Study of interaction between shock wave and unsteady boundary layer

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激波结构的研究--用立方样条数值模拟Kdv-Burgers激波结构的发展

使用王璞和R·Kahawita教授在河口动力学的数值模拟研究中得到的化简后的立方样条求解偏微分方程的 3× 3矩阵系统求解方法 (1- 3)数值模拟求解了一维的非线性Kdv -Burgers模型方程 ,讨论了耗散与弥散对此激波结构的影响 ,结果和文献[4] 一致。说明了对于Kdv方程不存在扭型弧立波 ;对于Burgers方程不存在钟型孤立波 ;对于Kdv -Burgers方程则兼有二者特点存在扭钟型 (振荡型 )弧立激波 ;这个结论对于文献[5] 是一个数值上的支持。在计算过程中 ,再次显示了立方样条在求解偏微分方程 (特别是流体力学问题 )中所具有的 :(1)任选网格保持高精度 ;(2 )极易处理边条 ;(3)具有的三对角型方程组计算快捷等优点。     

一类非线性方程激波位置与边界条件的关系

利用匹配条件讨论一类非线性方程的激波解.在一定条件下,当边界条件作微小变化时,激波位置作相应的偏移,激波解的形式也发生了较大的改变.最终得出了各种方式情形下,对应的激波解与边解条件的关系.     

一类具有非线性边界阻尼和源项的非线性波动方程的解的渐近性

研究一类具有非线性边界阻尼和源项的非线性波动方程的初边值问题，证明在一定条件下其整体广义解的存在、解具有衰减性并给出了解的衰减估计。     

On the hydrodynamic stability of a particle-laden flow in growing flat plate boundary layer

INTRODUCTION Turbulent particulate flows occur in many in-dustrial applications, such as in pneumatic transportof particulates, cyclone separators and chemical re-actors. The particles suspended in fluid play a role inthe turbulence modulation, which has been known forseveral years. The observation that adding dust to airflowing in turbulent motion through a pipe can ap-preciably reduce the resistance coefficient was re-ported by Sproull (1961). The observation can beexpressed as saying …     

Numerical simulation of water mitigation effects on shock wave with SPH method

The water mitigation effect on the propagation of shock wave was investigated numerically. The traditional smoothed particle hydrodynamics (SPH) method was modified based on Riemann solution. The comparison of numerical results with the analytical solution indicated that the modified SPH method has more advantages than the traditional SPH method. Using the modified SPH algorithm, a series of one-dimensional planar wave propagation problems were investigated, focusing on the influence of the air-gap between the high-pressure air and water and the thickness of water. The numerical results showed that water mitigation effect is significant. Up to 60% shock wave pressure reduction could be achieved with the existence of water, and the shape of shock wave was also changed greatly. It is seemly that the small air-gap between the high-pressure air and water has more influence on water mitigation effect.     

一类三阶微分方程激波解的多层现象

利用匹配条件讨论了一类三阶方程奇摄动问题，探讨了其渐近解的多层现象，并根据匹配条件得出相应的一致收敛的二阶近似解。     

冲击氧化铝单晶中失效波弛豫时间因子的测量

在冲击动压为133GPa的氧化铝单晶的冲击实验中,测量了在850nm处冲击氧化铝单晶的辐射曲线,发光信号显示被冲击压缩的单晶中存在延迟发射现象;该现象表明氧化铝单晶在冲击波到达后经历了一个再压缩过程,该过程可用失效波解释;通过实验曲线拟合到在133GPa下失效波的弛豫时间为0．107ms／cm．     

一类非线性方程激波位置的转移

利用引入伸长变量的方法讨论了一类非线性方程的激波位置与边界条件的关系，得出了在一定条件下，当边界条件作微小变化时，激波位置将作较大的偏移，甚至由内层转到边界层的结论。     

一类不具有指数型边界层的边值问题的奇摄动

研究带有小参数的二阶拟线性微分方程的边值问题：εy″=f(t，y)y’ g(t，y)，y(0，ε)=A，y(l，ε)=B．这里f(t，y)≤0且f(0，y)=0．利用微分不等式的相关理论，得到该问题的摄动解关于其退化解的渐近性及误差估计．     

知识与权力的互动与划界

在大学知识活动领域和大学职能变化所受到的社会生活各方面的影响中,政治权力对大学的影响是最直接和最具强度的。政府对大学的干预与大学的自治形成了一种对立统一关系,这两者的关系应在公共利益的基础上形成平衡。当今社会,知识与权力之间的联系日益紧密,"知识就是权力",知识日益成为权力的工具和权力的合法性外衣,大学作为知识组织,往往是规训社会、驯化学生的某种"权力的眼睛"。为了不让知识从属于权力,必须坚持学术自由,保持知识的独立地位,必须要有知识与权力之间自觉、清晰的划界。     

排水性沥青路面上中面层层间结合状况研究

通过环氧树脂、SBS改性乳化沥青、SBS改性热沥青和H#桥面防水材料等4种粘结层材料组合试件的剪切试验,对影响排水性路面的行车荷载、温度和水等外部因素进行了研究和分析.试验结果表明,温度升高会造成层间结合能力的降低,层间剪切强度与温度之间的关系接近一条对数曲线.在实际路面中,行车荷载作用中心区域下的剪切强度较其他部位要小.冻融和饱水等水损害都明显地降低了路面抗剪强度,破坏了上中面层间的层间结合.荷载、温度和水等因素的作用会对层间结合状况产生一定的不利影响,需要通过优选粘结层材料来提高排水性路面的耐久性.     

