far field and the near field by microphone arrays. The approach is unified for the far field and the near field and can enhance the effective power of the talker's signal. The simple algorithm further avoids singular-value decomposition (SVD) computations and is suitable for real-time processing. Computer simulations and experiments using actual array data support the techniques.
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  • 151
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    Circuits, systems and signal processing 16 (1997), S. 1-25 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Based on the combinatorial Routhα-β andγ-δ expansions of a stable transfer function, a new energy decomposition tree for linear systems is developed. The pertinent properties to the energy decomposition tree are investigated, and an algorithm is derived for synthesizing transfer functions from the tree. The synthesis process naturally leads to a new family of Routh approximants to the system. It is indicated that the selection of Routh approximants based on the values of impulse-response energy is often inadequate because there may be a number of different Routh approximants with the same order and the same impulse-response energy. In such cases, an additional performance criterion, such as the integral of squared error of impulse response or unit-step response, has to be used to select a suitable Routh approximant.
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  • 152
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    Circuits, systems and signal processing 16 (1997), S. 69-81 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract An adaptive generic algorithm was developed to solve the optimization problem of the maximum likelihood estimation of the sum of sinusoids in a noisy environment. The algorithm is based on genetic concepts and is extended, with modifications, to this problem. Simulation results were performed to see the effect of different parameters such as permutation and crossover probabilities. The effects of the signal-to-noise ratio (SNR) were also studied. It was found that the key factor for accuracy is the probabilities of permutation and crossover. Thus, we developed an adaptive method to estimate these probabilities, on line, to reduce the error. This was accomplished by considering them as unknown parameters to be estimated with the signal parameters. The mean square error of the frequency estimates was compared favorably to the Cramér-Rao lower bound. Several simulations are shown for SNR values ranging between −7 dB and 20 dB.
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  • 153
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    Circuits, systems and signal processing 16 (1997), S. 121-139 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In a recent work, the factorization properties of polynomials defined over finite integer polynomial rings were analyzed. These properties, along with other results pertaining to polymomial theory, led to the direct sum property and the American-Indian-Chinese extension of the Chinese remainder theorem over such integer rings. The objective of this paper is to describe algorithms for computing the one-and two-dimensional convolution of data sequences defined over finite integer rings. For one-dimensional convolution, algorithms for computing acyclic and cyclic convolution are described. For two-dimensional convolution, only the cyclic case is analyzed. Computational and other relevant aspects associated with the structure of these algorithms are also studied.
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  • 154
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    Circuits, systems and signal processing 16 (1997), S. 207-216 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract It is very important in many applications to preserve a desired signal without distortion. This paper presents a robust adaptive beamforming method to extract a desired signal from the signals received by broadband arrays. The proposed method relaxes the requirement of approximate knowledge of the desired direction and the sensor gains and delays (phases). Also the method enhances the desired signal based on a focusing transform for that signal, requires less computation than the taped-delay-line beamforming method, and provides good results even in a multipath environment. Computer simulations are given to support the proposed method.
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  • 155
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    Circuits, systems and signal processing 14 (1995), S. 587-602 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The least mean square (LMS) algorithm is investigated for stability when implemented with two's complement quantization. The study is restricted to algorithms with periodically varying inputs. Such inputs are common in a variety of applications, and for system identification, they can always be generated as shown with an example. It is shown that the quantized LMS algorithm is just a special case of a quantized periodically shift-varying (PSV) filter. Two different sufficient conditions are obtained for the bounded input bounded output (BIBO) stability of the PSV filter. When the filter is BIBO stable, two different bounds on the filter output are also derived. These conditions and bounds are then applied to the quantized LMS algorithm. The results are illustrated with examples.
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  • 156
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    Circuits, systems and signal processing 14 (1995), S. 603-614 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract An improved version of the Fast Polynomial Transform for the computation of two-dimensional cyclic convolutions is proposed in this paper. This new version of the Fast Polynomial Transform comes from the concept of splitting product-fields and gives more than a 20% to 50% reduction in the numbers of multiplications. An average of 20% improvement on overall computation time compared with the previous approach is also achievable.
