This article presents a novel kinematic model and controller design for a mobile robot with four Centered Orientable Conventional (COC) wheels. When compared to non-conventional wheels, COC wheels perform better over rough terrain, are not subject to vertical chatter and offer better braking capability. However, COC wheels are pseudo-omnidirectional and subject to nonholonomic constraints. Several established modeling and control techniques define and control the Instantaneous Center of Rotation (ICR); however, this method involves singular configurations that are not trivial to eliminate. The proposed method uses a novel ICR-based kinematic model to avoid these singularities, and an ICR-based nonlinear controller for one ‘master’ wheel. The other ‘slave’ wheels simply track the resulting kinematic relationships between the ‘master’ wheel and the ICR. Thus, the nonlinear control problem is reduced from 12th to 3rd-order, becoming much more tractable. Simulations with a feedback linearization controller verify the approach.
{"title":"Instantaneous Center of Rotation-Based Master-Slave Kinematic Modeling and Control","authors":"V. Ramanathan, A. Zelenak, M. Pryor","doi":"10.1115/dscc2019-9123","DOIUrl":"https://doi.org/10.1115/dscc2019-9123","url":null,"abstract":"\u0000 This article presents a novel kinematic model and controller design for a mobile robot with four Centered Orientable Conventional (COC) wheels. When compared to non-conventional wheels, COC wheels perform better over rough terrain, are not subject to vertical chatter and offer better braking capability. However, COC wheels are pseudo-omnidirectional and subject to nonholonomic constraints. Several established modeling and control techniques define and control the Instantaneous Center of Rotation (ICR); however, this method involves singular configurations that are not trivial to eliminate. The proposed method uses a novel ICR-based kinematic model to avoid these singularities, and an ICR-based nonlinear controller for one ‘master’ wheel. The other ‘slave’ wheels simply track the resulting kinematic relationships between the ‘master’ wheel and the ICR. Thus, the nonlinear control problem is reduced from 12th to 3rd-order, becoming much more tractable. Simulations with a feedback linearization controller verify the approach.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88360532","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}
The practice of hybridizing energy storage systems is vital to high ramp rate power applications, in which energy storage systems are constrained by strict power and energy requirements. Hybrid energy storage is typically studied in the electrical and thermal domains separately, but due to the inherent link between electrical and thermal energy domains, it is necessary to examine hybrid energy storage in both domains simultaneously. In this paper, a combined electro-thermal energy storage system is modeled and simulated. Equivalent circuit and lumped-parameter models are used to facilitate control design. PI controllers are designed for both the electrical and thermal domains to demonstrate the ability to perform multi-domain energy management.
{"title":"A Hybrid Electro-Thermal Energy Storage System for High Ramp Rate Power Applications","authors":"Cary E. Laird, A. Alleyne","doi":"10.1115/dscc2019-9089","DOIUrl":"https://doi.org/10.1115/dscc2019-9089","url":null,"abstract":"\u0000 The practice of hybridizing energy storage systems is vital to high ramp rate power applications, in which energy storage systems are constrained by strict power and energy requirements. Hybrid energy storage is typically studied in the electrical and thermal domains separately, but due to the inherent link between electrical and thermal energy domains, it is necessary to examine hybrid energy storage in both domains simultaneously. In this paper, a combined electro-thermal energy storage system is modeled and simulated. Equivalent circuit and lumped-parameter models are used to facilitate control design. PI controllers are designed for both the electrical and thermal domains to demonstrate the ability to perform multi-domain energy management.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73733358","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}
We study the dynamic engine-generator optimal control problem with a goal of minimizing fuel consumption while delivering a requested average electrical power. By using an infinite-horizon formulation and explicitly minimizing fuel consumption, we avoid issues inherent with penalty-based and finite-horizon problems. The solution to the optimal control problem, found using dynamic programming and the successive approximation method, can be expressed as instantaneous non-linear state-feedback. This allows for trivial real-time control, typically requiring 10–20 CPU instructions per control period, a few bytes of RAM, and 5–20 KiB of nonvolatile memory. Simulation results for a passenger vehicle indicate a fuel consumption improvement in the region of 5–7% during the transient phase when compared with the class of controllers found in the industry. Bench-tests, where the optimal controller is executed in native hardware, show an improvement of 3.7%, primarily limited by unmodeled dynamics. Our specific choice of problem formulation, a guaranteed globally optimal solution, and trivial real-time control resolve many of the limitations with the current state of optimal engine-generator controllers.
