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  • 1
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2002
    In:  Probability in the Engineering and Informational Sciences Vol. 16, No. 4 ( 2002-10), p. 453-469
    In: Probability in the Engineering and Informational Sciences, Cambridge University Press (CUP), Vol. 16, No. 4 ( 2002-10), p. 453-469
    Abstract: We consider the optimal control of two parallel servers in a two-stage tandem queuing system with two flexible servers. New jobs arrive at station 1, after which a series of two operations must be performed before they leave the system. Holding costs are incurred at rate h 1 per unit time for each job at station 1 and at rate h 2 per unit time for each job at station 2. The system is considered under two scenarios; the collaborative case and the noncollaborative case. In the prior, the servers can collaborate to work on the same job, whereas in the latter, each server can work on a unique job although they can work on separate jobs at the same station. We provide simple conditions under which it is optimal to allocate both servers to station 1 or 2 in the collaborative case. In the noncollaborative case, we show that the same condition as in the collaborative case guarantees the existence of an optimal policy that is exhaustive at station 1. However, the condition for exhaustive service at station 2 to be optimal does not carry over. This case is examined via a numerical study.
    Type of Medium: Online Resource
    ISSN: 0269-9648 , 1469-8951
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2002
    detail.hit.zdb_id: 2010880-1
    SSG: 24,1
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  • 2
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1999
    In:  Advances in Applied Probability Vol. 31, No. 4 ( 1999-12), p. 1095-1117
    In: Advances in Applied Probability, Cambridge University Press (CUP), Vol. 31, No. 4 ( 1999-12), p. 1095-1117
    Abstract: We consider the optimal stochastic scheduling of a two-stage tandem queue with two parallel servers. The servers can serve either queue at any point in time and the objective is to minimize the total holding costs incurred until all jobs leave the system. We characterize sufficient and necessary conditions under which it is optimal to allocate both servers to the upstream or downstream queue. We then conduct a numerical study to investigate whether the results shown for the static case also hold for the dynamic case. Finally, we provide a numerical study that explores the benefits of having two flexible parallel servers which can work at either queue versus servers dedicated to each queue. We discuss the results' implications for cross-training workers to perform multiple tasks.
    Type of Medium: Online Resource
    ISSN: 0001-8678 , 1475-6064
    RVK:
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1999
    detail.hit.zdb_id: 1474602-5
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  • 3
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2004
    In:  Advances in Applied Probability Vol. 36, No. 01 ( 2004-03), p. 139-170
    In: Advances in Applied Probability, Cambridge University Press (CUP), Vol. 36, No. 01 ( 2004-03), p. 139-170
    Abstract: We consider the dynamic scheduling of a multiclass queueing system with two servers, one dedicated (server 1) and one flexible (server 2), with no arrivals. Server 1 is dedicated to processing type-1 jobs while server 2 is primarily responsible for processing type-2 jobs but can also aid server 1 with its work. We address when it is optimal for server 2 to aid server 1 with type-1 jobs rather than process type-2 jobs. The objective is to minimize the total holding costs incurred until all jobs in the system are processed and leave the system. We show that the optimal policy can exhibit one of three possible structures: (i) an exhaustive policy for type-2 jobs, (ii) a nonincreasing switching curve in the number of type-1 jobs and (iii) a nondecreasing switching curve in the number of type-1 jobs. We characterize the necessary and sufficient conditions under which each policy will be optimal. We also explore the use of the optimal policy for the problem with no arrivals as a heuristic for the problem with dynamic arrivals.
