偏最小二乘回归法在海洋初级生产力影响因子分析中的应用

叶绿素a浓度是浮游植物生物量的重要指标,能反映出海洋初级生产力的状况。从海洋监测数据中,分析影响叶绿素a浓度的理化环境因子,尝试找出海洋初级生产力的主导因子。将数据标准化,运用变量投影重要性分析和T2椭圆图等辅助分析技术进行成分提取,进行偏最小二乘回归分析。实验结果表明,在贫营养化的川岛外水域,对叶绿素a影响能力最大的因子为磷酸盐和无机氮,其次为酸碱度、盐度和水温,溶解氧影响能力最小。但在富营养化的沙堤口水域,影响能力最大的因子为化学需氧量和溶解氧,水温也成为影响海洋初级生产力的重要因子,而无机氮却成为非重要因子。从以上结果可见,运用偏最小二乘回归法对叶绿素a影响因子进行探讨,既能在监测数据较少的条件下建立数学模型,又能解决多元回归分析时各理化环境因子之间存在多重相关性的问题,具有较高的相关分析精度。     

韩国农药残留肯定列表制度对我国农产品出口贸易的影响

韩国自2019年1月1日开始,对于没有制定农药残留限量标准的所有农产品实施肯定列表制度。我国是韩国的主要农产品贸易国,该制度的实施对我国农产品出口贸易造成影响。本文概述了韩国农药残留肯定列表制度,分析了可能影响我国出口的主要农产品和农药品种,提出了减少贸易影响的相关措施建议。     

Understanding effects of multiple farm management practices on barley performance

Because of the complexity of farming systems, the combined effects of farm management practices on nitrogen availability, nitrogen uptake by the crop and crop performance are not well understood. To evaluate the effects of the temporal and spatial variability of management practices, we used data from seventeen farms and projections to latent structures analysis (PLS) to examine the contribution of 11 farm characteristics and 18 field management practices on barley performance during the period 2009–2012. Farm types were mixed (crop-livestock) and arable and were categorized as old organic, young organic or conventional farms. The barley performance indicators included nitrogen concentrations in biomass (in grain and whole biomass) and dry matter at two growing stages. Fourteen out of 29 farm characteristics and field management practices analysed best explained the variation of the barley performance indicators, at the level of 56%, while model cross-validation revealed a goodness of prediction of 31%. Greater crop diversification on farm, e.g., a high proportion of rotational leys and pasture, which was mostly observed among old organic farms, positively affected grain nitrogen concentration. The highest average grain nitrogen concentration was found in old organic farms (2.3% vs. 1.7 and 1.4% for conventional and young organic farms, respectively). The total nitrogen translocated in grain was highest among conventional farms (80 kg ha⁻¹ vs. 33 and 39 kg ha⁻¹ for young and old organic farms, respectively). The use of mineral fertilizers and pesticides increased biomass leading to significant differences in average grain yield which became more than double for conventional farms (477 ± 24 g m⁻²) compared to organic farms (223 ± 37 and 196 ± 32 g m⁻² for young and old organic farms, respectively). In addition to the importance of weed control, management of crop residues and the organic fertilizer application methods in the current and three previous years, were identified as important factors affecting the barley performance indicators that need closer investigation. With the PLS approach, we were able to highlight the management practices most relevant to barley performance in different farm types. The use of mineral fertilizers and pesticides on conventional farms was related to high cereal crop biomass. Organic management practices in old organic farms increased barley N concentration but there is a need for improved management practices to increase biomass production and grain yield. Weed control, inclusion of more leys in rotation and organic fertilizer application techniques are some of the examples of management practices to be improved for higher N concentrations and biomass yields on organic farms.     

Using near-infrared hyperspectral images on subalpine fir board. Part 2: Density and basic specific gravity estimation

Abstract

Wood density (ρ_MC) and basic specific gravity (BSG) are important properties in several forest products manufacturing processes. In this study, near-infrared hyperspectral images were tested to produce two-dimensional (2D) ρ_MC and BSG images of subalpine fir (Abies lasiocarpa Hook) board. A total of 107 cubic samples with the size of 4 cm were prepared from 14 boards. All samples were dried to various moisture contents (MCs) during several steps until being completely dried. The resulting MCs ranged from 1% to 137% (dry basis). After the last drying step, the samples were soaked in water to determine BSG. Hyperspectral images and weight measurements were acquired over each sample at each drying step. ρ_MC was also estimated at each MC level. Partial least squares (PLS) models were developed for estimating both ρ_MC and BSG from the near-infrared hyperspectral imaging (NIR-HSI) system absorbance spectra acquired over all the samples during each drying step. The ρ_MC model provides a reasonable accuracy with the validation data-set (R² = 0.81, RMSE = 39 kg/m³, and RPD = 2.3). For BSG, only models built with samples having MC of less than 12% are significant. The calibration data-set provides similar accuracy as the ρ_MC model (RMSE = 0.004, R² = 0.82, and RPD = 2.28), but the accuracy is lower with the validation data-set (RMSE = 0.007, R² = 0.53, and RPD = 1.39). Our data-set has BSG values varying only from 0.326 to 0.374, and further work is needed to apply these methods to a data-set that includes a more extended range of BSG variations for improving estimation accuracy.     

