一种低焊接裂纹敏感性钢的奥氏体粗化温度研究

通过高温淬火试验观察试验钢奥氏体晶粒尺寸的变化情况.结合金相和TEM观察、显微硬度和第二相粒子的溶解度积公式分析了加热温度和保温时间对试验钢奥氏体晶粒粗化温度、第二相粒子的溶解情况以及显微硬度值的影响.结果表明:试验钢的奥氏体粗化温度在1200℃附近.当加热温度低于1200℃时,大量细小的第二相粒子阻碍奥氏体晶粒粗化;当加热温度高于1200℃时,细小的第二相粒子溶解,奥氏体晶粒出现异常长大.确定试验钢的合理加热温度为1150～1200℃,在此范围内可获得淬火组织的显微硬度值低于HV330.     

温度对电容器用TiCxN1-x／Al复合铝箔比电容的影响

采用多弧离子镀技术制备高容量电容器用TiCxN1-x/Al复合铝箔电极,研究不同温度下TiCxN1-x/Al复合铝箔的比电容特性,并通过扫描电镜和X射线衍射分析不同温度下铝箔的表面微观结构和物相变化规律.结果表明,TiCxN1-x/Al复合铝箔的比电容高达1 600 μF/cm2,经退火处理后,TiCxN1-x涂层表面颗粒有逐渐长大趋势,晶体结构也从非晶态向晶态转变,当退火温度高于200 ℃时,复合铅箔比电容下降较快.     

低压电容铝箔国产化的研制(英文)

本文利用金相、X光和电子显微镜等技术,对国产和进口低压电容器用铝箔的成分和组织结构等进行了对比分析。通过对铝箔直流腐蚀形貌的观察,研究了提高铝箔比电容的机理。成功地开发了一种新型国产电容铝箔,经工厂实际生产应用证明,各种技术指标均达到进口电容铝箔的水平,能取代进口箔,具有巨大的社会效益和经济效益。     

微量Ga对电容器阳极用铝箔组织及比电容的影响

采用X射线衍射定量检测含微量Ga高压电解电容器阳极用退火箔的立方织构,用金相显微镜及扫描电镜观察其显微组织,用图像分析软件分析腐蚀箔的腐蚀结构,研究了微量Ga对组织结构、腐蚀结构及比电容的影响.结果表明:Ga的质量分数由05×10-6提高至116×10-6时,铝箔的立方织构的体积分数略微下降,但在520V的比电容却由0662μF/cm2增加到0706μF/cm2;当Ga的质量分数增加至214×10-6时,显微组织及织构变化不明显,但比电容下降至0693μF/cm2.这是因为适当添加微量Ga能促进电化学腐蚀发孔,增加箔的表面积,提高其比电容;但Ga的质量分数高于116×10-6时,将增加箔的并孔数量,减少其表面积,导致比电容下降.     

中间退火工艺对铝箔力学性能和成品率的影响

采用 4种不同的中间退火工艺 ,通过显微组织观察、定量金相、X ray衍射分析 ,力学性能测试等实验手段 ,研究了中间退火工艺对AA12 35合金铝箔轧制性能和力学性能的影响。结果表明 ,中间退火工艺对铝箔力学性能和轧制性能有显著影响 ,当采用 380℃× 6h +2 10℃× 9h的分级退火工艺时 ,各压下量下材料的抗拉强度均小于 16 0N/mm2 ,其变形抗力较小 ,塑性较好 ,有利于薄箔的轧制 ,铝箔产品的成品率可达到 80 %以上。显微组织观察表明 ,采用该工艺时 ,铝箔毛料有较好的显微组织 ,Si和Fe析出充分 ,化合物尺寸峰值在 2～ 3μm之间。作者对工艺参数和杂质元素的影响机理进行了分析和讨论。     