{"title":"Optimal Transient Real-Time Engine-Generator Control in the Series-Hybrid Vehicle","authors":"Jonathan Lock, Rickard Arvidsson, T. McKelvey","doi":"10.1115/dscc2019-8964","DOIUrl":"https://doi.org/10.1115/dscc2019-8964","url":null,"abstract":"\u0000 We study the dynamic engine-generator optimal control problem with a goal of minimizing fuel consumption while delivering a requested average electrical power. By using an infinite-horizon formulation and explicitly minimizing fuel consumption, we avoid issues inherent with penalty-based and finite-horizon problems. The solution to the optimal control problem, found using dynamic programming and the successive approximation method, can be expressed as instantaneous non-linear state-feedback. This allows for trivial real-time control, typically requiring 10–20 CPU instructions per control period, a few bytes of RAM, and 5–20 KiB of nonvolatile memory. Simulation results for a passenger vehicle indicate a fuel consumption improvement in the region of 5–7% during the transient phase when compared with the class of controllers found in the industry. Bench-tests, where the optimal controller is executed in native hardware, show an improvement of 3.7%, primarily limited by unmodeled dynamics. Our specific choice of problem formulation, a guaranteed globally optimal solution, and trivial real-time control resolve many of the limitations with the current state of optimal engine-generator controllers.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86401128","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}
This paper proposes a control-oriented pressure wave model, utilizing outputs of a reaction-based two-zone engine combustion model developed earlier, to accurately predict the key knock characteristics. The model can be used for model-based knock prediction and control. An in-cylinder pressure wave model of oscillation magnitude decay is proposed and simplified to describe pressure oscillations due to knock combustion, and the boundary and initial conditions of the pressure wave model at knock onset are provided by the two-zone reaction-based combustion model. The proposed pressure wave model is calibrated using experimental data, and the chemical kinetic-based Arrhenius integral (ARI) and maximum amplitude of pressure oscillations (MAPO) are used as the evaluation criteria for predicting knock onset and intensity, and the knock frequency is studied with the fast Fourier transform (FFT). The calibrated model is validated for predicting knock onset timing, knock intensity and frequency. Simulation results are compared with the experimental ones to demonstrate the capability of predicting engine knock characteristics by the proposed model.
{"title":"A Real-Time Pressure Wave Model for Predicting Engine Knock","authors":"Ruixue C. Li, G. Zhu","doi":"10.1115/dscc2019-9147","DOIUrl":"https://doi.org/10.1115/dscc2019-9147","url":null,"abstract":"\u0000 This paper proposes a control-oriented pressure wave model, utilizing outputs of a reaction-based two-zone engine combustion model developed earlier, to accurately predict the key knock characteristics. The model can be used for model-based knock prediction and control. An in-cylinder pressure wave model of oscillation magnitude decay is proposed and simplified to describe pressure oscillations due to knock combustion, and the boundary and initial conditions of the pressure wave model at knock onset are provided by the two-zone reaction-based combustion model. The proposed pressure wave model is calibrated using experimental data, and the chemical kinetic-based Arrhenius integral (ARI) and maximum amplitude of pressure oscillations (MAPO) are used as the evaluation criteria for predicting knock onset and intensity, and the knock frequency is studied with the fast Fourier transform (FFT). The calibrated model is validated for predicting knock onset timing, knock intensity and frequency. Simulation results are compared with the experimental ones to demonstrate the capability of predicting engine knock characteristics by the proposed model.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86048381","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}
We present a new methodology for designing a heat exchanger that explicitly considers both static and transient performance characteristics. The proposed approach leverages 1) a highly detailed, albeit static model that captures the complex nonlinear relationship between heat exchanger geometry and heat transfer coefficients, and 2) a reduced-order dynamic model of the heat exchanger that approximates the geometry detailed in the static model. In order to optimize the component design for both static and transient performance metrics, pole locations of the corresponding linearized model are penalized in the cost function of the proposed optimization algorithm in order to move dominant poles further into the left half complex plane. Through a simulated case study for a shell and tube heat exchanger, we demonstrate how the proposed algorithm exploits the trade off between static design metrics, including mass and footprint, and the rate at which heat is removed from the primary fluid.
{"title":"Dynamic Design Optimization for Thermal Management: A Case Study on Shell and Tube Heat Exchangers","authors":"Austin L. Nash, Neera Jain","doi":"10.1115/dscc2019-9212","DOIUrl":"https://doi.org/10.1115/dscc2019-9212","url":null,"abstract":"\u0000 We present a new methodology for designing a heat exchanger that explicitly considers both static and transient performance characteristics. The proposed approach leverages 1) a highly detailed, albeit static model that captures the complex nonlinear relationship between heat exchanger geometry and heat transfer coefficients, and 2) a reduced-order dynamic model of the heat exchanger that approximates the geometry detailed in the static model. In order to optimize the component design for both static and transient performance metrics, pole locations of the corresponding linearized model are penalized in the cost function of the proposed optimization algorithm in order to move dominant poles further into the left half complex plane. Through a simulated case study for a shell and tube heat exchanger, we demonstrate how the proposed algorithm exploits the trade off between static design metrics, including mass and footprint, and the rate at which heat is removed from the primary fluid.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90648760","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}
This paper develops and demonstrates cooperative collision avoidance control on two robotic fish propelled by a servo motor and an ionic polymer-metal composite (IPMC)-driven fish tail. First, experiments conducted on a servo motor/IPMC-driven fish demonstrate an impulsive turning behavior in the fish’s trajectory under the application of a specific frequency, amplitude of the servo motor, and a constant voltage on the IPMC joint. These experiments validate the ‘back relaxation’ of the IPMC joint by observing the angular velocity and the centripetal acceleration of the fish. This impulsive turning speed due to the ‘back relaxation’ of IPMC joint is subsequently modeled by a transfer function and this transfer function is then integrated into the development of the collision avoidance laws for the fish. The collision avoidance control law utilizes the impulsive turning capability of the robotic fish. An experimental validation of the collision avoidance law is performed.
{"title":"Cooperative Collision Avoidance Control of Robotic Fish Propelled by a Servo/IPMC Driven Hybrid Tail","authors":"Xiongfeng Yi, Zheng Chen, A. Chakravarthy","doi":"10.1115/dscc2019-9228","DOIUrl":"https://doi.org/10.1115/dscc2019-9228","url":null,"abstract":"\u0000 This paper develops and demonstrates cooperative collision avoidance control on two robotic fish propelled by a servo motor and an ionic polymer-metal composite (IPMC)-driven fish tail. First, experiments conducted on a servo motor/IPMC-driven fish demonstrate an impulsive turning behavior in the fish’s trajectory under the application of a specific frequency, amplitude of the servo motor, and a constant voltage on the IPMC joint. These experiments validate the ‘back relaxation’ of the IPMC joint by observing the angular velocity and the centripetal acceleration of the fish. This impulsive turning speed due to the ‘back relaxation’ of IPMC joint is subsequently modeled by a transfer function and this transfer function is then integrated into the development of the collision avoidance laws for the fish. The collision avoidance control law utilizes the impulsive turning capability of the robotic fish. An experimental validation of the collision avoidance law is performed.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75642667","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}
This paper introduces a novel wearable full wrist exoskeleton designed for the alleviation of tremor in patients suffering from Parkinson’s Disease and Essential Tremor. The design introduces a structure to provide full observation of wrist kinematics as well as actuation in wrist flexion/extension and radial/ulnar deviation. To examine the feasibility of the design, the coupled dynamics of the device and the forearm is modeled via a general multibody framework. The dynamic analysis considers human motion, wrist stiffness, and tremor dynamics. The analysis of the model reveals that the identification of the wrist kinematics is indispensable for the controller design. Nonlinear regression based on the Levenberg-Marquardt algorithm has been applied to estimate the unknown parameters in a kinematic structural function designed to approximate the wrist kinematics, which leads to the construction of the control system framework. Finally, several simulation cases are demonstrated to conclude the study.
{"title":"On the Dynamics and Control of a Full Wrist Exoskeleton for Tremor Alleviation","authors":"Jiamin Wang, O. Barry, A. Kurdila, S. Vijayan","doi":"10.1115/dscc2019-9118","DOIUrl":"https://doi.org/10.1115/dscc2019-9118","url":null,"abstract":"\u0000 This paper introduces a novel wearable full wrist exoskeleton designed for the alleviation of tremor in patients suffering from Parkinson’s Disease and Essential Tremor. The design introduces a structure to provide full observation of wrist kinematics as well as actuation in wrist flexion/extension and radial/ulnar deviation. To examine the feasibility of the design, the coupled dynamics of the device and the forearm is modeled via a general multibody framework. The dynamic analysis considers human motion, wrist stiffness, and tremor dynamics. The analysis of the model reveals that the identification of the wrist kinematics is indispensable for the controller design. Nonlinear regression based on the Levenberg-Marquardt algorithm has been applied to estimate the unknown parameters in a kinematic structural function designed to approximate the wrist kinematics, which leads to the construction of the control system framework. Finally, several simulation cases are demonstrated to conclude the study.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72444175","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}
Kaian Chen, Zhaojian Li, Yan Wang, Jing Wang, Kai Wu, Dimitar Filev
In this paper, we treat the problem of online nonlinear system identification with parameter constraints. This approach is based upon our prior work on nonlinear system identification that exploits evolving Spatial-Temporal Filters (STF) to dynamically decompose system’s input/output space into a nonlinear combination of weighted local models. We extend the nonlinear system identification framework with the capability of dealing with linear equality and inequality parameter constraints. We leverage the gradient projection method in the local model parameter estimation process to inherently enforce the parameter constraints while retaining optimality. We apply the proposed algorithm to a turbo-charged gasoline engine system and promising results are demonstrated by experimental data.
