Showing papers on "Transfer function published in 2002"

Linear System Theory

Abstract: Chapter 8 establishes the relationship between the input and output power spectral densities of a linear system. Limitations on results are carefully detailed and the case of oscillator noise is considered. The theory is extended to multiple input-multiple output systems.

An Inverse Gray-Box Model for Transient Building Load Prediction

Abstract: Lower costs and improved performance of sensors, controllers, and networking is leading to the development of smart building features, such as continuous performance monitoring, automated diagnostics, and optimal supervisory control. For some of these applications, it is important to be able to predict transient cooling and heating requirements for the building using inverse models that are trained using on-site data. Existing inverse models for transient building loads range from purely empirical or “black-box” models to purely physical or “white-box” models. Generally, black-box (e.g., neural network) models require a significant amount of training data and may not always reflect the actual physical behavior, whereas white-box (e.g., finite difference) models require specification of many physical parameters. This paper presents a hybrid or “gray-box” modeling approach that uses a transfer function with parameters that are constrained to satisfy a simple physical representation for energy flows in the b...

A transmission line model for high-frequency power line communication channel

Abstract: This paper presents a novel approach to modelling the transfer function of the broadband power line communication channel. In the approach, the power line is firstly approximated as a two-wire transmission line. The two intrinsic line parameters, the characteristic impedance and the propagation constant, are derived based on the transmission line theory. Then from the derived line parameters, an echo-based model is used to determine the transfer function for communication signals in the frequency range of 1 MHz-30 MHz. This approach reaps the advantages of accuracy and simplicity of the conventional modeling approaches.

Digital Signal Processing: System Analysis and Design

Abstract: From the Publisher: Digital signal processing lies at the heart of the communications revolution and is an essential element of key technologies such as mobile phones and the Internet. This book covers all the major topics in digital signal processing (DSP) design and analysis, supported by MATLAB examples and other modeling techniques. The authors explain clearly and concisely why and how to use digital signal processing systems; how to approximate a desired transfer function characteristic using polynomials and ratios of polynomials; why an appropriate mapping of a transfer function onto a suitable structure is important for practical applications; and how to analyze, represent, and explore the trade-off between time and frequency representation of signals. An ideal textbook for students, it will also be a useful reference for engineers working on the development of signal processing systems.

Extremum seeking control for discrete-time systems

Abstract: We present an extremum seeking control algorithm for discrete-time systems applied to a class of plants that are represented as a series combination of a linear input dynamics, a static nonlinearity with an extremum, and a linear output dynamics. By using the two-time scale averaging theory, we derive a mild sufficient condition under which the plant output exponentially converges to an O(/spl alpha//sup 2/) neighborhood of the extremum value, where /spl alpha/ is the magnitude of modulation signal. The sufficient condition is related to positive realness of linear parts of the plant but only at the modulation frequency. The algorithm is illustrated with a brief simulation study.

Transfer function-noise modeling in continuous time using predefined impulse response functions

Abstract: Received 18 December 2001; revised 1 August 2002; accepted 1 August 2002; published 11 December 2002. [1] A method of transfer function-noise (TFN) modeling is presented that operates in continuous time and uses a predefined family of impulse response (IR) functions. The resulting class of models is referred to as predefined IR function in continuous time (PIRFICT). It provides a useful tool for standardized analysis of time series, as it can be calibrated using irregularly spaced data and does not require a model identification phase prior to calibration. In section 2, the discrete Box-Jenkins (BJ) model is presented and transformed into continuous time to obtain the PIRFICT model. The discrete transfer function of a BJ model, which is made up of a variable number of parameters, is replaced by a simple analytical expression that defines the IR function. From the IR function, block response functions are derived that enable the model to handle irregularly spaced data. In the example application, the parameter estimates and performance of the BJ and PIRFICT model are compared using a data set of 15 piezometers and a simulated series. It was found that the estimated transfer and BR functions of both models follow the same general pattern, although the BJ transfer functions are partly irregular. The performance of both models proves to be highly comparable for all piezometers. INDEX TERMS: 1829 Hydrology: Groundwater hydrology; 1833 Hydrology: Hydroclimatology; 1854 Hydrology: Precipitation (3354); 1869 Hydrology: Stochastic processes; 9820 General or Miscellaneous: Techniques applicable in three or more fields; KEYWORDS: groundwater level fluctuations, transfer function-noise, continuous time, time series, impulse response, PIRFICT

