A modified creep index and its application to viscoplastic modelling of soft clays

Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae.     

聚氨酯泡沫塑料应力-应变关系的试验与参数识别

介绍了获得聚氨酯泡沫塑料压缩状态下应力-应变关系的恒速加、卸载试验与参数识别的基本方法与过程.针对2种不同密度的聚氮酯泡沫塑料,以不同的速率做了恒速加、卸载试验,以遗传积分模型为例介绍了利用恒速加、卸载试验识别模型参数的方法,提出了进行试验数据预处理的线性插值法.     

热力参数软仪表在电厂中的应用

为了解决电厂中热力参数失效和优化运行的问题,提出了一种基于稀疏高斯过程的软测量建模方法,它基于Bayes在线学习算法,通过构造序列的相关子样本来给出高斯过程的预测输出.通过利用参数化和再生核Hilbert空间范数的投影技巧,得到优化后的参数和后验过程的稀疏高斯逼近.高斯过程的稀疏表达使得基于高斯过程的软仪表能够满足大规模数据集的实时应用需要,所提出的热力参数软仪表对于电厂经济运行有着重要的意义.     

An efficient algorithm for mining closed itemsets

This paper presents a new efficient algorithm for mining frequent closed itemsets. It enumerates the closed set of frequent itemsets by using a novel compound frequent itemset tree that facilitates fast growth and efficient pruning of search space. It also employs a hybrid approach that adapts search strategies, representations of projected transaction subsets, and projecting methods to the characteristics of the dataset. Efficient local pruning, global subsumption checking, and fast hashing methods are detailed in this paper. The principle that balances the overheads of search space growth and pruning is also discussed. Extensive experimental evaluations on real world and artificial datasets showed that our algorithm outperforms CHARM by a factor of five and is one to three orders of magnitude more efficient than CLOSET and MAFIA.     

An efficient algorithm for mining closed itemsets

INTRODUCTIONMiningfrequentitemsetsisafundamentalandessentialprobleminmanydataminingapplica tionsincludingthediscoveryofassociationrules,strongrules,correlations,sequentialrules,epi sodes,multi dimensionalpatterns,andmanyoth erimportantdiscoverytasks (AgarwalandSri kant,1994;Wangetal.,2 0 0 2 ) .Mostalgo rithmsproposedsofarworkwellondatasetswherethesizesofitemsetsarerelativelysmall.Howev er,theyusuallycrashwithdensedatasetswheretheitemsetsizesarelarge.Suchdatasetsincludethosecomposedofque…     

基于改进同伦算法的材料特性参数识别

随着仿真过程中对材料参数精度的要求不断提高,通过计算反求技术获取材料特性参数成为实现精细化建模的重要方法。如何能准确、高效地获取材料特性参数成为研究的热点。提出1种基于改进同伦算法的材料特性参数反求方法。首先,以准静态拉伸实验获取的力-位移曲线作为测量响应,并在敏感性分析基础上建立材料特性参数反求的目标函数。其次,对同伦算法进行改进,采用曲线预估代替传统的欧拉预估作为反求工具。最后,基于改进同伦算法给出某金属材料硬化系数和硬化指数的反求结果及收敛曲线,并与传统方法进行对比验证。结果表明,改进后的同伦算法能在不影响精度的情况下大大提高计算效率。     

多约束非线性背包问题的一种有效算法

1IntroductionWe consider the following multi-di mensional nonlin-ear knapsack problem(MNKP)maxf(x)=∑nj=1fj(xj)s.t.gi(x)=∑nj=1gij(xj)≤bi,i=1,…,m,x∈X={x|lj≤xj≤uj,xjinteger,j=1,…,n},where allfjand allgijare nondecreasing functions ofxjon[lj,uj]forj=1,…,n,i=1,…,m,andljandujare integer lower and upper bounds forxj,re-spectively,j=1,…,n.It has been proved that0-1linear knapsack problemis NP-hard[1].Nonlinear knapsack problems have numerous appli-cations in various fields,for example,ca…     

An efficient method for parallel CRC automatic generation

INTRODUCTIONCRC (CyclicRedundancyChecking)codesarewidelyusedintelecommunication ,especiallyintheinternallayersofprotocolssuchasEther net,X2 5,FDDIandATM (AAL5) .Thecom monhardwaresolutionforCRCcalculationisthelinearfeedbackshiftregister (LFSR) ,charac ter…     

An efficient method for tracing planar implicit curves

INTRODUCTION Tracing a planar implicit curve f(x, y)=0 on a rectangular region [xl, xr]×[yb, yt] is of great interest in Computer-Aided Design and Computer Graphics. While parametric curves are easy to plot, plotting implicit curves is a challenging problem. Planar im- plicit curve plotting method can be classified into two categories (Shou et al., 2005; Martin et al., 2002; Lopes et al., 2002). In the first category are subdivi- sion methods (Shou et al., 2005; Martin et al., 2002) …     

