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  • 101.
    Bergqvist, Tomas
    et al.
    Umeå universitet.
    Liljekvist, Yvonne
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    van Bommel, Jorryt
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Österholm, Magnus
    Umeå universitet.
    Evaluation of a large scale professional development program2017Ingår i: Proceedings of the 41st Conference of the International Group for the Psychology of Mathematics Education: Volume 2 / [ed] B. Kaur, W.K. Ho, T.L Toh, B.H. Choy, Singapore: PME , 2017, s. 153-160Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper reports on an evaluation of the professional development program Boost for Mathematics in Sweden. 200 mathematics lessons were visited, and the teachers were interviewed after each lesson.The analysis used an analytical framework based on Lithner et al. (2010).The findings indicate that the PD-program has had a significant impact on the teachers’ knowledge about the mathematical competencies as they are presented in the national curriculum documents, and that the teaching practice has improved and give the students better possibilities todevelop the competencies.The results also show that these improvements are still present one year after the program had ended.

  • 102. Bernhard, David
    et al.
    Kulyk, Oksana
    Volkamer, Melanie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Security Proofs for Participation Privacy and Stronger Verifiability for Helios2016Rapport (Övrigt vetenskapligt)
  • 103.
    Bernhard, David
    et al.
    University of Bristol, UK.
    Oksana, Kulyk
    Technische Universität Darmstadt, Germany.
    Volkamer, Melanie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Technische Universität Darmstadt, Germany.
    Security proofs for Participation privacy, receipt-freeness and ballot privacy for the helios voting scheme2017Ingår i: ARES '17 Proceedings of the 12th International Conference on Availability, Reliability and Security, New York: Association for Computing Machinery (ACM), 2017, artikel-id UNSP 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Helios voting scheme is well studied including formal proofs for verifiability and ballot privacy. However, depending on its version, the scheme provides either participation privacy (hiding who participated in the election) or verifiability against malicious bulletin board (preventing election manipulation by ballot stuffing), but not both at the same time. It also does not provide receipt-freeness, thus enabling vote buying by letting the voters construct receipts proving how they voted. Recently, an extension to Helios, further referred to as KTV-Helios, has been proposed that claims to provide these additional security properties. However, the authors of KTV-Helios did not prove their claims. Our contribution is to provide formal definitions for participation privacy and receipt-freeness that we applied to KTV-Helios. In order to evaluate the fulfillment of participation privacy and receipt-freeness, we furthermore applied the existing definition of ballot privacy, which was also used for evaluating the security of Helios, in order to show that ballot privacy also holds for KTV-Helios

  • 104.
    Bernhoff, Niclas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Boundary Layers and Shock Profiles for the Broadwell Model2016Ingår i: International Journal of Differential Equations, ISSN 1687-9643, E-ISSN 1687-9651, Vol. 2016, s. 1-8, artikel-id 5801728Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the existence of nonlinear boundary layers and the typically nonlinear problem of existence of shock profiles for the Broadwell model, which is a simplified discrete velocity model for the Boltzmann equation. We find explicit expressions for the nonlinear boundary layers and the shock profiles. In spite of the few velocities used for the Broadwell model, the solutions are (at least partly) in qualitatively good agreement with the results for the discrete Boltzmann equation, that is the general discrete velocity model, and the full Boltzmann equation.

  • 105.
    Bernhoff, Niclas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Boundary layers for discrete kinetic models: Multicomponent mixtures, polyatomic molecules, bimolecular reactions, and quantum kinetic equations2017Ingår i: Kinetic and Related Models, ISSN 1937-5093, E-ISSN 1937-5077, Vol. 10, nr 4, s. 925-955Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider some extensions of the classical discrete Boltzmann equation to the cases of multicomponent mixtures, polyatomic molecules (with a finite number of different internal energies), and chemical reactions, but also general discrete quantum kinetic Boltzmann-like equations; discrete versions of the Nordheim-Boltzmann (or Uehling-Uhlenbeck) equation for bosons and fermions and a kinetic equation for excitations in a Bose gas interacting witha Bose-Einstein condensate. In each case we have an H-theorem and so for the planar stationary half-space problem, we have convergence to an equilibrium distribution at infinity (or at least a manifold of equilibrium distributions). In particular, we consider the nonlinear half-space problem of condensation and evaporation for these discrete Boltzmann-like equations. We assume that the flow tends to a stationary point at infinity and that the outgoing flow is known at the wall, maybe also partly linearly depending on the incoming flow. We find that the systems we obtain are of similar structures as for the classical discrete Boltzmann equation (for single species), and that previously obtained results for the discrete Boltzmann equation can be applied after being generalized. Then the number of conditions on the assigned data at the wall needed for existence of a unique solution is found. The number of parameters to be specified in the boundary conditions depends on if we have subsonic or supersonic condensation or evaporation. All our results are valid for any finite number of velocities.

  • 106.
    Bernhoff, Niclas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Discrete quantum Boltzmann equation2019Ingår i: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2132, s. 1-9, artikel-id 130011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we consider a Boltzmann equation for anyons. In particular, we study a general discrete velocity model of the equation, where the velocity variable is assumed to only take values from a given finite-such that the (finite) number of velocities is arbitrary-set of velocities. Included, as two limiting cases, is the discrete quantum Boltzmann equation (Nordheim-Boltzmann/Uehling-Uhlenbeck equation) for bosons and fermions. Mass, momentum, and energy are assumed to be conserved during collisions, and considering suitable discrete velocity models, they will also be the only collision invariants. The equilibrium distributions will be given by a transcendental equation, and only in some few cases-including the two limiting cases where they are Planckians-they will be explicitly expressed. However, there is an H-theorem, and therefore one can prove that for the spatially homogeneous equation, as time tends to infinity, as well as, for the steady equation in a half-space with slab-symmetry, as the space variable tends to infinity, the distribution function converges to an equilibrium distribution. Linearizing around an equilibrium distribution in a suitable way, we find that the obtained linearized operator has similar properties as the corresponding linearized operator for the discrete Boltzmann equation: E.g. it is symmetric and positive semi-definite. Hence, previously obtained results for the spatially homogeneous Cauchy problem and the steady half-space problem in a slab symmetry for the discrete Boltzmann equation, can be applied also in the considered quantum case.

  • 107.
    Bernhoff, Niclas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Discrete velocity models for multicomponent mixtures and polyatomic molecules without nonphysical collision invariants and shock profiles2016Ingår i: 30th International Symposium on Rarefied Gas Dynamics: RGD 30 / [ed] Andrew Ketsdever, Henning Struchtrup, American Institute of Physics (AIP), 2016, s. 040005-1-040005-8, artikel-id 040005Konferensbidrag (Refereegranskat)
    Abstract [en]

    An important aspect of constructing discrete velocity models (DVMs) for the Boltzmann equation is to obtain the right number of collision invariants. It is a well-known fact that, in difference to in the continuous case, DVMs can have extra collision invariants, so called spurious collision invariants, in plus to the physical ones. A DVM with only physical collision invariants, and so without spurious ones, is called normal. The construction of such normal DVMs has been studied a lot in the literature for single species as well as for binary mixtures. For binary mixtures also the concept of supernormal DVMs has been introduced by Bobylevand Vinerean. Supernormal DVMs are defined as normal DVMs such that both restrictions to the different species are normal as DVMs for single species.

    In this presentation we extend the concept of supernormal DVMs to the case of multicomponent mixtures and introduce it for polyatomic molecules. By polyatomic molecules we mean here that each molecule has one of a finite number of different internal energies, which can change, or not, during a collision. We will present some general algorithms for constructing such models, but also give some concrete examples of such constructions.

    The two different approaches above can be combined to obtain multicomponent mixtures with a finite number of different internal energies, and then be extended in a natural way to chemical reactions.

    The DVMs are constructed in such a way that we for the shock-wave problem obtain similar structures as for the classical discrete Boltzmann equation (DBE) for one species, and therefore will be able to apply previously obtained results for the DBE. In fact the DBE becomes a system of ordinary dierential equations (dynamical system) and the shock profiles can be seen as heteroclinic orbits connecting two singular points (Maxwellians). The previous results for the DBE then give us the existence of shock profiles for shock speeds close to a typical speed, corresponding to the sound speed in the continuous case. For binary mixtures this extension has already been addressed before by the author.

  • 108.
    Bernhoff, Niclas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Discrete Velocity Models for Polyatomic Molecules Without Nonphysical Collision Invariants2018Ingår i: Journal of statistical physics, ISSN 0022-4715, E-ISSN 1572-9613, Vol. 172, nr 3, s. 742-761Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important aspect of constructing discrete velocity models (DVMs) for the Boltzmann equation is to obtain the right number of collision invariants. Unlike for the Boltzmann equation, for DVMs there can appear extra collision invariants, so called spurious collision invariants, in plus to the physical ones. A DVM with only physical collision invariants, and hence, without spurious ones, is called normal. The construction of such normal DVMs has been studied a lot in the literature for single species, but also for binary mixtures and recently extensively for multicomponent mixtures. In this paper, we address ways of constructing normal DVMs for polyatomic molecules (here represented by that each molecule has an internal energy, to account for non-translational energies, which can change during collisions), under the assumption that the set of allowed internal energies are finite. We present general algorithms for constructing such models, but we also give concrete examples of such constructions. This approach can also be combined with similar constructions of multicomponent mixtures to obtain multicomponent mixtures with polyatomic molecules, which is also briefly outlined. Then also, chemical reactions can be added.

  • 109.
    Bernhoff, Niclas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Half-Space Problems for a Linearized Discrete Quantum Kinetic Equation2015Ingår i: Journal of statistical physics, ISSN 0022-4715, E-ISSN 1572-9613, Vol. 159, nr 2, s. 358-379Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study typical half-space problems of rarefied gas dynamics, including the problems of Milne and Kramer, for a general discrete model of a quantum kinetic equation for excitations in a Bose gas. In the discrete case the plane stationary quantum kinetic equation reduces to a system of ordinary differential equations. These systems are studied close to equilibrium and are proved to have the same structure as corresponding systems for the discrete Boltzmann equation. Then a classification of well-posed half-space problems for the homogeneous, as well as the inhomogeneous, linearized discrete kinetic equation can be made. The number of additional conditions that need to be imposed for well-posedness is given by some characteristic numbers. These characteristic numbers are calculated for discrete models axially symmetric with respect to the x-axis. When the characteristic numbers change is found in the discrete as well as the continuous case. As an illustration explicit solutions are found for a small-sized model.

