Pub Date : 2016-10-01DOI: 10.1109/WPNC.2016.7822847
J. Papadoudis, A. Georgiadis
This work describes a method to extend classical maps in terms of additional information and a prediction about objects within the environment. The prediction system is based on the behaviour of the observed objects and influences accordingly the updating of the map. First all objects are classified due to their size and further parameters characterizing the ability to move. Furthermore the velocity and orientation of objects within the visible area of the autonomous system are extracted from a vision sensor. In case of a mobile autonomous system they help to adjust its path in real time. Additionally all objects are tracked. In order to generate the statistical map a statistical indicator is introduced describing the possible future positions of objects. Thus the conventional maps can be improved by adding information about the status of the considered space. Furthermore the status of objects can be predicted even when they are not visible anymore. In the case of a mobile system, it will improve the awareness drastically enabling it to act pre-emptively and improve the human-machine interaction in e.g. a production environment.
{"title":"Dynamic environment modelling and prediction for autonomous systems","authors":"J. Papadoudis, A. Georgiadis","doi":"10.1109/WPNC.2016.7822847","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822847","url":null,"abstract":"This work describes a method to extend classical maps in terms of additional information and a prediction about objects within the environment. The prediction system is based on the behaviour of the observed objects and influences accordingly the updating of the map. First all objects are classified due to their size and further parameters characterizing the ability to move. Furthermore the velocity and orientation of objects within the visible area of the autonomous system are extracted from a vision sensor. In case of a mobile autonomous system they help to adjust its path in real time. Additionally all objects are tracked. In order to generate the statistical map a statistical indicator is introduced describing the possible future positions of objects. Thus the conventional maps can be improved by adding information about the status of the considered space. Furthermore the status of objects can be predicted even when they are not visible anymore. In the case of a mobile system, it will improve the awareness drastically enabling it to act pre-emptively and improve the human-machine interaction in e.g. a production environment.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"310 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124416052","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822841
L. Altay, Salim Eryigit, Fatih Alagöz
Position & time awareness is one of the fundamental components of ubiquitous computing. Sophisticated mobile applications utilize location and time information to confirm, set aside and grant activities. GPS is one of the global position and time information service provider and increases the quality of the context of the ubiquitous computing with enhanced serviceability. GPS encompasses space, ground and user segments. Since the data confidentiality is not a primary concern of GPS, spoofing of navigational data is a straightforward attack type of the malicious users to falsify user segment. There are several studies for counter-spoofing for GPS data falsification threat, but they require additional hardware in receiver side or modification of the ground or space segments. In this paper, we propose a simple method to amend the current GPS structure without additional hardware to mitigate spoofing.
{"title":"GPS-SEC","authors":"L. Altay, Salim Eryigit, Fatih Alagöz","doi":"10.1109/WPNC.2016.7822841","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822841","url":null,"abstract":"Position & time awareness is one of the fundamental components of ubiquitous computing. Sophisticated mobile applications utilize location and time information to confirm, set aside and grant activities. GPS is one of the global position and time information service provider and increases the quality of the context of the ubiquitous computing with enhanced serviceability. GPS encompasses space, ground and user segments. Since the data confidentiality is not a primary concern of GPS, spoofing of navigational data is a straightforward attack type of the malicious users to falsify user segment. There are several studies for counter-spoofing for GPS data falsification threat, but they require additional hardware in receiver side or modification of the ground or space segments. In this paper, we propose a simple method to amend the current GPS structure without additional hardware to mitigate spoofing.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125966901","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822844
D. Neirynck, Eric Luk, Michael McLaughlin
Symmetric double-sided two-way ranging is a well-known technique to deal with clock drift in time-of-flight measurements between unsynchronised devices. However, the requirement for symmetric reply delays is often not feasible. This paper presents an alternative way to process double-sided two-way ranging measurements that eliminates the need for this impractical constraint. The error of the proposed method is of the same order of magnitude as the best case error of symmetric double-sided two-way ranging. Crucially, the error depends only on the clock drift of one of the devices, which can be exploited if one of the device has a better timing reference than the other.
