Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383881
Guanting Chen, Alexander D. Shkolnik, K. Giesecke
We develop and analyze Monte Carlo simulation estimators for path integrals of a multivariate diffusion with a general state-dependent drift and volatility. We prove that our estimators are unbiased and have finite variance by extending the regularity conditions of the parametrix method. The performance of our estimators is illustrated on numerical examples that highlight some applied problems for which our estimators apply.
{"title":"Unbiased Simulation Estimators for Path Integrals of Diffusions","authors":"Guanting Chen, Alexander D. Shkolnik, K. Giesecke","doi":"10.1109/WSC48552.2020.9383881","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383881","url":null,"abstract":"We develop and analyze Monte Carlo simulation estimators for path integrals of a multivariate diffusion with a general state-dependent drift and volatility. We prove that our estimators are unbiased and have finite variance by extending the regularity conditions of the parametrix method. The performance of our estimators is illustrated on numerical examples that highlight some applied problems for which our estimators apply.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"52 1","pages":"277-288"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84187841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383883
M. Müller, J. Ulrich, T. Reggelin, S. Lang, L. Reyes-Rubiano
Automated guided vehicles (AGVs) form a large and important part of logistic systems to improve productivity and reduce costs. When multiple AGVs are running in limited and uncertain environments, lots of issues can occur, such as collisions and deadlocks, which need to be addressed. This paper presents a flexible simulation model for a warehouse with various AGVs. We implemented all three typical strategies to handle deadlocks: prevention, avoidance and detection and resolution. The results show that there is no dominant strategy and that the results strongly depend on the individual case and the input parameters.
{"title":"Comparison of Deadlock Handling Strategies for Different Warehouse Layouts with an AGVS","authors":"M. Müller, J. Ulrich, T. Reggelin, S. Lang, L. Reyes-Rubiano","doi":"10.1109/WSC48552.2020.9383883","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383883","url":null,"abstract":"Automated guided vehicles (AGVs) form a large and important part of logistic systems to improve productivity and reduce costs. When multiple AGVs are running in limited and uncertain environments, lots of issues can occur, such as collisions and deadlocks, which need to be addressed. This paper presents a flexible simulation model for a warehouse with various AGVs. We implemented all three typical strategies to handle deadlocks: prevention, avoidance and detection and resolution. The results show that there is no dominant strategy and that the results strongly depend on the individual case and the input parameters.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"6 1","pages":"1300-1311"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78520213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383917
F. Buonocore, S. Giusepponi, M. Celino, P. García-Muller, R. M. García
In the silicon heterojunction solar cells, intrinsic hydrogenated amorphous silicon a-Si:H is used to passivate the crystal silicon c-Si surface to suppress the electrical losses at interfaces and to keep ultralow contact resistivity for the selective transport of one type of carrier only. We use ReaxFF (Reactive Force Field) molecular dynamics to efficiently simulate the thermalisation, quenching, and equilibration processes involving thousands of atoms forming realistic a-Si:H/c-Si interface structures. We generated snapshots of the equilibrated c-Si/a-Si:H interface atom configurations at room temperature. The ab initio characterization has been executed on selected configurations to monitor the electronic properties of the c-Si/a-Si:H interface. The evolution of the intragap states is monitored by analyzing density of states and charge density. This all will allow to design more efficient silicon solar cells belonging to the silicon heterojunction technology.