  • 110.
    Bernhoff, Niclas
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Vinerean, Mirela
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Discrete Velocity Models for Mixtures Without Nonphysical Collision Invariants2016Ingår i: Journal of statistical physics, ISSN 0022-4715, E-ISSN 1572-9613, Vol. 165, nr 2, s. 434-453Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An important aspect of constructing discrete velocity models (DVMs) for the Boltzmann equation is to obtain the right number of collision invariants. It is a well-known fact that DVMs can also have extra collision invariants, so called spurious collision invariants, in plus to the physical ones. A DVM with only physical collision invariants, and so without spurious ones, is called normal. For binary mixtures also the concept of supernormal DVMs was introduced, meaning that in addition to the DVM being normal, the restriction of the DVM to any single species also is normal. Here we introduce generalizations of this concept to DVMs for multicomponent mixtures. We also present some general algorithms for constructing such models and give some concrete examples of such constructions. One of our main results is that for any given number of species, and any given rational mass ratios we can construct a supernormal DVM. The DVMs are constructed in such a way that for half-space problems, as the Milne and Kramers problems, but also nonlinear ones, we obtain similar structures as for the classical discrete Boltzmann equation for one species, and therefore we can apply obtained results for the classical Boltzmann equation.

  • 111.
    Berthold, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Inter-temporal Privacy Metrics2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Informational privacy of individuals has significantly gained importance after information technology has become widely deployed. Data, once digitalised, can be copied, distributed, and long-term stored at negligible costs. This has dramatic consequences for individuals that leave traces in the form of personal data whenever they interact with information technology, for instance, computers and phones; or even when information technology is recording the personal data of aware or unaware individuals. The right of individuals for informational privacy, in particular to control the flow and use of their personal data, is easily undermined by those controlling the information technology.

    The objective of this thesis is to study the measurement of informational privacy with a particular focus on scenarios where an individual discloses personal data to a second party which uses this data for re-identifying the individual within a set of other individuals. We contribute with privacy metrics for several instances of this scenario in the publications included in this thesis, most notably one which adds a time dimension to the scenario for modelling the effects of the time passed between data disclosure and usage. The result is a new framework for inter-temporal privacy metrics.

  • 112.
    Berthold, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    The Privacy Option Language: Specification & Implementation2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The data protection laws in Europe require that data controllers provide privacy policies to inform individuals about the prospective processing of their personal data. The ever growing expressiveness of privacy policy languages allows to specify policies in a growing number of details. This and new options for policy negotiations transformed rather general privacy policies into specific privacy contracts between the data controller and the individual.

    In this report, we specify a privacy contract language and call it the Privacy Option Language. It is modelled after the analogy between financial option contracts and data disclosures which has been presented in previous work and led to the Privacy Option notion. The language specification provides privacy by design through its data minimisation provisions, i.e., all contracts are automatically reduced to their canonical form so that individual differences in the contract formulation are inherently normalised. The language specification is extensible in two ways. First, hooks are specified in the core language and can be used to connect sublanguages. The freedom to choose any suitable sublanguage allows to specify language details independent of the core language. Second, the Privacy Option Language itself can be used as a sublanguage within a more general-domain language. We give examples for both types of extensions. Additionally, we provide tools for evaluating semantics such as human-readable presentations of Privacy Options and contract management. The definitions of the semantics are kept simple and serve as templates for more practical ones.

    All functionality can be checked by interactive tests in a standard multi-purpose programming language interpreter, since the Privacy Option Language is specified as an embedded domain-specific language within Haskell. Hands-on examples are provided along with the language specification.

  • 113.
    Berthold, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Fischer-Hübner, Simone
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Martucci, Leonardo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Pulls, Tobias
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Crime and Punishment in the Cloud: Accountability, Transparency, and Privacy2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The goal of this work is to reason on the complexity of the relationship between three non-functional requirements in cloud comput-ing; privacy, accountability, and transparency. We provide insights on the complexity of this relationship from the perspectives of end-users, cloud service providers, and third parties, such as auditors. We shed light onthe real and perceived conflicts between privacy, transparency, and accountability, using a formal definition of transparency and an analysis on how well a privacy-preserving transparency-enhancing tool may assist in achieving accountability. Furthermore, we highlight the importance of the privacy impact assessment process for the realisation of both transparency and accountability.

  • 114.
    Berthold, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Lundin, Reine
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Re-identification revisitedManuskript (preprint) (Övrigt vetenskapligt)
  • 115.
    Bhamare, Deval
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Vestin, Jonathan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Khoshkholghi, Mohammad Ali
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    IntOpt: In-Band Network Telemetry Optimization for NFV Service Chain Monitoring2019Ingår i: 2019 IEEE International Conference on Communications (ICC) Próceedings, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Managing and scaling virtual network function(VNF) service chains require the collection and analysis ofnetwork statistics and states in real time. Existing networkfunction virtualization (NFV) monitoring frameworks either donot have the capabilities to express the range of telemetryitems needed to perform management or do not scale tolarge traffic volumes and rates. We present IntOpt, a scalableand expressive telemetry system designed for flexible VNFservice chain network monitoring using active probing. IntOptallows to specify monitoring requirements for individual servicechain, which are mapped to telemetry item collection jobsthat fetch the required telemetry items from P4 (programmingprotocol-independent packet processors) programmable dataplaneelements. In our approach, the SDN controller creates theminimal number of monitoring flows to monitor the deployedservice chains as per their telemetry demands in the network.We propose a simulated annealing based random greedy metaheuristic(SARG) to minimize the overhead due to activeprobing and collection of telemetry items. Using P4-FPGA, webenchmark the overhead for telemetry collection and compareour simulated annealing based approach with a na¨ıve approachwhile optimally deploying telemetry collection probes. Ournumerical evaluation shows that the proposed approach canreduce the monitoring overhead by 39% and the total delays by57%. Such optimization may as well enable existing expressivemonitoring frameworks to scale for larger real-time networks.

