Photopyroelectric technique for the measurement of thermal and optical properties of pigments in liquid solution

The analytical solution for the one-dimensional heat diffusion problem for a two-layer system, in the Beer-Lambert model for light absorption, is shown to be useful for the implementation of a novel photopyroelectric (PPE) methodology, for the measurement of thermal and optical properties for pigments in liquid solution. The PPE signal, as a function of the sample's thickness, is used for this goal. Exponential decay for the PPE amplitude, followed by a constant PPE phase, for solutions at low dye concentration and an exponential decay for the PPE amplitude but a linear PPE phase behavior for the higher concentrated ones are shown and are, respectively, used for the measurement of the optical absorption coefficient and thermal diffusivity for liquid samples. These PPE phase behaviors also provide a criterion to decide on the corresponding limit for optical and thermal properties measurement. This PPE methodology was tested by measuring the optical absorption coefficient (at 658 nm) and thermal diffusivity for solution of methylene blue and copper sulfate in distilled water at various concentrations. Independent measurements of optical properties, using a commercial spectrometer, were done to compare with the corresponding ones obtained with this PPE methodology, finding very good agreement to each other.     

A procedure for making phosphor viewing screens for the transmission electron microscope

A technique is described for preparing uniform, durable phosphor layers for viewing screens suitable for the transmission electron microscope; a settling procedure is used. The example described here is for a high-voltage instrument, but with adjustment of the coating density, the technique should be equally suitable for screen preparation for transmission electron microscopes that operate at lower acceleration voltages.     

A Surface Area Calculation and CAPP System for Non-Axisymmetric Deep Drawing Products

In this paper a surface area calculation for non-axisymmetric deep drawing products of elliptical shape was constructed for the design of blank shapes of deep drawing products by using an AutoLISP function in AutoCAD software. A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. In this study, a CAPP system for non-axisymmetric deep drawing products of elliptical shape was constructed using process sequence design. The system developed consists of four modules. The first is the recognition of shape module for recognising non-axisymmetric products. The second is a 3D modelling module for calculating the surface area for non-axisymmetric products. The third is a blank design module for creating an oval-shaped blank with an identical surface area. The fourth is a process planning module based on production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. The drawing coefficient, the punch and die radii for elliptical shape products are considered as the main design parameters. The suitability of this system was verified by applying it to a real deep drawing product. This surface area calculation and CAPP system should be very useful for reducing the lead-time for manufacturing and for improving the accuracy of products.     

Finite element analysis of rotorsAhaлмв кoлebhий potopob metoдoм кoнeыш элeмeнтoв

A finite element formulation for the natural vibration analysis of tapered and pretwisted rotors has been presented. Numerical results for natural frequencies for various values of the geometric parameters and rotational speeds, have been computed for the case of rotors with and without pretwist. A Galerkin solution for the fundamental has also been worked out and has been used to provide a comparison for the finite element results. Charts for rapid estimation of the fundamental frequency parameter of tapered rotors, have been included.     

机器人多手指抓取和适应性夹具夹持的封闭性和可达性

本文讨论了机器人多手指抓取和适应性夹具设计的共同特点和理论基础。提出了刚体点接触下的约束锥和自由锥的概念,研究了两者的对偶性;推导了定位确定性条件,抓取封闭性条件,可达性和可分离性条件;严格定义了刚体点接触的约束度和自由度;建立了刚体在点接触约束下瞬时运动分析的几何理论,给出了封闭性和可达性的代数判别准则和计算机自动判别方法。为机器人抓取规划,适应性夹具设计提供了理论依据和实现方法。     

亚临界和超临界汽轮机强度振动与寿命设计判据的研究

根据多年的科研成果提出了亚临界和超临界汽轮机部件的强度、振动与寿命的20个设计判据。给出了汽轮机的部件静强度、结构有限元分析、隔板刚度、低压缸刚度、汽轮机胀差、叶片动强度、整体围带叶片动强度、长叶片颤振、第一种调频叶片振动、第二种调频叶片振动、整圈连接叶片组振动、轴系临界转速、轴系油膜涡动的稳定性、不平衡响应、轴系扭振频率、轴系扭振应力、汽流激振、低周疲劳寿命、蠕变寿命和蠕变与低周疲劳交互作用下寿命等20个设计判据和这些设计判据的应用范围。使用这些设计判据,可以在设计阶段校核和分析汽轮机部件的强度、振动和寿命设计的安全性与可靠性,为大型汽轮机的研制和生产提供了科学的依据。     

