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  • 2701.
    Sljivo, Irfan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gallina, Barbara
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Carlson, Jan
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Hansson, Hans
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Puri, Stefano
    Intecs SpA, Italy.
    A Method to Generate Reusable Safety Case Argument-Fragments from Compositional Safety Analysis2017Ingår i: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 131, s. 570-590Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Safety-critical systems usually need to be accompanied by an explained and well-founded body of evidence to show that the system is acceptably safe. While reuse within such systems covers mainly code, reusing accompanying safety artefacts is limited due to a wide range of context dependencies that need to be satisfied for safety evidence to be valid in a different context. Currently, the most commonly used approaches that facilitate reuse lack support for systematic reuse of safety artefacts. To facilitate systematic reuse of safety artefacts we provide a method to generate reusable safety case argument-fragments that include supporting evidence related to compositional safety analysis. The generation is performed from safety contracts that capture safety-relevant behaviour of components in assumption/guarantee pairs backed up by the supporting evidence. We evaluate the feasibility of our approach in a real-world case study where a safety related component developed in isolation is reused within a wheel-loader.

  • 2702.
    Sljivo, Irfan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gallina, Barbara
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Kaiser, B.
    Berner & Mattner Systemtechnik GmbH, Munich, Germany.
    Assuring degradation cascades of car platoons via contracts2017Ingår i: Lecture Notes in Computer Science, vol. 10489, Springer Verlag , 2017, s. 317-329Konferensbidrag (Refereegranskat)
    Abstract [en]

    Automated cooperation is arriving in practice, for instance in vehicular automation like platoon driving. The development and safety assurance of those systems poses new challenges, as the participating nodes are not known at design time; they engage in communication at runtime and the system behaviour can be distorted at any time by failures in some participant or in the communication itself. When running on a highway, simply switching off the function is not an option, as this would also result in hazardous situations. Graceful degradation offer a systematic approach to define a partial-order of less and less acceptable operation modes, of which the best achievable is selected in presence of failures. In this work we propose an approach for assurance of the degradation cascades based on mode-specific assertions, captured by assumption/guarantee contracts. More specifically, we share our experiences and methodology for specifying the contracts for both the nominal safe behaviour as well as the less safe but acceptable behaviour in presence of failures. Furthermore, we present an argument pattern for adequacy of the degradation cascades for meeting the global safety goals based on the contracts. We illustrate our approach by a car platooning case study.

  • 2703.
    Smeraldi, Fabrizio
    et al.
    Högskolan i Halmstad.
    Bigun, Josef
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Gerstner, Wulfram
    Swiss Federal Institute of Technology, Lausanne.
    Support vector features and the role of dimensionality in face authentication2002Ingår i: Pattern recognition with support vector machines / [ed] Seong-Whan Lee, Alessandro Verri, Heidelberg: Springer Berlin/Heidelberg, 2002, Vol. LNCS-2388, s. 249-259Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A study of the dimensionality of the Face Authentication problem using Principal Component Analysis (PCA) and a novel dimensionality reduction algorithm that we call Support Vector Features (SVFs) is presented. Starting from a Gabor feature space, we show that PCA and SVFs identify distinct subspaces with comparable authentication and generalisation performance. Experiments using KNN classifiers and Support Vector Machines (SVMs) on these reduced feature spaces show that the dimensionality at which saturation of the authentication performance is achieved heavily depends on the choice of the classifier. In particular, SVMs involve directions in feature space that carry little variance and therefore appear to be vulnerable to excessive PCA-based compression. © Springer-Verlag Berlin Heidelberg 2002.

  • 2704.
    Smith, Jonathan M.
    et al.
    Computer Science Department, Columbia University, New York.
    Maguire Jr., Gerald Q.
    Effects of Copy-on-Write Memory Management on the Response Time of UNIX Fork Operations1988Ingår i: Computing Systems, ISSN 0895-6340, Vol. 1, nr 3, s. 255-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present techniques for analyzing the effect of ‘‘copy-on-write’ ’ page management strategies on the performance of UNIX (TM) fork() operations. The analysis techniques are applied on two workstations, the AT&T 3B2/310 TM and the Hewlett-Packard HP9000/350 TM in order to determine the relationships between the amount of memory in the parent’s data segment, the fraction of this memory which is written by the child, and the improvement in execution time due to ‘‘copy-on-write’’. Since the implementation of ‘‘copy-on-write’ ’ is straightforward with modern MMUs, our results for these workstations are readily generalized to other workstations. The results show that the size of the parent’s allocated memory has little direct effect on performance, due to the fact that only page table entries are copied during the fork() operations. The execution time is most influenced by the amount of memory that must be copied, which can be determined from the product of memory allocated and the fraction of memory written. Thus, the worst case occurs when large address space programs update much of their memory. In order to observe what occurs in practice, we measured two programs that have what are currently considered large address spaces. These programs, which we believe to be representative of the sorts of programs.

  • 2705.
    Smith, Jonathan M.
    et al.
    Columbia University.
    Maguire Jr., Gerald Q.
    Columbia University, Department of Computer Science.
    Measured response times for page-sized fetches on a network1989Ingår i: ACM SIGARCH Computer Architecture News, ISSN 0163-5964, Vol. 17, nr 5, s. 48-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous work has examined the response times associated with disk accesses and the response time associated with various memory access operations. Here, we discuss the response time behavior of access requests for pagesized objects which are made using a network connection. We feel that future architectures must include networked resources as a component of the storage hierarchy; such performance measurements will help architects place these resources intelligently.

  • 2706.
    Smith, Jonathan M.
    et al.
    Columbia University.
    Maguire Jr., Gerald Q.
    Columbia University, Department of Computer Science.
    Transparent concurrent execution of mutually exclusive alternatives1989Ingår i: 9th International Conference on Distributed Computing Systems, IEEE , 1989, s. 44-52Konferensbidrag (Refereegranskat)
    Abstract [en]

    The task of concurrently computing alternative solutions to a problem where only one of the solutions is needed is examined. In this case the rule for selecting between the solutions is faster first, where the first successful alternative is selected. For problems where the required execution time is unpredictable, this method shows substantial execution time performance increases over other methods. In order to test the utility of the design, it is used for two application areas: distributed execution of recovery blocks and OR-parallelism in Prolog. The authors present: (1) a model for selection of alternatives in a sequential setting: (2) a transformation that allows alternatives to execute concurrently; (3) a description of the semantics-preservation mechanism; and (4) parameterization of where the performance improvements can be expected. Additionally, examples of application areas for the method are given.

  • 2707. Soleimanifard, Siavash
    et al.
    Gurov, Dilian
    Algorithmic verification of procedural programs in the presence of code variability2016Ingår i: Science of Computer Programming, ISSN 0167-6423, E-ISSN 1872-7964, Vol. 127, s. 76-102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a generic framework for verifying temporal safety properties of procedural programs that are dynamically or statically configured by replacing, adapting, or adding new components. To deal with such a variability of a program, we require programmers to provide local specifications for its variable components, and verify the global properties by replacing these specifications with maximal models. Our framework is a generalization of a previously developed framework that fully abstracts from program data. In this work, we recapture program data and thus significantly increase the range of properties that can be verified. Our framework is generic by being parametric on the set of observed program events and their semantics. We separate program structure from the behaviour it induces to facilitate independent component specification and verification. To exemplify the use of the framework, we develop three concrete instantiations; in particular, we derive a compositional verification technique for programs written in a procedural language with pointers as the only datatype.

