埋地管道泄漏内封堵装置设计与研究

针对流体输送埋地管道泄漏问题,设计了一种利用管道机器人携带封堵气囊进行快速应急封堵修复的埋地管道泄漏内封堵装置。采用矩阵变换方法建立了牵引系统驱动轮过弯方程,利用MATLAB软件对过弯方程进行了验证,同时利用ADAMS软件仿真分析过弯路径与驱动轮转角对牵引系统行走速度的影响。研究结果表明:由两个串联封堵器组成的应急封堵系统可满足复杂工况下的管道泄漏封堵要求;牵引系统驱动轮在弯管内部行走时,单轮速度呈周期性变化,但三个驱动轮整体周期运动特性一致;驱动轮转角在25°~40°时,牵引系统行走速度与驱动轮转角成正比,且转角为30°时驱动效果最好。该内封堵装置的结构设计可为管道泄漏应急封堵领域装备的研发提供重要参考。     

电路电磁兼容建模与仿真

提出了对暴露在任意外场中的传输线进行时频分析的新方法，这种方法非常稳定，它能够与任意的传输线模型和电路仿真方法兼容，并且使用这种方法得到的仿真值和实际值之间的差别小于1％。     

随机库存分配问题的一种求解方法

讨论了在VMI管理思想下对具有随机需求特性的多客户库存分配问题 ,重点论述了有效近似算法的设计过程 ,最后基于一组模拟数据给出了一个算例。     

Ad Hoc与无线网络的扩展性研究

Ad Hoc作为无线网络的具有高抗毁性和灵活性的扩展网络,日益引人关注。本文首先从环绕网的理念入手,介绍Ad Hoc作为现有无线网络扩展的意义和优势,然后重点分析并提出融合策略以及需要思考的问题。     

利用AutoCAD编制电气CAD

介绍如何利用AutoCAD开发适合电气专业使用的CAD系统，通过编制电气CAD的功能菜单，构造电气元件库，增强CAD的专业性能。编制电气CAD可以有效地统一本单位电气制图标准，方便电气工程师使用CAD进行专业设计。     

通用串行总线(USB)接口芯片USBN9602的应用

简要介绍了通用串行总线USB的特点,对USB接口芯片USBN9602的内部结构、引脚、寄存器组作了详细的论述,并介绍了其应用。     

A New Measure of Misfit for Covariance Structure Models

Various fit indices exist in structural equation models. Most of these indices are related to the noncentrality parameter (NCP) of the chi-square distribution that the involved test statistic is implicitly assumed to follow. Existing literature suggests that few statistics can be well approximated by chi-square distributions. The meaning of the NCP is not clear when the behavior of the statistic cannot be described by a chi-square distribution. In this paper we define a new measure of model misfit (MMM) as the difference between the expected values of a statistic under the alternative and null hypotheses. This definition does not need to assume that the population covariance matrix is in the vicinity of the proposed model, nor does it need for the test statistic to follow any distribution of a known form. The MMM does not necessarily equal the discrepancy between the model and the population covariance matrix as has been assumed in existing literature. Bootstrap approaches to estimating the MMM and a related quantity are developed. An algorithm for obtaining bootstrap confidence intervals of the MMM is constructed. Examples with practical data sets contrast several measures of model misfit. The quantile-quantile plot is used to illustrate the unrealistic nature of chi-square distribution assumptions under either the null or an alternative hypothesis in practice.

     

绚丽多彩的楚汉丝织品（之二）──色彩与纹饰

湖南出土的楚汉丝织品，以马王堆一、三号汉墓所出为代表，其色彩反映了我国当时印染工艺技术所达到的高度水平，其纹饰则显示了鲜明的时代特征，表现了运动、气势和古拙的艺术风格，充满着神奇浪漫的色彩。     

广钢转炉分厂2号方坯连铸机拉速问题的探讨

通过分析钢水在结晶器内凝固的不均匀性及对钢水结晶的热量平衡计算，讨论连铸中间包钢水温度、结晶器冷却水流量及进出水温差对拉坯速度的影响。