Browsing by Subject "Supply chains"

Now showing 1 - 7 of 7

Open Access
Auction based scheduling for distributed systems
(International Institute of Informatics and Systemics, 2006) Zarifoğlu, Emrah; Sabuncuoğlu, İhsan
Businesses deal with huge databases over a geographically distributed supply network. When this is combined with scheduling and planning needs, it becomes too difficult to handle. Recently, Fast Consumer Goods sector tends to consolidate their manufacturing facilities on a single supplier serving to a distributed customer network. This decentralized structure causes imperfect information sharing between customers and the supplier. We model this problem as a single machine distributed scheduling problem with job agents representing the customers and the machine agent representing the supplier. We developed Auction Based Algorithm by exploiting the opportunity to use game theoretic approach to solve the problem in the decentralized utility case. Results of our extensive computational experiments indicate that Auction Based Algorithm converges to the upper bound found for the total utility measure.
Open Access
A bilevel uncapacitated location/pricing problem with Hotelling access costs in one-dimensional space
(International Conference on Information Systems, Logistics and Supply Chain, 2016) Arbib, C.; Pınar, Mustafa Ç.; Tonelli, M.
We formulate a spatial pricing problem as bilevel non-capacitated location: a leader first decides which facilities to open and sets service prices taking competing offers into account; then, customers make individual decisions minimizing individual costs that include access charges in the spirit of Hotelling. Both leader and customers are assumed to be risk-neutral. For non-metric costs (i.e., when access costs do not satisfy the triangle inequality), the problem is NP-hard even if facilities can be opened at no fixed cost. We describe an algorithm for solving the Euclidean 1-dimensional case (i.e., with access cost defined by the Euclidean norm on a line) with fixed opening costs and a single competing facility.
Open Access
A class of joint production and transportation planning problems under different delivery policies
(2013) Koc, U.; Toptal, A.; Sabuncuoglu, I.
This paper examines a manufacturer's integrated planning problem for the production and the delivery of a set of orders. The manufacturer in this setting can use two vehicle types for outbound shipments. The first type of vehicle is available in unlimited numbers, but expensive. The second type, which is relatively low in its price, has limited and time-varying availability. We analyze the manufacturer's planning problem under different delivery policies characterized by each of the following: whether orders can be split or not, whether they can be consolidated or not, and whether their sizes are restricted to be in integer multiples of vehicle capacities or not.
Open Access
How supply chain coordination affects the environment: a carbon footprint perspective
(Springer, 2017) Toptal, A.; Çetinkaya, B.
Environmental responsibility has become an important part of doing business. Government regulations and customers’ increased awareness of environmental issues are pushing supply chain entities to reduce the negative influence of their operations on the environment. In today’s world, companies must assume joint responsibility with their suppliers for the environmental impact of their actions. In this paper, we study coordination between a buyer and a vendor under the existence of two emission regulation policies: cap-and-trade and tax. We investigate the impact of decentralized and centralized replenishment decisions on total carbon emissions. The buyer in this system faces a deterministic and constant demand rate for a single product in the infinite horizon. The vendor produces at a finite rate and makes deliveries to the buyer on a lot-for-lot basis. Both the buyer and the vendor aim to minimize their average annual costs resulting from replenishment set-ups and inventory holding. We provide decentralized and centralized models for the buyer and the vendor to determine their ordering/production lot sizes under each policy. We compare the solutions due to independent and joint decision-making both analytically and numerically. Finally, we arrive at coordination mechanisms for this system to increase its profitability. However, we show that even though such coordination mechanisms help the buyer and the vendor decrease their costs without violating emission regulations, the cost minimizing solution may result in increased carbon emission under certain circumstances.
Open Access
Inventory performance with pooling: evidence from mergers and acquisitions
(Elsevier, 2015) Çömez-Dolgan, N.; Tanyeri B.
Theoretical studies show that compared to decentralized inventory management, (i) pooling inventories for different demand sources decreases the optimal safety stock, which in turn decreases inventory costs and (ii) the decrease in stock is related to the correlation between the different demand sources and variabilities of demands. Mergers and acquisitions (M&A) provide a business context to investigate the effects of correlation and variability of the merging firms' demands on potential improvements in inventory performance through inventory pooling. While merging firms may not fully centralize their inventory decisions, the coordination of inventory and supply chain decisions may result in synergies. Using firm-level data for 270 same-industry mergers carried out in U.S. between 1981 and 2009, we find that the inventory turnover of bidder and target firms improves (relative to firms in their industry) following the successful completion of mergers. The improvement in turnover is especially pronounced in deals where the demand of bidder and target firms are negatively correlated prior to the merger. Our results provide novel empirical support for the predictions of theoretical models on inventory economies in M&A.
Open Access
Organization and functioning of liberalized electricity markets: An overview of the Dutch market
(Elsevier Ltd, 2015) Tanrisever, F.; Derinkuyu, K.; Jongen, G.
Abstract In this paper, we examine the organization and the functioning of the Dutch electricity market. First we describe the organization of the Dutch electricity supply chain and the role of the main market participants including the transmission system operator, distribution system operators, program responsible parties and metering companies. We then describe the organization of financial trading and clearing mechanism of electricity through the organized futures exchange (The European Energy Derivatives Exchange), and the spot market (Amsterdam Power Exchange) which includes the day-ahead market and intra-day markets. We also detail the functioning of the imbalance market and reserve capacity management in the Netherlands. Through a set of numerical analysis, we provide an exploratory analysis of the APX day-ahead spot prices and the real-time imbalance prices using electricity price data from 2002 to 2013. We observe the price spikes both in the day-ahead and imbalance markets usually occur around 6-10 AM and 5-7 PM. We also observe that in the imbalance market system overages happen significantly more often than shortages pointing out that the market tends to buy more than what is demanded. This could be explained by the risk attitude of the market participants in the imbalance market.
Open Access
Purchase order finance: a conceptual model with economic insights
(Now Publishers Inc, 2017) Tanrisever, Fehmi; Van Bergen, M.; Reindorp, M.
Purchase Order (PO) finance is a form of financial intermediation which can alleviate capital constraints in certain supply chains. PO finance is typically utilized by small and medium-sized enterprises (SMEs) that operate as importers, exporters, wholesalers, or distributors and have high sales growth. When applicable, PO finance creates value for the supply chain by providing capital that is not available through regular lending channels, due to informational problems. We provide a conceptual model that clarifies the value proposition of PO finance and describe how the transactions are carried out in practice. The conceptual model allows us to highlight the settings where economic conditions will favor the application of PO finance.