Pub Date : 2015-04-12DOI: 10.1109/FCS.2015.7138948
K. Liang, A. Zhang, Zhiqiang Yang, Weiliang Chen, Weibo Wang, Long Bai, Guitao Fu
TWOTFT has been studied and implemented according to the similar principles to those of TWSTFT. We initially constructed the experiment system for TWOTFT and done some experiments such as time and frequency transfer through the laboratory optical fiber and the real optical fiber links including the real link with 109 km length at NIM. We can get the time stability of less than 6 ps/s and 0.9 ps/100s, and the standard uncertainty of less than 200 ps for time transfer.
{"title":"Preliminary time transfer through optical fiber at NIM","authors":"K. Liang, A. Zhang, Zhiqiang Yang, Weiliang Chen, Weibo Wang, Long Bai, Guitao Fu","doi":"10.1109/FCS.2015.7138948","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138948","url":null,"abstract":"TWOTFT has been studied and implemented according to the similar principles to those of TWSTFT. We initially constructed the experiment system for TWOTFT and done some experiments such as time and frequency transfer through the laboratory optical fiber and the real optical fiber links including the real link with 109 km length at NIM. We can get the time stability of less than 6 ps/s and 0.9 ps/100s, and the standard uncertainty of less than 200 ps for time transfer.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"1 1","pages":"742-746"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91295842","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138841
L. Sliwczynski, P. Krehlik, M. Lipinski, K. Turza, A. Binczewski
In the paper we are presenting the results of the experiments we performed with sending the frequency signals (10 MHz) to the remote location exploiting the optical dense wavelength division multiplexed telecommunication network. To stabilize the phase of the frequency signal we applied the approach with the electronic stabilization of the propagation delay. We measured the residual instability resulting from the fact that in a telecommunication network the signals in the forward and backward direction do not share the same fiber and are transmitted through different pieces of equipment when passing through reconfigurable optical add drop multiplexers or optical amplifiers. Our experiments show that results may depend substantially on the route of the link. For all tested links, however, the stability was better than the stability of the signal generated by commercial 5071A cesium standard. In case of one link even the stability better than stability of H-maser was observed for averaging times longer than 1000 s.
{"title":"Frequency distribution in delay-stabilized optical DWDM network over the distance of 3000 km","authors":"L. Sliwczynski, P. Krehlik, M. Lipinski, K. Turza, A. Binczewski","doi":"10.1109/FCS.2015.7138841","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138841","url":null,"abstract":"In the paper we are presenting the results of the experiments we performed with sending the frequency signals (10 MHz) to the remote location exploiting the optical dense wavelength division multiplexed telecommunication network. To stabilize the phase of the frequency signal we applied the approach with the electronic stabilization of the propagation delay. We measured the residual instability resulting from the fact that in a telecommunication network the signals in the forward and backward direction do not share the same fiber and are transmitted through different pieces of equipment when passing through reconfigurable optical add drop multiplexers or optical amplifiers. Our experiments show that results may depend substantially on the route of the link. For all tested links, however, the stability was better than the stability of the signal generated by commercial 5071A cesium standard. In case of one link even the stability better than stability of H-maser was observed for averaging times longer than 1000 s.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"44 1","pages":"280-283"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85733946","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138861
Qinghua Wang, F. Droz, P. Rochat
A robust clock ensemble is proposed for the time and frequency reference system to improve the robustness and performance of the system. Studies on the feasibility of hardware and algorithm approaches have been conducted. All clocks in the ensemble are locked in phase and frequency via the steering loop. The system performs corrections on the master clock in function of weighted averaging of clocks to generate one ensemble output, and the clock fault detection and compensation is implemented in real time with minimum three clocks powered. As the design has been demonstrated on an elegant breadboard of the Robust Onboard Frequency Reference Subsystem, this concept is proposed for the next-generation of Precise Timing Facility. Simulation results have demonstrated its capability and simplicity to provide a smooth and reliable timing or frequency output even in presence of clock feared events.
