Comments on Two Models for Operating Two-Warehouse Inventory Systems with Deteriorating Items and Inflationary Effects

2011 ◽  
Vol 2 (2) ◽  
pp. 1-21
Author(s):  
Huachun Xiong ◽  
Jinxing Xie ◽  
Bo Niu
Keyword(s):  
Infinite Horizon ◽  
Planning Horizon ◽  
Inventory Systems ◽  
Traditional Model ◽  
Present Value ◽  
Total Cost ◽  
Demand Rate ◽  
Replenishment Cycle ◽  
The Cost ◽  
Infinite Planning Horizon

This paper deals with the two-warehouse partial backlogging inventory problems under inflation for a deteriorating product with a constant demand rate over an infinite horizon. In contrast to the traditional model in which each replenishment cycle starts with an instant replenishment and ends with shortages, an alternative model is proposed in recent literature in which each cycle starts with shortages. It is proven to be less expensive to operate than the traditional model in terms of the present value of the cost per unit time. The present paper points out that the criteria of minimizing the cost per unit time is unreasonable when the inflationary effect is taken into consideration, and instead, the criteria of minimizing the present value of the total cost over the whole infinite planning horizon should be used. The objective functions of these two models are changed and proved that the model with shortages at the start of the cycle is less expensive to operate than the traditional model in terms of the present value of the total cost, but the optimal solutions of the models minimizing the cost per unit time indicate significantly higher total costs.

Comments on Two Models for Operating Two-Warehouse Inventory Systems with Deteriorating Items and Inflationary Effects

2013 ◽  
pp. 349-370
Author(s):  
Huachun Xiong ◽  
Jinxing Xie ◽  
Bo Niu
Keyword(s):  
Infinite Horizon ◽  
Planning Horizon ◽  
Inventory Systems ◽  
Traditional Model ◽  
Present Value ◽  
Total Cost ◽  
Demand Rate ◽  
Replenishment Cycle ◽  
The Cost ◽  
Infinite Planning Horizon

This paper deals with the two-warehouse partial backlogging inventory problems under inflation for a deteriorating product with a constant demand rate over an infinite horizon. In contrast to the traditional model in which each replenishment cycle starts with an instant replenishment and ends with shortages, an alternative model is proposed in recent literature in which each cycle starts with shortages. It is proven to be less expensive to operate than the traditional model in terms of the present value of the cost per unit time. The present paper points out that the criteria of minimizing the cost per unit time is unreasonable when the inflationary effect is taken into consideration, and instead, the criteria of minimizing the present value of the total cost over the whole infinite planning horizon should be used. The objective functions of these two models are changed and proved that the model with shortages at the start of the cycle is less expensive to operate than the traditional model in terms of the present value of the total cost, but the optimal solutions of the models minimizing the cost per unit time indicate significantly higher total costs.

scholarly journals VIABILIDADE ECONÔMICA DA PRODUÇÃO DE CARVÃO VEGETAL EM DOIS SISTEMAS PRODUTIVOS

FLORESTA ◽  
2014 ◽  
Vol 44 (1) ◽  
pp. 143 ◽  
Author(s):  
Aylson Costa Oliveira ◽  
Thiago Taglialegna Salles ◽  
Bárbara Luísa Corradi Pereira ◽  
Angélica De Cássia Oliveira Carneiro ◽  
Camila Soares Braga ◽  
...  
Keyword(s):  
Economic Analysis ◽  
Net Present Value ◽  
Production Systems ◽  
Planning Horizon ◽  
Economic Viability ◽  
Present Value ◽  
Charcoal Production ◽  
Average Annual Production ◽  
The Cost ◽  
Benefit Cost