    Type of Medium: Online Resource
    ISSN: 0001-8678 , 1475-6064
    RVK:
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2004
    detail.hit.zdb_id: 1474602-5
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  • 4
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2004
    In:  Advances in Applied Probability Vol. 36, No. 1 ( 2004-03), p. 139-170
    In: Advances in Applied Probability, Cambridge University Press (CUP), Vol. 36, No. 1 ( 2004-03), p. 139-170
    Abstract: We consider the dynamic scheduling of a multiclass queueing system with two servers, one dedicated (server 1) and one flexible (server 2), with no arrivals. Server 1 is dedicated to processing type-1 jobs while server 2 is primarily responsible for processing type-2 jobs but can also aid server 1 with its work. We address when it is optimal for server 2 to aid server 1 with type-1 jobs rather than process type-2 jobs. The objective is to minimize the total holding costs incurred until all jobs in the system are processed and leave the system. We show that the optimal policy can exhibit one of three possible structures: (i) an exhaustive policy for type-2 jobs, (ii) a nonincreasing switching curve in the number of type-1 jobs and (iii) a nondecreasing switching curve in the number of type-1 jobs. We characterize the necessary and sufficient conditions under which each policy will be optimal. We also explore the use of the optimal policy for the problem with no arrivals as a heuristic for the problem with dynamic arrivals.
    Type of Medium: Online Resource
    ISSN: 0001-8678 , 1475-6064
    RVK:
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2004
    detail.hit.zdb_id: 1474602-5
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  • 5
    Online Resource
    Online Resource
    Institute for Operations Research and the Management Sciences (INFORMS) ; 2019
    In:  Management Science Vol. 65, No. 8 ( 2019-08), p. 3758-3775
    In: Management Science, Institute for Operations Research and the Management Sciences (INFORMS), Vol. 65, No. 8 ( 2019-08), p. 3758-3775
    Abstract: The rising cost of prescription drugs is a concern in the United States. To manage drug costs, insurance companies induce patients to choose less-expensive medications by making them pay higher copayments for more-expensive drugs, especially when multiple drug options are available to treat a condition. However, drug manufacturers have responded by offering copay coupons—coupons intended to be used by those already with prescription drug coverage. Recent empirical work has shown that such coupons significantly increase insurer costs without much benefit to patients, who incur lower out-of-pocket expenses with coupons but may eventually see higher costs passed to them. As a result, there is pressure from the insurance industry and consumer advocacy groups to ban copay coupons. In this paper we analyze how copay coupons affect patients, insurance companies, and drug manufacturers, while addressing the question of whether insurance companies would in fact always benefit from a copay coupon ban. We find that copay coupons tend to benefit drug manufacturers with large profit margins relative to other manufacturers, while generally, but not always, benefiting patients; insurer costs tend to increase with coupons from high-price drug manufacturers and decrease with coupons from low-price manufacturers. Although often helping drug manufacturers and increasing insurer costs, we also identify situations in which copay coupons benefit both patients and insurers. Thus, a blanket ban on copay coupons would not necessarily benefit insurance companies. In addition to the policy implications of our work, we make concrete managerial recommendations to insurers. We discuss how they should set formulary selection policies taking into account the fact that drug manufacturers may offer coupons; and we suggest how they can benefit from subsidizing coupons from drug manufacturers with low-price drugs, or from having drug manufacturers compete on price, to receive a favorable formulary position (i.e., copay). This paper was accepted by Yossi Aviv, operations management.
    Type of Medium: Online Resource
    ISSN: 0025-1909 , 1526-5501
    RVK:
    Language: English
    Publisher: Institute for Operations Research and the Management Sciences (INFORMS)
    Publication Date: 2019
    detail.hit.zdb_id: 206345-1
    detail.hit.zdb_id: 2023019-9
    SSG: 3,2
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  • 6
    Online Resource
    Online Resource
    Institute for Operations Research and the Management Sciences (INFORMS) ; 2022
    In:  Operations Research Vol. 70, No. 6 ( 2022-11), p. 3054-3075
    In: Operations Research, Institute for Operations Research and the Management Sciences (INFORMS), Vol. 70, No. 6 ( 2022-11), p. 3054-3075
    Abstract: A buyer seeking to outsource production may be able to find ways to reduce a potential supplier’s cost, for example, by suggesting improvements to the supplier’s proposed production methods. We study how a buyer could use such cost-reduction investigations by proposing a three-step supplier selection mechanism: First, each of several potential suppliers submits a price bid for a contract. Second, for each potential supplier, the buyer can exert an effort to see if the buyer can identify how the supplier could reduce their cost to perform the contract; the understanding is that if savings are found, they are passed on to the buyer if the supplier is awarded the contract. Third, the buyer awards the contract to whichever supplier has the lowest updated bid (the supplier’s initial bid price minus any cost reduction the buyer is able to identify for that supplier). For this proposed process, we characterize how the buyer’s decision on which suppliers for which to investigate cost reductions in step 2 is affected by the aggressiveness of the suppliers’ bids in step 1. We show that, even if the buyer does not share the cost savings the buyer identifies in step 2, ex ante symmetric suppliers are actually better off (ex ante) in our proposed mechanism than in a setting without such cost-reduction investigations, resulting in a win–win for the buyer and suppliers. When suppliers’ cost and cost-reduction distributions become very heterogeneous, the win–win situation may no longer hold, but every supplier still has an incentive to allow the buyer to investigate them in step 2 because it increases their chance of winning the contract. Using an optimal mechanism analysis, our numerical studies show that our proposed bid–investigate–award mechanism helps the buyer achieve near-optimal performance despite its simplicity. Supplemental Material: The online appendix is available at https://doi.org/10.1287/opre.2022.2349 .
