In this paper, we introduce an inventory routing problem with network disruptions. In this problem, not only decisions on inventory levels and vehicle routing are made simultaneously, but also, we consider disruptions over the networks in which a number of arcs are vulnerable to these disruptions, leading to an increase in travel times. We develop a dynamic programming approach to deal with this situation, and we also evaluate some policies adapting well-known instances from the literature.

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Este artículo presenta un modelo para el diseño de una red de distribución considerando la demanda bajo incertidumbre en un ambiente de múltiples productos y múltiples periodos. El modelo propuesto integra un problema de localización de instalaciones y un problema de distribución con restricciones difusas en el cumplimiento de la demanda, el cual se resuelve utilizando el método de restricciones suaves propuesto por Zimmermann considerando parámetros difusos en el lado derecho de las restricciones de un problema de programación lineal entera mixta y funciones de pertenecía lineales. Los resultados encontrados muestran como la localización de las plantas y almacenes se puede conservar para en el modelo flexible, mientras se realiza un balance entre el inventario generado y el costo incurrido.

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Este trabajo propone el desarrollo de un modelo basado en dinámica de sistemas en el cual se caracteriza el sistema de transporte de Bogotá D.C. Para realizar esto se modelan las variables principales que intervienen en el sistema de transporte para así lograr un análisis global de la problemática de transporte y evaluar posibles soluciones propuestas por diferentes expertos.El modelo es desarrollado mediante el software Stella, y en él se incluyen los diferentes actores que intervienen en la problemática global. Previo al desarrollo del modelo computacional, se lleva a cabo la recolección de información a través de expertos en el tema, que permita realizar una caracterización inicial, para poder así comprender la relación entre variables. Adicionalmente se evalúan sobre el modelo seis diferentes alternativas de solución a la problemática, para observar el impacto que éstas tendrían sobre el sistema de transporte.

Objectives: The 9.5 version of IQVIA-CORE-Diabetes-Model (CDM) includes a simplified foot ulcer (FU) submodel. The current study aims to explain the differences between the new and previous FU submodel and assess their impact on health economic outputs. Methods: The updated FU submodel is a five-health-state Markov Model (no history of ulcer, active ulcer, history of ulcer, history of amputation, death) with an annual cycle length, using the UKPDS82 risk equations (user defined inputs are optional). The previous FU submodel comprised nine health-states with monthly cycles and included options of screening and several treatment types. To test this update, cohorts were simulated with baseline characteristics and treatment effects from the observational EDGE study comparing metformin+vildagliptin (M+V) with metformin+sulphonylurea (M+S), with mean age of 57.8 years and time horizon of 50 years. Patients had no history of ulcer and amputation. Cumulative Incidence (CI) of FU complications, total and quality-adjusted life years (LY, QALY) were determined. The economic analysis employed UK 2018 costs and applied an annual discount rate of 3.5% on costs and outcomes. Results: The updated FU model leads to moderate differences in first ulcer CI (M+V: 2.86% to 3.45%; M+S: 2.90% to 3.64%) and amputation rate (M+V: 1.10% to 0.82%; M+S: 1.08% to 0.85%). Changes benefit the most effective arm, which also reflects in a limited difference in costs between the two arms (10 GBP). FU-related costs are reduced (M+V: -4.67%; M+S: -1.12%). The new model results in higher LY (M+V: +0.224; M+S: +0.258) and QALY (M+V: +0.038; M+S: +0.052), mainly due to the updated renal submodel, which reduces end-stage renal disease CI (M+V: 9.91% to 2.39%; M+S 10.03% to 2.41%). The Incremental Cost-Utility Ratio (ICUR) increases from 8,455 to 10,410 GBP/QALY. Conclusions: Using the simplified ulcer model of v9.5 CDM results in small differences in FU-related incidence, benefiting the most effective treatment arm.

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