关键词： 动力机械   钢结构建筑物   振动位移  

摘要： 随着经济的发展，动力机械设备运用到钢结构的建筑，改善了建筑结构，提高建筑结构的性能。文章通过分析了钢结构建筑的特点和钢结构建筑中的动力机械，深入的探析了钢结构建筑中动力机械设备的设计和动力机械在钢结构建筑物中的应用。

关键词： 国际展览   纺织机械   展览会   中国   亚洲   聚焦   参展企业   网上报名  

摘要： 15万平方米的展出面积；1550家企业参展；展商来自28个国家与地区；最小展示面积统一为15平方米；参展企业全部通过网上报名。 4月19日，中国国际纺织机械展览会暨ITMA亚洲展览会（以下简称“联合展”）的主办方——中国国际贸促会纺织行业分会常务副会长徐迎新与北京泰格斯特国际展览展示有限公司总经理梁鹏程联袂接受记者专访，为6月在上海开幕的联合展作序。

关键词： 机械设计制造   学院   三峡大学   能源与动力工程   机械电子工程   材料成型   控制工程   本科专业  

摘要： 2014年1月原机械与材料学院更名为机械与动力学院，学院现设有机械设计制造及其自动化、机械电子工程、材料成型及控制工程、工业工程、能源与动力工程、核工程与核技术六个本科专业，其中机械设计制造及其自动化为国家特色专业、第二批卓越工程师教育培养计划专业和省本科品牌专业，材料成型及控制工程为第三批卓越工程师教育培养计划专业。

关键词： 机械表   电子表   智力游戏   科学知识  

摘要： 电子表的动力是电池中的电能，那么你知道机械表的动力是什么吗？

关键词： Glyoxylate   Mn-III(salen)   electron transfer   kinetics   DFT  

摘要： The kinetics of oxidation of glyoxylic acid (HGl) by Mn-III(salen)(OH ((H(2)salen = N,N'- bis(salicylidene)ethane-1,2-diamine) is investigated at 30.0-45.0A degrees C, 1.83 a parts per thousand currency sign pH a parts per thousand currency sign 6.10, I = 0.3 mol dm(-3)(NaClO4). The products are identified as formic acid, CO2 and Mn-II with the reaction stoichiometry, |Delta[Mn-III]/Delta[HGl]| = 2. The overall reaction involves fast equilibrium pre-association of Mn-III(salen)(OH with HGl and its conjugate base Gl(-) forming the corresponding inner sphere complexes (both HGl and Gl(-) being the monohydrate gem-diol forms) followed by the slow electron transfer steps. In addition, the second order electron transfer reactions involving the inner-sphere complexes and HGl/Gl(-) are also observed. The rate, equilibrium constants and activation parameters for various steps are presented. Mn-III(salen)(OH2)(Gl) is virtually inert to intra molecular electron transfer while the process is facile for Mn-III(salen)(OH2)(HGl)(+) (10(5) k (et) = 2.8 +/- 0.3 s(-1) at 35.0A degrees C) reflecting the involvement of proton coupled electron transfer mechanism in the latter case. A computational study of the structure optimization of the complexes, trans-Mn-III(salen)(OH, trans-Mn-III(salen)(OH2)(Gl), and trans- Mn-III(salen)(OH2)(HGl)(+) (all high spin Mn-III(d(4)) systems), reveals strongest axial distortion for the (aqua)(Gl) complex;HGl bound to Mn (III) centre by the C=O function of the carboxyl group in the (aqua)(HGl) complex facilitates the formation of a hydrogen bond between the proton of the carboxyl group and the coordinated phenoxide moiety ((O-H aEuro broken vertical bar O hydrogen bond distance 1.745 ) and the gem-diols are not involved in H-bonding in either case. A rate comparison for the second order paths: Mn-III(salen)(OH2)(HGl)/Gl)(+/0)+ HGl/Gl(-)-> products, shows that HGl for the (aqua)(HGl) complex is a better reducing agent than Gl(-) for the (aqua)(Gl) compl

关键词： Molecular dynamics   Shape memory alloy   NiAl   Martensite   Phase transformation  

摘要： We use molecular dynamics (MD) with an embedded atom model potential parameterized for NiAl to study martensitic phase transformations in a disordered shape memory alloy. We focus on the role of intrinsic atomic-level variability and mechanical constraints on the martensite and austenite transformation temperatures and on the martensite microstructure for specimens with varying size. We find that periodic system size has a weak effect on transformation temperature all the way to the nanometer scale, with the entropy-stabilized austenite phase slightly penalized with decreasing size. Atomic-level variability in these random alloys leads to significant sample-tosample variability in transformation temperature. The uncertainty in the austenite transformation temperature increases with decreasing size, reaching similar to,10% of the mean value for samples 10 nm on the side. Interestingly, the variability of the high-temperature martensite transition shows little size dependence. We find that a critical size of similar to 40 nm is required to develop multidomain martensite microstructures, and mechanical constraints reduce this critical size to similar to 17 nm, while significantly affecting the transformation temperatures. These results contribute to the understanding of martensitic transformation in nanocrystalline samples and of the fundamental limits of miniaturization of these alloys. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

