具有N-策略和延迟单重休假且休假不中断的M/G/1排队系统

本文考虑具有N-策略和延迟单重休假且休假不中断的M/G/1排队系统.运用更新过程理论,全概率分解技术和Laplace变换工具,从任意初始状态出发,研究了队长的瞬态和稳态性质,获得了瞬态队长分布的Laplace变换的表达式和稳态队长分布的递推表达式.同时求出了稳态队长分布的概率母函数和附加队长分布的显示表达式.进一步讨论...     

多级适应性休假$M^X/G/1$排队系统的队长分布

考虑多级适应性休假的MX/G/1排队系统.采用一种较简单的分析方法,讨论了队长分布的瞬态和稳态性质,得到了队长瞬态分布的拉普拉斯变换的递推表达式和稳态分布的递推表达式,以及稳态队长的随机分解,并给出了服务台闲期、服务台忙循环期的分布函数.另外,从讨论中直接导出了一些特殊排队模型的相应指标.     

积分变换在数理方程中的应用

积分变换是研究数理方程的重要工具.利用Fourier变换或Laplace变换,可以求得一些数理方程的显式解.事实上,对于一些半无界问题的数理方程如热传导方程,可以进行Fourier-Laplace变换,通过寻求半无界问题的Green函数和全空间问题热核的关系,给出半无界问题解的表达式.     

半圆域内的二维线性椭圆偏微分方程

本文研究了半圆域内的二维线性椭圆偏微分方程.利用Fokas提出的求解凸多边形区域内的线性椭圆偏微分方程的变换方法,我们改进了这个方法来研究半圆域内Laplace方程,修改Helmholtz方程和Helmholtz方程的解,并且导出了这些方程解的积分表达式,讨论了Helmholtz方程的广义Dirichlet到Neumann映射.     

半圆域内的二维线性椭圆偏微分方程（英文）

本文研究了半圆域内的二维线性椭圆偏微分方程.利用Fokas提出的求解凸多边形区域内的线性椭圆偏微分方程的变换方法,我们改进了这个方法来研究半圆域内Laplace方程,修改Helmholtz方程和Helmholtz方程的解,并且导出了这些方程解的积分表达式,讨论了Helmholtz方程的广义Dirichlet到Neumann映射.     

假期中顾客以概率p进入的单重休假M/G/1排队

本文考虑单重休假M/G/1排队系统,其中在服务员休假中到达的顾客以概率p(0≤p≤1)进入系统,采用一种较简单的分析方法,得到了队长瞬态分布的拉普拉斯变换的递推表达式和稳态分布的递推表达式.另外,通过本文的研究直接导出了一些特殊情况下的相应结果.     

带两步保费率的复合Poisson风险模型的占位时（英文）

本文考虑了带两步保费率的经典复合Poisson风险模型.使用一种替代方法,找到了两个不相交时间间隔的联合占位时对应Laplace变换的显式表达式.其中,Laplace变换用Levy过程的尺度函数来表示.     

阈红利边界下理赔时间间隔与理赔额相依的风险模型

考虑阈红利边界下理赌时间间隔与理赔额相依的风险模型.首先给出了该模型的Gerber- Shiu函数满足的积分.微分方程及更新方程,然后利用Laplace变换及复合几何分布函数得到了Gerber-Shiu函数的确切表达式.     

延迟Min(N,D)-策略的M/G/1排队系统的队长分布与数值计算

考虑延迟Min(N, D)-策略的M/G/1排队系统. 运用更新过程理论、全概率分解技术和Laplace变换工具, 从任意初始状态出发, 研究了队长的瞬态和稳态性质, 获得了瞬态队长分布的Laplace变换的递推表达式和稳态队长分布的递推表达式, 同时求出了附加队长分布的显示表达式. 进一步讨论了当N \to \infty, 或D \to \infty, 或N=1且P{Y=0}=1, 或P{Y=0}=1时的特殊情形. 最后通过数值实例, 讨论了稳态队长分布对系统参数的敏感性, 并阐述了稳态队长分布的表达式在系统容量优化设计中的重要价值.     