An efficient method for parallel CRC automatic generation

The State Transition Equation (STE) based method to automatically generate the parallel CRC circuits for any generator polynomial or required amount of parallelism is presented. The parallel CRC circuit so generated is partially optimized before being fed to synthesis tools and works properly in our LAN transceiver. Compared with the cascading method, the proposed method gives better timing results and significantly reduces the synthesis time, in particular. Project (No. 60271010) supported by the National Natural Science Foundation of China     

An Efficient Compression Coding System for Motion Images

lintroductionIndigitalimagecommunication,theaimofsourcecodingistoreducethedataratetofit'theavailabletransmissionchannelWhile1llaintaininggoodimagefidelity.ThisisachievedbyutilizingthestatisticalPropel-tiesoftheimagesandthevisualcharacteristicsofllulllaney…     

An adaptive finite element procedure for crack propagation analysis

INTRODUCTION The finite element method (FEM) has proved to be very well suited for the study of fracture mechanics. Nevertheless, modelling the propagation of a crack through a finite element mesh turns out to be difficult because of the modification of the mesh topology. Use of crack propagation laws based on stress inten-sity factor range is the most successful engineering application of fracture mechanics. The stress intensity factors are a very important parameter in fracture analys…     

An efficient numerical shape analysis for light weight membrane structures

The determination of initial equilibrium shapes is a common problem in research work and engineering applications related to membrane structures. Using a general structural analysis framework of the finite particle method （FPM）, this paper presents the first application of the FPM and a recently-developed membrane model to the shape analysis of light weight mem- branes. The FPM is rooted in vector mechanics and physical viewpoints. It discretizes the analyzed domain into a group of parti- cles linked by elements, and the motion of the free particles is directly described by Newton＇s second law while the constrained ones follow the prescribed paths. An efficient physical modeling procedure of handling geometric nonlinearity has been developed to evaluate the particle interaction forces. To achieve the equilibrium shape as fast as possible, an integral-form, explicit time integration scheme has been proposed for solving the equation of motion. The equilibrium shape can be obtained naturally without nonlinear iterative correction and global stiffness matrix integration. Two classical curved surfaces of tension membranes pro- duced under the uniform-stress condition are presented to verify the accuracy and efficiency of the proposed method.     

大规模ad hoc网络下的高效的主动RSA方案

A previous proactive RSA scheme for large-scale ad hoc network has been shown to be faulty. In this paper, we present a new proactive RSA scheme for ad hoc networks, which includes four protocols： the initial key distribution protocol, the share refreshing protocol, the share distribution protocol, and the signature generation protocol. This scheme has two advantages： the building blocks are secure, and the system is efficient.     

An efficient enhanced k-means clustering algorithm

INTRODUCTION The huge amount of data collected and stored in databases increases the need for effective analysis methods to use the information contained implicitly there. One of the primary data analysis tasks is cluster analysis, intended to help a user understand the natural grouping or structure in a dataset. Therefore, the development of improved clustering algorithms has received much attention. The goal of a clustering algorithm is to group the objects of a database into a set of m…     

一般Gauss-Markov模型中参数岭估计的可容许性的一个证明

讨论一般Gauss-Markov模型中参数岭估计的有关问题，并在均方误差矩阵意义下，证明了一般岭估计在线性估计类中是否容许估计。     

An efficient parallel algorithm for shortest paths in planar layered digraphs

This paper presents an efficient parallel algorithm for the shortest path problem in planar layered digraphs that runs in O(log3n) time with n processors. The algorithms uses a divide and conquer approach and is based on the novel idea of a one-way separator, which has the property that any directed path can be crossed only once.     

An empirical study of formal procedure specification

Programming a computer is a problem-solving activity which can be categorized as formal procedure specification.It is a useful vehicle for the study of this aspect of problem-solving because the procedures can be automatically tested for correctness.The reported study focuses on the incidence and severity of errors committed during program development by novice programmers.The observations are summarized in tabular form, to permit insights into the sorts of errors virtually untrained students make when specifying procedures, and the problems they have eliminating them.     

程序法初论

程序法是与实体法完全对应的具有独立系统性的法学研究领域.现有的法学理论并没有解决程序法的许多基本问题.程序法是一种通过立法预置的法律操作系统,具有整体性和不可分性.     

An efficient parallel algorithm for shortest paths in planar layered digraphs

INTRODUCTION Computing shortest paths in directed graphs isa fundamental optimization problem with applica-tions to many areas of computer sciences and op-eration research (Bellman, 1958; Coremen, 1990;Cohen, 1993). Given a digraph G with non-negativeweights on its edges and two vertices s and t of G,the single-pair shortest path problem consists ofdetermining a directed path from s to t with mini-mum total weight. Among the well-known sequential algorithmsfor this problem is the classic…