Pub Date : 2020-12-14DOI: 10.1109/WSC48552.2020.9384126
B. Sherafat, Abbas Rashidi, S. Asgari
Construction equipment performance monitoring can support detecting equipment idle time, estimating equipment productivity rates, and evaluating the cycle time of activities. Each equipment generates unique sound patterns that can be used for equipment activity detection. In the last decade, several audio-based methods are introduced to automate the process of equipment activity recognition. Most of these methods only consider single-equipment scenarios. The real construction job site consists of multiple machines working simultaneously. Thus, there is an increasing demand for advanced techniques to separate different equipment sound sources and evaluate each equipment’s productivity separately. In this study, six beamforming-based approaches for construction equipment sound source separation are implemented and evaluated using real construction job site data. The results show that Frost beamformer and time-delay Linear Constraint Minimum Variance (LCMV) generate outputs with array gains of more than 4.0, which are more reliable than the other four beamforming techniques for equipment sound separation.
{"title":"Comparison of Different Beamforming-Based Approaches for Sound Source Separation of Multiple Heavy Equipment at Construction Job Sites","authors":"B. Sherafat, Abbas Rashidi, S. Asgari","doi":"10.1109/WSC48552.2020.9384126","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384126","url":null,"abstract":"Construction equipment performance monitoring can support detecting equipment idle time, estimating equipment productivity rates, and evaluating the cycle time of activities. Each equipment generates unique sound patterns that can be used for equipment activity detection. In the last decade, several audio-based methods are introduced to automate the process of equipment activity recognition. Most of these methods only consider single-equipment scenarios. The real construction job site consists of multiple machines working simultaneously. Thus, there is an increasing demand for advanced techniques to separate different equipment sound sources and evaluate each equipment’s productivity separately. In this study, six beamforming-based approaches for construction equipment sound source separation are implemented and evaluated using real construction job site data. The results show that Frost beamformer and time-delay Linear Constraint Minimum Variance (LCMV) generate outputs with array gains of more than 4.0, which are more reliable than the other four beamforming techniques for equipment sound separation.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"63 1","pages":"2435-2446"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90346559","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/WSC48552.2020.9384015
P. Wan, M. Fu
Using Monte Carlo simulation, this paper proposes a new algorithm for estimating the arc criticalities of stochastic activity networks. The algorithm is based on the following result: given the length of all arcs in a network except for the one arc of interest, which is on the critical path (longest path) if and only if its length is greater than a threshold. Therefore, the new algorithm is named Threshold Arc Criticality (TAC). By applying Infinitesimal Perturbation Analysis (IPA) to TAC, an unbiased estimator of the stochastic derivative of the arc criticalities with respect to parameters of arc length distributions can be derived. With a valid estimator of stochastic derivative of arc criticalities, sensitivity analysis of arc criticalities is carried out via simulation of a small test network.
{"title":"Sensitivity Analysis of ARC Criticalities in Stochastic Activity Networks","authors":"P. Wan, M. Fu","doi":"10.1109/WSC48552.2020.9384015","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384015","url":null,"abstract":"Using Monte Carlo simulation, this paper proposes a new algorithm for estimating the arc criticalities of stochastic activity networks. The algorithm is based on the following result: given the length of all arcs in a network except for the one arc of interest, which is on the critical path (longest path) if and only if its length is greater than a threshold. Therefore, the new algorithm is named Threshold Arc Criticality (TAC). By applying Infinitesimal Perturbation Analysis (IPA) to TAC, an unbiased estimator of the stochastic derivative of the arc criticalities with respect to parameters of arc length distributions can be derived. With a valid estimator of stochastic derivative of arc criticalities, sensitivity analysis of arc criticalities is carried out via simulation of a small test network.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"19 1","pages":"2911-2922"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88810781","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/WSC48552.2020.9384019
Xiao Jin, Yichi Shen, L. Lee, E. P. Chew, C. Shoemaker
We propose a new method for solving continuous contextual simulation optimization with a single observation. By adopting the estimation on the large deviation rate in the contextual ranking and selection problem, we transfer the old theorem to the continuous setting using a shrinking ball inspired construct. Through the estimation of the rate, the new method is expected to achieve the optimal performance in this new problem setting. Brief numerical experiments are conducted and show significant advantages of our method against the uniform sampling scheme.
{"title":"A Hybrid of Shrinking Ball Method and Optimal Large Deviation Rate Estimation in Continuous Contextual Simulation Optimization with Single Observation","authors":"Xiao Jin, Yichi Shen, L. Lee, E. P. Chew, C. Shoemaker","doi":"10.1109/WSC48552.2020.9384019","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384019","url":null,"abstract":"We propose a new method for solving continuous contextual simulation optimization with a single observation. By adopting the estimation on the large deviation rate in the contextual ranking and selection problem, we transfer the old theorem to the continuous setting using a shrinking ball inspired construct. Through the estimation of the rate, the new method is expected to achieve the optimal performance in this new problem setting. Brief numerical experiments are conducted and show significant advantages of our method against the uniform sampling scheme.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"1 1","pages":"2996-3007"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88923251","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/WSC48552.2020.9384002
Haidong Li, H. Lam
We consider stochastic gradient estimation when only noisy function evaluations are available. Central finite-difference scheme is a common method in this setting, which involves generating samples under perturbed inputs. Though it is widely known how to select the perturbation size to achieve the optimal order of the error, exactly achieving the optimal first-order error, which we call asymptotic optimality, is considered much more challenging and not attempted in practice. In this paper, we provide evidence that designing asymptotically optimal estimator is practically possible. In particular, we propose a new two-stage scheme that first estimates the required parameter in the perturbation size, followed by running finite-difference based on the estimated parameter in the first stage. Both theory and numerical experiments demonstrate the optimality of the proposed estimator and the robustness over conventional finite-difference schemes based on ad hoc tuning.
{"title":"Optimally Tuning Finite-Difference Estimators","authors":"Haidong Li, H. Lam","doi":"10.1109/WSC48552.2020.9384002","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384002","url":null,"abstract":"We consider stochastic gradient estimation when only noisy function evaluations are available. Central finite-difference scheme is a common method in this setting, which involves generating samples under perturbed inputs. Though it is widely known how to select the perturbation size to achieve the optimal order of the error, exactly achieving the optimal first-order error, which we call asymptotic optimality, is considered much more challenging and not attempted in practice. In this paper, we provide evidence that designing asymptotically optimal estimator is practically possible. In particular, we propose a new two-stage scheme that first estimates the required parameter in the perturbation size, followed by running finite-difference based on the estimated parameter in the first stage. Both theory and numerical experiments demonstrate the optimality of the proposed estimator and the robustness over conventional finite-difference schemes based on ad hoc tuning.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"51 1","pages":"457-468"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91390653","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/WSC48552.2020.9383958
J. Bai, J. Brunner, Steven Gerstmeyr
The intensive care unit is one of the bottleneck resources in the hospital, due to the fact that the demand grows much faster than the capacity. The pressure on intensive care unit managers to use resources efficiently and effectively increases. Therefore, optimal management policies are required. In this work, we evaluate eleven commonly referred policies from the literature and compare their performance by nine key performance indicators in different perspectives, such as utilization, patient health status, and profit of the hospital. The 30 most frequently occurring patient paths, based on the practical dataset of more than 75,000 patient records from a German teaching hospital, are simulated. According to our results, increasing the capacity and treating the patients in well-equipped intermediate care units performed better in the medical perspective, while the early discharge policy performs well when the capacity is limited. Furthermore, the COVID-19 scenario could be integrated into the model.
{"title":"Simulation and Evaluation of ICU Management Policies","authors":"J. Bai, J. Brunner, Steven Gerstmeyr","doi":"10.1109/WSC48552.2020.9383958","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383958","url":null,"abstract":"The intensive care unit is one of the bottleneck resources in the hospital, due to the fact that the demand grows much faster than the capacity. The pressure on intensive care unit managers to use resources efficiently and effectively increases. Therefore, optimal management policies are required. In this work, we evaluate eleven commonly referred policies from the literature and compare their performance by nine key performance indicators in different perspectives, such as utilization, patient health status, and profit of the hospital. The 30 most frequently occurring patient paths, based on the practical dataset of more than 75,000 patient records from a German teaching hospital, are simulated. According to our results, increasing the capacity and treating the patients in well-equipped intermediate care units performed better in the medical perspective, while the early discharge policy performs well when the capacity is limited. Furthermore, the COVID-19 scenario could be integrated into the model.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"19 1","pages":"864-875"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83703656","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/WSC48552.2020.9383905
Yuanlu Bai, H. Lam
We consider the estimation of rare-event probabilities using sample proportions output by naive Monte Carlo. Unlike using variance reduction techniques, this naive estimator does not have a priori relative efficiency guarantee. On the other hand, due to the recent surge of sophisticated rare-event problems arising in safety evaluations of intelligent systems, efficiency-guaranteed variance reduction may face implementation challenges, which motivate one to look at naive estimators. In this paper we investigate this naive rare-event estimator, particularly its conservativeness level and the guarantees in using it to construct confidence bounds for the target probability. We show that the half-width of a valid confidence interval is typically scaled proportional to the magnitude of the target probability and inverse square-root with the number of positive outcomes in the Monte Carlo. We also derive and compare several valid confidence bounds constructed from various techniques.