  • 116.
    Björklund, Anna-Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Lärares arbete i matematiken med elever i språksvårigheter: En kvalitativ intervjustudie.2016Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta arbete kommer att handla om lärarnas förebyggande arbete för elever med språksvårigheter så de inte ska hamna i matematiksvårigheter. Syftet med detta arbete är att se vilka metoder, arbetsätt, arbetsmaterial, kompetens och kunskaper det finns hos lärarna på en skola i mellersta Sverige. Studien bygger på kvalitativa intervjuer med fem verksamma lärare i åk 1-3 som undervisar i svenska och matematik, varav en är förstelärare i matematik.

    En specialpedagog har också intervjuats som har mycket kunskap om språksvårigheter. Det som framkommit i min undersökning är att genom att arbeta med många gemensamma genomgångar, gemensam problemlösning, diskussioner för att befästa begrepp och symboler gynnar det alla elever inte bara de med språksvårigheter.

    Nyttan med studien har varit att bidra med kunskap om hur lärare kan hjälpa elever tidigt som har språksvårigheter, så de inte hamnar i matematiksvårigheter. Ambitionen har varit att komma fram till vilka olika metoder, arbetssätt och arbetsmaterial det finns för att underlätta hos eleverna i matematiken trots sina språksvårigheter. 

  • 117.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Eldh, Sigrid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Is Common Test Data the Solution to Poor Quality?: Solving the Right Problem – An Analysis of a Public Health Information System2013Ingår i: Procedia Technology: HCIST 2013 - International Conference on Health and Social Care Information Systems and Technologies / [ed] Maria Manuela Cruz-Cunha, João Varajão, Helmut Krcmar and Ricardo Martinho, Elsevier, 2013, Vol. 9, s. 1227-1236Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper reports our initial findings regarding the state of testing of software in the Swedish public health information system. At present, the system is only available through a black-box interface, i.e. through the GUI. This and other issues related to politics, management and organization indicate that much work is needed in order for the software to have the quality level expected by a safety-critical system. The proposed solution by the public health organization for raising the quality is to use an independent test database. Based on our initial understanding of the problem, we argue that there might be other solutions that would perhaps be more cost-effective and have a stronger impact on the quality of the system. Our main contribution lies in the data analysis, where we have collected the problems and suggested alternative cost-saving solutions.

  • 118.
    Blom, Martin
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Hassan, Mohammad Mahdi
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Applying clustering to analyze opinion diversity2015Ingår i: Proceedings of the 19th International Conference on Evaluation and Assessment in Software Engineering / [ed] He (Jason) Zhang, New York: Association for Computing Machinery (ACM), 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In empirical software engineering research there is an increased use of questionnaires and surveys to collect information from practitioners. Typically, such data is then analyzed based on overall, descriptive statistics. Even though this can capture the general trends there is a risk that the opinions of different (minority) sub-groups are lost. Here we propose the use of clustering to segment the respondents so that a more detailed analysis can be achieved. Our findings suggest that it can give a better insight about the survey population and the participants' opinions. This partitioning approach can show more precisely the extent of opinion differences between different groups. This approach also gives an opportunity for the minorities to be heard. Through the process significant new findings may also be obtained. In our example study regarding the state of testing and requirement activities in industry, we found several significant groups that showed significant opinion differences from the overall conclusion.

  • 119.
    Blomster, Amanda
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Institutionen för språk, litteratur och interkultur. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Fysisk aktivitet och matematiklärande: En kvalitativ studie om hur några lärare använder fysisk aktivitet i matematikundervisningen i förskoleklass2015Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of this study is to explore the use of physical activity in mathematics teaching. Through qualitative interviews with six teachers, the extent to which physical activity is used in mathematics education in pre school class was studied. The study shows how these teachers use physical activity in the education of mathematics and which effects the teachers can see that it has on the childrens mathematics learning. The result shows that physical activity is activly used by the respondents in mathematics teaching in different ways and that teachers can see positive effects of it.

  • 120.
    Bobylev, Alexander
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brantov, Andrei
    RAS, Lebedev Phys Inst, Moscow 117901, Russia.;Dukhov All Russia Res Inst Automat, Moscow, Russia..
    Bychenkov, Valerii
    RAS, Lebedev Phys Inst, Moscow 117901, Russia.;Dukhov All Russia Res Inst Automat, Moscow, Russia..
    Karpov, Stanislav
    Dukhov All Russia Res Inst Automat, Moscow, Russia..
    Potapenko, Irina
    Dukhov All Russia Res Inst Automat, Moscow, Russia.;RAS, Keldysh Inst Appl Math, Moscow 117901, Russia..
    DSMC Modeling of a Single Hot Spot Evolution Using the Landau-Fokker-Planck Equation2014Ingår i: Acta Applicandae Mathematicae - An International Survey Journal on Applying Mathematics and Mathematical Applications, ISSN 0167-8019, E-ISSN 1572-9036, Vol. 132, nr 1, s. 107-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerical solution of a fully nonlinear one dimensional in space and three dimensional in velocity space electron kinetic equation is presented. Direct Simulation Monte Carlo (DSMC) method used for the nonlinear Landau-Fokker-Planck (LFP) collision operator is combined with Particle-in-Cell (PiC) simulations. An assumption of a self-consistent ambipolar electric field is used. The illustrative simulation results for the relaxation of the initial temperature perturbation are compared with the antecedent analytical and numerical results.

