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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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《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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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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土壤洞穴动物鼹鼠具有极高的挖掘效率,前足爪趾是其主要挖掘器官.分析了鼹鼠中重要种属--麝鼹(Scaptochirus moschatus)具有优良挖掘功能的前足爪趾的几何结构特征,重点分析了前足爪趾触土面的几何结构.利用体视显微镜观察分析前足爪趾的宏观几何结构,通过逆向工程技术获取爪趾三维数据点云进行特征曲线量化分析,求得前足爪趾特征轮廓线的曲率及二阶导数的变化规律:鼹鼠爪趾纵向轮廓曲率变化较小,爪趾纵向表面平顺,保证了挖掘出的洞道内壁的平整;横向轮廓曲线曲率变化较大,且横向轮廓线尖端弯曲小,中后端弯曲大,这种结构使爪趾更易入土和扩洞. 相似文献