Robust filtering for uncertain linear systems with delayed states and outputs

Abstract: Deals with the robust filtering problem for uncertain linear systems with delayed states and outputs. Both time-invariant and time-varying cases are considered. For the time-invariant case, an algebraic Riccati matrix inequality approach is proposed to design a robust H/sub /spl infin// filter such that the filtering process remains asymptotically stable for all admissible uncertainties, and the transfer function from the disturbance inputs to error state outputs satisfies the prespecified H/sub /spl infin// norm upper bound constraint. We establish the conditions under which the desired robust H/sub /spl infin// filters exist, and derive the explicit expression of these filters. For the time-varying case, we develop a differential Riccati inequality method to design the robust filters. A numerical example is provided to demonstrate the validity of the proposed design approach.

Passive and Conservative Continuous-Time Impedance and Scattering Systems. Part I: Well-Posed Systems

Abstract: Let U be a Hilbert space. By an ℒ (U)-valued positive analytic function on the open right half-plane we mean an analytic function which satisfies the condition . This function need not be proper, i.e., it need not be bounded on any right half-plane. We study the question under what conditions such a function can be realized as the transfer function of an impedance passive system. By this we mean a continuous-time state space system whose control and observation operators are not more unbounded than the (main) semigroup generator of the system, and, in addition, there is a certain energy inequality relating the absorbed energy and the internal energy. The system is (impedance) energy preserving if this energy inequality is an equality, and it is conservative if both the system and its dual are energy preserving. A typical example of an impedance conservative system is a system of hyperbolic type with collocated sensors and actuators. We give several equivalent sets of conditions which characterize when a system is impedance passive, energy preserving, or conservative. We prove that a impedance passive system is well-posed if and only if it is proper. We furthermore show that the so-called diagonal transform (which may be regarded as a slightly modified feedback transform) maps a proper impedance passive (or energy preserving or conservative) system into a (well-posed) scattering passive (or energy preserving or conservative) system. This implies that, just as in the finite-dimensional case, if we apply negative output feedback to a proper impedance passive system, then the resulting system is (energy) stable. Finally, we show that every proper positive analytic function on the right half-plane has a (essentially unique) well-posed impedance conservative realization, and it also has a minimal impedance passive realization.

A unified approach to design dead-time compensators for stable and integrative processes with dead-time

Abstract: Proposes a unified 2 degrees of freedom robust dead-time compensator, for both stable and integrative plants. Using the performance and robustness as closed loop specifications simple and effective tuning rules are derived for the proposed controller. A comparative analysis with some structures of dead-time compensators that have been proposed in literature is presented. The analysis is made using the two most typical models of processes with delay that are found in the process industry. The comparative analysis shows that for the cases studied the proposed controller gives better or at least the same performance as the others. It is also shown that the tuning of this structure is simple because the tuning parameters have the usual physical meaning. Some simulation and experimental results illustrate the good performance of the controller.

Sound velocity measurement using transfer function method

Abstract: The transfer function of a piezoelectric transducer, buffer rod and sample assembly is used to measure the sound velocity of solid materials. From the recorded transfer function, pulse echo patterns at frequencies of the passband of the input signal are reproduced after convoluting with monochromatic RF input signals. The time delay is obtained by performing pulse echo overlap and phase comparison measurements on reproduced signals. Results for a single crystal of MgO along the [100] direction from this study are in good agreement with previous measurements but have the advantage of offline data analysis and fast data acquisition.

