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.     

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。     

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。     

固相微萃取和气相色谱-质谱法测定北京酱牛肉中的挥发性成分

采用顶空固相微萃取和气相色谱-质谱法（Head Space Solid Phase Microextraction Gas Chromatgraphy-Mass Spectrometry,HSSPME—GC—MS）对北京传统酱牛肉中的挥发性香气物质进行了测定,总共检测出68种风味化合物,其中包括醛类49.12%、酮类0.84%、醇类4.85%、烃类13.29%、酯类2.61%、酚醚类11.33%和含硫含氮及杂环化合物6.55%,另外还有11.41%的其它类物质,其中醛、酮和含硫含氮及杂环化合物中含有北京传统酱牛肉的主要香味成分。     

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.     

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     

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。     

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.     

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。     

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。     

第四十六讲工业物联网技术及标准体系

针对当前工业物联网系统中存在的异构性和互操作性问题,本文介绍了一种工业物联网技术及标准体系,该标准体系中包括了工业物联网身份标识、工业物联网应用属性协议、工业物联网服务协议以及工业物联网互操作协议四项标准。该系列标准的制定将有利于提高工业物联网的运行效率和互操作性,为工业物联网发展提供支持。     

Thermoelastic stability of duplex heat exchanger tubes

When duplex tubes are used for heat exchange purposes, thermal distortion affects the contact pressure and, hence, the thermal contact resistance at the interface. The resulting coupling between the thermal and thermoelastic fields for the system can lead to instability and non-uniqueness of the steady-state solution and, hence, to erratic heat transfer performance.Stability of the system is investigated by determining the conditions under which a small (axisymmetric or non-axisymmetric) perturbation on the steady state can grow exponentially in time. Substitution into the governing heat conduction and thermoelastic equations enables the unknown functions to be determined except for a set of arbitrary constants, which are then determined from the thermal and mechanical boundary conditions, including a statement of the relation between thermal contact resistance and pressure, linearized for small perturbations about the steady state.Results are presented for a range of material combinations and for both directions of steady state heat flux. It is shown that unstable axisymmetric perturbations can only occur for inward heat flow and, hence, the stability boundary for outward heat flow is always associated with a non-axisymmetric mode. In the latter case, the circumferential wavelength of the critical mode is generally about twice the tube thickness and a good approximation to the stability boundary can be obtained using previously published results for the stability of two plane layers in thermoelastic contact.For inward heat flow, the critical heat flux for axisymmetric perturbations is independent of the mean contact resistance, whereas that for non-axisymmetric modes increases with contact resistance. Thus, the stability boundary in this case is determined by non-axisymmetric modes for small values of contact resistance and by axisymmetric modes for large contact resistance.     

制药企业设备管理对策探讨

设备是企业在生产过程中使用最为重要的生产工具,设备不仅让企业的技术和生产质量得到了保证,也标志着企业经济现代化发展的进程,因此设备在企业生产中尤为重要。尤其是制药企业,设备管理的好坏可以说是关系着制药企业的经济命脉,生死存亡。但是,现在大多数的制药企业在设备的管理上并没有引起足够的重视,现状存在着很多的问题,在对制药企业的设备管理进行多年研究的基础上,就设备管理上存在的重点问题进行了分析,并提出了几点建议一起探讨。     

螺旋锥齿轮珩磨轮的制造方法

对用于螺旋锥齿轮珩磨加工的珩磨轮模具制造的关键技术进行深入研究。介绍珩磨轮齿面准均布网格点的计算方法,通过计算这些准均布网格点及其径矢和法矢,建立齿面上每一个网格点的拨模极限导程的数学模型。通过计算齿面上这些网格点的可行的螺旋线导程,判断其交集是否为空集,并以此作为判断是否出现拨模干涉的依据。针对已经出现的拨模干涉,提出拨模导程的优化方法以及干涉的修正方案和齿面光顺过程。详细讨论金属模具的逐点成形和展成加工方法以及它们各自的适用范围和可加工性,并以刀倾法为例,阐述加工螺旋锥齿轮珩磨轮的金属凸模的计算步骤,为螺旋锥齿轮珩磨轮的制造提供理论依据。     

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。     

影响凸轮检测精度的问题与对策

针对目前国内在发动机凸轮检测中 ,选择检测基准、确定检测位置、测头切换、最小判别等方面存在的带有普遍性的影响凸轮检测准确性的问题进行了分析 ,并参照 GB/T1 1 82 -1 996和 GB/T1 6671 - 1 996,以“最小条件”为依据 ,从发动机凸轮升程和转角是非线性函数关系入手 ,对选择凸轮检测基准原则、确定凸轮检测位置 (求解检测起始转角 )方法、凸轮升程检测数据的处理、凸轮升程合格性的判定等进行了论述     

复杂变型产品参数传递结构研究

针对基于3维模型的复杂产品变型,提出了与产品建模结构相融合的树形参数传递结构。该结构规定参数只允许纵向传递,避免了参数之间的交叉传递,为复杂产品变型设计提供了有效的变型信息传递通道,并在此基础上实现了参数传递结构的模块化。以Solid Edge 3维造型软件为设计环境,以VB为工具开发了剑杆织机变型设计系统,阐述了剑杆织机建模、参数传递和产品变型设计的关键技术及其实现方法。     

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.     

ORACLE采购库存模块中的常用表及其关系

简单阐述了ORACLEERP套件的采购作业流程,针对ORACLE数据库,分析了采购、库存2个模块中数据查询与统计中最常用的数据表及其关系,着重列举了采购申请、订单、出入库、物料事务处理等相关表的主要字段及关联,为数据库的二次开发与系统定制奠定了基础。     

A Comparative Study on the Three-Dimensional Surface Topography for the Polished Surface of Femoral Head

Several surface topographic techniques have been widely used in many manufacturing engineering fields for studying the surface characteristics for the practical application of manufacturing surfaces. In this paper, a polished surface of a femoral head is considered for the compatative study, where the stylusbased technique, the autofocused optical measurement technique, the interferometric technique, and scanning probe microscopy are applied. After the operational principles are introduced, some practical comparative measurements are reported for the polished surface. Some useful comparisons and conclusions are drawn from the comparative study. General guidelines for the 3D surface topography are also given for practical application.