共查询到20条相似文献,搜索用时 140 毫秒
1.
Adalev A.S. Korovkin N.V. Hayakawa M. 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(1):78-91
This paper treats the problem of identification of a linear electric circuit described by an ill-conditioned mathematical model. The identification problem is considered as the problem of model parameters determination by means of processing experimental data measured for the objective circuit. Topological singularities (low-admittance cutsets and low-impedance loops) in a circuit are found to be origins of ill-conditionality of a circuit model. For more in-depth investigation the classification of electric circuits is made in respect to singularities position. It is shown that the first set of experimental data obtained for an ill-conditioned model is useless for getting the required solution of the identification problem. In this case a solution error amounts to a huge value that exponentially increases with growth in condition number of a model matrix. It is found that linear relations between model parameters can be determined in an ill-conditioned problem. Accuracy of these relations does not depend on condition number, but is defined only by measurement precision. An approach named as repeat measurements principle (RMP) and based on linear relations is suggested to solve an ill-conditioned identification problem. A new RMP-based algorithm of linear circuit identification is developed. The algorithm shows a high efficiency and allows us to determine model parameters accurate to measurement precision as applied to any type of reciprocal and nonreciprocal linear circuits. 相似文献
2.
A frequency-domain inverse problem for the nonuniform LCRG transmission line is considered. The parameters of the nonuniform line are interpolated by Chebyshev polynomials, and the Telegraphers equations are solved by a collocation method using the same polynomials. The interpolation coefficients for the unknown parameters are reconstructed by means of Newton-type optimization methods for which the Jacobian matrix has been calculated explicitly. For the reconstruction of one or two parameters, the algorithm is tested on synthetic data, and the necessity to use regularization is discussed. Finally, the algorithm is tested with measured reflection data to reconstruct shunt capacitances with piecewise constant profiles. 相似文献
3.
This paper describes a new algorithm for the analysis of multiconductor transmission lines characterized by frequency-dependent per-unit-length parameters. The proposed model is based on studying telegrapher's equations as a Sturm-Liouville problem. The open-end impedance matrix is expressed in a series form as an infinite sum of matrices of rational functions, derived from the series form of the dyadic Green's function. The rational form of the open-end impedance matrix allows an easy identification of poles and residues and, thus, the development of a reduced-order system of the interconnect. The pole-residue representation can be synthesized in an equivalent circuit or converted into a state-space model, which can be easily embedded into conventional nonlinear circuit SPICE-like solvers. The numerical results confirm the validity of the proposed modeling technique. 相似文献
4.
Ting Long Houjun Wang Shulin Tian Jianguo Huang Bing Long 《Journal of Electronic Testing》2010,26(4):419-428
This paper proposes a test generation algorithm combining genetic algorithm for fault diagnosis on linear systems. Most test
generation algorithms just used a single value fault model. This test generation algorithm is based on a continuous fault
model. This algorithm can improve the treatment of the tolerance problem, including the tolerances of both normal and fault
parameters, and enhance the fault coverage rate. The genetic algorithm can be used to choose the characteristic values. The
genetic algorithm can enhance precision of test generation algorithm especially for complex fitness functions derived from
complex systems under test. The genetic algorithm can also further improve the fault coverage rate by reducing the loop number
of divisions of the initial fault range. The experiments are carried out to show this test generation algorithm with a linear
system and an integrated circuit. 相似文献
5.
Linear bispectrum of signals and identification of nonminimum phaseFIR systems driven by colored input 总被引:1,自引:0,他引:1
The identification of non-minimum-phase finite-impulse-response (FIR) systems driven by third-order stationary colored signals that are not linear processes is addressed. Modeling the linear part of the bispectrum of a signal is discussed. The bispectrum of a signal is decomposed into two multiplicative factors. The linear bispectrum is defined as the factor of the bispectrum that can exactly be modeled using a third-order white-noise-driven linear shift-invariant (LSI) system. The linear bispectrum of the output of the unknown LSI system is represented using an ARMA (autoregressive moving average) model, where the MA parameters correspond to the unknown FIR system impulse response coefficients, and the AR parameters model the linear bispectrum of the input signal. An algorithm for identifying the MA and AR parameters is given. How the proposed method is different from fitting an ARMA model directly to the bicumulants or the bispectrum of the system output is discussed. The method is applied to blur identification 相似文献
6.
This paper is concerned with finite impulse response (FIR) filtering problem for discrete-time linear system which possesses
stochastically jumping parameters described by a finite-state Markov process. An FIR filter processes the measured inputs
and outputs on a finite receding horizon linearly and the filter gain is obtained by minimizing variance of the error between
real state and estimated one. According to inverse computation, system matrix is always assumed to be non-singular. In terms
of engineering application, we must have complete access to the current time jump mode. The FIR filter is presented in batch
form and recursive form, respectively, and Kalman filter is also addressed for comparison. Finally, a numerical example is
given to illustrate the design procedure and their effectiveness. 相似文献
7.
可辨识性分析法是为具有时滞状态,可控输入和可观测输出的线性时滞系统开发的,该系统具有有限数量的集总延迟。文中阐述了提供充分不平稳输入信号时,线性时滞系统传递函数的在线辨识性,可控输入的不连续性对系统的马尔科夫参数可辨识性的决定性,系统传递函数的在线辨识性和系统的马尔科夫参数可辨识性的关系,分析了系统可辨识的条件和必需的输入信号特性,用一个例子说明了系统可辨识性理论的应用。 相似文献
8.
This paper presents the modeling and optimization of compact microwave bandpass filters whose compactness leads to complex and strong stray coupling paths, thereby making the identification of a simple and sparse coupling topology difficult and even impossible. The strong coupling coefficients needed for a broadband response can also cause an ambiguity in identifying the spatial extent of local resonances. An equivalent circuit, which is extracted directly from Maxwell's equations, is used in optimizing these filters. The filter is represented by its global resonances instead of individual resonators. The extraction of the parameters of the equivalent circuit is carried out in the physical frequency and not in the normalized frequency in order to preserve the physicality of the equivalent circuit, especially for asymmetric responses. The technique is successfully applied to the optimization of second-order suspended stripline bandpass filters with one transmission zero either below or above the passband, as well as fourth-order filters with three transmission zeros. A fourth-order filter with three transmission zeros is fabricated and measured. 相似文献
9.
An iterative method for obtaining the distribution of the relative permittivity ϵr(z ) or electrical conductivity σ(z ) of microwave semiconducting materials is presented. The semiconducting material is fitted in a rectangular waveguide which is terminated by a variable short circuit. The reflection coefficients of the system are measured at a single frequency and at different positions of the moving short. The measured coefficients are used in the iterative process of solving the inverse problem by obtaining the functional gradient. The method takes into account continuous and discontinuous profiles 相似文献
10.
《Electron Device Letters, IEEE》1986,7(4):214-218
Analytical models with parameters numerically extracted from I-V data have been used in simulation of MOS circuits. The equations are quasi-physical and the extracted parameters do not normally relate to any single identifiable physical mechanism. We have developed an extraction system that can provide a measure of the level of confidence in the extracted parameters; hence, these parameters may be reliably used in circuit simulation as well as process control. The algorithm described is model independent and can be used for any nonlinear least-squares parameter extraction problem. 相似文献
11.
Computer-Aided Filter Alignment and Diagnosis 总被引:1,自引:0,他引:1
《Microwave Theory and Techniques》1978,26(12):958-963
The cavity resonant frequencies and coupling values of a wide range of bandpass filters, band-reject filters, and equalizers have been determined in situ by computer-adjusting analytic models to fit the scattering parameters measured on an automatic network analyzer. A higher order mode elliptic filter, a dual-mode quasi-elliptic filter, and a dual-mode band-reject filter are presented as examples. The general relationships between mechanical dimensions and circuit parameters are discussed. The circuit adjustment procedure is outlined, and equations for the sensitivity coefficients of several element types are tabulated. 相似文献
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本文以激励系数为设计参量,讨论了直线阵的最坏情况容差最优化问题,给出了直线阵的最坏情况问题,固定容差问题和可变容差问题,研究了它们的新求解方法。固定容差问题将采用正多面体方法来求解,可变容差问题由一个双层迭代算法求解。可变容差问题以实际与理想方向图在容差域中的最大偏差为基准,协调阵列方向图的副(?)电平和激励系数的容差,使阵列方向图的副(?)电平满足所希望的指标要求,同时尽可能地放宽激励系数的容差,文中最后给出了6元和16元直线阵的最坏情况容差最优化的模拟计算结果。 相似文献
15.
