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Integrated pricing and inventory control for perishable products, taking into account the lack of backlog and inventory management policy by the seller

Assiddiqi Muktadi Amri, Anantadjaya Samuel Pd, Ahmad Israr, Le Kien, Iswanto A. Heri, Trung Nguyen Dinh, Al-Sudani Ahmed Qassem Ali Sharhan, Huy Dinh Tran Ngoc, Mutlak Dhameer Ali

Foundations of Computing and Decision Sciences

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2022

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Vol. 47, No. 4

371--382

EN

Recently, utilizing appropriate inventory control policy and determining the optimal selling price for various goods has been the main topic of scientific and industrial research. Inventory management policy 1 by the seller is one solution that improves the chain's performance by creating coordination between members of the supply chain. The current study attempts to devise an integrated model of inventory pricing and control under the inventory management policy by the seller for perishable goods with shortages is considered. The purpose of presenting the model is to determine the optimal price, the optimal repayment time, and the order size, in order to maximize the profit. To acquire those optimal values, the profit functions of the buyer and the seller are taken into account. Given the results acquired, it is demonstrated that at any cost, the repayment time is unique and optimal. It is concluded that with the optimal recovery time available, the objective function is a concave function of price, and its optimal value is available. Furthermore, utilizing the inventory management policy by the seller could be a proper means to reducing retailer costs while raising their profit.

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The performance evaluation of the spare parts management: case study

Oumaima Bounou, El Barkany Abdellah, El Biyaali Ahmed

Management and Production Engineering Review

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2019

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Vol. 10, No. 2

37--49

EN

The supply chain of spare parts is the intersection between the supply chain, the after-sales and the maintenance services. Some authors have tried to define improvement paths in terms of models to satisfy the performance criteria. In addition, other authors are directed towards the integration of risk management in the demand forecasting and the stock management (performance evaluation) through probabilistic models. Among these models, the probabilistic graphical models are the most used, for example, Bayesian networks and petri nets. Performance evaluation is done through performance indicators. To measure the appreciation of the supply of the spare parts stock, this paper focuses on the performance evaluation of the system by petri nets. This evaluation will be done through an analytical study. The purpose of this study is to evaluate and analyze the performance of the system by proposed indicators. First, we present a literature review on Petri nets which is the essential tool in our modeling. Secondly, we present in the third section the analytical study of the model based on bath deterministic and stochastic petri networks. Finally, we present an analysis of the proposed model compared to the existing ones.

3

The effect of the safety stock on the occurrence probability of the stock shortage

Korponai J., Tóth Á. B., Illés B.

Management and Production Engineering Review

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2017

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Vol. 8, No. 1

69--77

EN

The objective of the logistics management is to guarantee the stock level required for the adequate handling of production at the lowest possible level of costs and risks. The main purpose of the paper is to present the relations between stock level and risk of shortages. As a result of the research, the introduction of the safety stock is the solution to cover the effects of the uncertain factors in the supply chain. The theoretical approach of the model assumes a deterministic operational environment, in practice, however, there are several unpredictable factors influencing the operation of the production company. By using the periodic and continuous review models, the paper presents the effects of demand changes and stochastic length of replenishment time on the risk of stock availability. We need to quantify a service level which determines the accepted probability of the shortage occurrence.

4

Nurses in Poland — immediate action needed

Haczyński J., Skrzypczak Z., Winter M.

Engineering Management in Production and Services

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2017

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Vol. 9, no. 2

97--104

EN

The aim of the study is to analyse changes in the size of the population of nurses in Poland in the years 2004–2014, considering changes in their employment and the phenomenon of ageing. The analysis is based on the data published by the Central Register of Nurses and Midwives of the Central Statistical Office (GUS) and the Organisation for Economic Co-operation and Development (OECD). Nurses are the largest professional group in the healthcare sector. In 2014, only above 70% of licensed nurses were professionally active. The percentage of employed nurses compared to the number of licensed nurses varied between the lowest ratio of 65.1% in 2005 and the highest ratio of 71.7% in 2012. The latest ratio of 2014 was 70.9%, which was slightly lower compared to the highest ratio in 2012. The average age of a Polish nurse in 2008 was 44.19 years, increasing by about six years to 50.1 within the analysed period. The population of nurses aged above 65 years is almost 4.5 times bigger compared to the youngest age group, which is 21–25 years. Thus, 2/3 of the population of nurses are 41–60 years of age and nearly 85% are over 40. For two years (2000 and 2014), the number of practising nurses per 1000 inhabitants places Poland in the fifth bottom position among the European countries, which shows a significant reduction in patient access to nursing services. In Poland, the profession of nurses has no replacement generation. The article presents the shortage of professionally active nurses in Poland. The existing register of nurses does not contain complete information necessary to evaluate the current situation in Poland. There is a strong need to improve the tracking system of the register of nurses to accurately monitor the number of nurses in Poland The shortage of professionally active nurses and their ageing necessitates immediate action to reduce the shortage by increasing the appeal of the profession among young people and by encouraging nurses to return to the profession. It is also necessary to take action to delay the retirement of those nurses who want to work longer and to use their potential. This is also particularly important because of the gap in experience, which is going to become apparent the nearest future.

