5,754 research outputs found

    An Epq Model Having Weibull Distribution Deterioration With Exponential Demand and Production With Shortages Under Permissible Delay In Payments

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    In the fundamental production inventory model, in order to solve the economic production quantity (EPQ) we always fix both the demand quantity and the production quantity per day. But, in the real situation, production is usually dependend on demand. This paper derives a production model for the lot-size inventory system with finite production rate, taking into consideration the effect of decay and the condition of permissible delay in payments. Usually no interest is  charged  if the outstanding amount is settled within the permitted fixed settlement period. Therefore, it makes economic sense for the customer to delay the settlement of the replenishment account up to the last moment of the permissible period allowed by the supplier. In this model shortages are permitted and fully backordered . The purpose of this paper is to investigate a computing schema for the EPQ. The model is illustrated with a numerical example. Keywords Economic production quantity, permissible delay, weibull distribution, deterioration

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    An examination of the interfaces between operations and advertising strategies

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    This dissertation is composed of three journals examining the interfaces between the marketing variable of advertising and various aspects of the operations function of the enterprise, namely, (1) production cost [Chapter 2], (2) inventory control [Chapter 3], and (3) service cost learning [Chapter 4]. The first journal identified the optimum advertising allocation policy over time in the presence of a quadratic convex/concave production cost function when the advertising response function is concave using a modified Vidale-Wolfe model. Through analytical proofs and numerical simulations, the results indicated the potential superiority of a pulsation policy in the presence of concavity in the advertising response function only if the production cost function is convex; otherwise, the uniform policy would be optimal. The study is seen as applicable to frequently purchased products in the maturity stage of their life cycles of dominant firms in their industries practicing a zero-inventory policy in a just-in-time environment. The research objective pertaining to the second journal was to study how a firm would adapt optimum ordered quantity/production lot size and optimum advertising expenditure in response to changes in its own parameters, rival\u27s parameters, or parameters that are common to all firms in a symmetric duopoly/oligopoly market. This was accomplished by developing comparative statics (sensitivity analysis) of a symmetric competitive inventory model with advertising-dependent demand based on a market share attraction model. Both optimum advertising expenditure and ordered quantity were found to be sensitive to changes in marketing and operations parameters. The robustness of the symmetric comparative statics was assessed by using data from the brewing industry in the US that represents an asymmetric oligopoly. The empirical analysis indicated that the theoretical results obtained for a symmetric oligopoly remained valid for an oligopoly where each firm had a market share less than 50% and the market shares were further apart from one another. The study is thought to be applicable to low-priced frequently purchased consumer items in competitive mature markets. In the third journal, the original Bass model for new products was modified to incorporate advertising and customers\u27 disadoption to characterize the optimum advertising policy over time for subscriber service innovations where service cost follows a learning curve. After characterizing the optimal policy for a general diffusion model, the results pertaining to a specific diffusion model for which advertising affects the coefficient of innovation were reported. On the empirical side, four alternative diffusion models were estimated and their predictive powers, using a one-step-ahead forecasting procedure, were compared. Empirical research findings suggest that the specific diffusion model considered in this study is not only of theoretical appeal, but also of notable empirical relevance. Taken together, the analytical and empirical findings argue in favor of advertising more heavily during the early stage of the diffusion process of the new subscriber service innovation and including a related message that would predominantly target innovators. Furthermore, it might be inappropriate to model the diffusion of subscriber services as if they were durable goods. The study is thought to be applicable to service innovations that are made available to customers periodically at a subscription fee. Typical examples include, but are not limited to, cable TV, health clubs, pest control, and the internet

    Closed Loop Supply Chain (CLSC): economics, modelling, management and control

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    This article summarizes the papers published in the special issue entitled “Closed Loop Supply Chain (CLSC): Economics, Modelling, Management and Control” in the International Journal of Production Economics. A total of 24 papers, covering an extensive range of topics in the Closed Loop Supply Chain research area, have been included in this special issue. This special issue received a wide and diverse geographical contribution with authors from 16 countries located in 4 continents including America, Asia, Europe, and Africa. Initially, the special issue received 71 research paper submissions and the final selection of 24 papers, which were recommended by at least two reviewers, provide a basis for new research directions in the domain of reverse logistics and Closed Loop Supply Chain management