关键词： Correlation analysis   Halochromate   Kinetics   Mechanism   Oxidation  

摘要： The oxidation of organic sulfides by imidazolium fluorochromate resulted in the formation of the corresponding sulfoxides. The reaction is first order with respect to imidazolium fluorochromate. A Michaelis-Menten type kinetics was observed with respect to the reactants. The reaction is catalyzed by toluene-p-sulfonic acid. The oxidation was studied in nineteen different organic solvents. An analysis of the solvent effect by Swain's equation showed that the both cation-and anion-solvating powers of the solvents play important roles. The correlation analyses of the rate of oxidation of thirty four sulfides were performed in terms of various single and multiparametric equations. For the aryl methyl sulfides, the best correlation is obtained with Charton's LDR and LDRS equations. The oxidation of alkyl phenyl sulfides exhibited a good correlation in terms of Pavelich-Taft equation. The polar reaction constants are negative indicating an electron-deficient sulfur centre in the rate-determining step. A mechanism involving formation of a sulphenium cation intermediate in the slow step has been proposed.

关键词： Myosins   Lasers   Actins   Cell physiology   Stiffness   Cytoskeleton   Tissue mechanics   Phosphorylation  

摘要： Mechanics has an important role during morphogenesis, both in the generation of forces driving cell shape changes and in determining the effective material properties of cells and tissues. Drosophila dorsal closure has emerged as a reference model system for investigating the interplay between tissue mechanics and cellular activity. During dorsal closure, the amnioserosa generates one of the major forces that drive closure through the apical contraction of its constituent cells. We combined quantitation of live data, genetic and mechanical perturbation and cell biology, to investigate how mechanical properties and contraction rate emerge from cytoskeletal activity. We found that a decrease in Myosin phosphorylation induces a fluidization of amnioserosa cells which become more compliant. Conversely, an increase in Myosin phosphorylation and an increase in actin linear polymerization induce a solidification of cells. Contrary to expectation, these two perturbations have an opposite effect on the strain rate of cells during DC. While an increase in actin polymerization increases the contraction rate of amnioserosa cells, an increase in Myosin phosphorylation gives rise to cells that contract very slowly. The quantification of how the perturbation induced by laser ablation decays throughout the tissue revealed that the tissue in these two mutant backgrounds reacts very differently. We suggest that the differences in the strain rate of cells in situations where Myosin activity or actin polymerization is increased arise from changes in how the contractile forces are transmitted and coordinated across the tissue through ECadherin-mediated adhesion. Altogether, our results show that there is an optimal level of Myosin activity to generate efficient contraction and suggest that the architecture of the actin cytoskeleton and the dynamics of adhesion complexes are important parameters for the emergence of coordinated activity throughout the tissue.

关键词： Vesicles   Lipids   Surface dynamics   Cell membranes   Mechanical properties  

摘要： Multicomponent lipid vesicles are commonly used as a model system for the complex plasma membrane. One phenomenon that is studied using such model systems is phase separation. Vesicles composed of simple lipid mixtures can phase-separate into liquid-ordered and liquid-disordered phases, and since these phases can have different mechanical properties, this separation can lead to changes in the shape of the vesicle. In this work, we investigate the dynamics of phase separation in multicomponent lipid vesicles, using a model that couples composition to mechanical properties such as bending rigidity and spontaneous curvature. The model allows the vesicle surface to deform while conserving surface area and composition. For vesicles initialized as spheres, we study the effects of phase fraction and spontaneous curvature. We additionally initialize two systems with elongated, spheroidal shapes. Dynamic behavior is contrasted in systems where only one phase has a spontaneous curvature similar to the overall vesicle surface curvature and systems where the spontaneous curvatures of both phases are similar to the overall curvature. The bending energy contribution is typically found to slow the dynamics by stabilizing configurations with multiple domains. Such multiple-domain configurations are found more often in vesicles with spheroidal shapes than in nearly spherical vesicles. (C) 2014 AIP Publishing LLC.

关键词： CRYSTALLIZATION -- Kinetics   MELTING   POLYETHYLENE   MATERIALS -- Mechanical properties   HIGH density polyethylene (HDPE)   FOURIER transform infrared spectroscopy  

摘要： Partially melting high-density polyethylene (HDPE) is investigated by differential scanning calorimetry and in situ Fourier transform infrared spectroscopy (FTIR) measurements. The results show that some incompletely molten crystals can be preserved in the partially melting HDPE, thus accelerating subsequent crystallization. Moreover, quantitative calculation of such incompletely molten crystals has been done based on the FTIR results. Interestingly, the kinetically enhanced crystallization results from the improved nucleation rate because of the incompletely molten crystals. Furthermore, such interesting self-nucleation originating from the partially melting HDPE has been deliberately applied to practical polymer processing, i.e., extrusion, aiming to investigate the influence of partially melting HDPE on the microstructural development and the resultant mechanical properties of the extruded products. Unexpectedly, an increment in tensile strength has been achieved in the sheets extruded from partially melting HDPE compared with that extruded from completely melted HDPE. Wide-angle X-ray diffraction and small-angle X-ray scattering results show that the crystallinity, long period, and lamellar thickness increase for the sheets extruded from the partially melting HDPE. These increases are considered to be responsible for the mechanical increment. This work opens a new gateway for applying the self-nucleating effect of partially melting polymer melt into practical processing with the purpose of preparing high-performance polymer products.