{"title":"An alternative double-sided two-way ranging method","authors":"D. Neirynck, Eric Luk, Michael McLaughlin","doi":"10.1109/WPNC.2016.7822844","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822844","url":null,"abstract":"Symmetric double-sided two-way ranging is a well-known technique to deal with clock drift in time-of-flight measurements between unsynchronised devices. However, the requirement for symmetric reply delays is often not feasible. This paper presents an alternative way to process double-sided two-way ranging measurements that eliminates the need for this impractical constraint. The error of the proposed method is of the same order of magnitude as the best case error of symmetric double-sided two-way ranging. Crucially, the error depends only on the clock drift of one of the devices, which can be exploited if one of the device has a better timing reference than the other.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130465564","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822846
Swen Leugner, Mathias Pelka, H. Hellbrück
Indoor localization with Uplink Time Difference of Arrival (U-TDoA) provides good scalability, high updates rates and high accuracy. However, clock errors lead to localization errors and synchronization is important. In this paper, we design and implement wired and wireless synchronization and provide a comparison between them. We design and implement a wireless synchronization with clock drift compensation. For wired and wireless synchronization, we discuss reasons for clock deviation that lead to localization errors. We evaluate both approaches in a U-TDoA measurement setup. Finally, we provide recommendations for wired and wireless synchronization. Additionally to localization, wireless synchronization is suited for Time Division Multiple Access (TDMA).
{"title":"Comparison of wired and wireless synchronization with clock drift compensation suited for U-TDoA localization","authors":"Swen Leugner, Mathias Pelka, H. Hellbrück","doi":"10.1109/WPNC.2016.7822846","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822846","url":null,"abstract":"Indoor localization with Uplink Time Difference of Arrival (U-TDoA) provides good scalability, high updates rates and high accuracy. However, clock errors lead to localization errors and synchronization is important. In this paper, we design and implement wired and wireless synchronization and provide a comparison between them. We design and implement a wireless synchronization with clock drift compensation. For wired and wireless synchronization, we discuss reasons for clock deviation that lead to localization errors. We evaluate both approaches in a U-TDoA measurement setup. Finally, we provide recommendations for wired and wireless synchronization. Additionally to localization, wireless synchronization is suited for Time Division Multiple Access (TDMA).","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121837826","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822848
Gia-Minh Hoang, B. Denis, Jérôme Härri, D. Slock
Cooperative positioning based on Impulse Radio — Ultra WideBand (IR-UWB) is known to provide a centimeter-level accuracy when the positions of anchor nodes are perfectly known. In Vehicular Ad-Hoc Networks (VANETs), vehicles acting as “virtual anchor” nodes are highly mobile with imperfect position estimates delivered by the Global Navigation Satellite System (GNSS). The large difference between measurement noises of GNSS positioning and IR-UWB Vehicle-to-Vehicle (V2V) ranging creates a bias in the localization filter, which is cooperatively propagated to other to other vehicles, and therefore significantly attenuates the benefits of IR-UWB for Cooperative Localization (CLoc). This paper compensates this drawback by a novel 2-step CLoc fusion framework. It first selects the “virtual anchor” nodes with the lowest GNSS position uncertainty to mitigate and stop the propagation of the biases. Once all biases have been reduced, it refines localization accuracy through exhaustive fusion. This strategy increases the probability to reach a 40 cm accuracy from 25% (conventional IR-UWB) to 95%, and even a 20 cm accuracy from 5% to 40%.
{"title":"Cooperative localization in GNSS-aided VANETs with accurate IR-UWB range measurements","authors":"Gia-Minh Hoang, B. Denis, Jérôme Härri, D. Slock","doi":"10.1109/WPNC.2016.7822848","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822848","url":null,"abstract":"Cooperative positioning based on Impulse Radio — Ultra WideBand (IR-UWB) is known to provide a centimeter-level accuracy when the positions of anchor nodes are perfectly known. In Vehicular Ad-Hoc Networks (VANETs), vehicles acting as “virtual anchor” nodes are highly mobile with imperfect position estimates delivered by the Global Navigation Satellite System (GNSS). The large difference between measurement noises of GNSS positioning and IR-UWB Vehicle-to-Vehicle (V2V) ranging creates a bias in the localization filter, which is cooperatively propagated to other to other vehicles, and therefore significantly attenuates the benefits of IR-UWB for Cooperative Localization (CLoc). This paper compensates this drawback by a novel 2-step CLoc fusion framework. It first selects the “virtual anchor” nodes with the lowest GNSS position uncertainty to mitigate and stop the propagation of the biases. Once all biases have been reduced, it refines localization accuracy through exhaustive fusion. This strategy increases the probability to reach a 40 cm accuracy from 25% (conventional IR-UWB) to 95%, and even a 20 cm accuracy from 5% to 40%.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125168101","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822851
I. Passchier, G. V. Vugt, Komal Rauf
Positioning and timing subsystems are crucial components for cooperative and autonomous driving. Both during development and for validation and certification, it is crucial that advanced testing systems are available. To support the complete development life cycle, testing tools for hardware in the loop testing, open test track testing, and public road testing are required. This paper gives an overview of testing methodologies for all these cases. Furthermore, examples of implemented test systems are provided, illustrating how these test systems can be used in practice to support the development and certification process of positioning and timing systems for the automotive sector.
