Elias Olivares-Benitez | Universidad Panamericana (original) (raw)

Papers by Elias Olivares-Benitez

Complexity, Nov 12, 2018

Industrial systems, such as logistics and supply chain networks, are complex systems because they... more Industrial systems, such as logistics and supply chain networks, are complex systems because they comprise a big number of interconnected actors and significant nonlinear and stochastic features. This paper analyzes a distribution network design problem for a four-echelon supply chain. The problem is represented as an inventory-location model with uncertain demand and a continuous review inventory policy. The decision variables include location at the intermediate levels and product flows between echelons. The related safety and cyclic inventory levels can be computed from these decision variables. The problem is formulated as a mixed integer nonlinear programming model to find the optimal design of the distribution network. A linearization of the nonlinear model based on a piecewise linear approximation is proposed. The objective function and nonlinear constraints are reformulated as linear formulations, transforming the original nonlinear problem into a mixed integer linear programming model. The proposed approach was tested in 50 instances to compare the nonlinear and linear formulations. The results prove that the proposed linearization outperforms the nonlinear formulation achieving convergence to a better local optimum with shorter computational time. This method provides flexibility to the decision-maker allowing the analysis of scenarios in a shorter time.

Computación Y Sistemas, Mar 30, 2020

Location of small and large stores requires a market study to determine the demand for a product ... more Location of small and large stores requires a market study to determine the demand for a product in a particular region, as well as the selection of the target population. However, it is common to forget analyzing the impact of the competition regarding the suitability of locating facilities. The objective of this work is to propose a model that can be a tool to study the market; analyzing both demands as attraction factor and competition as rejection factor. The methodology used consists on the proposal of an exact model and a group of tests to prove its functionality. The model has characteristics that have not been considering before like a service radio where a new location can be open and is affected by customers and competitors. The results obtained demonstrated that the model suggests opening the facilities with fewer competitors and higher demand. This model is new because no other model considers how a new location is affected by competitors (rejection) and by customers (attraction), both located in a service radio area.

International Journal of Combinatorial Optimization Problems and Informatics, 2017

This paper summarizes our work towards developing a solution to the Curriculum Based Timetabling ... more This paper summarizes our work towards developing a solution to the Curriculum Based Timetabling Problem (CB-TTP) at a Mexican university and providing significant insights into timetable processing. We first, identified a data structure using a Mediation Software (MS). This software can read, analyze, and organize data from different institutional log files. Additionally, the MS makes groups of courses without interference in the curricula in order to eliminate this constraint of the Integer Programming (IP) model. Then, we present a comprehensive IP model, which use a set of complex constraints, e.g., professor’s availability, consider the course modality in order to assign an appropriate room, consecutive and isolated period of the courses, among others. Also, consider the constraint that ensures do not cancel courses of interest due to parallel assignments of the mandatory courses. With this methodology was possible to assign 2101 lectures and improve the efficiency of the current scheduling process.

Ciencias Holguín, Oct 30, 2017

Gestión de operaciones en una cadena de suministro agroalimentaria / Operations management in a a... more Gestión de operaciones en una cadena de suministro agroalimentaria / Operations management in a agri food supply chain Rafael Granillo-Macías.

Revista Global de Negocios, 2015

This paper discussed the importance that has the farming and rural markets of Huixcolotla and Zac... more This paper discussed the importance that has the farming and rural markets of Huixcolotla and Zacapoaxtla, located in the State of Puebla, Mexico, in regional economic development. The field work was carried out in the years 2011 and 2012. It is an explanatory study that deepens the knowledge of these markets with regard to production, marketing, costs, profits, employment, among others. The study focused on two regions of the State of Puebla: Northern and Central. The first is characterized by the production of crops in the form of temporary, the second is irrigation. The results indicate that both regions are an important revenue generator for the raw material suppliers, producers and marketers. The region of Huixcolotla provides more elements so that a process of accelerated regional economic development, is given since it generates higher profits when sold the product on the market. In addition, the investment of agricultural inputs and generation of jobs is greater. The existence of these rural markets, ensures income for producers and economic activity increases.

Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch ge... more Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may be saved and copied for your personal and scholarly purposes. You are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public.

