Search for: inventory-management
Total 23 records
Blood Inventory Management in Hospitals: Considering the Uncertainty
Sharif University of Technology
of Supply, Demand and Blood Transshipment
In recent years there is a growing trend in designing efficient health care systems. The applications of operations research have been instrumental in advancing this growing trend too. The blood management issue has raised concerns for human on the other hand. Blood is one of the vital commodities in the field of health. Despite significant advances in the field of medicine, a suitable replacement for this vital commodity has not been found yet. Collecting and managing the distribution of blood that is discussed in the blood supply chain management, requires careful planning and managing. In this research blood inventory management in hospitals considering the uncertainty of supply, demand...
Article Acta Polytechnica Hungarica ; Volume 12, Issue 4 , 2015 , Pages 221-239 ; 17858860 (ISSN) ; Hajji, A ; Alaei, R ; Behravesh, M ; Sharif University of Technology
Budapest Tech Polytechnical Institution 2015
In this paper, we study the differences between the Centralized and Decentralized approaches in a two-echelon stochastic inventory system under the lost sale policy. We formulate the condition in which the retailer applies (r, Q) inventory policy, and his relation with the upper echelon who acts as a manufacturer. This situation has not been considered in the literature before. The Centralized approach results in optimal solution of the system and the Decentralized one is based on Stackelberg game in which the manufacturer is the leader. The demand arrives according to the stationary Poisson process. We drive the long-run average cost functions, then a set of computational steps are...
Article 7th IEEE International Conference on Industrial Engineering and Applications, ICIEA 2020, 16 April 2020 through 21 April 2020 ; 2020 , Pages 819-826 ; Najafi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2020
Blood availability in hospitals is of high humanitarian importance, thus blood shortage is not desired at all. High wastage rate of blood in hospitals is an important issue, which becomes more important as the standards of health care services becomes higher. In order to address blood shortage and wastage issues in a hospital, this paper develops a new inventory management model as a decision making tool to help making tactical and operational level decisions for a Hospital Blood Bank (HBB) inventory management. These decisions include issuance and ordering policy and the aim of the model is to reduce blood wastage and shortage. For this purpose, a multi period, multi-product inventory...
M.Sc. Thesis Sharif University of Technology ; Kianfar, Farhad
In this thesis, an inventory- location model considering capacity constraints and coverage radius is described in which the capacity is determined based on the maximum accumulation inventory. This model, through minimizing the sum of the fixed facility location costs, transportation costs and safety stock and working inventory costs, concurrently, determines warehouse location, assignment of retailers to warehouses, shipment sizes from the plant to warehouses, working inventory and safety stock levels at the warehouses. This problem can be formulated as a nonlinear mixed integer program in which the objective function is neither concave nor convex. Lagrangian relaxation is incorporated for...
A parameter-tuned genetic algorithm for multi-product economic production quantity model with space constraint, discrete delivery orders and shortages, Article Advances in Engineering Software ; Volume 41, Issue 2 , 2010 , Pages 306-314 ; 09659978 (ISSN) ; Niaki, S.T.A ; Yeganeh, J. A ; Sharif University of Technology
In this paper, a multi-product economic production quantity problem with limited warehouse-space is considered in which the orders are delivered discretely in the form of multiple pallets and the shortages are completely backlogged. We show that the model of the problem is a constrained non-linear integer program and propose a genetic algorithm to solve it. Moreover, design of experiments is employed to calibrate the parameters of the algorithm for different problem sizes. At the end, a numerical example is presented to demonstrate the application of the proposed methodology
Article 2006 IIE Annual Conference and Exposition, Orlando, FL, 20 May 2006 through 24 May 2006 ; 2006 ; Haji, M ; Sharif University of Technology
In this paper we consider a newsvendor problem in which the suppliers offer quantity discounts. We assume that the initial inventory at the beginning of the period is a random variable. This assumption, among other applications, may apply to the case where the decision about the order quantity must be made at a time long before the start of the period and the available inventory may decrease due to several factors, such as deterioration, consumption, etc. up to the start of the period. In this paper, we obtain the optimal order quantity that maximizes the total profit for this model
M.Sc. Thesis Sharif University of Technology ; Hajji, Alireza
This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve...
