Pub Date : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803988
Min Han, W. Dou
In this paper, an improved Capon estimator is introduced, and reserves the characteristics of signal space after filtering the noise. More precise power estimation for both noise and signal from different directions can be obtained. Then, the covariance matrices of both interference-plus-noise and signal are reconstructed. With the estimated noise power and the covariance matrices, we propose 4 similar algorithms. Different from the previous methods, the proposed algorithms avoid the robust conditions in the constraints, even to solve a new convex optimization problem which would increase the amount of computation significantly. Simulation results show that the improved Capon estimator achieves better spatial resolution than existing methods, and the performance of the proposed robust adaptive beamforming is almost close to the optimal value across a wide range of signal to interference and noise ratio.
{"title":"Unconstrained Robust Adaptive Beamforming with Improved Capon Estimator","authors":"Min Han, W. Dou","doi":"10.1109/IEEE-IWS.2019.8803988","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803988","url":null,"abstract":"In this paper, an improved Capon estimator is introduced, and reserves the characteristics of signal space after filtering the noise. More precise power estimation for both noise and signal from different directions can be obtained. Then, the covariance matrices of both interference-plus-noise and signal are reconstructed. With the estimated noise power and the covariance matrices, we propose 4 similar algorithms. Different from the previous methods, the proposed algorithms avoid the robust conditions in the constraints, even to solve a new convex optimization problem which would increase the amount of computation significantly. Simulation results show that the improved Capon estimator achieves better spatial resolution than existing methods, and the performance of the proposed robust adaptive beamforming is almost close to the optimal value across a wide range of signal to interference and noise ratio.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125407788","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803934
Dajiang Li, M. Tang, Xiaoming Chen, Yang Wang, Kun‐Zhi Hu, R. Ziolkowski
A planar, wideband, multi-polarization reconfigurable filtering antenna is proposed. By controlling the state of PIN diodes, the operation states of the filtering antenna can be switched among linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The filtering antenna consists of a driven patch, a parasitic patch, and an established reconfigurable feed network. Two radiation nulls can be generated at the lower and upper band-edge in all operation states through interaction between the driven patch and feeding network. A pair of U-slots is etched on the driven patch to obtain the extra radiation null to further improve the sharp roll-off rate at the upper band-edge. The optimized prototype was fabricated and tested. The measured results, in good agreement with the simulated values, demonstrate that the filtenna has a wide -10dB fractional bandwidth: 15.6%, a realized gain value over operational bandwidth of 7.7 ± 0.5 dBi, and stable radiation performance. Furthermore, the filtenna presents a good out-of-band rejection level.
{"title":"Design of Planar, Wideband, Multi-Polarization Reconfigurable Filtering Antenna","authors":"Dajiang Li, M. Tang, Xiaoming Chen, Yang Wang, Kun‐Zhi Hu, R. Ziolkowski","doi":"10.1109/IEEE-IWS.2019.8803934","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803934","url":null,"abstract":"A planar, wideband, multi-polarization reconfigurable filtering antenna is proposed. By controlling the state of PIN diodes, the operation states of the filtering antenna can be switched among linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The filtering antenna consists of a driven patch, a parasitic patch, and an established reconfigurable feed network. Two radiation nulls can be generated at the lower and upper band-edge in all operation states through interaction between the driven patch and feeding network. A pair of U-slots is etched on the driven patch to obtain the extra radiation null to further improve the sharp roll-off rate at the upper band-edge. The optimized prototype was fabricated and tested. The measured results, in good agreement with the simulated values, demonstrate that the filtenna has a wide -10dB fractional bandwidth: 15.6%, a realized gain value over operational bandwidth of 7.7 ± 0.5 dBi, and stable radiation performance. Furthermore, the filtenna presents a good out-of-band rejection level.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130944691","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8804032
L. Gu, W. Feng, Zhu Liu, Shijun Tang, Tao Chen, W. Che
In this paper the design, implementation, and experimental results of an X-band 500W GaN-HEMT power amplifier (PA) are presented. The device consists of four GaN power dies of 18-mm gate periphery together with input and output 2-stage impedance transformer networks. The device exhibited saturated output power of 500 W with power gain of 9.0 dB over the frequency range of 8.2-8.8 GHz, operating at 50 V drain voltage under pulsed condition of 50us pulse width and 5% duty ratio. In addition, the highest saturated output power reached 580 W with power gain of 9.6 dB at 8.5 GHz. This is the highest output power GaN HEMT ever reported for X-band.
