开放式环境中的高可用性系统

高可靠性正在为高档次的开放系统环境中不可缺少的特性。     

A finite element formulation for multilayered and thick plates

A bilinear isoparametric finite element concept is used for the numerical analysis of multilayered plates. The underlying theory used allows for transverse shear and normal strains in each layer, thus extending the analysis to very thick plates and laminates. To illustrate the versatility of the multilayered element, three examples are presented and the results are compared with available exact solutions.     

Decomposition abstraction in parallel rule languages

Decomposition abstraction is the process of organizing and specifying decomposition strategies for the exploitation of parallelism available in an application. In this paper we develop and evaluate declarative primitives for rule-based programs that expand opportunities for parallel execution. These primitives make explicit, implicit relations among the data and similarly among the rules. The semantics of the primitives are presented in a general object-based framework such that they may be applied to most rule-based programming languages. We show how the additional information provided by the decomposition primitives can be incorporated into a semantic-based dependency analysis technique. The resulting analysis reveals parallelism at compile time that is very difficult, if not impossible, to discover by traditional syntactic analysis techniques. Simulation results demonstrate scalable and broadly available parallelism     

Design, engineering, and experimental analysis of a simulated annealing approach to the post-enrolment course timetabling problem

The post-enrolment course timetabling (PE-CTT) is one of the most studied timetabling problems, for which many instances and results are available. In this work we design a metaheuristic approach based on simulated annealing to solve the PE-CTT. We consider all the different variants of the problem that have been proposed in the literature and we perform a comprehensive experimental analysis on all the available public instances. The outcome is that our solver, properly engineered and tuned, performs very well on all cases, providing the new best known results on many instances and state-of-the-art values for the others.     

一种测量任意链路可用带宽的方法

可用带宽测量对于网络行为分析、网络服务质量(quality of service,简称QoS)的验证等有很重要的作用.现有可用带宽测量工作主要集中在端到端路径可用带宽测量,仅提供路径上承压链路(tight link)的信息,而不能提供其他关键链路的信息.为此,提出一种新颖的链路可用带宽测量算法LinkPPQ(trains of pairs of packet-quartets used to measure available bandwidth of arbitrary links),它采用由四探测分组结构对构成的探测序列,能够测量网络中任意链路的可用带宽,并跟踪该链路上背景流的变化.在仿真环境和实际网络环境下研究了LinkPPQ 的性能.仿真结果表明,在几种不同背景流场景下,对于具有单狭窄链路的路径和具有多狭窄链路的路径,LinkPPQ 都能够对各个链路的可用带宽进行有效的测量.绝大多数情况下测量误差小于30%,且具有较好的测量平稳性.实验网的实验结果也表明,LinkPPQ 可以准确测量以下几种情况下的链路的可用带宽:a) 从容量为10Mbps 的链路准确地测量一条100Mbps 链路的可用带宽;b) 准确测量容量10 倍于紧邻其后狭窄链路的容量的链路的可用带宽;c) 准确测量具有多狭窄链路的路径上各狭窄链路的可用带宽.     

光纤近红外漫反射光谱技术在前胡族植物分类中的应用探讨

探讨了近红外光谱技术在前胡族植物分类中的可能性。用系统聚类分析获得的分类结果与传统的植物学分类比较一致,谱明本方法应用于前胡植物中三亚族的分类是基本可行的。     

Error analysis of the ultraspherical spectral-collocation method for high-index IAEs

The subject of integral-algebraic equations (IAEs) with index?>?2 is new in the literature and there are a few available results which investigate these systems. We will deal here with a particular class of IAEs of index-3 and analyse ultraspherical polynomials collocation method as well as convergence analysis for the numerical solution of these systems. Our error analysis of collocation method is based on polynomial approximation theory and results related to the interpolation error in Sobolev space. Numerical examples illustrate the theoretical results.     

On the state-space analysis of linear R-L-C networks with source derivatives†

The state-space representation for a linear R-L-C network with the independent sources of the network as exclusive components of the input vector does not always exist. When the state variables are chosen as capacitor voltage and inductor currents, the state-space characterization of linear R-L-C networks involves derivatives of sources. In network analysis the available literature uses the state-apace representation exclusive of the source derivatives. Therefore, an extension of the results and expressions, available for the state-space characterization without source derivatives, is performed in this paper for the case when source derivatives are also involved in the state-space representation.     

Comparison of pair potential and thermochemical models of the heat of formation of BCC and FCC alloys

Data bases covering the thermochemical properties of solid solution phases are being assembled for a wide variety of applications. Such activities are often hampered by limitations on available experimental data and fundamental methods for estimating missing information. To bridge this gap the pair potential model has been developed and refined and is compared here with results drawn from thermochemical and phase diagram analysis of the heat of formation of bcc and fcc alloys. A computer program is presented providing a means for calculating the heat of formation for binary systems composed of twenty-seven elements. The results are compared with thermochemical values for sixty-six binary systems composed of all combinations of aluminum, cobalt, chromium, copper, iron, manganese, molybdenum, niobium, nickel, silicon, titanium and tungsten. The level of agreement provides a good measure of confidence in the usefulness of this pair potential model to obtain estimates for data which is otherwise available.     

