基准光电高温计的光谱响应度测量

基准光电高温计的光谱响应度是复现ITS-90银点以上温标的重要参数,中国计量科学研究院新建了一套基于单色仪的光谱响应度测量装置.在这套装置上高温计的光谱响应度作为一个整体参数进行测量,系统能够自动完成单色仪的波长标定和高温计的响应度测量.初步完成了基准光电高温计的600～1 200 nm之间的光谱响应度测量,并计算了基准光电高温计的有效波长及其不确定度.     

荧光量子效率绝对法测量系统校准及不确定度评定

荧光量子效率是发射与吸收的光子数之比,是表征荧光材料发光性能的关键参数。然而,用于绝对法测量荧光量子效率的光路和探测器未经校准溯源或是校准方法不当,会造成测量光谱的不准确,进一步影响荧光量子效率计算结果的不准确。采用汞氩灯对单色仪进行校准,保证了激发波长和发射波长的准确性,利用标准辐射源对光路、发射单元单色仪和探测器进行光谱相对强度校准,保证了激发波段和发射波段光谱相对强度的准确性;最后从测量模型出发,对测量不确定度进行了分析,得到在300~360nm的激发光波段和370~900nm的发射光波段内相对合成标准不确定度为3.58%,相对扩展不确定度为7.16%,k=2。通过对单色仪波长校准以及对光谱相对强度进行校准,为荧光量子效率的准确测量提供了参考。     

用全滤色片法进行光探测器相对光谱响应的修正

色玻璃全滤色片法是进行光探测器相对光谱响应修正的常用方法。本文讨论该法所用的滤光器在平行光垂直照明和漫射光照明两种情形下的最优设计问题,给出滤光器在漫射光照明下探头相对光谱响应的计算模型。实验结果与理论计算符合得很好。     

单色仪的杂散光及其测量

本文探讨了可定量描述光谱仪器杂散光特性的谱杂散光系数和总杂散光系数的概念和数学表达式,提出一种测量单色仪标称波长上的光谱透射率(相对值)的方法,并以此对近红外单色仪的杂散光特性进行了测量,给出测量结果。作者认为,用这种方法测量和描述杂散光较为符合实际情况,能够比较准确地表示光谱仪器的杂散光特性。     

关于新的光电探测器光谱响应度工作标准的研究

本文介绍了新的光电探测器光谱响应度工作标准 ,该项标准参加了 2 0 0 0年CCPR(国际计量委员会所属光度和辐射咨询委员会 )组织的国际比对。在新的工作标准中 ,用调制光代替原来的直流光 ,以减少杂散光、噪声等对测量准确度的影响 ;用锥腔型热释电探测器代替原来的热电堆探测器作为参考探测器 ,用锁相测量仪器代替原来的直流测量仪器并增加温度控制 ,以便提高测量系统的灵敏度和光谱响应度标准的平坦程度 ,进而提高准确度 ;以双单色仪代替原来的单色仪 ,大大减少杂散光 ;同时增加了光谱响应度的绝对定标     

200～400nm波段光电探测器光谱响应度测量装置研究

本文叙述了200~400nm波段光电探测器光谱响应度的测量装置原理、测量系统及不确定度。采用紫外光谱强度大的氙灯作为光源,采用紫外分光效率高的单色仪进行分光,腔型热释电探测器与标准硅光电探测器进行相对光谱响应比较得到标准硅光电探测器相对光谱响应度。绝对值标定则是利用低温辐射计对无窗紫敏硅光电探测器进行测量后再传递到标准硅光电探测器,从而最终测量出标准硅光电探测器在紫外波段的绝对光谱响应度。     

通过光波转换材料提高太阳能电池性能的研究进展

限于太阳能电池本身的光谱响应特性,其只能利用入射光谱中的低频部分光子,造成了光能的损失,因而转化效率较低。为此在电池的上表面引入"转光层",其中包含的转光材料首先吸收电池光谱响应较差的短波长光子(一般300～500nm),再发射出光谱响应性好的波长较长的光子,提高电池的光谱响应性,进而提高太阳能电池的转化效率。近年来,随着转光材料的丰富和性能的提高,应用转光层来提高太阳能电池效率的研究取得了显著的成果,但是距离其工业化应用仍有很多难题亟待解决。     

