论弹性力学广义变分原理的临界变分现象

应用拉氏乘子法消除Ｈｅｌｌｉｎｇｅｒ－Ｒｅｉｓｓｎｅｒ变分原理的约束关系时,在识别拉氏乘子的过程中,会出现拉氏乘子为零的现象,这种现象称为临界变分现象,本文提出了一些新的观点来解释这种现象。     

流体力学中的临界变分现象及其消除方法

通过一个具体例子,阐述了流体力学中存在的各种临界主分现象,并指出临界变分是拉氏乘子的固有特性。详细综述了消除临界变分的各种方法：刘高联预处理拉氏乘子法、钱伟长高阶拉氏乘子法及作者提出的半反推法。     

无小参数非线性振动方程的近似方法

本文提出了一种求解非线性方程的迭代算法 ,它不依赖于小参数 ,是先给方程一个带待定函数的试函数作为初始近似解 ,然后用拉氏乘子法构造一个迭代公式 (校正泛函 ) .试函数中的待定函数可用变分直接方法确定 ,而校正泛函中的拉氏乘子可用变分理论最佳确定 .应用这种方法不会出现长期项 ,其结果表明这种新方法是比较有效的 .     

求解摄动问题的一种新方法

本文提出了求解摄动问题的一种新方法－变分迭代算法,这种方法不按小参数展开,而是先给出一个近似解,然扣用拉氏乘子法校正其近似解,而拉氏乘子可用分变分理论最佳识别。     

基于Chandrasekharaiah广义线性理论的热压电力学的耦合广义变分原理

系统推导了热压电力学的变分原理。若应用传统的拉氏乘子法,由于会出现临界变分现象,不能得到本文的结果。本文指出临界变分是拉氏乘子的固有特性,半反推法是克服临界变分的有效途径之一。应用半反推法,根据Ｃｈａｎｄｒａｓｅｋｈａｒａｉａｈ关于压电材料的广义线性弹性理论,直接从控制方程及边初值条件,得到了经典意义上的一个耦合广义变分原理。本文的理论将给有限元方法、无单元方法及一些变分直接方法（如Ｒｉｔｚ法,Ｔ     

关于拉氏乘子法的细节及其作为变分原理的约束判据的可能性

本文就待定的拉氏乘子法和已识别的拉氏乘子法的区别进行了讨论,对现存的两种经验的拉氏乘子的识别方法进行了归纳,提出了识别的唯一性问题和识别的唯一性前提,最后对拉氏乘子法作为弹性力学变分原理是否存在约束条件的判据的可能性进行了讨论。     

双混合乘子法和动力学双混合广义变分原理

双混合拉氏乘子法是动力学问题所特有的。动力学问题所特有的两种约束条件——初始条件和终了条件,都可以用该文提出的双混合拉氏乘子法来放松。该文用双混合拉氏乘子法,建立了大变形非线性弹性理论的动力学双混合广义变分原理,这将给位移允许函数的设计和有限元计算带来方便。     

论弹性力学广义变分原理的临界变分状态

本文集中研究弹性力学变分原理中的临界变分状态,指出它的三种表现,并提出一个带预处理的修正拉氏乘子法来排除之。文中用它成功地导出了胡海昌－鹫津广义变分原理（简记作“Ｈ－Ｗ原理”）和由Ｈｅｌｌｉｎｇｅｒ－Ｒｅｉｓｓｎｅｒ亚广义变分原理（简记作“Ｈ－Ｒ”原理）广而得到的另二条广义变分原理,于是,拉氏乘子法的潜力得以更充分发挥,适用范围得以拓广。     

带有Lagrange乘子的变分及其离散差分

对于完整约束的力学系统,不直接消去不独立坐标,而是在作用量中引人Lagrange乘子,本文介绍了带Lagrange有乘子的拉氏和哈氏形式的变分原理,以及介绍带有Lagrange乘子的差分系统的离散变分方法和其差分离散变分方法,并且把所得结果与传统形式(即消去不独立坐标)的结果进行比较.     

建立广义变分原理的一种统一方法

在计算力学的发展中,各种广义变分原理的建立是计算力学发展的一个基础。作者在一篇还未发表的论文中,在钱伟长教授近期提出来的高阶拉氏乘子法的基础上,发展和推广了一种消除多个约束条件的高阶拉氏乘子法。本文进一步应用作者提出的这个方法,并作某些补充以便为建立各种一般形式的广义变分原理提供一个更加一般化的统一方法。为了说明本文方法,本文从最小位能原理出发得到了一个新的三变量无约束广义变分原理,从而证明本文所建议的方法有效性。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

<正>~~     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to