Wyniki wyszukiwania - BazTech

1

Management system structure vs. Behavior - a supply chain simulation analysis

Pietroń Roman

Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska

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2023

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z. 169

575--597

EN

Purpose: The purpose of this article is to present a research report on a system dynamics simulation modeling and experimenting of bullwhip effect (BWE) to examine effectiveness of some selected inventory control policies with down- and upstream information flow in a Beer Distribution Game (BDG) of a supply chain structure. Design/methodology/approach: The impact of systems’ structures and decision making policies in supply chains or logistics systems are measured and analyzed by an application of systems thinking paradigms and approaches. Particularly, the continuous simulation modeling approach with systems thinking Iceberg model metaphor, allowing to focus on strategic aspects of management with some recommendation to design better structures and decision making policies are taken. For the bullwhip effect analysis of a supply chain example (based on BDG model), a System Dynamics (SD) continuous simulation modeling method with some proposals in order to analyze feedback loop dominance are undertaken to explain supply chain behaviors and to make some sensitivity analysis for decision making (inventory control) policies. Findings: The research findings outline the impact of cause - effect relations, feedback loops polarities, and decision making policies to particular behaviors of the BDG supply chain. Research limitations/implications: Because of complexity of heuristic methods for feedback loop dominance analysis only simple approach was applied (LPD), and some selected scenario for simulation experiments were undertaken resulting in limited conclusions. Practical implications: The conclusions of the research draw some practical recommendations for a design of information sharing system and an effectiveness of some inventory control policies to be applied in supply chains. Social implications: One of the systems thinking elements in practical management is an influence to mental models of managers and decision makers. Managers in supply chain systems particularly need some recommendations to avoid bullwhip effect negative impacts. Additionally, managers and also scholars still call for more research to investigate the design and decision making in supply chains, therefore systems thinking simulation research can bridge the gap between traditional operations research and management with other approaches to provide insight into supply-chain dynamics and deliver impactful suggestions to managers. Originality/value: The paper gives a concept of supply chain dynamic analysis by an application of Iceberg model systems thinking metaphor, feedback loop dominance analysis, and a measurement of some selected inventory control policies effectiveness.

2

Using neural networks to examine trending keywords in Inventory Control

Sadowski Adam, Sadowski Michał, Engelseth Per, Galar Zbigniew, Skowron-Grabowska Beata

Production Engineering Archives

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2023

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Vol. 29, Iss. 4

474-489

EN

Inventory control is one of the key areas of research in logistics. Using the SCOPUS database, we have processed 9,829 articles on inventory control using triangulation of statistical methods and machine learning. We have proven the usefulness of the proposed statistical method and Graph Attention Network (GAT) architecture for determining trend-setting keywords in inventory control research. We have demonstrated the changes in the research conducted between 1950 and 2021 by presenting the evolution of keywords in articles. A novelty of our research is the applied approach to bibliometric analysis using unsupervised deep learning. It allows to identify the keywords that determined the high citation rate of the article. The theoretical framework for the intellectual structure of research proposed in the studies on inventory control is general and can be applied to any area of knowledge.

3

Control of perishable inventory system with uncertain perishability process using neural networks and robust multicriteria optimization

Chołodowicz Ewelina, Orłowski Przemysław

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 3

art. no. e141182

EN

The inventory systems are highly variable and uncertain due to market demand instability, increased environmental impact, and perishability processes. The reduction of waste and minimization of holding and shortage costs are the main topics studied within the inventory management area. The main difficulty is the variability of perishability and other processes that occurred in inventory systems and the solution for a trade-off between sufficient inventory level and waste of products. In this paper, the approach for resolving this trade-off is proposed. The presented approach assumes the application of a state-feedback neural network controller to generate the optimal quantity of orders considering an uncertain deterioration process and the FIFO issuing policy. The development of the control system is based on state-space close loop control along with neural networks. For modelling the perishability process Weibull distribution and FIFO policy are applied. For the optimization of the designed control system, the evolutionary NSGA-II algorithm is used. The robustness of the proposed approach is provided using the minimax decision rule. The worst-case scenario of an uncertain perishability process is considered. For assessing the proposed approach, simulation research is conducted for different variants of controller structure and model parameters. We perform extensive numerical simulations in which the assessment process of obtained solutions is conducted using hyper volume indicator and average absolute deviation between results obtained for the learning and testing set. The results indicate that the proposed approach can significantly improve the performance of the perishable inventory system and provides robustness for the uncertain changes in the perishability process.

4

Satisficing Newsvendor Problem with the Optimism Coefficient

Bieniek Milena

Foundations of Computing and Decision Sciences

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2019

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Vol. 44, No. 3

261--271

EN

In this research note the satisficing newsvendor problem is considered which is defined as the maximization of the probability of exceeding the expected profit multiplied by a positive constant. This constant called optimism coefficient can be chosen by the firm's management either based on their preference or the market conditions. The coefficient indicates whether there is a low or high optimistic decision maker. For the general demand distribution the results are significantly dependent on this coefficient.

5

Wzrost poziomu kontroli zasobów w łańcuchu dostaw potencjalnym źródłem przewagi konkurencyjnej

Bentyn Z.

Gospodarka Materiałowa i Logistyka

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2017

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nr 9

11--17

PL

Poszukiwanie przewagi konkurencyjnej w łańcuchu dostaw motywuje dążenie do wzrostu poziomu kontroli nad znajdującymi się w nim zasobami. Dzięki szybkiemu przepływowi informacji w łańcuchu dostaw i dostępowi do aktualnych danych możliwe jest realizowanie w rzeczywistości założeń koncepcji 7R, traktowanej jako źródło przewagi konkurencyjnej. Celem przeprowadzonego badania było stwierdzenie aktualnego poziomu kontroli zasobów w przedsiębiorstwach oraz jego wpływu na obsługę logistyczną partnerów w łańcuchu dostaw. W wyniku analizy zebranych ankiet ustalono, że niewielka cześć firm jest skłonna dzielić się danymi o posiadanych produktach, stanach magazynowych i innych zasobach. Jednocześnie pozytywnym aspektem badania okazało się dostrzeżenie konieczności benchmarkingu konkurencji w zakresie udostępniania danych.

EN

The search for a competitive advantage in the supply chain motivates striving to increase the level of control of its resources. With the rapid flow of information in the supply chain and access to current data it is possible to implement in reality the concept of 7R, treated as a source of competitive advantage. The aim of the study was to determine the current level of resource control in enterprises and its impact on logistics service supply chain partners. As a result of analysis of the collected survey it found that a small part of the companies are willing to share data held about products, inventory, and other resources. A positive aspect of the study was the perception of the need for benchmarking competition in terms of sharing the data.

6

Optimal ordering quantities for substitutable deteriorating items under joint replenishment

Mishraa V., Shankerb K.

Control and Cybernetics

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2017

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Vol. 46, no. 1

49--70

EN

In this paper, we study an inventory system for two substitutable deteriorating items where when an item is out of stock, the demand for it is met by the other item and any part of demand not met due to unavailability of the other item is lost. The level of inventory of both items deplete due to combined eﬀect of demand fulﬁlment and deterioration. The rates of demand and deterioration are assumed to be deterministic and constant. Items are ordered jointly in each ordering cycle so as to take advantage of joint replenishment. The problem is formulated and a solution procedure is developed to determine the optimal ordering quantities that minimize the total inventory cost. An extensive numerical analysis is carried out to illustrate the parameters of the model. The results indicate that there is substantial improvement in the optimal total cost of the inventory system with substitution over the case without substitution.

7

Sterowanie zapasami, czyli logistyka w branży kwiatowej

Kutyba A., Mikulik J.

Napędy i Sterowanie

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2016

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R. 18, nr 7/8

118--124

PL

W artykule omówiono oraz zaprezentowano dwie klasyczne metody obliczeń w celu analizy materiałów w wybranym przedsiębiorstwie branży kwiatowej. Przeprowadzone analizy pozwoliły na zidentyfikowanie najbardziej istotnych grup asortymentu, co może być podstawą poszukiwania efektywnych narzędzi do zarządzania gospodarką magazynową w branży materiałów ekskluzywnych.

EN

The article discusses and presents two classic calculation methods in order to analyze materials in selected enterprise flower industry. The analyzes allowed to identify the most important groups of assortment, which can be the basis for the search for effective tools for warehouse management in the industry exclusive materials.

8

Sterowanie przepływem towarów w magazynie z wykorzystaniem predyktora Smitha

Chołodowicz E., Orłowski P.

