Pub Date : 1998-10-27DOI: 10.1109/RTCSA.1998.726427
Jean-Ferdy Susini, L. Hazard, F. Boussinot
We extend the reactive approach to distributed computing. Reactive systems allow one to use instantaneous broadcast events, which is a very powerful communication means between parallel components, in addition to implicit synchronization. Extension to distribution implies that instantaneous broadcast becomes available over the network between local reactive areas. We describe a model of distributed reactive systems, called synchronized systems, and several algorithms of detection of instant termination to implement distributed instantaneous broadcast. In the infrastructure we choose to implement systems which consist of distributed reactive machines connected to synchronizers. We present various implementations in Java, using SugarCubes, the RMI mechanism and another distributed processing environment.
{"title":"Distributed reactive machines","authors":"Jean-Ferdy Susini, L. Hazard, F. Boussinot","doi":"10.1109/RTCSA.1998.726427","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726427","url":null,"abstract":"We extend the reactive approach to distributed computing. Reactive systems allow one to use instantaneous broadcast events, which is a very powerful communication means between parallel components, in addition to implicit synchronization. Extension to distribution implies that instantaneous broadcast becomes available over the network between local reactive areas. We describe a model of distributed reactive systems, called synchronized systems, and several algorithms of detection of instant termination to implement distributed instantaneous broadcast. In the infrastructure we choose to implement systems which consist of distributed reactive machines connected to synchronizers. We present various implementations in Java, using SugarCubes, the RMI mechanism and another distributed processing environment.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121046003","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726431
Chanho Ryu, E. Song, Booseon Jun, Young-Kuk Kim, Seong-il Jin
The objective of this paper is to develop a high performance access mechanism for real-time memory-resident database systems. Real-time systems have very important properties: timeliness and predictability. In conventional database systems, hashing is known faster than tree access mechanism on the simple searches. Hence, on some environments, hash can be more appropriate to the real-time applications. On the other hand, tree index mechanism, it is possible to search to a range of specific data. Depending on the distance of a node in the tree, however, each access time to a node in the tree is different. This feature is not desirable for real-time database application, which requires deterministic data access behavior. In this paper, we present a new combined access mechanism called Hybrid Tree-Hash (Hybrid-TH) mechanism. This mechanism is a complementary integration of tree-index and hash-index structure assuring that a Worst-Case Execution Time is bounded within a specific time, especially, when range search operation works. Our analysis shows that Hybrid-TH provides the predictability of data access operation in real-time memory-resident database systems (DBMS).
{"title":"Hybrid-TH: a hybrid access mechanism for real-time memory-resident database systems","authors":"Chanho Ryu, E. Song, Booseon Jun, Young-Kuk Kim, Seong-il Jin","doi":"10.1109/RTCSA.1998.726431","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726431","url":null,"abstract":"The objective of this paper is to develop a high performance access mechanism for real-time memory-resident database systems. Real-time systems have very important properties: timeliness and predictability. In conventional database systems, hashing is known faster than tree access mechanism on the simple searches. Hence, on some environments, hash can be more appropriate to the real-time applications. On the other hand, tree index mechanism, it is possible to search to a range of specific data. Depending on the distance of a node in the tree, however, each access time to a node in the tree is different. This feature is not desirable for real-time database application, which requires deterministic data access behavior. In this paper, we present a new combined access mechanism called Hybrid Tree-Hash (Hybrid-TH) mechanism. This mechanism is a complementary integration of tree-index and hash-index structure assuring that a Worst-Case Execution Time is bounded within a specific time, especially, when range search operation works. Our analysis shows that Hybrid-TH provides the predictability of data access operation in real-time memory-resident database systems (DBMS).","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115453320","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726357
Yann-Hang Lee, Daeyoung Kim, M. Younis, Jeffrey X. Zhou
Advances in the computer technology encouraged the avionics industry to replace the federated design of control units with an integrated suite of control modules that share the computing resources. The new approach, which is called integrated modular avionics (IMA), can achieve substantial cost reduction in the development, operation and maintenance of airplanes. A set of guidelines has been developed by the avionics industry to facilitate the development and certification of integrated systems. Among them, a software architecture is recommended to address real time and fault tolerance requirements. According to the architecture, applications are classified into partitions supervised by an operating system executive. A general purpose application/executive (APEX) interface is defined which identifies the minimum functionality provided to the application software of an IMA system. To support the temporal partitioning between applications, APEX interface requires a deterministic cyclic scheduling of partitions at the O/S level and a fixed priority scheduling among processes within each partition. We propose a scheduling scheme for partitions in APEX. The scheme determines the frequency that each partition must be invoked and the assignment of processor capacity on every invocation. Then, a cyclic schedule at the O/S level can be constructed and all processes within each partition can meet their deadline requirements.
