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Estimation of spectral responses and chlorophyll based on growth stage effects explored by machine learning methods

The Crop Journal 2022年第5期10卷 1292-1302页

作者： dehua gao Lang Qiao Lulu An Ruomei Zhao Hong Sun Minzan Li Weijie Tang Nan Wang Key Laboratory of Modern Precision Agriculture System Integration Research Ministry of EducationChina Agricultural UniversityBeijing 100083China Key Laboratory of Agricultural Information Acquisition Technology Ministry of Agriculture and Rural AffairsChina Agricultural UniversityBeijing 100083China Yantai Institute of China Agricultural University Yantai 264670ShandongChina

Estimation of leaf chlorophyll content(LCC) by proximal sensing is an important tool for photosynthesis evaluation in high-throughput phenotyping. The temporal variability of crop biochemical properties and canopy structure across different growth stages has great impacts on wheat LCC estimation, known as growth stage effects. It will result in the heterogeneity of crop canopy at different growth stages, which would mask subtle spectral response of biochemistry variations. This study aims to explore spectral responses on the growth stage effects and establish LCC models suited for different growth stages. A total number of 864 pairwise samples of wheat canopy spectra and LCC values with 216 observations of each stage were sampled at the tillering, jointing, booting and heading stages in 2021. Firstly, statistical analysis of LCC and spectral response presented different distribution traits and typical spectral variations peak at 470, 520 and 680 nm. Correlation analysis between LCC and reflectance showed typical red edge shifts. Secondly, the testing model of partial least square(PLS) established by the entire datasets to validate the predictive performance at each stage yielded poor LCC estimation accuracy. The spectral wavelengths of red edge(RE) and blue edge(BE) shifts and the poor estimation capability motivated us to further explore the growth stage effects by establishing LCC models at respective growth ***, competitive adaptive reweighted sampling PLS(CARS-PLS), decision tree(DT) and random forest(RF) were used to select sensitive bands and establish LCC models at specific stages. Bayes optimisation was used to tune the hyperparameters of DT and RF regression. The modelling results indicated that CARS-PLS and DT did not extract specific wavelengths that could decrease the influences of growth stage effects. From the RF out-of-bag(OOB) evaluation, the sensitive wavelengths displayed consistent spectral shifts from BE to GP and from RE to RV from t

关键词： Wheat chlorophyll content Growth stage effects Sensitive wavelengths Spectral response Random forest

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Estimation of chlorophyll content in maize canopy using wavelet denoising and SVR method

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International Journal of Agricultural and Biological Engineering 2018年第6期11卷 132-137页

作者： Haojie Liu Minzan Li Junyi Zhang dehua gao Hong Sun Liwei Yang Key Laboratory of Modern Precision Agriculture System Integration Research Ministry of EducationChina Agricultural UniversityBeijing 100083China Key Laboratory of Agricultural information acquisition technology Ministry of AgricultureChina Agricultural UniversityBeijing 100083China

In order to estimate the chlorophyll content of maize plant non-destructively and rapidly,the research was conducted on maize at the heading stage using spectroscopy *** spectral reflectance of maize canopy was measured and processed following wavelet denoising and multivariate scatter correction(MSC)to reduce the noise ***,the signal to noise ratio(SNR)and curve smoothness(CS)were used to evaluate the denoising effect of different wavelet functions and decomposition *** a result,the Sym6 wavelet basis function and the 5th level decomposition were determined to denoise the original *** MSC method was used to eliminate the scattering effect after *** three spectral ranges were extracted by interval partial least squares(IPLS)including the 525-549 nm,675-749 nm and 850-874 ***,the chlorophyll content estimation model was developed by using support vector regression(SVR)*** calibration Rc2 of the SVR model was 0.831,the RMSEC was 1.3852 mg/L;the validation Rv2 was 0.809,the RMSEP was 0.8664 mg/*** results show that the SNR and CS indicators can be used to select the parameters for wavelet denoising and model can be used to estimate the chlorophyll content of maize canopy in the field.

关键词： maize canopy spectral reflectance wavelet denoising SVR model chlorophyll content

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A novel wavelength selection strategy for chlorophyll prediction by MWPLS and GA

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International Journal of Agricultural and Biological Engineering 2019年第5期12卷 149-155页

作者： Haojie Liu Minzan Li Junyi Zhang dehua gao Hong Sun Man Zhang Jingzhu Wu Key Laboratory of Modern Precision Agriculture System Integration Research Ministry of EducationChina Agricultural UniversityBeijing 100083China Key Laboratory of Agricultural Information Acquisition Technology Ministry of Agriculture and Rural AffairsChina Agricultural UniversityBeijing 100083China Beijing Key Laboratory of Big Data Technology for Food Safety Beijing Technology and Business UniversityBeijing 100048China

The research proposed a novel wavelength selection strategy by the combination of moving window partial least squares(MWPLS)and genetic algorithm(GA)for the chlorophyll content detection of winter wheat canopy using spectroscopy ***,the original spectral dataset was pre-processed by wavelet denosing,multiple scatter ***,abnormal data samples were removed by Pauta Criterion and the dataset was divided into modeling set and validation set by ***,the sensitive wavebands were selected using MWPLS method and MWPLS+GA respectively and partial least squares(PLS)models were established for chlorophyll content *** the model established by using all the wavebands in the region of 400-900 nm,its R_(c)^(2) and R_(v)^(2) were 0.4468 and 0.3821 respectively;its modeling root mean square error(RMSEM)and verification root mean square error(RMSEV)were 2.9057 and 1.7589 *** the model established by using 151 wavebands selected by MWPLS,its R_(c)^(2) and R_(v)^(2) were 0.6210 and 0.5901 respectively;its RMSEM and RMSEV were 2.4007 and 1.6408 *** the model established by using 36 wavebands selected by MWPLS+GA,its R_(c)^(2) and R_(v)^(2) were 0.7805 and 0.7497 respectively;its RMSEM and RMSEV were 1.8504 and 1.1315 *** results show that wavelength selection can remove redundant information and improve model *** strategy of combining MWPLS with GA has also been proved to work well in selecting sensitive wavebands for chlorophyll content prediction.

关键词： MWPLS GA canopy spectral reflectance Chlorophyll content prediction

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利用S波源VSP四分量检测裂缝

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石油地球物理勘探 2001年第1期36卷 93-99页

作者：高希勤高爱荣于德华白俊辉高宏洁 CNPC物探监理中心中原油田计算中心石油地球物理勘探局第二地质调查处

本文利用 S波源 VSP四分量资料进行裂缝检测。首先利用非零偏 P波对 S波源进行定位 ,再利用 Alford旋转分离出快、慢横波 ,并求出快、慢波时差 ;最后用快、慢波时差计算各向异性因子以及裂缝密度。处理结果与钻井资料对比证明 ,S波源 VS... 详细信息

本文利用 S波源 VSP四分量资料进行裂缝检测。首先利用非零偏 P波对 S波源进行定位 ,再利用 Alford旋转分离出快、慢横波 ,并求出快、慢波时差 ;最后用快、慢波时差计算各向异性因子以及裂缝密度。处理结果与钻井资料对比证明 ,S波源 VSP四分量资料是研究岩体应力和裂缝结构的有力工具。

关键词： S波 VSP 钻井资料裂缝方位裂缝密度慢横波时差波源证明有效方法

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一种新的注册表隐藏Rootkit检测方案

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江苏大学学报（自然科学版） 2010年第3期31卷 328-333页

作者：张登银高德华李鹏南京邮电大学计算机学院江苏南京210003

为了检测通过篡改注册表文件而实现潜行于操作系统的Rootkit,分析了常见的Rootkit注册表隐藏技术以及相应的检测技术,并指出了当前检测技术存在的缺陷.在分析注册表文件的格式以及注册表操作控制流程的基础上,设计并实现了一种新型的注... 详细信息

为了检测通过篡改注册表文件而实现潜行于操作系统的Rootkit,分析了常见的Rootkit注册表隐藏技术以及相应的检测技术,并指出了当前检测技术存在的缺陷.在分析注册表文件的格式以及注册表操作控制流程的基础上,设计并实现了一种新型的注册表隐藏Rootkit检测方案.通过模拟win32系统底层枚举注册表键值的流程,获取真实有效的注册表键值,从而检测出隐藏的Root-kit.同时,在遍历注册表键值时使用了二叉搜索树算法以提高检测效率.试验表明该方法能准确并快速地检测出使用了注册表隐藏技术的Rootkit.

关键词：病毒入侵检测 Rootkit 注册表键索引 WinDbg

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基于ABM的公共政策仿真研究进展与方法论启示

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公共管理学报 2023年第2期20卷 116-127,173页

作者：王国成高德华中国社会科学院数量经济与技术经济研究所北京100732 山东工商学院管理科学与工程学院山东烟台264005

本文围绕基于主体的建模方法(Agent-Based Modeling,ABM)在公共政策研究中的应用,从跨学科视角探讨数智时代深化与变革公共政策研究的新使命。通过聚焦于ABM对于公共政策研究的方法(论)特色及优势,本文对应用ABM开展公共政策研究的一些... 详细信息

本文围绕基于主体的建模方法(Agent-Based Modeling,ABM)在公共政策研究中的应用,从跨学科视角探讨数智时代深化与变革公共政策研究的新使命。通过聚焦于ABM对于公共政策研究的方法(论)特色及优势,本文对应用ABM开展公共政策研究的一些代表性文献进行较为系统地梳理,力图勾勒这一领域的发展概貌和前沿动态;在此基础上,归纳总结应用ABM开展公共政策研究的时代机遇及所面临的困难和挑战,并且以公共政策研究的核心问题及其内在逻辑联系作为分析的起点,提出构建“计算+ABM”的新方法体系框架。本文的研究结果将有助于在一定程度上弥补当前公共政策抽象理论与鲜活现实之间的脱节现象,推动我国公共政策和公共管理决策的科学化、合理化、透明化进程,因此对于新时代背景下全方位提升社会公共治理能力、促进社会持续健康发展具有重要理论贡献和实践应用价值。

关键词：公共政策 ABM 异质性主体数智时代数字化治理

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