Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97最新文献
Pub Date : 1997-09-07DOI: 10.1109/IROS.1997.655069
Nick E. Pear
An active range sensor is summarised. This sensor can direct its field of view in order to fixate on range features for mobile robot navigation. The image position sensor used has a Gaussian noise characteristic with measurable variance, which makes the sensor particularly amenable to stochastic range feature detection. A geometric analysis of the sensor allows a mathematical model of the sensor to be built, the parameters of which can be determined from data collected during the calibration of the real sensor. This model forms the basis of a sensor simulation, which allows feature extraction algorithms to be developed. One such algorithm, based on the extended Kalman filter, extracts a piecewise-linear range representation of the local environment. This has a number of advantages over previous methods in that it is computationally efficient, it deals with noise appropriately, and it is robust to sensor head movements as range measurements are being made.
{"title":"Range feature extraction during active sensor motion","authors":"Nick E. Pear","doi":"10.1109/IROS.1997.655069","DOIUrl":"https://doi.org/10.1109/IROS.1997.655069","url":null,"abstract":"An active range sensor is summarised. This sensor can direct its field of view in order to fixate on range features for mobile robot navigation. The image position sensor used has a Gaussian noise characteristic with measurable variance, which makes the sensor particularly amenable to stochastic range feature detection. A geometric analysis of the sensor allows a mathematical model of the sensor to be built, the parameters of which can be determined from data collected during the calibration of the real sensor. This model forms the basis of a sensor simulation, which allows feature extraction algorithms to be developed. One such algorithm, based on the extended Kalman filter, extracts a piecewise-linear range representation of the local environment. This has a number of advantages over previous methods in that it is computationally efficient, it deals with noise appropriately, and it is robust to sensor head movements as range measurements are being made.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"173 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132995615","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 : 1997-09-07DOI: 10.1109/IROS.1997.656583
I. Murata, T. Chikura, S. Kunimitsu, Atsuya Yoshida, Tsunehiro Akabane
In this paper, the semiautomatic construction manipulators system for steel towers for the transmission of electricity is proposed. The piling up/expansion and contraction method is selected as the best construction method out of ten methods considered for the semiautomatic system. The first necessary function for construction manipulators is addressed and the suitable mechanism for it is considered as semiautomatic system. The remote operation method is used for operating a climbing crane and manipulators. This system has five monitors which display scenes sent from cameras on the crane and the manipulators and animation displays which are useful for operators to monitor working conditions from any direction. The climbing crane controls and construction manipulators require many kinds of functions. Anti sway control is necessary and very important for crane controls. Force control and tightening control are important for manipulators control. In addition, cooperative control is very important for crane and manipulators.
{"title":"Construction manipulators of steel towers for the transmission of electricity","authors":"I. Murata, T. Chikura, S. Kunimitsu, Atsuya Yoshida, Tsunehiro Akabane","doi":"10.1109/IROS.1997.656583","DOIUrl":"https://doi.org/10.1109/IROS.1997.656583","url":null,"abstract":"In this paper, the semiautomatic construction manipulators system for steel towers for the transmission of electricity is proposed. The piling up/expansion and contraction method is selected as the best construction method out of ten methods considered for the semiautomatic system. The first necessary function for construction manipulators is addressed and the suitable mechanism for it is considered as semiautomatic system. The remote operation method is used for operating a climbing crane and manipulators. This system has five monitors which display scenes sent from cameras on the crane and the manipulators and animation displays which are useful for operators to monitor working conditions from any direction. The climbing crane controls and construction manipulators require many kinds of functions. Anti sway control is necessary and very important for crane controls. Force control and tightening control are important for manipulators control. In addition, cooperative control is very important for crane and manipulators.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133395818","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 : 1997-09-07DOI: 10.1109/IROS.1997.649075
A. Joukhadar, F. Garat, C. Laugier
Dynamic simulation is potentially a powerful tool for studying complex contact interactions between robots and their environments. One of the main problems of such a simulation is the determination of the model parameters which provide realistic behavior for objects. This paper describes how to identify such parameters for a mass/spring based system. This identification process is composed of two main steps: 1) distributing the total mass of the object between different particles while respecting the inertial properties of the object; and 2) finding the values of the physical parameters of the model such as elasticity, viscosity, plasticity, etc. The numerical solution of the first step is described, while a genetic algorithm base approach is proposed for the second step. This approach allows us to find the values of the parameters which provide a consistent behavior under a set of given constraints (position, velocity, volume, etc.). It also allows us to minimize the computation time and to attach priorities with these constraints.
