Pub Date : 2001-11-11DOI: 10.1115/imece2001/dsc-24634
M. Bedillion, W. Messner, H. Choset
The Modular Distributed Manipulator System (MDMS) is an array of actuators that is capable of manipulating objects in the plane [1]. This paper derives equations of motion for the coupled dynamics of the MDMS actuators and objects riding upon it, and it derives feedforward control strategies for this multi-input, three-output system. Unlike previous work in which traction forces were generated using viscous friction caused by sliding contact between the manipulated object and the actuators, this paper considers traction forces generated by no-slip rolling contact. This approach allows more precise manipulation, because object positions and orientations and their time derivatives can be determined by wheel encoder information. The dynamic equations account for the electromechanical dynamics of each actuator and the coupling between them and the translational and rotational dynamics of the manipulated object. This paper then presents two different feedforward control strategies based on minimizing the sum of the squares of the inputs or minimizing the total system power.
{"title":"Rolling Contact Dynamics and Optimal Feedforward Control for the Modular Distributed Manipulator","authors":"M. Bedillion, W. Messner, H. Choset","doi":"10.1115/imece2001/dsc-24634","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24634","url":null,"abstract":"\u0000 The Modular Distributed Manipulator System (MDMS) is an array of actuators that is capable of manipulating objects in the plane [1]. This paper derives equations of motion for the coupled dynamics of the MDMS actuators and objects riding upon it, and it derives feedforward control strategies for this multi-input, three-output system. Unlike previous work in which traction forces were generated using viscous friction caused by sliding contact between the manipulated object and the actuators, this paper considers traction forces generated by no-slip rolling contact. This approach allows more precise manipulation, because object positions and orientations and their time derivatives can be determined by wheel encoder information. The dynamic equations account for the electromechanical dynamics of each actuator and the coupling between them and the translational and rotational dynamics of the manipulated object. This paper then presents two different feedforward control strategies based on minimizing the sum of the squares of the inputs or minimizing the total system power.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88408970","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24609
Shuguang Huang, J. Schimmels
In this paper, the quasistatic motion of an elastically suspended, unilaterally constrained rigid body is studied. The motion of the rigid body is determined, in part, by the position controlled motion of its support base and the behavior of the elastic suspension that couples the part to the support. The motion is also determined, in part, by contact with a frictional surface that both couples the rigid body to unilateral constraint surfaces and generates a friction force. The unknown friction force, however, is determined in part by the unknown direction of the rigid body motion. We derive a solvable set of equations that simultaneously determines both the friction force and the resulting rigid body motion. This set of equations requires that the friction and motion at the point of contact are oppositely directed. Solution involves the use of rigid body kinematics, the Coulomb friction coefficient, the commanded motion of the support, and the spatial elastic behavior of the coupling.
{"title":"The Motion of a Compliantly Suspended Rigid Body Constrained by a Frictional Surface","authors":"Shuguang Huang, J. Schimmels","doi":"10.1115/imece2001/dsc-24609","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24609","url":null,"abstract":"\u0000 In this paper, the quasistatic motion of an elastically suspended, unilaterally constrained rigid body is studied. The motion of the rigid body is determined, in part, by the position controlled motion of its support base and the behavior of the elastic suspension that couples the part to the support. The motion is also determined, in part, by contact with a frictional surface that both couples the rigid body to unilateral constraint surfaces and generates a friction force. The unknown friction force, however, is determined in part by the unknown direction of the rigid body motion. We derive a solvable set of equations that simultaneously determines both the friction force and the resulting rigid body motion. This set of equations requires that the friction and motion at the point of contact are oppositely directed. Solution involves the use of rigid body kinematics, the Coulomb friction coefficient, the commanded motion of the support, and the spatial elastic behavior of the coupling.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78464275","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24624
O. Bruneau, Fethi Ben Ouezdou, J. Fontaine
This article describes a method to design humanoid robots and to generate their dynamic gaits. Firstly, the global design process which defines structures able to carry out dynamic locomotion tasks is explained. Secondly, a set of leg mechanisms are described to generate these tasks. The third section describes a method to produce intrinsic smooth motions for fest walking gaits of bipedal robots having different leg mechanisms. Finally, some simulation results are given.
