Effectiveness of data dependence analysis

Data dependence testing is the basic step in detecting loop level parallelism in numerical programs. The problem is undecidable in the general case. Therefore, work has been concentrated on a simplified problem, affine memory disambiguation. In this simpler domain, array references and loops bounds are assumed to be linear integer functions of loop variables. Dataflow information is ignored. For this domain, we have shown that in practice the problem can be solved accurately and efficiently.⁽¹⁾ This paper studies empirically the effectiveness of this domain restriction, how many real references are affine and flow insensitive. We use Larus's llpp system⁽²⁾ to find all the data dependences dynamically. We compare these to the results given by our affine memory disambiguation system. This system is exact for all the cases we see in practice. We show that while the affine approximation is reasonable, memory disambiguation is not a sufficient approximation for data dependence analysis. We propose extensions to improve the analysis. This research was supported in part by a fellowship from AT & T Bell Laboratories and by DARPA contract N00014-87-K-0828.     

平稳小波变换在仿射不变性目标识别中的应用

寻找相对于平移、尺度、旋转、扭曲不变的仿射不变量是现今多尺度分析在模式识别中应用的关键性问题。以文献[4]定义的仿射不变量为基础,构造了基于平稳小波变换的仿射不变量。通过分析,指出原文中所给绝对仿射不变量存在的缺陷,定义了一种新的绝对仿射不变量。试验结果和分析表明,构造的仿射不变量可以更好地用于目标物体识别。     

Inner approximations of domains of attraction for a class of switched systems by computing Lyapunov‐like functions

Domain of attraction plays an important role in control systems analysis, which is usually estimated by sublevel sets of Lyapunov functions. In this paper, based on the concept of common Lyapunov‐like functions, we propose an iteration method for estimating domains of attraction for a class of switched systems, where the state space is divided into several regions, each region is described by polynomial inequalities, and any region has no intersection among with each other. Starting with an initial inner estimate of domain of attraction, we first present a theoretical framework for obtaining a larger inner estimate by iteratively computing common Lyapunov‐like functions. Then, for obtaining a required initial inner estimate of domain of attraction, we propose a higher‐order truncation and linear semidefinite programming–based method for computing a common Lyapunov function. Successively, the theoretical framework is under‐approximatively realized by using S‐procedure and sum‐of‐squares programming, associated with a coordinatewise iteration idea. Finally, we implement our method and test it on some examples with comparisons. These computation and comparison results show the advantages of our method.     

Robust adaptive fuzzy controller for non‐affine nonlinear systems with dynamic rule activation

This paper describes the design of a robust adaptive fuzzy controller for an uncertain single‐input single‐output nonlinear dynamical systems. While most recent results on fuzzy controllers considers affine systems with fixed rule‐base fuzzy systems, we propose a control scheme for non‐affine nonlinear systems and a dynamic fuzzy rule activation scheme in which an appropriate number of the fuzzy rules are chosen on‐line. By using the proposed scheme, we can reduce the computation time, storage space, and dynamic order of the adaptive fuzzy system without significant performance degradation. The Lyapunov synthesis approach is used to guarantee a uniform ultimate boundedness property for the tracking error, as well as for all other signals in the closed loop. No a priori knowledge of an upper bounds on the uncertainties is required. The theoretical results are illustrated through a simulation example. Copyright © 2002 John Wiley & Sons, Ltd.     

一类多项式非线性系统鲁棒H∞控制

针对一类具有多项式向量场的仿射型不确定非线性系统,给出一种基于多项式平方和(sum of squares,SOS)技术的鲁棒H∞状态反馈控制器设计方法.该方法的优点在于控制器的设计避开了直接求解复杂的哈密尔顿-雅可比不等式(Hamilton Jacobi inequality,HJI)和构造Lyapunov函数带来的困难.将鲁棒稳定性分析和控制器设计问题转化为求解以Lyapunov函数为参数的矩阵不等式,该类不等式可利用SOS技术直接求解.此外,在前文基础上研究了基于SOS规划理论与S-procedure技术的局部稳定鲁棒H∞控制器设计方法.最后以非线性质量弹簧阻尼系统作为仿真算例验证该方法的有效性.     

