共查询到20条相似文献,搜索用时 62 毫秒
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水射流切割技术作为一种"冷"切割工艺,具有切割时无热变形,切口光滑无毛刺,切割精度高的优点,其适用于各种材料的切割加工,有"万能切割机"之誉,另外,水射流切割技术加工过程不会产生污染环境的废物,水可以循环利用,属于环境友好型技术。本文对水射流切割专利技术进行分析,阐述了水射流切割技术领域专利申请发展趋势,并追踪了水射流切割整体发展路线。 相似文献
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巨菌草收割是菌草产业中劳动强度最大的工作环节之一。在国内,目前对巨菌草切割的相关研究较少,没有有效巨菌草茎秆切割装置。首先,通过对巨菌草的茎秆拉伸、压缩和弯曲等力学特性,以及直径和含水率等影响茎秆的抗拉压强度因素进行综述,对比不同的茎秆切割器研究现状得出:合理匹配圆盘式切割器结构参数与运动参数能够减小重割和漏割,而往复式切割的切割速度对剪切力影响较小,切割间隙和切割刀片组合形式对剪切力影响大。其次,指出虚拟仿真技术这一较新的技术领域,为探究切割装置提供了新的技术方法。最后,提出巨菌草收割目前存在的问题以及切割装置在未来应向智能化和多功能化发展的观点。 相似文献
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介绍了新疆采棉杌机头部分零件的特征,对比分析了过去和现在采用的制造工艺,并简单介绍了激光切割技术和DMG60数控加工技术在采棉机机头零件制造中的运用。 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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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
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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