{"title":"Partition scheduling in APEX runtime environment for embedded avionics software","authors":"Yann-Hang Lee, Daeyoung Kim, M. Younis, Jeffrey X. Zhou","doi":"10.1109/RTCSA.1998.726357","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726357","url":null,"abstract":"Advances in the computer technology encouraged the avionics industry to replace the federated design of control units with an integrated suite of control modules that share the computing resources. The new approach, which is called integrated modular avionics (IMA), can achieve substantial cost reduction in the development, operation and maintenance of airplanes. A set of guidelines has been developed by the avionics industry to facilitate the development and certification of integrated systems. Among them, a software architecture is recommended to address real time and fault tolerance requirements. According to the architecture, applications are classified into partitions supervised by an operating system executive. A general purpose application/executive (APEX) interface is defined which identifies the minimum functionality provided to the application software of an IMA system. To support the temporal partitioning between applications, APEX interface requires a deterministic cyclic scheduling of partitions at the O/S level and a fixed priority scheduling among processes within each partition. We propose a scheduling scheme for partitions in APEX. The scheme determines the frequency that each partition must be invoked and the assignment of processor capacity on every invocation. Then, a cyclic schedule at the O/S level can be constructed and all processes within each partition can meet their deadline requirements.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116874300","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726354
G. Lipari, G. Buttazzo, Luca Abeni
The paper focuses on the problem of providing efficient run time support for different applications running on a real time system. The goal of our research is to develop a scheduling algorithm to allow independent applications to coexist on the same system. In order to meet the requested QoS, we assign each application a minimum bandwidth and guarantee that it never demands more. This algorithm does not require the exact knowledge of the execution times and interarrival times of the application tasks: hence, it is especially suited for soft real time and multimedia applications.
{"title":"A bandwidth reservation algorithm for multi-application systems","authors":"G. Lipari, G. Buttazzo, Luca Abeni","doi":"10.1109/RTCSA.1998.726354","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726354","url":null,"abstract":"The paper focuses on the problem of providing efficient run time support for different applications running on a real time system. The goal of our research is to develop a scheduling algorithm to allow independent applications to coexist on the same system. In order to meet the requested QoS, we assign each application a minimum bandwidth and guarantee that it never demands more. This algorithm does not require the exact knowledge of the execution times and interarrival times of the application tasks: hence, it is especially suited for soft real time and multimedia applications.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117293986","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726358
Y. Kakuda, K. Ishida, S. Inoue, K. Amano
Multicast is a message delivery scheme from a source node to all nodes that belong to the given membership through a multicast tree. The paper discusses how source based multicast trees are set up such that the maximum damage due to failure of any link to the multicast trees is minimized. Then, the paper proposes a multiagent based method for finding such multiple source based multicast trees. The proposed method assumes that candidates of multicast tree rooted at each source node are given according to some criteria. Under this assumption, first, shared links in multiple multicast trees whose source nodes are different are recognized. Then, a multicast tree rooted at each source node is determined such that damage due to failure of a shared link is minimized. The proposed method has a potentially good adaptability for change of both network resources such as topology and link capacity and resource requirements such as source node, membership, and bandwidth of multicast trees.
