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  • 101.
    Metsch, Thijs
    et al.
    Intel Labs Europe, Intel Ireland.
    Ibidunmoye, Olumuyiwa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bayon-Molino, Victor
    Intel Labs Europe, Intel Ireland.
    Butler, Joe
    Intel Labs Europe, Intel Ireland.
    Hernández-Rodriguez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Apex lake: a framework for enabling smart orchestration2015Ingår i: Proceedings of the Industry Track of the 16th ACM/IFIP/USENIX Middleware Conference, New York, USA: Association for Computing Machinery (ACM), 2015, s. 1-7, artikel-id 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    The introduction of a Software-defined infrastructures brings additional challenges to the management of cloud infrastructure. With the impending convergence of telecommunications and cloud infrastructures, datacenters become an essential part of an overall integrated environment. The potential scale of such environments has significant implications as traditional orchestration approaches cannot scale appropriately. However, the combination of infrastructure topology, fine-grained operational data and advanced analytics, has the potential to deliver a scalable approach to facilitate orchestration and resource management. In this paper we introduce Apex Lake, a framework designed to address the question of "how to efficiently define and maintain a physical and logical resource and service landscape enriched by operational data, to support orchestration for optimized service delivery?" We also demonstrate with a use-case illustrating how functionalities provided by Apex Lake can be used dealing with performance anomalies.

  • 102.
    Morveli Espinoza, Mariela
    et al.
    UTFPR, Curitiba, Brazil.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Possebom, Ayslan T.
    UTFPR, Curitiba, Brazil.
    Puyol-Gruart, Josep
    IIIA-CSIC, Barcelona, Spain.
    Tacla, Cesar Augusto
    UTFPR, Curitiba, Brazil.
    Resolving Incompatibilities between Procedural Goals: An Argumentation-based Approach2018Ingår i: / [ed] Riccardo De Masellis, Valentin Goranko, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    During the deliberation phase in practical reasoning, an intelligent agent generates a set of pursuable goals (or desires) and then selects which of them he commits to achieve (intentions). When several pursuable goals are generated, it may cause that some incompatibilities arise between them. In this work, we focus on the denition, identication and resolution of these incompatibilities. The suggested approach considers the three forms of incompatibility introduced by Castelfranchi and Paglieri, namely the terminal incompatibility, the resources incompatibility and the superuity. We characterise computationally these forms of incompatibility by means of arguments that represent the plans that allow an agent to achieve his goals. The incompatibility between goals is dened based on the conicts between their plans, which are represented by means of attacks in an argumentation framework. For the goals selection, we propose to use abstract argumentation theory by applying argumentation semantics.

  • 103. Morveli-Espinoza, Mariela
    et al.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Possebom, Ayslan
    Tacla, Cesar Augusto
    Resolving Incompatibilities among Procedural Goals under Uncertainty2018Ingår i: / [ed] Viviana Mascardi, Alessandro Ricci, Danny Weyns, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    By considering rational agents, we focus on the problem of selecting goals out of a set of incompatible ones. We consider two forms of incompatibility introduced by Castelfranchi and Paglieri, namely the terminal and the superfluity. We represent the agent’s plans by means of structured arguments whose premises are pervaded with uncertainty. We measure the strength of such arguments in order to determine the set of compatible goals. In this settings, we represent a novel strength value defined by a three-dimensional vector determined from a probabilistic interval associated with each argument. The vector represents the precision of the interval, the location of it, and the combination of precision and location. This type of representation and treatment of the strength of a structured argument has not been defined before by the state of the art. Considering our novel approach for measuring the strength of structured arguments, we propose a semantics for the selection of plans and goals that is based on Dung’s abstract argumentation theory.

  • 104.
    Morveli-Espinoza, Mariela
    et al.
    Federal University of Technology of Paraná (UTFPR), Curitiba, Brazil.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tacla, Cesar Augusto
    Federal University of Technology of Paraná (UTFPR), Curitiba, Brazil.
    An Imprecise Probability Approach for Abstract Argumentation Based on Credal Sets2019Ingår i: Symbolic and Quantitative Approaches with Uncertainty: ECSQARU 2019 / [ed] Kern-Isberner G., Ognjanović Z, Springer, 2019, s. 39-49Konferensbidrag (Refereegranskat)
    Abstract [en]

    Some abstract argumentation approaches consider that arguments have a degree of uncertainty, which impacts on the degree of uncertainty of the extensions obtained from an abstract argumentation framework (AAF) under a semantics. In these approaches, both the uncertainty of the arguments and of the extensions are modeled by means of precise probability values. However, in many real life situations the exact probabilities values are unknown and sometimes there is a need for aggregating the probability values of different sources. In this paper, we tackle the problem of calculating the degree of uncertainty of the extensions considering that the probability values of the arguments are imprecise. We use credal sets to model the uncertainty values of arguments and from these credal sets, we calculate the lower and upper bounds of the extensions. We study some properties of the suggested approach and illustrate it with an scenario of decision making.

  • 105. Mualla, Yazan
    et al.
    Najjar, Amro
    Umeå universitet.
    Boissier, Olivier
    EMSE Saint-Etienne.
    Galland, Stéphane
    UTBM.
    Tchappi Haman, Igor
    University of Ngaoundere.
    Vanet, Robin
    IMT Saint-Etienne.
    A Cyber-Physical System for Semi-autonomous Oil & Gas Drilling Operations2019Ingår i: 2019 Third IEEE International Conference on Robotic Computing (IRC), IEEE Computer Society, 2019, s. 514-519Konferensbidrag (Refereegranskat)
    Abstract [en]

    In Oil&Gas drilling operations and after reaching deep drilled depths, high temperature increases significantly enough to damage the down-hole drilling tools, and the existing mitigation process is insufficient. In this paper, we propose a Cyber-Physical System (CPS) where agents are used to represent the collaborating entities in Oil\&Gas fields both up-hole and down-hole. With the proposed CPS, down-hole tools respond to high temperature autonomously with a decentralized collective voting based on the tools' internal decision model while waiting for the cooling performed up-hole by the field engineer. This decision model, driven by the tools' specifications, aims to withstand high temperature. The proposed CPS is implemented using a multiagent simulation environment, and the results show that it mitigates high temperature properly with both the voting and the cooling mechanisms.

