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针对小型带式拖拉机在使用过程中出现的安全性,对环境的适应性等方面的问题,进行了机构和技术性能等方面的综合分析,找出了影响其工作性能的主要因素,并在此基础上提出了结构改进方案。 相似文献
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我国排灌机械的研究现状与展望 总被引:6,自引:1,他引:5
排灌机械在我国农田灌溉、排涝抗旱、保障农业稳定高产及生态环境建设等方面发挥着重要作用,具有广阔的市场空间与发展前景.经过50多年的发展,排灌机械在理论研究、技术性能和制造水平等方面已经取得了长足进步,但在产品的安全可靠性、品种规格、性能质量、配套程度及售后服务等方面还有待于进一步提高.应加大新技术、新材料、新工艺在排灌机械领域的研究与应用力度,加强基础理论研究,改进和完善产品性能,提高设备与技术的可靠性、配套性和先进性,推动排灌机械向高效、多功能、低能耗、环保、智能化方向发展. 相似文献
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目前国内一些拖拉机灯具性能还不能完全达到规定的要求,而且与汽车和国外拖拉机灯具在性能方面还存在一定的差距。对照标准GB 20949-2007,GB 18447-2008,JB/T 6701-2008的有关规定,本文提出了我国拖拉机灯具在设计、制造、安装调试等方面存在的问题,同时建议进一步完善适合国内拖拉机安全性能要求的各类灯具标准,以便引导拖拉机灯具性能的不断提高。 相似文献
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制动性能是保证车辆安全可靠性的重要性能之一,而制动器是制动过程中实现制动性能的主要执行机构,是保证车辆制动性能实现的重要途径。论述了盘式制动器在热衰退等方面性能的优点,将盘式制动器引入到挂车车辆使用并对其制动安全性进行分析,得出有必要通过强制装备盘式制动器来提升挂车车辆制动安全性的结论。 相似文献
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轮式和履带式拖拉机适应性对比分析 总被引:1,自引:0,他引:1
王旭 《拖拉机与农用运输车》2006,33(1):1-2,13
拖拉机作为农业动力机械,其选型涉及到配套农具、耕作制度等诸多因素,本文以轮式拖拉机JD 4450,Zetor 16245和履带拖拉机ДT 75为例,对其结构性能、滚动阻力、附着性能、接地压力和适应性等方面在黑龙江垦区进行了对比分析,并对其选型提出了具体建议和要求。 相似文献
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2006年,京华BK6120EV型号的两台纯电动公交车样车在交通部公路交通试验场进行定型检测,作为国家863计划电动车重点课题的新车型正式交付使用。本文结合样车在试验场的定型试验和试验过程中的整改,对包括加速性能、爬坡性能、制动性能、续驶里程等检测项目进行分析,归纳了电动车辆在控制、性能、可靠性等改进的措施,并结合电动车辆国家标准要求,提出电动车辆电池组、控制策略、散热系统等方面工程化改进建议,作为电动车辆领域研究、设计和制造的参考资料。 相似文献
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钢板在镀锌后表面要进行钝化处理,但有时会出现钝化剂的性能不稳定、钝化效果不理想的现象,致使生产不能顺利进行,钝化膜的组成及结构决定它的性能。本文综述了国内外镀锌钝化层的研究现状,从镀层金属、钝化层成膜机理、膜层结构及性能等方面进行了阐述。 相似文献
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《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
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The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献
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感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
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从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性,认为在缺水不可避免的情况下,对供水进行优化调度可以减小缺水带来的损失,产生较好的减灾效益,特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性,提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献