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1.
Concept lattice is an efficient formal tool for data analysis and knowledge extraction. However, the present research presumes that all the intensions of concept lattice are equally important. In order to make the best use of concept lattice for analyzing data, extracting knowledge and effectively guiding the decision-making management, the weight value is introduced into the intension of the concept lattice and a new concept lattice, a weighted concept lattice (WCL) is presented, which develops the concept lattice structure. Then one FWCL (Frequent Weighted Concept Lattice) incremental construction method is offered and relative analysis together with an example is presented to illustrate its efficiency and feasibility.  相似文献   

2.
Web hyperlink structure analysis algorithm plays a significant role in improving the precision of Web information retrieval. Current link algorithms employ iteration function to compute the Web resource weight. The major drawback of this approach is that every Web document has a fixed rank which is independent of Web queries. This paper proposes an improved algorithm that ranks the quality and the relevance of a page according to users' query dynamically. The experiments show that the current link analysis algorithm is improved.  相似文献   

3.
This paper discusses an iconmap-based visualization technique that enables multiple geospatial variables to be illustrated in a single GIS raster layer.This is achieved by extending the conventional pixelbased data structure to an iconic design.In this way,spatial patterns generated by the interaction of geographic variables can be disclosed,and geospatial information mining can be readily achieved.As a case study,a visual analysis of soil organic matter and soil nutrients for Shuangliu County in the city of Chengdu,China,was undertaken using the prototype IconMapper software,developed by the authors.The results show that the static IconMap can accurately exhibit trends in the distribution of organic matter and nutrients in soil.The dynamic iconmap can both reflect interaction patterns between organic matter and the nutrient variables,and display soil fertility levels in a comprehensive way.Thus,the iconmap-based visualization approach is shown to be a non-fused,exploratory analytical approach for multivariate data analysis and as a result is a valuable method for visually analyzing soil fertility conditions.  相似文献   

4.
The intersection of N halfplanes is a basic problem in computational geometry and computer graphics,The optimal offline algorithm for this problem runs in time O(N log N).In this paper,an optimal online algorithm which runs also in time O(N log N) for this problem is presented.The main idea of the algorithm is to give a new definition for the left side of a given line,to assign the order for the opoints of a convex polygon.and then to use binary search method in an ordered vertex set.The data structure used in the algorithm is no more complex than array.  相似文献   

5.
Web hyperlink structure analysis algorithm plays a significant role in improving the precision of Web information retrieval.Current link algorithms employ iteration function to compute the Web resource weight.The major drawback of this approach is that every Web document has a fixed rank which is independent of Web queries.This paper proposes an improved algorithm that ranks the quality and the relevance of a page according to users‘ query dynamically.The experiments show that the current link analysis algorithm is improved.  相似文献   

6.
Designing a fuzzy inference system (FIS) from data can be divided into two main phases: structure identification and parameter optimization. First, starting from a simple initial topology, the membership functions and system rules are defined as specific structures. Second, to speed up the convergence of the learning algorithm and lighten the oscillation, an improved descent method for FIS generation is developed. Furthermore, the convergence and the oscillation of the algorithm are systematically analyzed. Third, using the information obtained from the previous phase, it can be decided in which region of the input space the density of fuzzy rules should be enhanced and for which variable the number of fuzzy sets that used to partition the domain must be increased. Consequently, this produces a new and more appropriate structure. Finally, the proposed method is applied to the problem of nonlinear function approximation.  相似文献   

7.
Object-oriented modeling with declarative equation based languages often unconsciously leads to structural inconsistencies. Component-based debugging is a new structural analysis approach that addresses this problem by analyzing the structure of each component in a model to separately locate faulty components. The analysis procedure is performed recursively based on the depth-first rule. It first generates fictitious equations for a component to establish a debugging environment, and then detects structural defects by using graph theoretical approaches to analyzing the structure of the system of equations resulting from the component. The proposed method can automatically locate components that cause the structural inconsistencies, and show the user detailed error messages. This information can be a great help in finding and localizing structural inconsistencies, and in some cases pinpoints them immediately.  相似文献   