  • 121.
    Bondarenko, Olga
    et al.
    Simula Research laboratory.
    Rajiullah, Mohammad
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Griwodz, Carsten
    Simula Research laboratory.
    Calvet, Lilian
    Simula Research laboratory.
    Brunstrom, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Petlund, Andreas
    Simula Research laboratory.
    Elmokashfi, Ahmed
    Simula Research laboratory.
    A Method for Hierarchical Clustering of Internet Traffic and its Use in Detecting Application-Limited FlowsManuskript (preprint) (Övrigt vetenskapligt)
  • 122. Borges, Fabio
    et al.
    Martucci, Leonardo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    iKUP keeps users' privacy in the Smart Grid2014Ingår i: Communications and Network Security (CNS), 2014 IEEE Conference on, IEEE, 2014, s. 310-318Konferensbidrag (Refereegranskat)
    Abstract [en]

    Privacy-enhancing technologies for the Smart Grid usually address either the consolidation of users’ energy consumption or the verification of billing information. The goal of this paper is to introduce iKUP, a protocol that addresses both problems simultaneously. iKUP is an efficient privacy-enhancingprotocol based on DC-Nets and Elliptic Curve Cryptography as Commitment. It covers the entire cycle of power provisioning, consumption, billing, and verification. iKUP allows: (i) utility providers to obtain a consolidated energy consumption value that relates to the consumption of a user set, (ii) utility providers to verify the correctness of this consolidated value, and (iii) the verification of the correctness of the billing information by both utility providers and users. iKUP prevents utility providers from identifying individual contributions to the consolidated value and, therefore, protects the users’ privacy. The analytical performance evaluation of iKUP is validated through simulation using as input a real-world data set with over 157 million measurements collected from 6,345 smart meters. Our results show that iKUP has a worse performance than other protocols in aggregationand decryption, which are operations that happen only once per round of measurements and, thus, have a low impactin the total protocol performance. iKUP heavily outperformsother protocols in encryption, which is the most demanded cryptographic function, has the highest impact on the overall protocol performance, and it is executed in the smart meters.

  • 123. Borges, Fábio
    et al.
    Martucci, Leonardo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Beato, Filipe
    Mühlhäuser, Max
    Secure and Privacy-Friendly Public Key Generation and Certification2014Ingår i: 2014 IEEE 13th International Conference on Trust, Security and Privacy in Computing and Communications, New York: IEEE, 2014, s. 114-121Konferensbidrag (Refereegranskat)
    Abstract [en]

    Digital societies increasingly rely on secure communication between parties. Certificate enrollment protocols are used by certificate authorities to issue public key certificates to clients. Key agreement protocols, such as Diffie-Hellman, are used to compute secret keys, using public keys as input, for establishing secure communication channels. Whenever the keys are generated by clients, the bootstrap process requires either (a) an out-of-band verification for certification of keys when those are generated by the clients themselves, or (b) a trusted server to generate both the public and secret parameters. This paper presents a novel constrained key agreement protocol, built upon a constrained Diffie-Hellman, which is used to generate a secure public-private key pair, and to set up a certification environment without disclosing the private keys. In this way, the servers can guarantee that the generated key parameters are safe, and the clients do not disclose any secret information to the servers.

  • 124.
    Borges, Fábio
    et al.
    Technische Universität Darmstad, Germany.
    Martucci, Leonardo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Mühlhäuser, Max
    Technische Universität Darmstadt, Germany.
    Analysis of privacy-enhancing protocols based on anonymity networks2012Ingår i: Smart Grid Communications (SmartGridComm), 2012 IEEE Third International Conference on, IEEE, 2012, s. 378-383Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we analyze privacy-enhancing protocols for Smart Grids that are based on anonymity networks. The underlying idea behind such protocols is attributing two distinct partial identities for each consumer. One is used to send real-time information about the power consumption, and the other for transmitting the billing information. Such protocols provide sender-anonymity for the real-time information, while consolidated data is sent for billing. In this work, the privacy properties of such protocols are analyzed, and their computational efficiencyis evaluated and compared using simulation to other solutionsbased on homomorphic encryption.

  • 125.
    Bozakov, Zdravko
    et al.
    Dell EMC.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Damjanovic, Dragana
    Mozilla.
    Riktor Evensen, Kristian
    Celerway.
    Fairhurst, Gorry
    University of Aberdeen, UK..
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Jones, Tom
    University of Aberdeen, UK..
    Mangiante, Simone
    Dell EMC.
    Papastergiou, Giorgos
    Simula.
    Ros, David
    Simula.
    Tüxen, Michael
    FH Münster, Germany.
    Welzl, Michael
    University of Oslo, Norway.
    Deliverable D2.1 - First Version of Low-Level Core Transport System2016Rapport (Refereegranskat)
    Abstract [en]

    This document presents the first version of the low-level Core Transport System in NEAT, to be used for development of a reference implementation of the NEAT System. The design of this core transport system takes into consideration the Transport Services and the API defined in Task 1.3 and in close coordination with the overall architecture (Task 1.2). To realise the basic Transport Services provided by the API, a set of low-level transport functionalities has to be provided by the NEAT core transport system. These functionalities take the formof several building blocks, or NEAT Components, each representing an associated implementation activity. Some of the components are needed to ensure the basic operation of the NEAT System—e.g., a NEAT Flow Endpoint, a callback-based NEAT API Framework, the NEAT Logic and the functionality to Connect to a name. Some other components are needed to ensure connectivity usingMiddlebox Traversal techniques (e.g., TURN), discovery of path support for different transport protocols using Happy Eyeballs mechanisms, offering end-to end Security (e.g., (D)TLS over transport), gather statistics for the users or system administrators, and the ability to apply different policies in order to influence the decision-making process of the transport system. This document describes each of these building blocks and related design choices.

