Recent trends in modeling of deteriorating inventory

4. Modelling Survival Data in Medical Research

This paper presents a complete and up-to-date survey of published inventory literature for the deteriorating (decaying) inventory models. More specifically, those papers are addressed that consider the effect of deterioration as a function of the on-hand level of inventory. The basic features, extensions and generalization of various models are discussed. A classification scheme is presented along with suggestions for future research.

https://link.springer.com/content/pdf/10.1057%2Fjors.1991.4.pdf

Survey of Literature on Continuously Deteriorating Inventory Models

Infertility and problems of impaired fecundity have been a concern through ages and is also a significant clinical problem today, which affects 8-12% of couples worldwide. Of all infertility cases, approximately 40-50% is due to "male factor" infertility and as many as 2% of all men will exhibit suboptimal sperm parameters. It may be one or a combination of low sperm concentration, poor sperm motility, or abnormal morphology. The rates of infertility in less industrialized nations are markedly higher and infectious diseases are responsible for a greater proportion of infertility. The present literature will help in knowing the trends of male factor infertility in developing nations like India and to find out in future, various factors that may be responsible for male infertility.

Trends of male factor infertility, an important cause of infertility: A review of literature.

Approximately 10 to 15% of couples are impacted by infertility. Recently, the pivotal role that lifestyle factors play in the development of infertility has generated a considerable amount of interest. Lifestyle factors are the modifiable habits and ways of life that can greatly influence overall health and well-being, including fertility. Many lifestyle factors such as the age at which to start a family, nutrition, weight, exercise, psychological stress, environmental and occupational exposures, and others can have substantial effects on fertility; lifestyle factors such as cigarette smoking, illicit drug use, and alcohol and caffeine consumption can negatively influence fertility while others such as preventative care may be beneficial. The present literature review encompasses multiple lifestyle factors and places infertility in context for the couple by focusing on both males and females; it aims to identify the roles that lifestyle factors play in determining reproductive status. The growing interest and amount of research in this field have made it evident that lifestyle factors have a significant impact on fertility.

/pdf/lifestyle-factors-and-reproductive-health-taking-control-of-ob45s39pgz.pdf

Lifestyle factors and reproductive health: taking control of your fertility

Optimal designs for estimating the optimum mixing proportions in a quadratic mixture model was first investigated by Pal and Mandal (2006). In this article, similar investigation is carried out when mean response in a mixture experiment is described by a quadratic log contrast model. It is found that in a symmetric subspace of the finite dimensional simplex, there exists a D-optimal design that puts weights at the centroid of the sub-space and the vertices of the experimental domain. The optimality is checked by numerical computation using Equivalence Theorem.

D-Optimum Designs for Optimum Mixture in a Quadratic Log Contrast Model

Optimal designs for estimating the parameters and also the optimum factor combinations in multi-response experiments have been considered by some authors However, the existing literature on mixture experiments shows studies mainly in the single response case In this paper an attempt has been made to investigate optimum designs for estimating optimum mixing proportions and also the optimum amount of mixture in a multi-response experiment The pseudo-Bayesian approach has been used, and the support points of the optimum design are found to be the union of the support points of a weighted centroid design and a three-point symmetric design, with support points at the two extremes and one at the centre

Optimal Designs for Estimation of Optimum Mixtures and Optimum Amount in a Multiresponse Mixture Experiment

In this paper we construct some skewed distributions with pdfs of the form 2f(u)G(¸u), where ¸ is a real number, f(¢) is taken to be a Laplace pdf while the cdf G(¢) comes from one of Laplace, double Weibull, reflected Pareto, reflected beta prime, or reflected generalized uniform distribution. Properties of the resulting distributions are studied. In particular, expressions for the moments of these distributions and the characteristic functions are derived. However, as some of these quantities could not be evaluated in closed forms, special functions have been used to express them. Graphical illustrations of the pdfs of the skewed distributions are also given. Further, skewness-kurtosis graphs for these distributions have been drawn.

/pdf/skewed-reflected-distributions-generated-by-the-laplace-5029w31t98.pdf

Skewed Reflected Distributions Generated by the Laplace Kernel

Based on standard probability distributions, new families of univariate distributions have been introduced and their properties studied by many authors. The present paper investigates some general properties of a family of Gamma generated distributions proposed by Zografos and Balakrishnan (2009).

/pdf/some-properties-of-gamma-generated-distributions-27obe49b6v.pdf

Some Properties of Gamma Generated Distributions

In many experimentations with mixtures, the classical mixture models are found to be inappropriate to describe the response. In pharmaceutical research, for example, the components of the mixture are often classified into groups and the proportions of different groups in the mixture are fixed. This results in relational constraints on the mixing components. In the paper, we study a mixture model appropriate in such a situation. We attempt to find optimum designs for estimation of parameters in the model, and also for estimation of the optimum proportions of components in a group. The support points of the optimum designs are found to belong to the union of barycentres of the domains of the groups involved.

Manisha Pal

Papers

D-Optimum Designs for Optimum Mixture in a Quadratic Log Contrast Model

Optimal Designs for Estimation of Optimum Mixtures and Optimum Amount in a Multiresponse Mixture Experiment

Skewed Reflected Distributions Generated by the Laplace Kernel

Some Properties of Gamma Generated Distributions

Optimum designs for mixtures with relational constraints on the components