用柠檬酸溶胶凝胶法合成SrFeCo_(0.5)O_x氧化物

采用柠檬酸溶胶凝胶法合成SrFeCo0 5Ox混合导体氧化物·利用XRD、TEM以及DTA方法研究与分析了不同条件下样品的晶体结构组成、相貌·确定了最佳制备条件·结果说明在燃料剂/氧化剂比例为0 64,550℃时得到单相钙钛矿氧化物,氧化物为纳米球形颗粒,尺寸分布均匀;加热温度升高850℃晶体结构无变化,颗粒尺寸明显长大但是形状不变·同时分析了溶胶凝胶反应过程及影响因素·     

金属冲击加热的研究

金属冲击加热是对流快速加热的一种新型加热工艺,也是金属加热的一项节能新技术。它是用高温高速气流直接冲击金属表面的快速对流加热方法来完成金属锻前或轧前的加热,金属加热温度均匀、加热速度快、加热时间短,可以大大降低燃耗。本文由金属冲击加热数学模型,用计算机解出了获得最佳加热炉温和断面温差最小的加热时间时换热系数范围为:300～500KKal/m~2·h·℃     

半固态A356合金触变成形件固溶组织与性能

利用电阻炉加热,对半固态A356铝合金触变成形件进行固溶时效处理,并进行组织与性能的观察分析·结果表明:在535℃温度下固溶处理,随固溶时间的延长,强化相溶解充分,合金元素在晶格的分布均匀,强度得到了提高·在180℃温度下时效,强度随时效时间的延长而增大,并达到最大值;进一步延长时效时间,则合金出现软化·触变成形变形带的存在,起到了强化作用·本研究为A356合金液相线半连续铸造生产工业化提供理论指导·     

混合导体氧化物SrFeCo_(0.5)O_(3-x)的微波混合加热合成

采用微波混合加热方法(即微波加热+电阻加热)和常规加热方法合成了混合导体氧化物SrFeCo05O3-x粉末·利用XRD,SEM/EDX测试手段对两种方法合成粉末的物相结构,形貌及化学成分进行了分析·结果表明,微波混合加热与常规加热合成粉末的结晶相结构类型相同,但是结晶相比例存在差异·微波混合加热法得到的主相属于立方钙钛矿结构;常规加热法得到的主相属于正交结构·微波混合加热制备的粉末颗粒尺寸分布较均匀,结晶度较好·     

火焰加热温度对6005A铝合金焊接接头性能的影响

针对铁路交通车辆用 60 0 5A铝合金型材的焊接变形 ,采用火焰加热方法进行矫正·研究了火焰加热温度对焊接接头抗拉强度、硬度及微观组织结构的影响·实验结果表明 ,当加热温度低于 2 0 0℃时 ,焊接接头的抗拉强度、硬度未降低 ,热影响区内软化区的显微组织未发生明显变化 ;当加热温度超过 2 0 0℃时 ,焊接接头的硬度发生较明显降低现象 ,软化区范围加宽·软化区材料性能下降的原因是在火焰加热的热输入过程中过热导致该区晶粒粗大     

垃圾热解中PVC组分HCl的析出特性

以垃圾中的PVC组分为试验物料,在外热式固定床热解试验台上,研究了PVC热解过程中HCl的析出特性·通过改变加热方式、热解终温、加热温度、加热时间等参数研究了HCl的析出过程、析出量和质量分数·试验表明,加热方式对HCl析出有很大的影响,快加热方式析出的HCl量几乎是慢加热方式的2倍;HCl析出过程可分为三个阶段,325℃时开始有HCl析出;热解终温对HCl析出过程有较大的影响,并决定着HCl的析出量,本试验在550℃左右析出的HCl量最多,这说明存在一个HCl析出量最大的峰值温度·并依据试验结果,从理论上进行了初步探讨     

液相线半连续铸造7075铝合金半固态组织演变

研究了液相线半连续铸造法生产的7075铝合金半固态浆料二次加热时组织的演变和主要合金元素的分布·结果表明,液相线铸造7075铝合金在相同加热温度下,随着保温时间的延长,晶粒尺寸与球化倾向增大;在相同保温时间下,随着加热温度的升高,晶粒尺寸与球化倾向也增加·加热温度580℃左右,保温时间在15～30min之间,和加热温度600℃左右,保温时间在5～15min之间,可以将半连续铸造锭坯中的蔷薇状和近球状组织转化为球形晶粒,晶粒的平均直径范围为40～55μm,完全适合于半固态加工·液相线铸造7075铝合金二次加热组织中,主要合金元素M...     

A2017半固态合金二次加热组织演化

对SCR技术制备的A2017半固态坯料进行二次加热,利用光学显微镜,电镜,图像分析仪等手段,对坯料二次加热微观组织的演化进行了研究·实验结果表明,在相同加热温度条件下,随着保温时间的延长,晶粒平均等积圆直径增大,晶粒越来越圆整,液相率增加;提高二次加热温度,晶粒长大和球化速度加快·二次加热最佳工艺条件为加热温度580℃,保温时间40～60min或者加热温度600℃,保温20～40min,晶粒平均等积圆直径为70～90μm,固相率在70%左右,适合于半固态加工·组织演化机制分析表明,加热初期阶段,液相少,晶粒主要通过碰撞熔合快速长大;随着保温时间延长,液相增加,晶粒主要通过原子扩散慢速长大并发生...     

加热温度对高速钢铸轧薄带中共晶碳化物形态的影响

研究了退火加热温度对高速钢双辊铸轧薄带中共晶碳化物形态的影响·试验结果表明,随着加热温度的提高,铸轧薄带中的网状共晶碳化物陆续熔断,粒状碳化物逐渐增多·当加热温度达到950℃后,铸轧薄带中的网状共晶碳化物基本上被粒状碳化物所取代·用汤普森弗瑞锥其(ThompsonFriedrich)方程,对试验结果进行了分析,并得出共晶碳化物层片间距的减小为高速钢铸轧薄带中的共晶碳化物的熔断和球化提供了条件·     

7075Al合金LSC铸锭二次加热中的液固相体积分数

研究了液相线半连续铸造法制备的7075Al合金坯料在二次加热过程中液固相比的变化,分别用电阻法、热涵法测定出不同温度下7075Al合金的液相体积分数,并与图像法进行了比较·结果表明,在600℃左右,电阻法与用热涵法、图像法所测的实验结果基本一致,正确反映了加热过程中合金的液固相变化规律·用电阻法能方便有效地测定二次加热过程中半固态7075Al合金的液固相比,具有实时性强的优点,在600～620℃时,7075Al合金液固相比为30%～50%,完全适于合金的半固态成形·     

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