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  • 157
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    Circuits, systems and signal processing 14 (1995), S. 653-660 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract An algorithm is presented for the spectrum of experimentally obtained exponentially damped sinusoidal signals. The implementation of this algorithm is straightforward and requires only simple basic mathematical operations. Applications of the algorithm are illustrated by several examples.
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  • 158
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    Circuits, systems and signal processing 14 (1995), S. 675-688 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Exact analysis of second-order sigma-delta modulators with constant input is presented. Some properties of general limit cycles are established. Sufficient conditions for the existence of a general class of limit cycles of the state vectors of the modulator are determined. The conditions interrelate the input, an initial vector, and the period of the limit cycle. Also, sufficient conditions are determined for a class of initial condition vectors to converge to a limit cycle.
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  • 159
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    Circuits, systems and signal processing 14 (1995), S. 735-747 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A weighted median filter is a nonlinear digital filter consisting of a window of length 2N + 1 and a weight vector W=(W− N,..., W0,..., WN). A root signal of a median type filter is a signal that is invariant to the filter. However, not all weighted median filters possess the convergence property. In this paper, we shall study the root structures and the convergence behavior of a subclass of weighted median filters, calledclass- 1 filters, which is symmetric in its weight vector. We shall introduce an important parameter, calledfeature value, and show that any one-dimensional unappended signal of lengthL will converge to a root signal in at most $$3\left\lceil {\frac{{L - 2}}{{2(2N + 2 - p)}}} \right\rceil$$ passes of aclass −1 filter with window width 2N + 1 and thefeature value p.
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  • 160
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    Circuits, systems and signal processing 14 (1995), S. 771-786 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A multirate modeling theory of the ARMA stochastic signals is derived from a state-space viewpoint in this work. Its application to the signal reconstruction problem for the recovery of the complete ARMA signal from its noise-corrupted, missing-sample sequence is then developed in detail. The proposed estimation-interpolation problem can be resolved by using the multirate optimal state estimation scheme of this work. Theoretically, the multirate Kalman reconstruction filters derived in this paper produce the minimum variance estimation and interpolation of the original complete, clean ARMA signal. Practically, the numerical examples show that the multirate Kalman reconstruction filters illustrate good estimation/interpolation performances, not only for synthetic ARMA sequences but also for human speech signals.
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  • 161
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    Circuits, systems and signal processing 15 (1996), S. 93-110 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Systematic methods are developed for simplified implementations of cascaded stack and WOS filters. For recursive stack and WOS filters, corresponding nonrecursive implementations are given, with linear complexity with respect to the number of iterations. Dynamic domino logic is proposed for VLSI hardware implementation of positive Boolean functions, and a pipelined stack filter architecture is described.
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  • 162
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    Circuits, systems and signal processing 16 (1997), S. 349-362 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We propose a new algorithm for estimating the parameters of damped, undamped, or explosive sinusoidal signals. The algorithm resembles the MODE algorithm, which is commonly used for direction of arrival estimation in the array signal processing field. It is derived as a natural approximation to an asymptotically (high-SNR) optimal parameter estimator and has excellent statistical accuracy. Nevertheless, it is computationally simple and easy to implement. Numerical examples are included to illustrate the performance of the proposed method.
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  • 163
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    Circuits, systems and signal processing 16 (1997), S. 387-403 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Our main result is a theorem that gives, in a certain setting, a necessary and sufficient condition under which discrete-space multidimensional shift-invariant input-output maps with vector-valued inputs drawn from a certain large set can be uniformly approximated arbitrarily well using a structure consisting of a linear preprocessing stage followed by a memoryless nonlinear network. Noncausal as well as causal maps are considered. Approximations for noncausal maps for which inputs and outputs are functions of more than one variable are of current interest in connection with, for example, image processing.
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  • 164
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    Circuits, systems and signal processing 16 (1997), S. 455-473 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper generalizes a recent result onsimple factorization of 2-variable (2-v) polynomials to simple andgroup factorization ofn-variate (n-v), (n≥3) polynomials. The emphasis is on developing a reliablenumerical technique for factorization. It is shown that simple as well as group factorization can be achieved by performing singular value decomposition (SVD) on certain matrices obtained from the coefficients of the givenn-v polynomial expressed in a Kronecker product form. For the polynomials that do not have “exact” simple and/or group factors, the concepts of approximate simple and group factorization are developed. The use of SVD leads to an elegant solution of an approximaten factorization problem. Several nontrivial examples are included to illustrate the results presented in this paper.
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  • 165
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    Circuits, systems and signal processing 16 (1997), S. 475-486 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper presents a sequentially operated periodic FIR filter to perform the functions of multirate filter banks for perfect reconstruction. This filter consists of an analysis filter and a synthesis filter. Each of these filters has a single-input/single-output FIR filter with periodically time-varying coefficients and a sequentially operated multichannel sampling scheme. As a result, the proposed filter can offer considerable improvements in computation and implementation. For the design of the filter, we provide a necessary and sufficient condition for perfect reconstruction in terms of the blocked transfer matrices and give a design procedure.
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  • 166
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    Circuits, systems and signal processing 16 (1997), S. 537-545 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper a novel analytical technique for designing linear-phase, FIR integrators of first degree has been proposed by taking the optimality criteria of maximal flatness (in the Butterworth sense) of the amplitude response, at midband frequency:ω=π/2. Mathematical formulas to compute exact weights for the design of first-degree integrators (i.e., frequency response 1/(jω)) have been derived. Thereafter, the design has been extended to approximate linear-phase integrators for any generic degreer, r〉1. The performance characteristics of the first-, second- and third-degree integrators have been given to highlight the efficacy of the designs. The suggested designs are particularly suitable for the midband frequency range of operations.
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  • 167
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    Circuits, systems and signal processing 16 (1997), S. 415-427 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A method is presented for the design of notch filters with specified notch frequency Ω0 and 3-dB rejection bandwidthB t, using a first-order real all-pass filter, wherein the only coefficient is used to control the notch frequency. To control the bandwidth, use is made of a new amplitude change function (ACF), and it is shown that given notch filter specifications can be exactly met thereby. Also, using the ACF, it is shown that stability of the second-order notch filter designs can be improved along with the noise gain.
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  • 168
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    Circuits, systems and signal processing 16 (1997), S. 487-505 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We consider a general nonlinear input-output system governed by operator equations that relate the system's input, state, and output, all of which are in extended spaces. It is assumed that the system variables are separated. Our results give conditions under which the stability of the nominal system is robust; i.e., it is not destroyed by any sufficiently small admissible perturbation of the system. Theorem 1 deals with the case when by stability we mean theincremental stability. Theorem 3 concerns the*-stability; i.e., the case when the stability is essentially the boundedness of the transmission operator. Moreover, in Theorem 2 it is shown that, under certain conditions, the incremental stability of the nominal system implies insensitivity. Basically, our results show that if the operators describing the nominal system are well behaved, and the transition from the nominal system to the perturbed system is not abrupt, then the nominal system stability is robust. The applications of the results are illustrated by several examples.
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  • 169
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    Circuits, systems and signal processing 18 (1999), S. 315-329 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In earlier studies a multiclass vector quantization (MVQ)-based neural network design was explored for pattern classification. We reconsider that design here in the context of function emulation. With proper adjustment, the MVQ design demonstrates excellent performance. Moreover, the design algorithms sense discontinuities in the data and replicate them in the network.
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  • 170
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    Circuits, systems and signal processing 18 (1999), S. 365-376 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In earlier studies the concept of a fast form was generalized to a format that unified such discrete transform examples as the FFT, the FCT, the FST, and the FHT. In this study we consider the approximation of arbitrary linear maps by fast forms. Using simulation we evaluate the approximation capabilities of the generalized fast form.
