Pub Date : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.02664
J. Borggaard, Kevin R. Pond, L. Zietsman
Abstract Over the past decade, a number of approaches have been put forth to improve the accuracy of projection-based reduced order models over parameter ranges. These can be classified as either i.) building a global basis that is suitable for a large parameter set by applying sampling strategies, ii.) identifying parameter dependent coefficient functions in the reduced order model, or iii.) changing the basis as parameters change. We propose a strategy that combines sampling with basis interpolation. We apply sampling strategies that identify suitable parameter values from which associated basis functions are interpolated at any parameter value in a region. While our approach has practical limits to roughly a handful of parameters, it has the advantage of achieving a desired level of accuracy in parametric reduced-order models of relatively small size. We present this method using a proper orthogonal decomposition model of a nonlinear partial differential equation with variable coefficients and initial conditions.
{"title":"Parametric Reduced Order Models Using Adaptive Sampling and Interpolation","authors":"J. Borggaard, Kevin R. Pond, L. Zietsman","doi":"10.3182/20140824-6-ZA-1003.02664","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.02664","url":null,"abstract":"Abstract Over the past decade, a number of approaches have been put forth to improve the accuracy of projection-based reduced order models over parameter ranges. These can be classified as either i.) building a global basis that is suitable for a large parameter set by applying sampling strategies, ii.) identifying parameter dependent coefficient functions in the reduced order model, or iii.) changing the basis as parameters change. We propose a strategy that combines sampling with basis interpolation. We apply sampling strategies that identify suitable parameter values from which associated basis functions are interpolated at any parameter value in a region. While our approach has practical limits to roughly a handful of parameters, it has the advantage of achieving a desired level of accuracy in parametric reduced-order models of relatively small size. We present this method using a proper orthogonal decomposition model of a nonlinear partial differential equation with variable coefficients and initial conditions.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"34 1","pages":"7773-7778"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76124398","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.00697
D. Rotondo, V. Puig, F. Nejjari
Abstract In this paper, virtual actuators are proposed as a Fault Tolerant Control (FTC) strategy for switching Linear Parameter Varying (LPV) systems subject to actuator faults. The overall solution relies on the addition of a virtual actuator block that keeps the stability and some desired performances without the need of retuning the nominal controller. It is shown that the design can be performed using polytopic techniques and Linear Matrix Inequalities (LMIs). Simulation results obtained with a four-wheeled omnidirectional mobile robot example are used to demonstrate the effectiveness of the proposed approach.
{"title":"A Virtual Actuator Approach for Fault Tolerant Control of Switching LPV Systems","authors":"D. Rotondo, V. Puig, F. Nejjari","doi":"10.3182/20140824-6-ZA-1003.00697","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.00697","url":null,"abstract":"Abstract In this paper, virtual actuators are proposed as a Fault Tolerant Control (FTC) strategy for switching Linear Parameter Varying (LPV) systems subject to actuator faults. The overall solution relies on the addition of a virtual actuator block that keeps the stability and some desired performances without the need of retuning the nominal controller. It is shown that the design can be performed using polytopic techniques and Linear Matrix Inequalities (LMIs). Simulation results obtained with a four-wheeled omnidirectional mobile robot example are used to demonstrate the effectiveness of the proposed approach.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"70 1","pages":"11667-11672"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76132949","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 : 2014-01-01DOI: 10.3182/20140313-3-IN-3024.00014
Reshma Susan Babu , Dr. U.P. Rajeev , R. Lethakumari
A simplified guidance law suitable for onboard implementation is derived in this paper exploiting the flatness property of the translational dynamics of a reusable launch vehicle (RLV). A tracking law to follow a reference trajectory profile is formulated. Dynamic inversion helps cancel the undesired dynamics and replaces the inerent dynamics of the vehicle by desired dynamics. Simulation studies indicate the effectiveness of the tracking law in case of nominal and off-nominal conditions. The behaviour of the tracking law for perturbations in initial conditions, aerodynamic coefficients and for physical variations such as mass is analyzed.