{"title":"On the Error of Naive Rare-Event Monte Carlo Estimator","authors":"Yuanlu Bai, H. Lam","doi":"10.1109/WSC48552.2020.9383905","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383905","url":null,"abstract":"We consider the estimation of rare-event probabilities using sample proportions output by naive Monte Carlo. Unlike using variance reduction techniques, this naive estimator does not have a priori relative efficiency guarantee. On the other hand, due to the recent surge of sophisticated rare-event problems arising in safety evaluations of intelligent systems, efficiency-guaranteed variance reduction may face implementation challenges, which motivate one to look at naive estimators. In this paper we investigate this naive rare-event estimator, particularly its conservativeness level and the guarantees in using it to construct confidence bounds for the target probability. We show that the half-width of a valid confidence interval is typically scaled proportional to the magnitude of the target probability and inverse square-root with the number of positive outcomes in the Monte Carlo. We also derive and compare several valid confidence bounds constructed from various techniques.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"147 1","pages":"397-408"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83805220","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/WSC48552.2020.9383949
Michael Wagner, H. Cornet, D. Eckhoff, Philipp Andelfinger, Wentong Cai, A. Knoll
A key challenge in the implementation of novel public transport systems is to maintain usability over a broad spectrum of potential users. Transport systems that increasingly emphasise dynamic adjustment to changing passenger numbers and destinations over time cannot rely on static schedules and routes like traditional systems do. In this work we are investigating the use of agent-based crowd simulation to evaluate how different passenger guidance systems affect agent navigation in a public transport hub. We study the effects of different digital signage placement strategies in terms of crowding and walking times and also analyse how the introduction of mobile phone guidance systems affects these metrics. Our results show that crowd simulation is a cost and time-efficient tool for the evaluation of guidance systems in public transport spaces that can also support the design of bus schedules and bay assignments.
{"title":"Evaluation of Guidance Systems at Dynamic Public Transport Hubs Using Crowd Simulation","authors":"Michael Wagner, H. Cornet, D. Eckhoff, Philipp Andelfinger, Wentong Cai, A. Knoll","doi":"10.1109/WSC48552.2020.9383949","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383949","url":null,"abstract":"A key challenge in the implementation of novel public transport systems is to maintain usability over a broad spectrum of potential users. Transport systems that increasingly emphasise dynamic adjustment to changing passenger numbers and destinations over time cannot rely on static schedules and routes like traditional systems do. In this work we are investigating the use of agent-based crowd simulation to evaluate how different passenger guidance systems affect agent navigation in a public transport hub. We study the effects of different digital signage placement strategies in terms of crowding and walking times and also analyse how the introduction of mobile phone guidance systems affects these metrics. Our results show that crowd simulation is a cost and time-efficient tool for the evaluation of guidance systems in public transport spaces that can also support the design of bus schedules and bay assignments.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"63 1","pages":"123-134"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83359542","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/WSC48552.2020.9384110
Haolin Feng, Zitian Li, Michelle M. Alvarado, Coralys M Colón-Morales
This study investigates how the variability of different stochastic elements affects the performance of operations at a Mohs Micrographic Surgery (MMS) clinic. MMS is a popular procedure to treat non-melanoma skin cancers. In MMS, the surgeon performs skin layer excisions on the patient one at a time, and the removed layer is then examined. If cancerous cells remain during examination, another excision will be conducted; otherwise the patient goes through wound repair before being discharged. Such repetitive excisions of thin layers lead to low re-occurrence rates and impressive post-surgery cosmetic results, but it requires uncertain amount of same-day surgeries which may lead to long patient waiting times and clinic overtime. We develop a simulation model to study the operational performance of an MMS clinic with a given appointment schedule used in practice. Our study reveals how the waiting time and clinic overtime is affected by different stochastic factors.
