计算机视觉测量中CCD摄像机参数的校正

在分析摄像测量坐标系的基础上，根据坐标变换的基本原理，建立了立体视觉中使用的ＣＣＤ摄像机几何模型，确定了校正系数和像距的分析与测量方法，并通过试验测得了校正系数，强调了影响校正系数测量的主要参数。     

基于AUTOSAR的天然气发动机应用层软件组件设计

基于已有的大功率6缸天然气发动机应用层控制策略,将应用层软件设计成符合AUTOSAR架构规范的软件组件,并提高应用层代码的可移植性和复用度,降低应用层软件开发过程与硬件资源的耦合度。探索应用层软件组件的设计方法,提出一种普适性较强的软件结构。利用MATLAB脚本函数文件完成软件组件的自动化配置,缩短开发周期。通过台架标定试验来验证软件组件的性能,结果证明:本文设计出的软件组件之间通信顺畅,发动机动态响应良好。     

Operative irrigation modelling for real-time applications on closed-end furrows

The complexity of physical phenomena in furrow irrigation,where numerous parameters vary with time and space, makeempirical models more operative than mechanistic models forimproving irrigation efficiency. In addition, when theseempirical models are well adapted for real-time calibration onadvance trajectory, they can be considered an efficient toolto predict irrigation performance.In the first section of this paper, the selection of operativefurrow irrigation modelling for real-time applications isdiscussed. Models derived from Horton and linear infiltrationequations through the water balance equation (WBE) arepreferred to those derived from the 2-term Philips equationand to the solution of WBE involving both the power advancefunction and Kostiakovs extended equation.The second section shows that simplified analytical modellingoptions can be added to the basic advance-infiltration modelfor improving irrigation efficiency. The modelling optiondeveloped in this paper concerns the prediction of cutoff timeand irrigation performance for closed-end furrows (CEF).The simplified analytical model for CEF based on the massconservation principle is successfully compared to field testsand numerical simulations.     

海南热区砖红壤颗粒离散元仿真模型参数标定

为获取适用于海南热区砖红壤与触土部件相互作用的离散元仿真模型参数,该文利用EDEM仿真软件中Hertz-Mindlin with JKR接触模型对海南地区砖红壤进行相关模型参数标定,首先以含水率为7.8%、实际休止角为32.35°的砖红壤为研究对象,以物理试验获取的砖红壤-砖红壤、砖红壤-触土部件间恢复系数、静摩擦系数及滚动摩擦系数为标定对象,应用Plackett-Burman设计试验筛选出对休止角有显著影响的参数:即砖红壤-砖红壤滚动摩擦系数、JKR表面能、砖红壤-28MnB5板滚动摩擦系数、砖红壤-砖红壤恢复系数。进一步以砖红壤颗粒休止角为响应值,基于Box-Behnken设计试验得到休止角与显著性参数的二阶回归模型,并以实际休止角为目标,针对显著性参数进行寻优,得到最佳组合:砖红壤-砖红壤滚动摩擦系数为0.07、砖红壤-28MnB5板滚动摩擦系数为0.24、砖红壤-砖红壤恢复系数为0.4、JKR表面能为4.31J/m^2。最后在标定的参数下进行休止角与破土阻力离散元仿真验证试验,对比计算得出仿真休止角与实测休止角相对误差为0.62%,仿真破土阻力与实测破土阻力相对误差为3.43%,并通过对比分析两次试验中破土阻力变化曲线的拟合情况,得出两曲线间的可决系数R2=0.993 9,均方根误差RMSE=0.017 7,该结果表明标定所得相关参数可用作海南热区砖红壤离散元仿真。     

用熏蒸提取法校正酸性红壤的KEC值

Commonly used K_EC value (0.45) of the fumigation-extraction (FE) method was obtained on the basis of temperate neutral soils. To ascertain its applicability to acidic red soils widespread in southern China and other subtropical regions, the K_EC value was investigated based on 8 acidic red soils by in situ labelling of native soil microorganisms using ¹⁴C-labelled glucose. Realistic K_EC value for red soils could be obtained by in situ ¹⁴C-labelling as long as an incubation period of 72 h is adopted after addition of ¹⁴C glucose to soil. The single K_EC values for the eight red soils ranged from 0.27 to 0.35 and averaged 0.31. Lower K_EC value obtained in red soils probably resulted from different soil quality, compared with other types of soil, which causes possible changes in microbial community structure and extractability of cellular component. Microbial biomass C contents of the eight red soils measured using a unique and constant K_EC value of 0.45 decreased by 22.2%~40% in comparison to those using variable K_EC values. The results suggest that microbial biomass C would be significantly underestimated using the present K_EC value and a calibration of the K_EC value is necessary for red soils.     

