Pub Date : 2004-06-06DOI: 10.1109/MWSYM.2004.1338929
T. Nakatani, T. Matsuura, K. Ogawa
A simple method has been proposed for the measurement of the output power and phase characteristics of the IM3 components appearing in multi-stage power amplifiers. By adopting a unique definition of the phase for the IM3 components that is independent of the delay time caused by transmission line and other instrument devices, it is possible to measure the phase, merely by using a vector signal analyzer. It is demonstrated that an accurate estimation of the IM3 characteristics of a two-stage cascaded power amplifier for cellular radio handheld terminals can be made by using the IM3 characteristics of the 1st and 2nd-stage amplifiers measured by the proposed method.
{"title":"A simple method for measuring the IM3 components of multi-stage cascaded power amplifiers considering the phase characteristics","authors":"T. Nakatani, T. Matsuura, K. Ogawa","doi":"10.1109/MWSYM.2004.1338929","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1338929","url":null,"abstract":"A simple method has been proposed for the measurement of the output power and phase characteristics of the IM3 components appearing in multi-stage power amplifiers. By adopting a unique definition of the phase for the IM3 components that is independent of the delay time caused by transmission line and other instrument devices, it is possible to measure the phase, merely by using a vector signal analyzer. It is demonstrated that an accurate estimation of the IM3 characteristics of a two-stage cascaded power amplifier for cellular radio handheld terminals can be made by using the IM3 characteristics of the 1st and 2nd-stage amplifiers measured by the proposed method.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129426827","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1338881
V. Wallace, A. Fitzgerald, B. Cole, R. Pye, D. Arnone
The technology behind optically-driven terahertz (THz) system is now well developed and commercial applications of this new technology are now beginning to emerge. The terahertz frequency range (0.1 to 10 THz) covers far infrared wavelengths. Terahertz light has the advantages that it is non-ionizing and is not highly scattered like visible and near-infrared light. Terahertz pulsed imaging (TPI) is a reflection imaging method that has been used successfully in the past for non-medical applications. More recently, a portable TPI has been used to image a variety of human tissues, like teeth, skin and breast.
{"title":"Biomedical applications of THz imaging","authors":"V. Wallace, A. Fitzgerald, B. Cole, R. Pye, D. Arnone","doi":"10.1109/MWSYM.2004.1338881","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1338881","url":null,"abstract":"The technology behind optically-driven terahertz (THz) system is now well developed and commercial applications of this new technology are now beginning to emerge. The terahertz frequency range (0.1 to 10 THz) covers far infrared wavelengths. Terahertz light has the advantages that it is non-ionizing and is not highly scattered like visible and near-infrared light. Terahertz pulsed imaging (TPI) is a reflection imaging method that has been used successfully in the past for non-medical applications. More recently, a portable TPI has been used to image a variety of human tissues, like teeth, skin and breast.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130399579","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1339010
H. T. Jeong, Hyun Seok Lee, Sung Wook Kim, Ik-Soo Chang
The design of high power push-pull amplifier and unique balun structure are presented. The balun consists of a dielectric resonator and slot line. In comparison with previous balun made up with cavity fixture by G.J. Laughlin (1976), the proposed one can be easily implemented due to its simple structure. The experimental result shows that push-pull amplifier has a gain of 13.7dB at the 2.1GHz W-CDMA band. With two carrier W-CDMA signal, the push-pull amplifier achieves an efficiency of 18.8% at the 41.5dBm average output power and ACLR test results of 36.7dBc at the 5MHz offset and 43.6dBc at the 10MHz offset.