  • 2708.
    Soliman, Amira
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Programvaruteknik och datorsystem, SCS.
    Graph-based Analytics for Decentralized Online Social Networks2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Decentralized Online Social Networks (DOSNs) have been introduced as a privacy preserving alternative to the existing online social networks.  DOSNs remove the dependency on a centralized provider and operate as distributed information management platforms. Current efforts of providing DOSNs are mainly focused on designing the required building blocks for managing the distributed network and supporting the social services (e.g., search, content delivery, etc.). However, there is a lack of reliable techniques for enabling complex analytical services (e.g., spam detection, identity validation, etc.) that comply with the decentralization requirements of DOSNs. In particular, there is a need for decentralized data analytic techniques and machine learning (ML) algorithms that can successfully run on top of DOSNs.

     

    In this thesis, we empower decentralized analytics for DOSNs through a set of novel algorithms. Our algorithms allow decentralized analytics to effectively work on top of fully decentralized topology, when the data is fully distributed and nodes have access to their local knowledge only. Furthermore, our algorithms and methods are able to extract and exploit the latent patterns in the social user interaction networks and effectively combine them with the shared content, yielding significant improvements for the complex analytic tasks. We argue that, community identification is at the core of the learning and analytical services provided for DOSNs. We show in this thesis that knowledge on community structures and information dissemination patterns, embedded in the topology of social networks has a potential to greatly enhance data analytic insights and improve results. At the heart of this thesis lies a community detection technique that successfully extracts communities in a completely decentralized manner. In particular, we show that multiple complex analytic tasks, like spam detection and identity validation,  can be successfully tackled by harvesting the information from the social network structure. This is achieved by using decentralized community detection algorithm which acts as the main building block for the community-aware learning paradigm that we lay out in this thesis. To the best of our knowledge, this thesis represents the first attempt to bring complex analytical services, which require decentralized iterative computation over distributed data, to the domain of DOSNs. The experimental evaluation of our proposed algorithms using real-world datasets confirms the ability of our solutions to generate  efficient ML models in massively parallel and highly scalable manner.

  • 2709.
    Soliman, Amira
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Programvaruteknik och datorsystem, SCS.
    Stad: Stateful Diffusion for Linear Time Community DetectionManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Community detection is one of the preeminent topics in network analysis. Communities in real-world networks vary in their characteristics, such as their internal cohesion and size. Despite a large variety of methods proposed to detect communities so far, most of existing approaches fall into the category of global approaches. Specifically, these global approaches adapt their detection model focusing on approximating the global structure of the whole network, instead of performing approximation at the communities level. Global techniques tune their parameters to "one size fits all" model, so they are quite successful with extracting communities in homogeneous cases but suffer in heterogeneous community size distributions.

    In this paper, we present a stateful diffusion approach (Stad) for community detection that employs diffusion. Stad boosts diffusion with conductance-based function that acts like a tuning parameter to control the diffusion speed. In contrast to existing diffusion mechanisms which operate with global and fixed speed, Stad introduces stateful diffusion to treat every community individually. Particularly, Stad controls the diffusion speed at node level, such that each node determines the diffusion speed associated with every possible community membership independently. Thus, Stad is able to extract communities more accurately in heterogeneous cases by dropping "one size fits all" model. Furthermore, Stad employs a vertex-centric approach which is fully decentralized and highly scalable, and requires no global knowledge. So as, Stad can be successfully applied in distributed environments, such as large-scale graph processing or decentralized machine learning. The results with both real-world and synthetic datasets show that Stad outperforms the state-of-the-art techniques, not only in the community size scale issue but also by achieving higher accuracy that is twice the accuracy achieved by the state-of-the-art techniques.

  • 2710.
    Soliman, Amira
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Girdzijauskas, Sarunas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Adagraph: Adaptive graph-based algorithms for spam detection in social networks2017Ingår i: 5th International Conference on Networked Systems, NETYS 2017, Springer Verlag , 2017, s. 338-354Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the past years, researchers developed approaches to detect spam in Online Social Networks (OSNs) such as URL blacklisting, spam traps and even crowdsourcing for manual classification. Although previous work has shown the effectiveness of using statistical learning to detect spam, existing work employs supervised schemes that require labeled training data. In addition to the heavy training cost, it is difficult to obtain a comprehensive source of ground truth for measurement. In contrast to existing work, in this paper we present AdaGraph that is a novel graph-based approach for spam detection. AdaGraph is unsupervised, hence it diminishes the need of labeled training data and training cost. Particularly, AdaGraph effectively detects spam in large-scale OSNs by analyzing user behaviors using graph clustering technique. Moreover, AdaGraph continuously updates detected communities to comply with users dynamic interactions and activities. Extensive experiments using Twitter datasets show that AdaGraph detects spam with accuracy 92.3%. Furthermore, the false positive rate of AdaGraph is less than 0.3% that is less than half of the rate achieved by the state-of-the-art approaches.

  • 2711.
    Soliman, Amira
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Girdzijauskas, Sarunas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Adaptive Graph-based algorithms for Spam Detection in Social Networks2016Rapport (Övrigt vetenskapligt)
    Abstract [en]

    As Online Social Networks (OSNs) continue to grow in popularity, a spam marketplace has emerged that includes services selling fraudulent accounts, as well as acts as nucleus of spammers who propagate large-scale spam campaigns. In the past years, researchers developed approaches to detect spam such as URL blacklisting, spam traps and even crowdsourcing for manual classification. Although previous work has shown the effectiveness of using statistical learning to detect spam, existing work employs supervised schemes that require labeled training data. In addition to the heavy training cost, it is difficult to obtain a comprehensive source of ground truth for measurement. In contrast to existing work, in this paper we present a novel graph-based approach for spam detection. Our approach is unsupervised, hence it diminishes the need of labeled training data and training cost. Particularly, our approach can effectively detect the spam in large-scale OSNs by analyzing user behaviors using graph clustering technique. Moreover, our approach continuously updates detected communities to comply with dynamic OSNs where interactions and activities are evolving rapidly. Extensive experiments using Twitter datasets show that our approach is able to detect spam with accuracy 92.3\%. Furthermore, our approach has false positive rate that is less than 0.3\% that is less than half of the rate achieved by the state-of-the-art approaches.

