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| 1 | Mobius Isoparametric Hypersurfaces in S^(n+1) with Two Distinct Principal Curvatures | Hai Zhong LI Department of Mathematics, Tsinghua University. Beijing 100084. P. R. China Hui Li LIU Department of Mathematics, Northeastern University. Shenyang 110000. P. R. China Chang Ping WANG Key Laboratory of Pure and Applied Mathematics, School of Mathematical Sciences. Peking University, Beijing 100871, P. R. China Guo Song ZHAO Department of Mathematics, Sichuan University, Chengdu 610064. P. R. China | 2002 | Acta Mathematica Sinica,English Series2002，18，3： | 53 |
| 2 | 基于粗糙集理论-主成分分析的Elman神经网络短期风速预测显示文摘为了解决传统静态前馈神经网络(FNN)在短期风速预测中易陷入局部最优值及动态性能的不足,引入Elman动态神经网络建立风速预测模型,采用主成分分析法(PCA)对原始风速数据进行特征提取以优化神经网络的输入,改进激励函数和网络结构以寻求函数收敛速度和预测精度的最优解。针对Elman神经网络预测模型在风速波动的峰值处预测误差较大及预测精度存在波动性,提出采用粗糙值理论对模型预测值进行修正与补偿,进一步提高预测精度。实验证明:所提出的方法能有效提高预测精度,增强神经网络模型的泛化能力,具有较好的实用性。 | 尹东阳 盛义发 蒋明洁 李永胜 谢曲天 | 2014 | 电力系统保护与控制2014，42，11： | 31 |
| 3 | Completeness in the sense of Cauchy principal value of the eigenfunction systems of infinite dimensional Hamiltonian operator显示文摘The properties of eigenvalues and eigenfunctions of the infinite dimensional Hamiltonian operators are studied, and the suffcient conditions of the completeness in the sense of Cauchy principal value of the eigenfunction systems of the infinite dimensional Hamiltonian operators are given. In the end, concrete examples are constructed to justify the effectiveness of the criterion. | Alatancang WU DeYu | 2009 | Science China Mathematics2009，52，1： | 22 |
| 4 | 近红外光谱技术对闽南乌龙茶品种的识别研究显示文摘采用近红外光谱技术建立了一种快速无损的乌龙茶品种识别方法。收集闽南地区不同茶场中铁观音、黄金桂、本山、毛蟹与梅占等5个品种共210份具有代表性的乌龙茶样品,采集近红外光谱数据,选用1100~1300 nm ,1640~2498 nm作为检测波长范围,利用主成分分析法(principal component analysis , PCA)建立模型,并在实验过程中比较多元散射校正(multiplicative scatter correction ,MSC)与标准正态变量校正(standard normal variate ,SNV)两种数据预处理方法对模型的影响。实验结果表明,多元散射校正对模型的影响优于标准正态变量校正,对校正集的识别准确率达到了96%,对预测集中样品的识别准确率达到了90%。实验结果证明了采用近红外光谱技术可以快速无损识别闽南地区乌龙茶,具有较强的实用价值和推广价值。 | 程权 杨方 王丹红 林振宇 邱彬 | 2014 | 光谱学与光谱分析2014，34，3： | 21 |
| 5 | 主成分分析结合Fisher最优分割法在烟叶分切中的应用显示文摘为探索烟叶原料分段打叶复烤较科学、合理的烟叶分切方法,以红大C3F等级初烤烟叶为研究对象,采用黄金分割法将烟叶进行分切并采集各段近红外光谱,运用主成分分析提取各段近红外光谱主成分,结合Fisher最优分割法对烟叶分切方法进行了研究,并从内在化学成分和感官质量两方面与现有分切方法的分段效果进行了对比评价。结果表明:1采用黄金分割法能将红大C3F等级初烤烟叶分切成11段,通过对各段近红外光谱进行主成分分析,最终确定了两个主成分用于反映原料信息,其累积方差贡献率达99.789%。2以主成分综合得分为基础,结合Fisher最优分割法确定了红大C3F等级初烤烟叶在实际生产中的最佳分段比例为叶基∶叶中∶叶尖=33%∶29%∶38%。3采用Fisher最优分割法分切后烟叶总糖、还原糖和烟碱等指标含量在叶基、叶中、叶尖之间的差异达到显著或极显著水平,叶基(44.87)、叶中(47.70)、叶尖(49.06)感官质量得分差距较大,且叶尖和叶中的感官质量得分相比现有分切方法均有不同程度提升,这为烟叶分段后科学打叶复烤加工与合理利用提供了参考。 | 龙明海 资文华 华一崑 王跃昆 林楠 汪显国 | 2016 | 烟草科技2016，49，8： | 20 |
| 6 | Multivariate analysis in dam monitoring data with PCA显示文摘Given the limitation of traditional univariate analysis method in processing the multicollinearity of dam monitoring data,this paper reconstructs the multivariate response variables by introducing principal component analysis(PCA) method,explores the ways of determining principal components(PCs),and extracts a few PCs that have major influence on data variance.For steady observation series,a control field for the whole observation values has been established based upon PCA;for unsteady observation series that have significant tendency,a control field for the future observation values has been constructed according to PC statistical predication model.These methods have already been applied to an actual project and the results showed that data interpretation method with PCA can not only realize data reduction,lower data redundancy,and reduce noise and false alarm rate,but also be effective to data analysis,having a broad application prospect. | YU Hong1,2,WU ZhongRu1,2,BAO TengFei1,2 & ZHANG Lan1,2 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China 2 National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,Hohai University,Nanjing 210098,China | 2010 | Science China(Technological Sciences)2010，53，4： | 16 |
