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  • 201.
    Krishnamoorthi, Vengatanathan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Efficient HTTP-based Adaptive Streaming of Linear and Interactive Videos2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Online video streaming has gained tremendous popularity over recent years and currently constitutes the majority of Internet traffic. As large-scale on-demand streaming continues to gain popularity, several important questions and challenges remain unanswered. This thesis addresses open questions in the areas of efficient content delivery for HTTP-based Adaptive Streaming (HAS) from different perspectives (client, network and content provider) and in the design, implementation, and evaluation of interactive streaming applications over HAS.

    As streaming usage scales and new streaming services emerge, continuous improvements are required to both the infrastructure and the techniques used to deliver high-quality streams. In the context of Content Delivery Network (CDN) nodes or proxies, this thesis investigates the interaction between HAS clients and proxy caches. In particular, we propose and evaluate classes of content-aware and collaborative policies that take advantage of information that is already available, or share information among elements in the delivery chain, where all involved parties can benefit. Asides from the users’ playback experience, it is also important for content providers to minimize users’ startup times. We have designed and evaluated different classes of client-side policies that can prefetch data from the videos that the users are most likely to watch next, without negatively affecting the currently watched video. To help network providers to monitor and ensure that their customers enjoy good playback experiences, we have proposed and evaluated techniques that can be used to estimate clients’ current buffer conditions. Since several services today stream over HTTPS, our solution is adapted to predict client buffer conditions by only observing encrypted network-level traffic. Our solution allows the operator to identify clients with low-buffer conditions and implement policies that help avoid playback stalls.

    The emergence of HAS as the de facto standard for delivering streaming content also opens the door to use it to deliver the next generation of streaming services, such as various forms of interactive services. This class of services is gaining popularity and is expected to be the next big thing in entertainment. For the area of interactive streaming, this thesis proposes, models, designs, and evaluates novel streaming applications such as interactive branched videos and multi-video stream bundles. For these applications, we design and evaluate careful prefetching policies that provides seamless playback (without stalls or switching delay) even when interactive branched video viewers defer their choices to the last possible moment and when users switches between alternative streams within multi-video stream bundles. Using optimization frameworks, we design and implement effective buffer management techniques for seamless playback experiences and evaluate several tradeoffs using our policies.  

    Delarbeten
    1. Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance
    Öppna denna publikation i ny flik eller fönster >>Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance
    Visa övriga...
    2013 (Engelska)Ingår i: Modeling, Analysis & Simulation of Computer and Telecommunication Systems (MASCOTS), 2013 IEEE 21st International Symposium, IEEE , 2013, s. 182-191Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    HTTP-based Adaptive Streaming (HAS) has become a widely-used video delivery technology. Use of HTTP enables relatively easy firewall/NAT traversal and content caching. While caching is an important aspect of HAS, there is not much public research on the performance impact proxies and their policies have on HAS. In this paper we build an experimental framework using open source Squid proxies and the most recent Open Source Media Framework (OSMF). A range of content-aware policies can be implemented in the proxies and tested, while the player software can be instrumented to measure performance as seen at the client. Using this framework, the paper makes three main contributions. First, we present a scenario-based performance evaluation of the latest version of the OSMF player. Second, we quantify the benefits using different proxy-assisted solutions, including basic best effort policies and more advanced content quality aware prefetching policies. Finally, we present and evaluate a cooperative framework in which clients and proxies share information to improve performance. In general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, as they significantly impact the relative performance differences between policy classes. We conclude that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2013
    Serie
    Modeling, Analysis, and Simulation of Com puter and Telecommunications Systems, ISSN 1526-7539
    Nyckelord
    HTTP-based adaptive streaming, Proxy assisted
    Nationell ämneskategori
    Datavetenskap (datalogi)
    Identifikatorer
    urn:nbn:se:liu:diva-105282 (URN)10.1109/MASCOTS.2013.26 (DOI)978-0-7695-5102-9 (ISBN)978-1-4799-1209-4 (ISBN)
    Konferens
    IEEE 21st International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS), 14-16 August 2013, San Francisco, CA, USA
    Tillgänglig från: 2014-03-15 Skapad: 2014-03-15 Senast uppdaterad: 2018-02-06Bibliografiskt granskad
    2. Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance
    Öppna denna publikation i ny flik eller fönster >>Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance
    Visa övriga...
    2015 (Engelska)Ingår i: Proceedings of the ACM International Conference on Multimedia (ACM Multimedia), New York, USA: Association for Computing Machinery (ACM), 2015, s. 551-560Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper considers the problem of providing users playing one streaming video the option of instantaneous and seamless playback of alternative videos. Recommendation systems can easily provide a list of alternative videos, but there is little research on how to best eliminate the startup time for these alternative videos. The problem is motivated by services that want to retain increasingly impatient users, who frequently watch the beginning of multiple videos, before viewing a video to the end. We present the design, implementation, and evaluation of an HTTP-based Adaptive Streaming (HAS) solution that provides careful prefetching and buffer management. We also present the design and evaluation of three fundamental policy classes that provide different tradeoffs between how aggressively new alternative videos are prefetched versus the importance of ensuring high playback quality. We show that our solution allows us to reduce the startup times of alternative videos by an order of magnitude and effectively adapt the quality such as to ensure the highest possible playback quality of the video being viewed. By improving the channel utilization we also address the discrimination problem that HAS clients often suffer from, allowing us to in some cases simultaneously improve the playback quality of the video being viewed and provide the value-added service of allowing instantaneous playback of the prefetched alternative videos.