8.
An Attack-Finding Algorithm for Security Protocols   总被引:5,自引:1,他引:5       下载免费PDF全文
This paper proposes an automatic attack construction algorithm in order to find potential attacks on ecurity protocols.It is based on a dynamic strand space model,which enhances the original strand space model by introducing active nodes on strands so as to characterize the dynamic procedure of protocol execution.With exact causal dependency relations between messages considered in the model,this algorithm can avoid state space explo-sion caused by asynchronous composition.In order to get a finite state space,a new method called strand-added on demand is exploited,which extends a bundle in an incremental manner without requiring explicit configuration of protocol execution parameters.A finer granularity model of term structure is also introduced, in which subterms are divided into check subterms and data subterms .Moreover,data subterms can be further classified based on the compatible data subterm relation to obtain automatically the finite set of valid acceptable terms for an honest principal.In this algorithm,terms core is designed to represent the intruder‘s knowledge compactly,and forward search technology is used to simulate attack patterns easily.Using this algorithm,a new attack on the Dolve-Yao protocol can be found,which is even more harmful beeause the secret is revealed before the session terminates.  相似文献   

9.
陈余庆  庄严  王伟 《自动化学报》2007,33(6):628-634
This article is concerned with cooperative control problems in formation of mobile robots under the nonholonomic constraints that certain geometrical constraints are imposed on multiple mobile robots throughout their travel. For this purpose, a new method of motion control for formation is presented, which is based on the dynamic regulation and scheduling scheme. It is attractive for its adaptability to the formation structure and desired trajectory. The quality of formation keeping can be evaluated by the instantaneous errors of formation offset and spacing distance. Some kinematics laws are developed to regulate and maintain the formation shape. Simulation results and data analysis show the validity of the proposed approach for a group of robots.  相似文献   

10.
A new signal processing method using a single vector hydrophone is proposed for solving the problem of azimuth angle estimation for multiple targets based on a small aperture underwater platform.The method extends the aperture from a single vector hydrophone into a half wavelength distance uniform linear array by decomposing the time-domain sample data from different channels of the hydrophone.The extended array has a narrower space beam pattern than a single vector hydrophone.The azimuths of spatial multiple targets are estimated by using the appended array snapshots under the condition of broadband or narrow band signals.The new method is robust because there is no need to correct the array manifold.Theoretical analysis and computer simulations show that,the new algorithm has the ability to distinguish two incoherent targets with either narrow band or broadband signals in an isotropic noise field.The algorithm provides a non-biased estimate with a high signal-to-noise ratio.  相似文献   

11.
指针数组的过程内别名分析   总被引:1,自引:1,他引:0  
指针别名分析在C语言的并行优化中占有重要的地位,但已有的指针别名分析只能处理指针标量的情况.文章在介绍已有指针别名信息表示法的不足的基础上,提出了一种能够表示指针数组别名信息的表示方法,它可以更加准确地表示指针别名信息.在此表示法的基础上,提出了指针数组的过程内别名分析算法.此算法完全包含了指针标量的别名分析,对现有的指针别名分析算法所不能解决的一些问题能进行有效地处理.  相似文献   

12.
刘鹏  赵荣彩  庞建民  姚远 《软件学报》2014,25(11):2486-2498
指针分析是数据流分析中的关键性技术,其分析结果是编译优化和程序变换的基础。在基于包含的指针分析算法研究的基础上,对 Narse 优先权约束评估算法中存在的冗余约束评估和优先权评估模型计算开销较大的问题进行分析,以指针的指向集更新信息确定约束评估的候选集,提出了基于指向更新的约束评估算法。采用约束语句间的解,引用依赖和标量依赖构建约束依赖图,通过依赖关系确定约束评估的优先权,提出了基于约束依赖图的优先权算法,简化了既有算法中复杂的优先权评估模型,进一步给出了优化后算法的整体框架。在基准测试集 SPEC 2000/SPEC 2006上进行实验,其结果表明,该算法与Narse优先权算法相比,在时间开销和存储开销上都有明显的性能提升。  相似文献   

