The exploitation of limestone and gypsum quarries is often complicated by the presence of waste-filled karstic zones. The capabilities of GPR to quickly delineate the economic material are studied. Surface radar data collected in a gypsum quarry are presented. These data provide limited information due to poor radar penetration and the presence of abundant diffraction patterns of ambiguous origin. Borehole GPR surveys are considered to delineate the karstic zone. Surface and borehole radar data are first synthesized numerically to seek optimal acquisition parameters. We use Carcione and Schoenberg (2000) modeling code, in which the 3D staggered grid pseudospectral operator is implemented. Modeling results show that minimally processed borehole and borehole-surfaced ata provide valuablea nd otherwise inaccessible information. The numerical simulations have also revealed limitations of the modeling code which requires further improvement.
{"title":"3D radar response of a karstic zone","authors":"B. Giroux, M. Chouteau","doi":"10.1117/12.462279","DOIUrl":"https://doi.org/10.1117/12.462279","url":null,"abstract":"The exploitation of limestone and gypsum quarries is often complicated by the presence of waste-filled karstic zones. The capabilities of GPR to quickly delineate the economic material are studied. Surface radar data collected in a gypsum quarry are presented. These data provide limited information due to poor radar penetration and the presence of abundant diffraction patterns of ambiguous origin. Borehole GPR surveys are considered to delineate the karstic zone. Surface and borehole radar data are first synthesized numerically to seek optimal acquisition parameters. We use Carcione and Schoenberg (2000) modeling code, in which the 3D staggered grid pseudospectral operator is implemented. Modeling results show that minimally processed borehole and borehole-surfaced ata provide valuablea nd otherwise inaccessible information. The numerical simulations have also revealed limitations of the modeling code which requires further improvement.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121446910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A study using GPR has been carried out at Itaipuacu beach,Marica, Rio de Janeiro with the aim of reconstructing and analysing the environment of depositing sediments. Fifty profiles were made using a 200 MHz bistatics antennas (nominal frequency). These profiles generated a 3D cube. In the same way, we obtained an estimation of propagation velocity of the signal in the subsoil (by CMP technique) using two 80 Mhz antennas. The analysis of the radargrams allows to recognize the stratigraphic sequence and its progradation. Through core drill sampling in the investigation site, it has been possible to establish a correlation between some reflections and the presence of organic matter, and to make evident that the salt content of water below the water table increases with depth. With these profiles we can see the progradations, and under the water table, a reflector which seems to be caused by the combination of organic matter, together with a sharp increase in the salt content of the water. This interpretation agrees with the model "Ghyben-Herzberg fresh-water lens" Hagrey & Muller,( 2000), as well as other results obtained by these authors.
{"title":"GPR radar imaging of water table, salty water, and sand stratigraphy in a coastal zone in Rio de Janeiro","authors":"T. Teixeira, H. Lorenzo, A. da Costa, P. Arias","doi":"10.1117/12.462305","DOIUrl":"https://doi.org/10.1117/12.462305","url":null,"abstract":"A study using GPR has been carried out at Itaipuacu beach,Marica, Rio de Janeiro with the aim of reconstructing and analysing the environment of depositing sediments. Fifty profiles were made using a 200 MHz bistatics antennas (nominal frequency). These profiles generated a 3D cube. In the same way, we obtained an estimation of propagation velocity of the signal in the subsoil (by CMP technique) using two 80 Mhz antennas. The analysis of the radargrams allows to recognize the stratigraphic sequence and its progradation. Through core drill sampling in the investigation site, it has been possible to establish a correlation between some reflections and the presence of organic matter, and to make evident that the salt content of water below the water table increases with depth. With these profiles we can see the progradations, and under the water table, a reflector which seems to be caused by the combination of organic matter, together with a sharp increase in the salt content of the water. This interpretation agrees with the model \"Ghyben-Herzberg fresh-water lens\" Hagrey & Muller,( 2000), as well as other results obtained by these authors.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"4758 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129349374","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}
Accurate and consistent manual interpretation of the vast quantities of GPR data collected during a typical survey constitute an implementation bottleneck that often limits the practicality and cost-effectiveness of this tool for rapid site investigation. Automatic unsupervised interpretation of GPR data is achieved by training a neural network to discriminate between signals originating from different types of targets and other spurious sources of reflections such as clutter. This is achieved by computing a number of statistical data descriptors for feature extraction. The neural classifier is capable of returning 3-dimensional image outlining regions of extended targets (such as reinforced concrete, disturbed soil or storage tanks) and pinpointing the location of localised targets such as mines and pipes. These reports are accompanied by a written log detailing the depths and geometry of these targets. This classifier was applied to a variety of GPR data sets gathered from a number of sites. The obtained results were in close agreement with those obtained by a trained operator manually, but in a fraction of the time. Different targets have been successfully discriminated, with a consistency greater than that of the operator. Although the system is implemented in software, the rate at which classifications are rendered lends the system Authors would like to thank the Engineering and Physical Sciences Research Council (EPSRC) for funding this work as a part of a larger project regarding automatic data-processing of ground penetrating radar. Authors would like also to express their gratitude to Zetica (UK) Ltd. for supporting this work financially, and providing sites data and related software. favourably to near real-time on-site processing and interpretation.
