循环压制对喷射沉积7075/SiCp致密化的影响

采用循环压制工艺对多层喷射沉积大尺寸7075/SiCp复合材料(高度H>140mm)进行了致密化加工.研究了循环压制工艺对复合材料沉积坯和挤压坯密度及显微组织的影响规律,测试了复合材料的力学性能.结果表明,循环压制过程中在大的静水压力和剪切应力的共同作用下,复合材料中大部分孔洞逐渐被拉长闭合,致密化效果良好.沉积坯多次循环压制后,SiC颗粒取向平行于基体金属流动方向.挤压坯二道次压制后SiC颗粒破碎明显,分布得到改善,强度可以达到600 MPa以上.     

7090/SiCP轧制板材的显微组织和力学性能

利用喷射共沉积工艺制备了7090/SiCP复合材料坯,通过力学性能测试、SEM形貌分析、TEM分析等手段对热处理后的复合材料轧制板材的力学性能以及微观组织进行了研究.轧制薄板中SiC颗粒沿轧制方向均匀分布.轧制变形量的增加导致颗粒破碎的程度加剧,且形状更为规整.对复合材料轧制态薄板进行470 ℃/1 h 490 ℃/1 h双级固溶 120 ℃/28 h时效后强度可达到675 MPa.实验结果表明,轧制板中SiC颗粒的断裂和界面脱粘为复合材料薄板的主要断裂机制.     

SiCp/FVS1012薄板微观结构及高温性能的研究

利用OM,XRD和TEM等方法研究了喷射沉积-挤压-轧制SiC颗粒增强FVS1012(SiCP/FVS1012)薄板的微观结构以及退火对该复合材料硬度的影响.结果表明,本工艺制备的SiCP/FVS1012薄板具有优异的高温力学性能,在315℃时,σb=308 MPa,σ0.2=290 MPa,δ=5.69%;在415℃时,σb=201 MPa,σ0.2=182 MPa,δ=3.65%.微观组织分析表明:类球状细小弥散的Al12(Fe,V)3Si相的生成是该复合材料具有优异高温力学性能的主要原因,此外,SiC颗粒的加入对提高该复合材料的高温力学性能也有重要作用.     

往复镦挤对SiC_p/2024铝基复合材料组织性能的影响

采用室温拉伸测试、扫描电镜及透射电镜等手段研究了往复镦挤变形工艺对SiCp/2024铝基复合材料显微组织和力学性能的影响.结果表明,SiCp/2024铝基复合材料经过往复墩挤后,基体组织出现细化,SiC颗粒发生破碎,基体中SiC颗粒由团聚变得分布均匀;在交替剪切变形作用下,基体中的位错发生重组和湮灭,形成细小的亚晶;相对于挤压态,经过4道次变形后,复合材料抗拉强度由271 MPa提高到378 MPa,屈服强度由203MPa提高到260 MPa;经过往复镦挤变形后,拉伸断口以界面脱粘和颗粒断裂方式为主.     

反复塑性变形法制备SiCp/AZ31镁基复合材料

采用反复塑性变形（RPW）技术,再结合挤压工艺可制备出SiC颗粒增强AZ31镁基复合材料,RPW次数和SiC颗粒的加入量对SiCP/AZ31镁基复合材料显微组织和性能的影响也得到了研究。研究结果表明,随着RPW次数的增加,SiC颗粒逐渐被细化并最终在基体中弥散分布,在RPW为300次时的力学性能最佳;随着SiC颗粒加入量的增加,其室温抗拉强度和硬度都逐渐增大,在SiC颗粒体积分数为6%时达到最大值,分别为371MPa和112。     

超显微硬度法研究SiC_P/6066铝基复合材料微区硬度变化

对喷射共沉积后经挤压的SiCP/ 6 0 6 6铝基复合材料 ,通过采用超显微硬度法测量了其微区的硬度变化 ,观察其显微组织 .结果表明 :在SiC颗粒分布密集处 ,基体超显微硬度值HV为 143.2 ,而在SiC颗粒分布稀疏处 ,硬度值HV为 10 7.2 ,二者之间有明显差距 .这是由于分布密集的增强体SiCP 周围局部基体应力场应力集中更剧烈而使超显微硬度值提高 .此外还测量了由于热收缩应力引起SiCP 周围应力场的变化而导致的微区硬度的变化 .在SiC颗粒附近基体硬度值较高 ,HV达 10 5 .8,而离SiC粒子距离大于其颗粒半径的基体中 ,硬度较低 ,HV约为 81.7.SiCP 造成基体中应力场的叠加可使基体中出现张应力区 .此外 ,通过测量复合材料超显微硬度值的变化 ,分析了残余应力对喷射共沉积复合材料微区一些力学性能的影响     

新型喷射沉积多孔材料致密化工艺

该文对三种新型喷射沉积铝合金多孔材料的致密化工艺（楔形压制工艺、陶瓷颗粒包覆轧制工艺及外框限制轧制工艺）进行了研究。实验结果表明：三种新型致密化工艺均可以有效提高喷射沉积材料的加工性能。尤其是使用楔形压制工艺可以用来对传统加工工艺无法进行后续加工的大尺寸喷射沉积材料得到有效的致密化。     

增强体颗粒尺寸对SiC_p/2124Al复合材料变形行为的影响

利用常规静态单向拉伸技术,研究了SiC颗粒尺寸对用粉末冶金工艺制得的SiC颗粒增强2124Al合金(SiCp/2124Al)变形行为和力学性能的影响.在体积比为20%的条件下,SiC颗粒尺寸在0.2～48μm的范围内变化,无论室温还是300℃,材料的变形行为和拉伸力学性能明显取决于SiC颗粒尺寸.研究表明,材料中的空隙密度、SiC颗粒的间距、分布状态以及SiC颗粒的断裂、SiC颗粒/Al界面的脱粘和基体材料的开裂等几种因素共同影响着复合材料的变形行为和力学性能.     

坩埚移动式喷射共沉积制取铝基复合材料的技术

提出了坩埚移动式喷射共沉积制备铝基SiC颗粒增强复合材料的装置和方法,并与传统的喷射共沉积装置进行了比较.在SiC颗粒增强相加入方法中,新工艺采用了双环缝复合雾化器和螺杆给料负压引流输送装置,解决了大尺寸、高SiC体积百分比复合材料坯制备技术问题.通过上述装置已经制备出Φ800×1000mm,SiC含量为20wt%,重达1t的铝基复合材料.经后续挤压、锻造加工,制备出了性能优异的6000Al/SiCp,FV0812Al/SiCp,7075Al/SiCp的大尺寸复合材料.讨论了喷射共沉积过程中金属液体对SiC颗粒的捕获机理、喷射共沉积过程中的传热与凝固特征,分析了SiC颗粒的加入对金属液粒凝固的影响.     

伪半固态挤压成形制备高体积分数SiCp/Al复合材料的性能

采用伪半固态挤压工艺制备SiC体积分数为40%、50%、65%的SiCp/Al复合材料,并对其微观组织和性能进行研究.结果表明:制备的高体积分数SiCp/Al复合材料中SiC颗粒分布均匀,铝合金填充在SiC缝隙中,形成致密组织.Mg和SiO2均能改善SiC颗粒与Al的界面润湿性,增加界面结合强度.所制得的φ(SiC)=65%的复合材料密度为3.11g/cm3,表面硬度为HB 108.5,抗折强度302.1 MPa,热膨胀率低于5.6×10-6/K,热导率为74 W/(m·K);SiC与Al基体界面的破坏以脱粘机制为主.     

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.