光纤近红外漫反射光谱技术在前胡族植物分类中的应用探讨

探讨了近红外光谱技术在前胡族植物分类中的可能性。用系统聚类分析获得的分类结果与传统的植物学分类比较一致 ,说明本方法应用于前胡族植物中三亚族的分类是基本可行的。     

Reduced‐order impulsive control for a class of nonlinear systems

Impulsive control of nonlinear systems is an attractive topic and a number of interesting results have been obtained in the recent years. However, most of the available results need to employ full information of the system states to achieve the desired objectives. In this paper, a reduced‐order impulsive control strategy that needs only part of state components is studied for a general class of nonlinear system, which is feasible for the case when some of the system states are not available or controllable. Typical chaotic systems, such as Lorenz system, Chua's oscillator, and Chen's system, are taken as examples. A systematic design scheme is proposed to select the impulsive intervals. After some theoretical analysis, simulation results illustrate the effectiveness of the proposed control scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

高可用CORBA

CORBA是OMG组织提出的一个基于OMA体系结构的分布式系统,是当前面向对象分布式系统中的典型代表。基于CORBA规范的分布式系统如IONA的Orbix、Inprise的Visibroker的产品等已经不断推向市场,CORBA在分布式环境中为解决异质环境的应用提供了良好的基础平台,用户在开发过程中不用考虑低层复杂的分布式环境,而把主要的精力放在高层。随着对CORBA的研究与开发,人们对其可靠性提出了更高的要求,于是如何建立基于CORBA环境     

B小波和阶跃谱分析在缺损频谱成像中的应用

提出一种用于频域的快速B小波变换方法和阶跃谱分析理论,并把它们用于磁共振缺损频谱数据中提取高频频谱、恢复完整频谱,重建图像.在此方法中,首先用快速B小波变换方法,从低频磁共振数据中提取、恢复缺少的高频分量的特征信息;然后用阶跃谱分析理论,由这些特征信息构成高频磁共振频谱、恢复完整频谱数据;最后用FFT(fast Fourier transform)重建磁共振图像.实验和模拟结果都表明,重建图像质量优于现有方法.     

Numerical investigating the effect of machining parameters on residual stresses in orthogonal cutting

The aim of the present study is to develop a finite element analysis based on the nonlinear finite element code MSC.Superform for investigating the effect of cutting speed and feed rate on surface and subsurface residual stresses induced after orthogonal cutting. Basically, the present analysis is a coupled thermo-mechanical dynamic-transient problem. The results from the model are compared to experimental measurements available in the literature, concerning orthogonal cutting of steel AISI 1045 and are in good agreement with experimental data.     

Finite element analysis of 3-D beam-columns on a nonlinear foundation

A numerically integrated finite element for the analysis of three-dimensional, nonlinear Winkler foundations is developed. Together with a linear beam-column element they are used to solve problems of beams, columns and beam-columns on linear and nonlinear foundations in two and three dimensions. The Newton-Raphson method is used in the solution. Excellent results are illustrated by comparisons with available solutions.     

Bending of anisotropic plates by charge simulation method

A boundary element method, called the charge simulation method, is presented for analysis of anisotropic thin-plate bending problems. In this method the singular integrals involved in the other boundary element methods are eliminated and there is no numerical integration involved. Further, the domain integral is replaced by a polynomial particular integral; hence the domain discretization is avoided. This method is conceptually very simple. The results obtained by this method are compared with the available analytical solutions for various anisotropic and symmetric laminates and the results are in good agreement.     

Passivity analysis for uncertain discrete-time stochastic BAM neural networks with time-varying delays

This paper is concerned with the passivity analysis problem for a class of discrete-time stochastic bidirectional associative memory neural networks with time-varying delays. Furthermore, the results are extended to the robust passivity analysis with mixed time delays that consist of both the discrete and distributed time delays, and the uncertainties are assumed to be time-varying norm bounded parameter uncertainties. By constructing a new Lyapunov–Krasovskii functional and introducing some appropriate free-weighting matrices, a delay-dependent passivity criterion is derived in terms of LMIs whose feasibility can be easily checked by some available software packages. Finally, two numerical examples with simulation results are given to demonstrate the effectiveness and usefulness of the proposed results.     

Research and Development of SAR Satellite Remote Sensing System of Ocean Oil Spills

SAR satellite remote sensing system of ocean oil spills has been developed for the operational surveillance in the offshore oil exploration areas of National Offshore Oil Corporation in China.The system is capable of SAR images processing,oil spill automatic detection using the algorithm of agglomeration hierarchy cluster and oil features extraction.The comprehensive analysis of oil detection results is also available including confidence analysis,multi-source and multi-phase data analysis as well as backtracking of oil spill sources.Oil thematic maps are output utilizing oil detection and comprehensive analysis results,which can be overlaid with electronic charts.The system can provide the technical backup and decision support for oil spill early warning and emergent measures implement.     

Evidence measures based on fuzzy information

An organized body of results pertaining to the analysis of evidence, when the available knowledge is pervaded with imprecision, is provided. The evidence theory of Dempster and Shafer is extended to the case of fuzzy observations and fuzzy events. Upper and lower possibilities of such events are derived by iterating the generation process of upper and lower probabilities, as done by Dempster. Both probabilistic and “possibilistic” models are developed in parallel. These evidence measures are used for decision evaluation when the available knowledge is poor. The classical model of decision-making under uncertainty is thus extended to the case when the consequences of a decision are only roughly described and their probabilities of occurrence modeled by intervals or fuzzy numbers.