  • 126.
    Bozakov, Zdravko
    et al.
    Dell EMC, Ireland.
    Mangiante, Simone
    Dell EMC, Ireland.
    Hernandez Benet, Cristian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Santos, Ricardo
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Buckley, Donagh
    Dell EMC, Ireland.
    A NEAT framework for enhanced end-host integration in SDN environments2017Ingår i: 2017 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN), IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    SDN aims to facilitate the management of increasingly complex, dynamic network environments and optimize the use of the resources available therein with minimal operator intervention. To this end, SDN controllers maintain a global view of the network topology and its state. However, the extraction of information about network flows and other network metrics remains a non-trivial challenge. Network applications exhibit a wide range of properties, posing diverse, often conflicting, demands towards the network. As these requirements are typically not known, controllers must rely on error-prone heuristics to extract them. In this work, we develop a framework which allows applications deployed in an SDN environment to explicitly express their requirements to the network. Conversely, it allows network controllers to deploy policies on end-hosts and to supply applications with information about network paths, salient servers and other relevant metrics. The proposed approach opens the door for fine grained, application-aware resource optimization strategies in SDNs

  • 127.
    Briscoe, Bob
    et al.
    BT, Ipswich IP5 3RE, Suffolk, England.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Karlstad Univ, S-65188 Karlstad, Sweden..
    Petlund, Andreas
    Simula Res Lab AS, N-1364 Fornebu, Norway..
    Hayes, David
    Univ Oslo, N-0316 Oslo, Norway..
    Ros, David
    Simula Res Lab AS, N-1364 Fornebu, Norway..
    Tsang, Ing-Jyh
    Alcatel Lucent, Bell Labs, B-2018 Antwerp, Belgium..
    Gjessing, Stein
    Univ Oslo, N-0316 Oslo, Norway..
    Fairhurst, Gorry
    Univ Aberdeen, Aberdeen AB24 3FX, Scotland..
    Griwodz, Carsten
    Simula Res Lab AS, N-1364 Fornebu, Norway..
    Welzl, Michael
    Univ Oslo, N-0316 Oslo, Norway..
    Reducing Internet Latency: A Survey of Techniques and Their Merits2016Ingår i: IEEE Communications Surveys and Tutorials, ISSN 1553-877X, E-ISSN 1553-877X, Vol. 18, nr 3, s. 2149-2196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Latency is increasingly becoming a performance bottleneck for Internet Protocol (IP) networks, but historically, networks have been designed with aims of maximizing throughput and utilization. This paper offers a broad survey of techniques aimed at tackling latency in the literature up to August 2014, as well as their merits. A goal of this work is to be able to quantify and compare the merits of the different Internet latency reducing techniques, contrasting their gains in delay reduction versus the pain required to implement and deploy them. We found that classifying techniques according to the sources of delay they alleviate provided the best insight into the following issues: 1) The structural arrangement of a network, such as placement of servers and suboptimal routes, can contribute significantly to latency; 2) each interaction between communicating endpoints adds a Round Trip Time (RTT) to latency, particularly significant for short flows; 3) in addition to base propagation delay, several sources of delay accumulate along transmission paths, today intermittently dominated by queuing delays; 4) it takes time to sense and use available capacity, with overuse inflicting latency on other flows sharing the capacity; and 5) within end systems, delay sources include operating system buffering, head-of-line blocking, and hardware interaction. No single source of delay dominates in all cases, and many of these sources are spasmodic and highly variable. Solutions addressing these sources often both reduce the overall latency and make it more predictable.

  • 128.
    Bromander, Anton
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Using Privacy Indicators to Nudge Users into Selecting Privacy Friendly Applications2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the play store today, users are shown download count, app rating, reviews, screenshots etc. when deciding to download an application, and it’s shown very conveniently. If the users however are interested in viewing privacy in- formation about the application, it is multiple clicks away and there is no default in how to display it. This is where privacy indicators come in handy. With privacy indicators, data can be analyzed and displayed to the user in a way they understand, even if they don’t understand what the data itself means and what is dangerous. This however comes with the challenge of deciding what is dangerous and what is not.

    This report creates and implements an app store with added privacy infor- mation displayed to the user in the form of a privacy indicator and some detailed information about each application. To test the effectiveness of the privacy indicator, a small scale study was conducted where it was discovered that users who were not already interested in privacy didn’t pay much at- tention to it, while those who were took it more into account when deciding to download applications.

