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  • 151. Budurushi, Jurlind
    et al.
    Volkamer, Melanie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Feasibility Analysis of Various Electronic Voting Systems for Complex Elections2014In: International Conference for E-Democracy and Open Government 2014 / [ed] Peter Parycek & Noella Edelmann, Krems: Donau-Universität , 2014, p. 141-152Conference paper (Refereed)
  • 152.
    Budzisz, Łukasz
    et al.
    Technische Universität Berlin, Berlin, Germany.
    Garcia, Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ferrús, Ramon
    Universitat Politècnica de Catalunya, Barcelona, Spain.
    A taxonomy and survey of SCTP research2012In: ACM Computing Surveys, ISSN 0360-0300, E-ISSN 1557-7341, Vol. 44, no 4, p. -36, article id 18Article in journal (Refereed)
    Abstract [en]

    The Stream Control Transmission Protocol (SCTP) is a relatively recent general-purpose transport layer protocol for IP networks that has been introduced as a complement to the well-established TCP and UDP transport protocols. Although initially conceived for the transport of PSTN signaling messages over IP networks, the introduction of key features in SCTP, such as multihoming and multistreaming, has spurred considerable research interest surrounding SCTP and its applicability to different networking scenarios. This article aims to provide a detailed survey of one of these new features—multihoming—which, as it is shown, is the subject of evaluation in more than half of all published SCTP-related articles. To this end, the article first summarizes and organizes SCTP-related research conducted so far by developing a four-dimensional taxonomy reflecting the (1) protocol feature examined, (2) application area, (3) network environment, and (4) study approach. Over 430 SCTP-related publications have been analyzed and classified according to the proposed taxonomy. As a result, a clear perspective on this research area in the decade since the first protocol standardization in 2000 is given, covering both current and future research trends. On continuation, a detailed survey of the SCTP multihoming feature is provided, examining possible applications of multihoming, such as robustness, handover support, and loadsharing.

  • 153.
    Bui, Michael
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Pedersen, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Implementation of a Log Agent in Microsoft Azure: and packaging it to Azure Marketplace2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Cloud computing is still in an early stage of development and Microsoft is now investing considerable amount of resources in the cloud. Microsoft Azure is a cloud platform developed by Microsoft and it is continuously evolving, new features are constantly being added and old features are being updated. Integration Software, which is a company that focuses on products for system integration strongly believes that cloud­-based solutions will have a significant impact on their future. This is why selling and developing solutions and services for the cloud are strategically important for them.

    The objective of this dissertation is to investigate Microsoft Azure in general and Azure Marketplace in particular. This investigation consisted of an implementation of a Microsoft Azure application and integrating this application with Azure Marketplace and evaluating the expenses for running the application. The purpose for this project is to gain practical experience and to work with new techniques and help Integration Software better understand Azure Marketplace.

    The application is a Log Agent which fetches data from an external source and resends the data to an external party (Integration Manager). Our first intention was to package and deploy the application to a newly updated Azure Marketplace. The new Azure Marketplace was never released during this dissertation so we decided to deploy the application to the existing version of Azure Marketplace. This was however not fully successful. We encountered some problems in successfully deploying the application to Azure Marketplace. The evaluations for the cost of running an Azure application were not carried out due to lack of time.

  • 154.
    Bures, Miroslav
    et al.
    Czech Technical University, Czech Republic.
    Ahmed, Bestoun S.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). Czech Technical University, Czech Republic.
    Employment of multiple algorithms for optimal path-based test selection strategy2019In: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 114, p. 21-36Article in journal (Refereed)
    Abstract [en]

    Context

    Executing various sequences of system functions in a system under test represents one of the primary techniques in software testing. The natural method for creating effective, consistent and efficient test sequences is to model the system under test and employ an algorithm to generate tests that satisfy a defined test coverage criterion. Several criteria for preferred test set properties can be defined. In addition, to optimize the test set from an economic viewpoint, the priorities of the various parts of the system model under test must be defined.

    Objective

    Using this prioritization, the test cases exercise the high-priority parts of the system under test by more path combinations than those with low priority (this prioritization can be combined with the test coverage criterion that determines how many path combinations of the individual parts of the system are tested). Evidence from the literature and our observations confirm that finding a universal algorithm that produces a test set with preferred properties for all test coverage criteria is a challenging task. Moreover, for different individual problem instances, different algorithms provide results with the best value of a preferred property. In this paper, we present a portfolio-based strategy to perform the best test selection.

    Method

    The proposed strategy first employs a set of current algorithms to generate test sets; then, a preferred property of each test set is assessed in terms of the selected criterion, and finally, the test set with the best value of a preferred property is chosen.

    Results

    The experimental results confirm the validity and usefulness of this strategy. For individual instances of 50 system under test models, different algorithms provided results having the best preferred property value; these results varied by the required test coverage level, the size of the priority parts of the model, and the selected test set preferred property criteria.

    Conclusion

    In addition to the used algorithms, the proposed strategy can be used to assess the optimality of different path-based testing algorithms and choose a suitable algorithm for the testing.

  • 155.
    Bönström, Daniel
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Smartphone application in PhoneGap: M2C’s electric vehicle smart charger2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 156. Camenisch, Jan
    et al.
    Crispo, Bruno
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Leenes, Ronald
    Russello, Giovanni
    Privacy and Identity Management for Life: 7th IFIP WG 9.2, 9.6/11.7, 11.4, 11.6 International Summer School, Trento, Italy, September 5-9, 2011. Revised Selected Papers2012Book (Refereed)
  • 157. Canova, Gamze
    et al.
    Volkamer, Melanie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Weiler, Simon
    Poster: Password Entering and Transmission Security2014Other (Other academic)
    Abstract [en]

    The most popular form of user authentication on websites is the use of passwords. When entering a password, it is crucial that the website uses HTTPS (for the entire content). However, this is often not the case. We propose PassSec - a Firefox Add-On to support users to detect password fields on which their password might be endangered. In addition, PassSec displays a non-blocking warning next to the password field, once users click into the password field. The user is provided with possible consequences of entering a password, recommendations and further information if wanted. 

  • 158.
    Cardellini, Valeria
    et al.
    University of Rome Tor Vergata, Rome, Italy.
    Galinac Grbac, Tihana
    Facylty of Engineering, University or Rijeka, Rijeka, Croatia .
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kathiravelu, Pradeeban
    INESC-ID Lisboa, Instituto Superior Técnico, Universidade de Lisboa, Portugal.
    Lo Presti, Francesco
    University or Rome tor Vergata, Rome, Italy.
    Marotta, Antonio
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Nardelli, Matteo
    University of Rome Tor Vergata, Rome, Italy.
    Luís, Veiga
    INESC-ID Lisboa/Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
    Integrating SDN and NFV with QoS-Aware Service Composition Cardellini2018In: Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools / [ed] Ivan Ganchev, Robert D. van der Mei and J.L. van den Berg, Cham, Switzerland: Springer, 2018, 1, p. 212-240Chapter in book (Refereed)
    Abstract [en]

    Traditional networks are transformed to enable full integrationof heterogeneous hardware and software functions, that are configuredat runtime, with minimal time to market, and are provided to theirend users on “as a service” principle. Therefore, a countless number ofpossibilities for further innovation and exploitation opens up. NetworkFunction Virtualization (NFV) and Software-Defined Networking (SDN)are two key enablers for such a new flexible, scalable, and service-orientednetwork architecture. This chapter provides an overview of QoS-awarestrategies that can be used over the levels of the network abstractionaiming to fully exploit the new network opportunities. Specifically, wepresent three use cases of integrating SDN and NFV with QoS-awareservice composition, ranging from the energy efficient placement of virtualnetwork functions inside modern data centers, to the deployment ofdata stream processing applications using SDN to control the networkpaths, to exploiting SDN for context-aware service compositions.

