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

Most of the studies on mixture experiments assume that the experimental region is the whole simplex. However, experimentation at the vertices of the simplex is generally not meaningful. One may, therefore, restrict the experiment to a subset of the simplex. In this chapter, an ellipsoid within the simplex is used as the experimental region, and Kiefer optimal designs are determined for both linear and quadratic models due to Scheffe.

Optimal Mixture Designs for Estimation of Natural Parameters in Scheffé’s Model Under Constrained Factor Space

While in Chap. 7, we have discussed determination of optimum designs for the estimation of optimum mixture when the mixing proportions vary in the whole simplex, in the present chapter we address the problem when (i) one of the proportions is bounded above, (ii) there is a cost constraint. Here, again, the trace criterion is used to find the optimum design.

Optimal Designs for Estimation of Optimum Mixture in Scheffé’s Quadratic Model Under Constrained Factor Space

This chapter addresses the problem of finding optimum designs for the estimation of optimum mixture combination when the mean response is defined by (i) the additive quadratic mixture model due to Darroch and Waller (1985) and (ii) the quadratic log-contrast model due to Aichison and Bacon-Shoane (1984). Both the models have some advantage over Scheffe quadratic mixture model, in specific situations.

Optimal Designs for Estimation of Optimum Mixture Under Darroch–Waller and Log-Contrast Models

The paper considers inventory of commodities which show fluctuations in price over time. A sequential model with a finite number of periods of equal length has been considered and optimal policy for procurement in different periods is obtained assuming future prices and demands to be random variables with known or predictable density functions.

A Sequential Inventory Model for Items Subject to Random Price Fluctuations

We introduce standard mixture models and standard mixture designs as are well known in the literature (vide Cornell2002). Some of the less known models are also introduced briefly. Next we explain the frameworks of exact and approximate [or, continuous] mixture designs. We mention about known applications of mixture experiments in agriculture, food processing, and pharmaceutical studies. We also provide a chapter-wise brief summary of the contents covered in the monograph.

Manisha Pal

Papers

Optimal Mixture Designs for Estimation of Natural Parameters in Scheffé’s Model Under Constrained Factor Space

Optimal Designs for Estimation of Optimum Mixture in Scheffé’s Quadratic Model Under Constrained Factor Space

Optimal Designs for Estimation of Optimum Mixture Under Darroch–Waller and Log-Contrast Models

A Sequential Inventory Model for Items Subject to Random Price Fluctuations

Mixture Models and Mixture Designs: Scope of the Monograph