Pub Date : 2018-08-01DOI: 10.1109/GNCC42960.2018.9019059
Ruixuan Wei, Qirui Zhang, Zhuofan Xu, Kai Zhou, Xiaolin Zhao
Small UAVs are seeking wide usage in urban space for its advantageous performance. However, there are crowded with static and dynamic buildings, causing serious challenges for UAVs’ safety. This paper proposes a novel autonomous collision avoidance method based on time-obstacle dynamic map. First, the state estimation and trajectory prediction are performed based on extended Kalman filtering. Second, the time-obstacle dynamic map is constructed via introducing time axis. Third, the flyable paths are searched on the basis of breadth first approach and then the optimal path can be obtained through A-Star algorithm. Finally, the simulation results have shown that the proposed collision avoidance method can avoid immobile building and moving obstacles, and making a safe path for UAVs in urban space
{"title":"UAVs’ autonomous collision avoidance in urban space*","authors":"Ruixuan Wei, Qirui Zhang, Zhuofan Xu, Kai Zhou, Xiaolin Zhao","doi":"10.1109/GNCC42960.2018.9019059","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9019059","url":null,"abstract":"Small UAVs are seeking wide usage in urban space for its advantageous performance. However, there are crowded with static and dynamic buildings, causing serious challenges for UAVs’ safety. This paper proposes a novel autonomous collision avoidance method based on time-obstacle dynamic map. First, the state estimation and trajectory prediction are performed based on extended Kalman filtering. Second, the time-obstacle dynamic map is constructed via introducing time axis. Third, the flyable paths are searched on the basis of breadth first approach and then the optimal path can be obtained through A-Star algorithm. Finally, the simulation results have shown that the proposed collision avoidance method can avoid immobile building and moving obstacles, and making a safe path for UAVs in urban space","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"22 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73700173","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9018860
Yuan Xie, Tao Zhang
System or equipment prognosis and health management (PHM) has become more important than ever as modern industry develop. Normally PHM requires abundant prior information or statistic features to predict future system states, however an expert or accurate physical model is usually unavailable in practice. As an important trend of deep neural network algorithms, long short term memory (LSTM) recurrent neural network (RNN) has been proven significantly practical and accurate in machine learning problems such as natural language processing (NLP) and time serial prediction. In this paper a novel fault prognosis approach using LSTM based on vibration signal of rotating machinery is presented. It is proven that the capacity of machinery performance prediction with LSTM algorithm is improved with limited data available in a relatively short time period. The proposed LSTM approach, compared with other prognosis methods, gives a successful outcomes that may enhance the ability of health management and machine condition monitoring. It is proven that the proposed approach is superior and more practical for machine prognosis in complex bearing systems.
{"title":"A Long Short Term Memory Recurrent Neural Network Approach for Rotating Machinery Fault Prognosis","authors":"Yuan Xie, Tao Zhang","doi":"10.1109/GNCC42960.2018.9018860","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9018860","url":null,"abstract":"System or equipment prognosis and health management (PHM) has become more important than ever as modern industry develop. Normally PHM requires abundant prior information or statistic features to predict future system states, however an expert or accurate physical model is usually unavailable in practice. As an important trend of deep neural network algorithms, long short term memory (LSTM) recurrent neural network (RNN) has been proven significantly practical and accurate in machine learning problems such as natural language processing (NLP) and time serial prediction. In this paper a novel fault prognosis approach using LSTM based on vibration signal of rotating machinery is presented. It is proven that the capacity of machinery performance prediction with LSTM algorithm is improved with limited data available in a relatively short time period. The proposed LSTM approach, compared with other prognosis methods, gives a successful outcomes that may enhance the ability of health management and machine condition monitoring. It is proven that the proposed approach is superior and more practical for machine prognosis in complex bearing systems.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"2 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72638001","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9018982
Liu Xiaochen, L. Xiaojie, Xiong Yufeng, Yan Jiangtao, Wang Yubo, W. Linwei, Liu Jun, Shen Chong, Tang Jun
Since the performance of pyramid Lucas-Kanade (LK) based optical flow algorithm would be influenced by different environments, this paper evaluates the simulation accuracy of the pyramid LK algorithm in cities, plains and mountains, respectively. The simulation results show that the LK algorithm can maintain high precision under the large motion, and the flight strategy of UAV under different environment is given according to the algorithm’s accuracy, In order to ensure the high accuracy of the optical flow sensor in different environments. For example, in the urban environment, when the UAV’s velocity is 12m/s-l5m/s, the best altitude is 80m-l50m. Simulation verification experiments are carried out in different environments. The simulation results show that the proposed UAV flight strategy is generally correct.
{"title":"Evaluation of Lucas-Kanade based optical flow algorithm","authors":"Liu Xiaochen, L. Xiaojie, Xiong Yufeng, Yan Jiangtao, Wang Yubo, W. Linwei, Liu Jun, Shen Chong, Tang Jun","doi":"10.1109/GNCC42960.2018.9018982","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9018982","url":null,"abstract":"Since the performance of pyramid Lucas-Kanade (LK) based optical flow algorithm would be influenced by different environments, this paper evaluates the simulation accuracy of the pyramid LK algorithm in cities, plains and mountains, respectively. The simulation results show that the LK algorithm can maintain high precision under the large motion, and the flight strategy of UAV under different environment is given according to the algorithm’s accuracy, In order to ensure the high accuracy of the optical flow sensor in different environments. For example, in the urban environment, when the UAV’s velocity is 12m/s-l5m/s, the best altitude is 80m-l50m. Simulation verification experiments are carried out in different environments. The simulation results show that the proposed UAV flight strategy is generally correct.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"107 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77417759","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9019135
Shuo Chen, Hui Zhao, Xin Huo, Yu Yao
As a new type of inertial actuator, the gyrowheel can perform actuator and sensor applied for micro-spacecraft. Due to the special support mechanical structure of gyrowheel rotor, the rotation speed of the rotor in the tilting would produce twice-spin frequency flutter, which affects the service life of system. In this paper, according to the rigid universal joint of the prototype, the mathematical model of speed transfer is established and the torque analysis of universal joint is carried out at the same time. The simulation results verified the effects of the joint on the gyrowheel.
{"title":"Analysis of Characteristics of Rigid Universal Joint of Gyrowheel","authors":"Shuo Chen, Hui Zhao, Xin Huo, Yu Yao","doi":"10.1109/GNCC42960.2018.9019135","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9019135","url":null,"abstract":"As a new type of inertial actuator, the gyrowheel can perform actuator and sensor applied for micro-spacecraft. Due to the special support mechanical structure of gyrowheel rotor, the rotation speed of the rotor in the tilting would produce twice-spin frequency flutter, which affects the service life of system. In this paper, according to the rigid universal joint of the prototype, the mathematical model of speed transfer is established and the torque analysis of universal joint is carried out at the same time. The simulation results verified the effects of the joint on the gyrowheel.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"50 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79162760","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9019155
Jiarui Zhang, Ruiyun Qi, B. Jiang
The paper presents a nonlinear dynamic model of flexible solar sail with elastic deformation and a stability analysis of the zero dynamics of model. Mathematical model based on the combination of hybrid coordinate method and the finite element method is used, to include the behavior of the vibration dynamics coupled to the solar sail. With both analytical and numerical results, it is shown that in the presence of elastic deformation, the zero dynamics of the coupled attitude-vibration model is stable only on the local compact set at its equilibrium point. This study demonstrates that the elastic deformation has a great impact on the state of the system, which needed to be considered in the design of controller. Then, a simple controller based on the backstepping method is proposed to complete the attitude maneuver of solar sail. A numerical simulation is used to verify the effectiveness of the controller.
{"title":"Modeling and Analysis of Flexible Solar Sail","authors":"Jiarui Zhang, Ruiyun Qi, B. Jiang","doi":"10.1109/GNCC42960.2018.9019155","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9019155","url":null,"abstract":"The paper presents a nonlinear dynamic model of flexible solar sail with elastic deformation and a stability analysis of the zero dynamics of model. Mathematical model based on the combination of hybrid coordinate method and the finite element method is used, to include the behavior of the vibration dynamics coupled to the solar sail. With both analytical and numerical results, it is shown that in the presence of elastic deformation, the zero dynamics of the coupled attitude-vibration model is stable only on the local compact set at its equilibrium point. This study demonstrates that the elastic deformation has a great impact on the state of the system, which needed to be considered in the design of controller. Then, a simple controller based on the backstepping method is proposed to complete the attitude maneuver of solar sail. A numerical simulation is used to verify the effectiveness of the controller.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"19 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84243682","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9018872
Chaojie Yang, Jiang Wu, Guoqing Liu, Yuncan Zhang
Ballistic missiles, as the main weapon for long-range precision fire strikes, reflect the military development level and strategic capabilities of a country. This paper focuses on the midcourse penetration process of ballistic missile maneuvers. Assuming that the interceptor missile uses a proportional guidance strategy, the reinforcement learning methods is used to train network models. The method avoids the need for traditional control theory methods to establish precise mathematical models based on controlled objects, and this reduces the difficulty of the performance model to solve the optimal analytical solution. The use of State space discretization reduce the action space, and improves the network learning efficiency. Finally, the simulation proves that reinforcement learning can greatly increase the miss distance of missile maneuver penetration.
