具有环形缺口圆杆在弯曲载荷下的裂断问题

以无量纲因子为ｆａ（ａ／ｂ）为表征参量，给出了具有环形缺口的圆杆缺口尖端附近的应力场；讨论了缺口尖端半径ρ，深度ｔ和张角α变化时的种种缺口形式；分析了缺口参数对无量纲因子ｆａ（ａ／ｂ）的影响，得到了以ｆａ（ａ／ｂ）为依据的安全设计，断裂设计准则。     

环形缺口拉伸圆杆的统一模型和断裂准则

对具有环形缺口的拉伸圆杆，以缺口尖端半径ρ，深度ｔ和张角α以及圆杆几何尺寸ａ和６为描述参量，将理想尖裂纹、钝裂纹和切口作为缺口来统一描述，给出了以ｆ＿α（ａ／ｂ）为依据的安全设计和断裂设计准则，从而使理想裂纹应力强度因子模型和切口应力集中模型得以衔接。     

功能梯度材料V型缺口根部裂纹场强特性分析

为研究功能梯度材料V型缺口根部裂纹尖端附近的应力场强特性,讨论了指数型梯度材料的裂纹场强特点.以双边V型缺口试件为研究对象,建立试件的有限元分析模型.基于分层法分析静态载荷和阶跃冲击载荷下功能梯度材料V型缺口根部裂纹尖端的应力场强.研究结果表明:静载荷下,缺口根部裂纹前沿中面裂尖等效应力、位移及应力强度因子随着梯度参数β的增大而增大;应力强度因子K随张开角α的增大而减小,且在0°~60°之间减小缓慢,而在60°~90°之间减小程度明显,而在大于90°时随张开角α迅速减小.在冲击阶跃载荷下随着梯度参数β的增大,其动态应力强度因子值减小.     

椭圆面积的求法

求椭圆x~2/a~2+y~2/b~2=1 (a>b)的面积。如图所示,作出椭圆的图形。以 O 为圆心 a 为半径作一圆 O,将 OA分成 n 等分,过第i-1、 i 点作垂线交椭圆和圆于 P′,P 和 Q′,Q。由圆的方程知 y_i′=(a~2-x_i~2) ~(1/2) ;由椭圆的方程知 y_i=b/a(a~2-x_i~2) ~(1/2) ,∴y_i/y_i′=b/a,即 y_i=(b/a)y_i′。     

微孔几何特征对密封端面动压润滑性能的影响

通过建立底面形状为矩形面、梯形面、抛物面和三角形面4种均匀分布的圆微孔密封端面理论模型,利用有限差分法求解流体动压润滑方程,获得了密封端面无量纲压力分布,并考察孔半径和深度对无量纲平均压力pav的影响。结果表明:不同底面形状微孔对密封端面动压性能的影响随微孔半径及深度均呈现先增大后减小的趋势,优化后的矩形面具有最佳的动压性能,其无量纲平均压力值达到1.39,相比于三角形面提高了8.59%,最优的微孔半径为0.17mm,与其它3种型面差别不大,但最优的微孔深度值最小。     

关于t-Euler优美数对的确定

设n为正整数,φ(n)是n的Eu ler函数,对于正整数a和b,如果存在正整数t使得φ(a)=b/t,φ(b)=a/t,则称(t,a,b)是一个t-Eu ler优美数对.用初等而简洁的方法讨论了t-Eu ler优美数对的存在性,并得到了全部的t-Eu ler优美数对只有(t,a,b)=(1,1,1),(2,2α,2α)及(3,2α.3β,2α.3β),其中α,β都是正整数.     

分数ID-[a,b]-因子临界图的最小度与独立数条件(英文)

对图G的每个独立集I,若G-I有分数[a,b]-因子,则G是分数ID-[a,b]-因子临界图.本文证明了若α(G)≤(4b(δ(G)-b+1))/((a+1)2+4b),则G是分数ID-[a,b]-因子临界图.     

金属材料不同缺口根半径拉伸试样中的应力应变分析

用有限元法计算了钢和铝合金不同缺口根半径拉伸试样的应力、应变分布及其随外加载荷的变化规律.研究结果表明,缺口前端的最大正应力σyy/σy、三向应力度σm/σ和等效塑性应变εp都随外加载荷P/Pgy的增加而增大,但在整体屈服之前(P/Pgy<1)和整体屈服之后(P/Pgy>1)的变化规律不同.当外加载荷P/Pgy一定时,随缺口根半径的减小,缺口前的σyy/σy、σm/σ和εp均增大,但在较大缺口根半径(R≥2mm)和较小缺口根半径(R<2mm)时的应力、应变分布及其随P/Pgy的变化规律有所不同.材料拉伸力学性能对缺口前端的应力、应变分布总体上影响不大.     

基于BB-递归核函数SVR算法的U型折弯件模型参数优化研究

影响U型折弯件回弹的因素众多，工件尺寸、力学性能、负载条件、材料各向异性等相互耦合，表现出高度复杂的非线性，从而导致回弹预测结果的不确定性。本研究以板料折弯件回弹后的张开角(α)为目标函数，构建一个递归核函数支持向量回归(SVR)模型，并部署到分支界限法(BB)中，从而筛选出维度为4的最优的特征变量参数子集，其决定系数(R²)为0.982 147,均方误差(MSE)为0.004 33,模型预测精度相对较高。算法优化得到的折弯件参数为：厚度(t)为12 mm,上模宽度(d)为90 mm,上模圆角半径(r)为9 mm,载荷速度(v)为10 mm/s。BB递归核函数SVR算法、有限元模拟和实际测量的α分别为16.3°、17.5°和18.2°,尽管有限元结果更接近于实际值，但是BB递归核函数SVR算法可以为有限元模拟提供筛选出的参数(t,d,r,v)的数据，以快速进行模拟并预测张开角α,并实现回弹补偿装置的高效设计。     

材料变形中应力三轴性和Lode参数分布演化的数值观测

应力三轴性T和Lode参数(θ)是影响材料韧性断裂的重要参数,凹纹平板和缺口平板两种试件由于其对于这两个参数有较好的控制能力,被用来观测T和(θ)在材料变形中的演化规律.对不同尺寸的试件进行了有限元数值模拟,结合等效塑性应变(ε)和三轴性T的分布和演化,参考双曲线断裂准则,判断可能发生初始断裂的区域并标示具有代表性的节点.对这些节点的T和(θ)随(ε)的变化曲线进行分析比较,得出结论:T和(θ)在缺口平板试件中比在凹纹平板试件中展现出更平稳的演化特点;凹纹平板中心由于其为平面应变状态,(θ)值为0;随着缺口平板的圆槽半径FNP-R增大,其应力三轴性T将减小,Lode参数(θ)将越小.     

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.