  • 106. Mualla, Yazan
    et al.
    Najjar, Amro
    Vanet, Robin
    Boissier, Olivier
    Galland, Stéphane
    Towards a Real-time Mitigation of High Temperature while Drilling using a Multi-agent System2018Ingår i: 1st International Workshop on Real-Time Compliant Multi-Agent Systems, RTcMAS 2018, 2018, s. 77-92Konferensbidrag (Refereegranskat)
  • 107. Mualla, Yazan
    et al.
    Vanet, Robin
    Najjar, Amro
    Boissier, Olivier
    Galland, Stéphane
    AgentOil: a multiagent-based simulation of the drilling process in oilfields2018Ingår i: International Conference on Practical Applications of Agents and Multi-Agent Systems, 2018, s. 339-343Konferensbidrag (Refereegranskat)
  • 108. Najjar, Amro
    et al.
    Mualla, Yazan
    Picard, Gauthier
    Singh, Kamal Deep
    Négociation multi-agent "un-à-plusieurs" et mécanismes de coordination pour la gestion de la satisfaction des utilisateurs d’un service2018Ingår i: 26èmes Journées Francophones sur les Systèmes Multi-Agents (JFSMA 2018), 2018Konferensbidrag (Refereegranskat)
  • 109. Najjar, Amro
    et al.
    Mualla, Yazan
    Singh, Kamal
    Picard, Gauthier
    One-to-Many Multi-agent Negotiation and Coordination Mechanisms to Manage User Satisfaction2018Ingår i: the 11th International Workshop on Agent-based Complex Automated Negotiations (ACAN2018), 2018Konferensbidrag (Refereegranskat)
  • 110.
    Najjar, Amro
    et al.
    Laboratoire Hubert Curien UMR CNRS 5516, Institut Henri Fayol, Mines Saint-Etienne, Saint-Etienne, France.
    Picard, Gauthier
    Boissier, Olivier
    Négociation multi-agents résistante aux pics de charge pour améliorer l’acceptabilité des services d’un fournisseur SaaS ouvert2018Ingår i: Revue d'intelligence artificielle: Revue des Sciences et Technologies de l'Information, ISSN 0992-499X, E-ISSN 1958-5748, Vol. 32, nr 5-6, s. 603-625Artikel i tidskrift (Refereegranskat)
    Abstract [fr]

    Le taux d’acceptabilité d’un service et la satisfaction des utilisateurs deviennent des facteurs clés pour éviter le désabonnement des clients et sécuriser le succès de tout fournisseur de logiciel en tant que service (SaaS). Néanmoins, le fournisseur doit également répondre à des charges de travail fluctuantes et minimiser le coût de la location de ressources sur le cloud. Pour répondre à ces préoccupations contradictoires, la plupart des travaux existants effectuent unilatéralement la gestion des ressources par le fournisseur. Par conséquent, les préférences de l’utilisateur final et son acceptabilité subjective du service sont pour la plupart ignorées. Afin d’évaluer la satisfaction des utilisateurs et l’acceptabilité du service, des études récentes dans le domaine de la qualité de l’expérience (QoE) recommandent aux fournisseurs d’utiliser des quantiles et des percentiles pour évaluer précisément l’acceptabilité du service utilisateur. Dans cet article, nous proposons un mécanisme de négociation « one-to-many » élastique, résistant à la charge et adaptatif pour améliorer l’acceptabilité du service d’un fournisseur SaaS ouvert. Basé sur l’estimation du quantile du taux d’acceptabilité du service et sur un modèle appris de la stratégie de négociation utilisateur, ce mécanisme ajuste le processus de négociation du fournisseur afin de garantir le taux d’acceptabilité du service souhaité tout en respectant les limites budgétaires du fournisseur. Le mécanisme proposé est mis en œuvre et ses résultats expérimentaux sont examinés et analysés.

  • 111.
    Nguyen, Chanh
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Multivariate LSTM-Based Location-Aware Workload Prediction for Edge Data Centers2019Ingår i: Proceedings, 19th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing, IEEE, 2019, s. 341-350Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Edge Clouds (MECs) is a promising computing platform to overcome challenges for the success of bandwidth-hungry, latency-critical applications by distributing computing and storage capacity in the edge of the network as Edge Data Centers (EDCs) within the close vicinity of end-users. Due to the heterogeneous distributed resource capacity in EDCs, the application deployment flexibility coupled with the user mobility, MECs bring significant challenges to control resource allocation and provisioning. In order to develop a self-managed system for MECs which efficiently decides how much and when to activate scaling, where to place and migrate services, it is crucial to predict its workload characteristics, including variations over time and locality. To this end, we present a novel location-aware workload predictor for EDCs. Our approach leverages the correlation among workloads of EDCs in a close physical distance and applies multivariate Long Short-Term Memory network to achieve on-line workload predictions for each EDC. The experiments with two real mobility traces show that our proposed approach can achieve better prediction accuracy than a state-of-the art location-unaware method (up to 44%) and a location-aware method (up to 17%). Further, through an intensive performance measurement using various input shaking methods, we substantiate that the proposed approach achieves a reliable and consistent performance.

  • 112.
    Nguyen, Chanh Le Tan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Location-aware load prediction in edge data centers2017Ingår i: 2017 Second International Conference on Fog and Mobile Edge Computing (FMEC), IEEE, 2017, s. 25-31Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Mobile Edge Cloud (MEC) is a platform complementing traditional centralized clouds, consisting in moving computing and storage capacity closer to users -e. g., as Edge Data Centers (EDC) in base stations -in order to reduce application-level latency and network bandwidth. The bounded coverage radius of base station and limited capacity of each EDC intertwined with user mobility challenge the operator's ability to perform capacity adjustment and planning. To face this challenge, proactive resource provisioning can be performed. The resource usage in each EDC is estimated in advance, which is made available for the decision making to efficiently determine various management actions and ensure that EDCs persistently satisfies the Quality of Service (QoS), while maximizing resource utilization. In this paper, we propose location-aware load prediction. For each EDC, load is not only predicted using its own historical load time series -as done for centralized clouds -but also those of its neighbor EDCs. We employ Vector Autoregression Model (VAR) in which the correlation among adjacent EDCs load time series are exploited. We evaluate our approach using real world mobility traces to simulate load in each EDC and conduct various experiments to evaluate the proposed algorithm. Result shows that our proposed algorithm is able to achieve an average accuracy of up to 93% on EDCs with substantial average load, which slightly improves prediction by 4.3% compared to the state-of-the-art approach. Considering the expected scale of MEC, this translates to substantial cost savings e. g., servers can be shutdown without QoS violation.

  • 113.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Approximating agreements in argumentation dialogues2018Ingår i: Multi-agent systems and agreement technologies: 15th European conference, EUMAS 2017, and 5th international conference, AT 2017, Evry, France, December 14-15, 2017, revised selected papers / [ed] Francesco Belardinelli, Estefanía Argente, Springer, 2018, s. 501-515Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many real applications, to reach an agreement between the participants of a dialogue, which can be for instance a negotiation, is not easy. Indeed, there are application domains such as the medical domain where to have a consensus among medical professionals is not feasible and might even be regarded as counterproductive. In this paper, we introduce an approach for expressing goals of a dialogue considering ordered disjunction rules. By applying argumentation semantics and degrees of satisfaction of goals, we introduce the so-called dialogue agreement degree. Moreover, by considering sets of dialogue agreement degrees, we define a lattice of agreement degrees. We argue that a lattice of agreement degrees suggests different approximations between the current state of a dialogue and its aimed goals. Indeed, a lattice of agreement degrees can show evidence about whether or not it is acceptable to dismiss goals in order to maximize agreements regarding other goals.

