My research interests fall in the area of Operations Management. I develop predictive and prescriptive Business Analytics approaches for the quantitative analyses of dynamic and stochastic systems. The research can be clustered in the following three areas:
Research interests
Predicting key performance measures such as throughput and cycle time is the basis for the design and control of systems that are subject to stochastic and dynamic influences (see Figure). This research area focuses on the development of queuing models and approaches for their quantitative analysis. Challenging is, e.g., the derivation of performance measures beyond the mean such as quantiles or service levels. This information is key for a solid risk assessment. The models and methods find applications in the analysis and optimization of manufacturing systems and logistics systems such as material handling systems.
The digitalization has extensive effects on supply chains and production systems. This research area focuses on methods that exploit available data and information about future developments of customer demand and the production system itself, on the control of digitalized production systems. This is relevant, e.g., for seasonal demand or during production ramp-up. Moreover, solution approaches that include the identification of structural properties of the underlying optimization problem in combination with simulation/
The trend towards shortening product life cycles leads to more frequent changes between product generations. Managing the transition phase is challenging because of the complex interdependencies between companies’ decisions and customer reactions. In particular, substitution effects between product generations need to be captured. The research aims at deriving structural insights about the impact of finite and stochastic production capacities on strategies for the transition phase that give guidance regarding product offering, pricing, production, and inventory decisions.
Publications
- Weiss, S., J. A. Schwarz, and R. Stolletz (2019): The Buffer Allocation Problem in production lines: Formulations, solution methods, and instances. IISE Transactions (formerly IIE Transactions), 51 (5), 456-485.
- Schwarz, J. A. and M. Epp (2016): Performance evaluation of a transportation-type bulk queue with generally distributed inter-arrival times. International Journal of Production Research 54 (20), 6251-6264.
- Schwarz, J. A., G. Selinka, and R. Stolletz (2016): Performance analysis of time-dependent queueing systems: survey and classification. Omega 63, 170-189.
- Göttlich, S., S. Kühn, J. A. Schwarz, and R. Stolletz (2016): Approximations of time-dependent unreliable flow lines with finite buffers. Mathematical Methods of Operations Research, 83 (3), 295-323.
- Schwarz, J. A., J. Stoll, and E. Özden (2015): A general model for batch building processes under the timeout and capacity rules. Annals of Operations Research 231 (1), 5-31.
- Daim, T. U., D. Lim, F. A. Gomez, J. A. Schwarz, and S. Jovanovic (2014): Storage technologies for wind power in the Columbia River Gorge. International Journal of Sustainable Energy 33 (1), 1-15.
- Schwarz, J. A., B. Tan (2019): Optimal sales and production rollover strategies under capacity constraints.
- Schwarz, J. A. and R. Stolletz. (2018): „Management von Produktionsanläufen.“ (Management of production ramp-ups) In: H. Corsten, R. Gössinger and T. S. Spengler (editors): Handbuch Produktions- und Logistikmanagement in Wertschöpfungsnetzwerken, 539-552, De Gruyter Oldenbourg, Berlin (in German).
- Schwarz, J. A. and R. Stolletz (2013): Warteschlangentheorie in der Betriebswirtschaftslehre. (Queueing theory and business administration.) WiSt - Wirtschaftswissenschaftliches Studium 42 (5), 262-265 (in German).
Participation in funded research projects
The research project “Productive 4.0 - Analytical approaches for performance evaluation and optimization of stochastic and dynamic processes in digital production” investigates how electronics and Information and Communication Technologies (ICT) can enhance production efficiency in semi-conductor supply chains across the entire value chain and product life cycle. With 109 partners from industry and research institutions, Productive4.0 is Europe’s biggest research project in the field of Digital Industry. The project is recognized as an ECSEL Lighthouse Initiative and receives funding from the EU and the German Federal Ministry of Education and Research (BMBF). The Chair of Production Management focuses on two challenging optimization problems: (i) operational planning of start of production decisions and (ii) product rollover management. These problems are of practical relevance due to the frequent ramp-ups and ramp-downs caused by short product life cycles in the semiconductor industry.
