Determination of Optimal Size of Casual Workers in a Production Company Using Stochastic Model

Many big production companies engage casual workers to work with their regular employees in order to meet their daily labour needs.  The researchers are quite aware that the Nigeria Labour Congress frowns at casualisation of workers which is seen as under-employment and cheating on the part of the people concerned.  Since unemployment and underemployment are parts of the problems confronting Nigeria, there is the need for the issue of workers casualisation to be addressed before the nation can be transformed. This paper therefore attempts to determine the daily optimal number of casual workers that could be engaged by a production company with specific reference to Dangote Cement PLC, Ibese. This is necessary in achieving the national transformation agenda through scientific approach since policy analysis has direct impact on production. This study was done by the use of a stochastic model. In view of this, data were generated, collected and collated from Dangote Cement PLC, Ibese and used to test the validity and applicability of the model. Keywords: Casual workers, Random numbers, Stochastic, Optima

The Newsboy Problem In Determining Optimal Quantity In Stochastic Inventory Problem For Fixed Demand

This paper describes optimization problem related to newsboy model using the famous stochastic inventory problem in determining optimal order–up–to quantity when demand is a continuous random variable. This study was done by the use of a stochastic model. In view of this, data were collected and collated from cocoa board, Ilaro, Egbado-South, Nigeria and used to test the validity and applicability of the model. Keywords: Stochastic, demand uncertainty, concave, optimal order-up-to quantit

The influence of demand variability on the performance of a make-to-stock queue

Variability, in general, has a deteriorating effect on the performance of stochastic inventory systems. In particular, previous results indicate that demand variability causes a performance degradation in terms of inventory related costs when production capacity is unlimited. In order to investigate the effects of demand variability in capacitated production settings, we analyze a make-to-stock queue with general demand arrival times operated according to a basestock policy. We show that when demand inter-arrival distributions are ordered in a stochastic sense, increased arrival time variability indeed leads to an augmentation of optimal base-stock levels and to a corresponding increase in optimal inventory related costs. We quantify these effects through several numerical examplesproduction/inventory; make-to-stock; base-stock; stochastic comparisons; GI/M/1, POLICIES; COSTS; SYSTEMS; LEAD

The value of SKU rationalization: the pooling effect under suboptimal inventory policies

Managing product variety is a widely recognized challenge. Several approaches to this rely on the "pooling effect", the reduction of uncertainty that occurs when individual demands are aggregated. This can occur through reduction of number of products orSKUs, through postponement of differentiation, or in other ways. These approaches are by now well-known and widely applied in practice. However, theoretical analyses of the pooling effect always assume that one has an optimal inventory policy before and after pooling. If this is not the case, how does that affect the value of pooling? This paper analyses the benefits of pooling in terms of costs and service level under optimal and suboptimal policies and proposes a simple framework to analyze the trade-off between implementing pooling and improving inventory policy. We show there is always a range of current inventory levels within which pooling is better and beyond whichoptimizing inventory policy is better. We analyze how this range varies with the problem parameters and illustrate these findings using highly erratic empirical demand data

Supply planning for a closed loop system with uncertain demand and return

This proposed model considers a supply network consisting of a manufacturer, its external suppliers, and a remanufacturing facility. The manufacturer, facing an uncertain market demand and return, has two options for supplying parts: either ordering the required parts to external suppliers or remanufacturing used products and bringing those back to \u27as new\u27 conditions. We propose a general framework for this multi product, closed loop system and develop a non-linear programming (NLP) model to maximize the total expected profit by optimally deciding quantity of parts to be remanufactured and quantity of parts to be purchased from external suppliers. We solved the mathematical model using two different solution techniques to find optimal or near optimal solution values. With a numerical example we compared the results from both solution techniques and introduced sensitivity analysis to illustrate the interacting effects among critical parameters in the model

Modularity and Commonality Research: Past Developments and Future Opportunities

Research on modularity and commonality has grown substantially over the past 15 years. Searching 36 journals over more than the past 35 years, I identify over 160 references in the engineering and management literature that focus on modularity or commonality in the product and process development context. Each of the references is analyzed along the dimensions subject, effect, and research method. The subjects of these studies have been products, processes, organizations, and even innovations, although the set of references shows a strong preference towards products. Similarly, a broad range of effects has been studied, albeit with the topic cost dominating all other effects. A variety of research methods has been applied to the study of modularity and commonality but the distribution of research methods differs substantially for modularity and commonality research. Despite the wealth of existing research, there are still significant opportunities for future research. In particular, studies that incorporate modularity and commonality’s multiple effects on various players along the supply chain, that combine multiple research methods, and that follow systems over time appear very promising

Procurement policy and allocation policy of common component in a two-echelon assembled-to-stock system

Ph.DDOCTOR OF PHILOSOPH