摘要:

Analysis of leaf measurements of a reference collection of elm leaves suggests that the leaves, collected from trees which were selected by R. H. Richens as spanning the range of elm in Europe, fall into two primary groups. The first of these groups is made up of the representatives of the Wych elm (Ulmus glabra), which is known to be a distinct species. The second, larger, group is made up of an assemblage of subgroups that represent English elm (Ulmus procera),Ulmus minorand hybrids betweenUlmus minorandUlmus glabra. A minimum variance cluster analysis suggests that these subgroups are reasonably distinct, and discriminant analysis, logistic regression and a genetic algorithm are used to help identify the subgroups.

ISSN:0266-4763    

DOI:10.1080/02664769623946

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The autoregressive moving average process ARMA (p,q) observed with noise has another ARMA (p,k) representation, wherek= max (p,q). Parameters for the ARMA (p,k) representation satisfy some non-linear restrictions. We develop restricted Newton-Raphson estimators of the ARMA (p,k) process which takes advantage of the information given in the non-linear restrictions. The asymptotic relative efficiency of the estimators indicates that the proposed restricted Newton-Raphson estimator is more efficient than the unrestricted Newton-Raphson estimator. In a Monte Carlo experiment, the proposed estimator is shown to perform better than the unrestricted estimator of the ARMA (p,k) process.

ISSN:0266-4763    

DOI:10.1080/02664769623955

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In the original hybrid reliability acceptance sampling plan RASP developed by Epstein for the exponential lifetime distribution, the sample size n and the number of failures r to be observed are determined given the truncation time T . However, these plans cannot be used when test items are expensive and or limited in number. Therefore, one wishes to have a plan in which n is given. In this paper, we develop hybrid RASPs in which r and T are determined, given n. These plans are tabulated for various combinations of parameter values, so that one may easily determine an appropriate plan.

ISSN:0266-4763    

DOI:10.1080/02664769623964

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

For the past 20 years, forest modellers have largely used the Weibull distribution to summarize diameter distributions and to predict timber volume in a forest at clearfell time. The wider family of Burr distributions is investigated here as an alternative to the Weibull distribution. Using data from 20 permanent sample plots ofPinus radiata, we compare Burr and Weibull fits, showing that the Burr distribution enhances precision by roughly 13 . The effectiveness of the Burr distribution for prediction is found to be similar to that of the Weibull distribution.

ISSN:0266-4763    

DOI:10.1080/02664769623973

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper reviews a number of extreme value models which have been applied to corrosion problems. The techniques considered are used to model and predict the statistical behaviour of corrosion extremes, such as the largest pit, thinnest wall, maximum penetration or similar assessment of corrosion phenomenon. These techniques can be applied to measurements over a regular grid or to measurements of selected extremes, and can be adapted to accommodate all values over a selected threshold, or a selected number of the largest values-or only the single largest value. Data can come from one coupon or several coupons, and can be modelled to allow for dependence on environmental conditions, surface area examined, and duration of exposure or of experimentation. The techniquesare demonstrated on data from laboratory experiments and also on data collected in an industrial context.

ISSN:0266-4763    

DOI:10.1080/02664769623982

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper introduces a new concept of maximum allowable average outgoing quality MAAOQ , which is the average outgoing quality at the inflection point. The procedure for designing a single sampling plan indexed through the maximum allowable per cent defective and MAAOQ is stated. Tables are constructed for the selection of parameters for the plan, and parametric conversions are also studied.

ISSN:0266-4763    

DOI:10.1080/02664769623991

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Automatic identification of faces from a database given a digital view is becoming increasingly important. The question arises whether or not there can be a face identification system similar to the fingerprinting system, where a certain number of matches are regarded as sufficient to identify the person in the database. We first give a very general review of the topic of facial measurements and indicate some deep statistical problems. We then analyze a database of photographs. Certain characteristics of the population are provided, such as the modes of variation and correlation structures using shape analysis. The data involve angles as well as distances. The principal component analysis for angular data is discussed, its conversion into landmark data is established and the two approaches are compared. A new approach of anchor shape analysis for specialized distances is discussed.

ISSN:0266-4763    

DOI:10.1080/02664769624008

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0266-4763    

DOI:10.1080/02664769624017

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor