Pub Date : 2018-06-01DOI: 10.23919/TMA.2018.8506522
A. Parichehreh, Stefan Alfredsson, A. Brunström
The unprecedented growth of user generated contents yielded by the proliferation of social networks applications, cellular based video surveillance and device-to-device (D2D) communication, makes the cellular uplink communication an attractive topic. In this paper we conduct a systematic evaluation and measurement analysis to characterize cellular uplink traffic and compare its interplay with different TCP congestion control algorithms (CCA), namely NewReno, Cubic, and BBR, in both stationary and mobility scenarios. The evaluation encompasses average throughput, average round trip time (RTT), fairness among simultaneous flows, and packet retransmission. The intended behavior of BBR has been observed in LTE uplink, but some severe issues such as lack of fairness among simultaneous flows and massive on device packet losses have been observed. It is observed that the lack of fairness among simultaneous flows can unpredictably change the throughput of multi-flow applications.
{"title":"Measurement Analysis of TCP Congestion Control Algorithms in LTE Uplink","authors":"A. Parichehreh, Stefan Alfredsson, A. Brunström","doi":"10.23919/TMA.2018.8506522","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506522","url":null,"abstract":"The unprecedented growth of user generated contents yielded by the proliferation of social networks applications, cellular based video surveillance and device-to-device (D2D) communication, makes the cellular uplink communication an attractive topic. In this paper we conduct a systematic evaluation and measurement analysis to characterize cellular uplink traffic and compare its interplay with different TCP congestion control algorithms (CCA), namely NewReno, Cubic, and BBR, in both stationary and mobility scenarios. The evaluation encompasses average throughput, average round trip time (RTT), fairness among simultaneous flows, and packet retransmission. The intended behavior of BBR has been observed in LTE uplink, but some severe issues such as lack of fairness among simultaneous flows and massive on device packet losses have been observed. It is observed that the lack of fairness among simultaneous flows can unpredictably change the throughput of multi-flow applications.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"180 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80193244","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506513
Esteban Carisimo, Carlos Selmo, José Ignacio Alvarez-Hamelin, A. Dhamdhere
There is recent evidence that the core of the Internet, which was formerly dominated by large transit providers, has been reshaped after the transition to a multimedia-oriented network, first by general-purpose CDNs and now by private CDNs. In this work we use k-cores, an element of graph theory, to define which ASes compose the core of the Internet and to track the evolution of the core since 1999. Specifically, we investigate whether large players in the Internet content and CDN ecosystem belong to the core and, if so, since when. We further investigate regional differences in the evolution of large content providers. Finally, we show that the core of the Internet has incorporated an increasing number of content ASes in recent years. To enable reproducibility of this work, we provide a website to allow interactive analysis of our datasets to detect, for example, “up and coming” ASes using customized queries.
{"title":"Studying the Evolution of Content Providers in the Internet Core","authors":"Esteban Carisimo, Carlos Selmo, José Ignacio Alvarez-Hamelin, A. Dhamdhere","doi":"10.23919/TMA.2018.8506513","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506513","url":null,"abstract":"There is recent evidence that the core of the Internet, which was formerly dominated by large transit providers, has been reshaped after the transition to a multimedia-oriented network, first by general-purpose CDNs and now by private CDNs. In this work we use k-cores, an element of graph theory, to define which ASes compose the core of the Internet and to track the evolution of the core since 1999. Specifically, we investigate whether large players in the Internet content and CDN ecosystem belong to the core and, if so, since when. We further investigate regional differences in the evolution of large content providers. Finally, we show that the core of the Internet has incorporated an increasing number of content ASes in recent years. To enable reproducibility of this work, we provide a website to allow interactive analysis of our datasets to detect, for example, “up and coming” ASes using customized queries.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"11 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90092487","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506566
R. V. Rosa, Christian Esteve Rothenberg
In the growing landscape of Virtualized Network Function (VNF) development processes and methodologies fueled by enabling technologies for virtualization, the myriad of customization options unveil unprecedented SW/HW configuration knobs and hazards. Underlying execution environments multiplex resources imposing hard-to-predict relationships between VNF performance metrics (e.g., latency), allocated infrastructure assets (e.g., vCPU), and stimuli workloads. Gym is a framework designed to enable automated testing and to extraction of such relationships by the means of VNF performance profiles, walking through a cause-effect path towards agile DevOps methodologies for NFV. The demo showcases the implementation of Gym through exemplified live extraction of VNF metrics for analytics use cases, such as comparison factors between physical network functions and pre-deployment infrastructure dimensioning.