  • 159.
    Carlsson, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    On the Use of 5G for Smart Grid Inter-Substation Control Signaling2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the energy domain today we are seeing an increasing number of energy equipments used and faceing new challenges such as network reliability, distributed renewable energy, increasing network complexity and energy efficiency. The concept of smart grid control systems has recently been seen as an appropriate way to address these new challenges.

    Today, the IEC 61850 standard is one of the most common standards used for power system automation. One of the services introduced is the so-called Generic Object Oriented Substation Event (GOOSE), which is a protocol to transfer time critical messages between multiple devices in a substation. The 5th generation of mobile networks (5G) are enabling new services and applications requiring lower latency, improved energy efficiency, better reliability and massive connection density. These promises of higher reliability and lower latency could then possibly be used in the future smart grid transmissions.

    In this work, the main goal was to understand the importance of time-critical messages, such as GOOSE messages, in the IEC61850 standard, and how these possibly could be used in the new 5th generation of mobile network. A proposed experimental setup which can be used for future research within both the GOOSE messaging area itself and the Open5GCore for emulated 5G mobile networks is presented. The intension of the experimental study is to send the GOOSE messages traversing through 5G networks by Open5GCore - an emulated 5G software.

  • 160.
    Carlsson, Maria
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Elevers rimlighetsbedömning när de löser olika typer av problemlösningsuppgifter2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aims to find out how different types of problem solving tasks affect students’ ability to plausible evaluate their solutions and answers. The study also intends to find out how students relate to reality when solving different types of problem solving tasks. In order to achieve the purpose of the study, a survey was conducted in several classes with grade two students (age 8). The results of the survey shows that the type of problem solving tasks can partially affect the students’ ability to assess plausibility. The results of the survey also shows that different types of problem solving tasks, affect how much the students reflect to reality. During the study it also became clear that the oral reasoning is crucial to perceive in order to be able to assess how students come to solutions and answers. Much of the ability to assess plausibility emerges through oral reasoning and is therefore very difficult to detect in written answers.  

  • 161.
    Casas, Israel
    et al.
    The University of Sydney, Sydney, Australia.
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ranjan, Rajiv
    CSIRO, Australia.
    Wang, Lizhe
    School of Computer Science, China University of Geosciences, China.
    Zomaya, Albert
    The University of Sydney, Sydney, Australia.
    GA-ETI: An enhanced genetic algorithm for the scheduling of scientific workflows in cloud environments2018In: Journal of Computational Science, ISSN 1877-7503, E-ISSN 1877-7511, Vol. 26, p. 318-331Article in journal (Refereed)
  • 162.
    Casas, Israel
    et al.
    Australia.
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ranjan, Rajiv
    Australia, UK.
    Wang, Lizhe
    China.
    Zomaya, Albert Y.
    Australia.
    A balanced scheduler with data reuse and replication for scientific workflows in cloud computing systems2017In: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 74, p. 168-178Article in journal (Refereed)
    Abstract [en]

    Cloud computing provides substantial opportunities to researchers who demand pay-as-you-go computing systems. Although cloud provider (e.g., Amazon Web Services) and application provider (e.g., biologists, physicists, and online gaming companies) both have specific performance requirements (e.g. application response time), it is the cloud scheduler’s responsibility to map the application to underlying cloud resources. This article presents a Balanced and file Reuse-Replication Scheduling (BaRRS) algorithm for cloud computing environments to optimally schedule scientific application workflows. BaRRS splits scientific workflows into multiple sub-workflows to balance system utilization via parallelization. It also exploits data reuse and replication techniques to optimize the amount of data that needs to be transferred among tasks at run-time. BaRRS analyzes the key application features (e.g., task execution times, dependency patterns and file sizes) of scientific workflows for adapting existing data reuse and replication techniques to cloud systems. Further, BaRRS performs a trade-off analysis to select the optimal solution based on two optimization constraints: execution time and monetary cost of running scientific workflows. BaRRS is compared with a state-of-the-art scheduling approach; experiments prove its superior performance. Experiments include four well known scientific workflows with different dependency patterns and data file sizes. Results were promising and also highlighted most critical factors affecting execution of scientific applications on clouds. 

  • 163.
    Casas, Israel
    et al.
    University of Sydney, Australia; CSIRO, Data61, Canberra, ACT, Australia.
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Ranjan, Rajiv
    Newcastle University, England ; CSIRO, Data61, Canberra, ACT, Australia.
    Zomaya, Albert Y.
    University of Sydney, Australia.
    PSO-DS: a scheduling engine for scientific workflow managers2017In: Journal of Supercomputing, ISSN 0920-8542, E-ISSN 1573-0484, Vol. 73, no 9, p. 3924-3947Article in journal (Refereed)
    Abstract [en]

    Cloud computing, an important source of computing power for the scientific community, requires enhanced tools for an efficient use of resources. Current solutions for workflows execution lack frameworks to deeply analyze applications and consider realistic execution times as well as computation costs. In this study, we propose cloud user-provider affiliation (CUPA) to guide workflow's owners in identifying the required tools to have his/her application running. Additionally, we develop PSO-DS, a specialized scheduling algorithm based on particle swarm optimization. CUPA encompasses the interaction of cloud resources, workflow manager system and scheduling algorithm. Its featured scheduler PSO-DS is capable of converging strategic tasks distribution among resources to efficiently optimize makespan and monetary cost. We compared PSO-DS performance against four well-known scientific workflow schedulers. In a test bed based on VMware vSphere, schedulers mapped five up-to-date benchmarks representing different scientific areas. PSO-DS proved its efficiency by reducing makespan and monetary cost of tested workflows by 75 and 78%, respectively, when compared with other algorithms. CUPA, with the featured PSO-DS, opens the path to develop a full system in which scientific cloud users can run their computationally expensive experiments.

  • 164.
    Chavez, Karina
    et al.
    Australia.
    Goratti, L
    Italy.
    Rasheed, T.b
    Italy.
    Oljira, Dejene Boru
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Fedrizzi, R.b
    Italy.
    Riggio, R.
    Italy.
    The Evolutionary Role of Communication Technologies in Public Safety Networks2015In: Wireless Public Safety Networks 1: Overview and Challenges, Elsevier, 2015, 1, p. 21-48Chapter in book (Other academic)
    Abstract [en]

    Existing networks for public safety communications are mostly based on systems such as terrestrial trunked radio (TETRA), TETRAPOL and Project 25. These systems are mainly designed to support voice services. However, public safety communication networks are challenged to expand their scope way beyond their original functions toward more sophisticated devices and support new services including packet data communications. Therefore, governments, public safety agencies and research communities are continuously working together and are making significant progresses toward improving public safety communications capabilities. Next-generation mobile technologies are the enablers for meeting the new requirements of the public safety community. Public safety and commercial systems are typically designed and deployed to fulfill different needs and have different requirements, which are directly affecting the quality of service of the communications. The unique and vital nature of public safety affects the technical decisions that are necessary to guarantee connectivity for everyone, anywhere and anytime. For this reason, recent enhancements of the 4G long term evolution (LTE) in the field of public safety communications, such as device-to-device and group communications for mobiles in physical proximity, accrue a great opportunity to bring new services and a high-level of technological innovation to the public safety workers or first responders. We describe and analyze the evolution of public safety communication systems from the technical standpoint providing a complete overview of what is available in the market and a glimpse of future trends. Furthermore, we discuss the challenges to efficiently deploy, operate and interoperate present and future technologies for public safety communication networks and describe how these technologies can help public safety agencies to meet their expectations.

  • 165.
    Cheng, Jun
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Telco Distributed DC with Transport Protocol Enhancement for 5G Mobile Networks: A Survey2017Report (Other academic)
    Abstract [en]

    Distributed data center hosts telco virtual network functions, mixing workloads that require data transport through transport protocols with either low end-to-end latency or large bandwidth for high throughput, e.g., from tough requirements in 5G use cases. A trend is the use relatively inexpensive, off-the-shelf switches in data center networks, where the dominated transport traffic is TCP traffic. Today’s TCP protocol will not be able to meet such requirements. The transport protocol evolution is driven by transport performance (latency and throughput) and robust enhancements in data centers, which include new transport protocols and protocol extensions such as DCTCP, MPTCP and QUIC protocols and lead to intensive standardization works and contributions to 3GPP and IETF.

    By implementing ECN based congestion control instead of the packet-loss based TCP AIMD congestion control algorithm, DCTCP not only solves the latency issue in TCP congestion control caused by the switch buffer bloating but also achieves an improved performance on the packet loss and throughput. The DCTCP can also co-exist with normal TCP by applying a modern coupled queue management algorithm in the switches of DC networks, which fulfills IETF L4S architecture. MPTCP is an extension to TCP, which can be implemented in DC’s Fat tree architecture to improve transport throughput and shorten the latency by mitigating the bandwidth issue caused by TCP connection collision within the data center. The QUIC is a reliable and multiplexed transport protocol over UDP transport, which includes many of the latest transport improvements and innovation, which can be used to improve the transport performance on streaming media delivery.

    The Clos topology is a commonly used network topology in a distributed data center. In the Clos architecture, an over-provisioned fabric cannot handle full wire-speed traffic, thus there is a need to have a mechanism to handle overload situations, e.g., by scaling out the fabric. However, this will introduce more end-to-end latency in those cases the switch buffer is bloated, and will cause transport flow congestion.

    In this survey paper, DCTCP, MPTCP and QUIC are discussed as solutions for transport performance enhancement for 5G mobile networks to avoid the transport flow congestion caused by the switch buffer bloating from overloaded switch queue in data centers. 

  • 166.
    Cheng, Jun
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kovács, Benedek
    Ericsson AB.
    Darula, Marian
    Ericsson AB.
    Proposal for IEC GOOSE transport in 5G networks2018Report (Other academic)
    Abstract [en]

    Smart grid control systems have special latency and performance requirements on the underlying communication network. In 3GPP, such requirements are typically served by the so-called Critical Machine Type Communication (C-MTC) network slice. Generic Object Oriented Substation Events (GOOSE, IEC 61850-8.1) is a protocol used in power substation automation. GOOSE is a layer 2 protocol that operates via multicast over Ethernet which allows Intelligent Electronic Devices (IEDs) to exchange data horizontally between the bays within substation and between the substations, especially for interlocking, measurement and tripping signals. 3GPP 5th generation of mobile networks (5G) will support a variety of services, including Massive Machine-Type Communications (M-MTC) and Ultra-Reliable Low Latency Communications (URLLC) differentiated by the latency and reliability requirements. GOOSE is used by C-MTC in smart grid power substations, which can be a part of URLLC in 5G IoT networks.

    Experiments so far proposed to tunnel GOOSE messages in 4G Evolved Packet Core (EPC) bearers, in an IP tunnel. In this paper, we will motivate the idea of transporting GOOSE over user plane by tunneling via Ethernet over Generic Routing Encapsulation (EoGRE) and 3GPP Non-IP Data Delivery (NIDD), which will follow 3GPP standardization on 5G Standalone (SA), where the transfer latency and reliability will be governed by 5G URLLC. For 5G Non-Standalone (NSA) networks, GOOSE communication involves 5G to Long Term Evolution (LTE) interworking, LTE protocol adaptation from GTP-U/UDP to GRE on S1-U has been realized and deployed in LTE networks. In addition, to reach the right performance level, we propose a GOOSE Gateway (GW) including a 5G Modem to create unicast GOOSE messages to be transmitted over 5G networks. A congestion control algorithm, e.g. Explicit Congestion Notification (ECN), is required in the data link layer (congestion control is supposed to be solved by multicasting in the original Virtual Local Area Network (VLAN) setup). In 3GPP Release 15 standardization, ECN is proposed to be implemented by Low Latency, Low Loss, Scalable Throughput (L4S) congestion control in 5G-NodeB, 5G User Equipment (UE) and other entity. GOOSE messages could share the same ECN congestion control mechanism.

    The main contributions from this paper are: (1) Analyzed and compared GOOSE over Ethernet and GOOSE over IP. (2) Introduced a new logic to optimize GOOSE traffic on EPC user plane via non-IP Packet Data Network (PDN) data type in the 5G network. (3) Suggested to implement GOOSE GW to aggregate and unicasting GOOSE messages effectively between the substations, and to add congestion control by using ECN mechanism in 5G-NodeB and by implementing the pushback/reaction point in GOOSE GW. 

  • 167.
    Chiaro, Pasquale
    et al.
    InfoCert, Milan, Italy.
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Groß, Thomas
    University of Newcastle upon Tyne, Newcastle upon Tyne, UK.
    Krenn, Stephen
    AIT Austrian Institute of Technology GmbH, Vienna, Austria.
    Lorünser, Tomas
    AIT Austrian Institute of Technology GmbH, Vienna, Austria.
    Garcí, Ana Isabel Martinez
    ETRA Investigacion y Desarrollo, S.A., Valencia, Spain.
    Migliavacca, Andrea
    Lombardia Informatica S.p.A., Milan, Italy.
    Rannenberg, Kai
    Goethe University Frankfurt, Frankfurt, Germany.
    Slamanig, Daniel
    AIT Austrian Institute of Technology GmbH, Vienna, Austria.
    Striecks, Christoph
    AIT Austrian Institute of Technology GmbH, Vienna, Austria.
    Zanini, Alberto
    Lombardia Informatica S.p.A., Milan, Italy.
    Secure and privacy-friendly storage and data processing in the cloud2018In: Privacy and Identity Management. The Smart Revolution / [ed] Marit Hansen, Eleni KostaIgor, Nai-Fovino, Simone Fischer-Hübner, Springer, 2018, p. 153-169Conference paper (Refereed)
    Abstract [en]

    At the IFIP Summer School 2017, the two H2020 projects credential and prismacloud co-organized a workshop dedicated to introducing the necessary background knowledge and demonstrating prototypes of privacy-preserving solutions for storing, sharing, and processing potentially sensitive data in untrusted cloud environments. This paper summarizes the given presentations and presents the discussions and feedback given by the workshop attendees, including students and senior researchers from different domains as well as relevant non-academic stakeholders such as public data protection agencies. © IFIP International Federation for Information Processing 2018.