The goal of this research project is the development of the theoretical foundation to support decision makers in creating shift schedules for the workforce and other resources. We consider the stochasticity and time-dependency of demand as key aspects that must be taken into account. Relevant objectives that will be investigated are the minimization of the employed workforce and related workforce costs as well as profit-oriented performance measures. The resulting plans must satisfy several constraints. The most important ones are contractual agreements on the working hours and on-time delivery of the goods. The main focus of this research project is the modeling of multi-stage systems with stochastic influences as well as the optimization and evaluation of the shift schedules. Our goal is to make a significant contribution to the research community and support decision makers of production and logistics systems with new managerial insights and the development of new optimization methods.
(Funded by Deutsche Forschungsgemeinschaft e.V. in Collaboration with Karlsruher Institut für Technologie) (2018 - 2020)
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Presentations at conferences, workshops, and research seminars
- Schwarz, J. A. (2019): Rollover strategies under stochastic demand and production, 8th Workshop on Queueing Theory, Obergurgl, Austria, December 2019.
- Schwarz, J. A. (2019): Optimal Rollover Strategies For Stochastic Demand and Production, INFORMS Annual Meeting, Seattle, USA, October 2019 (supported by DAAD).
- Schwarz, J. A., G. P Kiesmüller, and R. Stolletz (2019): Optimal repair decisions in capacitated repair shops for flow lines, SMMSO 2019, Goslar, Germany, June 2019.
- Schwarz, J. A. (2019): Optimizing Sales and Production Rollover Strategies Under Stochastic Demand and Random Yield. POMS 2019 28th Annual Conference, Washington D.C., USA, May 2019 (supported by Julius-Paul-Stiegler-Gedächtnis-Stiftung).
- Schwarz, J. A. and O. Karabag (2019): Optimal rollover strategies under consideration of capacity constraints, Research seminar – TU Eindhoven, TU Eindhoven, Eindhoven, The Netherlands, April 2019.
- Schwarz J. A. and R. Stolletz (2019): Impact of stochastic yield with learning on start of production. 11th Workshop for Supply Chain Management and Production, Obergurgl, Austria, March 2019.
- Schnitzler, J. M., Schwarz, J. A., and R. Stolletz (2019): Impact of stochastic yield with learning on start of production. Productive4.0 Research Workshop, Istanbul, Turkey, January 2019.
- Schwarz, J. A. and R. Stolletz (2018): Optimal repair decisions in capacitated repair shops for flow lines: First results. 7th Workshop on Queueing Theory, Obergurgl, Austria, December 2018.
- Schwarz, J. A. and B. Tan (2018): Sales and Operations Planning for Product Rollovers under Limited Capacity, INFORMS Annual Meeting, Phoenix, USA, November 2018 (supported by DAAD).
- Schwarz, J. A. (2018): Analyzing the impact of finite capacity on sales and operations planning for product rollovers. EURO 2018, Valencia, Spain, July 2018.
- Schwarz, J. A. (2018): Sales and operations planning for product rollovers with finite production capacities. Manufacturing and Service Operations Management 2018 Conference, Dallas, USA, July 2018 (supported by Julius-Paul-Stiegler-Gedächtnis-Stiftung).
- Schwarz, J. A. and R. Stolletz (2018): Structural properties of time-dependent flow production systems. StochMod18, Lancaster, UK, June 2018.
- Schwarz, J. A. (2018): Sales and operations planning for product rollovers: Structural insights. 28. Workshop der Quantitativen Betriebswirtschaftslehre, Hoechst, Germany, March 2018.
- Schwarz, J. A. (2018): Sales and operations planning for product rollovers, Research seminar - Mercator School of Management, University of Duisburg-Essen, Duisburg, Germany, January 2018.
- Schwarz, J. A. and R. Stolletz (2017): Minimizing work-in-process inventory in time-dependent flow lines by proactive Kanban control, Automotive Workshop, Brunswick, September 2017.
