稀土对α-Al2O3／Al基复合材料组织与性能的影响

采用稀土固态混合法和稀土液相包裹法制备含稀土α-Al2O3/Al基复合材料,研究了稀土元素加入方式和稀土含量对α-Al2O3/Al基复合材料组织和性能的影响.结果表明,与固态混合法相比,液相包裹法制备的Al基复合材料具有较高的硬度和耐磨性,添加适量的稀土Ce对α-Al2O3/Al基复合材料组织性能起到较好的改善作用.     

液相法纳米氧化铝粉的制备

以廉价的无水氯化铝为主要原料，采用液相法制备出Al(OH)3沉淀，经1200℃2h煅烧，得到了平均粒径为30nm～80nm的α-Al2O3，超细粉末，并对不同工艺方法对纳米氧化铝粉的粒度、分散特性及物相构成等方面的影响进行了分析和讨论。实验结果表明，不同的滴定方式对α-Al2O3，粉的颗粒大小、颗粒形态和团聚程度有重要影响，较高的煅烧温度可获得纯的α-Al2O3，纳米粉末。     

金属Ni、FeNi包裹氧化铝复合微粉的制备

利用非均相沉淀包裹工艺,首先制备了前驱体碱式碳酸镍（NCH）包裹α-Al2O3,或碱式碳酸铝铵（AACH）微粉,然后将前驱体在500℃下经氢气还原2h,成功制备了表面较光滑、致密的金属镍包裹氧化铝球形微粉．分析了非均相沉淀过程中前驱体包裹结构形成机理及影响因素,并初步确定了优化制备条件．通过采用α-Al2O3取代AACH或同时采用FeNi合金包裹解决了金属层易脱落问题．利用SEM、XRD及TG／DSC等手段表征了前驱体及还原产物的形貌、成分以及NCH／AACH热分解过程．Ni、FeNi包裹氧化铝复合结构球形微粉可应用于制备连续金属Ni或FeNi合金相三维网络结构氧化铝／金属复合陶瓷．非均相沉淀一热还原工艺可应用于陶瓷／金属封接中金属化层材料的制备．     

纳米α-Al2O3的制备及其对HMX热感度的影响

采用模板介入法制备了纳米级α-Al2O3,对制得的样品的尺寸、形貌和晶型等使用纳米粒度仪、透射电镜（TEM）以及X射线衍射仪（XRD）进行分析测试，将纳米仅α-Al2O3按2．0wt％加入奥克托今（HMX）中，对混合物进行慢烤实验．结果表明样品为粒度分布均匀、分散性很好的仅α-Al2O3，在密度为1．62g／cm^3，升温速率为3℃／Min条件下，添加纳米仅α-Al2O3，的HMX的自加速拐点温度提前10℃，混合炸药的热感度提高，纳米仅α-Al2O3，对HMX具有催化作用．     

均匀沉淀法制备纳米α-Al2O3粉

以Al（NO3）4.9H2O、NH4HCO3和C6H8O7.H2O为主要原料,采用均匀沉淀法制备纳米α-Al2O3粉。研究了表面活性剂和过滤方法对前躯体转晶温度的影响,采用XRD和TEM对粉体进行表征。结果表明：在前躯体制备过程中加入表面活性剂PEG6000可使前躯体的转化温度降低75℃,常压过滤比用真空抽滤的前躯体转化温度低25℃,前躯体转化为α-Al2O3相的最佳煅烧温度是1050℃;制备的α-Al2O3是粉体分散性良好的片状晶体,呈两极分布状态,小颗粒平均粒径约20nm,大颗粒的宽约50～80nm、长约100～200nm。     

促进剂对荧光粉用α-Al2 O3 形成过程及粉体形貌的影响

通过碳酸铝铵热分解法制备出α-Al2O3粉,并重点研究了促进剂在氧化铝制备过程中的作用.结果表明,加入促进剂可以使α-Al2O3相变温度降低至900 ℃,且没有θ-Al2O3相的生成;促进剂的加入促进了Al2O3晶体的生长,并趋向于形成六角形的片层状颗粒;煅烧温度过高容易形成过薄的片状氧化铝颗粒;适量加入促进剂可以获得大小均匀,外形规则的六角形氧化铝分散颗粒,大小约为1～2 μm,比表面约为2 m2/g.     

沉淀-共沸蒸馏法制备超细α-Al2O3粉体的研究

以Al2(SO4)3为铝源,(NH4)2CO3为沉淀剂,利用沉淀-共沸蒸馏法制备出前驱物碳酸铝铵(AACH),并煅烧得到超细α-Al2O3粉末.研究了加料方式、表面活性剂、干燥方式等因素对产物分散性能的影响,分析了超细氧化铝粉末在热处理过程中的结构和性能变化.采用热重/差示扫描法(DTA/TGA)、扫描电镜(SEM)、X射线衍射(XRD)以及ICP等现代分析检测技术对样品性能进行了表征.结果表明,只有将Al2(SO4)3溶液雾化加入到(NH4)2CO3溶液中,添加适量PEG1000做为分散剂,同时采用正丁醇共沸蒸馏才能制备出粒度分布均匀、分散性能优异的超细α-Al2O3粉末.煅烧过程中,氧化铝的相变过程为:Al2O3(无定型)→γ-Al2O3→θ-Al2O3→α-Al2O3,且随着煅烧温度的提高,产物的晶粒尺寸不断增大,密度不断得到提高.在优化条件下合成的前驱物AACH于1 200 ℃煅烧2 h,能得到粒度分布均匀、分散性良好、形貌为类球形且纯度为99.97%以上的α-Al2O3粉体.图9,表1,参15.     

La对CH_4-CO_2重整反应催化剂性能的影响

采用等体积浸渍法制备了Ni/γ-Al2O3和Ni/La2O3-γ-Al2O3系列催化剂,通过固定床反应、热重分析等方法,考察了催化剂的性能。结果表明:Ni质量分数为10%的Ni/γ-Al2O3催化剂具有较高的活性;稀土元素La的加入,提高了催化剂的抗积炭性能;在相同的反应条件下,10%Ni/3%La2O3-γ-Al2O3催化剂的积炭量比10%Ni/γ-Al2O3催化剂积炭量降低了40%,稳定性大大提高。以Ni/La2O3-γ-Al2O3催化剂中Ni质量分数10%,并且La质量分数3%为最佳,实验条件下制得的合成气CO/H2接近1/1。     

纳米TiO2/γ-Al2O3制备及光催化性质的研究

制备了TiO2/γ-Al2O3负载型纳米复合催化剂,利用XRD,UV-VIS手段对其光降解活性进行表征,考察了TiO2/γ-Al2O3纳米催化剂降解工业废水中的丙烯酸。结果表明：在可见光条件下,TiO2/γ-Al2O3纳米催化剂对高浓度工业废水中的丙烯酸有降解作用。     

微波-超声法制备α-Al_2O_3纳米粉体的研究

通过X-射线衍射、扫描电镜及透射电镜,研究了结合微波-超声的溶胶-凝胶法制备α-Al2O3纳米粉体,并探讨了该制备条件下α-Al2O3晶种的引入对产物相变的影响.结果表明:该法能制备出外观呈球形、粒径分布比较均匀、粒径约15 nm的α-Al2O3,且实验快速、简便;而引入α-Al2O3晶种,能促进θ-Al2O3向α-Al2O3转变,并能有效降低产物相变温度,当引入量为2%时,1 000℃煅烧并恒温2 h的产物全部为α-Al2O3.     

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.