Geometry of Dempster''s rule of combination

In this paper, we analyze Shafer's belief functions (BFs) as geometric entities, focusing in particular on the geometric behavior of Dempster's rule of combination in the belief space, i.e., the set Stheta of all the admissible BFs defined over a given finite domain theta. The study of the orthogonal sums of affine subspaces allows us to unveil a convex decomposition of Dempster's rule of combination in terms of Bayes' rule of conditioning and prove that under specific conditions orthogonal sum and affine closure commute. A direct consequence of these results is the simplicial shape of the conditional subspaces , i.e., the sets of all the possible combinations of a given BF s. We show how Dempster's rule exhibits a rather elegant behavior when applied to BFs assigning the same mass to a fixed subset (constant mass loci). The resulting affine spaces have a common intersection that is characteristic of the conditional subspace, called focus. The affine geometry of these foci eventually suggests an interesting geometric construction of the orthogonal sum of two BFs.     

Illumination Invariant Recognition of Three-Dimensional Texture in Color Images

In this paper, illumination-affine invariant methods are presented based on affine moment normalization techniques, Zernike moments, and multiband correlation functions. The methods are suitable for the illumination invariant recognition of 3D color texture. Complex valued moments (i.e., Zernike moments) and affine moment normalization are used in the derivation of illumination affine invariants where the real valued affine moment invariants fail to provide affine invariants that are independent of illumination changes. Three different moment normalization methods have been used, two of which are based on affine moment normalization technique and the third is based on reducing the affine transformation to a Euclidian transform. It is shown that for a change of illumination and orientation, the affinely normalized Zernike moment matrices are related by a linear transform. Experimental results are obtained in two tests: the first is used with textures of outdoor scenes while the second is performed on the well-known CURET texture database. Both tests show high recognition efficiency of the proposed recognition methods.     

MathQCDSR: A Mathematica package for QCD sum rules calculations

We present a software package written in Mathematica for standard QCD sum rules calculations. Two examples are given to demonstrate how to use the package. One is for the mass spectrum of octet baryons from two-point correlation functions; the other for the magnetic moments of octet baryons in the external-field method. The free package FeynCalc is used to handle the gamma-matrix algebra. In addition to two notebooks for the construction of the QCD sum rules, two corresponding notebooks are provided for a Monte Carlo-based numerical analysis, complete with in-line graphical display of sum rule matching, error distributions, and scatter plots for correlations.

Program summary

Program title: MathQCDSRCatalogue identifier: AEJA_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJA_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 93 897No. of bytes in distributed program, including test data, etc.: 631 481Distribution format: tar.gzProgramming language: MathematicaComputer: PCs and WorkstationsOperating system: Any OS that supports Mathematica. The package has been tested under Windows XP, Macintosh OS X, and LinuxClassification: 11.5External routines: FeynCalc (http://www.feyncalc.org/). It is a freely available Mathematica package for high-energy physics calculations. Here it is used primarily to handle gamma-matrix algebra.Nature of problem: The QCD sum rule method is a nonperturbative approach to solving quantum chromodynamics (QCD), the fundamental theory of the strong force. The approach establishes a direct link between hadron phenomenology and the QCD vacuum structure via a few QCD parameters called vacuum condensates and susceptibilities. It has been widely applied in nuclear and particle physics to gain insight into various aspects of strong-interaction physics.Solution method: First, QCD sum rules are constructed by evaluating correlation functions from two perspectives. On the quark level, it leads to a function of QCD parameters and the Borel mass parameter M. On the hadronic level, it leads to a function of phenomenological parameters and the same M. By numerically matching the two sides over a range in M, the phenomenological parameters can be extracted. The construction involves a large amount of gamma-matrix algebra, Fourier transform, and Borel transform. The matching usually involves searching for minimum χ². We employ a Monte Carlo-based procedure to perform the analysis which allows for realistic error estimates.Restrictions: The package deals with only standard (SVZ) QCD sum rule calculations. It can be easily adapted to handle other variants of the method (like finite-energy sum rules). Due to the use of FeynCalc, two of the notebooks (qcdsr2pt-construction.nb and qcdsr3pt-construction.nb) only run on version 6.0 of Mathematica. The other two can run on any version.Additional comments: The package consists of the following 4 notebooks:

• • 

  qcdsr2pt-construction.nb – This notebook constructs the QCD sum rules for octet baryon masses and outputs them, one particle at a time, to disk in plain text for analysis. For reference, we include all the output files (named Mass-*.txt) as part of the package, totaling 8 files in about 20 lines. The user should generate the outputs on their own computer and check against the supplied ones.

• • 

  qcdsr2pt-analysis.nb – This notebook reads and analyzes the QCD sum rules produced by qcdsr2pt-construction.nb. The user can save the graphics in the analysis to disk in a variety of formats.