    Ort, förlag, år, upplaga, sidor
    New York, USA: Association for Computing Machinery (ACM), 2015
    Nyckelord
    HTTP-based adaptive streaming (HAS); Bandwidth-aware prefetching; Multi-video preloading; Seamless playback
    Nationell ämneskategori
    Datorsystem
    Identifikatorer
    urn:nbn:se:liu:diva-128168 (URN)10.1145/2733373.2806270 (DOI)000387861300064 ()978-1-4503-3459-4 (ISBN)
    Konferens
    ACM Multimedia 2015
    Tillgänglig från: 2016-05-20 Skapad: 2016-05-19 Senast uppdaterad: 2018-02-06
    3. BUFFEST: Predicting Buffer Conditions and Real-time Requirements of HTTP(S) Adaptive Streaming Clients
    Öppna denna publikation i ny flik eller fönster >>BUFFEST: Predicting Buffer Conditions and Real-time Requirements of HTTP(S) Adaptive Streaming Clients
    2017 (Engelska)Ingår i: MMSys’17, Proceedings of the 8th ACM on Multimedia Systems Conference, ACM , 2017, s. 76-87Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Stalls during video playback are perhaps the most important indicator of a client's viewing experience. To provide the best possible service, a proactive network operator may therefore want to know the buffer conditions of streaming clients and use this information to help avoid stalls due to empty buffers. However, estimation of clients' buffer conditions is complicated by most streaming services being rate-adaptive, and many of them also encrypted. Rate adaptation reduces the correlation between network throughput and client buffer conditions. Usage of HTTPS prevents operators from observing information related to video chunk requests, such as indications of rate adaptation or other HTTP-level information.; AB@This paper presents BUFFEST, a novel classification framework that can be used to classify and predict streaming clients' buffer conditions from both HTTP and HTTPS traffic. To illustrate the tradeoffs between prediction accuracy and the available information used by classifiers, we design and evaluate classifiers of different complexity. At the core of BUFFEST is an event-based buffer emulator module for detailed analysis of clients' buffer levels throughout a streaming session, as well as for automated training and evaluation of online packet-level classifiers. We then present example results using simple threshold-based classifiers and machine learning classifiers that only use TCP/IP packet-level information. Our results are encouraging and show that BUFFEST can distinguish streaming clients with low buffer conditions from clients with significant buffer margin during a session even when HTTPS is used.

    Ort, förlag, år, upplaga, sidor
    ACM, 2017
    Nyckelord
    Buffer condition estimation, HTTP-based adaptive streaming, HTTPS, Real-time requirements
    Nationell ämneskategori
    Data- och informationsvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-140913 (URN)10.1145/3083187.3083193 (DOI)978-1-4503-5002-0 (ISBN)
    Konferens
    8th ACM Conference on Multimedia Systems, June 20-23, 2017, Taipei, Taiwan
    Tillgänglig från: 2017-09-15 Skapad: 2017-09-15 Senast uppdaterad: 2018-02-06
    4. Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video
    Öppna denna publikation i ny flik eller fönster >>Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video
    Visa övriga...
    2013 (Engelska)Ingår i: FhMN '13 Proceedings of the 2013 ACM SIGCOMM workshop on Future human-centric multimedia networking, New York, USA: Association for Computing Machinery (ACM), 2013, s. 53-58Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

    Ort, förlag, år, upplaga, sidor
    New York, USA: Association for Computing Machinery (ACM), 2013
    Nyckelord
    HTTP-based adaptive streaming, Multi-path video, Nonlinear video, Seamless playback
    Nationell ämneskategori
    Datorsystem
    Identifikatorer
    urn:nbn:se:liu:diva-96695 (URN)10.1145/2491172.2491183 (DOI)978-1-4503-2183-9 (ISBN)
    Konferens
    ACM SIGCOMM 2013, Hong Kong, China, 12-16 August 2013
    Anmärkning

    Nominated as the Best Paper in the 2013 ACM SIGCOMM workshop on Future human-centric Multimedia Networking (FhMN)

    Tillgänglig från: 2013-08-23 Skapad: 2013-08-23 Senast uppdaterad: 2018-02-06Bibliografiskt granskad
    5. Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming
    Öppna denna publikation i ny flik eller fönster >>Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming
    Visa övriga...
    2014 (Engelska)Ingår i: MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia, Association for Computing Machinery, Inc , 2014, s. 317-326Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Interactive branched video that allows users to select their own paths through the video, provides creative content designers with great personalization opportunities; however, such video also introduces significant new challenges for the system developer. For example, without careful prefetching and buffer management, the use of multiple alternative playback paths can easily result in playback interruptions. In this paper, we present a full implementation of an interactive branched video player using HTTP-based Adaptive Streaming (HAS) that provides seamless playback even when the users defer their branch path choices to the last possible moment. Our design includes optimized prefetching policies that we derive under a simple optimization framework, effective buffer management of prefetched data, and the use of parallel TCP connections to achieve efficient buffer workahead. Through performance evaluation under a wide range of scenarios, we show that our optimized policies can effectively prefetch data of carefully selected qualities along multiple alternative paths such as to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.

    Ort, förlag, år, upplaga, sidor
    Association for Computing Machinery, Inc, 2014
    Serie
    MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia
    Nyckelord
    Branched video; HTTP-based Adaptive Streaming (HAS); Multipath/nonlinear streaming; Seamless playback
    Nationell ämneskategori
    Data- och informationsvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-116449 (URN)10.1145/2647868.2654951 (DOI)2-s2.0-84913597570 (Scopus ID)9781450330633 (ISBN)
    Konferens
    2014 ACM Conference on Multimedia, MM 2014
    Tillgänglig från: 2015-03-27 Skapad: 2015-03-26 Senast uppdaterad: 2018-02-06
    6. Optimized Adaptive Streaming of Multi-video Stream Bundles
    Öppna denna publikation i ny flik eller fönster >>Optimized Adaptive Streaming of Multi-video Stream Bundles
    2017 (Engelska)Ingår i: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 19, nr 7, s. 1637-1653Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In contrast to traditional video, multi-view video streaming allows viewers to interactively switch among multiple perspectives provided by different cameras. One approach to achieve such a service is to encode the video from all of the cameras into a single stream, but this has the disadvantage that only a portion of the received video data will be used, namely that required for the selected view at each point in time. In this paper, we introduce the concept of a multi-video stream bundle that consists of multiple parallel video streams that are synchronized in time, each providing the video from a different camera capturing the same event or movie. For delivery we leverage the adaptive features and time-based chunking of HTTP-based adaptive streaming, but now employing adaptation in both content and rate. Users are able to change their viewpoint on-demand and the client player adapts the rate at which data are retrieved from each stream based on the users current view, the probabilities of switching to other views, and the users current bandwidth conditions. A crucial component of such a system is the prefetching policy. For this we present an optimization model as well as a simpler heuristic that can balance the playback quality and the probability of playback interruptions. After analytically and numerically characterizing the optimal solution, we present a prototype implementation and sample results. Our prefetching and buffer management solution is shown to provide close to seamless playback switching when there is sufficient bandwidth to prefetch the parallel streams.