  • 2712.
    Soliman, Amira
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Programvaruteknik och datorsystem, SCS. Royal Institute of Technology (KTH).
    Rahimian, Fatemeh
    RISE SICS.
    Girdzijauskas, Sarunas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Programvaruteknik och datorsystem, SCS. Royal Institute of Technology (KTH).
    Stad: Stateful Diffusion for Linear Time Community Detection2018Ingår i: 38th IEEE International Conference on Distributed Computing Systems, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Community detection is one of the preeminent topics in network analysis. Communities in real-world networks vary in their characteristics, such as their internal cohesion and size. Despite a large variety of methods proposed to detect communities so far, most of existing approaches fall into the category of global approaches. Specifically, these global approaches adapt their detection model focusing on approximating the global structure of the whole network, instead of performing approximation at the communities level. Global techniques tune their parameters to “one size fits all” model, so they are quite successful with extracting communities in homogeneous cases but suffer in heterogeneous community size distributions. In this paper, we present a stateful diffusion approach (Stad) for community detection that employs diffusion. Stad boosts diffusion with a conductance-based function that acts like a tuning parameter to control the diffusion speed. In contrast to existing diffusion mechanisms which operate with global and fixed speed, Stad introduces stateful diffusion to treat every community individually. Particularly, Stad controls the diffusion speed at node level, such that each node determines the diffusion speed associated with every possible community membership independently. Thus, Stad is able to extract communities more accurately in heterogeneous cases by dropping “one size fits all” model. Furthermore, Stad employs a vertex-centric approach which is fully decentralized and highly scalable, and requires no global knowledge. So as, Stad can be successfully applied in distributed environments, such as large-scale graph processing or decentralized machine learning. The results with both real-world and synthetic datasets show that Stad outperforms the state-of-the-art techniques, not only in the community size scale issue but also by achieving higher accuracy that is twice the accuracy achieved by the state-of-the-art techniques.

  • 2713.
    Sommestad, Teodor
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    A framework and theory for cyber security assessments2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Informationsteknik (IT) är kritiskt och värdefullt för vårt samhälle. En viktig typ av IT-system är de styrsystem som ofta kallas SCADA-system (från engelskans "Supervisor Control And Data Acquisition"). Dessa system styr och övervakar fysiska industriella processer så som kraftförsörjning, vattenförsörjning och järnvägstransport. Eftersom vårt samhälle är beroende av dessa industriella processer så är vi också beroende av våra SCADA-systems beteende. SCADA-system har blivit (och fortsätter bli) integrerade med andra IT system och blir därmed mer sårbara för cyberhot. Beslutsfattare behöver utvärdera säkerheten som en systemarkitektur erbjuder för att kunna fatta informerade beslut rörande dess lämplighet. Men datainsamlingskostnader begränsar ofta hur mycket information som kan samlas in om ett SCADA-systems arkitektur och det är svårt för en beslutsfattare att veta hur viktiga olika variabler är eller vad deras värden betyder för SCADA-systemets säkerhet.

    Bidraget i denna avhandling är ett modelleringsramverk och en teori för att stödja cybersäkerhetsutvärderingar. Det har ett särskilt focus på SCADA-system. Avhandlingen är av sammanläggningstyp och består av sex artiklar. Artikel A beskriver en mall för hur probabilistiska relationsmodeller kan användas för att koppla samman cybersäkerhetsteori med arkitekturmodeller. Artikel B till E bidrar med teori inom operationell säkerhet. Mer exakt, de bidrar med teori angående: upptäckt av mjukvarusårbarheter (artikel B), fjärrexekvering av godtycklig kod (artikel C), intrångsdetektering (artikel D) och attacker mot tillgänglighet (artikel E). Artikel F beskriver hur bidraget i artikel A kombineras med bidragen i artikel B till E och annan operationell cybersäkerhetsteori. Resultatet är ett beslutsstödsverktyg kallat Cyber Security Modeling Language (CySeMoL). Beslutsstödsverktyget producerar sårbarhetsutvärdering för ett system baserat på en arkitekturmodell av det.

  • 2714.
    Sommestad, Teodor
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Ekstedt, Mathias
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Holm, Hannes
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    The Cyber Security Modeling Language: A Tool for Assessing the Vulnerability of Enterprise System Architectures2013Ingår i: IEEE Systems Journal, ISSN 1932-8184, E-ISSN 1937-9234, Vol. 7, nr 3, s. 363-373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cyber security modeling language (CySeMoL) is a modeling language for enterprise-level system architectures coupled to a probabilistic inference engine. If the computer systems of an enterprise are modeled with CySeMoL, this inference engine can assess the probability that attacks on the systems will succeed. The theory used for the attack-probability calculations in CySeMoL is a compilation of research results on a number of security domains and covers a range of attacks and countermeasures. The theory has previously been validated on a component level. In this paper, the theory is also validated on a system level. A test indicates that the reasonableness and correctness of CySeMoL assessments compare with the reasonableness and correctness of the assessments of a security professional. CySeMoL's utility has been tested in case studies.

  • 2715.
    Sommestad, Teodor
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Holm, Hannes
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Ekstedt, Mathias
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Honeth, Nicholas
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Quantifying the effectiveness of intrusion detection systems in operation through domain expertsArtikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    An intrusion detection system is a security measure that can help system administrators in enterprise environments to detect attacks made against networks and their hosts. Evaluating the effectiveness of IDSs by experiments or observations is however difficult and costly. This paper describes the result of a study where 165 domain experts in the intrusion detection field estimated the effectiveness of 24 different scenarios pertaining to detection of remote arbitrary code exploits.

  • 2716.
    Sommestad, Teodor
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Holm, Hannes
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Ekstedt, Mathias
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Honeth, Nicholas
    KTH, Skolan för elektro- och systemteknik (EES), Industriella informations- och styrsystem.
    Quantifying the Effectivenness of Intrusion Detection Systems in Operation through Domain Experts2014Ingår i: Journal of Information System Security, ISSN 1551-0123, E-ISSN 1551-0808, Vol. 10, nr 2, s. 3-35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An intrusion detection system (IDS) is a security measure that can help system administrators in enterprise environments detect attacks made against computer networks. In order to be a good enterprise security measure, the IDS solution should be effective when it comes to making system operators aware of on-going cyber-attacks. However, it is difficult and costly to evaluate the effectiveness of IDSs by experiments or observations. This paper describes the result of an alternative approach to studying this topic. The effectiveness of 24 different IDS solution scenarios pertaining to remote arbitrary code exploits is evaluated by 165 domain experts. The respondents’ answers were then combined according to Cooke’s classical method, in which respondents are weighted based on how well they perform on a set of test questions. Results show that the single most important factor is whether either a host-based IDS, or a network-based IDS is in place. Assuming that either one or the other is in place, the most important course of action is to tune the IDS to its environment. The results also show that an updated signature database influences the effectiveness of the IDS less than if the vulnerability that is being exploited is well-known and is possible to patch or not.

  • 2717. Sommestad, Teodor
    et al.
    Sandström, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    An empirical test of the accuracy of an attack graph analysis tool2015Ingår i: Information & Computer Security, ISSN 2056-4961, Vol. 23, nr 5, s. 516-531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - The purpose of this paper is to test the practical utility of attack graph analysis. Attack graphs have been proposed as a viable solution to many problems in computer network security management. After individual vulnerabilities are identified with a vulnerability scanner, an attack graph can relate the individual vulnerabilities to the possibility of an attack and subsequently analyze and predict which privileges attackers could obtain through multi-step attacks (in which multiple vulnerabilities are exploited in sequence).

