Nodally exact Ritz discretizations of 1D diffusion–absorption and Helmholtz equations by variational FIC and modified equation methods

This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, which is used to modify the shape functions. This approach is applied to the FEM discretization of the steady-state, one-dimensional, diffusion–absorption and Helmholtz equations. Parametrized linear shape functions are directly inserted into a FIC functional. The resulting Ritz-FIC equations are symmetric and carry a element-level free parameter coming from the function modification process. Both constant- and variable-coefficient cases are studied. It is shown that the parameter can be used to produce nodally exact solutions for the constant coefficient case. The optimal value is found by matching the finite-order modified differential equation (FOMoDE) of the Ritz-FIC equations with the original field equation. The inclusion of the Ritz-FIC models in the context of templates is examined. This inclusion shows that there is an infinite number of nodally exact models for the constant coefficient case. The ingredients of these methods (FIC, Ritz, MoDE and templates) can be extended to multiple dimensions     

Accurate and simple synthesis formulas for coplanar waveguides

Simple and accurate closed‐form formulas obtained by using a differential evolution algorithm are presented for the synthesis of coplanar waveguides (CPW). The results of the synthesis formulas proposed in this article are compared with those of the quasi‐static analysis, the synthesis formulas reported by the other researchers and also the experimental works available in the literature. The accuracy of the proposed synthesis formulas is found to be better than 0.75% for 9256 CPWs samples. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

滩海海底管线悬空问题治理对策

根据埕岛油田浅海滩涂地带海底管线的安全评估报告,对目前影响海底管线安全的悬空问题进行分析和讨论,并针对其产生悬空的原因提出治理的对策和方法。重点介绍了水下支撑固定法。     

The differential effectiveness of group psychotherapy: A meta-analytic perspective.

The differential effectiveness of group psychotherapy was estimated in a meta-analysis of 111 experimental and quasi-experimental studies published over the past 20 years. A number of client, therapist, group, and methodological variables were examined in an attempt to determine specific as well as generic effectiveness. Three different effect sizes were computed: active versus wait list, active versus alternative treatment, and pre- to posttreatment improvement rates. The active versus wait list overall effect size (0.58) indicated that the average recipient of group treatment is better off than 72% of untreated controls. Improvement was related to group composition, setting, and diagnosis. Findings are discussed within the context of what the authors have learned about group treatment, meta-analytic studies of the extant group literature, and what remains for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation codes at singular points of algebraic differential equations

We use the special geometry of singular points of algebraic differential equations on the affine plane over finite fields to study the main features and parameters of error correcting codes giving by evaluating functions at sets of singular points. In particular, one gets new methods to construct codes with designed minimum distance. This work was partially supported by MCyT BFM2001-2251.     

起落架落震试验飞机机轮三向冲击位移的动态测量

为了研究飞机起落架受冲击载荷时的功量吸收状况，须在起落架落震试验中，对飞机着陆瞬间起落架机轮在空间三个方向上冲击位移的动态变化量进行测量。为此，本文设计了四自由度空间定位装置，并使其与计算机连接，实现了落震试验过程中，起落架在高速冲击状态下机轮三向位移的有效测量与记录。     

空间柔性机械臂三维动力学数值仿真

本文应用ｄ＇Ａｌｅｍｂｅｒｔ－Ｌａｇｒａｎｇｅ原理，对由基座、（ｎ－１）个柔性连杆及端部负载组成，相互用柱铰连接的柔性链式多体系统进行建模；对在空间技术中，具有一刚杆，两柔杆加上刚性负载所组成的三维机械臂系统，采用Ｇｅａｒ算法进行数值仿真。仿真结果比较符合实际，从而在柔性多体系统的数学模型为刚性常微分方程的情况下，为解决其数值仿真问题，特别是三维问题的数值仿真取得了进展。     

抽油机球铁齿轮的化学成分及生产工艺

为提高抽油机减速器齿轮铸件的机械性能，提出以Sn代替Mo作为合金元素，并通过试验确定了合理的Si、Cu、Sn的加入量。指出Si加入量应控制在1．9％－2．1％范围内，同时加入0．36％～0．9％的Cu和0．025％～0．07％的Sn，可保证球铁的强度和延伸率都满足QT700－2的要求。鉴于试件与实际铸件的表面硬度有一定的差值，为提高铸件表面硬度，进行了余热正火试验，并给出了铸件在铸型内的时间－冷却温度曲线。最后根据球铁化学成分的选择结果，进行了齿轮生产试验。     

差动光栅在精密测试中的应用

提出差动光栅概念,举例说明差动光栅在光纤面板刀口响应测试和材料形变自动监测系统等精密测试中的应用。     

MIM隧道结的电子输运特性和发光研究

论述作为一种新型发光器件的ＭＩＭ隧道结的发光机理，报告了该器件的发光现象和Ｉ－Ｖ特性曲线中负阻现象的实验观察。数据显示，结中表面等离极化激元（ＳＰＰ）与粗糙度的耦合是引起光发射的主要方面，ＳＰＰ对隧穿电子的阻塞作用导致了电子输运中的负阻现象。此外，还观察到了直接辐射的紫外峰。