{"title":"Robust clock ensemble for time and frequency reference system","authors":"Qinghua Wang, F. Droz, P. Rochat","doi":"10.1109/FCS.2015.7138861","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138861","url":null,"abstract":"A robust clock ensemble is proposed for the time and frequency reference system to improve the robustness and performance of the system. Studies on the feasibility of hardware and algorithm approaches have been conducted. All clocks in the ensemble are locked in phase and frequency via the steering loop. The system performs corrections on the master clock in function of weighted averaging of clocks to generate one ensemble output, and the clock fault detection and compensation is implemented in real time with minimum three clocks powered. As the design has been demonstrated on an elegant breadboard of the Robust Onboard Frequency Reference Subsystem, this concept is proposed for the next-generation of Precise Timing Facility. Simulation results have demonstrated its capability and simplicity to provide a smooth and reliable timing or frequency output even in presence of clock feared events.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"98 1","pages":"374-378"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73529147","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138900
J. Humphries, M. Gallagher, D. Gallagher, A. Weeks, D. Malocha
The universal software radio peripheral (USRP) is a versatile software defined radio (SDR) platform, developed by Ettus Research™, which is intended for a wide variety of applications ranging from communication links to RADAR. We have investigated another application of the USRP by implementing a transceiver capable of interrogating passive, wireless surface acoustic wave (SAW) sensors centered at 915MHz. Interrogation of wideband orthogonal frequency coded (OFC) SAW sensors imposes strict requirements on the timing and synchronization of the transceiver. In the standard mode of operation, samples are generated and streamed between the USRP and host computer, introducing latency and bandwidth limitations due to the sampling bus. To achieve the performance required for this application, the USRP FPGA has been modified to introduce new functionality. Extraction of the sensor temperature is accomplished with a custom matched filter correlator. The system is capable of interrogating multiple sensors and can quickly reconfigure the USRP. Demonstration of the USRP wireless sensor system is achieved by interrogating wireless SAW OFC sensors at 915MHz and extracting the sensor temperature.
{"title":"Interrogation of orthogonal frequency coded SAW sensors using the USRP","authors":"J. Humphries, M. Gallagher, D. Gallagher, A. Weeks, D. Malocha","doi":"10.1109/FCS.2015.7138900","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138900","url":null,"abstract":"The universal software radio peripheral (USRP) is a versatile software defined radio (SDR) platform, developed by Ettus Research™, which is intended for a wide variety of applications ranging from communication links to RADAR. We have investigated another application of the USRP by implementing a transceiver capable of interrogating passive, wireless surface acoustic wave (SAW) sensors centered at 915MHz. Interrogation of wideband orthogonal frequency coded (OFC) SAW sensors imposes strict requirements on the timing and synchronization of the transceiver. In the standard mode of operation, samples are generated and streamed between the USRP and host computer, introducing latency and bandwidth limitations due to the sampling bus. To achieve the performance required for this application, the USRP FPGA has been modified to introduce new functionality. Extraction of the sensor temperature is accomplished with a custom matched filter correlator. The system is capable of interrogating multiple sensors and can quickly reconfigure the USRP. Demonstration of the USRP wireless sensor system is achieved by interrogating wireless SAW OFC sensors at 915MHz and extracting the sensor temperature.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"34 8","pages":"530-535"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/FCS.2015.7138900","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72475996","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138880
Charis Basetas, A. Kanteres, P. Sotiriadis
This work discusses hardware implementation considerations for a novel Multi-Step Look-Ahead modulation architecture which improves on the stability and dynamic range of conventional Σ-Δ modulators for all-digital frequency synthesis applications. The basic theoretical concepts of the architecture are analyzed and an appropriate general hardware implementation of the required mathematical operations is presented. It is shown that hardware complexity reduction is possible when noise-shaping filters with convenient coefficients are utilized. Moreover, FPGA and IC implementation examples for a specific noise-shaping filter are given, accompanied by power, area and delay estimations.
{"title":"Hardware implementation aspects of Multi-Step Look-Ahead Σ-Δ modulation-like architectures for all-digital frequency synthesis applications","authors":"Charis Basetas, A. Kanteres, P. Sotiriadis","doi":"10.1109/FCS.2015.7138880","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138880","url":null,"abstract":"This work discusses hardware implementation considerations for a novel Multi-Step Look-Ahead modulation architecture which improves on the stability and dynamic range of conventional Σ-Δ modulators for all-digital frequency synthesis applications. The basic theoretical concepts of the architecture are analyzed and an appropriate general hardware implementation of the required mathematical operations is presented. It is shown that hardware complexity reduction is possible when noise-shaping filters with convenient coefficients are utilized. Moreover, FPGA and IC implementation examples for a specific noise-shaping filter are given, accompanied by power, area and delay estimations.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"21 3","pages":"452-455"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/FCS.2015.7138880","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72463417","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138792
U. Rohde, A. Poddar, E. Rubiola, M. Silaghi
This paper describes oscillator noise measurement techniques, challenges and associated measurement uncertainty. The cross-correlation method used in modern PN measurement equipments, can present erroneous result, depending upon phase-inversion, harmonics, o/p load mismatch, and cable length. This discussion is imperative for low phase noise signal sources, validated with 2.4 GHz SAW oscillator, and discussed steps for mitigating these issues by using filtering/phase-matching N/W.