  • 168.
    Cho, Daewoong
    et al.
    School of Information Technologies, University of Sydney, Sydney, NSW, Australia .
    Bastani, Saeed
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zomaya, Albert Y
    School of Information Technologies, University of Sydney, Sydney, NSW, Australia .
    Big Data helps SDN to optimize its controllers2018In: Big Data and Software Defined Networks / [ed] Javid Taheri, London: IET Digital Library, 2018, 1, p. 389-408Chapter in book (Refereed)
    Abstract [en]

    In this chapter, we first discuss the basic features and recent issues of the SDN control plane, notably the controller element. Then, we present feasible ideas to address the SDN controller-related problems using Big Data analytics techniques. Accordingly, we propose that Big Data can help various aspects of the SDN controller to address scalability issue and resiliency problem. Furthermore, we proposed six applicable scenarios for optimizing the SDN controller using the Big Data analytics: (i) controller scale-up/out against network traffic concentration, (ii) controller scale-in for reduced energy usage, (iii) backup controller placement for fault tolerance and high availability, (iv) creating backup paths to improve fault tolerance, (v) controller placement for low latency between controllers and switches, and (vi) flow rule aggregation to reduce the SDN controller's traffic. Although real-world practices on optimizing SDN controllers using Big Data are absent in the literature, we expect scenarios we highlighted in this chapter to be highly applicable to optimize the SDN controller in the future.

  • 169.
    Cho, Daewoong
    et al.
    Univ. of Sydney, Sydney, NSW, Australia.
    Taheri, Javid
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Zomaya, Albert Y
    School of Information Technologies, University of Sydney.
    Wang, Lizhe
    China Univ. of Geosci., China.
    Virtual Network Function Placement: Towards Minimizing Network Latency and Lead Time2017In: 2017 IEEE International Conference on Cloud Computing Technology and Science (CloudCom), Piscataway: IEEE, 2017, p. 90-97Conference paper (Refereed)
    Abstract [en]

    Network Function Virtualization (NFV) is an emerging network architecture to increase flexibility and agility within operator's networks by placing virtualized services on demand in Cloud data centers (CDCs). One of the main challenges for the NFV environment is how to minimize network latency in the rapidly changing network environments. Although many researchers have already studied in the field of Virtual Machine (VM) migration and Virtual Network Function (VNF) placement for efficient resource management in CDCs, VNF migration problem for low network latency among VNFs has not been studied yet to the best of our knowledge. To address this issue in this article, we i) formulate the VNF migration problem and ii) develop a novel VNF migration algorithm called VNF Real-time Migration (VNF-RM) for lower network latency in dynamically changing resource availability. As a result of experiments, the effectiveness of our algorithm is demonstrated by reducing network latency by up to 70.90% after latency-aware VNF migrations.

  • 170.
    Chow, Lawrence
    et al.
    Stanford Univ, Stanford, CA 94305 USA.
    Collins, Bradley
    Stanford Univ, Stanford, CA 94305 USA.
    Bambos, Nicholas
    Stanford Univ, Stanford, CA 94305 USA.
    Dely, Peter
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Peylo, Christoph
    Deutsch Telekom Labs, Berlin, Germany.
    Einsiedler, Hans
    Deutsch Telekom Labs, Berlin, Germany.
    Bayer, Nico
    Deutsch Telekom Labs, Berlin, Germany.
    Channel Aware Rebuffering for Wireless Media Streaming with Handoff Control2013In: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE Press, 2013, p. 4434-4439Conference paper (Refereed)
    Abstract [en]

    Packet/frame 'rebuffering' in wireless video streaming typically considers only connectivity from the mobile terminal to its network access point (AP). However, in the presence of multiple APs with the possibility of handoffs, the overall wireless environment should be considered. We develop a model capturing joint rebuffering & handoff dynamics in wireless video streaming, and design a new channel-aware joint rebuffering & handoff control scheme, aiming to minimize the long-run average cost of video jitters and freezes. We first characterize the optimal control in the general case of multiple wireless APs/channels and multiple states per channel. Subsequently, we evaluate the system performance in key important cases, using experimental traces of wireless channel data. We explore the relationship between optimal rebuffering thresholds and overall channel dynamics, and evaluate the associated joint handoff control. The performance results demonstrate the importance of jointly managing rebuffering and handoff controls to achieve high-performance wireless video streaming.

  • 171.
    Christian, Larsson
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Utredande undersökning av NoSQL grafdatabaser: En utredande undersökning av OrientDB, ArangoDB och HypergraphDBför ett specifikt användningsfall2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The need to store large quantities of data is increasing more and more. In correlation to this the development of various kinds of databases, especially so-called ”NoSQL”-databases, is also increasing. It can be difficult to navigate in this plethora of database solutions to find the the database that best suits a specific project. This report attempts to investigate which of the databases OrientDB, ArangoDB and HypergraphDB is best suited for a specific use case where data is to be saved to represent a building structure. The criteria for the investigation are how the organization behind the database looks, how their datamodels looks, which price models they offer as well as an emperical study of the databases’ performance in the specific use case. This survey is not designed to be a general comparison, but is commissioned by a company to see which database would suit their specific project best. The investigation shows that it’s a complex task to do fair comparisons on performance between NoSQL databases but based on the criteria in this report OrientDB would be best suited for the specific use case.

  • 172.
    Christin, Delphine
    et al.
    Tech Univ Darmstadt, Secure Mobile Networking Lab, Darmstadt, Germany.
    Roßkopf, Christian
    Tech Univ Darmstadt, Secure Mobile Networking Lab, Darmstadt, Germany.
    Hollick, Matthias
    Tech Univ Darmstadt, Secure Mobile Networking Lab, Darmstadt, Germany.
    Martucci, Leonardo
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kanhere, Salil
    IncogniSense: An anonymity-preserving reputation frameworkfor participatory sensing applications2012In: Proceedings of the 10th Annual IEEE In-ternational Conference on Pervasive Computing and Communications (PerCom2012) / [ed] Silvia Giordano, Marc Langheinrich, and Albrecht Schmidt, IEEE, 2012, p. 135-143Conference paper (Refereed)
    Abstract [en]

    Reputation systems rate the contributions to participatory sensing campaigns from each user by associatinga reputation score. The reputation scores are used to weedout incorrect sensor readings. However, an adversary can de-anonmyize the users even when they use pseudonyms by linking the reputation scores associated with multiple contributions. Since the contributed readings are usually annotated with spatio-temporal information, this poses a serious breach of privacy for the users. In this paper, we address this privacy threat by proposing a framework called IncogniSense. Our system utilizes periodic pseudonyms generated using blind signature and relies on reputation transfer between these pseudonyms. The reputation transfer process has an inherent trade-off between anonymity protection and loss in reputation. We investigate by means of extensive simulations several reputation cloaking schemes that address this tradeoff differently. Our system is robust against reputation corruption and a proof-of-concept implementation demonstrates that the associated overheads are minimal.