{"title":"Testing of positioning and timing for cooperative and autonomous driving systems","authors":"I. Passchier, G. V. Vugt, Komal Rauf","doi":"10.1109/WPNC.2016.7822851","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822851","url":null,"abstract":"Positioning and timing subsystems are crucial components for cooperative and autonomous driving. Both during development and for validation and certification, it is crucial that advanced testing systems are available. To support the complete development life cycle, testing tools for hardware in the loop testing, open test track testing, and public road testing are required. This paper gives an overview of testing methodologies for all these cases. Furthermore, examples of implemented test systems are provided, illustrating how these test systems can be used in practice to support the development and certification process of positioning and timing systems for the automotive sector.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128142370","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822858
H. Nikookar
In this paper accurate ranging using flexible wavelet packet modulation is addressed. Wavelet Packet modulated (WPM) signal can be used for joint communications and ranging (two functionalities in one technology). Using wavelet technology the optimal signal will be designed for the time-of-arrival (TOA) or time-difference-of-arrival (TDOA) ranging when there exists a synchronization error. The focus will be on the wavelet packet modulated signal as wavelets have lower sensitivity to distortion and interference as a result of synchronization error. Further advantage of wavelet technology lies in its flexibility to customize and shape the characteristics of the waveforms for context-aware communication and ranging purposes.
{"title":"Optimal wavelet design for TOA ranging in the presence of synchronization error","authors":"H. Nikookar","doi":"10.1109/WPNC.2016.7822858","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822858","url":null,"abstract":"In this paper accurate ranging using flexible wavelet packet modulation is addressed. Wavelet Packet modulated (WPM) signal can be used for joint communications and ranging (two functionalities in one technology). Using wavelet technology the optimal signal will be designed for the time-of-arrival (TOA) or time-difference-of-arrival (TDOA) ranging when there exists a synchronization error. The focus will be on the wavelet packet modulated signal as wavelets have lower sensitivity to distortion and interference as a result of synchronization error. Further advantage of wavelet technology lies in its flexibility to customize and shape the characteristics of the waveforms for context-aware communication and ranging purposes.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"175 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133905323","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822837
T. Nowak, M. Hartmann, L. Patino-Studencki, J. Thielecke
The use of wireless sensor networks is rapidly increasing. Also the demand of ubiquitous location sensors is swiftly expanding. Hence, energy and location-awareness come into focus of research today. A prospective approach for low-power locating sensor networks is received signal strength indicator (RSSI)-based direction finding. The presented approach is based on RSSI difference measurements retrieved by a array of directed antennas. In this paper, fundamental limits of RSSI-based direction finding are evaluated, beyond the Cramer-Rao Lower Bound (CRLB). That is not applicable for the design of a localization system topology due to the nature of the gain difference function that leads to an unbounded variance of the unbiased estimator. Thus, a maximum likelihood (ML) approach to the RSSI-based direction finding is presented. The ML estimator yields a limited variance for all signal directions. However, that benefit comes at the expense of being biased. Beyond treating direction estimates, mean square position errors are compared for both, the unbiased and the ML estimator.