    Ort, förlag, år, upplaga, sidor
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
    Nyckelord
    HTTP-based adaptive streaming (HAS); multi-view video streaming; multi-video stream bundles; optimized prefetching; seamless stream switching
    Nationell ämneskategori
    Telekommunikation
    Identifikatorer
    urn:nbn:se:liu:diva-139270 (URN)10.1109/TMM.2017.2673412 (DOI)000404061800019 ()
    Anmärkning

    Funding Agencies|Swedish Research Council (VR); Center for Industrial Information Technology (CENIIT); Natural Sciences and Engineering Research Council of Canada

    Tillgänglig från: 2017-07-07 Skapad: 2017-07-07 Senast uppdaterad: 2018-02-06
  • 202.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Bergström, Patrik
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Empowering the Creative User: Personalized HTTP-based Adaptive Streaming of Multi-path Nonlinear Video2013Ingår i: Computer communication review, ISSN 0146-4833, E-ISSN 1943-5819, Vol. 43, nr 4, s. 591-596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

  • 203.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Bergström, Patrik
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eager, Derek
    University of Saskatchewan.
    Mahanti, Anirban
    NICTA, Sydney, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Empowering the creative user: personalized HTTP-based adaptive streaming of multi-path nonlinear video2013Ingår i: FhMN '13 Proceedings of the 2013 ACM SIGCOMM workshop on Future human-centric multimedia networking, New York, USA: Association for Computing Machinery (ACM), 2013, s. 53-58Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the design, implementation, and validation of a novel system that supports streaming and playout of personalized, multi-path, nonlinear video. In contrast to regular video, in which the file content is played sequentially, our design allows multiple nonlinear video sequences of the underlying (linear) video to be stitched together and played in any personalized order, and clients can be provided multiple path choices. The design combines the ideas of HTTP-based adaptive streaming (HAS) and multi-path nonlinear video. Personalization of the content is achieved with the use of a customized metafile, which is downloaded separately from the underlying media and the manifest file that defines the HAS structure. An extension to the user interface allows path choices to be presented to and made by the user. Novel buffer management and prefetching policies are used to ensure seamless uninterrupted playback regardless of client path choices, even under scenarios in which clients defer their choices until the last possible moment. Our solution allows creative home users to easily create their own multi-path nonlinear video, opening the door to an endless possibility of new opportunities and media forms.

  • 204.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eager, D.
    University of of Saskatchewan, Canada.
    Mahanti, A.
    NICTA, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Quality-adaptive prefetching for interactive branched video using HTTP-based Adaptive Streaming2014Ingår i: MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia, Association for Computing Machinery, Inc , 2014, s. 317-326Konferensbidrag (Refereegranskat)
    Abstract [en]

    Interactive branched video that allows users to select their own paths through the video, provides creative content designers with great personalization opportunities; however, such video also introduces significant new challenges for the system developer. For example, without careful prefetching and buffer management, the use of multiple alternative playback paths can easily result in playback interruptions. In this paper, we present a full implementation of an interactive branched video player using HTTP-based Adaptive Streaming (HAS) that provides seamless playback even when the users defer their branch path choices to the last possible moment. Our design includes optimized prefetching policies that we derive under a simple optimization framework, effective buffer management of prefetched data, and the use of parallel TCP connections to achieve efficient buffer workahead. Through performance evaluation under a wide range of scenarios, we show that our optimized policies can effectively prefetch data of carefully selected qualities along multiple alternative paths such as to ensure seamless playback, offering users a pleasant viewing experience without playback interruptions.

  • 205.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Bandwidth-aware Prefetching for Proactive Multi-video Preloading and Improved HAS Performance2015Ingår i: Proceedings of the ACM International Conference on Multimedia (ACM Multimedia), New York, USA: Association for Computing Machinery (ACM), 2015, s. 551-560Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper considers the problem of providing users playing one streaming video the option of instantaneous and seamless playback of alternative videos. Recommendation systems can easily provide a list of alternative videos, but there is little research on how to best eliminate the startup time for these alternative videos. The problem is motivated by services that want to retain increasingly impatient users, who frequently watch the beginning of multiple videos, before viewing a video to the end. We present the design, implementation, and evaluation of an HTTP-based Adaptive Streaming (HAS) solution that provides careful prefetching and buffer management. We also present the design and evaluation of three fundamental policy classes that provide different tradeoffs between how aggressively new alternative videos are prefetched versus the importance of ensuring high playback quality. We show that our solution allows us to reduce the startup times of alternative videos by an order of magnitude and effectively adapt the quality such as to ensure the highest possible playback quality of the video being viewed. By improving the channel utilization we also address the discrimination problem that HAS clients often suffer from, allowing us to in some cases simultaneously improve the playback quality of the video being viewed and provide the value-added service of allowing instantaneous playback of the prefetched alternative videos.

  • 206.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Eager, Derek
    University of Saskatchewan, Canada.
    Mahanti, Anirban
    NICTA, Australia.
    Shahmehri, Nahid
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Helping Hand or Hidden Hurdle: Proxy-assisted HTTP-based Adaptive Streaming Performance2013Ingår i: Modeling, Analysis & Simulation of Computer and Telecommunication Systems (MASCOTS), 2013 IEEE 21st International Symposium, IEEE , 2013, s. 182-191Konferensbidrag (Refereegranskat)
    Abstract [en]

    HTTP-based Adaptive Streaming (HAS) has become a widely-used video delivery technology. Use of HTTP enables relatively easy firewall/NAT traversal and content caching. While caching is an important aspect of HAS, there is not much public research on the performance impact proxies and their policies have on HAS. In this paper we build an experimental framework using open source Squid proxies and the most recent Open Source Media Framework (OSMF). A range of content-aware policies can be implemented in the proxies and tested, while the player software can be instrumented to measure performance as seen at the client. Using this framework, the paper makes three main contributions. First, we present a scenario-based performance evaluation of the latest version of the OSMF player. Second, we quantify the benefits using different proxy-assisted solutions, including basic best effort policies and more advanced content quality aware prefetching policies. Finally, we present and evaluate a cooperative framework in which clients and proxies share information to improve performance. In general, the bottleneck location and network conditions play central roles in which policy choices are most advantageous, as they significantly impact the relative performance differences between policy classes. We conclude that careful design and policy selection is important when trying to enhance HAS performance using proxy assistance.

