钢-半固态铜-石墨压力复合的优化

为了开发钢铜石墨高温自润滑复合板材的复合技术,对钢板与QT i3.5-3.5石墨半固态浆料的压力复合进行了研究。采用人工神经网络建立了钢板预热温度、模具预热温度、QT i3.5-3.5石墨半固态浆料固相率等复合参数与钢-QT i3.5-3.5石墨复合板界面剪切强度之间的关系,并且利用遗传算法进行了优化,得到了合理的复合工艺。结果表明:在钢板预热温度为618℃、模具预热温度为526℃、QT i3.5-3.5石墨半固态浆料固相率为46.2%的条件下进行压力复合,复合板最大界面剪切强度为128.3M Pa。     

铁铝原子在金属间化合物形成中的扩散

采用铁铝扩散偶,研究铁铝原子在化合反应中的扩散和金属间化合物的形成机理,扩散偶在铁铝低共熔反应温度上下进行热处理,结果表明,扩散偶在低于共熔反应温度处理时,在扩散偶铁－铝界面铁的一侧,通过铝原子的扩散,形成了富铝相金属间化合物ＦｅＡｌ２;而在高于共熔反应温度处理时,则在铁－铝界面上,通过铁、铝原子的互扩散形成了金属间化合物Ｆｅ３Ａｌ５,并随时间向两旁生长,两种化合物均为多孔体。研究发现铁、铝原子的     

钢-铝石墨半固态铸轧复合的数值模拟

铸轧区的温度分布直接影响着铸轧过程的稳定性和复合板材的质量.针对实验室复合板半固态铸轧试验的特点建立了数学模型,采用有限元法对钢-铝石墨半固态铸轧复合过程的热流耦合问题进行了数值模拟计算,分析了不同浇注温度和铸轧速度下熔池内温度场变化的情况.模拟结果表明,当浇注温度为620℃,铸轧速度在0.6～0.8 m/min的范围内可保证铸轧稳定进行,此结论与试验数据相吻合.该模型可以有效预测凝固前沿位置,为半固态铸轧复合工艺的进一步研究和钢-铝石墨复合板的数字化生产提供了依据.     

加热对AZ31B/7075爆炸复合板界面的影响

对镁铝爆炸复合材料AZ31B/7075进行了300~400℃的加热处理。用光学显微镜、扫描电镜、能谱仪及力学性能试验机对复合界面结合区进行了组织观察、成分线扫描、剪切强度测试,分析了复合界面结合区加热时的变化。结果表明:随加热温度升高和保温时间延长,复合界面结合区组织形成再结晶且晶粒长大,爆炸组织特征完全消失,转变为具有一定厚度的由镁、铝互扩散形成的扩散层;扩散层组成按镁基固溶体-铝基固溶体、镁基固溶体-A l3Mg2-铝基固溶体、镁基固溶体-A l3Mg2-A l12Mg17-铝基固溶体的次序演化,其厚度增加主要是金属间化合物层的厚度增加所致;界面剪切强度因加热后扩散层中金属间化合物形成而降低,界面剪切断口也因扩散层中脆性金属间化合物的存在而表现为脆性断裂特征。     

硅对钢/铝轧制复合界面化合物抑制效应的研究

对钢铝复合材料高温时的界面化合物进行了系统研究并找到一定的方法抑制界面化合物的生成。要获得高品质的复合带材,就必须在高温时能抑制界面化合物的生成,提高钢铝结合强度和加工性能。通过对复合前的铝材料熔入不同含量的Si元素,经过与低碳钢的冷轧工艺复合,研究硅对于复合界面化合物的抑制作用。对不同Si含量的铝板复合后的样品进行分组比较,使用金相显微镜和扫描电镜进行了组织分析,发现钢/铝复合材料界面产生的化合物属于Fe-Al化合物,以Fe2Al5居多。通过热力学计算分析界面的自由能,发现Fe-Si化合物比Fe-Al化合物在退火过程中更容易生成,并且以大量实验结果表明微量元素Si的加入能显著抑制钢/铝界面Fe-Al化合物的生成,抑制效果随着硅含量的增加而越发明显。     

半固态Al-28Pb铸锭中Pb的分布

为有效解决铸造 Al- 2 8Pb润滑材料存在的 Pb分布不均问题 ,开发了半固态 Al- 2 8Pb加工技术 ,通过对不同固相率半固态浆料的常规铸锭中 Pb的分布进行研究 ,得到了半固态浆料固相率与铸锭中 Pb分布之间的关系。研究结果表明 ,随着浆料固相率的增大 ,铸锭中不同部位 Pb颗粒尺寸的差别逐渐减小 ,当固相率大于 4 5 %时 ,Pb颗粒尺寸的差别基本得以消除 ,尺寸相当的 Pb颗粒可均匀地分布在整个铸锭中。     

不锈钢/ZA43复合材料界面结构的研究

对常压浸渗法制备的不锈钢纤维增强的ZA43复合材料的界面结构进行了研究,结果表明,纤维与基体之间存在明显的界面层,此界面层由界面反应层和扩散偏聚层等多层构成,界面的形成过程主要是铁_铝金属间化合物的形成过程.同时,由于铝元素向纤维表面的偏聚和对纤维的腐蚀,导致了其它合金元素在界面处成分的不平衡分布.     

不锈钢／ZA43复合材料界面结构的研究

对常压浸渗法制备的不锈钢纤维增强的ZA43复合材料的界面结构进行了研究，结果表明，纤维与基体之间存在明显的界面层，此界面层由界面反应层和扩散偏聚层等多层构成，界面的形成过程主要是铁-铝金属间化合物的形成过程．同时，由于铝元素向纤维表面的偏聚和对纤维的腐蚀，导致了其它合金元素在界面处成分的不平衡分布．     

钢-铝固液相浸镀复合板的轧制处理

研究了轧制处理后－铝固液相浸镀复合板的界面剪切力学性能，确定了压下率与界面剪切强度之间的关系，结果表明，压下率为２．７３％时，可消除由１．２ｍｍ厚０８Ａｌ钢板和１．０ｍｍ厚工业纯铝构成的２．２ｍｍ厚钢－铝固液相浸镀复合板的界面附加应力，从而获得阳大界面剪切强度为８３．５ＭＰａ。     

铝钢异种金属钎焊膏的研制及其性能

为实现铝钢异种金属的焊接,研制一种新型锌基钎焊膏,并对该钎焊膏在6063铝板与Q235钢板上的铺展性能、钎焊接头力学性能以及显微组织进行研究.结果表明:随着Al元素质量分数的增加,钎焊膏在铝板与钢板上的铺展面积都不断增大,而且焊接接头中形成的金属间化合物层厚度也不断增大,但超过15%之后,由于金属间化合物层过厚,因此焊接接头力学性能降低.当Al元素质量分数为15%时,焊接接头力学性能最好,剪切强度可以达到96.8 MPa,接头断口处成分主要为Zn、Al、铝铁金属间化合物和锌铁化合物.     

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