共查询到20条相似文献,搜索用时 133 毫秒
1.
KDD方法在金融欺诈检测中的应用研究 总被引:3,自引:0,他引:3
摘 要:在分析了金融事务中进行金融欺诈的现象后,对传统的金融欺诈检测方法进行了分析,并在此基础上,提出了一种利用数据挖掘方法进行金融欺诈检测的模型,并在此基础上利用该模型列举了方法运行的案例。 相似文献
2.
3.
人机界面是影响软件设计质量的重要因素之一,需要利用综合评价方法,科学、合理地评判人机界面设计质量。该文分析了人机界面设计的原则,建立了评价指标体系,利用“灰色关联分析”确定评价指标的权重,采用灰色统计方法建立了测评矩阵,借鉴模糊综合评价方法对软件的人机界面进行了合理的评价。 相似文献
4.
5.
在分析了金融事务中进行金融欺诈的现象后,对传统的金融欺诈检测方法进行了分析,并在此基础上提出了一种利用数据挖掘方法进行金融欺诈检测的模型,并在此基础上利用该模型列举了方法运行的案例。 相似文献
6.
7.
8.
9.
装配设计中利用装配约束信息求解有关实体的位置和方向称为装配求解。传统装配求解方法多数利用求解联立方程组的数值解法,效率不高,稳定性差。针对这些不足,我们提出了一种基于几何自由度归约分析的装配求解方法。本文介绍了自由度分析和归约的方法以及基于此方法的装配求解的一般过程。 相似文献
10.
传统的聚类方法大多是基于距离或者是样品间相似度的,这就要求所分析的数据必须是定量的。但是在数据挖掘中,存在着大量的定性数据,传统的聚类分析方法已不再是一个可行的方法,这就需要寻找一个可以有效处理定性数据的聚类方法。粗糙集是处理定性数据的有效方法,在详细阐述粗糙集的相关概念后,利用属性重要性的概念,提出了一种能有效处理定性数据的聚类分析方法,并利用了数据对该方法进行了实证分析,取得了良好的结果。 相似文献
11.
Martin Schoeberl Wolfgang Puffitsch Rasmus Ulslev Pedersen Benedikt Huber 《Software》2010,40(6):507-542
In this paper, we propose a solution for a worst‐case execution time (WCET) analyzable Java system: a combination of a time‐predictable Java processor and a tool that performs WCET analysis at Java bytecode level. We present a Java processor, called JOP, designed for time‐predictable execution of real‐time tasks. The execution time of bytecodes, the instructions of the Java virtual machine, is known to cycle accuracy for JOP. Therefore, JOP simplifies the low‐level WCET analysis. A method cache, which fills whole Java methods into the cache, simplifies cache analysis. The WCET analysis tool is based on integer linear programming. The tool performs the low‐level analysis at the bytecode level and integrates the method cache analysis. An integrated data‐flow analysis performs receiver‐type analysis for dynamic method dispatches and loop‐bound analysis. Furthermore, a model checking approach to WCET analysis is presented where the method cache can be exactly simulated. The combination of the time‐predictable Java processor and the WCET analysis tool is evaluated with standard WCET benchmarks and three real‐time applications. The WCET friendly architecture of JOP and the integrated method cache analysis yield tight WCET bounds. Comparing the exact, but expensive, model checking‐based analysis of the method cache with the static approach demonstrates that the static approximation of the method cache is sufficiently tight for practical purposes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
The fundamental requirement for hard real-time systems is that task deadlines be never missed. As a consequence, knowing tasks worst case execution times (WCET) is crucial for such systems. Taking into account modern architectural features makes it possible to determine tighter WCET bounds than with program analysis that ignores such features. While effects of caches and pipelines on WCET analysis have been extensively studied, to our knowledge the effect of the branch prediction on WCET evaluation has not been studied yet. This paper describes a method for statically bounding the number of timing penalties due to erroneous branch predictions. The proposed method is based on static program analysis and branch target buffer modelling. It consists in collecting information on branch target buffer evolution by considering all possible execution paths of a program. Collected information can then be used to classify control transfer instructions so that their worst case branching cost can be estimated and incorporated into the program WCET. A method is also given to tightly predict the WCET of loops whose number of iterations depend on counter variables of outer loops. Experimental results show that the timing penalty due to wrong branch predictions estimated by the proposed technique is close to the real one, which demonstrates the practical applicability of our method. 相似文献
13.
符号化WCET(worst-case execution time)分析是用符号表达式表示任务的最大执行时间:表达式中包含了参数.通过在运行时刻快速确定表达式值,符号化WCET分析可以更精确地估算WCET.提出了一种针对其分支直接依赖于输入数据的程序的符号化WCET分析方法.首先对Blieberger方法进行扩充,使得WCET符号表达式能够表达依赖输入分支,然后利用程序的控制依赖图对符号表达式进行化简,从而产生带条件的WCET符号表达式,即不同的条件对应不同的符号表达式.与已有方法不同,符号化WCET公式直接依赖于输入参数,使得运行时的WCET估算更加简单直接. 相似文献
14.
