The New Mathematical Models for Inventory Management under Uncertain Market

Abstract: This paper presents the new mathematical model for determining the optimal ordering policy for industrial and commercial companies. In the previous research, the numerous inventory models under inflationary conditions have been developed. In these models, the demand rate, usually, has been considered constant and well known, time-varying, stock dependent or price-dependent. But, the demand rate, usually, is uncertain in the real world. Therefore, in this study, the new inflationary inventory models under stochastic demand conditions have been developed. The inventory system is in the state of multi-items with budget constraint. The numerical examples have also been given to illustrate and validate the theoretical results

Modelos de Inventarios con Productos Perecederos: Revisión de la Literatura

This paper presents a review of the main characteristics of the mathematical modelsdeveloped by the scientific community in order to determine an optimal inventory policyfor deteriorating items. Thus, a classified bibliography of 390 articles published from2001 to 2014 in high-impact journals is submitted while considering the type of demandand deterioration, the integration of inventory and pricing decisions, the inclusionof shortage and/or the time value of money, the consideration of multiple items and/ormulti-echelon systems, and the incorporation of uncertain parameters other than demand.Finally, research questions not yet addressed by the research community in the field ofinventory control for deteriorating items are pointed out.En el presente artículo se lleva a cabo una revisión de las principales características estudiadas por la comunidad científica en el desarrollo de modelos matemáticos que buscan definir una política de inventario óptima para productos que se deterioran. De este modo, se referencian 390 artículos publicados a partir del año 2001 en revistas de gran impacto, teniendo en cuenta: el tipo de demanda y deterioro representado en los modelos matemáticos, el estudio de una política de precio óptima, la inclusión de faltantes y/o valor del dinero en el tiempo, el estudio de múltiples productos y/o dos o más eslabones de la cadena de suministro, y la utilización de parámetros o variables difusas. Finalmente, se identifican oportunidades de investigación que a la fecha no han sido abordadas por la comunidad científica en este campo del conocimiento

Modelling and Determining Inventory Decisions for Improved Sustainability in Perishable Food Supply Chains

Since the introduction of sustainable development, industries have witnessed significant sustainability challenges. Literature shows that the food industry is concerned about its need for efficient and effective management practices in dealing with perishability and the requirements for conditioned storage and transport of food products that effect the environment. Hence, the environmental part of sustainability demonstrates its significance in this industrial sector. Despite this, there has been little research into environmentally sustainable inventory management of deteriorating items. This thesis presents mathematical modelling based research for production inventory systems in perishable food supply chains. In this study, multi-objective mixed-integer linear programming models are developed to determine economically and environmentally optimal production and inventory decisions for a two-echelon supply chain. The supply chain consists of single sourcing suppliers for raw materials and a producer who operates under a make-to-stock or make-to-order strategy. The demand facing the producer is non-stationary stochastic in nature and has requirements in terms of service level and the remaining shelf life of the marketed products. Using data from the literature, numerical examples are given in order to test and analyse these models. The computational experiments show that operational adjustments in cases where emission and cost parameters were not strongly correlated with supply chain collaboration (where suppliers and a producer operate under centralised control), emissions are effectively reduced without a significant increase in cost. The findings show that assigning a high disposal cost, limit or high weight of importance to perished goods leads to appropriate reduction of expected waste in the supply chain with no major cost increase. The research has made contributions to the literature on sustainable production and inventory management; providing formal models that can be used as an aid to understanding and as a tool for planning and improving sustainable production and inventory control in supply chains involving deteriorating items, in particular with perishable food supply chains.the Ministry of Science and Technology, the Royal Thai Government

A two-warehouse inventory model for non-instantaneous deteriorating items with interval-valued inventory costs and stock-dependent demand under inflationary conditions

This research work develops a two-warehouse inventory model for non-instantaneous deteriorating items with interval-valued inventory costs and stock-dependent demand under inflationary conditions. The proposed inventory model permits shortages, and the backlogging rate is variable and dependent on the waiting time for the next order, and inventory parameters are interval-valued. The main aim of this research is to obtain the retailer’s optimal replenishment policy that minimizes the present worth of total cost per unit time. The optimization problems of the inventory model have been formulated and solved using two variants of particle swarm optimization (PSO) and interval order relations. The efficiency and effectiveness of the inventory model are validated with numerical examples and a sensitivity analysis. The proposed inventory model can assist a decision maker in making important replenishment decisions.</p

Mathematical Modeling with Differential Equations in Physics, Chemistry, Biology, and Economics

This volume was conceived as a Special Issue of the MDPI journal Mathematics to illustrate and show relevant applications of differential equations in different fields, coherently with the latest trends in applied mathematics research. All the articles that were submitted for publication are valuable, interesting, and original. The readers will certainly appreciate the heterogeneity of the 10 papers included in this book and will discover how helpful all the kinds of differential equations are in a wide range of disciplines. We are confident that this book will be inspirational for young scholars as well