| 7 | Physiological mechanisms of resistance to cold stress associated with 10 elite apple rootstocks显示文摘A study was conducted in attempting to identify the cold-resistant apple rootstocks and to establish a comprehensive evaluation system. In this study, 10 elite apple dwarfing rootstocks(GM256, JM7, M26, M7, SC1, SH1, SH38, SH6, M9, and T337) were employed for the experiment and the following parameters were investigated under different low temperature stress conditions(0, –15, –20, –25, –30, and –35°C): the changes of the relative electrical conductivity(REC), anthocyanin content, protein content, soluble sugar content, soluble starch content, proline content, malondialdehyde(MDA) content, superoxide dismutase(SOD) activity, and peroxidase(POD) activity of the dormant branches. The inflection temperature that could represent the plant tissue semi-lethal temperature(LT_(50)) was obtained by the measurements of REC. The LT_(50) was used to evaluate eight other indices. The results showed that there was no significant correlation between LT_(50) and POD activity as well as between the soluble sugar, protein and proline contents at 0 and –15°C. Soluble starch content at 0 and –15°C and anthocyanin content at –15–(–30)°C were significantly but negatively correlated to the LT50 and the MDA content at 0–(–20)°C was significantly positively correlated to the LT_(50). Statistical analysis based on principal component analysis and LT50 showed that cold resistant apple rootstocks in the decreasing order from high to low as GM256, SH6, SH38, SH1, SC1, M26, M7, JM7, T337, and M9. | WANG Yan-xiu HU Ya CHEN Bai-hong ZHU Yan-fang Mohammed Mujitaba Dawuda Sofkova Svetla | 2018 | Journal of Integrative Agriculture2018，17，4： | 15 |
| 8 | 九种蔷薇科植物叶片的傅里叶红外光谱与亲缘关系分析显示文摘以蔷薇科三个亚科九种植物的叶为材料,利用傅里叶变换红外光谱法对九种植物进行亲缘关系分析和品种鉴定。叶中主要含有大量的碳水化合物、蛋白质、脂类、核酸等物质。糖类物质的峰主要在1440~775cm-1之间,1440~1337cm-1为纤维素、木质素的振动峰,1000~775cm-1为核糖的伸缩振动。蛋白质的峰主要在1620~1235cm-1之间,1620cm-1为蛋白质酰胺Ⅰ带的CO伸缩振动,1523cm-1为蛋白质酰胺Ⅱ带N-H和C-N吸收峰。脂类物质的峰主要出现在2930~1380cm-1之间,2922cm-1为脂肪CH2的伸缩振动,1732cm-1是脂肪酸CO的伸缩振动。核酸的标志峰出现在1250~1000cm-1,1068cm-1是磷酸基团的对称伸缩振动,1246cm-1是磷酸基团的不对称伸缩振动。研究结果表明:FTIR光谱数据经平滑、标准化处理、二阶求导、主成分分析和系统聚类建立的聚类分析模型与传统分类结果相一致。杏、樱桃聚为一类(李亚科),翻白叶、月季、草莓聚为第二类(蔷薇亚科),火棘、苹果、枇杷、海棠聚为第三类(苹果亚科),亚科聚类正确率为100%,但属聚类的正确率仅为55.56%。利用该聚类模型进行物种鉴定正确率为100%。该项研究为植物的亲缘关系分析提供了新的思路与方法。 | 邱璐 李晓勇 刘鹏 范树国 谢美华 刘仁明 周林宗 王静 | 2014 | 光谱学与光谱分析2014，34，2： | 15 |
| 9 | 基于PCA-LSSVM的机车走行部滚动轴承故障诊断研究显示文摘机车走行部的故障诊断是保障机车安全运行的重要手段之一。鉴于目前机车走行部滚动轴承故障诊断中存在的特征提取困难、故障诊断不准确等问题,提出一种基于最小二乘支持向量机(LSSVM)的故障诊断方法。通过主成分分析方法(PCA)对机车走行部滚动轴承的故障特征进行特征提取,将提取后的特征向量输入到故障诊断模型中,结合最小二乘支持向量机原理实现机车走行部滚动轴承的故障诊断。仿真结果表明,相比其他方法而言分类准确率达到了100%,模型构建时间为3.642 s,满足机车走行部滚动轴承的诊断要求。将最小二乘支持向量机引入并应用到机车走行部故障诊断领域中,为机车走行部故障诊断系统的研究与开发提供新思路和新方法。 | 钟小凤 贺德强 苗剑 | 2014 | 广西大学学报(自然科学版)2014，39，2： | 15 |
| 10 | Characterizing and estimating rice brown spot disease severity using stepwise regression,principal component regression and partial least-square regression显示文摘Detecting plant health conditions plays a key role in farm pest management and crop protection. In this study, measurement of hyperspectral leaf reflectance in rice crop (Oryzasativa L.) was conducted on groups of healthy and infected leaves by the fungus Bipolaris oryzae (Helminthosporium oryzae Breda. de Hann) through the wavelength range from 350 to 2 500 nm. The percentage of leaf surface lesions was estimated and defined as the disease severity. Statistical methods like multiple stepwise regression, principal component analysis and partial least-square regression were utilized to calculate and estimate the disease severity of rice brown spot