Study on dislocation density,microstructure, and mechanical properties of P92 steel for different heat treatment conditions

The impact of various heat treatment procedures on microstructure, dislocation density, hardness, tensile characteristics, and impact toughness of P92 steel was examined in the current experiment. The martensitic microstructure and average microhardness of 463 HV 0.2±8 HV 0.2 of the normalized steel were prevalent. A tempering procedure was carried out at 760 °C for a range of 2 hours to 6 hours. Additionally, an X-ray diffraction examination was carried out, and the results were used to determine the dislocation density. The normalized sample was characterized by a high dislocation density. The dislocation density was decreased by tempering of normalized samples. With an increase in tempering time, the effect of the treatment coarsened the grains, precipitates, and decreased the area fraction of precipitates. After tempering, MX, M₂₃C₆, and M₇C₃ types precipitates were found to have precipitated, according to energy dispersive spectroscopy and x-ray diffraction research. The ideal tempering period was determined to be 4 hours at a tempering temperature of 760 °C based on the microstructure and mechanical characteristics. Steel that was tempered at 760 °C for 4 hours had a yield strength of 472 MPa, an ultimate tensile strength of 668.02 MPa, and an elongation of 26.05 %, respectively.     

三峡水电站坝内埋管非线性有限元分析

结合三峡工程实际,对坝内埋管结构进行了非线性有限元分析,着重研究了不同管顶混凝土厚度和配筋对管道结构应力和强度的影响．计算结果表明,增大管顶混凝土厚度,可以明显提高坝内埋管的抗裂安全,确保混凝土大坝的整体稳定性,但是配筋多少对管周混凝土的抗裂能力影响较小．     

电站 F/A 异种钢接头早期失效及其防治措施

扼要归纳了Ｆ／Ａ异种钢接头早期失效的特征,分析了导致早期失效的因素,提出可用焊后高温回火和适当增加铁素体侧坡口角的办法降低钢１０２／Ｉｎｃｏｎｅｌ１８２／ＴＰ３４７Ｈ接头的早期失效倾向．文章列出的高温持久强度试验、高温承载加速模拟试验、残余应力测试等结果以及热应力的有限元分析都证明了上述措施是有效的．     

特细砂自流密实砂浆

探讨了特细砂砂浆流动度和含砂率对特细砂砂浆自流密实能力的影响,提出用强度比表示特细砂砂浆的自流密实能力,目的在于充分发挥特细砂砂浆的自流密实能力,节约水泥．     

火箭弹壳体强度的计算机辅助分析

研究了用计算机进行火箭弹受载及壳体强度计算;建立了适合于对火箭弹进行强度计算的模型;编制了相应的计算程序．程序可靠、使用方便,可以满足对火箭弹以及其它空中飞行体进行强度计算的要求．     

电镀塑料制品对结构设计及成形工艺的要求

为保证电镀塑料制品的质量,提出了符合电镀要求的塑料制品设计原则,并且指出在注塑成形时,对塑料经过充分干燥,采用较高的注塑温度,较低的注射压力和较慢的注射速度,是使镀层获得良好结合强度的先决条件。     

双悬臂梁式光纤Bragg光栅位移传感器

位移测量装置利用测量杆通过楔形块作用在固定于底座的等强度悬臂梁上,其中,光纤Bragg光栅粘贴于其中一块等强度悬臂梁外表面的中心线处。在测量中,当测量杆产生位移时,会带动楔形块产生相应的位移,并促使等强度悬臂梁的自由端产生扰度变化,从而导致粘贴于等强度悬臂梁外表面的光纤Bragg光栅产生波长移位。实验表明,当位移增加或者减少时,位于中心测点的光纤Bragg光栅的实验灵敏度分别为正行程0.015nm/mm,反行程为0.014nm/mm,重复性误差为2.2%;正行程的线性度为0.99728,反行程的线性度为0.99684,迟滞为0.0626%FS。     

Signal strength based routing for power saving in mobile ad hoc networks

The transmission bandwidth between two nodes in mobile ad hoc networks is important in terms of power consumption. However, the bandwidth between two nodes is always treated the same, regardless of what the distance is between the two nodes. If a node equips a GPS device to determine the distance between two nodes, the hardware cost and the power consumption increase. In this paper, we propose using a bandwidth-based power-aware routing protocol with signal detection instead of using GPS devices to determine the distance. In our proposed routing protocol, we use the received signal variation to predict the transmission bandwidth and the lifetime of a link. Accordingly, the possible amount of data that can be transmitted and the remaining power of nodes in the path after data transmission can be predicted. By predicting the possible amount of data that can be transmitted and the remaining power of nodes after data transmission, we can design a bandwidth-based power-aware routing protocol that has power efficiency and that prolongs network lifetime. In our simulation, we compare our proposed routing protocol with two signal-based routing protocols, SSA and ABR, and a power-aware routing protocol, MMBCR, in terms of the throughput, the average transmission bandwidth, the number of rerouting paths, the path lifetime, the power consumed when a byte is transmitted, and the network lifetime (the ratio of active nodes).     

无线传感器网络改进型节点定位算法的研究

无线传感器网络节点位置信息对于事件监测起到至关重要的作用,节点定位技术是无线传感器网络应用的支撑技术之一。为了提高无线传感器网络节点定位的精度,同时减少定位计算过程中的能耗,在RSSI,HCRL定位机制分析的基础上提出了一种改进型的节点定位算法:接收信号强度比定位算法(RSS-RL),通过仿真试验显示:RSS-RL定位算法不仅降低了节点定位复杂度,而且,提高了定位精度。     

基于功率MOSFET的激光器外触发系统研制

采用功率MOSFET及其驱动器和光纤收发器件,研究了激光触发开关脉冲功率源控制技术中的快上升沿(≤5ns)触发信号产生、驱动、传输及光纤隔离、高耐压脉冲变压器使用等关键技术。给出了激光器外触发控制电路的设计及测试结果,并对其应用特点进行了分析和讨论。