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针对农业运载工具中滑动导轨出现的卡槽和滚轮共振造成的损坏问题,对受迫运动工况下滚轮的三向受力和滑动机构平顺度进行研究,设计一种改进型导轨滚轮系统。用信赖域迭代算法对导轨曲率进行优化,将模型分割成一系列子区域,在该子区域的信赖域内对模型进行迭代近似求解,获得满足平顺性的导轨弯曲部分尺寸参数。在ADAMS中对导轨系统滑动单元倾斜振动情况和承力单元受迫运动情况进行仿真分析,给出滑动导轨优化后的判定数据。结果表明:采用分向受力的多滚轮设计可以有效分解每组导轨滚轮机构受到的作用力,承重轮在次坐标方向的受力低于主坐标方向的7.4%,导向轮在非转向段受力小于5N提高系统的平顺性和可靠性。 相似文献
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针对重型渣浆泵在偏离设计工况运转时出现的局部磨损情况进行了研究,应用Particle模型对重型渣浆泵高浓度浆体输送进行数值模拟,并通过试验验证,分析了节流设计的重型渣浆泵在小流量工况运转时,叶轮前后背叶片的设计对泵内部局部磨损的影响.研究结果表明:节流设计的渣浆泵在小流量工况下运行时,内部流场比设计工况下更加不稳定,扬程下降3%~10%;护套内部颗粒体积分数的分布受前后背叶片影响很小,但对颗粒滑移速度会产生明显影响;当设计有前后背叶片的重型渣浆泵在小流量工况下运行时,护套与转子交界靠近隔舌处固体颗粒的滑移速度激增,产生严重的局部磨损,严重影响使用寿命;通过去除前后背叶片,可以有效降低交界处的颗粒滑移速度,减轻磨损程度;但前背叶片的去除也会造成前腔回流量大幅增加,使前腔内部旋涡强度增大,加剧前护板内侧的磨损. 相似文献
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为了对履带式混合动力推土机在全工况下的经济性进行仿真分析,对ADVISOR进行二次开发,在Matlab/Simulink环境下建立直驶和转向动力学模型、履带行走机构模型、油泵模型和分动箱模型等,进而构建了混合动力推土机及其对照机的整机仿真模型。分别对两对照机进行实机试验,并对比仿真与试验中的关键运行参数以验证模型精度。结果表明,所建立模型在全工况下具有较高的仿真精度。利用该模型进行的全工况经济性仿真分析显示,混合动力推土机在直行推土和转向中均具有显著的节能效果,采用发动机-发电机组最优效率曲线控制时节能效果得到进一步提升。 相似文献
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根据弹塑性力学理论,分析了T型导轨翘曲矫正过程中所经历的弹性加载、弹塑性反弯和卸载回弹这3个变形阶段,推导了各个阶段的矫正载荷、弯矩和行程间的关系,给出各变形阶段的载荷-行程关系式,从而建立T型导轨翘曲变形矫正的载荷-行程模型。利用该模型,可根据导轨的初始翘曲挠度快速、准确地计算出相应的矫正行程。为验证该模型的正确性,以T89/B型导轨为例进行了实验对比分析,其结果表明该理论模型与实验所得出的矫正行程间的相对误差在10%以内,该模型是切实可行的,可为T型导轨全自动翘曲矫正机的开发提供理论支持。 相似文献
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基于STELLA的循环水养殖系统池塘总氨氮动态模拟 总被引:1,自引:0,他引:1
通过对影响循环水养殖系统养殖池塘中总氨氮动态的各种因素及其因果关系的分析,得出了养殖池塘中总氨氮的理论模型.在理论模型基础上,使用STELLA系统动力学模拟软件建立了循环水养殖实验系统中池塘水体总氨氮的系统动力学模型.通过将系统设计和运行的相关参数代人到该模型中,对养殖过程中池塘中总氨氮的动态变化进行了模拟运算,模拟结果与实测值基本吻合,说明该模型对实验系统的模拟具有一定的可信度,可为循环水养殖系统的设计和运行优化提供依据. 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