Carlos Andrés Romano

Two Simple Constructive algorithms for the Distributed Assembly Permutation Flowshop Scheduling Problem

Nowadays, it is necessary to improve the management of complex supply chains which are often composed of multi-plant facilities. This paper proposes a Distributed Assembly Permutation Flowshop Scheduling Problem (DAPFSP). This problem is a generalization of the Distributed Permutation Flowshop Scheduling Problem (DPFSP) presented by Naderi and Ruiz (Comput Oper Res, 37(4):754–768, 2010). The first stage of the DAPFSP is composed of f identical production factories. Each center is a flowshop that produces jobs that have to be assembled into final products in a second assembly stage. The objective is to minimize the makespan. Two simple constructive algorithms are proposed to solve the problem. Two complete sets of instances (small-large) are considered to evaluate performance of the proposed algorithms.

A Model of Makespan Flow-Shop Scheduling Under Ergonomic Requirements

This paper address the recent growing interest the industrial environment has put over the healthy work. The ergonomics studies worker’s fatigue and muscular stress risks. It shows the need to measure and evaluate risks to improve the efficiency and reduce the costs. Based on a literature review from the scheduling and ergonomics point of view implications are highlighted. The paper presents a MILP mathematical model to minimize makespan in an n-job flow shop problem with sequence dependent setup times considering recovery times.

Using blogs in teaching postgraduate courses

In this paper we present the experience of using blogs in teaching postgraduate courses. For this, we previously describe good practices and principles that must be satisfied in order to determine whether the use of blogs allows achieving the main objective of teaching-learning process: the acquisition of skills by students. Finally, we show an example.

Metaheuristics for multiobjective goods routing

Good transportation is a key activity within the supply chain, as it has a direct impact on the companys total costs and in customers service, giving it a special interest for seeking ways to optimize these distribution processes. In the literature there is a large number of approaches to optimize these processes, which generally require advanced methods for its solution. This article reviews the most used metaheuristics for solving multiobjective problems applied in goods distribution networks and analyzes the most common objectives used in such approaches. Some trends are identified in order to suggest some areas for future research.

Redefinition of Tasks to Increase the Process Capacity of Bottlenecks: Adjustment to a Real Case of Cutting Process of Structural Profiles of Carbon Steel

Once identified the bottleneck process, that one that limits the total capacity of the system, the following logical step is tied to the decision of how to optimize it. It will be necessary to know all the tasks that influence the speed of the process. The limitations can appear as materials, information, persons, machinery or any another aspect. It is very usual to connect the limitation of the process to aspects that, though indirectly if they determine the same one, they are not really those on which it is necessary to work hard. Therefore, the efficiency in the redesign of the process does not have the desired result. The detailed analysis of the procedure of each task that takes part in the process at some point of its accomplishment, allows knowing with accuracy the proper restrictions as well as the critical points on which it is necessary to work. This article provides a guide to the implementation of process improvements (regardless of the process in question) by identifying the constraints and solving them. The solutions are intended to increase the process speed, which is converted to a capacity increase of the whole organization. In the business of transformation of structural steel we meet the process of cutting as the common bottleneck of different organizations located in this sector. The standard product supplied by the manufacturers of steel is characterized by standard lengths. For the construction of structures, where the lengths are variable, it needs additional cutting to obtain specific lengths. This transformation of the base product is habitually done by appropriate machinery, and the capacities of cutting are based with the own process time of cutting. The optimization of this one task, measure as the increase of the number of hours of effective cutting, is obtained reducing to the maximum all the restrictions that limit the speed of the process. In our practical case, the solution to the bottleneck of cutting to allow the increase of sales could be solved by subcontracting, buying new tangible fixed assets or optimizing the process. The latter aspect is the developed one in this case of study. The cutting program is subordinated to the optimization of the bottleneck. We took measurements before the redesign of the process as well as after the changes. The result is cutting capacities much better than the initial values. This case of study is used in different degrees and master class as an example of the steps to identify, to analyze and to re-design a process. In addition, we emphasize the importance of measuring to understand the successfulness of the changes. For the real organizations, the redesign is fundamentally based on the learning and growth perspective. People who take part in the process are instructed in order to obtain a coherent adjustment with the needs of the new way of processing.

Scheduling unrelated parallel machines with resource-assignable sequence-dependent setup times

A novel scheduling problem that results from the addition of resource-assignable setups is presented in this paper. We consider an unrelated parallel machine problem with machine and job sequence-dependent setup times. The new characteristic is that the amount of setup time does not only depend on the machine and job sequence but also on the amount of resources assigned, which can vary between a minimum and a maximum. The aim is to give solution to real problems arising in several industries where frequent setup operations in production lines have to be carried out. These operations are indeed setups whose length can be reduced or extended according to the amount of resources assigned to them. The objective function considered is a linear combination of total completion time and the total amount of resources assigned. We present a mixed integer program (MIP) model and some fast dispatching heuristics. We carry out careful and comprehensive statistical analyses to study what characteristics of the problem affect the MIP model performance. We also study the effectiveness of the different heuristics proposed.