关键词： 事故预防   农用设备   农业机械   接触安全装置   危险区   定义   危害   机械工程   职业安全   安全装置   安全工程   机械安全   安全要求   整地机具   规范   用户信息   工作场所安全  

标准号: BS EN ISO 4254-5-2009

摘要： This part of ISO 4254, intended to be used together with ISO 4254-1, specifies the safety requirements andtheir verification for the design and construction of mounted, semi-mounted and trailed power-drivensoil-working machines used in agriculture. In addition, it specifies the type of information on safe workingpractices (including residual risks) to be provided by the *** part of ISO 4254 deals with significant hazards (as listed in Annex A), hazardous situations and eventsrelevant to power-driven soil-working machines used as intended and under the conditions foreseen by themanufacturer (see Clause 4).This part of ISO 4254 is not applicable to:- spading machines;- machines fitted with a retractable device making them capable of working between two successive plantsin the same *** part of ISO 4254 is not applicable to environmental hazards or electromagnetic compatibility. It is notapplicable to hazards related to moving parts for power transmission, except for strength requirements forguards and barriers, nor to maintenance or repairs carried out by professional service *** 1 Specific requirements related to road traffic regulations are not taken into account in this part of ISO *** 2 Vibrations are not regarded as a significant hazard in the case of mounted, semi-mounted or trailed *** part of ISO 4254 is not applicable to power-driven soil-working machines which are manufactured beforethe date of its *** requirements of this part of ISO 4254 are different from those which are stated in ISO 4254-1, therequirements of this part of ISO 4254 take precedence over the requirements of ISO 4254-1.

关键词： Flagellin   Flagellar export   Force-denaturation   Protein mechanics   Multi-domain  

摘要： Bacterial flagellum is a nano-scale motility device constructed by self-assembly. During construction of the cell-exterior filament (the 'propeller'), subunit proteins (called flagellin) are thought to be exported through the hollow flagellum to the growing filament tip in an unfolded state. To gain insight into the unfolded state preceding any force-spectroscopy experiments on flagellin, we employed force-probe molecular dynamics simulations. Two schemes to attain an unfolded state suitable for efficient transport were examined: (i) stretching flagellin along its length;(ii) unzipping flagellin from its adjacently placed termini. Atomic-level unfolding pathways and the mechanical efforts involved under each scheme were obtained for the four-domain flagellin from S. typhimurium. Flagellin appeared stiffer and required larger unfolding forces when stretched as the relative sliding of beta-strands require the breaking of multiple hydrogen bonds at once. In contrast, unzipping requires lower unfolding forces as it mainly involves unraveling beta-sheets by breaking hydrogen bonds one by one. (C) 2009 Elsevier Inc. All rights reserved.

关键词： Nanostructured materials   Surface mechanical attrition treatment   Hot-working tool steel   Duplex chromizing treatment   Diffusion  

摘要： A nanostructured surface layer of about 20 mu m in thickness was fabricated on a hot-working tool steel (AISI H13) plate by means of surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated in comparison with its coarse-grained counterpart. Relative to the coarse-grained form, the Cr-diffusion depth was obviously enhanced by SMAT at various chromizing temperatures, with a maximum increment at 600 degrees C. A duplex chromizing treatment at 600 degrees C followed by at a higher temperature led to the formation of a much thicker chromized surface layer (up to 30 mu m in thickness) on the SMAT sample. This might be attributed to the formation of a large amount of nanosized chromium compounds in the surface layer at 600 degrees C, which retarded growth of nano-sized ferrite grains and improved the Cr diffusion at higher temperatures. Gradient distributions of Cr concentration, microstructure and hardness were formed in the chromized surface layer in the SMAT steel after the duplex chromizing treatment, leading to an obvious enhancement in the wear resistance. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Ethylene-norbornene copolymers   Mechanical relaxation   Molecular motions  

摘要： Dynamic mechanical studies of Molecular dynamics have been performed for two ethylene-norbornene copolymers. The analysis of data indicates the existence of three relaxation processes: a primary (alpha) and two secondary (beta and gamma) ones. It was found that the secondary processes beta and gamma are connected with the local motions of ethylene and norbornene groups, respectively and that their rates follow the Arrhenius relation. Moreover, the beta process was recognized as the Johari-Goldstein process acting as the precursor of the cooperative structural alpha-relaxation. Contrary to gamma and beta processes, the motional rate of alpha-one follows the Vogel-Fulcher-Tammann equation indicating the cooperative nature of motions involved in this process. An increase in norbornene content in copolymer slows down the molecular dynamics of both norbornene fragments and whole chains, and in consequence shifts these relaxation Processes into higher temperatures. Using the Havriliak-Negami formalism the motional parameters for the processes mentioned above were estimated. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： 园林机械   汽油机   草坪割草机   术语   定义   技术要求   试验   检验   标志   使用说明书   包装   运输   贮存  

