四边固定载流矩形薄板的磁弹性稳定性分析

本文针对四边固定载流矩形薄板，利用Mathieu方程解的稳定性，研究其在电磁场与机械荷载共同作用下的磁弹性稳定性问题。首先在载流薄板的磁弹性非线性运动方程、物理方程、几何方程、洛仑兹力表达式及电动力学方程的基础上，导出了载流薄板在电磁场与机械荷载共同作用下的磁弹性动力稳定方程，然后应用Galerkin方法将稳定方程整理为Mathieu方程的标准形式，并将薄板的动力稳定性问题归结为对Mathieu方程的求解。利用Mathieu方程的稳定解区域与非稳定解区域的分界，即方程系数λ和η的本征值关系，得出了磁弹性问题失稳临界状态的判别方程。通过具体算例，给出了四边固定载流矩形薄板的磁弹性动力失稳临界状态与相关参量之间的关系曲线，并对计算结果及其变化规律进行了分析讨论。

数值模拟二元喷管的三维可压粘性流场

发展了一种用扫描有限元素法求解二元喷管内部湍流流场的数值模拟方法，并提出了N-S方程中二阶导数项新的离散方法，推导了更完善、更简洁的扫描有限元方程的表达式。用发展的方法对二维平面收扩喷管、两个大宽高比的二元喷管(宽高比分别为7和4)及其圆转方转接段的三维粘流场等算例的计算结果表明，该方法具有较宽广的适用范围，有较高的应用和研究价值。

黑体泵浦CO_2-CO,N_2O-CO,CO_2-H_2O和N_2O-H_2O激光的研究

本文对黑体辐射泵浦CO_2激光和N_2O激光由于CO和H_2O的加入所引起的激光功率变化进行了理论和实验研究.CO的加入可使的N_2O激光功率增加28%.

复合材料的多层、夹层和加筋圆柱曲板的稳定和振动

本文在文献〔1,2〕的基础上,考虑了沿壳体厚度方向的剪切变形,探讨周边简支的纤维增强复合材料的正交各向异性的多层、夹层和加筋矩形圆柱曲板(与圆柱壳),在轴压、侧压和剪切(扭矩)作用下的临界载荷和横向振动固有频率的计算问题。在编成计算程序后,用一些算例将用文献〔1〕中的扁壳方程(Donnell壳体理论) 和文献〔3〕中的非扁壳方程(Love的壳体一阶近似理论) 算得的结果作了比较;将轴压下轴对称失稳和非轴对称失稳的临界载荷作了比较;将在轴压和侧压作用下失稳时外加筋曲板和内加筋曲板的临界载荷作了比较;将有薄膜力N_x~0和N_y~0同时和分别作用时与没有薄膜力作用时的横向振动固有频率作了比较;将按壳体的剪切变形理论和经典理论算得的临界载荷作了比较;将铺层情况对临界载荷的影响作了比较。

等离子体电弧炉中的传热问题和一个设计原则

本文在供给电弧能量一定的条件下,建立了等离子体电弧炉二维传热模型,其传热系数可以随温度而变化。经过一些函数变换并采用分离变量法,给出了气体热流势和等离子体电弧炉传热效率η的分析表达式。最后本文还给出了传热效率η关于电弧与熔炼物间无量纲距离r_0和另一个无量纲量l/Q(以下详细说明)的简单的线性关系,它提供了一个电弧设计原则。

对二维编织复合材料弹性、热、强度及失效分析模型的评论

纺织结构作为聚合物复合材料的增强相在许多工业应用中变得非常重要,例如在航海与航空领域中,由于其刚度及强度与其重量的高比值而倍受炊迎.由于工业及工程应用的需求,研究纺织复合材料的弹性性质及失效行为变得非常重要.这篇文章重点评论了关于二维编织复合材料弹性、热、强度及失效分析的数值及解析模型,给出了主要的建模技术及方法.同时也简单给出了编织复合材料从最初的一维模型到最近三维模型的发展.本文的目的不是对所论模型的数学方法进行详细分析,而是告知研究者关于先前工作的主要思想.这篇评论总共引用了122篇文献.

