关键词： 农村富余劳动力   农业机械化   中国   新型农民   农村劳动力   第三产业   第一产业   工业化  

摘要： 农业机械化使中国平均每年产生1000万农村富余劳动力，为中国工业化、城镇化和第二、第三产业的发展提供有力支撑。 农业机械化在解放中国大批农村劳动力的同时，也造就了无数新型农民，这些农民有知识、有技术，利用现代化信息和工具，极大地提高了生产力，从事第一产业的人员每年在大量减少，但人均的生产率10年间却翻了3倍。如今，农忙时节外出打工的农民纷纷回乡务农的情形已经不复存在，

关键词： 工程机械行业   东方红柴油机   动力元件   上海新国际博览中心   宝马   展放   品牌   亚太地区  

摘要： 1 展会情况 “上海宝马工程机械展”是世界最大的工程机械展bauma在中国的延伸，同时也是2010年亚太地区最具影响力的国际性行业博览会。bauma China 2010暨第5届中国国际工程机械、建材机械、工程车辆及设备博览会于2010年11月23—26日在上海新国际博览中心召开。本届展会展示面积超过23万m2，

关键词： 水下机械手   动力学   水环境   流干扰  

摘要： 研究了四功能深海电驱动机械手所受的水动力。以Morison公式为计算基础,利用拉格朗日方法,建立了流干扰下的水下机械手动力学模型。仿真研究了水阻力、浮力、定常流以及非定常流对水下机械手动力学的影响。结果表明,在各水动力影响因素中,浮力影响最大,流干扰次之,而水下机械手运动搅水引起的水动力甚微。

关键词： 呼吸,人工   右美托咪定   镇静   血流动力学  

摘要： 目的:观察不同剂量右美托咪定对机械通气患者镇静效果和血流动力学的影响。方法:入监护室行机械通气的咽成形术后患者45例,随机分为A、B、C组,每组15例,按分组静脉微泵给予右美托咪定。A组:负荷剂量0.5μg/kg,维持剂量0.2μg/(kg·h);B组:负荷剂量0.75μg/kg,维持剂量0.3μg/(kg·h);C组:负荷剂量1.0μg/kg,维持剂量0.4μg/(kg·h)。如患者躁动,静脉单次给予吗啡5mg。机械通气24h后,停止右美托咪定输注,待患者完全清醒,肌力恢复,满足拔管条件后拔除气管导管。观察并记录给药前即刻(T0)、给药结束后即刻(T1)、给药后30min(T2)、给药后1h(T3)、给药后6h(T4)、给药后12h(T5)、给药后24h(T6)的无创动脉血压和心率,观察并记录上述各时点的镇静评分(Ramsay分级法),记录各组吗啡的总用量,观察并记录各组停止右美托咪定输注后至拔管所需时间。结果:血流动力学:A、B、C组部分时点动脉血压、心率较T0有所改变,差异有统计学意义;C组与A、B组间部分时点动脉血压、呼吸频率差异有统计学意义(P<0.05)。镇静评分:A、B、C各组各时点镇静评分与T0时比较差异无统计学意义;A、B、C各组相同时点镇静评分差异无统计学意义(P>0.05)。吗啡总用量:A、B、C各组吗啡总用量差异无统计学意义(P>0.05)。拔管所需时间:B组与A组之间,C组与B、A组之间拔管所需时间差异有统计学意义(P<0.05)。结论:随着右美托咪定给药剂量的增加,血流动力学变化加剧,拔除气管导管时间延长,但没有加深镇静程度。

关键词： 金砖四国   建筑机械行业   基础设施   投资   建筑机械市场   装载机   吸引力   俄罗斯  

摘要： 全球范围内，最具吸引力的建筑机械市场：巴西、俄罗斯、印度与中国（金砖四国），紧随其后的是非洲与中东； 价值链各环节竞争激烈； 重点产品领域：挖掘机与装载机、反铲装载机；

关键词： 混合动力   氢动力   工程机械   发动机  

摘要： 混合动力工程机械和氢动力发动机是开发利用新能源的典型代表。概述了二者的研究现状、在工程和汽车领域里的应用及其关键技术。为进一步降低排耗,分别针对工程机械的能量回收率、燃料利用率低和氢气的储运以及发动机的早燃、回火等问题提出了不同的解决策略。最后,对混合动力工程机械和氢动力发动机的发展趋势进行了总结和展望。研究结果表明,这些措施都有较好的可行性。