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Context of the inventory management expenses in the case of planned shortages

Korponai J., Tóth Á. B., Illés B.

Engineering Management in Production and Services

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2017

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Vol. 9, no. 1

26--35

EN

The main purpose of the paper is to present the relations between the different cost factors of the inventory management systems, and the context between the order quantities and the cost level. The theoretical approach of the model assumes a deterministic operational environment with planned shortages. We make the examination of the contexts by applying the ceteris paribus principle; we change only one cost factor from among the initial conditions at once and examine its effect on the cost level. By using the economic order quantity with the planned shortage model, we can define the optimal order quantity, along which our stock management can be guaranteed by the most favourable cost level. The optimisation of the inventory level and the inventory management expenses together means an important factor in the competitiveness of the company. During the definition of the optimal inventory level of purchased parts, the purchasing and stock holding costs, and also the consequence of shortages play an important role. The presentation of the specific expense factors in each other’s function, and the representation of the onetime order expenses show their proportion compared to each other and the effect of their change on the total cost, and define the opportunities of the optimisation. The significance of the model is that it represents the level line of costs, the movement of the different cost factors in relation to others and their operating mechanism. Thus, it facilitates the representation of costs and the definition of the direction of optimisation.

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Production-inventory Management model for a Weibull deteriorating item with linear demand and shortages

Panda G. C., Sukla P. K.

LogForum

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2013

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Vol. 9, no. 2

111--118

EN

Background: Physical decay or deterioration of goods in stock is an important feature of real inventory systems. Material and methods: In the present paper, we discuss an production inventory model for a Weibull deteriorating item over a finite planning horizon with a linearly time-varying demand rate and a uniform production rate, allowing shortages, which are completely backlogged. Results and conclusions: A production inventory model is developed for a Weibull deteriorating item over a finite planning horizon with a linear time varying demand, finite production rate and shortages. The optimal number of production cycles that minimizes the average system cost is determined.

PL

Wstęp: Fizyczny proces psucia się oraz obniżania wartości zapasów jest ważnym czynnikiem w realnych systemach magazynowych. Material i metody: w pracy poddano dyskusji model Weibulla zarządzania zapasami produkcyjnymi dla skończonego okresu planowania oraz liniowego zmiennego w czasie popytu i określonej partii produkcyjnej, zezwalający na braki, które podlegają uzupełnieniu. Wyniki i wnioski: opracowano model Weibulla zarządzania zapasami produkcyjnymi dla skończonego okresu planowania oraz liniowego zmiennego w czasie popytu, określonej partii produkcyjnej i braków. Określono optymalną ilość cykli produkcyjnych, minimalizujących średnie koszty systemu.

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An EOQ model for time dependent Weibull deterioration with linear demand and shortages

Mishra U, Tripathy C K

LogForum

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2012

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Vol. 8, no. 2

123--136

EN

Background. The study of control and maintenance of production inventories of deteriorating items with and without shortages has grown in its importance recently. The effect of deterioration is very important in many inventory systems. Deterioration is defined as decay or damage such that the item cannot be used for its original purpose. Methods: In this article order level inventory models have been developed for deteriorating items with linear demand and Weibull deterioration. In developing the model we have assumed that the production rate and the demand rate are time dependent. The unit production cost is inversely proportional to demand. Inventory-production system has two parameters Weibull deterioration. Results and conclusions: Two models have been developed considering without shortage cases and with shortage case where the shortages are completely backlogged. The objective of the model is to develop an optimal policy that minimizes the total average cost. Sensitivity analysis has been carried out to show the effect of changes in the parameter on the optimum total average cost.

PL

Wstęp: W ostatnim czasie coraz większego znaczenia nabierają prace badawcze z zakresu kontroli i utrzymania zapasów towarów łatwo psujących się. Problem psucia się towarów jest bardzo istotnym zagadnieniem w wielu systemach magazynowania. Psucie się definiowane jest jako obniżenie jakości lub uszkodzenia, które powodują, że dany towar nie może być użyty zgodnie z jego pierwotnym przeznaczeniem. Metody: W pracy opracowano model oparty na systemie poziomu zamówienia dla towarów łatwo psujących się, charakteryzujących się popytem liniowym oraz uszkodzeń Weibulla. Przy opracowaniu modelu założono, że wielkość produkcji i popytu jest zależną czasu. Jednostkowy koszt produkcji jest odwrotnie proporcjonalny do popytu. System produkcyjno-magazynowy obejmuje dwa parametry uszkodzeń Weibulla. Wyniki i wnioski: Zostały opracowane dwa modele, jeden przeznaczony dla sytuacji bez braków oraz drugi uwzględniający braki, które przyczyniają się do powstawania zaległości. Celem modelu było opracowanie optymalnego sposobu postępowania minimalizującego średni koszt całkowity. Przedstawiono analizę wrażliwości celem wykazania wpływu zmian parametrów na optymalny średni koszt całkowity.