反演二维瞬态热传导问题随温度变化的导热系数

基于边界元法反演二维瞬态热传导问题随温度变化的导热系数.采用Kirchhoff变换将非线性的控制方程转变为线性方程.边界元法用于构建二维瞬态热传导问题的数值分析模型.将反演参数作为优化变量,测点温度计算值与测量值之间的残差平方和作为优化目标函数.引入复变量求导法求解目标函数的梯度矩阵,梯度正则化法用于优化目标函数获得反演结果.探讨时间步长、测点数量和随机偏差对反演结果的影响.减小步长、增加测点数量收敛速度加快.降低了随机偏差,计算结果更精确.算例证明了算法的有效性与稳定性.     

On transient heat conduction in the walls of a rectangular gas channel

In this paper a problem on transient heat conduction in the walls of a gas channel with a rectangular cross-section is solved. The temperature of the gas flow in the channel rises linearly while the temperature of the surrounding open air is constant.The differential equation and its auxiliary conditions are Laplace transformed, the subsidiary equations are solved by a method resembling the two-dimensional relaxation method for steady state heat conduction problems, and the resulting temperatures are obtained by numerical inversion.Numerical results are presented at the end of the paper.     

Cooling of a cylindrical container blasted into the rock

An upright cylindrical container blasted into the rock is filled instantaneously with a warm liquid. Heat is transferred from the liquid into the surrounding rock and the open air. The temperature of the liquid and the surrounding rock is determined as a function of time.The differential equation and the auxiliary conditions of the transient heat conduction problem are Laplace transformed, the subsidiary equations are solved by two-dimensional relaxation, and the resulting temperature is obtained by means of numerical inversion of the Laplace transform.The results are presented numerically and graphically.     

非饱和土层一维固结问题的解析解

对一有限厚度,处于一维受荷状态,表面为透水透气面,底面为不透水不透气面的非饱和土层,依据Fredlund的非饱和土一维固结理论,由液相及气相的控制方程、Darcy定律及Fick定律,经Laplace变换及Cayley-Hamilton数学方法构造了顶面状态向量与任意深度处状态向量间的传递关系;通过引入初始及边界条件,得到了Laplace变换域内的超孔隙水压力、超孔隙气压力以及土层沉降的解;实现Laplace逆变换,得到了时间域内的解析解;用一典型算例,与差分法结果进行对比,验证了其正确性．     

放/吸热流体在两个充满多孔材料的竖直平行板之间作不稳定的自然对流

在一个由两块无限竖直平行板组成的管道中,充满着多孔的介质材料,使用Darcy模型(Brinkman模型的推广)的动量方程,连同能量方程,计算不可压缩、粘性、放/吸热流体在该管道中的不稳定自然对流,即Couette流动.流动是由于边界平板有不对称的加热,以及作加速运动所引起.选用合理的无量纲参数,对控制方程进行简化,通过Laplace变换进行解析求解,得到闭式的速度和温度分布曲线解,随后导出表面摩擦力和传热率.发现在竖直管道中的不同剖面,流体的流动及温度分布曲线随着时间而增加,且在运动平板附近更高.特别是,流体的速度和温度随着平板间距的增加而增加,但是,表面摩擦力和热传导率随着平板间距的增加而减小.     

Time-dependent MHD Couette flow in a porous annulus

This study presents the solution for the MHD transient Couette flow in an annulus formed by two concentric porous cylinders of infinite length. The fluid flow is induced by either the impulsive or the accelerated movements of the outer cylinder. A uniform magnetic field is assumed to be applied perpendicular to the direction of flow. General solution of the governing equations is obtained using a combination of Laplace transform and the Riemann-sum approximation method of Laplace inversion. The expressions for the skin friction at the two walls are obtained in both cases. The variations of the velocity and the skin friction with respect to the Hartmann number and suction/injection parameter have been discussed. It is found out that suction accelerates the flow whereas injection retards the flow.     

