Pub Date : 2018-06-01DOI: 10.1109/NETSOFT.2018.8459915
Sevil Dräxler, Stefan Schneider, H. Karl
Network function virtualization requires scaling and placement, deciding the number and the location of function instances. Current approaches are limited in flexibility and practical applicability. Specifically, we study dynamic, single-step, joint scaling and placement of network services with bidirectional flows traversing Physical or Virtual Network Functions (VNFs) and returning to their sources. We develop models to support stateful components and legacy network functions with fixed locations in these network services as well as the possibility of reusing VNFs across network services. We formalize the problem of jointly scaling and placing such network services as a mixed-integer linear program (MILP). We show that this problem is NP-complete and also present a heuristic algorithm to find good solutions in short time. In an extensive evaluation with realistic scenarios, we investigate the capabilities of the two approaches.
{"title":"Scaling and Placing Bidirectional Services with Stateful Virtual and Physical Network Functions","authors":"Sevil Dräxler, Stefan Schneider, H. Karl","doi":"10.1109/NETSOFT.2018.8459915","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8459915","url":null,"abstract":"Network function virtualization requires scaling and placement, deciding the number and the location of function instances. Current approaches are limited in flexibility and practical applicability. Specifically, we study dynamic, single-step, joint scaling and placement of network services with bidirectional flows traversing Physical or Virtual Network Functions (VNFs) and returning to their sources. We develop models to support stateful components and legacy network functions with fixed locations in these network services as well as the possibility of reusing VNFs across network services. We formalize the problem of jointly scaling and placing such network services as a mixed-integer linear program (MILP). We show that this problem is NP-complete and also present a heuristic algorithm to find good solutions in short time. In an extensive evaluation with realistic scenarios, we investigate the capabilities of the two approaches.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129273170","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: 10.1109/NETSOFT.2018.8460116
Sidan Gao, Shalki Shrivastava, Kemafor Ogan, Yufeng Xin, I. Baldin
The separation of control and data planes promulgated in Software-Defined Networking (SDN) architectures provides new opportunities for sophisticated control over the paths packets take while traversing the network. At the same time the complexity of data representing the network state continues to grow, reflecting complex topological and policy relationships between network elements and their domains. It is critical to the success of SDN to design an abstraction layer capable of storing network topology information and allowing to query it using standardized tools, in a way similar to how traditional databases enabled the abstraction of relational data. This abstraction would cleanly separate policy implementations in SDN controllers from the nuts-and-bolts of handling the topology data. In this paper we investigate multiple approaches to path queries in semantically-rich network descriptions using a variety of mechanisms. We describe a method for storing and querying semantic network graph data using Tarjan path algebras - to our knowledge used for the first time in the context of path-finding in computer networks. We compare the expressiveness and performance of queries that are representative of multi-domain SDN environments.
{"title":"Evaluating Path Query Mechanisms as a Foundation for SDN Network Control","authors":"Sidan Gao, Shalki Shrivastava, Kemafor Ogan, Yufeng Xin, I. Baldin","doi":"10.1109/NETSOFT.2018.8460116","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8460116","url":null,"abstract":"The separation of control and data planes promulgated in Software-Defined Networking (SDN) architectures provides new opportunities for sophisticated control over the paths packets take while traversing the network. At the same time the complexity of data representing the network state continues to grow, reflecting complex topological and policy relationships between network elements and their domains. It is critical to the success of SDN to design an abstraction layer capable of storing network topology information and allowing to query it using standardized tools, in a way similar to how traditional databases enabled the abstraction of relational data. This abstraction would cleanly separate policy implementations in SDN controllers from the nuts-and-bolts of handling the topology data. In this paper we investigate multiple approaches to path queries in semantically-rich network descriptions using a variety of mechanisms. We describe a method for storing and querying semantic network graph data using Tarjan path algebras - to our knowledge used for the first time in the context of path-finding in computer networks. We compare the expressiveness and performance of queries that are representative of multi-domain SDN environments.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115590344","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: 10.1109/NETSOFT.2018.8458499
R. Bauer, M. Zitterbart
This paper conducts a systematic analysis of different conceptual choices on implementing ICN core functionalities (routing, forwarding, caching) in Software-defined networks. The analysis considers recent developments in the area of Software-defined Networking and Network Functions Virtualization. Based on this, four abstract models of deployment options are presented and their requirements, advantages and disadvantages are discussed. The paper also presents a preliminary coarse-grained performance evaluation of the different options.
{"title":"Analysis of Deployment Options for SDN-based Information Centric Networking","authors":"R. Bauer, M. Zitterbart","doi":"10.1109/NETSOFT.2018.8458499","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8458499","url":null,"abstract":"This paper conducts a systematic analysis of different conceptual choices on implementing ICN core functionalities (routing, forwarding, caching) in Software-defined networks. The analysis considers recent developments in the area of Software-defined Networking and Network Functions Virtualization. Based on this, four abstract models of deployment options are presented and their requirements, advantages and disadvantages are discussed. The paper also presents a preliminary coarse-grained performance evaluation of the different options.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127033228","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: 10.1109/NETSOFT.2018.8460038
Chaojie Yu, Zhipeng Yang, Xiang Chen, Jian Yang
Aiming at improving the video transmission service in Wireless Mesh Network (WMN), this paper presents a scalable video transmission system over WMN with Software Defined Networking (SDN) architecture. By integrating SDN, the control plane of WMN is separated from the data plane and been managed by a centralized controller which conduct network optimization using global network information. Following this architecture, we formulate the scalable video bitrate adaptation problem as maximizing the average video quality while keeping the link congestion probability below certain threshold. In order to solve this problem, we derive an online adaptation strategy based on large deviation principle (LDP) to estimate congestion probability and adjust the video's bitrate accordingly. To verify the performance of the proposed strategy, we implement our experiments in Mininet-wifi and the results validate the effectiveness of our algorithm.
{"title":"Scalable Video Transmission in Software Defined Wireless Mesh Network","authors":"Chaojie Yu, Zhipeng Yang, Xiang Chen, Jian Yang","doi":"10.1109/NETSOFT.2018.8460038","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8460038","url":null,"abstract":"Aiming at improving the video transmission service in Wireless Mesh Network (WMN), this paper presents a scalable video transmission system over WMN with Software Defined Networking (SDN) architecture. By integrating SDN, the control plane of WMN is separated from the data plane and been managed by a centralized controller which conduct network optimization using global network information. Following this architecture, we formulate the scalable video bitrate adaptation problem as maximizing the average video quality while keeping the link congestion probability below certain threshold. In order to solve this problem, we derive an online adaptation strategy based on large deviation principle (LDP) to estimate congestion probability and adjust the video's bitrate accordingly. To verify the performance of the proposed strategy, we implement our experiments in Mininet-wifi and the results validate the effectiveness of our algorithm.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126022470","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: 10.1109/NETSOFT.2018.8460087
Maryam Tanha, Dawood Sajjadi, Jianping Pan
Software Defined Networking (SDN) brings unprecedented opportunities for facilitating the management of Wireless Mesh Networks (WMNs), particularly when handling network dynamics such as link/node failures. The inflexible destination-based routing and failure recovery of conventional WMN routing protocols are superseded by the efficient and highly flexible per-flow (re)routing in SDN-based networks. Most of the existing works focus on protection by pre-computing backup paths using OpenFlow fast failover groups to reroute the flows in case of channel re-assignment or a single link failure in software-defined WMNs. However, the limitations of failure detection using link monitoring for protection have not been studied. Moreover, the potentials of restoration-based failure recovery to handle single/multiple failure scenarios, have not been fully investigated. In this paper, we implement a prototype for reactive failure recovery in multi-radio multi-channel software-defined WMNs that provides a detailed performance and sensitivity analysis. The acquired results from the SDN-based scenarios outperform the most popular conventional WMN routing protocols in terms of recovery time while preserving the best achievable throughput even when the out-of-band control network is partially impaired. We also demonstrate the limitation of link monitoring, which mainly results from the shared nature of wireless medium, for protection-based mechanisms in software-defined WMNs.
{"title":"Demystifying Failure Recovery for Software-Defined Wireless Mesh Networks","authors":"Maryam Tanha, Dawood Sajjadi, Jianping Pan","doi":"10.1109/NETSOFT.2018.8460087","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8460087","url":null,"abstract":"Software Defined Networking (SDN) brings unprecedented opportunities for facilitating the management of Wireless Mesh Networks (WMNs), particularly when handling network dynamics such as link/node failures. The inflexible destination-based routing and failure recovery of conventional WMN routing protocols are superseded by the efficient and highly flexible per-flow (re)routing in SDN-based networks. Most of the existing works focus on protection by pre-computing backup paths using OpenFlow fast failover groups to reroute the flows in case of channel re-assignment or a single link failure in software-defined WMNs. However, the limitations of failure detection using link monitoring for protection have not been studied. Moreover, the potentials of restoration-based failure recovery to handle single/multiple failure scenarios, have not been fully investigated. In this paper, we implement a prototype for reactive failure recovery in multi-radio multi-channel software-defined WMNs that provides a detailed performance and sensitivity analysis. The acquired results from the SDN-based scenarios outperform the most popular conventional WMN routing protocols in terms of recovery time while preserving the best achievable throughput even when the out-of-band control network is partially impaired. We also demonstrate the limitation of link monitoring, which mainly results from the shared nature of wireless medium, for protection-based mechanisms in software-defined WMNs.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117256088","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: 10.1109/NETSOFT.2018.8460029
Sevil Dräxler, Manuel Peuster, Marvin Illian, H. Karl
Understanding the behavior of the components of service function chains (SFCs) in different load situations is important for efficient and automatic management and orchestration of services. For this purpose and for practical research in network function virtualization in general, there is a great need for benchmarks and experimental data. In this paper, we describe our experiments for characterizing the relationship between resource demands of virtual network functions (VNFs) and the expected performance of the SFC, considering the individual performance of the VNFs as well as the interdependencies among VNFs within the SFC. We have designed our experiments focusing on video streaming, an important application in this context. We present examples of models for predicting the interdependence between resource demands and performance characteristics of SFCs using support vector regression and polynomial regression models. We also show practical evidence from our experiments that VNFs need to be benchmarked in their final chain setup, rather than individually, to capture important interdependencies that affect their performance. The data gathered from our experiments is publicly available.
{"title":"Generating Resource and Performance Models for Service Function Chains: The Video Streaming Case","authors":"Sevil Dräxler, Manuel Peuster, Marvin Illian, H. Karl","doi":"10.1109/NETSOFT.2018.8460029","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8460029","url":null,"abstract":"Understanding the behavior of the components of service function chains (SFCs) in different load situations is important for efficient and automatic management and orchestration of services. For this purpose and for practical research in network function virtualization in general, there is a great need for benchmarks and experimental data. In this paper, we describe our experiments for characterizing the relationship between resource demands of virtual network functions (VNFs) and the expected performance of the SFC, considering the individual performance of the VNFs as well as the interdependencies among VNFs within the SFC. We have designed our experiments focusing on video streaming, an important application in this context. We present examples of models for predicting the interdependence between resource demands and performance characteristics of SFCs using support vector regression and polynomial regression models. We also show practical evidence from our experiments that VNFs need to be benchmarked in their final chain setup, rather than individually, to capture important interdependencies that affect their performance. The data gathered from our experiments is publicly available.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126436807","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: 10.1109/NETSOFT.2018.8460009
H. Asai
Network softwarization has accelerated the research and development of network functions on commercial off-the-shelf hardware. Multicore scalability has been a key to achieve high-performance packet forwarding engines. However, resource efficiency and bottlenecks in multicore scaling have not been discussed in the past research. Therefore, different hardware configurations sometimes encounter serious performance degradation. This paper presents a design and implementation of the forwarding engine that efficiently scales on multicore systems. Exclusive CPU core utilization and buffer management enable concurrent processing without synchronization overheads between multiple CPU cores. Our experiments demonstrate that memory access in buffer handling is the bottleneck in multicore scaling, and thus, thorough buffer management to reduce cache misses of shared CPU caches is required to debottleneck it. We also exhibit that the efficiency of CPU resource utilization could be enhanced by taking the advantage of hyperthreading that alleviate the overheads of memory access latency. The implemented forwarding engine efficiently scales and achieves 0% loss routing against 143 mega-packets per second traffic on the backbone router's IPv4 routing table using twelve CPU cores.
{"title":"Efficient Multicore Scaling in Software Packet Forwarding Engines","authors":"H. Asai","doi":"10.1109/NETSOFT.2018.8460009","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8460009","url":null,"abstract":"Network softwarization has accelerated the research and development of network functions on commercial off-the-shelf hardware. Multicore scalability has been a key to achieve high-performance packet forwarding engines. However, resource efficiency and bottlenecks in multicore scaling have not been discussed in the past research. Therefore, different hardware configurations sometimes encounter serious performance degradation. This paper presents a design and implementation of the forwarding engine that efficiently scales on multicore systems. Exclusive CPU core utilization and buffer management enable concurrent processing without synchronization overheads between multiple CPU cores. Our experiments demonstrate that memory access in buffer handling is the bottleneck in multicore scaling, and thus, thorough buffer management to reduce cache misses of shared CPU caches is required to debottleneck it. We also exhibit that the efficiency of CPU resource utilization could be enhanced by taking the advantage of hyperthreading that alleviate the overheads of memory access latency. The implemented forwarding engine efficiently scales and achieves 0% loss routing against 143 mega-packets per second traffic on the backbone router's IPv4 routing table using twelve CPU cores.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131014299","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: 10.1109/NETSOFT.2018.8460092
Frank Loh, Florian Wamser, T. Hossfeld, P. Tran-Gia
Today's networks require a deep understanding of applications to optimize networks, efficiently design networks, and meet traffic demands, application heterogeneity, and application requirements. Current application areas include live video streaming and real-time applications, such as those that are named in 5G use cases with automation, disaster recovery, gaming, and Industry 4.0. In this work, we examine an application scenario with live video streaming and parallel real-time requirements in the uplink for disaster recovery. We study the quality of service (QoS) features of a remote-controlled drone. The drone is controlled via a tablet or smartphone while the video from the camera is transmitted from the drone to the user. There are high demands in both the uplink and downlink direction. The contribution of the work is the measurement of the QoS and application parameters for this scenario and the definition of influencing parameters for the application-layer.
