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  • 51.
    Dubrova, Elena
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik och Inbyggda System.
    Näslund, Mats
    Ericsson AB.
    Carlsson, Gunnar
    Ericsson AB.
    Fornehed, John
    Ericsson AB.
    Smeets, Ben
    Ericsson AB.
    Two Countermeasures Against Hardware Trojans Exploiting Non-Zero Aliasing Probability of BIST2016Ingår i: Journal of Signal Processing Systems, ISSN 1939-8018, E-ISSN 1939-8115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The threat of hardware Trojans has been widely recognized by academia, industry, and government agencies. A Trojan can compromise security of a system in spite of cryptographic protection. The damage caused by a Trojan may not be limited to a business or reputation, but could have a severe impact on public safety, national economy, or national security. An extremely stealthy way of implementing hardware Trojans has been presented by Becker et al. at CHES’2012. Their work have shown that it is possible to inject a Trojan in a random number generator compliant with FIPS 140-2 and NIST SP800-90 standards by exploiting non-zero aliasing probability of Logic Built-In-Self-Test (LBIST). In this paper, we present two methods for modifying LBIST to prevent such an attack. The first method makes test patterns dependent on a configurable key which is programed into a chip after the manufacturing stage. The second method uses a remote test management system which can execute LBIST using a different set of test patterns at each test cycle.

  • 52. Ebrahimi, M.
    et al.
    Daneshtalab, M.
    Sreejesh, N. P.
    Liljeberg, P.
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS. University of Turku, Finland.
    Efficient network interface architecture for network-on-chips2009Ingår i: 2009 NORCHIP, 2009, artikel-id 5397837Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present novel network interface architecture for on-chip networks to increase memory parallelism and to improve the resource utilization. The proposed architecture exploits AXI transaction based protocol to be compatible with existing IP cores. Experimental results with synthetic test case demonstrate that the proposed architecture outperforms the conventional architecture in term of latency.

  • 53.
    Ebrahimi, Masoumeh
    et al.
    KTH.
    Weldezion, Awet Yemane
    Hangofay AB, Stockholm, Sweden..
    Daneshtalab, Masoud
    Malardalen Univ, Vasteras, Sweden..
    NoD: Network-on-Die as a Standalone NoC for Heterogeneous Many-core Systems in 2.5D ICs2017Ingår i: 2017 19TH INTERNATIONAL SYMPOSIUM ON COMPUTER ARCHITECTURE AND DIGITAL SYSTEMS (CADS), IEEE , 2017, s. 28-33Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to a high cost of 3D IC process technology, the semiconductor industry is targeting 2.5D ICs with interposer as a fast and low-cost alternative to integrate dissimilar technologies. In this paper, we propose an independent network-on-chip die, called Network-on-Die (NoD), for 2.5D ICs that operates as a communication backbone for heterogeneous many-core systems on interposer. NoD is responsible for routing packets from a source router to a destination router, and the connections between routers and cores pass through the interposer. This technique eliminates the complexity of the routing algorithms in heterogeneous systems by turning the irregular form of NoC in 2.5D ICs into a regular/optimized one in NoD. The performance evaluation is verified through RTL simulations for a heterogeneous many-core system of varying die sizes and with asymmetric shapes. We provide the theoretical justification for our simulation results.

  • 54.
    Edström, Viking
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Hallberg, Fredrik
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Human Interaction in 3D Manipulations: Can sonification improve the performance of the interaction?2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this report the effects of using sonification when performing move- ments in 3D space are explored. User studies were performed where partic- ipants had to repeatedly move their hand toward a target. Three different sonification modes were tested where the fundamental frequency, sound level and sound rate were varied respectively depending on the distance to the target. The results show that there is no statistically significant performance increase for any sonification mode. There is however an in- dication that sonification increases the interaction speed for some users. The mode which provided the greatest average performance increase was when the sound level was varied. This mode gave a 7% average speed increase over the silent control mode. However, the sound level mode has some significant drawbacks, especially the very high base volume re- quirement, which might not make it the best suited sonification mode for all applications. In the general case we instead recommend using the sonification mode that varies the sound rate, which gave a slightly lower performance gain but can be played at a lower volume due to its binary nature. 

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  • 55.
    Eklöf, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Fault-tolerance in HLA-based distributed simulations2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Successful integration of simulations within the Network-Based Defence (NBD), specifically use of simulations within Command and Control (C2) environments, enforces a number of requirements. Simulations must be reliable and be able to respond in a timely manner. Otherwise the commander will have no confidence in using simulation as a tool. An important aspect of these requirements is the provision of fault-tolerant simulations in which failures are detected and resolved in a consistent manner. Given the distributed nature of many military simulations systems, services for fault-tolerance in distributed simulations are desirable. The main architecture for distributed simulations within the military domain, the High Level Architecture (HLA), does not provide support for development of fault-tolerant simulations.

    A common approach for fault-tolerance in distributed systems is check-pointing. In this approach, states of the system are persistently stored through-out its operation. In case a failure occurs, the system is restored using a previously saved state. Given the abovementioned shortcomings of the HLA standard this thesis explores development of fault-tolerant mechanisms in the context of the HLA. More specifically, the design, implementation and evaluation of fault-tolerance mechanisms, based on check-pointing, are described and discussed.

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  • 56. Eklöf, Martin
    et al.
    Sparf, Magnus
    Moradi, Farshad
    Ayani, Rassul
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Peer-to-peer-based resource management in support of HLA-based distributed simulations2004Ingår i: Simulation (San Diego, Calif.), ISSN 0037-5497, E-ISSN 1741-3133, Vol. 80, nr 4-5, s. 181-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent years, the concept of peer-to-peer computing has gained renewed interest for sharing resources within and between organizations or individuals. This article describes a decentralized resource management system (DRMS) that uses a network of workstations for the execution and storage of high-level architecture (HLA) federations/federates in a peer-to-peer environment. The implementation of DRMS is based on the open-source project JXTA, which represents an attempt to standardize the peer-to-peer domain. DRMS is part of a Web-based simulation environment supporting collaborative design, development, and execution of HLA federations. This study evaluates the possibilities of using peer-to-peer technology for increasing the reuse and availability of simulation components within the defense modelling and simulation community. More specifically, it addresses the necessary adjustments of simulation components to conform to the requirements of the DRMS and shows that JXTA could provide the foundation for a distributed system that increases the possibilities for reusing simulation components.

  • 57.
    EKSTAM LJUSEGREN, LOVE
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    FLORÉN, MIKAEL
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Basic simulation of natural selection: A study of the evolution of artificial life in varied environments2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I det här projektet undersöktes ett sätt att simulera natur- ligt urval med sina mest grundläggande principer. För att visa hur simpla och kraftfulla evolutionära system kan va- ra, kämpade ett antal simulerade livsformer för överlevnad och utvecklades över generationer. Med detta projekt ville vi både påvisa hur enkla evolutionära system kan vara för ut- bildningsändamål, och visa potentialen hos självförbättrande algoritmer. Detta gjordes genom att ställa två frågor. Kan ett enkelt system, så som det som beskrivs i denna rapport, räcka för att producera stabila populationer och genpooler, givet tid? Och om så är fallet, kan de utvecklas till olika stabila lösningar givet olika problem, i detta fall olika mil- jöer, att ta itu med? Testmiljön var väldigt enkel; ett antal simulerade livsformer, med förmågan att producera avkom- ma med slumpmässiga mutationer, placerades i olika miljöer. Resultaten från simulationen visar att vi efter en tid får po- pulationer som är stabila i både genuppsättning och antal. De visar också att olika miljöer leder till olika genuppsätt- ningar. Från detta kan vi dra slutsatsen att ett så simpelt test som detta, kan användas för att producera både olika och stabila arter som är bättre anpassade för att överleva än tidiga generationer. 