The problem of estimating the parameters of 2-D homogeneous moving average (MA) random fields only from output measurements is addressed. A novel computationally efficient algorithm for the estimation of the parameters of a minimum-phase 2-D MA model with a nonsymmetric half-plane (NSHP) region of support (ROS) is proposed. Using the 2-D spectral factorization, relationship between the NSHP MA model parameters and the cepstral coefficients of a 2-D MA random field is considered. Based on this relation, recursive equations are derived so as to estimate the NSHP MA model parameters. It is noteworthy that the proposed algorithm is practical, i.e., it does not require computationally complex processes namely fitting to a high-order autoregressive model, any initial estimates, nor matrix inversion. Performance analysis of the derived algorithm together with an existing method is given for comparison purposes. Index 相似文献
16.
The inverse problem for a nonuniform LCRG transmission line is considered in the frequency domain. Imbedding equations for the reflection and transmission coefficients are derived through the concept of wave-splitting. An optimization approach is applied to reconstruct the line parameters as functions of the position using band-limited reflection and/or transmission data. Exact and explicit expressions for the gradients are derived, and the reconstruction algorithm (based upon a conjugate gradient method) is tested with both clean and noisy data, The problem of the nonuniqueness is also discussed 相似文献
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《IEEE transactions on medical imaging》2010,29(2):217-229
19.
In the application of real-time identification methods for diagnosis or adaptive control of biomedical systems, there is often known model information that is ignored. Constraints on the allowable values of parameters, which may be based on physical considerations, are often neglected because the information does "fit" easily into commonly used parameter-identification algorithms. In this paper a method of incorporating constraints on model parameters is developed. This method is applicable to most recursive parameter-identification algorithms. It enforces linear equality constraints on identified parameters. The use of this method for the real-time identification of autoregressive moving-average-type time series models, subject to parameter constraints, is described in detail. These constraints may be time varying. At each time step, the parameter estimate obtained by a recursive least squares estimator is orthogonally projected onto the constraint surface. This simple idea, when appropriately executed, enhances the output prediction accuracy of estimated parameters. Using constraint information in this way is important when we do not wish to destroy a "natural" parameterization of the model (by an initial projection to incorporate equality constraints), or when we cannot use a single initial model simplification (because the constraints are time varying or involve inputs and outputs). Because it improves output prediction at future times, this method is advantageous for use in predictive adaptive controllers. The use of this algorithm is demonstrated in the identification of electrically stimulated quadriceps muscles in paraplegic human subjects, using percutaneous intramuscular electrodes. The nonlinear steady-state force versus pulsewidth recruitment characteristic of the electrode-muscle system is identified simultaneously with the input-output muscle response dynamics, using a Hammerstein-type model. Knowledge of the recruitment curve's shape is translated into constraints on the identified parameters. This information improves the experimental predictive quality of the identified model. 相似文献
20.
《Signal processing》1993,30(2):199-219
This paper presents several new families of cumulant-based linear equations with respect to the inverse filter coefficients for deconvolution (equalisation) and identification of nonminimum phase systems. Based on noncausal autoregressive (AR) modeling of the output signals and three theorems, these equations are derived for the cases of 2nd-, 3rd and 4th-order cumulants, respectively, and can be expressed as identical or similar forms. The algorithms constructed from these equations are simpler in form, but can offer more accurate results than the existing methods. Since the inverse filter coefficients are simply the solution of a set of linear equations, their uniqueness can normally be guaranteed. Simulations are presented for the cases of skewed series, unskewed continuous series and unskewed discrete series. The results of these simulations confirm the feasibility and efficiency of the algorithms. 相似文献