{"title":"Constrain-based identification of a dynamic model","authors":"A. Joukhadar, F. Garat, C. Laugier","doi":"10.1109/IROS.1997.649075","DOIUrl":"https://doi.org/10.1109/IROS.1997.649075","url":null,"abstract":"Dynamic simulation is potentially a powerful tool for studying complex contact interactions between robots and their environments. One of the main problems of such a simulation is the determination of the model parameters which provide realistic behavior for objects. This paper describes how to identify such parameters for a mass/spring based system. This identification process is composed of two main steps: 1) distributing the total mass of the object between different particles while respecting the inertial properties of the object; and 2) finding the values of the physical parameters of the model such as elasticity, viscosity, plasticity, etc. The numerical solution of the first step is described, while a genetic algorithm base approach is proposed for the second step. This approach allows us to find the values of the parameters which provide a consistent behavior under a set of given constraints (position, velocity, volume, etc.). It also allows us to minimize the computation time and to attach priorities with these constraints.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133031992","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 : 1997-09-07DOI: 10.1109/IROS.1997.655073
J. H. Kim, I. Suh, Sang-Rok Oh, Y. J. Cho, Y. K. Chung
For continuous state space applications, a novel method of Q-learning is proposed, where the method incorporates a region-based reward assignment being used to solve a structural credit assignment problem and a convex clustering approach to find a region with the same reward attribution property. Our learning method can estimate a current Q-value of an arbitrarily given state by using effect functions, and has the ability to learn its actions similar to that of Q-learning. Thus, our method enables robots to move smoothly in a real environment. To show the validity of our method, the proposed Q-learning method is compared with conventional Q-learning method through a simple two dimensional free space navigation problem, and visual tracking simulation results involving a 2-DOF SCARA robot are also presented.
{"title":"Region-based Q-learning using convex clustering approach","authors":"J. H. Kim, I. Suh, Sang-Rok Oh, Y. J. Cho, Y. K. Chung","doi":"10.1109/IROS.1997.655073","DOIUrl":"https://doi.org/10.1109/IROS.1997.655073","url":null,"abstract":"For continuous state space applications, a novel method of Q-learning is proposed, where the method incorporates a region-based reward assignment being used to solve a structural credit assignment problem and a convex clustering approach to find a region with the same reward attribution property. Our learning method can estimate a current Q-value of an arbitrarily given state by using effect functions, and has the ability to learn its actions similar to that of Q-learning. Thus, our method enables robots to move smoothly in a real environment. To show the validity of our method, the proposed Q-learning method is compared with conventional Q-learning method through a simple two dimensional free space navigation problem, and visual tracking simulation results involving a 2-DOF SCARA robot are also presented.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133093486","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 : 1997-09-07DOI: 10.1109/IROS.1997.655082
Sooyong Lee, H. Asada
In the traditional force-guided control schemes, the contact force measured by a force sensor is directly fed back to a feedback controller to generate a motion correction signal. The issue central to force guided robot control is how to obtain reliable, consistent and copious force signals and extract useful information in order to successfully guide the robot while keeping the contact force at a desired level. In this paper, instead of simply measuring contact forces, we take positive actions by giving perturbation to the end effector and observing the reaction forces to the perturbation in order to obtain much richer and more reliable information. By taking the correlation between the input perturbation and the resultant reaction forces, we can determine the gradient of the force profile and guide the part correctly. This algorithm is applied to a pipe insertion task, and connector assembly task. Based on the process model and stability analysis using the Popov stability criterion, conditions for stable, successful insertion despite nonlinearities and uncertainties in the environment are obtained. The theoretical results are verified using the experimental data.