On identifiability of linear time-delay systems

Abstract: Identifiability analysis is developed for linear time-delay systems with delayed states, control inputs, and measured outputs, all with a finite number of lumped delays. These systems are governed by linear functional differential equations with uncertain time-invariant parameters and delays. It is shown that the transfer function of such a system admits the online identification if a sufficiently nonsmooth input signal is applied to the system. Sufficiently nonsmooth signals are constructively defined by imposing different smoothness properties on the control input and the state of the system. The required nonsmoothness property is verified independently of any underlying time-delay system.

Vector network analyzer applique for adaptive communications in wireless networks

Abstract: A test signal generator at a transmitter station and a facsimile generator at a receiver station go through an acquisition and tracking process which aligns the two signals so that a logical processor can compute the frequency transfer function of the entire propagation path for use in an adaptive, concurrently sent communication signal. The frequency transfer function is conveyed back to the transmit end via a control channel permitting an adaptivity function at the transmit end to influence subsequent selection of communication parameters, among which are typically transmitted data rate, selection of modulation, selection of forward error correcting coding, and selection of frequency band for transmission. The same measurement is conveyed to an adaptivity function at the receive end for use in the communications receiver to select demodulator variables such as gain control, and equalization of amplitude and phase, versus frequency. The adaptivity function also permits interspersing of reverse-direction communications over the same frequency bands in a time-share mode between forward-direction and reverse-direction communication with the measurement signals having to be transmitted in only one direction. An alternate embodiment invention of this type is described which is additionally useful for mobile communications channels. Another variation embodiment is described for pure propagation measurements only, absent conveyance of end-user information.

Estimation of the transfer function of a subscriber loop by means of a one-port scattering parameter measurement at the central office

Abstract: In order to qualify a subscriber loop for xDSL transmission, the channel capacity has to be estimated, which depends on the transfer function of the network. A method is provided to estimate the transfer function of the subscriber loop only measuring the one-port scattering parameter at the central office. We consider three types of networks according to their topology: a single line, a homogeneous network with a bridged tap, and a cascade of two line sections. For each type of network a parametric model is derived of its one-port scattering parameter and transfer function based on the physical line model VUB0. The model for the scattering parameter is used to identify the network based on the corresponding measurements by means of a maximum-likelihood estimator. The estimated parameters are substituted in the transfer function model, which is needed for the capacity estimation. The proposed models and estimators are validated by measurements and simulations. For the measurements, which were performed with a network analyzer, three types of twisted-pair cables were used: British Telecom (BT), Deutsch Telekom (FT), and Belgacom.

Linear Systems Theory

Abstract: This chapter contains sections titled: Linear Shift-Invariant Systems, Convolution, Impulses, Impulse Response of a System, Resistor-Capacitor Circuits, Higher Order Equations, The Heaviside-Laplace Transform, Linear System's Transfer function, The Resistor-Capacitor Circuit (A Second Look), Low-Pass, High-Pass, and Band-Pass Filters

Noise shapers with shared and independent filters and multiple quantizers and data converters and methods using the same

Abstract: A noise shaper including first and second quantizers and first and second feedback paths each providing feedback from a corresponding quantizer output. A loop filter system implements a plurality of transfer functions including a first non-zero transfer function between the first feedback path and an input of the first quantizer, a second non-zero transfer function between the first feedback path and an input of the second quantizer, a third non-zero transfer function between the second feedback path and the input of the first quantizer and a fourth non-zero transfer between the second feedback path and the input the second quantizer.