M.Sc. Thesis Sharif University of Technology ; Houshmand, Mahmoud
Kanban is a tool developed by Toyota Motors Corporation to increase productivity and eliminate waste from their large-scale manufacturing processes. Recently, the system has been used as a tool of choice in Lean software development. Kanban system is the inventory stock control system that triggers the signal for production of product based on actual customer requirement.The present thesis is researching the advantages and disadvantages that Kanban system implementation might cause to the material management processes of a manufacturing facility as well as the theoretical and/or practical reasons behind these results. On an empirical level, the research question is analyzed by participating...
A capacitated multi-product dynamic lot-sizing problem by considering expiration dates; a new approach, Article IFAC Proceedings Volumes (IFAC-PapersOnline) ; 2013 , Pages 152-157 ; 14746670 (ISSN) ; 9783902823359 (ISBN) ; Sazvar, Z ; Baboli, A ; Rekik, Y ; Akbari Jokar, M ; Sharif University of Technology
Although managing and controlling the inventories of perishable products is progressively becoming more important, they are often neglected in lot-sizing research and modeling. This paper studies a new multi-product multi-period dynamic lot sizing problem, where the inventories of products are assumed to be expired at a pre-specified date. For this purpose we assume a retailer that purchases products in large quantities (lot size) from manufacturers, and then sells smaller quantities (or single units) to the consumer. So, the order quantities can be merely an integer multiplier of that product batch size. The retailer also owns a capacitated warehouse. In order to make decisions on "how much...
Blood inventory management in hospitals: considering supply and demand uncertainty and blood transshipment possibility, Article Operations Research for Health Care ; Volume 15 , 2017 , Pages 43-56 ; 22116923 (ISSN) ; Ahmadi, A ; Zolfagharinia, H ; Sharif University of Technology
Despite significant advancements in medicine, human blood is still a scarce resource. Only humans produce it, and there is currently no other product or alternative chemical process that can be used to generate blood. For this reason, blood is a vital commodity in healthcare systems. Since blood is also a perishable product, its inventory management is difficult. The challenge is in holding enough stock to ensure a high level of supply while keeping losses from expiration at a minimum. This research will investigate blood inventory management in a hospital, and develop a mathematical model to manage blood ordering and issuing. This study will account for the fact that blood demand and supply...
Article 36th International Conference on Computers and Industrial Engineering, ICC and IE 2006, Taipei, 20 June 2006 through 23 June 2006 ; 2006 , Pages 3498-3502 ; Haji, R ; Bijari, M ; Sharif University of Technology
The classical single-period problem (SPP) is to find a product's order quantity that maximizes the expected profit in a single period under probabilistic demand. In this paper we consider a SPP model in which a percent of the quantity ordered to the supplier contains defective units and is a random variable with a known distribution function. We assume that the initial inventory at the beginning of the period is a random variable. This assumption, among other applications, may apply to the case where the decision about the order quantity must be made at a time long before the start of the period and the available inventory may decrease stochastically due to several factors, such as...
M.Sc. Thesis Sharif University of Technology ; Kourosh, Eshghi
This research is focused on inventory management of a blood banking system by assuming deterministic demand and supply with the objective function of minimizing the summation of shortage and wastage. In this research, two integer programming models are developed to solve the problem. In the first model, it is assumed that the blood groups are independent, but in the second one, the transactions between different blood groups are allowed, as it is in reality. Then, to be more efficient and practical, a dynamic heuristic algorithm is developed. In addition, we compared the solution of heuristic algorithm with the exact solutions derived from integer programming models. The data used in this...
Ph.D. Dissertation Sharif University of Technology ; Haji, Alireza ; Haji, Rasoul
Although inventory control under discrete demand in dynamic quantities and time intervals are very common in reality, existing literature has largely ignored them. In this thesis, we investigate the inventory control decisions in a two echelon supply chain. The vendor supplies a product to several retailers, buying discrete quantities in pre-determined time intervals. The order quantity and order cycles for each retailer can be different from others. We have developed a new efficient algorithm to find the optimal ordering policy involves the scheduling and the order quantity of vendor to his supplier to minimize his cost function in infinite time horizon. Moreover, we have designed a revenue...
M.Sc. Thesis Sharif University of Technology ; Najafi, Mahdi
major challenges in field of blood supply chain has made it to an important field of study in these era. Due to specific holding environment and limited lifetime, inventory management and inventory planning of blood banks are interesting fields for research. On the other hand, various process in a blood bank make this field very complicated. In this thesis an integer programming model is presented to minimize wastage and shortages in a hospital blood bank (HBB). Elective demands are considered in a finite horizon. This model considers blood compatibility (in case of shortage of same blood group) and crossmathcing a single unit of blood package for more than one patient (demand). Inventory...