  • 173. Christoforidis, Christos
    et al.
    Ivarsson, Niklas
    Johansson, Henrik
    Nilsson, Jonas
    Grinnemo, Karl-Johan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    SCTPTrace: An Extension of TCPTrace for SCTP2016Report (Other (popular science, discussion, etc.))
    Abstract [en]

    When it comes to analyzing TCP data and extracting the information in such a way that it becomes viewable, there are a couple of tools that can be used. One of them is TCPTrace. TCPTrace is used to analyze special dump files created from programs such as tcpdump, snoop and WinDump. TCPTrace became published for a broader public in the late 1996 by Shawn Ostermann. Since then functionalities, changes and fixes have been implemented for example the extension to create graphs and trace UDP packets. From the dump files a trace will be done, and depending on the input from the user, TCPTrace can present this information in a number of ways such as plain text, trace files and graphs, depending on the amount of information the user is looking for. The extensive information traced will be viewed and divided for each connection found. For each connection, information such as retransmits, throughput, round trip times, bytes and packets sent and received etc. can be presented.

    This project came to be, since there has been a desire to see a tool for SCTP that provides the same functionalities as TCPTrace. The project, called SCTPTrace, aimed to implement as much of the previous TCP functionalities as possible for the SCTP protocol. 

  • 174.
    Ciallellla, Alessandro
    et al.
    Sapienza Univ Roma, Dipartimento Sci Base & Applicate Ingn, Rome, Italy.
    Cirillo, Emilio
    Sapienza Univ Roma, Dipartimento Sci Base & Applicate Ingn, Rome, Italy.
    Curseu, Petre
    Babes Bolyai Univ, Dept Psychol, Cluj, Romania Open Univ Netherlands, Dept Org, Heerlen, Netherlands.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Free to move or trapped in your group: Mathematical modeling of information overload and coordination in crowded populations2018In: Mathematical Models and Methods in Applied Sciences, ISSN 0218-2025, Vol. 28, no 9, p. 1831-1856Article in journal (Refereed)
    Abstract [en]

    We present modeling strategies that describe the motion and interaction of groups of pedestrians in obscured spaces. We start off with an approach based on balance equations in terms of measures and then we exploit the descriptive power of a probabilistic cellular automaton model. Based on a variation of the simple symmetric random walk on the square lattice, we test the interplay between population size and an interpersonal attraction parameter for the evacuation of confined and darkened spaces. We argue that information overload and coordination costs associated with information processing in small groups are two key processes that influence the evacuation rate. Our results show that substantial computational resources are necessary to compensate for incomplete information - the more individuals in (information processing) groups the higher the exit rate for low population size. For simple social systems, it is likely that the individual representations are not redundant and large group sizes ensure that this non-redundant information is actually available to a substantial number of individuals. For complex social systems, information redundancy makes information evaluation and transfer inefficient and, as such, group size becomes a drawback rather than a benefit. The effect of group sizes on outgoing fluxes, evacuation times and wall effects is carefully studied with a Monte Carlo framework accounting also for the presence of an internal obstacle.

  • 175.
    Cider, Andreas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Jacobs, Max
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Byggserverövervakning: Utveckling av ett system för att synliggöra integrationsproblem2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Software in computers control many important functions in today's society and are widely used for communication but also to control equipment. For the software to work reliably it needs to be built correctly and tested extensively. To achieve reliability, a build server can be used to automatically build and test the software. This report describes how a prototype of a monitoring system for the build servers was created. The system will be monitored by a monitoring service that retrieves information from a build server using the CruiseControl.NET [10] software. The information gathered by the monitoring service will be presented on a web portal. The information retrieved from build the server goes from a high level of abstraction down to the smallest detail that is based on the log files from the build server, for example, information about compilation errors.

    The development of the monitoring system has been focused on making it possible to use cloud services and thus not restrict where a build server is located. One of the cloud services used is the Service Bus Relay [27] that handles the communication between a monitoring service and the web portal. The web portal is developed to be responsive [34] and provide support for mobile devices which give the user the freedom to visit the web portal from whatever device. The web portal uses a database to store information which enables monitoring of multiple build servers. A well-developed user management system is used on the web portal which provides administrators with an effective tool for user management. There have been several lessons learned, including the discovery of a bug in the Microsoft implementation of message handling in the Service Bus Relay.

  • 176.
    Cirillo, Emilio
    et al.
    Sapienza University, Italy.
    Colangeli, Matteo
    University of L’Aquila, Italy.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Thieu, T. K. Thoa
    Gran Sasso Science Institute, Italy.
    A lattice model for active–passive pedestrian dynamics: a quest for drafting effects2020In: Mathematical Biosciences and Engineering, ISSN 1547-1063, E-ISSN 1551-0018, Vol. 17, no 1, p. 460-477Article in journal (Refereed)
    Abstract [en]

    We study the pedestrian escape from an obscure room using a lattice gas model with twospecies of particles. One species, called passive, performs a symmetric random walk on the lattice,whereas the second species, called active, is subject to a drift guiding the particles towards the exit.The drift mimics the awareness of some pedestrians of the geometry of the room and of the location ofthe exit. We provide numerical evidence that, in spite of the hard core interaction between particles –namely, there can be at most one particle of any species per site – adding a fraction of active particlesin the system enhances the evacuation rate of all particles from the room. A similar effect is alsoobserved when looking at the outgoing particle flux, when the system is in contact with an externalparticle reservoir that induces the onset of a steady state. We interpret this phenomenon as a discretespace counterpart of the drafting effect typically observed in a continuum set–up as the aerodynamicdrag experienced by pelotons of competing cyclists.

  • 177.
    Cirillo, Emilio
    et al.
    Sapienza Univ Roma, Dipartimento Sci Base & Appl Ingn, Via A Scarpa 16, I-00161 Rome, Italy.
    Krehel, Oleh
    Eindhoven Univ Technol, ICMS, Dept Math & Comp Sci, POB 513, NL-5600 MB Eindhoven, Netherlands.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    van Santen, Rutger
    Eindhoven Univ Technol, Fac Chem Engn, ICMS, POB 513, NL-5600 MB Eindhoven, Netherlands.
    Lattice model of reduced jamming by a barrier2016In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 94, no 4, article id 042115Article in journal (Refereed)
  • 178. Cirillo, Emilio
    et al.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    van Santen, Rutger
    Particle-based modeling of flow through obstacles2019In: Complexity science: An introduction / [ed] Mark A. Peletier, Rutger A. van Santen, World Scientific, 2019Chapter in book (Refereed)
    Abstract [en]

    Particle diffusion is modified by the presence of barriers. In cells macro-molecules, behaving as obstacles, slow down the dynamics so that the mean-square displacement of molecules grows with time as a power law with exponent smaller than one. In different situations, such as grain and pedestrian dynamics, it can happen that an obstacle can accelerate the dynamics. In the framework of very basic models, we study the time needed by particles to cross a strip for different bulk dynamics and discuss the effect of obstacles. We find that in some regimes such a residence time is not monotonic with respect to the size and the position of the obstacles. We can then conclude that, even in very elementary systems where no interaction among particles is considered, obstacles can either slow down or accelerate the particle dynamics depending on their geometry and position.

