Pub Date : 2003-12-19DOI: 10.1109/IPOM.2003.1251225
A. Molina, S. Tartarelli, F. Raspall, S. Niccolini
Several tools are already available for measuring IP traffic flows. However, a standard for exporting results is still missing and the IETF IPFIX WG (IP flow information export working group) is currently working towards this target. We present a prototype implementation of an IPFIX compliant flow meter and discuss its major challenges. Through an extensive profiling activity, we try to point out which operations are most critical for scalability issues. The latter can be raised by both a large number of contemporary flows and a high packet input rate. We finally provide some indicative figures of the incoming traffic rate, which can be reliably monitored with the platform we used to test our implementation.
{"title":"Implementation of an IPFIX compliant flow traffic meter: challenges and performance assessment","authors":"A. Molina, S. Tartarelli, F. Raspall, S. Niccolini","doi":"10.1109/IPOM.2003.1251225","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251225","url":null,"abstract":"Several tools are already available for measuring IP traffic flows. However, a standard for exporting results is still missing and the IETF IPFIX WG (IP flow information export working group) is currently working towards this target. We present a prototype implementation of an IPFIX compliant flow meter and discuss its major challenges. Through an extensive profiling activity, we try to point out which operations are most critical for scalability issues. The latter can be raised by both a large number of contemporary flows and a high packet input rate. We finally provide some indicative figures of the incoming traffic rate, which can be reliably monitored with the platform we used to test our implementation.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122242086","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251229
D. Yuan
For intra-domain routing, open shortest path first (OSPF) is the most commonly used protocol. In OSPF, traffic is routed using paths that are shortest with respect to a set of link costs. One problem is the optimization of OSPF link costs. The problem amounts to finding a set of link costs such that the total network congestion is minimized. We consider robust OSPF routing that takes into account the impact of link failures. The optimized link costs for the non-failure scenario do not necessarily minimize the congestion when a link failure occurs. An OSPF routing solution is robust if it not only leads to low congestion in the non-failure scenario, but also attempts to minimize the impact of link failures. To address this problem, we present a bicriteria optimization model, which simultaneously considers the congestion of the normal state and that of the failure states. Previously proposed methods for bicriteria optimization problems often involve weighting together the two objective functions. We propose a different approach using an artificial objective function. When embedded into a local search algorithm, the function guides the search towards Pareto-optimal solutions. These solutions can be used for analyzing the trade-off between the congestion of the normal state and that of the failure states. The proposed algorithm can therefore be used as an aid for implementing robust OSPF routing.
{"title":"A bicriteria optimization approach for robust OSPF routing","authors":"D. Yuan","doi":"10.1109/IPOM.2003.1251229","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251229","url":null,"abstract":"For intra-domain routing, open shortest path first (OSPF) is the most commonly used protocol. In OSPF, traffic is routed using paths that are shortest with respect to a set of link costs. One problem is the optimization of OSPF link costs. The problem amounts to finding a set of link costs such that the total network congestion is minimized. We consider robust OSPF routing that takes into account the impact of link failures. The optimized link costs for the non-failure scenario do not necessarily minimize the congestion when a link failure occurs. An OSPF routing solution is robust if it not only leads to low congestion in the non-failure scenario, but also attempts to minimize the impact of link failures. To address this problem, we present a bicriteria optimization model, which simultaneously considers the congestion of the normal state and that of the failure states. Previously proposed methods for bicriteria optimization problems often involve weighting together the two objective functions. We propose a different approach using an artificial objective function. When embedded into a local search algorithm, the function guides the search towards Pareto-optimal solutions. These solutions can be used for analyzing the trade-off between the congestion of the normal state and that of the failure states. The proposed algorithm can therefore be used as an aid for implementing robust OSPF routing.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133172923","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251232
M. Girish, B. Zhou, Jianqiang Hu
Multiprotocol label switching (MPLS) enables IP networks with quality of service to be traffic engineered well. Rerouting and bumping of label switched paths (LSP) are caused by link or node failure or recovery, connection admission or load balancing. We develop an algorithm for the traffic engineering problem associated with rerouting.
{"title":"An algorithm for rerouting in traffic engineering of MPLS based IP networks","authors":"M. Girish, B. Zhou, Jianqiang Hu","doi":"10.1109/IPOM.2003.1251232","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251232","url":null,"abstract":"Multiprotocol label switching (MPLS) enables IP networks with quality of service to be traffic engineered well. Rerouting and bumping of label switched paths (LSP) are caused by link or node failure or recovery, connection admission or load balancing. We develop an algorithm for the traffic engineering problem associated with rerouting.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121805776","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251223
Matthew C Schlesener, Joseph Evans, Gary Minden, user user, C. User
A new signaling protocol being developed for use in the Internet or an enterprise IP network is analyzed. The protocol is telephony routing over IP (TRIP). The most basic function of TRIP is to locate the optimum gateway on a voice over IP (VoIP) network connected to the public switched telephone network (PSTN). TRIP is analyzed from a carrier perspective and performance results are discussed.
分析了一种用于Internet或企业IP网络的新的信令协议。该协议是基于IP的电话路由(TRIP)。TRIP最基本的功能是定位与PSTN (public switched telephone network)相连的VoIP (voice over IP)网络上的最佳网关。从载波角度对TRIP进行了分析，并对性能结果进行了讨论。
{"title":"Performance evaluation of telephony routing over IP (TRIP)","authors":"Matthew C Schlesener, Joseph Evans, Gary Minden, user user, C. User","doi":"10.1109/IPOM.2003.1251223","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251223","url":null,"abstract":"A new signaling protocol being developed for use in the Internet or an enterprise IP network is analyzed. The protocol is telephony routing over IP (TRIP). The most basic function of TRIP is to locate the optimum gateway on a voice over IP (VoIP) network connected to the public switched telephone network (PSTN). TRIP is analyzed from a carrier perspective and performance results are discussed.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122081326","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251219
E. Gelenbe, R. Lent, A. Núñez
The World Wide Web (WWW) has caught people's attention since its inception and today is a major source of traffic in the Internet. WWW traffic is typically asymmetric: servers receive small requests but answer with large number of packets. To ensure good service, WWW servers require a large egress bandwidth to the Internet. We propose an innovative approach to connect Web servers to the Internet via many outgoing connections. We employ cognitive packet networks to make packets learn which link provides the best quality for each client so as to balance the WWW traffic effectively. Egress bandwidth can easily be increased by increasing the number of links to the Internet. The paper describes our traffic engineering approach, an implementation model, a testbed platform in the context of the Linux kernel, and measurement data; these indicate the usefulness of our proposal.
{"title":"Traffic balancing via smart packets","authors":"E. Gelenbe, R. Lent, A. Núñez","doi":"10.1109/IPOM.2003.1251219","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251219","url":null,"abstract":"The World Wide Web (WWW) has caught people's attention since its inception and today is a major source of traffic in the Internet. WWW traffic is typically asymmetric: servers receive small requests but answer with large number of packets. To ensure good service, WWW servers require a large egress bandwidth to the Internet. We propose an innovative approach to connect Web servers to the Internet via many outgoing connections. We employ cognitive packet networks to make packets learn which link provides the best quality for each client so as to balance the WWW traffic effectively. Egress bandwidth can easily be increased by increasing the number of links to the Internet. The paper describes our traffic engineering approach, an implementation model, a testbed platform in the context of the Linux kernel, and measurement data; these indicate the usefulness of our proposal.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134458760","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251230
S. Beker, D. Kofman, N. Puech
One of the main reasons for the present market enthusiasm for the MPLS architecture is its capability for implementing evolved traffic engineering (TE) functionalities, as they are required, for example, to support the next generation Internet. MPLS paths (LSPs) can be calculated on-line, as demands arrive, or off-line for a given estimate of the traffic matrix. Off-line calculation has the advantage of enabling a globally optimal network design. From the operational standpoint, the layout design for a large network should consider minimizing the layout complexity, thus reducing the cost of operation. Layout optimization objectives usually aim at minimizing total delay in the network, maximum loaded link, or any other function of link loads. To address the layout complexity issue, we propose an optimization problem whose objective is to minimize the number of required paths, while an end-to-end path delay constraint provides the required quality of service (QoS) guarantees. To solve the resulting multicommodity flow allocation problem, a MINLP (mixed integer non linear program) formulation is used. The results are then compared to the solutions obtained with a commonly used cost function, which does not consider complexity.