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  • 58.
    Ekstedt, Mathias
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Lapalme, J.
    Franke, U.
    Schulte, S.
    Message from the EDOC 2018 Workshop and Demo Chairs2018Ingår i: 22nd IEEE International Enterprise Distributed Object Computing Conference Workshops, EDOCW 2018, ISSN 1541-7719, Vol. 2018-October, artikel-id 8536091Artikel i tidskrift (Refereegranskat)
  • 59.
    El-Ansary, Sameh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    A component-based P2P simulation environmentManuskript (preprint) (Övrigt vetenskapligt)
  • 60.
    El-Ansary, Sameh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    A structured P2P overlay networks primerManuskript (preprint) (Övrigt vetenskapligt)
  • 61.
    El-Ansary, Sameh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Designs and analyses in structured peer-to-peer systems2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Peer-to-Peer (P2P) computing is a recent hot topic in the areas of networking and distributed systems. Work on P2P computing was triggered by a number of ad-hoc systems that made the concept popular. Later, academic research efforts started to investigate P2P computing issues based on scientific principles. Some of that research produced a number of structured P2P systems that were collectively referred to by the term ``Distributed Hash Tables'' (DHTs). However, the research occurred in a diversified way leading to the appearance of similar concepts yet lacking a common perspective and not heavily analyzed. In this thesis we present a number of papers representing our research results in the area of structured P2P systems grouped as two sets labeled respectively ``Designs'' and ``Analyses''.

    The contribution of the first set of papers is as follows. First, we present the principle of distributed k-ary search (DKS) and argue that it serves as a framework for most of the recent P2P systems known as DHTs. That is, given the DKS framework, understanding existing DHT systems is done simply by seeing how they are instances of that framework. We argue that by perceiving systems as instances of the DKS framework, one can optimize some of them. We illustrate that by applying the framework to the Chord system, one of the most established DHT systems. Second, We show how the DKS framework helps in the design of P2P algorithms by two examples: (a) The DKS(n;k;f) system which is a system designed from the beginning on the principles of distributed k-ary search. (b) Two broadcast algorithms that take advantage of the distributed k-ary search tree.

    The contribution of the second set of papers is as follows. We account for two approaches that we used to evaluate the performance of a particular class of DHTs, namely the one adopting periodic stabilization for topology maintenance. The first approach was of an intrinsic empirical nature. In that approach, we tried to perceive a DHT as a physical system and account for its properties in a size-independent manner. The second approach was of a more analytical nature. In this approach we applied the technique of Master equations, which is a widely used technique in the analysis of natural systems. The application of the technique lead to a highly accurate description of the behavior of structured overlays.

    Additionally, the thesis contains a primer on structured P2P systems that tries to capture the main ideas that are prevailing in the field and enumerates a subset of the current hot and open research issues.

  • 62.
    El-Ansary, Sameh
    et al.
    Distributed Systems Lab, SICS-Swedish Institute of Computer Science.
    Aurell, Erik
    KTH, Tidigare Institutioner                               , Fysik.
    Brand, Per
    Distributed Systems Lab, SICS-Swedish Institute of Computer Science.
    Haridi, Seif
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Experience with a physics-style approach for the study of self properties in structured overlay networks2004Ingår i: SELF-STAR: International Workshop on Self-* Properties in Complex Information Systems, May 2004, Bertinoro, Italy, 2004Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper gives a brief summary of our experience in applying a physics-style approach for analyzing the behavior of structured overlay networks that deploy self-organization and self-repair policies. Such systems are not always simple to model analytically and simulation of scales of interest can be prohibitive. Physicists deal with scale by characterizing a system using intensive variables, i.e. variables that are size independent. The approach proved its substantial usefulness when applied to satisfiability theory and it is the hope that it can be as useful in the field of large-scale distributed systems. We report here our finding of one simple self-organization-related intensive variable, and a more complex self-repair-related intensive variable.

  • 63.
    El-Ansary, Sameh
    et al.
    Swedish Institute of Computer Science (SICS).
    Aurell, Erik
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Haridi, Seif
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    A physics-inspired performance evaluation of a structured peer-to-peer overlay network2005Ingår i: IASTED International Conference on Parallel and Distributed Computing and Networks, as part of the 23rd IASTED International Multi-Conference on Applied Informatics: Innsbruck: 15 February 2005 through 17 February 2005, 2005, s. 116-122Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the majority of structured peer-to-peer overlay networks a graph with a desirable topology is constructed. In most cases, the graph is maintained by a periodic activity performed by each node in the graph to preserve the desirable structure in face of the continuous change of the set of nodes. The interaction of the autonomous periodic activities of the nodes renders the performance analysis of such systems complex and simulation of scales of interest can be prohibitive. Physicists, however, are accustomed to dealing with scale by characterizing a system using intensive variables, i.e. variables that are size independent. The approach has proved its usefulness when applied to satisfiability theory. This work is the first attempt to apply it in the area of distributed systems. The contribution of this paper is two-fold. First, we describe a methodology to be used for analyzing the performance of large scale distributed systems. Second, we show how we applied the methodology to find an intensive variable that describe the characteristic behavior of the Chord overlay network, namely, the ratio of the magnitude of perturbation of the network (joins/failures) to the magnitude of periodic stabilization of the network.

  • 64.
    El-Ansary, Sameh
    et al.
    Distributed Systems Laboratory, SICS Swedish Institute of Computer Science.
    Aurell, Erik
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Haridi, Seif
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Physics-inspired performance evaluation of DHTsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In the majority of structured peer-to-peer overlay networks a graph with a desirable topology is constructed. In most cases, the graph is maintained by a periodic activity performed by each node in the graph to preserve the desirable structure in face of the continuous change of the set of nodes. The interaction of the autonomous periodic activities of the nodes renders the performance analysis of such systems complex and simulation of scales of interest can be prohibitive. Physicists, however, are accustomed to dealing with scale by characterizing a system using intensive variables, i.e. variables that are size independent. The approach has proved its usefulness when applied to satisfiability theory. This work is the first attempt to apply it in the area of distributed systems. The contribution of this paper is two-fold. First, we describe a methodology to be used for analyzing the performance of large scale distributed systems. Second, we show how we applied the methodology to find two intensive variables that describe the characteristic behavior of the Chord overlay network, the variables are: 1) The density of nodes in the identifier space and 2) The ratio of the magnitude of perturbation of the network (joins/failures) to the magnitude of periodic stabilization of the network.