程序的最坏执行时间WCET是实时系统时间操作方面的可信基础,现有的WCET静态分析方法都需要对系统某种程度上的额外知识和限定性假设,导致现有的WCET分析方法本质上为偏高估计,降低了资源的利用率和系统的性能。给出一种基于极值统计的程序最坏执行时间估计新方法,采用程序执行时间的测量值作为样本,利用Gumbel分布建立程序最坏执行时间统计模型,根据测量样本序列预测执行时间的最大值,与以往的方法相比,这种方法综合体现了各种硬件特性对程序执行时间的影响,估计结果更为精确,更适合处理硬件特性和软件复杂度较高情况下的程序最坏执行时间估计。实验结果表明利用Gumbel分布建立的WCET估计模型能够快速且有效地给出实时程序的最坏执行时间估计。 相似文献
15.
《Control Engineering Practice》2000,8(6):697-703
This paper studies the worst case execution time (WCET) of PL programs which specify cyclic computing applications. The structure of a PL program differs from that of a sequential program. A PL program contains declarative information about the data to be operated on and about the periodic processes. The WCET of a PL program is defined as WCET for each period of the cyclical application. The processes of a cyclical application may run in different execution modes depending on the context. Not every combination of modes is feasible. Two methods are provided to calculate the WCET of a PL program while taking the unfeasibility constraints into account. One method uses the Integer Linear Programming technique and the other uses heuristic search-based technique. Timing analysis for multiple-period PL programs is also studied. The calculated WCET can be used to validate the timing constraints of the system or to help to decide the sampling rates of the system. 相似文献
16.
面向通用计算机系统的指令预取技术无法满足实时系统的应用需求,其中一个重要原因是:无效预取引起的指令Cache内容污染使得实时任务WCET评估值不够精确,导致系统可调度性下降,严重影响系统效率.以简化实时任务WCET分析、降低任务WCET评估值为目标,提出一种基于程序基本块的指令预取方法.该方法以基本块为粒度执行指令预取,避免了传统指令预取技术引入的无效预取;通过简化最坏情况下的指令访问命中/缺失情况判定,简化任务WCET分析过程并优化WCET评估值.实时基准测试程序评估结果表明:与常规无预取方法相比,该预取方法可使实时任务WCET评估值降低约20%,平均执行情况下的指令Cache访问性能提升约10%. 相似文献
17.
实时系统最坏执行时间分析* 总被引:2,自引:1,他引:1
实时系统开发过程中必须强调时间的重要性和支持时间的可预报性。最坏执行时间分析与可调度性分析构成了实时系统时间方面操作可信的基础。最坏执行时间分析计算任务执行时间的上界,这些任务的上界用来分配正确的CPU时间给实时任务。最坏执行时间是可调度分析工具的输入,可调度分析决定了一组任务在一个给定的目标系统下是否可调度。对最坏执行时间分析方面的研究进行了综述,给出在这一领域所取得的进展。 还讨论了在最坏执行时间分析方面存在的问题,给出了将来的研究方向。 相似文献
18.
事先获知系统中程序最差情况的执行时间(Worst-CaseExecutionTime,WCET),是设计和验证实时系统调度及可调度性分析的前提,也是确定周期性任务是否满足其性能目标,从而发现系统性能瓶颈的基础。本文概述了程序WCET的分析方法,描述了WCET分析的定义和组成,重点总结其中的程序流事实分析方法,并指出程序流事实分析存在的问题和WCET分析的研究热点。 相似文献
19.
The schedulability analysis of real-time embedded systems requires worst case execution time (WCET) analysis for the individual tasks. Bounding WCET involves not only language-level program path analysis, but also modeling the performance impact of complex micro-architectural features present in modern processors. In this paper, we statically analyze the execution time of embedded software on processors with speculative execution. The speculation of conditional branch outcomes (branch prediction) significantly improves a program's execution time. Thus, accurate modeling of control speculation is important for calculating tight WCET estimates. We present a parameterized framework to model the different branch prediction schemes. We further consider the complex interaction between speculative execution and instruction cache performance, that is, the fact that speculatively executed blocks can generate additional cache hits/misses. We extend our modeling to capture this effect of branch prediction on cache performance. Starting with the control flow graph of a program, our technique uses integer linear programming to estimate the program's WCET. The accuracy of our method is demonstrated by tight estimates obtained on realistic benchmarks. 相似文献
20.
Hard real-time systems require absolute guarantees in their execution times. Worst case execution time (WCET) of a program has therefore become an important problem to address. However, performance enhancing features of a processor (e.g. cache) make WCET analysis a difficult problem. In this paper, we propose a novel analysis framework by combining abstract interpretation and program verification for different varieties of cache analysis ranging from single to multi-core platforms. Our framework can be instantiated with different program verification techniques, such as model checking and symbolic execution. Our modeling is used to develop a precise yet scalable timing analysis method on top of the Chronos WCET analysis tool. Experimental results demonstrate that we can obtain significant improvement in precision with reasonable analysis time overhead. 相似文献