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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Effects of annealing temperature on the microstructure and properties of the 25Mn-3Si-3Al TWIP steel 总被引:3,自引:0,他引:3
Microstructures and mechanical properties of the 25Mn twinning induced plasticity (TWIP) steel at different annealing temperatures were investigated. The results indicated that when the annealing temperature was 1000°C,the 25Mn steel showed ex-cellent comprehensive mechanical properties,the tensile strength was about 640 MPa,the yield strength was higher than 255 MPa,and the elongation was above 82%. The microstructure was analyzed by optical microscopy (OM),X-ray diffraction (XRD),and transmission electron... 相似文献
992.
A new hydraulic system of a novel automatic transmission (AT) was designed. The dimension and structure of valves and cylinders
were designed by theoretical calculation. The dynamic simulation model of hydraulic system of AT was established by ITI-SimulationX.
Simulation results and theoretical design results were compared to confirm the simulation model. Based on the confirmed simulation
model, the simulation results of pressure and flow of the hydraulic system were analyzed. The dynamic simulation method is
very helpful for designing and analyzing the performance of hydraulic system and further optimization design. The theoretical
design method and dynamic simulation model are feasible for the real industrial applications. The research results can be
used in hydraulic system design and optimization.
Foundation item: Project(911901204) supported by Youth Innovation Foundation of Beijing University of Aeronautics and Astronautics 相似文献
993.
The experimental tests of tensile for lead-free solder Sn-3.5Ag were performed for the general work temperatures range from
11 to 90 °C and strain rate range from 5×10−5 to 2×10−2 s−1, and its stress—strain curves were compared to those of solder Sn-37Pb. The parameters in Anand model for solder Sn-3.5Ag
were fitted based on experimental data and nonlinear fitting method, and its validity was checked by means of experimental
data. Furthermore, the Anand model was used in the FEM analysis to evaluate solder joint thermal cycle reliability. The results
show that solder Sn-3.5Ag has a better creep resistance than solder Sn-37Pb. The maximum stress is located at the upper right
corner of the outmost solder joint from the symmetric center, and thermal fatigue life is predicted to be 3.796×104 cycles under the calculated conditions.
Foundation item: Project(50376076) supported by the National Natural Science Foundation of China 相似文献
994.
Electromagnetic emission (EME) is a kind of physical phenomenon accompanying the process of deformation and frac-ture of loaded coal and rock and it is of importance in quantitatively analyzing its characteristics. This will reveal the process of deformation and fracture of coal and predicting dynamic disasters in coal mines. In this study, the G-P (Grassberger and Procaccia) algorithm, calculation steps of the (if only 1 dimension) correlation dimension of time series and the identification standards of chaotic signals are introduced. Furthermore, the correlation dimensions of EME and the acoustic emission (AE) signals of time series during deformation and fracture of coal bodies are calculated and analyzed. The results show that the time series of pulses number of EME and the time series of AE count rate are chaotic and that the saturation embedding dimensions of a K3 coal sample are, respectively, 5 and 6. The results can be used to provide basic parameters for predicting of EME and AE time series. 相似文献
995.
高校科研团队建设已成为全面提高高校科研工作水平的重要环节,日益成为科学研究的基本组织形式。本文从"投入—转化—产出"的视角对高校科研团队的组织系统的运行机理、内外部因素和核心(动力)因素进行了较详尽的剖析,然后运用组织系统权变理论构建了线性模式、星型模式、平行模式、联邦模式、分布模式和虚拟模式共六种不同的高校科研团队组织模式,对高校科研团队建设的理论与实践有着一定的理论价值和现实意义。 相似文献
996.
远程虚拟实验室数据库的设计及访问 总被引:1,自引:0,他引:1
在基于LabVIEW的虚拟实验室平台中,引入数据库管理系统可以更加有效、安全地对用户、仪器设备和实验数据等进行管理。运用SQL Server2000设计了远程虚拟实验室平台的数据库系统,并借助LabSQL工具包实现了LabVIEW远程虚拟仪器程序对数据库的访问及操作. 相似文献
997.
998.
精度控制是反求实践研究的一项重要内容.论文分析了精度控制的必要性,给出了精度误差的评价标准,通过对打纬共轭凸轮反求实践中各环节的精度控制,有效的控制了反求误差,实现了凸轮的高精度反求,提高了凸轮反求的品质. 相似文献
999.
单柔体动力学是多柔体动力学的基础,把单柔体动力学的理论研究好了,多柔体动力学的理论也就水到渠成了;另外,单柔体动力学还有它独特的重要应用.文章应用简捷的方法,建立了非保守单柔体动力学的卷积型拟变分原理,推导了非保守单柔体动力学的卷积型拟变分原理的拟驻值条件.以弹性拦截器为例说明了变形速度对弹性单体运动轨迹和运动姿态的影响,研究了弹性单体的动力特性.讨论了解析法与数值法的互补特性. 相似文献
1000.