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Economics is an essential tool for understanding the complexities of a modern society.

经济学是一个不可或缺的工具，为了解复杂的现代社会的需要。

The sneak complier machine is an essential tool to the sneak system's development.

嵌入式编译器是嵌入式系统开发的一个必不可少的重要工具。

Because the history of China's development is essential for the development of world history component.

因为中国历史的发展是世界历史发展的必不可少的构成部分。

The application of information technology has become an essential component for the survival and development of enterprises.

21世纪是信息时代，信息技术的应用成了企业生存和发展所不可缺少的组成部分。

The thesis studies the difference between GWSs composition and traditional workflow applications, proposes the implement mechanism and technical architecture of GWSs composition and defines the reference model of GWSs composition platform, which provide holistic framework and top-level guidance for studying dynamic GWSs composition technology, designing GWSs composition platform, and implementing representative composite service applications.2、Theories and methods of composite process modeling and process analysis. This thesis proposes a meta-model of Geo-spatial Web services composition process defining from two aspects, i.e. process and resource. According to the process definition meta-model, we propose a new Geo-spatial Web services composition Process/Resource model based on extended WF-net, which effectively resolves the problems on uncertain activity option and dynamic variation of service in composite process model. A notion with regard to soundness of process model is proposed from three aspects, i.e. the structural correctness of process model, validity of data link and validity of resource. The notion of soundness definitely gives a dividing line on correctness of composite GWS process. This thesis analyzes sufficient and essential terms of soundness, and studies compositional property of WSCP/R-net models which provides an effective method to construct a soundness WSCP/R-net model. According to WSCP/R-net, the thesis proposes composition algebra and studies the properties of it. Based on the composition algebra, 6 kinds of composite process reduction rules are induced to optimize the process.3、Geo-spatial Web service QoS model and its application architecture. This thesis proposes an extendable GWS QoS model from three aspects, i.e. Geo-spatial Web Service itself, networking conditions and service consumer which can be used to distinguish GWSs with overlapping or identical functionality. We work over the QoS evaluation methods of composite GWS process which can be used to guide the execution, monitor and service selection of composition process. Aming at some disadvantages in traditional Web service discovery model for its lacking of QoS supporting, this thesis proposes a new service discovery model SDMQ supporting QoS constraints.4、Technologies of composite service executing. SSPL, a new composite service process language, is defined to overcome the disadvantages of existing composite services process languages which can not adapt to the dynamic variation of Geo-spatial Web Services. An algorithm is described to translate WSCP/R-net model into SSPL. The thesis studies the model of dynamic services selection with QoS global optimization, presenting an algorithm GODSS to resolve dynamic services selection with QoS global optimization in GWSs Composition.5、Design and implement experimental system and representative applications. According to the research findings presented above, we design and implement an experimental system and construct two representative applications to show that our achievements are effective and practical.

针对当前空间信息服务聚合研究中存在的若干不足，本文重点在基于工作流的空间信息服务聚合框架、空间信息服务聚合流程建模和分析技术、空间信息服务QoS模型及应用体系以及空间信息服务聚合流程执行等几个方面进行深入研究，主要工作和创新点包括：1、基于工作流的空间信息服务动态聚合框架：研究了空间信息服务动态聚合和传统工作流应用的不同，在此基础上提出了基于工作流技术的空间信息服务动态聚合实现机制、技术体系和参考模型，为研究空间信息服务聚合的关键技术、开发服务聚合支撑平台以及在此基础上构造特定的空间信息服务聚合应用提供了总体框架和顶层指导。2、空间信息服务聚合流程建模和分析技术：首先基于动态服务聚合流程建模的需求和空间信息服务动态变化的应用实际，从服务聚合的过程维和资源维出发定义了服务聚合流程定义元模型；与之相对应，对基本的WF-net进行扩展，提出服务聚合流程/资源网作为空间信息服务聚合流程的形式化描述模型，有效解决了现有的基于基本Petri网和工作流网的服务聚合建模方法所不能解决的不确定路径选择和服务的动态变化性问题；从流程结构正确性、数据依赖有效性和资源实现有效性三个方面提出了WSCP/R-net健壮性的概念，明确界定了聚合流程正确性的标准，并对WSCP/R-net模型的健壮性分析方法和WSCP/R-net模型的组合特性进行了研究；提出了空间信息服务聚合代数算子并对其性质进行了研究，在此基础上提出了6种聚合流程约简规则，从而可达到优化聚合流程、提高聚合流程执行效率的目的。3、空间信息服务QoS模型和应用体系：从服务本身、网络环境和服务消费者三个层次出发，提出了一个可扩展的空间信息服务QoS模型GSQM，实现了对空间信息服务的度量和评价，并对GSQM不同质量要素信息的客观、公正采集方法进行了研究；研究了空间信息服务聚合流程QoS评价方法，有效支持了空间信息服务聚合流程的执行、监控以及服务选择等操作；针对目前的服务发现模型仅支持服务功能性描述、不能有效满足空间信息服务应用需求的现状，提出了一种新的支持QoS约束的服务发现模型SDMQ，并对模型的实现框架进行了研究。4、空间信息服务聚合流程执行技术：针对现有的服务聚合流程描述语言不能有效满足空间信息服务动态聚合流程描述的特点，基于BPEL4WS提出了一种新的空间信息服务聚合流程描述语言SSPL；研究了满足健壮性要求的WSCP/R-net模型向SSPL的转换算法，在此基础上可以满足用户无显式编码来实现空间信息服务聚合应用的目的；研究了服务动态选择QoS全局优化模型，并在此基础上提出了一种解决服务动态选择QoS全局优化问题的实现算法GODSS.5、基于论文研究成果，设计实现了"空间信息服务聚合实验系统"，并构建了"矿产资源评价"和"城市消防应急响应"两个典型应用案例，对论文所述模型、方法的可行性和有效性进行了验证。

These features are essential for the kind of compositional development that makes functional programming so powerful.

这些特征正是这种使得函数编程变得如此强大的组合化开发的核心。

Data applications are set up resources for interoperable model of heterogeneous database environment or file system connected to achieve implementation of the middleware connectivity; at Distributed System, the essential data are concentrated in the data storage server, they can be a relationship between the type, compound document type, with a variety of multimedia-based storage format, or are encrypted or compressed storage, such middleware for virtual buffer at the network access, format conversion, extracting and other convenient

是为了建立数据应用资源互操作的模式，对异构环境下的数据库实现联接或文件系统实现联接的中间件；在分布式系统中，重要的数据都集中存放在数据服务器中，它们可以是关系型的、复合文档型、具有各种存放格式的多媒体型，或者是经过加密或压缩存放的，这类中间件将为在网络上虚拟缓冲存取、格式转换、解压等带来方便

Life. That's not essential but it's much more than just having a better positive compulsion.

这并不是必需的但有一个更好的积极的冲动真的很更好。

In today's world of computerised working and developing technology, continued education is often essential for people to meet the changing requirements of their profession.

在工作电脑化和科技不断发展的今天，为了满足人们职业的不断变化的需求，继续教育是非常必要的。

The essential problem of man in a computerized age remains the same as it has always been.

在计算机时代，人类的基本问题依然是过去一直存在的问题。

Since historical times,England ,where the early inhabitants were Celts, has been conquered three times .

从有历史以来，英国，在此地早期居住的是凯尔特人，已经被征服了三次。

Bluetooth OBEX File Transfer Enables the sending and receiving of files on your phone via Bluetooth.

蓝牙OBEX文件移动允许经过蓝牙传送和接受文件。。。。