Origin of 1/f noise in bipolar transistors

In planar n-p-n transistors fabricated in IC technology, the dependence of 1/fnoise on the base current density jB, the base width WB, and the emitter area FEwas measured. The power spectrumS_{iB}(f)of the base current fluctuations iBcan be represented by the empirical relationS_{iB} = const. jmin{B}max{gamma} cdot Fmin{E}max{beta} cdot wmin{B}max{-1} cdot f^{-1}where1 leq gamma leq 2and β has been found to be 1.3 or 2. The results of measurements on gate-controlled devices indicate that 1/fnoise cannot be explained by McWhorter's surface model. Therefore, a new model is proposed which assumes resistance fluctuations in the base region as the cause of 1/fnoise in bipolar transistors. The model establishes the relation forS_{iB}(f)as well as the magnitude of the coefficients β and γ.     

Index two linear time varying singular systems of differential equations

Linear time varying singular systems of differential equations of the formA(t)x(t) + B(t)x(t)=f(t) whereA(t) is singular and the system has index at most two are considered. Recent results on their analytic solution are improved on. Examples are given that show these results are not easily extended.This work was supported in part by the National Science Foundation under Grant No. DMS-8318026 and the Air Force Office of Scientific Research under Grant No. 84-0240.     

On the design of output feedback for finite and infinite pole assignment in singular systems with application to the control problem of constrained robots

For a given square solvable singular systemEx=Ax+Bu with outputy=Cx we present a useful chain of transformations, acting on the quadruplet {E, A, B C}. The application of this chain enables the design of an output feedback for obtaining (provided the problem is solvable) finite and infinite pole assignment with regularity. Special consideration is given to the control problem of a holonomically constrained robot, and fundamental results concerning the singular model which is obtained by a (local) linearization of the equations have been established of the constrained mechanical system about a nominal trajectory. In particular we consider the structure of an output map which enables a simple closed-loop configuration for obtaining design objectives with regards to the resulting linear singular system. This research was partly supported by the Paul Ivanier Center for Robotics and Production Management, Ben Gurion University of the Negev.     

Step-by-step decoding of the Bose-Chaudhuri- Hocquenghem codes

A new and conceptually simple decoding procedure is developed for all of the cyclic Bose-Chaudhuri-Hocquenghem codes. Iftis the number of errors guaranteed correctable by the Bose-Chaudhuri bound, then any pattern oftor fewer errors can be corrected in a step-by-step manner using this procedure. In the binary case, the method requires only the determination of whether at times tmatrix is singular. In the general case, the method requires only the determination of whether at times tmatrix and a(t+1) times (t+1)matrix are simultaneously singular. Circuits to implement the algorithm are developed and two detailed examples are given. Finally, the step-by-step procedure is compared to other known methods for decoding the Bose-Chaudhuri-Hocquenghem codes.     

Numerically stable algorithm for standard controllability form determination

A procedure to determine the standard controllability form of a matricial pair (A, B), using orthogonal similarity transformations, is proposed. All rank computations are performed via singular value decompositions. The procedure can be used to test controllability of the pair (A, B) or in the model reduction of linear systems.     

Very low-frequency measurements of flicker noise in silicon planar transistors

The noise-power spectrum from 0.01 to 10?4 Hz is measured using a progressive bandwidth-measuring method. The 1/f law is verified, and it is found that flicker noise may be represented in the common-emitter configuration by an input current generator iB given in terms of current collector Ie and current gain ? by iB2? = C?f/f Ie3/2/?2     

Solving the generalized eigenvalue problem with singular forms

Two methods are developed for computing the generalized eigenvalues and eigenvectors associated with the matrix pair {A, B}, where B is a singular Hermitian matrix and A is a matrix, not necessarily Hermitian, the range space of which is a subset of the range space of B. Conventional methods of solution break down for this case. An application is described based on the recently reported ESPRIT algorithm, a method of high-resolution direction-of-arrival estimation.     