{"title":"Hybrid Guidance Algorithm using Flatness and Dynamic Inversion for RLV","authors":"Reshma Susan Babu , Dr. U.P. Rajeev , R. Lethakumari","doi":"10.3182/20140313-3-IN-3024.00014","DOIUrl":"10.3182/20140313-3-IN-3024.00014","url":null,"abstract":"<div><p>A simplified guidance law suitable for onboard implementation is derived in this paper exploiting the flatness property of the translational dynamics of a reusable launch vehicle (RLV). A tracking law to follow a reference trajectory profile is formulated. Dynamic inversion helps cancel the undesired dynamics and replaces the inerent dynamics of the vehicle by desired dynamics. Simulation studies indicate the effectiveness of the tracking law in case of nominal and off-nominal conditions. The behaviour of the tracking law for perturbations in initial conditions, aerodynamic coefficients and for physical variations such as mass is analyzed.</p></div>","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"47 1","pages":"Pages 7-13"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3182/20140313-3-IN-3024.00014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76150041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.00929
I. Manuel, A. Bishop
Abstract We present a Monte Carlo solution to the distributed data fusion problem and apply it to distributed particle filtering. The consensus-based fusion algorithm is iterative and it involves the exchange and fusion of empirical posterior densities between neighbouring agents. As the fusion method is Monte Carlo based it is naturally applicable to distributed particle filtering. Furthermore, the fusion method is applicable to a large class of networks including networks with cycles and dynamic topologies. We demonstrate both distributed fusion and distributed particle filtering by simulating the algorithms on randomly generated graphs.
{"title":"Distributed Monte Carlo information fusion and distributed particle filtering","authors":"I. Manuel, A. Bishop","doi":"10.3182/20140824-6-ZA-1003.00929","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.00929","url":null,"abstract":"Abstract We present a Monte Carlo solution to the distributed data fusion problem and apply it to distributed particle filtering. The consensus-based fusion algorithm is iterative and it involves the exchange and fusion of empirical posterior densities between neighbouring agents. As the fusion method is Monte Carlo based it is naturally applicable to distributed particle filtering. Furthermore, the fusion method is applicable to a large class of networks including networks with cycles and dynamic topologies. We demonstrate both distributed fusion and distributed particle filtering by simulating the algorithms on randomly generated graphs.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"111 1","pages":"8681-8688"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75010070","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.02156
K. Lunze, B. Misgeld, S. Leonhardt
Abstract This paper presents the results of our recent blood glucose control trials with diabetic Gottingen minipigs. In particular, we describe our new switching hybrid control algorithm which uses different sampling intervals and insulin application strategies for daytime and night phases. The experimental results of the control application to two animals are given and compared with manual insulin treatment. Both strategies for glucose regulation result in comparable blood glucose trajectories even though meals were not announced to the controller but were taken into account in the manual protocol.
{"title":"Switching Hybrid Control of Blood Glucose in Diabetic Göttingen Minipigs","authors":"K. Lunze, B. Misgeld, S. Leonhardt","doi":"10.3182/20140824-6-ZA-1003.02156","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.02156","url":null,"abstract":"Abstract This paper presents the results of our recent blood glucose control trials with diabetic Gottingen minipigs. In particular, we describe our new switching hybrid control algorithm which uses different sampling intervals and insulin application strategies for daytime and night phases. The experimental results of the control application to two animals are given and compared with manual insulin treatment. Both strategies for glucose regulation result in comparable blood glucose trajectories even though meals were not announced to the controller but were taken into account in the manual protocol.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"9 1","pages":"10156-10161"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75035847","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.02126
R. Kammerer, R. Obermaisser, Mino Sharkhawy
Abstract In many application domains there is an increasing trend for mixed-criticality systems with functions of different assurance levels on shared computing platforms. Today's CAN-based platforms do not support the requirements of mixed-criticality systems. A single CAN bus provides low cost, real-time support and flexibility for applications where the communication service is not safety-relevant. Fault-tolerance extensions for CAN impose incompatibility to legacy applications, high cost and overhead for the entire CAN communication. This paper introduces a CAN infrastructure for fault isolation and selective fault-tolerance, which permits a balanced trade-off between cost and fault-tolerance for each subsystem of a mixed-criticality system. We introduce replicated CAN routers that perform fault isolation based on a priori knowledge of the permitted behavior of CAN nodes. Fault masking is supported selectively through the redundant transmission of messages from safety-critical subsystems. The CAN routers perform input agreement on pending messages for replica deterministic behavior, as well as output agreement on the delivery status of messages. Software layers hide the fault-tolerance mechanisms to establish compatibility to legacy software. The benefits of the proposed communication infrastructure are demonstrated in a simulation of an example system.