    Design/methodology/approach - The attack graph tool, MulVAL, was fed information from the vulnerability scanner Nexpose and network topology information from 8 fictitious organizations containing 199 machines. Two teams of attackers attempted to infiltrate these networks over the course of two days and reported which machines they compromised and which attack paths they attempted to use. Their reports are compared to the predictions of the attack graph analysis.

    Findings - The prediction accuracy of the attack graph analysis was poor. Attackers were more than three times likely to compromise a host predicted as impossible to compromise compared to a host that was predicted as possible to compromise. Furthermore, 29 per cent of the hosts predicted as impossible to compromise were compromised during the two days. The inaccuracy of the vulnerability scanner and MulVAL's interpretation of vulnerability information are primary reasons for the poor prediction accuracy.

    Originality/value - Although considerable research contributions have been made to the development of attack graphs, and several analysis methods have been proposed using attack graphs, the extant literature does not describe any tests of their accuracy under realistic conditions.

  • 2718.
    Song, Qunying
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Shen, Hui
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Intelligent Voice Assistant2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This project includes an implementation of an intelligent voice recognition assistant for Android where functionality on current existing applications on other platforms is compared. Until this day, there has not been any good alternative for Android, so this project aims to implement a voice assistant for the Android platform while describing the difficulties and challenges that lies in this task.

  • 2719.
    Sonntag, Dag
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    A Study of Chain Graph Interpretations2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Probabilistic graphical models are today one of the most well used architectures for modelling and reasoning about knowledge with uncertainty. The most widely used subclass of these models is Bayesian networks that has found a wide range of applications both in industry and research. Bayesian networks do however have a major limitation which is that only asymmetric relationships, namely cause and eect relationships, can be modelled between its variables. A class of probabilistic graphical models that has tried to solve this shortcoming is chain graphs. It is achieved by including two types of edges in the models, representing both symmetric and asymmetric relationships between the connected variables. This allows for a wider range of independence models to be modelled. Depending on how the second edge is interpreted this has also given rise to dierent chain graph interpretations.

    Although chain graphs were first presented in the late eighties the field has been relatively dormant and most research has been focused on Bayesian networks. This was until recently when chain graphs got renewed interest. The research on chain graphs has thereafter extended many of the ideas from Bayesian networks and in this thesis we study what this new surge of research has been focused on and what results have been achieved. Moreover we do also discuss what areas that we think are most important to focus on in further research.

  • 2720.
    Sonntag, Dag
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Chain Graphs: Interpretations, Expressiveness and Learning Algorithms2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Probabilistic graphical models are currently one of the most commonly used architectures for modelling and reasoning with uncertainty. The most widely used subclass of these models is directed acyclic graphs, also known as Bayesian networks, which are used in a wide range of applications both in research and industry. Directed acyclic graphs do, however, have a major limitation, which is that only asymmetric relationships, namely cause and effect relationships, can be modelled between their variables. A class of probabilistic graphical models that tries to address this shortcoming is chain graphs, which include two types of edges in the models representing both symmetric and asymmetric relationships between the variables. This allows for a wider range of independence models to be modelled and depending on how the second edge is interpreted, we also have different so-called chain graph interpretations.

    Although chain graphs were first introduced in the late eighties, most research on probabilistic graphical models naturally started in the least complex subclasses, such as directed acyclic graphs and undirected graphs. The field of chain graphs has therefore been relatively dormant. However, due to the maturity of the research field of probabilistic graphical models and the rise of more data-driven approaches to system modelling, chain graphs have recently received renewed interest in research. In this thesis we provide an introduction to chain graphs where we incorporate the progress made in the field. More specifically, we study the three chain graph interpretations that exist in research in terms of their separation criteria, their possible parametrizations and the intuition behind their edges. In addition to this we also compare the expressivity of the interpretations in terms of representable independence models as well as propose new structure learning algorithms to learn chain graph models from data.

  • 2721.
    Sonntag, Dag
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Peña, Jose M.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Learning Multivariate Regression Chain Graphs under Faithfulness2012Ingår i: Proceedings of the 6th European Workshop on Probabilistic Graphical Models, Granada (Spain), 19-21 September, 2012 / [ed] Andrés Cano, Manuel Gémez.-Olmedo and Thomas D. Nielsen, 2012, s. 299-306Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper deals with multivariate regression chain graphs, which were introduced by Cox and Wermuth (1993, 1996) to represent linear causal models with correlated errors. Specifically, we present a constraint based algorithm for learning a chain graph a given probability distribution is faithful to. We also show that for each Markov equivalence class of multivariate regression chain graphs there exists a set of chain graphs with a unique minimal set of lines. Finally, we show that this set of lines can be identified from any member of the class by repeatedly splitting its connectivity components according to certain conditions.

  • 2722.
    Sorici, Alexandru
    et al.
    University Politehnica of Bucharest, Romania.
    Awada, Imad Alex
    University Politehnica of Bucharest, Romania.
    Kunnappilly, Ashalatha
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mocanu, Irina
    University Politehnica of Bucharest, Romania.
    Cramariuc, Oana
    IT Cenetr for Science and Technology, Romania.
    Malicki, Lukasz
    Knowledge Society Association, Poland.
    Seceleanu, Cristina
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Florea, Adina Magda
    University Politehnica of Bucharest.
    CAMI - An Integrated Architecture Solution for Improving Quality of Life of the Elderly2016Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The increasing ageing population worldwide imposes some new challenges to the society like the provision of dependable support while facing a shortage in the numbers of caregivers, increased health costs and the emergence of new diseases. As such there is a great demand for technologies that support the independent and safe living of the elderly and ensuring that they are not socially isolated. Ambient Assisted Living (AAL) technologies have thus emerged to support the elderly people in their daily activities, while removing the need of caregivers being always physically present in order to look after the elderly. The current AAL systems are intelligent enough to take critical decisions in emergency situations like a fall, fire or a cardiac arrest, hence the elderly can live safely and independently. In this abstract, we describe our solution that aims at integrating all relevant functionalities of an AAL system, based on feedback collected from representative users. This work is carried out in the European Union project called CAMI (Artificially intelligent ecosystem for self-management and sustainable quality of life in AAL).

  • 2723.
    Sormain, Rémi
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Offline H.264 encoding method for omnidirectional videos with empirical region-of-interest2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Panoramisk virtuell verklighet (VR) är en kommande teknik som nyligen har mött intresse från forskarsamhället och vanliga konsumenter. Det gör det möjligt för användarna att fördjupa sig i videor upptagna från flera riktningar, med hjälp av ett VR-headset : tack vare ett växande antal billiga och huvudburna bildskärmar, erbjuder alla nya smarttelefoner en passande panoramisk VR-erfarenhet. Men på grund av den breda synvinkeln i flerriktade media behöver videor med 360 graders synfält stor upplösning och därför höga bithastigheter.