at the leaf level. Our results revealed that multiple stepwise linear regressions could efficiently estimate disease severity with three wavebands in seven steps. The root mean square errors (RMSEs) for training (n=210) and testing (n=53) dataset were 6.5% and 5.8%, respectively. Principal component analysis showed that the first principal component could explain approximately 80% of the variance of the original hyperspectral reflectance. The regression model with the first two principal components predicted a disease severity with RMSEs of 16.3% and 13.9% for the training and testing dataset, respec-tively. Partial least-square regression with seven extracted factors could most effectively predict disease severity compared with other statistical methods with RMSEs of 4.1% and 2.0% for the training and testing dataset, respectively. Our research demon-strates that it is feasible to estimate the disease severity of rice brown spot using hyperspectral reflectance data at the leaf level. | LIU Zhan-yu1, HUANG Jing-feng1, SHI Jing-jing1, TAO Rong-xiang2, ZHOU Wan3, ZHANG Li-li3 (1Institute of Agriculture Remote Sensing and Information System Application, Zhejiang University, Hangzhou 310029, China) (2Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China) (3Plant Inspection Station of Hangzhou City, Hangzhou 310020, China) | 2007 | Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)2007，8，10： | 13 |
| 11 | Extracting mineral alteration information using WorldView-3 data显示文摘The multispectral commercial satellite-WorldView-3(WV-3) has the highest spatial, spectral and radiation resolutions among the satellites currently and can generate good data in the shortwave infrared(SWIR). The study area is located in the Pobei area of Xinjiang Uygur Autonomous Region, which is rich in mineral resources. The spectral analyses of some typical altered hydroxy-bearing, iron-bearing, and carbonate-bearing minerals could establish several Principal Component Analysis(PCA) models and mineral indices, using the visible and near infrared(VNIR) and the shortwave infrared(SWIR) subsystems of WV-3 data. In addition, the Spectral Angle Method and the spectrum index tool of ENVI software were used to extract the relevant alteration information. The WV-3 data is well suited for identifying hydroxy-bearing alteration with rich SWIR bands which distinguish Al-OH-bearing from MgOH-bearing alteration. Hence, this study provides a basis for the prediction of mineral resources in the Pobei area and sets the foundation for WV-3 data to be used as an important tool in extracting alteration information and prospecting practices. | Yaqin Sun Shufang Tian Baogang Di | 2017 | Geoscience Frontiers2017，8，5： | 13 |
| 12 | Integration of principal components analysis and cellular automata for spatial decisionmaking and urban simulation显示文摘This paper discusses the issues about the correlation of spatial variables during spatial decisionmaking using multicriteria evaluation (MCE) and cellular automata (CA). The correlation of spatial variables can cause the malfunction of MCE. In urban simulation, spatial factors often exhibit a high degree of correlation which is considered as an undesirable property for MCE. This study uses principal components analysis (PCA) to remove data redundancy among a large set of spatial variables and determine 'ideal points' for land development. PCA is integrated with cellular automata and geographical information systems (GIS) for the simulation of idealized urban forms for planning purposes. | 黎夏 叶嘉安 | 2002 | Science China Earth Sciences2002，45，6： | 12 |