{"title":"Neural network target identifier based on statistical features of GPR signals","authors":"S. Shihab, W. Al-Nuaimy, Yi Huang, A. Eriksen","doi":"10.1117/12.462228","DOIUrl":"https://doi.org/10.1117/12.462228","url":null,"abstract":"Accurate and consistent manual interpretation of the vast quantities of GPR data collected during a typical survey constitute an implementation bottleneck that often limits the practicality and cost-effectiveness of this tool for rapid site investigation. Automatic unsupervised interpretation of GPR data is achieved by training a neural network to discriminate between signals originating from different types of targets and other spurious sources of reflections such as clutter. This is achieved by computing a number of statistical data descriptors for feature extraction. The neural classifier is capable of returning 3-dimensional image outlining regions of extended targets (such as reinforced concrete, disturbed soil or storage tanks) and pinpointing the location of localised targets such as mines and pipes. These reports are accompanied by a written log detailing the depths and geometry of these targets. This classifier was applied to a variety of GPR data sets gathered from a number of sites. The obtained results were in close agreement with those obtained by a trained operator manually, but in a fraction of the time. Different targets have been successfully discriminated, with a consistency greater than that of the operator. Although the system is implemented in software, the rate at which classifications are rendered lends the system Authors would like to thank the Engineering and Physical Sciences Research Council (EPSRC) for funding this work as a part of a larger project regarding automatic data-processing of ground penetrating radar. Authors would like also to express their gratitude to Zetica (UK) Ltd. for supporting this work financially, and providing sites data and related software. favourably to near real-time on-site processing and interpretation.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114287418","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}
The volume of image data generated in ground-penetrating radar surveys can severely restrict the practicality of this site investigation technique. This is particularly true in situations where automatic analysis or interpretation is required, as segmentation and classification tasks that utilise multivariate data are critically affected by the volume and dimensionality of the data. A general-purpose unsupervised image segmentation system is presented here for the automatic detection of image regions exhibiting different visual texture properties. A suboptimal feature selection procedure is proposed to automatically select the set of texture features best suited for the particular application. The reduction in the size of the feature set both reduces the computation time and improves the accuracy of the final classification.
{"title":"Unsupervised segmentaiton of subsurface radar images","authors":"W. Al-Nuaimy, Yi Huang, S. Shihab, A. Eriksen","doi":"10.1117/12.462233","DOIUrl":"https://doi.org/10.1117/12.462233","url":null,"abstract":"The volume of image data generated in ground-penetrating radar surveys can severely restrict the practicality of this site investigation technique. This is particularly true in situations where automatic analysis or interpretation is required, as segmentation and classification tasks that utilise multivariate data are critically affected by the volume and dimensionality of the data. A general-purpose unsupervised image segmentation system is presented here for the automatic detection of image regions exhibiting different visual texture properties. A suboptimal feature selection procedure is proposed to automatically select the set of texture features best suited for the particular application. The reduction in the size of the feature set both reduces the computation time and improves the accuracy of the final classification.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"238 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115760275","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}
Turbidite outcrops of the on shore portion of Almada Basin are made of conglomeratic sandstones and shales of the Urucutuca Formation. Those rocks are the unique Turbidite examples of the marine transgression mega-sequence in the Brazilian passive margin, which were sedimented during late Cretaceous. They are analogues to important Campos Basin reservoirs, offshore of Rio de Janeiro State, which is the largest Brazilian oil producer basin. A combined GPR, resistivity and well log survey was planned in the region to provide information regarding rock properties, such as lithology, geometry and permeability. The survey's goal was to predict the variability on the characteristics normally encountered in this kind of deposits. The GPR survey was done in order to provide a stratigraphic interpretation.
