杂交稻与常规稻的光谱特性差异初步分析

通过杂交晚稻和常规晚稻的反射光谱试验,发现杂交稻由于其生长发育特性及株型的差异,在整个生长期内其反射光谱特性与常规晚稻有着明显的差异。     

Systolic time intervals assessed by 2-D echocardiography and spectral Doppler in the horse

In the present study, the ‘acoustic windows’ for the measurement of the left ventricular systolic time intervals is studied by means of 2‐D echocardiography and cardiac Doppler ultrasonography, and the normal values in the horse (n = 112) are determined. The left ventricular isovolumetric contraction time, the pre‐ejection period (PEP), as well as the left ventricular ejection time (LVET) have been measured, and the values of the left ventricular total electromechanical systole (LVTES) and the PEP‐to‐LVET ratio have been calculated. It has been established that the most suitable window for the measurement of the aforementioned indices in 2‐D echocardiography is the right parasternal window in a view in short axis at the level of the cardiac base to measure the aortogram. In Doppler ultrasonography, the preferred window is the left parasternal using the five chambers apical view. The following values have been acquired: PEP = 0.071 ± 0.01 s; LVET = 0.532 ± 0.097 s; LVTES = 0.6 ± 0.1 s and PEP‐to‐LVET = 0.138 ± 0.025 measured by 2‐D echocardiography and PEP = 0.068 ± 0.009 s; LVET = 0.527 ± 0.076 s; LVTES = 0.598 ± 0.098 s and PEP‐to‐LVET = 0.131 ± 0.01 measured by Doppler ultrasonography.     

地物反射光谱的测试

本文讨论了双向反射率分布函数、双向反射率、双向反射率因子等光谱反射率之间的关系,并指出了在一定条件下,遥感技术中野外测量地物反射光谱所得的双向反射率因子和物理学中惯用的光谱反射率即半球反射率定义(全部反射光功率与入射光功率之比)是完全一致的.最后还讨论了在野外测量地物反射光谱时需要注意的几个具体问题.     

近红外光谱分析技术在测定饲料中植酸磷含量上的应用

植酸是一种抗营养因子。传统的用三氯化铁沉淀植酸的化学分析法费时费工,不能满足饲料工业发展的需要。为了寻求快速检测饲料中植酸磷(简称P.P.)含量的手段,本试验运用近红外光谱分析技术(简称 NIRS),分别以植酸磷含量较高的米糠饼和植酸磷含量较低的高粱为样品,对这两种饲料的化学分析法测值与近红外光谱法测值进行了比较。试验结果表明:用48个米糠饼样品和50个高粱样品进行定标,相关系数(R,下同)分别为0.901和0.890,残余标准差(RSD,下同)分别为0.06和0.03;另用不参与定标的25个米糠饼样品和21个高粱样品对定标结果进行检验,R 分别为0.803和0.917,RSD 分别为0.07和0.02。NIRS 法的分析精度基本上可以达到化学分析法的要求。作者认为,达项技术作为饲料中 PP 含量快速分析的手段是可行的。     

高山草地的光谱反射特征及其估产模型

对祁连山东段高山草地中５种植物群落的光谱反射特征进行了测试研究。结果表明：１）草本植物和灌木种群的光谱反射率在可见光波段上无显著差异，但在近红外波段存在显著差异；２）土壤背景和测试仪器高度对群落的光谱反射产生显著影响；３）植物生长盛期，可用近红外波段的反射差异来区分草地植物群落的空间分布：４）草地植物群落的地上植物量与几种变换的植被指数呈显著或极显著的非线性相关。     

毛竹林光谱特征及其与典型植被光谱差异分析

以毛竹光谱特征为研究对象,通过对光谱曲线和一阶导数曲线进行分析,探明了不同季节毛竹林的光谱特征及其与典型树种的光谱差异,为毛竹林的遥感监测提供了理论依据。研究结果表明:1)毛竹光谱曲线在可见光波段出现1个反射峰和1个吸收谷,这2个峰的对应波长分别为556和680 nm, 近红外波段的反射率明显增大。2)大年毛竹林春季和夏季的一阶导数曲线的红边波段呈“双峰”,秋季和冬季呈“单峰”,夏季的红边位于700 nm,其他季节红边位于718 nm;小年毛竹林秋季的一阶导数曲线的红边波段呈“双峰”,冬季呈“单峰”,红边均位于718 nm;不同季节毛竹林红边振幅大小依次为:春季夏季冬季秋季。3)毛竹林与其他典型植被在500～600、660～680、700～900 nm 等波段的反射率差异明显,可作为遥感监测的最佳波段,并且“绿峰”、“红谷”、红边位置、红边振幅以及红边波段的“峰型”等特征可作为毛竹林遥感识别的主要参数,监测最佳季节是春季,其次为秋季。      

