基于VRML-JAVA的通用虚拟装配场景交互操作的研究与实现

通过对不同CAD软件输出的VRML文件进行分析,提出了利用树形结构组织场景,将不同CAD软件输出的VRML文件进行标准化的基本方法。利用JAVA语言强大的编程功能和VRML2.0提供的EAI(ExternalAuthoringInterface,外部程序扩展接口)针对标准文件编写交互操作的程序,从而实现了对不同CAD软件建模的VRML装配场景的拆装、任意部分的隐藏和透明度调节等交互操作控制。     

基于VRML场景的虚拟装配环境设计

Java 和VRML 的结合,构成了创建基于网络的大规模虚拟环境的理想综合平台,特别适合分布式VRML 场景的虚拟装配环境设计。给出了一种基于VRML 和Java的虚拟现实构建方法,即通过I-DEAS 完成虚拟产品的物理建模和装配设计,修改由I-DEAS的输出的VRML 文件,增加交互性所必需的传感器节点,然后利用VRML 的Script 和EAI将它们有机地集成在一起,在此技术上完成VRML 场景的动态生成、装配控制及装配过程的动画回放等功能。     

基于Unity 3D与自然手势交互的车辆虚拟拆装实验系统

传统的车辆虚拟拆装仿真技术,存在实操感差、交互灵活性低的问题。鉴于此,本文提出了基于自然手势交互的汽车虚拟拆装实验系统和方法框架。通过Leap Motion手势识别,构建了车辆拆装虚拟仿真实验平台,提供了发动机拆装、整车拆装、传动系统拆装、制动系统拆装和转向系统拆装模块,实现了拆装过程的仿真和评价。与传统的车辆虚拟拆装方法相比,基于自然手势交互的虚拟拆装方法具有交互性和沉浸性更强的优点,能够最大程度地模拟现场车辆拆装过程,避免实践场地、时间不足的问题。     

VRML虚拟校园漫游与交互技术

鉴于虚拟校园在高校数字化和信息化建设中的重要意义,以石家庄铁道学院为例,探讨VRML构建虚拟场景的漫游与交互技术。以VRML、3DMax等为场景构建工具、以JavaScript为VRML内部脚本和外部脚本接口编程工具,通过VRML与HTML的整合集成,实现了虚拟校园漫游与交互系统,具有导航漫游、对虚拟场景进行交互操作和设置、信息查询等功能。直观地展示了校园景观及设施,方便了用户对校园信息的查询,取得了良好的效果。     

第二代Web语言(VRML)的发展及其应用

本文简要阐述了第二代Web语言 (VRML)的发展及其特点 ,同时论述了VRML如何通过Script节点或EAI接口与Java语言有机结合来编程以及VRML编程环境和运行平台 ,最后介绍了VRML的应用及发展前景。     

基于网络的虚拟三维环境中人机交互实现途径

VRML（虚拟现实建模语言）是网络三维技术中的代表，本文以VRML为例分析了网络虚拟三维环境中人机交互的实现模式。详细分析了具体节点接受鼠桔操作事件以实现交互的方式，并且介绍了通过Script节点和外部编程接口扩展交互功能的途径。     

VRML虚拟现实网络互动仿真装配平台的研究

在计算机上实现了虚拟装配的流程以及运用VRML创建可视化的三维虚拟场景,提出了一种基于VRML和Java的虚拟现实构建方法,以增强VRML虚拟场景与外界的交互性,并通过实例提出了创建网络虚拟装配交互仿真的具体方案。该方法不仅可用于演示网络环境下的可视化装配,也适用于基于VRML的其它领域科学可视化。     

协同环境中3D替身交互行为动态控制的实现

协同环境中用户之间的协同感知程度和实时交互性直接影响到协同工作的质量。目前,部分CSCW 应用系统通过向虚拟协同环境CVEs 中添加3D 替身来提高用户之间的协同感和交互感。但经研究发现,其场景中所有的替身只是在用户的控制下机械地使用VRML 中提供的行为机制进行运动,替身之间也不存在交互行为,用户交互程度仍然不足。为了进一步解决这个问题,笔者着重研究了CVEs 中3D 替身之间交互行为的实现,通过替身行为机制的建立,利用VRML 和Java 实现了替身之间交互行为的动态控制,从而增强了用户的协同感和交互感,提高了协同工作的效率。     

采用VRML的齿轮变速箱虚拟模型的实现

分析了当今虚拟现实技术对开发机械产品的影响,提出了利用VRML构建齿轮变速箱虚拟模型的基本方法.利用CAD三维建模软件建立零件模型,根据变速箱的结构特征和工作原理在VRML中编程实现虚拟装配及运动仿真和控制.实现了虚拟模型在网络上的交互式展示,为机械产品的异地设计及结果评估提供了有效方法.     

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.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

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。     

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.     

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.     

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.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.