Showing papers on "Transfer function published in 1981"
TL;DR: In this article, a linear feedback control is applied in high accuracy tracking of a periodic reference input by locating the imaginary poles of the controller's transfer function to suit the period of the input.
432 citations
TL;DR: In this article, a method to model a time delay by a finite impulse response filter is presented, which is useful in simulation work that involves time delays and transforms the time delay estimation problem into one of parameter estimation.
Abstract: A method to model a time delay by a finite impulse response filter is presented. It is useful in simulation work that involves time delays and transforms the time delay estimation problem into one of parameter estimation. The benefits of this approach are the elimination of spectral estimation, a choice of many parameter estimation algorithms, and the capability to track time-varying delays. Two examples of estimating nonstationary time delays are also given.
131 citations
TL;DR: In this article, two analytic synthesis techniques are presented for even-degree dual-mode in-line prototype networks up to degree 14, where the coupling matrix for the double cross-coupled array, rotational transformations are applied to transform the matrix into the form required for the dualmode inline asymmetric structure.
Abstract: Two analytic synthesis techniques are presented for even-degree dual-mode in-line prototype networks up to degree 14. Commencing with the coupling matrix for the double cross-coupled array, rotational transformations are applied to transform the matrix into the form required for the dual-mode in-line asymmetric structure. "Asymmetric" here means that the coupling elements (irises, screws) are unequal in value about the physical center of the filter. The necessity for these asymmetric solutions arose when it was discovered that it was impossible to realize certain useful transmission characteristics with the symmetric in-line structure, on account of their transmission zero pattern in the complex-plane representation of the transfer function. Furthermore, because the full coupling matrix is used instead of the even-mode matrix as with the symmetric solution, the asymmetric in-line realization process may be applied to electrically asymmetric matrices, such as those for single ended filters for multiplexer applications. To demonstrate the validity of the theory, a practical model of each type of realization has been constructed.
109 citations
TL;DR: In this article, it was shown that for any 2D digital filter satisfying Shanks' criterion there exists a realization that cannot support overflow oscillations, and a technique for determining whether a normal realization exists for a given 2D discrete system.
Abstract: An important theorem relating to the Lyapunov stability of two-dimensional discrete systems is proven. Using this theorem it is shown that for any 2-D digital filter satisfying Shanks' criterion there exists a realization that cannot support overflow oscillations. In the process of proving the theorem some interesting results on the multi-dimensional bilinear transformation are developed. One of these results yields a simple test that can be used to check the stability of a 2-D discrete transfer function that has been obtained from the bilinear transform of a 2-D continuous transfer function with a 2-D Hurwitzian denominator polynomial. A technique is given for determining whether a normal realization exists for a given 2-D discrete system. Also, a theorem is presented that allows the determination of the norm of the minimum norm realization of a given transfer function. A noniterative technique for obtaining a low norm realization and an iterative technique for obtaining a minimum norm realization are developed.
93 citations
90 citations
TL;DR: Chebyshev gain functions have been widely employed for tly, matching a complex load to a resistive generator as discussed by the authors, and such transfer functions do result in optimum response when the terminations are purely resistive.
Abstract: Chebyshev gain functions have been widely employed for tly, matching a complex load to a resistive generator. Such transfer functions do result in optimum response when the terminations are purely resistive. However, assuming the overall transducer gain characteristic has monotone decreasing stopband behavior, the equal ripple transfer function is shown to be not optimum for a complex load. Furthermore, equalizers simpler in structure and superior in frequency response to equal ripple designs can readily be synthesized. Indeed it appears that nonoptimality will generally result whenever analytic gain-bandwidth theory is used to determine the constants of a transfer function belonging to an a priori specified class. Examples are presented for the matching of LCR and CR loads.
85 citations
TL;DR: In this article, the authors show how in the particular case of diagonal compensators or similarity transforms, there is a very easy way, based on Perron-Frobenius theory, of obtaining optimal reduction in the off-diagonal elements.