傅里叶变换红外光谱仪光谱响应非线性试验研究

利用傅里叶变换红外光谱仪测量不同温度黑体的光谱辐射,采用最小二乘法进行数据拟合,获得了光谱仪光谱响应的线性特性。为了更好地描述仪器的线性特性,引入"光谱线性度"的概念,通过实验得到DTGS及MCT探测器对应的仪器的光谱线性度曲线图,直观反映出仪器光谱线性特性及影响因素,据此方法可以确定线性度满足使用要求的探测器、测量光谱范围、测量目标的能量范围,反映影响仪器线性度的内外因素,具有重要的实际意义。     

扫描仪理想的光谱响应特性研究

提出了扫描仪应该是一个颜色反应器的观点 ,并通过颜色反应器理论探讨了扫描仪理想的光谱响应条件 ,为扫描仪中照明光源的理想光谱分布 ;滤色片以及光电倍增管的最佳光谱响应提出了理论依据。     

扫描仪理想的光谱响应性研究

提出了扫描仪应该是一个颜色反应器的观点,并通过颜色反应器理论探讨了扫描仪理想的光谱响应条件,为扫描仪中照明光源的理想光谱分布,滤色片以及光电倍增管的最佳光谱响应提出了理论依据。     

Simple modifications for stabilization of the finite point method

A stabilized version of the finite point method (FPM) is presented. A source of instability due to the evaluation of the base function using a least square procedure is discussed. A suitable mapping is proposed and employed to eliminate the ill‐conditioning effect due to directional arrangement of the points. A step by step algorithm is given for finding the local rotated axes and the dimensions of the cloud using local average spacing and inertia moments of the points distribution. It is shown that the conventional version of FPM may lead to wrong results when the proposed mapping algorithm is not used. It is shown that another source for instability and non‐monotonic convergence rate in collocation methods lies in the treatment of Neumann boundary conditions. Unlike the conventional FPM, in this work the Neumann boundary conditions and the equilibrium equations appear simultaneously in a weight equation similar to that of weighted residual methods. The stabilization procedure may be considered as an interpretation of the finite calculus (FIC) method. The main difference between the two stabilization procedures lies in choosing the characteristic length in FIC and the weight of the boundary residual in the proposed method. The new approach also provides a unique definition for the sign of the stabilization terms. The reasons for using stabilization terms only at the boundaries is discussed and the two methods are compared. Several numerical examples are presented to demonstrate the performance and convergence of the proposed methods. Copyright © 2005 John Wiley & Sons, Ltd.     

基于磁性法的钢中残余奥氏体含量测定方法与装置

阐述了磁性法测定钢中残余奥氏体含量的原理和方法,并研制了一种基于磁性法的钢中残余奥氏体含量测定装置。该测定装置可以实现换向法、甩脱法和动态法等3种残余奥氏体含量测定方法,其中换向法和甩脱法以不同方式静态测定残余奥氏体含量,动态法能够在试件拉伸过程中连续、快速地动态测定残余奥氏体含量与应变的对应关系。该测定装置以LabVIEW为平台,构成了虚拟仪器系统,对数据进行采集、分析和处理,实现了可视化操作、自动测量、曲线显示和数据保存等功能。使用该装置采用3种方法分别对M50NiL轴承钢中的残余奥氏体含量进行了测定,试验结果表明该测定装置能够精确地测定钢中的残余奥氏体含量。     

A comparison of domain integral evaluation techniques for boundary element methods

In many cases, boundary integral equations contain a domain integral. This can be evaluated by discretization of the domain into domain elements. Historically, this was seen as going against the spirit of boundary element methods, and several methods were developed to avoid this discretization, notably dual and multiple reciprocity methods and particular solution methods. These involved the representation of the interior function with a set of basis functions, generally of the radial type. In this study, meshless methods (dual reciprocity and particular solution) are compared to the direct domain integration methods. The domain integrals are evaluated using traditional methods and also with multipole acceleration. It is found that the direct integration always results in better accuracy, as well as smaller computation times. In addition, the multipole method further improves on the computation times, in particular where multiple evaluations of the integral are required, as when iterative solvers are used. The additional error produced by the multipole acceleration is negligible. Copyright © 2001 John Wiley & Sons, Ltd.     