Identification of Wiener-Hammerstein models using linear interpolation in the frequency domain (LIFRED)

Abstract: A new method to identify the linear subsystems of a Wiener-Hammerstein model through the measurement of the second-order Volterra kernel is proposed. This technique makes use of the symmetry properties of the Volterra kernel and assumes that the frequency response gain and phase between estimated points can be reasonably well approximated by a straight line. The signal applied for the identification is a multisine with properties of no interharmonic distortion. Several advantages of the proposed method over existing ones are discussed, and two simulation examples are presented to illustrate the applicability of the technique. The method is also shown to be robust to noise and distortion in the input signal.

Method and system for digital equalization of non-linear distortion

Abstract: A method is provided for equalization of nonlinear distortion in a distorted signal comprising the steps of: digitizing the distorted signal and passing the digitized distorted signal through an inverse non-linear transfer function to equalize the nonlinear distortion. Other systems and methods are disclosed.

Frequency domain identification of Hammerstein models

Abstract: This paper discusses Hammerstein model identification in frequency domain using the sampled input-output data. By exploring the fundamental frequency and harmonics generated by the unknown nonlinearity, we propose a frequency domain approach and show its convergence for both the linear and nonlinear subsystems in the presence of noise. No a priori knowledge of the structure of the nonlinearity is required and the linear part can be non-parametric.

Computing dominant poles of power system multivariable transfer functions

Abstract: This paper describes a numerical linear algebraic algorithm to compute the dominant poles of multi-input-multi-output (MIMO) high-order transfer functions. The results presented are related to the study of electromechanical oscillations in large electrical power systems, but the algorithm is completely general. The computed dominant poles may then be used to build modal equivalents for MIMO transfer functions of large linear systems, among other applications.

A transfer-function approach to the analysis and design of zero-power controllers for magnetic suspension systems

Abstract: A transfer function approach is applied to the analysis and design of zero-power controllers for magnetic suspension systems. The general structures of controllers achieving zero-power control are derived for both current- and voltage-controlled magnetic suspension systems. For the former type of system, there are two basic approaches: feeding back the velocity signal and introducing a minor feedback of the integral of the current. Both approaches are applicable to the latter type of system. In addition to them, the self-sensing suspension also achieves zero-power characteristics automatically. A direct synthesis method for zero-power control is developed based on the analysis. Several experiments are carried out with a single-degree-of-freedom model. The experimental results show the effectiveness of the proposed synthesis method. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(2): 67–75, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10049

On the synthesis of controllers for a non-overshooting step response

Abstract: In this paper, we show how a two-parameter compensator can always be designed for any Linear Time Invariant (LTI) plant, that does not have a zero at the origin, to render its step response non-overshooting.

Symbolic modeling of periodically time-varying systems using harmonic transfer matrices

Abstract: This paper presents an algorithm for generating symbolic expressions for the harmonic transfer functions of linear periodically time-varying (LPTV) systems, like mixers and PLLs. The harmonic transfer functions characterize the up- and downconversion behavior of the wanted and unwanted signal components. The algorithm, which the authors call Symbolic HTM, is based on the organization of the harmonic transfer functions into a harmonic transfer matrix. This representation allows one to manipulate LPTV systems in a way that is similar to linear time-invariant systems, making it possible to generate symbolic expressions relating the overall harmonic transfer functions to the building block parameters. These expressions can be used as design equations or as parameterized models for use in simulations or synthesis. Comparison of the symbolic models with numerical data shows them to be accurate, even for small numbers of modeling terms.

Robust H∞ control for uncertain linear neutral delay systems

Abstract: This paper deals with the problem of robust H∞ control for uncertain linear neutral delay systems. The parameter uncertainty under consideration is assumed to be norm-bounded time-invariant and appears in all the matrices of the state-space model. The problem we address is the design of memoryless state feedback controllers such that the closed-loop system is asymptotically stable and the H∞ norm of the closed-loop transfer function from disturbance to the controlled output is strictly less than a prescribed positive scalar for all admissible uncertainties. In terms of a linear matrix inequality (LMI), a sufficient condition for the solvability of the above problem is proposed. When this matrix inequality is feasible, an explicit expression for the desired state feedback controller is given. Furthermore, a numerical example is provided to demonstrate the effectiveness of the proposed approach. Copyright © 2002 John Wiley & Sons, Ltd.

