Pub Date : 1996-03-19DOI: 10.1109/NRSC.1996.551100
E. Ewada
The wide applications of adaptive filtering have necessitated a great deal of theoretical research in order to supply engineers with efficient adaptation algorithms, conditions of stability of the adaptive filter, optimal values of the parameters, ... etc. Therefore, many papers have appeared. However, most of these papers are restricted to the case of stationary adaptive filtering. The analysis of the nonstationary case has not yet received sufficient care and it is far from being complete. This paper has two main goals. The first one is to provide a tutorial review of the theoretical results that have been achieved in the context of nonstationary adaptive filtering and to highlight some open issues. The second goal is to provide new results concerning the tracking properties of the sign-sign algorithm, an adaptive filtering algorithm that has received a great deal of interest in the area of high speed data communications.
{"title":"Advances in nonstationary adaptive signal processing","authors":"E. Ewada","doi":"10.1109/NRSC.1996.551100","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551100","url":null,"abstract":"The wide applications of adaptive filtering have necessitated a great deal of theoretical research in order to supply engineers with efficient adaptation algorithms, conditions of stability of the adaptive filter, optimal values of the parameters, ... etc. Therefore, many papers have appeared. However, most of these papers are restricted to the case of stationary adaptive filtering. The analysis of the nonstationary case has not yet received sufficient care and it is far from being complete. This paper has two main goals. The first one is to provide a tutorial review of the theoretical results that have been achieved in the context of nonstationary adaptive filtering and to highlight some open issues. The second goal is to provide new results concerning the tracking properties of the sign-sign algorithm, an adaptive filtering algorithm that has received a great deal of interest in the area of high speed data communications.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127939265","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551107
O. Abo-Elnor
This paper presents an application of the nonlinear multi-mode frequency-domain analysis for a gyrotron, which has been first introduced by Jensen and Shunemann (1991) and applied by Abo-Elnor (see Proceeding of the 2nd International Conference on Millimeter and Submillimeter Waves and Applications, vo1.2558, p.236-9, San Diego, CA, 1995), to a simple cavity gyrotron. Power reflections from the load affect the performance of the gyrotron. These power reflections will change the output power efficiency, and will result in frequency pulling. The gyrotron oscillator may come into instability. These types of applications are very hard-if possible at all-to study using the classical time domain analysis. The effects of power reflections on the output power, efficiency, and frequency pulling have been calculated for different levels of power reflections. The effect of changing the load reference position is also included.
本文介绍了非线性多模频域分析在回旋管上的应用，该分析首先由Jensen和Shunemann(1991)提出，并由Abo-Elnor(参见第二届毫米波和亚毫米波及其应用国际会议论文集，vol .2558, p.236-9, San Diego, CA, 1995)应用于一个简单腔回旋管。负载的功率反射影响回旋管的性能。这些功率反射将改变输出功率效率，并将导致频率拉。回旋管振荡器可能陷入不稳定状态。这些类型的应用很难(如果可能的话)使用经典的时域分析进行研究。计算了不同功率反射水平下功率反射对输出功率、效率和频率拉升的影响。改变荷载参考位置的影响也包括在内。
{"title":"Effect of load reflections on gyrotron using frequency-domain analysis","authors":"O. Abo-Elnor","doi":"10.1109/NRSC.1996.551107","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551107","url":null,"abstract":"This paper presents an application of the nonlinear multi-mode frequency-domain analysis for a gyrotron, which has been first introduced by Jensen and Shunemann (1991) and applied by Abo-Elnor (see Proceeding of the 2nd International Conference on Millimeter and Submillimeter Waves and Applications, vo1.2558, p.236-9, San Diego, CA, 1995), to a simple cavity gyrotron. Power reflections from the load affect the performance of the gyrotron. These power reflections will change the output power efficiency, and will result in frequency pulling. The gyrotron oscillator may come into instability. These types of applications are very hard-if possible at all-to study using the classical time domain analysis. The effects of power reflections on the output power, efficiency, and frequency pulling have been calculated for different levels of power reflections. The effect of changing the load reference position is also included.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131733185","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551141
A. M. Moselhy, M. Fouad
An analytical approach to design of microwave BJTs and FETs oscillator is presented. The technique presented here is based on the small signal S-parameters which either may be measured or obtained from data sheet. By means of this technique two kinds of oscillators, 6-GHz MESFET oscillator and 2-GHz BJT oscillator, have been designed. The designed circuits are simulated by using general purpose analysis program. A practical circuit has been built by using microwave integrated circuit technology. The results of simulation program and the experimental measurements showed that the design method introduced is optimum approach for microwave transistor oscillator design.