  • 179.
    Cirillo, Emilio N. M.
    et al.
    Sapienza Univ Roma, Dipartimento Sci Base & Appl Ingn, Via A Scarpa 16, I-00161 Rome, Italy.
    Colangeli, Matteo
    Gran Sasso Sci Inst, Viale F Crispi 7, I-00167 Laquila, Italy.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Blockage-induced condensation controlled by a local reaction2016In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 94, no 4Article in journal (Refereed)
    Abstract [en]

    We consider the setup of stationary zero range models and discuss the onset of condensation induced by a local blockage on the lattice. We show that the introduction of a local feedback on the hopping rates allows us to control the particle fraction in the condensed phase. This phenomenon results in a current versus blockage parameter curve characterized by two nonanalyticity points.

  • 180.
    Cirillo, Emilio N.M.
    et al.
    Sapienza Universit`a di Roma, Italy.
    Colangeli, Matteo
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Muntean, Stela Andrea
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A lattice model approach to the morphology formation from ternary mixtures during the evaporation of one component2019In: The European Physical Journal Special Topics, ISSN 1951-6355, E-ISSN 1951-6401, Vol. 228, no 1, p. 55-68Article in journal (Refereed)
    Abstract [en]

    Stimulated by experimental evidence in the field of solution-born thin films, we study the morphology formation in a three state lattice system subjected to the evaporation of one component. The practical problem that we address is the understanding of the parameters that govern morphology formation from a ternary mixture upon evaporation, as is the case in the fabrication of thin films from solution for organic photovoltaics. We use, as a tool, a generalized version of the Potts and Blume-Capel models in 2D, with the Monte Carlo Kawasaki-Metropolis algorithm, to simulate the phase behaviour of a ternary mixture upon evaporation of one of its components. The components with spin 1, −1 and 0 in the Blume-Capel dynamics correspond to the electron-acceptor, electron-donor and solvent molecules, respectively, in a ternary mixture used in the preparation of the active layer films in an organic solar cell. Furthermore, we introduce parameters that account for the relative composition of the mixture, temperature, and interaction between the species in the system. We identify the parameter regions that are prone to facilitate the phase separation. Furthermore, we study qualitatively the types of formed configurations. We show that even a relatively simple model, as the present one, can generate key morphological features, similar to those observed in experiments, which proves the method valuable for the study of complex systems.

  • 181. Cirillo, E,N.M
    et al.
    Colangeli, M.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Stationary currents in particle systems with constrained hopping rates2016In: Journal of Non-Equilibrium Thermodynamics, ISSN 0340-0204, E-ISSN 1437-4358, Vol. 41, no 2, p. 99-106Article in journal (Refereed)
  • 182.
    Cirillo, E.N.M.
    et al.
    Dipartimento di Scienze di Base e Applicate per l’Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, I–00161, Roma, Italy.
    Colangeli, M
    Dipartimento di Ingegneria e Scienze dell’Informazione e Matematica, Università degli Studi dell’Aquila, Via Vetoio, 67100 L’Aquila, Italy.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Trapping in bottlenecks: Interplay between microscopic dynamics and large scale effects2017In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 488, no 11, p. 30-38Article in journal (Refereed)
    Abstract [en]

    We investigate the appearance of trapping states in pedestrian flows through bottlenecks as a result of the interplay between the geometry of the system and the microscopic stochastic dynamics. We model the flow through a bottleneck via a Zero Range Process on a one-dimensional periodic lattice. Particle are removed from the lattice sites with rates proportional to the local occupation numbers. The bottleneck is modeled by a particular site of the lattice whose updating rate saturates to a constant value as soon as the local occupation number exceeds a fixed threshold. We show that for any finite value of the threshold the stationary particle current saturates to the limiting bottleneck rate when the total particle density in the system exceeds a critical value corresponding to the bottleneck rate itself.

  • 183.
    Colangeli, M.
    et al.
    LAquila, Italy.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Richardson, Omar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Thieu, T. K. T.
    LAquila, Italy.
    Modelling interactions between active and passive agents moving through heterogeneous environments2018In: Crowd Dynamics: volume 1 / [ed] Livio Gibelli, Nicola Bellomo, Basel: Springer , 2018, p. 211-257Chapter in book (Refereed)
    Abstract [en]

    We study the dynamics of interacting agents from two distinct intermixed populations: one population includes active agents that follow a predetermined velocity field, while the second population contains exclusively passive agents, i.e., agents that have no preferred direction of motion. The orientation of their local velocity is affected by repulsive interactions with the neighboring agents and environment. We present two models that allow for a qualitative analysis of these mixed systems. We show that the residence times of this type of systems containing mixed populations is strongly affected by the interplay between these two populations. After showing our modelling and simulation results, we conclude with a couple of mathematical aspects concerning the well-posedness of our models.

  • 184.
    Colangeli, M.
    et al.
    L.Aquila Italy.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Richardson, Omar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Thieu, T.K.T.
    L.Aquila Italy.
    Modelling interactions between active and passive agents moving through heterogeneous environments2019In: Crowd Dynamics: Vol. 1: Theory, Models and Safety Problems / [ed] G. Libelli, N. Bellomo, Birkhäuser Verlag, 2019, p. 211-254Chapter in book (Refereed)
  • 185.
    Colesky, Michael
    et al.
    Nijmegen, The Netherlands.
    Demetzou, Katerina
    Nijmegen, The Netherlands.
    Fritsch, Lothar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Herold, Sebastian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Helping Software Architects Familiarize with the General Data Protection Regulation2019In: 2019 IEEE International Conference on Software Architecture Companion (ICSA-C), IEEE , 2019, p. 226-229Conference paper (Refereed)
    Abstract [en]

    Abstract—The General Data Protection Regulation (GDPR)impacts any information systems that process personal datain or from the European Union. Yet its enforcement is stillrecent. Organizations under its effect are slow to adopt itsprinciples. One particular difficulty is the low familiarity withthe regulation among software architects and designers. Thedifficulty to interpret the content of the legal regulation ata technical level adds to that. This results in problems inunderstanding the impact and consequences that the regulationmay have in detail for a particular system or project context.In this paper we present some early work and emergingresults related to supporting software architects in this situation.Specifically, we target those who need to understand how theGDPR might impact their design decisions. In the spirit ofarchitectural tactics and patterns, we systematically identifiedand categorized 155 forces in the regulation. These results formthe conceptual base for a first prototypical tool. It enablessoftware architects to identify the relevant forces by guidingthem through an online questionnaire. This leads them to relevantfragments of the GDPR and potentially relevant privacy patterns.We argue that this approach may help software professionals,in particular architects, familiarize with the GDPR and outlinepotential paths for evaluation.

  • 186.
    Corbetta, Alessandro
    et al.
    Eindhoven University of Technology.
    Lee, Chung-Min
    California State University Long Beach.
    Benzi, Roberto
    University of Rome Tor Vergata.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Toschi, Federico
    Eindhoven University of Technology.
    Fluctuations around mean walking behaviors in diluted pedestrian flows2017In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 95, no 3Article in journal (Refereed)
    Abstract [en]

    Understanding and modeling the dynamics of pedestrian crowds can help with designing and increasing the safety of civil facilities. A key feature of a crowd is its intrinsic stochasticity, appearing even under very diluted conditions, due to the variability in individual behaviors. Individual stochasticity becomes even more important under densely crowded conditions, since it can be nonlinearly magnified and may lead to potentially dangerous collective behaviors. To understand quantitatively crowd stochasticity, we study the real-life dynamics of a large ensemble of pedestrians walking undisturbed, and we perform a statistical analysis of the fully resolved pedestrian trajectories obtained by a yearlong high-resolution measurement campaign. Our measurements have been carried out in a corridor of the Eindhoven University of Technology via a combination of Microsoft Kinect 3D range sensor and automatic head-tracking algorithms. The temporal homogeneity of our large database of trajectories allows us to robustly define and separate average walking behaviors from fluctuations parallel and orthogonal with respect to the average walking path. Fluctuations include rare events when individuals suddenly change their minds and invert their walking directions. Such tendency to invert direction has been poorly studied so far, even if it may have important implications on the functioning and safety of facilities. We propose a model for the dynamics of undisturbed pedestrians, based on stochastic differential equations, that provides a good agreement with our field observations, including the occurrence of rare events.