77 citations
01 Dec 1981
TL;DR: In this article, a transfer function characterization of this property is developed, which allows characterization also of the degree of a fixed mode, this concept being given a meaningful definition in the course of the paper.
Abstract: Multiple-input, multiple-output systems are considered which are linear, time-invariant and finite dimensional and which possess a decentralized fixed mode. A transfer function characterization of this property is developed, which allows characterization also of the degree of a fixed mode, this concept being given a meaningful definition in the course of the paper.
67 citations
01 Nov 1981
TL;DR: Simultaneous frequency and wavenumber estimation using two-dimensional (2-D) linear prediction on a space-time data array is investigated and is superior to the 2-D Fourier transform method in resolving signals closely spaced in frequency andwavenumber.
Abstract: Simultaneous frequency and wavenumber estimation using two-dimensional (2-D) linear prediction on a space-time data array is investigated. The method used is a direct extension of our previously presented one-dimensional (1-D) frequency estimation technique. It is relatively simple computationally and is superior to the 2-D Fourier transform method in resolving signals closely spaced in frequency and wavenumber.
65 citations
TL;DR: The performance of young adult subjects was recorded when the photometric contrast of a task was altered using “realistic” methods and suggestions for practical lighting design were presented.
Abstract: The performance of young adult subjects was recorded when the photometric contrast of a task was altered using “realistic” methods. A general transfer function was obtained relating task contrast to performance. Based upon the transfer function and additional photometric measurements, suggestions for practical lighting design were presented.
59 citations
TL;DR: In this article, a procedure is developed for the computation of a state-space realization of a two-dimensional filter with a separable transfer function, which relies on a canonic form for the state space realization.
Abstract: In this paper a procedure is developed for the computation of a state-space realization of a two-dimensional filter. The transfer function of this realization has a separable denominator. The procedure relies on a canonic form for the state-space realization and utilizes a finite sequence of two-dimensional pulse response coefficients (Markov parameters).
01 Jan 1981
TL;DR: The device physics of silicon photodetectors is presented in detail including discussion and analysis of quantum efficiency, responsivity, ctosstalk, charge handling capacity, data rate, optical to electrical transfer function, noise sources, dynamic range, and sensitivity.
Abstract: A description of devices, architecture, and performance criteria is presented for solid-state CCD and photodiode sensors useful in acousto-optic processing systems. Special attention is given to sensors used in both bulk and integrated optical acousto-optic instantaneous Fourier transform systems. The device physics of silicon photodetectors is presented in detail including discussion and analysis of quantum efficiency, responsivity, ctosstalk, charge handling capacity, data rate, optical to electrical transfer function, noise sources, dynamic range, and sensitivity. A description of new technologies, such as VHSIC and GaAs IC's which are applicable to sensor technology for AO signal processing systems is also presented.
TL;DR: In this article, three circuits each realizing a first-order all-pass transfer function are described, each of which offers high input impedance and controllable voltage gain, and three circuits are described.
Abstract: Three circuits each realizing a, first-order all-pass transfer function are described in this communication, These circuits offer high input impedance and controllable voltage gain.
TL;DR: In this article, the authors give a simple approach for obtaining recursive-in-time identification procedures for both AR and ARMA processes, investigating furthermore the connections between the so obtained algorithms and the classical (least squares procedure).
Abstract: Fast recursive-in-time identification procedures for both AR and ARMA processes (e.g., Chandrasekhar, square root algorithms,... ) have been available for a few years. These algorithms realize the desired transfer functions in the classical polynomial or rational form. On the other hand, the synthesis of polynomial and rational transfer functions in lattice and ladder form has fostered great interest in network theory by virtue of its pleasant properties. This type of synthesis is strongly related to the theory of orthogonal polynomials on the unit circle. An identification procedure with the realization of the desired whitening filter in lattice form was available for AR processes. We give here a simple approach for obtaining such algorithms, investigating furthermore the connections between the so obtained algorithms and the classical ones (least squares procedure). In the same way, we obtain identification procedures with realization of the desired filter in lattice and ladder form for ARMA processes, together with the connection with the classical extended least squares procedure. The method is based upon a fairly general Levinson orthogonalization lemma in Hilbert space, involving innovation techniques. We extend the method to various other estimation problems. The algorithms we obtain are fast (even somewhat faster than the previous fast ones) and seem to be well conditioned.
