10 Gb/s 光模块的设计与测试

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

微重力燃烧研究进展

认识燃烧过程是安全、高效、洁净地利用能源的基础.但是,常重力条件下的浮力对流和重力沉降使得燃烧现象变得复杂.而微重力条件下这些影响几乎消失,这简化了对燃烧的研究.在加深对地面燃烧过程和载人航天器火灾安全问题的认识的推动下,经过近半个世纪特别是最近10多年的发展,微重力燃烧研究已经涵盖了预混气体、气体扩散、液滴、颗粒和粉尘燃烧、燃料表面的火焰传播等燃烧学科的各个领域.研究中实现了球对称液滴燃烧、不受沉降影响的粉尘燃烧、静止或低速对流环境中的燃烧,观察到了火球、自熄灭火焰等现象,阐明了碳黑形成中的热泳力效应、可燃极限与火焰稳定性等机理.加深了对燃烧现象,特别是对辐射效应的理解:在预混气体、气体扩散、液滴等多种火焰中,除了停留时间过短引起的吹熄极限外,还存在辐射热损失过大引起的冷熄极限,后者只能在微重力条件下观测到.部分研究成果已经进入教材.而火焰在微重力下不同于常重力下的现象,对载人航天器火灾安全具有重要意义.考虑到我国的现实情况和国内外的研究现状,建议将煤炭颗粒和粉尘的燃烧、与碳黑相关的机理、辐射效应、化学动力学等作为我国微重力燃烧的主要研究方向.

激光弯曲机理的评述

对激光弯曲变形机理问题进行了探讨,提出了激光弯曲的变形机理本质上是温度梯度机理,反向弯曲机理和增厚机理是当材料厚度方向的温度梯度很小时,针对不同厚度的材料而出现的现象.实验发现有限厚度材料在激光辐照作用下,其内部产生了用经典傅里叶定律无法解释的非常规温度分布,将其定义为泛傅里叶效应,用于进一步揭示激光弯曲机理的实质.

郑哲敏对应用力学和技术科学的贡献

2004年10月2日是我们尊敬的郑哲敏先生八十华诞.是年9月29日,中国科学院力学研究所举办了隆重热烈的"祝贺郑哲敏先生八十华诞应用力学学术报告会".……

修正算子γB_0~0的物理含义解释

本文依据球面波传播原理和介质阻尼效应解释了修正算子的物理含义,解释结果表明加修正算子γB00后的多次透射公式考虑了介质的几何扩散特性,或引入了介质的阻尼特性。最后,通过分析比较,指出基于球面波传播原理的物理解释更符合实际。

多孔弹性海床上的管土相互作用数值模拟

采用有限元软件ABAQUS对管土系统进行分析,土体的本构模型采用多孔弹性模型。通过改变管道的水下重、环境载荷等参数进行计算,可以得到管道的位移、海床孔隙水压力分布、土体侧向隆起。计算结果表明,管道的水下重、环境载荷、土性参数均对管土系统有影响。

变频涡轮式分选机在电厂粉煤灰分选中的应用

本文阐述了粉煤灰分选的各种方法 ,主要介绍了变频涡轮式分选机设备及闭路分选系统工艺特点、系统参数的优化选择 ,以及其在电厂粉煤灰分选中的应用情况。

氢氧爆轰波在变截面扩张管道中传播的数值模拟

采用二阶精度频散控制耗散格式(DCD)和8组分20个方程的基元反应模型,对轴对称变截面管道中氢氧爆轰波传播进行数值模拟.结果表明,爆轰波传播至突变截面扩张管道时,由于稀疏波的作用可能会使爆轰波局部熄爆甚至完全熄爆,对于某些敏感度高的反应气体爆轰波可以二次起爆.而在渐变截面扩张管道爆轰波相对不易熄爆.