{"title":"Mixed-Criticality Systems based on a CAN Router with Support for Fault Isolation and Selective Fault-Tolerance","authors":"R. Kammerer, R. Obermaisser, Mino Sharkhawy","doi":"10.3182/20140824-6-ZA-1003.02126","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.02126","url":null,"abstract":"Abstract In many application domains there is an increasing trend for mixed-criticality systems with functions of different assurance levels on shared computing platforms. Today's CAN-based platforms do not support the requirements of mixed-criticality systems. A single CAN bus provides low cost, real-time support and flexibility for applications where the communication service is not safety-relevant. Fault-tolerance extensions for CAN impose incompatibility to legacy applications, high cost and overhead for the entire CAN communication. This paper introduces a CAN infrastructure for fault isolation and selective fault-tolerance, which permits a balanced trade-off between cost and fault-tolerance for each subsystem of a mixed-criticality system. We introduce replicated CAN routers that perform fault isolation based on a priori knowledge of the permitted behavior of CAN nodes. Fault masking is supported selectively through the redundant transmission of messages from safety-critical subsystems. The CAN routers perform input agreement on pending messages for replica deterministic behavior, as well as output agreement on the delivery status of messages. Software layers hide the fault-tolerance mechanisms to establish compatibility to legacy software. The benefits of the proposed communication infrastructure are demonstrated in a simulation of an example system.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"142 1","pages":"12284-12292"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75045238","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.00248
Zhuo Wang, Derong Liu
Abstract In this paper, we develop data-based methods to analyze the characteristics of linear discrete-time systems, which have unknown parameter matrices. These characteristics include output controllability, asymptotic stability of the equilibrium point, bounded-input bounded- state stability, and bounded-input bounded-output stability. Our methods only use measured state and output data to verify the system properties. They are direct analysis methods and do not need to identify the unknown parameter matrices. These data-based methods not only can avoid identification errors, but also have lower computational complexity than traditional model-based analysis approaches.
{"title":"Data-Based Characteristics Analysis for Linear Discrete-Time Systems","authors":"Zhuo Wang, Derong Liu","doi":"10.3182/20140824-6-ZA-1003.00248","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.00248","url":null,"abstract":"Abstract In this paper, we develop data-based methods to analyze the characteristics of linear discrete-time systems, which have unknown parameter matrices. These characteristics include output controllability, asymptotic stability of the equilibrium point, bounded-input bounded- state stability, and bounded-input bounded-output stability. Our methods only use measured state and output data to verify the system properties. They are direct analysis methods and do not need to identify the unknown parameter matrices. These data-based methods not only can avoid identification errors, but also have lower computational complexity than traditional model-based analysis approaches.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"127 1","pages":"4993-4998"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72684492","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.02410
A. Crespo, M. Masmano, J. Coronel, S. Peiró, P. Balbastre, J. Simó
Abstract Multi-core processors are increasingly being considered to provide the performance required by future safety critical systems. In some domains like space, it is specially significant due to the processor technology frequency is limited by the presence of radiation. In that case, the way to increase computing power can be achieved by the use of multi-core systems. There is a number of challenges involved in the migration to multi-core processor architectures in safety-critical embedded systems domain which are still unresolved and which contribute to increase the complexity of the design. Even if multi-core processors may offer several benefits to embedded systems, their use is not straightforward. Virtualization techniques maturity have reach the level to offer guarantees in critical systems. In this paper, we present a multi-core hypervisor for mixed-criticality applications as one of the results of the MultiPARTES project. The paper analyse the design and implementation of XtratuM for multi-core and details a performance analysis to determine the overheads incurred by the virtualization layer and presents some results when shared resources are considered.