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  • 171
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    Circuits, systems and signal processing 18 (1999), S. 377-393 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract On-line running spectral analysis is of considerable interest in many electrophysiological signals, such as the EEG (electroencephalograph). This paper presents a new method of implementing the fast Fourier transform (FFT) algorithm. Our “real-time FFT algorithm” efficiently utilizes computer time to perform the FFT computation while data acquisition proceeds so that local butterfly modules are built using the data points that are already available. The real-time FFT algorithm is developed using the decimation-in-time split-radix FFT (DIT sr-FFT) butterfly structure. In order to demonstate the synchronization ability of the proposed algorithm, the authors develop a method of evaluating the number of arithmetic operations that it requires. Both the derivation and the experimental result show that the real-time FFT algorithm is superior to the conventional whole-block FFT algorithm in synchronizing with the data acquisition process. Given that the FFT sizeN=2 r , real-time implementation of the FFT algorithm requires only 2/r the computational time required by the whole-block FFT algorithm.
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  • 172
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    Circuits, systems and signal processing 18 (1999), S. 523-523 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
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  • 173
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    Circuits, systems and signal processing 18 (1999), S. 539-551 
    ISSN: 1531-5878
    Schlagwort(e): H 2 deconvolution filter ; envelope-constrained filter ; finite impulse response filter ; linear matrix inequality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper, we consider an envelope-constrained (EC)H 2 optimal finite impulse response (FIR) filtering problem. Our aim is to design a filter such that theH 2 norm of the filtering error transfer function is minimized subject to the constraint that the filter output with a given input to the signal system is contained or bounded by a prescribed envelope. The filter design problem is formulated as a standard optimization problem with linear matrix inequality (LMI) constraints. Furthermore, by relaxing theH 2 norm constraint, we propose a robust ECFIR filter design algorithm based on the LMI approach.
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  • 174
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    Circuits, systems and signal processing 18 (1999), S. 565-585 
    ISSN: 1531-5878
    Schlagwort(e): Two-dimensional system ; model conversion ; Roesser's model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper presents a geometric-series method for finding two-dimensional (2D) discrete-time (continuous-time) state-space models from 2D continuous-time (discretetime) systems. This method allows the use of well-developed theorems and algorithms in the 2D discrete-time (continuous-time) domain to indirectly carry out analysis and design of hybrid 2D composite systems.
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  • 175
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    Circuits, systems and signal processing 14 (1995), S. 817-825 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The necessary and sufficient conditions for the invariance of theU-function of a linear time-invariant two-port network under lossless nonreciprocal imbedding are given in terms of the anti-Hermitian property of the immittance matrix of the imbedding network.
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  • 176
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    Circuits, systems and signal processing 15 (1996), S. 51-69 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this study we consider a multilayer perceptron network with sigmoidal activation and trained via the backpropagation algorithm. The output of all neurons is collected and a simple linear regression is performed. It is shown that untrained networks with randomly chosen coefficients perform comparably with fully trained networks. This result casts a new light on the role of activation functions, the impact of dimensionality, and the efficacy of training algorithms such as backpropagation.
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  • 177
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    Circuits, systems and signal processing 15 (1996), S. 23-50 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The PNS module is discussed as the building block for the synthesis of parallel, self-organizing, hierarchical, neural networks (PSHNNs). The PNS module contains three submodules (units), the first two of which are created as simple neural network constructs and the last of which is a statistical unit. The first two units are fractile in nature, meaning that each such unit may itself consist of a number of parallel PNS modules in a fractile fashion. Through a mechanism of statistical acceptance or rejection of input vectors for classification, the sample space is divided into a number of regions. The input vectors belonging to each region are classified by a dedicated set of PNS modules. This strategy results in considerably higher accuracy of classification and better generalization as compared to previous neural network models. If the delta rule network is used to generate the first two units, each region approximates a linearly separable region. In this sense, the total system becomes similar to a piecewise linear model. The various regions are determined nonlinearly by the first and third units of the PNS modules.