{"title":"An X-band 500W Internally Matched High Power GaN Amplifier","authors":"L. Gu, W. Feng, Zhu Liu, Shijun Tang, Tao Chen, W. Che","doi":"10.1109/IEEE-IWS.2019.8804032","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8804032","url":null,"abstract":"In this paper the design, implementation, and experimental results of an X-band 500W GaN-HEMT power amplifier (PA) are presented. The device consists of four GaN power dies of 18-mm gate periphery together with input and output 2-stage impedance transformer networks. The device exhibited saturated output power of 500 W with power gain of 9.0 dB over the frequency range of 8.2-8.8 GHz, operating at 50 V drain voltage under pulsed condition of 50us pulse width and 5% duty ratio. In addition, the highest saturated output power reached 580 W with power gain of 9.6 dB at 8.5 GHz. This is the highest output power GaN HEMT ever reported for X-band.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131136825","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803870
L. Xia, Hanyu Xie, Bian Wu, Jianzhong Chen, Shining Sun, Xiaoyu Pang
A miniaturized substrate integrated waveguide (SIW) triplexer with a common triple-mode resonator has been proposed in this paper. The common triple-mode resonator is perturbed by centered cross-shaped slots etched on the top surface of a square SIW cavity. By investigation of surface current distributions on the slot perturbed triple-mode square cavity, the first and second higher-order spurious resonant frequencies can be respectively controlled by each slot, and the fundamental mode frequency is not affected. Meanwhile, the triple-mode resonator has merit of compact size due to slot perturbation. Besides, bandwidths of the three filter channels can be flexibly controlled without extra matching network. Based on systematic analysis of resonant characteristic of the perturbed triple-mode SIW resonator, a triplexer with second-order Chebyshev frequency response at each channel is synthesized and designed. Furthermore, a compact circuit occupation of only approximately 1.79λg × 1.19λg has been obtained. The synthesized, simulated and measured results show a good agreement.
{"title":"A Miniaturized SIW Triplexer Based on a Triple-Mode Resonator with Slot Perturbation","authors":"L. Xia, Hanyu Xie, Bian Wu, Jianzhong Chen, Shining Sun, Xiaoyu Pang","doi":"10.1109/IEEE-IWS.2019.8803870","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803870","url":null,"abstract":"A miniaturized substrate integrated waveguide (SIW) triplexer with a common triple-mode resonator has been proposed in this paper. The common triple-mode resonator is perturbed by centered cross-shaped slots etched on the top surface of a square SIW cavity. By investigation of surface current distributions on the slot perturbed triple-mode square cavity, the first and second higher-order spurious resonant frequencies can be respectively controlled by each slot, and the fundamental mode frequency is not affected. Meanwhile, the triple-mode resonator has merit of compact size due to slot perturbation. Besides, bandwidths of the three filter channels can be flexibly controlled without extra matching network. Based on systematic analysis of resonant characteristic of the perturbed triple-mode SIW resonator, a triplexer with second-order Chebyshev frequency response at each channel is synthesized and designed. Furthermore, a compact circuit occupation of only approximately 1.79λg × 1.19λg has been obtained. The synthesized, simulated and measured results show a good agreement.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130071291","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803863
Yijing He, Yue Li, Zhijun Zhang, Zhenghe Feng
In this paper, a method of achieving dual-polarized high-gain microstrip antenna for MIMO wireless communication applications is proposed utilizing the slot-loaded higher order mode. By loading half-wavelength slots on electric field nulls of ordinary microstrip antenna operating at higher order mode, equivalent in-phase magnetic current array can be constructed within a single low-profile cavity using simple feed technique. To verify the proposed method, a dual-polarized TM50-mode microstrip antenna with a maximum measured gain of 10.9 dBi is presented firstly, using single-layered substrate and a pair of single feeds. Further, a dual-polarized high-gain magnetic current array with a pair of differential feeds is demonstrated utilizing TM90 mode, achieving a maximum measured gain of 15.5 dBi. Moreover, the low envelop correlation coefficient indicates the good diversity performance of the proposed antennas. The proposed method has the merits of low profile, high isolation and simple feeding, with promising usage in MIMO and diversity applications.