  • 114.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Approximating agreements in formal argumentation dialogues2019Ingår i: AI Communications, ISSN 0921-7126, E-ISSN 1875-8452, Vol. 32, s. 335-346Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In many real applications, to reach an agreement between the participants of a dialogue, which can be for instance a negotiation, is not easy. Indeed, there are application domains such as the medical domain where to reach a consensus among medical professionals is not feasible and might be even regarded as counterproductive. In this paper, we introduce an approach for expressing qualitative preferences between the goals of a dialogue considering ordered disjunction rules. By applying argumentation semantics and degrees of satisfaction of goals, we introduce the so-called dialogue agreement degree. Moreover, by considering sets of dialogue agreement degrees, we define a lattice of agreement degrees. We argue that a lattice of agreement degrees suggests different approximations between the current state of a dialogue and its aimed goals; hence, a lattice of agreement degrees can help to define different heuristics in the settings of strategic argumentation.

  • 115.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Argumentation Inference as Logic Programming Inference: an Extended Abstract2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In this extended abstract, we present a small survey of recent results in the study of argumentation theory as logic programming. In particular, we survey recent characterizations of eight argumentation semantics, i.e., Ground, Stable, Preferred, Complete, Semi-stable, Ideal, CF2, Stage, as logic programming semantics with negation as failure. These results consolidate the strong relationship between argumentation semantics and logic programming semantics with negation as failure.

  • 116.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Expansion and equivalence relations on argumentation frameworks based on logic programs2017Ingår i: Multi-agent systems and agreement technologies: 14th European conference, EUMAS 2016, and 4th international conference, AT 2016, Valencia, Spain, December 15-16, 2016, revised selected papers / [ed] Criado Pacheco N., Carrascosa C., Osman N., Julián Inglada V., Cham: Springer, 2017, s. 375-389Konferensbidrag (Refereegranskat)
    Abstract [en]

    Expansion and equivalence relations have been explored in the settings of abstract argumentation. However, in terms of structured arguments, expansion and equivalence relations have not been explored in the settings of structured arguments based on logic programs. In this paper, we draw connections between resulting argumentation frameworks from logic programs considering expansion and equivalence relations. We show that by considering different methods for constructing arguments and defining attack relations, one can define different expansion and equivalence relations between the resulting argumentation frameworks from logic programs. Moreover, we extended results from abstract argumentation into structured arguments based on logic programs.

  • 117.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Andrade, Daniel
    Guerrero, Esteban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    MAIoT: An IoT Architecture with Reasoning and Dialogue Capability2017Ingår i: Applications for Future Internet: International Summit, AFI 2016, Puebla, Mexico, May 25-28, 2016, Revised Selected Papers / [ed] Enrique Sucar, Oscar Mayora, Enrique Munoz de Cote, Cham: Springer, 2017, s. 109-113Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes MAIoT, a Multiagent-based Architecture which aims to coordinate Internet of Things (IoT) devices. MAIoT is distinguished by its capabilities for allowing dialogues between IoT devices. To support theses dialogue capabilities, the IoT devices are wrapped into rational agents with reasoning and dialogue capabilities.

  • 118.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Haeusler, Edward Hermann
    Pontifícia Universidade Católica do Rio de Janeiro, Brazil.
    Lopes, Bruno
    Universidade Federal Fluminense, Brazil.
    Editorial: Thematic issue: Advances in Logic-based Methods for Intelligent Systems2017Ingår i: Journal of Computacion y Sistemas, ISSN 1405-5546, Vol. 21, nr 3, s. 399-400Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This issue presents 14 papers, among them the first six papers present to the readers advances in Logic-based Methods for Intelligent Systems.

  • 119.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Merging Deductive and Abductive Knowledge Bases: An Argumentation Context Approach2013Ingår i: POLIBITS Research Journal on Computer Science and Computer Engineering With Applications, ISSN 1870-9044, Vol. 48, s. 39-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The consideration of heterogenous knowledge sources for supporting decision making is key to accomplish informed decisions, e.g., about medical diagnosis. Consequently, merging different data from different knowledge bases is a key issue for providing support for decision-making. In this paper, we explore an argumentation context approach, which follows how medical professionals typically reason, in order to merge two basic kinds of reasoning approaches based on logic programs: deductive and abductive inferences. In this setting, we introduce two kinds of argumentation frameworks: deductive argumentation frameworks and abductive argumentation frameworks. For merging these argumentation frameworks, we follow an approach based on argumentation context systems. We illustrate the approach by considering two different declarative specifications of evidence-based medical knowledge into logic programs in order to support informed medical decisions.

  • 120.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Possibilistic nested logic programs and strong equivalence2015Ingår i: International Journal of Approximate Reasoning, ISSN 0888-613X, E-ISSN 1873-4731, Vol. 59, s. 1-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the class of possibilistic nested logic programs is introduced. These possibilistic logic programs allow us to use nested expressions in the bodies and heads of their rules. By considering a possibilistic nested logic program as a possibilistic theory, a construction of a possibilistic logic programing semantics based on answer sets for nested logic programs and the proof theory of possibilistic logic is defined. In order to define a general method for computing the possibilistic answer sets of a possibilistic nested program, the idea of equivalence between possibilistic nested programs is explored. By considering properties of equivalence between possibilistic programs, a process of transforming a possibilistic nested logic program into a possibilistic disjunctive logic program is defined. Given that our approach is an extension of answer set programming, we also explore the concept of strong equivalence between possibilistic nested logic programs. To this end, we introduce the concept of poss SE-models. Therefore, we show that two possibilistic nested logic programs are strong equivalents whenever they have the same poss SE-models.

    The expressiveness of the possibilistic nested logic programs is illustrated by a scenario from the medical domain. In particular, we exemplify how possibilistic nested logic programs are expressive enough for capturing medical guidelines which are pervaded by vagueness and qualitative information.

  • 121.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Marcial-Romero, José Raymundo
    Preface2015Ingår i: Electronical Notes in Theoretical Computer Science, ISSN 1571-0661, E-ISSN 1571-0661, Vol. 315, nr 9, s. 1-2Artikel i tidskrift (Övrigt vetenskapligt)
  • 122.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Osorio, Mauricio
    Extending Well-Founded Semantics with Clark's Completion for Disjunctive Logic Programs2018Ingår i: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, artikel-id 4157030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we introduce new semantics (that we call D3-WFS-DCOMP) and compare it with the stable semantics (STABLE). For normal programs, this semantics is based on suitable integration of the well-founded semantics (WFS) and the Clark's completion. D3-WFS-DCOMhas the following appealing properties: First, it agrees with STABLE in the sense that it never defines a nonminimal model or a nonminimal supported model. Second, for normal programs it extends WFS. Third, every stable model of a disjunctive program.. is a D3-WFS-DCOM model of P. Fourth, it is constructed using transformation rules accepted by STABLE. We also introduce second semantics that we call D2-WFS-DCOMP. We show that D2-WFS-DCOMP is equivalent to D3-WFS-DCOMP for normal programs but this is not the case for disjunctive programs. We also introduce third new semantics that supports the use of implicit disjunctions. We illustrate how these semantics can be extended to programs including explicit negation, default negation in the head of a clause, and a lub operator, which is a generalization of the aggregation operator setof over arbitrary complete lattices.