01 Apr 1981
TL;DR: It is shown in this paper that from this set of eigenvectors and the corresponding eigenvalues, an estimator for the sources spectral densities can be derived.
Abstract: In the eigenvalue - eigenvector decomposition of the spectral density matrix of the signals received on a passive array, two sets of eigenvectors are found. The first set contains eigenvectors which are asymptotcally orthogonal to the sources direction vectors : from them a high resolution bearing estimator has been deduced. The other set contains eigenvectors which are asymptotically a basis for the sources direction vectors space. It is shown in this paper that from this set and the corresponding eigenvalues, an estimator for the sources spectral densities can be derived. Simulation results are given.
TL;DR: Detailed design specifications of a low-cost instrument that is capable of yielding transfer function measurements with a high degree of accuracy and speed are presented, especially well suited to the measurement of transfer functions of biological systems.
Abstract: The measurement of the linear transfer function of a biological system has found wide use in the characterization of the system's input/output properties, and in the separation and measurement of the properties of the different subelements that make up the system. Unfortunately sophisticated and expensive instrumentation has traditionally been required to make these measurements. In this paper, we present detailed design specifications of a low-cost instrument that is capable of yielding transfer function measurements with a high degree of accuracy and speed. The instrument is comprised of a pseudo-random binary sequence signal generator with precise date acquisition synchronization circuits, interfaced to a general-purpose mini-or microcomputer system common to many laboratory environments. The instrument is capable of measuring the transfer function of an arbitrary biological system up to a bandwidth of 8.3 KHz, with a frequency resolution of 425 points. In cases where the biological measurements are not contaminated with experimental noise, the transfer function can be determined in as little as 47 ms of data collection. In the case where experimental noise is present in the biological measurements, a simple averaging method is described which results in an effective increase in the signal-to-noise ratio, thereby yielding accurate transfer function estimates. The instrument is especially well suited to the measurement of transfer functions of biological systems, where experimental noise is a problem and where only limited time is available to acquire stable measurements.
TL;DR: In this article, the Inverse Fourier Transform is avoided by direct frequency domain fitting: either interpolation (exact for selected points) or weighted least squares approximation, and the method of recursive convolutions is generalized for complex exponentials.
Abstract: Recursive convolutions are believed to be the basic approach for digital calculation of electromagnetic transients on transmission systems. They require step responses expressed by means of exponential functions. This paper presents the theory for obtaining an arbitrary number of exponential components - with real or complex exponents directly from the frequency domain transfer function. The Inverse Fourier Transform is avoided by direct frequency domain fitting: either interpolation (exact for selected points) or weighted least squares approximation. Finally the method of recursive convolutions is generalized for complex exponentials.
TL;DR: In this article, conditions for unstable pole-zero cancellation in the product of two transfer function matrices G and H were studied, and conditions for cancellation were phrased in terms of the coprimeness of matrices associated with matrix fraction descriptions.
Abstract: We study conditions for pole-zero cancellation including unstable pole-zero cancellation in the product of two transfer function matrices G and H. Pole-zero cancellation is defined using McMillan degree ideas, and conditions for cancellation are phrased in terms of the coprimeness of matrices associated with matrix fraction descriptions of G and H. Using the condition for unstable pole-zero cancellation, we obtain a new set of conditions for the stability of linear MIMO feedback systems. We show that such a feedback system is stable if and only if there is no unstable pole-zero cancellation in GH and if (I+GH)^{-1} is stable. On the other hand, if there is no unstable pole-zero cancellation in GH and any or all of (I+ HG)^{-1}, G(I+ HG)^{-1} , and H(I+ GH)^{-1} are stable, the closed-loop may be unstable- but only if there is an unstable pole-zero cancellation in HG.