M.Sc. Thesis Sharif University of Technology ; Hajji, Alireza
In real production systems, the process is always bound with the production of faulty items which different approaches may be taken toward handling these low quality items according to the nature of the industry and product. Repairing, discarding or selling items in a secondary market are some of the possible actions. We investigated the essentiality of coordinated decision making between a supplier and a buyer in this environment hence developing a model to minimize total costs of two parties with an attitude towards improving quality of production system. In common two layered supply chains, the buyer defines the economic order quantity (EOQ) according to its own decision criteria. These...
Article IFAC Proceedings Volumes (IFAC-PapersOnline) ; 2013 , Pages 1702-1707 ; 14746670 (ISSN) ; 9783902823359 (ISBN) ; Rekik, Y ; Akbari Jokar, M. R ; Baboli, A ; Mirzapour Al E Hashem, S. M. J ; Sharif University of Technology
Inventory management of deteriorating items faces major challenges by uncertain demand, uncertain lead time, perishability, and high customer service level requirements. So, this issue is extremely important in many corporations today. The periodic up-to level policy for deteriorating products under stochastic demand and stochastic lead time is not paid enough attention up to now. In this paper we propose a new approach to study inventory up-to level policy of deteriorating products under normal distributed demand and lead time by considering service level requirements. To model deterioration process, a non-linear increasing holding cost function is considered. After developing the...
Article International Journal of Advanced Manufacturing Technology ; Volume 63, Issue 1-4 , 2012 , Pages 191-200 ; 02683768 (ISSN) ; Bozorgi, B ; Sharif University of Technology
Nowadays, location of distribution centers integrated with inventory or transportation decision play an important role in optimizing supply chain management. Location-inventory models analyze the location and inventory policies in distribution network, simultaneously. Developing location-inventory models under fuzzy environment can enrich the model, and this is our approach in this article. We consider the demand as a fuzzy variable and formulate the problem using credibility theory in order to locate distribution centers (DCs) as well as determining inventory levels in DCs. The derived model belongs to nonlinear mixed integer programming problems, and we presented a genetic algorithm to...
Article Computers and Industrial Engineering ; Volume 123 , 2018 , Pages 82-102 ; 03608352 (ISSN) ; Pasandideh, S. H. R ; Akhavan Niaki, S. T ; Nahavandian, M. H ; Sharif University of Technology
Elsevier Ltd 2018
The Newsboy problem has always been an important issue in inventory management. The multi-product newsboy problem with random yield and budget constraint named as the Gardener Problem is one of the novels and popular extensions of the newsboy problem. Different from the existing studies, this paper presents a multi-product gardener problem with reservation policy. Moreover, a discount rate is offered to those customers who are willing to make reservations. In addition to the demand from the original customers, extra demand is included in the model due to the motivation received by the discount rate. A solution algorithm namely the multi-product gardener problem with reservation policy...
Investigation of Make to Order, Make to Stock and Vendor Managed Inventory Replenishment Strategies in Supply Chain Performance, M.Sc. Thesis Sharif University of Technology ; Hajji, Rasoul
In recent years, numerous companies in various industries apply supply-chain management to improve their market competitiveness. Advances in information technology bring new approaches for managing supply chain activities. Consequently, emphasis on supply-chain coordination has increased in recent years. Vendor managed inventory (VMI) is an important coordination initiative. In VMI, the vendor assumes responsibility for managing inventories at retailers using advanced online messaging and data-retrieval systems. In this dissertation we investigate the effect of VMI on supply chain performance under make-to-order and make-to-stock environment. By using renewal reward theorem, we derive the...
An Application of Deep Reinforcement Learning in Novel Supply Chain Management Approaches for Inventory Control and Management of Perishable Supply Chain Network, M.Sc. Thesis Sharif University of Technology ; Akhavan Niaki, Taghi
This study proposes a deep reinforcement learning approach to solve a perishable inventory allocation problem in a two-echelon supply chain. The inventory allocation problem is studied considering the stochastic nature of demand and supply. The examined supply chain includes two retailers and one distribution center (DC) under a vendor-managed inventory (VMI) system. This research aims to minimize the wastages and shortages occurring at the retailer's sites in the examined supply chain. With regard to continuous action space in the considered inventory allocation problem, the Advantage Actor-Critic algorithm is implemented to solve the problem. Numerical experiments are implemented on...