基于MATLAB的起重机四连杆结构瞬时角度计算

四连杆结构设计是门座起重机设计工作的主要内容。本文通过推导门座起重机的四连杆结构的几何关系建立了非线性方程组,并基于MATLAB完成求解,得到四连杆结构中的象鼻梁、臂架和大拉杆构件与水平面的瞬时夹角,为建立四连杆结构的空间杆系模型提供初始数据;同时,按照四连杆结构的变幅位置对应计算结果完成了图形显示,方便设计人员进行数据分析。     

基于Web的机械设计答疑系统的研究与开发

利用JavaScript和VBScript编写ASP程序 ,利用SQL和ODBC技术建立网络数据库 ,利用流媒体技术实现动画和视频的网上快速播放 ,利用虚拟现实技术实现三维图形的交互式实时浏览 ,开发了一套基于Web的机械设计答疑系统。该系统适用于绝大部分机械设计人员 ,尤其适用于广大初学者。     

基于MIC理论构建嵌入式装备控制领域建模语言的研究

现有的嵌入式系统开发成本高，采用通用的开发环境，应用领域的工程人员难以开发。由此，研究嵌入式系统面向装备控制的领域扩展技术。基于模型集成计算理论搭建嵌入式装备控制系统的元模型，解释成面向领域的图形化建模语言，使装备控制领域的工程人员能够对不同的嵌入式装备控制系统快速搭建模型。通过建立模型解释器，实现从应用系统模型到代码的映射。通过面向该领域软件构架的研究，探索面向系统的嵌入式组件设计方法。     

普通有控点接触共轭制齿形（简称PK制齿形）

本文对PK制齿形作了扼要介绍,并阐述了PK制齿形的基准曲面的设计要点和替代曲面的共轭曲率值的修正量的确定原则。文中叙述了PK制齿形的各种切制方式以及PK制齿形计算卡的组成。文中还介绍了编写PK制齿形计算程序的源程序中所使用的标准过程的代码的含意,并列出了各种类型PK制齿形的计算程序的编组表。     

多接收双聚焦等离子体质谱法测定高精度同位素比

采用 VG Axiom型多接收双聚焦等离子质谱仪 ( MC-ICPMS)测定 Nd、Pb、U同位素比值 ,应用指数公式对测定的结果进行质量歧视校正。结果表明 :测定参考物质 Ames Nd获得的钕同位素比值为 14 3 Nd/14 4 Nd=0 .5 1 2 1 44± 0 .0 0 0 0 1 5 (确认值为 0 .5 1 2 1 3 5 )、14 5Nd/14 4 Nd=0 .3 4841 7± 0 .0 0 0 0 1 9(确认值为 0 .3 4841 8) ;测定参考物质 NIST SRM981获得的铅同位素比值为 2 0 8Pb/2 0 4Pb=3 6.71 1 4± 0 .0 0 81、2 0 7Pb/2 0 4Pb=1 5 .4886± 0 .0 0 3 8、2 0 7Pb/2 0 6Pb=0 .91 44 5 6± 0 .0 0 0 0 3 9、2 0 6Pb/2 0 4Pb=1 6.93 82± 0 .0 0 3 1、2 0 8Pb/2 0 6Pb=2 .1 660 1± 0 .0 0 0 1 6;测定参考物质 NIST SRM 0 1 0获得的铀同位素比值为 2 3 4 U/2 3 8U =0 .0 0 0 0 5 46±0 .0 0 0 0 0 0 3 (确认值为 0 .0 0 0 0 5 46)     

面向绿色制造的产品模块化设计研究综述

阐述了绿色产品生命周期的涵义,分析了绿色产品生命周期各阶段的特性及关联关系,对目前存在的绿色模块化设计技术和方法进行了分类总结。根据绿色产品生命周期各阶段研究侧重点不同,将目前绿色制造模块化设计归纳为面向产品生命周期模块化设计、绿色设计模块化设计、环境意识模块化设计、再制造模块化设计、可拆卸模块化设计、维修模块化设计、回收模块化设计、重用模块化设计及其他模块化设计,并对其相应的模块化设计方法进行了综述分析。最后展望了今后的研究趋势。     

新型安全离合器

介绍了一种结构简单、工艺性好，造价、运行费用低廉，寿命长，可在运动中迅速接合分离，可补偿两轴之间的任何偏移，能过载安全保护的新型安全离合器的结构设计。     

采用ADAMS的轮式小型甘蔗收割机转向和越障性能仿真研究

借助ADAMS-View软件建立一个轮式小型甘蔗收割机的样机模型,并对样机模型行走转向和越障性能进行仿真,得到样机行走转向和越障性能的仿真曲线,为轮式小型甘蔗收割机行走机构的研制提供一些依据.     