TL;DR: In this paper, the surface kinetics of reactive molecular beam scattering have been analyzed by discrete Fourier analysis of the scattered product waveform, and it has been shown that with square wave modulation, harmonics in the scattered waveform as high as 29 can be significant.
Abstract: The surface kinetics of reactive molecular beam scattering have been analyzed by discrete Fourier analysis of the scattered product waveform. In experiment and by calculation, it has been shown that with square wave modulation, harmonics in the scattered waveform as high as 29 can be significant. These harmonics can be used to characterized the transfer function of linear surface kinetics with modulation at four or fewer frequences. Optimum signal‐to‐noise in the derived rate parameter is obtained using the phase shift of the first harmonic where K/ω is approximately one. Fourier waveform analysis of square wave modulation compares favorably with lock‐in amplifier detection, cross correlation modulation, and pulse testing for the analysis of surface kinetics.
TL;DR: In this paper, the non-minimal real state-space realization for n-dimensional transfer functions with polylinear numerators and denominators is stated and proved, and it is shown that every existing realization of such transfer functions can be achieved from the companion matrix of some (n + 1)-variable polynomial linear with respect to one of its variables.
Abstract: In this paper the non-minimal real state-space realization for n-dimensional transfer functions with polylinear numerators and denominators is stated and proved. It is also shown that the every existing realization of an n-dimensional transfer function can be achieved from the companion matrix of some (n + 1)-variable polynomial linear with respect to one of its variables.
01 Jan 1981
TL;DR: In this article, the effects of actuator and sensor locations on transfer function zeros were investigated, using uniform bars and beams as generic models of flexible space structures, and finite element codes were used directly to calculate transfer function zero.
Abstract: The effects of actuator and sensor locations on transfer function zeros are investigated, using uniform bars and beams as generic models of flexible space structures. It is shown how finite element codes may be used directly to calculate transfer function zeros. The impulse response predicted by finite-dimensional models is compared with the exact impulse response predicted by the infinite dimensional models. It is shown that some flexible structures behave as if there were a direct transmission between actuator and sensor (equal numbers of zeros and poles in the transfer function). Finally, natural damping models for a vibrating beam are investigated since natural damping has a strong influence on the appropriate active control logic for a flexible structure.
01 Apr 1981
TL;DR: The approach is based on employing the Walsh spectra of input output signals in an algorithm that yields the unknown initial conditions along with the system parameters to be useful in practical situations wherein the input-output data is available on an arbitrary but active period of time.
Abstract: A method of identification of the transfer function matrix of a multi-input multi-output (MIMO) linear time invariant system is presented. The approach is based on employing the Walsh spectra of input output signals in an algorithm that yields the unknown initial conditions along with the system parameters to be useful in practical situations wherein the input-output data is available on an arbitrary but active period of time.
TL;DR: A modeling approach which makes use of conventional systems engineering techniques where the transfer functions are expressed in the complex domain using Laplace transforms is presented, yielding measures of effectiveness of the security system.
TL;DR: In this paper, a complete set of design equations for first-order and biquadratic transfer functions in the z-domain is given, and a step-by-step design procedure for SC filters is discussed.
Abstract: A complete set of design equations is given for first-order and biquadratic transfer functions in the z -domain. These equations are derived directly from the first- and second-order transfer functions in the s -domain. Consequently no new approximation for a prewarped set of cutoff frequencies is required. A step-by-step design procedure for SC filters follows. The sampling-conditions for input and output signals and for cascading are also discussed.
01 Sep 1981
TL;DR: In this paper, a 3D theory of short-primary linear induction machines is presented, which almost completely incorporates both longitudinal and transverse end effects, especially including ferromagnetic end effects caused by the geometry of the primary laminated iron.