{"title":"Design of push-pull amplifier using slot line balun with dielectric resonator","authors":"H. T. Jeong, Hyun Seok Lee, Sung Wook Kim, Ik-Soo Chang","doi":"10.1109/MWSYM.2004.1339010","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1339010","url":null,"abstract":"The design of high power push-pull amplifier and unique balun structure are presented. The balun consists of a dielectric resonator and slot line. In comparison with previous balun made up with cavity fixture by G.J. Laughlin (1976), the proposed one can be easily implemented due to its simple structure. The experimental result shows that push-pull amplifier has a gain of 13.7dB at the 2.1GHz W-CDMA band. With two carrier W-CDMA signal, the push-pull amplifier achieves an efficiency of 18.8% at the 41.5dBm average output power and ACLR test results of 36.7dBc at the 5MHz offset and 43.6dBc at the 10MHz offset.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123655797","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1338811
O. Lee, Jeong‐Geun Kim, S. Jeon, Jaewoo Park, Songchel Hong
This paper presents a VCO with frequency doubler and a 1/8 frequency divider MMICs for a V-band PLL using cost effective InGaP/GaAs HBT technology. The VCO was implemented common base inductive topology with 27.5 GHz differential outputs and 55 GHz doubler output. The 1/8 frequency divider was implemented by connecting two stages of static frequency divider circuits after dynamic one. To achieve higher operating frequency, active loads are used in the dynamic frequency divider. The maximum operating frequency of the 1/8 frequency divider is higher than f/sub T//2 of transistor.
{"title":"A V-band VCO and frequency divider MMICs for phased-locked loop","authors":"O. Lee, Jeong‐Geun Kim, S. Jeon, Jaewoo Park, Songchel Hong","doi":"10.1109/MWSYM.2004.1338811","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1338811","url":null,"abstract":"This paper presents a VCO with frequency doubler and a 1/8 frequency divider MMICs for a V-band PLL using cost effective InGaP/GaAs HBT technology. The VCO was implemented common base inductive topology with 27.5 GHz differential outputs and 55 GHz doubler output. The 1/8 frequency divider was implemented by connecting two stages of static frequency divider circuits after dynamic one. To achieve higher operating frequency, active loads are used in the dynamic frequency divider. The maximum operating frequency of the 1/8 frequency divider is higher than f/sub T//2 of transistor.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"44 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114095847","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1339155
J. Hirshfield, A. Vikharev, O. Ivanov, A. Gorbachev, V. Isaev, M. A. Lapointe, V. Yakovlev, O.A. Nezevenko, S. Gold, A. Kinkead
Active RF pulse compression relies on use of a component in the RF circuit that can be switched from one state to another in a time much shorter than the desired RF pulse width. This paper reviews work wherein (a) the switching is accomplished using rapidly-ionized plasma tubes to detune a resonator that forms one reflector for an energy storage cavity, and (b) the switching is accomplished by rapidly switching the dielectric constant of low-loss ferroelectric elements in an energy storage cavity. Recent experiments to produce >50 MW compressed rf pulses at 11.4 GHz using plasma switches are described, while recent designs for ferroelectric switches are also described. The latter may have the advantage of permitting more than one switching during a single RF input pulse, thus allowing the efficiency to be greater than that for a single switching.
{"title":"Active RF pulse compression for accelerator applications","authors":"J. Hirshfield, A. Vikharev, O. Ivanov, A. Gorbachev, V. Isaev, M. A. Lapointe, V. Yakovlev, O.A. Nezevenko, S. Gold, A. Kinkead","doi":"10.1109/MWSYM.2004.1339155","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1339155","url":null,"abstract":"Active RF pulse compression relies on use of a component in the RF circuit that can be switched from one state to another in a time much shorter than the desired RF pulse width. This paper reviews work wherein (a) the switching is accomplished using rapidly-ionized plasma tubes to detune a resonator that forms one reflector for an energy storage cavity, and (b) the switching is accomplished by rapidly switching the dielectric constant of low-loss ferroelectric elements in an energy storage cavity. Recent experiments to produce >50 MW compressed rf pulses at 11.4 GHz using plasma switches are described, while recent designs for ferroelectric switches are also described. The latter may have the advantage of permitting more than one switching during a single RF input pulse, thus allowing the efficiency to be greater than that for a single switching.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121492477","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1338903
M. Micovic, A. Kurdoghlian, H. Moyer, P. Hashimoto, A. Schmitz, I. Milosavjevic, P.J. Willadesn, W. Wong, J. Duvall, M. Hu, M. Delaney, D. Chow
We report the development of Ka-band GaN MMIC power amplifiers in CPW and microstrip topologies. This is, to the best of our knowledge, the first demonstration of millimeter wave MMIC's in GaN technology. The single stage CPW MMIC utilizes four 2/spl times/100 /spl mu/m wide GaN HFET's whilst four 4/spl times/60 /spl mu/m wide HFET's with individual through substrate source vias were used for the microstrip MMIC's. The CPW amplifier has a gain peak of 8 dB at 33 GHz with 4 GHz bandwidth while the microstrip amplifier has a peak gain of 9 dB at 27 GHz and gain higher than 8 dB over the 2.45 GHz to 33 GHz frequency range. The saturated CW output power of the amplifiers measured into a 50 /spl Omega/ system at 33 GHz was, respectively, 1.6 W for the microstrip MMIC. The corresponding power density of 2.3 W per mm of gate periphery for the microstrip MMIC is by a factor of 4 higher than that of a typical GaAs pHEMT MMIC at this frequency. Microstrip MMIC performance was further improved through external output impedance matching, resulting in power levels of up to 2.8 W (27% associated PAE) and peak PAE's of up to 36.2% (1.2 W associated power).