{"title":"A Combined Classical Molecular Dynamics Simulations and AB Initio Calculations Approach to Study A-SI:H/C-SI Interfaces","authors":"F. Buonocore, S. Giusepponi, M. Celino, P. García-Muller, R. M. García","doi":"10.1109/WSC48552.2020.9383917","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383917","url":null,"abstract":"In the silicon heterojunction solar cells, intrinsic hydrogenated amorphous silicon a-Si:H is used to passivate the crystal silicon c-Si surface to suppress the electrical losses at interfaces and to keep ultralow contact resistivity for the selective transport of one type of carrier only. We use ReaxFF (Reactive Force Field) molecular dynamics to efficiently simulate the thermalisation, quenching, and equilibration processes involving thousands of atoms forming realistic a-Si:H/c-Si interface structures. We generated snapshots of the equilibrated c-Si/a-Si:H interface atom configurations at room temperature. The ab initio characterization has been executed on selected configurations to monitor the electronic properties of the c-Si/a-Si:H interface. The evolution of the intragap states is monitored by analyzing density of states and charge density. This all will allow to design more efficient silicon solar cells belonging to the silicon heterojunction technology.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"21 1","pages":"3117-3127"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73279750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383924
Hong Wan, Kejun Li, Yining Huang
Blockchain is a distributed, append-only digital ledger (database). The technology has caught much attention since the emergence of cryptocurrency, and there is an increasing number of blockchain applications in a wide variety of businesses. The concept, however, is still novel to many members of the simulation and operations research community. In this tutorial, we introduce the blockchain technology and review its frontier operations-and-data-related research. There are exciting opportunities for researchers in simulation, system analysis, and data science.
{"title":"Blockchain: A Review from The Perspective of Operations Researchers","authors":"Hong Wan, Kejun Li, Yining Huang","doi":"10.1109/WSC48552.2020.9383924","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383924","url":null,"abstract":"Blockchain is a distributed, append-only digital ledger (database). The technology has caught much attention since the emergence of cryptocurrency, and there is an increasing number of blockchain applications in a wide variety of businesses. The concept, however, is still novel to many members of the simulation and operations research community. In this tutorial, we introduce the blockchain technology and review its frontier operations-and-data-related research. There are exciting opportunities for researchers in simulation, system analysis, and data science.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"19 1","pages":"75-89"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77190640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent robotic research has led to different architectural approaches that support enactment of automatically synthesized discrete event controllers from user specifications over low-level continuous variable controllers. Simulation of these hybrid control approaches to robotics can be a useful validation tool for robot users and architecture designers, but presents the key challenge of working with discrete and continuous representations of the robot, its environment and its mission plans. In this work we address this challenge showcasing a unified DEVS-based hybrid simulation platform. We model and simulate the hybrid robotic software architecture of a fixed-wing UAV, including the full stack of controllers involved: discrete, hybrid and continuous. We validate the approach experimentally on a typical UAV mapping mission and show that with our unified approach we are able to achieve simulation speed-ups up to one order of magnitude above our previous Software In The Loop simulation setup.
{"title":"Unified Devs-Based Platform for Modeling and Simulation of Hybrid Control Systems","authors":"Ezequiel Pecker Marcosig, Sebastián Zudaire, Martín Garrett, Sebastián Uchitel, R. Castro","doi":"10.1109/WSC48552.2020.9384025","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384025","url":null,"abstract":"Recent robotic research has led to different architectural approaches that support enactment of automatically synthesized discrete event controllers from user specifications over low-level continuous variable controllers. Simulation of these hybrid control approaches to robotics can be a useful validation tool for robot users and architecture designers, but presents the key challenge of working with discrete and continuous representations of the robot, its environment and its mission plans. In this work we address this challenge showcasing a unified DEVS-based hybrid simulation platform. We model and simulate the hybrid robotic software architecture of a fixed-wing UAV, including the full stack of controllers involved: discrete, hybrid and continuous. We validate the approach experimentally on a typical UAV mapping mission and show that with our unified approach we are able to achieve simulation speed-ups up to one order of magnitude above our previous Software In The Loop simulation setup.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"76 1","pages":"1051-1062"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82576814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383918
I. Stogniy, W. Scholl
Infineon Technologies Dresden has long used discrete event simulation to optimize production planning for its fully automated front end manufacturing lines. There are needs to reduce maintenance efforts, to increase transparency for validation and verification, and to improve flexibility for the fast simulation of scenarios with a focus on qualitative statements. Less detailed models will be utilized where components could be omitted. This paper considers a simplification of the process flows through operation substitution for constant delays. The main idea is to consider the accuracy measurements used to evaluate simplification. It is shown that standard accuracy measurements (e.g. mean absolute error, correlation coefficient, etc.) produce rather poor performance. It is suggested instead to use measurements based on lot cycle time distributions (e.g. goodness-of-fit tests). Nine types of simplification sieve functions were analyzed, with analyses based on the MIMAC dataset 5 model.
