聚乙烯型尾形链构象统计 Monte Carlo模拟的理论模型

以聚乙烯型尾形链为例,采用不同于Metropolis原理的一种新理论模型,该模型根据链的实际键长,键角和θ条件下每一链段处于不同旋转异构态的条件概率生成样本链分子;并且论述了该模型的实现步骤、条件概率的计算及构象相关物理量统计平均值的计算公式。     

条件概率与刚性近似下高分子链非格子模型的Monte Carlo模拟

探讨了采用高分子链的实际键长、键角、旋转异构态和无扰链时的条件概率逐个链段地生成样本高分子链进行真实链和受限链分子构象统计研究的可能性.并就无扰链、尾形链、真实链的情况与完全计算法、Flory矩阵方法进行了比较.结果表明:在刚性近似下,使用无扰态时的条件概率生成样本高分子链的Monte Carlo模拟,其样本库能真实地重现平衡态时受限链和真实链的构象分布,适用于受限链和真实链的构象统计研究.     

条件概率与刚性近似下高分子链非格子模型的Monte Carlo模拟

探讨了采用高分子链的实际键长、键角、旋转异构态和无扰链时的条件概率逐个链段地生成样本高分子链进行真实链和受限链分子构象统计研究的可能性.并就无扰链、尾形链、真实链的情况与完全计算法、Flory矩阵方法进行了比较.结果表明:在刚性近似下,使用无扰态时的条件概率生成样本高分子链的Monte Carlo模拟,其样本库能真实地重现平衡态时受限链和真实链的构象分布,适用于受限链和真实链的构象统计研究.     

用^13C核磁共振测定高聚物分子量：PE分子量的测定

提出应用~(13)C核磁共振(NMR)方法测定聚合物分子链末端浓度来求数均分子量M_n的问题。具有不同分子量的聚乙烯(PE)在~(13)C-NMR谱上,主链亚甲碳原子,各种支化链结构以及接近链末端和末端的碳原子将显示出各自的不同强度的特征峰。考虑了影响~(13)C-NMR谱定量性的因素,通过谱强度计算出一系列经分级后PE各级分的数均分子量M_n,与GPC的测定结果基本一致,探讨了~(13)C谱测定M_n的可能性和准确性。     

星型共聚高分子构象的Monte-Carlo模拟

采用非格子Monte-Carlo模拟方法对星型共聚高分子的回转半径、均方回转半径、构象和能量等随时间的演化过程进行了模拟研究,并进一步分析讨论了分支数目、分支聚合度以及分支末端链单元间相互作用对星型共聚高分子驰豫过程及其聚集态结构的影响.结果表明,稳定状态下的星型聚合物可以呈现瓜型构象.所得结果可为星型共聚高分子性质的研究提供线索.     

随机环境中马氏链的特征数与禁止概率

利用马氏链的一般理论讨论了随机环境中马氏链的特征数和禁止概率的关系,给出了强常返状态特征数的分解公式,利用禁止概率的一般分解公式研究了分布矩的性质,丰富了现有文献中的随机环境中马氏链的相关结果。     

向量值鞅变换算子加权条件矩不等式及其应用

证明加权条件下Banach值鞅变换算子的极大函数、P阶均方函数条件矩不等式；作为应用，给出了鞅变换算子的极大函数，P阶均方函数的加权Ф型不等式，并且与Banach空间的一致凸性和一致光滑性联系起来。     

用邻接矩阵法判断运动链同构

针对机构运动链的同构判断问题进行了讨论 ,提出了一种运动链同构判断的邻接矩阵法 ,并举例说明了此方法的具体运用 ,从而证明了采用邻接矩阵法 ,可准确、高效地判断运动链同构 .     

聚乙烯-醋酸乙烯酯接枝聚乙二醇共聚物的合成及结构表征

研究了以聚乙烯—醋酸乙烯酯为主链化合物，利用威廉森(Williamson)合成法，在主链上接枝聚乙二醇，合成了一类新型的大分子表面改性剂。利用核磁共振氧谱和红外光谱，表征了聚乙烯-醋酸乙烯酸及合成的接枝共聚物的化学结构，讨论了实验条件对接枝产物大分子链结构的影响。     

EVOH基单离子聚合物的结构与性能研究

以聚乙烯乙烯醇为主链,利用其羟基的反应活性,通过Williamson反应将短链的聚乙二醇结构引入聚乙烯-乙烯醇主链上,并通过磺酸丙内酯开环反应对其侧链进行磺化,制备出一种主链为疏水的聚乙烯链段,侧链为(—CH2CH2O—)重复单元,且侧链末端为磺酸氢的梳形单离子聚合物.采用红外光谱分析法证实了氯代缩乙二醇被接枝到EVOH主链上以及—SO3—基团的存在;采用示差扫描量热法(DSC)和热重分析法(TG)对其热学性能进行了表征.DSC分析表明随着侧链长度的增加,主链和侧链的玻璃化转变温度均向低温方向移动;而TG分析显示EVOH-g-nSPEG的热失重曲线有两个失重台阶,并且在第一个失重台阶出现之前还出现了缔合水的失重,该离聚物的起始的热分解温度仍高于200℃.     

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

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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