{"title":"Frequency signal source's PN (phase noise) measurements: Challenges and uncertainty","authors":"U. Rohde, A. Poddar, E. Rubiola, M. Silaghi","doi":"10.1109/FCS.2015.7138792","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138792","url":null,"abstract":"This paper describes oscillator noise measurement techniques, challenges and associated measurement uncertainty. The cross-correlation method used in modern PN measurement equipments, can present erroneous result, depending upon phase-inversion, harmonics, o/p load mismatch, and cable length. This discussion is imperative for low phase noise signal sources, validated with 2.4 GHz SAW oscillator, and discussed steps for mitigating these issues by using filtering/phase-matching N/W.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"54 1","pages":"62-67"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75063771","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138930
P. Defraigne, J. Sleewaegen
Precise Point Positioning (PPP) is a zero-difference single-station technique that has proved to be very effective for time and frequency transfer, enabling the comparison of atomic clocks with a precision of a hundred picoseconds and a one day stability below the 1e-15 level. It was however noted that for some receivers, a frequency difference is observed between the clock solution based on the code measurements and the clock solution based on the carrier phase measurements. These observations reveal some inconsistency between the code and carrier phases measured by the receiver. One explanation of this discrepancy is the time offset that can exist for some receivers between the code and carrier phase latching. This paper explains how a code-phase bias in the receiver hardware can induce a frequency difference between the code and the carrier phase clock solutions. The impact on PPP is then quantified. Finally, the possibility to determine this code-phase bias in the PPP modeling is investigated, and the first results are presented.
{"title":"Correction for code-phase clock bias in PPP","authors":"P. Defraigne, J. Sleewaegen","doi":"10.1109/FCS.2015.7138930","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138930","url":null,"abstract":"Precise Point Positioning (PPP) is a zero-difference single-station technique that has proved to be very effective for time and frequency transfer, enabling the comparison of atomic clocks with a precision of a hundred picoseconds and a one day stability below the 1e-15 level. It was however noted that for some receivers, a frequency difference is observed between the clock solution based on the code measurements and the clock solution based on the carrier phase measurements. These observations reveal some inconsistency between the code and carrier phases measured by the receiver. One explanation of this discrepancy is the time offset that can exist for some receivers between the code and carrier phase latching. This paper explains how a code-phase bias in the receiver hardware can induce a frequency difference between the code and the carrier phase clock solutions. The impact on PPP is then quantified. Finally, the possibility to determine this code-phase bias in the PPP modeling is investigated, and the first results are presented.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"17 1","pages":"662-666"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74622518","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138962
Songbai Kang, M. Gharavipour, F. Gruet, C. Affolderbach, G. Mileti
We report on the development of a compact laserpumped Rb clock based on the pulsed optical pumping (POP) technique, in view of future industrial applications. The clock Physics Package (PP) is based on a compact magnetron-type microwave cavity of 45 cm3 volume, and our current clock PP has a volume of only 0.8 liters, including temperature control and magnetic shields. This clock PP is completed by a newlydeveloped frequency-stabilized laser head of 2.5 liters overall volume, with an acoustic optical modulator (AOM) integrated within the laser head for switching the laser output power. Due to the highly uniform magnetic field inside the microwave cavity, Ramsey signals with high contrast of up to 35% and with a linewidth of 160 Hz have been demonstrated. A typical shortterm clock stability of 2.4×10-13τ-1/2 is measured. Thanks to the pulsed operation, the light-shift effect has been considerably suppressed as compared to previously demonstrated continuous-wave (CW) clock operation using the same clock PP, which is expected to enable improved long-term clock stabilities down to the 10-14 level or better.