{"title":"Quality of Service Assessment of Live Video Streaming with a Remote-Controlled Drone","authors":"Frank Loh, Florian Wamser, T. Hossfeld, P. Tran-Gia","doi":"10.1109/NETSOFT.2018.8460092","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8460092","url":null,"abstract":"Today's networks require a deep understanding of applications to optimize networks, efficiently design networks, and meet traffic demands, application heterogeneity, and application requirements. Current application areas include live video streaming and real-time applications, such as those that are named in 5G use cases with automation, disaster recovery, gaming, and Industry 4.0. In this work, we examine an application scenario with live video streaming and parallel real-time requirements in the uplink for disaster recovery. We study the quality of service (QoS) features of a remote-controlled drone. The drone is controlled via a tablet or smartphone while the video from the camera is transmitted from the drone to the user. There are high demands in both the uplink and downlink direction. The contribution of the work is the measurement of the QoS and application parameters for this scenario and the definition of influencing parameters for the application-layer.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129384062","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: 10.1109/NETSOFT.2018.8459971
Agnese V. Ventrella, Flavio Esposito, L. Grieco
Cyber foraging techniques have been proposed in edge computing to support resource-intensive and latency-sensitive mobile applications. In a natural or man-made disaster scenario, all cyber foraging challenges are exacerbated by two problems: edge nodes are scarce and hence easily overloaded and failures are common due to the ad-hoc hostile conditions. In this paper, we study the use of efficient load profiling and migration strategies to mitigate such problems. In particular, we propose FORMICA, an architecture for cyber foraging orchestration, whose goal is to minimize the completion time of a set of jobs offloaded from mobile devices. Existing service offloading solutions are mainly concerned with outsourcing a job out of the mobile responsibility. Our architecture supports both mobile-based offloading and backend-driven onloading i.e., the offloading decision is taken by the edge infrastructure and not by the mobile node. FORMICA leverages Gelenbe networks to estimate the load profile of each node of the edge computing infrastructure to make proactive load profiling decisions. Our evaluation on a proof-of-concept implementation shows the benefits of our policy-based architecture in several (challenged disaster) scenarios but its applicability is broad to other IoT-based latency-sensitive applications.
{"title":"Load Profiling and Migration for Effective Cyber Foraging in Disaster Scenarios with FORMICA","authors":"Agnese V. Ventrella, Flavio Esposito, L. Grieco","doi":"10.1109/NETSOFT.2018.8459971","DOIUrl":"https://doi.org/10.1109/NETSOFT.2018.8459971","url":null,"abstract":"Cyber foraging techniques have been proposed in edge computing to support resource-intensive and latency-sensitive mobile applications. In a natural or man-made disaster scenario, all cyber foraging challenges are exacerbated by two problems: edge nodes are scarce and hence easily overloaded and failures are common due to the ad-hoc hostile conditions. In this paper, we study the use of efficient load profiling and migration strategies to mitigate such problems. In particular, we propose FORMICA, an architecture for cyber foraging orchestration, whose goal is to minimize the completion time of a set of jobs offloaded from mobile devices. Existing service offloading solutions are mainly concerned with outsourcing a job out of the mobile responsibility. Our architecture supports both mobile-based offloading and backend-driven onloading i.e., the offloading decision is taken by the edge infrastructure and not by the mobile node. FORMICA leverages Gelenbe networks to estimate the load profile of each node of the edge computing infrastructure to make proactive load profiling decisions. Our evaluation on a proof-of-concept implementation shows the benefits of our policy-based architecture in several (challenged disaster) scenarios but its applicability is broad to other IoT-based latency-sensitive applications.","PeriodicalId":333377,"journal":{"name":"2018 4th IEEE Conference on Network Softwarization and Workshops (NetSoft)","volume":"85 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127438190","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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