Wavelet packet transfer function modelling of nonstationary time series

Abstract: This article shows how a non-decimated wavelet packet transform (NWPT) can be used to model a response time series, Yt, in terms of an explanatory time series, Xt. The proposed computational technique transforms the explanatory time series into a NWPT representation and then uses standard statistical modelling methods to identify which wavelet packets are useful for modelling the response time series. We exhibit S-Plus functions from the freeware WaveThresh package that implement our methodology. The proposed modelling methodology is applied to an important problem from the wind energy industry: how to model wind speed at a target location using wind speed and direction from a reference location. Our method improves on existing target site wind speed predictions produced by widely used industry standard techniques. However, of more importance, our NWPT representation produces models to which we can attach physical and scientific interpretations and in the wind example enable us to understand more about the transfer of wind energy from site to site.

Multi-channel echo cancel method, multi-channel sound transfer method, stereo echo canceller, stereo sound transfer apparatus and transfer function calculation apparatus

Abstract: Stereo sound signals are reproduced directly from loudspeakers (SP(L), SP(R)). By using a sum signal and a difference signal of the stereo sound signals as a reference signal, and according to a cross spectrum calculation of the reference signal with a microphone-collected sound signal, calculation is performed to obtain transfer functions of four sound transfer systems between the loudspeakers (SP(L), SP(R)) and microphones (MC(L), MC(R)). The transfer functions obtained are subjected to inverse Fourier transform to obtain impulse responses, which are set in filter means (40-1 to 40-4) to create echo cancel signals and perform echo canceling. This solves the problem of an indefinite coefficient in the echo cancel technique of a multi-channel sound signal.

