摘要:

In the chemical and petrochemical industries kinetic models are useful for describing the physical and chemical steps that occur in commercial processes. Often kinetic models involve several responses. Box and Draper (1965) have demonstrated that using multiresponse data for estimating the parameters in a model results in confidence regions for the parameters that are smaller than those obtained when the responses are considered individually, and they have developed a procedure for the multiresponse estimation of common parameters. Using multiresponse data also provides a better understanding of the reaction mechanism and makes possible a more comprehensive assessment of the correctness of the proposed model. Data from an oil shale pyrolysis experiment was used to fit and critique a sequence of models. These showed that conversion of the organic material in shale to oil was better explained when an intermediate product was included in the reaction network, and multiresponse techniques were employed. This led to a plausible kinetic representation of the pyrolysis process. Multiresponse models for more complex reaction mechanisms may require the estimation of a large number of parameters. An example is given, methods for minimizing computational difficulties in this situation are discussed, and some numerical results are presented.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486129

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Self-tuning control is a natural coupling of stochastic control theory with on-line parameter estimation techniques. This paper reviews much of the relevant theory of these controllers, presents a fairly thorough discussion of some of the practical considerations that are useful in implementing these, and applies it in various forms to the control of a highly exothermic packed bed, tubular reactor.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486130

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

In this paper, we give variables sampling plans for items whose failure times are distributed as either extreme-value variates or Weibull variates (the logarithms of which are from an extreme-value distribution). Tables applying to acceptance regions and operating characteristics for sample sizen, ranging from 3 to 18, are given. The tables allow for Type II censoring, with censoring numberrranging from 3 ton. In order to fix the maximum time on test, the sampling plan also allows for Type I censoring.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486131

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Brown and Fisher (1972) proposed a model for subsampling mixtures of sampled material and used it to analyze an elementary composite sampling procedure. Their results and the results of Rohde (1976) are extended to cover procedures with several finite composites, testing error and within-increment variability. Among the properties of composite sampling procedures derived are the following: (1) the composite sampling estimator of a lot mean (μx) is unbiased whether or not the subsampling procedure in unbiased, (2) there is a relative upper bound on the variance of the composite sampling estimator of μx, and (3) it is not necessary to form more than one composite to check for changes in basic parameters from lot to lot. The impact of these and other properties on the process of choosing a composite sampling procedure is discussed.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486132

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Moment estimatorsk* andb* for the shape parameter,k, and scale parameter,b, of the twoparameter form of the Weibull distribution,

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486133

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The Weibull and log linear rate models are frequently used in the statistical analysis of a Poisson series of events. By developing a general model for which the simpler rate models are special cases it becomes possible to use optimal conditional tests to assess the adequacy of the simpler models. A means is presented for generating the conditional distributions needed for the tests.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486134

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Given a type 2 censored sample from a left truncated exponential distribution, Bayesian prediction bounds are derived for future observations and the uncensored sample observations. Numerical examples are used to compare these bounds with those obtained using both classical and Bayesian approaches assuming the lifetimes follow a two-parameter exponential distribution.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486135

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

This paper derives the exact expressions for the first two moments of a generalized ridge estimator employing the initial choice of characterizing scalars as recommended by Hoer1 and Kermard (1970a). A numerical comparison of relative bias, relative mean squared error and efficiency with respect to the ordinary least squares estimator is also presented.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486136

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Multiple linear regression techniques that are resistant to changes in a small fraction of the data have been proposed and investigated in recent literature. This paper develops a regression procedure based onM-estimators that is adaptive in nature. That is, after a preliminary fit, an attempt is made to assess the nature of the distribution of the errors. Based on this assessment, an appropriateM-estimator is then chosen and the final multiple linear regression equation is computed. The rule's resistance to a few outlying data points is demonstrated with a classical data set on the stack loss of a plant converting ammonia to nitric acid. The adaptive procedure's excellent performance characteristics over a broad class of distributions is shown in a Monte Carlo study.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486137

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Robust estimation of the location parameter α based on selected order statistics is considered. The distribution function is only known to belong to a subset of a setDof distributions consisting of Tukey's lambda family of symmetric distributions with the inverse distribution function of the form α + β/γ) [λγ– (1 – λ)γ], 0 ≤ λ ≤ 1, and the normal, Cauchy and double exponential distributions. The scale parameter β can be unknown. In the setD, distributions with tail length varying from short to extremely long, when the shape parameter γ varies, are included. The asymptotically best linear estimate (ABLE) based onk(k= 2(1)5) optimally chosen symmetrical sample quantiles is considered. It can be used as a robust estimate and is shown to compete favorably with optimally trimmed and Winsorized means, in the sense of giving a higher guaranteed relative asymptotic efficiency (GRAE) for subsets ofD. Tables are provided so that the robustk-ABLE giving the highest GRAE for any subset ofDcan easily be obtained. An adaptive procedure of trying to identify the prototype by means of estimating the tail length is suggested.

ISSN:0040-1706    

DOI:10.1080/00401706.1980.10486138

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor