卫星观测任务数据的XML描述

将XML技术用于描述卫星观测任务数据库,特别是用XML模式描述了任务的数据结构和数据内容,同时强调了数据语义的体现。目的是实现卫星观测数据的标准化,方便未来跨领域、跨平台卫星观测任务的统筹规划和执行。     

可扩展性卫星任务规划系统的设计与实现

针对现有卫星任务规划系统可扩展性差的特点,设计并实现了一种类似于HLA(High Level Architecture)框架的可扩展性卫星任务规划系统HES3(High-Extensible Satellite Scheduling System).为保证HES3的可扩展性,提出了基于专家系统和约束分离的卫星任务规划算法的两阶段规划处理机制.设计了基于类甘特图和GIS(Geo-graphic Information System)视图的规划结果可视化人机交互接口.最后,通过一个应用实例说明了HES3的运行过程.     

基于XML的想定描述与作战任务分析

分布交互式作战仿真系统对作战想定的描述和作战任务的分析依赖于统一的表达格式和功能强大的表示手段.该文通过对XML在数据表达与交互方面的介绍,探讨了基于XML的想定描述与作战任务分析的基本方法.提出了在分布交互作战仿真系统中通过XML文档的发布,实现异构信息的交换与共享的一种思路.     

基于XML的潜艇作战仿真想定开发

作战仿真想定是军事仿真系统的重要组成部分,为仿真系统的运行提供了初始态势和作战任务.目前在仿真想定中存在的主要问题是对想定描述的格式和手段不统一,生成的仿真想定可读性和可移植性不好,影响了仿真系统的真实性和可信度.该文着眼于解决上述问题,通过分析潜艇作战想定描述的层次结构,针对XML技术在数据表达方面的特点和应用,探讨了使用XML表示标准的潜艇作战想定开发方法,并对仿真想定编辑系统进行了实现.为潜艇作战仿真系统的剧情开发与编辑提供了标准化的思路.     

一种基于HLA的卫星分布式仿真系统研究及其应用

卫星系统的仿真是一个多因素、多学科、多节点的复合性问题,传统的仿真方法存在扩展性和重用性差等缺点。基于HLA体系规范,构建一个良好扩展性和重用性的仿真系统能够对卫星总体设计方案进行仿真演示和验证,进一步提高卫星总体设计方案的科学化水平。基于HLA的卫星分布式仿真系统的优点在于不需对仿真系统主题框架做任何更改的情况下,通过XML配置文件实现不同任务目标的卫星任务仿真系统,从而实现仿真组建的发展和重用,解决单机系统仿真大规模扩展困难和难以真实描述系统间数据交互的难题。     

卫星任务规划系统时间窗口模块的设计与实现

设计并实现了卫星任务规划系统的时间窗口模块。通过数据接口设置任务的约束要求,利用STK(Satellite Tool Kit)的时间窗口计算能力,计算卫星传感器对于地面目标的可用时间窗口,以简化资源调度模块的求解过程。对于没有可用时间窗口的任务,时间窗口模块能分析时间窗口分配失败的原因,用户可以根据失败原因来分析卫星系统的动态能力。     

基于XML的仿真数据管理技术

为了解决仿真中复杂数据的描述问题,实现数据管理,在仿真中引入了XML语言.介绍了XML语言的特点,研究了XML文档的典型结构,分析了XML语言在数据管理应用上的优势.基于XML语言实现了仿真输入数据和输出数据的描述,并结合XML语言灵活性、扩展性强的特点,研究了数据集成策略,实现了仿真数据管理.应用实践表明,XML可以很方便地描述各种不同类型的数据,有利于复杂数据整合和处理,能够提升仿真的数据管理效率.     

XML物化视图远程增量维护在试验任务数据接口同步中的应用

在试验任务中引入XML文档数据接口,一方面提高了远程数据查询分析的效率,另一方面也产生了XML物化视图的维护带来的高系统开销的问题.针对该问题,采用XML物化视图远程增量维护的方法,通过系统原型设计、系统部署、同步机制,可有效地实现试验任务数据接口同步.结果表明,在不影响试验任务数据处理与传输的实时性及可靠性的条件下,XML物化视图远程增量维护有效地实现了指挥显示系统数据接口的一致性.     

MARC数据转换为XML格式文档的实现方法及应用

阐述了MARC元数据的XML描述技术,讨论了MARC数据向XML数据的转换方法,并以一个MARC文件为例,实现了到XML文档的转换.研究成果对数字图书馆的建设具有重要意义.     

卫星全球普查任务规划系统预处理模块的开发

全球普查任务利用地球观测卫星季节性地动态监测地球表面变化，是遥感技术在全球变化监测中一种应用。卫星全球普查任务规划系统为全球普查任务的实施提供了技术和工具支持。该文介绍了卫星全球普查任务规划系统中预处理模块的设计和实现，分析了预处理模块的结构和功能，重点讨论了全球表面场景划分的可视化、时间窗口计算和分析、卫星日常图像采集活动中候选场景的确定和场景拍摄优先级的动态调整的关键技术。     

一种XML解析器技术的研究与实现

介绍了XML解析的详细过程,设计并实现了一个特定Schema的XML解析器的自动生成工具。该生成工具以一个XML Schema文件作为输入,输出一个JavaCC词法和语法规格说明文件,然后在JavaCC工具的帮助下,生成一个基于特定XML Schema的XML解析器。实验证明,这个生成解析器能够对XML文档进行解析的同时,验证其有效性。     

Static analysis of XML transformations in Java

XML documents generated dynamically by programs are typically represented as text strings or DOM trees. This is a low-level approach for several reasons: 1) traversing and modifying such structures can be tedious and error prone, 2) although schema languages, e.g., DTD, allow classes of XML documents to be defined, there are generally no automatic mechanisms for statically checking that a program transforms from one class to another as intended. We introduce XACT, a high-level approach for Java using XML templates as a first-class data type with operations for manipulating XML values based on XPath. In addition to an efficient runtime representation, the data type permits static type checking using DTD schemas as types. By specifying schemes for the input and output of a program, our analysis algorithm will statically verify that valid input data is always transformed into valid output data and that the operations are used consistently.     

Rules about XML in XML

We developed three different rule-based systems, each designed to take XML as input and produce XML as output and manipulate intermediate facts as XML. They use very different methods of representing the XML during rule processing. Our series of benchmarks show when each representation is best. We also developed an XML language for representing the rules. The markup to recognize an input XML is a sample of that input; certain fields are replaced with special tags to match variables against text or subtrees within the input XML. The output or intermediate XML is also represented by a sample of the output XML. We also report on a graphical user interface developed for developing the rules in this special XML language.     

基于XML的网络服装定制系统的设计与实现

介绍了 XML的概念和基本特点 ,分析了 XML在数据交换以及数据存储方面的应用。通过一个具体的实例展示了 XML技术在网络服装定制系统中的应用     

Automatic property‐based testing and path validation of XQuery programs

Property‐based testing has gained popularity in recent years in many areas of software development. The specification of assertions/properties helps to understand the semantics of pieces of code, and in modern programming environments, it can serve to test the program behavior. In this paper an XQuery property‐based testing tool is presented, which enables to automatically test XQuery programs. The tool is able to systematically generate XML instances (i.e., test cases) from a given XML schema, and to filter XML instances with input properties specified by the programmer. Additionally, the tool automatically checks output (respectively, input‐output) properties in each output instance (respectively, each pair of input‐output instances). The tool is able to report whether the XQuery program passes the test, that is, if all the test cases satisfy the (input‐)output property, as well as the number of test cases used for testing. In addition, if the XQuery program fails the test, the tool shows counterexamples found in the test cases. Properties are specified with XQuery Boolean functions, and the testing tool has been implemented in XQuery. Additionally, an XQuery path validation tool is presented. This tool is able to detect wrong paths in XQuery expressions. The path validation tool takes as input an XML schema, and it reports those paths on the XQuery program that do not match the XML schema. The path validation tool is a complement to the testing tool rejecting XQuery programs that do not conform to the XML schema. The path validation tool has been also implemented in XQuery. Finally, a web tool has been developed enabling to test and validate XQuery programs.     

XML stream transformer generation through program composition and dependency analysis

XML stream transformation, which sequentially processes the input XML data on the fly, makes it possible to process large sized data within a limited amount of memory. Though being efficient in memory-use, stream transformation requires stateful programming, which is error-prone and hard to manage.This paper proposes a scheme for generating XML stream transformers. Given an attribute grammar definition of transformation over an XML tree structure, we systematically derive a stream transformer in two steps. First, an attribute grammar definition of the XML stream transformation is inferred by applying a program composition method. Second, a finite state transition machine is constructed through a dependency analysis. Due to the closure property of the program composition method, our scheme also allows modular construction of XML stream transformers.We have implemented a prototype XML stream transformer generator, called altSAX. The experimental results show that the generated transformers are efficient in memory consumption as well as in execution time.     

基于智能适配器的气象数据入库通用模型

针对气象数据入库工作量较大的问题,提出一种基于智能适配器的气象数据入库通用模型。将可扩展标志语言作为元数据表示方法,利用JAXB技术读取和写入元数据。使用脚本语言处理适配器的规则配置问题,提高气象数据的智能性。基于该模型,构建气象数据通用入库系统。运行结果表明,该系统具有高度灵活性和可扩展性。     

基于XML的数学模型管理平台

为解决多数管理平台存在的诸如模型信息交流不畅、异构数据处理不便、模型输出不易重用等问题 ,提出了基于 XML的数学模型管理平台构建方法 ,该方法充分利用了最新的 XML技术。使数学模型可以方便地发布、组合、查询和调用 ,为建立实用的数学模型管理平台提供了一种可行的方法。实践证明该平台可以广泛应用在数据输入格式化的数学模型运算软件系统中。     

基于XML的体育数据规格化存储技术研究

计算机辅助体育训练是融合了信息技术、生物力学和运动训练学的交叉学科,而体育训练数据的规格化存储问题又是它的基础。由于体育训练数据项本身不确定性,使得传统技术很难灵活地记录训练数据。可扩展标记语言XML是W3C提出的一种元标记语言。该文介绍了清华大学体能训练系统采用XML技术存储体育训练数据的方法,从而克服了数据项的不确定性问题,还使得被存储数据具有灵活的扩展性和良好的自描述性。     

Using XML to improve the productivity and robustness in application development in geosciences

In this paper, we describe an approach to apply Extensible Markup Language (XML) technologies to improve the robustness of geological and geophysical applications as well as to increase the efficacy in the application development process. Geological and geophysical applications are often data centric, I/O intensive and their development is incremental. Therefore, significant amount of development resources is devoted to the design and reengineering of the container data structures that store data. This process is time consuming, mechanical and error prone. Normally, ad hoc parsers are necessary for reading inputs, as well as numerous filters, or adapters to transform the data for integration with other legacy applications. Most of this can be avoided by using XML-related technologies. XML has a type system schema that can be used to define input parameters and constraints. The XML parser can validate the input data using the constraints defined in the schema. Exporting results in XML format allows the use of Extensible Stylesheet Language Transformations (XSLT) to transform XML output to any other format necessary for integration with legacy applications. Additionally, XML-data binding code can be automatically generated in specified languages such C++ and Java. We used this approach to develop applications for seismic ray-tracing and basin modeling with great success, and the major benefits of this approach were the significant gains in productivity during the developement and application robustness.