{"title":"Ka-band MMIC power amplifier in GaN HFET technology","authors":"M. Micovic, A. Kurdoghlian, H. Moyer, P. Hashimoto, A. Schmitz, I. Milosavjevic, P.J. Willadesn, W. Wong, J. Duvall, M. Hu, M. Delaney, D. Chow","doi":"10.1109/MWSYM.2004.1338903","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1338903","url":null,"abstract":"We report the development of Ka-band GaN MMIC power amplifiers in CPW and microstrip topologies. This is, to the best of our knowledge, the first demonstration of millimeter wave MMIC's in GaN technology. The single stage CPW MMIC utilizes four 2/spl times/100 /spl mu/m wide GaN HFET's whilst four 4/spl times/60 /spl mu/m wide HFET's with individual through substrate source vias were used for the microstrip MMIC's. The CPW amplifier has a gain peak of 8 dB at 33 GHz with 4 GHz bandwidth while the microstrip amplifier has a peak gain of 9 dB at 27 GHz and gain higher than 8 dB over the 2.45 GHz to 33 GHz frequency range. The saturated CW output power of the amplifiers measured into a 50 /spl Omega/ system at 33 GHz was, respectively, 1.6 W for the microstrip MMIC. The corresponding power density of 2.3 W per mm of gate periphery for the microstrip MMIC is by a factor of 4 higher than that of a typical GaAs pHEMT MMIC at this frequency. Microstrip MMIC performance was further improved through external output impedance matching, resulting in power levels of up to 2.8 W (27% associated PAE) and peak PAE's of up to 36.2% (1.2 W associated power).","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121670048","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1339145
R. Wanner, G. Olbrich, H. Jorke, J. Luy, S. Heim, E. Kasper, P. Russer
In this paper we describe the experimental verification of the resonance phase effect for the first time. A silicon heterojunction bipolar transistor (HBT) has been enhanced to a resonance phase transistor (RPT) by the concept of transit time delay, using a thickened base layer. The RPT shows a current amplification far beyond its transit frequency f/sub T/. As the purpose of this paper is to demonstrate the resonance phase effect, a thick base layer of 120 nm was incorporated, thus decreasing the resonance frequency and facilitating the measurement. In the setup analyzed, a current gain of 6.5 dB has been measured at 40 GHz. By downscaling the base width the resonance frequency is expected to be increasable by a factor of four.
{"title":"Experimental verification of the resonance phase transistor concept","authors":"R. Wanner, G. Olbrich, H. Jorke, J. Luy, S. Heim, E. Kasper, P. Russer","doi":"10.1109/MWSYM.2004.1339145","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1339145","url":null,"abstract":"In this paper we describe the experimental verification of the resonance phase effect for the first time. A silicon heterojunction bipolar transistor (HBT) has been enhanced to a resonance phase transistor (RPT) by the concept of transit time delay, using a thickened base layer. The RPT shows a current amplification far beyond its transit frequency f/sub T/. As the purpose of this paper is to demonstrate the resonance phase effect, a thick base layer of 120 nm was incorporated, thus decreasing the resonance frequency and facilitating the measurement. In the setup analyzed, a current gain of 6.5 dB has been measured at 40 GHz. By downscaling the base width the resonance frequency is expected to be increasable by a factor of four.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114842761","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1339211
C. Baylis, L. Dunleavy, J.E. Daniel
New methods are presented for direct extraction of thermal resistance and capacitance from pulsed IV measurements. Because thermal effects are frequency dependent, a thermal circuit is used in many models to characterize the device channel temperature as a function of frequency. Thermal resistance is determined using pulsed IV data sets taken at varied ambient temperature, while the thermal capacitance is found through use of a new normalized difference unit (NDU) for IV data. Determination of thermal subcircuit parameters from readily available pulsed IV measurements reduces the complexity of electrothermal model development for microwave transistors.