Abstract: A new 3-dimensional theory of short-primary linear induction machines is presented. The theory almost completely incorporates both longitudinal and transverse end effects, especially including ferromagnetic end effects caused by the geometry of the primary laminated iron. The theory is based on the idea of considering two different regions of the primary iron and the airspace around it as one fictitious region having an inhomogeneous permeability, with step variations only at the four iron/air boundaries if the primary iron is assumed nonconducting. The 5-layer boundary-value problem including the fictitious layer is solved neatly in a mathematical sense using the new transfer-matrix method developed here. The theory is verified from test data on the double-sided linear induction machine at General Electric Co. The theory can very accurately predict the machine behaviour, including the vertical force, at low computational cost.
TL;DR: A formula is given which allows the determination of the transfer function matrix of linear multivariable two-dimensional systems directly in terms of the state transition matrix and the characteristic equation.
Abstract: A formula is given which allows the determination of the transfer function matrix of linear multivariable two-dimensional (2-D) systems directly in terms of the state transition matrix and the characteristic equation.
TL;DR: In this article, singular perturbation methods are used to exhibit the asymptotic structure of the transfer function matrices of discrete-time tracking systems incorporating linear multivariate plants which are amenable to fast-sampling error-actuated digital control only if extra output measurements are generated by the introduction of appropriate transducers and processed by inner-loop compensators.
Abstract: Singular perturbation methods are used to exhibit the asymptotic structure of the transfer function matrices of discrete-time tracking systems incorporating linear multivariate plants which are amenable to fast-sampling error-actuated digital control only if extra plant output measurements are generated by the introduction of appropriate transducers and processed by inner-loop compensators. It is shown that these results greatly facilitate the determination of controller and transducer matrices which ensure that the closed-loop behaviour of such discrete-time tracking systems becomes increasingly non-interacting as the sampling frequency is increased. These general results are illustrated by designing a fast-sampling error-actuated digital controller for an aircraft.
TL;DR: In this paper, the problem of factorizing the transfer function of single-input single-output 2D systems to a product of two 1-D transfer functions using state feedback is considered.
Abstract: The problem of factorizing the transfer function of single-input single-output 2-D systems to a product of two 1-D transfer functions using state feedback is considered. It is shown that if the numerator of the open-loop transfer function can, by itself, be written as a product of two 1-D polynomials, then the closed-loop transfer function can, under certain conditions, be factorized as a product of two 1-D transfer functions. In cases where the numerator is not by itself factorizable, then the present results restrict themselves to factoring the denominator of the closed-loop system to a product of two 1-D polynomials.
TL;DR: In this article, two methods of approximating the desired variable characteristics by a rational transfer function and constructing it as a concrete network are described, which can be realized with a minimal number of dynamic elements and variable elements in the network construction.
Abstract: A variable network is a network in which a designated input-output characteristic can be obtained continuously by varying continuously a specific parameter. This paper describes two methods of approximating the desired variable characteristics by a rational transfer function and constructing it as a concrete network. In the conventional method, an approximation with good accuracy is obtained by raising the orders of the complex frequency s and the variable parameter λ. The actual construction of the network becomes difficult because of the higher orders. Two methods are proposed in this paper to avoid this difficulty. In the first method, the approximated transfer function is divided into unit blocks, lower order for the complex frequency s and a bilinear form for the variable parameter λ. By this method, the actual construction of a network can be simplified considerably. In the second method, the desired characteristics are approximated in the form of a transfer function in which the denominator polynomial is resolved into the polynomials of s and λ, respectively. The approximated transfer function in this form has a merit in that it can be realized with a minimal number of dynamic elements and variable elements in the network construction. Moreover, its stability is independent of λ.
TL;DR: In this paper, a high-gain error-actuated analogue controller for a chemical reactor is proposed. But the controller matrices are not shown to be asymptotic in the transfer function matrices.
Abstract: Singular perturbation methods are used to exhibit the asymptotic structure of the transfer function matrices of continuous-time tracking systems incorporating linear multivariable plants which are amenable to high-gain error-actuated analogue control. It is shown that these results greatly facilitate the determination of controller matrices which ensure that the closed-loop behaviour of such continuous-time tracking systems becomes increasingly ‘ tight ’ and non-interacting as the gain parameter is increased. These general results are illustrated by designing a high-gain error-actuated analogue controller for a chemical reactor.