  • 207.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Halepovic, Emir
    AT&T Labs, USA.
    Petajan, Eric
    AT&T Labs, USA.
    BUFFEST: Predicting Buffer Conditions and Real-time Requirements of HTTP(S) Adaptive Streaming Clients2017Ingår i: MMSys’17, Proceedings of the 8th ACM on Multimedia Systems Conference, ACM , 2017, s. 76-87Konferensbidrag (Refereegranskat)
    Abstract [en]

    Stalls during video playback are perhaps the most important indicator of a client's viewing experience. To provide the best possible service, a proactive network operator may therefore want to know the buffer conditions of streaming clients and use this information to help avoid stalls due to empty buffers. However, estimation of clients' buffer conditions is complicated by most streaming services being rate-adaptive, and many of them also encrypted. Rate adaptation reduces the correlation between network throughput and client buffer conditions. Usage of HTTPS prevents operators from observing information related to video chunk requests, such as indications of rate adaptation or other HTTP-level information.; AB@This paper presents BUFFEST, a novel classification framework that can be used to classify and predict streaming clients' buffer conditions from both HTTP and HTTPS traffic. To illustrate the tradeoffs between prediction accuracy and the available information used by classifiers, we design and evaluate classifiers of different complexity. At the core of BUFFEST is an event-based buffer emulator module for detailed analysis of clients' buffer levels throughout a streaming session, as well as for automated training and evaluation of online packet-level classifiers. We then present example results using simple threshold-based classifiers and machine learning classifiers that only use TCP/IP packet-level information. Our results are encouraging and show that BUFFEST can distinguish streaming clients with low buffer conditions from clients with significant buffer margin during a session even when HTTPS is used.

  • 208.
    Kumar, Pardeep
    et al.
    University of Oxford, England.
    Braeken, An
    Vrije University of Brussel, Belgium.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten. ITMO University, Russia.
    Iinatti, Jari
    University of Oulu, Finland.
    Hoai Ha, Phuong
    University of Tromso, Norway.
    Anonymous Secure Framework in Connected Smart Home Environments2017Ingår i: IEEE Transactions on Information Forensics and Security, ISSN 1556-6013, E-ISSN 1556-6021, Vol. 12, nr 4, s. 968-979Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The smart home is an environment, where heterogeneous electronic devices and appliances are networked together to provide smart services in a ubiquitous manner to the individuals. As the homes become smarter, more complex, and technology dependent, the need for an adequate security mechanism with minimum individuals intervention is growing. The recent serious security attacks have shown how the Internet-enabled smart homes can be turned into very dangerous spots for various ill intentions, and thus lead the privacy concerns for the individuals. For instance, an eavesdropper is able to derive the identity of a particular device/appliance via public channels that can be used to infer in the life pattern of an individual within the home area network. This paper proposes an anonymous secure framework (ASF) in connected smart home environments, using solely lightweight operations. The proposed framework in this paper provides efficient authentication and key agreement, and enables devices (identity and data) anonymity and unlinkability. One-time session key progression regularly renews the session key for the smart devices and dilutes the risk of using a compromised session key in the ASF. It is demonstrated that computation complexity of the proposed framework is low as compared with the existing schemes, while security has been significantly improved.

  • 209.
    Kumar, Pardeep
    et al.
    UiT Arctic University of Norway, Norway.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten. ITMO University, Russia.
    Iinatti, Jari
    University of Oulu, Finland.
    Sain, Mangal
    Dongseo University, South Korea.
    Ha, Phuong H.
    UiT Arctic University of Norway, Norway.
    Access Control Protocol With Node Privacy in Wireless Sensor Networks2016Ingår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, nr 22, s. 8142-8150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For preventing malicious nodes joining wireless sensor networks (WSNs), an access control mechanism is necessary for the trustworthy cooperation between the nodes. In addition to access control, recently, privacy has been an important topic regarding how to achieve privacy without disclosing the real identity of communicating entities in the WSNs. Based on elliptic curve cryptography, in this paper, we present an access control protocol with node privacy (called ACP) for the WSN. The proposed scheme not only accomplishes the node authentication but also provides the identity privacy (i.e., source to destination and vice-versa) for the communicating entities. Compared with the current state of the art, the proposed solution can defend actively against attacks. The efficacy and the efficiency of the proposed ACP are confirmed through the test bed analysis and performance evaluations.

  • 210.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A framework for session-based ontology alignment2011Ingår i: Proceedings of the 6th International Workshop on Ontology Matching, CEUR Workshop Proceedings , 2011, s. 238-239Konferensbidrag (Refereegranskat)
    Abstract [en]

    [No abstract available]

  • 211.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Advances in Secure and Networked Information Systems – The ADIT Perspective: Festschrift in honor of professor NAHID SHAHMEHRI2012Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
    Abstract [en]

    This book contains contributions by current and former colleagues and PhD students of professor Nahid Shahmehri in celebration of her 60th birthday. Although it would be difficult to cover the full range of her academic contributions, we have at least been able to hint the importance and the breadth of her work. We have chosen the title ‘Advances in Secure and Networked Information Systems - The ADIT Perspective’ as many of the contributions of Nahid and her group have been in these areas, given a fairly broad interpretation of “networked information systems”. In this collection we have gathered both republications of past work as well as newly written articles.

     

  • 212.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Extending Standard Description Logics1994Ingår i: Proceedings of the International Workshop on Description Logics, 1994, s. 42-44Konferensbidrag (Refereegranskat)
  • 213.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Introduction to Description Logics2001Ingår i: Ontologies and Search - Proceedings of the 2nd OntoQuery Workshop, 2001, s. 53-56Konferensbidrag (Refereegranskat)
  • 214.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Filosofiska fakulteten.
    Ontologies in Bioinformatics and Systems Biology2004Ingår i: Artificial Intelligence Methods and Tools for Systems Biology / [ed] Werner Dubitzky and Francisco Azuaje, Springer Science+Business Media B.V., 2004, 5, s. 129-145Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Ontologies are being used in bioinformatics and systems biology, among others, for communication between people and organizations, as the basis for interoperability between systems, and as query models and indexes to repositories of information. In this chapter we give a background of the area and provide a state of the art overview. We present different possible definitions of ontology, examples of bio-ontologies and their use, formalisms that can be used to represent ontologies as well as tools that support the different stages in the life cycle of an ontology.

  • 215.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Part-Whole Reasoning in an Object-Centered Framework2000Bok (Refereegranskat)
    Abstract [en]

    In this book, the author develops an object-centered framework with specialized support of the part-of relation based on description logics. These logics are a family of object-centered knowledge representation languages tailored for describing knowledge about concepts and is-a hierarchies of these concepts. In addition to the representation and reasoning facilities provided by description logics for is-a, representation and reasoning facilities are introduced for part-of. Finally, the feasibility and the usefulness of the approach is demonstrated by applying the framework to various areas including domain modeling, agent-oriented scenarios, document management and retrieval, and composite concept learning.

  • 216.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Semantic Web, Ontologies and Linked Data2014Ingår i: Comprehensive Biomedical Physics: Volume 6: Bioinformatics / [ed] Brahme (ed in chief), Persson, (ed), Amsterdam: Elsevier, 2014, s. 67-76Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Researchers in various areas in the life sciences use biomedical data sources and tools for their research. However, with the explosion of the amountof available data sources and tools, researchers also face the difficulties of finding and retrieving relevant information and tools as well as integratinginformation from different sources. The vision of the Semantic Web alleviates these difficulties. In this chapter, we introduce the Semantic Web anddiscuss steps that have been taken toward this vision. We discuss ontologies as a key technology as well as the recent development of Linked Data. Further, for each of these, we list issues for future research.

