关键词： 工程机械液压系统   动力匹配   控制技术  

摘要： 作为机电一体化技术中的一部分,工程机械液压系统的动力匹配与智能控制技术在生产中具有重要的作用,能够高效的将发动机、液压系统以及自动控制系统有机的结合起来,保证作业中设备的稳定、高效运行,保证生产的质量和可靠性,这种技术综合了多门学科,具有较强的综合性和技术性,对技术人员和设备的要求较高。高效的运用机电一体化技术,不仅能够减少操作时间,而且极大的提高了操作效率,降低了错误率和事故率。本文就工程机械液压系统动力匹配及其控制技术进行了详细的讨论。

关键词： ANTIMALARIALS   BENZIMIDAZOLES   PARASITE life cycles   ORAL medication   DRUG efficacy   MICE as laboratory animals  

摘要： Further structure-activity relationship (SAR) studies on the recently identified pyrido[1,2-a]benzimidazole (PBI) antimalarials have led to the identification of potent, metabolically stable compounds with improved in vivo oral efficacy in the P. berghei mouse model and additional activity against parasite liver and gametocyte stages, making them potential candidates for preclinical development. Inhibition of hemozoin formation possibly contributes to the mechanism of action.

关键词： ferroelectrics   scanning probe microscopy   nanotechnology   strain   stress  

摘要： We investigate ferroelectric domain structure and piezoelectric response under variable mechanical compressive stress in Pb(Zr0.2TiO0.8)O-3 ( PZT) thin films using high-resolution piezoresponse force microscopy (PFM) and an in situ sample bending stage. Measurements reveal a drastic change in the ferroelectric domain structure which is presented along with details of the mediating switching process involving domain wall motion, nucleation, and domain wall roughening under an applied external mechanical stimulus. Furthermore, local PFM hysteresis loops reveal significant changes in the observed coercive biases under applied stress. The PFM hysteresis loops become strongly imprinted under increasing applied compressive stress.

关键词： Nano-structures   Mechanical properties   Computational modelling   Graphene  

摘要： This paper investigates the mechanical properties of graphene/PMMA nanocomposite system by using the molecular dynamics simulations. The graphene nanoplates are assumed to be fully exfoliated in the PMMA matrix and are all planar orientated, which are similar to the ones assembled using layer-by-layer technique. The Young's modulus and shear modulus of the composites with different graphene volume fractions under different temperatures are simulated and discussed. The results show that the Young's and shear moduli increase with the increase of graphene volume fraction and decrease as the temperature rises from 300 K to 500 K, while the efficiency of the reinforcement is reduced as the graphene content becomes higher. Simulations of single layer graphene under uniaxial tension, in-plane pure shear and uniformly distributed transverse load are performed and the effective thickness and the elastic moduli of graphene are subsequently determined uniquely. The obtained stiffnesses of graphene are then substituted into the simple rule of mixture to predict the overall mechanical properties of the composite. Large discrepancies between the results from the MD simulations and the rule of mixture are observed. (C)2016 Elsevier Ltd. All rights reserved.

关键词： 串联机械手   动力学   优化  

摘要： 提出一种基于轨迹的三自由度串联机械手动力学优化方法。在已知机械手末端轨迹和运动状态下,建立刚体动力学模型。以各关节力矩和的最大值最小为优化目标,对机械手进行动力学优化,并将优化后的机械手与原机进行对比。工程实例表明,优化后机械手的关节力矩和的最大值对比优化前降幅约为10.8512%,动力学效果得到明显改善。

关键词： 工程机械   动力系统   加载系统   电液伺服  

摘要： 工程机械的正常工况可以类比为一般车辆的恶劣工况,即大负荷周期性波动,这对动力系统的瞬时动力性能提出了非常严酷的要求.液压-动力系统集成匹配性能的优劣直接决定了油耗、效率、协调性等整车性能.为针对动力液压系统的匹配性能进行测试优化,设计了工程机械机、电、液匹配综合性能试验台.试验台包含3个直线加载通道和3个扭矩加载通道,不仅可以满足对挖掘机、推土机的性能测试,通过简单改装也可用于各种工程机械的性能测试.

关键词： 多体动力学   机械工程   应用  

摘要： 多体动力学,通常指多体系统动力学,是一门较为复杂、具备综合性的力学学科,在当下机械工程领域中发挥着关键的作用,也因此成为了学科研究的重中之重。文章先介绍了多体动力学模型的建立过程,结合对其中各个要素的相关阐述,讨论了该学科在机械工程领域的应用状况。