{"title":"GPR imaging of a turbidite outcrop in Almada Basin (Brazil)","authors":"J. M. Travassos, M. Ceia, A. Carrasquilla","doi":"10.1117/12.462246","DOIUrl":"https://doi.org/10.1117/12.462246","url":null,"abstract":"Turbidite outcrops of the on shore portion of Almada Basin are made of conglomeratic sandstones and shales of the Urucutuca Formation. Those rocks are the unique Turbidite examples of the marine transgression mega-sequence in the Brazilian passive margin, which were sedimented during late Cretaceous. They are analogues to important Campos Basin reservoirs, offshore of Rio de Janeiro State, which is the largest Brazilian oil producer basin. A combined GPR, resistivity and well log survey was planned in the region to provide information regarding rock properties, such as lithology, geometry and permeability. The survey's goal was to predict the variability on the characteristics normally encountered in this kind of deposits. The GPR survey was done in order to provide a stratigraphic interpretation.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"155 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116052758","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}
The soil water content distribution at two field sites was measured with the air launched surface reflectivity method using a standard GPR system elevated ~1 m above the surface. Time domain reflectometry (TDR) measurements of water content were also acquired at these sites. At one site, water was applied to the surface in two separate experiments and the water content was measured during drainage. At the other site, a water content profile was acquired across two terrain types, a flat grass field and a corn field. Although the GPR surface reflectivity method was able to map the water content distribution at both sites there were substantial differences between these measurements and those acquired with TDR. The main contributors to these differences are likely scattering and changes in the nature of the gradational air/ground interface, related to spatial variability in water content.
{"title":"Field studies of GPR air launched surface reflectivity measurements of soil water content","authors":"J. Redman, J. L. Davis, L. Galagedara, G. Parkin","doi":"10.1117/12.462256","DOIUrl":"https://doi.org/10.1117/12.462256","url":null,"abstract":"The soil water content distribution at two field sites was measured with the air launched surface reflectivity method using a standard GPR system elevated ~1 m above the surface. Time domain reflectometry (TDR) measurements of water content were also acquired at these sites. At one site, water was applied to the surface in two separate experiments and the water content was measured during drainage. At the other site, a water content profile was acquired across two terrain types, a flat grass field and a corn field. Although the GPR surface reflectivity method was able to map the water content distribution at both sites there were substantial differences between these measurements and those acquired with TDR. The main contributors to these differences are likely scattering and changes in the nature of the gradational air/ground interface, related to spatial variability in water content.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127390223","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}
The development of transient antennas for Ground Penetrating Radar would be difficult without numerical simulations of their performance. To this end FDTD code should be considered as a useful and powerful tool for transient antenna analysis. As an example of such analysis we describe simulations of the dielectric wedge antenna. Detailed investigations on such key model elements as the staircase approximation of 3D structures, the antenna feed model, the cell size and the size of the domain of computation were carried out. Very good agreement between theoretical predictions and experimental results was observed. Some of antenna characteristics (like the radial component of the electric field in the near zone, the radiated waveform and the antenna footprint in different grounds) cannot be measured easily, so the correct theoretical (numerical) model is essential for their determination. The numerical model of the antenna can be also used for optimization of the antenna.
{"title":"GPR antenna simulations in time domain","authors":"A. Yarovoy, G. Mur, L. Ligthart","doi":"10.1117/12.462189","DOIUrl":"https://doi.org/10.1117/12.462189","url":null,"abstract":"The development of transient antennas for Ground Penetrating Radar would be difficult without numerical simulations of their performance. To this end FDTD code should be considered as a useful and powerful tool for transient antenna analysis. As an example of such analysis we describe simulations of the dielectric wedge antenna. Detailed investigations on such key model elements as the staircase approximation of 3D structures, the antenna feed model, the cell size and the size of the domain of computation were carried out. Very good agreement between theoretical predictions and experimental results was observed. Some of antenna characteristics (like the radial component of the electric field in the near zone, the radiated waveform and the antenna footprint in different grounds) cannot be measured easily, so the correct theoretical (numerical) model is essential for their determination. The numerical model of the antenna can be also used for optimization of the antenna.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125381616","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}
We developed an interferometric borehole radar system, which has one transmitter and two receivers. A new analog optical link is equipped in this new borehole radar system. Field experiments were carried out and the system was evaluated. Clear reflections from subsurface fractures were observed. Two radar profiles can be obtained by one measurement. These two radar profiles are acquired by two receivers spacing 1 m apart, therefore these profiles can be used for interferometry. The difference in these profiles is caused only from the different of the wave paths from the radar target. By interferometric interpretation, much detailed information can be obtained from borehole radar compared to the conventional technique. For example, the direct coupling component of the received signal can be used for electromagnetic well logging.
