Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893157
W. Lu, Q. Liu, Z. Wang, P. W. R. Smith
In this paper, breakdown voltages and acceleration voltages of an inhibited Gas-To-Liquid (GTL) based transformer oil were investigated under both positive and negative lightning impulse voltages. A conventional inhibited mineral oil was also tested as a benchmark. Both point-sphere and point-plane configurations were used. Rising voltage method was used to conduct the breakdown tests, and the breakdown voltage was obtained as the average of ten tests. Results show that both positive and negative impulse breakdown voltages of the GTL based oil are higher than those of the conventional mineral oil. This is thought to be due to the significantly lower aromatic content in the GTL based oil, since aromatic molecules tend to have low ionization potentials that promote the positive streamer propagation and electron scavenging properties that accelerate the negative streamer propagation. In addition, the paper also discusses streamer propagation velocity and acceleration voltages of the GTL based oil under both positive and negative polarities.
{"title":"Lightning impulse breakdown performance of an inhibited Gas-To-Liquid (GTL) hydrocarbon transformer oil","authors":"W. Lu, Q. Liu, Z. Wang, P. W. R. Smith","doi":"10.1109/ICDL.2014.6893157","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893157","url":null,"abstract":"In this paper, breakdown voltages and acceleration voltages of an inhibited Gas-To-Liquid (GTL) based transformer oil were investigated under both positive and negative lightning impulse voltages. A conventional inhibited mineral oil was also tested as a benchmark. Both point-sphere and point-plane configurations were used. Rising voltage method was used to conduct the breakdown tests, and the breakdown voltage was obtained as the average of ten tests. Results show that both positive and negative impulse breakdown voltages of the GTL based oil are higher than those of the conventional mineral oil. This is thought to be due to the significantly lower aromatic content in the GTL based oil, since aromatic molecules tend to have low ionization potentials that promote the positive streamer propagation and electron scavenging properties that accelerate the negative streamer propagation. In addition, the paper also discusses streamer propagation velocity and acceleration voltages of the GTL based oil under both positive and negative polarities.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"17 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88724123","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893086
K. Fukunaga, M. Mizuno, K. Sasaki, S. Watanabe
Dielectric property measurement of liquid in the frequency range above microwave region is required to investigate the interaction between electromagnetic waves and human body because most biological materials are liquids. Various measurement systems are compared by measuring water approximately from 1 GHz to 3 THz. All data are in good agreement.
{"title":"Dielectric measurement of liquids in terahertz frequency band","authors":"K. Fukunaga, M. Mizuno, K. Sasaki, S. Watanabe","doi":"10.1109/ICDL.2014.6893086","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893086","url":null,"abstract":"Dielectric property measurement of liquid in the frequency range above microwave region is required to investigate the interaction between electromagnetic waves and human body because most biological materials are liquids. Various measurement systems are compared by measuring water approximately from 1 GHz to 3 THz. All data are in good agreement.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"30 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88931252","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893153
P. Vázquez, Jian Wu, P. Traoré, A. Pérez
In this work, we present the results of numerical simulations of the EHD convection between parallel plates in a rectangular domain with no-slip boundary conditions at all the walls. The electroconvection between parallel plates in an infinite domain is a classic EHD problem. Experimental, theoretical and numeric studies show that when a high enough voltage is applied across the plates, the liquid is set into motion. The nature of the bifurcation is subcritical. A roll pattern is established where the maximum velocity of the liquid is higher than the drift velocity of the ions. As a consequence, regions voided of electric charge appears in the bulk. However, when the domain is enclosed by rigid walls, the nature of the bifurcation changes, becoming supercritical. Stable velocity rolls with a maximum velocity smaller than the drift velocity of the ions are possible. We present a numeric analysis of these new phenomena. The physical mechanism which leads to this situation is analyzed and discussed. The evolution of the bifurcation diagrams with the aspect ratio of the cavity is also provided and analyzed.
{"title":"EHD convection in an enclosed rectangular domain","authors":"P. Vázquez, Jian Wu, P. Traoré, A. Pérez","doi":"10.1109/ICDL.2014.6893153","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893153","url":null,"abstract":"In this work, we present the results of numerical simulations of the EHD convection between parallel plates in a rectangular domain with no-slip boundary conditions at all the walls. The electroconvection between parallel plates in an infinite domain is a classic EHD problem. Experimental, theoretical and numeric studies show that when a high enough voltage is applied across the plates, the liquid is set into motion. The nature of the bifurcation is subcritical. A roll pattern is established where the maximum velocity of the liquid is higher than the drift velocity of the ions. As a consequence, regions voided of electric charge appears in the bulk. However, when the domain is enclosed by rigid walls, the nature of the bifurcation changes, becoming supercritical. Stable velocity rolls with a maximum velocity smaller than the drift velocity of the ions are possible. We present a numeric analysis of these new phenomena. The physical mechanism which leads to this situation is analyzed and discussed. The evolution of the bifurcation diagrams with the aspect ratio of the cavity is also provided and analyzed.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"15 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81670636","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893078
P. Leblanc, T. Paillat, C. Perrier, G. Morin
Mineral oils are commonly used for cooling and electrical insulation purposes in electrical power transformers and other electrical apparatus. Flow electrification of insulating liquids in different ducts has been studied for a long time. The physicochemical process appearing at the solid/liquid interface creates the electrical double layer. To study this phenomenon, a facility was designed a few years ago. It consists of a closed circulation loop where oil flows through a rectangular channel and allows measuring a streaming current and the accumulated charge on the pressboard during the flow. The present work focuses on the influence of external DC electric field.
{"title":"Impact of an DC electric field on the charge accumulation at the pressboard/oil interface","authors":"P. Leblanc, T. Paillat, C. Perrier, G. Morin","doi":"10.1109/ICDL.2014.6893078","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893078","url":null,"abstract":"Mineral oils are commonly used for cooling and electrical insulation purposes in electrical power transformers and other electrical apparatus. Flow electrification of insulating liquids in different ducts has been studied for a long time. The physicochemical process appearing at the solid/liquid interface creates the electrical double layer. To study this phenomenon, a facility was designed a few years ago. It consists of a closed circulation loop where oil flows through a rectangular channel and allows measuring a streaming current and the accumulated charge on the pressboard during the flow. The present work focuses on the influence of external DC electric field.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"94 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84326570","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893175
Miha Bečan, I. Kobal, Jalen Stremfelj, M. Babuder, Boris Zupanc
The paper describes an analytical approach adopted to improve the insulation condition evaluation procedure. Electrical testing of power transformer insulation may provide reliable information about its state and aging grade. Inconveniently, the majority of dielectric parameters used in this evaluation are temperature dependent; hence, the accurate measurement of the temperature is decisive for the final assessment result. The on-site tested transformers are usually put off operation and disconnected few hours before the tests initiate and are still slowly cooling down during testing. Non stable average insulation temperature may lead to a considerable systematic measuring error. Aiming to avoid this, an authentic several years collected database was taken and a suitable emendation method applied.
{"title":"The identification of systematic error in determining the average temperature of power transformer insulation obtained by comprehensive analysis of an authentic on-site condition assessment database","authors":"Miha Bečan, I. Kobal, Jalen Stremfelj, M. Babuder, Boris Zupanc","doi":"10.1109/ICDL.2014.6893175","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893175","url":null,"abstract":"The paper describes an analytical approach adopted to improve the insulation condition evaluation procedure. Electrical testing of power transformer insulation may provide reliable information about its state and aging grade. Inconveniently, the majority of dielectric parameters used in this evaluation are temperature dependent; hence, the accurate measurement of the temperature is decisive for the final assessment result. The on-site tested transformers are usually put off operation and disconnected few hours before the tests initiate and are still slowly cooling down during testing. Non stable average insulation temperature may lead to a considerable systematic measuring error. Aiming to avoid this, an authentic several years collected database was taken and a suitable emendation method applied.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"100 2 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88091428","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893167
Jian Wu, P. Traoré, P. Vázquez, A. Pérez
We performed a numerical study of two-dimensional electroconvection in a dielectric liquid contained between two concentric circular cylinders with the radius ratio of 0.5. The convection is induced by unipolar injection from the inner or outer cylinder. Both the weak and strong injection regimes were considered. We determined the linear stability criterion from direct numerical results and compared them with the values predicted by the stability analysis. Perfect agreements were found for all the cases we considered. At the threshold of motion, we observed a steady and a chaotic flow pattern for strong and weak injection, respectively. These results share strong analogy with the previous findings with the planar configuration.
{"title":"Numerical simulation of annular electroconvection in a dielectric liquid induced by unipolar injection","authors":"Jian Wu, P. Traoré, P. Vázquez, A. Pérez","doi":"10.1109/ICDL.2014.6893167","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893167","url":null,"abstract":"We performed a numerical study of two-dimensional electroconvection in a dielectric liquid contained between two concentric circular cylinders with the radius ratio of 0.5. The convection is induced by unipolar injection from the inner or outer cylinder. Both the weak and strong injection regimes were considered. We determined the linear stability criterion from direct numerical results and compared them with the values predicted by the stability analysis. Perfect agreements were found for all the cases we considered. At the threshold of motion, we observed a steady and a chaotic flow pattern for strong and weak injection, respectively. These results share strong analogy with the previous findings with the planar configuration.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"15 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85329766","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893142
N. Davari, P. Åstrand, M. Unge
The field-dependent ionization potential is determined by calculating the dissociation energy barrier for the interaction between a cation and an electron in an electric field. A quantum-chemical method based on constrained density-functional theory (CDFT) has been established for this purpose. Here we present the field-dependent ionization potential and excitation energies for polyaromatic molecules relevant for electrically insulating liquids. In the CDFT model, we rely on that the dissociation barrier is located somewhere outside the cation. This causes problems for all molecules at sufficiently high electric fields, but for polyaromatic molecules the problems appear at lower fields as compared to previously studied molecules. This limitation has been investigated in detail and some initial results are presented for a set of polyaromatic molecules including benzene and pyrene. The importance of ionization potential and excitation energies in streamer initiation and propagation are discussed.
{"title":"Field-dependent ionization potential for polyaromatic molecules from constrained density-functional theory","authors":"N. Davari, P. Åstrand, M. Unge","doi":"10.1109/ICDL.2014.6893142","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893142","url":null,"abstract":"The field-dependent ionization potential is determined by calculating the dissociation energy barrier for the interaction between a cation and an electron in an electric field. A quantum-chemical method based on constrained density-functional theory (CDFT) has been established for this purpose. Here we present the field-dependent ionization potential and excitation energies for polyaromatic molecules relevant for electrically insulating liquids. In the CDFT model, we rely on that the dissociation barrier is located somewhere outside the cation. This causes problems for all molecules at sufficiently high electric fields, but for polyaromatic molecules the problems appear at lower fields as compared to previously studied molecules. This limitation has been investigated in detail and some initial results are presented for a set of polyaromatic molecules including benzene and pyrene. The importance of ionization potential and excitation energies in streamer initiation and propagation are discussed.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"53 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81026371","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893077
Ivanka Atanasova-Höhlein
The phenomenon of fault gas generation out of insulating fluids at moderate temperatures, based solely on their constituent and not related to an equipment failure is described with the term “straygassing”. Straygassing is not a new phenomenon, but it seems to be stronger manifisted with modern mineral oils. Especially the use of some additives, mainly passivators may accelerate strongly the straygassing production. This paper is an overview on: the possible mechanism of straygassing; the typical stray gas formation of mineral oil, as well as of further insulating liquids like synthetic or natural esters under various temperature conditions; examples of possible interference of the straygassing pattern with diagnostics; how to distinguish straygassing from fault cases in the DGA evaluation.
{"title":"Straygassing of insulating liquids - Manifestation and influence on diagnostics","authors":"Ivanka Atanasova-Höhlein","doi":"10.1109/ICDL.2014.6893077","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893077","url":null,"abstract":"The phenomenon of fault gas generation out of insulating fluids at moderate temperatures, based solely on their constituent and not related to an equipment failure is described with the term “straygassing”. Straygassing is not a new phenomenon, but it seems to be stronger manifisted with modern mineral oils. Especially the use of some additives, mainly passivators may accelerate strongly the straygassing production. This paper is an overview on: the possible mechanism of straygassing; the typical stray gas formation of mineral oil, as well as of further insulating liquids like synthetic or natural esters under various temperature conditions; examples of possible interference of the straygassing pattern with diagnostics; how to distinguish straygassing from fault cases in the DGA evaluation.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"81 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90692679","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893082
N. Lavesson, L. Walfridsson, O. Hjortstam, J. Schiessling
This article studies the apparent resistivity of mineral oil as a function of electric DC stress using theoretical and experimental methods for three different oils. The experimental measurement of the apparent resistivity is done using a cell with two bare Rogowski like electrodes separated by a 2mm gap. The dc current is measured after one hour and the stress is varied in steps. For low DC stress the apparent resistivity rises with increasing voltage, leveling off and dropping slightly for higher voltages. The resistivity is modeled using the ion drift model with equilibrium resistivity measured using dielectric response as input. The charge dynamics and the corresponding resistivity is simulated and the results compared with the measured values. The main features seen in the measurements are captured in the simulation and there is a good overall agreement between the theoretical data and the experimental values.
{"title":"Modelling and measurement of field dependent resistivity of transformer oil","authors":"N. Lavesson, L. Walfridsson, O. Hjortstam, J. Schiessling","doi":"10.1109/ICDL.2014.6893082","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893082","url":null,"abstract":"This article studies the apparent resistivity of mineral oil as a function of electric DC stress using theoretical and experimental methods for three different oils. The experimental measurement of the apparent resistivity is done using a cell with two bare Rogowski like electrodes separated by a 2mm gap. The dc current is measured after one hour and the stress is varied in steps. For low DC stress the apparent resistivity rises with increasing voltage, leveling off and dropping slightly for higher voltages. The resistivity is modeled using the ion drift model with equilibrium resistivity measured using dielectric response as input. The charge dynamics and the corresponding resistivity is simulated and the results compared with the measured values. The main features seen in the measurements are captured in the simulation and there is a good overall agreement between the theoretical data and the experimental values.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"26 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81868962","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 : 2014-09-08DOI: 10.1109/ICDL.2014.6893176
T. Gradnik, B. Čuček, M. Koncan-Gradnik
Paper analyses temperature and physical-chemical factors that influence determination of water content in transformer insulating liquids by capacitive moisture sensors. Water solubility coefficients are used to calculate the water content from moisture sensor's relative saturation and temperature measurements. Absolute water content and water solubility coefficients of various types and ageing degree of mineral, ester and silicon based transformer insulating liquids were determined in controlled laboratory conditions. Results of capacitive moisture sensor measurement, the method under study, and the Karl Fisher coulometric direct titration method as the reference method, are analysed and discussed in the paper. The experimental results confirm that water solubility coefficients of the studied liquids can be basically correlated to the liquids' chemical structure. The impact of the liquid temperature and oil circulation speed on the error of the capacitive moisture sensor measurement is analysed and quantified. The paper discusses the influence of laboratory experimental conditions on determination of water solubility coefficients as well as potential error sources of water content measurements by capacitive moisture sensors in transformers in operation.
{"title":"Temperature and chemical impact on determination of water content in dielectric liquids by capacitive moisture sensors","authors":"T. Gradnik, B. Čuček, M. Koncan-Gradnik","doi":"10.1109/ICDL.2014.6893176","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893176","url":null,"abstract":"Paper analyses temperature and physical-chemical factors that influence determination of water content in transformer insulating liquids by capacitive moisture sensors. Water solubility coefficients are used to calculate the water content from moisture sensor's relative saturation and temperature measurements. Absolute water content and water solubility coefficients of various types and ageing degree of mineral, ester and silicon based transformer insulating liquids were determined in controlled laboratory conditions. Results of capacitive moisture sensor measurement, the method under study, and the Karl Fisher coulometric direct titration method as the reference method, are analysed and discussed in the paper. The experimental results confirm that water solubility coefficients of the studied liquids can be basically correlated to the liquids' chemical structure. The impact of the liquid temperature and oil circulation speed on the error of the capacitive moisture sensor measurement is analysed and quantified. The paper discusses the influence of laboratory experimental conditions on determination of water solubility coefficients as well as potential error sources of water content measurements by capacitive moisture sensors in transformers in operation.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"35 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75921829","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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