{"title":"Online Nonlinear System Identification With Parameter Constraints: Application to Automotive Engine Systems","authors":"Kaian Chen, Zhaojian Li, Yan Wang, Jing Wang, Kai Wu, Dimitar Filev","doi":"10.1115/dscc2019-9092","DOIUrl":"https://doi.org/10.1115/dscc2019-9092","url":null,"abstract":"\u0000 In this paper, we treat the problem of online nonlinear system identification with parameter constraints. This approach is based upon our prior work on nonlinear system identification that exploits evolving Spatial-Temporal Filters (STF) to dynamically decompose system’s input/output space into a nonlinear combination of weighted local models. We extend the nonlinear system identification framework with the capability of dealing with linear equality and inequality parameter constraints. We leverage the gradient projection method in the local model parameter estimation process to inherently enforce the parameter constraints while retaining optimality. We apply the proposed algorithm to a turbo-charged gasoline engine system and promising results are demonstrated by experimental data.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82885436","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}
A foot interface may one day control a third arm to assist the hands with a difficult task, but the interface needs to be easy to use. Developing a good foot interface is challenging because of the need to provide support for the leg, allow the user to disengage with the interface without causing unwanted motion, and make it easy for the user to hold a set position. The addition of friction in the interface can enable the device to meet these goals without negatively affecting performance. Although teleoperation is a well explored area of research, relatively little research has been done that examines the effects of friction on the control interface. This paper presents an experiment in which two foot control interfaces are compared. One device uses friction and the other has no added friction, so there is little resistance to motion in any direction. The experiment uses a reaching task and a path-following task to compare the interfaces. The only statistically significant performance differences were that the friction interface reduced the time needed to stop at a target and reduced excess movement when stopping at a target. Also, subjects indicated a preference for the friction interface. The results show that friction can be added to a foot interface to support the device and user and provide some positive gains in performance.
{"title":"Comparison of Position Control With and Without Friction on a Foot Interface","authors":"B. Rudolph, Ryder C. Winck","doi":"10.1115/dscc2019-9019","DOIUrl":"https://doi.org/10.1115/dscc2019-9019","url":null,"abstract":"\u0000 A foot interface may one day control a third arm to assist the hands with a difficult task, but the interface needs to be easy to use. Developing a good foot interface is challenging because of the need to provide support for the leg, allow the user to disengage with the interface without causing unwanted motion, and make it easy for the user to hold a set position. The addition of friction in the interface can enable the device to meet these goals without negatively affecting performance. Although teleoperation is a well explored area of research, relatively little research has been done that examines the effects of friction on the control interface. This paper presents an experiment in which two foot control interfaces are compared. One device uses friction and the other has no added friction, so there is little resistance to motion in any direction. The experiment uses a reaching task and a path-following task to compare the interfaces. The only statistically significant performance differences were that the friction interface reduced the time needed to stop at a target and reduced excess movement when stopping at a target. Also, subjects indicated a preference for the friction interface. The results show that friction can be added to a foot interface to support the device and user and provide some positive gains in performance.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84411290","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}
Recently, the automobile industry has begun applying an increasing number of systems to recycling wasted energy. One area that demands further research is the recycling and storing of energy in car suspension systems, especially in terms of developing an electronic interface to keep energy flowing bidirectionally. An electronic interface was designed to facilitate control of regenerative forces and store energy after the rectification process. The electronic interface was designed to be a symmetrical-bridgeless boost converter, due to this mechanism having few components and requiring little control effort. The converter was created such that it kept the current and voltage in phase for the maximum power factor. The input into this controller was the generator voltage used to determine the polarity of the pulse-width modulation, considering external road disturbances. Thus, this combination of converter and controller was able to replace an active controller. Variable resistance could be further controlled to manipulate the suspension damping force.
{"title":"Design and Control of a Power-Electronic Interface for Regenerative Suspension Systems","authors":"Abdullah A. Algethami, Won-jong Kim","doi":"10.1115/dscc2019-9081","DOIUrl":"https://doi.org/10.1115/dscc2019-9081","url":null,"abstract":"\u0000 Recently, the automobile industry has begun applying an increasing number of systems to recycling wasted energy. One area that demands further research is the recycling and storing of energy in car suspension systems, especially in terms of developing an electronic interface to keep energy flowing bidirectionally. An electronic interface was designed to facilitate control of regenerative forces and store energy after the rectification process. The electronic interface was designed to be a symmetrical-bridgeless boost converter, due to this mechanism having few components and requiring little control effort. The converter was created such that it kept the current and voltage in phase for the maximum power factor. The input into this controller was the generator voltage used to determine the polarity of the pulse-width modulation, considering external road disturbances. Thus, this combination of converter and controller was able to replace an active controller. Variable resistance could be further controlled to manipulate the suspension damping force.","PeriodicalId":41412,"journal":{"name":"Mechatronic Systems and Control","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84527369","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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