Production and Operations Management最新文献

{"title":"Increasing the supply of health products in underserved regions","authors":"Burak Kazaz, Scott Webster, Prashant Yadav","doi":"10.1111/poms.14085","DOIUrl":"https://doi.org/10.1111/poms.14085","url":null,"abstract":"Abstract We study mechanisms that encourage manufacturers of health products to build production and distribution capacity. This is important for low‐ and middle‐income country (LMIC) markets where ability to pay is lower and demand risks are greater. Development finance institutions and philanthropies are beginning to utilize new instruments to incentivize manufacturers to build production/distribution capacity for LMIC markets. The goal of this paper is to understand the effectiveness of such mechanisms in different settings. We examine four instruments: (1) subsidy proportional to unit sales (sales subsidy), (2) subsidy proportional to unit capacity (variable‐capacity subsidy), (3) subsidy proportional to total capacity investment (total‐capacity subsidy), (4) a minimum volume guarantee. We analyze incentivized capacity as a function of social‐investor budget for each instrument. We show how our framework can be used to identify a social investor's preferred instrument given relevant parameter estimates, and we provide insight into the type of settings where a particular instrument dominates. A sales subsidy dominates when ability to pay is very low; a total‐capacity subsidy dominates when ability to pay is low. Outside of these settings, instrument preference is nuanced, though a sales subsidy is dominated by at least one other instrument. When ability to pay is moderate, a variable‐capacity subsidy tends to be preferred under high variable‐capacity cost and high budget, a volume guarantee tends to be preferred under low variable‐capacity cost and high budget, and a total‐capacity subsidy tends to be preferred under low budget. This article is protected by copyright. All rights reserved","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135646116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A boosting policy to optimize user forum performance: Model and validation","authors":"Radha Mookerjee, Wael Jabr, Harpreet Singh","doi":"10.1111/poms.14066","DOIUrl":"https://doi.org/10.1111/poms.14066","url":null,"abstract":"Abstract Near‐constant Internet access through desktop or mobile devices has turned self‐service support forums into the first port of call for users seeking to troubleshoot product or service issues. The firms providing these products and services also benefit from this trend since it reduces user support costs by diverting service requests away from costlier support channels, such as help desks. For the continued success of such a forum, however, the managing entity must ensure that users receive timely solutions to their inquiries quickly and regularly. We develop a mathematical model of a user forum's operations to obtain a “white box” view of a user forum and reveal the support system's dynamics. Then, using a large and comprehensive dataset of questions and answers from Apple's iPhone user forum, we empirically estimate the forum's performance to validate the predictions of the mathematical model. Our results demonstrate that the predictions closely match the forum's actual performance, with an error of less than 10%. We then propose and analyze an optimal threshold policy that boosts a thread to rekindle user interest and demonstrate the benefit of our intervention policy in managing the iPhone forum.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135131289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spread and control of medical rumors in a social network: A generalized diffusion model with a highly asymmetric network structure","authors":"Chen‐Nan Liao, Ying‐Ju Chen, Vincent (Pei‐Ming) Chen","doi":"10.1111/poms.14057","DOIUrl":"https://doi.org/10.1111/poms.14057","url":null,"abstract":"Abstract Medical rumors have become a threat to modern society. To study the spread and control of rumors, nonlinear differential equations modeling with the well‐mixed assumption is commonly used. However, this approach ignores the underlying network structure which plays an important role in information spreading. We establish a generalized differential equations model to study the spread and control of medical rumors in a highly asymmetric social network. In our model, each node represents a group of people and a “weighted” and “directed” network describes the communications between these nodes. This network can be generated from real‐world data by community detection algorithms. We provide methods to numerically calculate the final size of a rumor in each node and its derivatives with respect to each parameter. With these methods, if the government has resources to influence the parameters subject to certain constraints or cost functions, one can obtain the optimal resources allocation easily through nonlinear programming algorithms. We show that the implications on the government's resources allocation from the well‐mixed special case in the literature or conventional wisdom may become inapplicable in the general situation. Therefore, the underlying network should not be ignored. Because the final size of a medical rumor is not always the best measure of its damage, we extend our results to a wide class of objectives and show that different objectives result in very different implications. While the lack of a rule of thumb may sound negative, our flexible framework provides a powerful workhorse for interested parties to work out the details in their specific situations. Finally, we provide a sufficient condition for no outbreak of rumors. This condition can serve as a heuristic that a government with abundant resources can use to prevent the outbreak of rumors.