{"title":"Using Accuracy Measurements to Evaluate Simulation Model Simplification","authors":"I. Stogniy, W. Scholl","doi":"10.1109/WSC48552.2020.9383918","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383918","url":null,"abstract":"Infineon Technologies Dresden has long used discrete event simulation to optimize production planning for its fully automated front end manufacturing lines. There are needs to reduce maintenance efforts, to increase transparency for validation and verification, and to improve flexibility for the fast simulation of scenarios with a focus on qualitative statements. Less detailed models will be utilized where components could be omitted. This paper considers a simplification of the process flows through operation substitution for constant delays. The main idea is to consider the accuracy measurements used to evaluate simplification. It is shown that standard accuracy measurements (e.g. mean absolute error, correlation coefficient, etc.) produce rather poor performance. It is suggested instead to use measurements based on lot cycle time distributions (e.g. goodness-of-fit tests). Nine types of simplification sieve functions were analyzed, with analyses based on the MIMAC dataset 5 model.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"28 1","pages":"1825-1836"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78834055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383903
Jens Heger, T. Voss
Sequencing operations can be difficult, especially under uncertain conditions. Applying decentral sequencing rules has been a viable option; however, no rule exists that can outperform all other rules under varying system performance. For this reason, reinforcement learning (RL) is used as a hyper heuristic to select a sequencing rule based on the system status. Based on multiple training scenarios considering stochastic influences, such as varying inter arrival time or customers changing the product mix, the advantages of RL are presented. For evaluation, the trained agents are exploited in a generic manufacturing system. The best agent trained is able to dynamically adjust sequencing rules based on system performance, thereby matching and outperforming the presumed best static sequencing rules by ≈ 3%. Using the trained policy in an unknown scenario, the RL heuristic is still able to change the sequencing rule according to the system status, thereby providing robust performance.
{"title":"Dynamically Changing Sequencing Rules with Reinforcement Learning in a Job Shop System With Stochastic Influences","authors":"Jens Heger, T. Voss","doi":"10.1109/WSC48552.2020.9383903","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383903","url":null,"abstract":"Sequencing operations can be difficult, especially under uncertain conditions. Applying decentral sequencing rules has been a viable option; however, no rule exists that can outperform all other rules under varying system performance. For this reason, reinforcement learning (RL) is used as a hyper heuristic to select a sequencing rule based on the system status. Based on multiple training scenarios considering stochastic influences, such as varying inter arrival time or customers changing the product mix, the advantages of RL are presented. For evaluation, the trained agents are exploited in a generic manufacturing system. The best agent trained is able to dynamically adjust sequencing rules based on system performance, thereby matching and outperforming the presumed best static sequencing rules by ≈ 3%. Using the trained policy in an unknown scenario, the RL heuristic is still able to change the sequencing rule according to the system status, thereby providing robust performance.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"102 1","pages":"1608-1618"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76091654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9384130
C. Alexopoulos, Joseph H. Boone, D. Goldsman, Athanasios Lolos, Kemal Dinçer Dingeç, James R. Wilson
Extending developments of Calvin and Nakayama in 2013 and Alexopoulos et al. in 2019, we formulate point and confidence-interval (CI) estimators for given quantiles of a steady-state simulation output process based on the method of standardized time series (STS). Under mild, empirically verifiable conditions, including a geometric-moment contraction (GMC) condition and a functional central limit theorem for an associated indicator process, we establish basic asymptotic properties of the STS quantile-estimation process. The GMC condition has also been proved for many widely used time-series models and a few queueing processes such as M/M/1 waiting times. We derive STS estimators for the associated variance parameter that are computed from nonoverlapping batches of outputs, and we combine those estimators to build asymptotically valid CIs. Simulated experimentation shows that our STS-based CI estimators have the potential to compare favorably with their conventional counterparts computed from nonoverlapping batches.