纳米氧化锌材料的制备方法及结构表征

文章介绍了纳米ZnO材料的常用制备方法，如应用较多的气-固-液法、气相法、水热法和有着较好应用前景的电化学法，以及各类纳米ZnO材料的结构表征，并展望了纳米ZnO材料的发展前景。     

YAG透明陶瓷纳米粉末的制备方法及其应用分析

钇铝石榴石(YAG)具有良好的力学性能和优异的光学特性,适宜用作激光基质材料或其他特种光学组件。而要制备透明、输出功率大的块体YAG,纯度高、粒度细而均匀的前驱体粉末是必要的。总结和综述了近年来YAG前驱体粉末的多种制备技术,如传统固相法和高能球磨法以及液相法中的溶胶-凝胶法、燃烧法、水热法和共沉淀法等,分析了这些方法的优缺点,指出了燃烧法相对较为简单,制备成本较低,可获得质量较高的前驱体粉末,是一种较有前景的制备方式。     

超疏水表面制备方法的比较

超疏水性是一种特殊的润湿性,它是指水滴与表面的静态接触角大于150°或者滑动角小于10°,其最初来源于“荷叶效应”。本文对近几年关于超疏水理论和自然界中超疏水现象研究进行介绍,并对超疏水表面的制备方法及其应用进行综述。分别总结了基于模板法、涂覆法、刻蚀法的超疏水表面制备方案的优缺点及其改进措施,重点阐述超疏水表面在金属表面抗腐蚀方面的应用。最后对具有特殊功能的超疏水表面的制备进行了介绍,如自愈性超疏水表面、润湿转变型超疏水表面。在制备方法中,模板法和涂覆法制备时间短、成本低,但稳定性和耐磨性较差;刻蚀法易于控制,但实用性受限。      

聚合物熔体界面张力测定方法的研究进展

在聚合物共混体系中,界面张力对聚合物相容性有着重要影响,决定着相与相之间的粘接性,成为控制其最终相态结构的一个重要因素,是研究多相聚合物相态结构的基础。文中综述了聚合物熔体界面张力的测定方法,这些测定方法主要有热力学方法、流变学方法以及动力学方法三大类;介绍了每种方法的基本原理,并对其优缺点及适用范围进行了简单说明。其中,动力学方法是使用最多、相对准确的,对该方法进行了重点介绍,并且讨论了动力学方法中熔体粘弹性对界面张力测定的影响。     

Combined hybrid approach to finite element schemes of high performance

Based on a combination of Hellinger–Reissner principle with its dual, a mixed/hybrid method of non‐saddle point type has been presented in the previous papers. In the paper, an application of the method to two‐dimensional elasticity problems is considered in a manner of combination of mathematical analysis with numerical investigation. How to construct a combined hybrid scheme of high performance is discussed, and several four‐node quadrilateral CH‐elements are systematically verified. In brief, this paper shows that for the hybrid element scheme, the energy compatibility condition, introduced in Zhou (Combined hybrid finite element method without requirement for Babuska‐Brezzi condition, to appear) is the ultimate key to the achievement of high performance. Copyright © 2001 John Wiley & Sons, Ltd.     

Recent developments of free mesh method

This paper presents the recent advances on Free Mesh Method by the authors. In this method, elements are locally created at each node in an autonomous manner, so that only nodal information is necessary without global meshing. The method has been tested with various applications such as heat conduction, fluid and fracture analyses, and reliable solutions were obtained with good parallel efficiency. Modifications of Free Mesh Method have been further proposed, and the accuracy of solution has been improved.The overall review of the recent advances has demonstrated the effectiveness of Free Mesh Method. Copyright © 2000 John Wiley & Sons, Ltd.