  • 123.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Osorio, Mauricio
    Ideal Extensions as Logical Programming Models2016Ingår i: Journal of logic and computation (Print), ISSN 0955-792X, E-ISSN 1465-363X, Vol. 26, nr 5, s. 1361-1393Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that the ideal sets of an argumentation framework can be characterized by two kinds of logical models: ideal models (2-valued logical models) and p-stable models (2-valued logical models). We also show that the maximal ideal set of an argumentation framework can be characterized by the well-founded+ model (a 3-valued logical model). These results argue for  the logical foundations of the ideal sets of an argumentation framework. Moreover, these results  consolidate the strong relationship between argumentation semantics and logic programming semantics with negation as failure. More accurately, we prove that the five argumentation semantics suggested by Dung etal, grounded, stable, preferred, complete and ideal semantics, can be characterized by the well-founded model, stable-model, p-stable, Clark's completion and well-founded+ model semantics, respectively by using a unique mapping from argumentation frameworks into logic programs. We observe that the labellings of these argumentation semantics can be inferred by the logical models of a logic program.

  • 124.
    Nieves, Juan Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Partonia, Saeed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Guerrero, Esteban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A Probabilistic Non-Monotonic Activity Qualifier2015Ingår i: The 6th International Conference on Ambient Systems, Networks and Technologies (ANT-2015), the 5th International Conference on Sustainable Energy Information Technology (SEIT-2015) / [ed] Elhadi Shakshuki, Elsevier, 2015, Vol. 52, s. 420-427Konferensbidrag (Refereegranskat)
    Abstract [en]

    The International Classification of Functioning, Disability and Health (ICF) defines Functioning and Disability as the results of the interaction between the health conditions of a person and his/her environment. It considers a set of components and qualifiers to evaluate activity and participation. In this paper, we interpret a performance quantifier under a human activity recognition process. To this end, we introduce a novel definition of an activity which is based on ICF guidelines. This definition gives place to a probabilistic non-monotonic activity qualifier. In order to recognize an activity according to our novel activity's definition, we explore non-monotonic reasoning technics to capture domain knowledge in terms of action specification languages. By considering an action specification language, called CTAID, and Answer Set Programming, we propose and develop a system called ActRec system which takes background information into consideration and recognize activities according to our suggested definition. Moreover, we show that by aggregating our probabilistic non-monotonic activity qualifier, we are able of detecting complex activities, e.g., long-term activities. We illustrate our approach in the context of an ambient assisted living environment called As-A-Pal.

  • 125.
    Nilsson, Elin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    A Recipe for Responsiveness: Strategies for Improving Performance in Android Applications2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Mobile applications are expected to be fast and responsive to user interaction, despite challenges mobile platforms and devices face in terms of limited computational power, battery, memory, etc. Ensuring that applications are performant is however not trivial, as performance bugs are difficult to detect, fix, and verify. In order for mobile applications and devices to appear perfectly responsive to the user, they need to meet a 60 frames per second frame rate, and keep load times preferably between 0-300 ms. Meeting these expectations means that there is no room for performance bugs, so there is a need for improving and developing better testing tools and strategies in order to help mobile developers improve performance in their applications.

    This thesis investigates strategies for testing and improving performance in Android applications by conducting a literary study, and a case study with the Spotify Android application. Some of the key findings of this thesis include promising results from tools that visualise sources of performance bugs in the user interface of applications, as well as proposed strategies and tools aimed to help developers profile and improve performance in their Android applications.

  • 126.
    Nyberg, Jakob
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Panda Cloud System Management Stjärna Fyrkant Umeå2015Självständigt arbete på grundnivå (kandidatexamen), 180 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Panda Cloud Systems Management (PCSM) is a cloud-based system for monitoring, inventorying and managing computers, servers and networks. Stjarna Fyrkant started its IT-department in August 2014 where they manage for Stjarna Fyrkants computers and networks but also other companies as IT consultants. They have chosen to use PCSM to manage and to monitor these networks.

     

    The project was started because Stjarna Fyrkant wants a better insight of the system as they have gone through with the basics of it. They have chosen four areas where they wants to know more about and these are monitoring of computers and servers, SNMP for monitoring other equipment, automated processes such as updating programs and Windows automatically and for Mobile Management (MDM) to manage and monitor iPhones.

     

    To make this happen I was given login information to PCSM, two computers and an iPhone to test PCSM and its other functionalities for what Stjarna Fyrkant want to accomplish. For monitors the report will go through about which monitor that exists in the store and in PCSM and later assign these to two groups for monitoring the servers and clients. Then how to monitor other devices via SNMP and how this was applied to the devices that Stjarna Fyrkant has, such as printers. However, this didn’t work for all devices.

     

    For maintenance of computers the report analyzes how to keep important updates for programs like Java and .NET but also for Windows. Additionally it was looked into how to remove unnecessary files found on the computers, such as the temporary files.

     

    For MDM the report looks in to which functionalities that exists and these were later tested for an iPhone. These functions worked surprisingly fast when it took only a few seconds for them to apply. There were plans to create a product sheet for companies of these features, but this was handed to someone else with more knowledge for design such towards companies.

     

  • 127.
    Nyberg, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Systemintegration baserad på WCF2011Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport beskriver arbetet med att utveckla ett API (Application Programming Interface) till Eurocons projekteringssystem SiteBase. Utvecklingen av systemet har bedrivits som ett examensarbete på uppdrag av Eurocon Consulting AB i Örnsköldsvik. Examensarbetet har bedrivits som en examinerande kurs för en högskoleingenjörsexamen med inriktning elektronik med en specialisering mot datorteknik och inbyggda system.

    Arbetet består av att utveckla ett API, till ett projekteringssystem baserat på WCF (Windows Communication Foundation), som är konfigurerbar så att den relativt enkelt ska kunna integreras med andra system.

    Syftet är att underlätta och minska den utvecklingstid det tar att integrera andra system med SiteBase, att skapa en bas att utgå ifrån för framtida integrationer.

    Systemet är utvecklat i C# med Visual Studio 2010 samt med Microsoft NET Framework 4.0 som ramverk. Utvecklingen av systemet har framställts i faser där delar av systemet utvecklats innan nästa del påbörjats.