    Economic evaluation in decision models: a critical review and methodological propositions

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    International audienceDecision models of industrial management articles are often based on an economic criterion to find the proposed solution. They use economic parameters that are generally imported from the firm cost accounting system. When cost information is not adapted to the decision, the obtained solution of the model may be invalid. In this article, we deal with a critical literature review to report the methodological problems encountered in industrial management articles vis-à-vis the used costs. Finally we suggest methodological propositions to be kept in mind by authors when they are using costs in decision models

    An assessment of the Inventory Management Practices of Small and Medium Enterprises (SMEs) in the Northern Region of Ghana

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    The purpose of this study was to assess inventory management practices and its effect on the financial performance of SMEs in the Northern Region of Ghana. The study adopted a descriptive cross-sectional survey research design which allowed the collection of primary quantitative data through structured questionnaires. The target population was 1000 owner/ managers of SMEs. Stratified random sampling technique was used to obtain a sample of 300 SMEs comprising 164 trading 26 manufacturing, 10 hairstyling, 62 dressmaking, and 38 carpentry enterprises. The data was analyzed using both descriptive and inferential statistics. The study revealed that SME financial performance was positively related to efficiency of inventory management (EIM) at 1 per cent significance level. The study concluded that stock management practices have influence on the financial performance of SMEs, hence there was need for SME managers to embrace efficient stock management practices as a strategy to improve their financial performance and survive in the uncertain business environment. Keywords: Inventory Management Practices, Financial Performance, SME

    DETERIORATING ITEM INVENTORY MODEL WITH SHORTAGES, VARIABLE HOLDING COST AND TIME DEPENDENT QUADRATIC DEMAND: AN OPTIMIZATION APPROACH USING WITH AND WITHOUT CONTROLLABLE RATE OF DETERIORATION

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    The purpose of this study is to develop time dependent quadratic demand and variable holding cost, a model of inventory system, for instantaneous deteriorating items with the consideration of the facts that the deteriorating rate can be controlled by using the preservation technology (PT). A solution procedure is presented to find the optimal solution of the cost function. Shortages are allowed and partially backlogged. The backlogging rate is assumed to be dependent on the length of the waiting time for the next replenishment. The longer the waiting time is, the smaller the backlogging rate would be. Results have been validated with relevant examples. Sensitivity analysis is performed to show the effect of changes in the parameters on the optimum solution for both the cases that is with and without using the preservation technology respectively. The analysis of the model shows that the solution of the model is quite stable and can be applied for optimizing the inventory cost of deteriorating items for the business enterprise

    Deterministic and stochastic optimal inventory control with logistic stock-dependent demand rate

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    It has been suggested by many supply chain practitioners that in certain cases inventory can have a stimulating effect on the demand. In mathematical terms this amounts to the demand being a function of the inventory level alone. In this work we propose a logistic growth model for the inventory dependent demand rate and solve first the continuous time deterministic optimal control problem of maximising the present value of the total net profit over an infinite horizon. It is shown that under a strict condition there is a unique optimal stock level which the inventory planner should maintain in order to satisfy demand. The stochastic version of the optimal control problem is considered next. A bang-bang type of optimal control problem is formulated and the associated Hamilton-Jacobi-Bellman equation is solved. The inventory level that signifies a switch in the ordering strategy is worked out in the stochastic case. Copyright © 2014 Inderscience Enterprises Ltd

    Диффузионная аппроксимация процесса производства и сбыта скоропортящейся продукции

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    Найдена плотность распределения количества скоропортящейся продукции при непрерывном производстве и релейном управлении ценой продажи

    Optimal maintenance and replacement decisions under technological change with consideration of spare parts inventories

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    International audienceClassical spare parts inventory models assume that the same vintage of technology will be utilized throughout the planning horizon. However, replacement often occurs in the form of a new technology that renders existing spare parts inventories obsolete. This paper aims to study the impact of spare parts inventory on maintenance and replacement decisions under technological change via a Markov decision process formulation. The replacement decision is complex in that one must decide with which technology available on the market to replace the current asset. Under technological change, the do nothing and repair options have significantly more value as they allow the appearance of even better technologies in the future
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