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135131461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal robust inventory management with volume flexibility: Matching capacity and demand with the lookahead peak‐shaving policy^a","authors":"Joren Gijsbrechts, Christina Imdahl, Robert N. Boute, Jan A. Van Mieghem","doi":"10.1111/poms.14069","DOIUrl":"https://doi.org/10.1111/poms.14069","url":null,"abstract":"Abstract We study inventory control with volume flexibility: A firm can replenish using period‐dependent base capacity at regular sourcing costs and access additional supply at a premium. The optimal replenishment policy is characterized by two period‐dependent base‐stock levels but determining their values is not trivial, especially for nonstationary and correlated demand. We propose the Lookahead Peak‐Shaving policy that anticipates and peak shaves orders from future peak‐demand periods to the current period, thereby matching capacity and demand. Peak shaving anticipates future order peaks and partially shifts them forward. This contrasts with conventional smoothing, which recovers the inventory deficit resulting from demand peaks by increasing later orders. Our contribution is threefold. First, we use a novel iterative approach to prove the robust optimality of the Lookahead Peak‐Shaving policy. Second, we provide explicit expressions of the period‐dependent base‐stock levels and analyze the amount of peak shaving. Finally, we demonstrate how our policy outperforms other heuristics in stochastic systems. Most cost savings occur when demand is nonstationary and negatively correlated, and base capacities fluctuate around the mean demand. Our insights apply to several practical settings, including production systems with overtime, sourcing from multiple capacitated suppliers, or transportation planning with a spot market. Applying our model to data from a manufacturer reduces inventory and sourcing costs by 6.7%, compared to the manufacturer's policy without peak shaving.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135131455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Risk‐sensitive markov decision processes with long‐run CVaR criterion","authors":"Li Xia, Luyao Zhang, Peter W. Glynn","doi":"10.1111/poms.14077","DOIUrl":"https://doi.org/10.1111/poms.14077","url":null,"abstract":"Abstract CVaR (Conditional value at risk) is a risk metric widely used in finance. However, dynamically optimizing CVaR is difficult, because it is not a standard Markov decision process (MDP) and the principle of dynamic programming fails. In this paper, we study the infinite‐horizon discrete‐time MDP with a long‐run CVaR criterion, from the view of sensitivity‐based optimization. By introducing a pseudo‐CVaR metric, we reformulate the problem as a bilevel MDP model and derive a CVaR difference formula that quantifies the difference of long‐run CVaR under any two policies. The optimality of deterministic policies is derived. We obtain a so‐called Bellman local optimality equation for CVaR, which is a necessary and sufficient condition for locally optimal policies and only necessary for globally optimal policies. A CVaR derivative formula is also derived for providing more sensitivity information. Then we develop a policy iteration type algorithm to efficiently optimize CVaR, which is shown to converge to a local optimum in mixed policy space. Furthermore, based on the sensitivity analysis of our bilevel MDP formulation and critical points, we develop a globally optimal algorithm. The piecewise linearity and segment convexity of the optimal pseudo‐CVaR function are also established. Our main results and algorithms are further extended to optimize the mean and CVaR simultaneously. Finally, we conduct numerical experiments relating to portfolio management to demonstrate the main results. Our work sheds light on dynamically optimizing CVaR from a sensitivity viewpoint.