Pomiary Automatyka Robotyka

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2015

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R. 19, nr 3

55--60

PL

W pracy przedstawiono wyniki analizy literaturowej zagadnień związanych ze sterowaniem przepływem materiałów w systemach magazynowych. Na podstawie zaproponowanego dyskretnego, niestacjonarnego, dynamicznego modelu systemu magazynowego ze zmiennym w czasie opóźnieniem stworzono układ sterowania. Przedstawiona koncepcja usprawnienia przepływu towarów wykorzystuje predyktor Smitha z regulatorem PID. Do doboru optymalnych nastaw parametrów układu regulacji zastosowany został algorytm genetyczny. Wskaźnik jakości skonstruowano na bazie: kosztów tworzenia i utrzymania zapasów oraz utraconych zysków, tj. różnic między zapotrzebowaniem a sprzedażą produktów. Wskaźnik ten odzwierciedla, jak system sterowania zamówieniami nadąża za zmieniającymi się potrzebami rynku. Problem ten jest istotny w przedsiębiorstwach produkcyjnych i handlowych, które dążą do minimalizacji czasu realizacji operacji magazynowych i maksymalizacji przepustowości magazynu przy zapewnieniu ciągłości procesu produkcyjnego i sprzedaży. Sformułowano opis matematyczny systemu sterowania oraz problemu optymalizacji. Dokonano jego implementacji stosując algorytm genetyczny. Przedstawione zostały wyniki badań symulacyjnych ukazujące jakość zaproponowanego układu regulacji w środowisku MATLAB/Simulink.

EN

There are a number of theorems and techniques that view inventory management from variant perspectives. The recent progress in research has resulted in innovative and more general techniques that can reduce the supply chain costs fundamentally. Modern inventory control is anchored in vastly advanced and complex models, which require considerable computational efforts. In this paper, we use a mathematical model of a warehouse system with time-varying delivery delay and adapt control system in order to apply it to the problem of goods flow in inventory systems. On the basis of the analysis of the inventory system, we propose a control system, then made its initial verification in the way of computer simulation in MATLAB/Simulink. The concept of improving the flow of materials is based on the structure of the Smith predictor and the PID controller. We perform optimization studies using genetic algorithm. Two quality indicators are subjected to minimization: the total costs of creating and maintaining inventories and differences between the demand and sales of products – the value of providing on whether the storage system keep up with the changing needs of the market (avoid stoppages). In this article, we mainly want to show that our idea of control system is able to achieve a high service level with maintaining a given inventory capacity to avoid redundancy.

9

A periodic inventory control system with adaptive reference stock level for long supply delay

Chołodowicz E., Orłowski P.

Measurement Automation Monitoring

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2015

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Vol. 61, No. 12

568--572

EN

Modern inventory control is anchored in vastly advanced and complex models, which require considerable computational efforts. In this paper, we use a mathematical model of an inventory system with large supply delay and control system in order to optimize goods flow in inventory systems. The paper proposes the use of automatic control systems to control the system for supplementary orders. A discrete-time, dynamic model of the warehouse system is assumed for the analysis. For the given model, two automatic control systems: adaptive and classical non-adaptive periodic inventory systems , are analyzed. The non-adaptive control system is well known in the literature and the second one is its extension. The parameters of the control system are tuned by minimizing the cost function using a genetic algorithm for the assumed scenario for the market demand. Results of numerical simulations of the dynamical system and selected results in the objective space are presented in the paper.

10

Shop floor-level control of manufacturing companies: an interview study in Finland

Tokola H., Järvenpää E., Salonen T., Lanz M., Koho M., Niemi E.

Management and Production Engineering Review

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2015

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Vol. 6, No. 1

51--58

EN

This paper publishes the results of interviews regarding shop-floor-level control of 18 Finnish manufacturing companies. The interviews had 17 open questions relating to demand characteristics, shop floor-level control issues, production flexibility, inventory control, and potential development areas. In order to get insights from the interviews, this paper analyses the answers from the interviews and categorises them into typical answers. The companies that were interviewed are also categorised as small companies with their own end products, subcontractors, or large companies with their own end products, and the emphasis of the analysis is on how companies differ in their shop floor-level control. The results show that different types of companies have different characteristics. Small companies are characterised by constant workflow, seasonal trends in demand, and the use of forecasts. Subcontractors have great daily variation in their demand and processing times. Large companies tend to focus on inventory issues.

11

Dynamiczny dyskretny model systemu magazynowego ze zmiennym w czasie opóźnieniem

Chołodowicz E., Orłowski P.