Social Science Research Network, 2015

En éste artículo se analizó la importancia que tiene la actividad agrícola y los mercados rurales... more En éste artículo se analizó la importancia que tiene la actividad agrícola y los mercados rurales de Huixcolotla y Zacapoaxtla, ubicados en el estado de Puebla, México, en el desarrollo económico regional. El trabajo de campo se realizó en los años 2011 y 2012. Es un estudio explicativo que profundiza el conocimiento de dichos mercados con respecto a la producción, comercialización, costos, ganancias, generación de empleos, entre otros. El estudio se centró en dos regiones del estado de puebla: norte y centro. La primera se caracteriza por la producción de cultivos bajo la modalidad de temporal, la segunda es de riego. Los resultados indican que ambas regiones son un importante generador de ingresos para los proveedores de materias primas, productores y comercializadores. La región de Huixcolotla aporta más elementos para que se dé un proceso de desarrollo económico regional más acelerado, debido a que genera mayores ganancias cuando se vende el producto en el mercado; además, la inversión de insumos agrícolas y generación de empleos es mayor. La existencia de estos mercados rurales, asegura ingresos para los productores y la actividad económica incrementa.

Diversos documentos (Villa, 2011; DOF, 2013), reconocen que el acceso a capacitación, créditos, t... more Diversos documentos (Villa, 2011; DOF, 2013), reconocen que el acceso a capacitación, créditos, tecnología en la producción es prácticamente ausente para aquellos con "limitada vinculación al mercado" (72.6%), comparada con la de aquellos productores "en transición" (8.3%), con "actividad empresarial de rentabilidad frágil" (9.9%), más aún con quienes tienen una actividad pujante (8.4%) y dinámica (0.3%). Es preocupación de diversos organismos nacionales e internacionales "potenciar la competitividad de las empresas agroalimentarias procurando elevar la productividad de las unidades de baja escala" (IICA, 2010; DOF, 2013). Dicho esfuerzo también se plasma en la "estrategia agroalimentaria para la productividad" (DOF, 2013; PND, 2013-2018) la cual propone elevar la productividad del minifundio a través de modelos de asociatividad (clúster) y la integración de la cadena productiva que otorgue un papel más activo a los pequeños productores a lo largo de la cadena de valor reconociendo y fortaleciendo sus capacidades productivas e innovadoras.

International Transactions in Operational Research, Apr 20, 2016

This study presents a metaheuristic based on a multiobjective evolutionary algorithm to solve a b... more This study presents a metaheuristic based on a multiobjective evolutionary algorithm to solve a biobjective mixed-integer nonlinear programming model for supply chain design with location-inventory decisions and supplier selection. The supply chain has four echelons with suppliers, plants, distribution centers, and retailers. The decision variables are the opening of plants and distribution centers and the flow of materials between the different facilities, considering a continuous review inventory policy. The conflicting objectives are to minimize total costs on the entire chain, and to maximize a combined value of overall equipment effectiveness from suppliers. Small-and medium-sized scenarios are solved and compared with Pareto fronts obtained with commercial optimization software applying the epsilon-constraint method. The numerical results show the effectiveness of the proposed metaheuristic. The main contributions of this work are a new practical problem that has not been analyzed before, and the development of the evolutionary algorithm.

Custos e Agronegocio, 2018

Malted barley is the main raw material for brewing. In the last decade, Mexico has consolidated i... more Malted barley is the main raw material for brewing. In the last decade, Mexico has consolidated its position as the main beer brewer in the world. Freight and the operations related to the distribution of the harvest have an effect on the production costs and the amount of sawed, harvested and sold grain. This research study aimed at obtaining a mixed integer linear programming model and applying it in a malted-barley supply chain in Mexico. The model design a distribution network with minimal freight costs, considering variables like penalties/incentives, crop yields and costs of collecting points. This model allows identifying better scenarios that could be configured according to the agricultural contract that prevails in this chain. The results obtained in three possible scenarios showed through variations in the supply, demand and penalties / incentives the convenience of distributing 50% of the harvest obtained to each of the two malts with minimum costs between 329,210 and 598, 231 USD.