{"title":"Dual-Polarized High-Gain Microstrip Antenna for MIMO Wireless Communication Systems","authors":"Yijing He, Yue Li, Zhijun Zhang, Zhenghe Feng","doi":"10.1109/IEEE-IWS.2019.8803863","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803863","url":null,"abstract":"In this paper, a method of achieving dual-polarized high-gain microstrip antenna for MIMO wireless communication applications is proposed utilizing the slot-loaded higher order mode. By loading half-wavelength slots on electric field nulls of ordinary microstrip antenna operating at higher order mode, equivalent in-phase magnetic current array can be constructed within a single low-profile cavity using simple feed technique. To verify the proposed method, a dual-polarized TM50-mode microstrip antenna with a maximum measured gain of 10.9 dBi is presented firstly, using single-layered substrate and a pair of single feeds. Further, a dual-polarized high-gain magnetic current array with a pair of differential feeds is demonstrated utilizing TM90 mode, achieving a maximum measured gain of 15.5 dBi. Moreover, the low envelop correlation coefficient indicates the good diversity performance of the proposed antennas. The proposed method has the merits of low profile, high isolation and simple feeding, with promising usage in MIMO and diversity applications.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128879447","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803995
Donghao Li, K. Xu
A fifth-order bandpass filter (BPF) using three pairs of coupled lines and two shorted stepped-impedance stubs is proposed in this paper. Five transmission poles (TPs) within the passband and six deep transmission zeros (TZs) from 0 to 2f0 (f0:passband center frequency) can be realized through input admittance calculation. For demonstration, a sharp roll-off BPF prototype centered at 2 GHz with good in-band characteristics (insertion losses and return losses) and high stopband rejections is designed, whose 3-dB fractional bandwidth is of 34%.
{"title":"Sharp Roll-Off Bandpass Filter Using Coupled Lines and Stepped-Impedance Stubs","authors":"Donghao Li, K. Xu","doi":"10.1109/IEEE-IWS.2019.8803995","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803995","url":null,"abstract":"A fifth-order bandpass filter (BPF) using three pairs of coupled lines and two shorted stepped-impedance stubs is proposed in this paper. Five transmission poles (TPs) within the passband and six deep transmission zeros (TZs) from 0 to 2f0 (f0:passband center frequency) can be realized through input admittance calculation. For demonstration, a sharp roll-off BPF prototype centered at 2 GHz with good in-band characteristics (insertion losses and return losses) and high stopband rejections is designed, whose 3-dB fractional bandwidth is of 34%.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122390147","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803847
Songhu Ge, Hongbo Liu, Yongcai Liu, Jinling Xing, Jin Meng
In this paper, a baseband digital canceller is designed and implemented to cancel the co-site interference. Especially, in order to achieve high-speed low-latency cancellation performance, a transposed form retimed delayed LMS (TF-RDLMS) filter structure is introduced and extended to complex signal form. In the proposed complex TF-RDLMS filter, the basic Processing Module (PM) is established with a set of real cross-coupling signal flows. Then, the canceller is implemented with Xilinx field programmable gate array (FPGA) chip by cascading several PMs. Finally, the validity and effectiveness of the implemented canceller is confirmed by experimental results. It is shown that the canceller can achieve 31 dB and 27 dB cancellation performance for 5 MHz and 10 MHz interference signal, respectively.
{"title":"Design and Implementation of A Real-time Baseband Adaptive Digital Interference Canceller","authors":"Songhu Ge, Hongbo Liu, Yongcai Liu, Jinling Xing, Jin Meng","doi":"10.1109/IEEE-IWS.2019.8803847","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803847","url":null,"abstract":"In this paper, a baseband digital canceller is designed and implemented to cancel the co-site interference. Especially, in order to achieve high-speed low-latency cancellation performance, a transposed form retimed delayed LMS (TF-RDLMS) filter structure is introduced and extended to complex signal form. In the proposed complex TF-RDLMS filter, the basic Processing Module (PM) is established with a set of real cross-coupling signal flows. Then, the canceller is implemented with Xilinx field programmable gate array (FPGA) chip by cascading several PMs. Finally, the validity and effectiveness of the implemented canceller is confirmed by experimental results. It is shown that the canceller can achieve 31 dB and 27 dB cancellation performance for 5 MHz and 10 MHz interference signal, respectively.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122490908","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803899
J. Modelski, Y. Yashchyshyn, Grzegorz Bogdan
The 4D (four-dimensional) antenna array introduces time as an additional degree of freedom in antenna beamforming. Periodical on/off switching applied to each element of the antenna array leads to generation of sidebands which are suitable for multi-channel transmission and smart beamforming. This paper provides an overview of the state of the art in the area of 4D antennas with focus on technical limitations and achievable performance.