  • 65.
    El-Ansary, Sameh
    et al.
    Swedish Institute of Computer Science (SICS).
    Haridi, Seif
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    An overview of structured P2P overlay networks2006Ingår i: Handbook on Theoretical and Algorithmic Aspects of Sensor, Ad Hoc Wireless, and Peer-to-Peer Networks / [ed] Jie Wu, Auerbach Publications , 2006Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 66.
    El-Ansary, Sameh
    et al.
    Distributed Systems Laboratory, SICS Swedish Institute of Computer Science.
    Krishnamurthy, Supriya
    Distributed Systems Laboratory, SICS Swedish Institute of Computer Science.
    Aurell, Erik
    KTH, Tidigare Institutioner                               , Fysik.
    Haridi, Seif
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    An Analytical Study of Consistency and Performance of DHTs under Churn2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, we present a complete analytical study of dynamic membership (aka churn) in structured peer-to-peer networks. We use a master-equation-based approach, which is used traditionally in non-equilibrium statistical mechanics to describe steady-state or transient phenomena. We demonstrate that this methodology is infact also well suited to describing structured overlay networks by an application to the Chord system. For any rate of churn and stabilization rates, and any system size, we accurately account for the functional form of: the distribution of inter-node distances, the probability of network disconnection, the fraction of failed or incorrect successor and finger pointers and show how we can use these quantities to predict both the performance and consistency of lookups under churn. Additionally, we also discuss how churn may actually be of different 'types' and the implications this will have for structured overlays in general. All theoretical predictions match simulation results to a high extent. The analysis includes details that are applicable to a generic structured overlay deploying a ring as well as Chord-specific details that can act as guidelines for analyzing other systems.

  • 67.
    El-Ansary, Sameh
    et al.
    Distributed Systems Laboratory, SICS Swedish Institute of Computer Science.
    Krishnamurthy, Supriya
    Distributed Systems Laboratory, SICS Swedish Institute of Computer Science.
    Aurell, Erik
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Haridi, Seif
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Analytical study of consistency and performance of DHTs under churnManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, we present a complete analytical study of dynamic membership (aka churn) in structured peer-to-peer networks. We use a master-equation-based approach, which is used traditionally in non-equilibrium statistical mechanics to describe steady-state or transient phenomena. We demonstrate that this methodology is infact also well suited to describing structured overlay networks by an application to the Chord system. For any rate of churn and stabilization rates, and any system size, we accurately account for the functional form of: the distribution of inter-node distances, the probability of network disconnection, the fraction of failed or incorrect successor and finger pointers and show how we can use these quantities to predict both the performance and consistency of lookups under churn. Additionally, we also discuss how churn may actually be of different ’types’ and the implications this will have for structured overlays in general. All theoretical predictions match simulation results to a high extent. The analysis includes details that are applicable to a generic structured overlay deploying a ring as well as Chord-specific details that can act as guidelines for analyzing other systems.

  • 68.
    El-Ansary, Sameh
    et al.
    Swedish Institute of Computer Science.
    Onana Alima, Luc
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Brand, Per
    Swedish Institute of Computer Science.
    Haridi, Seif
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    A Framework for Peer-To-Peer Lookup Services based on k-ary search2002Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Locating entities in peer-to-peer environments is a fundamentaloperation. Recent studies show that the concept of distributed hash table can be used to design scalable lookup schemes with good performance (i.e. small routing table and lookup length). In this paper, we propose a simple framework for deriving decentralized lookup algorithms. The proposed framework is simple in that it is based on the well-known concept of k-ary search. To demonstrate the applicability of our framework, we show how it can be used to instantiate Chord. When deriving a generalized Chord from our framework, we obtain better performance in terms of the routing table size (38% smaller than the generalization suggested by the Chord authors).

  • 69.
    El-Ansary, Sameh
    et al.
    Swedish Institute of Computer Science.
    Onana Alima, Luc
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Brand, Per
    Swedish Institute of Computer Science.
    Haridi, Seif
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Efficient broadcast in structured P2P networks2003Ingår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 2735, s. 304-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this position paper, we present an efficient algorithm for performing a broadcast operation with minimal cost in structured DHT-based P2P networks. In a system of N nodes, a broadcast message originating at an arbitrary node reaches all other nodes after exactly N - 1 messages. We emphasize the perception of a class of DHT systems as a form of distributed k-ary search and we take advantage of that perception in constructing a spanning tree that is utilized for efficient broadcasting. We consider broadcasting as a basic service that adds to existing DHTs the ability to search using arbitrary queries as well as dissiminate/collect global information.

  • 70. El-Mekawy, Mohamed
    et al.
    Östman, Anders
    Semantic Mapping: An Ontology Engineering Method for Integrating Building Models in IFC and CityGML2010Ingår i: In Proceedings of the 3rd ISDE DIGITAL EARTH SUMMIT, 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the main problems facing 3D city modelling applications is lack of interoperability among various Building Information Models (BIM) and Geographic Information Systems (GIS) models. CityGML (representing a wide range of 3D urban objects) and IFC (representing a very detailed semantic model for buildings) are considered the most prominent semantic models in GIS and BIM, respectively, today. When integrating the two models, substantial difficulties may arise in transforming information from one to the other. Professionals from both domains have made significant efforts to integrate CityGML and IFC models for seeking useful common applications. However, most of these efforts use a unidirectional method (mostly from IFC to CityGML) for a conversion process. As a formal mapping between both domains is required, researchers have suggested that harmonising semantics is the best approach for such integration. In this paper, we focus on semantic integration of IFC and CityGML building models for bidirectional conversion. Both IFC and CityGML use different terminologies to describe the same domain. Additionally, there is a great heterogeneity in their semantics. This paper, therefore, propose more expressive reference ontology between IFC and CityGML semantic models and an intermediate Unified Building Modelled (UBM) is built. The result of the paper contributes, through the reference ontology, towards a formal mapping between IFC and CityGML ontologies that allows bidirectional conversion between them. It also contributes towards a design of meta-standard for 3D city modelling that can support applications on both domains.

  • 71.
    El-Mekawy, Mohamed
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Östman, Anders
    Shahzad, Khurram
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Geospatial Interoperability for IFC and CityGML: Challenges of Existing Building Information Databases2008Ingår i: Proceedings of Innovations 08th, IEEE Conference, Dubai, December 16-18, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    CityGML is a XML based standard for geographical information related to the outdoor activities where urban objects can be represented and linked in different spatial relationships. Industrial Foundation Classes (IFC) standard on the other hand looks at buildings in more detailed picture that represents internal constructional and non-constructional objects. Interoperability between CityGML and IFC, i) leads to creation of a common standard for integrating 3D city (indoor and outdoor) applications, ii) provides an integrated view to decision makers for multi leveled analysis and for launching fast responses against crises. The purpose of this paper is to elicit prerequisites of interoperating CityGML and IFC. For this purpose, we have proposed a geospatial interoperability model, and applied it on a case study. The main challenges faced are related to spatial data integration issues. These issues include tabular data related aspects (such as schema matching problems and heterogeneity of sources) as well as spatial aspects (such as missing geometrical information and complexity of geometrical information presentation).

  • 72.
    Elowsson, Anders
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Deep Layered Learning in MIRManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Deep learning has boosted the performance of many music information retrieval (MIR) systems in recent years. Yet, the complex hierarchical arrangement of music makes end-to-end learning hard for some MIR tasks – a very deep and structurally flexible processing chain is necessary to extract high-level features from a spectrogram representation. Mid-level representations such as tones, pitched onsets, chords, and beats are fundamental building blocks of music. This paper discusses how these can be used as intermediate representations in MIR to facilitate deep processing that generalizes well: each music concept is predicted individually in learning modules that are connected through latent representations in a directed acyclic graph. It is suggested that this strategy for inference, defined as deep layered learning (DLL), can help generalization by (1) – enforcing the validity of intermediate representations during processing, and by (2) – letting the inferred representations establish disentangled structures that support high-level invariant processing. A background to DLL and modular music processing is provided, and relevant concepts such as pruning, skip connections, and layered performance supervision are reviewed.