Management and Industrial Engineering, 2017

This chapter addresses a production planning problem for a company that mass-replicates compact d... more This chapter addresses a production planning problem for a company that mass-replicates compact discs. In the current situation, the staff of the company creates a production plan for the long term, with low flexibility to make a new plan when new orders arrive. The combination of attributes of the orders and the available machines for the processes generate a high complexity to determine the appropriate production routes and sequencing. To reduce complexity, the computation of a priority index is proposed to combine different attributes of the orders. To optimize the utilization of the production capacities, two approaches were proposed: a Simulation Model and a Linear Programming Model. The priority index is used in both models to promote early scheduling of certain orders to the machines during the planning horizon. The results show that the models proposed deliver production plans in a short time, with a better utilization of the production capacity, and with a focus on improving service level when compared to the current methodology in the company. Additionally, the Linear Programming Model is integrated into an intelligent decision-support system to guarantee the data transfer from the information system of the company and fast execution as often as needed.

International Journal of Operational Research, 2021

A shift scheduling problem for a call centre is solved by applying a column generation method. Th... more A shift scheduling problem for a call centre is solved by applying a column generation method. The objective is to find an employee schedule within the planning horizon that meets staffing requirements provided by the customer and that minimises the costs of excess-staffing and under-staffing. To solve the problem, two iterative models were used: the first being a mixed integer-linear programming model, the master problem, and the second being a column generation model. In a first approach, the master problem was solved considering a fixed number of shift patterns. The second approach was to use both models iteratively to generate shift patterns to be used in the master problem. Both approaches met all constraints relatively fast, but the column generation model decreased the cost considerably when cheaper shift patterns were generated. The models contribute to the current literature by providing flexibility to consider under-coverage and over-coverage at two levels.

Resumen— El problema del agente viajero y los modelos de ubicación de instalaciones son abordados... more Resumen— El problema del agente viajero y los modelos de ubicación de instalaciones son abordados a través de una aplicación práctica en la cadena de suministro agroalimentaria, considerando que es posible utilizar métodos cuantitativos de optimización que tradicionalmente se emplean en otros sectores. En este artículo se presenta un breve análisis sobre la cadena de suministro agroalimentaria haciendo una revisión de los conceptos generales. Dentro de este artículo se aplica para el caso de la cadena de suministro de la cebada en México un modelo de ubicación de instalaciones basado en las coordenadas geográficas de diferentes granjeros/productores con el fin de determinar la mejor ubicación para una posible apertura de un centro de acopio, y posteriormente se analiza una propuesta de ruta de entrega de semilla con base en el modelo TSP utilizando una búsqueda aleatoria. Palabras clave— cadena de suministro agroalimentaria, cebada, programación, TSP, localización de instalaciones. Introducción El problema del agente viajero o TSP (por sus siglas en inglés) se encuentra clasificado dentro de los problemas de optimización combinatoria del tipo NP-completos. Para la formulación de este tipo de problema se inicia por definir la estructura de la cadena de suministro identificada por destinos o ciudades, que de forma gráfica se representan por nodos y líneas que son utilizadas para conectar dos puntos, para cada recorrido entre ciudades existe un costo asociado con la distancia entre estas. Un recorrido completo que pasa por todas las ciudades y regresa al punto origen se denomina ciclo hamiltoniano, en el cual la suma de todas las distancias del recorrido representara la longitud del ciclo. Para el caso de la ubicación de instalaciones el objetivo es el de encontrar la mejor ubicación que minimice tanto el costo como la distancia asociada con los diferentes puntos de venta/distribución identificados para esta instalación (Chen et al., 2010). Generalmente, los métodos de optimización aquí descritos son aplicados en sectores de la manufactura y servicios. Sin embargo, en este caso se propone una aplicación práctica para resolver un problema de determinación de ubicación de instalaciones a través del método de TSP con el propósito de mejorar la distancia total recorrida realizada para la entrega de semilla en la cadena de suministro agroalimentaria de la cebada, específicamente con datos de granjeros/productores ubicados dentro del altiplano en el estado de Hidalgo.

Nova Scientia, 2015

Introducción: Los impactos del calentamiento global y el cambio climático son una preocupación en... more Introducción: Los impactos del calentamiento global y el cambio climático son una preocupación en prácticamente todos los sectores de la sociedad, debido a las consecuencias que ya se perciben y que afectarán cada día más a todos los sistemas naturales y creados por el hombre, generalmente de forma negativa. Para revertir estos efectos negativos y no continuar deteriorando el medio ambiente, es necesario un tipo especial de personas que sean capaces de tomar las decisiones adecuadas en los ámbitos en los que se desenvuelven. En esta investigación, estos seres humanos se denominan: personas con “talento verde”. El término talento verde no se ha sido caracterizado y su uso es aun restringido. Esta investigación hace una caracterización del talento verde y propone una encuesta para detectar a las personas que cuentan con estas características. Es importante hacer notar que este trabajo forma parte de una investigación más amplia que busca la relación entre directivos con talento verde ...