标准号: LY/T 1202-2010

摘要： 本标准规定了以汽油机为动力的步进式草坪割草机（以下简称草坪机）都属于和定义、型号编制方法、技术要求、试验方法、检验规则、标志、使用说明书及包装、运输和贮存。 本标准适用于以汽油机为动力的步进式草坪割草机。 本标准不适用于坐骑式草坪机，不适用于悬挂乘人部件的拖乘机组，也不适用于切割部件为非金属柔线或自由定心式非金属切割器、每个切割部件的切割能力（动能）不大于10J的草坪机。

关键词： Glass forming ability   Thermal stability   Non-isothermal crystallization   Mechanical property  

摘要： The glass forming ability (GFA), thermal stability, non-isothermal crystallization kinetics, and mechanical property of Zr61.5Al10.7Cu13.65Ni14.15 glass forming alloy were investigated. Its maximum glass forming dimension reaches up to 5.5 mm and its critical cooling rate is less than 40 K s(-1). The apparent activation energies for glass transition Eg, onset crystallization Ex, and crystallization peak E-p are 214.56 +/- 16.14, 267.42 +/- 9.36, and 305.69 +/- 7.31 kJ mol(-1), respectively. Small fragility parameter m about 17 indicates its better thermodynamic stability and GFA. In addition, its elastic strain limit, compressive strength, and Young's modulus are 2.73%, 1.81 GPa, and 70.47 GPa, respectively. Its V-shape fracture mode is different form other bulk metallic glasses. (C) 2009 Elsevier B.V. All rights reserved.

关键词： 并联机器人   动力性能   尺度综合  

摘要： 研究广泛用于高速抓放操作的Delta机械手动力尺度综合方法。在建立系统运动学和刚体动力学模型的基础上,利用奇异值分解原理,提出一种基于单轴最大驱动力矩全域最大值最小的动力学性能评价指标。该指标可表示为系统尺度和惯性参数及位形的显函数形式,可直接用于观察奇异位形的出现条件。在考虑工作空间/机构尺度比、速度、精度和刚度等尺度和映射特性约束基础上,利用工程实例研究映射特性约束对尺度参数和动力学性能评价指标的影响规律,并据此综合出一组在满足上述约束条件下使得系统动力学性能最优的尺度参数。

关键词： 机械表   发现时间   擒纵机构   咖啡机   摆幅   表业   传动机构   机械结构   运行精度   机械系统  

摘要： 现代社会,时间的度量可以通过手机、电脑时钟,或者客厅的咖啡机来实现,时针、分针的缓慢走动对于现代人而言犹如来自异域的陌生事物。渐渐地,人们发现时间并不是想象的那么简单,简单到两根指针可以涵盖。它仿佛心脏的跳动,在他(它)们独处的那一刻,齿轮的啮合,摆轮的摆动,摆幅和位置的偏差,以及对于动力的需要传入了他们的耳朵,犹如触摸到了自己的脉搏那般……

关键词： 农业机械   总动力   时间序列   自相关   模型  

摘要： 对一个地区的农业机械总动力及其影响因素进行分析可为当地农业机械化发展目标的制定提供可靠依据。本文采集了江苏省1989～2006年的相关数据,对江苏省农业机械总动力及其影响因素进行了相关性分析分析,并用自相关时间序列回归分析方法建立了模型。结果表明,影响农业机械总动力的6个关键因素的相关性排序为:农村剩余劳动力转移率、农村居民家庭人均纯收入、粮食播种面积、政府的财政投入、农民受教育程度和粮食单产,它们与农业机械总动力的相关系数分别为0.9396、0.9384、0.8924、-0.8778、0.8671和0.7224,并得出了较高精度的农业机械总动力的自相关时间序列回归模型(R2=0.998),模型预测结果的平均偏差为0.68%。

关键词： 工程钻机   液压动力头   多功能   机械厂   履带   探矿   西安   回转钻进  

摘要： 1 用途主要适用于硬质合金回转钻进、螺旋钻进、潜孔钻进、跟管钻进、旋喷(摆喷、定喷)工程施工等多种钻进工艺方法.可广泛用于:隧道管棚支护、深基坑锚固、抗浮锚固、路基堤坝加固、地源热泵孔、水文水井、基桩施工及地质灾害治理等工程领域.