    Detta masterexamensarbete som utförts på RE’FLEKT GmbH är ett utforskande arbete som strävar efter att reducera panoramabildens bithastighet. I flerriktade videoklipp kan användaren bara se en del av varje bildruta, härigenom får somliga zoner mer uppmärksamhet än andra. Syftet med denna studie är att introducera begreppet region-av-intresse (ROI) kodning i panoramisk VR. Huvudbidraget är en metod för att koda panoramisk video i en H.264-ström med en varierande nivå av detaljer som beror på de zoner som får mest av tittarnas intresse. Först detekteras ROI genom en huvudspårningsmodul kombinerad med en gaussisk uppmärksamhetsmodell. Därefter kodas referensvideoen med x264-kodaren (öppen källkod) med hjälp av ROI-informationen. ITU-standardens subjektiva test visar att den här metoden kan fungera bättre än klassisk H.264-kodning i enskilda fall.

  • 2724.
    Sotomane, Constantino
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Factors affecting the use of data mining in Mozambique: Towards a framework to facilitate the use of data mining2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Advances in technology have enabled organizations to collect a variety ofdata at high speed and provided the capacity to store them. As a result theamount of data available is increasing daily at a rapid rate. The data stored inorganizations hold important information to improve decision making andgain competitive advantage. To extract useful information from these hugeamounts of data, special techniques such as data mining are required. Datamining is a technique capable of extracting useful knowledge from vastamounts of data. The successful application of data mining in organizationsdepends on several factors that may vary in relation to the environment. InMozambique, these factors have never been studied. The study of the factorsaffecting the use of data mining is important to determine which aspectsrequire special attention for the success of the application of data mining.This thesis presents a study of the level of awareness and use of datamining in Mozambique and the factors affecting its use. It is a step towardsthe development of a framework to facilitate the application of data miningin Mozambique. The study is exploratory and uses multiple case studies intwo institutions in Maputo city, the capital of Mozambique, one in the areaof agriculture and the other in the field of electricity, and of Maputo citymore broadly. The study involved a combination of observations, focusgroup discussions and enquiries directed at managers and practitioners onaspects of information technology (IT) and data analysis. The results of the study reveal that the level of awareness and use of datamining in Mozambique is still very weak. Only a limited number ofprofessionals in IT are aware of the concept or its uses. The main factorsaffecting the use of data mining in Mozambique are: the quality, availabilityand integration of, access to data, skill in data mining, functional integration,alignment of IT and business, interdisciplinary learning, existence ofchampions, commitment of top management, existence of changemanagement, privacy, cost and the availability of technology. Threeapplications were developed in two real settings, which showed that thereare problems to be solved with data mining. The two examples in the area ofelectricity demonstrate how data mining is used to develop models toforecast electricity consumption and how they can enhance the estimation ofelectricity to be sold to the international market. The application in the areaof agriculture extracts associations between the characteristics of smallfarmers and the yield of maize from a socioeconomic database with hundreds of attributes. The applications provide practical examples of howdata mining can help to discover patterns that can lead to the development ofmore accurate models and find interesting associations between variables inthe dataset. The factors identified in this thesis can be used to determine thefeasibility of the implementation of data mining projects and ensure itssuccess.

  • 2725.
    Sotsenko, Alisa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    A Rich Context Model: Design and Implementation2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The latest developments of mobile devices include a variety of hardware features that allow for more rich data collection and services. Numerous sensors, Internet connectivity, low energy Bluetooth connectivity to other devices (e.g., smart watches, activity tracker, health data monitoring devices) are just some examples of hardware that helps to provide additional information that can be beneficially used for many application domains. Among others, they could be utilized in mobile learning scenarios (for data collection in science education, field trips), in mobile health scenarios (for health data collection and monitoring the health state of patients, changes in health conditions and/or detection of emergency situations), and in personalized recommender systems. This information captures the current context situation of the user that could help to make mobile applications more personalized and deliver a better user experience. Moreover, the context related information collected by the mobile device and the different applications can be enriched by using additional external information sources (e.g., Web Service APIs), which help to describe the user’s context situation in more details.

    The main challenge in context modeling is the lack of generalization at the core of the model, as most of the existing context models depend on particular application domains or scenarios. We tackle this challenge by conceptualizing and designing a rich generic context model. In this thesis, we present the state of the art of recent approaches used for context modeling and introduce a rich context model as an approach for modeling context in a domain-independent way. Additionally, we investigate whether context information can enhance existing mobile applications by making them sensible to the user’s current situation. We demonstrate the reusability and flexibility of the rich context model in a several case studies. The main contributions of this thesis are: (1) an overview of recent, existing research in context modeling for different application domains; (2) a theoretical foundation of the proposed approach for modeling context in a domain-independent way; (3) several case studies in different mobile application domains.

  • 2726.
    Sotsenko, Alisa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Exploring Different Use Cases for a Rich Context Model for Mobile Applications2015Ingår i: Proceedings of Doctoral Symposium of the 9th International and Interdisciplinary Conference on Modeling and Using Context (CONTEXT 2015) / [ed] Peter Werner Eklund & Rebekeh Wegener, 2015, Vol. 1537, s. 23-31Konferensbidrag (Refereegranskat)
    Abstract [en]

     Substantial research in the field of context modeling has explored aspects related to the use of contextualization in various mobile scenarios. The current context of a mobile user has been often limited to his/her current position, neglecting the possibilities offered by modern mobile devices of providing a much richer representation of the current user’s context. This research aims to improve the usability of users’ context in the mobile software development process. Therefore, this paper presents the proposal of a rich context model (RCM) as general approach for context modeling to explore the context of the users in different application domains.

  • 2727.
    Sotsenko, Alisa
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Jansen, Marc
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Milrad, Marcelo
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Using a Rich Context Model for People-to-People Recommendation2015Ingår i: 2015 3rd International Conference on Future Internet of Things and Cloud (FiCloud), 24-26 Aug. 2015, Rome, IEEE, 2015, s. 703-708Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present an approach for People- to-People recommendations based on a Rich Context Model (RCM). We consider personal user information as contextual information used for our recommendations. The evaluation of our recommendation approach was performed on a social network of students. The obtained results do show a significant increase in performance while, at the same time, a slight increase in quality in comparison to a manual matching process. The proposed approach is flexible enough to handle different data types of contextual information and easy adaptable to other recommendation domains. 

  • 2728.
    Sotsenko, Alisa
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Zbick, Janosch
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Jansen, Marc
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Milrad, Marcelo
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Contextualization of Mobile Learners2015Ingår i: Mobile Learning: Trends, Attitudes and Effectiveness / [ed] Mohamed Hamada, Nova Science Publishers, Inc., 2015, s. 39-54Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This chapter describes our current research efforts related to the contextualization of learners in mobile learning activities. Substantial research in the field of mobile learning has explored aspects related to contextualized learning scenarios. However, new ways of interpretation and consideration of contextual information of mobile learners are necessary. This chapter provides an overview regarding the state of the art of innovative approaches for supporting contextualization in mobile learning. Additionally, we provide the description of the design and implementation of a flexible multi-dimensional vector space model to organize and process contextual data together with visualization tools for further analysis and interpretation. We also present a study with outcomes and insights on the usage of the contextualization support for mobile learners. To conlcude, we discuss the benefits of using contextualization models for learners in different use-cases. Moreover, a description is presented in order to illustrate how the proposed contextual model can easily be adapted and reused for different use-cases in mobile learning scenarios and potentially other mobile fields.