Mathematical Methods and Operation Research in Logistics, Project Planning, and Scheduling

In the last decade, the Industrial Revolution 4.0 brought flexible supply chains and flexible design projects to the forefront. Nevertheless, the recent pandemic, the accompanying economic problems, and the resulting supply problems have further increased the role of logistics and supply chains. Therefore, planning and scheduling procedures that can respond flexibly to changed circumstances have become more valuable both in logistics and projects. There are already several competing criteria of project and logistic process planning and scheduling that need to be reconciled. At the same time, the COVID-19 pandemic has shown that even more emphasis needs to be placed on taking potential risks into account. Flexibility and resilience are emphasized in all decision-making processes, including the scheduling of logistic processes, activities, and projects

Aplicación de la gestión de almacenamiento para reducir los costos de inventario en la empresa Tecnología Fabricación y Mantenimiento SAC, Chimbote – 2021

Esta investigación tuvo como objetivo general aplicar la gestión de almacenamiento para reducir los costos de inventario en la empresa Tecnología Fabricación y Mantenimiento SAC, Chimbote, la metodología empleada fue de tipo aplicada, fue de enfoque cuantitativo y de diseño pre experimental. En los resultados se determinó que las principales causas que generan elevados costos de inventario son que no hay un registro de evaluación de proveedores, la falta de procedimiento de compras y almacenamiento, existe una mala distribución física del almacén, no existe planificación de compras de productos y la falta de un sistema de inventario; a su vez, se determinó que el costo de compras y el costo por mantener son montos elevados para la empresa, para dar solución a los problemas se implementó un procedimiento para la adquisición de materiales, se realizó una evaluación a los proveedores, se rediseño el almacén para la correcta distribución física de los productos, luego se hizo un pronóstico de compras, y finalmente se implementó el EOQ. Como conclusión, se determinó que el costo de compras es de S/. 330.80 soles y el costo por mantener es de S/. 130.48 soles, donde estos valores son menores con respecto al diagnóstico inicia

Aplicación de las buenas prácticas para reducir los costos de almacenamiento en la Empresa Distribuidora PMA EIRL, Chimbote – 2021

Esta investigación tuvo como objetivo general aplicar las buenas prácticas para reducir los costos de almacenamiento en la empresa Distribuidora PMA EIRL, Chimbote, la metodología empleada fue de tipo aplicada, fue de enfoque cuantitativo y de diseño pre experimental. En los resultados se determinó que las principales causas que generan elevados costos de almacenamientos son que no hay un registro de evaluación de proveedores, la falta de procedimiento de compras y almacenamiento, existe una mala distribución física del almacén, no existe planificación de compras de productos y la falta de un sistema de inventario; a su vez, se determinó que el costo de compras ascendió a S/. 10,354.50 soles, y el costo de almacenamiento fue de S/. 4,349.79 soles, estos montos son elevados para la empresa, para dar solución a los problemas se implementó un procedimiento para la adquisición de materiales, se realizó una evaluación a los proveedores, se rediseño el almacén para la correcta distribución física de los productos, luego se hizo un pronóstico de compras, y finalmente se implementó el sistema kardéx. Como conclusión, se determinó que el costo de compras fue S/. 1,956.50 soles y de almacenamiento fue S/. 479.58 soles, mostrando que estos valores son menores

Essays on macroeconomics: Macroeconomic policy and economic performance.

This thesis discusses the three issues that are important to macroeconomic policymakers. First, I examine the role of inventories over the business cycle. Despite accounting for less that 1% of the level of GDP, inventory changes have made up almost 50% of the post-war volatility of US GDP growth, and yet most models of the business cycle exclude inventories. I develop a dynamic business cycle model that incorporates distribution inventories as well as simple storage inventories. I find that the behaviour of inventories in this model matches the aggregate data well. However, there is little evidence that improved inventory management contributed to the decline in macroeconomic volatility over the last quarter of a century. Second, the optimal design of a monetary policy committee (MPC) is examined as to whether such committees should include a mix of members from outside (external) as well as inside central banks (internal). Using a new theoretical model of voting behaviour on a mixed committee, it is shown that, under certain circumstance and behaviour, the presence of external committee members may be beneficial. However, using the voting record of the Bank of England's MPC, reveals a problem; there is evidence of an agency problem which may eliminate any benefit to the appointment of external members. These results undermine the current intuition as to why such mixed committees should be employed by policymaking institutions. Finally, I investigate the effect of policy uncertainty on household saving using a quasi-natural experiment from Germany in the late 1990s. Around the 1998 election, there was a marked increase in uncertainty; using the fact that civil servants were largely unaffected by this policy uncertainty, we show that households reacted to the increase in uncertainty by saving more and, where possible, by working more via the margin offered by part-time employment