几种热控涂层的真空-紫外辐照试验

无机热控涂层是航天器常用的一类热控涂层。文章采用上海硅酸盐研究所研制的真空－紫外辐照装置,选用合适的加速倍率,对国内几种常用的热控涂层进行了10000ESH以上的辐照试验,原位测量了各阶段试验样品的太阳吸收比,获得了这些热控涂层的太阳吸收比变化曲线,验证了热控涂层的“漂白效应”。相关研究结果可以为热控制专家进行热设计时提供参考。     

基于分数阶微分光谱指数的冬小麦根域土壤含水率估算模型

为探讨分数阶微分（fractional-order differentiation,FOD）技术联合光谱指数改善高光谱反演冬小麦根域土壤含水率（soil moisture content,SMC）的效果,该研究以冬小麦为研究对象,测取高光谱反射率和土壤含水率数据,将高光谱反射率经Savitzky-Golay(SG)平滑处理后计算典型光谱指数以此构建偏最小二乘回归（partial least squares regression,PLSR）、随机森林（random forest,RF）和BP神经网络（back propagation neural network,BPNN）3种土壤含水率反演模型;将高光谱反射率进行0～2.0阶（步长为0.2）的分数阶微分处理后计算比值指数（ratio index,RI）和归一化指数（normalized difference index,NDI）,分析不同阶的RI、NDI与SMC之间的二维相关性,筛选得出敏感光谱指数并分组,以此构建3种反演模型（PLSR、RF和BPNN）。结果表明：不同典型光谱指数与土壤含水率的相关性存在很大差异,相关系数波动范围在0....     

基于RGB图像光谱重建的鱼糜掺假定量检测研究

实现基于RGB图像的光谱重建对降低光谱的硬件要求、扩大其实际应用具有重大意义。该研究以鱼糜掺假检测为例,比较多元多项式最小二乘回归算法（polynomial multivariate least-squares regression,PMLR）与深度学习HRNet网络对光谱重建的性能,建立基于重建光谱多种掺假鱼糜检测模型并验证其实际应用的有效性。结果表明,2种方法的重建光谱误差较小,HRNet网络、PMLR算法重建光谱的均方根误差（root mean square error,RMSE）分别为0.010 4和0.012 6,大多数掺假检测模型有较高的预测准确性,其预测相关系数大于0.91,预测均方根误差小于9%。在基于重建光谱建立的掺假检测模型中,效果最佳的是基于PMLR算法重建光谱使用标准正态变量变换（standard normal variate,SNV）预处理的极限学习机回归模型,其预测均方根误差为3.954 4%、预测相关系数为0.983 0。因此,PMLR算法和HRNet网络均能较好的实现基于RGB图像的光谱重建,且重建光谱均能实现对鱼糜掺假样本的较好检测结果,为基于重建光谱的食品和农产品品质与安全检测提供了新思路。     

Cow‐specific diet digestibility predictions based on near‐infrared reflectance spectroscopy scans of faecal samples

This study was designed to obtain information on prediction of diet digestibility from near‐infrared reflectance spectroscopy (NIRS) scans of faecal spot samples from dairy cows at different stages of lactation and to develop a faecal sampling protocol. NIRS was used to predict diet organic matter digestibility (OMD) and indigestible neutral detergent fibre content (iNDF) from faecal samples, and dry matter digestibility (DMD) using iNDF in feed and faecal samples as an internal marker. Acid‐insoluble ash (AIA) as an internal digestibility marker was used as a reference method to evaluate the reliability of NIRS predictions. Feed and composite faecal samples were collected from 44 cows at approximately 50, 150 and 250 days in milk (DIM). The estimated standard deviation for cow‐specific organic matter digestibility analysed by AIA was 12.3 g/kg, which is small considering that the average was 724 g/kg. The phenotypic correlation between direct faecal OMD prediction by NIRS and OMD by AIA over the lactation was 0.51. The low repeatability and small variability estimates for direct OMD predictions by NIRS were not accurate enough to quantify small differences in OMD between cows. In contrast to OMD, the repeatability estimates for DMD by iNDF and especially for direct faecal iNDF predictions were 0.32 and 0.46, respectively, indicating that developing of NIRS predictions for cow‐specific digestibility is possible. A data subset of 20 cows with daily individual faecal samples was used to develop an on‐farm sampling protocol. Based on the assessment of correlations between individual sample combinations and composite samples as well as repeatability estimates for individual sample combinations, we found that collecting up to three individual samples yields a representative composite sample. Collection of samples from all the cows of a herd every third month might be a good choice, because it would yield a better accuracy.