摘要:

Image warping is a transformation which maps all positions in one image plane to positions in a second plane. It arises in many image analysis problems, whether in order to remove optical distortions introduced by a camera or a particular viewing perspective, to register an image with a map or template, or to align two or more images. The choice of warp is a compromise between a smooth distortion and one which achieves a good match. Smoothness can be ensured by assuming a parametric form for the warp or by constraining it using differential equations. Matching can be specified by points to be brought into alignment, by local measures of correlation between images, or by the coincidence of edges. Parametric and non-parametric approaches to warping, and matching criteria, are reviewed.

ISSN:0266-4763    

DOI:10.1080/02664769823151

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, we study the distribution tables of imperfectly shuffled hands in a bridge game under a conditional Markov chain model, based on which a simple approximate test on the randomness of the decks is derived. The idea is to examine whether a stochastic process is a compound hypergeometric process, through the number of its ties, and it is easily adapted to similar situations.

ISSN:0266-4763    

DOI:10.1080/02664769823160

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A two-sample version of the non-parametric index of tracking for longitudinal data introduced by Foulkes and Davis is described. The index is based on a multivariate U -statistic, and provides a measure of the stochastic ordering of the underlying growth curves of the samples. The utility of the U -statistic approach is explored with two applications related to growth curves and repeated measures analyses.

ISSN:0266-4763    

DOI:10.1080/02664769823179

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A novel proposal for combining forecast distributions is to use quantile regression to combine quantile estimates. We consider the usefulness of the resultant linear combining weights. If the quantile estimates are unbiased, then there is strong intuitive appeal for omitting the constant and constraining the weights to sum to unity in the quantile regression. However, we show that suppressing the constant renders one of the main attractive features of quantile regression invalid. We establish necessary and sufficient conditions for unbiasedness of a quantile estimate, and show that a combination with zero constant and weights that sum to unity is not necessarily unbiased.

ISSN:0266-4763    

DOI:10.1080/02664769823188

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper presents three methods for estimating Weibull distribution parameters for the case of irregular interval group failure data with unknown failure times. The methods are based on the concepts of the piecewise linear distribution function (PLDF), an average interval failure rate (AIFR) and sequential updating of the distribution function (SUDF), and use an analytical approach similar to that of Ackoff and Sasieni for regular interval group data. Results from a large number of simulated case problems generated with specified values of Weibull distribution parameters have been presented, which clearly indicate that the SUDF method produces near-perfect parameter estimates for all types of failure pattern. The performances of the PLDF and AIFR methods have been evaluated by goodness-of-fit testing and statistical confidence limits on the shape parameter. It has been found that, while the PLDF method produces acceptable parameter estimates, the AIFR method may fail for low and high shape parameter values that represent the cases of random and wear-out types of failure. A real-life application of the proposed methods is also presented, by analyzing failures of hydrogen make-up compressor valves in a petroleum refinery.

ISSN:0266-4763    

DOI:10.1080/02664769823197

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A number of models have been examined for modelling probability based on rankings. Most prominent among these are the gamma and normal probability models. The accuracy of these models in predicting the outcomes of horse races is investigated in this paper. The parameters of these models are estimated by the maximum likelihood method, using the information on win pool fractions. These models are used to estimate the probabilities that race entrants finish second or third in a race. These probabilities are then compared with the corresponding objective probabilities estimated from actual race outcomes. The data are obtained from over 15 000 races. it is found that all the models tend to overestimate the probability of a horse finishing second or third when the horse has a high probability of such a result, but underestimate the probability of a horse finishing second or third when this probability is low.

ISSN:0266-4763    

DOI:10.1080/02664769823205

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Fisher has presented various applications of the repeated integral of the normal distribution function. A new application has appeared in shape distributions. This work has led to the search for an explicit expression for the repeated normal integral function in place of an infinite series expansion for this function first given by Fisher. We provide an explicit expression for this function with a finite number of terms.

ISSN:0266-4763    

DOI:10.1080/02664769823214

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We consider the use of standard univariate and multivariate methods for profile analysis of randomized complete block experiments. Although the analysis for the case where the block time interaction is included in the model parallels that used for factorial experiments, situations where such interaction is not present may not be handled in the same way. We identify hypotheses for which the standard analysis may be applied, as well as those for which some adaptation is required. We also indicate how to implement such analyses via existing computer software.

ISSN:0266-4763    

DOI:10.1080/02664769823223

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

T = \[x + … + x ]/ Sigma x (T*= \[x + … + x ] Sigma x ) is the max k (n- k+ 1 ) (n) i k ( 1 ) (k) i imum likelihood ratio test statistic for k upper ( lower ) outliers in an exponential sample x , …, x . The null distributions of T for k= 1,2 were given by Fisher and by Kimber 1 n k and Stevens , while those of T*(k= 1,2) were given by Lewis and Fieller . In this paper , k the simple null distributions of T and T* are found for all possible values of k, and k k percentage points are tabulated for k= 1, 2, …, 8. In addition , we find a way of determining k, which can reduce the masking or ' swamping ' effects .

ISSN:0266-4763    

DOI:10.1080/02664769823232

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The discordancy test for multiple outliers is complicated by problems of masking and swamping. The key to the settlement of the question lies in the determination of k , i.e. the number of 'contaminants' in a sample. Great efforts have been made to solve this problem in recent years, but no effective method has been developed. In this paper, we present two ways of determining k , free from the effects of masking and swamping, when testing upper (lower) outliers in normal samples. Examples are given to illustrate the methods.

ISSN:0266-4763    

DOI:10.1080/02664769823241

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor