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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Imported intermediate goods and product innovation(Elsevier B.V., 2024) Şeker, Murat; Rodriguez-Delgado, Jose Daniel; Department of Business Administration; Ulu, Mehmet Fatih; Department of Business Administration; College of Administrative Sciences and EconomicsWe build a structural model of multi-product firms to illustrate how access to foreign intermediate goods contributes to product innovation. We establish a stochastic dynamic model of firm evolution and allow firms to be heterogeneous in their efficiency levels. The model's mechanism to capture the effects of importing intermediate goods is twofold: (i) importing these goods increases the revenue per each product introduced, and (ii) increases the likelihood of introducing new varieties using newly available inputs. We calibrate the model to firm-level data from India. The model successfully explains the heterogeneous innovation dynamics and statistical moments related to importing and product distribution. Counterfactual exercises further illustrate and quantify the mechanism between trade, innovation performance, and product growth. We find that the critical contribution of trade to growth and product innovation is mainly through access to new imported varieties rather than just the direct import cost. © 2024 Elsevier B.V.Publication Metadata only Production and energy mode control of a production-inventory system(Elsevier, 2023) Karabag, Oktay; Khayyati, Siamak; Department of Business Administration; Tan, Barış; Department of Business Administration; College of Administrative Sciences and EconomicsEnergy efficiency in manufacturing can be improved by controlling energy modes and production dy-namically. We examine a production-inventory system that can operate in Working, Idle, and Off energy modes with mode-dependent energy costs. There can be a warm-up delay to switch between one mode to another. With random inter-arrival, production and warm-up times, we formulate the problem of de-termining in which mode the production resource should operate at a given time depending on the state of the system as a stochastic control problem under the long-run average profit criterion considering the sales revenue together with energy, inventory holding and backlog costs. The optimal solution of the problem for the exponential inter-arrival, production and warm-up times is determined by solving the Markov Decision Process with a linear programming approach. The structure of the optimal policy for the exponential case uses two thresholds to switch between the Working and Idle or Working and Off modes. We use the two-threshold policy as an approximate policy to control a system with correlated inter-event times with general distributions. This system is modelled as a Quasi Birth and Death Process and analyzed by using a matrix-geometric method. Our numerical experiments show that the joint pro-duction and energy control policy performs better compared to the pure production and energy control policies depending on the system parameters. In summary, we propose a joint energy and production control policy that improves energy efficiency by controlling the energy modes depending on the state of the system.Publication Metadata only Energy-efficient production control of a make-to-stock system with buffer- and time-based policies(Taylor and Francis Ltd., 2023) Karabağ, Oktay; Khayyati, Siamak; Department of Business Administration; Tan, Barış; Department of Business Administration; College of Administrative Sciences and EconomicsIncreasing energy efficiency in manufacturing has significant environmental and cost benefits. Turning on or off a machine dynamically while considering the production rate requirements can offer substantial energy savings. In this work, we examine the optimal policies to control production and turn on and off a machine that operates in working, idle, off, and warmup modes for the case where demand inter-arrival, production, and warmup times have phase-type distributions. The optimal control problem that minimises the expected costs associated with the energy usage in different energy modes and the inventory and backlog costs is solved using a linear program associated with the underlying Markov Decision Process. We also present a matrix-geometric method to evaluate the steady-state performance of the system under a given threshold control policy. We show that when the inter-arrival time distribution is not exponential, the optimal control policy depends on both the current phase of the inter-arrival time and inventory position. The phase-dependent policy implemented by estimating the current phase based on the time elapsed since the last arrival yields a buffer- and time-based policy to control the energy mode and production. We show that policies that only use the inventory position information can be effective if the control parameters are chosen appropriately. However, the control policies that use both the inventory and time information further improve the performance.Publication Metadata only The digital twin synchronization problem: framework, formulations, and analysis(Taylor & Francis Inc, 2023) Matta, Andrea; Department of Business Administration; Tan, Barış; Department of Business Administration; College of Administrative Sciences and EconomicsAs the adoption of digital twins increases steadily, it is necessary to determine how to operate them most effectively and efficiently. In this article, the digital twin