A Reply to Ponte et al (2016) Supply Chain Collaboration: Some Comments on the Nucleolus of the Beer Game

Purpose: The aim of the paper is to pick up the result of a previously published paper in order to deepen the discussion. We analyze the solution against the background of some well-known concepts and we introduce a newer one. In doing so we would like to inspire the further discussion of supply chain collaboration. Design/methodology/approach: Based on game theoretical knowledge we present and compare seven properties of fair profit sharing. Findings: We show that the nucleolus is a core-solution, which does not fulfil aggregate monotonicity. In contrast the Shapley value is an aggregate monotonic solution but does not belong to the core of every cooperative game. Moreover, we present the Lorenz dominance as an additional fairness criteria. Originality/value: We discuss the very involved procedure of establishing lexicographic orders of excess vectors for games with many players.Peer Reviewe

Improving joint revenues through partner sharing of flight leg opportunity costs

Thesis (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 125-128).Airlines participating in alliances offer code share itineraries (with flight segments operated by different partners) to expand the range of origin-destination combinations offered to passengers, thus increasing market share at little cost. The presence of code share flights presents a problem for airline revenue management (RM) systems, which aim to maximize revenues in an airline's network by determining which booking requests are accepted. Because partners do not jointly optimize revenues on code share flights, alliance revenue gains from implementing advanced RM methods may be lower than an individual airline's gains. This thesis examines seat availability control methods that alliance partners can adopt to improve the total revenues of the alliance without formally merging. Partners share information about the opportunity costs to their network, called "bid prices", of selling a seat on their own flight leg, a mechanism termed bid price sharing (BPS). Results show that BPS methods often improve revenues and work best for networks with certain characteristics and partners with similar RM systems that exchange recently calculated bid prices as often as possible. Gains are typically only achieved if both alliance partners participate in the code share availability decision (called dual control) rather than one partner only, but implementation of dual control is more difficult for airlines in practice. In the best case scenario, gains of up to .40% where achieved, which can translate into $120 million per year for the largest airlines. In our simulations, BPS with dual control and frequent bid price calculation and exchange was the only method that produced consistently positive revenue gains in all the scenarios tested. Therefore, alliance airlines must consider the trade off between revenue gains and implementation difficulties of more frequent bid price exchange or dual control.by Alyona Michel.S.M.in Transportatio

Kerjasama Pemanfaatan Prasarana dan Sarana Terminal Dalam Upaya Mengurangi Waktu Pelayanan Kapal Di Terminal Peti Kemas