基于PLS算法的生物质秸秆元素分析NIRS快速检测

为探讨利用近红外光谱技术快速检测生物质秸秆中N、C、H、S和O元素的可行性,采集并制备水稻、小麦、油菜和玉米秸秆样本199个,采用近红外光谱(NIRS)分析技术,结合偏最小二乘(PLS)化学计量学算法,在7 400~5 550cm-1波段范围内,比较不同光谱预处理方法的定标效果,建立最优的生物质秸秆中N、C、H、S和O元素的定量分析模型,并用独立的验证集样本对模型进行验证。验证结果表明:所建立的N元素的定量分析模型可用于实际检测;O元素的定量分析模型可进行实际估测;采用近红外技术用于C元素定量分析是可行的,但模型需要进一步优化;H、S元素采用NIRS技术无法进行定量分析。     

Prediction of Board Values in Pinus sylvestris Sawlogs Using X-ray Scanning and Optical Three-dimensional Scanning of Stems

As the sawmill industry strives towards customer orientation, the need for sorting of logs according to quality has been recognized, and automatic sorting based on measurements by three-dimensional (3D) optical log scanners has been implemented at sawmills. There is even a small number of sawmills using the X-ray log scanner for automatic log-sorting. At the log-sorting stage, the potential of the raw material to fulfil the needs has already been reduced by the decisions taken when the trees were bucked (cross-cut) into logs. Thus, the application of predictions of the boards’ properties at the bucking stage is desirable. This study investigates the possibility of predicting board values from logs based on 3D scanning alone and 3D scanning in combination with X-ray scanning of stems. This study is based on 628 logs scanned by computed tomography that make up the Swedish Pine Stem Bank. Simulated sawing of the logs gave product values for each log. Prediction models on product value were adapted using partial least squares regression and x-variables derived from the properties of the logs and their original stems, measurable with a 3D log scanner and the X-ray LogScanner. The results were promising. Using a 3D scanner alone, R ² was 0.68, and using a 3D scanner in combination with an X-ray LogScanner, R ² was 0.72.     

利用近红外漫反射光谱(NIRS)技术建立甘薯茎叶重金属预测模型

植物样品中的无机离子以一定形式与具有近红外吸收的有机基团结合,因而可以借助近红外光谱技术测测其含量.探讨研究了近红外光谱法快速预测甘薯叶和茎镉、铜、锌含量的可行性,以不同肥料种植的甘薯叶和茎样品各67份,利用偏最小二乘回归法(PLS)对甘薯叶和茎中水分、蛋白质、镉、铜、锌含量进行预测分析.结果表明:所建模型可用于快速预...     

生态赤字影响因素的定量分析及其动态预测研究--以江苏省为例

以江苏省为例,选取表征社会经济发展的重要指标建立社会经济系统指标体系,在对江苏省1985-2009年生态赤字时间序列计算分析的基础上,综合运用STIRPAT模型、变量投影重要性指数(VIP)和偏最小二乘(PLS)方法构建了江苏省生态赤字动态预测模型,对江苏省"十二五"规划期间生态赤字的发展情况进行了动态预测。结果表明,"十二五"规划期间,江苏省总生态赤字将从2009年的1.156 1×108 hm2上升至2015年的1.418 4×108 hm2,呈整体上升趋势,人均生态赤字从2009年的1.496 7hm2上升至2015年的1.768 8hm2,高于全球平均水平(0.400 0hm2),且江苏省不存在生态赤字EKC曲线的有关假说;根据VIP值得出"十二五"规划期间江苏省生态赤字持续增加的重要驱动因素,且按其影响的重要性排序依次为:二三产业产值占总产值比重>农作物总播种面积>人均GDP>普通高等学校师生比>卫生机构床位数>货运周转量>总人口数。最后就如何实现江苏省"十二五"规划目标提出相关政策建议。