关键词： 机械制造行业   系统动力学   综合评价方法   危险程度  

摘要： 为了研究机械制造行业综合危险性,应用系统动力学理论和方法,结合层次分析法(AHP)、预先危险性分析-作业条件危险性评价法(PHA-LEC)、模糊综合评价法以及安全检查表法(SCL)等评价技术,利用仿真技术构造机械行业危险性整体框架,研究机械制造行业突发事故的危险程度,并以"8·2昆山粉尘爆炸事故"作为具体实例,综合评价突发事故的危险性。

关键词： MSC   FATIGUE   ADAMS   链轮   再制造  

摘要： 应用Solid Works软件对履带行走式机械驱动链轮进行了三维建模,通过ADAMS软件进行系统运动学/动力学仿真与分析,得出驱动链轮轮齿载荷谱。根据载荷谱应用MSC PANTRAN与MSC FATIGUE软件对链轮轮齿进行疲劳寿命分析,为驱动链轮的修复与再制造提供理论依据。

关键词： 工程机械   混合动力技术   应用  

摘要： 混合动力分析是多种机械技术的综合应用,混合动力技工程机械中的应用,可以大大提供机械运行在实际应用中的工作效率,降低共用功的浪费,实现了工程机械在我国社会动力发展中的全面性创新应用。本文对混合动力技术下在工程机械中技术设计原理和实际应用的技术要点进行分析,促进我国社会工程技术实现创新发展。

关键词： 农业机械动力   县域   变异系数   艾肯森指数   空间自相关   探索性空间数据分析  

摘要： 农业机械化是农业现代化建设的重要内容。为此,以县域为基本研究单元,利用变异系数与艾肯森指数等区域差异研究方法对河南省2004-2013年近10年的农业机械动力投入进行动态差异分析,并采用探索性空间分析方法(ESDA),在Arc GIS与Deo Da095i软件的支持下,分析近10年来河南省农业机械动力投入的时空格局与时空演变特征。结果表明:2004-2013年,河南省县域农业机械动力投入均值呈显著的增长趋势,但整体区域差异呈现出逐渐缩小的态势;2004-2013年河南省县域农业机械动力投入之间存在显著的空间正相关,表现出明显的空间集聚现象,但农业机械动力投入水平相似的县域在空间上的集聚态势会逐渐降低;局部空间集聚格局,总体呈现出东北部较高而西南与东南部较低的特征;2004-2013年整体空间分布位置变化不大,数量上有明显变化,高高集聚与低低集聚型县域数量总体呈现出明显减少的趋势,各县(县级市)趋向于平衡化的发展。

关键词： Drosophila   Imaging   Morphogenesis  

摘要： The actin cable is a supracellular structure that embryonic epithelia produce to close gaps. However, the action of the cable remains debated. Here, we address the function of the cable using Drosophila dorsal closure, a paradigm to understand wound healing. First, we show that the actin cytoskeleton protein Zasp52 is specifically required for actin cable formation. Next, we used Zasp52 loss of function to dissect the mechanism of action of the cable. Surprisingly, closure dynamics are perfect in Zasp52 mutants: the cable is therefore dispensable for closure, even in the absence of the amnioserosa. Conversely, we observed that the cable protects cellular geometries from robust morphogenetic forces that otherwise interfere with closure: the absence of cable results in defects in epithelial organization that lead to morphogenetic scarring. We propose that the cable prevents morphogenetic scarring by stabilizing cellular interactions rather than by acting on closure dynamics.

关键词： Molecular Dynamics Simulation   strain rate   Mechanical properties   silicon dioxide   kinetic simulation   Stress relaxation   Silica glass   plateaus  

摘要： Assessment of the empirical reactive force field ReaxFF to predict the formation of amorphous silica from its crystalline structure and the determination of mechanical properties under tension using molecular dynamics simulations is presented. Detailed procedures for preparing amorphous silica from crystalline silica are presented and the atomic structure is in good agreement with experimental results. Tensile properties of silica are predicted over a wide range of strain rates (2.3 x 10(8) s(-1)-1.0 x 10(15) s(-1)) allowing comparison with results reported in the literature for other force fields. Quasi-static modulus obtained from power-law fitting of the low-stain rate modulus predicted by ReaxFF is in good agreement with experimental results. A transition strain rate of approximately is identified where modulus increases rapidly to a plateau level. Tensile strength also increases significantly in this range of strain rate and plateaus at the theoretical upper bound for silica. A detailed study is presented to understand the mechanisms associated with strain rate effects on the overall stress-strain response of silica. Bond breakage which evolves into void growth leading to failure is predicted to occur at approximately 27 % strain for all strain rates. Stress relaxation simulations indicates that the transition strain rate occurs when the characteristic time for high-strain rate loading and stress relaxation times are the same order. The effects of cooling rate and temperature on the structure and the stress-strain response of the silica glass are also investigated. Low-cooling rate and low-cooling temperature enhance the properties of silica.

关键词： ELECTRIC oscillators   SELF-organizing systems   DYNAMICS  

摘要： This focus issue presents a collection of research papers from a broad spectrum of topics related to the modeling, analysis, and control of mechanical oscillators and beyond. Examples covered in this focus issue range from bridges and mechanical pendula to self-organizing networks of dynamic agents, with application to robotics and animal grouping. This focus issue brings together applied mathematicians, physicists, and engineers to address open questions on various theoretical and experimental aspects of collective dynamics phenomena and their control. Published by AIP Publishing.

关键词： Multibody mechanical system   Multiple clearances   Contact and impact   Dynamics analysis   Numerical simulation  

摘要： In this work, the dynamic responses of multibody mechanical systems including multiple revolute clearance joints are investigated numerically. The joint components of an imperfect joint with clearance are modeled as contact bodies. The normal force in the revolute clearance joint is modeled using a continuous contact force model, which is based on the elastic Hertz theory together with a dissipative term. The friction effect is considered using a modified Coulomb friction model. Then the dynamics equation of multibody systems with clearance joint is established. Finally, a planar four-bar mechanical system with multiple revolute clearance joints is utilized as demonstrative application example to perform the investigation. The main results of this work can be drawn that clearances in joints play a crucial role in predicting accurately the dynamic responses of multibody mechanical systems and the multiple clearance joints interact strongly with one another. (C) 2016 Elsevier Masson SAS. All rights reserved.

关键词： Molecular docking   Pharmacophore   3D-QSAR   Molecular dynamics   Binding free energy   Density functional theory  

摘要： Deregulated epigenetic activity of Histone deacetylase 1 (HDAC1) in tumor development and carcinogenesis pronounces it as promising therapeutic target for cancer treatment. HDAC1 has recently captured the attention of researchers owing to its decisive role in multiple types of cancer. In the present study a multistep framework combining ligand based 3D-QSAR, molecular docking and Molecular Dynamics (MD) simulation studies were performed to explore potential compound with good HDAC1 binding affinity. Four different pharmacophore hypotheses Hypo1 (AADR), Hypo2 (AAAH), Hypo3 (AAAR) and Hypo4 (ADDR) were obtained. The hypothesis Hypo1 (AADR) with two hydrogen bond acceptors (A), one hydrogen bond donor (D) and one aromatics ring (R) was selected to build 3D-QSAR model on the basis of statistical parameter. The pharmacophore hypothesis produced a statistically significant QSAR model, with co-efficient of correlation r(2) = 0.82 and cross validation correlation co-efficient q(2) = 0.70. External validation result displays high predictive power with r(2) (o) value of 0.88 and r(2) (m) value of 0.58 to carry out further in silico studies. Virtual screening result shows ZINC70450932 as the most promising lead where HDAC1 interacts with residues Asp99, His178, Tyr204, Phe205 and Leu271 forming seven hydrogen bonds. A high docking score (-11.17 kcal/mol) and lower docking energy 37.84 kcal/mol) displays the binding efficiency of the ligand. Binding free energy calculation was done using MM/GBSA to access affinity of ligands towards protein. Density Functional Theory was employed to explore electronic features of the ligands describing intramolcular charge transfer reaction. Molecular dynamics simulation studies at 50 ns display metal ion (Zn)-ligand interaction which is vital to inhibit the enzymatic activity of the protein. (C) 2016 Elsevier Inc. All rights reserved.