Berth allocation problem merupakan permasalahan yang kompleks karena adanya faktor ketidakpastian (uncertainty) yang menyebabkan kedatangan kapal di pelabuhan sulit untuk diprediksi dan seringkali terlambat dari jadwal yang telah ditentukan. Keterlambatan kedatangan kapal mengakibatkan sumber daya yang sudah dipersiapkan menjadi menganggur. Operator terminal harus menyusun jadwal ulang untuk mengalokasikan kapal yang mengalami keterlambatan. Apabila sumber daya tidak tersedia maka kapal harus menunggu (antri) sampai dermaga tersedia. Berth allocation tidak semata-mata hanya mengalokasikan kapal ke dermaga, tetapi juga mengalokasikan sumber daya lainnya seperti crane, yard, RTG, dan alat transportasi. Untuk pelabuhan yang memiliki lebih dari satu terminal yang dioperasikan oleh operator berbeda dimana setiap terminal menerapkan sistem windows slot, setiap terminal memiliki potensi pada saat yang sama di satu terminal terjadi kekurangan (shortage) dan terminal lain terjadi kelebihan (surplus) sumber daya. Oleh karena itu dibutuhkan strategi untuk menghadapi kondisi tersebut. Salah satu strategi yang diusulkan adalah dengan melakukan kerja sama atau kolaborasi. Pada kondisi eksisting shipping lines yang memiliki windows slot di satu terminal hanya bisa berthing dan bongkar muat menggunakan sumber daya yang dimiliki terminal tersebut. Apabila seluruh dermaga dan sumber daya di terminal tersebut sedang digunakan, maka kapal yang datang harus menunggu dan antri sampai dermaga tersedia, meskipun di terminal lain terdapat dermaga yang tidak digunakan, demikian juga sebaliknya. Strategi kolaborasi memungkinkan setiap kapal bisa berthing di setiap terminal meskipun kapal tersebut memiliki windows di terminal yang berbeda. Dalam penelitian ini dikembangkan model simultaneous berth allocation problem dengan strategi kolaborasi. Karena sistem yang dimodelkan relatif kompleks dan mengandung unsur ketidakpastian maka dalam studi ini digunakan permodelan discrete event simulation. Beberapa skenario diusulkan dan dipilih skenario terbaik yang terbaik. Skenario ditentukan berdasarkan kombinasi empat faktor, yaitu service order, berth-yard, crane dan strategy, dimana setiap faktor memiliki 2 level. Dengan menggunakan konsep full factorial design (2k factorial design) dihasilkan sebanyak 16 skenario. Skenario pertama merupakan kondisi eksisting yang dijadikan sebagai baseline untuk menentukan skenario terbaik yang ditentukan berdasarkan dua respon, yaitu waktu (waiting time, handling time, turnaround time) dan jumlah kapal yang menunggu. Berdasarkan hasil simulasi diperoleh skenario terbaik dengan kombinasi service order secara menggunakan sistem prioritas, berth-yard secara independent, alokasi crane secara fixed, dan strategi yang digunakan adalah kolaborasi. Hasil simulasi menunjukkan bahwa kolaborasi dapat menciptakan keseimbangan operasi di terminal dengan load tinggi dan terminal dengan load rendah. Waiting time dan turnaround time di terminal dengan load tinggi menjadi lebih pendek, sedangkan di terminal dengan load rendah menjadi lebih panjang. Strategi kolaborasi dapat mengurangi jumlah kapal menunggu hingga 43.82 % per tahun, menurunkan waiting time sebesar 46.82%, dan menurunkan turnaround time sebesar 10.60% per kapal per kedatangan. Kolaborasi menimbulkan terjadinya shifting kapal dan container dari terminal load tinggi ke terminal load rendah. Pergeseran kapal dan container menyebabkan terjadinya perubahan performa finansial bagi kedua terminal. Untuk menghindarkan terjadinya kerugian bagi salah satu pihak, maka dibuat skema profit sharing atau profit redistribution. ================================================================================================================== Berth allocation problem is a complex problem because of the uncertainty factor that causes the arrival of the ship in the port is difficult to predict and often the arrival of the ship is late from the schedule.The ship's delays result in the resources already allocated for the vessel cannot be utilized. If the ship comes out of schedule, the terminal operator should re-schedule the ship, so the ship must wait until the berth is available. Berth allocation does not solely allocate ships to berth, but also allocates other resources such as cranes, yards, RTG and transportation. For ports that have more than one terminal operated by different operators and each terminal implements a windows system, each terminal has the potential at the same time in one terminal to have a shortage of resources and another terminal overload (surplus). Strategy is needed to deal with the condition. One of the proposed strategies is to collaborate between terminals. In the existing condition of shipping lines that have windows in one terminal can only berthing, loading and unloading using resources in the terminal. If all the resources at the terminal are in use, the arriving vessel will have to wait and queue until the berth is available, even in other terminals there are unused docks, and vice versa. The collaboration strategy allows each ship to berthing in every terminal even though it has windows in different terminals. The allocation of berth, crane and yard is an interrelated process so that the allocation cannot be done partially or gradually (multiphase). Partial and multiphase solutions are generally accomplished by completing the berth allocation in the first phase, and continued with the crane or yard allocation in the next phase. Multiphase solutions have drawbacks because they do not always result in optimal completion. The allocation of berth, crane and yard is an interrelated process so that the allocation cannot be done partially or gradually (multiphase). Partial and multiphase solutions are generally accomplished by completing the berth allocation in the first phase, and continued with the crane or yard allocation in the next phase. Multiphase solutions have drawbacks because they do not always result in optimal completion. The optimal crane allocation in the second phase can change the optimal berth allocation in the first phase. This research develops simultaneous berth allocation problem model with collaboration strategy. Because the modeled system is relatively complex and contains uncertainty factor, this study uses discrete event simulation model. In this simulation, 16 scenarios were obtained using the full factorial design concept (2k factorial design) from a combination of four factors: service order, berth-yard, crane and strategy, each factor has two levels. The first scenario is an existing condition that is used as a baseline to determine the best scenario. The best scenario is determined based on two responses, namely time (waiting time, handling time, turnaround time) and the number of ships waiting. Simulation results show that collaboration can create a balance of operations in terminals with high load and terminals with low load. Waiting time and turnaround time in terminals with high load becomes shorter, while in terminals with low load becomes longer. The collaboration strategy can reduce the number of ships waiting up to 43.82% per year, while the waiting time is reduced by 46.82%. Turnaround time decreased by 10.60% per ship per arrival. Collaboration creates unavoidable consequences of shifting ships and containers from high load terminals to low load terminals. Shifting vessels and containers leads to changes in financial performance for both terminals. In this research also created profit sharing scheme or profit redistribution to avoid losses for either party

Network Revenue Management under Competition within Strategic Airline Alliances

Airlines often cooperate with partners within strategic alliances to offer their customers itineraries beyond their own networks. However, despite the cooperation, the alliance members often remain competitors on other routes and compete for customers. This thesis takes into account the competition between two alliance partners and models it in a linear program. An algorithm is developed to compute optimal capacity allocations in pure Nash equilibria based on the model. For cases, in which a Nash equilibrium does not exist or cannot be found within a pre-defined time, a heuristic approach is described to compute an approximate Nash equilibrium. Computational studies show the applicability of the approaches in real-sized airline networks. Finally, suggestions for future research are made