关键词： evolution   biomechanics   mechanical sensitivity   mechanical equivalence  

摘要： A classic question in evolutionary biology is how form-function relationships promote or limit diversification. Mechanical metrics, such as kinematic transmission (KT) in linkage systems, are useful tools for examining the evolution of form and function in a comparative context. The convergence of disparate systems on equivalent metric values (mechanical equivalence) has been highlighted as a source of potential morphological diversity under the assumption that morphology can evolve with minimal impact on function. However, this assumption does not account for mechanical sensitivity-the sensitivity of the metric to morphological changes in individual components of a structure. We examined the diversification of a four-bar linkage system in mantis shrimp (Stomatopoda), and found evidence for both mechanical equivalence and differential mechanical sensitivity. KT exhibited variable correlations with individual linkage components, highlighting the components that influence KT evolution, and the components that are free to evolve independently from KT and thereby contribute to the observed pattern of mechanical equivalence. Determining the mechanical sensitivity in a system leads to a deeper understanding of both functional convergence and morphological diversification. This study illustrates the importance of multi-level analyses in delineating the factors that limit and promote diversification in form-function systems.

关键词： 运转效率   汽车   动力性  

摘要： 阐述了国内外汽车动力提高的现状和发展趋势,对我国汽车的动力传动系统、动力性及燃油经济性进行了分析。

关键词： Molecular dynamics  

摘要： The quantum mechanical charge-field molecular dynamics (QMCF-MD) simulation method was employed to study the hydration properties of gadolinium(III) and terbium(III). Slight differences of the solvation shells' structural and dynamical properties were discovered. While the Ln-O radial distribution functions are in excellent agreement with recent experiments, average coordination numbers of 8.5 (Gd) and 8.4 (Tb) were found. Vivid ligand exchange dynamics along with rapid intrashell rearrangements were observed, underlined by mean residence times in the picosecond range, which is characteristic for trivalent lanthanoides according to quantum mechanical simulations. Vibrational analysis yielded ion-water force constants below 100 N m(-1). (C) 2015 Elsevier B.V. All rights reserved.

关键词： 柔性机械手   矢量法   动力学   Lagrange方程  

摘要： 为解决柔性机械手动力学建模常用的有限元等方法导致模型精度不高的问题,将柔性机械手视为连续整体,用矢量法建立了机械手的动力学模型。对比了矢量法和FEM法建立的动力学模型以及理想状态下机械手刚体动力学模型的仿真结果。对比结果表明,用矢量法建立的柔性机械手动力学模型是可行的,精度也较高。

关键词： Aortic balloon pump   Left ventricular assist device   Primary PCI   Coronary intervention  

摘要： Background: Studies have reported conflicting results regarding efficacy of mechanical hemodynamic support using intra-aortic balloon pump (IABP) or percutaneous ventricular assisted device (pVAD) in patients undergoing high-risk PCI. We performed a Bayesian network meta-analysis comparing the safety and efficacy of mechanical hemodynamic support devices and medical therapy (MT). Methods and results: RCTs comparing overall mortality of IABP versus MT or IABP versus pVAD in high-risk PCI populations were included. The primary endpoint was overall mortality, using the longest available follow-up in each study. This analysis included 2843 patients from 13 trials. In network meta-analysis, overall survival benefit was not significant with IABP (RR 0.84, 95% CrI 0.56-1.24) or pVAD (RR 0.95, 95% CrI 0.42-2.06), compared with MT. IABP or pVAD also did not show early survival benefit compared with MT. In terms of bleeding, pVAD was the worst (versus IABP: RR 29.4, 95% CrI 5.99-221.0;versus MT: RR 41.7, 95% CrI 8.19-330.0), which was mainly driven by the higher incidence of bleeding in the ECMO and TandemHeart, while IABP was worse than MT (RR 1.41, 95% CrI 1.01-2.08). The incidence of acute limb ischemia or vascular complication was not different between treatment groups. Conclusions: In this meta-analysis, routine elective use of IABP or pVAD did not reduce mortality, while it increased bleeding, compared with MT in high-risk PCI population or even in the patients with cardiogenic shock. Thoughtful selection of appropriate patients and balancing the risk and benefit should be the prerequisites to the use of mechanical hemodynamic support devices. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

关键词： 热能动力机械   行业发展   现状解析  

摘要： 经济的高速发展给许多行业都带来了活力,热能动力机械行业也是如此。热能动力机械在我国许多行业中都有较为广泛的应用,并且为经济发展做出巨大贡献。但是近年来科学技术发展较快,传统的热能动力机械已经不能满足市场发展的需求,必须对其进行完善。从当前我国热能动力机械的发展现状入手,详细分析其中影响热能动力机械发展的问题,展望其未来发展方向。

关键词： 动力机械设备   故障诊断技术   发展趋势  

摘要： 动力机械设备在运行的过程中,对安全性及可靠性的要求是非常高的,不过在实际运行的过程中,动力机械设备比较容易出现各种故障,进而影响设备的安全性及可靠性。在本文中,介绍了几种常用的动力机械设备故障诊断技术,并分析了影响故障诊断技术发展的因素,同时分析了动力机械设备故障诊断技术的发展趋势。

关键词： 液压元件   参数选择   动力匹配  

摘要： 液压行走系统在工程机械上应用越来越广泛,它以其平稳的传动性能和方便的操纵控制系统,在工程机械行走领域深受操作者的喜爱,但是液压行走元件的选择、计算是困扰工程机械设计人员的一个问题,为此,本文从工程机械行走系液压元件计算与动力匹配角度来探讨液压元件的选择方法。

关键词： 机械动力设备   检修管理   方法措施  

摘要： 阐述了机械动力设备检修管理的重要性,分析了机械动力设备的特点,提出机械动力设备检修管理的主要任务和要求,以便解决机械动力设备检修管理中存在的问题。

关键词： 机械运动视角   轮岗制度   企业发展  

摘要： 从机械运动视角出发,以机械动力的产生、机械动力的传导及机械运动内部摩擦力的控制为逻辑线索,并通过相关机械模型的引入类比式地探究了三个相应的过程,即轮岗制度驱动企业发展动力产生的过程、驱动作用在企业范围内扩大化的过程以及在实施过程中对于偏差进行控制的过程,其中着重剖析了轮岗制度与企业的知识管理、组织结构、组织文化和人力资源管理之间深层次的作用关系及其应用价值,进而从机械运动视角深化了轮岗制度作为驱动企业发展新动力的认识。