  • 73.
    Elowsson, Anders
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH, Musikakustik.
    Modeling Music: Studies of Music Transcription, Music Perception and Music Production2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna avhandling presenterar tio studier inom tre viktiga delområden av forskningsområdet ”Music Information Retrieval” (MIR) – ett forskningsområde fokuserat på att extrahera information från musik. Del A riktar in sig på musiktranskription, del B på musikperception och del C på musikproduktion. En avslutande del diskuterar maskininlärningsmetodiken och spanar framåt (del D).

    I del A presenteras system som kan transkribera musik med hänsyn till rytm och polyfon tonhöjd. De två första publikationerna beskriver metoder för att estimera tempo och positionen av taktslag i ljudande musik. En metod för att beräkna den mest framstående periodiciteten (”cepstroiden”) beskrivs, samt hur denna kan användas för att guida de applicerade maskininlärningssystemen.  Systemet för polyfon tonhöjdsestimering kan både identifiera ljudande toner samt notstarter- och slut. Detta system är både tonhöjdsinvariant samt invariant med hänseende till variationer över tid inom ljudande toner. Transkriptionssystemen tränas till att predicera flera musikaspekter i en hierarkisk struktur. Transkriptionsresultaten är de bästa som rapporterats i tester på flera olika dataset.

    Del B fokuserar på perceptuella särdrag i musik. Dessa kan prediceras för att modellera fundamentala perceptionsaspekter, men de kan också användas som representationer i modeller som försöker klassificera övergripande musikparametrar. Modeller presenteras som kan predicera den upplevda hastigheten samt den upplevda dynamiken i utförandet med hög precision. Medelvärdesbildade skattningar från omkring 20 lyssnare utgör målvärden under träning och evaluering.

    I del C utforskas aspekter relaterade till musikproduktion. Den första studien analyserar variationer i medelvärdesspektrum mellan populärmusikaliska musikstycken. Analysen visar att nivån på perkussiva instrument är en viktig faktor för spektrumdistributionen – data antyder att denna nivå är bättre att använda än genreklassificeringar för att förutsäga spektrum. Den andra studien i del C behandlar musikkomposition. Ett algoritmiskt kompositionsprogram presenteras, där relevanta musikparametrar fogas samman en hierarkisk struktur. Ett lyssnartest genomförs för att påvisa validiteten i programmet och undersöka effekten av vissa parametrar.

    Avhandlingen avslutas med del D, vilken placerar den utvecklade maskininlärningstekniken i ett vidare sammanhang och föreslår nya metoder för att generalisera rytmprediktion. Den första studien diskuterar djupinlärningssystem som predicerar olika musikaspekter i en hierarkisk struktur. Relevanta koncept presenteras tillsammans med förslag för framtida implementationer. Den andra studien föreslår en tempoinvariant metod för att processa log-frekvensdomänen av rytmsignaler med så kallade convolutional neural networks. Den föreslagna arkitekturen kan använda sig av magnitud, relative fas mellan rytmkanaler, samt ursprunglig fas från frekvenstransformen för att ta sig an flera viktiga problem relaterade till rytm.

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    Introduction and Summary of Dissertation: Modeling Music - Anders Elowsson
  • 74.
    Eriksson, Emil
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    DánDán, György
    KTH, Skolan för elektro- och systemteknik (EES).
    Fodor, Viktoria
    KTH, Skolan för elektro- och systemteknik (EES).
    Coordinating Distributed Algorithms for Feature Extraction Offloading in Multi-Camera Visual Sensor Networks2018Ingår i: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205, Vol. 28, nr 11, s. 3288-3299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Real-time visual analysis tasks, like tracking and recognition, require swift execution of computationally intensive algorithms. Visual sensor networks could be enabled to perform such tasks by allowing the camera nodes to offload their computational load to nearby processing nodes. In this paper, we address the problem of minimizing the completion time of multiple camera sensors that share the transmission and the processing resources of multiple processing nodes for computation offloading. We show that the problem is NP-hard, and propose a combination of central coordination and distributed optimization with limited signaling among the camera sensors as a solution. We analyze the existence of equilibrium allocations for the distributed algorithms, evaluate the effect of the network topology and of the video characteristics on the algorithms' performance, and assess the benefits of central coordination. Our results demonstrate that with sufficient information available, distributed optimization can provide low completion times, moreover predictable and stable performance can be achieved with additional, sparse central coordination.

  • 75.
    Eriksson, John
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Höglund, Jonas
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    A comparison of reductions from FACT to CNF-SAT2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The integer factorisation problem (FACT) is a well-known number-theoreticproblem, with many applications in areas such as cryptography. An instanceof a FACT problem (a number n such that n = p × q) can be reduced to aninstance of the conjunctive normal form boolean satisfiability problem (CNF-SAT), a well-known NP-complete problem. Some applications of this is toutilize advances in SAT solving for solving FACT, and for creating difficultCNF-SAT instances.This report compares four different reductions from FACT to CNF-SAT,based on the full adder, array multiplier and Wallace tree multiplier circuits.The comparisons were done by reducing a set of FACT instances to CNF-SATinstances with the different reductions. The resulting CNF-SAT instanceswere then compared with respect to the number of clauses and variables, aswell as the time taken to solve the instances with the SAT solver MiniSat.

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  • 76. Fakih, M.
    et al.
    Grüttner, K.
    Schreiner, S.
    Seyyedi, R.
    Azkarate-Askasua, M.
    Onaindia, P.
    Poggi, T.
    Romero, N. G.
    Gonzalez, E. Q.
    Sundström, T.
    Frasquet, S. P.
    Balbastre, P.
    Mohammadat, T.
    Öberg, Johnny
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Elektronik och inbyggda system.
    Bebawy, Y.
    Obermaisser, R.
    Maleki, A.
    Lenz, A.
    Graham, D.
    Experimental evaluation of SAFEPOWER architecture for safe and power-efficient mixed-criticality systems2019Ingår i: Journal of Low Power Electronics and Applications, Vol. 9, nr 1, artikel-id 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the ever-increasing industrial demand for bigger, faster and more efficient systems, a growing number of cores is integrated on a single chip. Additionally, their performance is further maximized by simultaneously executing as many processes as possible. Even in safety-critical domains like railway and avionics, multicore processors are introduced, but under strict certification regulations. As the number of cores is continuously expanding, the importance of cost-effectiveness grows. One way to increase the cost-efficiency of such a System on Chip (SoC) is to enhance the way the SoC handles its power consumption. By increasing the power efficiency, the reliability of the SoC is raised because the lifetime of the battery lengthens. Secondly, by having less energy consumed, the emitted heat is reduced in the SoC, which translates into fewer cooling devices. Though energy efficiency has been thoroughly researched, there is no application of those power-saving methods in safety-critical domains yet. The EU project SAFEPOWER (Safe and secure mixed-criticality systems with low power requirements) targets this research gap and aims to introduce certifiable methods to improve the power efficiency of mixed-criticality systems. This article provides an overview of the SAFEPOWER reference architecture for low-power mixed-criticality systems, which is the most important outcome of the project. Furthermore, the application of this reference architecture in novel railway interlocking and flight controller avionic systems was demonstrated, showing the capability to achieve power savings up to 37%, while still guaranteeing time-triggered task execution and time-triggered NoC-based communication. 

  • 77. Falappa, Marcelo A.
    et al.
    Ferme, Eduardo L.
    Kern-Isberner, Gabriele
    On the Logic of Theory Change: Relations between Incision and Selection Functions2006Ingår i: ECAI 2006, PROCEEDINGS, 2006, Vol. 141, s. 402-406Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work elaborates on the connection between partial meet contractions and kernel contractions in belief change theory. We present a way to define incision functions (used in kernel contractions) from selection functions (used in partial meet contractions) and vice versa. Then we make precise under which conditions there are exact correspondences between selection and incision functions so that the same contraction operations can be obtained by using either of them.

  • 78.
    Falk, Andreas
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Moberg, Johannes
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Algorithmic trading using MACD signals2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Todays stock market is dominated by algorithmic trading either as helpful tool for trading decisions or as a fully automatic trader. We test howa fully automated trading algorithm using MACD signals as indicatorsperform on historical stock data. The purpose of this essay is to seehow a simple algorithm performs and get a better understanding ofeconomical forecasting.

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    fulltext
  • 79.
    Fang, Huan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Brorsson, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster, Programvaru- och datorsystem, SCS.
    Scalable directory architecture for distributed shared memory chip multiprocessors2008Ingår i: SIGARCH Computer Architecture News, ISSN 0163-5964, E-ISSN 1943-5851, Vol. 36, nr 5, s. 56-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Traditional Directory-based cache coherence protocol is far from optimal for large-scale cache coherent shared memory multiprocessors due to the increasing latency to access directories stored in DRAM memory. Instead of keeping directories in main memory, we consider distributing the directory together with L2 cache across all nodes on a Chip Multiprocessor. Each node contains a processing unit, a private L1 cache, a slice of L2 cache, memory controller and a router. Both L2 cache and memories are distributed shared and interleaved by a subset of memory address bits. All nodes are interconnected through a low latency two dimensional Mesh network. Directory, being a split component to L2 cache, only stores sharing information for blocks while L2 cache stores only data blocks exclusive with L1 cache. Shared L2 cache can increase total effective cache capacity on chip, but also increase the miss latency when data is on a remote node. Being different from Directory Cache structure, our proposal totally removes the directory from memory, which saves memory space and reduces access latency. Compared to L2 cache that combines directory information internally, our L2 cache structure saves up to 88% cache space and achieves similar performance.

  • 80.
    feisal, haadi
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    altangerel, ulsbold
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Multi-sided payment platform using Blockchain and Open banking2019Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det finns flera dominerande konkurrenter på den digitala betalningsmarknaden. Dessa företag har en majoritet av kunderna och upprätthåller sitt dominerande inflytande på marknaden genom att ta avgifter från kunder och handlare för mobila betalningar. Syftet med denna studie är att utveckla ett betalningssystem som ansluter olika betalningsapplikationer och banksystem med hjälp av blockkedjeteknik och öppen bankteknologi. Blockkedja-systemet används som en säker universell databas, medan den öppna banktekniken används för transaktioner. Denna studie utvecklade en arkitektur för en gemensam betalningsplattform. Arkitekturen följer ett mikro-tjänst designmönster vilket tillåter systemets komponenter att utvecklas och underhållas individuellt. En prototyp utvecklades som en konceptvalidering för arkitekturen, vilket bevisar möjligheten till en gemensam betalningsplattform. Betalningsapplikationen “ICA Handla” och Nordea öppen bankteknologi är anslutna till prototypsystemet via ett gateway program. Syftet med gateway programmet är att ansluta mobila betalningsapplikationer eller banktjänster med en blockkedja-system. Den gemensamma betalningsapplikationer skapar möjligheter på den digitala betalningsmarknaden.

    Publikationen är tillgänglig i fulltext från 2020-06-08 10:00
  • 81.
    Feng, Chaochao
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Liao, Z.
    Lu, Zhonghai
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Jantsch, Axel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem.
    Zhao, Z.
    Performance analysis of on-chip bufferless router with multi-ejection ports2015Ingår i: Proceedings - 2015 IEEE 11th International Conference on ASIC, ASICON 2015, IEEE conference proceedings, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In general, the bufferless NoC router has only one local output port for ejection, which may lead to multiple arriving flits competing for the only one output port. In this paper, we propose a reconfigurable bufferless router in which the number of ejection ports can be configured as 2, 3 and 4. Simulation results demonstrate that the average packet latency of the routers with multi-ejection ports is 18%, 10%, 6%, 14%, 9% and 7% on average less than that of the router with 1 ejection ports under six synthetic workloads respectively. For application workloads, the average packet latency of the router with more than two ejection ports is slightly better than the router with only one ejection port, which can be neglect. Making a compromise of hardware cost and performance, it can be concluded that it is no need to implement bufferless routers with 3 and 4 ejection ports, as the router with 2 ejection ports can achieve almost the same performance as the routers with 3 and 4 ejection ports.

  • 82.
    Fernandes Pereira, Sonia
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Hamid, Nejat
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Closed-Loop Orchestration Solution2019Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Datornätverk utvecklas kontinuerligt och växer i storlek och komplexitet. Nyteknik införs som ytterligare ökar komplexiteten. Nätverksservice orkestrering handlar om att skicka ut konfiguration automatiskt till enheter i nätverket utan mänsklig in- blandning. Det kan finnas problem som gör att orkestreringen misslyckas. I många fall måste manuella åtgärder utföras för att lösa problemet, vilket är mycket motsä- gelsefullt, eftersom målet med orkestrering är att det ska vara fullt automatiserat.

    Det finns indikationer på att fel kan detekteras och hanteras av en återkopplings- mekanismen. Detta examensarbete syftar till att bygga på aktuell insikt, och om möj- ligt, verifiera att återkopplingsmekanismen är en möjlig metod.

    Efter överväganden på vilka olika sätt som projektmålet kunde uppnås föll valet på att skapa en testmiljö där ansatsen kunde testas. Testmiljön användes för att utreda om ett nätverksorkestreringssystem kan integreras med en återkopplings mekanism. Resultat av projektet presenterar ett sätt att automatiskt upptäcka ett nätverksfel och skicka återkoppling till ett nätverksorkestreringssystem. Nätverksorkestreraren kan sedan detektera och åtgärda felet.

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  • 83.
    Fernandes Pereira, Sonia
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Hamid, Nejat
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Closed-Loop Orchestration Solution2019Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Datornätverk utvecklas kontinuerligt och växer i storlek och komplexitet. Nyteknik införs som ytterligare ökar komplexiteten. Nätverksservice orkestrering handlar om att skicka ut konfiguration automatiskt till enheter i nätverket utan mänsklig in- blandning. Det kan finnas problem som gör att orkestreringen misslyckas. I många fall måste manuella åtgärder utföras för att lösa problemet, vilket är mycket motsä- gelsefullt, eftersom målet med orkestrering är att det ska vara fullt automatiserat.

