冲击倾向煤样在不同应变率载荷作用下破裂的声发射及碎片分形特征

现有研究针对岩石受载破坏过程的声发射特征和试件碎片分形特征进行了相关分析，并取得了一定成果，但针对冲击倾向煤样在不同应变率单向受载条件下破坏程度的定量描述及与加载应变率定量关系的研究较少。针对该问题，基于MTS−C64.106型电液伺服系统对原煤试件在单轴静态载荷基础上施加不同应变率载荷试验，试验中采用PCI−2卡型声发射卡对试件受载破裂过程开展实时监测，同时应用分形理论对试件破裂碎片进行处理分析，定量评价试件破碎程度及与载荷应变率的关系。结果表明：① 在静态载荷基础上，试件破坏的峰值强度随着应变率动载荷的升高而逐渐上升。② 随着加载应变率增大，声发射总体数量减少，高能声发射事件增多，声发射振铃计数和能量幅值经历缓增−急增−突增的一致转变过程。③ 试件受载的能量输入速率与声发射振铃计数、内部撞击数增长趋势基本一致，即也会经历缓增−急增−突增的变化。④ 声发射与震动强弱正相关的常数随加载应变率增大而减小，与高低能震动数之比负相关的常数随加载应变率增大而增大；原煤试件的破坏模式会发生剪切破坏−劈裂破坏−爆裂破坏的转变。⑤ 当加载应变率较低时，试件主要是上半部分破坏，应变率增大后由试件中部逐渐向下半部分延伸破坏，原煤试件在动载应变率作用下的破坏过程主要是裂纹的脆性扩展行为。⑥ 试件冲击碎片质量分维与加载应变率呈二次函数关系，即存在加载应变率极值使试件破坏程度达到最大，试验显示该值为2.8×10−3 s−1

Optimization of a combined reheating/regenerative/internal regenerative organic Rankine cycle based on exergy analysis

A combined reheating, regenerative and internal regenerative organic Rankine cycle（CRORC） is put forwarded for the utilization of low grade thermal energy, which consists of a reheat, a mixing chamber and an internal heat exchanger in addition. R245 fa i

基于Pro/E Mechanica的农业机械用链轮的动力学分析

链传动由于其传动可靠、结构简单,在农业机械中获得广泛应用。在工厂化水产养殖中应用的链斗式过滤装置中,作为链传动中关键零件,链轮受到工作环境恶劣、复杂载荷等因素影响,齿根磨损严重而失效。为增加链轮寿命、减少应力集中,利用Pro/E平台建立链轮的三维模型,并应用Pro/E Mechanica进行动力学分析,进行链轮设计的结构优化,在减轻其重量的同时,使链轮受力基本均匀,减少应力集中和变形。通过对链轮做全局敏感度分析表明:齿顶圆弧半径的增加削弱了最大应力的增长;最大应力随凸缘直径的增加而减小。最后以质量最小为目标函数对两个重要参数在合理范围内进行优化得到的最佳设计:当齿顶圆弧直径与凸缘直径分别为14mm、54.952 3mm时,模型质量最小为3.408kg,模型的质量减少了4.48%

基于Pro/E Mechanica的农业机械用链轮的动力学分析

链传动由于其传动可靠、结构简单,在农业机械中获得广泛应用。在工厂化水产养殖中应用的链斗式过滤装置中,作为链传动中关键零件,链轮受到工作环境恶劣、复杂载荷等因素影响,齿根磨损严重而失效。为增加链轮寿命、减少应力集中,利用Pro/E平台建立链轮的三维模型,并应用Pro/E Mechanica进行动力学分析,进行链轮设计的结构优化,在减轻其重量的同时,使链轮受力基本均匀,减少应力集中和变形。通过对链轮做全局敏感度分析表明:齿顶圆弧半径的增加削弱了最大应力的增长;最大应力随凸缘直径的增加而减小。最后以质量最小为目标函数对两个重要参数在合理范围内进行优化得到的最佳设计:当齿顶圆弧直径与凸缘直径分别为14mm、54.952 3mm时,模型质量最小为3.408kg,模型的质量减少了4.48%

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies