The analysis of production systems using discrete, event-based simulation is wide spread and generally accepted as a decision support technology. It aims either at the comparison of competitive system designs or the i...
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ISBN:
(纸本)9781479939503;9781479920778
The analysis of production systems using discrete, event-based simulation is wide spread and generally accepted as a decision support technology. It aims either at the comparison of competitive system designs or the identification of a best possible parameter configuration of a simulation model. Here, combinatorial techniques of simulation and optimization methods support the user in finding optimal solutions, but typically result in long computation times, which often prohibits a practical application in industry. To close this gap, this paper presents a fast converging procedure combining a Genetic Algorithm with a material flow simulation including an interactive analysis of simulation runs. An early termination of simulation runs is used for unpromising parameter configurations. The integrated implementation allows automated, distributed simulation runs for practical, complex production systems. A use-case shows the proof of concept with a reference model and demonstrates the resulting speed-up of this approach.
Continual improvements to the efficiency of patient flow in emergency departments (EDs) are necessary to meet patient demand. Discrete Event simulation (DES) is commonly employed for this purpose, but validation and v...
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ISBN:
(纸本)9781479939503;9781479920778
Continual improvements to the efficiency of patient flow in emergency departments (EDs) are necessary to meet patient demand. Discrete Event simulation (DES) is commonly employed for this purpose, but validation and verification is daunting in that many stakeholders-clinicians, administrators, and engineers-need to understand the system's processes in a unified manner. Therefore, knowledge transfer between stakeholders requires a unified formal approach. We describe the use use of System Modeling Language (SysML) to this end, as well as the results of model validation by comparing hourly census in many areas in the real-world ED with those predicted from simulation, before and after a process intervention. The accuracy of these comparisons provides evidence that a methodologically rigorous DES model, incorporating our method for model verification using SysML, is a valuable decision making tool for judging the utility of interventions to improve patient flow.
We tackle the problem of scheduling logical processes that can significantly affect the performance of running parallel simulation either in real time or proportional to real time. In particular, we present a comprehe...
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ISBN:
(纸本)9781479939503;9781479920778
We tackle the problem of scheduling logical processes that can significantly affect the performance of running parallel simulation either in real time or proportional to real time. In particular, we present a comprehensive solution to dealing with the mixture of simulated and emulated events in a full-fledged conservatively synchronized parallel simulation kernel to improve efficiency and timeliness for processing the emulated events. We propose an event delivery mechanism for the parallel simulator to incorporate emulated events originated from the physical system. We augment the parallel simulation API to support emulation capabilities independent from a particular simulation domain. Preliminary experiments demonstrate the our simulator's real-time performance on high-performance computing platforms.
When faced with output from multiple simulation models, a decision maker must aggregate the forecasts provided by each model. This problem is made harder when the models are based on similar assumptions or use overlap...
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ISBN:
(纸本)9781479939503;9781479920778
When faced with output from multiple simulation models, a decision maker must aggregate the forecasts provided by each model. This problem is made harder when the models are based on similar assumptions or use overlapping input data. This situation is similar to the problem of expert judgment aggregation where experts provide a forecast distribution based on overlapping information, but only samples from the output distribution are obtained in the simulation case. We propose a Bayesian method for aggregating forecasts from multiple simulation models. We demonstrate the approach using a climate change example, an area often informed by multiple simulation models.
This paper provides simulation practitioners and consumers with a grounding in how discrete-event simulation software works. Topics include discrete-event systems;entities, resources, control elements and operations;s...
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ISBN:
(纸本)9781479939503;9781479920778
This paper provides simulation practitioners and consumers with a grounding in how discrete-event simulation software works. Topics include discrete-event systems;entities, resources, control elements and operations;simulation runs;entity states;entity lists;and their management. The implementations of these generic ideas in AutoMod, SLX, ExtendSim, and Simio are described. The paper concludes with several examples of "why it matters" for modelers to know how their simulation software works, including discussion of AutoMod, SLX, ExtendSim, Simio, Arena, ProModel, and GPSS/H.
Global Sourcing adds to a company's value by realizing the best prices on a global market and making new markets accessible. However, increasing global orientation of the companies is associated with new challenge...
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ISBN:
(纸本)9781479939503;9781479920778
Global Sourcing adds to a company's value by realizing the best prices on a global market and making new markets accessible. However, increasing global orientation of the companies is associated with new challenges in planning and controlling the network processes to obtain a high service level and a guaranteed availability of supply goods. Order-to-Delivery Network simulation (OTD-NET) offers a simulation based approach for gaining insight in global networks. The OTD-NET suite provides services for modelling, simulating and analyzing complete logistic networks including the specifics of the different network participants like suppliers or producers. With the specialized automotive edition, OTD-NET enables a precise specification of complex products considering its configuration, bill of materials and supports an easy analysis of various network strategies like network design, structure and process concepts, supply strategies as well as different production strategies. OTD-NET is developed by Fraunhofer Institute for Material Flow and Logistics in Dortmund (Germany). Within the paper OTD-NET is presented and exemplarily demonstrated by a joint project with Volkswagen.
Government economic policy regarding the financial markets in the United States has been focused on promoting self-regulation based on a belief in natural equilibrium. This has led to decreased regulation and permitte...
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Rare events in heavy-tailed systems are challenging to analyze using splitting algorithms because large deviations occur suddenly. So, every path prior to the rare event is viable and there is no clear mechanism for r...
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ISBN:
(纸本)9781479939503;9781479920778
Rare events in heavy-tailed systems are challenging to analyze using splitting algorithms because large deviations occur suddenly. So, every path prior to the rare event is viable and there is no clear mechanism for rewarding and splitting paths that are moving towards the rare event of interest. We propose and analyze a splitting algorithm for the tail distribution of a heavy-tailed random walk. We prove that our estimator achieves the best possible performance in terms of the growth rate of the relative mean squared error, while controlling the population size of the particles.
Over the past decade, efforts have been made to incorporate Operations Management and Operations Research into pre-college school curricula. Not only does this approach introduce students earlier to a relatively unkno...
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ISBN:
(纸本)9781479939503;9781479920778
Over the past decade, efforts have been made to incorporate Operations Management and Operations Research into pre-college school curricula. Not only does this approach introduce students earlier to a relatively unknown field, but it also provides a different side of mathematics, showing that math can be very real-world specific, practical, and relevant. In this paper, we describe a semester-long research project working with a group of 14 sixth grade students at a US military base in Germany. At the end of the semester, students presented the results of a discrete event simulation study to their parents and peers. We feel the project was very successful, and would encourage others to try similar projects.
This paper deals with Optimization via simulation (OvS) of the management of a catchment basin involving dams, electrical power station, pumping station, valves, etc. We explain how an iterative process allows us to i...
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ISBN:
(纸本)9781479939503;9781479920778
This paper deals with Optimization via simulation (OvS) of the management of a catchment basin involving dams, electrical power station, pumping station, valves, etc. We explain how an iterative process allows us to integrate optimization algorithms into a discrete-event simulation using a DOvS (Discrete Optimization via simulation) methodology. This process has been implemented using the DEVSimPy (DEVS simulator in Python language) environment and the obtained results point out the feasibility of the proposed approach. Furthermore this software is actually used by the Corsican Water Agency in order to efficiently manage the South East water network.
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