  • 128.
    Oetsch, Johannes
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Stable-Ordered Models for Propositional Theories with Order Operators2019Ingår i: Logics in Artificial Intelligence: JELIA 2019 / [ed] Calimeri, Francesco; Leone, Nicola; Manna, Marco, Springer, 2019, s. 794-802Konferensbidrag (Refereegranskat)
    Abstract [en]

    The stable-model semantics has been generalised from logic programs to arbitrary theories. We explore a further generalisation and consider sequences of atoms as models instead of sets. The language is extended by suitable order operators to access this additional information. We recently introduced an extension of classical logic by a single order operator with a temporal interpretation for activity reasoning. The logic envisaged here is a nonmonotonic version thereof. Our definition of what we call stable-ordered models is based on the stable-model semantics for theories due to Ferraris and Lifschitz with the necessary changes. Compared to related nonmonotonic versions of temporal logics, our approach is less costly as checking model existence remains at the second level of the polynomial hierarchy. We demonstrate versatile applications from activity reasoning, combinatorial testing, debugging concurrent programs, and digital forensics.

  • 129.
    Ohlsson, Kristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Metodiskt backupsystem för lokalkontrollsutrustningar2013Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Statkraft är helägt av Norska staten och är Sveriges fjärde största elproducent. Detta examensarbete syftar till att ta fram en metod för att lösa hur Statkraft Sverige AB ska lagra mjukvarubackuper av sina lokalkontrollssystem. För närvarande finns det ingen homogen lagringsmetod för backuper på företaget och problemet som ska lösas i examensarbetet är hur man kan lagra backuper från ett flertal heterogena system på en gemensam lagringsplattform. I och med att de allra flesta hjälpsystem för konfigurering av styrdatorer (PLC) bygger på Microsoft DOS/Windows så är det relativt enkelt att överföra backuper till en gemensam plattform. För äldre hjälpmedel kan man dock tänka sig att virtualisera hjälpmedlen på en nyare PC-dator med exempelvis VMware för att undvika problem som kan uppstå med äldre hårdvara. Därefter kan man arkivera backuperna i ZIP-format som man kan lagra på en server. Fördelen med att använda sig av ZIP för arkivering är att man får en inbyggd integritetskontroll av backuperna då ZIP har inbyggd cyclic redundancy check (CRC) som använder sig av kontrollsummor för att kontrollera så att filerna är korrekta. Dessutom så får man endast en fil i jämförelse med många filer per backup om man inte använder sig av arkivering. Backuperna ska sedan lagras på en server som ligger inom företagets intranät/kontorsnät som endast behörig personal har tillgång till. Uppladdningen av filerna kan gå till på flera olika sätt, större backupfiler från PC-system kan laddas upp direkt via nätverket och dokumentationen uppdateras manuellt. Mindre backupfiler skulle dock kunna laddas upp genom en webbsida på intranätet där dokumentationen uppdateras automatiskt i samband med uppladdning. Lagringsutrymmet för båda dessa lösningar är dock detsamma så det går även att ladda upp mindre backuper manuellt genom nätverket. Med dessa lösningar har berörda tekniker tillgång till backuperna vart de än befinner sig så länge internetuppkoppling finns genom ett virtuellt privat nätverk (VPN) till företagets intranät/kontorsnät.

  • 130. Osorio, Mauricio
    et al.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Range-based argumentation semantics as two-valued models2017Ingår i: Theory and Practice of Logic Programming, ISSN 1471-0684, E-ISSN 1475-3081, Vol. 17, nr 1, s. 75-90Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Characterizations of semi-stable and stage extensions in terms of two-valued logical models are presented. To this end, the so-called GL-supported and GL-stage models are defined. These two classes of logical models are logic programming counterparts of the notion of range which is an established concept in argumentation semantics.

  • 131. Osorio, Mauricio
    et al.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Santoyo, Alejandro
    Complete Extensions as Clark's Completion Semantics2013Ingår i: 2013 MEXICAN INTERNATIONAL CONFERENCE ON COMPUTER SCIENCE (ENC 2013), IEEE, 2013, s. 81-88Konferensbidrag (Refereegranskat)
    Abstract [en]

    According to Dung, the sets of arguments which can be considered as admissible from an argumentation framework can be regarded as logical models of a given logic program. Clark's completions defines a basic logic programming semantics which has influenced modern non-monotonic semantics such as Answer Set Semantics. The Complete Semantics is a fundamental argumentation semantics which identifies a set of admissible sets which contains the grounded, stable, preferred and ideal semantics. In this paper we introduce a characterization of the complete semantics in terms of logical models using Clark's completions. Given that we use a unique mapping which characterizes the grounded, stable, preferred and ideal semantics, our characterization argues for a strong bridge between argumentation semantics and logic programming semantics with negation as failure. This paper also seeks to draw attention to the correspondence between the complete semantics of argumentation frameworks and models of Clark's completion, since this correspondence also allows us to identify the possibility of computing argumentation frameworks based on integer programming.

  • 132.
    Palmgren, Marcus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Hyperkonvergerad lösning med Storage spaces direct, för och nackdelar2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport behandlar frågor angående Storage Spaces Direct i Windows 2016:s server. Den tar upp hur man installerar en hyperkonvergerad lösning samt vilka konfigureringar som krävs för att kunna sätta upp funktionen. Två olika frågeställningar uppkom i början av projektet, dessa var: ”hur bra är Storage Spaces Direct?” samt ”går det att implementera funktionen på ett företag idag?”. Utförandet av projektet gjordes i ett samarbete med ett konsultföretag som heter TeamNorr och med deras hårdvara. Storage Spaces Direct är en funktion som fungerar bra och smidigt. Detta om man har rätt information, har nog med kunskap om funktionen samt gör ett grundligt och detaljerat förarbete. Två olika installationer av servrar jämförs, den ena är via desktop experience där man tar hjälp av Windows GUI och det andra är via en Powershellterminal. Båda kan användas vid installation av Storage Spaces Direct. Dessa två olika servrar har olika för- och nackdelar. Jag kom fram till att när man använder Powershell för att installera servrar och tillägg var det överlägset bäst och säkrast. Slutresultatet blev som förväntat. Storage Spaces Direct är det bästa sättet att spara information och köra redundans som finns i dagsläget. Storage Spaces Direct är både enklare använda och att underhålla samt mer kostnadseffektivt för företag.