关键词： Joints   Friction   Contact   Damping   Thin layer elements   Zero thickness elements  

摘要： This article gives an overview of different approaches for modeling the dynamics of mechanical joints in assembled structures. It contains a literature review pertaining to joint characteristics, types of joint models, and briefly examines models used in the simulation of assembled structures. Further on, a more detailed insight in joint modeling with the finite element method based on three different approaches is given: node-to-node contact using a Jenkins friction model, thin layer elements, and zero thickness elements. These approaches presented with real life applications come from an extensive joint modeling research performed at the Institute of Applied and Experimental Mechanics in the last 15 years. The advantages as well as limitations of these methods are discussed and the authors give practical hints for which cases these methods can be implemented. The article is supplemented with easy to model examples, so that the interested reader can apply the proposed approaches and compare the results with solutions provided by the authors. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Zirconium (oxy)carbide   Spark plasma sintering   Chemical properties   Mechanical properties   Electron microscopy  

摘要： Different stoichiometries of zirconium oxycarbide (ZrCxOy) powders were synthesised by carboreduction to approach the role of the chemical composition on the densification behaviour during spark plasma sintering and on the mechanical properties. Chemical analyses were performed using complementary methods to determine the actual stoichiometry and homogeneity of powders. Evolution of relative density during SPS treatment and microstructure observations by SEM showed that oxygen and vacancy contents would enhance the densification kinetics by promoting the lattice diffusion of limiting species. A study of mechanical properties of SPS sintered specimens has highlighted their significant dependence on the oxycarbide stoichiometry, especially at high temperature. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Polyurethanes   Benzidine   Mechanical properties   Thermal behavior   Dielectric properties  

摘要： This paper reports the effect that the aromatic diamines and crosslinker nature have on the physico-mechanical and dielectric properties of linear and crosslinked polyurethane-urea. These elastomers were prepared using poly(tetramethylene glycol) (Terathane 1400), 1,6-hexamethylene diisocyanate and 4,4'-diaminobiphenyl (benzidine) as chain extender and glycerin or castor oil as crosslinkers. The polyurethane-ureas were characterized through Fourier transform infrared spectroscopy, thermogravimetric analysis, differential dynamic mechanical analysis, dielectric properties. The effects of the hard segments structure on physical, dielectric, mechanical and dynamic mechanical properties of the polyurethane-urea elastomers were investigated. The presence of more urea groups in the hard segment leads to high tensile strength (60-70 MPa), high elongation (700%-950%), increased thermally stability and superior dielectric properties.

关键词： SKELETAL MUSCLE   METABOLISM   ENERGETICS   EFFICIENCY   FATIGUE   EXERCISE TOLERANCE  

摘要： JONES, A. M., B. GRASSI, P. M. CHRISTENSEN, P. KRUSTRUP, J. BANGSBO, and D. C. POOLE. Slow Component of (V) over dotO(2) Kinetics: Mechanistic Bases and Practical Applications. Med. Sci. Sports Exerc., Vol. 43, No. 11, pp. 2046-2062, 2011. The (V) over dotO(2) slow component, a slowly developing increase in (V) over dotO(2) during constant-work-rate exercise performed above the lactate threshold, represents a progressive loss of skeletal muscle contractile efficiency and is associated with the fatigue process. This brief review outlines the current state of knowledge concerning the mechanistic bases of the (V) over dotO(2) slow component and describes practical interventions that can attenuate the slow component and thus enhance exercise tolerance. There is strong evidence that, during constant-work-rate exercise, the development of the (V) over dotO(2) slow component is associated with the progressive recruitment of additional (type II) muscle fibers that are presumed to have lower efficiency. Recent studies, however, indicate that muscle efficiency is also lowered (resulting in a "mirror-image" (V) over dotO(2) slow component) during fatiguing, high-intensity exercise in which additional fiber recruitment is unlikely or impossible. Therefore, it seems that muscle fatigue underpins the (V) over dotO(2) slow component, although the greater fatigue sensitivity of recruited type II fibers might still play a crucial role in the loss of muscle efficiency in both situations. Several interventions can reduce the magnitude of the (V) over dotO(2) slow component, and these are typically associated with an enhanced exercise tolerance. These include endurance training, inspiratory muscle training, priming exercise, dietary nitrate supplementation, and the inspiration of hyperoxic gas. All of these interventions reduce muscle fatigue development either by improving muscle oxidative capacity and thus metabolic stability or by enhancing bulk muscle O-2 delivery or local (Q) over