MODIS土地利用/覆被多时相多光谱决策树分类

利用MODIS多时相与多光谱结合,尝试探讨低成本、高精度的北京土地利用/覆被实时获取方法。首先根据归一化植被指数（NDVI）的均值、标准差建立了研究区各地类的典型NDVI时间序列曲线,进而提取了6个可以反映区域物候模式、植被生长速率等信息的分类参数;然后对反映地表土壤信息较多的3月份多光谱影像进行主成分变换,选取第一主成分（PC1）作为辅助分类参数;最后基于分类回归树（CART）算法进行监督决策树分类。经SPOT-5影像验证,分类总体精度达到83%,Kappa系数为0.769,PC1辅助分类后总体精度提高     

宇宙射线中子法测量区域土壤水分准确性季节变化研究

为证实典型气象条件下宇宙射线中子法测量区域土壤水分准确性的差异和应用普适性,以季节为时间划分尺度,并选取典型气象条件时段,对比研究山地地形下垫面宇宙射线中子法(CRNS)与频域反射法(FDR)土壤水分连续观测效果差异.结果 表明:山地地形下垫面,CRNS水平测量足迹的季节变化较为稳定,垂直足迹在耕作层范围内有一定波动....     

基于Mask-RCNN的复杂背景下多目标叶片的分割和识别

在基于叶片图像进行植物识别和生长状态监控时,植物目标叶片的准确分割和识别是前提和基础,但复杂背景给叶片的分割和识别带来了极大的挑战。本研究提出基于Mask-RCNN深度学习网络分割和识别复杂背景下多目标叶片的算法,共拍摄自然生长状态下常见的植物叶片图像7 357张,标注3 000张作为训练数据库,这3 000张图像共包含4种植物,分别为孔雀竹芋(Calathea makoyana)、珊瑚树(Viburnum odoratissinum)、洋常春藤(Hedera helix L.)和黄花羊蹄甲(Bauhinia tomentosa)。选择这4种植物的80个测试样本图像进行分割、识别与错分率分析。结果表明:Mask-RCNN深度学习网络对这4种植物的识别效果良好,未出现误识别的情况;分割的平均图像错分率为0.93%,最大值不超过2.49%,即分割准确率达97.51%;同时该算法具有强大的迁移能力。     

思茅区森林生物量分层抽样调查设计

基于普洱市思茅区森林资源二类调查数据,以森林起源、地类、龄组、优势树种作为分层变量,在95%的可靠性下,设置95%,90%和85%的抽样设计精度分层抽样进行森林生物量估测,将抽样调查结果与系统抽样方法进行比较。结果表明:1)分层抽样具有样本数量少、抽样精度高的明显优势,在普洱市思茅区,按85%的设计精度,按优势树种的分层抽样比系统抽样的效率约提高了52%;2)采用单变量进行分层抽样,优势树种具有显著优势。按85%的设计精度,在样本数量为44个的前提下,其实际抽样精度达到87.82%。     

The use of incidence counts for estimation of aphid populations. 2. Confidence intervals from fixed sample sizes

Two approaches have been used in the monitoring of local populations of cereal aphids: direct counting of aphids on a number of tillers, and the less time-consuming assessment of incidence levels (the proportion of tillers infested). This paper compares the accuracy of these two methods, using a fixed sample size, as is desirable in a practical monitoring system. It is shown that the two methods are equally reliable over a range of incidence levels, but that the confidence intervals for the population density are very broad. Reduction of these sampling error requires a considerable increase in sample size, so they should instead be taken into account in the management decision-making process.Samenvatting Er worden doorgaans twee methoden gebruikt om de dichtheid van graanluizen vast te stellen: directe telling en bepaling van het bezettingsperentage. De nauwkeurigheid van deze twee methoden wordt hier vergeleken bij een constante monstergrootte, die gewenst is bij praktische waarnemingssystemen. De beide methoden zijn even betrouwbaar over een reeks van bezettingspercentages, maar de betrouwbaarheids-intervallen zijn erg ruim. Verkleining van deze bemonsteringsfouten vereist een aanzienlijke toename van de monstergrootte, zodat het waarschijnlijk beter is deze fouten in het beslissingsproces voor de bestrijding te betrekken.     

