Papers by Armin Lüer-Villagra
The leader multipurpose shopping location problem
European Journal of Operational Research
Controllable and non-controllable factors to measure performance in primary care practices under Medicare alternative payment models
Operations research for health care, 2021
We analyze the two recent Medicare alternative payment models, the comprehensive primary care plu... more We analyze the two recent Medicare alternative payment models, the comprehensive primary care plus (CPC+) and the primary care first (PCF). Both models comprise fee-for-service, traditional capitation, and pay-for-performance (P4P) components. The main objective of these reimbursement models is to advance toward value-based care. However, the models confer some hesitations since the P4P component is based on factors not entirely controlled by the practice, increasing the potential admission of healthier patients and affecting the profit of small primary care practices. We have modified the P4P component in both models to include a non-controllable agent (the hierarchical condition category score) and a controllable factor (the Bice–Boxerman continuity of care index) through a probabilistic classification model to predict hospital admissions. This study aims to determine the impact of adjusting the P4P component, in the CPC+ and PCF reimbursement models, on the profit per team, reven...
The aim of this paper is to analyze the results of the implementation of several parallelization ... more The aim of this paper is to analyze the results of the implementation of several parallelization techniques for the metaheuristics applied to the p-median problem. Further analysis showed: constraints on the number of processors used because of the network technology, advantages in the use of multiprocessors and the penalty in performance when using intensive communications strategies. Moreover, within the optimization using heuristics there is always an implicit balance between speed in obtaining a solution and the quality of it, which suggests the use of hybrid strategies that exploit the best of each.
Managing premium wines using an $$(s - 1,s)$$ ( s - 1 , s ) inventory policy: a heuristic solution approach
Annals of Operations Research
Effects of multipurpose shopping trips on retail store location in a duopoly
European Journal of Operational Research
A single allocation p-hub median problem with general piecewise-linear costs in arcs
Computers & Industrial Engineering
The milk collection problem with blending and collection points
Computers and Electronics in Agriculture, 2017
A novel problem for the collection of raw milk from a network of farms supplying a dairy is speci... more A novel problem for the collection of raw milk from a network of farms supplying a dairy is specified and solved. The proposed approach incorporates milk blending and the delivery of production to collection points by small, distant farms. The milk is collected by, and blended in, a homogeneous fleet of trucks and classified according to the lowest quality product included in the blend. Optimization criteria are used to determine where the collection points should be located and which producers are allocated to them for delivery, with all other production picked up directly at the farms. The approach is built around an integer programming model and two implementation strategies, one using a branch-and-cut algorithm for small instances and the other a heuristic procedure combining both exact and approximated methods to handle large instances within a reasonable computation time. A real case study involving 500 farms and 112 possible collection points is solved and the results compared. The impact on the solutions of dividing the real instance into zones is also explored.
Optimal Repairable Spare-Parts Procurement Policy under Total Business Volume Discount Environment
Reliability Engineering & System Safety, 2016
The maxisum and maximin-maxisum HAZMAT routing problems
Transportation Research Part E: Logistics and Transportation Review, 2016
Scheduling operating rooms with consideration of all resources, post anesthesia beds and emergency surgeries
Computers & Industrial Engineering, 2016
Integrating mining loading and hauling equipment selection and replacement decisions using stochastic linear programming
International Journal of Mining, Reclamation and Environment, 2015
Equipment selection is a key strategic decision in the design of a material handling system, beca... more Equipment selection is a key strategic decision in the design of a material handling system, because an improper one will lead to operational problems and unnecessary investment costs. It involves determining the number and combination of loaders and trucks which will move the material, fulfilling a specified production schedule. Previous works have addressed this problem with deterministic approaches, without considering the inter-dependent availability of trucks and loaders. In order to fill this gap, we developed a stochastic model that combines the selection and equipment replacement problems, subject to a stochastic production rate constraint. This is a new idea that will help decision-makers to decide faster and more reliable. The proposed model optimises the fleet by minimising the total life cycle costs. To solve it, we used a linearisation approach that reduces the computational effort. We tested our approach with a benchmark model, using a mining case study. Results indicate that the solutions ensure with a high probability a determined production target, producing good robust solutions compared to the deterministic counterpart.
