Influence of nano-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-reinforced oxide-dispersion-strengthened Cu on the mechanical and tribological properties of Cu-based composites

The mechanical and tribological properties of Cu-based powder metallurgy (P/M) friction composites containing 10wt%–50wt% oxide-dispersion-strengthened (ODS) Cu reinforced with nano-Al₂O₃ were investigated. Additionally, the friction and wear behaviors as well as the wear mechanism of the Cu-based composites were characterized by scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS) elemental mapping. The results indicated that the Cu-based friction composite containing 30wt% ODS Cu exhibited the highest hardness and shear strength. The average and instantaneous friction coefficient curves of this sample, when operated in a high-speed train at a speed of 300 km/h, were similar to those of a commercial disc brake pad produced by Knorr-Bremse AG (Germany). Additionally, the lowest linear wear loss of the obtained samples was (0.008 ± 0.001) mm per time per face, which is much lower than that of the Knorr-Bremse pad ((0.01 ± 0.001) mm). The excellent performance of the developed pad is a consequence of the formation of a dense oxide composite layer and its close combination with the pad body.     

县域领导干部应该重视现代农业产业技术创新战略联盟的发展

在我国产学研合作深入发展及农业现代化快速发展的重要阶段,构建和发展农业产业技术创新战略联盟是提升我国农业产业国际竞争力的有效途径。本文梳理了近年来我国在产业技术创新战略联盟的政策文件,揭示了发展农业产业技术创新战略联盟的必要性和意义,总结了我国农业产业技术创新战略联盟发展中存在的问题,最后,提出了农业产业技术创新战略联盟发展的对策建议。     

组合拍卖在土地出让中的应用

针对现有土地出让方式无法满足开发商需求不同土地组合的问题,基于机制设计理论以及组合拍卖思路与方法,建立了关联价值下的最优土地组合拍卖机制设计模型,通过求解该模型得到了具体的最优拍卖机制。该机制不仅允许开发商对不同土地的组合投标,还能激励开发商披露其对土地组合的真实估值信号,并在此基础上实现政府期望收益最大化,从而促进土地的合理配置。算例分析表明,所提出的最优组合拍卖机制具有计算简单、可操作性强等优点。     

Interfacial characteristics and properties of a low-clad-ratio AA4045/AA3003 cladding billet fabricated by semi-continuous casting

A low-clad-ratio AA4045/AA3003 cladding billet was fabricated using a semi-continuous casting process and was subsequently extruded indirectly into a cladding pipe. The temperature distribution near the interface was measured. The microstructures, elemental distribution, Vickers hardness around the bonding interface, and the interfacial shear strength were examined. The results showed that the interface temperature rebounded when AA4045 melt contacted the supporting layer. The two alloys bonded well, with few defects, via the diffusion of Si and Mn in the temperature range from 569°C to 632°C. The mean shear strength of the bonding interface was 82.3 MPa, which was greater than that of AA3003 (75.8 MPa), indicating that the two alloys bonded with each other metallurgically via elemental interdiffusion. Moreover, no relative slip occurred between the two alloys during the extrusion process.     

给定限界势结构生成算法的改进

寻求最优联盟结构是NP-完全的,建立限界k=n/2的最小搜索是搜索联盟结构图的最底二层及顶层,在最小搜索之后,不同算法采用不同的搜索单位和路径进行有选择地部分搜索,以尽快达到给定限界值。在实际应用中,充分利用同势的两个联盟同值或值相差不大的特征,研究最优势结构生改进算法效率。文中通过分析势结构间的关系,指出了给定限界的势结构生成算法中一些可以去除的冗余搜索集合,从两个方面改进了算法,并进行了相关结果的证明。     

地方高师院校人才培养质量监控体系研究——基于利益相关者理论视野

人才培养质量是高等学校的生命线.完善人才培养质量监控体系、努力提高教师教育的质量和水平,是当前地方高师院校必须着力解决的重要问题.从利益相关者理论出发,深度剖析当前地方高师院校现有质量监控体系建设在目标系统存在偏差,组织系统、监督系统、评价系统、管理制度系统均存在参与主体缺位,监督系统存在监督范围过于狭窄等五方面的不足,从坚持立德树人、全面贯彻党的教育方针,坚持多元主体监控、构建利益相关者全员参与的质量监控体系,坚持全面监控、构建利益相关者全过程参与的质量监控体系等五方面给予完善.     

一类带有反应扩散项和非单调功能反应函数的食饵-捕食系统的Turing不稳定性

研究了带有反应扩散项和非单调功能反应函数的食饵-捕食系统,分析了系统的局部稳定性,并且推导出了系统空间齐次和非齐次常数平衡解Turing不稳定的精确的参数范围.应用数值模拟进一步说明了理论推导的正确性.     

探索生产实习新模式 培养电科专业高素质人才

生产实习是所有工科高校中培养理论联系实践的高素质人才的重要环节,而生产实习的模式将直接影响学生对理论知识的理解及其理论与实际相结合的认识.针对目前本专业在生产实习过程中存在问题的分析和对国内外多所高校实习模式的调研,详细地探讨了与本专业相关的生产实习模式及其改进的方法,除了需要进一步加强校外实习,还提出了校外实习与校内实习相结合、成立专职教师队伍、引入工程类"project"项目等改革方案,根据学生对专业理论知识掌握及自身兴趣的不同,提出了分层次、分类别实习的模式,由此进一步提高学生的工程实践能力,增强其创新意识.     

网络环境下高校大学生深度阅读策略

深度阅读是对处在当今信息化社会、快节奏生活方式的人们提出的一个很难贯彻落实到日常生活中的高要求。因为方便快捷的移动式和电子化阅读的普遍适用,在此网络环境的消极作用下,现在各大高校图书馆的纸质化阅读规模和借阅数量较之前有了很大的缩减,因此,对高校图书馆提出促进深度阅读工作开展的要求也是严格的。本文主要针对目前高校大学生阅读现状进行了分析和探讨,在此基础上提出了高校图书馆助力深度阅读的策略。     

Experimental determination of significant waveheight by OSMAR071: Comparison with results from buoy

OSMAR071 is the latest product of the OSMAR (ocean state monitor and analysis radar) series of high frequency surface wave radar (HFSWR), which was developed by the Radiowave Propagation Laboratory of Wuhan University. It adopts a modified Barrick waveheight inversion model. The modifications are introduced to improve the model’s performances under the effect of noises and interferences and in the case of broad beam radar detection. The two unknown coefficients in the modified model are figured out by fitting the HFSWR significant waveheight results to those output from a wave buoy located in the radiating coverage of the radar site. The model is applied to inverse the waveheights from radar data for the duration from Dec. 1st, 2008 to Feb. 25th, 2009, and then the radar waveheights are compared with the buoy measurements. Results show that the rms difference between radar-derived significant waveheights and those from the buoy is 0.38 m and the correlation coefficient between the two series is 0.66. This study describes OSMAR071 observation of significant waveheight with relatively satisfactory accuracy during about three months.