Formulation and solution of structured total least norm problemsfor parameter estimation

The total least squares (TLS) method is a generalization of the least squares (LS) method for solving overdetermined sets of linear equations Ax≈b. The TLS method minimizes ∥[E|-r]∥_F, where r=b-(A+E)x, so that (b-r)∈Range (A+E), given A∈C^m×n, with m⩾n and b∈C^m×1. The most common TLS algorithm is based on the singular value decomposition (SVD) of [A/b]. However, the SVD-based methods may not be appropriate when the matrix A has a special structure since they do not preserve the structure. Previously, a new problem formulation known as structured total least norm (STLN), and the algorithm for computing the STLN solution, have been developed. The STLN method preserves the special structure of A or [A/b] and can minimize the error in the discrete L_p norm, where p=1, 2 or ∞. In this paper, the STLN problem formulation is generalized for computing the solution of STLN problems with multiple right-hand sides AX≈B. It is shown that these problems can be converted to ordinary STLN problems with one right-hand side. In addition, the method is shown to converge to the optimal solution in certain model reduction problems. Furthermore, the application of the STLN method to various parameter estimation problems is studied in which the computed correction matrix applied to A or [A/B] keeps the same Toeplitz structure as the data matrix A of [A/B], respectively. In particular, the L₂ norm STLN method is compared with the LS and TLS methods in deconvolution, transfer function modeling, and linear prediction problems     

Enhanced time-frequency analysis of VAG signals by segmentation and denoising algorithm

An enhanced time-frequency analysis of vibroarthrographic (VAG) signals is devised using segmentation by the dynamic time warping and denoising algorithm by the singular value decomposition, and the normal and abnormal VAG signals are classified by a back-propagation neural network. A total of 1408 VAG segments (normal 1031, abnormal 377) were used for evaluating the performance of the devised method and, consequently, the average accuracy was 92.0 + 1.6% (ranging from 89.4 to 95.4). This method could be used as a complementary tool for the non-invasive diagnosis of joint disorders.     

Stability tests for singular cases of discrete systems

The well-known Jury and Blanchard's stability test for discrete systems is with an array of (2n–3) rows of elements. Raible simplified Jury and Blanchard's array to (n+1) rows by introducing an additional element at the end of each row. Chen and Chan recently derived a Liapunov function through Schwarz' transform to prove the criterion directly and to produce a very compact form. The purpose of this paper is to explore the various singular cases by using the newly established Chen-Chan criterion. Some existing methods for studying singular cases are re-examined under the light shed by Chen and Chan. A by-product is to define and to determine the relative stability of discrete systems.This research was partially supported by the U.S. Army Missile Command under Contract DAAH 01-86-C-A048.     

一种基于奇异值特征的神经网络人脸识别新途径

本文在Z Hong等人使用的奇异值分解(SVD)基础上,将人脸图像矩阵的奇异值作为识别特征,解决了奇异值处理、神经网络训练策略和竞争选择问题;运用BP网络进行识别,提出了一种基于奇异值特征的神经网络人脸识别新方法.基于ORL人脸数据库的多次反复实验结果表明,在大样本情况下,识别方法具有实现简单、识别速度快、识别率高的特点,为人脸的实时识别提供了一种新途径.     

基于方向场DFT和角点检测的指纹奇异点定位

提出了一种新的基于方向场离散傅里叶变换（DFT, Discrete Fourier transform）和角点检测的指纹奇异点定位算法。对方向场做DFT变换到频域处理能更好的压制噪声。通过角点提取、基于目标标注的聚类方法来定位指纹图像的奇异点。从方向场的极/零点模型出发,导出了若干新颖的性质,说明了奇异点和角点之间的关系。实验结果表明,奇异点定位精度有所提高,处理时间更短。     

Optimal regulator with bounds on the derivative of the input

The problem of minimising ?t0?(x?Qx + u?Ru)dt for a completely controllable linear system, subject to the constraint |u?|< 1, is shown to be equivalent to a singular optimal-control problem; the known singular theory is then used to obtain the optimal control.     

基于奇异值分解的TD-HSPA+系统赋形算法研究

文章提出了一种适用于多径信道的基于奇异值分解(SVD)的波束赋形算法,并结合64正交幅度调制(QAM)高阶调制算法,对时分双工增强高速分组接入(TD-HS-PA+)系统性能进行仿真研究。文章重点分析了市区宏小区和市区微小区场景下SVD算法和特征向量法(EBB)的性能差异以及引入64QAM后的系统性能增益。系统级仿真结果表明,基于SVD的波束赋形算法相比传统EBB算法能够明显提升扇区平均吞吐量,引入64QAM后吞吐量能够得到进一步提升。     

