舰船保障物资优化分配方法研究*

论文针对实际应用中舰船保障物资分配的需求,提出了动态态势物资分配优化方法,建立了动态态势物资分配优化数学模型,即混合0‐1整数规划模型并提供了求解策略。同时利用项目管理方法,提出了保障物资分配项目实施方案的优化流程。     

TiAl合金汽车气门

介绍了ＴｉＡｌ基合金的力学性能和用该合金生产汽车发动机气门的各种方法的优缺点，认为金属模铸工艺是一种低成本的有潜力的方法，并从价格方面分析了ＴｉＡｌ基合金气门的应用前景。     

城市交通信息系统规划研究

针对我国城市交通面临的巨大挑战,从规划及政策手段、工程设施建设手段、运行管理手段并运用信息技术、通信技术、控制技术等对传统交通运输系统进行改造,从而提高系统的运行效率。     

高速公路检测中需要注意的问题

随着我国交通业的发展,各类高速公路工程也大量的开展起来,这种情况下,做好高速公路的质量检测就显得至关重要。结合工作经验,对高速公路的监测问题进行分析,从路基工程检测手段和重点内容、路面检测手段和重点内容、附属建筑检测手段和重点内容等几个方面,对高速公路的监测中需要注意的问题进行论述,以期推动我国高速公路质量监测水平的发展。     

Improvements of elevated temperature strength and creep resistance of Mg-12Zn-4Al based alloy with calcium addition

A series of Mg-12Zn-4Al-0.3Mn (ZA124) based alloys with additions of calcium have been prepared and their microstructure and properties have been investigated. The results show that Mg-12Zn-4Al-0.3Mn alloy consists of the ??-Mg matrix and block quasicrystal and exhibits excellent creep resistance compared to commonly used AZ91 alloy. A small amount of calcium addition to the ZA124 based alloys increased the yield strenghth at both ambient and elevated temperatures as well as creep resistance, although the ductility decreased slightly. Microanalysis indicated that the addition of calcium decreased the quasicrystalline phase and caused the formation of some lamellar precipitates of Al₂Mg₅Zn₂ with orthorhombic crystal structure. This Ca-containing Al₂Mg₅Zn₂ phase with high stability straddled the grain boundaries and strengthened grain boundaries by inhibiting crack propagation during creep tests at elevated temperature.