首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The results of unsupervised pattern recognition methods are critically dependent on the measure ofsimilarity used for clustering objects. There is little a priori information available on the relative utilityof various similarity measures. We introduce here an alternative similarity measure based on the metrictensor measure (MTM). Two standard clustering strategies are tested with the proposed similaritymeasure: hierarchical clustering and the K-median method. As data we use the ARCH obsidian data,a data set on Hungarian coal, and trace element data on Hungarian paprika. Differences from theMahalanobis distance measure are described for intraclass relations.  相似文献   

2.
Genetic algorithms have been created as an optimization strategy to be used especially when complexresponse surfaces do not allow the use of better-known methods (simplex, experimental designtechniques, etc.). This paper shows that these algorithms, conveniently modified, can also be a valuabletool in solving the feature selection problem. The subsets of variables selected by genetic algorithms aregenerally more efficient than those obtained by classical methods of feature selection, since they canproduce a better result by using a lower number of features.  相似文献   

3.
ealibrared.The diseussion in this PaPer foeuses on near一infrared(NIR)sPeetroseoPy as the examPle instrument.However,the Proeedures Presented are aPPlieable tomost methods of instrumental analysis.Essentially,ealibration eonsists of assembling a seriesof samPles eontaining the analyte or analytes at  相似文献   

4.
吉林省河流水质分析与评价   总被引:6,自引:0,他引:6  
王俊  姜建祥 《地理科学》1994,14(2):165-171
  相似文献   

5.
与传统的离子色谱相比较,讨论了目前分析化学的前沿技术毛细管离子分析技术,它具有分析快速、高效、分离度好、样品预处理简单、用样量少、维护方便、自动化程度高等特点,完全可替代目前在分析极地冰雪中所通用的离子色谱仪,成为极地冰雪化学分析强有力的新的分析工具  相似文献   

6.
Fisher variance ratio tests are developed for determining(1)the number of statistically significantabstract factors responsible for a data matrix and(2)the significance of target vectors projected into theabstract factor space.F-tests,developed from the viewpoint of vector distributions,are applied tovarious data sets taken from the chemical literature.  相似文献   

7.
8.
This paper utilizes variable step size generalized simulated annealing(VSGSA)to design multicomponentcalibration samples for spectroscopic data.VSGSA is an optimization procedure which is capable ofconverging to exact positions of global optima located on multidimensional continuous functions.On thebasis of analysis sample response vectors,optimally designed calibration concentration matrices areobtained assuming knowledge of components present.The complexity of response surfaces establishedby the optimization criteria is described.  相似文献   

9.
Cross-validatory estimation of the bilinear model based on principal components is reviewed andKrzanowski's modification of Wold's procedure is described. Two different types of residuals useful forchecking model adequacy are defined and indices measuring the influence of each observed unit on theestimates of the parameters are discussed. A method for the selection of variables derived from Procrustesanalysis is described. Results arising from the study of two sets of enological data are given.  相似文献   

10.
福建省冬季农业气候资源及其聚类分析   总被引:2,自引:0,他引:2  
分析了福建省科季农业开发的重要意义,并根据福建省冬季气候资源的特点,利用一定的指标对福建省的冬季气候进行了聚类分析,得出全省冬季气候的地域分布特点以及动态变化,为冬季农业开发模式的选择和合理布局提供理论基础。  相似文献   

11.
针对云南腾冲机场、泸沽湖机场周边增设的6个自动气象站,从地理环境、选址规范性、水汽输送路径、流场特征、网络通讯条件几个方面对自动站选址的合理性及科学性进行分析评价,并用天气形势个例分析了天气气候条件,分析表明,6个自动气象站的选址能够较好的反映当地地理环境特征,充分考虑水汽输送方向和主要天气系统的路径,可以较好的反映降水的垂直变化,对分析研究机场雾的生消规律也提供了针对性资料。  相似文献   

12.
Analysis of multivariate response data by modelling the principal components of the response has beenapplied to two sets of data. In both cases principal components analysis revealed the relationships amongthe response variables and exploited them to simplify the problem of modelling and optimizing themultivariate response. The models and optima obtained from the principal components comparedfavourably with the individual models and simultaneous optima.  相似文献   

