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.研究结果表明:在300 ℃钎焊90 s后,AuSn/(Ni/AlSi)焊点形成细小的层状(ζ-Au5Sn)+(δ-AuSn)共晶组织和针状的(Ni,Au)3Sn2相.焊点在200 ℃固相老化退火不同时间后,共晶组织明显粗化,焊料/基体界面处形成(Au,Ni)Sn+(Ni,Au)3Sn2复合金属间化合物(IMC)层,且随退火时间延长逐渐增大.退火时间达1 000 h时,在(Ni,Au)3Sn2/Ni界面处产生(Ni,Au)3Sn相.当退火时间小于300 h时,焊点剪切强度随退火时间延长逐渐降低,断裂形式主要是发生在焊料/IMC界面的脆性断裂.退火时间继续延长剪切强度基本不变,断裂主要发生在IMC内部,而且从断裂模型沿晶断裂转变为穿晶断裂. 关键词:AuSn/(Ni/AlSi)焊点;固相老化退火;金属间化合物(IMC);脆性断裂 中图分类号:TG156.21  ......
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J. Cent. South Univ. (2017) 24: 2940-2950 DOI: https://doi.org/10.1007/s11771-017-3708-1 Energy analysis of rock plug thickness in karst tunnels based on non-associated flow rule and nonlinear... tunnel face. Therefore, it is a pivotal issue to determine the reserved thickness of rock plug during the construction of tunnels. The limit analysis principle is employed to analyze the safe thickness......
RCT-β Thickness Gauge Has Been DevelopedH.X.F.摘 要:<正> The RCT-β thickness gauge is a non-contact type instrument used for measuringthickness,which... degree of the attenuation in the intensity of the β-ray corresponds to the thick-ness of the material.The β-ray thickness gauge basing on this principle has been developed,whichis used to measure......
IMC耦合PID的节流阀控制的汽车稳定性研究张柏军1,杜峰2,刘元伟31. 潍坊科技学院汽车工程学院2. 山东科技大学交通工程学院3. 中国矿业大学机电工程学院摘 要:扭矩精确控制对汽车运行过程中稳定性具有重要影响.针对汽车扭矩控制的精确度不高的问题,提出了基于内膜控制(IMC)和比例积分控制(PID)相结合汽车牵引力控制系统.通过分析汽车运动过程,构建牵引力动力学模型,以发动机扭矩控制为基础,设计MIC-PID控制器,对控制增益进行整定,实现对发动机节流阀开启角度的控制,确保汽车行驶过程中保持最优的滑移率.仿真实验表明:汽车在湿沥青和积雪道路上,提出的控制方式能够有效的降低司机控制指令,从而有效的控制汽车滑移率.说明该方法能够提高汽车牵引控制控制精度和效率,维持汽车的稳定性.关键词:牵......
Finite element analysis on stresses field of normalized layer thickness within ceramic coating on aluminized steel WU Zhen-qiang(吴振强), XIA Yuan(夏 原), LI Guang(李 光), XU Fang-tao(徐方涛) Institute... dipping aluminum(HDA) and plasma electrolytic oxidation(PEO). A triangle of normalized layer thickness was created for describing thickness ratios of HDA/PEO coatings. Then, the effect of thickness......
J. Cent. South Univ. (2016) 23: 581-597 DOI: 10.1007/s11771-016-3105-1 IMC based robust pid controller tuning for disturbance rejection Mohammad Shamsuzzoha Department of Chemical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia Central South University Press and Springer-Verlag Berlin Heidelberg 2016 Abstract: It is well-known that the IMC-PID......
基于改进IMC的开环不稳定时滞过程控制朱宏栋,邵惠鹤摘 要:针对开环不稳定对象,在传统内模控制结构中增加了一个预稳定控制器,提出了改进的内模控制结构,给出了闭环系统内稳定判定定理;更重要的是提出一个综合闭环性能和相角裕度的指标函数,将该指标函数最大化,可获得在不同归一化时滞情况下的优化预稳定控制器整定参数,并拟合出公式.最后,与国际上最新发表的控制方法进行了对比,显示了该方法的优越性.关键词:不稳定时滞过程;改进内模控制;优化整定;......
基于改进IMC的磁头微焊点寿命预测模型研究肖祥慧1,唐荣军2,周影良21. 佛山科学技术学院自动化学院2. 日本TDK集团(SAE)摘 要:磁头无铅微焊点寿命预测方法主要采用疲劳模型,由于磁头焊点十分小,传统的寿命预测方法很难取得较好效果,本文融合金属间化合物生长动力学理论,提出了一种新的用于预测磁头无铅微焊点寿命的生长模型.对比结果表明,新模型预测磁头无铅微焊点寿命与实际结果更加接近.关键词:磁头;微焊点;寿命预测;模型;......
J. Cent. South Univ. (2016) 23: 2346-2353 DOI: 10.1007/s11771-016-3293-8 Minimum safe thickness of rock plug in karst tunnel according to upper bound theorem YANG Zi-han(杨子汉), ZHANG Jia-hua(张佳华... ahead of a karst tunnel face tend to cause geological disasters, such as water and mud bursts. So, the determination of safe thickness of the reserved rock plug is a key technical problem to be solved......