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  • 178
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    Circuits, systems and signal processing 15 (1996), S. 111-136 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We use the so-calledreflection coefficients (RCs) to examine, review, and classify the Schur-Cohn and Marden-Jury (SCMJ) class of tests for determining the zero location of a discrete-time system polynomial with respect to the unit circle. These parameters are taken as a platform to propose a partition of the SCMJ class into four useful types of schemes. The four types differ in the sequence of polynomials (the “table”) they associate with the tested polynomials by scaling factors: (A) a sequence of monic polynomials, (B) a sequence of least arithmetic operations, (C) a sequence that produces the principal minors of the Schur-Cohn matrix, and (D) a sequence that avoids division arithmetic. A direct derivation of a zero location rule in terms of the RCs is first provided and then used to track a proper zero location rule in terms of the leading coefficients of the polynomials of the B, C, and D scheme prototypes. We review many of the published stability tests in the SCMJ class and show that each can be sorted into one of these four types. This process is instrumental in extending some of the tests from stability conditions to zero location, from real to complex polynomial, in providing a proof of tests stated without a proof, or in correcting some inaccuracies. Another interesting outcome of the current approach is that a byproduct of developing a zero location rule for the Type C test is one more proof for the relation between the zero location of a polynomial and the inertia of its Schur-Cohn matrix.
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  • 179
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    Circuits, systems and signal processing 15 (1996), S. 261-274 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We study the following type of filtering problem: consider an image on ℤ2, that is, a nonnegative function on the vertices of a grid, which represents the brightness at each of these points. We assume that there is, however, a “smudging” effect. That is, what ought to be a point of light becomes the point together with a halo about it, visualized by a distribution of light which is greatest at the point itself and decreases with the distance. So what we actually see is a blurry image. In this article we investigate methods for clearing up the image, i.e. reconstructing the original function from the blurry haloed image when the halo decays exponentially, and also for some haloes with small finite support. This task is usually performed by inverting the convolution operator induced by the halo (that is, by Fourier analysis). We introduce a different recovery procedure, based upon a family of filtering operators that change from point to point. For the finitely supported haloes, this procedure compares favorably with the Fourier methods. Moreover, in principle it is more general, because it does not require assumptions of invariance under translation. In full generality, however, we are able to recover images not on grids, but only on trees.
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  • 180
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    Circuits, systems and signal processing 15 (1996), S. 233-260 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract This paper considers several aspects of robust estimation in the restoration of mutichannel images. Robust functionals emerging from a generalized maximum a posteriori (MAP) approach are employed for the representation of both the noise and the signal statistics. Several linear multichannel techniques can be derived as special cases of the approach presented. In addition, the robust approach derives nonlinear algorithms that simultaneously account for the suppression of nominal noise and outliers, and for the efficient reconstruction of sharp detailed structure in the estimate. The robust multichannel approach is presented as a general approach for the regularization of the ill-posed restoration problem. From this perspective, we develop a method for the selection of the regularization parameter, which can be used in a wide variety of applications that may or may not involve noise outliers. We consider several issues associated with the application of robust algorithms to multichannel images, we discuss computational inefficiencies of such algorithms, and we propose approximations that are appropriate for their cost-efficient multichannel implementation. We demonstrate the robust approach in two examples from the rapidly developing fields of color image processing and multiresolution image processing in the wavelet domain.
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  • 181
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    Circuits, systems and signal processing 15 (1996), S. 415-435 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In our recent work, we solved the word sequence length constraint problem associated with number theoretic transforms defined in finite integer rings. This is based on the American-Indian-Chinese extension of the Chinese remainder theorem. This work builds further on the results by extending them to the domain of integer polynomial rings. The theory of polynomial factorization and the resulting direct sum property are studied in depth. The emphasis is on the theory of computational algorithms for processing sequences defined in finite integer and complex integer rings.
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  • 182
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    Circuits, systems and signal processing 15 (1996), S. 437-452 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this work, we analyze the algebraic structure of fast algorithms for computing one- and two-dimensional convolutions of sequences defined over the fields of rational and complex rational numbers. The algorithms are based on factorization properties of polynomials and the direct sum property of modulo computation over such fields. Algorithms are described for cyclic as well as acyclic convolution. It is shown that under certain nonrestrictive conditions, all the previously defined algorithms over the fields of rational and complex rational numbers are also valid over the rings of finite integers. Examples are presented to illustrate the results.