Assessment of different methods to estimate bovine colostrum quality on farm

AIMS: To evaluate two different hydrometers and an optical and a digital Brix refractometer for the assessment of bovine colostrum quality, in terms of accuracy and precision compared with the measurement of IgG concentrations using radial immunodiffusion (RID), and to evaluate the reliability and repeatability of the Brix refractometers.

METHODS: To determine reliability and repeatability, 145 colostrum samples were tested by two independent observers twice, using the optical and digital Brix refractometers. A further 193 colostrum samples from Holstein cows were collected on one commercial dairy farm at first milking and tested with two hydrometers and an optical and digital Brix refractometer. An aliquot of each sample was frozen for RID measurement of IgG concentrations and samples were classified as poor (≤50 g IgG/L) or good (>50?g?IgG/L) quality colostrum. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-observer reliability and repeatability. Optimised cut-off values for the four devices were determined using receiver operating characteristics (ROC) analysis with the RID results as the reference. Using these cut-offs, sensitivities and specificities for determining good quality colostrum were calculated.

RESULTS: The ICC for inter-observer reliability was 0.98 for the optical Brix refractometer, and for intra-observer repeatability was 0.97 and 0.98 for the optical and the digital Brix refractometers, respectively. For the 193 colostrum samples, 67 (34.7%) had concentrations of IgG ≤50 g/L determined by RID. Optimised cut-off values evaluated by ROC analysis were higher for all devices compared with manufacturer reference or previously published values. Using these values, the sensitivities for the two hydrometers, and the optical and the digital Brix refractometers were 0.73, 0.71, 0.56 and 0.79, respectively; specificities were 0.72, 0.61, 0.90 and 0.69, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE: The Brix refractometers provided the most accurate assessment of colostrum quality of the devices evaluated, and demonstrated excellent precision in terms of repeatability. To provide optimal health for newborn calves, a sufficient intake of good quality colostrum is essential. The Brix refractometers provide rapid, convenient tools for classification of colostrum quality.     

基于GBLUP和Bayes方法实现山羊体重基因组选择

为有效实现山羊基因组选择,提高选择准确性,根据前期对内蒙古绒山羊生产性能的遗传评估结果,以山羊的体重(h2=0.11)性状为例,结合NCBI已经公布的山羊基因组序列信息,设定群体传递过程和基因组参数,模拟获得个体表型和基因型数据,利用GBLUP和Bayes方法进行基因组育种值估计。结果表明,不同历史群体变化模式下,基因组选择对山羊体重基因组育种估计值准确性无显著影响(P>0.05)。GBLUP法估计的准确性高于Bayes Lasso,准确性达0.40。在历史群体下降模式下,基因组选择准确性高于恒定模式。     

Interpretation of lysimeter weighing data affected by wind

Weighing lysimeters are valuable devices for measuring water‐balance components with high temporal resolution and high accuracy. However, some older lysimeter facilities still operate with lever‐arm‐counterbalance weighing systems that are sensitive to disturbances, e.g., forces exerted by wind. Filtering and averaging are commonly used for processing noisy raw data. We studied some data of a lever‐arm weighing system and performed additional experiments in order to (1) determine the measurement accuracy of the current weighing scheme (facility, and measuring and averaging procedure) regarding wind effects, (2) describe the oscillation behavior, (3) test the mechanical performance of the system, and (4) adapt the averaging procedure with respect to improved interpretation of the weighing data. The measurement accuracy for a wind velocity < 5 m s^–1, measured in 10 m height, was ≈ ± 0.4 kg (equivalent to ± 0.14 mm); at a higher wind velocity, the accuracy was three times lower, but there was no linear relationship. Additional experiments showed that the weighing system is oscillating with more or less irregular amplitudes. A loading–unloading experiment delivered proper results of the measured loads. The mechanical system reacted immediately, and no directional effects were found. However, small changes of < 1 kg could hardly be determined due to the oscillations. A time series of raw data measured every 2 s served as basis for improving the averaging method. A moving average from 64 values was computed representing the currently used method, and serving as reference. With this procedure an accuracy of ± 0.38 kg could be reached. Averaging 150 values led to an accuracy of ± 0.28 kg (0.1 mm) for a wind velocity < 5 m s^–1.     

养鸡光照自动控制装置的研制

本文论述采用电子控制技术、研制的补光自动控制装置。该装置解决了由人工控制带来的准确性差、经济性差的问题