{"title":"An Approach for the Design of Walking Humanoid Robots Having Different Leg Mechanisms and Using Dynamic Gaits","authors":"O. Bruneau, Fethi Ben Ouezdou, J. Fontaine","doi":"10.1115/imece2001/dsc-24624","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24624","url":null,"abstract":"\u0000 This article describes a method to design humanoid robots and to generate their dynamic gaits. Firstly, the global design process which defines structures able to carry out dynamic locomotion tasks is explained. Secondly, a set of leg mechanisms are described to generate these tasks. The third section describes a method to produce intrinsic smooth motions for fest walking gaits of bipedal robots having different leg mechanisms. Finally, some simulation results are given.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84761783","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24590
Cheol W. Lee, T. Choi, Y. Shin
This paper presents a generalized modeling approach to modeling of complex manufacturing processes. Fuzzy basis function networks with a novel training algorithm are used to capture the cause-effect relationships of complex manufacturing processes. The modeling scheme allows for utilization of the existing knowledge in the form of analytical models, experimental data and heuristic rules in developing a suitable model. The method is implemented for the surface grinding processes based on the hierarchical structure of fuzzy basis function networks proposed by Lee and Shin [21]. Process models for surface roughness and residual stress are developed based on the available grinding model structures with a small number of experimental data to demonstrate the concept. The accuracy of developed models is validated through independent sets of grinding experiments.
{"title":"Intelligent Modeling of Complex Manufacturing Processes Using Hierarchical Fuzzy Basis Function Networks","authors":"Cheol W. Lee, T. Choi, Y. Shin","doi":"10.1115/imece2001/dsc-24590","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24590","url":null,"abstract":"\u0000 This paper presents a generalized modeling approach to modeling of complex manufacturing processes. Fuzzy basis function networks with a novel training algorithm are used to capture the cause-effect relationships of complex manufacturing processes. The modeling scheme allows for utilization of the existing knowledge in the form of analytical models, experimental data and heuristic rules in developing a suitable model. The method is implemented for the surface grinding processes based on the hierarchical structure of fuzzy basis function networks proposed by Lee and Shin [21]. Process models for surface roughness and residual stress are developed based on the available grinding model structures with a small number of experimental data to demonstrate the concept. The accuracy of developed models is validated through independent sets of grinding experiments.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83826431","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24596
S. Shankar
In this paper, we consider the problem of designing a decentralized detection filter for a class of homogeneous interconnected systems; in this class of systems, all subsystems have identical structure. A fault in a subsystem propagates via interactions with other subsystems in the collection. The decentralized detection filter is composed of interacting detection filters, one for each subsystem. We assume communication of state estimates amongst subsystems to be feasible. A concern, dealt with here, is that of propagation of state estimation errors. It is treated as a Ĥ∞ filtering problem with full state information, by requiring the transfer function from the propagated input of the ith subsystem to that of the (i + 1)st subsystem to have a magnitude less than unity at all frequencies.
{"title":"Design of a Decentralized Detection Filter for a Class of Interconnected Systems","authors":"S. Shankar","doi":"10.1115/imece2001/dsc-24596","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24596","url":null,"abstract":"\u0000 In this paper, we consider the problem of designing a decentralized detection filter for a class of homogeneous interconnected systems; in this class of systems, all subsystems have identical structure. A fault in a subsystem propagates via interactions with other subsystems in the collection.\u0000 The decentralized detection filter is composed of interacting detection filters, one for each subsystem. We assume communication of state estimates amongst subsystems to be feasible. A concern, dealt with here, is that of propagation of state estimation errors. It is treated as a Ĥ∞ filtering problem with full state information, by requiring the transfer function from the propagated input of the ith subsystem to that of the (i + 1)st subsystem to have a magnitude less than unity at all frequencies.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83483979","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24633
Antoine Ferreira, J. Fontaine
This paper presents a new generation of compliant piezoelectric microconveyers for microobjects based on the cooperation of arrayed direct-drive standing wave ultrasonic actuators. A method using an equivalent electromechanical circuit is proposed for estimating and analysing the optimum driving force. On the basis of the proposed method, the friction drive optimization of the micro-robot is performed through the implementation of an electromagnetic field-based preload controller. Preliminary experiments were also performed in order to demonstrate the proposed control method.