  • 187.
    Coutinho, Nuno
    et al.
    Universidade de Aveiro, Portugal.
    Matos, Ricardo
    Universidade de Aveiro, Portugal.
    Marques, Carlos
    Universidade de Aveiro, Portugal.
    Reis, Andre
    Universidade de Aveiro, Portugal.
    Sargento, Susana
    Universidade de Aveiro, Portugal.
    Chakareski, Jacob
    University of Alabama, United States.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Dynamic Dual-Reinforcement-Learning Routing Strategies for Quality of Experience-aware Wireless Mesh Networking2015In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 88, no 269, article id 285Article in journal (Refereed)
    Abstract [sv]

    The impact of transmission impairments such as loss and latency on user perceived quality(QoE) depends on the service type. In a real network, multiple service types such as audio,video, and data coexist. This makes resource management inherently complex and difficultto orchestrate. In this paper, we propose an autonomous Quality of Experience managementapproach for multiservice wireless mesh networks, where individual mesh nodes apply rein-forcement learning methods to dynamically adjust their routing strategies in order to maxi-mize the user perceived QoE for each flow. Within the forwarding nodes, we develop a novelpacket dropping strategy that takes into account the impact on QoE. Finally, a novel sourcerate adaptation mechanism is designed that takes into account the expected QoE in order tomatch the sending rate with the available network capacity. An evaluation of our mechanismsusing simulations demonstrates that our approach is superior to the standard approaches,AODV and OLSR, and effectively balances the user perceived QoE between the service flows.

  • 188.
    Curado, Marilia
    et al.
    Univ Coimbra, Dept Informat Engn, P-3000 Coimbra, Portugal.;Univ Coimbra, Ctr Informat & Syst, Lab Commun & Telemat, P-3000 Coimbra, Portugal..
    Ganchev, Ivan
    TRC, Limerick, Ireland.;Plovdiv Univ Paisii Hilendarski, Plovdiv, Bulgaria..
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Koucheryavy, Yevgeni
    TUT, Dept Elect & Commun Engn, Pretoria, South Africa..
    Guest editorial: Special issue on mobile wireless networks2016In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 107, p. 145-147Article in journal (Refereed)
  • 189.
    Dahlberg, Love
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Dynamic algorithm selection for machine learning on time series2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We present a software that can dynamically determine what machine learning algorithm is best to use in a certain situation given predefined traits. The produced software uses ideal conditions to exemplify how such a solution could function. The software is designed to train a selection algorithm that can predict the behavior of the specified testing algorithms to derive which among them is the best. The software is used to summarize and evaluate a collection of selection algorithm predictions to determine  which testing algorithm was the best during that entire period. The goal of this project is to provide a prediction evaluation software solution can lead towards a realistic implementation.

  • 190.
    Dahlberg, Rasmus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Aggregating Certificate Transparency Gossip Using Programmable Packet Processors2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Certificate Transparency (CT) logs are append-only tamper-evident data structures that can be verified by anyone. For example, it is possible to challenge a log to prove certificate inclusion (membership) and log consistency (append-only, no tampering) based on partial information. While these properties can convince an entity that a certificate is logged and not suddenly removed in the future, there is no guarantee that anyone else observes the same consistent view. To solve this issue a few gossip protocols have been proposed, each with different quirks, benefits, assumptions, and goals. We explore CT gossip below the application layer, finding that packet processors such as switches, routers, and middleboxes can aggregate gossip passively or actively to achieve herd immunity: (in)direct protection against undetectable log misbehaviour. Throughout the thesis we describe, instantiate, and discuss passive aggregation of gossip messages for a restricted data plane programming language: P4. The concept of active aggregation is also introduced. We conclude that (i) aggregation is independent of higher-level transparency applications and infrastructures, (ii) it appears most prominent to aggregate Signed Tree Heads (STHs) in terms of privacy and scalability, and (iii) passive aggregation can be a long-term solution if the CT ecosystem adapts. In other words, not all sources of gossip must be encrypted to preserve privacy.

  • 191.
    Dahlberg, Rasmus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Pulls, Tobias
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Standardized Syslog Processing: Revisiting Secure Reliable Data Transfer and Message Compression2016Report (Other academic)
    Abstract [en]

    Today's computer logs are like smoking guns and treasure maps in case of suspicious system activities: they document intrusions, and log crucial information such as failed system updates and crashed services. An adversary thus has a clear motive to observe, alter, and delete log entries, considering that she could (i) start by using the log's content to identify new security vulnerabilities, and (ii) exploit them without ever being detected. With this in mind we consider syslog standards and open source projects that safeguard events during the storage and transit phases, and examine how data compression effects security. We conclude that there are syslog standards in place that satisfy security on a hop-by-hop basis, that there are no such standards for secure storage, and that message compression is not recommended during transit.

  • 192.
    Dahlberg, Rasmus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Pulls, Tobias
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Verifiable Light-Weight Monitoring for Certificate Transparency Logs2018In: Secure IT Systems. NordSec 2018: Lecture Notes in Computer Science, vol. 11252 / [ed] N. Gruschka, Springer, 2018, p. 171-183Conference paper (Refereed)
    Abstract [en]

    Trust in publicly verifiable Certificate Transparency (CT) logs is reduced through cryptography, gossip, auditing, and monitoring. The role of a monitor is to observe each and every log entry, looking for suspicious certificates that interest the entity running the monitor. While anyone can run a monitor, it requires continuous operation and copies of the logs to be inspected. This has lead to the emergence of monitoring as-a-service: a trusted third-party runs the monitor and provides registered subjects with selective certificate notifications. We present a CT/bis extension for verifiable light-weight monitoring that enables subjects to verify the correctness of such certificate notifications, making it easier to distribute and reduce the trust which is otherwise placed in these monitors. Our extension supports verifiable monitoring of wild-card domains and piggybacks on CT’s existing gossip-audit security model. 

  • 193.
    Dahlberg, Rasmus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Pulls, Tobias
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Peeters, Roel
    Katholieke Universiteit Leuven, Belgium.
    Efficient Sparse Merkle Trees: Caching Strategies and Secure (Non-)Membership Proofs2016In: Secure IT Systems: 21st Nordic Conference, NordSec 2016, Oulu, Finland, November 2-4, 2016. Proceedings / [ed] Billy Bob Brumley, Juha Röning, Springer, 2016, p. 199-215Conference paper (Refereed)
    Abstract [en]

    A sparse Merkle tree is an authenticated data structure based on a perfect Merkle tree of intractable size. It contains a distinct leaf for every possible output from a cryptographic hash function, and can be simulated efficiently because the tree is sparse (i.e., most leaves are empty). We are the first to provide complete, succinct, and recursive definitions of a sparse Merkle tree and related operations. We show that our definitions enable efficient space-time trade-offs for different caching strategies, and that verifiable audit paths can be generated to prove (non-)membership in practically constant time (<4 ms) when using SHA-512/256. This is despite a limited amount of space for the cache—smaller than the size of the underlying data structure being authenticated—and full (concrete) security in the multi-instance setting.