{"title":"Optimum microwave oscillator design using small-signal S-parameters","authors":"A. M. Moselhy, M. Fouad","doi":"10.1109/NRSC.1996.551141","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551141","url":null,"abstract":"An analytical approach to design of microwave BJTs and FETs oscillator is presented. The technique presented here is based on the small signal S-parameters which either may be measured or obtained from data sheet. By means of this technique two kinds of oscillators, 6-GHz MESFET oscillator and 2-GHz BJT oscillator, have been designed. The designed circuits are simulated by using general purpose analysis program. A practical circuit has been built by using microwave integrated circuit technology. The results of simulation program and the experimental measurements showed that the design method introduced is optimum approach for microwave transistor oscillator design.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125559164","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551424
I. El-Shahat, F. Soliman, A. Al-Kabbani, F. Farag
The design, construction, and analysis of a microwave active filters all-or band-pass were described using the NE71083 GaAs FETs and lumped circuit components. In addition to optimizing the passive element values, it was necessary to replace each FET with the composite transistor to achieve a better flat frequency response. Besides, cascade networks were introduced for the design and construction of second-degree all-or band-pass filters for the realization of higher order filters. A computer-simulated design has illustrated the feasibility of the cascade composite GaAs FETs synthesis approach. Finally, illustrative examples were given for both filters.
{"title":"Optimization of microwave active filters based on cascaded composite GaAs FETs","authors":"I. El-Shahat, F. Soliman, A. Al-Kabbani, F. Farag","doi":"10.1109/NRSC.1996.551424","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551424","url":null,"abstract":"The design, construction, and analysis of a microwave active filters all-or band-pass were described using the NE71083 GaAs FETs and lumped circuit components. In addition to optimizing the passive element values, it was necessary to replace each FET with the composite transistor to achieve a better flat frequency response. Besides, cascade networks were introduced for the design and construction of second-degree all-or band-pass filters for the realization of higher order filters. A computer-simulated design has illustrated the feasibility of the cascade composite GaAs FETs synthesis approach. Finally, illustrative examples were given for both filters.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122525719","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551150
M. Aziz, F. Salam, M. Talat, A. Helal, H. El-Khabeary T., N.T. El-Merai
Experimental results are given for the perveance at different pressures and RF power using nitrogen and argon ions. The results are taken using a constricted axial RF ion source with an aspect ratio of the radius of the outlet aperture to the extraction gap width equals 0.4. Our data confirm the validity of the current scaling law at RF power equals 50 watt 20 watt in case of nitrogen and argon gases respectively at a pressure of 3 /spl mu/Hg. It is found that by increasing the pressure the beam current will decrease. Therefore, in order to keep the beam current constant, the RF power must be increased. In case of nitrogen, at a perveance of 0.24/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 0.03/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 25 /spl mu/Hg, it reduces to 1.2/spl deg/. In case of argon, at a perveance of 0.12/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 3 /spl mu/Hg, the beam divergence is 7.2/spl deg/, while at a perveance of 0.02/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 25 /spl mu/Hg, it becomes 3.2.
{"title":"Technological and physical aspects of a constricted RF ion source","authors":"M. Aziz, F. Salam, M. Talat, A. Helal, H. El-Khabeary T., N.T. El-Merai","doi":"10.1109/NRSC.1996.551150","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551150","url":null,"abstract":"Experimental results are given for the perveance at different pressures and RF power using nitrogen and argon ions. The results are taken using a constricted axial RF ion source with an aspect ratio of the radius of the outlet aperture to the extraction gap width equals 0.4. Our data confirm the validity of the current scaling law at RF power equals 50 watt 20 watt in case of nitrogen and argon gases respectively at a pressure of 3 /spl mu/Hg. It is found that by increasing the pressure the beam current will decrease. Therefore, in order to keep the beam current constant, the RF power must be increased. In case of nitrogen, at a perveance of 0.24/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 0.03/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 25 /spl mu/Hg, it reduces to 1.2/spl deg/. In case of argon, at a perveance of 0.12/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 3 /spl mu/Hg, the beam divergence is 7.2/spl deg/, while at a perveance of 0.02/spl times/10/sup -8/ Amp/V/sup 3/2/ corresponding to a pressure of 25 /spl mu/Hg, it becomes 3.2.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123117273","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551146
M. M. Mokhtar, A. Ragab
An extensive analysis of using the decision feedback equalizer (DFE) that uses a recursive least squares (RLS) adaptation algorithm to equalize multipath fading radio channels in general and digital cellular radio (DCR) channels in particular is performed. Throughout this analysis, the effect of the fade rate, multipath spread, equalizer size, and tracking speed on convergence rate and steady state behavior of a DFE-RLS is examined. Also, for a given fade rate, a compromise between fast adaptation (necessary to track variations in the input statistic) and slow adaptation (necessary to contain noise in the adaptive process) is performed. In addition, for a proposed mobile communication system for North America, recommendations are also documented for some system parameters to ensure an acceptable performance.
{"title":"Performance analysis of adaptive DFE-RLS in mobile fading channels","authors":"M. M. Mokhtar, A. Ragab","doi":"10.1109/NRSC.1996.551146","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551146","url":null,"abstract":"An extensive analysis of using the decision feedback equalizer (DFE) that uses a recursive least squares (RLS) adaptation algorithm to equalize multipath fading radio channels in general and digital cellular radio (DCR) channels in particular is performed. Throughout this analysis, the effect of the fade rate, multipath spread, equalizer size, and tracking speed on convergence rate and steady state behavior of a DFE-RLS is examined. Also, for a given fade rate, a compromise between fast adaptation (necessary to track variations in the input statistic) and slow adaptation (necessary to contain noise in the adaptive process) is performed. In addition, for a proposed mobile communication system for North America, recommendations are also documented for some system parameters to ensure an acceptable performance.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123485952","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551103
F. Soliman, I.A. El-Shabat, A. Al-Kabbani, F. Farag
A methodology for computer-simulated design of active microwave filters, either all-or band-pass ones, was previously carried out by the authors. We consider the effects of radiation and temperature on the operation of such filters. In general, gamma-exposure of the GaAs MESFETs up to a total gamma-dose of 80.0 Mrads causes the gain of the filters to decrease. In the ideal cases of both filters the reduction is negligible, but in the optimal cases, the gain reduction is noticeable. Also, when the devices' temperature increases, from -50 up to 150 /spl deg/C, the gain is reduced in both cases; ideal and optimal.
{"title":"Radiation and temperature effects on the operation of microwave active filters","authors":"F. Soliman, I.A. El-Shabat, A. Al-Kabbani, F. Farag","doi":"10.1109/NRSC.1996.551103","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551103","url":null,"abstract":"A methodology for computer-simulated design of active microwave filters, either all-or band-pass ones, was previously carried out by the authors. We consider the effects of radiation and temperature on the operation of such filters. In general, gamma-exposure of the GaAs MESFETs up to a total gamma-dose of 80.0 Mrads causes the gain of the filters to decrease. In the ideal cases of both filters the reduction is negligible, but in the optimal cases, the gain reduction is noticeable. Also, when the devices' temperature increases, from -50 up to 150 /spl deg/C, the gain is reduced in both cases; ideal and optimal.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124677393","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551423
A. Allam, A. Ragab
The paper presents the convergence phenomenon of the moment method, Floquet modal analysis, and spectral domain analysis of free standing arrays of dipoles. The ill-posed situation of a system of equations, Johansson's (1985) condition and the measurements of the transmission response are used to describe that phenomenon.