石墨消解连续光源原子吸收法测定废气中重金属

采用DEENA石墨消解仪对采集的废气样品进行前处理,利用contrAA700连续光源原子吸收光谱仪测定样品中重金属铜、锌、镍、铅、镉、锰。本试验优化了消解液的组合,使样品消解更完全,且克服了传统火焰原子吸收法需要更换空心阴极灯的缺陷,提高了分析速度。各元素的检出限分别为铜0.0025mg/m~3,锌0.0012mg/m~3,镍0.0038mg/m~3,锰0.0025mg/m~3,铅0.0075mg/m~3,镉0.0025mg/m~3。各元素的回收率分别为铜94.2%,锌102.5%,镍95.6%,锰104.1%,铅97.3%,镉95.3%。本方法具有较高的准确度,相比传统的火焰原子吸收法有更高的工作效率,适用于废气中多种重金属的同时测定。     

高压容器气密性检测的闭水渗透量与闭气降压量换算关系的研究

为将高压容器密闭性的闭水检测改为闭气检测，根据高压容器密闭性能的要求，通过对流体力学小孔口自由出流分析，建立了闭水试验定量数学模型。根据对高压气体绝热流动规律的分析，建立了闭气试验定量数学模型。为将闭水试验改成闭气试验，通过对比闭水试验与闭气试验定量数学模型，推导出了两者流量之间的换算关系，为在实际生产中运用闭气试验提供了坚实的理论基础。     

Flexible tools for specifying design variation

This paper describes flexible tools for specifying design variations that are based on non-uniform profile tolerance definitions. These tools specify bounds of design performance that can be used for negotiation among engineers in a collaborative design process. These specification methods allow for the capture of many different design functions that are not easily described with current tool designs. In addition, these specification methods lend themselves to efficient verification methods. Profile tolerance definitions provide the most general variation controls for complex mechanical surfaces. Common design practices and engineering standards for profile tolerances exhibit many weaknesses and limitations. We present a rationale for a complete specification approach using B-splines [1, 2] for profile tolerances, and illustrate the approach with examples. B-splines can be used to specify both uniform and non-uniform profile tolerance boundaries. Subsequently, algorithms for the evaluation of actual feature deviations and reporting methodologies for such tolerance zones are presented.     

产品设计重用技术支持体系研究

详细讨论了支持产品设计重用的技术体系。首先从产品设计重用的过程框架 (资源创建、资源管理和资源集成 )分析提出产品设计重用的技术需求 ,然后对现有技术如计算机辅助设计 (CAD) ,产品数据管理 (PDM) ,人工智能 (AI) ,知识管理 (KM) ,Web技术等对产品设计重用的支持性和相关性进行了详细深入的分析讨论 ,最后提出了基于设计制品理论的产品设计重用的完整技术体系及需要解决的关键技术     

Approximate Formula for the Contact between Truncated Surfaces and Frictional Characteristics of a Journal Bearing in Mixed Lubrication

This paper presents an approximate formula for the contact of a non‐Gaussian distribution of truncated surfaces, which is useful for mixed lubrication theory, and gives a method for the determination of the truncation parameters in this formula from a measured roughness profile. Using this approximate formula for a contact, the approximate formula for the friction coefficient of a journal bearing in mixed lubrication, which was previously proposed by the authors, is modified for truncated surfaces, and the frictional characteristics are demonstrated for various parameters of truncated roughness using the modified formula.     

基于ANSYS的轴流风机叶片模态分析

针对轴流风机运行中,常常碰到由于叶片的共振而产生的破坏性事故。本文通过建立叶片有限元模型进行模态分析得到叶片的各阶固有频率及相应振型,同时计算了考虑离心力影响下叶片动频率及相应振型。分析了可能产生共振的频率,为轴流风机的结构改进、结构优化以及动力修改提供理论依据。