  • 129.
    Brunström, Mats
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    An Expanded Version of Toulmin’s Model to Analyze Students’ Mathematical Reasoning in a Dynamic Software EnvironmentManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Toulmin’s model of argumentation has been used to analyse mathematical reasoning in a wide range of contexts. While conducting a recent case study of students’ mathematical reasoning in a dynamic software environment, it proved advantageous to develop an expanded version of this model to deepen the data analysis. Since this expanded model served well to discern and illustrate characteristic features in students’ reasoning, the question arose of whether it could also be useful in other cases. The present paper addresses this question, by considering further examples of students working in pairs in a dynamic software environment. The model was examined using data from two different studies, varying in the types of task and level of mathematics concerned. Transcribed data from these studies were interpreted in terms of the model to examine its applicability. Assessment of its use in all three studies shows that the expanded version of Toulmin’s model can enhance its capacity to analyse reasoning in this type of setting. At the same time, the operationalization of the model in concrete situations can sometimes be debatable, emphasising the importance of elucidating the interpretation principles used.

  • 130.
    Brunström, Mats
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Matematiska resonemang i en lärandemiljö med dynamiska matematikprogram2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Baksidestext

    Det övergripande problem som legat till grund för denna avhandling är att elever får begränsad möjlighet att utveckla sin resonemangsförmåga samtidigt som det finns dynamiska matematikprogram som kan utnyttjas för att stimulera denna förmåga. Syftet med avhandlingen är att bidra till den samlade kunskapen inom detta problemområde, dels genom att fokusera på design av uppgifter i en lärandemiljö med dynamiska matematikprogram och dels genom att studera och karakterisera de resonemang som utvecklas när elever jobbar med olika uppgifter i denna miljö. För att analysera elevernas resonemang utvecklades ett nytt analysverktyg i form av en utökad version av Toulmins modell.

    Resultat från en av studierna i avhandlingen visar att dynamiska matematikprogram i kombination med utforskande uppgifter kan stimulera till matematiska resonemang där hypoteser formuleras, undersöks och förfinas i en cyklisk process. Samtidigt visar samma studie att de resonemang som utvecklas i stor utsträckning saknar matematiskt grundade förklaringar. Detta resultat bekräftas till viss del av ytterligare en studie.  Frågan hur uppgifter bör designas för att främja matematiskt grundade resonemang har därför varit central i avhandlingen. Två av artiklarna behandlar uppgiftsdesign, men utifrån olika utgångspunkter.

  • 131.
    Brunström, Mats
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Students’ Mathematical Reasoning in a Dynamic Software EnvironmentManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Mathematical reasoning has been identified as one of the key competencies needed to master mathematics. It is also well documented that dynamic mathematics software can be utilized to provide students with opportunities to practice different aspects of mathematical reasoning. In this study an expanded version of Toulmin’s model of argumentation was used to analyze the reasoning that emerged when three student pairs used GeoGebra to explore how the different parameters influence the graph of the function y = A sin (Bx + C) + D. Several characteristic features, both promising and cautionary, were discerned in the students’ reasoning.

  • 132.
    Brunström, Mats
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Fahlgren, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Designing Prediction Tasks in a Mathematics Software Environment2015Ingår i: International Journal of Technology in Mathematics Education, ISSN 1744-2710, Vol. 22, nr 1, s. 3-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a recognized need in mathematics teaching for new kinds of task which exploit the affordances provided by new technology. This paper focuses on the design of prediction tasks to foster student reasoning about exponential functions in a mathematics software environment. It draws on the first iteration of a design based research study conducted by the authors in collaboration with four upper secondary school teachers. A task sequence was trailed with four 10th grade classes, involving a total of 85 students. The research process pinpointed key didactical variables that proved crucial in designing these tasks. As well as being useful in the task design process, the didactical variables were found to be valuable in the processes of analysis and revision. While the didactical variables identified a priori were informed by the research literature concerning reasoning and functions, those identified a posteriori deal mainly with scaffolding issues that emerged.  

  • 133.
    Brunström, Mats
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Fahlgren, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    GeoGebra - A Tool to Create Favorable Learning Situations with Emphasize on Logical Reasoning and Communication2009Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Logic reasoning and communication are general competencies, important in all areas of mathematics. We think that one of the major advantages of GeoGebra is the possibility to create favorable learning situations for these competencies. We would like to investigate these possibilities. Our main interest is to find out how students use logic reasoning and how they communicate when they work in pairs with GeoGebra. We think that investigating the validity of certain geometrical statements is a kind of task appropriate for this purpose

  • 134.
    Brunström, Mats
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Fahlgren, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Orchestration of mathematical discussions drawing on students’ computer-based work2017Ingår i: ICT in mathematics education: the future and the realities: Proceedings of MADIF 10 The tenth research seminar of the Swedish Society for Research in Mathematics Education / [ed] Johan Häggström, Eva Norén, Jorryt van Bommel, Judy Sayers, Ola Helenius, Yvonne Liljekvist, Göteborg: Svensk förening för MatematikDidaktisk Forskning - SMDF, 2017, s. 77-87Konferensbidrag (Refereegranskat)
    Abstract [en]

    Research points out the importance of following up students’ work on computerbasedtasks with whole-class discussions in which students play a central role.However, at the same time, research highlights the challenge for teachers in orchestratingsuch follow-up discussions. This paper examines whether an establishedmodel developed as guidance for teachers to orchestrate mathematical whole-classdiscussions (Stein, Engle, Smith & Hughes, 2008) could be useful in this educationalsetting. Students’ written responses to two different tasks are the main data used toexamine the model. The results indicate that the model has great potential to guidethese follow-up discussions