  • 217.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Towards a semantic web for bioinformatics using ontology-based annotation2005Ingår i: 14th IEEE International Workshops on Enabling Technologies: Infrastructures for Collaborative Enterprises,2005, Institute of Electrical and Electronics Engineers (IEEE), 2005, s. 3-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nowadays, biologists use biological data sources and tools to find relevant information for their research. However, with the explosion of the amount of online accessible data and tools, finding the relevant sources and retrieving the relevant information is not an easy task. Further, often information from different sources needs to be integrated. The vision of a Semantic Web alleviates these difficulties. The Semantic Web is an extension of the current Web in which information is given a well-defined meaning by annotating Web content with ontology terms. In this paper we discuss the Semantic Web vision and focus on an important technology, ontologies, that is needed to make this vision happen.

  • 218.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Delin, Anna
    School of Science and Engineering (SCI) at the Royal Institute of Technology, KTH, Sweden.
    Li, Huanyu
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Big Semantic Data Processing in the Materials Design Domain2018Ingår i: Encyclopedia of Big Data Technologies / [ed] Sherif Sakr and Albert Zomaya, Cham: Springer, 2018Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    To speed up the progress in the field of materials design, a number of challenges related to big data need to be addressed. This entry discusses these challenges and shows the semantic technologies that alleviate the problems related to variety, variability, and veracity.

  • 219.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Borgida, AlexRutgers University, NJ, USA.Lenzerini, MaurizioUniversita degli Studi di Roma "La Sapienza", Italy..Möller, RalfUniversity of Hamburg, Germany.Patel-Schneider, PeterBell Labs Research, NJ, USA.
    Proceedings of the 1999 International Workshop on Description Logics1999Proceedings (redaktörskap) (Refereegranskat)
    Abstract [en]

    The International Workshop on Description Logics was held in Linköping Sweden from July to August. It was an a affiliate event with the Sixteenth International Joint Conference on Articial Intelligence IJCAI Stockholm July 31 - August 6 and with the Sixth International Workshop on Knowledge Representation meets Databases KRDB Linköoping July 29-30.

    The workshop was organized in sessions on theoretical advances in de scription logics (2 sessions), applications of description logics (2 sessions), description logic systems (2 sessions) and extensions of description logics (1 session). Further there was a joint session with the Sixth International Workshop on Knowledge Representation Meets Databases. There were two invited talks Natasha Alechina gave a tutorial on logics for semi-structured data Robert MacGregor and Deborah McGuinness gave a presentation on DARPAs High Performance Knowledge Base project.

    The workshop was sponsored by the Swedish Research Council for Engineering Sciences TFR Telefonaktiebolaget LM Ericssons Stiftelse for främjande av elektroteknisk forskning, Linköpings kommun, Erda AB andthe Laboratory for Intelligent Information Systems, Linköpings universitet.Thanks go also to Lotta Nissen Yelena Turetskaya and a number of studentsfor their contribution to the organization.

  • 220.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Get my pizza right: Repairing missing is-a relations in ALC ontologies2012Ingår i: Second Joint International Semantic Technology Conference, Springer Berlin/Heidelberg, 2012, s. 17-32Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the increased use of ontologies in semantically-enabled applications, the issue of debugging defects in ontologies has become increasingly important. These defects can lead to wrong or incomplete results for the applications. Debugging consists of the phases of detection and repairing. In this paper we focus on the repairing phase of a particular kind of defects, i.e. the missing relations in the is-a hierarchy. Previous work has dealt with the case of taxonomies. In this work we extend the scope to deal with ALC ontologies that can be represented using acyclic terminologies. We present algorithms and discuss a system.

  • 221.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Anslow, Craig
    Middlesex University, London, UK.
    Visualization for Ontology Evolution2016Ingår i: VOILA 2016 Visualization and Interaction for Ontologies and Linked Data: Proceedings of the 2nd  International Workshop on Visualization and Interaction for Ontologies and Linked Data / [ed] Valentina Ivanova; Patrick Lambrix; Steffen Lohmann; Catia Pesquita, Rheinisch-Westfaelische Technische Hochschule Aachen University , 2016, s. 54-67Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the challenges for the ontology engineering community is theuser involvement in the engineering process. Ontologies are not static entities andthere is a demand for tools to support the user during the ontology evolution pro-cess. This paper aims to provide a set of functionality requirements for ontologyevolution systems, with a particular focus on the visualization of the ontologies,their versions and information needed for ontology evolution tasks. Further, wereview the current state of the art in ontology evolution systems with respect tothe requirements and the visualization. We also view ontologies as software anddiscuss approaches from the software visualization area that could be used forontology evolution visualization.

  • 222.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Edberg, Anna
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Evaluation of ontology merging tools2003Ingår i: Pacific Symposium on Biocomputing, World Scientific , 2003, s. 589-600Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ontologies are being used nowadays in many areas, including bioinformatics. One of the issues in ontology research is the aligning and merging of ontologies. Tools have been developed for ontology merging, but they have not been evaluated for their use in bioinformatics. In this paper we evaluate two of the most well-known ontology merging tools with a bioinformatics perspective. As test ontologies we have used Gene Ontology and Signal-Ontology.

  • 223.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Edberg, Anna
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Manis, Carolyn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Tan, He
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Merging DAML+OIL bio-ontologies2003Ingår i: International workshop on description logics, 2003Konferensbidrag (Refereegranskat)
  • 224.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Göthe Lundgren, Maud
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Kamkar, Mariam
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Computer science as an integrated part of engineering education1997Ingår i: Proceedings of the ACM SIGCSE/SIGCUE Conference on Integrating Technology into Computer Science Education, 1997, s. 151-Konferensbidrag (Refereegranskat)
  • 225.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Habbouche, Manal
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Perez, Marta
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Evaluation of ontology development tools for bioinformatics2003Ingår i: Bioinformatics, ISSN 1367-4803, E-ISSN 1367-4811, Vol. 19, nr 12, s. 1564-1571Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ontologies are being used nowadays in many areas, including bioinformatics. To assist users in developing and maintaining ontologies a number of tools have been developed. In this paper we compare four such tools, Protégé-2000, Chimaera, DAG-Edit and OilEd. As test ontologies we have used ontologies from the Gene Ontology Consortium. No system is preferred in all situations, but each system has its own strengths and weaknesses.

