表达式求值算法比较

论述了表达式求值相关算法的实现过程及分析。     

算术表达式求值算法实现的难点剖析

在分析算术表达式求值算法的基础上,对如何实现＂算符优先关系＂的比较、如何设定栈中元素的类型、如何将数字字符串转换为相应的数字等几个难点进行了剖析,并给出了不同的解决方案。     

将中缀表达式转换成后缀表达式的三种方法

本文给出了已知中缀表达式求解后缀表达式的三种方法。     

栈在表达式求值中的应用

栈是限定只能在表的一端进行插入和删除的线性表。根据栈的这种存取特征,栈也被称为后进先出表。生活中的穿衣脱衣、九连环游戏、括号匹配等都是应用栈的这一特点。栈的基本操作包括入栈、出栈、得到栈顶元素、判断栈空、判断栈满等等。在该文中我们将讨论栈在中缀表达式求值、后缀表达式求值以及后缀表达式转换成中缀表达式中的应用。     

栈在表达式求值中的应用

栈是限定只能在表的一端进行插入和删除的线性表。根据栈的这种存取特征,栈也被称为后进先出表。生活中的穿衣脱衣、九连环游戏、括号匹配等都是应用栈的这一特点。栈的基本操作包括入栈、出栈、得到栈顶元素、判断栈空、判断栈满等等。在该文中我们将讨论栈在中缀表达式求值、后缀表达式求值以及后缀表达式转换成中缀表达式中的应用。     

表达式求值器在工作流中的应用

在工作流管理系统中需要广泛地使用表达式。工作流管理系统需要在定义时对表达式进行静态的编译,发现其中的错误;在运行时能够动态地对表达式求值。文章提出了一种基于Java的工作流引擎设计中用JavaCC和JJtree设计和开发表达式求值器的实现方法。     

VC++6.0环境下C表达式求值潜规则揭密

针对初学者在C表达式求解过程中遇到的问题,通过剖析一组典型实例,提出了在常用编译环境VC++6.0下表达式求值的5个潜规则.     

由表达式求值说开去

“本文通过一个算术表达式的求值过程引出了编写程序的基本方法,通过问题小发寻求解得一个过程。在文中讨论了有关中缀表达式和后缀表达式求值的一些基本算法问题,并讨论了有关栈,线性结构,映射结构等基本数据结构。最后讨论了软件设计对于扩展算法功能和实现复杂结构的灵活性的一些思路和方法。”     

具备逻辑表达式解析功能的小区联动监控系统的设计

本文介绍了一套基于单片机的具备逻辑表达式解析功能的小区联动监控系统的软硬件设计，本系统通过合理分配设置存储器的信息及编程，完成了对各传感器输入通道和继电器输出通道的联动组合设置和控制。     

基于算符优先算法的逻辑表达式合法性判断

基于字符串的逻辑表达式的合法性进行判断在很多领域和场合下是经常遇到的 ,比如 :文件检索 ,信息查询等等 .而我们常见的文件检索与信息查询软件大多仅仅支持几个简单的逻辑算符 ,例如 :与、或 ,并且逻辑表达式中的组成字符串只能做简单的与、或运算 ,使得逻辑表达式的表达能力有限 ,用户使用的灵活性小 .本文针对上述问题进行了研究 ,采用算符优先算法给出了对该问题一种非常实用而又简练的实现方法 ,不但实现了普通搜索引擎所支持的简单的逻辑表达式的合法性判断功能 ,而且扩展了所支持的逻辑表达式的逻辑表达能力 :支持非运算 ;增加了支持逻辑表达式的优先级算符“(”和“)”.这使得逻辑表达式的表达功能和表达灵活性都得到很大的增强和提高 .本文给出的算法还可用于许多其他的基于字符串的逻辑表达式的操作功能 .     

逻辑实体的行列模板的设计与实现

在现实中存在许多这样的实体,它需要关系数据库中多个相关的记录一起才能完整地表示其意义,且这些记录之间通常具有行和列上的计算关系,使用传统的方法不能很好地实现这样的实体.针对该情况,提出逻辑实体及其行列模板的概念,设计逻辑实体和行列模板的关系模式,给出行列模板的实现,并结合一个实例,详细说明了行列模板的具体应用.     

数字逻辑实验动态演示系统设计与实现

针对传统数字逻辑实验课的讲授过程不能形象地演示实验过程这一问题,提出利用Flash技术制作数字逻辑实验动态演示系统,将5个数字逻辑实验和实验内容以片头、界面、导航、填空题的形式进行连接,对实验中的重点难点进行演示和交互式讨论。该系统有利于激发学生学习数字逻辑实验课的积极性,提高动手操作能力,提高课堂效率和教学质量。     

立地评价系统的设计与实现

针对目前基层林农与林场在森林经营管理中的立地评价问题,探讨了利用林分生长模型对有林地进行评价的方法与技术,建立了以定距等分算法为核心,采用好、中、差立地等级对有林地进行评价的方法,设计了林分生长模型库,实现了生长模型解析算法.在此基础上,设计了立地评价系统工作流程和立地评价系统架构,结合无林地评价开发了基于浏览器与服务器体系结构的综合立地评价系统,从而有效满足了在只有林分生长模型情况下的立地评价需求.     

An implementation of logical analysis of data

Describes a new, logic-based methodology for analyzing observations. The key features of this “logical analysis of data” (LAD) methodology are the discovery of minimal sets of features that are necessary for explaining all observations and the detection of hidden patterns in the data that are capable of distinguishing observations describing “positive” outcome events from “negative” outcome events. Combinations of such patterns are used for developing general classification procedures. An implementation of this methodology is described in this paper, along with the results of numerical experiments demonstrating the classification performance of LAD in comparison with the reported results of other procedures. In the final section, we describe three pilot studies on applications of LAD to oil exploration, psychometric testing and the analysis of developments in the Chinese transitional economy. These pilot studies demonstrate not only the classification power of LAD but also its flexibility and capability to provide solutions to various case-dependent problems     

软件可靠性测试及评估平台的设计与实现

设计并实现了软件可靠性测试与评估平台,支持软件可靠性测试用例自动生成,便于可靠性数据收集以及软件可靠性评估和预测,解决了软件可靠性测试难以有效开展的问题。通过与SMERFS预测结果对比,表明本平台对软件可靠性测试与评价具有较强的实用性。     

Ad hoc网络多层混合实验系统的设计与实现

现有的多数Ad hoc实验系统均基于Linux/Unix操作系统,存在层次结构简单、系统控制复杂等问题。为此设计并实现了一个基于Windows系统的多层混合Ad hoc实验系统,支持网络各个层次协议的测试与验证,其模块化的可配置结构易于进行新协议算法的开发,系统测试操作控制简单。     

Design, implementation and evaluation of an adaptive user interface

Software systems developed in recent years are becoming increasingly powerful, but in most cases they tend to abandon the user to deal with the complexity of the system alone. There is an immense need for systems with individual, context-sensitive support. The paper discusses the development of such a support system with special focus on the user interface. The extension of an existing and complex program. Excel, to an adaptive and customizable system is described. This extension is called Flexcel, and it has been implemented and evaluated.

The primary aim of this extension is to provide a convenient environment for adapting Excel's user interface to particular users and their current tasks. For example, it allows the user to define new menu for actions that are frequently needed and normally require a tedious dialog step. Flexcel also analyzes the user's interaction style and presents adaptation suggestions. A critique component supports the user in his/her problem solving and learning activities related to the adaptability of Flexcel's user interface.     

Design, implementation, and evaluation of differentiated caching services

With the dramatic explosion of online information, the Internet is undergoing a transition from a data communication infrastructure to a global information utility. PDAs, wireless phones, Web-enabled vehicles, modem PCs, and high-end workstations can be viewed as appliances that "plug-in" to this utility for information. The increasing diversity of such appliances calls for an architecture for performance differentiation of information access. The key performance accelerator on the Internet is the caching and content distribution infrastructure. While many research efforts addressed performance differentiation in the network and on Web servers, providing multiple levels of service in the caching system has received much less attention. It has two main contributions. First, we describe, implement, and evaluate an architecture for differentiated content caching services as a key element of the Internet content distribution architecture. Second, we describe a control-theoretical approach that lays well-understood theoretical foundations for resource management to achieve performance differentiation in proxy caches. An experimental study using the Squid proxy cache shows that differentiated caching services provide significantly better performance to the premium content classes.     

Design,implementation and evaluation of a virtual storage system

Large organizations always have a strong demand for storage from data‐intensive applications and instruments. In this paper, we present the design, implementation, and evaluation of a new virtual storage system, Storage@desk, which can aggregate a large number of distributed machines within an organization to provide storage services with quality of service guarantees. Because storage virtualization is the prominent goal, Storage@desk provides clients with the abstraction of a hard drive by utilizing the Internet SCSI protocol. As such, data access to new storage services is transparent so that clients do not need to modify any existing applications nor change their current practices. Storage@desk replicates data and employs version‐based journaling for high availability. It utilizes a market‐based model for resource management and a feedback controller for automated performance control. We have developed a prototype of Storage@desk that implements the core components. Copyright © 2010 John Wiley & Sons, Ltd.     

Systematic evaluation of logical story unit segmentation

Although various logical story unit (LSU) segmentation methods based on visual content have been presented in literature, a common ground for comparison is missing. We present a systematic evaluation of the mutual dependencies of segmentation methods and their performances. LSUs are subjective and cannot be defined with full certainty. To limit subjectivity, we present definitions based on film theory. For evaluation, we introduce a method measuring the quality of a segmentation method and its economic impact rather than the amount of errors. Furthermore, the inherent complexity of the segmentation problem given a visual feature is measured. Also, we show to what extent LSU segmentation depends on the quality of shot boundary segmentation. To understand LSU segmentation, we present a unifying framework classifying segmentation methods into four essentially different types. We present results of an evaluation of the four types under similar circumstances using an unprecedented amount of 20 hours of 17 complete videos in different genres. Tools and ground truths are available for interactive use via the Internet.