共查询到20条相似文献，搜索用时 109 毫秒
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模糊聚类分析是模糊数学的一个分支。它的主要功能是进行多指标的综合分类。由于它能分析自然界中的模糊现象,给人以清晰的答案,因而越来越受到人们的重视。目前已在很多领域中得到了应用,成为人们处理模糊问题的有力工具。水土流失分类是以防治为目的,由于影响水土流失的因素很多,单独采用侵蚀模数作为分级指标,虽然能看出水土流失的强弱,但不能反映造成各类侵蚀的主导因子是什么,所以满足不了制定水土保持规划的要求。要在分类中正确的反映众多的侵蚀因子信息,就需要采用数学方法,应用计算机进行多指标的综合分类。数学分类方法较多,模糊聚类分析是其中较好的方法之一。本文试图介绍模糊聚类分析的基本思想和运用步骤,并以水土流失分类为例来说明模糊聚类分析在水土流失分类中的应用。 相似文献
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对我国农村环境监测、环境质量评价现状作了简要的分析,探讨了农村环境质量指数的计算及综合评价方法,提出了农村环境质量监测布点及监测指标选择的优化原则。同时,选择生态型农村——湖南省郴州市宜章县上寮村作为典型案例进行研究,对其进行环境质量基础调查与监测,根据对上寮村的环境质量监测结果、指数的计算、综合评价方法及目前农村村庄分类情况,得出上寮村环境质量好、适合居住,与将其划为生态型农村相符。农村环境质量监测布点及监测指标选择的优化原则与指数的计算及综合评价方法的提出,对加强农村环境管理、保护和改善农村环境质量具有十分重要的意义。 相似文献
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GIS支持下豫东地区土壤野外采样布点方法探索 总被引：5，自引：0，他引：5
以河南省通许县潮土区中低产田为例,介绍了一种GIS支持下的土壤野外采样布点方法,并对所取得的结果进行了讨论。根据要求覆盖研究区中低产田潮土的面积、涵盖所有土种类型、表层采样与剖面采样相结合、网格点与类型控制点相结合等原则,确定采用2 km×2 km网格布点方法。室内初步布点157个,涵盖了研究区16种土种类型,其中普通网格点141个,类型网格采样点6个,类型参考采样点10个。将布点图层与土壤图进行叠加分析,建立了空间数据库,完善布点属性表,作为野外精确采样的依据。实际采集普通网格点135个,剖面点15个。将室内布点与实际采样点位信息在数据库中分层管理,方便查询与更新。特别在剖面采样过程中发现实际采样与第二次土壤普查土种图比较,存在某些差异,应该根据实际采样诊断土壤类型并在GIS界面修正原始土壤分布图,将此改动作为建议提出,以便完善当地的土壤图。 相似文献
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系统聚类分类法在水土保持林林种分类中的应用 总被引：3，自引：0，他引：3
海东霞 《水土保持应用技术》2000,(3):43-44
将水保林种进行合理分类,可为各林种的合理营造、经营方向或科学配置提供理论依据。利用系统聚类分类方法对辽宁阜新县阿其玛嘎小流域的水保林进行了林种分类;采用评价指标为坡向、坡度、坡位、土壤侵蚀状况、林分蓄积量、密度、郁闭度、生物量等８个可量化指标,对１０４．４７ ｈｍ２林地进行聚类分析。经专家综合分析评判,该流域林地分为用材林、护坡林、薪炭林、经济林、沟道速生丰产林、分水岭防护林等６个林种。此分类为指导今后水保林配置提供了依据。 相似文献
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In the research, in this paper, we investigate spatial and temporal variations in the composition of wastewater near Croatian highways in three climatic regions (continental, Mediterranean, highland) during three seasons (autumn, winter and spring). In our paper, the spatial division of the investigated areas that pertain to the three aforementioned climatic regions was obtained using the method of hierarchical clustering of monitored locations. One thousand five hundred thirty-three samples from 14 locations along Croatian highways were collected and analysed by methods of multivariate exploratory analysis. By methods of principal components, factor analysis and hierarchical clustering of variables, we grouped the variables into factors. Whereas 60 % of variation in the data was explained by three principal components, six principal components accounted for 88 % of data variation. The key section of our research was conducted by the decision tree method. For the purpose of analysis, we classified 1,533 samples into three classes representing climatic regions separately for each season and obtained the accuracy of 76–90 % on test samples. Finally, using decision trees, we identified the most important variables that differentiate climatic regions by the level of contamination of water along highways in different seasons. 相似文献
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Kim N Kim K Choi BY Lee D Shin YS Bang KH Cha SW Lee JW Choi HK Jang DS Lee D 《Journal of agricultural and food chemistry》2011,59(19):10435-10441
An ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-Tof MS)-based metabolomic technique was applied for metabolite profiling of 60 Panax ginseng samples aged from 1 to 6 years. Multivariate statistical methods such as principal component analysis and hierarchical clustering analysis were used to compare the derived patterns among the samples. The data set was subsequently applied to various metabolite selection methods for sophisticated classification with the optimal number of metabolites. The results showed variations in accuracy among the classification methods for the samples of different ages, especially for those aged 4, 5, and 6 years. This proposed analytical method coupled with multivariate analysis is fast, accurate, and reliable for discriminating the cultivation ages of P. ginseng samples and is a potential tool to standardize quality control in the P. ginseng industry. 相似文献
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Data for 85 soil profiles, located at random within 17 physiographic units in a 1,000 km2 area near Oxford, and each characterized by 37 properties, were analysed by two sets of multivariate techniques. Principal component analysis yielded two components accounting for 44 per cent of the total variation, and the distribution of the profiles along these components is plotted as a scatter diagram (ordination). Similarity analysis and hierarchical grouping (classification) were performed using three different similarity indices, two different standardization techniques, and three different sorting strategies. Before analysis the profiles were classified by two pedologists, independently using their judgement. For the Brown Earths there was moderately good agreement between the results of the two prior classifications and between them and those produced by the several numerical procedures. The degree of clustering was slight and much less than imagined prior to analysis. For the Gleys there was no evident clustering. Different numerical procedures gave different results, as also did the two prior classifications. Pedologists faced with difficult classificatory decisions cannot look to any hierarchical clustering strategy as arbiter, though they should get guidance from a principal component plot. 相似文献
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定量化方法在生态分区过程中的应用及案例研究 总被引：2，自引：0，他引：2
该文在总结国内外有关生态分区研究的基础上,针对目前研究中存在的主观性强、专家选取对分区结果影响大的问题,在生态分区过程的两个关键点引入定量方法。应用主成分分析方法,确定各指标权重,筛选生态分区划分指标,确定各级生态分区的指标。应用系统聚类方法,确定各生态分区的最终边界。以辽河流域为例,选取降雨量、地势地貌、植被类型以及土壤类型等指标,应用定量化方法进行生态分区的划分,共划分一级生态分区3个,二级生态分区9个。该文旨在为生态分区的划分提供更为客观、科学的方法,从而为环境与资源的研究、评估、监测和管理提供适宜的空间分析框架,为生态管理和相关政策的制定与实施提供科学、合理的依据。 相似文献
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聚类分析在测土配方施肥中的应用 总被引：2，自引：0，他引：2
对浙江省慈溪市2007 ～ 2009年2 043个耕地土样的有机质、全氮、碱解氮、有效磷和速效钾含量进行了聚类分析,将慈溪市耕地养分划成5个类型区,根据各类型区特点,提出了相应的作物配方施肥建议. 相似文献
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农户类型与农业景观变化类型间相互作用研究--以陕西省米脂县高西沟村为例 总被引：1，自引：0，他引：1
通过半访谈式的实际调研获取数据,利用多元对应分析和系统聚类方法,从农户的社会经济条件、拥有土地状况等方面,探讨了其与不同类型农业景观变化类型间的相互作用.研究表明,(1)农户类型与农业景观格局间变化存在较为密切的关系,不同农户类型对于景观变化的类型作用不同;(2)多元对应分析方法有利于揭示农户与农业景观格局间的相互作用,为探索宏观景观格局的优化奠定基础;(3)确定导致高西沟景观变化的主要农户类型,为规范农户土地利用行为提供理论基础. 相似文献
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滇青、青饼和普洱茶（熟饼）近红外指纹图谱分析 总被引：9，自引：0，他引：9
为深入了解滇青（晒青毛茶）、青饼和普洱茶（熟饼）在化学组成方面的异同,为茶类的区分与界别提供进一步的科学依据,对滇青、青饼和普洱茶（熟饼）的近红外化学指纹图谱采用欧氏距离、主成分分析和系统聚类等方法进行了定性判别分析。结果发现,普洱茶（熟饼）近红外指纹图谱与滇青、青饼图谱间的欧氏距离均大于各自组内最大偏差的绝对阈值,而滇青和青饼的组间差异小于各自的组内阈值;在第一主成分和第二主成分得分值散点图上,熟饼样品与青饼和滇青样品间界限分明,而滇青和青饼样品间无明显界限;所有的熟饼样品在系统聚类分析中聚为一类,而青饼与滇青样品聚为一类。因此,青饼的近红外光谱在各方面都与普洱茶（熟饼）样品差异显著,而与其原料滇青（晒青毛茶）十分接近。从化学本质上来说,青饼更接近于绿茶类产品。 相似文献