• • 

  qcdsr3pt-construction.nb – This notebook constructs the QCD sum rules for the octet baryon magnetic moments and outputs them, one particle at a time, to disk in plain text for analysis. Again, for reference, we include all the output files (named Mag-*.txt), totaling 24 files in about 400 lines. The user should generate the outputs on their own computer and check against the supplied ones to make sure the program is running properly.

• • 

  qcdsr3pt-analysis.nb – This notebook reads and analyzes the QCD sum rules produced by qcdsr3pt-construction.nb. The user can save the graphics in the analysis to disk in a variety of formats.

Each notebook can be run separately, apart from the simple interface between the construction and analysis programs via plain text files written to disk.Running time: For mass calculations, qcdsr2ptconstruction.nb and qcdsr2pt-analysis.nb take about a minute each to run on a laptop. For magnetic moment calculations, qcdsr3pt-construction.nb can take up to 10 minutes for a given particle, and qcdsr3pt-analysis.nb typically a few minutes, depending on the number of Monte Carlo samples.     

Permutation equivalence of cubic rotation symmetric Boolean functions

Rotation symmetric Boolean functions have been extensively studied for about 15 years because of their applications in cryptography and coding theory. Until recently little was known about the basic question of when two such functions are affine equivalent. The simplest case of quadratic rotation symmetric functions which are generated by cyclic permutations of the variables in a single monomial was only settled in 2009. For the much more complicated case of cubic rotation symmetric functions generated by a single monomial, the affine equivalence classes under permutations which preserve rotation symmetry were determined in 2011. It was conjectured then that the cubic equivalence classes are the same if all nonsingular affine transformations, not just permutations, are allowed. This conjecture is probably difficult, but here we take a step towards it by proving that the cubic affine equivalence classes found in 2011 are the same if all permutations, not just those preserving rotation symmetry, are allowed. The needed new idea uses the theory of circulant matrices.     

扩展词组数最小法的假名汉字转换

本文描述了改进后的“词组最小法”、并提出了新算法。它被名为“扩展词组最小法”。重新定义了句子中词组的计算方法。为了实现此目标,从始读到句子假名的全部读入,将词库查询及语法检查的结果以“树”型数据加以保留。采用上述算法后,以假名文字为单位的变换率可达95. 8 %;以词组为单位的变换率可达88. 9 %。     

一种新的统计仿射不变量

本文在充分分析了现有各种仿射不变量的基础上，提出了一种新的统计仿射不变量，它对于发生尺度变化、旋转、扭曲和平移的目标具有不变性。实验结果表明，相对于传统的仿射不变量，在目标轮廓分割不完整或噪声污染的情况下，仍能够保持较高的稳健性，同时克服了基于轮廓的小波方法和傅立叶级数等方法对目标轮廓出现缺陷时的不足，
，在图像目标识别中具有实用价值。     

基于平面与直线的仿射重建

首先给出了无穷远平面的单应矩阵以及仿射重建算法，然后从数学上严格证明了下述命题：在变参数模型下，如果场景中含有一张平面和一对平行直线，或者场景中含有两张平行平面，则从两个平移视点下的图像均可以线性地对场景进行仿射重建；文章同时指出：如果场景中包含一对平行平面和一对平行直线，则从两个一般运动视点也可以线性地重建场景的仿射几何．大量的模拟和真实图像实验表明，该线性仿射重建算法是正确的，同时具有较高的重建精度和鲁棒性．     

An efficient algorithm for optimal control of PWA systems with polyhedral performance indices

We present an algorithm for the computation of explicit optimal control laws for piecewise affine (PWA) systems with polyhedral performance indices. The algorithm is based on dynamic programming (DP) and represents an extension of ideas initially proposed in Kerrigan and Mayne [(2003). Optimal control of constrained, piecewise affine systems with bounded disturbances. In Proceedings of the 41st IEEE conference on decision and control, Las Vegas, Nevada, USA, December], and Baoti? et al. [(2003). A new algorithm for constrained finite time optimal control of hybrid systems with a linear performance index. In Proceedings of European control conference, Cambridge, UK, September]. Specifically, we show how to exploit the underlying geometric structure of the optimization problem in order to significantly improve the efficiency of the off-line computations. An extensive case study is provided, which clearly indicates that the algorithm proposed in this paper may be preferable to other schemes published in the literature.     

