材料非线性对沥青道面结构力学响应的影响

借助三维有限元软件,建立半刚性基层沥青道面和柔性基层沥青道面结构模型,分析了B737,B767,B777飞机荷载作用下,土基材料非线性、粒料材料非线性、土基和粒料材料均为非线性三种情况时对道面结构力学响应的影响.结果表明,在三类不同起落架荷载作用下,随着轮载的增加,材料非线性对道面结构力学响应的影响逐渐增加,土基非线性对两种道面结构的力学响应影响不明显.半刚性基层沥青道面结构,粒料非线性与土基和粒料均为非线性时对道面表面弯沉和土基顶面竖向压应变影响不显著,但对沥青面层底部的拉应变和半刚性基层底部的拉应力影响较为明显.柔性基层沥青道面结构,粒料非线性对表面弯沉的影响不显著,但对土基顶面竖向压应变影响较大,土基和粒料均为非线性时对沥青面层底部拉应变的影响明显.     

圆形均布荷载下铺面结构层应力的水平向分布规律

基于弹性层状理论,研究圆形均布荷载作用下铺面结构层底弯拉应力,土基顶面压应力水平向分布规律.考察了铺面结构层层底径向应力系数φr、切向应力系数φθ和土基顶面压应力系数φz随距荷载圆中心点水平距离r的增加而衰减的规律,分析总结了铺面结构参数对上述3个应力系数的影响,给出了3个应力系数与铺面结构参数和距荷载圆中点水平距离r之间的回归关系式.     

路面结构的土基应力应变近似计算

从研究双圆荷载作用于双层路面结构时土基应力、应变入手,分析了不同轴型、不同荷位和多层结构条件下,土基不同深度的压应力、压应变的变化规律,通过引入旁侧轮系数ξ、邻轴系数ζ和荷位系数φ并归纳它们的近似回归式,建立了具有普适性和较高精度的路面结构下土基的竖向最大压应力和压应变的近似计算式.     

混合式基层沥青路面动态响应测试结果特征分析

依托遂广高速公路沥青路面动态响应试验段,进行了系统采集数据的有效性分析,并基于沥青混合料、级配碎石和土体经典力学理论,评价了单后轴和双后轴货车作用下路面结构内部水平应变和竖向力学指标时程曲线的力学基本特征.研究结果表明:移动荷载作用下,沥青层层底纵向应变先后出现压—拉—压循环交变应变,沥青层层底横向应变表现为压—拉两个过程,沥青层层底纵向和横向应变应分别采用应变幅值和拉应变峰值作为路面在荷载作用下实际应变变化值,且沥青层层底横向应变测值受轮胎作用位置影响较大;同时,荷载驶离传感器后,沥青层层底水平应变响应存在明显残余应变,而土基顶面竖向压应力并不存在残余应力;双后轴货车后轴对应的路基顶面竖向压应力和沥青层层底横向应变叠加效应显著高于其他指标.现场试验证实,路面结构动态计算分析中,路基可简化为弹性体,沥青混合料材料应考虑其黏弹性特征,级配碎石过渡层应考虑其永久变形特性.     

沥青路面结构层弯拉应力与应变的近似计算

研究了各种条件下沥青路面结构弯拉应力和应变规律,引入曲面系数修正竖向压应力和剪应力的影响,引入面层弯曲中性轴下移量参数修正层间光滑与连续之间的差异,引入面层与基层弯矩分配系数反映面层、基层弯曲曲率不同的影响;对于模量不均匀面层,提出了弯曲刚度等效原则换算式;最后,讨论了各种条件下的沥青面层层底弯拉应变、半刚性或刚性基层层底弯拉应力的计算精度,其误差均不超过5%.     

