Investigation on compressive behavior of Cu-35Ni-15Al alloy at high temperatures

Microstructures and mechanical properties of Cu-35Ni-15Al alloy in cast and porous states were studied by scanning electron microscopy and compression tests. The influence of porosity, deformation temperature and loading rate on mechanical properties of the two kinds of alloys was investigated. The results show that the as cast alloy and porous alloys have almost the same phase constitution: Cu rich phase, Ni rich phase and K intermetallics. The yield strength of porous alloys increases continuously with decreasing porosity, the relationship between porosity and yield stress follows Gibson-Ashby equation. With decreasing deformation temperature, the yield strength of as cast alloy and porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend. After compression, the microstructure of as cast alloy is more uniform, and porous alloys are more prone to have localized deformations.     

天津美术馆空调系统设计探讨

根据建筑内部空间特点,以保证工作区空调效果的空调系统节能为出发点,采用CFD模拟分析软件,对比研究了不同空调风系统与气流组织形式对体积较大但空间冷热负荷指标较低的高大展厅以及步进式序厅共享空间的适应性;通过对空调区域正压平衡风量的分析计算,指出了GB 50189-2005第5.3.14条关于排风热回收规定对于艺术类展览...     

Influence of oxygen content on the crystallinity of MgO layers in magnetic tunnel junctions

With RF sputtering process, Si/Si02/Ta/Ru/Ta/CoFeB/MgO/CoFeB/Ta/Ru structure has been grown on Si （100） substrate. Attempting different targets and adjusting the oxygen dose, the crystallization quality of the MgO layer is studied. The X-ray diffraction measurements demonstrate that crystal structure and crystallization quality of MgO layers are related to the type of target and concentration of oxygen in sputtering process. With the method sputtering Mg in an ambient flow of oxygen, not only the crystallization quality of a normal MgO layer with lattice constant of 0.421 nm is improved, but also a new MgO crystal with lattice constant of 0.812 nm is formed and the perpendicular magnetic anisotropy of CoFeB is enhanced. Also it is found that crystallization quality for both the normal MgO and new MgO is more improved with MgO target and same oxygen dose, which means that this new method is helpful to form a new structure of MgO annealed at 400 ℃ in vacuum. with lattice constant of 0.812 nm. All of the samples were     

甜型黄酒发酵过程中的生物和化学成分性质研究

对甜型黄酒发酵过程中微生物和化学成分的变化规律进行了研究。通过对糖化酶活力、酵母菌总数、淀粉残留量、总糖、还原糖、总酸、氨基态N、氨基酸、酒精度、感官品质、可溶性固形物等生化指标的定期观察、检测,总结出在甜型黄酒发酵过程中微生物和化学成分的变化规律,并分析、讨论甜型黄酒生产中各工艺过程,有助于改进现代化甜型黄酒生产的工艺。     

黄浦南汊桥风致抖振疲劳频域分析

提出了在频率域内用Markov过程进行大跨度桥梁风致抖振疲劳分析的计算方法.以黄浦南汊桥为例,用不同的方法对其进行了疲劳分析.其初步计算结果表明,本文提出的方法是可行和有效的.     

端锚预应力CFRP板加固混凝土梁的施工技术研究

介绍预应力CFRP板加固钢筋混凝土梁的施工工艺和技术,包括预应力CFRP板的张拉设备、加固施工流程和技术要点等,利用自行研制的预应力CFRP板配套锚具,完成了6根预应力CFRP板加固钢筋混凝土梁的受弯试验。结果表明：与非预应力CFRP板加固方法相比,可提高构件的受弯承载力和抗裂度,该加固技术可直接应用于实际工程。     

变电站35kV系统电弧光保护的设计与应用

高载能变电站35 kV系统易发生近端短路故障,伴随产生电气弧光,导致故障范围扩大,危害设备安全。针对上述问题,在采用电压、电流作为保护动作判据的基础上,引入电弧光保护装置作为保护动作判据,并对电弧光保护系统的3种配置方案进行比较分析,认为方案1中主单元包含电流闭锁单元,通信采用光纤,较为合理。将方案1应用于某变电站,弧光保护装置可以捕捉到电气弧光,可保护35 kV母线、开关柜安全,提高了供电可靠性。     

三辊连轧管机的结构发展及对比

介绍了三辊连轧管机的结构发展情况,对比分析了轴向换辊、侧向换辊和双侧换辊3种换辊方式的共同点与差异性,以及3种换辊方式连轧管机的主要技术参数,并对PQF与FQM连轧管机轧制机架的差异部分进行了阐述。从应用情况来看,小规格钢管生产机组采用轴向和侧向换辊两种方式都可;大规格钢管生产机组都选用轴向换辊方式。     

基于壳牌标准的螺旋埋弧焊管超声波探伤设备改造

为了实现大壁厚螺旋埋弧焊管焊缝超声波探伤100%覆盖扫查,对螺旋埋弧焊管自动超声波探伤的几种标准进行了对比,重点分析了壳牌管线钢管标准DEP 31.40.20.37－Gen与其他标准不同之处,以及对螺旋埋弧焊管自动超声波探伤设备的要求,明确了不同壁厚钢管执行壳牌标准时焊缝探架上每个探头的作用和焊缝探伤的区域。针对目前螺旋焊管自动超声波探伤设备执行壳牌标准存在的问题提出了设备改造方案。设备改造后,超声波探伤能力得到了提高,钢管焊缝质量得到了保证。