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  • 183
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    Circuits, systems and signal processing 15 (1996), S. 519-527 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The aim of this paper is to give an explicit computation for the potential generated by a dipole on a 2-dimensional grid such that the conductances on the vertical and horizontal edges have period 2.
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  • 184
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    Circuits, systems and signal processing 15 (1996), S. 529-542 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Digital filterbanks, an important signal processing tool, are used in a radar signal processor to measure target range and/or velocity [4]. The windowed FFT is the most common radar filterbank. The FFT is a special case of modulated filterbank. Modulated filterbanks subdivide the frequency region by modulating a prototype baseband filter. This baseband filter usually satisfies certain frequency response constraints. Filterbanks used in radar applications are not concerned with reconstruction as are wavelet-based approaches [2], but rather with how well the filters subdivide the frequency region into a prescribed number of equal frequency regions. Wavelets use time decimation or frequency scaling to form filterbanks. This paper focuses on using a wavelet-like scaling approach along with modulation to design a digital filterbank. However, we are not concerned with reconstruction but with the subdivision of the frequency region into a prescribed number of equal segments. It will be shown that this new design algorithm has a frequency response performance comparable to existing techniques but with less computational effort. The performance measures considered are rejection of out of bands signals, uniformity of inband signal gain, and transition width from inband to stopband.
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  • 185
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    Circuits, systems and signal processing 18 (1999), S. 505-521 
    ISSN: 1531-5878
    Schlagwort(e): Multirate systems ; multirate signal processing ; filter banks ; optimal design
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The design of general nonuniform filter banks is studied. Contrary to uniform filter banks, in nonuniform filter banks, it may not be possible to achieve perfect reconstruction, but in some cases by using optimization techniques, we can design acceptable filter banks. Here, the initial finite impulse response (FIR) analysis filters are designed according to the characteristics of the input. By the design procedure, the FIR synthesis filters are found so that theH-norm of an error system is minimized over all synthesis filters that have a prespecified order. Then, the synthesis filters obtained in the previous step are fixed, and the analysis filters are found similarly. By iteration, theH-norm of the error system decreases until it converges to its final value. At each iteration, the coefficients of the analysis or synthesis filters are obtained by finding the least squares solution of a system of linear equations. If necessary, the frequency characteristics of the filters can be altered by adding penalty terms to the objective function.
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  • 186
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    Circuits, systems and signal processing 18 (1999), S. 617-617 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
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  • 187
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    Circuits, systems and signal processing 16 (1997), S. 107-119 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract For models of zero-input direct-form digital filters implemented in fixed-point digital hardware it is known that if saturation arithmetic is used and stability holds when the quantization is ignored, then the amplitude of all limit cycles can be made arbitrarily small by making the bound on the magnitude of the quantization sufficiently small. In that sense the effects of quantization and overflow can be considered separately. Recently, this proposition was extended to the case in which the input need not be zero. Here we give a result to the effect that quantization and overflow can be considered separately for a much more general class of discrete-time systems, and we give as an example an application of this result to systems governed by state equations.
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  • 188
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    Circuits, systems and signal processing 16 (1997), S. 197-206 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A new two-dimensional (2D) sample-based conjugate gradient (SCG) algorithm is developed for adaptive filtering. This algorithm is based on the conjugate gradient method of optimization and therefore has a fast convergence characteristic. The SCG is computationally simpler than the recursive least squares (RLS) algorithm. The SCG algorithm with the equation-error and output-error methods is investigated for application in image restoration. Simulation results show that the new algorithm significantly outperforms existing algorithms in the restoration of noisy images.
