关键词： 机械功   热能与动力工程   应用   优化  

摘要： 本文对机械功所具有的物理意义进行了分析,在此基础上阐述了机械功在热能与动力工程中的应用与优化。

关键词： 钢拱架安装机   虚拟样机   ADAMS仿真   逆动力学分析  

摘要： 在充分了解钢拱架安装机工况的基础上,运用Solidworks和ADAMS对机械臂进行三维实体建模和虚拟样机逆动力学仿真,对机械臂各液压缸铰点处的受力进行分析,获得液压缸工作中的最大负载值,为液压系统的设计做准备,为机构的整体设计提供了数据参考。

关键词： 5-Fluorouracil   Polyoxyethylenic spacer   Liposomes   Enzymatic inhibition  

摘要： In a previous investigation, cationic liposomes formulated with new 5-FU derivatives, differing for the length of the polyoxyethylenic spacer that links the N-3 position of 5-FU to an alkyl chain of 12 carbon atoms, showed a higher cytotoxicity compared to free 5-FU, the cytotoxic effect being directly related to the length of the spacer. To better understand the correlation of the spacer length with toxicity, we carried out initial rate studies to determine inhibition, equilibrium and kinetic constants (K-I, K-M, k(cat)), and get inside inhibition activity of the 5-FU derivatives and their mechanism of action, a crucial information to design structural variations for improving the anticancer activity. The experimental investigation was supported by docking simulations based on the X-ray structure of thymidine phosphorylase (TP) from Escherichia coli complexed with 3'-azido-2'-fluoro-dideoxyuridin. Theoretical and experimental results showed that all the derivatives exert the same inhibition activity of 5-FU either as monomer and when embedded in lipid bilayer. (C) 2015 Elsevier B.V. All rights reserved.

关键词： 水下机械手   水动力学模型   轨迹规划  

摘要： 以Morison公式为基础,研究了浮力、水阻力、附加质量力对水下机械手的影响,结果表明,在各影响因素中,浮力影响最大,水阻力和附加质量力引起的水动力很小.以大臂关节为例分析了不同水阻系数和附加质量力系数对搅水力矩的影响,水阻力系数对搅水力矩的影响较大,而附加质量力系数对搅水力矩的影响较小.

关键词： 变速箱   啮合力   啮合频率   接触应力  

摘要： 针对某公司全新设计的一种液压机械无级变速箱，为了分析工作过程中其齿轮所受到的啮合力以及接触应力是否满足要求，首先在一个恒定的输入转速下对变速箱进行动力学仿真，将仿真得到的输出齿轮的啮合力和啮合频率与理论值进行比较分析，然后将动力学仿真结果作为边界条件，再对齿轮对进行接触应力有限元分析。结果显示齿轮三向啮合力的仿真值为586．3、267．5、124．1N与理论值596．8、221．3、***相差甚微，啮合频率仿真值为106．8Hz与理论值110．9Hz基本吻合，接触应力分析值在250-300MPa之间也与理论值285．14MPa基本一致，说明了齿轮模型的正确性以及动力学和有限元分析方法的合理性。

关键词： 机械活化   三水铝石矿   溶出性能   动力学   控制步骤  

摘要： 分析了机械活化作用下铝土矿的溶出特点,考察了溶出温度、溶出时间及机械活化转速等对铝土矿直接溶出与机械活化溶出性能效果的影响,并探讨了该过程控制步骤的转化规律.研究结果表明:机械活化作用可有效降低三水铝石型铝土矿的溶出温度及溶出时间,放宽给矿粒度,在装球量为30%,钢弹转速为100 r/min,料球质量比为1.2∶1,溶出温度为150℃,溶出时间为40 min的条件下,矿物中氧化铝的实际溶出率可达85%以上;机械活化作用可大幅度降低扩散控制对三水铝石矿溶出过程的影响.

关键词： 水田动力机械   手扶拖拉机   船式拖拉机   水田轮式拖拉机   履带式水田耕作机   水田履带拖拉机  

摘要： 水田面积的逐年扩大,以及劳动力成本的提升,促进了水田动力机械的快速发展。从传统的畜力耕作,逐渐过渡到手扶拖拉机、船式拖拉机、水田轮式拖拉机、履带式水田耕作机,各种动力机械在水田使用过程中均不尽完美。水田履带拖拉机的出现基本解决了现水田耕作过程中面对的问题。

关键词： agricultural mechanization level   planting industry   labor demand   estimation model   data acquisition   crop production  

摘要： The research on the relationship between mechanization level in planting industry and labor demand was carried out based on the present *** former estimation model of labor demand in planting industry was established without analyzing the effects of planting structure on labor demand in planting *** purpose of the research is to develop and perfect the theory of estimating both labor demand and rural surplus labor in planting industry,then to provide some theoretical references for scientific *** model established in this research can be used to calculate not only the amount of current labor demand,but also the demand in the various moment of future according to forecasted mechanization level and cultivated ***,it was explored how to obtain the indexes of cultivated areas,mechanization level and the average cultivated area that each labor can burden when the mechanization level is 0 and 100%.According to statistics principle,the methods of inspection to eliminate abnormal data and data processing were given in order to make the data more ***,an example was presented for demonstration purposes.

关键词： 分层注水   机械臂   运动仿真   优化设计  

摘要： 针对分层注水测调仪的工作特点和关键技术,提出一种新型分层注水测调仪机械臂结构方案。基于多体系统动力学理论建立其动力学模型,应用仿真分析软件ADAMS对测调仪机械臂进行了测调工况下的动力学仿真分析。对测调仪机械臂自动展开、定位、收回,以及机械臂的对接机构与坐封在配水器中的堵塞器实现弹性对接等一系列运动过程进行仿真分析。结果表明,由工作中产生的振动和碰撞引起机械臂机构位姿的变化在合理的范围内。仿真分析有效评价了测调仪机械臂系统动力学特性,为其结构的优化设计提供参考。

关键词： MATERIALS -- Mechanical properties   CARBON composites   CHEMICAL kinetics   CARBON nanotubes   FABRICATION (Manufacturing)   MICROSTRUCTURE   SHEAR strength  

摘要： Carbon nanotube reinforced carbon/carbon composites were fabricated via in situ growth of carbon nanotubes directly on needle-punched felts following direct resistive heating thermal gradient chemical vapor infiltration. The infiltration kinetics, mechanical properties and microstructure of carbon nanotube reinforced carbon/carbon composites were studied. The results show that rough laminar pyrocarbon is obtained owing to CNTs favoring the formation of high-textured pyrocarbon. When nickel nitrate content is 0.10 ml/L, carbon nanotubes with the diameter about 30 nm are obtained together with continuous network on the carbon fibers. The flexural strength and interlaminar shear strength of the composites obtained with 0.1 mol/L nickel nitrate contents are increased by nearly 44.2% and 40.7%, respectively, compared to that of the composite containing no carbon nanotubes. (C) 2015 Elsevier Ltd. All rights reserved.