{"title":"Resource reservation for multicast trees using multiagents","authors":"Y. Kakuda, K. Ishida, S. Inoue, K. Amano","doi":"10.1109/RTCSA.1998.726358","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726358","url":null,"abstract":"Multicast is a message delivery scheme from a source node to all nodes that belong to the given membership through a multicast tree. The paper discusses how source based multicast trees are set up such that the maximum damage due to failure of any link to the multicast trees is minimized. Then, the paper proposes a multiagent based method for finding such multiple source based multicast trees. The proposed method assumes that candidates of multicast tree rooted at each source node are given according to some criteria. Under this assumption, first, shared links in multiple multicast trees whose source nodes are different are recognized. Then, a multicast tree rooted at each source node is determined such that damage due to failure of a shared link is minimized. The proposed method has a potentially good adaptability for change of both network resources such as topology and link capacity and resource requirements such as source node, membership, and bandwidth of multicast trees.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123698460","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726360
K. Nishimura, Kaori Maeda, R. Aibara
In videoconferencing, which means a small group meeting, interactive distance learning and so on, there is a requirement to get required video at a remote site freely and easily by local control of a remote camera. However, there are some delays between camera control operations at a remote site and actual video images displayed on a local screen. Delays are caused by network delays between sender and receiver and by video compression delays. To operate a remote camera interactively, a user must control the device considering these delays. We describe these problems in the case of videoconferencing and develop a real time camera control system to solve them. Our approach does not involve reducing delays but showing delays for users by some indication under the current environment. With our proposed system, a user can easily operate a remote camera without considering network and compression delays. We use a new camera control protocol designed by us in our system. We also describe a prototype system and its evaluation used in distance learning.
{"title":"Real-time camera control for videoconferencing over the Internet","authors":"K. Nishimura, Kaori Maeda, R. Aibara","doi":"10.1109/RTCSA.1998.726360","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726360","url":null,"abstract":"In videoconferencing, which means a small group meeting, interactive distance learning and so on, there is a requirement to get required video at a remote site freely and easily by local control of a remote camera. However, there are some delays between camera control operations at a remote site and actual video images displayed on a local screen. Delays are caused by network delays between sender and receiver and by video compression delays. To operate a remote camera interactively, a user must control the device considering these delays. We describe these problems in the case of videoconferencing and develop a real time camera control system to solve them. Our approach does not involve reducing delays but showing delays for users by some indication under the current environment. With our proposed system, a user can easily operate a remote camera without considering network and compression delays. We use a new camera control protocol designed by us in our system. We also describe a prototype system and its evaluation used in distance learning.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126753205","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726359
K. Abe, T. Matsuura, K. Yasumoto, T. Higashino
We have developed a portable user level thread library RT-PTL on UNIX, which is intended to be used for soft real time processing, such as multimedia systems. A user level thread is known to be more efficient than a kernel level one because of its small context switch overhead. However user level thread has a restriction that if one thread issues a system call that forces the calling process to be entirely blocked (such as disk I/O operation), no other thread is runnable until the system call has completed. This characteristic is undesirable for real time processing. We present a method to overcome this restriction. Using this method, if one thread requests a system call such as disk I/O operation, only the thread that issues the request is blocked and other threads can continue execution. We have implemented this method and have confirmed by some experiments that the method is widely usable and is also efficient.
{"title":"Design and implementation of an efficient I/O method for a real-time user level thread library","authors":"K. Abe, T. Matsuura, K. Yasumoto, T. Higashino","doi":"10.1109/RTCSA.1998.726359","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726359","url":null,"abstract":"We have developed a portable user level thread library RT-PTL on UNIX, which is intended to be used for soft real time processing, such as multimedia systems. A user level thread is known to be more efficient than a kernel level one because of its small context switch overhead. However user level thread has a restriction that if one thread issues a system call that forces the calling process to be entirely blocked (such as disk I/O operation), no other thread is runnable until the system call has completed. This characteristic is undesirable for real time processing. We present a method to overcome this restriction. Using this method, if one thread requests a system call such as disk I/O operation, only the thread that issues the request is blocked and other threads can continue execution. We have implemented this method and have confirmed by some experiments that the method is widely usable and is also efficient.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115207344","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726346
Yu-Chung Wang, Kwei-Jay Lin
Linux has become one of the most popular UNIX operating systems. Commercial support for Linux and adoption of Linux in real world applications have now started to emerge. Some of the applications have strict real-time requirements. We discuss how to make Linux a real-time operating system. The real-time capability is achieved by three new kernel mechanisms. We port a microtimer into the kernel. We adopt the time-driven scheduling paradigm and implement a time-driven scheduler in the Linux kernel. Finally, we insert preemption points in the kernel to make it more preemptable so that real-time jobs may experience shorter blockings. Our approach is general and may be used to enhance the real-time capability of other non-real-time operating systems as well.