{"title":"Ballistic Missile Maneuver Penetration Based on Reinforcement Learning","authors":"Chaojie Yang, Jiang Wu, Guoqing Liu, Yuncan Zhang","doi":"10.1109/GNCC42960.2018.9018872","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9018872","url":null,"abstract":"Ballistic missiles, as the main weapon for long-range precision fire strikes, reflect the military development level and strategic capabilities of a country. This paper focuses on the midcourse penetration process of ballistic missile maneuvers. Assuming that the interceptor missile uses a proportional guidance strategy, the reinforcement learning methods is used to train network models. The method avoids the need for traditional control theory methods to establish precise mathematical models based on controlled objects, and this reduces the difficulty of the performance model to solve the optimal analytical solution. The use of State space discretization reduce the action space, and improves the network learning efficiency. Finally, the simulation proves that reinforcement learning can greatly increase the miss distance of missile maneuver penetration.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"36 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84346060","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9019193
M. Butt, Zhan Hai, Xiaochen Qiu
When using camera as an aiding sensor, extraction of accurate pose measurement in the form of translation and rotation is instrumental to the navigation solution. This paper shows the experimental results of accurate angle extraction between a sequence of images taken from a calibrated camera while keeping the scale constant. In this work a complete mathematical model for rotation extraction is discussed comprising of feature extraction and matching, epipolar geometry constraints, structure from motion (SFM), etc. As far as the author’s knowledge, such a benchmarking for rotation extraction has not been previously reported and hence this algorithm can be used as a beginning point for new practitioners in the field of visual navigation. This benchmarking algorithm is also provided as an open-source toolbox for MATLAB available at https://github.com/maazmb/rotation_extraction.git.
{"title":"A benchmark for rotation extraction between two images in visual navigation","authors":"M. Butt, Zhan Hai, Xiaochen Qiu","doi":"10.1109/GNCC42960.2018.9019193","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9019193","url":null,"abstract":"When using camera as an aiding sensor, extraction of accurate pose measurement in the form of translation and rotation is instrumental to the navigation solution. This paper shows the experimental results of accurate angle extraction between a sequence of images taken from a calibrated camera while keeping the scale constant. In this work a complete mathematical model for rotation extraction is discussed comprising of feature extraction and matching, epipolar geometry constraints, structure from motion (SFM), etc. As far as the author’s knowledge, such a benchmarking for rotation extraction has not been previously reported and hence this algorithm can be used as a beginning point for new practitioners in the field of visual navigation. This benchmarking algorithm is also provided as an open-source toolbox for MATLAB available at https://github.com/maazmb/rotation_extraction.git.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"11 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84483837","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9019209
Shaokun Shi, Jiufen Zhao, Hao You
In order to improve the guidance precision and increase the control of the falling angle, the bias proportional navigation guidance law to the moving targets with impact angle constraint is derived according to tilted moving target. By adding the relative motion state between missile and target in the bias term, the specified angle attack to the moving targets is realized. Considering imprecision of traditional time-to-go estimation under the moving targets with impact angle constraint, by predicting missile-target crack point, the time-to-go estimation method with impact angle constraint based on predicted crack point is designed under the deduced guidance law. The simulation results show that the estimation of designed time-to-go estimation method based on predicted crack point is precise under different angle constraint; The deduced bias proportional navigation guidance law to the fast-moving targets with impact angle constraint has better effect on high impact accuracy, control impact angle and overload