{"title":"Steady-State Quantile Estimation Using Standardized Time Series","authors":"C. Alexopoulos, Joseph H. Boone, D. Goldsman, Athanasios Lolos, Kemal Dinçer Dingeç, James R. Wilson","doi":"10.1109/WSC48552.2020.9384130","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384130","url":null,"abstract":"Extending developments of Calvin and Nakayama in 2013 and Alexopoulos et al. in 2019, we formulate point and confidence-interval (CI) estimators for given quantiles of a steady-state simulation output process based on the method of standardized time series (STS). Under mild, empirically verifiable conditions, including a geometric-moment contraction (GMC) condition and a functional central limit theorem for an associated indicator process, we establish basic asymptotic properties of the STS quantile-estimation process. The GMC condition has also been proved for many widely used time-series models and a few queueing processes such as M/M/1 waiting times. We derive STS estimators for the associated variance parameter that are computed from nonoverlapping batches of outputs, and we combine those estimators to build asymptotically valid CIs. Simulated experimentation shows that our STS-based CI estimators have the potential to compare favorably with their conventional counterparts computed from nonoverlapping batches.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"1 1","pages":"289-300"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86907387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9383913
Vivianne Horsti dos Santos, Kathy Kotiadis, M. P. Scaparra
Hybrid Simulation (HS) has been applied to healthcare systems, but there is still limited literature and an opportunity to develop research. This review explores applications of HS in healthcare, to outline research gaps and foster new research in HS to solve complex real healthcare problems. The twelve application papers found through a systematic literature search covered nearly all hybrid combinations. Discrete Event (DES) and System Dynamics (SD) were found to be the most popular combination, and AnyLogic, the most used HS tool. We found that none of the papers we reviewed used the SD-ABS approach, which raises questions about the need and challenges associated with certain combinations. HS in healthcare applications, for the most part, are published in conference proceedings. We discuss opportunities for research and, in particular, the potential for HS application in problems related to communicable disease and healthcare services planning.
{"title":"A Review of Hybrid Simulation in Healthcare","authors":"Vivianne Horsti dos Santos, Kathy Kotiadis, M. P. Scaparra","doi":"10.1109/WSC48552.2020.9383913","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383913","url":null,"abstract":"Hybrid Simulation (HS) has been applied to healthcare systems, but there is still limited literature and an opportunity to develop research. This review explores applications of HS in healthcare, to outline research gaps and foster new research in HS to solve complex real healthcare problems. The twelve application papers found through a systematic literature search covered nearly all hybrid combinations. Discrete Event (DES) and System Dynamics (SD) were found to be the most popular combination, and AnyLogic, the most used HS tool. We found that none of the papers we reviewed used the SD-ABS approach, which raises questions about the need and challenges associated with certain combinations. HS in healthcare applications, for the most part, are published in conference proceedings. We discuss opportunities for research and, in particular, the potential for HS application in problems related to communicable disease and healthcare services planning.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"40 1","pages":"1004-1015"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87142152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9384096
M. Polter, P. Katranuschkov, R. Scherer
A generic process for simulation-based system identification for civil engineering problems is presented. It is iterative and contains a feedback loop for the continuous refinement of the system, taking into account the sensor values of the real object. The process was implemented in a generic workflow engine that can be integrated into software systems and adapted to specific application scenarios. An exemplary implementation in the context of a cyber-physical system for dynamic adaptation of production processes shows the feasibility and the advantages of the developed concept.
{"title":"A Generic Workflow Engine for Iterative, Simulation-Based Non-Linear System Identifications","authors":"M. Polter, P. Katranuschkov, R. Scherer","doi":"10.1109/WSC48552.2020.9384096","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384096","url":null,"abstract":"A generic process for simulation-based system identification for civil engineering problems is presented. It is iterative and contains a feedback loop for the continuous refinement of the system, taking into account the sensor values of the real object. The process was implemented in a generic workflow engine that can be integrated into software systems and adapted to specific application scenarios. An exemplary implementation in the context of a cyber-physical system for dynamic adaptation of production processes shows the feasibility and the advantages of the developed concept.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"1 1","pages":"2671-2682"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86148147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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