{"title":"Multicore partitioned systems based on hypervisor","authors":"A. Crespo, M. Masmano, J. Coronel, S. Peiró, P. Balbastre, J. Simó","doi":"10.3182/20140824-6-ZA-1003.02410","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.02410","url":null,"abstract":"Abstract Multi-core processors are increasingly being considered to provide the performance required by future safety critical systems. In some domains like space, it is specially significant due to the processor technology frequency is limited by the presence of radiation. In that case, the way to increase computing power can be achieved by the use of multi-core systems. There is a number of challenges involved in the migration to multi-core processor architectures in safety-critical embedded systems domain which are still unresolved and which contribute to increase the complexity of the design. Even if multi-core processors may offer several benefits to embedded systems, their use is not straightforward. Virtualization techniques maturity have reach the level to offer guarantees in critical systems. In this paper, we present a multi-core hypervisor for mixed-criticality applications as one of the results of the MultiPARTES project. The paper analyse the design and implementation of XtratuM for multi-core and details a performance analysis to determine the overheads incurred by the virtualization layer and presents some results when shared resources are considered.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"281 1","pages":"12293-12298"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72696152","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.02511
Y. Bayiz, Robert Babuška
Abstract Reinforcement Learning (RL) algorithms can learn optimal control laws for nonlinear dynamic systems without relying on a mathematical model of the system to be controlled. While RL can in principle discover control laws from scratch, by solely interacting with the process, in practice this does not yield any significant advantages. Learning control laws from scratch is lengthy and may lead to system damage due to the trial and error nature of the learning process. In this paper, we adopt a different and largely unexplored approach: a nominal control law is used to achieve reasonable, yet suboptimal, performance and a RL agent is trained to act as a nonlinear compensator whose task is to improve upon the performance of the nominal controller. The RL agent learns by means of an actor-critic algorithm using a plant model acquired on-line, alongside the critic and actor. Fuzzy approximators are employed to represent all the adjustable components of the learning scheme. One advantage of fuzzy approximators is the straightforward way in which they allow for the inclusion of prior knowledge. The proposed control scheme is applied to a reference tracking problem of 1-DOF robot arm influenced by an unknown payload disturbance due to gravity. The nominal controller is a PD controller, which is unable to properly compensate the effect of the disturbance considered. Simulation results indicate that the novel method is able to learn to compensate the disturbance for any reference angle varying throughout the experiment.
{"title":"Nonlinear Disturbance Compensation and Reference Tracking via Reinforcement Learning with Fuzzy Approximators","authors":"Y. Bayiz, Robert Babuška","doi":"10.3182/20140824-6-ZA-1003.02511","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.02511","url":null,"abstract":"Abstract Reinforcement Learning (RL) algorithms can learn optimal control laws for nonlinear dynamic systems without relying on a mathematical model of the system to be controlled. While RL can in principle discover control laws from scratch, by solely interacting with the process, in practice this does not yield any significant advantages. Learning control laws from scratch is lengthy and may lead to system damage due to the trial and error nature of the learning process. In this paper, we adopt a different and largely unexplored approach: a nominal control law is used to achieve reasonable, yet suboptimal, performance and a RL agent is trained to act as a nonlinear compensator whose task is to improve upon the performance of the nominal controller. The RL agent learns by means of an actor-critic algorithm using a plant model acquired on-line, alongside the critic and actor. Fuzzy approximators are employed to represent all the adjustable components of the learning scheme. One advantage of fuzzy approximators is the straightforward way in which they allow for the inclusion of prior knowledge. The proposed control scheme is applied to a reference tracking problem of 1-DOF robot arm influenced by an unknown payload disturbance due to gravity. The nominal controller is a PD controller, which is unable to properly compensate the effect of the disturbance considered. Simulation results indicate that the novel method is able to learn to compensate the disturbance for any reference angle varying throughout the experiment.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"32 1","pages":"5393-5398"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72698979","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 : 2014-01-01DOI: 10.3182/20140824-6-ZA-1003.00125
A. Bobtsov, S. Kolyubin, A. Pyrkin, A. Kapitonov, N. Nikolaev
Abstract In this paper we consider the problem of output control of nonlinear systems in the presence of structural disturbances caused by so called unmodelled dynamics. This paper develops results published in Bobtsov (2002). In Bobtsov (2002) conditions of efficiency of consecutive compensator were found for the case of output stabilization of linear parametrically uncertain plant under conditions of unmodelled asymptotically stable dynamics. We added disturbances as smooth nonlinear function meeting the conditions of sector restriction to the model and synthesized regulator for this case.
{"title":"Output Control of Nonlinear Systems with Unmodelled Dynamics1","authors":"A. Bobtsov, S. Kolyubin, A. Pyrkin, A. Kapitonov, N. Nikolaev","doi":"10.3182/20140824-6-ZA-1003.00125","DOIUrl":"https://doi.org/10.3182/20140824-6-ZA-1003.00125","url":null,"abstract":"Abstract In this paper we consider the problem of output control of nonlinear systems in the presence of structural disturbances caused by so called unmodelled dynamics. This paper develops results published in Bobtsov (2002). In Bobtsov (2002) conditions of efficiency of consecutive compensator were found for the case of output stabilization of linear parametrically uncertain plant under conditions of unmodelled asymptotically stable dynamics. We added disturbances as smooth nonlinear function meeting the conditions of sector restriction to the model and synthesized regulator for this case.","PeriodicalId":13260,"journal":{"name":"IFAC Proceedings Volumes","volume":"13 1","pages":"1302-1307"},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74985313","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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