The high uncertainty in demand and supply in the agri food supply chain located logistics as a ke... more The high uncertainty in demand and supply in the agri food supply chain located logistics as a key element to improve their performance, thus optimization models focused on logistics transport operations seeking to reduce the costs associated with the move of food products Ciencias Holguín ISSN 1027-2127 1 Granillo, Olivares, Martínez, Caballero from point of harvest to the collection centers and processing considering the various constraints of these products as are the decay in quality, production performance, levels of customer service among others. This paper shows a solution to a transportation problem in the supply chain of barley in Mexico considering the particular levels of performance in harvesting under different scenarios. This study identifies the best assignments that minimize the cost of transportation in this chain.

Proceedings of the 11th International Conference on Operations Research and Enterprise Systems

Export shipments arriving late at the freight building of KLM Cargo at Schiphol Airport is a trig... more Export shipments arriving late at the freight building of KLM Cargo at Schiphol Airport is a trigger to deviations in the standard acceptance process. These Late Shows are currently handled ad-hoc making it difficult to plan and predict these events. By conducting a data analysis to quantitatively identify the characteristics of the Late Shows, and by conducting stakeholder interviews to understand the current process and discuss the future process, this research tried to design the operational process of the Late Shows to improve the operational excellence and quality of the acceptance process. The research shows that currently, late shipments are often still tried to be build up for the planned flight. It is found that 13% of these shipments do eventually not depart on the planned flight. The research concludes that the design of the Late Show process should include a check on whether the shipment was delivered on time, before acceptance of the shipment. By only accepting the shipment once it is decided that the planned flight is achievable or when it is rebooked to another flight, it is assured that the Late Show will be on time at the build-up buffer for the booked flight.

Diverse scheduling problems in education such as planning of lectures’ or exams’ timetables are a... more Diverse scheduling problems in education such as planning of lectures’ or exams’ timetables are among the most recurrent problems each begging of an academic period. Therefore, these areas have been gaining interest, the planning of the schedules of professors or exams for a set of groups and courses. The timetabling problem involves scheduling a number of resources, each consisting of class of students, a teacher, a subject and a room, to a fixed number of time slots. The problem of school timetabling is addressed for an institution of technical education, analyzing three groups of one specialty among those offered by the institution. A mathematical programming model using branch and bound technique was designed to solve the timetable problem for a Mexican Institution. The solutions obtained by this approximation were implemented in the 2013 - 2014 academic period. The proposed approach has proved very good results by helping the decision makers in the institution to solve the plan...

RESUMEN Un problema recurrente en cada inicio de periodo escolar en las Instituciones Educativas ... more RESUMEN Un problema recurrente en cada inicio de periodo escolar en las Instituciones Educativas (IEs) es la calendarización de horarios de los profesores para un conjunto de grupos y cursos. En este trabajo se pretende optimizar la asignación de cursos a grupos en un conjunto de periodos de tiempo con determinados requerimientos. Se aborda este problema dentro de un plantel de educación técnica media, en el cual se analizan tres grupos de la especialidad de Laboratorista químico ofertada por la institución. Se diseñó un modelo de programación matemática que fue resuelto mediante la técnica de ramificación y acotamiento disponible en un software comercial de optimización llamado LINGO® 10. Este caso real fue implementado en el ciclo 2013-2014 y validado con éxito al resolver en 4 segundos las actividades que realizarán los empleados dentro de una franja horaria de entre 5 a 7 horas. El enfoque planteado contribuye a agilizar la toma de decisiones del centro escolar al inicio del cic...

Int. J. Comb. Optim. Probl. Informatics, 2018

This article presents a methodology for solving the Periodic Vehicle Routing Problem (PVRP) with ... more This article presents a methodology for solving the Periodic Vehicle Routing Problem (PVRP) with an Iterated Local Search Metaheuristic (ILS). The problem is solved in two phases: the first step is to assign days of visit to each customer, and in the second step to determine the routes that each vehicle must perform each day. The heuristic for local improvement in ILS is Clarke & Wright Heuristic, and perturbation is made on the days of visit assigned to some customers. The instances generated by Cordeau for PVRP with 51, 102 and 153 customers are used. The results are compared to the best known solutions. The gap between the results presented by the proposed metaheuristic range from 15% to 5% above the best known solutions. The time to find the solutions with the proposed metaheuristic goes from 6.76 seconds for instances of 51customers, to 172.09 seconds for instances of 153 customers.