13.
Basic contemporary portfolio models are applied to an interregional economic analysis of U.S. Census Regions during 1963-1978. The models are well suited the type of analysis that partitions a region's economic cycle into national and local components. Portfolio theory provides a logic for interregional cross investment; results of an empirical test indicate portfolio theory may be superior to simple neoclassical theory in explaining spatial patterns of capital investment.  相似文献   

14.
SPLITTING OF CALIBRATION DATA BY CLUSTER ANALYSIS   总被引:1,自引:0,他引:1  
from eorresponding valuesof x.The most eommon aPProaeh to this Problem 15 linear regression(or ealibration),but1 inear methods are usually best suited for quite limited regions alld are not generallyaPPlieable.If a linear fit 15 not satisfactory,alternative aPProaehes are non一linear regression,non一Parametrie regression,transformations and sPlitting of the data into subgrouPs  相似文献   

15.
以北京顺义区32通道成像光谱数据为例,从数据的统计参数入手,分别从数据的方差、动态范围、相关性、直方图等方面分析研究噪声及特点,在此基础上提高局部邻域自动噪声查找与消除算法。  相似文献   

16.
对于目前普遍存在的流域水资源冲突问题,将谈判支持系统引入到流域水资源谈判中来,建立一种面向解决流域水资源冲突的网上谈判支持系统;运用软件工程的方法和理论对该系统进行了系统分析与框架设计。流域水资源冲突网上谈判支持系统是一种利用先进的计算机和信息技术,辅助谈判中的一方或各方公正合理地解决争议的计算机辅助决策支持系统,其为缓解和解决存在的或是潜在的水资源冲突提供了一种新的思路和方法。并且丰富了流域水资源集成管理的理论与应用手段。  相似文献   

17.
18.
Cluster analysis has been applied to characterize the group structures of four sets of Catalan white wines(Conca de Barberà),Camp de Tarragona,Terra Alta and Ribera-Falset)on the basis of eleven classicaloenological parameters and seven micro and trace metallic constituents considered to be relativelyinsensitive to cultural practices.In spite of the vintage variation and the lack of a clear varietaldifferentiation among the wines,each region could be individually characterized.The application ofsupervised pattern recognition methods has allowed regional assignment of unknown samples with aprediction rate higher than 95%.Several metal ions(such as calcium,strontium, zinc and magnesium)and a few classical parameters(such as ethanol content and the sum of malic and lactic acid contents)have been found to be relevant for a correct classification.ALLOC and KNN classification methodscombined with LDA have been proven useful with the present data set,although their performance wasnot superior to that of LDA and SIMCA.  相似文献   

19.
A program for the potentiometric determination of the protonation constants of mononuclear polyproticsubstances is described.A maximum of twelve parameters can be determined simultaneously,includingup to six protonation constants,four electrode calibration parameters,the protolysis constant of thesolvent and the titrant concentration.Optimization is carried out by using the non-simplifiedNewton-Raphson method,which is potentiated by the Marquardt algorithm and a distance speeding-upcoefficient.A direct search method is also used to improve the initial set of values.Variances arecalculated very accurately,since the real Hessian function is used.Statistical weights and ionic strengthcorrections are also considered,The program has been tested by using simulated titration curves ofpolyprotic acids with close constants.  相似文献   

20.
台湾西南部泥岩土地利用型态与环境劣化趋势之分析   总被引:5,自引:2,他引:5  
台湾泥岩恶地因其特殊之土壤理化性质及区域微气候的相互恶性循环,衍生生态环境等问题。在以往之35年,裸化面积从1967年的2532hm^2,至2001年11月已扩大为15539hm^2。其表土大量流失、崩塌、河川含砂量激增、植被退化与微气候变异等破坏,更显示泥岩之环境劣化问题。以SPOT卫星影像判识泥岩裸露面积,探讨不同时期之地景变异,并应用地景生态理论量化泥岩地表不同土地利用之空间结构变化,分析地景结构变迁之生态内涵与生态指标意义。因子分析结果其主要变异为多样性因子与形状破碎型因子所影响,而应用马可夫链模式计算出不同时期之土地利用变迁内涵,此结果搭配指标分析可解释泥岩裸露面积与竹林面积皆持续扩大,乃由人为土地利用之活动及植被变迁所引起。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号