Two-dimensional singular vector elements for finite-elementanalysis

The finite-element method (FEM) exhibits a reduced convergence rate when used for the analysis of geometries containing sharp edges where the electromagnetic field is singular. The convergence of the method can be-improved by introducing singular elements that model analytically predicted singular behavior. A number of authors have developed singular elements that are compatible with the scalar FEM. In this paper, we propose a new singular element that is compatible with edge-based vector finite elements and can cope with any order of singularity while preserving the sparsity of the FEM equations. Edge-based singular elements more correctly model singular fields and thus require fewer unknowns, while avoiding the introduction of spurious modes in the numerical solution. Numerical results verify that the convergence of the FEM is significantly improved     

A new eigenstructure method for sinusoidal signal retrieval inwhite noise: estimation and pattern recognition

A new approach, in a framework of an eigenstructure method using a Hankel matrix, is developed for sinusoidal signal retrieval in white noise. A closed-form solution for the singular pairs of the matrix is defined in terms of the associated sinusoidal signals and noise. The estimated sinusoidal singular vectors are applied to form the noise-free Hankel matrix. A pattern recognition technique is proposed for partitioning signal and noise subspaces based on the singular pairs of the Hankel matrix. Three types of cluster structures in an eigen-spectrum plot are identified: well-separated, touching, and overlapping. The overlapping, which is the most difficult case, corresponds to a low signal-to noise ratio (SNR). Optimization of Hankel matrix dimensions is suggested for enhancing separability of cluster structures. Once features have been extracted from both singular value and singular vector data, a fuzzy classifier is used to identify each singular component. Computer simulations have shown that the method is effective for the case of “touching” data and provides reasonably good results for a sinusoidal signal reconstruction in the time domain. The limitations of the method are also discussed     

Electron states in single-layer graphene containing short-range defects: The potential separable in the momentum representation

Electron states in single-layer graphene containing short-range defects are studied. A model potential concentrated on a circle and asymmetric with respect to the band number is treated. The study is carried out for the (2 + 1)-dimensional Dirac equation with a potential separable in the angular momentum representation. The characteristic equation derived in the study for bound and resonance states is compared with the equation derived previously for the same system by another method. The momentum representation used in this study provides a means for satisfactorily regularizing the Hadamard-incorrect problem with a singular potential. The method developed here is applied to regularization of the previously derived formulas for the scattering parameters and conductivity in graphene.     

奇异值分解带通滤波背景抑制和去噪

针对可见光图像弱小目标检测中的背景抑制和去噪问题,提出了奇异值分解(Singular Value Decomposition,SVD)带通滤波新方法.首先分析了图像奇异值与目标、噪声和图像背景的关系,结果表明奇异值的高序部分更多地反映图像噪声,中序部分更多地反映目标性质,而低序部分更多地反映图像背景.以此为依据提出了SVD-I型和SVD-II型两种带通滤波器,并给出了奇异值曲线转折点法和门限准则法两种滤波器参数确定方法.实验表明SVD带通滤波能有效抑制图像背景,去除噪声,进而提高弱小目标的信噪比.     

Singular value decomposition-based reconstruction algorithm forseismic traveltime tomography

A reconstruction method is given for seismic transmission traveltime tomography. The method is implemented via the combinations of singular value decomposition, appropriate weighting matrices, and variable regularization parameter. The problem is scaled through the weighting matrices so that the singular spectrum is normalized. Matching the normalized singular values, a regularization parameter varies within the interval [0, 1], and linearly increases with singular value index from a small, initial value rather than a fixed one to eliminate the impacts of smaller singular values' components. The experimental results show that the proposed method is superior to the ordinary singular value decomposition (SVD) methods such as truncated SVD and Tikhonov (1977) regularization.     

A stabilization algorithm for multichannel multidimensional linearprediction of imagery

The authors have investigated the stability problems observed in multichannel multidimensional linear predictive modeling of images. It is known that based on a positive definite autocorrelation matrix, singular values of the matrix H=delta(i+1)xHerm (delta(i+1)) must lie inside the unit circle for a stable solution, where delta(i+1 ) is the normalized partial correlation matrix and Herm denotes the Hermitian operator. The authors have developed a two-step stabilization method to obtain stabilized linear prediction coefficients for short term analysis windows formed digitized images. The authors have modified the multichannel Levinson recursion algorithm to include this stability procedure. They have tested the algorithm on numerous images commonly used in image coding and the results are very impressive.