带主动冷却的超声速燃烧室传热分析

介绍了流体、固体传热耦合的一维分析方法,对带主动冷却系统的马赫数2.5超声速燃烧室进行了传热分析.该分析以实验测量的燃烧室壁面静压以及超临界煤油换热特性数据为基础,考虑了燃气的高温离解效应,燃烧特性以及碳氢燃料的高温热物理特性,对不同燃烧状态、冷却条件下的主动冷却过程进行了分析.结果表明有燃烧时壁面热流可高达1 MW/m~2以上,是无燃烧时的2～3倍.当煤油流量较小时(当量比为0.45),冷却后的壁面温度仍偏高,而且冷却壁内温度分布不均匀.随着煤油流量的增加,冷却效果明显提高,冷却壁内温度分布趋于均匀;并且煤油的出口温度也显著减小.

一种含运动固壁超声速流动的Descartes网格算法

提出一种Descartes网格算法,用于数值求解含任意复杂及运动固壁的超声速流动问题.采用位标集函数确定和跟踪流-固界面.引入虚网格技术处理流-固边界条件,并沿法向和切向分别进行计算.该算法简单、稳健,可与高阶有限差分格式并用.选取一组一维/二维静止或运动物体绕流算例,验证其有效性.

Propagation of a few-cycle laser pulse in a V-type three-level system

Propagation of a few-cycle laser pulse in a V-type three-level system (fine structure levels of rubidium) is investigated numerically. The full three-level Maxwell-Bloch equations without the rotating wave approximation and the standing slowly varying envelope approximation are solved by using a finite-difference time-domain method. It is shown that, when the usual unequal oscillator strengths are considered, self-induced transparency cannot be recovered and higher spectral components can be produced even for small-area pulses. (c) 2005 Pleiades Publishing, Inc.

Femtosecond optical Kerr effect study of Ge(10)AS(40)S(30)Se(20) film

The results of the femtosecond optical heterodyne detection of optical Kerr effect at 805 nm with the 80 fs ultrafast pulses in amorphous Ge10As40S30Se20 film is reported in this paper. The film shows an optical non-linear response of: 200 fs under ultrafast 80 fs-pulse excitation and the values of real and imaginary parts of non-linear susceptibility chi((3)) were 9.0 X 10(-12) and -4.0 X 10(-12) esu, respectively. The large third-order non-linearity and ultrafast response are attributed to the ultrafast distortion of the electron orbits surrounding the average positions of the nucleus of Ge, As, S and Se atoms. This Ge10As40S30Se20 chalcogenide glass would be expected as a promising material for optical switching technique. (c) 2005 Elsevier Ltd. All rights reserved.

Preparation, characterization and gas sensing properties of nickel octa-iso-pentyloxynaphthalocyanine spin-coating films

Spin-coated films of nickel 1,6,10,15,19,24,28,33-octa-iso-pentyloxy-2,3-naphthalocyanine complex were obtained and characterized by UV-vis absorption spectroscopy. A linear relationship between the absorbance and solution concentration was observed. Low concentration solutions could afford smooth and homogeneous film surfaces as indicated by atomic force microscopy. The film structure was studied by small angle X-ray diffraction. The films were used for NO2 sensing experiments. The results indicate that the elevation of sensing temperature can shorten the response time and increase recovery ratio and response magnitude of the sensing films. High NO2 concentration can also shorten response time. (C) 2008 Elsevier B.V. All rights reserved.

硅片表面球形粒子散射研究

为求解硅片表面微小粒子在任意线偏振平面入射光照射下的散射光光强分布，选择了基于Mie散射的杨氏模型为依据，推导了该模型下散射光强空间分布的计算方法，并给出了0．54／μm球形粒子在垂直、倾斜入射下光强空间分布的模拟计算结果，以及入射平面第一象限内散射光强与国外已发表实验结果的比较．

Characterization of diode-pumped laser operation of a novel Yb : GSO crystal

We report what is believed to be the first demonstration of the laser action of Yb3+ -doped Gd2SiO5 (Yb:GSO) crystal pumped by a 940-nm laser diode at room temperature. The threshold of laser generation is only 0.85 kW/cm(2), which is smaller than the theoretic threshold of Yb:YAG (1.54 kW/cm(2)). The laser wavelength is 1090 mn. With a 2.5% output coupler, the maximum output power is 415 mW under a pump power of 5 W. By using the SESAM, the Q-switched mode locking and CW mode-locked operations are demonstrated.