Logistyka

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2015

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nr 4

28--32

PL

W pracy dokonano analizy literaturowej zagadnień związanych z modelowaniem systemów magazynowych. Następnie zaproponowano dyskretny, dynamiczny model systemu magazynowego z uwzględnieniem opóźnień dostaw, opóźnień dotyczących realizacji zamówienia oraz zmiennych w czasie opóźnień związanych z oczekiwaniem na transport. Wskazano możliwość rozbudowy modelu w celu optymalizacji fizycznego przepływu produktów od producenta na rynek, począwszy od etapu wytwarzania, skończywszy na etapie doręczenia to waru do klientów. Problem ten jest istotny w przedsiębiorstwach produkcyjnych i handlowych, które dążą do minimalizacji czasu realizacji operacji magazynowych i maksymalizacji przepustowości magazynu przy zapewnieniu ciągłości procesu produkcyjnego i sprzedaży. W końcowej części przedstawione są wyniki symulacji komputerowych w środowisku MATLAB/ Simulink.

EN

This work includes analysis of the literature related to issues in the inventory control. On the basis of the analysis of the inventory system, we proposed mathematical model and then made its initial verification in the way of computer simulation in Matlab / Simulink for different scenarios of the market behavior. The simulation was designed to reflect the dynamic phenomena connected with inventory control. This is a suitable foundation to design a stable control strategy which will minimize lost service favorable circumstances (occurring when only a part of the required demand can be satisfied from the stock available at the distribution center. Such a model enables the use of existing synthesis methods of control to avoid demurrages and minimize their effects. A block diagram of an inventory system with delay varying in time is presented in Fig.1. The last part of this paper presents the results of a simulation of the developed model in Fig.2. The graph of this r esponses i s shown i n Figs. 3,5 a nd 6. The paper presents a mathematical model of a warehouse system with time-varying delivery delay. The aim of this work is to adapt and extend the mathematical model and analyze the mechanism of flow of goods associated with inventory management. The work contains an introduction with literature review, simulation and potential future research directions. The first part of the paper is focused on crucial facts about the inventory phenomena over the years. There are a number of theorems and techniques that view inventory management from variant perspectives. Modern enterprises have to make inventory decisions that benefit the entire supply c hain to maximize profit a nd m inimize costs. I n this article, we want to show not only the mathematics associated with proper inventory control but also the mechanism of managing inventory. Striking a balance between operating savings and the costs and capital requirements associated with larger stock is the fundamental problem of inventory policy.

12

Integrated decision on spare parts ordering and equipment maintenance under condition based maintenance strategy

Wang Y., Zhao J., Cheng Z., Yang Z.

Eksploatacja i Niezawodność

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2015

|

Vol. 17, no. 4

591--599

EN

Aiming to optimize the equipment maintenance and the spare parts ordering management jointly, a comprehensive decision model under condition based maintenance (CBM) policy is presented for a single equipment system with continuous and random deterioration. In this model, the equipment deterioration is a continuous Gamma process under a continuous condition monitoring, and the spare parts inventory is controlled by spare parts support probability. Firstly, a spare part support probability model was developed to determine the optimal spare parts stock level S, which is set to meet the requirement of a predetermined stockout probability. Secondly, the equipment replacement and spare parts ordering decision is made to optimize the equipment replacement and spare parts ordering jointly, which is based on the equipment deterioration leveland total operating cost of the system. Thirdly, an integrated decision simulation model is presented for evaluating cost rate, availability and stockout probability. Finally, a numerical example is given to illustrate the performance of this model. The results show that the optimal preventive maintenance threshold obtained from the proposed decision model can satisfy the spare parts support requirements under (S-1, S) inventory control strategy.

PL

Dążąc do jednoczesnej optymalizacji utrzymania ruchu urządzeń i zarządzania zamówieniami części zamiennych, zaproponowano kompleksowy model decyzyjny w ramach strategii utrzymania zależnej od bieżącego stanu technicznego (CBM) przeznaczony dla systemów z pojedynczym urządzeniem i ciągłym oraz losowym zużyciem. W niniejszym modelu, zużycie urządzenia jest ciągłym procesem Gamma z ciągłym monitorowaniem stanu, podczas gdy zapasy części zamiennych są kontrolowane poprzez prawdopodobieństwo wsparcia w zakresie części zamiennych. Po pierwsze, opracowano model prawdopodobieństwa wsparcia w zakresie części zamiennych w celu określenia optymalnego poziomu zapasów części zamiennych S, ustalonej aby spełnić wymogi określonego prawdopodobieństwa braku dostępności. Po drugie, przeprowadzono proces decyzyjny dotyczący wymiany urządzenia i zamawiania części zamiennych w celu jednoczesnej optymalizacji wymiany urządzenia i zamawiania części zamiennych, w oparciu o poziom zużycia urządzenia i całkowity koszt działania systemu. Po trzecie, zaprezentowano zintegrowany symulacyjny model decyzyjny dla oceny poziomu kosztów, dostępności i prawdopodobieństwa jej braku. Zasady niniejszego modelu zilustrowano przykładem numerycznym. Wyniki pokazują, że optymalny próg konserwacji zapobiegawczej uzyskany za pomocą proponowanego modelu decyzyjnego może spełnić wymagania dotyczące części zamiennych w ramach (S-1, S) strategii kontroli zapasów.

13

Adaptive inventory control system for material items with continuous non-stationary demand

Krajčovič M., Plinta D.

Management and Production Engineering Review

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2014

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Vol. 5, No. 1

11--20

EN

This paper describes an algorithm of dynamic inventory control system for large numbers of material items with continuous non-stationary demand. It uses principles of pull inventory control systems, statistical inventory analysis and joint replenishment inventory systems. This algorithm was processed in software module (VBA for Excel) and applied in practice. The target of described algorithm is to keep an optimum inventory level and optimum customer service level in terms of inventory control of items with non-stationary demand.

14

Robust control of the inventory level in warehouses systems

Adamski A., Więcek P.

Logistyka

|

2014

|

nr 6

1379--1389

EN

In the paper the inventory level optimal control problem was presented and solved. The crucial control specification is created by representative prediction of stochastic demand of the goods buyers which creates the reference for adequate control problem formulation. The minimized control performance criterion represents the sum of inventory surplus related holding costs and demand surplus related ordering costs including of delivery time, which directly leads to optimal inventory level optimization. For this problem the stochastic demand prediction problems were solved and verified by adequate models. After that the dedicated dynamic stochastic inventory level control problem with predicted demand treated as references was solved. The original results confirm high practical utility of the proposed approach.

PL

W artykule przedstawiono problem sterowania poziomem zapasów w magazynie. Kluczową specyfikacją dla tego problemu jest reprezentatywna predykcja stochastycznego popytu na towary stanowiąca punkt odniesienia dla sformułowania adekwatnego problemu sterowania. W problemie tym minimalizowane kryterium reprezentuje sumę nadmiernych kosztów związanych z nadmiernym przechowywaniem lub zamawianiem towarów w magazynie co sprowadza się do zapewnienia właściwego z perspektywy popytu poziomu zapasów w magazynie. Dla potrzeb sterowania rozwiązano i zweryfikowano więc najpierw problemy predykcji stochastycznego popytu stosując reprezentatywne modele. Następnie sformułowano i rozwiązano dedykowany dynamiczny problem sterowania zapasami dla którego przewidywany popyt stanowił punkt odniesienia przy optymalizacji. Otrzymane wyniki są oryginalne i potwierdzają dużą użyteczność praktyczną proponowanego podejścia.

15

Decision support of spare parts supply

Kot S., Łodziński J.

Journal of Applied Mathematics and Computational Mechanics

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2013

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Vol. 12, nr 1

69--76

EN

Decisions concerning the way of purchasing spare parts affect the level of the generated costs of collecting and maintaining stocks as well as the level of maintaining the continuity of production in enterprises. To learn about different situations of spare parts purchasing appearing in real economic conditions there has been conducted the simulation of different scenarios of spare parts purchase in connection with the selected factors. In this paper the case study for replacement parts used in a printing house was considered. As a result of the analysis, the best option to purchase replacement parts was indicated.

16

EOQ revisited with sustainability considerations

Arslan M C, Turkay M

Foundations of Computing and Decision Sciences

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2013

|

Vol. 38, No. 4

223--249

EN

The economic order quantity (EOQ) model is a pure economic model in classical inventory control theory. The model is designed to find the order quantity so as to minimize total cost under a deterministic setting. In this study, we revise the standard EOQ model to incorporate sustainability considerations that include environmental and social criteria in addition to the conventional economic considerations. We propose models for a number of different policies and analyze these revised models. Based on our analysis, we show how the triple bottom line considerations of sustainability be appended to traditional cost accounting in EOQ model. We also provide a number of useful insights for decision and policy making practices.