{"title":"Assembly automation using perturbation/correlation","authors":"Sooyong Lee, H. Asada","doi":"10.1109/IROS.1997.655082","DOIUrl":"https://doi.org/10.1109/IROS.1997.655082","url":null,"abstract":"In the traditional force-guided control schemes, the contact force measured by a force sensor is directly fed back to a feedback controller to generate a motion correction signal. The issue central to force guided robot control is how to obtain reliable, consistent and copious force signals and extract useful information in order to successfully guide the robot while keeping the contact force at a desired level. In this paper, instead of simply measuring contact forces, we take positive actions by giving perturbation to the end effector and observing the reaction forces to the perturbation in order to obtain much richer and more reliable information. By taking the correlation between the input perturbation and the resultant reaction forces, we can determine the gradient of the force profile and guide the part correctly. This algorithm is applied to a pipe insertion task, and connector assembly task. Based on the process model and stability analysis using the Popov stability criterion, conditions for stable, successful insertion despite nonlinearities and uncertainties in the environment are obtained. The theoretical results are verified using the experimental data.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133302700","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 : 1997-09-07DOI: 10.1109/IROS.1997.656546
P. Weckesser, R. Dillmann, U. Rembold
The mobile service robots described are designed to operate in dynamics and changing environments together with human beings and other static or moving objects. Sensors that are capable of providing the quality of information that is required for the described scenario are optical sensors, like digital cameras and laser scanners. In this paper the sensor integration and fusion for such sensors is described. Complementary sensor information is transformed into a common representation in order to achieve a cooperating sensor system. Sensor fusion is performed by matching the local perception of the laser scanner and camera system with a global model that is being build incrementally. The Mahalanobis distance is used as matching criterion and a Kalman filter is used to fuse matching features. A common representation including the uncertainty and the confidence is used for all scene features. The system's performance is demonstrated for the task of exploring an unknown environment and incrementally building of the geometrical model.
{"title":"Navigating a mobile service-robot in a natural environment using sensor-fusion techniques","authors":"P. Weckesser, R. Dillmann, U. Rembold","doi":"10.1109/IROS.1997.656546","DOIUrl":"https://doi.org/10.1109/IROS.1997.656546","url":null,"abstract":"The mobile service robots described are designed to operate in dynamics and changing environments together with human beings and other static or moving objects. Sensors that are capable of providing the quality of information that is required for the described scenario are optical sensors, like digital cameras and laser scanners. In this paper the sensor integration and fusion for such sensors is described. Complementary sensor information is transformed into a common representation in order to achieve a cooperating sensor system. Sensor fusion is performed by matching the local perception of the laser scanner and camera system with a global model that is being build incrementally. The Mahalanobis distance is used as matching criterion and a Kalman filter is used to fuse matching features. A common representation including the uncertainty and the confidence is used for all scene features. The system's performance is demonstrated for the task of exploring an unknown environment and incrementally building of the geometrical model.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128985079","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 : 1997-09-07DOI: 10.1109/IROS.1997.656597
Jun Sasaki, G. Nishida, A. Yamashita, Y. Aiyama, J. Ota, T. Arai
In transporting various objects by multiple mobile robots we need to change the formation of robots and posture of an object. This planning depends on the mass and center of gravity of an object. Here we discuss the accuracy of the estimation of the mass and the position of the center of gravity of an object. Particularly we propose a method for estimating the height of the center of gravity which cannot be estimated by only one measurement. Validity of this strategy is verified by means of a real robot system.
{"title":"Estimating the center of gravity of an object using tilting by multiple mobile robots","authors":"Jun Sasaki, G. Nishida, A. Yamashita, Y. Aiyama, J. Ota, T. Arai","doi":"10.1109/IROS.1997.656597","DOIUrl":"https://doi.org/10.1109/IROS.1997.656597","url":null,"abstract":"In transporting various objects by multiple mobile robots we need to change the formation of robots and posture of an object. This planning depends on the mass and center of gravity of an object. Here we discuss the accuracy of the estimation of the mass and the position of the center of gravity of an object. Particularly we propose a method for estimating the height of the center of gravity which cannot be estimated by only one measurement. Validity of this strategy is verified by means of a real robot system.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128659705","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 : 1997-09-07DOI: 10.1109/IROS.1997.656541
L. Aguilar, T. Hamel, P. Souéres
The techniques of filtering and merging data coming from several sensors allow to localize a mobile robot in its environment with a precision which can be evaluated. However, as the localization error cannot be neglected, the design of robust closed-loop controller for wheeled robots constitutes a difficult problem. We present here a path following feedback controller robust with respect to localization error. The model is a dynamic extension of the usual kinematic model of a car, in the sense that the path curvature error is considered as a new state variable. The control inputs are respectively the linear velocity and the derivative of the curvature. We determine a variable structure control with sliding mode to stabilize the vehicle's motion around the reference path in the nominal case. Then, we prove that the system remains stable when the state feedback is computed from the estimated values instead of the exact ones. We show that the regulation error is contained in a compact attractive domain when the system has reached its steady state. From this domain, one can easily compute a security margin to guarantee obstacle avoidance during the path following process. Experimental results are presented at the end of the paper.