O objetivo deste trabalho foi analisar a viabilidade econômica da produção de carvão vegetal em dois sistemas produtivos: oito fornos de superfície acoplados a uma fornalha para queima de gases e dez fornos do tipo “rabo-quente” sem sistema de queima de gases. Para análise econômica, definiu-se uma produção anual média igual a 1.571 metros cúbicos de carvão (mdc) e horizonte de planejamento de 12 anos, sendo propostos 2 cenários. No primeiro cenário, após a colheita da madeira, realiza-se o plantio de uma nova floresta, permanecendo o custo da madeira constante em todo o planejamento; no segundo cenário, após a colheita, considerou-se a condução da brotação, reduzindo os custos na 2ª rotação e consequentemente os custos da madeira. A análise econômica foi realizada através da determinação dos seguintes indicadores: Valor Presente Líquido (VPL), Valor Anual Equivalente (VAE), Razão Benefício/Custo (B/C) e Lucratividade. Os indicadores calculados demonstraram a viabilidade dos dois sistemas produtivos avaliados em ambos os cenários propostos, porém o sistema fornos-fornalha apresentou melhores valores para os indicadores. Conclui-se que a produção de carvão vegetal nos sistemas avaliados foram viáveis economicamente, com o sistema fornos-fornalha gerando maior lucro ao produtor de carvão.Palavras-chave: Fornos de alvenaria; análise determinística; valor presente líquido. Abstract Economic viability of charcoal production in two production systems. The objective of this study was to analyze the economic viability of charcoal production in two conversion technologies: eight surface kilns coupled to a furnace for burning gases (kilns-furnace system) and ten "rabo-quente" or traditional charcoal kilns without burning gases system. An average annual production of 1571 cubic meters of charcoal (mdc) was used to perform the economic analysis. A planning horizon of 12 years and two scenarios were proposed. In the first scenario, after harvesting the wood, the planting of a new forest was performed, and the cost of wood remained constant throughout the planning horizon. In the second scenario, after the harvest, the conduction of shooting was considered, which reduced costs in the second rotation and consequently the cost of wood. The economic analysis was performed by determining the following indicators: Net Present Value (NPV), Equivalent Annual Value (EAV) and Benefit - Cost Reason (B/C). Calculated indicators demonstrated the viability of producing charcoal in the two production systems in both scenarios proposed, but kilns-furnace system presented better values. As conclusion, production of charcoal in the evaluated systems were economically viable. Kilns-furnace system was able to generate more profit to charcoal producer.Keywords: Kilns; deterministic analysis; net present value.

scholarly journals A model of a production-repair inventory system with time-varying demand and quality-dependent recovery channels

2021 ◽  
Vol 36 ◽  
pp. 04002
Author(s):  
Ivan Yeo
Keyword(s):  
Raw Materials ◽  
Planning Horizon ◽  
Inventory System ◽  
Raw Material ◽  
Time Varying ◽  
Total Cost ◽  
External Sources ◽  
Varying Demand ◽  
Infinite Planning Horizon ◽  
Better Than

In this paper, we study an inventory system over an infinite planning horizon where a time-varying demand is satisfied by process cycles that consist of a production batch followed by a recovery batch. Our model considers three types of inventory—returned items, serviceable items, and raw material. Furthermore, our model considers two recovery channels—recovery into serviceable items and recovery into raw material. Serviceable items are thus sourced from two inputs—direct recovery and production from raw material. These raw materials can be salvaged from returned items, as well as bought from external sources whenever required. We propose an expression for the unit time total cost as well as a numerical method to find the optimal policy. The properties of the model are studied through numerical experiments, in particular, the feasible situations where hybrid policies are better than pure policies.

Dynamic macro I: Infinite horizon models

2018 ◽  
Author(s):  
Hans Fehr ◽  
Fabian Kindermann
Keyword(s):  
Dynamic Programming ◽  
Infinite Horizon ◽  
Planning Horizon ◽  
Macroeconomic Models ◽  
Total Utility ◽  
The World ◽  
Famous Argument ◽  
Infinite Planning Horizon

In this chapter we apply the principles of dynamic programming to some standard macroeconomic models. For now we stay in the world of infinite horizon models, which are characterized by the fact that they are populated by one or several households with an infinite planning horizon, similar to the previous chapter. There are several justifications for such an assumption. Beneath simplicity, altruism is probably the most famous argument in favour of infinite horizon models. Assume that in a period t there is one generation that dies with certainty after this period.The utility of this generation from its own consumption is u(·). Yet, each generation is altruistic towards its descendants. Consequently, total utility of the generation is Ut = u(·) + βUt+1 where β ≤ 1 can be interpreted as the degree of altruism. All generations together then form a dynasty.