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135477762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of trauma on internal integration: An approach‐avoidance analysis in disaster relief operations","authors":"Llord Brooks, Iana Shaheen, David Dobrzykowski","doi":"10.1111/poms.14081","DOIUrl":"https://doi.org/10.1111/poms.14081","url":null,"abstract":"Abstract Disaster relief workers face unique factors in their operating environments that can inhibit internal integration. For example, disaster relief often involves exposure to traumatic events affecting relief workers’ commitment to cooperation and the organization. As such, disaster relief organizations dedicate substantial amounts of scarce resources to support workers exposed to trauma. Unfortunately, contradictory views exist in the literature on how trauma exposure affects commitment and integrative behaviors and how supervisor support influences these relationships. Based on the approach‐avoidance coping theory, we test whether trauma exposure has positive or negative effects. We test our hypotheses on data from 300 disaster relief workers collected using a 2 × 3 factorial scenario‐based experiment. We find that trauma exposure evokes avoidance coping behaviors, which decrease individuals’ cooperative disposition and approach coping behaviors, which motivate organizational commitment. Next, we show that both forms of commitment have a nonlinear convex relationship with internal integration and mediate the relationship between trauma exposure and internal integration. Finally, we find that supervisor support amplifies these relationships. When exposed to trauma, supervisor approach and avoidance orientations provide higher internal integration levels than subjects exposed to no supervisor support. These findings extend the literature on disaster relief management, integration, and support, guiding decision‐making regarding support investments in disaster relief organizations. This article is protected by copyright. All rights reserved","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135536286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equitable anesthesiologist scheduling under demand uncertainty using multiobjective programming","authors":"Kai Sun, Minghe Sun, Deepak Agrawal, Ronald Dravenstott, Frank Rosinia, Arkajyoti Roy","doi":"10.1111/poms.14058","DOIUrl":"https://doi.org/10.1111/poms.14058","url":null,"abstract":"Abstract This work addresses the practical anesthesiologist scheduling (AS) problem motivated by the needs of an academic anesthesiology department. The AS problem requires the department to plan and deploy providers to adequately meet clinical demand and institutional protocols of various clinical units over a planning horizon of up to several weeks. A data‐driven two‐step AS framework is developed by exploiting the historical demand data of anesthesia cases. The first step is a shift design which obtains the optimal shifts considering clinical demand under uncertainty using conditional value‐at‐risk constraints, and the second step is provider assignments that generate the schedule considering optimal and equitable workload distribution and provider availability using multiobjective mixed‐integer programming models. Moreover, the AS framework incorporates the provider specialties, and clinical and lifestyle preferences and aligns with the existing scheduling practices. An ɛ‐constraint solution method is applied for multiobjective optimization, and an iterative solution method is developed to improve solution quality for workload equity in clinical applications. Computational experiments are performed to evaluate the performance of three alternative forms of the workload equity objective function, and the results show that the minimization of the sum of the absolute deviations of provider workloads best balances solution runtime and quality. In the concerned academic anesthesiology department, two clinical problems, the budget and hiring planning and the monthly scheduling, are addressed via the application of the proposed AS framework. For budget and hiring, decision‐makers can make trade‐offs based on their preference using the nondominated frontiers obtained via the ɛ‐constraint method. For monthly scheduling, the iterative solution method can accommodate preassigned shifts capturing institutional requirements while improving workload equity. The workload variance has been substantially reduced from 2.92 to 1.39 after the implementation based on the historical schedule data. The provider schedule satisfaction is improved from 3.13/5 to 3.44/5, and at least 82% of scheduling burden on department leaders is relieved. The developed AS framework is generic and can be extended to the scheduling of other types of care providers, including nurses and residents.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134904067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Managing material shortages in project supply chains: Inventories, time buffers, and supplier flexibility","authors":"Panos Kouvelis, Xingxing Chen, Yu Xia","doi":"10.1111/poms.14059","DOIUrl":"https://doi.org/10.1111/poms.14059","url":null,"abstract":"Abstract We consider a two‐stage project supply chain with a downstream project firm producing an engineer‐to‐order (ETO) complex product or a make‐to‐order (MTO), low‐volume, customized industrial product as a project, and an upstream contract supplier supplying a key material to the project. The project faces two uncertainties: project activity time uncertainty and material consumption uncertainty, which may be positively or negatively correlated. In anticipation of these uncertainties, the project firm has to carefully decide its promised project due date to its project customer, against which harsh penalties will be assessed, and his material order quantity to commit to the contract supplier in advance. In most practical settings, project