Comparative study of embrittlement of quenched and tempered steels in hydrogen environments

The study of steels which guarantee safety and reliability throughout their service life in hydrogen-rich environments has increased considerably in recent years. Their mechanical behavior in terms of hydrogen embrittlement is of utmost importance. This work aims to assess the effects of hydrogen on the tensile properties of quenched and tempered 42CrMo4 steels. Tensile tests were performed on smooth and notched specimens under different conditions: pre-charged in high pressure hydrogen gas, electrochemically pre-charged, and in-situ hydrogen charged in an acid aqueous medium. The influence of the charging methodology on the corresponding embrittlement indexes was assessed. The role of other test variables, such as the applied current density, the electrolyte composition, and the displacement rate was also studied. An important reduction of the strength was detected when notched specimens were subjected to in-situ charging. When the same tests were performed on smooth tensile specimens, the deformation results were reduced. This behavior is related to significant changes in the operative failure micromechanisms, from ductile (microvoids coalescence) in absence of hydrogen or under low hydrogen contents, to brittle (decohesion of martensite lath interfaces) under the most stringent conditions.     

Influence of the Impaction Angle on the Triboelectric Charging of Aerosol Nanoparticles

A low pressure impactor is used to measure triboelectric charging behavior of metallic nanoparticles. Ag nanoparticles, produced by spark discharge, were impacted onto Pt sputtered targets. The influence of the impaction angle and impaction velocity on the triboelectric charging was investigated. While for perpendicular impaction the charge transfer behavior of previous work was confirmed, the oblique impaction revealed new phenomena. Additional charge transfer was observable, which increases with obliqueness. The possibility of mass transfer between particle and target due to the high-energy collisions was also investigated. SEM characterization and Auger spectroscopy indicate mass transfer from the particle to the target surface.     

移相全桥变换器在电动汽车充电单元中的应用

分析了峰值电流控制模式下移相全桥变换器的工作原理,设计了电动汽车充电单元的串联双闭环控制器。该控制器外环主回路实时获取负载电压与输入参考电压之间的偏差,通过输入PID电压环对输出电压进行调节,其内环副回路实时计算原边控制电流与PID电压环控制输出的偏差,通过输入PID电流环对控制电流进行调节。针对当控制输入信号占空比大于50%后峰值电流变换器系统出现不稳定的问题,设计了一种斜坡补偿方法,并以PIC16F887单片机为核心,开发了一套电动汽车充电控制单元。实验结果表明,所设计的充电控制单元可以满足电动汽车的充电要求,并具有可靠性高、动态响应快、补偿网络易实现以及带宽增益较高等优点。     

层拉平技术在地震解释中的深化应用

从地震解释角度看，层拉平是一种古地表重建技术。由于技术本身的局限性，地震层拉平无法精确恢复倾斜地层厚度、压实地层厚度和地层水平伸缩量。为此，从地震层拉平的技术原理出发，首先将该技术与其他恢复技术进行对比、分析，然后通过增加地质条件约束或对原有技术方案进行改进，最大限度地降低恢复误差对恢复结果的影响，使地震层拉平技术更好地应用于地震解释的各个环节。并得出如下结论：①在楔状层序顶、底界面夹角小于15°、地层间隔厚度小于1000m的条件下，可利用沿层切片近似代替地层切片预测薄储层； ②当不整合面上、下地层压实作用差异较小时，可先利用地震层拉平技术恢复剥蚀地层厚度，进而利用修正的残余厚度法恢复古地貌；③对于一般地区而言，恢复主成藏期的古构造形态不用再做压实校正，在提高恢复精度的同时，也增强了古构造恢复的油气地质意义；④针对构造变形不甚强烈地区，可利用地震层拉平技术近似代替平衡剖面分析构造演化。这些结论可进一步促进地震层拉平技术在油气勘探领域中的深化应用。     