scholarly journals Manufacturing/remanufacturing based supply chain management under advertisements and carbon emission process

2021 ◽  
Author(s):  
Subhash Kumar ◽  
Meenu Sigroha ◽  
Kamal Kumar ◽  
Biswajit Sarkar
Keyword(s):  
Supply Chain ◽  
Graphical Representation ◽  
Consumer Products ◽  
Chain Model ◽  
Total Cost ◽  
Product Demand ◽  
On Demand ◽  
Supply Chain Model ◽  
Demand Rate ◽  
The Cost

One of the most successful ways to get the word out about a product's popularity across all types of customers is through advertising. It has a valuable direct influence on increasing product demand. The supply chain model is developed for manufacturer and retailer, where advertisements are dependent on demand. The advertisement rate has been considered a function that has enhanced at a diminishing rate concerning time, although the growth rate slowed. During the manufacturing cycle, the market's demand is a function of advertisement, and the customer's demand is a linear function of time. The production rate exceeds the demand rate during manufacturing and remanufacturing; shortages are not faced. It involves a manufacturing/remanufacturing process that quickly delivers consumer products and less waste. To keep the environment clean, the cost of carbon emissions is incorporated into the manufacturer's and supplier's holding and degrading costs. The model's primary purpose is to minimize the overall cost of manufacturing and remanufacturing. The overall cost during the manufacturing cycle is higher than that during the remanufacturing cycle. This study confirms that the increasing cost of advertising provides the continuous increasing value of the total cost. A numerical example is provided, graphical representation and sensitivity analysis determine the function's behavior and test the model.

scholarly journals Optimal Replenishment and Lot Sizing Strategy for Inventory Mechanism with Step-Shaped Demand and Backordering

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Lixia Zhang ◽  
Lili Han
Keyword(s):  
Lot Sizing ◽  
Closed Form Solution ◽  
Planning Horizon ◽  
Form Solution ◽  
Inventory Cost ◽  
Second Stage ◽  
Demand Rate ◽  
Two Stages ◽  
The Given ◽  
Infinite Planning Horizon

This paper discusses the inventory mechanism with backordering and with the infinite planning horizon consisting of two stages wherein the demand rate in the first stage is strictly greater than that in the second stage. To minimize the retailer’s inventory cost, we establish a lot sizing decision model. On the basis of the inventory cost analysis, we present a closed-form solution to the model and provide an optimal replenishment and stocking strategy to the retailer. The given numerical experiments show the validity of the model.

scholarly journals On the shortage control in a continuous review (Q, r) inventory policy using αL service-level

2021 ◽  
Vol 55 (5) ◽  
pp. 2785-2806
Author(s):  
Pablo Escalona ◽  
Diego Araya ◽  
Enrique Simpson ◽  
Mario Ramirez ◽  
Raul Stegmaier
Keyword(s):  
Service Level ◽  
Inventory Systems ◽  
Inventory Policy ◽  
Continuous Review ◽  
Arbitrary Time ◽  
Product Availability ◽  
Random Events ◽  
Replenishment Cycle ◽  
The Cost

Popular measures of product availability in inventory systems seek to control different aspects of stock shortages. However, none of them simultaneously control all aspects of shortages, because stock shortages in inventory systems are complex random events. This paper analyzes the performance of αL service measure, defined as the probability that stockouts do not occur during a replenishment cycle, to cover different aspects of stock shortages when used to design an optimal continuous review (Q, r) policy. We show that explicitly controlling the frequency of replenishment cycle stockouts, using the αL service-level, allows to implicitly control the size of the stockouts at an arbitrary time, the size of accumulated backorders at an arbitrary time, and the duration of the replenishment cycle stockouts. However, the cost of controlling the frequency of replenishment cycle stockouts is greater than the cost of controlling the size of stockouts and the duration of the replenishment cycle stockouts.

scholarly journals The Development of Patient Scheduling Groups for an Effective Appointment System

2016 ◽  
Vol 07 (01) ◽  
pp. 43-58 ◽  
Author(s):  
Yu Li Huang
Keyword(s):  
Access To Care ◽  
Treatment Time ◽  
Optimization Technique ◽  
Urgent Care ◽  
Patient Scheduling ◽  
Total Cost ◽  
Patient Type ◽  
Clinic Efficiency ◽  
The Cost ◽  
The Impact

SummaryPatient access to care and long wait times has been identified as major problems in outpatient delivery systems. These aspects impact medical staff productivity, service quality, clinic efficiency, and health-care cost.This study proposed to redesign existing patient types into scheduling groups so that the total cost of clinic flow and scheduling flexibility was minimized. The optimal scheduling group aimed to improve clinic efficiency and accessibility.The proposed approach used the simulation optimization technique and was demonstrated in a Primary Care physician clinic. Patient type included, emergency/urgent care (ER/UC), follow-up (FU), new patient (NP), office visit (OV), physical exam (PE), and well child care (WCC). One scheduling group was designed for this physician. The approach steps were to collect physician treatment time data for each patient type, form the possible scheduling groups, simulate daily clinic flow and patient appointment requests, calculate costs of clinic flow as well as appointment flexibility, and find the scheduling group that minimized the total cost.The cost of clinic flow was minimized at the scheduling group of four, an 8.3% reduction from the group of one. The four groups were: 1. WCC, 2. OV, 3. FU and ER/UC, and 4. PE and NP. The cost of flexibility was always minimized at the group of one. The total cost was minimized at the group of two. WCC was considered separate and the others were grouped together. The total cost reduction was 1.3% from the group of one.This study provided an alternative method of redesigning patient scheduling groups to address the impact on both clinic flow and appointment accessibility. Balance between them ensured the feasibility to the recognized issues of patient service and access to care. The robustness of the proposed method on the changes of clinic conditions was also discussed.

Optimum Seismic Zoning Using An Artificial Neural Network

2016 ◽  
Vol 32 (2) ◽  
pp. 1187-1207 ◽  
Author(s):  
Jaime García-Pérez ◽  
René Riaño
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Seismic Design ◽  
Seismic Zoning ◽  
Present Value ◽  
Total Cost ◽  
Structural Types ◽  
Initial Cost ◽  
Different Types ◽  
Artificial Neural

The Kohonen artificial neural network is employed to divide a region of known seismicity into zones. Optimum boundaries and seismic design coefficients for each zone are determined by computing the expected present value of the total cost, including the initial cost of structures and damages due to earthquakes. The region is discretized into cells containing information on seismicity and the number of structural types. Then regionalization is performed, first without considering jurisdictional limits and later including this restriction. Up to four different types of structures are considered simultaneously in the regionalization. The results are presented in maps showing both zones and corresponding seismic design coefficients.

scholarly journals A MEAN FIELD GAME ANALYSIS OF SIR DYNAMICS WITH VACCINATION

2020 ◽  
pp. 1-18
Author(s):  
Josu Doncel ◽  
Nicolas Gast ◽  
Bruno Gaujal
Keyword(s):  
Mean Field ◽  
Vaccination Strategy ◽  
Game Analysis ◽  
Total Cost ◽  
Mean Field Game ◽  
Vaccination Behavior ◽  
Switching Curve ◽  
The One ◽  
The Cost ◽  
Vaccination Period

We analyze a mean field game model of SIR dynamics (Susceptible, Infected, and Recovered) where players choose when to vaccinate. We show that this game admits a unique mean field equilibrium (MFE) that consists in vaccinating at a maximal rate until a given time and then not vaccinating. The vaccination strategy that minimizes the total cost has the same structure as the MFE. We prove that the vaccination period of the MFE is always smaller than the one minimizing the total cost. This implies that, to encourage optimal vaccination behavior, vaccination should always be subsidized. Finally, we provide numerical experiments to study the convergence of the equilibrium when the system is composed by a finite number of agents ( $N$ ) to the MFE. These experiments show that the convergence rate of the cost is $1/N$ and the convergence of the switching curve is monotone.

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