On Two Problems in the Generation of Program Test Paths

In this paper we analyze the complexity of algorithms for two problems that arise in automatic test path generation for programs: the problem of building a path through a specified set of program statements and the problem of building a path which satisfies impossible-pairs restrictions on statement pairs. These problems are both reduced to graph traversal problems. We give an efficient algorithm for the first, and show that the second is NP-complete.     

Cache-Aware Multigrid Methods for Solving Poisson's Equation in Two Dimensions

Conventional implementations of iterative numerical algorithms, especially multigrid methods, merely reach a disappointing small percentage of the theoretically available CPU performance when applied to representative large problems. One of the most important reasons for this phenomenon is that the need for data locality due to poor main memory latency and limited bandwidth is entirely neglected by many developers designing numerical software. Only when most of the data to be accessed during the computation are found in the system cache (or in one of the caches if the machine architecture comprises a cache hierarchy) fast program execution can be expected. Otherwise, i.e. in case of a significant rate of cache misses, the processor must stay idle until the necessary operands are fetched from main memory, whose cycle time is in general extremely large compared to the time needed to execute a floating point instruction. In this paper, we describe program transformation techniques developed to improve the cache performance of two-dimensional multigrid algorithms. Although we merely consider the solution of Poisson's equation on the unit square using structured grids, our techniques provide valuable hints towards the efficient treatment of more general problems. Received January 31, 1999; revised October 17, 1999     

On Digital Distance Transforms in Three Dimensions

Digital distance transforms in 3D have been considered for more than 10 years. However, not all of the complexities involved have been unravelled. In this paper the complete geometry and equations for 3D transforms based on a 3 × 3 × 3 neighborhood of local distances are given. A new type of valid distance transforms (DTs) have been discovered. The optimal solutions are computed, where optimality is defined as minimizing the maximum difference from the true Euclidean distance, thus making the DTs as direction independent as possible. The well-known 〈3, 4, 5〉 DT is confirmed as the most practical weighted DT, where the distance is set to 3 between neighbors sharing an area, 4 between neighbors sharing an edge, and 5 between neighbors sharing a point.     

PB中关于数据窗口的两个问题

PowerBuilder是美国著名的数据库应用开发工具生产商Sybase公司的产品,而数据窗口是PowerBuilder的核心技术和专利产品,学好PowerBuilder关键是要掌握数据窗口技术。作者就数据窗口连接数据库的三种方法及获得和修改数据窗口对象中属性和数据的方法做了总结与阐述。     

PB中关于数据窗口的两个问题

PowerBuilder是美国著名的数据库应用开发工具生产商Sybase公司的产品,而数据窗口是PowerBuilder的核心技术和专利产品,学好PowerBuilder关键是要掌握数据窗口技术.作者就数据窗口连接数据库的三种方法及获得和修改数据窗口对象中属性和数据的方法做了总结与阐述.     

高维数据挖掘在入侵检测中的应用

本文讨论一种在数据挖掘的基础上的入侵检测系统的构建,建立了高维数据挖掘和分类的挖掘引擎,利用数据挖掘的方法从大量的攻击数据中提取有攻击行为的特征,并用于监测,实现知识的自动获取和学习。     

On Dimensions of Linear Discrete Dimension-unbounded Systems

This letter investigates the variance of state dimensions of linear discrete dimension-unbounded systems, which are a class of cross-dimensional systems. First, the dimensional relationship of states, initial values and system matrices of some special cases is discussed. Then, for the general case, to directly calculate the transition time and state dimensions after the transition time, an algorithm is established on the basis of the iterative time, dimensions of initial values and system matrices. Finally, there is an illustrative example to show the effectiveness of these obtained results.

     

LPR中两个问题的MATLAB解决方案

变形车牌矫正和复杂牌照的文字区域提取是LPR中两个比较重要的问题，本文运用MATLAB,通过Radon变换检测牌照的角度,使用旋转与错切变换相结合的方法来解决变形牌照矫正问题;通过对牌照区域进行颜色提取从而消除非牌照颜色的干扰,解决复杂牌照的文字区域提取问题。     

基于DC和AC分量的二维数字水印算法

提出一种新的二维数字水印算法,该算法先把原始图像分块DCT,再对水印图像分块DCT,取每一图像块的直流系数和前12个DCT低频交流系数,分别构成水印信号的直流分量和交流分量。利用能量比确定各个子块的直流拉伸因子和交流拉伸因子。水印信号的直、交流分量以不同的能量分别嵌入到原始图像块DCT域的DC分量和AC分量中。实验结果表明,该算法具有良好的不可见性和稳健性。     

基于DC和AC分量的二维数字水印算法

提出一种新的二维数字水印算法,该算法先把原始图像分块DCT,再对水印图像分块DCT,取每一图像块的直流系数和前 12个DCT低频交流系数,分别构成水印信号的直流分量和交流分量.利用能量比确定各个子块的直流拉伸因子和交流拉伸因子.水印信号的直、交流分量以不同的能量分别嵌入到原始图像块DCT域的DC分量和AC分量中.实验结果表明,该算法具有良好的不可见性和稳健性.     

