扭矩法拧紧工艺条件下装配质量的评定与控制

扭矩拧紧方法在现代螺纹副装配作业中占有主要地位,也是目前螺栓紧固所采用的一种主要的方法。但如何在这种工艺条件下对螺纹副的联结质量进行评定、控制,则是一个需要解决的实际问题,本文就此进行了一些探讨。     

浅谈创新与标准化

标准化是通过制定和实施标准,使重复事务达到统一以获得最佳秩序和社会效益的技术。国防科技工业是国家战略性产业,是产品研制生产的物质和技术基础,是国家创新体系的一支重要力量。标准化是国防工业现代化建设与管理的技术基础。高质量高水平的标准是建设现代化国防的重要技术基础。胡锦涛总书记对“十一五”时期国防科技工业提出明确要求“坚持强化基础,自主创新,努力提高科研和制造水平”。     

运动目标轨迹分类与识别

运动目标轨迹识别是运动分析中的基本问题,其目的是解释所监视场景中发生的事件,对所监视场景中运动目标轨迹的行为模式进行分析与识别,智能地做出自动分类.对轨迹有效性判断后采用K均值聚类,引入改进的隐马尔可夫模型算法,针对轨迹的复杂程度对各个轨迹模式类建立相应的隐马尔可夫模型,利用训练样本训练模型得到可靠的模型参数,计算测试样本对于各个模型的最大似然概率,选取最大概率值对应的轨迹模式类作为轨迹识别的结果,对两种场景中聚类后的轨迹进行训练与识别,平均识别率较高,实验结果表明该方法是有效的.     

谈谈《开国将帅》系列肖像油画

王孝柏同志创作的系列肖像油画--<开国将帅>,是一项艰巨、浩大的油画创作工程.它是以为共和国诞生立下显赫战功的十大元帅和十大将为创作对象,每位将帅的形象按构思要求,均须设计为胸像式的"标准像"构图,每位将帅的服装、佩饰基本一致,形式统一.     

Estimating failure time distribution and its parameters based on intermediate data from a Wiener degradation model

Instead of measuring a Wiener degradation or performance process at predetermined time points to track degradation or performance of a product for estimating its lifetime, we propose to obtain the first‐passage times of the process over certain nonfailure thresholds. Based on only these intermediate data, we obtain the uniformly minimum variance unbiased estimator and uniformly most accurate confidence interval for the mean lifetime. For estimating the lifetime distribution function, we propose a modified maximum likelihood estimator and a new estimator and prove that, by increasing the sample size of the intermediate data, these estimators and the above‐mentioned estimator of the mean lifetime can achieve the same levels of accuracy as the estimators assuming one has failure times. Thus, our method of using only intermediate data is useful for highly reliable products when their failure times are difficult to obtain. Furthermore, we show that the proposed new estimator of the lifetime distribution function is more accurate than the standard and modified maximum likelihood estimators. We also obtain approximate confidence intervals for the lifetime distribution function and its percentiles. Finally, we use light‐emitting diodes as an example to illustrate our method and demonstrate how to validate the Wiener assumption during the testing. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Optimal control of a production process subject to AOQL constraint

A production process which exhibits a decreasing pattern in the mean quality during the course of production is considered. A lower limit is specified for the quality characteristic of interest, and an item is classified as defective if its quality characteristic is below this lower limit. The major concern of the manufacturer is the average outgoing quality (AOQ). Hence, the process has to be adjusted after a time to avoid producing a large proportion of defective items due to deteriorating quality. To meet consumer specifications, an average outgoing quality limit (AOQL) is specified. A process-control scheme is developed in which decisions as to the upper and lower limit of the process mean are made based upon the choice of an AOQL. We discuss the decision problem of selecting the starting level of the process mean, and the level at which the process mean should be adjusted back to the starting level, so that the AOQ is not larger than AOQL. We consider a cost model which includes a fixed cost for adjustment, and a production cost which is assumed to be a function of the quality level. Due to the complexity of the model, a search procedure is used to find the optimal solution. In addition, an approximate solution which requires only simple calculations is developed, and is shown to be very effective in finding near-optimal solutions.     

Approximation results for min‐max path cover problems in vehicle routing

This article studies a min‐max path cover problem, which is to determine a set of paths for k capacitated vehicles to service all the customers in a given weighted graph so that the largest path cost is minimized. The problem has wide applications in vehicle routing, especially when the minimization of the latest service completion time is a critical performance measure. We have analyzed four typical variants of this problem, where the vehicles have either unlimited or limited capacities, and they start from either a given depot or any depot of a given depot set. We have developed approximation algorithms for these four variants, which achieve approximation ratios of max{3 ‐ 2/k,2}, 5, max{5 ‐ 2/k,4}, and 7, respectively. We have also analyzed the approximation hardness of these variants by showing that, unless P = NP , it is impossible for them to achieve approximation ratios less than 4/3, 3/2, 3/2, and 2, respectively. We have further extended the techniques and results developed for this problem to other min‐max vehicle routing problems.© 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

浅谈产品研制开发中金属材料选取确定应遵循的原则

作为产品研制开发过程中非常重要的关键环节——金属材料的科学合理选取确定,是确保产品零件具备最佳安全可靠性,最高工作寿命,良好经济性和批生产稳定性的重要基础之一。本文探讨了产品研制开发中金属材料的选取确定应遵循的原则,以求共识。     

刍议GJB 1371与GJB 3837的关系

在新装备的研制过程中,需要有效地开展保障性分析工作,同时会产生大量的信息,GJB 3837便是为有效地存储这些信息而制定的标准。为明确GJB 3837与保障性分析工作之间的对应关系,本文对GJB 1371与GJB 3837进行了简要介绍,并对二者之间的对应关系展开研究,以期为GJB 1371和GJB 3837的工程化应用奠定基础。     

浅析以法律形式控制网络军备竞赛的必要性

网络战是近年来全球军事界相当热的话题,其作为一种全新概念的组织机构,已经开始登上了军事舞台。美国、韩国等国家先后宣布组建网络司令部,引起了全球网络军备竞赛的热潮。文章探讨网络军备竞赛的发展现状和特点,分析以法律形式进行控制的必要性,能够全面系统的了解网络军备竞赛所带来的严重危害,为控制军备竞赛的对策和决策提供一些建议。