对Bezier曲面和B样条曲面之间过渡曲面构造问题的研究

提出了张量积Bezier曲面和B样条曲面的过渡曲面的算法,并且对于双三次张量积B样条曲面和双三次张量积Bezier曲面给出了计算实例,验证了算法的可行性。     

厚钣展开及成形研究—可展曲面的等距曲面及等距曲面族

用画法几何方法研究了几种可展曲面的“等距曲面”,重点是椭圆锥面的等距曲面,结论是：椭圆锥面的等距曲面是切线曲面。指出了一种“干涉现象”,它是与钣材展开成形有关的重要问题,提出了“等距曲面族”概念,并用其分析了一般切线曲面及“变位中间曲面”的等距曲面。     

用有理Bezier曲面生成G^1过渡曲面

描述了用有理Ｂｅｚｉｅｒ曲面生成过渡曲面的方法，提出一个实用的充分条件，推导出沿两相邻有理Ｂｅｚｉｅｒ曲面片Ｇ＾１连续的显式顶点关系式，讨论了等阶曲面拼接，并给出本算法的实验结果。     

隐式与参数曲面间的混合曲面设计方法

针对管道曲面设计中如何构造过渡曲面问题,提出了一种隐式曲面与参数曲面间的混合曲面设计方法.对于给定的隐式曲面与参数曲面,存在着等距曲面族,每一对相关的曲面均产生交线,混合曲面即为一系列相关曲面交线的集合.采用该方法能更加方便有效地调整混合曲面的范围与形状,并能满足工程要求.文章还证明了混合曲面与隐式曲面及参数曲面之间为G1-连续.     

曲面零件立体造型中的过渡曲面

过渡曲面在计算机曲面立体造中往往被忽略，而在曲面集体所有制 实际加工中不中避免要涉及到过渡曲面的问题，在讨论曲面之间形成的过渡曲面的性质的基础上，提出在立体造型中利用包络实现过渡曲面的步骤和计算方法，并给出了实例，结果证明这种方法是可行的。     

曲面积分与曲面形状无关性

分析了曲面积分与曲面形状无关的第三种条件及其场论解释与应用。     

切线曲面的斜等距曲面及其性质

斜等距曲面原理在机械加工中有着广泛的应用,因此,对斜等距曲面的性质进行研究具有实际意义,我们已经证明了锥面、柱面的斜等距曲面的一些性质,将证明切线曲面的斜等距曲面的一些性质,并分析了切线曲面上各点邻近处点的形状,由于在实际应用中,我们需要知道根据模型加工出的曲面能否达到要加工的曲面的形状要求,因此对曲面上各点形状的分析对实际应用具有指导作用。     

Coons曲面在汽车前照灯多曲面反射镜设计中的应用

采用Coons曲面造型可以满足前照灯反射镜固定边界条件下曲面变形的需求.为使Coons曲面的形状容易调整,采用Bernstein基函数来构造跨界导矢,这样曲面4条边界上的跨界导矢可以分别逼近4个矢量,只需给定4个矢量就可以控制Coons曲面的形状.为进一步简化曲面形状调整方法,并使控制量与曲面的空间位置无关,采用3个标量作为控制量,分别控制曲面凹陷的深浅和偏向.这3个标量为前述4个跨界导矢逼近矢量和曲面4个角点位置矢量的函数,调整3个标量就能修改曲面跨界切矢的模长和方向组合,从而改变曲面的形状.仅用3个标量的Coons曲面变形方法实现了固定边界条件下曲面前照灯反射镜曲面的快速变型.     

自由曲面的求交及其过渡曲面的生成

现有的为平面或二次曲面产生过渡曲面的算法均不能用于自由曲面。本文用双三次 Ｂｅｚｉｅｒ曲面片来表示自由曲面，用基于分割的递归算法求出自由曲面之间的交线，在这 基础上，提出并实现了围绕交线产生过渡曲面的算法，过渡曲面本身也是用双三次Ｂｅｚｉｅｒ 曲面来表示的。所述算法已在ＤＯＲＡＤＯ计算机上用ＣＥＤＡＲ语言实现，并作了实例计 算。     

旋转曲面上的第二型曲面积分的计算公式

给出旋转曲面上的第二型曲面积分的一个计算公式,由该公式可将此类型曲面上的曲面积分转化为参数的二重积分.     

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.     

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.     

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).     

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.