复合式机场道面荷载应力

为了分析复合式机场道面的荷载应力,建立了9块板的复合式机场道面三维有限元模型,以B777-200飞机荷载为计算荷载,选取沥青混凝土层底拉应力、沥青混凝土剪应力、水泥混凝土板底拉应力为考察指标,分析复合式机场道面的最不利荷位;利用正交设计分析结构参数对荷载应力影响的显著性,指导复合式机场道面结构设计。研究表明:水泥混凝土板底拉应力应该作为复合式机场道面荷载应力分析的关键指标,复合式机场道面基于多板分析的最不利荷位位于三轴双轮荷载的中轴荷载与板边中点相切处;增加水泥混凝土板模量对板底拉应力负面影响显著,增强土基模量可以明显减小水泥混凝土板底拉应力和沥青混凝土层底拉应力;复合式机场道面结构设计过程中,必须重视土基处理,提高土基强度;不能过分强调增加水泥混凝土板的模量,应该综合考虑其弯拉强度,合理选择水泥混凝土配合比。     

横观各向同性的半刚性基层沥青路面结构

为了分析土基和沥青面层材料的横观各向同性特性对半刚性基层沥青路面结构的影响,基于建立的横观各向同性沥青路面设计理论,运用编制的基于该理论解的路面结构分析程序ANISOLAYER,利用沥青面层及土基横观各向同性特性,对半刚性基层沥青路表(路表面)弯沉进行了研究。同时运用ANISOLAYER程序分析了在不同厚度沥青面层及不同半刚性基层弹性模量情况下,土基横观各向同性特性对路面结构关键性设计指标的影响(路表弯沉、半刚性基层底部拉应力及路基顶部压应变,沥青层底应变为压应变或较小的拉应变,故未考虑)。研究结果表明:无论是面层还是土基,其各向异性度(水平弹性模量与垂直弹性模量之比)对路表弯沉的影响曲线变化趋势是一致的;随着土基水平模量的增加,延长了路面的寿命;随着半刚性基层弹性模量的增大,土基水平模量的变化对路表弯沉及基层底部拉应力的敏感性将降低,对路基顶部压应变的敏感性更加显著,但其绝对值较小。     

考虑温度变化的柔性基层沥青路面结构力学分析

采用BISAR 3.0程序计算行车荷载在不同温度下两种柔性基层沥青路面结构的力学行为.荷载采用双圆均布垂直荷载,且为标准轴载BZZ-100,轮载P=25 k N,轮压p=0.7 MPa,半径d=0.106 5 m,层间接触状态为完全连续.通过计算结果分析比较路表弯沉、面层层底拉应力与剪应力以及基层层底拉应力与剪应力随温度变化规律情况,探索最优柔性路面结构形式.     

均布荷载下横观各向同性沥青路面力学行为分析

文章采用广义Maxwell模型描述沥青混合料面层的黏弹性,考虑碎石基层和土基的横观各向同性特征对路面结构力学行为的影响。在弹性假设条件下引入材料水平模量与竖直模量比值为变量,运用有限元方法建立路面结构三维有限元模型;通过模拟计算,对比分析均布荷载作用下碎石基层和土基各向同性与横观各向同性对各结构层应力和应变及路表弯沉值的影响,并对沥青路面服务寿命进行预估分析。分析结果表明:均布荷载作用下碎石基层的横观各向同性特征对路表弯沉影响较小,而土基横观各向同性特征对路表弯沉影响较大;路基顶部压应变受碎石基层及土基横观各向同性特征影响较大,而面层层底拉应变和基层底拉应力仅受碎石基层横观各向同性特征影响较大;沥青路面服务寿命受碎石基层横观各向同性特征影响较大,且在碎石基层各向同性时服务寿命最长。因此,在路面结构设计中应适当考虑基层和路基材料的横观各向同性特征。     

考虑飞机制动力的机场沥青道面力学响应分析

针对飞机在降落制动过程中所产生的制动力对道面结构产生显著影响,并借助ABAQUS三维有限元软件,建立了柔性道面结构和半刚性道面结构有限元模型,分析在常用的民用飞机和新一代大型飞机荷载作用下,考虑水平制动力作用时对道面结构产生的力学响应.同时分析了以B777-300ER、A380-800为代表的新一代大型飞机,在考虑不同的水平制动力、土基模量、面-基层接触状况条件下时对道面力学响应的影响.计算结果表明:考虑制动力后,面层最大拉应力出现在道面表面;水平制动力超过0.5倍单轮荷载后,使得面层内部的拉应力急剧增大;层间的不良接触对半刚性道面结构影响较大,当面-基层的接触系数大于0.5后,对面层内部的最大剪应力和面层底部的拉应力影响不显著.     

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.