关键词： Hydrogen storage   TiFe alloy   Metal hydride   Ball milling   Cold rolling  

摘要： In this paper, effect of air exposure on first hydrogenation kinetics of TiFe +4 wt% Zr + 2 wt % Mn alloy was studied. After 7 days of air exposure, the first hydrogenation kinetics of the alloy was slow with a long incubation time. An air exposure of 30 days made the alloy totally inert to hydrogen. In an attempt to recover the hydrogen absorption ability of the alloy, it was mechanically treated using cold rolling and ball milling processes. It was found that the air exposed alloy could be successfully hydrogenated after ball milling and after cold rolling with some loss in hydrogen storage capacity. The loss in storage capacity was more important after ball milling than after cold rolling. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Graphene   nanocomposites   molecular dynamics (MD) simulation   Halpin_Tsai semi-empirical micromechanical model   mechanical properties  

摘要： In this study, the mechanical properties of graphene-epoxy nanocomposites were investigated using experimental tests, molecular dynamics (MD) simulation and Halpin_Tsai semi-empirical micromechanical model. To fabricate graphene/epoxy nanocomposite, specimens containing 0, 0.3, 0.5 and 0.7 weight percent (wt.%) of graphene nanoparticle (GNP), high power dispersion sonicating method and high-speed shearing were employed. Then, tensile and flexural modulus of manufactured nanocomposites were obtained, and the results illustrated that the elastic and flexural modulus of GNP/epoxy nanocomposites increased significantly until GNP was added up to 0.5 wt.% and after that, the trend of increasing elastic modulus declined which could be due to local GNP agglomerations within the nanocomposites with higher contents of filler. Furthermore, graphene, epoxy and graphene-epoxy nanocomposites were simulated by MD, and the mechanical properties of simulated graphene-epoxy nanocomposites were calculated. However, the effect of temperature and strain rate on tensile properties of graphene-epoxy nanocomposites was studied, which showed that increasing temperature decreased the strength of graphene-epoxy nanocomposites, and also increasing the strain rates led to an increase in the elastic modulus. Finally, experimental results and the Halpin_Tsai model were compared in which a good agreement between experimental and analytical results was observed.

关键词： assisted circulation   catheterization   hemodynamics   shock   cardiogenic  

摘要： The recent widespread availability and use of mechanical circulatory support is transforming the management and outcomes of cardiogenic shock (CS). Clinical decision-making regarding the optimization of therapies for patients with CS can be guided effectively by hemodynamic monitoring with a pulmonary artery catheter (PAC). Because several studies regarding the benefit of PACs are ambiguous, the use of PACs is variable among clinicians treating patients with CS. More notable is that PAC use has not been studied as part of a randomized, controlled trial in patients with CS with or without mechanical circulatory support. Standardized approaches to hemodynamic monitoring in these patients can improve decision-making and outcomes. In this review, we summarize the hemodynamics of CS and mechanical circulatory support with PAC-derived measurements, and provide a compelling rationale for the use of PAC monitoring in patients with CS receiving mechanical circulatory support.

关键词： Bowen病   手部   机械磨削术   氨基酮戊酸   光动力疗法  

摘要： 目的:探讨机械磨削术联合氨基酮戊酸光动力疗法(ALA-PDT)治疗手部Bowen病疗效。方法:10例经病理确诊的手部Bowen病患者,均行机械磨削术联合ALA-PDT治疗。磨削时从外向里进行磨削,磨至弥漫性出血为止。后将氨基酮戊酸配成20%溶液涂于皮损及外周0.5cm,3~4h后行635nm红光照射,能量密度为80~100J/cm2,时间20min,每周照射1次,共3次。6个月后观察肿瘤有无复发,患者满意度及瘢痕形成等情况。结果:10例患者行机械磨削联合ALA-PDT治疗后,至少随访6个月,均未见肿瘤复发;10例患者均非常满意,治疗后无明显瘢痕增生。结论:机械磨削术联合ALA-PDT治疗手部Bowen病安全高效,痛苦小,创伤轻,患者满意度高,无明显瘢痕形成,值得临床推广。

关键词： 农业机械总动力   空间分布   演变特征   相关性  

摘要： 运用ArcGIS空间分析探究2000-2017年中国9大农业区农业机械总动力水平的空间分布,从省域层面分析各省(自治区、直辖市)(香港、澳门、台湾除外)地均农业机械总动力空间分布的演变特征,并运用皮尔逊(Pearson)相关性分析探究耕地变化和第一产业增加值变化与农业机械总动力变化的相关性。结果表明:2000-2017年,中国农业机械总动力水平快速提升,整体由"一强多弱"向"多强并存"格局演变,但省域发展不均衡,存在较明显的空间差异。农业机械总动力与第一产业增加值变化的相关系数为0.735,说明农业机械总动力的增长会带动第一产业增加值的提高,与耕地变化的相关系数为0.478。

关键词： 锚杆钻机   机械臂   动力学方程   算法及相应程序  

摘要： 矿用锚杆钻机是锚杆支护作业中专门用于实现钻凿锚杆孔、锚杆安装并紧固锚杆的设备。该设备的主要工作部分是2个智能机械臂。基于拉格朗日理论推导出了机械臂的动力学模型,并且根据动力学方程的简化原则对函数进行分析,列出了求解算法及相应程序。最后基于MATLAB语言实现动力学各个杆件正向求解和仿真。