{"title":"Enhancing the real-time capability of the Linux kernel","authors":"Yu-Chung Wang, Kwei-Jay Lin","doi":"10.1109/RTCSA.1998.726346","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726346","url":null,"abstract":"Linux has become one of the most popular UNIX operating systems. Commercial support for Linux and adoption of Linux in real world applications have now started to emerge. Some of the applications have strict real-time requirements. We discuss how to make Linux a real-time operating system. The real-time capability is achieved by three new kernel mechanisms. We port a microtimer into the kernel. We adopt the time-driven scheduling paradigm and implement a time-driven scheduler in the Linux kernel. Finally, we insert preemption points in the kernel to make it more preemptable so that real-time jobs may experience shorter blockings. Our approach is general and may be used to enhance the real-time capability of other non-real-time operating systems as well.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133918302","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726356
J. Ng, HongOng Wai, S. Xiong, Xi-Wan Du
When a distributed MPEG player system is transmitting MPEG video streams over an open network, like the Internet, the system usually has no control on the network traffic. We define the quality of service (QoS) for video transmissions in an adaptive mechanism, and we propose a priority feedback mechanism with QoS Control (PFB-QoS) for a distributed MPEG player system. With the feedback signal coming from each client and our predefined priority mapping functions, the current status and priority of each client can be obtained. With such information, the video server will adapt to the dynamic changes in the network and make efforts to maintain the QoS requirement for each client under the current network constraints. From our preliminary experiments, we find that when a video server is serving multiple clients where every client can demand a different QoS, the use of a priority feedback mechanism can effectively maintain the committed quality of service.
{"title":"A distributed MPEG video player system with feedback and QoS control","authors":"J. Ng, HongOng Wai, S. Xiong, Xi-Wan Du","doi":"10.1109/RTCSA.1998.726356","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726356","url":null,"abstract":"When a distributed MPEG player system is transmitting MPEG video streams over an open network, like the Internet, the system usually has no control on the network traffic. We define the quality of service (QoS) for video transmissions in an adaptive mechanism, and we propose a priority feedback mechanism with QoS Control (PFB-QoS) for a distributed MPEG player system. With the feedback signal coming from each client and our predefined priority mapping functions, the current status and priority of each client can be obtained. With such information, the video server will adapt to the dynamic changes in the network and make efforts to maintain the QoS requirement for each client under the current network constraints. From our preliminary experiments, we find that when a video server is serving multiple clients where every client can demand a different QoS, the use of a priority feedback mechanism can effectively maintain the committed quality of service.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127538705","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 : 1998-10-27DOI: 10.1109/RTCSA.1998.726418
T. Hasegawa, T. Hasegawa, Toshihiko Kato
Most current systems which play video data produced remotely in a real time manner transfer video packets without retransmission. However, corrupted packets can be retransmitted if the time of playing is delayed for the fixed amount of time. This paper proposes a new reliable real time protocol, based on SSCOP for ATM networks, which retransmits the only corrupted packets which reach the receiver before the deadline. It also describes the implementation method of the proposed protocol in the UNIX kernel using STREAMS mechanism and its performance evaluation. This protocol can be applied to vic (videoconference tool) application and reduces the packet loss rate to less than 1/100.
{"title":"Design and implementation of reliable protocol for video data produced in real time manner","authors":"T. Hasegawa, T. Hasegawa, Toshihiko Kato","doi":"10.1109/RTCSA.1998.726418","DOIUrl":"https://doi.org/10.1109/RTCSA.1998.726418","url":null,"abstract":"Most current systems which play video data produced remotely in a real time manner transfer video packets without retransmission. However, corrupted packets can be retransmitted if the time of playing is delayed for the fixed amount of time. This paper proposes a new reliable real time protocol, based on SSCOP for ATM networks, which retransmits the only corrupted packets which reach the receiver before the deadline. It also describes the implementation method of the proposed protocol in the UNIX kernel using STREAMS mechanism and its performance evaluation. This protocol can be applied to vic (videoconference tool) application and reduces the packet loss rate to less than 1/100.","PeriodicalId":142319,"journal":{"name":"Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124577381","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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