天然气管网的瞬变流数值模拟研究

研究了天然气管网中的瞬变流动,介绍了采用特征线法求解天然气管网瞬变流的方法,讨论了该方法的物理意义及其计算公式.采用该方法对工程实例进行了模拟与分析.结果表明,特征线法能满足不同瞬变条件下的精度与计算速度要求,对天然气管网的可靠性评价和优化管理提供了理论依据.     

Synthesis and characterisation of imidazolium-based ionic liquid crystals bearing a cholesteryl mesogenic group

A series of cholesteryl-containing imidazolium chlorides and imidazolium tetrachloroaluminates were synthesised, and the chemical structure, liquid crystalline behaviour and ionic conductivity were characterised by several technical methods. Whereas the imidazolium chlorides show chiral smectic A (SmA*) phase on heating and cooling cycles, the imidazolium tetrachloroaluminates display chiral nematic (N*) phase, which is uncommon for ionic liquid crystals (ILCs). The imidazolium chlorides display similar phase transition temperature and entropy, indicating the cholesteryl component influence predominately on the phase transition rather than the different alkyl substituent groups. The imidazolium tetrachloroaluminates show lower melting point temperatures and lower clear point temperature than the imidazolium chlorides. The mesophases exist at rather moderate temperatures. Non-mesomorphic imidazolium tetrachloroaluminate(III) salts with short alkyl substituents have been known for a long time, and the synthesised imidazolium tetrachloroaluminates are the first examples of tetrahalogenoaluminate(III)-containing ILCs. For the imidazolium tetrachloroaluminates, imidazolium cations combine loosely with AlCl₄^? ions because AlCl₄^? ions are large and occupy more space in spite of the hydrogen bond and electrostatic attraction interaction, indicating that the layer structure can be destroyed easily to form N* phase on heating.     

急性失眠的国外研究述评

对急性失眠的国外研究进行了综述。首先介绍了当前用于急性失眠诊断的3个系统,来探讨急性失眠的概念化问题;从已有的病因理论模型和近年来病因探究的新进展,来解释急性失眠的发病机制。阐述了急性失眠的治疗与用药现状。最后提出了急性失眠未来研究的几点建议。     

实时织物悬垂性能物理模型及应用

快速计算机模拟和仿真技术是纺织物、服装的计算机辅助设计和制造的关键技术组成．逼真的纺织物、布料、服装的三维计算机可视化设计在其他许多领域也非常重要．例如在3DCG电影制作中逼真的计算机服装动态特效、3D电脑游戏、网上购物等．本文着重于计算方法，综述和分析了服装物理模型及其应用的最新进展，探讨了当前主要存在的问题，技术挑战，和可能的解决方案．提出了一种基于变形能的服装悬垂模型及算法，并展示了仿真结果．本文所提出的模型适用于纺织物、服装的快速计算机三维动态模拟．另外，也提出和探讨了识别纺织物材料的复杂动态变形材料性能参数的可能性方案．     

碳分子筛的制法、性质和用途

本文综述了碳分子筛的制法、性质和用途，论述了碳分子筛的研究进展，指出碳分 子筛的优越性在于它具有潜在新用途，加强这方面的研究是化学、化工工作者探讨的领域之 一。     

V型太阳能空气集热器热过程的数值模拟

从太阳能空气集热器传热特征及热平衡分析出发，建立了适合于V型、平板型、单流道、双流道、带与不带肋片的空气集热器的通用数学模型，并根据工程实际对模型作了合理的简化。采用有限差分法对微分方程离散化后，可方便地求得空气集热器的瞬时效率。     

ANALYSIS AND EXPERIMENT ON TRANSIENT DYNAMIC RESPONSE IN FINITE MINDLIN PLATE

The transient wave propagation in the finite rectangular Mindlin plate is investigated by the analytical and experimental methods. The generalized ray method (GRM) which has been successfully applied to study the transient responses of beams, planar trusses, space frames and infinite layered media is extended to investigate the transient wave propagation and early short time transient response in finite Mindlin plate. Combining the wave solution, the shock source and the boundary conditions, the ray groups transmitted in the finite rectangular plate can be determined. Numerical simulations and experiments are performed and compared with each other. The results show that the transient wave propagation and early short time transient responses in the finite plate can be studied using the GRM. The early short time transient accelerations are very large for the finite plate subjected to the unit impulse, while the early short time transient displacements are very small. The early short time transient accelerations under the unit impulse are much larger than those under the unit step impulse. The thickness and material characteristics have remarkable effects on the early short time transient responses.     

苏州拙政园游客行为调查与分析

园林是苏州最重要的旅游资源 ,园林开发程度的高下直接关系到苏州旅游业的发展规模和速度。本文以拙政园为例 ,通过对拙政园国内游客行为进行调查与分析 ,得出游客出游的基本规律及游客对该园林的改进意见 ,并在此基础上提出发展苏州旅游业的几点建议。     

矿内空气非定常流动规律研究

根据矿内空气非定常流动方程，分析了均匀管道的简谐振荡特性和周期压力阶跃脉冲在无限大管道与终端放空管道的瞬态特性，通过现场实测与分析，得出有扰动源引起井巷风流脉动时，流动变化不大而压力振幅较大且压力振幅在传播过程中基本不变的结论。     

推广的梯形公式中间点的渐近性质

得到梯形公式和推广的梯形公式中间点的渐近性质的主要结果是limx→aξ-a/x-a=6/(n+3)(n+2)~(1/n).