α钛合金(Ti-Al-Zr)在360℃水,400℃蒸汽条件下的静水腐蚀行为

研究了α钛合金(Ti-Al-Zr)在360℃,18.6 MPa水和400℃,10.3 MPa水蒸汽中的静水腐蚀行为,腐蚀时间累计分别达到221 d和213 d.利用扫描电镜和X-射线衍射技术观察并分析了α钛合金氧化膜的形貌及物相组成.结果表明:α钛合金在高压水和蒸汽中的腐蚀动力学曲线上均出现了三个阶段.在腐蚀的第一阶段,腐蚀增重随腐蚀时间增加而缓慢增加;在第二阶段,腐蚀增重突然增大;到第三阶段,腐蚀增重变化不大.α钛合金的氧化膜主要由两种不同的TiO2组成:金红石和锐钛矿.随着腐蚀时间的延长,氧化膜中锐钛矿的相对含量逐渐增加.     

钛,锰,铌对Fe—25Cr合金在硫化环境中预氧化保护作用的影响

研究了中等含量的钛、锰或铌对Ｆｅ－２５Ｃｒ合金预氧化层在高温硫化环境中保护怀的影响，实验结果发现：所有合金在１０００℃、１０＾５ＰａＯ２中经不同时间预氧化后的硫化出现了增重缓慢的保护性硫化阶段，之后试样迅速增重，加ｗ（Ｔｉ）＝４％使合金形成了略厚的ＴｉＯ和ＴｉＣｒ２Ｏ４混合氧化层，使保护性阶段加长了约１倍，而加ｗ（Ｍｎ）＝９％的合金却形成了多孔的以ＭｎＯ和ＭｎＣｒ２Ｏ４尖晶石相为主的混合氧化层，保     

碱激发低品位石灰石胶凝材料的研究

通过水玻璃改性，实现了常温了石灰石－水玻璃的反应，生成物具有明显的胶结性质，净浆小试体７ｄ强度达３２．６ＭＰａ，１４ｄ强度达４０．４８ＭＰａ，砂浆试体７ｄ强度达１４．６８ＭＰａ，１４ｄ强度达２３．０８ＭＰａ。     

复合稳定剂增加脊髓灰质炎糖丸疫苗的稳定性

该研究改进了现行脊髓灰质炎糖丸疫苗的稳定性，由１ｍｏｌ·Ｌ－１ＭｇＣｌ２稳定性改为１ｍｏｌ·Ｌ－１ＭｇＣｌ２＋０．５ｍｏｌ·Ｌ－１磷酸盐缓冲液复合稳定剂（１ｍｏｌ·Ｌ－１ＭｇＣｌ２＋０．５ｍｏｌ·Ｌ－１ＰＢ）．采用复合稳定剂后，大大增加了疫苗的稳定性．２２℃保存时间比１ｍｏｌ·Ｌ－１ＭｇＣｌ２稳定剂延长了一周，即保存时间从１２ｄ延长至１８～２１ｄ．疫苗于４℃保存了６个月，滴度降低甚微．在３７℃保存３ｄ，疫苗的滴度降仍符合ＷＨＯ规程的要求     

Al2O3—ZrO2—SiC陶瓷的快速烧结与力学性能

研究反应结合Ａｌ２Ｏ３－ＺｒＯ３－ＳｉＣ复合陶瓷的快速烧结工艺和力学性能,讨论反应结合过程及物相变化,快速烧结是抑制晶粒生长,获得均匀,细微,致密结构有效途径Ｎｏ．３复合陶瓷在１５５０℃经１０ｍｉｎ的快速烧结,材料的力生能达到了较好水平,经度５５５ＭＰａ,断裂韧性３．６ＭＰａ．ｍ＾１／２维氏硬度１７．１ＧＰａ。     

卵黄油在超临界二氧化碳中的溶解度及其模拟

本文利用动态法及半连续装置，在温度３５℃－７５℃、压力２５ＭＰａ－２６ＭＰａ的条件下，进行了卵黄油在超临界二氧化碳中溶解度试验，并将试验结果用反传播神经网络方法进行模拟，社会网络能较好地模拟卵黄油在超临界二氧化碳中的溶解度。     

Si3N4-MgO-CeO2陶瓷烧结过程中的致密化与相变

氮化硅陶瓷有极大的应用潜力,但由于其强共价键,很难烧结致密化。采用了一种新的ＭｇＯ－ＣｅＯ２复合烧结助剂,利用Ｘ射线衍射、透射电镜等手段研究了ＭｇＯ－ＣｅＯ２复合烧结助剂对氮化硅陶瓷致密化和相变过程的影响,结果发现对Ｓｉ３Ｎ４－ＭｇＯ－ＣｅＯ２陶瓷,在１４５０℃就会有大量液相出现,１５００～１５５０℃为快速致密化阶段,而α－Ｓｉ３Ｎ４→β－Ｓｉ３Ｎ４相变主要发生在１５５０～１６００℃,相变过程滞后于致密化过程。常压烧结Ｓｉ３Ｎ４－ＭｇＯ－ＣｅＯ２陶瓷,强度达９４８ＭＰａ,因此,ＭｇＯ－ＣｅＯ２是一种非常有效的氮化硅的烧结助剂。     

1000℃MgO—B2O3—SiO2三元相关系研究

ＭｇＯ－Ｂ２Ｏ３－ＳｉＯ２三元系１０００℃时，３５％≤ＭｇＯ％〈６０％组成范围内平衡相均为固相，其相关系可由Ｍｇ３Ｂ２Ｏ６－Ｍｇ２ＳｉＯ４－Ｍｇ２Ｂ２Ｏ５，Ｍｇ２Ｂ２Ｏ５－Ｍｇ２ＳｉＯ４－ＭｇＳｉＯ３，Ｍｇ２Ｂ２Ｏ５－ＭｇＳｉＯ３－ＳｉＯ２三个结线三角形表示。各平衡相量之间关系可应用ＸＲＤ定量相分析或重心规则计算。     

化合物N—（2‘,4’,5‘—三氯）苯基—2—羟基—3,5,6—三氯苯磺 …

使用半径验分子轨道计算得到了化合物Ｎ－（２’４‘,５’－三氯）苯甘－２－羟基－３,５,６－三氯苯磺酰胺的一些电子性质,用分子力学程序ＭＭＰ２得到了该化合物的分子几何构型和稳定构象。计算时参数取自对分子Ｎ－甲基甲基磺酸胺的ａｂｉｎｉｔｉｏ计算研究和Ｘ－光晶体衍射结果。研究表明：原子Ｓ和Ｎ形成ｄ－ｐ配价键,通过此键,其电子进一步与两边的取代苯环共轭,ｄ－ｐ配价键对分子中的电子离域可能起着一个重要的桥梁     

水－仲丁醇－碳4三元体系8MPa时的液液平衡

在国内首次建立的一套温度高达３５０℃，压力直至２０ＭＰａ的高压液液相平衡测定装置上，测定了水－仲丁醇－碳４三元体系在８ＭＰａ和４０３．１５，４２３．１５，４４３．１５Ｋ时液液相平衡数据。采用修改的Ｒ－Ｋ方程对此数据进行了理论关联。关联结果与实验数据一致。     

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。