Deformation due to time harmonic sources in micropolar thermoelastic medium possessing cubic symmetry with two relaxation times

The response of a micropolar thermoelastic medium possessing cubic symmetry with two relaxation times due to time harmonic sources is investigated. Fourier transform is employed and the transform is inverted by using a numerical inversion technique. The components of displacement, stress, microrotation and temperature distribution in the physical domain are obtained numerically. The results of normal displacement, normal force stress, tangential couple stress and temperature distribution are compared for micropolar cubic crystal and micropolar isotropic solid. The numerical results are illustrated graphically for a particular material. Some special cases are also deduced.     

变温度荷载作用下半无限成层饱和介质的热固结分析

对半无限成层饱和多孔介质作用随时间变化的温度荷载的热固结问题进行解析求解．其中,热-水-力耦合线性弹性控制方程考虑了热渗效应和等温热流效应的影响．先采用Laplace变换求其在变换域上的解,然后用数值方法求逆变换．对半无限体表面作用呈指数衰减热荷载的双层体系进行研究,分析了两层介质热固结系数、弹性模量等的差异性对热固结特征的影响．研究表明:位移场和应力场对温度场的耦合作用可以忽略,而热渗效应对温度和孔压有显著影响．     

多孔介质中两相驱离的格子Boltzmann模型新研究

利用粒子之间相互作用,即同种物质粒子相互吸引,异种物质粒子相互排斥这一物理化的原理研究并提出了一个新型的模拟多孔介质中二相驱离的格子玻耳兹曼模型,结果表明它能有效地模拟多孔介质中的二相驱离问题,且节省机时,分界面上涨落也小,不必采取任何平均措施.     

Al-TM合金熔体的中程有序结构及其演化规律

用高温溶体X射线衍射仪对Al-TM（TM = Fe, Ni）合金的熔体结构进行了实验 研究。在Al-1.0at%Fe（原子百分比）合金的结构因子曲线S（Q）上,温度为670 ℃时,存在预峰,即中程有序结构,当温度过热到1400 ℃时,预峰消失。Al- 20at%Ni合金熔体温度在≤1300 ℃范围内,存在预峰;温度高于1400 ℃时,预峰 逐渐消失。这些实验结果表明,Al-Ni, Al-Fe合金熔体中除存在短程有序结构外, 还存在中程有序结构。这种中程有序结构的存在与消失与温度有关。在相似的条件 下,Al-Si合金中没有发现中程有序结构。本文对中程有序结构的演化机理也作了 探讨。     

对钨酸铅晶体光收集效率及其均匀性的蒙特卡洛模拟

利用Litrani软件包^[1]对钨酸铅(PbWO₄或PWO)长晶体的光传导与光收集过程进行了模拟计算,着重讨论了晶体的吸收长度、表面处理等因素对光收集的影响,并对各向同性与各向异性的模拟作了比较.     

Enhancement of Kerr nonlinearity with vanishing absorption in a tripod scheme

The giant enhancement of Kerr nonlinearity in a four-level tripod type system is investigated theoretically. By tuning the value of the Rabi frequency of the coherent control field, owing to the double dark resonances, the giant-enhanced Kerr nonlinearity can be achieved within the right transparency window. The influence of Doppler broadening is also discussed.     

光盘中的化学知识

光盘按其功能可以分为3种:只读式、可录式和可擦重写式。本文对其组成、结构及记录和读取信息的原理进行了简单介绍。     

横观各向同性饱和地基的三维动力响应

首先引入位移函数,将直角坐标系下横观各向同性饱和土Biot波动方程转化为2个解耦的六阶和二阶控制方程;然后基于双重Fourier变换,求解了Biot波动方程,得到以土骨架位移和孔隙水压力为基本未知量的积分形式的一般解,并用一般解给出了饱和土总应力分量的表达式．在此基础上系统研究了横观各向同性饱和半空间体的稳态动力响应问题,考虑表面排水和不排水两种情况,得到了半空间体在任意分布的表面谐振荷载作用下,表面位移的稳态动力响应,文末给出了算例．     

在受轴向周期扰动作用下双壁碳纳米管动力屈曲的研究

对双壁碳纳米管受轴向周期扰动的动力响应进行了研究．采用连续体模型研究双壁碳纳米管的动力屈曲问题,考虑了壁间van der Waals力和周围弹性介质对轴向动力屈曲的影响．给出了受轴向周期扰动的屈曲模型及临界应变和临界频率．发现双壁碳纳米管由于壁间van der Waals力的作用较单壁碳纳米管具有较低的临界应变．van der Waals力和周围弹性介质将影响双壁碳纳米管不稳定区,van der Waals力使受轴向周期性扰动的双壁碳纳米管的临界频率增大,周围弹性介质对双壁碳纳米管的临界频率影响不大．     

Green function on two-phase saturated medium by concentrated force in two-dimensional displacement field

The Green function on two-phase saturated medium by concentrated force has a broad and important use in seismology, seismic engineering, soil mechanics, geophysics, dynamic foundation theory and so on. According to the Green function on two-phase saturated medium by concentrated force in three-dimentional displacement field obtained by Ding Bo-yang et al. , it gives out the Green function in two-dimensional displacement field by infinite integral method along x3 -direction derived by De Hoop and Manolis. The method adopted in the thesis is simpler. The result will be simplified to the boundary element method of dynamic problem.