基于德拜模型讨论晶格比热

晶格比热是反映晶体热学性质的一个重要物理量。对晶格比热的具体求解是一个相当复杂的问题,在一般讨论中,常采用爱因斯坦模型及德拜模型。本文基于德拜模型系统地研究了一维简单晶格,二维简单晶格以及三维晶格的晶格比热,并讨论了高低温极限,对进一步理解德拜模型的物理思想,及其讨论具体问题的方法有重要意义。     

关于格蕴含代数的公理系统

简化了由ZhuY .和TuW .给出的格蕴含代数的公理系统 ,并给出另一个公理系统。     

恒定磁场下一维格子的两粒子关联研究

研究了稳恒均匀磁场情况赫伯德势作用的一维有限晶格粒子关联问题，求出能量和波函数的精确解，在此基础上求出磁化强度。计算表明：（1）处于外磁场中的一维格子系统，其能级没有赝三重态，只有赝单态。（2）系统的能量和磁化强度主要取决于外磁场，其次才是关联总动量Q。当η≤1时，无论Q为何值，系统能量和磁化强度均随外磁场增大而非线性减小。而η≥1，系统能量和磁化强度均随外磁场增而线性减小。     

Numerical simulation of wind flow fields around buildings using the lattice Boltzmann method

This paper presents the simulation results of the wind environment around a single high-rise building and that around two tall buildings in tandem arrangement by using the lattice Boltzmann method with an aim to understand the ventilation issues around high-rise buildings in an urban environment. We analyzed the velocity distribution around the buildings and performed numericl simulations to reveal the formation and evolution law of the complex vortex system around the high-rise buildings. Numerical simulation results manifest a periodicity phenamenon in the process of the vortex evolution. For the case of two high-rise buildings, wind velocity in the space between the two buildings is very small, which is nearly a silent regime. Wind velocity above the front building is relatively larger and the maximum wind velocity is approximately 2.5 times the incoming wind velocity. The numerical results can be used in layout planning of high-rise residential buildings to create better environment for ventilation purpose in an urban area.     

用格子Boltzmann方法模拟正压大气运动

用一种新近发展起来的、基于统计力学的计算流体力学方法———格子Boltzmann方法模拟了正压大气的运动。在一般格子Boltzmann的基础上,加入了科氏力和重力,用流体柱高度代替一般模型中的密度,避免了不可压缩流动计算的困难,并用这一改进的模型成功地模拟了地转风和气旋的形成过程     

Comparision of DdQm models in image optical flow analysis based on LBM

The optical flow analysis of the image sequence based on the formal lattice Boltzmann equation, with different DdQm models, is discussed in this paper. The algorithm is based on the lattice Boltzmann method (LBM), which is used in computational fluid dynamics theory for the simulation of fluid dynamics. At first, a generalized approximation to the formal lattice Boltzmann equation is discussed. Then the effects of different DdQm models on the results of the optical flow estimation are compared with each other, while calculating the movement vectors of pixels in the image sequence. The experimental results show that the higher dimension DdQm models, e.g., D3Q15 are more effective than those lower dimension ones.     

基于非交换剩余格的（α,β]-模糊滤子（上）

对BL-代数的（∈,∈∨q）-模糊滤子和（∈,∈∨q）-模糊滤子进行了较为细致的研究,首先,在非交换剩余上首次引入了（α,β]-模糊滤子的概念,将非交换剩余格上的模糊滤子,（∈,∈∨q）-模糊滤子和（∈,∈∨q）-模糊滤子纳入到（α,β]-模糊滤子体系之中;其次,在非交换剩余上引入了生成（α,β]-模糊滤子的概念,给出了一般模糊子集生成（α,β]-模糊滤子的方法,指出了一个非交换剩余格上全体（α,β]-模糊滤子之集构成一个完备格,并证明了在α=0的情况下格的分配性成立.     

关于偏序集上的关联蕴涵代数

引入偏序集上的弱蕴涵代数的概念,证明它在满足条件(x→y)→y=(y→x)→x时构成M V代数,也构成弱R0代数.同时探讨了关联蕴涵代数与剩余格及BL代数之间的关系.     

Document concept lattice for text understanding and summarization

We argue that the quality of a summary can be evaluated based on how many concepts in the original document(s) that can be preserved after summarization. Here, a concept refers to an abstract or concrete entity or its action often expressed by diverse terms in text. Summary generation can thus be considered as an optimization problem of selecting a set of sentences with minimal answer loss. In this paper, we propose a document concept lattice that indexes the hierarchy of local topics tied to a set of frequent concepts and the corresponding sentences containing these topics. The local topics will specify the promising sub-spaces related to the selected concepts and sentences. Based on this lattice, the summary is an optimized selection of a set of distinct and salient local topics that lead to maximal coverage of concepts with the given number of sentences. Our summarizer based on the concept lattice has demonstrated competitive performance in Document Understanding Conference 2005 and 2006 evaluations as well as follow-on tests.     

几种一维原子链晶格振动特性比较研究

本文从结构、态密度和本征波函数三个方面系统研究了单原子周期链、双原子周期链、无序链、纳米链、Ｆｉｂｏｎａｃｃｉ准晶链和Ｔｈｕｅ－Ｍｏｒｓｅ链六种一维体系的晶格振动特性，给出并讨论了他们的区别和联系。