    Det finns indikationer på att fel kan detekteras och hanteras av en återkopplings- mekanismen. Detta examensarbete syftar till att bygga på aktuell insikt, och om möj- ligt, verifiera att återkopplingsmekanismen är en möjlig metod.

    Efter överväganden på vilka olika sätt som projektmålet kunde uppnås föll valet på att skapa en testmiljö där ansatsen kunde testas. Testmiljön användes för att utreda om ett nätverksorkestreringssystem kan integreras med en återkopplings mekanism. Resultat av projektet presenterar ett sätt att automatiskt upptäcka ett nätverksfel och skicka återkoppling till ett nätverksorkestreringssystem. Nätverksorkestreraren kan sedan detektera och åtgärda felet.

    Ladda ner fulltext (pdf)
    fulltext
  • 84.
    Firouzi, Seyed Reza
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. KTH The Royal Institute of Technology.
    Ruiz-Alvarez, A.
    Mahmood, Farhan
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. KTH The Royal Institute of Technology.
    Hooshyar, Hossein
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. KTH The Royal Institute of Technology.
    Cairo, I.
    An IEC 61850-90-5 gateway for IEEE C37.118.2 synchrophasor data transfer2016Ingår i: IEEE Power and Energy Society General Meeting, IEEE, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work describes the implementation and validation of a library named Khorjin to receive and parse synchrophasor data from a PμPDC based on IEEE C37.118.2 protocol, map it to the IEC 61850 data model and transmit the synchrophasor data through either Routed-Sampled Value or Routed-GOOSE services defined in the IEC 61850-90-5 protocol. In addition, the library is capable of acting as the receiver and parser of IEC 61850-90-5 messages, extracting raw synchrophasor data and feeding to subscriber applications. The functionality of the Khorjin library is validated in a Real-Time Hardware-in-the-Loop (HIL) simulation environment to asses its conformance to the functional requirements of the IEC 61850-90-5 standard.

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    fulltext
  • 85.
    Foitzik, John
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Comparison between two methods for 3D imaging of machine parts2015Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Idag tillverkas komponenter med additive manufacturing (AM) vilket gör att produktionsti- den blivit kortare och de färdiga produkterna har vanligtvis mycket få fel. Om komponen- ternas kvalitet ska valideras, görs det med en icke-förstörande provningsmetod. I denna avhandling har en provbit av Inconel 939, ett material som lämpar sig för höga temperaturer undersökts med en oförstörande provning teknik (NDT), datortomografi (CT) och förstö- rande provning (DT) genom att slipa sig ner i provbiten till en given position och ta bilder på ytan. Syftet var att validera datortomografibilder genom att göra en tvådimensionell kor- relation mellan bilder från CT och DT med hjälp av MATLAB. På grund av tekniska pro- blem så visar de resulterande bilderna inte samma område. Därför ska korrelationsmetoden valideras. Genom att ändra en 2D-bild från CT och köra den i koden skriven i MATLAB så att den distorderade bilden kan kvantifieras. Resultatet presenteras i figurerna och i tabeller. Tabellen visar mer detaljerat med exakta koordinater och vad varje delområde har för kor- relation. Figuren visar rörelser och riktning av förändringarna. Resultatet visar att metoden kan upptäcka förändringar och göra det som var tänkt. 

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  • 86. Garbajosa, J.
    et al.
    Magnusson, Mats
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    Wang, X.
    Generating innovations for the internet of things: Agility and speed2017Ingår i: ACM International Conference Proceeding Series, Association for Computing Machinery , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Internet of Things (IoT) bears great potential for innovation in modern companies. Agility and speed both matter when innovating in such a context. The first Inno4IoT workshop focuses on how to properly achieve and balance the two aspects while innovating IoT-based solutions, which represents unique opportunities and challenges to researchers and practitioners alike. An overview of the three working papers presented and published in the workshop is provided in this introductory paper.

  • 87.
    Ghodsi, Ali
    et al.
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Onana Alima, Luc
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    El-Ansary, Sameh
    Swedish Institute of Computer Science.
    Brand, Per
    Swedish Institute of Computer Science.
    Haridi, Seif
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Self-Correcting Broadcast in Distributed Hash Tables2003Ingår i: Proceedings of the Fifteenth IASTED International Conference on Parallel and Distributed Computing and Systems / [ed] Gonzalez, T., 2003, s. 93-98Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present two broadcast algorithms that can be used on top of distributed hash tables (DHTs) to perform group communication and arbitrary queries. Unlike other P2P group communication mechanisms, which either embed extra information in the DHTs or use random overlay networks, our algorithms take advantage of the structured DHT overlay networks without maintaining additional information. The proposed algorithms do not send any redundant messages. Furthermore the two algorithms ensure 100% coverage of the nodes in the system even when routing information is outdated as a result of dynamism in the network. The first algorithm performs some correction of outdated routing table entries with a low cost of correction traffic. The second algorithm exploits the nature of the broadcasts to extensively update erroneous routing information at the cost of higher correction traffic. The algorithms are validated and evaluated in our stochastic distributed-algorithms simulator.

  • 88.
    Gilljam, Daniel
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Youssef, Mario
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Jämförelse av artificiella neurala nätverksalgoritmerför klassificering av omdömen2018Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Vid stor mängd data i form av kundomdömen kan det vara ett relativt tidskrävande arbeteatt bedöma varje omdömes sentiment manuellt, om det är positivt eller negativt laddat. Denna avhandling har utförts för att automatiskt kunna klassificera kundomdömen efter positiva eller negativa omdömen vilket hanterades med hjälp av maskininlärning. Tre olika djupa neurala nätverk testades och jämfördes med hjälp av två olika ramverk, TensorFlow och Keras, på både större och mindre datamängder. Även olika inbäddningsmetoder testades med de neurala nätverken. Den bästa kombination av neuralt nätverk, ramverk och inbäddningsmetod var ett Convolutional Neural Network (CNN) som använde ordinbäddningsmetoden Word2Vec, var skriven i ramverket Keras och gav en träffsäkerhetpå ca 88.87% med en avvikelse på ca 0.4%. CNN gav bäst resultat i alla olika tester framför de andra två neurala nätverken, Recurrent Neural Network (RNN) och Convolutional Recurrent Neural Network (CRNN)

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    Examensrapport
  • 89.
    Gonzalez Prieto, Alberto
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Stadler, Rolf
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Adaptive distributed monitoring with accuracy objectives2006Ingår i: Proceedings of the 2006 SIGCOMM Workshop on Internet Network Management, INM'06, 2006, Vol. 2006, s. 65-70Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present A-GAP, a novel protocol for continuous monitoring of network state variables, which aims at achieving a given monitoring accuracy with minimal overhead. Network state variables are computed from device counters using aggregation functions, such as SUM, AVERAGE and MAX. The accuracy objective is expressed as the average estimation error. A-GAP is decentralized and asynchronous to achieve robustness and scalability. It executes on an overlay that interconnects management processes on the devices. On this overlay, the protocol maintains a spanning tree and updates the network state variables through incremental aggregation. It dynamically configures local filters that control whether an update is sent towards the root of the tree. It reduces the overhead by attempting to minimize the maximum processing load over all management processes. We evaluate A-GAP through simulation using an ISP topology and real traces. The results show that we can effectively control the trade-off between accuracy and protocol overhead, that the overhead can be reduced significantly by allowing small errors, and that an accurate estimation of the error distribution can be provided in real-time.

  • 90.
    Gopu, Anusharani
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Using non-medical risk factors related to dementia and cognitive decline for developing an evidencebased e-health tool2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Antal demensfall ökar över hela världen. Forskning och utveckling inom detta område är relaterat till att förebygga demens och att utveckla olika prognosverktyg för demens. Flera tillgängliga verktyg tar hänsyn till medicinska data i beräkning av riskpoäng, med endast en liten mängd av icke-medicinska data. Det finns en hel del data om medicinska och icke-medicinska faktorer online, men de används idag inte för riskpoängberäkning. Som en del av projektet Multimodala strategier för att främja en frisk hjärna i åldrande: Innovativa evidensbaserade verktyg (MULTI-MODE), så har en ny metod utvecklats för att användas i ett nytt IT-baserat verktyg för demensförutsägelse.

    Identifiering av icke-medicinska data och en bra modell för att överbrygga gapet mellan tillgängliga data på servern och använda dessa data i riskberäkning kan bidra till att öka precisionen hos verktyg. I den här studien beskrivs en del befintliga riskfaktorer för förutsägelse av demens och vikten av icke-medicinska faktorer i beräkning av risk diskuteras. Ytterligare icke-medicinska faktorer identifieras som skulle kunna ingå i framtida versioner av riskverktyg (såsom appar). Vissa identifierade riskfaktorer har analyserats och visade att effekten av att införa icke-medicinska faktorer ökar precisionen i resultaten. En databasdesign för lagring av riskinformation på ett effektivt sätt presenteras, liksom en appstruktur som kan användas på serversidan för att validera några av de parametrar som kan öka effektiviteten av verktyget.

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  • 91.
    Gramfors, Dexter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Johansson, Andreas
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Emotionally expressive song synthesis using formants and syllables2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Speech synthesis is an area of computer science with many practical uses, such as enabling people with visual impairments to take part of text and to provide more human-like feedback from information systems. A similar area of research is text-to-song, where systems comparable to those used in text-to-speech pro- vide mappings from text to melodic units of song. This paper discusses how a text-to-song algorithm can be developed and what parameters affect what emotion is communicated. Fifty participants listened to music generated with our algorithm. Results show that tempo and mode both heavily account for what emotion is communicated; a melody performed with a tempo of 250 bpm was perceived as significantly more happy than a performance with a tempo of 120 bpm, and a melody in major tonality was perceived as significantly more happy than a melody in minor tonality. Combined, these parameters gave even more significant results. A fast tempo combined with major tonality produced a performance that was perceived as even more happy. The opposite was observed when a slow tempo was combined with minor tonality. When a fast tempo was combined with a minor tonality the average answer was neu- tral with answers distributed over the whole spectrum from sad to happy. A slow tempo combined with a major tonality gave almost identical results. We concluded that generating emotionally expressive song with the use of an al- gorithm is definitely possible, but that the methodology can be improved in order to convey emotions even more clearly. 

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  • 92.
    Guanciale, Roberto
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Teoretisk datalogi, TCS.
    Protecting Instruction Set Randomization from Code Reuse Attacks2018Ingår i: 23rd Nordic Conference on Secure IT Systems, NordSec 2018, Springer Verlag , 2018, s. 421-436Konferensbidrag (Refereegranskat)
    Abstract [en]

    Instruction Set Randomization (ISR) prevents code injection by randomizing the instruction encoding used by programs, thus preventing an attacker from preparing a payload that can be injected in a victim. In this paper we show that code-reuse attacks can be used to circumvent existing ISR techniques and we demonstrate these attacks on an ARMv7 CPU that has been extended with ISR support. To counter this treat, we propose a new ISR that does not have the same vulnerabilities as the existing solutions, imposes moderate decryption cost, does not require additional memory per instruction, and affords efficient random access to the encrypted code. These properties enable efficient hardware implementation of our solution. In order to evaluate our proposal, we implement the new ISR in a hardware simulator and we compare its overhead with respect to existing ISR. 

  • 93. Guang, L.
    et al.
    Plosila, J.
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik.
    Self-adaptive SoCs for dependability: Review and prospects2014Ingår i: Advancing Embedded Systems and Real-Time Communications with Emerging Technologies, IGI Global, 2014, s. 1-21Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Dependability is a primary concern for emerging billion-transistor SoCs (Systems-on-Chip), especially when the constant technology scaling introduces an increasing rate of faults and errors. Considering the time-dependent device degradation (e.g. caused by aging and run-time voltage and temperature variations), self-adaptive circuits and architectures to improve dependability is promising and very likely inevitable. This chapter extensively surveys existing works on monitoring, decision-making, and reconfiguration addressing different dependability threats to Very Large Scale Integration (VLSI) chips. Centralized, distributed, and hierarchical fault management, utilizing various redundancy schemes and exploiting logical or physical reconfiguration methods, are all examined. As future research directions, the challenge of integrating different error management schemes to account for multifold threats and the great promise of error resilient computing are identified. This chapter provides, for chip designers, much needed insights on applying a self-adaptive computing paradigm to approach dependability on error-prone, cost-sensitive SoCs.

  • 94.
    Guo, Yao
    et al.
    School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China.
    Vlassov, Vladimir
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Ashok, Raksit
    Google Inc., 1600 Amphitheatre Parkway, Mountain View, CA 94043, USA.
    Weiss, Richard
    The Evergreen State College, Olympia, WA 98505, USA.
    Andras Moritz, Csaba
    Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, MA 01003, USA.
    Synchronization coherence: A transparent hardware mechanism for cache coherence and fine-grained synchronization2008Ingår i: Journal of Parallel and Distributed Computing, ISSN 0743-7315, E-ISSN 1096-0848, Vol. 68, nr 2, s. 165-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The quest to improve performance forces designers to explore finer-grained multiprocessor machines. Ever increasing chip densities based on CMOS improvements fuel research in highly parallel chip multiprocessors with 100s of processing elements. With such increasing levels of parallelism, synchronization is set to become a major performance bottleneck and efficient support for synchronization an important design criterion. Previous research has shown that integrating support for fine-grained synchronization can have significant performance benefits compared to traditional coarse-grained synchronization. Not much progress has been made in supporting fine-grained synchronization transparently to processor nodes: a key reason perhaps why wide adoption has not followed. In this paper, we propose a novel approach called synchronization coherence that can provide transparent fine-grained synchronization and caching in a multiprocessor machine and single-chip multiprocessor. Our approach merges fine-grained synchronization mechanisms with traditional cache coherence protocols. It reduces network utilization as well as synchronization related processing overheads while adding minimal hardware complexity as compared to cache coherence mechanisms or previously reported fine-grained synchronization techniques. In addition to its benefit of making synchronization transparent to processor nodes, for the applications studied, it provides up to 23% improvement in performance and up to 24% improvement in energy efficiency with no L2 caches compared to previous fine-grained synchronization techniques. The performance improvement increases up to 38% when simulating with an ideal L2 cache system.

