5 research outputs found
Lagrangian Relaxation for an Inventory Location Problem with Periodic Inventory Control and Stochastic Capacity Constraints
No full textIndexación: Scopus.We studied a joint inventory location problem assuming a periodic review for inventory control. A single plant supplies a set of products to multiple warehouses and they serve a set of customers or retailers. The problem consists in determining which potential warehouses should be opened and which retailers should be served by the selected warehouses as well as their reorder points and order sizes while minimizing the total costs. The problem is a Mixed Integer Nonlinear Programming (MINLP) model, which is nonconvex in terms of stochastic capacity constraints and the objective function. We propose a solution approach based on a Lagrangian relaxation and the subgradient method. The decomposition approach considers the relaxation of different sets of constraints, including customer assignment, warehouse demand, and variance constraints. In addition, we develop a Lagrangian heuristic to determine a feasible solution at each iteration of the subgradient method. The proposed Lagrangian relaxation algorithm provides low duality gaps and near-optimal solutions with competitive computational times. It also shows significant impacts of the selected inventory control policy into total system costs and network configuration, when it is compared with different review period values. © 2018 Claudio Araya-Sassi et al.https://www.hindawi.com/journals/mpe/2018/8237925
¿Es Chile un mercado competitivo? Análisis de la persistencia de la rentabilidad aplicando un panel dinámico
No full textLa persistencia de las rentabilidades es un fenómeno largamente estudiado, tanto en países desarrollados como en países en desarrollo. Sin embargo, la evidencia empírica es mixta. Mientras algunos estudios sugieren que las firmas compitiendo en países en desarrollo tienen niveles de persistencia menores, también existen estudios que señalan que la persistencia de las rentabilidades es menor en firmas de países desarrollados. En este estudio se utiliza una metodología de panel dinámico para analizar el nivel de persistencia de la rentabilidad de firmas compitiendo en Chile. Los resultados sugieren que en Chile existe un entorno competitivo más bien débil, que no logra erosionar sustantivamente el desempeño de las firmas, situando al país en un nivel de competitividad interna incluso menor al de países de un nivel de desarrollo económico inferior
O chile é um mercado competitivo? Análise da persistência da rentabilidade aplicando um painel dinâmico
No full textThe phenomenon of persistence of profits has been studied for a considerable time in both developed and developing countries. However, the empirical evidence is inconsistent: while some research suggests that companies operating in developing countries display lower persistence levels, other studies find this to be the case for firms in developed countries. This paper uses a dynamic panel approach to examine the persistence of profits of companies operating in Chile. The results suggest that Chile\u27s competitive environment is relatively weak and incapable of eroding company performance significantly. Chile displays lower levels of competetiveness even than countries with lower levels of economic development.La persistencia de las rentabilidades es un fenómeno largamente estudiado, tanto en países desarrollados como en países en desarrollo. Sin embargo, la evidencia empírica es mixta. Mientras algunos estudios sugieren que las firmas compitiendo en países en desarrollo tienen niveles de persistencia menores, también existen estudios que señalan que la persistencia de las rentabilidades es menor en firmas de países desarrollados. En este estudio se utiliza una metodología de panel dinámico para analizar el nivel de persistencia de la rentabilidad de firmas compitiendo en Chile. Los resultados sugieren que en Chile existe un entorno competitivo más bien débil, que no logra erosionar sustantivamente el desempeño de las firmas, situando al país en un nivel de competitividad interna incluso menor al de países de un nivel de desarrollo económico inferior.A persistência das rentabilidades é um fenômeno amplamente estudado, tanto em países desenvolvidos quanto em países em via de desenvolvimento. Contudo, a evidência empírica é variada: enquanto alguns estudos sugerem que as firmas que competem em países em desenvolvimento têm níveis de persistência menores, também existem estudos que indicam que a persistência das rentabilidades é menor em firmas de países desenvolvidos. Neste estudo, utiliza-se uma metodologia de painel dinâmico para analisar o nível de persistência da rentabilidade de firmas que competem no Chile. Os resultados sugerem que no Chile existe um ambiente competitivo mais fraco, que não consegue acabar substancialmente o desempenho das firmas, o que situa o país em um nível de competitividade interna inclusive menor ao de países de um nível de desenvolvimento econômico inferior
The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
No full textThe PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity
