应用扩展实体数据的零件号标注方法的研究与实现

通过扩展实体数据的创建、标记和解释实现了零件号的自动生成,以及通过扩展实体数据对零件标号的查询和排序等技术,实现了零件号的修改、零件号的删除、零件号的插入等功能,并给出了算法。所开发的系统可满足装配图中零件号标注的各种需要,有效地提高了工作效率,在工程绘图中具有较大的实用价值。     

工程图学装配图读图的CAI课堂教学

装配体装拆过程的三维动态模拟，装配体装拆过程的二维视图动态模拟，由装配图拆画零件图的二维过程演示，这三者构成了工程图学中有关装配图读图部分完整的课堂教学模式。笔者结合工程图学独特的教学特点，论述了上述课堂教学模式中3个组成部分之间的内在联系和不可分割性。并以作者所在课题组的CAI课件研制成果为例，介绍了该课堂教学模式在课件中装配图读图部分的总体设计、实现方法与过程。     

装配图中零件间遮挡的自动处理

本文提出了一种处理装配图中各零件间遮档的方法,该方法根据装配进程,在自动获取各零件外形信息的前提下,可灵活、方便地生成满足要求的装配图。     

用AutoCAD自动拆图方法的探讨

以实例说明如何创建适合用AutoCAD2000自动生成零件视图的装配图绘图环境以及绘制该装配图的具体方法和步骤。指出了自动生成零件视图的实现过程和操作技巧;对用一般方法绘制的机械装配图提出了分层处理的解决方案,并提供了用AutoCAD2000目标选择集等相关命令快速处理的方法;最后总结说明了该方法在拆画零件图和零件结构设计过程中的诸多优点。     

融合模式下装配图教学过程与绘图方法的改革

联系目标教学改革的实际,多角度全方位地论述了运用ＣＡＩ技术对装配图教学过程进行改革与优化的必要性与具体的做法。深入结合计算机绘图的特点,论述了对装配图教学中的拼图和拆图方法进行的有关改革及创新,提出了一种有利于提高装配图教学效率与质量的新的教学方法和思路。     

板式阀-插装阀混合的复杂集成块元件布局设计

液压集成块外部元件布局设计与内部油路连通设计的强耦合效应是妨碍其实现自动设计的核心问题.系统归纳总结了2类元件布局经验知识,即隐含于各类标准、技术规范与大量工程实例中文档化设计知识,以及专家在长期工程实践中积累的经验知识.在此基础上提出了一种基于知识和规则推理的板式阀-插装阀混用的液压集成块元件布局设计方法.由于布局经验知识与规则综合考虑了后续油路路径规划,元件的安装、调试与维护等方面的需求,因此极大降低了集成块设计的复杂程度.该方法与虚拟设计技术或智能优化算法相结合,为液压集成块的智能优化设计提供了一条有效途径.     

冲模CAD系统中装配图消隐算法

介绍了几种实现模具装配图消隐的方法,分析了各种方法的缺陷.根据模具装配图中各零件之间的相互关系,对模具零件进行了分类,并提出了一种新的实现模具装配图消隐的方法--图形实体重构法.     

AutoCAD绘制机械装配图技巧研究

绘制装配图是机械设计的重要内容之一。利用AutoCAD绘制装配图,可以采用直接绘制法或拼图画法。本文主要研究拼图画法中的图块插入法和"垂直平铺法"在绘制机械装配图中技巧问题。     

基于Pro/E的二维标注标准化和快捷化实现方法

针对Pro/E二维标注系统存在的不符合国标及效率低下等问题,提出了基于Pro/E二维标注系统的实现方案,并通过采用标准符号库、智能化尺寸标注、公差(配合)自动化查询以及简化人机交互等方法,实现了二维标注的标准化和便捷化.在基于Pro/E二次开发软件敏捷标注系统SmartDrawing上,对这些方法进行了验证.实例表明,采用SmartDrawing系统的二维标注,在标准化和快捷化等方面都有显著提升.     

三维标注技术发展概况

回顾了从二维手工绘图、CAD三维建模直到三维标注的发展历程,指出了三维标注技术的意义：摆脱二维束缚实现设计制造过程的三维化,以及实现基于主模型的设计制造一体化。探究了三维标注技术的实现原理。分析了标注技术推行过程可能遇到的障碍并提出了解决思路。三维标注技术引领了产品设计制造一体化的趋势,展现出良好的应用前景。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。