鄂尔多斯盆地西南部延长组7段致密油充注影响因素分析

通过岩心观察、试油资料分析、岩石薄片鉴定、CT三维成像与主控因子分析等技术手段，研究了鄂尔多斯盆地延长组7段(长7段)致密油的源—储组合特征，明确了致密油充注的主控因素。结果表明:鄂尔多斯盆地长7段发育源夹储、源—储互层与储夹源3种源—储岩性组合类型；不同源—储岩性组合内部发育薄层、中厚层与厚层3类烃源岩；构造裂缝、层理缝与微观孔喉网络为长7段主要的源—储通道。烃源岩厚度与源—储岩性组合是影响致密油充注的主要因素，源—储通道的影响相对较弱。厚层优质烃源岩是致密油充注的物理基础，剩余压力为致密油充注的主要动力，源—储岩性组合是致密油充注的空间场所。中厚层烃源岩与源夹储及源—储互层型岩性组合发育的区域为致密油有利的充注区。     

顾及计算强度的地质矢量大数据计算域均衡分解方法研究

在地质大数据爆发式增长的背景下,本文结合目前在线大数据地图服务在实际应用中的瓶颈,针对面向地质大数据实时渲染的计算域均衡分解问题,研究了一系列的优化方案,包括矢量地图服务时间样本自动采集、矢量地图服务时间工时自动统计、矢量地图网格化、基于网格的可视域划分、多线程并行渲染,渲染结果合并等,在矢量大数据在线服务的响应速率提升方面获得了比较明显的效果。     

First experimental results of intrinsic torque on EAST

Direct measurements of the intrinsic torque profile in L-mode plasmas on the EAST tokamak have been performed using the balanced neutral beam injection. Co-and counter-current neutral beams are modulated to balance the intrinsic and externally injected torques, which result in the rotation profile close to zero and flat. The experimental results show that the intrinsic torque derived from momentum balance equations is found to be in the co-current direction, peaked in the plasma edge and negligibly small in the core.     

Investigation of the hydrogen induced cracking behaviour of API 5L X65 pipeline steel

The effect of microstructural features on the hydrogen induced cracking (HIC) susceptibility of two API 5L X65 pipeline steels were investigated by cathodic charging, hydrogen permeation and hydrogen microprint experiments. Microstructural evaluation after hydrogen charging revealed cracks at the mid-thickness (segregation zone) of both plates. However, more severe cracks were observed in the plate with higher dislocation density and residual stresses. The plate with lower plastic strain and more {111}-oriented grains had less severe cracks. Inclusions found along the crack path, comprising of Si-enriched oxides and carbides contributed to the initiation and propagation of cracks. The variation of the trapping behaviour and hydrogen diffusion through the plates were examined. The results confirmed that a higher ratio of reversible to irreversible traps contributes to increasing HIC severity in steels. Additionally, hydrogen transport through the steels was most prominent along the grain boundaries, indicating the importance of grain boundary character to HIC.     

Effects of Smart Charging of Multiple Electric Vehicles in Reducing Power Generation Fuel Cost

The high penetration of variable sources of renewable power generation will lead to operational difficulties in supply/demand balancing in the entire power system. The mass deployment of electric vehicles (EVs) and plug‐in hybrid vehicles (PHEVs) will also cause significant changes in electricity demand. Therefore, controlling and managing the charging time of EVs/PHEVs are effective approaches that are imperative for improving balancing in power system operation. We assumed travel patterns for EVs in a model of the future Tokyo power system and analyzed the power system loads, including the charging load of the EVs, under several charging control scenarios. We verified that charging time controls are substantially effective for reducing the fuel costs in the power system. Further, we found that load leveling under a multicar charging management scenario gave the best results in terms of the fuel costs in all cases.     

15/25MN立捣卧挤炭素挤压机主机装配攻关

立捣卧挤炭素挤压机采用立式捣固预压,卧式挤压,旋转料室+延长料室结构,旋转料室和延伸料室均采用过盈配合,粗加工后要进行热装,压机整体高度较高,由于厂内不具备现场安装条件,导致装配难度很大,通过工艺和装配攻关,确定合理的安装方案,制作专用工装工具,采取相应措施,保证装配精度符合要求。