{"title":"Interferometric borehole radar system","authors":"Kazunori Takahashi, Sixin Liu, Motoyuki Sato","doi":"10.1117/12.462206","DOIUrl":"https://doi.org/10.1117/12.462206","url":null,"abstract":"We developed an interferometric borehole radar system, which has one transmitter and two receivers. A new analog optical link is equipped in this new borehole radar system. Field experiments were carried out and the system was evaluated. Clear reflections from subsurface fractures were observed. Two radar profiles can be obtained by one measurement. These two radar profiles are acquired by two receivers spacing 1 m apart, therefore these profiles can be used for interferometry. The difference in these profiles is caused only from the different of the wave paths from the radar target. By interferometric interpretation, much detailed information can be obtained from borehole radar compared to the conventional technique. For example, the direct coupling component of the received signal can be used for electromagnetic well logging.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121023441","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}
The application of impulse radar for structural investigation of concrete elements has been increased during the last years related to technical developments, i. e. of high frequency antennas. In this paper, case studies will be presented related to the location of reinforcing bars, tendon ducts and repaired concrete areas in concrete bridges, anchors and dowels in concrete highways and delaminations of layered structures as they are used for non-ballasted railway tracks. It is shown that impulse radar can be applied in case of regular inspection and for searching the cause of damages but also for quality assessment in civil engineering.
{"title":"Application of impulse radar for nondestructive investigation of concrete structures","authors":"C. Maierhofer, T. Kind","doi":"10.1117/12.462218","DOIUrl":"https://doi.org/10.1117/12.462218","url":null,"abstract":"The application of impulse radar for structural investigation of concrete elements has been increased during the last years related to technical developments, i. e. of high frequency antennas. In this paper, case studies will be presented related to the location of reinforcing bars, tendon ducts and repaired concrete areas in concrete bridges, anchors and dowels in concrete highways and delaminations of layered structures as they are used for non-ballasted railway tracks. It is shown that impulse radar can be applied in case of regular inspection and for searching the cause of damages but also for quality assessment in civil engineering.","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"30 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125817069","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}
ABSTRACT Improvement of resolution is the challenging issue in Ground Penetrating Radar (GPR) and that is greatly desired to increase in order to get the clear imaging of very closely buried targets. GPR has been approved as very successful technology for various kinds of investigations & detection of buried targets. In this paper, the application possibility of super resolution technique MUSIC (Multiple Signal Classification) algorithm is examined because of its superior results. Moreover, the conventional FFT (Fast Fourier Transform) has been utilized to get higher precision receiving signal level. Combined Processing Method (CPM) oftime domain response of MUSIC and IFFT (Inverse FFT) has been proposed for the first time to get high resolution and high precision receiving signal level. Simulation and experiment result show that the proposed method has high resolution and high precision receiving signal level than other conventional signal processing approach. Key words: Subsurface radar, FFT, MUSIC Algorithm, Super Resolution
提高分辨率是探地雷达(GPR)研究中的一个难题，为了获得深埋目标的清晰成像，迫切需要提高分辨率。探地雷达已被认为是一种非常成功的技术，用于各种隐蔽目标的调查和探测。鉴于MUSIC (Multiple Signal Classification，多信号分类)算法的优越性，本文对其应用的可能性进行了探讨。此外，利用传统的快速傅立叶变换(FFT)获得更高精度的接收信号电平。首次提出了MUSIC和逆FFT (Inverse FFT)时域响应的组合处理方法(CPM)，以获得高分辨率、高精度的接收信号电平。仿真和实验结果表明，与其他传统的信号处理方法相比，该方法具有高分辨率和高精度的接收信号电平。关键词:地下雷达，FFT, MUSIC算法，超分辨率
{"title":"Application possibilities of super-resolution technique for GPR imaging","authors":"S. Shrestha, I. Arai, T. Miwa","doi":"10.1117/12.462234","DOIUrl":"https://doi.org/10.1117/12.462234","url":null,"abstract":"ABSTRACT Improvement of resolution is the challenging issue in Ground Penetrating Radar (GPR) and that is greatly desired to increase in order to get the clear imaging of very closely buried targets. GPR has been approved as very successful technology for various kinds of investigations & detection of buried targets. In this paper, the application possibility of super resolution technique MUSIC (Multiple Signal Classification) algorithm is examined because of its superior results. Moreover, the conventional FFT (Fast Fourier Transform) has been utilized to get higher precision receiving signal level. Combined Processing Method (CPM) oftime domain response of MUSIC and IFFT (Inverse FFT) has been proposed for the first time to get high resolution and high precision receiving signal level. Simulation and experiment result show that the proposed method has high resolution and high precision receiving signal level than other conventional signal processing approach. Key words: Subsurface radar, FFT, MUSIC Algorithm, Super Resolution","PeriodicalId":256772,"journal":{"name":"International Conference on Ground Penetrating Radar","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125866242","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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