基于分数阶热传导方程激光加热瞬态温度场研究

基于分数阶Taylor(泰勒)级数展开原理,建立单相延迟一阶分数阶近似方程,获得分数阶热传导方程.针对短脉冲激光加热问题建立分数阶热传导方程组,并运用Laplace(拉普拉斯)变换方法进行求解,给出非Gauss(高斯)时间分布的激光内热源温度场解析解.针对具体算例数值研究温度波传播特性.结果表明热传播速度与分数阶阶次有关,分数阶阶次增加,热传播速度减小,温度变化幅度增加.分数阶方程可以用于描述介于扩散方程和热波方程间的热传输过程,且对热传播机制与分数阶热传导方程中分数阶项的关系做了深入剖析.     

非饱和土一维固结的半解析解

首先对Fredlund的非饱和土一维固结理论进行简化,由得到的液相及气相的控制方程、Darcy定律及Fick定律,经Laplace变换及Cayley-Hamilton定理构造了顶面状态向量与任意深度处状态向量间的传递关系;通过引入边界条件,得到了大面积瞬时加荷情况多种边界条件下Laplace变换域内的超孔隙水压力、 超孔隙气压力及土层沉降的解;采用Crump方法编制程序实现Laplace逆转换,得到了时间域内的超孔隙水压力、超孔隙气压力、土层沉降的半解析解;引用典型算例,对单面排水排气情况,与已有的解析解进行对比,验证其正确性;对单面排气不排水情况,与差分法结果进行对比进一步证明半解析解的正确性,并进行固结特性分析．该研究对非饱和土一维固结的研究具有重要的意义．     

三相滞后对有球形空腔无限介质双温广义热弹性的影响

就各向同性的无限弹性体,具有一个球形空腔时,从双温广义热弹性理论（2TT）角度,研究三相滞后热方程的热弹性相互作用问题．在三相滞后理论中,热传导方程是一个含时间四阶导数的、双曲型的偏微分方程．假设无限介质初始时静止,通过Laplace变换,将基本方程用向量矩阵微分方程的形式表示,然后通过状态空间法求解．将得到的通解应用于特殊问题:空腔边界上承受着热荷载（热冲击和坡型加热）和力学荷载．使用Fourier级数展开技术,实现Laplace变换的求逆．计算了铜类材料物理量的数值解．图形显示,两种模型:带能量耗散的双温Green-Naghdi理论（2TGNIII）和双温3相滞后模型（2T3相）明显不同．还对双温和坡型参数的影响进行了研究．     

Nonlocal coupled photo-thermoelasticity analysis in a semiconducting micro/nano beam resonator subjected to plasma shock loading: A Green-Naghdi-based analytical solution

In this article, coupled photo-thermoelasticity analysis is carried out using an analytical method in a semiconducting micro/nano beam resonator, considering Green – Naghdi theory (with energy dissipation) and small scale effects. The governing equations for temperature and displacement fields are derived using Eringen nonlocal theory combined with Rayleigh beam theory. One end of the assumed semiconducting MEMS/NEMS is excited by three types of suddenly increasing carrier density and temperature as the plasma and thermal shock loading. The transient behaviours of carrier density field are studied and the effects of disturbances in plasma field on other fields including temperature and deflection are obtained using the proposed analytical solution. The presented analytical solution is based on Laplace transform. To find the dynamic and transient behaviours of fields’ variables in time domain, an inversion Laplace technique is utilized, which is called Talbot method. The effects of small scale parameter and dimensions of the semiconducting micro/nano beam on the dynamic behaviours of fields’ variables are discussed in detail. The axial wave propagation and the distribution of fields’ variables along axial direction are studied at various times.     

Solution of fractional order heat equation via triple Laplace transform in 2 dimensions

In this article, we introduce the triple Laplace transform for the solution of a class of fractional order partial differential equations. As a consequence, fractional order homogeneous heat equation in 2 dimensions is investigated in detail. The corresponding solution is obtained by using the aforementioned triple Laplace transform, which is the generalization of double Laplace transform. Numerical plots to the concerned solutions are provided to demonstrate our results.