  • 2729.
    Sotsenko, Alisa
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Zbick, Janosch
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Jansen, Marc
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME). University of Applied Sciences Ruhr West, Germany.
    Milrad, Marcelo
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för medieteknik (ME).
    Flexible and Contextualized Cloud Applications for Mobile Learning Scenarios2016Ingår i: Mobile, Ubiquitous, and Pervasive Learning: Fundaments, Applications, and Trends / [ed] Alejandro Peña-Ayala, Springer Publishing Company, 2016, s. 167-192Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This chapter describes our research efforts related to the design of mobile learning (m-learning) applications in cloud-computing (CC) environments. Many cloud-based services can be used/integrated in m-learning scenarios, hence, there is a rich source of applications that could easily be applied to design and deploy those within the context of cloud-based services. Here, we present two cloud-based approaches—a flexible framework for an easy generation and deployment of mobile learning applications for teachers, and a flexible contextualization service to support personalized learning environment for mobile learners. The framework provides a flexible approach that supports teachers in designing mobile applications and automatically deploys those in order to allow teachers to create their own m-learning activities supported by mobile devices. The contextualization service is proposed to improve the content delivery of learning objects (LOs). This service allows adapting the learning content and the mobile user interface (UI) to the current context of the user. Together, this leads to a powerful and flexible framework for the provisioning of potentially ad hoc mobile learning scenarios. We provide a description of the design and implementation of two proposed cloud-based approaches together with scenario examples. Furthermore, we discuss the benefits of using flexible and contextualized cloud applications in mobile learning scenarios. Hereby, we contribute to this growing field of research by exploring new ways for designing and using flexible and contextualized cloud-based applications that support m-learning.

  • 2730.
    Spiess, Norbert
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för datavetenskap (DV).
    Realisation of a framework for the analysis of business processes2013Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Companies structure their work to be done using business processes. A widely used modeling language is BPMN which provides a standardized graphical notation and execution semantics. But studies show that many business processes contain logical errors. The detection of these errors priorly to the execution can save money and effort.

    A wide range of structural analysis methods for business processes exist that transform business processes into Petri nets or workflow graphs. But the analyses are either very slow or lack in the detection of all errors and their details. At the Friedrich Schiller University, a new workflow graph based approach is under development that promises a fast analysis, the detection of all errors and specific details to these errors.

    The aim of this thesis was to realise a framework that combines the modelling and analysis of business processes in BPMN. The framework should transform business processes into workflow graphs and analyse them dynamically while they are modelled. Analyses are supposed to be easily introducable. Another aspect was the enrichment of the BPMN diagram with process data that can be included into analyses too.

    The designed framework provides a simple interface to add new analyses or transformations. Analyses can share data independent of workflow graphs, define execution conditions and therefore define dependencies to other analyses. The transformation transforms BPMN diagrams always into analysable workflow graphs through several correction patterns that follow the BPMN semantics.

  • 2731.
    Spiliopoulos, Vasileios
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Bagdia, Akash
    Hansson, Andreas
    Aldworth, Peter
    Kaxiras, Stefanos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Introducing DVFS-Management in a Full-System Simulator2013Ingår i: Proc. 21st International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, IEEE Computer Society, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dynamic Voltage and Frequency Scaling (DVFS) is an essential part of controlling the power consumption of any computer system, ranging from mobile phones to servers. DVFS efficiency relies on hardware-software co-optimization, thus using existing hardware cannot reveal the full optimization potential beyond the current implementation’s characteristics. To explore the vast design space for DVFS efficiency, that straddles software and hardware, a simulation infrastructure must provide features that are not readily available today, for example: software controllable clock and voltage domains, support for the OS and the frequency scaling module of it, and an online power estimation methodology. As the main contribution,this work enables DVFS studies in a full-system simulator. We extend the gem5 simulator to support full-system DVFS modeling. By doing so, we enable energy-efficiency experiments to be performed in gem5 and we showcase such studies. Finally, we show that both existing and novel frequency governors for Linux and Android can be effortlessly integrated in the framework, and we evaluate the efficiency of different DVFS schemes.

  • 2732.
    Spiliopoulos, Vasileios
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Sembrant, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Kaxiras, Stefanos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Power-Sleuth: A Tool for Investigating your Program's Power Behavior2012Ingår i: International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS'12), 2012, s. 241-250Konferensbidrag (Refereegranskat)
    Abstract [en]

    Modern processors support aggressive power saving techniques to reduce energy consumption. However, traditional profiling techniques have mainly focused on performance, which does not accurately reflect the power behavior of applications. For example, the longest running function is not always the most energy-hungry function. Thus software developers cannot always take full advantage of these power-saving features.

    We present \powersleuth, a power/performance estimation tool which is able to provide a full description of an application's behavior for any frequency from a single profiling run. The tool combines three techniques: a power and a performance estimation model with a program phase detection technique to deliver accurate, per-phase, per-frequency analysis.

    Our evaluation (against real power measurements) shows that we can accurately predict power and performance across different frequencies with average errors of 3.5% and 3.9% respectively.

  • 2733.
    Srinivasan, Jayakanth
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Studying Customer-Supplier Relationships in Global Software Development2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    The preliminary argument used by most organizations that choose to source their software from other organizations is the perceived cost savings. The nature of the relationship between the customer and supplier has to necessarily evolve in order for it to remain mutually beneficial over the long run, i.e., the 'arms-length' relationship becomes one of strategic partnering. Studying this evolving relationship requires a set of methods that capture the context within which these organizations exist, make explicit the gap (if any) between the actual and articulated nature of the relationship between the two organizations, and can be used to create some useful constructs for managing/ evolving the relationship. This paper illustrates how the paradigm of engaged scholarship has been applied to studying the EuroTel-IndiaCo relationshi

