纳米氧化铝粉的制备

本文分别以廉价的硫酸铝铵和碳酸氢铵为主要原料,采用AACH法制备出Al(OH)3沉淀,经1200℃、2小时煅烧后,得到了平均粒径为70～100nm的α-Al2O3纳米粉末。讨论了不同工艺参数对所获得纳米粉体颗粒形状、颗粒分布、团聚情况以及晶相构成等的影响规律。实验结果表明,在1200℃进行煅烧处理,则可获得纯的刚玉型氧化铝;同时分析讨论了不同工艺对α-Al2O3粉的粒度、分散特性等方面的影响。不同的滴定方式对α-Al2O3的粒度和团聚程度有重要影响,而对粉末的晶粒形状没有明显的影响。     

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。     

Ni包裹纳米α-Al2 O3复合粉体的制备

以纳米α-Al2O3、NH4HCO3和Ni(NO3)2·6H2O为原料,采用非均匀沉淀法制备了Ni包裹纳米α-Al2O3复合粉体,并利用XRD、SEM、EDS和TEM测试手段,分析包裹粉的物相和形貌,研究了沉淀剂的加入方式、电解质浓度等反应条件对包裹效果的影响.研究表明低浓度的电解质母液和中等功率超声场易使纳米α-Al2O3在母液中充分悬浮,从而为制备均匀的包裹粉体提供条件;沉淀剂以雾化的方式加入可以使Ni盐优先在Al2O3颗粒上形核,减少其自发形核,制备出适合热喷涂的纳米结构包裹复合粉.     

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.     

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.     

颗粒增强Al基复合材料组织和性能的研究

采用高能球磨粉末冶金法制备颗粒增强Al基复合材料,分别以ZrO2,SiC和α-Al2O3为增强体,对比分析了不同颗粒增强Al基复合材料的组织与性能.以α-Al2O3颗粒为主增强体,分析了不同粒度α-Al2O3对复合材料组织性能的影响.研究结果表明,ZrO2/Al和 SiC/Al 复合材料的界面结合不如α-Al2O3/Al复合材料的界面结合紧密,α-Al2O3颗粒粒径为45μm时,复合材料性能更好地得到改善,添加适量的Ce能改善基体与增强体的界面结合,并显著地提高了颗粒增强Al基复合材料的性能.     

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．     

Y2O3-Al反应合成YAG相变分析

针对高纯Y2O3和Al粉体之间发生的相变和Y2O3-Al粉体固相反应法制备的YAG粉体进行了研究。Y2O3-Al粉体在摩尔比3∶10和转速200 r/min条件下球磨12 h,在1 200℃空气中煅烧2 h生成YAG粉体。采用DTA-TG表征混合的Y2O3-Al粉体热物性,并采用XRD、SEM表征混合的Y2O3-Al粉体、YAG粉体特性。实验表明：Y2O3-Al粉体在569℃时,Al粉氧化显著,Al氧化物继续与Y2O3粉反应;600℃煅烧后出现YAM相,800℃煅烧后显现YAP相,1 200℃煅烧生成YAG粉体;混合的Y2O3-Al粉体和煅烧的YAG粉体粒径均为亚微米级,粉体存在软团聚。     

沉淀法制备氧化铝的相变过程

为获得沉淀法制备氧化铝的相变过程及微观形貌,将NaOH溶液与AlCl3溶液混合,在pH值6～9内,制备三羟铝石,将其加热到1 200℃获得了氧化铝粉体。经TG-DTA、XRD、FTIR光谱、SEM等测试手段分析,300℃煅烧后获得了单水铝石,然后依次获得γ-Al2O3、δ-Al2O3、θ-Al2O3过渡相,并且在1200℃煅烧后获得了纯相α-Al2O3。TG-DTA表征,粉体在273℃脱水显著,在1000℃后θ-Al2O3向α-Al2O3形核并长大,需要较大激化能而放热,1 200℃煅烧后FTIR透过光谱表征α-Al2O3的典型的AlO6八面体结构引发形成640～590 cm^-1的两个吸收峰。制备的三羟铝石呈亚微米的团絮状,而纯相α-Al2O3呈现亚微米的聚集体颗粒形貌。这为改进陶瓷性能提供工艺参数依据。     

α-Fe_2O_3纳米颗粒的制备及其对曙红B的吸附性能研究

以Fe(NO_3)_3·9H_2O与Na_2S_2O_3为前驱体溶液,加入表面活性剂聚乙烯吡咯烷酮(PVP),采用光化学合成方法首先制备FeO(OH)/S粉体材料,然后通过高温煅烧后得到Fe_2O_3纳米颗粒.结果表明,随着煅烧温度的升高,α-Fe_2O_3纳米颗粒的结晶度变好,晶粒粒度逐渐增大;α-Fe_2O_3纳米颗粒对曙红B具有较好的吸附效果,煅烧温度为400℃时吸附效果最佳.研究了不同吸附剂用量、p H对吸附性能的影响.Fe_2O_3纳米颗粒对曙红B的吸附过程符合二级动力学与Freundich等温吸附模型,最大吸附量为368 mg/g.     

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.