13.
Reasoning about pointer programs is difficult and challenging, while their safety is critical in software engineering. Storeless semantics pioneered by Jonkers provides a method to reason about pointer programs. However, the representation of memory states in Jonkers’ model is costly and redundant. This paper presents a new framework under a more efficient storeless model for automatically verifying properties of pointer programs related to the correct use of dynamically allocated memory such as absence of null dereferences, absence of dangling dereferences, absence of memory leaks, and preservation of structural invariants. The introduced logic-Pointer Logic, is developed to achieve such goals. To demonstrate that Pointer Logic is a useful storeless approach to verification, the Schorr-Waite tree-traversal algorithm which is always considered as a key test for pointer formalizations was verified via our analysis. Moreover, an experimental tool-plcc was implemented to automatically verify a number of non-trivial pointer programs.  相似文献   

14.
指针是C语言的核心。利用它可以表示多种数据结构,把指针与普通变量、数组、函数结合可以设计出灵活高效的程序。本文针对指针的这些常见用法进行了具体的分析。  相似文献   

15.
针对遗传算法在求解旅行商问题时,受限于初始种群质量而存在收敛速度慢、易陷入局部最优等问题,提出一种基于指针网络改进遗传算法种群模型。通过经改进指针网络生成初始种群取代原种群,并结合基于汉明距离轮盘赌策略对种群个体进行择优,形成个体质量和种群多样性高的新种群。实验在TSPLIB标准库上多组实例进行测试,并和研究进展种群改进算法和多种主流启发式算法进行多项系数对比。结果表明,经过优化后算法的收敛速度和寻优能力有显著提高,能够有效用于改善遗传算法在旅行商问题上的应用。  相似文献   

16.
指针是C语言的核心。利用它可以表示多种数据结构,把指针与普通变量、数组、函数结合可以设计出灵活高效的程序。本文针对指针的这些常见用法进行了具体的分析。  相似文献   

17.
上下文敏感的过程间指针分析   总被引:4,自引:0,他引:4  
提出了一种新的指针指向信息的过程间传播方法 ,对过程间指针分析所必须解决的若干重要问题给出了详尽的算法 ,从而形成了一种实用的上下文敏感的过程间指针分析框架 .该方法已在 C程序分析工具 Agassiz系统中实现 ,实验数据说明这些方法是行之有效的 .  相似文献   

18.
流敏感的跨过程指针别名分析   总被引:3,自引:0,他引:3  
李健  刘坚 《计算机应用》2004,24(3):112-114
对指针别名及其表示方式进行了阐述。描述了跨过程指针别名分析的框架,通过在分析时创建PCG(程序调用图)来处理函数指针。研究了基于此框架的一个流敏感的跨过程指针别名分析算法,算法是跨过程阶段和过程内阶段交叉进行的。最后对算法进行了实例分析和验证。  相似文献   

19.
指针分析是编译优化、程序静态分析中的基础,很多应用都需要基于指针分析,低精度的指针分析会给这些应用带来高误报率和漏报率,通过添加上下文敏感信息是提高指针分析的精度的一个重要手段.自从面向对象的概念被提出来之后,该概念得到了广泛的应用, Java、C++、.NET、C#等主流语言都支持面向对象的特性,面向对象程序的指针分析越来越受关注.做了一个系统文献综述(SLR),通过对索引到的相关文献进行分析和归类,总结了面向对象程序的上下文敏感指针分析研究的5个主要问题,并对这5个问题中用到的方法进行了分析讨论.  相似文献   

20.
过程间指针分析算法的改进   总被引:1,自引:0,他引:1       下载免费PDF全文
指针分析对于使用C语言编制程序的数据流分析有着重要的意义。该文介绍指针问题的复杂度、指针分析算法的分类以及指针分析算法的现状,并采用Atkinson提出的基于函数类型过滤得到较为精确的函数调用图的思想,改进刘强提出的上下文敏感的过程间指针分析算法,在对使用函数指针进行函数调用时,使用函数原型过滤限制在函数调用处的函数指针的指向集,提高指针分析的精确度。  相似文献   

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