Ground State of a Quantum Particle Coupled to a Scalar Bose Field

We use methods from functional integration to prove the existence and uniqueness of the ground state of a confined quantum particle coupled to a scalar massless Bose field. For an external potential growing at infinity, the ground state exists under fairly general conditions while, for a decaying potential, an unphysical condition on the coupling strength is still needed.     

网络传媒业供应链质量控制策略与组织模式选择

网络传媒供应链由内容制作商提供有价值的信息产品(如娱乐、资讯等)并通过网站提供给消费者.产品质量控制对网络传媒供应链至关重要.首先利用博弈论的方法分析内容制作商和网站分别独立决策时的策略,纳什均衡揭示双方的"搭便车"动机使供应链整体利润无法达到最优.然后利用最优化的方法分析他们在垂直整合模式下的策略,发现协调决策可以提高整体利润.最后考虑垂直整合模式的新增成本,分析需求质量弹性、利润分配均匀性和质量控制成本等因素对供应链是否采取垂直整合模式的影响.帮助理解网络媒体产业的质量控制策略和供应链组织模式.     

大尺寸单晶金刚石磨抛一体化加工研究

金刚石因其优异的物理性质被视为下一代半导体材料,然而其极高的硬度、脆性和耐腐蚀性导致其加工困难,尤其是对于大尺寸的化学气相沉积(chemical vapor deposition, CVD)单晶金刚石(SCD)晶片而言,目前还缺乏一种高效、低成本的磨抛加工方法。本文提出一种基于工件自旋转的同心双砂轮磨抛一体化加工技术,在一次装夹中,先采用金刚石磨料的陶瓷内圈砂轮磨削单晶金刚石晶片表面,将单晶金刚石表面迅速平坦化,后采用金刚石与CuO混合磨料的外圈溶胶-凝胶(sol-gel,SG)抛光轮抛光单晶金刚石晶片表面,使其在较短时间内完成从原始生长面(Sa约46 nm)到原子级表面精度(Sa＜0.3 nm)的加工。磨削加工中,硬质金刚石磨料的陶瓷砂轮高速划擦金刚石晶片表面,在强机械作用下获得较大的材料去除以及纳米级的光滑单晶金刚石表面,同时引起进一步的表面非晶化;SG抛光加工中,硬质金刚石磨料高速划擦单晶金刚石表面形成高温高压环境,进一步诱导CuO粉末与单晶金刚石表面的非晶碳发生氧化还原反应,实现反应抛光。磨抛一体化的加工技术为晶圆级的单晶、多晶金刚石的工业化生产提供借鉴。     

基于科教融合开展制药分离工程案例教学的研究*

制药分离工程是一门实践性较强的课程,传统授课模式侧重于理论知识的讲解,缺乏对学生解决实际问题的能力和设计能力的培养。以“金雀花花蕾中异鼠李素-3-O-β-D-芸香糖的提取”工程案例和实施过程为例,介绍如何通过案例教学和现代信息技术强化学生实践能力的培养,并对案例教学应用于制药分离工程教学进行了探讨。     

Compound wall treatment with low‐Re turbulence model

A generalized treatment for the wall boundary conditions relating to turbulent flows is developed that blends the integration to a solid wall with wall functions. The blending function ensures a smooth transition between the viscous and turbulent regions. An improved low Reynolds number k?ε model is coupled with the proposed compound wall treatment to determine the turbulence field. The eddy viscosity formulation maintains the positivity of normal Reynolds stresses and Schwarz' inequality for turbulent shear stresses. The model coefficients/functions preserve the anisotropic characteristics of turbulence. Computations with fine and coarse meshes of a few flow cases yield appreciably good agreement with the direct numerical simulation and experimental data. The method is recommended for computing the complex flows where computational grids cannot satisfy a priori the prerequisites of viscous/turbulence regions. Copyright © 2011 John Wiley & Sons, Ltd.     

An enriched finite element algorithm for the implicit simulation of the Stefan problem

An implicit enriched finite element algorithm is proposed to simulate heat transfer involving isothermal phase changes. This technique is based on a mixed variational formulation discretized by means of an enriched finite element approximation of the enthalpy in space. The interface is implicitly described without coupling with an interface-capturing technique. The time integration is carried out with an implicit (backward) Euler algorithm in time. Two examples in 1D and 2D clearly evidence the efficiency of the method developed.     

结构损伤诊断的改进灵敏度方法

提出一种改进的灵敏度方法用于工程结构损伤检测中。通过在迭代算法中引入一个“加速”公式来迅速获得足够精确的识别结果,避免了多次迭代,可以大大减少计算花费。用文献[8]和文献[10]中的两个数值算例对所提方法进行了验证,并把结果和原文中的计算结果进行比较。结果表明：采用改进的方法一般只需经过一次计算即可获得精度更高的识别结果,避免了多次迭代,显著减少了计算花费,显示了改进方法突出的优越性。     

基于微分求积法求解非粘滞阻尼系统的时程响应

研究一种含有指数型非粘滞阻尼线性多自由度振动系统的时程分析问题。该非粘滞阻尼模型假设阻尼力与质点速度的时间历程相关,数学表述为质点速度与核函数的卷积。由于阻尼模型的改变,常用的数值积分方法（如Newmark-β法、Wilson-θ法）不能直接应用于这种非粘滞阻尼系统。基于一种无条件稳定的微分求积方法,给出了这种非粘滞阻...