    Type of Medium: Online Resource
    ISSN: 0030-364X , 1526-5463
    RVK:
    Language: English
    Publisher: Institute for Operations Research and the Management Sciences (INFORMS)
    Publication Date: 2022
    detail.hit.zdb_id: 2019440-7
    detail.hit.zdb_id: 123389-0
    SSG: 3,2
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  • 7
    Online Resource
    Online Resource
    Institute for Operations Research and the Management Sciences (INFORMS) ; 2019
    In:  Mathematics of Operations Research Vol. 44, No. 2 ( 2019-05), p. 601-631
    In: Mathematics of Operations Research, Institute for Operations Research and the Management Sciences (INFORMS), Vol. 44, No. 2 ( 2019-05), p. 601-631
    Abstract: We study a multiperiod network revenue management problem where a seller sells multiple products made from multiple resources with finite capacity in an environment where the underlying demand function is a priori unknown (in the nonparametric sense). The objective of the seller is to simultaneously learn the unknown demand function and dynamically price the products to minimize the expected revenue loss. For the problem where the number of selling periods and initial capacity are scaled by [Formula: see text], it is known that the expected revenue loss of any non-anticipating pricing policy is [Formula: see text] . However, there is a considerable gap between this theoretical lower bound and the performance bound of the best-known heuristic control in the literature. In this paper, we propose a nonparametric self-adjusting control and show that its expected revenue loss is [Formula: see text] for any arbitrarily small [Formula: see text] , provided that the underlying demand function is sufficiently smooth. This is the tightest bound of its kind for the problem setting that we consider in this paper, and it significantly improves the performance bound of existing heuristic controls in the literature. In addition, our intermediate results on the large deviation bounds for spline estimation and nonparametric stability analysis of constrained optimization are of independent interest and are potentially useful for other applications. The online appendix is available at https://doi.org/10.1287/moor.2018.0937 .
    Type of Medium: Online Resource
    ISSN: 0364-765X , 1526-5471
    Language: English
    Publisher: Institute for Operations Research and the Management Sciences (INFORMS)
    Publication Date: 2019
    detail.hit.zdb_id: 2004273-5
    detail.hit.zdb_id: 195683-8
    SSG: 3,2
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  • 8
    Online Resource
    Online Resource
    Institute for Operations Research and the Management Sciences (INFORMS) ; 2007
    In:  Management Science Vol. 53, No. 8 ( 2007-08), p. 1289-1302
    In: Management Science, Institute for Operations Research and the Management Sciences (INFORMS), Vol. 53, No. 8 ( 2007-08), p. 1289-1302
    Abstract: We consider a two-location production/inventory model where each location makes production decisions and is subject to uncertain capacity. Each location optimizes its own profits. Transshipment (at a cost) is allowed from one location to another. We focus on the question of whether one can globally set a pair of coordinating transshipment prices, i.e., payments that each party has to make to the other for the transshipped goods, that induce the local decision makers to make inventory and transshipment decisions that are globally optimal. A recent paper suggests, for a special case of our model, that there always exists a unique pair of coordinating transshipment prices. We demonstrate through a counterexample that this statement is not correct and derive sufficient and necessary conditions under which it would hold. We show that in some conditions, coordinating prices may exist for only a narrow range of problem parameters and explore conditions when this can happen. Finally, we study the effects of demand and capacity variability on the magnitude of coordinating transshipment prices.