| 13 | A new elliptic-parabolic yield surface model revised by an adaptive criterion for granular soils显示文摘An adaptive criterion for shear yielding as well as shear failure of soils is proposed in this paper to address the fact that most criteria,including the Mohr-Coulomb criterion,the Lade criterion and the Matsuoka-Nakai criterion,cannot agree well with the experimental results when the value of the intermediate principal stress parameter is too big.The new criterion can adjust an adaptive parameter based on the experimental results in order to make the theoretical calculations fit the test results more accurately.The original elliptic-parabolic yield surface model can capture both soil contraction and dilation behaviors.However,it normally over-predicts the soil strength due to its application of the Extended Mises criterion.A new elliptic-parabolic yield surface mode is presented in this paper,which introduces the adaptive criterion in three-dimensional principal stress space.The new model can well model the stress-strain behavior of soils under general stress conditions.Compared to the original model which can only simulate soil behavior under triaxial compression conditions,the new model can simulate soil behaviors under both triaxial compression conditions and general stress conditions. | LIU HanLong 1,2 ,XIAO Yang 1,2 ,LIU JinYuan 3 &LI GuoYing 4 1 Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University, Nanjing 210098,China 2 Geotechnical Research Institute,Hohai University,Nanjing 210098,China 3Department of Civil Engineering,Ryerson University,Toronto,Canada 4 Department of Geotechnical Engineering,Nanjing Hydraulic Research Institute,Nanjing 210014,China | 2010 | Science China(Technological Sciences)2010，53，8： | 12 |
| 14 | Strain and kinematic vorticity analysis of the Louzidian low-angle ductile shear detachment zone in Chifeng,Inner Mongolia,China显示文摘The Louzidian low-angle ductile shear detachment zone at the south of Chifeng is a SE-dipping, low-angle normal fault system. It is composed mainly of ductile shear zone, ductile-brittle shear zone and brittle fault zone. The ductile shear zone consists of, from bottom to top, mylonitic rocks, protomylonites and mylonites. Finite strain measurement of feldspar strain markers from those rocks using the Rf /φ method shows that strain intensities (Es) of the mylonite at core of the ductile shear zone (Es=0.65-0.96) are higher than those of the mylonitic rocks close to the granite intrusions (Es=0.59-0.62) and of the protomylonites at top of the ductile shear zone (Es= 0.47-0.70), and the strain types of the protomylonites and mylonties are elongate strain and plane-flattening strain, respectively. The kinematic vorticity values (Wk) estimated by the Polar Mohr diagram and the Rigid Grain Net range from 0.81 to 0.90 with an average of 0.85 for the protomylonites, and from 0.53 to 0.80 with 0.66 on average for the mylonites; Wk values of the extensional crenulation cleavage, i.e., C′, estimated by C′ method range from 0.63 to 0.37 with an average of 0.50. The angles between the maximum principal stress and shearing direction determined using the Maximum effective moment criterion evolved from 61° to 69° and to 75°, and finally normal to shearing direction. The results of strain and kinematic vorticity measurements suggest that high strain corresponds to low kinematic vorticity. Kinematic vorticity measurements show that the Louzidian low-angle ductile shear detachment zone is a result of a combination of simple-dominated general shearing at the early stage and pure-dominated general shearing at the late stage. All these, together with isotope geochronology and regional tectonic background, suggest that the Louzidian ductile shear detachment zone resulted from a combination of crust extension and magma intrusion. The model of simple shear at the early stage and pure shear at the late stage in the formation of metamorphic core complex has probably general significance. | LI JianBo WANG Tao OUYANG ZhiXia | 2010 | Science China Earth Sciences2010，53，11： | 12 |
| 15 | Accumulation and potential sources of heavy metals in soils of the Hetao area,Inner Mongolia,China显示文摘Soil contamination by heavy metals is a problem in agricultural irrigation systems.To assess the accumulation and sources of heavy metals in the Yongji irrigation district of the Hetao area,Inner Mongolia,China,195 soil samples from 39 sites(0–100 cm)were collected,and Zn,Cu,Pb,Cr,and Cd concentrations were analyzed.The mean concentrations were 107.17,32.48,12.31,53.53,and 0.22 mg kg-1,respectively,with no significant differences between soil depths(P>0.05).Concentrations of Zn,Cu,and Cd were higher than the background levels,with moderate accumulation;the contamination factor(CF)values were 1.9,1.7,and 1.9,respectively,and the geoaccumulation index(Igeo)was>0.Concentrations of Pb and Cr were lower than,or close to,the background levels(CF<1,Igeo<0),indicating that they originated from a natural source.The monomial potential ecological risk index(Eri)for Zn,Cu,Pb,and Cr was low;Eri for Cd was 55.73,implying a moderate risk.The grade of potential ecological risk index of the five heavy metals(RI)was low,declining from south to north.The studied soils were contaminated with Zn,Cu,and Cd;principal component(PC)analysis implicated the enrichment of Cd and partial Cu(high loading in PC 2)was related to agricultural activities;Zn and partial Cu,closely associated with PC 3,may have originated from irrigation water from the Yellow River.Future agricultural development should focus on fertilizer and pesticide application and the quality of irrigation water. | Yangchun ZHU Lijin WANG Xueyong ZHAO Jie LIAN Zhenhua ZHANG | 2020 | Pedosphere2020，30，2： | 12 |
| 16 | A Study on Retrieving Atmospheric Profiles from EOS/AIRS Observations显示文摘The paper presents the algorithms for retrieving atmospheric temperature and moisture profiles and surface skin temperature from the high-spectral-resolution Atmospheric Infrared Sounder (AIRS) with a statistical technique based on principal component analysis. The synthetic regression coefficients for the statistical retrieval are obtained by using a fast radiative transfer model with atmospheric characteristics taken from a dataset of global radiosondes of atmospheric temperature and moisture profiles. Retrievals are evaluated by comparison with radiosonde observations and European Center of Medium-Range Weather Forecasts (ECMWF) analyses. AIRS retrievals of temperature and moisture are in general agreement with the distributions from ECMWF analysis fields and radiosonde observations, but AIRS depicts more detailed structure due to its high spectral resolution (hence, high vertical spatial resolution). | 官莉 ALLEN Huang 李俊 | 2005 | Acta meteorologica Sinica2005，19，1： | 11 |
| 17 | 颗粒团聚对Al基SiC颗粒增强复合材料的流变形为影响(英文)显示文摘基于微观组织的有限元分析模型,研究颗粒团聚对Al基SiC颗粒增强金属基复合材料流变行为的影响。通过建立的3种增强颗粒分布的胞元模型(一个团聚现象、两个团聚现象和随机分布),分析讨论基体和增强颗粒中的等效应力和等效应变的分布规律,以此为基础,获得3种颗粒分布模型下的SiC颗粒增强Al基复合材料的应力应变曲线。结果表明:颗粒增强金属基复合材料的流变行为和力学响应与增强颗粒的分布非常敏感,但在弹性变形阶段这种影响就相对较弱。从增强颗粒的最大主应力分布来看,颗粒团聚增加了SiC颗粒开裂的概率。从基体的静水应力分布来看,颗粒团聚将促进早期的界面脱粘和在韧性基体中形成微空洞。 | 张鹏 李付国 | 2010 | 稀有金属材料与工程2010，39，9： | 10 |