{"title":"Compact and high-performance Rb clock based on pulsed optical pumping for industrial application","authors":"Songbai Kang, M. Gharavipour, F. Gruet, C. Affolderbach, G. Mileti","doi":"10.1109/FCS.2015.7138962","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138962","url":null,"abstract":"We report on the development of a compact laserpumped Rb clock based on the pulsed optical pumping (POP) technique, in view of future industrial applications. The clock Physics Package (PP) is based on a compact magnetron-type microwave cavity of 45 cm3 volume, and our current clock PP has a volume of only 0.8 liters, including temperature control and magnetic shields. This clock PP is completed by a newlydeveloped frequency-stabilized laser head of 2.5 liters overall volume, with an acoustic optical modulator (AOM) integrated within the laser head for switching the laser output power. Due to the highly uniform magnetic field inside the microwave cavity, Ramsey signals with high contrast of up to 35% and with a linewidth of 160 Hz have been demonstrated. A typical shortterm clock stability of 2.4×10-13τ-1/2 is measured. Thanks to the pulsed operation, the light-shift effect has been considerably suppressed as compared to previously demonstrated continuous-wave (CW) clock operation using the same clock PP, which is expected to enable improved long-term clock stabilities down to the 10-14 level or better.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"38 1","pages":"800-803"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81544035","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138914
Meifang Wu, Pei Wei, Xuhai Yang, Shou-gang Zhang
This paper aims to research and determine GEO satellite clock bias during maneuvering. By analyzing of GEO satellite clock bias data, quadratic polynomials, cubic spline and Lagrange are chose as interpolation methods. The result of the test in this paper shows that in most cases, cubic spline interpolation is the best one of the three interpolation methods. And the accuracy of cubic spline interpolation is at the level of 0.08ns~0.38ns which can meet the actual demand; besides the stability of cubic spline interpolation is obviously better than that of quadratic polynomials and Lagrange interpolations.
{"title":"The method of determination of GEO satellite precise clock bias during maneuvering","authors":"Meifang Wu, Pei Wei, Xuhai Yang, Shou-gang Zhang","doi":"10.1109/FCS.2015.7138914","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138914","url":null,"abstract":"This paper aims to research and determine GEO satellite clock bias during maneuvering. By analyzing of GEO satellite clock bias data, quadratic polynomials, cubic spline and Lagrange are chose as interpolation methods. The result of the test in this paper shows that in most cases, cubic spline interpolation is the best one of the three interpolation methods. And the accuracy of cubic spline interpolation is at the level of 0.08ns~0.38ns which can meet the actual demand; besides the stability of cubic spline interpolation is obviously better than that of quadratic polynomials and Lagrange interpolations.","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"10 1","pages":"591-593"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79945146","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 : 2015-04-12DOI: 10.1109/FCS.2015.7138901
Z. Ramshani, B. B. Narakathu, A. S. G. Reddy, M. Atashbar, J. T. Wabeke, S. Obare
In this study, a shear horizontal mode surface acoustic wave (SH-SAW) sensor, was designed and fabricated for the detection of heavy metals. The SH-SAW sensor was photolithographically fabricated by patterning gold (Au) interdigitated electrodes (IDE) and reflectors on the surface of a 64° YX-LiNbO3 based piezoelectric substrate. A flow cell, with a reservoir volume of 3 μl, which employs inlet and outlet ports for the microfluidic chamber and polydimethylsiloxane (PDMS) based microfluidic channels, was also designed and fabricated using acrylic material. Phenol and naphtho[2,3-a]dipyrido[3,2-h:2'3'-f] phenazine-5,18-dione (QDPPZ) were employed as the sensing layers for mercury and nickel ions, respectively. The frequency based response of the SH-SAW sensor demonstrated picomolar level detection for mercury nitrate (Hg(NO3)2) and nickel nitrate (Ni(NO3)2).
{"title":"SH-SAW-based sensor for heavy metal ion detection","authors":"Z. Ramshani, B. B. Narakathu, A. S. G. Reddy, M. Atashbar, J. T. Wabeke, S. Obare","doi":"10.1109/FCS.2015.7138901","DOIUrl":"https://doi.org/10.1109/FCS.2015.7138901","url":null,"abstract":"In this study, a shear horizontal mode surface acoustic wave (SH-SAW) sensor, was designed and fabricated for the detection of heavy metals. The SH-SAW sensor was photolithographically fabricated by patterning gold (Au) interdigitated electrodes (IDE) and reflectors on the surface of a 64° YX-LiNbO3 based piezoelectric substrate. A flow cell, with a reservoir volume of 3 μl, which employs inlet and outlet ports for the microfluidic chamber and polydimethylsiloxane (PDMS) based microfluidic channels, was also designed and fabricated using acrylic material. Phenol and naphtho[2,3-a]dipyrido[3,2-h:2'3'-f] phenazine-5,18-dione (QDPPZ) were employed as the sensing layers for mercury and nickel ions, respectively. The frequency based response of the SH-SAW sensor demonstrated picomolar level detection for mercury nitrate (Hg(NO3)2) and nickel nitrate (Ni(NO3)2).","PeriodicalId":57667,"journal":{"name":"时间频率公报","volume":"18 1","pages":"536-540"},"PeriodicalIF":0.0,"publicationDate":"2015-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87325994","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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