A numerical approach to the interaction between airflow and a high-speed train subjected to crosswind

Aerodynamic forces and dynamic performances of railway vehicles are coupled and affected by each other. On the one hand, aerodynamic forces change the displacements of a train. On the other hand, displacements affect aerodynamic forces. Based on vehicle-track coupling dynamics and aerodynamics, a numerical approach to the interaction between airflow and a high-speed train is presented in this paper. Aerodynamic forces and dynamic performances of a high-speed train subjected to crosswind were numerically simulated. Results showed that the interaction between airflow and a high-speed train has a significant influence on displacements and aerodynamic forces of the head coach. Therefore, it is necessary to consider the interaction between airflow and a high-speed train subjected to crosswind.     

Mesh size effect in numerical simulation of blast wave propagation and interaction with structures

Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the numerical results are sensitive to the finite element mesh size.Previous numerical simulations show that a mesh size acceptable to one blast scenario might not be proper for another case,even though the difference between the two scenarios is very small,indicating a simple numerical mesh size convergence test might not be enough to guarantee accu-rate numerical results.Therefore,both coarse mesh and fine mesh were used in different blast scenarios to investigate the mesh size effect on numerical results of blast wave propagation and interaction with structures.Based on the numerical results and their comparison with field test re-sults and the design charts in TM5-1300,a numerical modification method was proposed to correct the influence of the mesh size on the simulated results.It can be easily used to improve the accu-racy of the numerical results of blast wave propagation and blast loads on structures.     

曲面单元上超奇性与近超奇性边界积分数值计算的几何变换法

With the aid of the properties of the hypersingular kernels,a geometric conversion approach was presented in this paper.The conversion leads to a general approach for the accurate and reliable numerical evaluation of the hypersingular surface boundary integrals encountered in a variety of applications with boundary element method.Based on the conversion,the hypersingularity in the boundary integrals could be lowered by one order,resulting in the simplification of the computer code.Moreover,an integral transformation was introduced to damp out the nearly singular behavior of the kernels by the distance function defined in the local polar coordinate system for the nearly hypersingular case.The approach is simple to use,which can be inserted readily to computer code,thus getting rid of the dull routine deduction of formulae before the numerical implementatins,as the expressions of these kernels are in general complicated.The numerical examples were gien in three-dimensional elasticity,verifying the effectiveness of the proposed approach,which makes it possible to observe numerically the behavior of the boundary integral values with hypersingular kernels across the boundary.     

人血清白蛋白与番红花红T的相互作用研究

研究了人血清白蛋白与番红花红T的结合反应特征。荧光光谱显示番红花红T对人血清白蛋白的荧光有猝灭作用。用Stern-Volmer方程和Lineweaver-Burk双倒数函数处理实验数据。得到一定温度下的动态猝灭常数和静态猝灭结合常数、反应的热力学参数和结合位点数。根据Fǒster能量转移原理计算了番红花红T与人血清白蛋白的结合距离r=2.80nm。     

Numerical simulation of interaction between laminar flow and elastic sheet

A numerical simulation of the interaction between laminar flow with low Reynolds number and a highly flexible elastic sheet is presented. The mathematical model for the simulation includes a three-dimensional finitevolume based fluid solver for incompressible viscous flow and a combined finite-discrete element method for the three-dimensional deformation of solid. An immersed boundary method is used to couple the simulation of fluid and solid. It is implemented through a set of immersed boundary points scattered on the solid surface. These points provide a deformable solid wall boundary for the fluid by adding body force to Navier-Stokes equations. The force from the fluid is also obtained for each point and then applied on the boundary nodes of the solid. The vortex-induced vibration of the highly flexible elastic sheet is simulated with the established mathematical model. The simulated results for both swing pattern and oscillation frequency of the elastic sheet in low Reynolds number flow agree well with experimental data.     

家族文学研究的分层与守界原则

家族文学研究成为学术热点的同时,也出现了结论大而无当     

药物小分子与生物大分子相互作用的研究进展

药物小分子与生物大分子相互作用的研究是涉及到化学与生命科学等多个领域的交叉课题。血清蛋白（SA）与脱氧核糖核酸（DNA）是生物体内的重要转运载体和生命物质,对药物在体内的分布、代谢过程起到至关重要的作用。本文以相互作用的分子机制为导向,对药物小分子与生物大分子相互作用的原理和分析方法以及最新进展进行综述,为深入探索生命物质的结构与功能以及开发设计高效低毒的新药提供了理论依据。     

一类拟线性波动方程解的长时间行为

该文运用一个特殊的积分不等式得到一类拟线性波动方程初边值问题.