A Top Height Equation for Pinus pinaster

A number of equations were fitted by means of stepwise regression to data from 171 compartments enumerated for working plan purposes in the southern and south-western Cape Province. Top height (= the mean height of the 100 biggest trees per ha in terms of diameter at breast height) or a function of top height was used as the dependent variable. Mean height, age (A), stems per ha (SPH) and mean diameter at breast height were used as the independent variables. The following equation gave the best results:

Top height = mean height + 0,03 log (SPH—99) A     

近红外光谱法测定DDGS中粗蛋白含量的试验研究

试验建立DDGS粗蛋白含量测定的近红外光谱分析定标模型。采用化学分析法测定72个DDGS样品中的粗蛋白含量,利用FOSS InfraXact型近红外光谱分析仪采集样品光谱,光谱经2,4,4,1导数和标准正常化+散射处理(SNV+Detrend),用改进最小二乘法(MPLS)回归,获得了较好的定标模型,校正决定系数(RSQ)、交叉验证决定系数(1-VR)、校正标准误差(SEC)、交叉验证标准误差(SECV)分别为0.982 5、0.932 8、0.266 2、0.389 5。利用30个验证集的DDGS样品进行外部检验,预测值与真实值之间差异不显著(P>0.05)。结果表明,定标模型的预测性能较好,可以替代化学分析法快速测定DDGS中的粗蛋白含量。     

Comparison and Dynamic Calibration between LAI Values of Larix principis-rupprechtii Plantation Determined by Canopy Scanner and Litter-fall Collection

In order to test the accuracy of the usually-used fixed calibration factor of the canopy scanner of LAI-2000 for measuring the leaf area index(LAI),a Larix principis-rupprechtii plantation was chosen in the small watershed of Xiangshuihe located at the Liupan Mountains of Ningxia Hui Autonomous Region of NW China,the LAI was measured in October 2010,a period from full canopy to the total fall of needles,by using both the LAI- 2000 and litterfall collection method.Then,a comparison was made between the LAI values determined by the litter-fall collection and that calculated based on the figures read from LAI-2000 and the fixed calibration factor(1.49).It showed that the average of LAI measurements of the 2 methods was very close,with a difference of only 5%.However,the calculated LAI from LAI-2000 was obviously higher than the true values determined by litter-fall collection when the canopy was full of needles;and obviously lower than the true value when the canopy was sparse after needle falling.The reason may be that LAI-2000 takes the projection of twigs as needles.So,a dynamic calibration factor is needed,especially in the seasons when the needle amount and the percentage of twigs projection in crown projection change quickly.Therefore,a statistic relation in a quadratic polynomial form between the 2 series of LAI data was well fitted. This relation can be used for a more accurate estimation of LAI based on the data read from the easilyused canopy scanners like LAI-2000.     

水稻田间肥效校正试验

为了验证"3414"试验给出的最佳施肥量和施肥比例,完善测土配方施肥模型,参照测土配方施肥肥效校正试验方案的要求,进行了水稻田间肥效校正试验。结果表明,推荐的最佳施肥量每667 m2氮肥(N46%)10.2 kg、磷肥(P2O512%)4.2 kg、钾肥(K2O 60%)5.2 kg,可获得最理想的水稻产量每667m2407.1 kg、净收入720元和净增值(除地力)2.3元,比农户习惯施肥处理分别提高2.3%、2.3%和4.5%。试验结果可为当地配方设计、施肥指导和建立并验证施肥指标体系提供依据。     

HH2型土壤湿度计测定土壤含水量的标定研究

就HH2型土壤湿度计在黄土高原沟壑区黑垆土表层的应用进行了标定研究,分析了HH2测量的准确性,各容重标定曲线的精度和灵敏度。结果表明:在各种容重条件下用HH2测量土壤水分,输出电压的变异系数小于6%,仪器的准确性较高。线性标定方程斜率a随容重的增大而增加,常数b则相反。容重标定曲线对HH2的可调参数a0、a1影响较小。当土壤水分含量为18%～19%时,不同容重的标定曲线的差别最低。     

中国地区太阳分光辐射观测网的建立与仪器标定

大规模的太阳分光地基联网观测不但能够直接为该项研究提供基础数据,同时也可为卫星遥感提供地表订正.利用性能优越的LED型太阳光度计,依托中国生态研究网络(CERN)分布在中国各地的观测站,建立了标准的太阳分光辐射观测网.利用Langley定标法结合量值传递定标法对观测网所有光度计的标定方法及误差分析表明,不同光度计间的同步观测结果(相对标准偏差小于3%)以及与CIMEL光度计的观测结果间(相对偏差小于5%)有很好的一致性,证实了观测结果的准确性以及该类型光度计及其观测网的稳定性和可靠性.     

林区地形起伏对Spot5遥感图像几何精校正的影响

为探索林区地形起伏对空间分辨率为 2 5m的Spot5遥感图像几何精校正的影响规律 ,在理论分析地形起伏造成遥感图像像点位移的基础上 ,通过比较控制点间实测距离和图像上相应距离的偏差 ,研究了林区Spot5遥感图像像点位移的变化规律 .利用GPS虚拟网络参考站定位系统 ,以厘米级精度测定校正遥感图像的地面控制点 .根据地面控制点海拔高度的差异设置 4种校正方案 ,对Spot5遥感图像进行几何精校正 .通过比较各种校正方案对图像变形的纠正效果 ,详细探讨了林区地形起伏对Spot5遥感图像几何精校正的影响规律     

多旋翼无人机载高光谱成像系统几何和辐射校正方法研究

针对农林环保等行业应用,结合成像光谱仪与无人机(unmanned aerial vehicle, UAV)技术,有效地解决了高光谱遥感数据不足和空间分辨率低等问题.但UAV高光谱成像系统面临的设备昂贵、数据质量差和效率低等一系列问题,致使低成本高效便捷的UAV高光谱成像系统成为了研究的关键.介绍了将室内成像光谱仪搭载在多旋翼UAV上采集数据的高光谱成像系统,在试验区布设控制点和标准灰布,用GPS-RTK测量控制点的三维坐标和ASD地物光谱仪测量标准灰布的反射率以验证系统的成像精度.从辐射和几何两个方面进行分析评价.在辐射方面,经过辐射定标和MODTRAN模型大气校正的高光谱数据中校准灰布的反射率与ASD地物光谱仪测量的结果十分吻合;在几何方面,用GPS-IMU数据进行初始几何校正的图像与地面控制点坐标以分析图像处理后的几何误差,并提出通过改正姿态偏转角的方法提高图像的地理位置精度.     

基于颗粒缩放的小麦粉离散元参数标定

为获得小麦粉离散元仿真精确的接触参数,将不规则形状的小麦粉简化成软质球形颗粒,利用颗粒接触缩放原理和量纲分析进行颗粒缩放,将平均粒径0.212 mm的小麦粉放大至1.2 mm,选择"Hertz–Mindlin with JKR"接触模型,利用休止角对接触参数进行标定。首先通过Plackett-Burman试验筛选出对休止角影响显著的参数:表面能JKR(Johnson Kendall Roberts)、小麦粉-小麦粉滚动摩擦系数、小麦粉-不锈钢静摩擦系数;然后根据Box-Behnken试验建立并优化休止角与显著性参数的二阶回归模型,得到显著性参数的最佳组合为JKR为0.157、小麦粉-小麦粉滚动摩擦系数为0.25、小麦粉-不锈钢静摩擦系数为0.58;最后用标定参数仿真所得休止角大小与真实试验值进行对比,二者相对误差为0.61%。结果表明标定所得的接触参数可用于小麦粉放大颗粒的离散元仿真,为定量供送螺杆的设计提供参考。