PERFORMANCE ANALYSIS OF CONTROL SYSTEMS WITH INPUT CONSTRAINTS VIA PIECEWISE QUADRATIC STORAGE FUNCTIONS

Input constraints exist in almost all real‐world systems and frequently cause unexpected undesirable phenomena, such as performance degradation or instability. Although many studies have focused on this problem, precise performance analysis of whole control systems with constraints is still difficult. In this paper, such control systems are represented as piecewise affine systems, and global and local L₂ incremental gain analysis methods via piecewise quadratic storage functions are presented.     

Analysis of discrete-time piecewise affine and hybrid systems

In this paper, we present various algorithms both for stability and performance analysis of discrete-time piece-wise affine (PWA) systems. For stability, different classes of Lyapunov functions are considered and it is shown how to compute them through linear matrix inequalities that take into account the switching structure of the systems. We also show that the continuity of the Lyapunov function is not required in discrete time. Moreover, the tradeoff between the degree of conservativeness and computational requirements is discussed. Finally, by using arguments from the dissipativity theory for nonlinear systems, we generalize our approach to analyze the l₂-gain of PWA systems.     

Model-checking software library API usage rules

Modern software increasingly relies on using third-party libraries which are accessed via application programming interfaces (APIs). Libraries usually impose constraints on how API functions can be used (API usage rules) and programmers have to obey these API usage rules. However, API usage rules often are not well documented or documented informally. In this work, we show how to use the SCTPL and SLTPL logics to precisely and formally specify API usage rules in libraries, where SCTPL/SLTPL can be seen as an extension of the branching/linear temporal logic CTL/LTL with variables, quantifiers and predicates over the stack. This allows library providers to formally describe API usage rules without knowing how their libraries will be used by programmers. We propose an automated approach to check whether programs using libraries violate API usage rules or not. Our approach consists in modeling programs as pushdown systems (PDSs) and checking API usage rules by SCTPL/SLTPL model-checking for PDSs. To make the model-checking procedure more efficient and precise, we propose an abstraction that reduces drastically the size of the program model and integrate may-alias analysis into our approach to reduce false alarms. Moreover, we characterize two sublogics rSCTPL and rSLTPL of SCTPL and SLTPL that are preserved by the abstraction. We implement our techniques in a tool and apply the tool to check several open-source programs. Our tool finds several previously unknown bugs in several programs. The may-alias analysis avoids most of the false alarms that occur using SCTPL or SLTPL model-checking techniques without may-alias analysis.     

Stabilizing low complexity feedback control of constrained piecewise affine systems

Piecewise affine (PWA) systems are powerful models for describing both non-linear and hybrid systems. One of the key problems in controlling these systems is the inherent computational complexity of controller synthesis and analysis, especially if constraints on states and inputs are present. In addition, few results are available which address the issue of computing stabilizing controllers for PWA systems without placing constraints on the location of the origin.This paper first introduces a method to obtain stability guarantees for receding horizon control of discrete-time PWA systems. Based on this result, two algorithms which provide low complexity state feedback controllers are introduced. Specifically, we demonstrate how multi-parametric programming can be used to obtain minimum-time controllers, i.e., controllers which drive the state into a pre-specified target set in minimum time. In a second segment, we show how controllers of even lower complexity can be obtained by separately dealing with constraint satisfaction and stability properties. To this end, we introduce a method to compute PWA Lyapunov functions for discrete-time PWA systems via linear programming. Finally, we report results of an extensive case study which justify our claims of complexity reduction.     

An efficient procedure for finding best compromise solutions to the multi-objective assignment problem

In this paper, we consider the problem of determining a best compromise solution for the multi-objective assignment problem. Such a solution minimizes a scalarizing function, such as the weighted Tchebychev norm or reference point achievement functions. To solve this problem, we resort to a ranking (or k-best) algorithm which enumerates feasible solutions according to an appropriate weighted sum until a condition, ensuring that an optimal solution has been found, is met. The ranking algorithm is based on a branch and bound scheme. We study how to implement efficiently this procedure by considering different algorithmic variants within the procedure: choice of the weighted sum, branching and bounding schemes. We present an experimental analysis that enables us to point out the best variants, and we provide experimental results showing the remarkable efficiency of the procedure, even for large size instances.     

基于仿射变换和线性回归的3D人脸姿态估计方法

提出了一种由仿射变换关系到线性回归的3D人脸空间姿态估计方法。即跟踪到人脸特征点后,根据仿射变换关系得到人脸姿态的粗估计值,以这个粗估计值作为人脸姿态的初始值,再通过线性回归迭代求得人脸姿态的精确值。实验结果表明,该方法在较大的姿态变化范围内,具有良好的估计精确度和鲁棒性。