  • 226.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Habbouche, Manal
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Perez, Marta
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Evaluation of ontology development tools for bioinformatics2005Ingår i: Yearbook of the International Medical Informatics Association 2005 / [ed] Haux R, Kulikowski C, Stuttgart: Schattauer Verlagsgesellschaft mbH , 2005, s. 547-554Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Ontologies are being used nowadays in many areas, including bioinformatics. To assist users in developing and maintaining ontologies a number of tools have been developed. In this paper we compare four such tools, Protégé-2000, Chimaera, DAG-Edit and OilEd. As test ontologies we have used ontologies from the Gene Ontology Consortium. No system is preferred in all situations, but each system has its own strengths and weaknesses.

  • 227.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Hyvönen, EeroAalto University, Finland.Blomqvist, EvaLinköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.Presutti, ValentinaSTLab ISTC-CNR, Italy.Qi, GuilinSoutheast University, China.Sattler, UliUniversity of Manchester, UK.Ding, YingIndiana University Bloomingtom, USA.Ghidini, ChiaraFondazione Bruno Kessler, Italy.
    Knowledge Engineering and Knowledge Management: EKAW 2014 Satellite Events, VISUAL, EKM1, and ARCOE-Logic, Linköping, Sweden, November 24-28, 2014. Revised Selected Papers2015Proceedings (redaktörskap) (Refereegranskat)
    Abstract [en]

    This volume contains the Satellite Events proceedings of the 19th International Conference on Knowledge Engineering and Knowledge Management (EKAW 2014), held in Linköping, Sweden, during November 24–28, 2014. This was the first EKAW conference in a Nordic country. It was concerned with all aspects of eliciting, acquiring, modeling, and managing knowledge, the construction of knowledge-intensive systems and services for the Semantic Web, knowledge management, e-business, natural language processing, intelligent information integration, personal digital assistance systems, and a variety of other related topics. The special focus of EKAW2014 was Diversity.

  • 228.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A unified approach for debugging is-a structure and mappings in networked taxonomies2013Ingår i: Journal of Biomedical Semantics, ISSN 2041-1480, E-ISSN 2041-1480, Vol. 4, artikel-id 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    With the increased use of ontologies and ontology mappings in semantically-enabled applications such as ontology-based search and data integration, the issue of detecting and repairing defects in ontologies and ontology mappings has become increasingly important. These defects can lead to wrong or incomplete results for the applications.

    Results

    We propose a unified framework for debugging the is-a structure of and mappings between taxonomies, the most used kind of ontologies. We present theory and algorithms as well as an implemented system RepOSE, that supports a domain expert in detecting and repairing missing and wrong is-a relations and mappings. We also discuss two experiments performed by domain experts: an experiment on the Anatomy ontologies from the Ontology Alignment Evaluation Initiative, and a debugging session for the Swedish National Food Agency.

    Conclusions

    Semantically-enabled applications need high quality ontologies and ontology mappings. One key aspect is the detection and removal of defects in the ontologies and ontology mappings. Our system RepOSE provides an environment that supports domain experts to deal with this issue. We have shown the usefulness of the approach in two experiments by detecting and repairing circa 200 and 30 defects, respectively.

  • 229.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ivanova, Valentina
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Dragisic, Zlatan
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Contributions of LiU/ADIT to Debugging Ontologies and Ontology Mappings2012Ingår i: Advances in secure and networked information systems: the ADIT perspective ; Festschrift in honor of professor Nahid Shahmehri / [ed] Patrick Lambrix, Linköping: Linköping University Electronic Press, 2012, s. 109-120Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This book contains contributions by current and former colleagues and PhD students of professor Nahid Shahmehri in celebration of her 60th birthday. Although it would be difficult to cover the full range of her academic contributions, we have at least been able to hint the importance and the breadth of her work. We have chosen the title ‘Advances in Secure and Networked Information Systems - The ADIT Perspective’ as many of the contributions of Nahid and her group have been in these areas, given a fairly broad interpretation of “networked information systems”. In this collection we have gathered both republications of past work as well as newly written articles.

  • 230.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Kaliyaperumal, Rajaram
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A Session-based Approach for Aligning Large Ontologies: Extended Semantic Web Conference2013Ingår i: The Semantic Web: Semantics and Big Data: 10th International Conference, ESWC 2013, Montpellier, France, May 26-30, 2013. Proceedings / [ed] Philipp Cimiano, Oscar Corcho, Valentina Presutti, Laura Hollink, Sebastian Rudolph, Springer Berlin/Heidelberg, 2013, s. 46-60Konferensbidrag (Refereegranskat)
    Abstract [en]

    There are a number of challenges that need to be addressed when aligning large ontologies. Previous work has pointed out scalability and efficiency of matching techniques, matching with background knowledge, support for matcher selection, combination and tuning, and user involvement as major requirements. In this paper we address these challenges. Our first contribution is an ontology alignment framework that enables solutions to each of the challenges. This is achieved by introducing different kinds of interruptable sessions. The framework allows partial computations for generating mapping suggestions, partial validations of mappings suggestions and use of validation decisions in (re)computation of mapping suggestions and the recommendation of alignment strategies to use. Further, we describe an implemented system providing solutions to each of the challenges and show through experiments the advantages of the session-based approach.

  • 231.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten. Swedish e-Science Research Centre, Linköping University, Linköping, Sweden.
    Kaliyaperumal, Rajaram
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    A session-based ontology alignment approach enabling user involvement2017Ingår i: Semantic Web, ISSN 1570-0844, E-ISSN 2210-4968, Vol. 8, nr 2, s. 225-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the current challenges in ontology alignment is the user involvement in the alignment process. To obtain high-quality alignments user involvement is needed for validation of matching results as well as in the mapping generation process. Further, there is a need for supporting the user in tasks such as matcher selection, combination and tuning.

    In this paper we introduce a conceptual ontology alignment framework that enables user involvement in a natural way. This is achieved by introducing different kinds of interruptible sessions. The framework allows partial computations for generating mapping suggestions, partial validations of mapping suggestions, recommendations for alignment strategies as well as the use of validation decisions in the (re-)computation of mapping suggestions and the recommendations. Further, we show the feasibility of the approach by implementing a session-based version of an existing system. We also show through experiments the advantages of our approach for ontology alignment as well as for evaluation of ontology alignment strategies.