{"title":"Robust path following control for wheeled robots via sliding mode techniques","authors":"L. Aguilar, T. Hamel, P. Souéres","doi":"10.1109/IROS.1997.656541","DOIUrl":"https://doi.org/10.1109/IROS.1997.656541","url":null,"abstract":"The techniques of filtering and merging data coming from several sensors allow to localize a mobile robot in its environment with a precision which can be evaluated. However, as the localization error cannot be neglected, the design of robust closed-loop controller for wheeled robots constitutes a difficult problem. We present here a path following feedback controller robust with respect to localization error. The model is a dynamic extension of the usual kinematic model of a car, in the sense that the path curvature error is considered as a new state variable. The control inputs are respectively the linear velocity and the derivative of the curvature. We determine a variable structure control with sliding mode to stabilize the vehicle's motion around the reference path in the nominal case. Then, we prove that the system remains stable when the state feedback is computed from the estimated values instead of the exact ones. We show that the regulation error is contained in a compact attractive domain when the system has reached its steady state. From this domain, one can easily compute a security margin to guarantee obstacle avoidance during the path following process. Experimental results are presented at the end of the paper.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115846373","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 : 1997-09-07DOI: 10.1109/IROS.1997.649069
J. Zelek
Interaction between robots and humans should be at a level which is accessible and natural for human operators. A lexicon template is proposed for specifying commands for 2D mobile robot navigational tasks. The language lexicon is a minimal spanning semantic set for human 2D navigational tasks. The task command lexicon consists of a verb, destination, direction and a speed. The destination is a location in the environment defined by a geometric model positioned at a particular spatial location in a globally-referenced Cartesian coordinate space. The task command lexicon has been used as a language template for specifying commands for the SPOTT mobile robot control architecture. It is not the intent that the template serve as the only commands that the robot recognizes, but rather as an internal language that gets mapped onto planning and control constructs. A speech recognition system maps spoken commands onto the proposed internal natural language command template.
{"title":"Human-robot interaction with minimal spanning natural language template for autonomous and tele-operated control","authors":"J. Zelek","doi":"10.1109/IROS.1997.649069","DOIUrl":"https://doi.org/10.1109/IROS.1997.649069","url":null,"abstract":"Interaction between robots and humans should be at a level which is accessible and natural for human operators. A lexicon template is proposed for specifying commands for 2D mobile robot navigational tasks. The language lexicon is a minimal spanning semantic set for human 2D navigational tasks. The task command lexicon consists of a verb, destination, direction and a speed. The destination is a location in the environment defined by a geometric model positioned at a particular spatial location in a globally-referenced Cartesian coordinate space. The task command lexicon has been used as a language template for specifying commands for the SPOTT mobile robot control architecture. It is not the intent that the template serve as the only commands that the robot recognizes, but rather as an internal language that gets mapped onto planning and control constructs. A speech recognition system maps spoken commands onto the proposed internal natural language command template.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"302 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116323897","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 : 1997-09-07DOI: 10.1109/IROS.1997.649101
G. Deacon, M. Wright, C. Malcolm
For pt. 1 see Proc. IEEE Int. Conf. on Robotics and Automation, p.2697-704 (1997). We investigate the topology of the space of possible pushing behaviour for 2.5 D objects of arbitrary outline. We do this by studying the push-stability diagram (PSD) derived by Brost (1985, 1988). We show how to predict some of the effects on the topology of the PSD that arise from varying the position of the centre of mass, making it possible to use this as a control parameter in the design of objects for feeding.
{"title":"Qualitative transition in object reorienting behaviour. 2. The effects of varying the centre of mass","authors":"G. Deacon, M. Wright, C. Malcolm","doi":"10.1109/IROS.1997.649101","DOIUrl":"https://doi.org/10.1109/IROS.1997.649101","url":null,"abstract":"For pt. 1 see Proc. IEEE Int. Conf. on Robotics and Automation, p.2697-704 (1997). We investigate the topology of the space of possible pushing behaviour for 2.5 D objects of arbitrary outline. We do this by studying the push-stability diagram (PSD) derived by Brost (1985, 1988). We show how to predict some of the effects on the topology of the PSD that arise from varying the position of the centre of mass, making it possible to use this as a control parameter in the design of objects for feeding.","PeriodicalId":408848,"journal":{"name":"Proceedings of the 1997 IEEE/RSJ International Conference on Intelligent Robot and Systems. Innovative Robotics for Real-World Applications. IROS '97","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116644162","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：