  • 133.
    Papadopoulos, Alessandro Vittorio
    et al.
    Lund University.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Årzén, Karl-Erik
    Lund University.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    PEAS: A Performance Evaluation framework for Auto-Scaling strategies in cloud applications2015Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Numerous auto-scaling strategies have been proposed in the last few years for improving various Quality of Service (QoS)indicators of cloud applications, e.g., response time and throughput, by adapting the amount of resources assigned to theapplication to meet the workload demand. However, the evaluation of a proposed auto-scaler is usually achieved throughexperiments under specific conditions, and seldom includes extensive testing to account for uncertainties in the workloads, andunexpected behaviors of the system. These tests by no means can provide guarantees about the behavior of the system in generalconditions. In this paper, we present PEAS, a Performance Evaluation framework for Auto-Scaling strategies in the presenceof uncertainties. The evaluation is formulated as a chance constrained optimization problem, which is solved using scenariotheory. The adoption of such a technique allows one to give probabilistic guarantees of the obtainable performance. Six differentauto-scaling strategies have been selected from the literature for extensive test evaluation, and compared using the proposedframework. We build a discrete event simulator and parameterize it based on real experiments. Using the simulator, each auto-scaler’s performance is evaluated using 796 distinct real workload traces from projects hosted on the Wikimedia foundations’servers, and their performance is compared using PEAS. The evaluation is carried out using different performance metrics,highlighting the flexibility of the framework, while providing probabilistic bounds on the evaluation and the performance of thealgorithms. Our results highlight the problem of generalizing the conclusions of the original published studies and show thatbased on the evaluation criteria, a controller can be shown to be better than other controllers.

  • 134.
    Papadopoulos, Alessandro Vittorio
    et al.
    IDT, Mälardalen University, Sweden.
    Krzywda, Jakub
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Maggio, Martina
    Department of Automatic Control, Lund University, Sweden.
    Power-aware cloud brownout: Response time and power consumption control2017Ingår i: 2017 IEEE 56th Annual Conference on Decision and Control (CDC), IEEE, 2017, s. 2686-2691Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cloud computing infrastructures are powering most of the web hosting services that we use at all times. A recent failure in the Amazon cloud infrastructure made many of the website that we use on a hourly basis unavailable1. This illustrates the importance of cloud applications being able to absorb peaks in workload, and at the same time to tune their power requirements to the power and energy capacity offered by the data center infrastructure. In this paper we combine an established technique for response time control — brownout — with power capping. We use cascaded control to take into account both the need for predictability in the response times (the inner loop), and the power cap (the outer loop). We execute tests on real machines to determine power usage and response times models and extend an existing simulator. We then evaluate the cascaded controller approach with a variety of workloads and both open- and closed-loop client models.

  • 135. Penya, Yoseba K.
    et al.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Espinoza, Angelina
    Borges, Cruz E.
    Peña, Aitor
    Ortega, Mariano
    Distributed Semantic Architecture for Smart Grids2012Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 5, nr 11, s. 4824-4843Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The smart grid revolution demands a huge effort in redesigning and enhancing current power networks, as well as integrating emerging scenarios such as distributed generation, renewable energies or the electric vehicle. This novel situation will cause a huge flood of data that can only be handled, processed and exploited in real-time with the help of cutting-edge ICT (Information and Communication Technologies). We present here a new architecture that, contrary to the previous centralised and static model, distributes the intelligence all over the grid by means of individual intelligent nodes controlling a number of electric assets. The nodes own a profile of the standard smart grid ontology stored in the knowledge base with the inferred information about their environment in RDF triples. Since the system does not have a central registry or a service directory, the connectivity emerges from the view of the world semantically encoded by each individual intelligent node (i.e., profile + inferred information). We have described a use-case both with and without real-time requirements to illustrate and validate this novel approach.

  • 136.
    Pizzamiglio, Sara
    et al.
    School of Architecture, Computing and Engineering, University of East London, United Kingdom.
    Naeem, Usman
    School of Architecture, Computing and Engineering, University of East London, United Kingdom.
    Ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. School of Architecture, Computing and Engineering, University of East London, United Kingdom.
    Sharif, Muhammad Saeed
    School of Architecture, Computing and Engineering, University of East London, United Kingdom.
    Abdalla, Hassan
    School of Architecture, Computing and Engineering, University of East London, United Kingdom.
    Turner, Duncan L.
    Neurorehabilitation Unit, School of Health, Sport and Bioscience, University of East London, United Kingdom.
    A multimodal approach to measure the distraction levels of pedestrians using mobile sensing2017Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 113, s. 89-96Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The emergence of smart phones has had a positive impact on society as the range of features and automation has allowed people to become more productive while they are on the move. On the contrary, the use of these devices has also become a distraction and hindrance, especially for pedestrians who use their phones whilst walking on the streets. This is reinforced by the fact that pedestrian injuries due to the use of mobile phones has now exceeded mobile phone related driver injuries. This paper describes an approach that measures the different levels of distraction encountered by pedestrians whilst they are walking. To distinguish between the distractions within the brain the proposed work analyses data collected from mobile sensors (accelerometers for movement, mobile EEG for electroencephalogram signals from the brain). The long-term motivation of the proposed work is to provide pedestrians with notifications as they approach potential hazards while they walk on the street conducting multiple tasks such as using a smart phone.

  • 137. Rochwerger, Benny
    et al.
    Vázquez, Constantino
    Breitgand, David
    Hadas, David
    Villari, Massimo
    Massonet, Philippe
    Levy, Eliezer
    Galis, Alex
    Llorente, Ignacio M.
    Montero, Rubén S.
    Wolfsthal, Yaron
    Nagin, Kenneth
    Larsson, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Galán, Fermín
    An Architecture for Federated Cloud Computing2011Ingår i: Cloud Computing: Principles and Paradigms / [ed] Rajkumar Buyya, James Broberg, Andrzej Goscinski, Hoboken, N. J.: John Wiley & Sons, 2011, s. 393-412Kapitel i bok, del av antologi (Refereegranskat)
  • 138.
    Rodrigo, Gonzalo P
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Antypas, Katie
    Lawrence Berkeley National Lab.
    Gerber, Richard
    Lawrence Berkeley National Lab.
    Ramakrishnan, Lavanya
    Lawrence Berkeley National Lab.
    HPC System Lifetime Story: Workload Characterization and Evolutionary Analyses on NERSC Systems2015Ingår i: Proceedings of the 24th International Symposium on High-Performance Parallel and Distributed Computing (HDPC), ACM Digital Library, 2015, , s. 57-60s. 57-60Konferensbidrag (Refereegranskat)
    Abstract [en]

    High performance computing centers have traditionally served monolithic MPI applications. However, in recent years, many of the large scientific computations have included high throughput and data-intensive jobs. HPC systems have mostly used batch queue schedulers to schedule these workloads on appropriate resources. There is a need to understand future scheduling scenarios that can support the diverse scientific workloads in HPC centers. In this paper, we analyze the workloads on two systems (Hopper and Carver) at the National Energy Research Scientific Computing (NERSC) Center. Specifically, we present a trend analysis towards understanding the evolution of the workload over the lifetime of the two systems.