  • 2734.
    Srinivasan, Jayakanth
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lundqvist, Kristina
    Mälardalens högskola, Akademin för innovation, design och teknik.
    A Constructivist Approach to teaching Software Processes2007Konferensbidrag (Övrigt vetenskapligt)
  • 2735.
    Srinivasan, Jayakanth
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lundqvist, Kristina
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Driving Open Innovation: Learning from Three Cases2008Ingår i: Workshop on Open Innovation in Services, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 2736.
    Srinivasan, Jayakanth
    et al.
    MIT, USA.
    Lundqvist, Kristina
    MIT, USA.
    Identifying Rate Mismatch through Architecture Transformation2003Ingår i: AIAA/IEEE Digital Avionics Systems Conference - Proceedings, Volume 2, 2003, 2003, s. 6.A.2/1-6.A.2/8Konferensbidrag (Övrigt vetenskapligt)
  • 2737.
    Srinivasan, Jayakanth
    et al.
    MIT, Cambridge, United States .
    Lundqvist, Kristina
    MIT, Cambridge, United States .
    Real-Time Architecture Analysis: A COTS Perspective2002Ingår i: AIAA/IEEE Digital Avionics Systems Conference - Proceedings, Volume 1, 2002, 2002, Vol. 1Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Real-time systems are defined as systems in which the correctness of the system depends not only on the logical correctness of the computation, but also on the time at which the result is produced. Honeywell's choice of the Time Triggered Protocol (TTP) for a low cost avionics bus in 2001, exemplifies the industry trend to using Commercial Off The Shelf (COTS) components to implement real-time systems. The driving factors behind the trend are the introduction of SoC devices (Systems on a Chip) that contain processors, memory, network access, I/O interface, system and application software, and smart MEMS transducers which contain the sensing element, the signal conditioning logic and network access logic on a single silicon die. In this paper, we compare and contrast TTP, FlexRay and MIL-STD-1553 architectures in terms of the basic requirements for a systems bus, namely, network architecture, bus access, message formats, clock synchronization, fault tolerance, error detection and tool support.

  • 2738.
    Stadler, Rolf
    KTH, Skolan för elektro- och systemteknik (EES).
    Protocols for Distributed Embedded Management2012Ingår i: Network-Embedded Management and Applications: Understanding Programmable Networking Infrastructure / [ed] A. Clemm and R. Wolter, Springer Publishing Company, 2012, 1, s. 263-290Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    We survey approaches to distributed management and highlightan architecture that is especially suited for embedded management in a largenetwork. We then discuss in detail two fundamental classes of protocols thatexecute as embedded functions within such an architecture. The rst is theclass of Echo protocols, which can be used for distributed polling, globalstate estimation, resource discovery, and distributed conguration. The sec-ond class is that of GAP protocols, whose main application is continuousreal-time monitoring. Both classes are based on distributed trees, which arecreated during the execution of the protocols. Furthermore, both protocolsperform in-network aggregation of the results from local operations on net-work elements. When presenting the protocols, we discuss their underlyingdistributed algorithms, their performance properties, such as overhead andexecution times, and possible extensions for operational use. We limit thediscussion to a single administrative domain.

  • 2739.
    Stadler, Rolf
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Protocols for Distributed Management2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We survey approaches to distributed management and highlight an architecture thatis especially suited for distributed management in a large network. We then discuss indetail two fundamental classes of protocols that execute within such an architecture.The rst is the class of Echo protocols, which can be used for distributed polling, globalstate estimation, resource discovery, and distributed conguration. The second classis that of GAP protocols, whose main application is continuous real-time monitoring.Both classes are based on distributed trees, which are created during the executionof the protocols. Furthermore, both protocols perform in-network aggregation of theresults from local operations on network elements. When presenting the protocols, wediscuss their underlying distributed algorithms, their performance properties, such asoverhead and execution times, and possible extensions for operational use. We limitthe discussion to a single administrative domain.

  • 2740.
    Standar, Magnus
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för datavetenskap (DV).
    Continuous architecture in a large distributed agile organization: A case study at Ericsson2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Agile practices have become norm, also in large scale organizations. Applying agile methods includes introducing continuous practices, including continuous architecture. For web scale applications microservices is a rising star. This thesis investigates if microservices could be an answer also for embedded systems to tackle the synchronizing problem of many parallel teams.

  • 2741.
    Stanic, Biljana
    et al.
    Mälardalens högskola.
    Afzal, Wasif
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. IS (Embedded Systems).
    Process Metrics are not Bad Predictors of Fault Proneness2017Ingår i: Proceedings - 2017 IEEE International Conference on Software Quality, Reliability and Security Companion, QRS-C 2017, 2017, s. 493-499, artikel-id 8004363Konferensbidrag (Refereegranskat)
    Abstract [en]

    The correct prediction of faulty modules or classes has a number of advantages such as improving the quality of software and assigning capable development resources to fix such faults. There have been different kinds of fault/defect prediction models proposed in literature, but a great majority of them makes use of static code metrics as independent variables for making predictions. Recently, process metrics have gained a considerable attention as alternative metrics to use for making trust-worthy predictions. The objective of this paper is to investigate different combinations of static code and process metrics for evaluating fault prediction performance. We have used publicly available data sets, along with a frequently used classifier, Naive Bayes, to run our experiments. We have, both statistically and visually, analyzed our experimental results. The statistical analysis showed evidence against any significant difference in fault prediction performances for a variety of different combinations of metrics. This reinforced earlier research results that process metrics are as good as predictors of fault proneness as static code metrics. Furthermore, the visual inspection of box plots revealed that the best set of metrics for fault prediction is a mix of both static code and process metrics. We also presented evidence in support of some process metrics being more discriminating than others and thus making them as good predictors to use.

  • 2742.
    Stark, Jesper
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för datavetenskap (DV).
    Mätning, Modellering och Presentation av Testvägar för Fordonsindustrin2013Självständigt arbete på grundnivå (högskoleexamen), 180 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Volvo Construction Equipment i Braås är världsledande inom tillverkning av ramstyrda dumprar. I Braås utförs därför en mängd olika testfall där man kartlägger utfallen genom insamling av data från CAN-bussar i dumpern. Om ett test går fel beskrivs det i en felrapport med tillhörande beskrivning av händelseförloppet. Idag finns det inget enhetligt sätt att visa händelse ihop med position.

    För att analysera insamlad data används idag CANalyzer. Fördelen är att det går att visa insamlad data på ett strukturerat grafiskt sätt. Problemet ligger i att det inte finns någon korrelation mellan position och data.

    Kraven som ställdes på systemet var väldigt otydliga. Därför gjordes en förstudie för att utreda vilken systemutvecklingsmodell som passar det specifika fallet med flera aktörer bäst. Det visade sig att \emph{Scrum} passar syftet väldigt bra. Scrum underlättar för förändringar i kravspecifikationer samtidigt som det blir enkelt att kommunicera information mellan klienter.

    User stories används för att fånga de olika aktörernas krav på en hög nivå. Där efter bryts kraven ner i mer specifika tasks. Dessa task är så pass detaljerade att de möjliggör för en mjukvaru-implementering.

    Google Earth erbjuder möjligheten att visa geodetisk data på en 3D-modellerad version av jorden. För att kunna visa insamlad data i Google Earth måste det konverteras till rätt format. Som en demonstration skapas en enkel prototyp applikation för att konvertera insamlad data från en Excelfil(komma-separerad).

  • 2743.
    Staron, Mirolaw
    et al.
    University of Gothenburg.
    Hansson, JörgenHögskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.Bosch, JanChalmers University of Technology.
    Performance in software development – Special issue editorial2014Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 2744.
    Staron, Miroslaw
    et al.
    University of Gothenburg.
    Hansson, Jörgen
    Högskolan i Skövde, Institutionen för informationsteknologi. Högskolan i Skövde, Forskningscentrum för Informationsteknologi.
    Bosch, Jan
    Chalmers University of Technology.
    Performance in software development – Special issue editorial2014Ingår i: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 56, nr 5, s. 463-464s. 463-464Artikel i tidskrift (Refereegranskat)
  • 2745.
    Stavström, Marcus
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Evaluation of FPGA based Test Systems2015Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This master thesis report covers an investigation of how FPGA based hardware can be used to create customizable measurement instruments, for test of electrical equipment in JAS 39 Gripen. The investigation is done at Saab Support and Services in Arboga.

