颗粒弥散强化复相陶瓷

制备SiC、TiB2及ZrO2颗粒弥散强化MoSi2、Al2O3基复相陶瓷，研究了弥散颗粒及其加入量对材料强韧化效果的影响，并探讨了弥散颗粒多重强化协调作用及机理。结果表明：弥散颗粒的加入量对材料的强韧性有显著影响；通过合理的工艺控制，不仅在ZrO2、TiB2二元颗粒复合弥散强化的Al2O3基复相陶瓷中，而且在单相ZrO2颗粒弥散强化的MoSi2基复相陶瓷中，弥散颗粒均实现了相变强化与弥散强化双重作用。     

ZrO2基陶瓷注凝成型料浆流变性的研究

陶瓷料浆流变性能是注凝成型工艺的关键,料浆流变性要求高固含量,低粘度.实验通过在ZrO2表面包覆Al2O3,形成ZrO2-Al2O3复相陶瓷料浆.根据静电位阻稳定理论,通过调节pH值和分散剂的加入量,可得到满足成型要求的高固含量,低粘度的料浆.结果表明,在pH值为10左右,分散剂加入量为粉料质量的3%时,料浆固相体积分数可以达到40%.同时表明了Al2O3对ZrO2颗粒表面有改性作用,提高了悬浮体的稳定性.     

重力分离SHS复合管内衬(Al_2O_3 ZrO_2)复相陶瓷的显微组织与形成

研究了重力分离SHS复合管内衬 (Al2 O3 ZrO2 )复相陶瓷的显微组织与形成过程 .研究得出 :陶瓷基体主要由Al2 O3 与ZrO2 的层片状或棒状共晶组织形成 .在 (Al2 O3 ZrO2 )复相陶瓷凝固过程中 ,亚共晶成分复相陶瓷熔体将先后发生离异共晶生长行为和共生共晶生长行为 ;而对于过共晶成分复相陶瓷 ,复相陶瓷熔体将按共生共晶方式结晶生长     

ZTA纳米复相陶瓷的制备研究进展

介绍了ZTA(ZrO2 toughening Al2O3)复相纳米陶瓷国内外发展情况和ZTA陶瓷的主要性能及结构，论述了ZrO2增韧Al2O3的几种增韧机理和制备ZTA复相纳米陶瓷粉体的主要方法。     

铝热法制备的ZrO2/A12O3复相陶瓷材料组织和力学性能

通过铝热反应制备ZrO2/Al2O3复相陶瓷材料,研究ZrO2含量对复相陶瓷显微组织与力学性能的影响.结果表明:复相陶瓷的相组成为ZrO2和Al2O3.随着ZrO2含量增加,ZrO2在基体中的分布越均匀,维氏硬度为8～15 GPa,在ZrO2质量分数为41.5%时呈现最大值为14.85 GPa;断裂韧性先增加后降低,在...     

铝热法制备的ZrO_2/Al_2O_3复相陶瓷材料组织和力学性能

通过铝热反应制备ZrO2/Al2O3复相陶瓷材料,研究ZrO2含量对复相陶瓷显微组织与力学性能的影响.结果表明:复相陶瓷的相组成为ZrO2和Al2O3.随着ZrO2含量增加,ZrO2在基体中的分布越均匀,维氏硬度为8～15GPa,在ZrO2质量分数为41.5%时呈现最大值为14.85GPa;断裂韧性先增加后降低,在ZrO2质量分数为30%时呈现最大值8.01MPa.m1/2.     

等离子分解锆英石制备ZrO2-SiO2-Al2O3系复相陶瓷

等离子分解锆英石(PDZ,plasmicalldecomposedZrO2)与Al2O3注浆成型反应烧结制备ZrO2SiO2Al2O3系复相陶瓷,与用锆英粉和Al2O3制备的该系复相陶瓷进行对比。采用XRD、OM、SEM等手段研究烧成后材料的物相组成、显微结构及物理性能。结果表明:ZrSiO4的分解先于莫来石形成;由PDZ制得的制品性能优于锆英粉制得的制品;n(Al2O3)/n(PDZ)=3/1、1540～1580℃为合适的原料配方和烧成温度范围     

内氧化工艺对Al_2O_3/Cu复合材料中Al_2O_3颗粒分布的影响

采用压块加入法和分别加入法两种内氧化工艺 ,将 Cu O和 Al粉末加入到 Ar气保护的铜液中制备 Al2 O3/ Cu复合材料 ,在光学显微镜、扫描电镜及 X射线衍射仪上观察分析了Al2 O3颗粒的数量、分布及材料的相组成。结果表明 ,压块加入法生成的 Al2 O3颗粒呈枝晶状分布 ,最佳保温时间为 30～ 45 min;分别加入法生成的 Al2 O3颗粒呈弥散状分布 ,最佳保温时间为 45～ 6 0 mi     

(TiB_2+Al_2O_3)增强铝基复合材料的组织分析与硬度测试

将TiO2和B2O3原料混合后加入ZL102铝熔体,采用原位反应的方法,使其与铝液发生反应,制备出(TiB2+Al2O3)双相增强铝基复合材料.用EPMA及SEM分析反应合成的增强颗粒在基体上的分布状态以及TiB2和Al2O3颗粒的微观组织,用显微硬度仪测定复合材料组成相的显微硬度.结果表明,利用Al-TiO2-B2O3体系可以原位制备颗粒增强的铝基复合材料,合成的复合材料硬度比ZL102提高37.3%.     

Al_2O_3-ZrO_2复相陶瓷的超塑压缩变形织构

为了验证Al2O3-ZrO2复相陶瓷压缩变形后是否出现织构,采用X射线衍射（XRD）、极图和扫描电镜（SEM）对Al2O3-ZrO2复相陶瓷超塑压缩变形后的组织进行了分析。结果表明：复相陶瓷压缩变形后,Al2O3晶粒在（110）、（113）和（300）晶面出现择优取向,织构强度高达6.21,而ZrO2取向不明显。     

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.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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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。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

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