firms order from contracted suppliers via a flexible wholesale price contract consisting of a discounted advance order price and a risk‐premium adjusted expedite order price. The discounted advance order price encourages the project firm to take more inventory risk in the supply chain, and the expedite order price incentivizes the supplier to bear more inventory risk by carrying safety stock in excess of the project firm's advance material order. We formulate an optimization model that solves the project firm's project due date and material order problem, which takes into account the supplier's strategic reaction to the project firm's material order under the flexible wholesale price contract. We show that for MTO projects, risk‐sharing with suppliers on project materials is less important to the project firm, with the project firm assuming ownership of all material inventory in the channel and setting a deliberate project due date being the key. On the other hand, for ETO projects, risk‐sharing with contracted suppliers assumes critical importance. Project firms managing ETO projects should fully exploit the flexibility in the material supply contract to optimally drive the supplier's safety stock level and set the project due date reflecting the shared risk in the supply chain.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136129919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Competition between P2P Ridesharing Platforms and Traditional Taxis","authors":"Wen Diao, Baojun Jiang, Lin Tian","doi":"10.1111/poms.14062","DOIUrl":"https://doi.org/10.1111/poms.14062","url":null,"abstract":"Abstract Over the past decade, the surge of peer‐to‐peer (P2P) ride‐sharing has significantly cut the market share and profitability for taxis, but taxis remain a major service provider in the personal transportation service industry. This paper analytically examines a market with two segments of consumers based on their travel distances, where a P2P platform and a traditional taxi company have different inconvenience costs and compete for customers through pricing. Our analysis shows that consumers’ inconvenience costs and the relative size or travel–distance heterogeneity of the two consumer segments play an important role in determining the firms’ equilibrium targeting and pricing decisions. We find that the taxi's inconvenience cost can have non‐monotonic effects on firms’ prices. An increase in the taxi's inconvenience cost can reduce both firms’ profits because it can induce both firms to lower their prices. In an extension, we show that distance‐based price discrimination (charging different unit prices based on the consumer's travel distance) can lead to win–win or lose–lose outcomes for both firms. Our results have useful managerial and regulatory implications.","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Maximizing disability diversity, language diversity and productivity: A study in apparel manufacturing","authors":"Ying Zhang, Sriram Narayanan, Tharo Soun, Kalyanmoy Deb, Dustin Cole","doi":"10.1111/poms.14073","DOIUrl":"https://doi.org/10.1111/poms.14073","url":null,"abstract":"Abstract The UN Sustainable Development Goals have recently emphasized the importance of diversity inclusion. Motivated by this goal, we examine the impact of employing individuals with disabilities in apparel manufacturing cells on overall team productivity. We formulate a series of deterministic and stochastic productivity maximization assignment problems to study the impact of disability inclusion on a production line. We extend the baseline productivity maximization formulation to study a multi‐objective problem that simultaneously maximizes productivity, disability diversity, and language diversity. Each analysis is performed across two different garments drawn from a real‐world setting. The models are tested using archival time study data collected in partnership with an apparel manufacturing firm where more than 75% of the billed work hours are from individuals with significant disabilities. The following insights emerge from the analyses. First, the productivity of teams which have individuals across multiple, different types of disabilities is higher than the productivity of teams with employees who share a single, specific type of disability. Second, teams that employ both individuals with and without disabilities perform slightly better than teams that consist of only individuals with disabilities. In some instances, contrary to intuition, teams of only individuals with disabilities even have higher productivity than teams of only individuals with no disabilities. Finally, our results from the multi‐objective problem that simultaneously maximizes productivity, disability diversity, and language diversity suggest that productivity is not generally sensitive to increases in disability diversity. However, productivity is sensitive at extreme levels of disability diversity and language diversity. Limitations and possible future extensions of the study are discussed. This article is protected by copyright. All rights reserved","PeriodicalId":20623,"journal":{"name":"Production and Operations Management","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}