{"title":"Direct measurement of thermal circuit parameters using pulsed IV and the normalized difference unit","authors":"C. Baylis, L. Dunleavy, J.E. Daniel","doi":"10.1109/MWSYM.2004.1339211","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1339211","url":null,"abstract":"New methods are presented for direct extraction of thermal resistance and capacitance from pulsed IV measurements. Because thermal effects are frequency dependent, a thermal circuit is used in many models to characterize the device channel temperature as a function of frequency. Thermal resistance is determined using pulsed IV data sets taken at varied ambient temperature, while the thermal capacitance is found through use of a new normalized difference unit (NDU) for IV data. Determination of thermal subcircuit parameters from readily available pulsed IV measurements reduces the complexity of electrothermal model development for microwave transistors.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127710386","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1338804
Tomás O 'sullivan, Robert A York, B. Noren, Peter M Asbeck
As the complexity of modern modulation schemes increases, the noise levels inserted in the receive band by the transmitter are also increased. In this paper a technique to enhance the isolation of a duplexer is introduced, which reduces the noise levels in the receive band of the system. Feedforward techniques are used to create an adaptive null in the receive band, which can be targeted at any channel across the band. This null has been shown to give an improved isolation of 20 dB for the duplexer over a 2 MHz bandwidth. This feedforward system is implemented using a BST phase shifter to enable tenability of the enhancement null.
{"title":"Adaptive duplexer implemented using feedforward technique with a BST phase shifter","authors":"Tomás O 'sullivan, Robert A York, B. Noren, Peter M Asbeck","doi":"10.1109/MWSYM.2004.1338804","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1338804","url":null,"abstract":"As the complexity of modern modulation schemes increases, the noise levels inserted in the receive band by the transmitter are also increased. In this paper a technique to enhance the isolation of a duplexer is introduced, which reduces the noise levels in the receive band of the system. Feedforward techniques are used to create an adaptive null in the receive band, which can be targeted at any channel across the band. This null has been shown to give an improved isolation of 20 dB for the duplexer over a 2 MHz bandwidth. This feedforward system is implemented using a BST phase shifter to enable tenability of the enhancement null.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"39 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125739994","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 : 2004-06-06DOI: 10.1109/MWSYM.2004.1336073
J. Sidén, A. Koptioug, M. Gulliksson
Smart diaper moisture detection system described is a paper-based disposable moisture-activated RFID system that could be incorporated into the traditional cellulose-based diaper. The tag is semi-passive in the sense that it has no internal battery but incorporates a built-in energy conversion sensor (Action-Activated Tag). The tag with sensor unit is optimized for low-cost manufacturing, utilizes screen-printing with electrically conductive ink on paper-based substrates and inherits very low EM radiation. A discussion on the manufacturability and cost efficiency of the system is presented. A prototype system is shown and other possible application areas of the system are mentioned.
{"title":"The \"smart\" diaper moisture detection system","authors":"J. Sidén, A. Koptioug, M. Gulliksson","doi":"10.1109/MWSYM.2004.1336073","DOIUrl":"https://doi.org/10.1109/MWSYM.2004.1336073","url":null,"abstract":"Smart diaper moisture detection system described is a paper-based disposable moisture-activated RFID system that could be incorporated into the traditional cellulose-based diaper. The tag is semi-passive in the sense that it has no internal battery but incorporates a built-in energy conversion sensor (Action-Activated Tag). The tag with sensor unit is optimized for low-cost manufacturing, utilizes screen-printing with electrically conductive ink on paper-based substrates and inherits very low EM radiation. A discussion on the manufacturability and cost efficiency of the system is presented. A prototype system is shown and other possible application areas of the system are mentioned.","PeriodicalId":334675,"journal":{"name":"2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115938743","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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