17

Sliding mode control of periodic review perishable inventories with multiple suppliers and transportation losses

Bartoszewicz A., Maciejewski M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2013

|

Vol. 61, nr 4

885--892

EN

The purpose of this paper is to develop robust and computationally efficient supply chain management strategy ensuring fast reaction to the demand variations for periodic review perishable inventory systems. For that purpose, we apply a sliding mode approach and we propose a new discrete time warehouse management strategy. The strategy employs the sliding hyperplane appropriately designed to ensure a dead-beat performance of the closed loop system. Our strategy not only explicitly takes into account decay of goods stored in the warehouse (perishing inventories) but it also accounts for transportation losses which take place on the way from suppliers to the warehouse. The proposed strategy ensures full customers’ demand satisfaction, minimizes the on-hand inventory volume and prevents from exceeding the warehouse capacity. This reflects the need of simultaneous minimization of the lost sales costs and inventory holding costs. Furthermore, the strategy ensures that the ordered quantities of goods are always non-negative and upper bounded. These favourable properties of the proposed strategy are formally stated as a lemma and three theorems and proved in the paper.

18

Zapasy magazynowe w sterowaniu produkcją powtarzalną

Krystek J.

Logistyka

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2012

|

nr 2

PL

W artykule przedstawiono dwie metody międzykomórkowego sterowania produkcją według stanów zapasów magazynowych: maksimum-minimum oraz stanu zamówieniowego. Metody te różnią się sposobem kontroli stanu zapasów magazynowych i sposobem wystawiania zamówień na dostawę nowych elementów. W obu metodach dodatkowo zaimplementowano możliwość generowania zapotrzebowania zgodnie z metodą MRP. Celem było wskazanie sposobu sterowania zapasami produkcji cechującego się niższymi kosztami magazynowania.

EN

The article presents two methods of intracellular production stocks’ controlling: a maximum-minimum and the state ordering. These methods differ from each other in inventory control and the issue of procurement of new items. In both methods, the possibility of generating additional demand in accordance with MRP method is implemented. The aim was to show the production inventory control method which is characterized by a lower cost storage.

19

Sterowanie zapasami w przedsiębiorstwie z uwzględnieniem aspektów ryzyka i niepewności

Tymińska M.

Logistyka

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2012

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nr 6

2--8

PL

Artykuł dotyczy wybranych zagadnień sterowania zapasami w warunkach przedsiębiorstwa produkcyjnego. Całość problematyki podzielona została na trzy części. W pierwszej części przedstawiono kluczowe pojęcia dotyczące zapasów i sterowania ich przepływem w procesie gospodarczym. Druga część obejmuje metodologiczne podstawy konstrukcji modeli deterministycznych oraz probabilistycznych. Modele probabilistyczne uwzględniają aspekty ryzyka i niepewności. Dlatego też w sposób urealniony odzwierciedlają procesy sterowania zapasami. W części trzeciej – empirycznej – zaprezentowano modelowy przykład optymalnego sterowania zapasami w warunkach ograniczonej powierzchni magazynowej.

EN

The article discusses some selected problems in controlling company’s stock of materials. The discussion has been divided in to three parts. Part one introduces the key notions concerning stock and the control of its flows in a production process. Part two presents methodological foundations under lying the construction of deterministic and probabilistic models. Because the probabilistic models allow for risk and uncertainty, they realistically capture the stock control processes. The third part that has an empirical character presents a model example of optimal stock control for the case of a limited storage space.

20

Dead-Beat and reaching law based sliding mode control laws for perishable inventories with transportation losses

Bartoszewicz A., Maciejewski M.

Archives of Control Sciences

|

2012

|

Vol. 22, no. 3

255-272

EN

This paper describes discrete sliding mode (SM) supply management strategies for inventory systems with perishable goods and transportation losses. In the considered systems, the stock used to satisfy the unknown, bounded and time-varying demand is replenished with some delay from a distant supply source. The on-hand stock deterioration during lead-time delay, as well as commodity losses in supply process are explicitly taken into account. Two supply management strategies are proposed. The first one ensures fast reaction to the imposed demand variations, but may result in excessive control signal magnitude at the beginning of the inventory management process. Therefore, in order to conform to supplier limitations we also develop an alternative control strategy based on the concept of the reaching law. That strategy helps reduce the initial supply rate and satisfy the supplier limitations. A number of desirable properties of both proposed strategies are formulated and formally proved. These properties include full customer demand satisfaction and elimination of the risk of exceeding the warehouse capacity.