| 18 | Three-dimensional FDEM numerical simulation of failure processes observed in Opalinus Clay laboratory samples显示文摘This study presents the first step of a research project that aims at using a three-dimensional(3D) hybrid finite-discrete element method(FDEM) to investigate the development of an excavation damaged zone(EDZ) around tunnels in a clay shale formation known as Opalinus Clay. The 3D FDEM was first calibrated against standard laboratory experiments, including Brazilian disc test and uniaxial compression test. The effect of increasing confining pressure on the mechanical response and fracture propagation of the rock was quantified under triaxial compression tests. Polyaxial(or true triaxial) simulations highlighted the effect of the intermediate principal stress(s2) on fracture directions in the model: as the intermediate principal stress increased, fractures tended to align in the direction parallel to the plane defined by the major and intermediate principal stresses. The peak strength was also shown to vary with changing σ2. | Omid Mahabadi Patrick Kaifosh Paul Marschall Tim Vietor | 2014 | Journal of Rock Mechanics and Geotechnical Engineering2014，6，6： | 10 |
| 19 | Ecological vulnerability analysis of Beidagang National Park,China显示文摘Ecological vulnerability analysis (EVA) is vital for ecological protection,restoration,and management of wetland-type national parks.In this study,we assessed the ecological vulnerability of Beidagang National Park based upon remote sensing (RS) and geographic information system (GIS) technologies.To quantify the ecological vulnerability,10 indices were collected by the 'exposuresensitivity- adaptive capacity' model and spatial principal component analysis (SPCA) was then applied to calculate the ecological vulnerability degree (EVD).Based on the numerical values,EVD of the study area was classified into five levels: moderate,light,medium,strong,and extreme.Results showed that the average EVD value was approximately 0.39,indicating overall good ecological vulnerability in Beidagang National Park.To be specific,80.42% of the whole area was assigned to a moderate level of EVD with the highest being the tourism developed areas and the lowest being the reservoirs and offshore areas.Ecological vulnerability of the region was determined to be affected by the natural environment and anthropogenic disturbance jointly.The primary factors included tourism disturbance,traffic interference,exotic species invasion,land use/land cover,and soil salinization.We expected to provide some insights of the sustainable development of Beidagang National Park and would like to extend the results to other wetland-type national parks in the future. | Xue YU Yue LI Min XI Fanlong KONG Mingyue PANG Zhengda YU | 2019 | Frontiers of Earth Science2019，13，2： | 10 |
| 20 | DYNAMIC VARIATIONS OF WATER QUALITY IN TAIHU LAKE AND MULTIVARIATE ANALYSIS OF ITS INFLUENTIAL FACTORS显示文摘Dynamic variation of water quality in Meiliang Bay and part of West Taihu Lake has been analysed based on data from 1991 to 1992. Principal Component Analysis is used to reveal the mutual relationships of various factors. It is shown that there existis an obvious spatial and temporal variation in the main factors of water quality. Annual values of TP, CON, TN, Chl-a and conductivity decrease evidently from inner Meiliang Bay to the outer from north to south. TP and TN fluctuate seasonally with much higher value in winter. This is particularly true for the mouth of Liangxi River. In addition, the Chl-1 has a synchronous variation with water temperature, although being lagged a little, and closely relates to TP and TN. Finally, the results from Principal Component Analysis show that TP, TN, SS (or SD), water temperature and Chl-a are the most influential factors to water qualuty in this area, and both suspensions and algae can contribute to transparency to Taihu Lake. | Cai Qiming Gao Xiyun Chen Yuwei Ma Shengwei Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008 People’s Republic of ChinaMartin Dokulil Institute of Limnology, Austria | 1997 | Journal of Geographical Sciences1997，7，3： | 9 |
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