synchronization problem is introduced and defined formally. Frequent synchronizations would increase cost and data traffic congestion, whereas infrequent synchronizations would increase the bias of the predictions and yield wrong decisions. This work defines the synchronization problem variants in different contexts. To discuss the problem and its solution, the problem of determining when to synchronize an unreliable production system with its digital twin to minimize the average synchronization and bias costs is formulated and analyzed analytically. The state-independent, state-dependent, and full-information solutions have been determined by using a stochastic model of the system. Solving the synchronization problem using simulation is discussed, and an approximate policy is proposed. Our results show that the performance of the state-dependent policy is close to the optimal solution that can be obtained with full information and significantly better than the performance of the state-independent policy. Furthermore, the approximate periodic state-dependent policy yields near-optimal results. To operate digital twins more effectively, the digital twin synchronization problem must be considered and solved to determine the optimal synchronization policy.Publication Metadata only Continuous-flow simulation of manufacturing systems with assembly/disassembly machines, multiple loops and general layout(Elsevier Sci Ltd, 2023) Scrivano, Salvatore; Tolio, Tullio; Department of Business Administration; Tan, Barış; Department of Business Administration; College of Administrative Sciences and EconomicsPerformance evaluation methods are important to design and control manufacturing systems. Approximate analytical methods are fast, but they may be limited by the restrictive assumptions on the system. On the contrary, simulation has not specific limitations in its applicability, but the time to model and analyse a manufacturing system can increase as the level of detail addressed by the model increases. The main contribution of this study is presenting a computationally efficient methodology to simulate single-part continuous-flow manufacturing systems with assembly/disassembly machines, multiple loops, general layout and general inter-event time distributions. By using graph theory, a new method is presented to identify the machines causing slowdown, blocking and starvation in a general layout and determine the time before the occurrence of a state transition for each machine and the time before the fulfilment or depletion of each buffer. By advancing the time clock to the next event-time accordingly, the number of discrete events needed to be simulated is decreased compared to a discrete-event simulation with discrete flow of parts. As a result, the proposed method is on average 15 times faster than DES methods in the analysis of discrete-flow systems, and 110 times faster on average in the analysis of continuous-flow systems. The low computational time of the proposed method allows to simulate systems under general assumptions and in a very short time.Publication Metadata only Enabling older employees' well-being through HR attributions: the moderating role of management context(Wiley, 2024) Department of Business Administration; Aksoy, Eda; Marcus, Justin; Department of Business Administration; College of Administrative Sciences and EconomicsFusing the extant literature on successful aging at work (SAW) and HR attributions, we examined the confluence of employee-oriented internal HR attributions and unit-level employee management context on burnout for employees across the age spectrum. Time-lagged, multi-level survey data were collected from a sample of 1762 blue-collar employees from 178 work units at the manufacturing plants of a large firm operating in the Turkish energy industry, which is characterized as a high-risk safety environment. A cross-level moderated mediation model was tested using multi-level structural equation modeling (MSEM). Results supported study hypotheses such that the negative association between age and burnout was mediated by employee-oriented positive HR attributions, and this indirect association was moderated by unit-level perceptions of the employee management context. Development-oriented contexts that emphasized personal development/growth-indicated by the degree of emphasis on innovation strategy, safety training, and active unit safety leadership-weakened the negative indirect (i.e., buffering) effect of age on burnout via less positive HR attributions. Conversely, a maintenance-oriented context that emphasized maintaining the status quo-indicated by passive unit safety leadership-strengthened said effect through more positive HR attributions. The theoretical and practical implications of these findings for fostering employee well-being across the age spectrum are discussed.Publication Metadata only LeverAge: a European network to leverage the multi-age workforce(Oxford Univ Press, 2024) Scheibe, Susanne; Kooij, Dorien; Truxillo, Donald M.; Zaniboni, Sara; Abuladze, Liili; Bamberger, Peter A.; Balytska, Mariia; Betanzos, Norma D.; Perek-Bialas, Jolanta; Boehm, Stephan Alexander; Burmeister, Anne; Cabib, Ignacio; Caon, Maurizio; Deller, Juergen; Derous, Eva; Drury, Lisbeth; Eppler-Hattab, Raphael; Fasbender, Ulrike; Fueloep, Marta; Furunes, Trude; Gerpott, Fabiola H.; Gostautaite, Bernadeta; Halvorsen, Cal J.; Hernaus, Tomislav; Inceoglu, Ilke; Iskifoglu, Mustafa; Ivanoska, Kalina Sotiroska; Kanfer, Ruth; Kenig, Nikolina; Klimek, Sabina; Kunze, Florian; Mertan, Emete