  • 194.
    Dahlberg, Rasmus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Pulls, Tobias
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Vestin, Jonathan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Høiland-Jørgensen, Toke
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Aggregation-Based Gossip for Certificate TransparencyOther (Other academic)
    Abstract [en]

    Certificate Transparency (CT) is a project that mandates public logging of TLS certificates issued by certificate authorities. While a CT log is designed to be trustless, it relies on the assumption that every client sees and cryptographically verifies the same log. The solution to this problem is a gossip mechanism that ensures that clients share the same view of the logs. Despite CT being added to Google Chrome, no gossip mechanism is pending wide deployment. We suggest an aggregation-based gossip mechanism that passively observes cryptographic material that CT logs emit in plaintext, aggregating at packet processors and periodically verifying log consistency off-path. Based on 20 days of RIPE Atlas measurements that represents clients from 3500 autonomous systems and 40% of the IPv4 space, our proposal can be deployed incrementally for a realistic threat model with significant protection against undetected log misbehavior. We also discuss how to instantiate aggregation-based gossip on a variety of packet processors, and show that our P4 and XDP proof-of-concepts implementations run at line-speed.

  • 195.
    Dahlin, Mathilda
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Avkodning av cykliska koder - baserad på Euklides algoritm2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today’s society requires that transformation of information is done effectively and correctly. In other words, the received message must correspond to the message being sent. There are a lot of decoding methods to locate and correct errors. The main purpose in this degree project is to study one of these methods based on the Euclidean algorithm. Thereafter an example will be illustrated showing how the method is used when decoding a three - error correcting BCH code. To begin with, fundamental concepts about coding theory are introduced. Secondly, linear codes, cyclic codes and BCH codes - in that specific order - are explained before advancing to the decoding process. The results show that correcting one or two errors is relatively simple, but when three or more errors occur it becomes much more complicated. In that case, a specific method is required.

  • 196.
    Darle, Mona
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Karlsson, Linnéa Karlsson
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Rektorers resursfördelning.: Faktorer som påverkar rektorers resursfördelning till matematikundervisningen av särskilt begåvade elever.2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    How school works with gifted students depends on the pedagogical leadership of the principals’ and their decisions regarding the distribution of resources. It’s these decisions that define how the students develop and if they get the right kind of stimulants that they need. The aim of this study is to examine how the frame factor theory influences the principals’ work with distributing resources for gifted students in mathematics. This study have been using interviews as method to find out how the frame factor theory influences principals work. The result of the study shows that principals instantly draw parallels to the budget in the question of distribution of resources, but also link this to several other framework factors that interact with each other. All of the principals state that the teachers’ competence is important in order to stimulate gifted students in mathematics. The conclusion of this study is that the principals are controlled by several of the factors in the frame factor theory regarding the distributing resources for gifted students in mathematics. The results from the study can increase the teachers’ knowledge, and other colleagues, and hopefully it can increase an awareness of how the principals' work regarding distributing resources for gifted students in mathematics are affected by the frame factor theory in their line of work every day.

  • 197.
    de Bonis, Ida
    et al.
    Universitá Giustino Fortunato, Italy .
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Existence of weak solutions to a nonlinear reaction-diffusion system with singular sources2017In: Electronic Journal of Differential Equations, ISSN 1550-6150, E-ISSN 1072-6691, Vol. 2017, no 202, p. 1-16Article in journal (Refereed)
    Abstract [en]

    We discuss the existence of a class of weak solutions to a nonlinear parabolic system of reaction-diffusion type endowed with singular production terms by reaction. The singularity is due to a potential occurrence of quenching localized to the domain boundary. The kind of quenching we have in mind is due to a twofold contribution: (i) the choice of boundary conditions, modeling in our case the contact with an infinite reservoir filled with ready-to-react chemicals and (ii) the use of a particular nonlinear, non-Lipschitz structure of the reaction kinetics. Our working techniques use fine energy estimates for approximating non-singular problems and uniform control on the set where singularities are localizing.

  • 198.
    Dely, Peter
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Chow, Lawrence
    Stanford Univ, Stanford, CA 94305 USA..
    Bambos, Nicholas
    Stanford Univ, Stanford, CA 94305 USA..
    Bayer, Nico
    Telekom Innovat Labs, D-10587 Berlin, Germany..
    Einsiedler, Hans
    Telekom Innovat Labs, D-10587 Berlin, Germany..
    Peylo, Christoph
    Telekom Innovat Labs, D-10587 Berlin, Germany..
    BEST-AP: Non-intrusive estimation of available bandwidth and its application for dynamic access point selection2014In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 39, p. 78-91Article in journal (Refereed)
    Abstract [en]

    The coverage area of Access Points CAPS) in Wireless Local Area Networks (WLANs) often overlaps considerably. Hence, a station can potentially associate with many APs. In traditional IEEE 802.11 systems, the station associates to the AP with the strongest signal. This strategy may result in load imbalance between APs and thus low overall network throughput. This paper proposes a new mechanism for selecting the "best" AP based on a novel available bandwidth estimation scheme. The available bandwidth provided by an AP depends mainly on the signal quality and the load on the wireless channel. Based on measurements we first analyze how those factors vary stochastically over time and motivate why a frequent estimation of available bandwidth is necessary. We then develop BEST-AP, a system for Bandwidth ESTimation of Access Points, which uses regular data traffic to estimate the available bandwidth from all APs in reach in a non-intrusive way, even if they are on a different channel. Based on OpenFlow, BEST-AP allows the station to be associated with multiple APs simultaneously and to switch between APs with low overhead. Using the available bandwidth estimates, the system exploits the "best" AP for longer duration while probing the less good APs for shorter durations to update the bandwidth estimations. The evaluation in a WLAN testbed shows that with background load created from real WLAN traces, the dynamic selection of APs improves the throughput of a station by around 81%, compared to a static selection. When the station is mobile, the throughput increases by 176% on average.

  • 199.
    Dely, Peter
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Chow, Lawrence
    USA.
    Bambos, Nicholas
    USA.
    Bayer, Nico
    Germany.
    Einsiedler, Hans
    Germany.
    Peylo, Christoph
    Germany.
    Mellado, Daniel
    Spain.
    Sanchez, Miguel
    Spain.
    A software-defined networking approach for handover management with real-time video in WLANs2013In: Journal of Modern Transportation, ISSN 2095-087X, E-ISSN 2196-0577, Vol. 21, no 1, p. 58-65Article in journal (Refereed)
  • 200.
    Dely, Peter
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Vestin, Jonathan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    CloudMAC - Using OpenFlow to Process 802.11 MAC Frames in the Cloud2013In: PIK - Praxis der Informationsverarbeitung und Kommunikation, ISSN 0930-5157, Vol. 36, no 1, p. 53-Article in journal (Refereed)
1234567 151 - 200 of 909
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