{"title":"Convergence in the analysis of frequency selective arrays of linear dipoles","authors":"A. Allam, A. Ragab","doi":"10.1109/NRSC.1996.551423","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551423","url":null,"abstract":"The paper presents the convergence phenomenon of the moment method, Floquet modal analysis, and spectral domain analysis of free standing arrays of dipoles. The ill-posed situation of a system of equations, Johansson's (1985) condition and the measurements of the transmission response are used to describe that phenomenon.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123761871","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551149
S. Zakhary
The motion of charged particle in a crossed RF field and DC magnetic field describes the occurrence of resonance (increase of the energy gained by the particle between collisions) which causes low breakdown voltage, higher plasma intensity, and higher extracted ion current. The resonance in the microwave discharge is essential for plasma electron heating. The development line in both ECRISs and RFISs includes increase of electron population in the discharge to intensify the plasma and increase the extracted ion current plasma cooling with the use of electron injection or gas mixing increases the lifetime of the ions in the plasma allowing for multiple ionization collision and increase of the highly charged ion species. Adaptation of both electrical and geometrical properties of these sources can lead to lower beam emittance.
{"title":"Study of the electron resonance and the development line in both electron cyclotron resonance and radio frequency ion sources","authors":"S. Zakhary","doi":"10.1109/NRSC.1996.551149","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551149","url":null,"abstract":"The motion of charged particle in a crossed RF field and DC magnetic field describes the occurrence of resonance (increase of the energy gained by the particle between collisions) which causes low breakdown voltage, higher plasma intensity, and higher extracted ion current. The resonance in the microwave discharge is essential for plasma electron heating. The development line in both ECRISs and RFISs includes increase of electron population in the discharge to intensify the plasma and increase the extracted ion current plasma cooling with the use of electron injection or gas mixing increases the lifetime of the ions in the plasma allowing for multiple ionization collision and increase of the highly charged ion species. Adaptation of both electrical and geometrical properties of these sources can lead to lower beam emittance.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116211138","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 : 1996-03-19DOI: 10.1109/NRSC.1996.551127
T. Khattab, A.D. Rawlins
In space RF communications payloads, it is increasingly required that high-power multi-channel transmitters and broadband receivers have shared, or closely adjacent RF feeds. Because of the large power level difference between the transmit and receive signals and the limitation of frequency allocation, passive intermodulation (PIM) interference due to passive non-linearities in the high-power transmission path can be serious problem. One of the main sources of PIM in RF microwave systems is the metal-to-metal contact. A contact model regardless of the suspected non-linear mechanisms, i.e. semiconductor, electron tunnelling and microdischarge, has been used to explain the non-linear effect at metallic contacts. The model requires that the non-linear effect is current dependent and the PIM level is proportional to the current density at the contacts. Because metal-to-metal contact in an RF coaxial connector is unavoidable, an alternative has to be developed. The work reported represents some of our efforts toward developing a demountable RF coaxial connector which does not involve metal-to-metal contact in any electrically significant part, i.e. a "contactless connector". The novel design of the coaxial contactless connector and the theoretical analysis are described.
{"title":"Principles of low PIM hardware design","authors":"T. Khattab, A.D. Rawlins","doi":"10.1109/NRSC.1996.551127","DOIUrl":"https://doi.org/10.1109/NRSC.1996.551127","url":null,"abstract":"In space RF communications payloads, it is increasingly required that high-power multi-channel transmitters and broadband receivers have shared, or closely adjacent RF feeds. Because of the large power level difference between the transmit and receive signals and the limitation of frequency allocation, passive intermodulation (PIM) interference due to passive non-linearities in the high-power transmission path can be serious problem. One of the main sources of PIM in RF microwave systems is the metal-to-metal contact. A contact model regardless of the suspected non-linear mechanisms, i.e. semiconductor, electron tunnelling and microdischarge, has been used to explain the non-linear effect at metallic contacts. The model requires that the non-linear effect is current dependent and the PIM level is proportional to the current density at the contacts. Because metal-to-metal contact in an RF coaxial connector is unavoidable, an alternative has to be developed. The work reported represents some of our efforts toward developing a demountable RF coaxial connector which does not involve metal-to-metal contact in any electrically significant part, i.e. a \"contactless connector\". The novel design of the coaxial contactless connector and the theoretical analysis are described.","PeriodicalId":127585,"journal":{"name":"Thirteenth National Radio Science Conference. NRSC '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116854189","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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