A Decomposition Method for Computing System Reliability by a Boolean Expression

A substitutionary decomposition method for computing the reliability of a redundant system S given by a Boolean expression is proposed, System S is decomposed into two subsystems S(x) and S(x?) according to up-and down-states of its keystone variable x. This is repeated until all terms become s-independent in each decomposed subsystem. A criterion for choosing the keystone variable and a property which saves computation time are obtained.     

A Method for Computing Complex System Reliability

The computation of reliability becomes quite tedious when one has to deal with a non series-parallel system. In this paper a proposed method is developed by taking the system as a probabilistic graph in which a component of the system is represented by a branch. The proposed method is composed of three phases: Phase 1 involves the reduction of all series, parallel, and series-parallel components to an irreducible non series-parallel system. In Phase 2 the algorithm enumerates all possible paths from the source to the sink of the graph. Phase 3 then computes the system reliability based on the path information obtained in Phase 2. An example of the use of the method to compute system reliability is given.     

Bayesian Decomposition Method for Computing the Reliability of an Oriented Network

For a nonoriented network, Bayesian decomposition is straightforward and well known. A keystone element is assumed perfect (shorted), then failed (open) and the reliabilities of the two subnetworks are calculated. But for an oriented network, when the keystone element is assumed perfect, it cannot always be shorted (the 2 nodes brought together), because even a perfect element still retains its orientation. A technique for choosing keystone elements is proposed.     

基于可重构计算系统的矩阵三角化分解硬件并行结构研究

可重构计算系统成为加速计算密集型应用的重要选择之一.在众多受到关注的计算密集型问题中,矩阵三角化分解作为典型的基础类应用始终处于研究的核心地位,在求解线性方程组、求矩阵特征值等科学与工程问题中有重要的研究价值.本文面向矩阵三角化分解中共有的三角化计算过程,通过分析该过程的线性计算规律,提出一种适于硬件并行实现的子矩阵更新同一化算法及矩阵三角化计算FPGA (Field Programmable Gate Array)并行结构.针对LU矩阵三角化分解在并行结构模板上的高性能实现及优化方法开展了研究.理论分析表明,该算法针对矩阵三角化计算过程具有更高的数据并行性与流水并行性;实验结果表明,与通用处理器的软件实现相比,根据该算法实现的矩阵三角化分解FPGA并行结果在关键计算性能上可以取得10倍以上的加速比.     

一种快速非负矩阵分解的人脸识别算法

用于人脸识别的非负矩阵分解算法,虽可提高图像识别率,但因其是通过迭代方法同时计算出基矩阵和系数矩阵,故当迭代次数较多时,计算过程耗时长。文中将二维线性判别分析方法与非负矩阵分解方法融合,提出了一种快速的双边二维非负矩阵分解算法。通过在AR、Ｙale人脸数据库上的实验结果显示,较二维双边非负矩阵分解算法,文中算法不仅使得训练时间大幅减少,而且识别率也有所提高。     

基于超几何分解的随机运算系统分析方法

基于Bernoulli分布的方差及期望传递方程一直是随机运算系统的数学基础,针对这种传统分析方法在实际应用中的不准确性和片面性,该文提出一种全新的数学方法：超几何分解(hypergeometic decomposition),用来解决在更复杂情况下期望与方差在随机运算系统中的传播规律。基于超几何分解,提出4组更加精确的期望及方差传递方程,在数学上证明了随机运算体系更加广泛的适用性,并且通过随机运算系统在图像处理中的应用,提出了基于方差的系统评价方法,相比于传统按位仿真方法,基于方差的系统分析方法具有耗时短、准确和全面的优点。新的方差传递方程首次将随机信号源的类型引入性能分析,证明了具有特定码流长度的随机序列可以使系统性能达到最优。     

一种LDPC系统中的似然值计算方法

在通信系统中采用低密度奇偶校验码（LDPC）与扰码,一方面能够使得信息随机化,同时也能得到较高的编码增益,加扰可以在 LDPC 编码前进行,也可以在编码后进行。针对 LDPC 编码后进行加扰的通信系统,提出了一种通过软解调与软解扰进行LDPC译码所需的似然值的计算方法。首先对这种级联系统的结果进行描述,其次对似然值的计算进行了理论推导,最后构建仿真系统,与 LDPC 结合进行仿真验证。     

计算无圈有向网络ST可靠性的一个新方法

本文考虑计算无圈有向网络的ＳＴ可靠性问题（至少存在一条从源点ｓ到汇点ｔ的正常运行道路的概率）。文章引进了深度优先搜索（Ｄｅｐｔｈ－ＦｉｒｓｔＳｅａｒｃｈ）有序根树的概念并提出一个新的计算无圈有向网络ＳＴ可靠性的拓扑公式。以该公式为基础,我们利用ＤＦＳ方法提出一个新的计算无圈有向网络ＳＴ可靠性算法,它能生成简洁的可靠性表达式,进而有效地计算无圈有向网络的ＳＴ可靠性。两个例子例证了我们的结论     

基于非负约束矩阵分解的语音增强算法研究

从噪声背景中提取尽可能纯净的语音信号，增强有用信号，抑制、降低噪声干扰的技术称为语音增强技术。语音增强有着广泛的应用，因此寻求一种有效的算法对带噪语音信号进行处理得到较纯净的原始语音信号的研究有着很大的意义。多年来很多经典的语音增强算法被提出，如谱减算法，子空间算法等。文章提出了一种新颖的语音增强方法，即基于非负低秩稀疏分解的原理在强噪声环境下实现语音增强。把语音信号和噪声信号看做是一个非负低秩稀疏分解问题并且不断的优化算法分离出语音信号和噪声信号的幅度谱。实验结果表明在强噪声环境下这种方法对比一些传统的语音增强方法效果更好，具有更少的噪声残余与较低的语音失真等优点     

A Simple Method for Reliability Evaluation of a Communication System

Very few techniques exist for reliability evaluation of communication systems where links as well as nodes have certain probability of failure. This correspondence describes a technique by which the reliability expression for such a system can be conveniently derived. It is also shown that using the concept of this correspondence, it is possible to extend all the existing reliability-evaluation algorithms to communication systems with little effort.     

