半导体激光器的光学准直

对半导体激光器进行光学准直是空间光通信系统必须进行的重要工作。文中简述了准直通常使用的方法,测试了使用单透镜对一种３５ｍＷ半导体激光器的准直结果,准直效率约为６０％,准直后的发射角为０４～０７５ｍｒａｄ。     

中国服务业显性比较优势测算——基于前向联系增加值出口

基于"前向联系增加值出口"方法,测算了1995-2011年中国服务业细分产业层面及按要素密集度特征分类层面的显性比较优势指数(RCA_F),并同基于"总出口"1的比较优势指数(RCA)进行了比较。研究发现,中国在全球价值链分工中,比较优势集中在资本密集型服务业领域,且实现了比较劣势向比较优势的转变;劳动、知识密集型服务业及健康教育公共服务均尚未取得比较优势,但是有迹象表明三个领域的比较劣势有改善的趋势。与基于前向联系增加值出口核算结果相比,基于总出口核算结果"高估"了劳动密集型产业的比较优势,其中对建筑业和零售贸易两个部门的估计偏差最大;同时,在资本、知识密集型两个领域存在不同程度的"低估"现象。     

A simple algorithm for calculating values for folded normal distribution

Folded normal distribution originates from the modulus of normal distribution. In the present article, we have formulated the cumulative distribution function (cdf) of a folded normal distribution in terms of standard normal cdf and the parameters of the mother normal distribution. Although cdf values of folded normal distribution were earlier tabulated in the literature, we have shown that those values are valid for very particular situations. We have also provided a simple approach to obtain values of the parameters of the mother normal distribution from those of the folded normal distribution. These results find ample application in practice, for example, in obtaining the so-called upper and lower α-points of folded normal distribution, which, in turn, is useful in testing of the hypothesis relating to folded normal distribution and in designing process capability control chart of some process capability indices. A thorough study has been made to compare the performance of the newly developed theory to the existing ones. Some simulated as well as real-life examples have been discussed to supplement the theory developed in this article. Codes (generated by R software) for the theory developed in this article are also presented for the ease of application.     

Testing for Serial Independence: Beyond the Portmanteau Approach

Portmanteau tests are typically used to test serial independence even if, by construction, they are generally powerful only in presence of pairwise dependence between lagged variables. In this article, we present a simple statistic defining a new serial independence test, which is able to detect more general forms of dependence. In particular, differently from the Portmanteau tests, the resulting test is powerful also under a dependent process characterized by pairwise independence. A diagram, based on p-values from the proposed test, is introduced to investigate serial dependence. Finally, the effectiveness of the proposal is evaluated in a simulation study and with an application on financial data. Both show that the new test, used in synergy with the existing ones, helps in the identification of the true data-generating process. Supplementary materials for this article are available online.     

Phase-II monitoring and diagnosing of multivariate categorical processes using generalized linear test-based control charts

In this paper, two control charts based on the generalized linear test (GLT) and contingency table are proposed for Phase-II monitoring of multivariate categorical processes. The performances of the proposed methods are compared with the exponentially weighted moving average-generalized likelihood ratio test (EWMA-GLRT) control chart proposed in the literature. The results show the better performance of the proposed control charts under moderate and large shifts. Moreover, a new scheme is proposed to identify the parameter responsible for an out-of-control signal. The performance of the proposed diagnosing procedure is evaluated through some simulation experiments.     

Collapsibility of Conditional Graphical Models

Abstract. In this paper, we consider two kinds of collapsibility, that is, the model‐collapsibility and the estimate‐collapsibility, of conditional graphical models for multidimensional contingency tables. We show that these two definitions are equivalent, and propose a sufficient and necessary condition for them in terms of the interaction graph, which allows the collapsibility to be characterized and judged intuitively and conveniently.     

电子声学显微镜中的斩束研究

根据扫描电子声学显微镜的要求,利用物镜光阑在第一透镜的上方形成的虚像作为斩束孔,分析了由三个透镜组成的电镜中电子束的斩束系统,给出了斩束光路设计和测试结果。     

科技期刊表格常见编排问题及规范加工

针对科技期刊表格编排中常见的问题,以国家有关科技期刊编排标准为依据,对其进行了规范性及科学性分析,给出了解决表格编排中存在问题的正确做法;指出了科技期刊表格编排必须科学、规范、简洁、自明.     

量子阱光电子开关器件(一)

量子阱半导体结构可使诸如光调制器和开关等光电子器件做得更小、更快、效率更高。它所具有的逻辑特性使其在并行高速互连的电子集成电路的集成度上具有良好的潜力。光电子器件能采用波导,也能采用二维并行阵列制作。其集成规模可达2048个单元,可工作的光逻辑和存贮器件的阵列得以实现及运行,所有单元都可由自由空间光(free-space optics)进行外部并行访问。本文概述了量子阱器件的运行机理及其发展前景。     

含氟聚酰亚胺高分子光波导工艺研究

对光通信用含氟聚酰亚胺高分子聚合物材料的特性进行了讨论，报告了材料制备、膜厚控制、折射率控制以及光波导制备技术等方面的实验结果．实测了含氟聚酰亚胺薄膜的温度特性和色散特性，并给出了测量方法和测量结果．