    Type of Medium: Online Resource
    ISSN: 0025-1909 , 1526-5501
    RVK:
    Language: English
    Publisher: Institute for Operations Research and the Management Sciences (INFORMS)
    Publication Date: 2007
    detail.hit.zdb_id: 206345-1
    detail.hit.zdb_id: 2023019-9
    SSG: 3,2
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  • 9
    Online Resource
    Online Resource
    Institute for Operations Research and the Management Sciences (INFORMS) ; 2011
    In:  Operations Research Vol. 59, No. 4 ( 2011-08), p. 914-928
    In: Operations Research, Institute for Operations Research and the Management Sciences (INFORMS), Vol. 59, No. 4 ( 2011-08), p. 914-928
    Abstract: We study a supply chain consisting of one supplier and one OEM (original equipment manufacturer). The OEM faces stochastic demand for a final product that requires assembly of two major components, one of which is procured exclusively from the supplier. In the absence of competition, the supplier is able to make a take-it-or-leave-it offer to the OEM in the form of a menu of price-quantity contracts. The OEM possesses private information across two dimensions: (1) demand forecasts about the final product, and (2) production cost of the in-house component. Both pieces of information are relevant to the total supply chain profit, thus affecting the supplier's optimal offer. By initially assuming an exogenous information structure, we characterize the supplier's optimal contract menu for a simple case and demonstrate that more dimensions of asymmetric information are not always preferable for the OEM but could be beneficial for the supply chain. We subsequently examine whether this preference for one less dimension of private information implies disclosure of private information to the supplier when the information structure is endogenized. Our results indicate that if OEMs that are indifferent between disclosing and keeping information private choose to disclose it, disclosure of any verifiable information from all OEMs is always an equilibrium, whereas nondisclosure might fail to be an equilibrium. We also consider the possibility of the OEM and the supplier contracting at the ex-ante stage, i.e., before the OEM observes his private information. When both dimensions of the OEM's private information are verifiable and the cost of disclosing information is small enough, an ex-ante agreement on information disclosure is always possible; otherwise its feasibility depends on the problem parameters.
    Type of Medium: Online Resource
    ISSN: 0030-364X , 1526-5463
    RVK:
    Language: English
    Publisher: Institute for Operations Research and the Management Sciences (INFORMS)
    Publication Date: 2011
    detail.hit.zdb_id: 2019440-7
    detail.hit.zdb_id: 123389-0
    SSG: 3,2
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  • 10
    Online Resource
    Online Resource
    Institute for Operations Research and the Management Sciences (INFORMS) ; 1994
    In:  Operations Research Vol. 42, No. 6 ( 1994-12), p. 1162-1171
    In: Operations Research, Institute for Operations Research and the Management Sciences (INFORMS), Vol. 42, No. 6 ( 1994-12), p. 1162-1171
    Abstract: In a recent paper, L. M. Wein (1992) addressed the problem of scheduling a network of queues. Given a multistation, multiclass queueing network, the problem involves deciding when to release a job to the network as well as how to sequence jobs at each machine in the network to meet a desired throughput level. By approximating this problem by a control problem involving Brownian motion, Wein derived effective heuristics, which easily outperformed traditional work release and sequencing rules. However, Wein's work release rules are complex and his sequencing rules are dynamic. In this paper, we test the performance of a simpler work release policy based on CONWIP (constant work-in-process) in conjunction with static sequencing rules. The results of our simulation study indicate that this simple work release rule can be effective.
    Type of Medium: Online Resource
    ISSN: 0030-364X , 1526-5463
    RVK:
    Language: English
    Publisher: Institute for Operations Research and the Management Sciences (INFORMS)
    Publication Date: 1994
    detail.hit.zdb_id: 2019440-7
    detail.hit.zdb_id: 123389-0
    SSG: 3,2
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