Biran; Varianou-Mikellidou, Cleo; Moasa, Horia; Ng, Yin Lu; Parker, Sharon K.; Reh, Susan; Resuli, Vebina; Schmeink, Martina; Silberg, Slavka; Sousa, Ines C.; Steiner, Dirk D.; Stukalina, Yulia; Tomas, Jasmina; Topa, Gabriela; Turek, Konrad; Vignoli, Michela; von Bonsdorff, Monika; Wang, Dahua; Wang, Mo; Yeung, Dannii Yuen-lan; Yildirim, Kemal; Zhang, Xin; Znidarsic, Jana; Department of Business Administration; Marcus, Justin; Al Mursi, Noura; Kıran, Sibel; Department of Business Administration; College of Administrative Sciences and Economics; Graduate School of Business; School of MedicineBringing together 150+ scholars and practitioners from 50+ countries, and funded by the European Commission, COST Action LeverAge (https://www.cost.eu/actions/CA22120/) is the first network-building project of its kind in the work and organizational psychology and human resource management (WOP/HRM) aspects of work and aging. Focused on the aging workforce, the Action aims to foster interdisciplinary and multinational scientific excellence and the translation of science to practical and societal impact across 4 years. Based on a research synthesis, we identify five broad research directions for work and aging science including work and organizational practices for a multi-age workforce, successful aging at work, the integration of age-diverse workers and knowledge transfer, aging and technology at work, and career development in later life and retirement. We provide key research questions to guide scientific inquiry along these five research directions alongside best practice recommendations to expand scholarly impact in WOP/HRM.Publication Metadata only Duality of language as a tool for integration versus mobility at work: utility of a polyphonic perspective(Edward Elgar Publishing Ltd, 2023) Erbil, Cihat; Baglama, Sercan Hamza; Department of Business Administration; Özbilgin, Mustafa; Department of Business Administration; College of Administrative Sciences and EconomicsN/APublication Metadata only Patient adherence in healthcare operations: a narrative review(Elsevier Ltd, 2024) Department of Business Administration; Kılıç, Hakan; Güneş, Evrim Didem; Department of Business Administration; Graduate School of Sciences and Engineering; College of Administrative Sciences and EconomicsPatient nonadherence to healthcare providers’ recommendations is a major obstacle to desired health outcomes. It results in health deterioration and hospitalization, which might have been avoided with a high level of patient adherence. This paper reviews the literature addressing the issue of adherence in healthcare operations. A total of 73 published articles from operations research and management science journals are included in the review as a result of the systematic search that covered studies from inception until October 26, 2022. This paper is the first comprehensive review of adherence-related research in the operations research field. We summarize how adherence is measured, the research contexts, interactions between adherence and the healthcare system, and how adherence is modeled mathematically. Furthermore, we review adherence-related research at clinical, hospital, and healthcare system levels of planning and control, in addition to medical decision-making. We identify the opportunities in adherence research under the following themes: Supporting proactive management of adherence for healthcare providers, designing a healthcare system that enables adherence, developing personalized treatments, and addressing the global health issues of antimicrobial resistance and vaccine hesitancy. © 2023Publication Metadata only Service science editorial board, 2023(Informs Inst.for Operations Res.and the Management Sciences, 2023) Benjaafar, Saif; Jiang, Baojun; Xu, Alison; Allon, Gad; Tang, Christopher S.; Chernobai, Anna; Pinedo, Michael; Schaefer, Andrew; Agarwal, Ashish; Agrawal, Vishal; Anderson, Chris; Barrett, Michael; Basole, Rahul; Belavina, Elena; Blomberg, Jeanette; Boyacı, Tamer; Buell, Ryan; Burtch, Gordon; Chan, Timothy; Chen, Cynthia; Chen, Li; Choi, Sunmee; Chun, HaeEun Helen; Curti, Filippo; Debo, Laurens; Dixon, Michael; Elmachtoub, Adam; Fang, Eric; Farahani, Reza Zanjirani; Geroliminis, Nikolas; Guajardo, Jose; Gui, Luyi; Gurnani, Haresh; Hua, Zhongsheng; Brandeau, Margaret; Chase, Richard; Dietrich, Brenda; Frei, Frances; Gann, David; Gallego, Guillermo; Hu, Ming; Verma, Rohit; Sheng, Olivia; de Vericourt, Francis; Roels, Guillaume; Roth, Aleda; Cui, Tony Haitao; Huang, Yanliu; Iyer, Krishnamurthy; Jouini, Oualid; Kannan, P.K.; Kavadias, Stelios; Kim, Sang; de Koster, Rene; Lee, Donald; Li, Zhepeng; Lin, Grace; Liu, Yunchuan; Lo, Chris; Mak, Ho-Yin; Minner, Stefan; Misic, Velibor; Narayanan, Sriram; Nie, Marco; Nohadani, Omid; Osadchiy, Nikolay; Pant, Gautam; Righter, Rhonda; Saghafian, Soroush; Shi, Pengyi; Harker, Patrick; Hsu, Cheng; Karmarkar, Uday; Larson, Richard; Baron, Opher; Ziya, Serhan; Song, Jeannette; Girotra, Karan; Yin, Yafeng; Benjaafar, Saif; Shin, Hyoduk; Shugan, Steve; Subramanian, Upender; Sun, Peng; Sun, Wei; Taneri, Niyazi; Thompson, Gary; Trichakis, Nikolaos; Van Oyen, Mark; Venkataraman, Sriram; Victorino, Liana; Wang, Hai; Wang, Zizhuo; Wu, Xiaole; Xu, Lizhen; Xu, Yuqian; Yam, Kai Chi; Yang, Xiaojing; Yano, Candace; Yu, Yimin; Zhang, Yinghao; Zheng, Karen; Zhou, Sean; Qiu, Robin G.; Roth, Aleda; Tien, James; Wladawsky-Berger, Irving; Department of Business Administration; Karaesmen, Zeynep Akşin; Department of Business Administration; College of Administrative Sciences and Economics