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  • 189
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    Digitale Medien
    Springer
    Circuits, systems and signal processing 16 (1997), S. 287-305 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract A number of agents can arrange themselves equidistantly in a row via a sequence of adjustments, based on a simple “local” interaction. The convergence of the configuration to the desired one is exponentially fast. A similarity is shown between this phenomenon and the dynamics of pulse propagation along a distributedRC line, and a conjecture is made concerning the evolution of a similar system with a probabilistic rule of behavior.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 190
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 321-334 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract To improve the simulation efficiency of switched circuits, it is advantageous to model their switching devices as short and open circuits. The disadvantage is that such models may cause inconsistent initial conditions (IIC), and Dirac impulses may appear. Conventional simulators do not handle such situations correctly. This paper introduces a new algorithm for analyzing circuits with IIC by a mixed numerical-symbolic method. The method detects the order of the Dirac impulse and also finds the correct initial conditions after switching. It is applicable to nonlinear circuits.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 191
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 691-702 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We consider stability properties of discrete-time bilinear filters. Simple sufficient conditions are given for bounded-input bounded-output stability (with not necessarily zero initial conditions),l p stability, and three other important types of stability. In particular, conditions are given under which asymptotically periodic inputs produce asymptotically periodic outputs with the same period.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 192
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 709-718 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The stability of autoregressive (AR) models is an important issue in many applications such as spectral estimation, simulation of EEG, and synthesis of speech. There are methods for AR parameter estimation that guarantee the stability of the model, that is, all roots of the characteristic polynomial of the model have moduli less than unity. However, in some situations, such as EEG simulation, the models that exhibit roots with almost unit moduli are difficult to use. In this paper we propose a method for estimating AR models that guarantees hyperstability, that is, the moduli of the roots are less than or equal to some arbitrary positive number. The method is based on an iterative minimization scheme in which the associated nonlinear constraints are linearized sequentially.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 193
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 17 (1998), S. 733-735 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We direct attention to a widespread oversight concerning linear systems and superposition.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 194
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 43-57 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract We consider multirate digital control systems that consist of an interconnection of a continuous-time nonlinear plant (described by ordinary differential equations) and a digital lifted controller (described by ordinary difference equations). The input to the digital controller consists of the multirate sampled output of the plant, and the input to the continuous-time plant consists of the multirate hold output of the digital controller. In this paper we show that when quantizer nonlinearities are neglected, then under reasonable conditions (which exclude the critical cases), the stability properties (in the Lyapunov sense) of the trivial solution of the nonlinear multirate digital control system can be deduced from the stability properties of the trivial solution of its linearization. We also point out that certain results involving quantization effects and stabilizing controllers can be established which are in the spirit of some existing results.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 195
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 59-73 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Chaotic systems provide a simple means of generating deterministic signals that resemble white noise. It is this noise-like property that provides the potential for applying chaotic systems in communications. In this work, we report a detailed study of the logistic map for use as direct-sequence spread-spectrum (DS/SS) codes. The advantages of the chaotic DS/SS codes are the almost unlimited number of distinct sequences of arbitrary lengths, the ease of generating these sequences, and the increased privacy afforded by the noise-like appearance of these sequences. Some design criteria are provided from the correlation properties of these sequences, and bit-error rate (BER) results are generated by Monte Carlo simulations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 196
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 75-84 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The asymptotic behavior of block floating-point and floating-point digital filters is analyzed. As a result, mantissa wordlength conditions are derived guaranteeing the absence of limit cycles in the regular dynamic range. Explicitly, the requirements are given for block floating-point state space filters with different quantization formats. Although these conditions are only sufficient, examples are given in which they are also necessary. In most cases the conditions are easily satisfied.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 197
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 85-85 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 198
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 87-88 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 199
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 189-190 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 200
    Digitale Medien
    Digitale Medien
    Springer
    Circuits, systems and signal processing 18 (1999), S. 169-181 
    ISSN: 1531-5878
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In this paper the Cramér-Rao bound (CRB) for a general nonparametric spectral estimation problem is derived under a local smoothness condition (more exactly, the spectrum is assumed to be well approximated by a piecewise constant function). Further-more, it is shown that under the aforementioned condition the Thomson method (TM) and Daniell method (DM) for power spectral density (PSD) estimation can be interpreted as approximations of the maximum likelihood PSD estimator. Finally the statistical efficiency of the TM and DM as nonparametric PSD estimators is examined and also compared to the CRB for autoregressive moving-average (ARMA)-based PSD estimation. In particular for broadband signals, the TM and DM almost achieve the derived nonparametric performance bound and can therefore be considered to be nearly optimal.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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