交接配线式ODN结构的研究

针对光纤到户（FTTH：Fiber To The Home）网络建设中，在接入用户不确定条件下的配线结构选择问题，通过定性和定量的分析方法，对直接配线式ODN(Optical DistributionNetwork)结构与交接配线式ODN结构进行比较。结果表明，交接配线式ODN结构具有接入稳定、覆盖范围大和扩容灵活的优点，适宜在竞争的电信市场环境中应用，对FTTH的大规模工程建设具有一定的借鉴意义。     

Students’ multilingual repertoires-in-use for meaning-making: Contrasting case studies in three multilingual constellations

Mathematics education for multilingual classrooms calls for instructional approaches that build upon students’ multilingual resources. However, so far, students’ multilingual resources and the interplay of their components have only partly been disentangled and rarely compared between different multilingual contexts. This article suggests a conceptualization of multilingual repertoires-in-use as characterized by (a) what students use of certain languages, registers, and representations as sources for meaning-making in mathematics classrooms and (b) their processes of how they connect certain languages, registers, and representations. This qualitative learning-process study compares students’ multilingual repertoires-in-use in three contexts: Spanish-speaking foreign language learners of German in Colombia, Turkish- and German-speaking students born in Germany, and Arabic-speaking German language beginners recently immigrated to Germany. The analysis reveals the biggest differences not only in what the students use, but how they connect languages, registers, and representations. Some of these differences can partly be traced back to different classroom cultural practices. These findings suggest extending the conceptual framework for multilingual repertoires-in-use and including it in a social theoretical perspective. Thus, these findings have important practical consequences for multilingual mathematics classrooms: The instructional approach of relating languages, registers, and representations needs to be applied more flexibly, taking into account students’ different starting points. When doing so, students’ connection processes should be supported and explicated more systematically in order to fully exploit the students’ repertoires.     

基于实景图像的道路限速标志检测算法研究

在基于道路图像的交通标志识别系统中,关键步骤之一就是对图像中的交通标志能够快速有效地检测.以分析限速标志为例,根据限速标志的特点在图像中寻找到其所在的位置并提取出相关区域,为图像的识别做好前期准备.为了提取出交通标志,采用了颜色预处理、形态学滤波、二值化后的连通域处理和圆的检测等方法.实验表明,该方法能有效地从实景图像中提取出含有交通标志的区域.     

双圆弧拟合公路纵断面竖曲线方法

设计公路纵断面竖曲线,采用直线拟合竖曲线的方法,显然存在着不足。文章提出了用双圆弧拟合竖曲线,把竖曲线表示成Ｃ１连续的圆弧段,明显优于采用折线段表示方法,保证了竖曲线的精度和光滑度。文章给出了双圆弧拟合竖曲线的算法。     

双连杆内燃机三维参数化建模与仿真

以双连杆内燃机为背景,采用基于底层语言(VC 6．0)与大型软件包(PrO／Engineer)二次开发相结合的开发模式,研究了内燃机装配仿真系统的总体结构,并建立了1126内燃机参数化模型．在此基础上,运用多体动力学的方法对内燃机曲柄连杆机构进行了动态仿真分析,得到了活塞的升程、速度、加速度变化规律,为内燃机的设计改进提供了重要依据。     

有理Beta样条曲面拼接曲面拼接的新算法

本文依据实际应用系统,介绍了有理Beta样条曲面造型的概念,并根据该系统所运用的曲面边界的具体处理方法,提出了一种新的曲面非连续拼接算法,并加以实现。     

利用UG运动分析模块实现精密剪切模具的运动仿真分析

阐述了机构运动仿真的意义,介绍了在UG中进行运动仿真的过程,指出了在UG中创建机构运动分析方案的步骤,并按照该步骤详细地阐述了实现精密剪切模具运动仿真的过程.给出了动、静模运动过程中的速度曲线,为利用UG进行精密剪切模具的CAD/CAE进行了探索.     

一个平面系统的连结轨道

本文给出了一个平面系统存在连结轨的判定准则,并应用于具体方程组中得到存在连结轨的参数区域．     

EFFECT OF Z-PINS'' DIAMETER, SPACING AND OVERLAP LENGTH ON CONNECTING PERFORMANCE OF CMC SINGLE LAP JOINT

The effect of through-thickness reinforcement by composite pins (Z-pins) on the static tensile strength and failure mechanisms of the joints made from ceramic matrix composite (CMC) is investigated.Overlap length of the single lap joint is 15 mm,20 mm,23 mm,37 mm,and 60 mm,respectively.The experimcntal results indicate that the final failure modes of the joints can be divided into twó groups,(a) the bond-line stops debonding until crack encounters Z-pins;and then the adherends break at the location of Z-pins,when overlap length is more than 20 mm;(b) the bond-line detaches entirely and Z-pins are drawn from adherends,when overlap length is equal to 15 mm.A simple efficient computational approach is presented for analyzing the benefit of through-thickness pins for restricting failure in the single lap joints.Here,the mechanics problem is simplified by representing the effect of the pins by tractions acting on the fracture surfaces of the cracked bond-line.The tractions are prescribed as functions of the crack displacement,which are available in simple forms that summarize the complex deformations to a reasonable accuracy.The resulting model can be used to track the evolution of complete failure mechanisms,for example,bond-line initial delamination and ultimate failure associated with Z-pin pullout,ultimate failure of the adherends.The paper simulates connecting performance of the single lap joints with different Z-pins' diameter,spacing and overlap length;the numerical results agree with the experimental results;the numerical results indicate enlarging diameter and decreasing spacing of Z-pins are in favor of improving the connecting performance of the joints.By numerical analysis method,the critical overlap length that lies between two final failure modes is between 18 mm and 19 mm,when Z-pins' diameter and spacing are 0.4 ram,5 ram,respectively.     

光互连网络中的光学比较交换实现方法

本文提出了一种全混洗交换光互连网络中对两个数字光信号进行比较交换的新方法。用液晶光调制器和光导开关构成数字光信号交换控制单元,自动完成两列数字光信号大小的并行比较和交换