    Electrical equipment are gradually replacing functions, which previously have been obtained by other systems, in safety critical environments. Since the functions are safety critical, they require regular testing in order to verify proper operation. The aircraft JAS 39 Gripen, which is manufactured and developed by Saab, is an example of such system. Proper operation of the avionics in it are essential in order to maintain flying safety.

    There already exist systems today that can verify the functionality of electronics in JAS 39 Gripen. However, there are a number of scenarios where those test systems are somewhat inflexible. More flexible test systems are often desired. This flexibility can be obtained by using congurable hardware, suggestively with FPGAs. This approach is investigated in this master thesis.

  • 2746.
    Stavåker, Kristian
    Linköpings universitet, Institutionen för datavetenskap, PELAB - Laboratoriet för programmeringsomgivningar. Linköpings universitet, Tekniska högskolan.
    Contributions to Parallel Simulation of Equation-Based Models on Graphics Processing Units2011Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis we investigate techniques and methods for parallel simulation of equation-based, object-oriented (EOO) Modelica models on graphics processing units (GPUs). Modelica is being developed through an international effort via the Modelica Association. With Modelica it is possible to build computationally heavy models; simulating such models however might take a considerable amount of time. Therefor techniques of utilizing parallel multi-core architectures for simulation are desirable. The goal in this work is mainly automatic parallelization of equation-based models, that is, it is up to the compiler and not the end-user modeler to make sure that code is generated that can efficiently utilize parallel multi-core architectures. Not only the code generation process has to be altered but the accompanying run-time system has to be modified as well. Adding explicit parallel language constructs to Modelica is also discussed to some extent. GPUs can be used to do general purpose scientific and engineering computing. The theoretical processing power of GPUs has surpassed that of CPUs due to the highly parallel structure of GPUs. GPUs are, however, only good at solving certain problems of data-parallel nature. In this thesis we relate several contributions, by the author and co-workers, to each other. We conclude that the massively parallel GPU architectures are currently only suitable for a limited set of Modelica models. This might change with future GPU generations. CUDA for instance, the main software platform used in the thesis for general purpose computing on graphics processing units (GPGPU), is changing rapidly and more features are being added such as recursion, function pointers, C++ templates, etc.; however the underlying hardware architecture is still optimized for data-parallelism.

  • 2747.
    Steiner, Wilfried
    et al.
    TTTech Computertechnik AG, Austria.
    Gutiérrez, Marina
    TTTech Computertechnik AG, Austria.
    Matyas, Zoltan
    TTTech Hungary Kft., Budapest, Hungary.
    Pozo Pérez, Francisco Manuel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Rodriguez-Navas, Guillermo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Current Techniques, Trends and New Horizons In Avionics Networks Configuration2015Ingår i: Digital Avionics Systems Conference DASC-34, 2015Konferensbidrag (Övrigt vetenskapligt)
  • 2748.
    Steiner, Wilfried
    et al.
    TTTech Computertechnik AG, Austria.
    Gutiérrez Peón, Pablo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. TTTech Computertechnik AG, Austria.
    Gutiérrez, Marina
    TTTech Computertechnik AG, Austria.
    Mehmed, Ayhan
    TTTech Computertechnik AG, Austria.
    Rodriguez-Navas, Guillermo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lisova, Elena
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Pozo Pérez, Francisco Manuel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Next Generation Real-Time Networks Based on IT Technologies2016Ingår i: 21st IEEE Conference on Emerging Technologies and Factory Automation ETFA'16, 2016, s. Article number 7733580-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ethernet-based networks have found their way into industrial communication more than a decade ago. However, while industry and academia developed Ethernet variants to also meet real-time and fault-tolerant requirements, recent standardization efforts within the IEEE 802 will broadly bring standard IT switched Ethernet in future industrial communication networks. As first standards of IEEE 802.1 time-sensitive networking (TSN) are becoming published at the time of this writing, we review these standards and formulate further research challenges that still go beyond current standard developments. Furthermore, we report on recent research results from the RetNet project that target these research challenges.

  • 2749.
    Steiner, Wilfried
    et al.
    TTTech Computertechnik AG, Vienna, Austria.
    Mehmed, Ayhan
    TTTech Computertechnik AG, Vienna, Austria.
    Punnekkat, Sasikumar
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Improving Intelligent Vehicle Dependability By Means of Infrastructure-Induced Tests2015Ingår i: Proceedings - 2015 45th Annual IEEE/IFIP International Conference on Dependable Systems and Networks Workshops, DSN-W 2015, 2015, s. 147-152Konferensbidrag (Refereegranskat)
    Abstract [en]

    Advanced driver assistance systems (ADAS) take over more and more driving responsibilities from the human operator and, therefore, evolve into safety-critical systems. Thus, the dependability of such systems is of up-most importance. While upcoming automobiles themselves will implement fault-tolerance and robustness mechanisms, it can be beneficial to also take infrastructure measures into account when assessing the overall vehicle dependability. In this paper we discuss an example of an infrastructure measure that targets to improve the dependability of an on-board computer vision system. Based on this example we outline a cyber-physical systems (CPS) architecture for intelligent vehicles and address open research directions.

  • 2750.
    Steinle, Mirko
    et al.
    Ecole Polytechnique Federale de Lausanne.
    Aberer, Karl
    Ecole Polytechnique Federale de Lausanne.
    Girdzijauskas, Sarunas
    Ecole Polytechnique Federale de Lausanne.
    Lovis, Christian
    Geneva University Hospitals (HUG).
    Mapping Moving Landscapes by Mining Mountains of Logs: Novel Techniques for Dependency Model Generation2006Ingår i: The 32nd International Conference on Very Large Data Bases, September 12-15, 2006, Seoul, Korea., 2006, s. 1093-1102Konferensbidrag (Refereegranskat)
    Abstract [en]

    Problem diagnosis for distributed systems is usually difficult. Thus, an automated support is needed to identify root causes of encountered problems such as performance lags or inadequate functioning quickly. The many tools and techniques existing today that perform this task rely usually on some dependency model of the system. However, in complex and fast evolving environments it is practically unfeasible to keep such a model up-to-date manually and it has to be created in an automatic manner. For high level objects this is in itself a challenging and less studied task. In this paper, we propose three different approaches to discover dependencies by mining system logs. Our work is inspired by a recently developed data mining algorithm and techniques for collocation extraction from the natural language processing field. We evaluate the techniques in a case study for Geneva University Hospitals (HUG) and perform large-scale experiments on production data. Results show that all techniques are capable of finding useful dependency information with reasonable precision in a real-world environment.

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