超高周疲劳研究现状及展望

超高周疲劳是指疲劳周次达到108及其以上时材料的疲劳行为.与一般认识的疲劳行为不同之处是,超高周疲劳发生在传统疲劳极限以下,因此研究超高周疲劳行为有助于进一步理解疲劳的本质和疲劳机理.文中综述近几年超高周疲劳研究的进展,包括超高周疲劳的典型特征,如S-N曲线的特点、断口特征、断面上的鱼眼形貌以及裂纹的起源与扩展特征等;分析疲劳机理和相关的模型以及简要探讨影响超高周疲劳的一些因素,如加载频率、加载方式、氢的作用等.在此基础上提出值得进一步研究的几个问题.

非转移弧层流等离子体射流熔凝铸铁表面耐磨性的研究

对在大气压条件下用非转移弧层流等离子体射流熔凝强化处理的W-Mo-Cu铸铁表面,采用光学显微镜、显微硬度计、磨损试验机、扫描电镜等,观察和测试了熔凝试样的表面层组织、硬度、耐磨性和磨损形貌.结果表明,熔凝后铸铁表面为初晶渗碳体和莱氏体组成的过共晶组织,硬度和耐磨性有了明显的提高.

机械载荷作用下的单边裂纹电热止裂效应分析

用一种新的方法求解出热源功率密度的表达式,定义出电热应力强度因子的概念。推导出电热应力强度因子的表达式,并与外加载荷产生的应力强度因子相叠加,得到了机械载荷和电流共同作用下的应力强度因子。进而得出应力强度因子与断裂准则的关系。通过算例分析证明,电热止裂可以提高金属材料的安全系数。

Formation and Structure of Composite Coating of HAD and Micro-Plasma Oxidation on A3 Steel

Composite coatings were obtained on A3 steel by hot dipping aluminum(HAD) at 720 degreesC for 6 min and micro-plasma oxidation (MPO) in alkali electrolyte. The surface morphology, element distribution and interface structure of composite coatings were studied by means of XRD, SEM and EDS. The results show that the composite coatings obtained through HAD/MPO on A3 steel consist of four layers. From the surface to the substrate, the layer is loose Al2O3 ceramic, compact Al2O3 ceramic, At and FeAl intermetallic compound layer in turn. The adhesions among all the layers are strengthened because the ceramic layer formed at the At surface originally, FeAl intermetallic compound layer and substrate are combined in metallurgical form through mutual diffusion during HAD process. Initial experiment results disclose that the anti-corrosion performance and wear resistance of composite coating are obviously improved through HAD/MPO treatment.

Two Bubbles Thermocapillary Migration Experimental System

An experimental investigation will be performed on the thermocapillary motion of two bubbles in Chinese return-satellite. The experiment will study the migration process of bubble caused by thermocapillary effect in microgravity environment, and their interaction between two bubbles. The bubble is driven by the thermocapillary stress on the surface on account on the variation of the surface tension with temperature. The interaction between two bubbles becomes significant as the separation distance between them is reduced drastically so that the bubble interaction has to be considered. Recently, the problem has been discussed on the method of successive reflections, and accurate migration velocities of two arbitrarily oriented bubbles were derived for the limit of small Marangoni and Reynolds numbers. Numerical results for the migration of the two bubbles show that the interaction between two bubbles has significant influence on their thermocapillary migration velocities with a bubble approaching another. However, there is a lack of experimental validate for the theoretic results. Now the experimental facility is designed for experimenting time after time. A cone-shaped top cover is used to expel bubble from the cell after experiment. But, the cone-shaped top cover can cause temperature uniformity on horizontal plane in whole cell. Therefore, a metal board with multi-holes is fixed under the top cover. The board is able to let the temperature distribution on the board uniform because of their high heat conductivity, and the bubble can pass through it. In the system two bubbles are injected into the test cell respectively by two sets of cylinder. And the bubbles sizes are controlled by two sets of step-by-step motor. It is very important problem that bubble can be divorced from the injecting mouth in microgravity environment. Thus, other two sets of device for injecting mother liquid were used to push bubble. The working principle of injecting mother liquid is to utilize pressure difference directly between test cell and reservoir