{"title":"4D Antennas Design and Technology – the State of the Art","authors":"J. Modelski, Y. Yashchyshyn, Grzegorz Bogdan","doi":"10.1109/IEEE-IWS.2019.8803899","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803899","url":null,"abstract":"The 4D (four-dimensional) antenna array introduces time as an additional degree of freedom in antenna beamforming. Periodical on/off switching applied to each element of the antenna array leads to generation of sidebands which are suitable for multi-channel transmission and smart beamforming. This paper provides an overview of the state of the art in the area of 4D antennas with focus on technical limitations and achievable performance.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121004812","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 : 2019-05-01DOI: 10.1109/IEEE-IWS.2019.8803912
Shiyu Zhang, W. Whittow, D. Cadman, R. Mittra, J. Vardaxoglou
This paper explores advanced additive manufacturing for creating RF circuits and componentry and analyses their RF performance. Additive manufacture of such objects allows novel and complex structures to be fabricated to realize high gain antenna systems with low material costs, reduced manual fabrication and low impact on the environment. Furthermore, it currently offers the RF performance that can be competitive through further advances in manufacturing processes and materials.
{"title":"Additive Manufacturing for High Performance Antennas and RF Components","authors":"Shiyu Zhang, W. Whittow, D. Cadman, R. Mittra, J. Vardaxoglou","doi":"10.1109/IEEE-IWS.2019.8803912","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8803912","url":null,"abstract":"This paper explores advanced additive manufacturing for creating RF circuits and componentry and analyses their RF performance. Additive manufacture of such objects allows novel and complex structures to be fabricated to realize high gain antenna systems with low material costs, reduced manual fabrication and low impact on the environment. Furthermore, it currently offers the RF performance that can be competitive through further advances in manufacturing processes and materials.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126677466","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 polarization switchable ultra-wideband horn antenna with feeding network is designed and implemented. A single antenna can realize four switchable polarization modes (vertical polarization, horizontal polarization, left-hand circular polarization, and right-hand circular polarization) with ultra-wideband characteristics in the microwave and millimeter wave frequency band by an electronically controlled mechanical switch. TTL (Transistor-Transistor Logic) level is adopted as controlled electrical signal. The antenna can significantly improve test efficiency by avoiding manual switching of the antenna polarization mode. The presented antenna has a super wide bandwidth of 9.3GHz, worked well from 0.7GHz to 10GHz. Measured results for VSWR, radiation pattern, and gain of the designed horn antenna are provided.
{"title":"A Polarization Switchable Ultra-Wideband Horn Antenna with Feeding Network","authors":"Nan Hu, Wenqing Xie, Q. Zeng, Jianrui Liu, Shuang Liu, Lixin Zhao, Changyong Yuan, Yanbin Luo, Yong Wu","doi":"10.1109/IEEE-IWS.2019.8804070","DOIUrl":"https://doi.org/10.1109/IEEE-IWS.2019.8804070","url":null,"abstract":"A polarization switchable ultra-wideband horn antenna with feeding network is designed and implemented. A single antenna can realize four switchable polarization modes (vertical polarization, horizontal polarization, left-hand circular polarization, and right-hand circular polarization) with ultra-wideband characteristics in the microwave and millimeter wave frequency band by an electronically controlled mechanical switch. TTL (Transistor-Transistor Logic) level is adopted as controlled electrical signal. The antenna can significantly improve test efficiency by avoiding manual switching of the antenna polarization mode. The presented antenna has a super wide bandwidth of 9.3GHz, worked well from 0.7GHz to 10GHz. Measured results for VSWR, radiation pattern, and gain of the designed horn antenna are provided.","PeriodicalId":306297,"journal":{"name":"2019 IEEE MTT-S International Wireless Symposium (IWS)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126943328","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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