  • 95.
    Görtz, Stefan
    et al.
    KTH, Tidigare Institutioner                               , Farkost- och flygteknik.
    Möller, Joakim
    KTH, Tidigare Institutioner                               , Numerisk analys och datalogi, NADA.
    Evaluation of the Recursive Projection Method for Efficient Unsteady Turbulent CFD Simulations2004Ingår i: 24th INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES, 2004, s. 1-13Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Recursive Projection Method (RPM) hasbeen implemented into an unstructured CFD code to improve the efficiency of dual time steppingfor unsteady turbulent CFD simulations.RPM is a combined implicit-explicit method that enhances convergence. It can easily be implementedinto existing codes and the solver’s existing acceleration techniques can be used withoutchange. The method has been evaluated by computing the periodic self-induced shock oscillations over an 18% thick biconvex airfoil at0◦ angle of attack, a Mach number of 0.76 anda Reynolds number of 11 million. On average,RPM accelerated the convergence of the innerloop of dual time stepping to a predefined convergencecriterion by a factor of about 2.5.

  • 96.
    Görtz, Stefan
    et al.
    KTH, Tidigare Institutioner, Farkost- och flygteknik.
    Möller, Joakim
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    Recursive Projection Method for efficient unsteady CFD simulations2004Ingår i: / [ed] P. Neittaanmäki, T. Rossi, K. Majava, and O. Pironneau, 2004, s. 1-20Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Recursive Projection Method (RPM) has been implemented into the unstructured grid CFD code EDGE to accelerate the inner-loop convergence of dual time stepping. The method tries to identify the slowly converging subspace and applies Newton iterations in this subspace together with a fixed point scheme in the complement. The method has been employed to compute the steady and unsteady viscous flow around a circular cylinder for a Reynolds number of 100. When converging to machine accuracy, RPM accelerated the convergence of the steady-state solution by a factor of 2.5. The time-accurate simulations were accelerated by a factor of about two.

  • 97. Haghbayan, M. -H
    et al.
    Rahmani, A. -M
    Fattah, M.
    Liljeberg, P.
    Plosila, J.
    Navabi, Z.
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik.
    Power-aware online testing of manycore systems in the dark silicon era2015Ingår i: Proceedings -Design, Automation and Test in Europe, DATE, IEEE conference proceedings, 2015, s. 435-440Konferensbidrag (Refereegranskat)
    Abstract [en]

    Online defect screening techniques to detect runtime faults are becoming a necessity in current and near future technologies. At the same time, due to aggressive technology scaling into the nanometer regime, power consumption is becoming a significant burden. Most of today's chips employ advanced power management features to monitor the power consumption and apply dynamic power budgeting (i.e., capping) accordingly to prevent over-heating of the chip. Given the notable power dissipation of existing testing methods, one needs to efficiently manage the power budget to cover test process of a many-core system in runtime. In this paper, we propose a power-aware online testing method for many-core systems benefiting from advanced power management capabilities. The proposed power-aware method uses non-intrusive online test scheduling strategy to functionally test the cores in their idle period. In addition, we propose a test-aware utilization-oriented runtime mapping technique that considers the utilization of cores and their test criticality in the mapping process. Our extensive experimental results reveal that the proposed power-aware online testing approach can efficiently utilize temporarily free resources and available power budget for the testing purposes, within less than 1% penalty on system throughput for the 16nm technology.

  • 98. Haghbayan, Mohammad-Hashem
    et al.
    Miele, Antonio
    Rahmani, Amir M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik.
    Liljeberg, Pasi
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik. Univ Turku.
    A Lifetime-Aware Runtime Mapping Approach for Many-core Systems in the Dark Silicon Era2016Ingår i: PROCEEDINGS OF THE 2016 DESIGN, AUTOMATION & TEST IN EUROPE CONFERENCE & EXHIBITION (DATE), IEEE conference proceedings, 2016, s. 854-857Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we propose a novel lifetime reliability-aware resource management approach for many-core architectures. The approach is based on hierarchical architecture, composed of a long-term runtime reliability analysis unit and a short-term runtime mapping unit. The former periodically analyses the aging status of the various processing units with respect to a target value specified by the designer, and performs recovery actions on highly stressed cores. The calculated reliability metrics are utilized in runtime mapping of the newly arrived applications to maximize the performance of the system while fulfilling reliability requirements and the available power budget. Our extensive experimental results reveal that the proposed reliability-aware approach can efficiently select the processing cores to be used over time in order to enhance the reliability at the end of the operational life (up to 62%) while offering the comparable performance level of the state-of-the-art runtime mapping approach.

  • 99. Haghbayan, Mohammad-Hashem
    et al.
    Teravainen, Sami
    Rahmani, Amir-Mohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik. Turku Univ..
    Liljeberg, Pasi
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Industriell och Medicinsk Elektronik.
    Adaptive Fault Simulation on Many-core Microprocessor Systems2015Ingår i: PROCEEDINGS OF THE 2015 IEEE INTERNATIONAL SYMPOSIUM ON DEFECT AND FAULT TOLERANCE IN VLSI AND NANOTECHNOLOGY SYSTEMS (DFTS), IEEE Computer Society, 2015, s. 151-154Konferensbidrag (Refereegranskat)
    Abstract [en]

    Efficiency of Network-on-Chip based many-core microprocessors to implement parallel fault simulation methods for different circuit sizes is explored in this paper. We show that a naive and straightforward execution of fault simulation programs on such systems does not provide the maximum speedup due to severe bottlenecks in off-chip shared memory access at memory controllers. In order to exploit the available massive parallelism of homogenous many-core microprocessors, a runtime approach capable of adaptively balancing the load during the fault simulation process is proposed. We demonstrate the proposed adaptive fault simulation approach on a many-core platfonn, Intels Single-chip Cloud Computer showing up to 45X speedup compared to a serial fault simulation approach.

  • 100.
    Hammer, Joakim
    et al.
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    Lind, Olle
    KTH, Skolan för teknik och hälsa (STH), Data- och elektroteknik.
    Scalable platform for health service integrations2013Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete har utförts hos företaget ShapeUp Club i Stockholm. ShapeUp Club erbjuder en digital kaloriräknare för webben, iOS och Android med synkronisering av data mellan dessa plattformar. ShapeUp Club vill kunna erbjuda sina kunder möjligheten att synkronisera data mellan ShapeUp Club och andra externa hälsotjänster.

    Målet med detta projekt har varit att implementera en ny tjänst till ShapeUp Clubs nuvarande backend-lösning där externa hälsotjänster snabbt och skalbart kan implementeras. Externa hälso-API:er har utvärderats och implementerats i samband med utvecklingen av den nya backendtjänsten, för att validera dess funktionalitet. Mängden kod som behövs för att implementera en hälsotjänst bör vara så minimal som möjligt för att utvecklare snabbt ska kunna lägga till ytterligare tjänster. För att systemet ska vara skalbart måste logik finnas för hur ofta användare ska tillåtas att fråga efter data mot de tjänster de har valt att synkronisera mot. För att tillfredställa dessa behov har en utökning av ShapeUp Clubs nuvarande backend-lösning byggts med ramverket Django för Python. Genom att ha en större, generisk klass som nya implementeringar ärver från så har mängden nödvändig kod för varje hälsotjänst-implementering minskats till metoder för API-anrop, autentisering och serialisering av data. För att minska antalet “onödiga” poll-anrop så placerar vi användare i olika grupper beroende på om deras poll-anrop frekvent återvänder utan någon ny information. De olika grupperna bestämmer sedan hur länge användarna måste vänta innan de tillåts göra nya poll-anrop. 

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