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Olive oil fluorescence is related to oil composition. Here it is shown that the natural clustering of different types of commercial Spanish olive oils depends on their fluorescence excitation-emission matrices (EEMs). Fifty-six commercial samples of olive oil (29 virgin olive oils, 20 pure olive oils, and 7 olive-pomace oils) were used. The clustering method was hierarchical agglomerative clustering using the Euclidean distance as a similarity measure and the average linkage. Two spectral ranges were considered (which either contained the fluorescence peak of the chlorophylls or did not), and various methods for preprocessing the fluorescence spectra were compared. The oils were clearly distinguished using the unfolded EEMs measured between lambda(ex) = 300-400 nm and lambda(em) = 400-600 nm. The optimal preprocessing was normalization of the unfolded spectra followed by column autoscaling. Also shown are the advantages of using second-order data (EEMs) instead of first-order data (a single fluorescence spectrum) for each sample. 相似文献
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D Cuthbertson PK Andrews JP Reganold NM Davies BM Lange 《Journal of agricultural and food chemistry》2012,60(35):8552-8560
A gas chromatography-mass spectrometry approach was employed to evaluate the use of metabolite patterns to differentiate fruit from six commercially grown apple cultivars harvested in 2008. Principal component analysis (PCA) of apple fruit peel and flesh data indicated that individual cultivar replicates clustered together and were separated from all other cultivar samples. An independent metabolomics investigation with fruit harvested in 2003 confirmed the separate clustering of fruit from different cultivars. Further evidence for cultivar separation was obtained using a hierarchical clustering analysis. An evaluation of PCA component loadings revealed specific metabolite classes that contributed the most to each principal component, whereas a correlation analysis demonstrated that specific metabolites correlate directly with quality traits such as antioxidant activity, total phenolics, and total anthocyanins, which are important parameters in the selection of breeding germplasm. These data sets lay the foundation for elucidating the metabolic basis of commercially important fruit quality traits. 相似文献
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Fourteen commercial soft drinks have been analyzed using colorimetric sensor arrays made from a set of 25 chemically responsive dyes printed on a hydrophobic membrane. Digital imaging of the dye array before and after immersion provides a color change profile as a unique fingerprint for each specific analyte. The digital data library generated was analyzed with statistical and chemometric methods, including principal component analysis (PCA) and hierarchical clustering analysis (HCA). Facile identification of all of the soft drinks was readily achieved using comparison of the color change profiles or a PCA score plot. Using a HCA dendrogram, the misclassification rate was <2%, and even very similar sodas were easily differentiated. In addition, the monitoring of soft drinks as they degas or upon dilution also proved to be possible. This work demonstrates the potential of our colorimetric sensor array technology for quality assurance/control applications of sodas and perhaps other beverages as well. 相似文献