Changing course of secondary succession in abandoned sandy fields

The vegetation of abandoned arable fields on dry sandy soils was investigated in 1986 and again in 2000. Comparison of the two data sets by ordination, calibration based on indicator values, and statistical modelling revealed that the vegetation in 2000 differed significantly from the vegetation in 1986. Part of this difference could be explained by field age, but significant difference remained after correction for age. The analysis showed that species indicating nutrient-rich and acidic conditions were more abundant in the 2000 samples than expected from the age of the fields. Possible causes for the observed differences are discussed, and the role of airborne nitrogen deposition and landscape changes is emphasised. Changing course of successional processes may place serious constraints on future habitat restoration.     

四川盆地紫色丘陵区小流域范围内LISEM土壤侵蚀模型的校定与验证

该研究是在欧盟项目EroChiNut框架内实施,其目的是在研究区域内对LISEM土壤侵蚀模型进行验证。研究采用1次小雨和3次中雨共4次降雨过程,并将结果与1次大雨的校定结果相比较。验证结果显示在降雨初期对流量估算过高,而在降雨结束时期又过低。其原因可能是LISEM直接反应于雨强,而测定的流量则滞后。看来小流域犹如一个自然缓冲器,使第一次径流高峰滞后。造成测定和模拟峰值不吻合的另一原因可能是土壤导水率和水压的时空变异性。研究还采用了小雨对LISEM进行验证,如实测值一样,模拟的流量也很小。结果显示在用小雨进行研究时,应考虑量水槽的误差范围。在EroChiNut项目中,其误差范围可以高达6 mm(12 l/s)。同时,量水槽中泥沙淤积问题也是造成测值不准的原因。总的来说如果用相近的降雨过程对LISEM进行校定,其验证结果应更好一些。在该项研究中,如果用中等降雨过程对LISEM进行校定,应该提高验证的准确度。     

汽车跟驰状态下驾驶员反应时间研究

驾驶员反应时间是评价驾驶安全性的重要指标之一。本研究采用互相关分析法与灰色关联分析法相结合的方式对驾驶员反应时间进行标定,并结合简单反应时间、复杂反应时间双正态分布的理论假设,通过大量的实测数据对假设的合理性进行验证。结果表明,理论假设能够很好地解释反应时间的实测数据,反应时间的实测数据可以由这两个正态分布的混合分布来拟合。对跟驰状态下反应时间的深入研究,为驾驶员形成进一步的行动方案和提升驾驶安全性提供重要的理论参考。     

一次典型西风槽型降水过程的双通道微波辐射计探测分析

对2012年10月27日傍晚时分,沈阳区域气象中心大楼所在地降水过程前后的双通道微波辐射计与雨量计的测量数据进行对比分析,得到双通道微波辐射计的一些测量特征,以为人工增雨作业时机的选择提供指示作用。     

Application of the DNDC model to predict N2O emissions from sandy arable soils with differing fertilization in a long‐term experiment

Modeling crop growth and soil N dynamics is difficult due to the complex nature of soil–plant systems. In several studies, the DNDC model has been claimed to be well‐suited for this purpose whereas in other studies applications of the model were less successful. Objectives of this study were to test a calibration and validation scheme for DNDC‐model applications to describe a field experiment with spring wheat on a sandy soil near Darmstadt (SW Germany) using different fertilizer types (either application of mineral fertilizer and straw—MSI; or application of farmyard manure—FYM) and rates (low—MSI_L, FYM_L; and medium—MSI_M, FYM_M). The model test is based on a model parameterization to best describe the case MSI_L and applies this parameterization for a retrospective simulation of the other cases (MSI_M, FYM_L, FYM_M) including crop growth and N₂O emissions. Soil water contents were not accurately simulated using either the DNDC default values for a loamy sand or for the next finer texture class or using results from the pedotransfer function provided by ROSETTA. After successful calibration of the soil water flow model using a soil texture class that led to the best fit of the measured water content data, grain yield of spring wheat and cumulative N₂O emission were slightly underestimated by DNDC and were between 91% and 86% of the measured data. A subsequent calibration of the yields and cumulative N₂O emissions from soils of the MSI_L treatment gave a good prediction of crop growth and N₂O emissions in the MSI_M treatment, but a marked underestimation of yields of the FYM treatments. Cumulative N₂O emissions were predicted well for all MSI and FYM treatments, but seasonal dynamics were not. Overall, our results indicated that for the sandy soil in Germany, site‐specific calibration was essentially required for the soil hydrology and that a calibration was useful for a subsequent prediction where greater amounts of the same fertilizer were used, but not useful for a prediction with a different fertilizer type.