{"title":"Optimized Driving Force Control of a Planar Micro-Robot Using Friction Drive Mechanism","authors":"Antoine Ferreira, J. Fontaine","doi":"10.1115/imece2001/dsc-24633","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24633","url":null,"abstract":"\u0000 This paper presents a new generation of compliant piezoelectric microconveyers for microobjects based on the cooperation of arrayed direct-drive standing wave ultrasonic actuators. A method using an equivalent electromechanical circuit is proposed for estimating and analysing the optimum driving force. On the basis of the proposed method, the friction drive optimization of the micro-robot is performed through the implementation of an electromagnetic field-based preload controller. Preliminary experiments were also performed in order to demonstrate the proposed control method.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77117679","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24580
H. Pan, V. Kapila
In this paper, we address a tracking control problem for the coupled translational and attitude motion of a spacecraft. Specifically, a nonlinear adaptive control law is developed to ensure global asymptotic tracking of the desired translational and attitude trajectories in the presence of unknown mass and inertia parameters of spacecraft. Using the vectrix formalism the translational and attitude dynamics of spacecraft is modeled, where the mutual coupling in the translational and attitude motion induced by their gravitational interaction is duly accounted. The four-parameter quaternion representation is employed to describe the attitude kinematics of spacecraft in order to enable large orientation maneuvers. Based on the structure of the resulting system dynamics, the filtered translational and attitude tracking error dynamics are developed, which facilitate the transformation of second-order translational and attitude motion error dynamics as first-order equations, thus providing a considerable simplification in control law synthesis/analysis. With the aid of two linear operators, the open-loop filtered tracking error dynamics is parameterized such that the unknown mass and inertia parameters of spacecraft are isolated and can be estimated on-line. Using a Lyapunov framework, nonlinear control and adaptation laws are designed that ensure the global asymptotic convergence of the translational and attitude position tracking errors, despite the presence of unknown mass and inertia parameters of spacecraft. In addition, the form of the filtered tracking error reveals the convergence of translational and attitude velocity tracking errors of spacecraft. An illustrative numerical simulation is presented to demonstrate the effectiveness of the proposed control design methodology for the coupled translational and attitude motion control of spacecraft.
{"title":"Adaptive Nonlinear Control for Spacecraft With Coupled Translational and Attitude Dynamics","authors":"H. Pan, V. Kapila","doi":"10.1115/imece2001/dsc-24580","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24580","url":null,"abstract":"\u0000 In this paper, we address a tracking control problem for the coupled translational and attitude motion of a spacecraft. Specifically, a nonlinear adaptive control law is developed to ensure global asymptotic tracking of the desired translational and attitude trajectories in the presence of unknown mass and inertia parameters of spacecraft. Using the vectrix formalism the translational and attitude dynamics of spacecraft is modeled, where the mutual coupling in the translational and attitude motion induced by their gravitational interaction is duly accounted. The four-parameter quaternion representation is employed to describe the attitude kinematics of spacecraft in order to enable large orientation maneuvers. Based on the structure of the resulting system dynamics, the filtered translational and attitude tracking error dynamics are developed, which facilitate the transformation of second-order translational and attitude motion error dynamics as first-order equations, thus providing a considerable simplification in control law synthesis/analysis. With the aid of two linear operators, the open-loop filtered tracking error dynamics is parameterized such that the unknown mass and inertia parameters of spacecraft are isolated and can be estimated on-line. Using a Lyapunov framework, nonlinear control and adaptation laws are designed that ensure the global asymptotic convergence of the translational and attitude position tracking errors, despite the presence of unknown mass and inertia parameters of spacecraft. In addition, the form of the filtered tracking error reveals the convergence of translational and attitude velocity tracking errors of spacecraft. An illustrative numerical simulation is presented to demonstrate the effectiveness of the proposed control design methodology for the coupled translational and attitude motion control of spacecraft.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73040161","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24530
I. Kolmanovsky, I. Siverguina
The paper describes a game-theoretic framework and a computational algorithm for feasibility evaluation of automotive powertrains with storage elements in terms of fuel economy and emissions performance. The game-theoretic framework allows to handle various time-dependent uncertainties, including uncertainties in the drive cycle. In particular, an important issue in the prior approaches to this problem, the drive cycle dependence of the optimal policies, is alleviated. Within the basic framework, it is also possible to generate implementable operating policies that specify powertrain actuator settings as functions of engine operating conditions and states of the storage elements. We illustrate the procedure using an example powertrain with a Direct Injection Stratified Charge engine and an aftertreatment system consisting of a Three Way Catalyst and a Lean NOx Trap.
