受力状态下混凝土试件碳化试验研究

为了研究混凝土桥梁的碳化规律,采用加速碳化试验方法,进行了碳化环境下受力状态混凝土试件的耐久性试验,分析了碳化混凝土的退化机理和规律.结果表明:拉、压应力分别加快和减缓了混凝土碳化的速率,且应力变化越大,碳化速率的改变就越大;桥梁常用C50强度混凝土的碳化深度远小于低强度混凝土,但C50强度混凝土受拉时的相对碳化深度大于低强度混凝土.根据试验结果修正了现有混凝土碳化深度预测模型中的工作应力影响系数.当混凝土桥梁的裂缝宽度满足规范要求时,裂缝对混凝土碳化的影响很小;预应力混凝土桥梁的耐久性能优于钢筋混凝土桥梁.     

裂缝对预应力混凝土结构耐久性影响的试验研究

通过预应力混凝土裂缝状态试件 (共两组 ,每组 1 0个工况 )在碳化、氯离子侵蚀环境下的试验研究 ,提出了预应力混凝土裂缝状态试件的制作及试验方法 ;探讨了裂缝对预应力混凝土耐久性影响的机理及成因 ;着重研究了不同水灰比、不同裂缝宽度、不同保护层厚度等因素对预应力混凝土裂缝状态试件的耐久性影响程度及规律 ,所得结论对预应力结构耐久性设计与评估具有一定的参考价值     

现代预应力结构耐久性(碳化)数值计算

基于应力状态下构件快速碳化试验,开展应力状态下混凝土碳化深度的计算机仿真,采用Matlab神经网络工具箱对应力状态下混凝土碳化深度进行训练、仿真和预测.提出采用分项系数γc来反映结构可靠指标的结构耐久性设计方法,给出一定设计使用年限、一定可靠指标下结构耐久性设计时保护层厚度的计算表达式,并对算例中各框架预应力筋的保护层厚度进行计算.结果表明,建立的神经网络模型有较高的预测与仿真能力;提出的设计方法简单、实用,可以作为结构设计和耐久性验算复核的手段.     

环保型裂缝修复材料对混凝土抗碳化性能的影响

混凝土碳化会导致混凝土中的钢筋脱钝,从而引起钢筋锈蚀,最终影响到混凝土结构的耐久性。该文对环保型裂缝修复材料处理试件进行了抗碳化性能试验。试验结果表明：相比普通混凝土试件,ECRM处理后试件的碳化深度减小,且混凝土碳化速率提前出现下降趋势,ECRM能有效增强混凝土的抗碳化能力。     

压应力下混凝土结构碳化试验研究

进行了在碳化箱中加速腐蚀碳化环境状态下的混凝土结构碳化试验,试件为直接受压的应力状态,阐述了试验中采用休哈特控制图对碳化深度数据进行采集和动态统计控制原理,建立了压应力状态下碳化深度动态统计控制模型。试验结果表明,该方法能有效的对钢筋混凝土结构在压应力工作状态下的碳化深度进行动态监测、分析、评价和控制,避免对结构的耐久性及稳定性产生不利影响,造成安全隐患,从而确保在承载环境中钢筋混凝土结构的质量和安全。     

预应力结构设计使用寿命模型

预应力混凝土结构的耐久性问题和普通的耐久性有相似之处，但更有其独特性，文中阐述了预应力结构中力筋应力腐蚀断裂牧场生，分析了预应力结构与普通混凝土结构使用寿命的不同之处，然后在碳化作用机理的基础上，利用碳化深度计算公式提出了碳化作用环境下的预应力结构设计使用寿命模型。     

混凝土裂缝宽度和深度对裂缝表面碳化的影响

为研究混凝土裂缝宽度和深度对裂缝表面混凝土碳化的影响,制作了带裂缝的钢筋混凝土试件并进行了碳化试验研究。研究采用碳化时未开裂的试件、裂缝近似贯通的试件、裂缝未贯通的试件的横断面,其中裂缝近似贯通试件、裂缝未贯通试件的横断面即为裂缝开裂断面。对于裂缝近似贯通和未贯通的试件,通过对比裂缝的宽度、深度和裂缝表面混凝土的碳化情况,并与未开裂试件断面混凝土碳化情况进行对比分析。研究结果表明,裂缝宽度对于混凝土裂缝表面的碳化几乎没有影响,表面碳化主要与裂缝深度有关。本文对混凝土开裂部位的耐久性研究仅以裂缝表面宽度为依据进行的方法提出了不同看法,建议将混凝土裂缝宽度和深度列为同等重要的研究依据。     

预应力结构设计使用寿命模型

预应力混凝土结构的耐久性问题和普通混凝土的耐久性有相似之处 ,但更有其独特性 文中阐述了预应力结构中力筋应力腐蚀断裂特征 ,分析了预应力结构与普通混凝土结构使用寿命的不同之处 ,然后在碳化作用机理的基础上 ,利用碳化深度计算公式提出了碳化作用环境下的预应力结构设计使用寿命模型     

海工预应力混凝土氯离子侵蚀模型及耐久性

总结分析了国内外有关混凝土中氯离子侵入模型的研究概况，针对海工预应力混凝土结构，讨论了影响氯离子侵入预应力混凝土的各种因素．考虑混凝土与氯离子间的结合能力，建立了预应力混凝土氯离子侵入数学模型．以混凝土保护层厚度、氯离子扩散速度以及表面氯离子浓度为主要参数，运用可靠度理论，建立了海工预应力混凝土结构耐久性可靠度分析模型．分析结果表明：应力状态下。混凝土的氯离子有效扩散系数是变化的，其中混凝土的拉应力会加快氯离子的扩散，而压应力则相反；同时从耐久性分析中可知，混凝土保护层厚度对氯离子侵蚀下的PC结构耐久性影响最大，表面氯离子浓度及氯离子扩散速度次之．     

应力状态对RC梁混凝土碳化损伤及承载力的影响

为研究应力状态对RC梁混凝土碳化损伤及承载力的影响规律，制作了7根RC梁进行加速碳化环境与荷载耦合作用试验研究。将RC梁放入环境箱中，进行三点弯曲静力持荷条件下的7 d、14 d、28 d加速碳化试验，得到不同持荷时间下的RC梁受拉、受压不同区域的混凝土碳化深度，进一步开展加速碳化作用、加速碳化与荷载耦合作用后的RC梁三点弯曲试验，探讨应力状态时碳化深度对RC梁极限承载力的影响机制。结果表明：通过对RC梁受压、受拉区的混凝土碳化深度分析，发现压应力状态会抑制碳化反应的进行，而拉应力状态会促进碳化反应的进行，28 d后受拉区混凝土碳化深度比受压区增加了34.7%。混凝土碳化损伤导致抗压强度降低、钢筋锈蚀影响了试验梁的极限承载力，加速碳化作用28 d后RC梁的极限承载力下降了10.7%，加速碳化与荷载耦合作用28 d后RC梁的极限承载力下降了14.9%。     

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.