Two Undecidable Problems of Analysis

Minds and Machines -     

Variational Framework for FIC Formulations in Continuum Mechanics: High Order Tensor-Derivative Transformations and Invariants

This is part of an article series on a variational framework for continuum mechanics based on the Finite Increment Calculus (FIC). The formulation utilizes high order derivatives of the classical fields of continuum mechanics integrated over control regions to construct stabilizing modification terms. Fields may include displacements, body forces, strains, stresses, pressure and volumetric strains. To support observer-invariant FIC formulations, we have catalogued field transformation equations as well as sets of linear and quadratic invariants of fields and of their derivatives up to appropriate order. Attention is focused on the two-dimensional case of a body in plane strain under the drilling-rotation transformation group. Results are presented for displacement and body-force derivatives of orders up to 4, and for stress, strain, pressure and volumetric strain derivatives of order up to 3. The material assembled here is self-contained because this catalog is believed to be useful beyond FIC applications; for example gradient-based, nonlocal constitutive models of multiscale mechanics and physics that involve finite characteristic dimensions analogous to FIC steplengths.     

对OFDM和SC-CP中两个问题的分析

OFDM系统中IFFT模块和FFT模块的位置问题和SG-CP系统中时域交织及比特交织对系统性能的影响做了理论分析。仿真结果表明，OFDM系统中的IFFT模块和FFT模块的位置是可以交换的。同时，在SC-CP系统中只使用简单时域交织并不能提高系统性能。但是，如果在编码后比特交织，然后做时域交织是可以提高系统性能的。     

Tailored Finite Point Method for a Singular Perturbation Problem with Variable Coefficients in Two Dimensions

In this paper, we propose a tailored-finite-point method for a type of linear singular perturbation problem in two dimensions. Our finite point method has been tailored to some particular properties of the problem. Therefore, our new method can achieve very high accuracy with very coarse mesh even for very small ε, i.e. the boundary layers and interior layers do not need to be resolved numerically. In our numerical implementation, we study the classification of all the singular points for the corresponding degenerate first order linear dynamic system. We also study some cases with nonlinear coefficients. Our tailored finite point method is very efficient in both linear and nonlinear coefficients cases.     

On the Convergence of a Spline Method for Singular Two Point Boundary Value Problems Arising in Physiology

The second order spline method developed by Iyengar et al. [11] for the problems $$eqalign{ x^{-alpha}(x^alpha y^prime)^prime & = f(x,y),quad 0     

On the Theories and Numerics of Continuum Models for Adaptation Processes in Biological Tissues

Computational continuum mechanics have been used for a long time to deal with the mechanics of materials. During the last decades researches have been using many of the theoretical models and numerical approaches of classical materials to deal with biological tissue which, in many senses, are a much more sophisticated material. We aim to review the last achievements of continuum models and numerical approaches on adaptation processes in biological tissues. In this review, we are looking, in particular, at growth in terms of changes of density and/or volume as, e.g., in collagen remodeling, wound healing, arterial thickening, etc. Furthermore, we point out some of the most relevant limitations of the current state-of-the-art in terms of these well established computational continuum models. In connection with these limitations, we will finish by discussing the trend lines of future work in the field of modeling biological adaptation, focusing on the computational approaches and mechanics that could overcome the current drawbacks. We would also like to attract the attention of all those researchers in classical materials (metal, alloys, composites, etc), to point out how similar the continuum and computational models between our fields are. We hope we can motivate them for getting their expertize in this challenging field of research.     

Information Loss of the Mahalanobis Distance in High Dimensions: Application to Feature Selection

When an infinite training set is used, the Mahalanobis distance between a pattern measurement vector of dimensionality D and the center of the class it belongs to is distributed as a chi^2 with D degrees of freedom. However, the distribution of Mahalanobis distance becomes either Fisher or Beta depending on whether cross validation or resubstitution is used for parameter estimation in finite training sets. The total variation between chi^2 and Fisher, as well as between chi^2 and Beta, allows us to measure the information loss in high dimensions. The information loss is exploited then to set a lower limit for the correct classification rate achieved by the Bayes classifier that is used in subset feature selection.