{"title":"A Simulation Study of Outpatient Surgery Clinic with Stochastic Patient Re-Entrance","authors":"Haolin Feng, Zitian Li, Michelle M. Alvarado, Coralys M Colón-Morales","doi":"10.1109/WSC48552.2020.9384110","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384110","url":null,"abstract":"This study investigates how the variability of different stochastic elements affects the performance of operations at a Mohs Micrographic Surgery (MMS) clinic. MMS is a popular procedure to treat non-melanoma skin cancers. In MMS, the surgeon performs skin layer excisions on the patient one at a time, and the removed layer is then examined. If cancerous cells remain during examination, another excision will be conducted; otherwise the patient goes through wound repair before being discharged. Such repetitive excisions of thin layers lead to low re-occurrence rates and impressive post-surgery cosmetic results, but it requires uncertain amount of same-day surgeries which may lead to long patient waiting times and clinic overtime. We develop a simulation model to study the operational performance of an MMS clinic with a given appointment schedule used in practice. Our study reveals how the waiting time and clinic overtime is affected by different stochastic factors.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"3 1","pages":"910-921"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83310820","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/WSC48552.2020.9384038
Xinyun Chen, Xiuwen Wang
As an extension of self-exciting Hawkes process, the multivariate Hawkes process models counting processes of different types of random events with mutual excitement. In this paper, we present a perfect sampling algorithm that can generate i.i.d. stationary sample paths of multivariate Hawkes process without any transient bias. In addition, we provide an explicit expression of algorithm complexity in model and algorithm parameters and provide numerical schemes to find the optimal parameter set that minimizes the complexity of the perfect sampling algorithm.
{"title":"Perfect Sampling of Multivariate Hawkes Processes","authors":"Xinyun Chen, Xiuwen Wang","doi":"10.1109/WSC48552.2020.9384038","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9384038","url":null,"abstract":"As an extension of self-exciting Hawkes process, the multivariate Hawkes process models counting processes of different types of random events with mutual excitement. In this paper, we present a perfect sampling algorithm that can generate i.i.d. stationary sample paths of multivariate Hawkes process without any transient bias. In addition, we provide an explicit expression of algorithm complexity in model and algorithm parameters and provide numerical schemes to find the optimal parameter set that minimizes the complexity of the perfect sampling algorithm.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"3 1","pages":"469-480"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87399215","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/WSC48552.2020.9383902
Carlos Alberto Barrera Diaz, Tehseen Aslam, Amos H. C. Ng, Erik Flores-García, Magnus Wiktorsson
The purpose of this study is to analyze the use of Simulation-Based Multi-Objective Optimization (SMO) for Reconfigurable Manufacturing System Configuration Analysis (RMS-CA). In doing so, this study addresses the need for efficiently performing RMS-CA with respect to the limited time for decision-making in the industry, and investigates one of the salient problems of RMS-CA: determining the minimum number of machines necessary to satisfy the demand. The study adopts an NSGA II optimization algorithm and presents two contributions to existing literature. Firstly, the study proposes a series of steps for the use of SMO for RMS-CA and shows how to simultaneously maximize production throughput, minimize lead time, and buffer size. Secondly, the study presents a qualitative comparison with the prior work in RMS-CA and the proposed use of SMO; it discusses the advantages and challenges of using SMO and provides critical insight for production engineers and managers responsible for production system configuration.
{"title":"Simulation-Based Multi-Objective Optimization for Reconfigurable Manufacturing System Configurations Analysis","authors":"Carlos Alberto Barrera Diaz, Tehseen Aslam, Amos H. C. Ng, Erik Flores-García, Magnus Wiktorsson","doi":"10.1109/WSC48552.2020.9383902","DOIUrl":"https://doi.org/10.1109/WSC48552.2020.9383902","url":null,"abstract":"The purpose of this study is to analyze the use of Simulation-Based Multi-Objective Optimization (SMO) for Reconfigurable Manufacturing System Configuration Analysis (RMS-CA). In doing so, this study addresses the need for efficiently performing RMS-CA with respect to the limited time for decision-making in the industry, and investigates one of the salient problems of RMS-CA: determining the minimum number of machines necessary to satisfy the demand. The study adopts an NSGA II optimization algorithm and presents two contributions to existing literature. Firstly, the study proposes a series of steps for the use of SMO for RMS-CA and shows how to simultaneously maximize production throughput, minimize lead time, and buffer size. Secondly, the study presents a qualitative comparison with the prior work in RMS-CA and the proposed use of SMO; it discusses the advantages and challenges of using SMO and provides critical insight for production engineers and managers responsible for production system configuration.","PeriodicalId":6692,"journal":{"name":"2020 Winter Simulation Conference (WSC)","volume":"62 1","pages":"1527-1538"},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84733661","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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