  • 232.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Kaliyaperumal, Rajaram
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Contributions of LiU/ADIT to Ontology Alignment2012Ingår i: Advances in secure and networked information systems: the ADIT perspective ; Festschrift in honor of professor Nahid Shahmehri / [ed] Patrick Lambrix, Linköping: Linköping University Electronic Press, 2012, s. 97-108Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This book contains contributions by current and former colleagues and PhD students of professor Nahid Shahmehri in celebration of her 60th birthday. Although it would be difficult to cover the full range of her academic contributions, we have at least been able to hint the importance and the breadth of her work. We have chosen the title ‘Advances in Secure and Networked Information Systems - The ADIT Perspective’ as many of the contributions of Nahid and her group have been in these areas, given a fairly broad interpretation of “networked information systems”. In this collection we have gathered both republications of past work as well as newly written articles.

  • 233.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Kamkar, Mariam
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Computer Science as an Integrated Part of Engineering Education1998Ingår i: Proceedings of the Third ACM SIGCSE/SIGCUE Conference on Integrating Technology into Computer Science Education, 1998, s. 153-156Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Information Technology curriculum at Linköping University has as goal to form engineers with an integrated view of engineering. The teaching philosophy in this curriculum is Problem-Based Learning. The education in each term is organised in a number of themes where topics from different disciplines are integrated. We describe a particular term in the Information Technology curriculum as an example of the approach and the integration of computer science teaching with the teaching of other disciplines. An important advantage of the approach is that the students discover interactions between different disciplines and view the different topics as naturally connected. Also, the students seem to have a better understanding of the topics and are better motivated. Further, they obtain improved communication and co-operation skills. Another advantage is that the approach is appreciated by our female students, which has led to a higher percentage of female students in this curriculum compared to our other computer science curricula.

  • 234.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Kemp, GrahamChalmers University of Technology.
    Proceedings of the Seventh International Conference on Data Integration in the Life Sciences2010Proceedings (redaktörskap) (Refereegranskat)
  • 235.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Larocchia, Pierpaolo
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Learning Composite Concepts1998Ingår i: Proceedings of the International Workshop on Description Logics, 1998, s. 147-152Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes a framework to learn concepts from different kinds of observations. We define a language to describe meta-concepts, that represent the sets of possible concepts that can be the result of learning given a set of observations. The kinds of observations that we have studied are subsumption, membership and part-of. We exemplify the framework by showing how composite concepts can be learned in a specific description logic and we show that previous machine learning approaches in description logics can be reformulated in our framework. 1 Introduction In [LM96] the problem of learning composite concepts was formulated in the framework of description logics. Description logics are restricted variants of firstorder logic providing a form of logical bias that dates back to semantic networks. Some recent work investigates concept learning in the context of description logics

    Learning Composite Concepts.. Available from: http://www.researchgate.net/publication/220956947_Learning_Composite_Concepts [accessed Jul 1, 2015].

  • 236.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A System for Debugging is-a Structure in Networked Taxonomies2011Ingår i: Demo proceeding of the 10th International Semantic Web Conference, 2011Konferensbidrag (Refereegranskat)
  • 237.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Debugging is-a structure in networked taxonomies,2011Ingår i: Proceedings of the Fourth International Workshop on Semantic Web Applications and Tools for Life Sciences, Association for Computing Machinery (ACM), 2011, s. 58-65Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the proliferation of ontologies and their use in semantically-enabled applications, the issue of finding and repairing defects in ontologies has become increasingly important. In this paper we address the problem of defects in the is-a structure of taxonomies, the currently most frequently used kind of ontologies. We deal with both missing is-a relations as well as existing wrong is-a relations. The context of our study is a taxonomy network consisting of taxonomies networked by correct mappings. We propose a semi-automatic ontology debugging approach, which supports domain experts in debugging the is-a structure in taxonomies. We develop algorithms to detect and repair wrong and missing is-a relations. Further, we discuss an implemented system, RepOSE, and an experiment on real-world ontologies.

  • 238.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Debugging the missing is-a structure within taxonomies networked by partial reference alignments2013Ingår i: Data & Knowledge Engineering, ISSN 0169-023X, E-ISSN 1872-6933, Vol. 86, s. 179-205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the proliferation of ontologies and their use in semantically-enabled applications, the issue of finding and repairing defects in ontologies has become increasingly important. Current work mostly targets debugging semantic defects in ontologies. In our work, we focus on another kind of severe defects, modeling defects, which require domain knowledge to detect and resolve. In particular, we debug the missing structural relations (is-a hierarchy) in a fundamental kind of ontologies, i.e. taxonomies. The context of our study is an ontology network consisting of several taxonomies networked by partial reference alignments. We use the ontology network as domain knowledge to detect the missing is-a relations in these ontologies. We also propose algorithms to generate possible repairing actions, rank missing is-a relations, recommend and execute repairing actions. Further, we discuss an implemented system RepOSE and experiments on ontologies of the Ontology Alignment Evaluation Initiative and the Finnish Ontology Library Service.

  • 239.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Using partial reference alignments to align ontologies2009Ingår i: Proceedings of the 6th European Semantic Web Conference - ESWC09, Springer Berlin/Heidelberg, 2009, Vol. 5554 LNCS, s. 188-202Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In different areas ontologies have been developed and many of these ontologies contain overlapping information. Often we would therefore want to be able to use multiple ontologies. To obtain good results, we need to find the relationships between terms in the different ontologies, i.e. we need to align them. Currently, there already exist a number of ontology alignment systems. In these systems an alignment is computed from scratch. However, recently, some situations have occurred where a partial reference alignment is available, i.e. some of the correct mappings between terms are given or have been obtained. In this paper we investigate whether and how a partial reference alignment can be used in ontology alignment. We use partial reference alignments to partition ontologies, to compute similarities between terms and to filter mapping suggestions. We test the approaches on previously developed gold standards and discuss the results.

  • 240.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Tan, He
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A system for repairing missing is-a structure in ontologies2009Ingår i: Semantic Web Applications and Tools for Life Sciences, 2009Konferensbidrag (Refereegranskat)
  • 241.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Tan, He
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Aligning anatomy ontologies in the Ontology Alignment Evaluation Initiative2009Ingår i: 25th Workshop of the Swedish Artificial Intelligence Society, 2009, s. 13-20Konferensbidrag (Refereegranskat)
  • 242.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Tan, He
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Repairing the missing is-a structure of ontologies2009Ingår i: Proceedings of the 4th Asian Semantic Web Conference - ASWC09, Springer Berlin/Heidelberg, 2009, 1, s. 76-90Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Developing ontologies is not an easy task and often the resultingontologies are not consistent or complete. Such ontologies,although often useful, also lead to problems when used insemantically-enabled applications. Wrong conclusions may bederived or valid conclusions may be missed. To deal with thisproblem we may want to repair the ontologies. Up to date most workhas been performed on finding and repairing the semantic defectssuch as unsatisfiable concepts and inconsistent ontologies. Inthis paper we tackle the problem of repairing modeling defects andin particular, the repairing of structural relations (is-ahierarchy) in the ontologies. We study the case where missing is-arelations are given. We define the notion of a structural repairand develop algorithms to compute repairing actions that wouldallow deriving the missing is-a relations in the repairedontology. Further, we define preferences between repairs. We alsolook at how we can use external knowledge to recommend repairingactions to a domain expert. Further, we discuss an implementedprototype and its use as well as an experiment using theontologies of the Anatomy track of the Ontology AlignmentEvaluation Initiative.