Linear Dynamic Systems and Signals

Abstract: Preface. 1. Introduction to Linear Systems. 1.1 Continuous and Discrete Linear Systems and Signals. 1.2 System Linearity and Time Invariance. 1.3 Mathematical Modeling of Systems. 1.4 System Classification. 1.5 MATLAB System Computer Analysis and Design. 1.6 Book Organization. 1.7 Chapter One Summary. 1.8 References. 1.9 Problems. 2. Introduction to Signals. 2.1 Common Signals in Linear Systems. 2.2 Signal Operations. 2.3 Signal Classification. 2.4 MATLAB Laboratory Experiment on Signals. 2.5 Chapter Two Summary. 2.6 References. 2.7 Problems. I. FREQUENCY DOMAIN TECHNIQUES. 3. Fourier Series and Fourier Transform. 3.1 Fourier Series. 3.2 Fourier Transform and Its Properties. 3.3 Fourier Transform in System Analysis. 3.4 Fourier Series in Systems Analysis. 3.5 From Fourier Transform to Laplace Transform. 3.6 Fourier Analysis MATLAB Laboratory Experiment. 3.7 Chapter Three Summary. 3.8 References. 3.9 Problems. 4. Laplace Transform. 4.1 Laplace Transform and Its Properties. 4.2 Inverse Laplace Transform. 4.3 Laplace Transform in Linear System Analysis. 4.4 Block Diagrams. 4.5 From Laplace to the z-Transform. 4.6 MATLAB Laboratory Experiment. 4.7 Chapter Four Summary. 4.8 References. 4.9 Problems. 5. The z Transform. 5.1 The z Transform and Its Properties. 5.2 Inverse of the z Transform. 5.3 The z Transform in Linear System Analysis. 5.4 Block Diagram. 5.5 Discrete-Time Frequency Spectra. 5.6 MATLAB Laboratory Experiment. 5.7 Chapter Five Summary. 5.8 References. 5.9 Problems. II. TIME DOMAIN TECHNIQUES. 6. Convolution. 6.1 Convolution of Continuous-Time Signals. 6.2 Convolution for Linear Continuous-Time Systems. 6.3 Convolution of Discrete-Time Signals. 6.4 Convolution for Linear Discrete-Time Systems. 6.5 Numerical Convolution Using MATLAB. 6.6 MATLAB Laboratory Experiments on Convolution. 6.7 Chapter Six Summary. 6.8 References. 6.9 Problems. 7. System Response in Time Domain. 7.1 Solving Linear Differential Equations. 7.2 Solving Linear Difference Equations. 7.3 Discrete-Time System Impulse Response. 7.4 Continuous-Time System Impulse Response. 7.5 Complete Continuous-Time System Response. 7.6 Complete Discrete-Time System Response. 7.7 Stability of Continuous-Time Linear Systems. 7.8 Stability of Discrete-Time Linear Systems. 7.9 MATLAB Experiment on Continuous-Time Systems. 7.10 MATLAB Experiment on Discrete-Time Systems. 7.11 Chapter Seven Summary. 7.12 References. 7.13 Problems. 8. State Space Approach. 8.1 State Space Models. 8.2 Time Response from the State Equation. 8.3 Discrete-Time Models. 8.4 System Characteristic Equation and Eigenvalues. 8.5 Cayley-Hamilton Theorem. 8.6 Linearization of Nonlinear System. 8.7 State Space MATLAB Laboratory Experiments. 8.8 Chapter Eight Summary. 8.9 References. 8.10 Problems. III. SYSTEMS IN ELECTRICAL ENGINEERING. 9. Signals in Digital Signal Processing. 9.1 Sampling Theorem. 9.2 Discrete-Time Fourier Transform (DFDT). 9.3 Double Sided z-Transform. 9.4 Discrete Fourier Transform. 9.5 Discrete-Time Fourier Series. 9.6 Correlation of Discrete-Time Signals. 9.7 FIR and IIR Filters. 9.8 Laboratory Experiment on Digital Signal Processing. 9.9 Chapter Nine Summary. 9.10 References. 9.11 Problems. 10. Signals in Communication Systems. 10.1 Signal Transmission in Communications. 10.2 Signal Correlation, Energy and Power Spectra. 10.3 Hilbert Transform. 10.4 Ideal Filter. 10.5 Modulation and Demodulation. 10.6 Digital Communication System. 10.7 Communication Systems Laboratory Experiment. 10.8 Chapter Ten Summary. 10.9 References. 10.10 Problems. 11. Linear Electric Circuits. 11.1 Basic Relations. 11.2 First-Order Linear Electrical Circuits. 11.3 Second-Order Linear Electrical Circuits. 11.4 Higher-Order Linear Electrical Circuits. 11.5 Chapter Eleven Summary. 11.6 References. 11.7 MATLAB Laboratory Experiment. 11.8 Problems. 12. Linear Controls Systems. 12.1 The Essence of Feedback. 12.2 Transient Response of Second-Order Systems. 12.3 Feedback System Steady State Errors. 12.4 Feedback System Frequency Characteristics. 12.5 Bode Diagrams. 12.6 Common Dynamic Controllers: PD, PI, PID. 12.7 Laboratory Experiment on Control Systems. 12.8 Chapter Twelve Summary. 12.9 References. 12.10 Problems. Appendices. A. Linear Algebra. B. Some Results from Calculus. C. Introduction to MATLAB. D. Introduction to SIMULINK. Index.

Single-phase PWM AC/AC semiconductor transformer topologies and applications

Abstract: This paper deals with the AC voltage transformation circuits, which contain matrix or matrix-reactance PWM AC fine conditioners. These circuits can be treated as PWM AC/AC semiconductor transformers. In this paper the review of single-phase topologies are presented. The review covers both nonisolated and isolated ones as well as single or two-quadrant structure. Furthermore there are shown the averaged models, their four terminal chain parameters and some exemplary applications are outlined of presented AC voltage transformation circuits as well.