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991.
Electrochemical oxidation of the carbon nanotube (CNT) polarizable electrodes of electric double layer capacitors (EDLCs) was studied. It indicated that electrochemical oxidation elevated the available surface area of the electrodes and introduced some kinds of functional group on the CNT surfaces. The specific capacitances of the polarizable electrodes with organic electrolyte could be enhanced from 22.4 F g-1 to 78.2 F g-1 after electrolysis oxidization. The enhancement of the specific capacitance depends on the extent of electrochemical oxidation. Using acidic electrolyte for electrochemical oxidation has different effects on modifying the performances of the CNT polarizable electrodes compared to using basic electrolyte. 相似文献
992.
张恒星 《武汉工程大学学报》2012,34(8):75-78
以客户提供的液化器设计结构草案和设计载荷为基础进行分析,对液化器下部带夹套的异形偏心锥体结构进行强度核算.首先利用三维建模软件SOLIDWORK建立实体模型,然后将模型导入有限元分析计算软件ANSYS中定义单元、划分网格和施加载荷,再进行有限元内压静载荷分析和外压屈曲稳定性分析,最后依据国家标准JB4732-1995(2005确认)中的相关评定规则对分析结果进行评定.对结构草案中弯曲应力超过标准要求的不连续结构区域进行结构改造,降低弯曲应力,使液化器下部锥体的最终设计方案能够满足国家标准的要求和客户的要求. 相似文献
993.
内压支撑下薄壁管弯曲变形力学分析 总被引:3,自引:0,他引:3
管件内压弯曲又称为管件充液弯曲,具有减小截面畸变,延缓薄壁管内侧失稳起皱,提高弯曲成形极限等优点。支撑内压在其中起到了关键性的作用,对于环向和轴向的应力应变分量具有重要影响。采用塑性理论,对内压和弯矩共同作用下的薄壁管弯曲变形进行理论分析。考虑内压对微元平衡方程的影响,建立一个新的理论分析模型,通过求解非线性方程组,得到薄壁管应力应变的分布规律,定量分析内压对薄壁管应力应变的影响趋势。同时通过将有限元分析得到的应力应变分量的信息,与理论解进行对比发现,理论预测和模拟结果相符合,验证所建立的理论分析模型的可靠性。结果表明,轴向和环向应力随内压升高均大大提高,环向应变随内压升高线性递增,而厚向应变线性减小。 相似文献
994.
通过改进蔡树棠两相流基本方程的相间阻力项,建立能够进行二维解析研究的水沙动力学基本方程.该研究给出沙相压力和沙相粘性切应力的学科定义,以及它们的本构关系.对于牛顿流体,当输沙稳定时,挟沙水流的能坡与清水并无差别.沙相压力的二阶导数不为零是泥沙扩散条件,也是凹岸冲、凸岸淤自然现象的力学本质.蔡树棠方程隐含着流体的粘性切应力按运动组成可以分解或叠加的物理性质.正是这个结构性特点,给了解答浑水粘性这个古老的力学难题的方法,使我们能够完整地推导出牛顿流体沙相运动学粘滞系数vs公式;推导并证明了浑水综合粘滞系数μm=εv+ svνs,而不是习惯使用的μm=v+svvs.探讨了影响vs值的一些复杂因素,如颗粒表面束缚水的影响.本文研究能够证明:对分散相应用连续介质原理不仅可行,且是遵从压力传递规律惟一的正确方法.而揭示粘性切应力的结构性,在多相流和流变学领域具有深远的意义. 相似文献
995.
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998.
《Ergonomics》2012,55(12):1795-1805
Due to typical physiological changes with age, older individuals are likely to have different perceptual responses to and different needs for driver–seat interface design. To assess this, a study was conducted in which a total of 22 younger and older participants completed six short-term driving sessions. Three subjective ratings (comfort, discomfort and overall) were obtained, along with 36 driver–seat interface pressure measures, and were used to assess differences and similarities between the two age groups. For both age groups, localised comfort ratings were more effective at distinguishing between driver seats and workspaces. Older individuals appeared to be less sensitive to discomfort than younger individuals. Across age groups, two distinct processes were used in determining whole-body comfort and discomfort perceptions based on localised comfort/discomfort perceptions. Whole-body discomfort levels were largely affected by lower back discomfort in the younger group versus upper back discomfort in the older group. Four specific pressure measures at several body regions differed between the age groups, suggesting distinct contract pressure requirements and loading patterns among these groups. 相似文献
999.
《Ergonomics》2012,55(7):1342-1351
Abstract Involuntary delays in human-computer interaction, for example, system response times (SRTs) can increase stress. In the present study, 40 college-age subjects were randomly divided into an “incentive” and a “non-incentive” group”. Subjects performed a computer task with SRTs of 0-5, 15, and 4-5 s. Physiological, subjective, and performance data were collected during the task. The computer task was designed to individually set difficulty level (i.e., mental strain), thus standardizing the task for all subjects. By using this procedure, changes resulting from SRT duration can be separated from the effects related to task difficulty. The results indicate that both short and long SRTs produced differential psychophysiological changes consistent with different types of stress responses. Short SRTs resulted in higher autonomic and somatic activity, increased positive self-reported emotional states but poorer performance. Long SRTs resulted in increased electrodermal activity, negative self-reported emotional states and better performance. 相似文献
1000.
《Ergonomics》2012,55(3):261-273
The current study examined whether reality-based practice under pressure may help in preventing degradation of handgun shooting performance under pressure for police officers. Using a pre–post–test design, one group of nine police officers practised handgun shooting under pressure evoked by an opponent who also fired back using marking (coloured soap) cartridges. The control group (n = 8) practised handgun shooting on standard cardboard targets instead of real opponents. Within a fortnight after the pre-test, both groups received three training sessions of 1 h, in which each person fired a total of 72 rounds. During the pre- and post test each participant took 30 shots without pressure (cardboard targets) and 30 shots under additional pressure (with an opponent firing back). While during the pre-test both groups performed worse in front of an opponent firing back compared to the cardboard targets, after the training sessions shooting performance of the experimental group no longer deteriorated with an opponent while performance of the control group was equally harmed as during the pre-test. These results indicate that training exercises involving increased pressure can acclimatize shooting performance of ordinary police officers to those situations with elevated pressure that they may encounter during their police work. 相似文献