{"title":"Feasibility Assessment and Operating Policy Optimization of Automotive Powertrains With Uncertainties Using Game Theory","authors":"I. Kolmanovsky, I. Siverguina","doi":"10.1115/imece2001/dsc-24530","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24530","url":null,"abstract":"\u0000 The paper describes a game-theoretic framework and a computational algorithm for feasibility evaluation of automotive powertrains with storage elements in terms of fuel economy and emissions performance. The game-theoretic framework allows to handle various time-dependent uncertainties, including uncertainties in the drive cycle. In particular, an important issue in the prior approaches to this problem, the drive cycle dependence of the optimal policies, is alleviated. Within the basic framework, it is also possible to generate implementable operating policies that specify powertrain actuator settings as functions of engine operating conditions and states of the storage elements. We illustrate the procedure using an example powertrain with a Direct Injection Stratified Charge engine and an aftertreatment system consisting of a Three Way Catalyst and a Lean NOx Trap.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75302024","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24520
C. Tai, T. Tsao
The control of engine valve seating velocity has been identified to be crucial for the application of an electromagnetic valve (EMV) actuator for camless variable valve timing engine operations. Analysis shows that the EMV actuator becomes unstable when the engine valve is hold steady close to the seating position. As such, valve motion under open loop control is sensitive to disturbances and suffers poor repeatability. Therefore, closed-loop control is required to achieve desirable quiet-seating performance consistently. A linear plant model was constructed based on a gray-box approach that combines mathematical modeling and system identification. A controller was developed with H∞ loop-shaping method to stabilize the EMV actuator. The performance of this control design is demonstrated by experimental results. “Seating velocity” and “seating tail-length” are defined and used to evaluate the control system performance.
{"title":"Quiet Seating Control Design of an Electromagnetic Engine Valve Actuator","authors":"C. Tai, T. Tsao","doi":"10.1115/imece2001/dsc-24520","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24520","url":null,"abstract":"\u0000 The control of engine valve seating velocity has been identified to be crucial for the application of an electromagnetic valve (EMV) actuator for camless variable valve timing engine operations. Analysis shows that the EMV actuator becomes unstable when the engine valve is hold steady close to the seating position. As such, valve motion under open loop control is sensitive to disturbances and suffers poor repeatability. Therefore, closed-loop control is required to achieve desirable quiet-seating performance consistently.\u0000 A linear plant model was constructed based on a gray-box approach that combines mathematical modeling and system identification. A controller was developed with H∞ loop-shaping method to stabilize the EMV actuator. The performance of this control design is demonstrated by experimental results. “Seating velocity” and “seating tail-length” are defined and used to evaluate the control system performance.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74752835","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24599
Tormod Fretheim, R. Shoureshi, T. Vincent
A new fault detection and isolation scheme has been developed to enable automatic detection of faulty conditions in linear or non-linear systems. The focus of this paper is on the development of a general, and feasible method for nonlinear system fault detection which can be easily implemented on input/output models. The method proposed here is different in that the neural network is used to model the process dynamics, while a dead-beat observer is implemented by solving a set of coupled nonlinear equations. This enables the introduction of constraints into the problem that can improve the power of the fault detection techniques.
{"title":"Fault Detection for Nonlinear Systems","authors":"Tormod Fretheim, R. Shoureshi, T. Vincent","doi":"10.1115/imece2001/dsc-24599","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24599","url":null,"abstract":"\u0000 A new fault detection and isolation scheme has been developed to enable automatic detection of faulty conditions in linear or non-linear systems. The focus of this paper is on the development of a general, and feasible method for nonlinear system fault detection which can be easily implemented on input/output models. The method proposed here is different in that the neural network is used to model the process dynamics, while a dead-beat observer is implemented by solving a set of coupled nonlinear equations. This enables the introduction of constraints into the problem that can improve the power of the fault detection techniques.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80495704","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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