Optimizing Current Strategies and Applications in Industrial Engineering, 2019

A MILP and genetic algorithm optimization model for the sequencing of jobs in a medium-sized fact... more A MILP and genetic algorithm optimization model for the sequencing of jobs in a medium-sized factory, dedicated to the manufacturing of home furniture, where different categories and types of articles are produced and whose routes and manufacturing processing times vary widely, are proposed. Different scenarios are considered for the objective function based on minimizing makespan and tardiness. The results of the optimization for an instance of 24 jobs on five machines, chosen as a representative instance of the order sizes that are handled by the company, show important reductions in the productive system's usage times, oscillating between 10% and 20% with respect to a random initial sequence in the production plan. Improvements were similar in both techniques, the main difference being the solution time of each one.

Complexity, Nov 12, 2018

Computación Y Sistemas, Mar 30, 2020

International Journal of Combinatorial Optimization Problems and Informatics, 2017

Ciencias Holguín, Oct 30, 2017

Revista Global de Negocios, 2015

Social Science Research Network, 2015

International Transactions in Operational Research, Apr 20, 2016

Custos e Agronegocio, 2018

Management and Industrial Engineering, 2017

International Journal of Operational Research, 2021

Nova Scientia, 2015

Proceedings of the 11th International Conference on Operations Research and Enterprise Systems

Int. J. Comb. Optim. Probl. Informatics, 2018

Optimizing Current Strategies and Applications in Industrial Engineering, 2019

A supply chain design problem based on a two-echelon single-product system is addressed. The prod... more A supply chain design problem based on a two-echelon single-product system is addressed. The product is distributed from plants to distribution centers and then to customers. There are several transportation channels available for each pair of facilities between echelons. These transportation channels introduce a cost-time tradeoff in the problem to formulate a biobjective mixed-integer programming model. The decisions to be taken are the location of the distribution centers, the selection of the transportation channels and the flow between facilities. Since this problem is NP-hard a metaheuristic algorithm was developed to solve it. The metaheuristic algorithm is composed of three methods. The constructive method generates solutions using a random strategy for opening distribution centers and a weighted greedy function to select the transportation channel. The improvement method uses local search with a dominance strategy. The combination method is used for post-processing and is based on a Path Relinking scheme. The proposed algorithm was compared with a previously developed εconstraint based algorithm and over instances of different size. For the smallest instances, as expected, the reference algorithm was more efficient in terms of computing time and solution quality. However, for the largest instances with similar run times the metaheuristic algorithm achieved better results.

Sales territories design has been studied as the problem of grouping customers in large geographi... more Sales territories design has been studied as the problem of grouping customers in large geographical groups where each group is assigned to a salesman. The objectives are diverse like securing the compactness of the territories, maximizing profit, or balancing the salesmen workload. The problem addressed in this work is related to the re-design of sales territories. The problem is formulated as a three-objective optimization model. It considers the geographical balance of the territories and the balance of the workload of the sales force. A third objective is related to a new economic approach not treated in the literature previously. In general, sales territories already exist for operating firms, and their customers change because of market dynamics and salesmen efforts. The structure of economic rewards for the sales force is aligned with the sales volume achieved by each agent. Therefore a change in the design of the territories has an impact in such structure. Thus, the third objective looks for maintaining the sales volume for each salesman while reassigning the customers to satisfy the geographical and workload balances. The problem is solved using the epsilon-constraint method to obtain the efficient solutions set for data from real case instances.

In México, the brickworks are considered obnoxious facilities. The lack of regulation and the use... more In México, the brickworks are considered obnoxious facilities. The lack of regulation and the use of highly contaminant fuels and old technologies contribute to the pollution by these facilities. To reduce the pollution effects it has been considered their relocation. A multiobjective model is proposed to relocate these obnoxious facilities, considering economic, chemical and social aspects. A Gaussian diffusion model is integrated to guarantee that the contaminants received by the population do not exceed the legal limits. The model is solved using the epsilonconstraint method using commercial optimization software and data from a real case instance.