In addition , we summarize some spatial join algorithms based on r - tree index and their cost estimation models . we also give out a query optimization algorithm framework based on dynamic programming algorithm , and integrated basic r - tree index method and query optimization mechanism into sadbs ii 另外，本文还总结了几种基于r树索引的空间连接算法及其代价评估模型，利用动态编程算法给出了查询优化的算法框架，并在sadbs中集成了基本的r树索引方法和查询优化机制。
On the basis of collecting and processing many datum and materials . firstly . this paper analyzes main activities and cost constitutions of each stage of the life cycle of a fcs , and lay a foundation for later analysis and evaluation of system lcc . secondly , a basis method and usage range for estimating the system lcc are introduced . a multivariate linear regression model of pcs development cost and cost driven factor is built by use of the parametric method and supplies the base of cost estimation of newly - developed systems . thirdly , combine actual examples and make statistical analysis of lcc of a certain pcs developed by our institute , predict unhappened usage and service cost with grey prediction method , obtain proportion of each constitute to the lcc . forthly , according to actual conditions , use the fuzzy theory to overall evaluate efficacy of the fcs , fifthly , combimng our actual conditions , investigate specific measures of how to implement the life cycle cost management in our institute and put forward a new conception of developing web - based flight control system lcc management information system with pdm as the platform . at last , investigate important factors such as reliability and maintainability that may affect the life cycle cost of the fcs in detail , and put forward specific methods of lowering the life cycle cost of the fcs 论文在收集和整理大量资料的基础上，首先深入分析了飞控系统寿命周期各阶段的主要活动以及各阶段的费用构成，为以后系统寿命周期费用的分析和评价奠定了基础；其次，介绍了寿命周期费用估算的基本方法和使用范围，并利用参数法建立了飞控系统研制费用与费用驱动因子的多元线性回归模型，为新研系统的费用估算提供了依据；第三，结合实例对我所研制的某型飞控系统的寿命周期费用进行统计分析，运用灰色预测方法对未发生的使用及维修费用进行预测，得出了该系统的寿命周期费用以及各组成部分所占比例；第四，根据实际情况，首次运用模糊理论对飞控系统的系统效能进行了综合评价，构造了飞控系统系统效能模糊综合评价模型；第五，结合我所实际，探讨了如何在本单位实施加强寿命周期费用管理的具体措施，提出以pdm为平台，开发基于web的飞控系统lcc管理信息系统的新构思；最后，对影响飞控系统寿命周期费用的重要因素如可靠性和维修性等进行了详细地研究，提出了降低飞控系统寿命周期费用的具体方法。
This paper analyses software cost ’ s component and features , discusses the relationship between software cost estimation and software project management , introduces the software cost estimation ’ s basic steps and train of thought . to solve the problems of uncertain factors and difficulty to decide cost in early period of software project , use neural network and fuzzy theory together to estimate software cost 本文分析了软件项目成本的构成与特点,讨论了软件成本估算与软件项目管理的关系,提出了软件成本估算的基本步骤和思路,并且针对软件项目早期阶段不确定因素多,成本难以确定的问题,提出使用神经网络和模糊理论相结合的方法来进行软件成本估算。
Many mature technologies on this level have been brought out , such as the relational algebra law , the improved logical query plan , the cost estimation of operation , the selective plan based on cost and order of joint , etc . although many methods have been tried out , no remarkable result or noteworthy technology has come to reality because of complexity of data decomposition and network effects 例如，从物理查询计划的底层磁盘输入输出到语法分析阶段的语法分析树、用于改进查询计划的代数定律、逻辑查询计划的改进，以及操作代价的估计、基于代价的计划和连接顺序的选择等全过程，都进行了不懈的努力。在这方面的研究已经非常成熟。
Based on the feature technology and object - oriented mechanism , we found the manufacture - oriented three levels ( namely part , feature and geometry ) model of mechanical part and the resource model ; secondly , we realize the concurrent design of mechanical part and process through decomposing cycle , and then we constitute the evaluation guidelines on the basis of evaluation strategy of levels , which carry out from two levels ( part and feature ) and four phases ( part rough evaluation , feature rough evaluation , feature detail evaluation and part general evaluation ) ; thirdly , we put forward some evaluation methods according the evaluation guidelines , which include the rule - based process evaluation method , rule - based and fuzzy evaluation - based method associated with resources , case - bas ed and feature - based cost estimation method ; at last , we give a manufacturing - oriented evaluation system of rotating mechanical part , which validate the evaluation guidelines and method of the dissertation useful and practical 以特征技术为基础，面向对象的编程机制为手段，建立了面向制造的三层次(即零件层、特征层、几何层)零件模型；同时进行了面向制造的资源建模。第二，通过细化循环，采用分层递阶的评价策略，分两层(零件层和特征层)四个阶段(零件初评价、特征初评价、特征详细评价和零件总体评价)建立可制造性评价指标；第三，以评价指标为基础，分别提出了基于规则的结构工艺性评价方法、基于规则和模糊综合评判定性和定量相结合的加工可行性评价方法、以及基于实例和特征的加工成本估算方法；最后，以solidworks为开发平台， vb6为编程工具，初步构建了面向制造的回转类零件可制造性评价系统，它们验证了本文评价指标和评价方法的实用性和可行性。