介孔Co_3O_4纳米片的结构和超级电容性能研究

利用X射线衍射(XRD)、透射电子显微镜(TEM)、恒温氮气吸附等技术,研究了不同焙烧温度下制备的介孔Co3O4纳米片的物相和微结构特点,明确了焙烧温度影响介孔Co3O4纳米片超级电容性能的微观机理.XRD和TEM结果表明,不同焙烧温度下获得的产物均为尖晶石结构的介孔Co3O4纳米片,且随着焙烧温度的升高,样品的结晶性增强.恒温氮气吸附结果表明,随着焙烧温度从300℃增加到500℃,介孔Co3O4纳米片的BET比表面积从27.9m2/g降低到2.2m2/g.电化学测试结果表明,400℃焙烧产物具有最优的超级电容性能,其比电容值为151F/g,是300和500℃焙烧产物比电容值的2倍左右.基于上述表征结果,我们提出样品结晶性和表面微结构的协同作用是决定介孔Co3O4纳米片超级电容性能的关键因素:与300℃焙烧样品相比,400℃焙烧产物具有更好的结晶性,利于电极氧化还原反应过程中电子的传输迁移;与500℃焙烧样品相比,400℃焙烧产物具有更为适中的BET比表面积,利于电解液参与电极反应.     

12%Cr马氏体不锈钢中温转变产物的组织与性能的研究

本文用金相硬度法测定了2Cr13钢中温转变动力学曲线,用金相显微镜及透射电镜观察了在不同温度回火后的 M/B 组织形态及其精细结构,并用碳化物萃取复型观察了碳化物析出与分布的特点,对等温组织与普通调质组织在硬度、强度、塑性、韧性、大气与腐蚀疲劳、腐蚀抗力、断裂韧度、疲劳门槛值与裂纹扩展速率诸方面的性能进行了对比和分析。在扫描电镜下分析了疲劳断口形貌。研究表明,等温组织(M/B)在常规力学性能方面均显著优于淬火回火组织,均匀腐蚀抗力较好,大气疲劳强度较高。但在600℃～650℃回火后与调质比较,其断裂韧性较差,腐蚀疲劳强度下降,点蚀电位较低。这与等温组织在热处理过程中沿原奥氏体晶界偏聚析出较多碳化物有关。     

马氏体时效钢激冷粉末的时效性

利用SEM技术,观察马氏体时效钢冷冷粉末经480℃、3h时效后的表面,发现有大量的白点相,主要分布于结晶组织的晶臂间,经能谱和波谱分析,鉴别其为Ti的化合物。显微硬度的分析表明,激冷粉末的时效硬度远远高于固溶淬火后的时效硬度,并有可能利用激冷组织的特征来提高马氏体时效钢的性能,并调整其成分。     

2301阴极电子铝箔的制备工艺研究

文中开发了一种2301Al合金阴极电子铝箔的生产工艺,设计采用"铸轧-冷轧"法生产了0.04mm厚度的3003Al、2301Al合金箔,观察了3003Al、2301Al合金箔的金相组织,测试了3003Al、2301Al合金箔力学性能及比电容。研究结果表明:首先通过铸轧获得7.5mm铝带坯,然后冷轧10-11道次,每道次变形率为30%-50%,可以成功制备0.04mm厚度2301Al成品箔。未进行二次退火的2301Al成品箔的抗拉强度为188MPa,腐蚀后比电容为641μF/cm~2。在中间道次中进行320℃/20h二次退火,2301Al成品箔表面质量提高,其抗拉强度变为160MPa,腐蚀后比电容变为532μF/cm~2。     

热处理对高铬铸铁组织和性能的影响

研究了不同热处理状态下高铬白口铸铁显微组织,探讨了热处理对高铬铸铁冲击韧性和硬度的影响,并确定了组织与性能的相关性。分别采用金相显微镜观察热处理后高铬铸铁显微组织,洛氏硬度计测定高铬铸铁的硬度,冲击试验机测定冲击韧性。结果表明：高铬铸铁随着淬火温度的升高,硬度先升后降,冲击韧性则相反。在1 000℃淬火空冷,并在400℃回火时,材料可以获得良好的综合力学性能。     

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.     

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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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.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。