El objetivo de este trabajo es poner a prueba distintos enfoques de paralelización (sincrónico, c... more El objetivo de este trabajo es poner a prueba distintos enfoques de paralelización (sincrónico, cooperativo, centralizado, etc.) para las metaheurísticas empleadas, en los algoritmos de resolución del problema de las p-medianas. Un análisis posterior arrojó: limitaciones en la cantidad de procesadores utilizados debido a la tecnología de red, ventajas en el uso de multiprocesadores y la penalización en el rendimiento al emplear estrategias intensivas en comunicación. Además, en la optimización mediante heurísticas siempre está implícito un balance entre la velocidad en la obtención de una solución y la calidad de ésta, por lo que se sugiere el uso de estrategias híbridas, que aprovechan lo mejor de cada una de ellas.
European Journal of Operational Research, 2015
The hazardous material routing problem from an origin to a destination in an urban area is addres... more The hazardous material routing problem from an origin to a destination in an urban area is addressed. We maximise the distance between the route and its closest vulnerable centre, weighted by the centre's population. A vulnerable centre is a school, hospital, senior citizens' residence or the like, concentrating a high population or one that is particularly vulnerable or difficult to evacuate in a short time. The potential consequences on the most exposed centre are thus minimized. Though previously studied in a continuous space, the problem is formulated here over a transport (road) network. We present an exact model for the problem, in which we manage to significantly reduce the required variables, as well as an optimal polynomial time heuristic. The integer programming formulation and the heuristic are tested in a real-world case study set in the transport network in the city of Santiago, Chile.
The Follower Competitive Location Problem with Comparison-Shopping
Networks and Spatial Economics
The hazardous material routing problem from an origin to a destination in an urban area is addres... more The hazardous material routing problem from an origin to a destination in an urban area is addressed. We maximise the distance between the route and its closest vulnerable centre, weighted by the centre's population. A vulnerable centre is a school, hospital, senior citizens' residence or the like, concentrating a high population or one that is particularly vulnerable or difficult to evacuate in a short time. The potential consequences on the most exposed centre are thus minimized. Though previously studied in a continuous space, the problem is formulated here over a transport (road) network. We present an exact model for the problem, in which we manage to significantly reduce the required variables, as well as an optimal polynomial time heuristic. The integer programming formulation and the heuristic are tested in a real-world case study set in the transport network in the city of Santiago, Chile.
A milk collection problem with blending is introduced. A firm collects milk from farms, and each ... more A milk collection problem with blending is introduced. A firm collects milk from farms, and each farm produces one out of three possible qualities of milk. The revenue increases with quality, and there is a minimum requirement at the plant for each quality. Different qual- ities of milk can be blended in the trucks, reducing revenues, but also transportation costs, resulting in higher profit. A mixed integer-programming model, a new cut, and a branch- and-cut algorithm are proposed to solve medium-sized instances. A three-stage heuristic is designed for large instances. Computational experience for test instances and a large-sized real case is presented.
A competitive hub location and pricing problem
Early studies by Armin Lüer-Villagra
Resumen. En general en las universidades se desarrollan actividades de extensión y vinculación ac... more Resumen. En general en las universidades se desarrollan actividades de extensión y vinculación académica como charlas, seminarios, clases magistrales, cátedras, etc., que comúnmente son desaprovechadas por la sobrecarga de trabajo, o por la falta de difusión.
Resumen. El presente artículo propone el diseño de un sistema de cómputo de alto rendimiento, en ... more Resumen. El presente artículo propone el diseño de un sistema de cómputo de alto rendimiento, en el que se utiliza un laboratorio de computación como un cluster durante el tiempo en que no se está utilizando para realizar clases. Para esto, se comienza describiendo la infraestructura típica con la que se cuenta en un laboratorio de computación, para posteriormente detallar el sistema propuesto, sus características y como se integraría a una instalación existente de forma transparente para los usuarios. Dentro de las características de este sistema, se mencionan sus fortalezas y debilidades. Finalmente se plantean aplicaciones posibles que podrían dársele, considerando las particularidades de su arquitectura funcional.
Resumen. Uno de los problemas típicos que conforman la gestión logística habitual es el de rutas ... more Resumen. Uno de los problemas típicos que conforman la gestión logística habitual es el de rutas de vehículos. Inicialmente enunciado en la década de 1950, ha sido ampliamente estudiado, y se han ideado diversas técnicas para resolverlo. El presente
Uploads
Papers by Armin Lüer-Villagra
Early studies by Armin Lüer-Villagra