  • 139.
    Rodrigo, Gonzalo P.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Östberg, P-O
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ramakrishnan, Lavanya
    Lawrence Berkeley National Lab, USA.
    A2L2: an application aware flexible HPC scheduling model for low-latency allocation2015Ingår i: VTDC '15: proceedings of the 8th International workshop on virtualization technologies in distributed computing, ACM Digital Library, 2015, , s. 11-19s. 11-19Konferensbidrag (Refereegranskat)
    Abstract [en]

    High-performance computing (HPC) is focused on providing large-scale compute capacity to scientific applications. HPC schedulers tend to be optimized for large parallel batch jobs and, as such, often overlook the requirements of other scientific applications. In this work, we propose a cloud-inspired HPC scheduling model that aims to capture application performance and requirement models (Application Aware - A2) and dynamically resize malleable application resource allocations to be able to support applications with critical performance or deadline requirements. (Low Latency allocation - L2). The proposed model incorporates measures to improve data-intensive applications performance on HPC systems and is derived from a set of cloud scheduling techniques that are identified as applicable in HPC environments. The model places special focus on dynamically malleable applications; data-intensive applications that support dynamic resource allocation without incurring severe performance penalties; which are proposed for fine-grained back-filling and dynamic resource allocation control without job preemption.

  • 140.
    Schwarz, Angelika Beatrix
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Karlsson, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Scalable eigenvector computation for the non-symmetric eigenvalue problem2019Ingår i: Parallel Computing, ISSN 0167-8191, E-ISSN 1872-7336, Vol. 85, s. 131-140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present two task-centric algorithms for computing selected eigenvectors of a non-symmetric matrix reduced to real Schur form. Our approach eliminates the sequential phases present in the current LAPACK/ScaLAPACK implementation. We demonstrate the scalability of our implementation on multicore, manycore and distributed memory systems.

  • 141.
    Schwarz, Angelika Beatrix
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kjelgaard Mikkelsen, Carl Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Robust Task-Parallel Solution of the Triangular Sylvester EquationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The Bartels-Stewart algorithm is a standard approach to solving the dense Sylvester equation. It reduces the problem to the solution of the triangular Sylvester equation. The triangular Sylvester equation is solved with a variant of backward substitution. Backward substitution is prone to overflow. Overflow can be avoided by dynamic scaling of the solution matrix. An algorithm which prevents overflow is said to berobust. The standard library LAPACK contains the robust scalar sequential solver dtrsyl. This paper derives a robust, level-3 BLAS-based task-parallel solver. By adding overflow protection, our robust solver closes the gap between problems solvable by LAPACK and problems solvable by existing non-robust task-parallel solvers. We demonstrate that our robust solver achieves a similar performance as non-robust solvers.

  • 142.
    Sedaghat, Mina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hernandez, Francisco
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A virtual machine re-packing approach to the horizontal vs. vertical elasticity trade-off for cloud autoscaling2013Ingår i: Proceedings of the 2013 ACM Cloud and Autonomic Computing Conference, ACM Press, 2013, s. Article no. 6-Konferensbidrag (Refereegranskat)
    Abstract [en]

    An automated solution to horizontal vs. vertical elasticity problem is central to make cloud autoscalers truly autonomous. Today's cloud autoscalers are typically varying the capacity allocated by increasing and decreasing the number of virtual machines (VMs) of a predefined size (horizontal elasticity), not taking into account that as load varies it may be advantageous not only to vary the number but also the size of VMs (vertical elasticity). We analyze the price/performance effects achieved by different strategies for selecting VM-sizes for handling increasing load and we propose a cost-benefit based approach to determine when to (partly) replace a current set of VMs with a different set. We evaluate our repacking approach in combination with different auto-scaling strategies. Our results show a range of 7% up to 60% cost saving in total resource utilization cost of our sample applications and workloads.

  • 143.
    Shafiq, ur Réhman
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Royal Institute of Technology (KTH), Sweden..
    Using Vibrotactile Language for Multimodal Human Animals Communication and Interaction2014Ingår i: Proceedings of the 2014 Workshops on Advances in Computer Entertainment Conference, ACE '14, Association for Computing Machinery (ACM), 2014, s. 1:1-1:5Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work we aim to facilitate computer mediated multimodal communication and interaction between human and animal based on vibrotactile stimuli. To study and influence the behavior of animals, usually researchers use 2D/3D visual stimuli. However we use vibrotactile pattern based language which provides the opportunity to communicate and interact with animals. We have performed experiment with a vibrotactile based human-animal multimodal communication system to study the effectiveness of vibratory stimuli applied to the animal skin along with audio and visual stimuli. The preliminary results are encouraging and indicate that low-resolution tactual displays are effective in transmitting information.

  • 144.
    Shahrad, Mohammad
    et al.
    Princeton University.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Zheng, Liang
    Princeton University.
    Chiang, Mung
    Princeton University / Purdue University.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wentzlaf, David
    Princeton University.
    Incentivizing Self-Capping to Increase Cloud Utilization2017Ingår i: Proceedings of the 2017 Symposium on Cloud Computing (SOCC '17), Association for Computing Machinery (ACM), 2017, s. 52-65Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cloud Infrastructure as a Service (IaaS) providers continually seek higher resource utilization to better amortize capital costs. Higher utilization not only can enable higher profit for IaaS providers but also provides a mechanism to raise energy efficiency; therefore creating greener cloud services. Unfortunately, achieving high utilization is difficult mainly due to infrastructure providers needing to maintain spare capacity to service demand fluctuations.

    Graceful degradation is a self-adaptation technique originally designed for constructing robust services that survive resource shortages. Previous work has shown that graceful degradation can also be used to improve resource utilization in the cloud by absorbing demand fluctuations and reducing spare capacity. In this work, we build a system and pricing model that enables infrastructure providers to incentivize their tenants to use graceful degradation. By using graceful degradation with an appropriate pricing model, the infrastructure provider can realize higher resource utilization while simultaneously, its tenants can increase their profit. Our proposed solution is based on a hybrid model which guarantees both reserved and peak on-demand capacities over flexible periods. It also includes a global dynamic price pair for capacity which remains uniform during each tenant's Service Level Agreement (SLA) term.

    We evaluate our scheme using simulations based on real-world traces and also implement a prototype using RUBiS on the Xen hypervisor as an end-to-end demonstration. Our analysis shows that the proposed scheme never hurts a tenant's net profit, but can improve it by as much as 93%. Simultaneously, it can also improve the effective utilization of contracts from 42% to as high as 99%.