关键词： 动力学   仿人机械臂   气动肌肉   固有频率   能量法  

摘要： 气动肌肉驱动器因能很好地解决机械臂柔顺性的问题,其在仿人机械臂上的应用已经成为了研究热点。但目前针对机械臂的建模多忽略驱动器质量,或考虑为集中分布情况,同时一般考虑关节铰为线弹性扭簧。这些假设不太符合气动肌肉驱动器的实际力学性能。因此通过D-H法建立了一种仿人机械臂结构的运动学模型,核算了其奇异位形。通过能量法建立了驱动器质量分散分布下的仿人机械臂的动力学模型;通过假设模态法进行离散化,得到标准特征式方程。基于Wolfram Mathematica 9进行编程,获得了该仿人机械臂在两个关键的奇异位形之间运动时,其固有频率随关节角度和关节铰刚度变化的形式。

关键词： 机械通气   急性呼吸窘迫综合征   不同跨肺压   血流动力学  

摘要： 目的比较不同跨肺压(Ptp)机械通气治疗急性呼吸窘迫综合征的效果及对血流动力学的影响。方法选取我院2017年3月-2019年3月收治的88例急性呼吸窘迫综合征患者为研究对象,所有患者依据随机数表法分为4组,即对照组、A组、B组、C组,每组22例。对照组参照《急性呼吸窘迫综合征患者机械通气指南》进行治疗,A、B、C组调节呼气末正压(PEEP)后设定不同Ptp治疗,分别为10、15、20cmH2O。对比4组治疗后12、24、48h血气分析指标[动脉血氧分压(Pa02)、二氧化碳分压(PaC02)、氧合指数(Pa02/Fi02)]及呼吸力学指标[肺顺应性(Cst)、PEEP、血管外肺水指数(ELWI)]变化,对比4组治疗前后血流动力学指标[平均动脉压(MAP)、中心静脉压(CPV)、心指数(CI)、收缩压(SBP)、舒张压(DBP)、心率(HR)]变化,另外统计4组治疗后28 d预后情况。结果4组不同时点PaO2、PaCo2、PaO2/FiO2水平呈上升趋势,12h<24h<48h,差异有统计学意义(P<0.05)。4组不同时点Cst、PEEP水平呈上升趋势,12h<24h<48h,差异有统计学意义(P<0.05);4组不同时点ELWI水平呈下降趋势,12h>24h>48h,差异有统计学意义(P<0.05)。对照组、B组、C组治疗后MAP、DBP、HR水平与治疗前对比显著降低,差异有统计学意义(P<0.05);对照组、B组、C组治疗后CI水平与治疗前对牝显著提高,差异有统计学意义(P<0.05)。对照组治疗后死亡率为22.73%,A组为9.09%,B组为13.64%,C组为18.18%,4组死亡率的差异无统计学意义(P>0.05)。结论Ptp为10cmH2O时机械通气治疗急性呼吸窘迫综备征可改善患者氧合及呼吸力学指标,且血流动力学稳定,安全性较高,值得临床应用。

关键词： CPAP   BiPAP   血流动力学   组织灌注   微循环  

摘要： 目的观察健康志愿者在不同无创通气模式(CPAP或BiPAP)下,压力变化对血流动力学的影响,探讨正压通气影响血流动力学的机制,为临床实施循环保护通气策略提供依据。方法连续入选30例健康志愿者,每例均先后接受CPAP(压力为0、10、15 cmH 2O)与BiPAP(IPAP 0、15、20 cmH 2O,EPAP 4 cmH 2O)模式并同步监测血流动力学指标。血流动力学监测心率(HR)、心输出量(CO)、心脏动力学指数(CPI)等大循环指标及经皮氧分压(PctO 2)、经皮二氧化碳分压(PctcO 2)等微循环指标。结果在CPAP和BiPAP两种通气模式下随压力的增加,SV、SI变化均无统计学意义(P>0.05),而HR、CI、CO及CPI降低,TPR及TPRI升高,差异有统计学意义(P<0.01);同一模式下改变通气压力PctO 2的变化无统计学意义(P1>0.05),但BiPAP模式下PctO 2较CPAP更高,差异有统计学意义(P2<0.01);两种通气模式下PctcO 2均呈降低趋势(P1<0.01),但BiPAP模式降幅更大,差异有统计学意义(P2<0.01)。结论CPAP和BiPAP均能引起健康志愿者血流动力学改变,心率、心输出量及心肌收缩力指数下降,微循环灌注增加,其中BiPAP对提高组织氧及降低组织二氧化碳的效果更明显。

关键词： 机械臂   MATLAB/Sim-Mechanics   可视化仿真  

摘要： 对六轴机械臂进行动力学理论分析。基于SolidWorks与MATLAB的联合仿真平台对机械臂进行动力学可视化仿真,通过对比理论分析与机械臂Sim-Mechanics物理模型之间的力矩差,从而判断理论分析以及仿真的正确性。仿真结果为后续的机械臂运动控制提供了理论依据。