- Schwarz, J. A. and R. Stolletz (2017): Minimizing work-in-process inventory in dynamic Kanban systems. OR2017, Berlin, September 2017.
- Schwarz, J. A. and R. Stolletz (2017): Structural properties of flow production with time-dependent processing rates. INFORMS Applied Probability Society Conference 2017, Evanston, Illinois, USA, July 2017.
- Schwarz, J. A. and Stolletz, R. (2017): Numerical comparison of Kanban mechanisms for production systems with time-dependent processing times. SMMSO 2017, Acaya (Lecce), Italy, June 2017 (supported by Julius-Paul-Stiegler-Gedächtnis-Stiftung).
- Schwarz, J. A. (2017): Product rollovers with finite production capacities: first results. 9. Workshop für Supply Chain Management und Produktion, Obergurgl, Austria, March 2017.
- Schwarz, J. A. and R. Stolletz (2016): Structural properties of flow production lines for stationary, transient and time-dependent settings. 5th Workshop on Queueing Theory, Obergurgl, Austria, December 2016.
- Schwarz, J. A. and R. Stolletz (2016): Minimizing work-in-process inventory in stochastic and time-dependent flow lines. OR 2016, Hamburg, Germany, September 2016.
- Schwarz, J. A. and R. Stolletz (2016): A proactive approach to Kanban allocation in stochastic and time-dependent flow lines. POMS 2016 27th Annual Conference, Orlando, USA, May 2016 (supported by DAAD).
- Schwarz, J. A. and R. Stolletz (2016): BAPLib - A library and classification of Buffer Allocation Problem instances in serial flow lines. 8. Forschungsseminar für Supply Chain Management und Produktion, Obergurgl, Austria, March 2016.
- J. A. Schwarz and R. Stolletz (2015): Structural properties in stochastic and time-dependent flow lines. 4th Workshop on Queueing Theory, Obergurgl, Austria, December 2015.
- Schwarz, J. A. and R. Stolletz (2015): The allocation of Kanban cards in stochastic and time-dependent production systems. OR 2015, Vienna, Austria, September 2015 (supported by IPID4all funds of the DAAD).
- Schwarz, J. A. and R. Stolletz (2015): Performance analysis of time-dependent queueing systems: Survey and classification. 18th INFORMS Applied Probability Society Conference, Istanbul, Turkey, July 2015 (supported by IPID4all funds of the DAAD).
- Weiss, S., J. A. Schwarz, and R. Stolletz (2015): Buffer Allocation Problems for stochastic flow lines with unreliable machines. SMMSO 2015, Volos, Greece, June 2015 (supported by Julius-Paul-Stiegler-Gedächtnis-Stiftung).
- Schwarz, J. A. and R. Stolletz (2014): Performance analysis of time-dependent queueing systems: A survey and classification. 3rd Workshop on Queueing Theory, Obergurgl, Austria, December 2014.
- Schwarz, J. A. (2014): A classification of approaches to the performance evaluation of time-dependent queues. 8th Young European Queueing Theorists Workshop, Eindhoven, Netherlands, November 2014 (invited talk).
- Schwarz, J. A. and R. Stolletz (2014): Setting Kanban cards for non-stationary and stochastic flow lines via sampling. OR 56 - 56th Conference of the UK Operational Research Society, London, UK, September 2014 (supported by Julius-Paul-Stiegler-Gedächtnis-Stiftung).
- Schwarz, J. A. and R. Stolletz (2014): Setting Kanban cards for production systems under non-stationary and stochastic operating environments. OR 2014, Aachen, September 2014.
- Schwarz, J. A., G. Selinka, and R. Stolletz (2014): Analytical performance evaluation of time-dependent queues: A classification. StochMod14, Mannheim, July 2014.
- Schwarz, J. A. and R. Stolletz (2013): Setting Kanban cards for production systems under non-stationary and stochastic operating environments. 2nd Workshop on Queueing Theory, Obergurgl, Austria, December 2013.
- Schwarz, J. A. and R. Stolletz (2013): A sampling approach for the analysis of time-dependent stochastic flow lines. SMMSO 2013, Kloster Seeon, May 2013.
- Schwarz, J. A. and R. Stolletz (2013): Evaluation and optimization of buffer allocations in time-dependent stochastic flow lines. 23. Workshop für Quantitative Betriebswirtschaftslehre, Altleiningen, February 2013.
- Schwarz, J. A. and R. Stolletz (2012): Time-dependent stochastic flow lines. Workshop on Queueing Theory, Obergurgl, Austria, December 2012.
- Schwarz, J. A., R. Stolletz, and S. Göttlich (2012): Time-dependent stochastic tandem queues. Brownbag Seminar Operations Management & Operations Research, Mannheim, November 2012.
- Schwarz, J. A. (2012): A discrete time approach to analyze the behavior of Milkrun supplied inventories. OR 2012, Hanover, September 2012.
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Education
03/2012-04/2016
Doctoral Studies in Business Administration, Chair of Production Management (Prof. Stolletz), University of Mannheim
10/2006-12/2011
Studies in Business Engineering (Diploma), Karlsruhe Institute of Technology (KIT)09/2009-06/2010
Studies in Engineering and Technology Management (M.S.), Portland State University07/2006
Abitur, Gymnasium Oberalster, Hamburg -
Awards and grants
- Südwestmetall Förderpreis 2016, awarded by the Baden-Wuerttemberg Employers’ Association of the Metal and Electrical Industry, for the Ph.d. thesis „Analysis of buffer allocations in time-dependent and stochastic flow lines“
- Dieter Arnold Preis 2012, awarded by the „Wissenschaftliche Studiengesellschaft für Fördertechnik Karlsruhe e.V.“, for the diploma thesis „Modellierung einer Serienfertigung mit Kanban-Heijunka-Steuerung und Materialbereitstellung über Milkrun-Zyklen“ (Modeling of a Heijunka leveled Kanban controlled production system, with auxiliary materials distributed by Milkrun cycles)
- Camelot Innovative Value Chain Thesis Award for the diploma thesis „Modellierung einer Serienfertigung mit Kanban-Heijunka-Steuerung und Materialbereitstellung über Milkrun-Zyklen“ (Modeling of a Heijunka leveled Kanban controlled production system, with auxiliary materials distributed by Milkrun cycles)
- GfPM Thesis Award 2012 for the diploma thesis „Modellierung einer Serienfertigung mit Kanban-Heijunka-Steuerung und Materialbereitstellung über Milkrun-Zyklen“ (Modeling of a Heijunka leveled Kanban controlled production system, with auxiliary materials distributed by Milkrun cycles)
- BVL Thesis Award 2012 for the diploma thesis „Modellierung einer Serienfertigung mit Kanban-Heijunka-Steuerung und Materialbereitstellung über Milkrun-Zyklen“ (Modeling of a Heijunka leveled Kanban controlled production system, with auxiliary materials distributed by Milkrun cycles)
- Fulbright Scholarship, 2009-2010
- Scholarship of the Konrad Adenauer Stiftung, 2006-2011
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Professional experience
09/2016-present
Assistant Professor (Akademischer Rat auf Zeit), Chair of Production Management (Prof. Stolletz), University of Mannheim06/2016–08/2016
Visiting Scholar, Koc University, College of Administrative Sciences and Economics, Turkey05/2016–06/2016
Visiting Scholar, Massachusetts Institute of Technology, Laboratory for Manufacturing and Productivity, USA03/2012-04/2016
Research Assistant, Chair of Production Management (Prof. Stolletz), University of Mannheim04/2011-06/2011
Internship, The Boston Consulting Group GmbH, Johannesburg South Africa11/2010-02/2011
Internship, Robert Bosch GmbH, Karlsruhe09/2008-10/2008
Internship, Preh GmbH, Bad Neustadt a. d. Saale