基于Marquardt和Runge-Kutta算法的发酵过程建模

利用简单的线性模型很难描述发酵这类复杂的非线性动态过程,因此需要利用非线性方法对该类过程进行建模。为此,提出了利用基于Marquardt算法的非线性回归方法和基于四阶Runge-Kutta算法的非线性微分方程求解方法对发酵过程进行建模分析;并进一步利用统计方法分析了该非线性回归方法的有效性。该方法应用于黄酒发酵过程中,实现了黄酒发酵过程模型的求解和模型参数的动态优化。     

基于LabWindows/CVI的联合时频分析

在LabWindows/CVI平台的基础上,研究了利用联合时频分析(JTFA)方法来分析信号的能量分布情况。此方法利用了短时傅里叶变换(STFT)的基本原理,对一些非平稳信号进行分析,能很好地描述信号的频率如何随时间而变化。这种方法比单独利用时域或频域来分析信号具有一定的优越性。     

基于VB的FrontPage2000文档分析

本文主要讨论的是如何利用Visual Basic来分析FrontPage2000文档,文章首先研究了Frontpage2000的对象模型,提出了利用Frontpage文档内部的HTML代码和利用Frontpage的对象模型中对象两种方法分别对FrontPage2000文档进行分析,然后提出了两种方法的优缺点,最后提出了用两种方法的结合来分析FrontPage2000文档新观点。     

MATLAB时频分析工具箱在VisualC++程序设计中的应用研究

在分析利用MATLAB函数开发独立可执行VisualC++应用程序的优势和接口技术的基础上,克服以往该方法不能调用MATLAB工具箱函数的不足,探讨了一种能在VisualC++中利用MATLAB时频分析工具箱函数编制独立可执行应用程序的方法。笔者在利用该方法编制旋转机械振动信号时频分析软件收到了良好的效果。     

密码协议的Promela语言建模及分析

给出了利用SPIN模型检测分析密码协议的一般方法。作为一个实例,对Needham Schroeder 公钥密码协议用Promela语言建模,并利用SPIN进行了分析验证,发现了其安全漏洞。该方法很容易推广到有多个主体参与的密码协议的分析     

土地可持续综合评价与时空分析——河南省为例

针对目前土地可持续利用评价标准不一、土地利用评价缺乏时空统一分析等问题,采用频数统计、主成分分析等方法筛选了显著评价指标,确定了各个指标的相对权重,构建了较为科学全面的评价指标体系,提出了土地可持续利用的综合评价及时空分析法。以河南省为例,将河南省18个省辖市和省直管县级市作为研究单元,根据河南省2006~2014年的统计年鉴以及省辖市的年鉴获取数据,采用聚类方法确定评价标准,并利用分段分析、横向比较、热点分析等方法对河南省的土地可持续利用情况进行时序和空间分异分析,结果较好地反映了10年来河南省土地可持续利用发展的情况。论文同时对河南省土地可持续利用发展提出了相关的建议。案例研究证明了该方法的可行性和有效性,为其他地区土地可持续利用评价提供借鉴和参考。     

文件操作访问大容量ODBC数据库的技巧讨论

以访问印花机工艺数据库为实例,简要分析了大容量ODBC数据库存在的问题,并阐述了利用文件操作动态访问Access数据源的两种方法,分析了利用此方法分解大容量数据库为小型数据库的可行性.     

数据仓库技术在医院病情诊疗分析中的应用研究

分析了病案统计分析系统的现状及存在的不足.为了使病案得到充分的有效的利用,提出了将数据仓库技术应用其中的方法.以病情诊疗分析为主题,介绍了此方法的原理及主要功能,给出方法实现的具体步骤,对方法的关键部分进行了详细的解释说明.其核心思想是通过数据仓库来清洗纷繁芜杂的数据,然后利用联机分析系统独特的多维方式对数据进行分析,使用户从不同的维了解历史及现状,最后利用数据挖掘工具自动地挖掘潜在的模式,找到正确的决策.     

基于密码技术的数字水印研究

分析了Cox等人关于水印结构的理论,提出了利用密码技术构造水印序列的方法。利用该方法既实现了对版权信息的直观有效标识、又构造出了具有较强鲁棒性的水印。最后利用该方法实现了JPEG图像的数字水印。     

数据仓库技术在医院病情诊疗分析中的应用研究

分析了病案统计分析系统的现状及存在的不足。为了使病案得到充分的有效的利用,提出了将数据仓库技术应用其中的方法。以病情诊疗分析为主题,介绍了此方法的原理及主要功能,给出方法实现的具体步骤,对方法的关键部分进行了详细的解释说明。其核心思想是通过数据仓库来清洗纷繁芜杂的数据,然后利用联机分析系统独特的多维方式对数据进行分析,使用户从不同的维了解历史及现状,最后利用数据挖掘工具自动地挖掘潜在的模式,找到正确的决策。     

Worst‐case execution time analysis for a Java processor

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.     

Worst Case Execution Time Analysis for a Processor with Branch Prediction

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.     

包含依赖输入分支程序的符号化WCET分析

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.     

Timing analysis of PL programs

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.     

程序最坏执行时间极值统计方法

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。     

一种面向实时系统的程序基本块指令预取技术

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%.     

实时系统最坏执行时间分析*

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。     

实时系统程序最差情况执行时间(WCET)的分析

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。     

Modeling Control Speculation for Timing Analysis

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.     

Scalable and precise refinement of cache timing analysis via path-sensitive verification

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.