  • 145.
    Shan, Min
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik.
    What matters in the digital shopping mall?: A study of Chinese consumers’ adoption of E-business platforms and vendors2012Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    E-business is growing rapidly all over the world and especially in China, which now has the largest C2C market in the world. Most studies of users’ experience of E-business either focus on the platform usage, platform adoption or include platform usage and vendors’ behavior as variables in general e-retailing models. However, we do not know much about what effect the interplay between E-business platforms and vendors operating on the platform has on consumers E-business behavior. In this paper, buyers' behavior in terms of choosing platforms and choosing stores is examined separately, while measurements for influencing factors such as size of vendor base and trust of platform owner is included to capture second order effects. Data was gathered through a questionnaire, published on a professional Chinese survey website for collecting data. Afterwards, SPSS was used for analyzing data. Similarities and differences between the outcomes for the two research questions were analyzed. The main patterns in the two models are similar, suggesting that the interaction between platform owners and vendors has impact on buyers as well. Price, which was one of the most important features of E-business, proved to be of minor importance for choosing both E-business platform and vendors. However, there are some differences between adoption of platforms and vendors, range of market is important for platform adoption, while it is not a indicator for consumers to choose a certain vendor. These findings suggest that there are second order effects involved in E-business platforms. Further, they indicate that once an E-business platform has acquired a large enough user base, the owner might consider increasing revenues from vendor fees, as long as they translate to small product price increases rather than a decreased vendor user base.

  • 146. 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.

  • 147.
    Souza, Abel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Papadopoulos, Alessandro Vittorio
    Tomás Bolivar, Luis
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Red Hat Inc..
    Gilbert, David
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hybrid Adaptive Checkpointing for Virtual Machine Fault Tolerance2018Ingår i: Proceedings - 2018 IEEE International Conference on Cloud Engineering, IC2E 2018 / [ed] Li J., Chandra A., Guo T., Cai Y., Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 12-22Konferensbidrag (Refereegranskat)
    Abstract [en]

    Active Virtual Machine (VM) replication is an application independent and cost-efficient mechanism for high availability and fault tolerance, with several recently proposed implementations based on checkpointing. However, these methods may suffer from large impacts on application latency, excessive resource usage overheads, and/or unpredictable behavior for varying workloads. To address these problems, we propose a hybrid approach through a Proportional-Integral (PI) controller to dynamically switch between periodic and on-demand check-pointing. Our mechanism automatically selects the method that minimizes application downtime by adapting itself to changes in workload characteristics. The implementation is based on modifications to QEMU, LibVirt, and OpenStack, to seamlessly provide fault tolerant VM provisioning and to enable the controller to dynamically select the best checkpointing mode. Our evaluation is based on experiments with a video streaming application, an e-commerce benchmark, and a software development tool. The experiments demonstrate that our adaptive hybrid approach improves both application availability and resource usage compared to static selection of a checkpointing method, with application performance gains and neglectable overheads.

  • 148.
    Souza, Abel Pinto Coelho de
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Application-aware resource management for datacenters2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    High Performance Computing (HPC) and Cloud Computing datacenters are extensively used to steer and solve complex problems in science, engineering, and business, such as calculating correlations and making predictions. Already in a single datacenter server, there are thousands of hardware and software metrics – Key Performance Indicators (KPIs) – that individually and aggregated can give insight in the performance, robustness, and efficiency of the datacenter and the provisioned applications. At the datacenter level, the number of KPIs is even higher. The fast growing interest on datacenter management from both public and industry together with the rapid expansion in scale and complexity of datacenter resources and the services being provided on them have made monitoring, profiling, controlling, and provisioning compute resources dynamically at runtime into a challenging and complex task. Commonly, correlations of application KPIs, like response time and throughput, with resource capacities show that runtime systems (e.g., containers or virtual machines) that are used to provision these applications do not utilize available resources efficiently. This reduces datacenter efficiency, which in term results in higher operational costs and longer waiting times for results.

    The goal of this thesis is to develop tools and autonomic techniques for improving datacenter operations, management and utilization, while improving and/or minimizing impacts on applications performance. To this end, we make use of application resource descriptors to create a library that dynamically adjusts the amount of resources used, enabling elasticity for scientific workflows in HPC datacenters. For mission critical applications, high availability is of great concern since these services must be kept running even in the event of system failures. By modeling and correlating specific resource counters, like CPU, memory and network utilization, with the number of runtime synchronizations, we present adaptive mechanisms to dynamically select which fault tolerant mechanism to use. Likewise, for scientific applications we propose a hybrid extensible architecture for dual-level scheduling of data intensive jobs in HPC infrastructures, allowing operational simplification, on-boarding of new types of applications and achieving greater job throughput with higher overall datacenter efficiency.

  • 149.
    Souza, Abel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Rezaei, Mohamad
    PDC Center for High Performance Computing, KTH Royal Institute of Technology, Sweden.
    Laure, Erwin
    PDC Center for High Performance Computing, KTH Royal Institute of Technology, Sweden.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hybrid Resource Management for HPC and Data Intensive Workloads2019Ingår i: 2019 19th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing (CCGRID), Los Alamitos: IEEE Computer Society, 2019, s. 399-409Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traditionally, High Performance Computing (HPC) and Data Intensive (DI) workloads have been executed on separate hardware using different tools for resource and application management. With increasing convergence of these paradigms, where modern applications are composed of both types of jobs in complex workflows, this separation becomes a growing overhead and the need for a common computation platform for both application areas increases. Executing both application classes on the same hardware not only enables hybrid workflows, but can also increase the usage efficiency of the system, as often not all available hardware is fully utilized by an application. While HPC systems are typically managed in a coarse grained fashion, allocating a fixed set of resources exclusively to an application, DI systems employ a finer grained regime, enabling dynamic resource allocation and control based on application needs. On the path to full convergence, a useful and less intrusive step is a hybrid resource management system that allows the execution of DI applications on top of standard HPC scheduling systems.In this paper we present the architecture of a hybrid system enabling dual-level scheduling for DI jobs in HPC infrastructures. Our system takes advantage of real-time resource utilization monitoring to efficiently co-schedule HPC and DI applications. The architecture is easily adaptable and extensible to current and new types of distributed workloads, allowing efficient combination of hybrid workloads on HPC resources with increased job throughput and higher overall resource utilization. The architecture is implemented based on the Slurm and Mesos resource managers for HPC and DI jobs. Our experimental evaluation in a real cluster based on a set of representative HPC and DI applications demonstrate that our hybrid architecture improves resource utilization by 20%, with 12% decrease on queue makespan while still meeting all deadlines for HPC jobs.

  • 150.
    Svedestedt, Hampus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Cross platform applicationswith HTML52013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis was made for Cybercom in Ostersund. They wanted an evaluation of HTML5 cross platform applications which studied HTML5 features as well as JavaScript libraries and frameworks. The resources put into mobile application development can be reduced bymaking applications that can work on all platforms instead of only natively. These types ofapplications are called cross platform applications and can be developed with specic tools.One way to develop cross platform applications is by using HTML5, which can either beused as a web application or packed into native applications using plug-ins. The purpose ofthis thesis was to create a mobile web app that can save maps to be used oine. The workwas done by evaluating frameworks for web applications. Frameworks that provide userinterface elements and features similar to those in native applications, and libraries that render maps served by map servers. Development environments for web development were also tested and evaluated. The results of the research and development were documented experience, and a HTML5 application that shows a map, has GPS functionality and can beused oine.

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