{"title":"Automated VNF Testing with Gym: A Benchmarking Use Case","authors":"R. V. Rosa, Christian Esteve Rothenberg","doi":"10.23919/TMA.2018.8506566","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506566","url":null,"abstract":"In the growing landscape of Virtualized Network Function (VNF) development processes and methodologies fueled by enabling technologies for virtualization, the myriad of customization options unveil unprecedented SW/HW configuration knobs and hazards. Underlying execution environments multiplex resources imposing hard-to-predict relationships between VNF performance metrics (e.g., latency), allocated infrastructure assets (e.g., vCPU), and stimuli workloads. Gym is a framework designed to enable automated testing and to extraction of such relationships by the means of VNF performance profiles, walking through a cause-effect path towards agile DevOps methodologies for NFV. The demo showcases the implementation of Gym through exemplified live extraction of VNF metrics for analytics use cases, such as comparison factors between physical network functions and pre-deployment infrastructure dimensioning.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"6 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90145813","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506536
W. D. Vries, R. V. Rijswijk-Deij, P. Boer, A. Pras
In 2009 Google launched its Public DNS service, with its characteristic IP address 8.8.8.8. Since then, this service has grown to be the largest and most well-known DNS service in existence. The popularity of public DNS services has been disruptive for Content Delivery Networks (CDNs). CDNs rely on IP information to geo-Iocate clients. This no longer works in the presence of public resolvers, which led to the introduction of the EDNSO Client Subnet extension. ECS allows resolvers to reveal part of a client's IP address to authoritative name servers and helps CDNs pinpoint client origin. A useful side effect of ECS is that it can be used to study the workings of public DNS resolvers. In this paper, we leverage this side effect of ECS to study Google Public DNS. From a dataset of 3.7 billion DNS queries spanning 2.5 years, we extract ECS information and perform a longitudinal analysis of which clients are served from which Point-of-Presence. Our study focuses on two aspects of GPDNS. First, we show that while GPDNS has PoPs in many countries, traffic is frequently routed out of country, even if that was not necessary. Often this reduces performance, and perhaps more importantly, exposes DNS requests to state-level surveillance. Second, we study how GPDNS is used by clients. We show that end-users switch to GPDNS en masse when their ISP's DNS service is unresponsive, and do not switch back. We also find that many e-mail providers configure GPDNS as the resolver for their servers. This raises serious privacy concerns, as DNS queries from mail servers reveal information about hosts they exchange mail with. Because of GPDNS's use of ECS, this sensitive information is not only revealed to Google, but also to any operator of an authoritative name server that receives ECS-enabled queries from GPDNS during the lookup process.
{"title":"Passive Observations of a Large DNS Service: 2.5 Years in the Life of Google","authors":"W. D. Vries, R. V. Rijswijk-Deij, P. Boer, A. Pras","doi":"10.23919/TMA.2018.8506536","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506536","url":null,"abstract":"In 2009 Google launched its Public DNS service, with its characteristic IP address 8.8.8.8. Since then, this service has grown to be the largest and most well-known DNS service in existence. The popularity of public DNS services has been disruptive for Content Delivery Networks (CDNs). CDNs rely on IP information to geo-Iocate clients. This no longer works in the presence of public resolvers, which led to the introduction of the EDNSO Client Subnet extension. ECS allows resolvers to reveal part of a client's IP address to authoritative name servers and helps CDNs pinpoint client origin. A useful side effect of ECS is that it can be used to study the workings of public DNS resolvers. In this paper, we leverage this side effect of ECS to study Google Public DNS. From a dataset of 3.7 billion DNS queries spanning 2.5 years, we extract ECS information and perform a longitudinal analysis of which clients are served from which Point-of-Presence. Our study focuses on two aspects of GPDNS. First, we show that while GPDNS has PoPs in many countries, traffic is frequently routed out of country, even if that was not necessary. Often this reduces performance, and perhaps more importantly, exposes DNS requests to state-level surveillance. Second, we study how GPDNS is used by clients. We show that end-users switch to GPDNS en masse when their ISP's DNS service is unresponsive, and do not switch back. We also find that many e-mail providers configure GPDNS as the resolver for their servers. This raises serious privacy concerns, as DNS queries from mail servers reveal information about hosts they exchange mail with. Because of GPDNS's use of ECS, this sensitive information is not only revealed to Google, but also to any operator of an authoritative name server that receives ECS-enabled queries from GPDNS during the lookup process.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"156 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76918444","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506521
M. Wullink, G. Moura, Cristian Hesselman
Behind each Internet domain name, there is a set of entities/companies responsible for delivering the various services associated with it, such as Web hosting and e-mail. Together, they form what we refer to as DNS ecosystem. Currently, there is no single measurement tool designed to measure this ecosystem altogether. As a result, researchers that aim at analyzing (parts of) this ecosystem often have to spend significant amounts of time preparing and executing the multiple application measurements and post-processing their heterogeneous raw datasets. Given that time is a scare resource, this complexity diverts researcher's time from actual analysis, ultimately limiting how far many studies go. To help researchers facing this situation, we present Dmap, an active measurement application that reduces the complexity of executing both measurements and analysis. It does so by (i) automating the crawling of several application protocols (DNS, HTTP, TLS/SSL, SMTP, both over IPv4 and IPv6) and (ii) storing the results into a relational data base, enabling researchers to quickly perform hypothesis tests within interactive response times using SQL. Dmap current version has 40 classifiers that generate 166 derived features (e.g., CMS detection, page language), which can be used by researchers and operators to build applications and services. We present an evaluation of Dmap and show three applications that it can be used for, such as profiling the Alexa 1 million domains. We use Dmap at SIDN (.nl registry) for research on the. nl zone and make it open-source for researchers.
{"title":"Dmap: Automating Domain Name Ecosystem Measurements and Applications","authors":"M. Wullink, G. Moura, Cristian Hesselman","doi":"10.23919/TMA.2018.8506521","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506521","url":null,"abstract":"Behind each Internet domain name, there is a set of entities/companies responsible for delivering the various services associated with it, such as Web hosting and e-mail. Together, they form what we refer to as DNS ecosystem. Currently, there is no single measurement tool designed to measure this ecosystem altogether. As a result, researchers that aim at analyzing (parts of) this ecosystem often have to spend significant amounts of time preparing and executing the multiple application measurements and post-processing their heterogeneous raw datasets. Given that time is a scare resource, this complexity diverts researcher's time from actual analysis, ultimately limiting how far many studies go. To help researchers facing this situation, we present Dmap, an active measurement application that reduces the complexity of executing both measurements and analysis. It does so by (i) automating the crawling of several application protocols (DNS, HTTP, TLS/SSL, SMTP, both over IPv4 and IPv6) and (ii) storing the results into a relational data base, enabling researchers to quickly perform hypothesis tests within interactive response times using SQL. Dmap current version has 40 classifiers that generate 166 derived features (e.g., CMS detection, page language), which can be used by researchers and operators to build applications and services. We present an evaluation of Dmap and show three applications that it can be used for, such as profiling the Alexa 1 million domains. We use Dmap at SIDN (.nl registry) for research on the. nl zone and make it open-source for researchers.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"1 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74006054","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506489
Hoang Tran-Viet, Hajime Tazaki, Q. D. Coninck, O. Bonaventure
Voice is progressively becoming a popular way to interact with mobile devices such as smartphones or connected cars. Most of the current deployments depend on cloud services to recognize the user,s commands. For this reason, voice-controlled applications have stringent requirements in terms of delay or availability. On the other hand, many of the devices using such applications are attached to several wireless networks. On iPhones, Multipath TCP made voice-enabled applications useable while users move from cellular to WiFi. In this paper, we leverage the MONROE platform to analyze the performance of Multipath TCP for voice-activated applications. For this, we port the Multipath TCP Linux kernel code into the Linux Kernel Library so that it can run as a regular application. We extend iperf3 to emulate voice-activated applications and carry out measurement campaigns. Our measurements show that Multipath TCP brings clear benefits for users attached to two networks.
{"title":"Voice-Activated Applications and Multipath TCP: A Good Match?","authors":"Hoang Tran-Viet, Hajime Tazaki, Q. D. Coninck, O. Bonaventure","doi":"10.23919/TMA.2018.8506489","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506489","url":null,"abstract":"Voice is progressively becoming a popular way to interact with mobile devices such as smartphones or connected cars. Most of the current deployments depend on cloud services to recognize the user,s commands. For this reason, voice-controlled applications have stringent requirements in terms of delay or availability. On the other hand, many of the devices using such applications are attached to several wireless networks. On iPhones, Multipath TCP made voice-enabled applications useable while users move from cellular to WiFi. In this paper, we leverage the MONROE platform to analyze the performance of Multipath TCP for voice-activated applications. For this, we port the Multipath TCP Linux kernel code into the Linux Kernel Library so that it can run as a regular application. We extend iperf3 to emulate voice-activated applications and carry out measurement campaigns. Our measurements show that Multipath TCP brings clear benefits for users attached to two networks.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"23 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81208427","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506503
Theodoros Karagkioules, D. Tsilimantos, S. Valentin, Florian Wamser, Bernd Zeidler, Michael Seufert, Frank Loh, P. Tran-Gia
Datasets are a valuable resource to analyze, model and optimize network traffic. This paper describes a new public dataset for YouTube's popular video streaming client on mobile devices. At the moment, we are providing 374 hours of time-synchronous measurements at the network, transport and application layer from two controlled environments in Europe. After describing our experimental design in detail, we discuss how to use our dataset for the analysis and optimization of HTTP Adaptive Streaming (HAS) traffic and point to specific use cases. To assure reproducibility and for community benefit, we publish the dataset at [1].