{"title":"Design of Bias Proportional Navigation Guidance Law for Motion Target with Impact Angle Constraint","authors":"Shaokun Shi, Jiufen Zhao, Hao You","doi":"10.1109/GNCC42960.2018.9019209","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9019209","url":null,"abstract":"In order to improve the guidance precision and increase the control of the falling angle, the bias proportional navigation guidance law to the moving targets with impact angle constraint is derived according to tilted moving target. By adding the relative motion state between missile and target in the bias term, the specified angle attack to the moving targets is realized. Considering imprecision of traditional time-to-go estimation under the moving targets with impact angle constraint, by predicting missile-target crack point, the time-to-go estimation method with impact angle constraint based on predicted crack point is designed under the deduced guidance law. The simulation results show that the estimation of designed time-to-go estimation method based on predicted crack point is precise under different angle constraint; The deduced bias proportional navigation guidance law to the fast-moving targets with impact angle constraint has better effect on high impact accuracy, control impact angle and overload","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"24 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84506691","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9018685
Siting Peng, Yuan Liang, Hong Jiang, Qingdong Li, Xiwang Dong, Z. Ren
According to the characteristics of the cubature Kalaman filter, the precision of filter can be improved by considering the statistical characters of the noise, thus an adaptive CKF is applied to solve the estimation problem existed in the semi-strapdown seeker system. By calculating the mean value in each iteration, the algorithm can estimate and correct the statistical characters of the noise on-line by using Sage-Husa maximum a posterior (MAP) estimator in the filtering process therefore, and then can effectively improve the estimation accuracy and stability of the CKF. When the normal and adaptive CKF methods are applied in the target tracking model of infrared semi-strapdown seeker, the simulation results show that the adaptive CKF algorithm is more feasible and effective, and it has better performance than the CKF both in stability and precision, thus demonstrating that the ACKF could obviously improve the filtering effect of normal CKF algorithm.
{"title":"Application of An Adaptive Cubature Kalman Filter in Target Tracking Model of Infrared Semi-strapdown Seeker","authors":"Siting Peng, Yuan Liang, Hong Jiang, Qingdong Li, Xiwang Dong, Z. Ren","doi":"10.1109/GNCC42960.2018.9018685","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9018685","url":null,"abstract":"According to the characteristics of the cubature Kalaman filter, the precision of filter can be improved by considering the statistical characters of the noise, thus an adaptive CKF is applied to solve the estimation problem existed in the semi-strapdown seeker system. By calculating the mean value in each iteration, the algorithm can estimate and correct the statistical characters of the noise on-line by using Sage-Husa maximum a posterior (MAP) estimator in the filtering process therefore, and then can effectively improve the estimation accuracy and stability of the CKF. When the normal and adaptive CKF methods are applied in the target tracking model of infrared semi-strapdown seeker, the simulation results show that the adaptive CKF algorithm is more feasible and effective, and it has better performance than the CKF both in stability and precision, thus demonstrating that the ACKF could obviously improve the filtering effect of normal CKF algorithm.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"37 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84869444","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 : 2018-08-01DOI: 10.1109/GNCC42960.2018.9019206
Guo Guangyan, Lv Yongshen, Yang Xuerong, Dong Xu-rong
Ballistic Missile Defense System (BMDS) is an essential part of national defense system and its deployment situation has a great influence on the capability of the system. A reasonable plan for the deployment could improve the combat effectiveness significantly. This paper analyzes the composition and process of BMDS, introduces the simulation platform for BMDS deployment research. Then, by using PSO method, the paper analyze the optimum area of interceptors in two different situations, provides ideas and solutions for future deployment of BMDS.
{"title":"Ballistic Missile Defense System Deployment Simulation Based on Particle Swarm optimization*","authors":"Guo Guangyan, Lv Yongshen, Yang Xuerong, Dong Xu-rong","doi":"10.1109/GNCC42960.2018.9019206","DOIUrl":"https://doi.org/10.1109/GNCC42960.2018.9019206","url":null,"abstract":"Ballistic Missile Defense System (BMDS) is an essential part of national defense system and its deployment situation has a great influence on the capability of the system. A reasonable plan for the deployment could improve the combat effectiveness significantly. This paper analyzes the composition and process of BMDS, introduces the simulation platform for BMDS deployment research. Then, by using PSO method, the paper analyze the optimum area of interceptors in two different situations, provides ideas and solutions for future deployment of BMDS.","PeriodicalId":6623,"journal":{"name":"2018 IEEE CSAA Guidance, Navigation and Control Conference (CGNCC)","volume":"9 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85123728","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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