Pilar I. Vidal-Carreras

Economic lot scheduling with deliberated and controlled coproduction

This paper presents an algorithm to define the optimal parameters for deliberated and controlled coproduction in an economic lot scheduling problem setting (DCCELSP). Coproduction is said to be deliberated and controlled because it is possible to decide whether or not to coproduce when all the parameters associated with the process are known. The aim is to determine how to produce two products most economically where deliberated coproduction is an option. For this purpose, a procedure for defining optimal lot periods is introduced. Two models are proposed for this procedure and a numerical illustration is provided to gain insight into their dynamics. The cost advantages of coproduction were found to depend on the relationship between setup and holding costs, production rates, and demand for products. The more similar these system parameters are and the higher the machine usage ratio is, the more favourable coproduction is. Additionally, if coproduction is not deliberated appropriately, costs soar.

Competence Acquisition, Encouragement and Development in Smart Organizations: Some Examples

A good competence and knowledge management is required in smart companies to achieve and maintain competitive advantages. In this context, competence acquisition, encouragement and development are needed to hire and retain talented employees in these companies. In this paper, we describe briefly some examples according to these three dimensions.

Wiki as an Activity Learning

The purpose of this paper is to analyse the design of an activity based on wiki technology in a Higher Education environment, specifically in engineering studies. The issues proposed here are based on the previous experience of the authors by developing a wiki activity in the field of industrial engineering. Wiki is considered a type of Web 2.0 technology that enables users to work together on the Web. The research literature reports a number of experiences with wiki-based collaborative writing in education. However, to enable all the advantages as far as possible, a clear specific description of the activity is mandatory for both students and teachers. This work confers guidelines as to how wikis will be developed and evaluated. Regarding developing wikis, the content of this task is specified in collaboration with the instructor. Regarding assessments, the quality of the wikipage and possible competences developed should be considered. The methodological design presented herein intends to act as a basis for the wiki-based collaborative writing approach. In addition, a list of assessment indicators that can be the basis for a future research line related to an automated tool for evaluating wiki is provided.

A practical model for managing inventories with unknown costs and a budget constraint

The economic production quantity method is one of the simplest models to control production and inventory. However, the assumptions on which it is based make its application difficult in practical situations. In most companies, set-up and inventory costs are unknown, or may not even exist as such, although other data are known, such as available capacity in machining hours and limits set by the financing subsystem. The present work offers a multi-item inventory model that sets reference values using known values such as inventory investment limits and production capacity. In order to confer the proposed model’s larger practical content, a spreadsheet available to be downloaded has been implemented. Finally, the model dynamics is illustrated as a numerical example obtained from a real company.

Considering the effect of demand diversity on the performance of different production strategies for the Economic Lot Scheduling Problem

We consider the problem of scheduling the production of multiple products on a single facility with limited production capacity, in literature known as Economic Lot Scheduling Problem (ELSP). In this work we compare the performance of five different production strategies for the ELSP under different stationary stochastic demand patterns. The performance, related to total inventory and setup costs, of different approaches to this problem is clearly dependent upon the production environment. In this study we focus on demand rates, as one of the most important parameters affecting this environment. We analyze through a simulation study the effect of diversity on stochastic demand rates, under different utilization levels. The results of our simulation study confirm that the performance of a production strategy is strongly dependent on utilization and homogeneity of demand rates. Therefore, this effect proves that a sensitivity analysis to evaluate the impact of the particular value of these and other parameters on the performance of the production strategies might be a key issue for industrial applications of the ELSP.

Estimating Costs in the EOQ Formula

The EOQ formula (Harris, Fact Mag Manage 10(2):135-6-152, 1913) provides a balance between setup costs and holding costs in the system. This formula has been widely developed in the literature. However in the industrial reality, it is often difficult to know the exact value of these setup and holding costs. In this paper, we develop a formula to estimate lot size from the values known in the company. It is verified that the behavior of these formulas meets expectations.