{"title":"A Public Dataset for YouTube's Mobile Streaming Client","authors":"Theodoros Karagkioules, D. Tsilimantos, S. Valentin, Florian Wamser, Bernd Zeidler, Michael Seufert, Frank Loh, P. Tran-Gia","doi":"10.23919/TMA.2018.8506503","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506503","url":null,"abstract":"Datasets are a valuable resource to analyze, model and optimize network traffic. This paper describes a new public dataset for YouTube's popular video streaming client on mobile devices. At the moment, we are providing 374 hours of time-synchronous measurements at the network, transport and application layer from two controlled environments in Europe. After describing our experimental design in detail, we discuss how to use our dataset for the analysis and optimization of HTTP Adaptive Streaming (HAS) traffic and point to specific use cases. To assure reproducibility and for community benefit, we publish the dataset at [1].","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"35 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90543361","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506524
Michael Seufert, Nikolas Wehner, P. Casas
This demonstration introduces CroQoE, a new app for crowdsourced QoE studies of HTTP Adaptive Streaming. The app is running on the mobile device of the study participant and connects to a backend server to control the subjective QoE study. As video content is a crucial QoE factor, the proposed app allows the participant to submit keywords for topics or contents, which videos he wants to watch during the study. Matching videos are retrieved and prepared on the backend server, and the test conditions are included. Thereby, the user is able to watch interesting and relevant content during the QoE study.
{"title":"App for Dynamic Crowdsourced QoE Studies of HTTP Adaptive Streaming on Mobile Devices","authors":"Michael Seufert, Nikolas Wehner, P. Casas","doi":"10.23919/TMA.2018.8506524","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506524","url":null,"abstract":"This demonstration introduces CroQoE, a new app for crowdsourced QoE studies of HTTP Adaptive Streaming. The app is running on the mobile device of the study participant and connects to a backend server to control the subjective QoE study. As video content is a crucial QoE factor, the proposed app allows the participant to submit keywords for topics or contents, which videos he wants to watch during the study. Matching videos are retrieved and prepared on the backend server, and the test conditions are included. Thereby, the user is able to watch interesting and relevant content during the QoE study.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"42 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73915393","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 : 2018-06-01DOI: 10.23919/TMA.2018.8506529
S. Boumard, I. Harjula, T. Kanstrén, S. Rantala
Energy and spectral efficiencies are key metrics to assess the performance of networks and compare different configurations or techniques. There are many ways to define those metrics, and the performance indicators used in their calculation can also be measured in different ways. Using an LTE-A network, we measure different performance indicators and the metrics' outputs are compared. Modifying the transmitted output power, the bandwidth, and the number of base stations, different network configurations are also compared. As expected, the measurements show that increasing the bandwidth increases the throughput more than it increases the energy consumption. Results clearly show that using inappropriate indicators can be misleading. The power indicator should include all energy consumed and the throughput should be dependent on the traffic, taking into account the idle time of the network, if any. There is a need to include more performance indicators into the metrics, especially those related to quality of service.
{"title":"Comparison of Spectral and Energy Efficiency Metrics Using Measurements in a LTE-A Network","authors":"S. Boumard, I. Harjula, T. Kanstrén, S. Rantala","doi":"10.23919/TMA.2018.8506529","DOIUrl":"https://doi.org/10.23919/TMA.2018.8506529","url":null,"abstract":"Energy and spectral efficiencies are key metrics to assess the performance of networks and compare different configurations or techniques. There are many ways to define those metrics, and the performance indicators used in their calculation can also be measured in different ways. Using an LTE-A network, we measure different performance indicators and the metrics' outputs are compared. Modifying the transmitted output power, the bandwidth, and the number of base stations, different network configurations are also compared. As expected, the measurements show that increasing the bandwidth increases the throughput more than it increases the energy consumption. Results clearly show that using inappropriate indicators can be misleading. The power indicator should include all energy consumed and the throughput should be dependent on the traffic, taking into account the idle time of the network, if any. There is a need to include more performance indicators into the metrics, especially those related to quality of service.","PeriodicalId":6607,"journal":{"name":"2018 Network Traffic Measurement and Analysis Conference (TMA)","volume":"91 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78670291","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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