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1.
针对甘薯秧蔓机械化回收过程中离散元仿真研究缺乏准确参数值的问题,采用直接测量和虚拟标定相结合的方法对碎甘薯茎秆和叶片离散元仿真参数进行研究。采用物理试验法获得碎甘薯秧的本征参数、碰撞恢复系数等参数值及碎甘薯秧颗粒的静摩擦系数参数范围,并为离散元法仿真设计了不同的参数组合。通过堆积角优化仿真试验确定甘薯叶片本征参数及其他不易直接测量的离散元仿真参数。Plackett-Burman试验表明,甘薯茎秆—甘薯茎秆和甘薯茎秆—45钢的静摩擦系数、甘薯茎秆—甘薯茎秆和甘薯茎秆—甘薯叶的滚动摩擦系数均显著影响堆积角。运用最陡爬坡试验和Box-Behnken优化试验标定了对碎甘薯秧堆积角有显著影响的参数值,以得到的参数进行颗粒堆积仿真试验,测得堆积角平均值为40.51°,与实测值相对误差为0.972%,说明物理试验加优化仿真试验来标定离散元参数是可行的,标定所得的参数可作为甘薯秧茎叶离散元仿真参数。 相似文献
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A field calibration experiment was carried out on salt‐affected clayey soil in Syria, to compare the sensitivity to soil electrical conductivity (ECe), and bulk density (ρb) of two instruments for estimating soil moisture: the neutron probe (NP) and the Diviner 2000 capacitance probe (CP). The results showed that the values of the correlation coefficient of the calibration were decreased when the ECe and ρb values increased; this decrease was more pronounced for the Diviner 2000, indicating that it was more sensitive to ρb and ECe than the NP. When only scaled frequency was used in the fitted equation, the Diviner 2000 in wet soil underestimated soil water content significantly at all depths, but especially in the top layer, by up to 0.09 cm3/cm3 compared with gravimetric determinations. However, in dry soil, the Diviner 2000 overestimated the volumetric water content by up to 0.05 cm3/cm3 in the top 15 cm, and by 0.03 cm3/cm3 at 30‐45 cm depth. The performance of the neutron probe was better overall; using a factory calibration curve no significant differences were observed between NP estimates and the gravimetric values. Including both ρb and ECe in the calibration equations improved the fits, although the regression coefficient (R2) for the Diviner 2000 remained low. 相似文献
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The two methods of estimating parameter in computable general equilibrium(CGE) model are introduced and compared:the calibration procedure and econometric estimation. The conclusions are:the estimation of parameter in CGE model must use the calibration procedure coupled with the econometric estimation method;the elasticity of output with respect to labor input,the marginal expenditure share for households and price elasticity of export demand are estimated by econometric estimation method;and other parameters of the CGE model can be get by calibration procedure. 相似文献
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In the past, the criterion for calibration has almost invariably been the stellar oriented ballistic camera,the method is a point to point comparison on the identical coordinate system. Deficiencies is follows: The request of weather is severe(cloudless night); The period is often long; the measure equipment of high precision can't be calibrated. While EMBET methods is used in calibration, it does not need criterion and it demands only that the measure elements is larger than 3,and the trajectory and many system errors of the measure elements can be simultaneously calculated with the measure data sequences. The error models of related equipments' measure elements and the EMBET of typical equipment group are given. The EMBET method is successfully used in Accuracy-analysis of Satellite Launch. 相似文献
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基于机器视觉的无损检测是植物生长建模的关键技术之一,对图像采集系统进行标定是实现无损检测的基本步骤.目前,摄像机标定的方法有传统标定方法、主动视觉标定法、自标定方法等.为此,对现有标定方法分别进行了讨论与比较,结果表明,传统线性标定法可以满足农作物无损检测的要求. 相似文献
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R. Ramesh Kumar L. Prasanna Anjaneya ReddyJ. Vinay Kumar K. KomaraiahS. Purnanand K.P. Sastry 《Industrial Crops and Products》2012,35(1):199-202
Ashwagandha (Withania somnifera) is an important medicinal plant and its dried roots are used in traditional systems of medicine. The market price of roots is determined by physical (textural) quality. Brittle roots with high starch and low fiber are considered to be superior because of ease in grinding. Genetic diversity studies based on root textural parameters have not been done so far. So the present study was designed to assess genetic diversity for morphometric traits and root textural quality parameters among two morphologically distinct groups: Poshita and Nagore. The PCA separated the morphometric and root texture variables distinctly into two different principal components: PC-1 and PC-2 respectively, indicating that both are negatively associated. All the morphotypes in Poshita group showed high positive loadings in PC-1 indicating that component genotypes are high root yielding. Nagore morphotypes were low yielding but the root texture was good. Clustering of morphotypes grouped Poshita and Nagore separately with high inter-cluster distances indicating that both groups are highly divergent from each other, suggesting that there is sufficient scope for varietal improvement through hybridization. 相似文献
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Sensitivity analyses using a one-at-a-time approach were carried out for leaching models which have been widely used for pesticide registration in Europe (PELMO, PRZM, PESTLA and MACRO). Four scenarios were considered for simulation of the leaching of two theoretical pesticides in a sandy loam and a clay loam soil, each with a broad distribution across Europe. Input parameters were varied within bounds reflecting their uncertainty and the influence of these variations on model predictions was investigated for accumulated percolation at 1-m depth and pesticide loading in leachate. Predictions for the base-case scenarios differed between chromatographic models and the preferential flow model MACRO for which large but transient pesticide losses were predicted in the clay loam. Volumes of percolated water predicted by the four models were affected by a small number of input parameters and to a small extent only, suggesting that meteorological variables will be the main drivers of water balance predictions. In contrast to percolation, predictions for pesticide loss were found to be sensitive to a large number of input parameters and to a much greater extent. Parameters which had the largest influence on the prediction of pesticide loss were generally those related to chemical sorption (Freundlich exponent nf and distribution coefficient Kf) and degradation (either degradation rates or DT50, QTEN value). Nevertheless, a significant influence of soil properties (field capacity, bulk density or parameters defining the boundary between flow domains in MACRO) was also noted in at least one scenario for all models. Large sensitivities were reported for all models, especially PELMO and PRZM, and sensitivity was greater where only limited leaching was simulated. Uncertainty should be addressed in risk assessment procedures for crop-protection products. 相似文献