  • 243.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Qiang
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Tan, He
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    RepOSE: an environment for repairing missing ontological structure2009Ingår i: The Semantic Web: Fourth Asian Conference, ASWC 2009, Shanghai, China, December 6-9, 2009. Proceedings, Springer Berlin/Heidelberg, 2009, 1, s. 365-366Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Developing ontologies is not an easy task and often the resultingontologies are not consistent or complete. Such ontologies,although often useful, also lead to problems when used insemantically-enabled applications. Wrong conclusions may bederived or valid conclusions may be missed. To deal with thisproblem we may want to repair the ontologies. Up to date most workhas been performed on finding and repairing the semantic defectssuch as unsatisfiable concepts and inconsistent ontologies. Inthis paper we tackle the problem of repairing modeling defects andin particular, the repairing of structural relations (is-ahierarchy) in the ontologies. We study the case where missing is-arelations are given. We define the notion of a structural repairand develop algorithms to compute repairing actions that wouldallow deriving the missing is-a relations in the repairedontology. Further, we define preferences between repairs. We alsolook at how we can use external knowledge to recommend repairingactions to a domain expert. Further, we discuss an implementedprototype and its use as well as an experiment using theontologies of the Anatomy track of the Ontology AlignmentEvaluation Initiative.

  • 244.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Maleki, Jalal
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska högskolan.
    Learning composite concepts in description logics: A first step1996Ingår i: Foundations of Intelligent Systems: 9th International Symposium, ISMIS '96 Zakopane, Poland, June 9–13, 1996 Proceedings / [ed] Zbigniew W. Raś, Maciek Michalewicz, Springer Berlin/Heidelberg, 1996, s. 68-77Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This paper proposes the use of description logics as a representational framework for learning composite concepts. Description logics are restricted variants of first-order logic providing a form of logical bias that dates back to semantic networks. Some recent work investigates concept learning in the context of these formalisms. Also, having recognized the importance of part-whole hierarchies in commonsense reasoning, researchers have started to incorporate part-of reasoning into description logics. In our approach we represent composite concepts in such a formalism. On one hand we have a relatively rich representation language with an infinite space of possible concepts. On the other hand we have special constructs for handling part-of relations that can be used in the learning algorithm to reduce the overall search space.

  • 245.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Ouchterlony, Ulla
    Linköpings universitet, Matematiska institutionen, Beräkningsvetenskap. Linköpings universitet, Tekniska högskolan.
    Integration of Psychology, Economics and Information Technology in an Engineering Curriculum1999Ingår i: Computer Science Education, ISSN 0899-3408, E-ISSN 1744-5175, Vol. 9, nr 2, s. 162-180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Engineers often work together with professionals from entirely different areas. Therefore, it is important for the engineers to understand enough of these other areas, where technology is used, to obtain good results. To this aim a term has been developed within the civil engineering curriculum in information technology at Linköpings universitet, where the students work and study together with students from the psychology and economics education programs. The information technology and economics students build companies together and perform a project. The psychology students act as consultants for the different companies. Subjects from six departments are integrated into the project. The students work and study together for different parts of the project, although the learning goals differ between the different programs. The cooperation in the project leads to a transfer of information and knowledge between the students. Experience also suggests that the students obta in a better motivation and an integrated view of technology and the other areas as a result of the integrated project. The learning method also promotes cooperation and understanding between different professional cultures.

  • 246.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Padgham, L
    Linköpings universitet, Institutionen för datavetenskap.
    A Description Logic for Composite Objects for Domain Modeling in an Agent-Oriented Application1996Ingår i: Proceedings of the International Workshop on Description Logics, 1996, s. 146-149Konferensbidrag (Refereegranskat)
  • 247.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Padgham, Lin
    Linköpings universitet, Institutionen för datavetenskap.
    Analysis of Part-of Reasoning in Description Logics for Use in a Document Management Application1995Ingår i: Proceedings of the Eighth International Symposium on Artificial Intelligence, 1995, s. 102-110Konferensbidrag (Refereegranskat)
  • 248.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Padgham, Lin
    Department of Computer Science, RMIT University, Melbourne, Vic. 3000, Australia.
    Conceptual modeling in a document management environment using part-of reasoning in description logics2000Ingår i: Data & Knowledge Engineering, ISSN 0169-023X, E-ISSN 1872-6933, Vol. 32, nr 1, s. 51-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The notion of giving support to composite objects in systems is gaining strength in a number of areas. In this paper we examine the usefulness of introducing part-of reasoning in a description logic in a document management environment. We identify key issues in both expressivity and inferencing. We define a language that allows for differentiating between different kinds of parts and definition of domains, number restrictions and ordering of parts. We identified also questions and inferences which are useful in document management. This has led us to define a part-of hierarchy for individuals and inferences concerning the assembly of composite objects.

  • 249.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Padgham, Lin
    Linköpings universitet, Institutionen för datavetenskap.
    Reasoning in Description Logics: A Document Management Application1995Ingår i: Proceedings of the International Workshop on Description Logics, 1995, s. 106-108Konferensbidrag (Refereegranskat)
  • 250.
    Lambrix, Patrick
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Padgham, Lin
    Dept. of Computer Science, RMIT University, Melbourne, Australia.
    Using Knowledge Representation for Agent World Model1998Ingår i: Proceedings International Conference on Multi Agent Systems, IEEE Computer Society, 1998, s. 443-444Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates the use of a description logic knowledge representation system, for representing and managing an agent's knowledge of the world for an intentional agent system. An existing application is represented using this mechanism, and the findings are discussed. A number of errors and/or inconsistencies were found in the original implementation using this methodology, indicating that it would be useful for consistency management. In addition there was a straight forward mapping from the domain knowledge to the knowledge representation system. An added benefit was a simplification of the plans required by the agent system.

2345678 201 - 250 av 452
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