{"title":"Fundamental limits in RSSI-based direction-of-arrival estimation","authors":"T. Nowak, M. Hartmann, L. Patino-Studencki, J. Thielecke","doi":"10.1109/WPNC.2016.7822837","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822837","url":null,"abstract":"The use of wireless sensor networks is rapidly increasing. Also the demand of ubiquitous location sensors is swiftly expanding. Hence, energy and location-awareness come into focus of research today. A prospective approach for low-power locating sensor networks is received signal strength indicator (RSSI)-based direction finding. The presented approach is based on RSSI difference measurements retrieved by a array of directed antennas. In this paper, fundamental limits of RSSI-based direction finding are evaluated, beyond the Cramer-Rao Lower Bound (CRLB). That is not applicable for the design of a localization system topology due to the nature of the gain difference function that leads to an unbounded variance of the unbiased estimator. Thus, a maximum likelihood (ML) approach to the RSSI-based direction finding is presented. The ML estimator yields a limited variance for all signal directions. However, that benefit comes at the expense of being biased. Beyond treating direction estimates, mean square position errors are compared for both, the unbiased and the ML estimator.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"111 7‐8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113969353","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822849
Richard Weber, Paul Balzer, O. Michler, Erik Mademann
In recent years, wireless sensor networks became popular for a wide range of mainstream applications. Closely related with this evolution, a problem for consumer market use emerged: How to initialize and setup the infrastructure automatically. This paper presents an approach to solve this problem. We present a novel approach how to build infrastructure maps only with anchor-mobile range measurements. The approach uses a baseline SLAM implementation in form of incremental posterior mapping. We adapt the approach by representing mobile posterior as well as anchor maps with probability grids similar to Markov Localization due to addressing the complex Range Only Simultaneous Localization and Mapping (RO-SLAM) problem. In urban areas mobiles are employed e.g. by pedestrians or bikes which feature a specific kinematic locomotion activity. Hence, we pair RO-SLAM with a SVM-based activity classifier in order to raise anchor mapping accuracy. Simulation results discuss algorithm convergence and demonstrate the accuracy improvement in the presence of activity information.
{"title":"Improved RO-SLAM using activity classification for automated V2X infrastructure mapping","authors":"Richard Weber, Paul Balzer, O. Michler, Erik Mademann","doi":"10.1109/WPNC.2016.7822849","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822849","url":null,"abstract":"In recent years, wireless sensor networks became popular for a wide range of mainstream applications. Closely related with this evolution, a problem for consumer market use emerged: How to initialize and setup the infrastructure automatically. This paper presents an approach to solve this problem. We present a novel approach how to build infrastructure maps only with anchor-mobile range measurements. The approach uses a baseline SLAM implementation in form of incremental posterior mapping. We adapt the approach by representing mobile posterior as well as anchor maps with probability grids similar to Markov Localization due to addressing the complex Range Only Simultaneous Localization and Mapping (RO-SLAM) problem. In urban areas mobiles are employed e.g. by pedestrians or bikes which feature a specific kinematic locomotion activity. Hence, we pair RO-SLAM with a SVM-based activity classifier in order to raise anchor mapping accuracy. Simulation results discuss algorithm convergence and demonstrate the accuracy improvement in the presence of activity information.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131295644","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 : 2016-10-01DOI: 10.1109/WPNC.2016.7822838
A. Popleteev
This paper presents an ongoing long-term study exploring indoor positioning systems based on ambient radio signals (such as FM, TV and GSM). We introduce an open-source platform designed to facilitate data acquisition in indoor localization experiments. The platform is currently employed for the creation of a public dataset of geo referenced ambient radio signal samples. The paper discusses the system design as well as the challenges and current lessons of the year-long experiment.
{"title":"Indoor positioning using ambient radio signals: Data acquisition platform for a long-term study","authors":"A. Popleteev","doi":"10.1109/WPNC.2016.7822838","DOIUrl":"https://doi.org/10.1109/WPNC.2016.7822838","url":null,"abstract":"This paper presents an ongoing long-term study exploring indoor positioning systems based on ambient radio signals (such as FM, TV and GSM). We introduce an open-source platform designed to facilitate data acquisition in indoor localization experiments. The platform is currently employed for the creation of a public dataset of geo referenced ambient radio signal samples. The paper discusses the system design as well as the challenges and current lessons of the year-long experiment.","PeriodicalId":148664,"journal":{"name":"2016 13th Workshop on Positioning, Navigation and Communications (WPNC)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123871625","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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