Pub Date : 2002-06-23DOI: 10.1109/DSN.2002.1028887
Xiaoliang Zhao, Dan Pei, Lan Wang, D. Massey, A. Mankin, S. F. Wu, Lixia Zhang
Network measurement has shown that a specific IP address prefix may be announced by more than one autonomous system (AS), a phenomenon commonly referred to as Multiple Origin AS, or MOAS. MOAS can be due to either operational need to support multi-homing, or false route announcements due to configuration or implementation errors, or even by intentional attacks. Packets following such bogus routes will be either dropped or in the case of an intentional attack, delivered to a machine of the attacker's choosing. The paper presents a protocol enhancement to BGP which enables BGP to detect bogus route announcements from false origins. Rather than imposing cryptography-based authentication and encryption to secure routing message exchanges, our solution makes use of the rich connectivity among ASs that exists in the Internet. Simulation results show that this simple solution can effectively detect false routing announcements even in the presence of multiple compromised routers, become more robust in larger topologies, and can substantially reduce the impact of false routing announcements even with a partial deployment.
{"title":"Detection of invalid routing announcement in the Internet","authors":"Xiaoliang Zhao, Dan Pei, Lan Wang, D. Massey, A. Mankin, S. F. Wu, Lixia Zhang","doi":"10.1109/DSN.2002.1028887","DOIUrl":"https://doi.org/10.1109/DSN.2002.1028887","url":null,"abstract":"Network measurement has shown that a specific IP address prefix may be announced by more than one autonomous system (AS), a phenomenon commonly referred to as Multiple Origin AS, or MOAS. MOAS can be due to either operational need to support multi-homing, or false route announcements due to configuration or implementation errors, or even by intentional attacks. Packets following such bogus routes will be either dropped or in the case of an intentional attack, delivered to a machine of the attacker's choosing. The paper presents a protocol enhancement to BGP which enables BGP to detect bogus route announcements from false origins. Rather than imposing cryptography-based authentication and encryption to secure routing message exchanges, our solution makes use of the rich connectivity among ASs that exists in the Internet. Simulation results show that this simple solution can effectively detect false routing announcements even in the presence of multiple compromised routers, become more robust in larger topologies, and can substantially reduce the impact of false routing announcements even with a partial deployment.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"16 1","pages":"59-68"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88040749","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 : 2002-06-23DOI: 10.1109/DSN.2002.1028909
Manuel Rodríguez, A. Albinet, J. Arlat
This paper presents a new prototype tool called MAFALDA-RT (Microkernel Assessment by Fault injection AnaLysis and Design Aid for Real Time systems) that is aimed at the dependability assessment of real-time systems. The tool proposes a novel method to cope with the problem of temporal intrusiveness caused by the use of SWIFI. In addition to typical failure modes (e.g., application hang, system hang, exception, etc), the observation capabilities of MAFALDA-RT extend to temporal measurements characterizing both the executive and application layers (e.g., task processing, task synchronization, context-switch, system calls, etc.). The usefulness of the tool is illustrated by a set of results of a significant case study, based on a real time system consisting of the Chorus microkernel and a mine drainage control application.
针对实时系统的可靠性评估问题，提出了一种新的原型工具MAFALDA-RT (Microkernel Assessment by Fault injection AnaLysis and Design Aid for Real Time systems)。该工具提出了一种新的方法来解决由于使用SWIFI而引起的时间入侵问题。除了典型的故障模式(例如，应用程序挂起、系统挂起、异常等)之外，MAFALDA-RT的观察能力还扩展到表征执行层和应用层的时间测量(例如，任务处理、任务同步、上下文切换、系统调用等)。基于由Chorus微内核和矿井排水控制应用组成的实时系统的一组重要案例研究结果说明了该工具的实用性。
{"title":"MAFALDA-RT: a tool for dependability assessment of real-time systems","authors":"Manuel Rodríguez, A. Albinet, J. Arlat","doi":"10.1109/DSN.2002.1028909","DOIUrl":"https://doi.org/10.1109/DSN.2002.1028909","url":null,"abstract":"This paper presents a new prototype tool called MAFALDA-RT (Microkernel Assessment by Fault injection AnaLysis and Design Aid for Real Time systems) that is aimed at the dependability assessment of real-time systems. The tool proposes a novel method to cope with the problem of temporal intrusiveness caused by the use of SWIFI. In addition to typical failure modes (e.g., application hang, system hang, exception, etc), the observation capabilities of MAFALDA-RT extend to temporal measurements characterizing both the executive and application layers (e.g., task processing, task synchronization, context-switch, system calls, etc.). The usefulness of the tool is illustrated by a set of results of a significant case study, based on a real time system consisting of the Chorus microkernel and a mine drainage control application.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"40 1","pages":"267-272"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86996884","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 : 2002-06-23DOI: 10.1109/DSN.2002.1029022
Mohammad Zulkernine, R. Seviora
This paper proposes a specification-based monitoring approach for automatic run-time detection of software errors and failures of distributed systems. The specification is assumed to be expressed in communicating finite state machines based formalism. The monitor observes the external I/O and partial state information of the target distributed system and uses them to interpret the specification. The approach is compositional as it achieves global monitoring by combining the component-level monitoring. The core of the paper describes the architecture and operations of the monitor The monitor includes several independent mechanisms, each tailored to detecting specific kinds of errors or failures. Their operations are described in detail using illustrative examples. Techniques for dealing with nondeterminism and concurrency issues in monitoring a distributed system are also discussed with respect to the considered model and specification. A case study describing the application of the prototype monitor to an embedded system is presented.
{"title":"A compositional approach to monitoring distributed systems","authors":"Mohammad Zulkernine, R. Seviora","doi":"10.1109/DSN.2002.1029022","DOIUrl":"https://doi.org/10.1109/DSN.2002.1029022","url":null,"abstract":"This paper proposes a specification-based monitoring approach for automatic run-time detection of software errors and failures of distributed systems. The specification is assumed to be expressed in communicating finite state machines based formalism. The monitor observes the external I/O and partial state information of the target distributed system and uses them to interpret the specification. The approach is compositional as it achieves global monitoring by combining the component-level monitoring. The core of the paper describes the architecture and operations of the monitor The monitor includes several independent mechanisms, each tailored to detecting specific kinds of errors or failures. Their operations are described in detail using illustrative examples. Techniques for dealing with nondeterminism and concurrency issues in monitoring a distributed system are also discussed with respect to the considered model and specification. A case study describing the application of the prototype monitor to an embedded system is presented.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"27 1","pages":"763-772"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85671708","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 : 2002-06-23DOI: 10.1109/DSN.2002.1029006
George Candea, J. Cutler, A. Fox, Rushabh Doshi, Priyank Garg, Rakesh Gowda
We present ideas on how to structure software systems for high availability by considering MTTR/MTTF characteristics of components in addition to the traditional criteria, such as functionality or state sharing. Recursive restartability (RR), a recently proposed technique for achieving high availability, exploits partial restarts at various levels within complex software infrastructures to recover from transient failures and rejuvenate software components. Here we refine the original proposal and apply the RR philosophy to Mercury, a COTS-based satellite ground station that has been in operation for over 2 years. We develop three techniques for transforming component group boundaries such that time-to-recover is reduced, hence increasing system availability. We also further RR by defining the notions of an oracle, restart group and restart policy, while showing how to reason about system properties in terms of restart groups. From our experience with applying RR to Mercury, we draw design guidelines and lessons for the systematic application of recursive restartability to other software systems amenable to RR.
{"title":"Reducing recovery time in a small recursively restartable system","authors":"George Candea, J. Cutler, A. Fox, Rushabh Doshi, Priyank Garg, Rakesh Gowda","doi":"10.1109/DSN.2002.1029006","DOIUrl":"https://doi.org/10.1109/DSN.2002.1029006","url":null,"abstract":"We present ideas on how to structure software systems for high availability by considering MTTR/MTTF characteristics of components in addition to the traditional criteria, such as functionality or state sharing. Recursive restartability (RR), a recently proposed technique for achieving high availability, exploits partial restarts at various levels within complex software infrastructures to recover from transient failures and rejuvenate software components. Here we refine the original proposal and apply the RR philosophy to Mercury, a COTS-based satellite ground station that has been in operation for over 2 years. We develop three techniques for transforming component group boundaries such that time-to-recover is reduced, hence increasing system availability. We also further RR by defining the notions of an oracle, restart group and restart policy, while showing how to reason about system properties in terms of restart groups. From our experience with applying RR to Mercury, we draw design guidelines and lessons for the systematic application of recursive restartability to other software systems amenable to RR.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"20 1","pages":"605-614"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79992928","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 : 2002-06-23DOI: 10.1109/DSN.2002.1029013
Hairong Sun, James J. Han, I. Levendel
In this paper, we investigate the impact of a fault management server and its failure-related parameters on high-availability communication systems. The key point is that, to achieve high overall availability of a communication system, the availability of the fault management server itself is not as important as its fail-safe ratio and fault coverage. In other words, in building fault management servers, more attention should be paid to improving the server's ability of detecting faults in functional units and its own isolation under failure from the functional units. Tradeoffs can be made between the availability of the fault management server, the fail-safe ratio and the fault coverage ratio to optimize system availability. A cost-effective design for the fault management server is proposed in this paper.
{"title":"Impact of fault management server and its failure-related parameters on high-availability communication systems","authors":"Hairong Sun, James J. Han, I. Levendel","doi":"10.1109/DSN.2002.1029013","DOIUrl":"https://doi.org/10.1109/DSN.2002.1029013","url":null,"abstract":"In this paper, we investigate the impact of a fault management server and its failure-related parameters on high-availability communication systems. The key point is that, to achieve high overall availability of a communication system, the availability of the fault management server itself is not as important as its fail-safe ratio and fault coverage. In other words, in building fault management servers, more attention should be paid to improving the server's ability of detecting faults in functional units and its own isolation under failure from the functional units. Tradeoffs can be made between the availability of the fault management server, the fail-safe ratio and the fault coverage ratio to optimize system availability. A cost-effective design for the fault management server is proposed in this paper.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"4 1","pages":"679-686"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89639087","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 : 2002-06-23DOI: 10.1109/DSN.2002.1028920
M. Bertier, O. Marin, Pierre Sens
Chandra and Toueg (1996) introduced the concept of unreliable failure detectors, They showed how, by adding these detectors to an asynchronous system, it is possible to solve the Consensus problem. In this paper, we propose a new implementation of a failure detector. This implementation is a variant of the heartbeat failure detector which is adaptable and can support scalable applications. In this implementation we dissociate two aspects: a basic estimation of the expected arrival date to provide a short detection time, and an adaptation of the quality of service according to application needs. The latter is based on two principles: an adaptation layer and a heuristic to adapt the sending period of "I am alive" messages.
{"title":"Implementation and performance evaluation of an adaptable failure detector","authors":"M. Bertier, O. Marin, Pierre Sens","doi":"10.1109/DSN.2002.1028920","DOIUrl":"https://doi.org/10.1109/DSN.2002.1028920","url":null,"abstract":"Chandra and Toueg (1996) introduced the concept of unreliable failure detectors, They showed how, by adding these detectors to an asynchronous system, it is possible to solve the Consensus problem. In this paper, we propose a new implementation of a failure detector. This implementation is a variant of the heartbeat failure detector which is adaptable and can support scalable applications. In this implementation we dissociate two aspects: a basic estimation of the expected arrival date to provide a short detection time, and an adaptation of the quality of service according to application needs. The latter is based on two principles: an adaptation layer and a heuristic to adapt the sending period of \"I am alive\" messages.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"6 1","pages":"354-363"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75134061","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 : 2002-06-23DOI: 10.1109/DSN.2002.1029023
Paolo Ballarini, Simona Bernardi, S. Donatelli
This paper presents a case study on the combined use of different tools and techniques for the validation and evaluation, from, the early stages of the design, of a fault tolerant software mechanism named distributed synchronization. The mechanism has been specified using UML state charts and sequence diagrams. A number of stochastic well-formed nets (SWN) models have been derived from the specifications: they have been composed using the tool algebra, and the resulting model has been model-checked using the PROD tool for temporal logic properties, thanks to a GreatSPN-to-PROD translator. The quantitative analysis has been performed using the SWN solvers of the Great-SPN tool.
{"title":"Validation and evaluation of a software solution for fault tolerant distributed synchronization","authors":"Paolo Ballarini, Simona Bernardi, S. Donatelli","doi":"10.1109/DSN.2002.1029023","DOIUrl":"https://doi.org/10.1109/DSN.2002.1029023","url":null,"abstract":"This paper presents a case study on the combined use of different tools and techniques for the validation and evaluation, from, the early stages of the design, of a fault tolerant software mechanism named distributed synchronization. The mechanism has been specified using UML state charts and sequence diagrams. A number of stochastic well-formed nets (SWN) models have been derived from the specifications: they have been composed using the tool algebra, and the resulting model has been model-checked using the PROD tool for temporal logic properties, thanks to a GreatSPN-to-PROD translator. The quantitative analysis has been performed using the SWN solvers of the Great-SPN tool.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"30 1","pages":"773-782"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74208161","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 : 2002-06-23DOI: 10.1109/DSN.2002.1028975
Kishor S. Trivedi
Discusses SHARPE, a well known package in the field of reliability and performability, used in universities as well as in companies. A modeler who is familiar with many different kinds of models, can easily choose models that best suit a particular system and the kind of measure that is needed at each stage of the design. It is also possible to use different kinds of models hierarchically for different physical or abstract levels of the system and to use different kinds of models to validate each other's results. Steady-state and transient computations are available in the tool.
{"title":"SHARPE 2002: Symbolic Hierarchical Automated Reliability and Performance Evaluator","authors":"Kishor S. Trivedi","doi":"10.1109/DSN.2002.1028975","DOIUrl":"https://doi.org/10.1109/DSN.2002.1028975","url":null,"abstract":"Discusses SHARPE, a well known package in the field of reliability and performability, used in universities as well as in companies. A modeler who is familiar with many different kinds of models, can easily choose models that best suit a particular system and the kind of measure that is needed at each stage of the design. It is also possible to use different kinds of models hierarchically for different physical or abstract levels of the system and to use different kinds of models to validate each other's results. Steady-state and transient computations are available in the tool.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"23 1","pages":"544-"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85246007","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 : 2002-06-23DOI: 10.1109/DSN.2002.1029018
R. Khayari, R. Sadre, B. Haverkort
Since the early 1990s, a variety of studies has shown that network traffic, both for local- and wide-area networks, has self-similarity properties. This has led to new approaches in network traffic modelling. Instead of developing completely new traffic models, a number of researchers have proposed to adapt traditional traffic modelling approaches to incorporate aspects of self-similarity. The motivation for doing so is the hope to be able to reuse techniques and tools that have been developed in the past and with which experience has been gained. One such an approach for a traffic model that incorporates aspects of self-similarity is the so-called pseudo self-similar traffic model. This model is appealing, as it is easy, to understand and easily embedded in Markovian performance evaluation studies. In applying this model in a number of cases, we have perceived various problems which we initially, thought were particular to these specific cases. We briefly review the pseudo self-similar traffic model and discuss its fundamental shortcomings.
{"title":"A validation of the pseudo self-similar traffic model","authors":"R. Khayari, R. Sadre, B. Haverkort","doi":"10.1109/DSN.2002.1029018","DOIUrl":"https://doi.org/10.1109/DSN.2002.1029018","url":null,"abstract":"Since the early 1990s, a variety of studies has shown that network traffic, both for local- and wide-area networks, has self-similarity properties. This has led to new approaches in network traffic modelling. Instead of developing completely new traffic models, a number of researchers have proposed to adapt traditional traffic modelling approaches to incorporate aspects of self-similarity. The motivation for doing so is the hope to be able to reuse techniques and tools that have been developed in the past and with which experience has been gained. One such an approach for a traffic model that incorporates aspects of self-similarity is the so-called pseudo self-similar traffic model. This model is appealing, as it is easy, to understand and easily embedded in Markovian performance evaluation studies. In applying this model in a number of cases, we have perceived various problems which we initially, thought were particular to these specific cases. We briefly review the pseudo self-similar traffic model and discuss its fundamental shortcomings.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"37 1","pages":"727-734"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78337663","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 : 2002-06-23DOI: 10.1109/DSN.2002.1028889
A. Striegel, G. Manimaran
The phenomenal growth of QoS-aware applications over the Internet has accelerated the development of key technologies such as differentiated services (DiffServ). Although QoS is provided through class-based service differentiation, the aspect of fault tolerance is not addressed in the DiffServ architecture. For traditional IP networks, the underlying link state protocol provides fault detection and recovery. However for QoS sensitive flows, the recovery times of such protocols may not be adequate. Although such a problem may be solved through fine grain HELLO timers, the underlying core routers may not be able to tolerate the additional CPU and bandwidth burden. The edge-based intelligence of the DiffServ domain represents a unique opportunity to improve the fault detection capability of the link state protocol. We propose a hybrid scheme whereby heartbeat packets are used to detect possible faults coupled with a temporary fine grain HELLO interval for fault location and possible recovery. We analyze our scheme through extensive simulation studies and we examine the tradeoffs and benefits of our scheme.
{"title":"Edge-based fault detection in a DiffServ network","authors":"A. Striegel, G. Manimaran","doi":"10.1109/DSN.2002.1028889","DOIUrl":"https://doi.org/10.1109/DSN.2002.1028889","url":null,"abstract":"The phenomenal growth of QoS-aware applications over the Internet has accelerated the development of key technologies such as differentiated services (DiffServ). Although QoS is provided through class-based service differentiation, the aspect of fault tolerance is not addressed in the DiffServ architecture. For traditional IP networks, the underlying link state protocol provides fault detection and recovery. However for QoS sensitive flows, the recovery times of such protocols may not be adequate. Although such a problem may be solved through fine grain HELLO timers, the underlying core routers may not be able to tolerate the additional CPU and bandwidth burden. The edge-based intelligence of the DiffServ domain represents a unique opportunity to improve the fault detection capability of the link state protocol. We propose a hybrid scheme whereby heartbeat packets are used to detect possible faults coupled with a temporary fine grain HELLO interval for fault location and possible recovery. We analyze our scheme through extensive simulation studies and we examine the tradeoffs and benefits of our scheme.","PeriodicalId":93807,"journal":{"name":"Proceedings. International Conference on Dependable Systems and Networks","volume":"14 1","pages":"79-88"},"PeriodicalIF":0.0,"publicationDate":"2002-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78366954","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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