不同库水模型对高拱坝动力特性的影响

给出了3种模型及不同情况下高拱坝动力特性的数值求解方案,并结合实际工程分析了不同库水模型对高拱坝动力特性所产生的影响.计算和分析结果表明:不同库水模型对坝体的自振频率、振型参与系数和振型等动力特性的影响程度相差较大;可压缩库水模型最能真实地反映库水的特性和库水对坝体动力特性的影响,可采用可压缩库水模型来求解高拱坝的动力特性.     

解非线性方程的一种新的三步六阶迭代格式

Newton迭代法是求解非线性方程的重要方法之一,其收敛阶是二阶,在迭代过程中需要计算一个函数值和一个导数值,因此Newton迭代法的效率指数为1.414 2。基于Newton迭代法结合两步迭代格式构造了一种新的三步迭代格式,通过理论证明其收敛阶是六阶,在迭代过程中每次均需要计算2个函数值和2个导数值,则该三步迭代格式的效率指数为1.565 1,最后数值实验结果也验证了该方法的有效性和可行性。     

基于状态空间理论的工程结构地震时程响应分析

基于状态空间理论分析与计算工程结构地震时程响应问题,根据结构动力学方程,引入结构系统的状态变量,建立结构地震时程响应分析的状态方程,并给出非齐次状态方程的解.为了求解矩阵指数函数,着重介绍了凯莱-哈密尔顿(Kaley-Hamilton)法、状态空间迭代法和精细积分法.对结构动力时程响应问题按这三种解法分别建立了计算格式,并编制相应计算程序.最后,给出若干数值算例,其计算结果表明,状态空间法分析计算结构动力时程响应,其精度好,效率高,是一种非常有效的方法.     

基于TDMA的多孔介质热湿耦合模型求解与算法优化

为了提高多孔介质热湿耦合模型的求解效率,采用三对角矩阵求解法(TDMA)对模型进行求解,并将该算法和迭代法进行对比分析.对TDMA计算误差与时间步长之间进行了敏感性分析,基于敏感性分析结果提出了一种变时间步长的TDMA优化算法.数值计算结果表明:对于变物性参数问题,随着时间步长的增加,TDMA计算精度将会下降,而迭代法精度保持不变;对于纤维素绝热材料,当连续2个时间步长内相对湿度变化小于0.24％且温度变化小于0.1℃时,时间步长取值对TDMA计算精度的影响可以忽略;相比于TDMA,变时间步长TDMA算法不受时间步长取值影响,精度更高;相比于迭代法,变时间步长TDMA算法具有相同的计算精度,但用时更短,计算用时可减小67％.     

基于有限差分离散的模方法定价美式债券期权

针对美式债券期权定价模型的数值解法, 构造全隐式的有限差分格式, 并给出格式的稳定性证明. 采用模系矩阵分裂迭代法求解离散得到的线性互补问题, 并与投影超松弛迭代法进行比较. 数值实验验证了新方法的有效性和稳健性.     

空间结构-地基动力相互作用数值分析时域算法研究

对于大型结构地震响应分析,结构-无限地基耦合系统动力分析的数值实现,往往由于有限元网格过多,以及地基无限域时域计算模型中存在的复杂卷积运算,严重限制了求解规模.为解决此问题,提出了基于阻尼溶剂抽取法的三维结构-地基相互作用分析的分区时域逐步求解模型.并针对三维大规模工程问题的数值求解,在积分算法及矩阵存储格式等方面,结合阻尼溶剂抽取法的特点进行了详细的探讨,以推进动力相互作用时域数值分析的实用化.以三维全空间球形空腔动力变形及大岗山拱坝的地震响应分析为例,针对上述数值实现算法进行了具体验证,并就不同的地基弹模及地震波输入方式对坝体响应的影响进行了探讨.计算结果表明,地基辐射阻尼以及河谷散射效应对结构的动力响应有很大影响,而该模型表现出了良好的精度和计算效率.     

基于投影法的三维流场数值求解方法

本文利用投影法和浸入边界法使用的固定笛卡尔网格技术,三维泊松方程(poisson equation)采用有限七点差分格式离散,结合迭代法和直接法将三维的数值求解问题简化为二维问题,然后利用二维的直接数值解法进行快速的迭代求解.采用VC++编写数值计算代码,通过三维数值算例验证了三维压力Poisson方程求解数值方法的有...     

基于牛顿法的美式期权最优实施边界的数值模拟

美式看跌期权最优实施边界具有单调非减和凸性质,为寻找符合性质的数值解法,本文对非线性最优实施边界问题提出了牛顿迭代格式。通过数值试验分析得出牛顿迭代法下复合梯形格式的图形符合最优实施边界性质,并与不动点迭代法下的复合梯形格式求解的最优实施边界进行了比较,得到两种方法求解的最优实施边界数值解误差非常小。     

一种高效的求解非线性方程的史蒂芬森型迭代法

首先,针对非线性方程求根问题,提出一种最优4阶收敛的无记忆史蒂芬森型方法.在迭代过程中该新方法不需要计算任何导数,仅需计算3个函数值就达到了4阶收敛,该方法的计算效率为1. 587;其次,利用加速参数得到该无记忆迭代法的有记忆迭代格式,进一步提高了收敛阶;最后,将无记忆迭代法扩展到Banach空间,用于求解非线性方程组,并且数值实验结果验证了方法的有效性.     

结构地震反应DQ解法的两种数值格式

通过对时间计算域的离散化将结构地震时程分析问题转化为一系列初值问题的求解,建立了一种基于DQ原理的结构地震反应高精度数值分析方法.为了使DQ原理能够应用于任意变化的地震地面加速度激励下的结构动力分析问题,提出了两种数值方案———单时步格式和多时步格式.单时步格式要求假定时步内地面加速度的分布模式,并且需要对时步进行网格剖分;多时步格式直接利用地面加速度的离散信息构造数值格式,一次运算可获得多个时刻的反应值.数值试验表明:两种数值格式均可以获得较高的数值精度.对于单时步格式,可以通过采用较大步距的方式降低结构动力分析的计算工作量;对于多时步格式,可以通过时步数量的合理选择达到提高计算效率的目的.     

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…     

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。     

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

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.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.