{"title":"Off-line reduced complexity layout design for MPLS networks","authors":"S. Beker, D. Kofman, N. Puech","doi":"10.1109/IPOM.2003.1251230","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251230","url":null,"abstract":"One of the main reasons for the present market enthusiasm for the MPLS architecture is its capability for implementing evolved traffic engineering (TE) functionalities, as they are required, for example, to support the next generation Internet. MPLS paths (LSPs) can be calculated on-line, as demands arrive, or off-line for a given estimate of the traffic matrix. Off-line calculation has the advantage of enabling a globally optimal network design. From the operational standpoint, the layout design for a large network should consider minimizing the layout complexity, thus reducing the cost of operation. Layout optimization objectives usually aim at minimizing total delay in the network, maximum loaded link, or any other function of link loads. To address the layout complexity issue, we propose an optimization problem whose objective is to minimize the number of required paths, while an end-to-end path delay constraint provides the required quality of service (QoS) guarantees. To solve the resulting multicommodity flow allocation problem, a MINLP (mixed integer non linear program) formulation is used. The results are then compared to the solutions obtained with a commonly used cost function, which does not consider complexity.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133453027","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251222
Michael Mackay, Christopher Edwards
The paper outlines the need to supplement the current work on network management for IPv6 with a system specifically to support IP transitioning. As something that is likely to play a major role in any IPv6 network for the considerable future, support for managing the transitioning aspects of managed networks is vital in terms of their infrastructure and service provision. While there is work being carried out within the IETF and other bodies on the management of IPv6 networks, the management aspects relating to transitioning require special attention as they are likely to be among the more dynamic over the period of IPv4/IPv6 interoperation and, importantly, have yet to be fully addressed. The paper introduces the site transitioning framework, which unifies a site's transitioning infrastructure under a single architecture in order to simplify its management and operation. We outline its design and operation, highlighting the advantages that this method would introduce. Finally, the STF concept is demonstrated using a case study of an IPv6 site based interoperation scenario.
{"title":"IPv6 migration implications for network management - introducing the site transitioning framework (STF)","authors":"Michael Mackay, Christopher Edwards","doi":"10.1109/IPOM.2003.1251222","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251222","url":null,"abstract":"The paper outlines the need to supplement the current work on network management for IPv6 with a system specifically to support IP transitioning. As something that is likely to play a major role in any IPv6 network for the considerable future, support for managing the transitioning aspects of managed networks is vital in terms of their infrastructure and service provision. While there is work being carried out within the IETF and other bodies on the management of IPv6 networks, the management aspects relating to transitioning require special attention as they are likely to be among the more dynamic over the period of IPv4/IPv6 interoperation and, importantly, have yet to be fully addressed. The paper introduces the site transitioning framework, which unifies a site's transitioning infrastructure under a single architecture in order to simplify its management and operation. We outline its design and operation, highlighting the advantages that this method would introduce. Finally, the STF concept is demonstrated using a case study of an IPv6 site based interoperation scenario.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124788362","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251233
Risto Vaarandi
Today, event logs contain vast amounts of data that can easily overwhelm a human. Therefore, mining patterns from event logs is an important system management task. The paper presents a novel clustering algorithm for log file data sets which helps one to detect frequent patterns from log files, to build log file profiles, and to identify anomalous log file lines.
{"title":"A data clustering algorithm for mining patterns from event logs","authors":"Risto Vaarandi","doi":"10.1109/IPOM.2003.1251233","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251233","url":null,"abstract":"Today, event logs contain vast amounts of data that can easily overwhelm a human. Therefore, mining patterns from event logs is an important system management task. The paper presents a novel clustering algorithm for log file data sets which helps one to detect frequent patterns from log files, to build log file profiles, and to identify anomalous log file lines.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"187 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114183712","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251224
N. Brownlee, P. Christ, J. Jaehnert, Yongzheng Liang, K. Srinivasan, Jie Zhou
The commercial operation of future "4G" mobile wireless networks, comprising both IP-based voice and data uniformly, is widely considered as the next challenge for service providers. Within such an IP-environment, with its implicit integration of the control and data plane, passive measuring and metering will be one of the key elements for AAA and QoS provision, for performance and fault management purposes. Within the IETF, a real-time flow measurement framework has been developed for measurement and accounting for the fixed Internet infrastructure. The article first briefly introduces the IETF "real-time flow measurement" (RTFM) architecture, a pure IP 4G-architecture, together with its key signalling scenarios, and Java/J2EE and Web middleware technology. It then describes "FlowVis", a highly scalable and distributed IP based protocol visualization and verification framework for both signalling and data traffic. Combining the near-real-time capabilities of the existing IETF RTFM with current middleware technology, this "FlowVis" framework can serve as a starting point for distributed protocol analysis in future 4G networks. We use NeTraMet, an open-source implementation of the RTFM architecture as the key metering component of "Moby Dick", a 4G mobile access network architecture.
{"title":"MobyDick FlowVis - using NeTraMet for distributed protocol analysis in a 4G network environment","authors":"N. Brownlee, P. Christ, J. Jaehnert, Yongzheng Liang, K. Srinivasan, Jie Zhou","doi":"10.1109/IPOM.2003.1251224","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251224","url":null,"abstract":"The commercial operation of future \"4G\" mobile wireless networks, comprising both IP-based voice and data uniformly, is widely considered as the next challenge for service providers. Within such an IP-environment, with its implicit integration of the control and data plane, passive measuring and metering will be one of the key elements for AAA and QoS provision, for performance and fault management purposes. Within the IETF, a real-time flow measurement framework has been developed for measurement and accounting for the fixed Internet infrastructure. The article first briefly introduces the IETF \"real-time flow measurement\" (RTFM) architecture, a pure IP 4G-architecture, together with its key signalling scenarios, and Java/J2EE and Web middleware technology. It then describes \"FlowVis\", a highly scalable and distributed IP based protocol visualization and verification framework for both signalling and data traffic. Combining the near-real-time capabilities of the existing IETF RTFM with current middleware technology, this \"FlowVis\" framework can serve as a starting point for distributed protocol analysis in future 4G networks. We use NeTraMet, an open-source implementation of the RTFM architecture as the key metering component of \"Moby Dick\", a 4G mobile access network architecture.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114804399","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 : 2003-12-19DOI: 10.1109/IPOM.2003.1251217
I. Hamadeh, G. Kesidis
Distributed denial-of-service (DDoS) attacks are among the most difficult and damaging security problems that the Internet currently faces. The component problems for an end-system that is the victim of a DDoS attack are: determining which incoming packets are part of the attack (intrusion detection); tracing back to find the origins of the attack (i.e., "traceback"); taking action to mitigate or stop the attack at the source by configuring firewalls or taking some kind of punitive measures. The preferable solution to these problems operates in real time so that a DDoS attack can be mitigated before the victim is seriously harmed. The paper focuses on the technique of packet marking/overloading for automated DDoS traceback which is a complex problem simply because attackers can use spoof source IP addresses in their attacking packets. A new packet marking strategy is proposed and is shown to yield better results in terms of complexity and performance.
{"title":"Performance of IP address fragmentation strategies for DDoS traceback","authors":"I. Hamadeh, G. Kesidis","doi":"10.1109/IPOM.2003.1251217","DOIUrl":"https://doi.org/10.1109/IPOM.2003.1251217","url":null,"abstract":"Distributed denial-of-service (DDoS) attacks are among the most difficult and damaging security problems that the Internet currently faces. The component problems for an end-system that is the victim of a DDoS attack are: determining which incoming packets are part of the attack (intrusion detection); tracing back to find the origins of the attack (i.e., \"traceback\"); taking action to mitigate or stop the attack at the source by configuring firewalls or taking some kind of punitive measures. The preferable solution to these problems operates in real time so that a DDoS attack can be mitigated before the victim is seriously harmed. The paper focuses on the technique of packet marking/overloading for automated DDoS traceback which is a complex problem simply because attackers can use spoof source IP addresses in their attacking packets. A new packet marking strategy is proposed and is shown to yield better results in terms of complexity and performance.","PeriodicalId":128315,"journal":{"name":"Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) (IEEE Cat. No.03EX764)","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122561189","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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