某型光电探测系统可靠性增长评估

光电探测系统研制阶段的试验数据具有小样本特征,针对传统的可靠性评估结果偏保守的问题,基于单调约束模型,通过综合利用光电探测系统多阶段试验数据进行可靠性评估,以达到精确评估的目的。考虑将研制过程中不同试验阶段数据中包含的可靠性增长信息作为约束条件,推导出可靠度分布函数表达式,并给出一种等效的统计抽样计算方法——Monte Carlo模拟算法,使计算过程更加简便,便于工程应用。最后以某型光电探测系统为例,表明利用可靠性增长信息进行可靠性评估,可有效提高评估的精度。     

A Recursive Method Based on Case Analysis for Computing Network Terminal Reliability

In this paper a unified treatment is provided of the methods for computing terminal reliability based on recursive case analysis. The possible choices in case enumeration are discussed, and a rationale is given to support a particular policy. Simplification and decomposition techniques are also examined, and some experimental results are described, obtained with a computer program, which is a good compromise between efficiency and simplicity.     

A Simple Technique for Computing Network Reliability

A tree construction technique to compute a reliability expression of a network is derived. The technique is straight forward and good for both directed and undirected graphs. It gives mutually disjoint success branches. The reliability expression of each branch can be directly written by a set of rules. The reliability of the network can then be obtained by taking the direct sum of the reliabilities of the branches. It involves fewer multiplications than other known techniques. For a moderately complex network it is very easy to use this technique for evaluating reliability.     

A Modified Technique for Computing Network Reliability

Ahmad (1982) has published a technique to compute the reliability of a network without resorting to paths or cutsets. However, the technique uses a random choice of next node connected to the previous node in the construction of a tree. This approach can lead to a large number of terms in the reliability expression. Our modified version of the Ahmad technique always produces a reliability expression with the same or fewer terms as the original technique.     

Recursive Technique For Computing System Reliability

This paper presents a simple recursive formula for calculating source-to-sink congestion, and hence reliability, in a network. This congestion is derived from individual blocking probabilities of each link. The method has an advantage of not requiring cut-sets. Such a knowledge is a prerequisite in most other methods of reliability analysis. We have programmed the algorithm using Pascal as it allows recursive procedure calls. An example illustrates the method.     

A Direct Method for Maximizing the System Reliability

A simple computational procedure has been developed for allocating redundancy among subsystems so as to achieve maximum reliability of a multistage system subject to multiple constraints which need not be linear. The computational time is quite short. Two examples are shown.     

一种基于特征值分解的测量矩阵优化方法

测量矩阵是压缩感知中一个很重要的部分,为了减小测量矩阵与稀疏变换矩阵的互相干性,从而改善重建质量,本文首先通过测量矩阵和稀疏变换矩阵的乘积构造得到一个Gram矩阵,然后定义了一种基于Gram矩阵非对角线元素的整体互相干系数,推导出整体互相干系数与Gram矩阵特征值之间的关系。在此基础上,我们提出了一个最优化模型,在不改变Gram矩阵特征值和的前提下,让每个大于零的特征值的大小都为它们和的平均值,使得测量矩阵和稀疏变换矩阵的整体互相干系数达到最小,从而优化了测量矩阵的性能。将该方法用在一些已知的测量矩阵上,实验结果中矩阵的优化速度快,并且用优化矩阵所得的图像的PSNR有所提高,表明本文优化测量矩阵的方法在重建效果和优化速度方面都有一定的优势。      

Reliability Evaluation by Network Decomposition

The method evaluates the reliability of large computer communication systems by systematic decomposition of the probabilistic graph of the system into two parts using an appropriate cutset. A technique is evolved for determining the conditional success events using both the node removal and connection multiplication methods for path enumeration. An example is solved to show the versatility of the method. The results of the example are verified by using an existing algorithm. The suggested method is general and computationally economical.     

A Recursive Algorithm for Computing Exact Reliability Measures

An algorithm is presented to find source-to-K-terminal reliability in a directed graph with independent arc failures. The algorithm is based on a discrete-time Markov chain with two absorbing states. The Markov chain has an upper triangular transition probability matrix, thus the probability of absorption in a state can be found by back-substitution. We show: 1) The source-to-K-terminal reliability is the probability of absorption in a particular absorbing state; 2) The time until absorption can be used as an alternative reliability measure; and 3) The algorithm can be used to find a third reliability measure called the degree of connectedness.     

A Practical Algorithm for Computing Multi-State Two-Terminal Reliability

A practical, important system performance index for analyzing real world systems is NP-hard multi-state two-terminal reliability. Contributions of this paper are 1) it presents a direct, correct decomposition method for solving NP-hard multi-state two-terminal reliability, and 2) it does not require a priori the multi-state minimal paths/cuts of the system. Because all the exact methods solve the multi-state two-terminal reliability problem in terms of two/three NP-hard problems, excluding the impractical complete enumeration method, and Doulliez & Jamoulle's popular but incorrect decomposition method, development of such an exact, direct, and practical algorithm is thus worthwhile. Computational experiments verify that the proposed method is practical, fast, and efficient in comparison with the complete enumeration method.