  • 135.
    Brunström, Mats
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Mossberg, Eva
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Vinerean-Bernhoff, Mirela
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    An exploratory approach to engineering mathematics using GeoGebra2016Konferensbidrag (Övrigt vetenskapligt)
  • 136.
    Buckley, Jim
    et al.
    Univ Limerick, Lero CSIS, Limerick, Ireland.
    Herold, Sebastian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Pruijt, Leo
    HU Univ Appl Sci, Dept ICT, NL-3513 EX Utrecht, Netherlands.
    The 4th Workshop on Software Architecture Erosion and Architectural Consistency (SAEroCon 2017)2017Ingår i: PROCEEDINGS 11TH EUROPEAN CONFERENCE ON SOFTWARE ARCHITECTURE (ECSA 2017) - COMPANION VOLUME / [ed] Book Group Author(s):ACM, Broadway, New York: Association for Computing Machinery (ACM), 2017Konferensbidrag (Övrigt vetenskapligt)
  • 137.
    Buckley, Jim
    et al.
    University of Limerick / Lero, Ireland.
    Rosik, Jacek
    University of Limerick / Lero, Ireland.
    Herold, Sebastian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Wasala, Asanka
    University of Limerick / Lero, Ireland.
    Botterweck, Götz
    University of Limerick / Lero, Ireland.
    Exton, Chris
    University of Limerick / Lero, Ireland.
    FLINTS: A Tool for Architectural-level Modeling of Features in Software Systems2016Ingår i: ECSAW 2016 Proceedings of the 2016 European Conference on Software Architecture Conference Workshops, Association for Computing Machinery (ACM), 2016Konferensbidrag (Refereegranskat)
  • 138.
    Budurushi, Jurlind
    et al.
    Detecon Int GmbH, Cologne, Germany.
    Neumann, Stephan
    Tech Univ Darmstadt, Darmstadt, Germany.
    Renaud, Karen
    Abertay Univ, Dundee, Scotland; Univ South Africa, Pretoria, South Africa.
    Volkamer, Melanie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Tech Univ Darmstadt, Darmstadt, Germany.
    Introduction to special issue on e-voting2018Ingår i: Journal of Information Security and Applications, ISSN 2214-2134, E-ISSN 2214-2126, Vol. 38, s. 122-123Artikel i tidskrift (Refereegranskat)
  • 139. Budurushi, Jurlind
    et al.
    Renaud, Karen
    Volkamer, Melanie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Woide, Marcel
    An Investigation into the Usability of Electronic Voting Systems for Complex Elections2016Ingår i: Annals ofTelecommunications, ISSN 0003-4347, Vol. 71, nr 7, s. 309-322Artikel i tidskrift (Refereegranskat)
  • 140. Budurushi, Jurlind
    et al.
    Volkamer, Melanie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Feasibility Analysis of Various Electronic Voting Systems for Complex Elections2014Ingår i: International Conference for E-Democracy and Open Government 2014 / [ed] Peter Parycek & Noella Edelmann, Krems: Donau-Universität , 2014, s. 141-152Konferensbidrag (Refereegranskat)
  • 141.
    Budzisz, Łukasz
    et al.
    Technische Universität Berlin, Berlin, Germany.
    Garcia, Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Ferrús, Ramon
    Universitat Politècnica de Catalunya, Barcelona, Spain.
    A taxonomy and survey of SCTP research2012Ingår i: ACM Computing Surveys, ISSN 0360-0300, E-ISSN 1557-7341, Vol. 44, nr 4, s. -36, artikel-id 18Artikel i tidskrift (Refereegranskat)
    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.

  • 142.
    Bui, Michael
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Pedersen, Magnus
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Implementation of a Log Agent in Microsoft Azure: and packaging it to Azure Marketplace2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    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.

  • 143.
    Bures, Miroslav
    et al.
    Czech Technical University, Czech Republic.
    Ahmed, Bestoun S.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013). Czech Technical University, Czech Republic.
    Employment of multiple algorithms for optimal path-based test selection strategy2019Ingår i: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 114, s. 21-36Artikel i tidskrift (Refereegranskat)
    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.

  • 144.
    Bönström, Daniel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Smartphone application in PhoneGap: M2C’s electric vehicle smart charger2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 145. Camenisch, Jan
    et al.
    Crispo, Bruno
    Fischer-Hübner, Simone
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    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 Papers2012Bok (Refereegranskat)
  • 146. Canova, Gamze
    et al.
    Volkamer, Melanie
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Weiler, Simon
    Poster: Password Entering and Transmission Security2014Övrigt (Övrigt vetenskapligt)
    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. 

  • 147.
    Cardellini, Valeria
    et al.
    University of Rome Tor Vergata, Rome, Italy.
    Galinac Grbac, Tihana
    Facylty of Engineering, University or Rijeka, Rijeka, Croatia .
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (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
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (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 Cardellini2018Ingår i: 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, s. 212-240Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 148.
    Carlsson, Adrian
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    On the Use of 5G for Smart Grid Inter-Substation Control Signaling2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    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.

  • 149.
    Carlsson, Maria
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Elevers rimlighetsbedömning när de löser olika typer av problemlösningsuppgifter2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Den här studien har för avsikt att ta reda på hur olika typer av problemlösningsuppgifter påverkar elevernas förmåga att rimlighetsbedöma sina lösningar och svar. Studien syftar också till att ta reda på hur elever relaterar till verkligheten när de löser olika typer av problemlösningsuppgifter. För att uppnå syftet med studien genomfördes en undersökning i flera elevgrupper i årskurs två (ålder 8 år). Resultatet på undersökningen visar att olika typer av problemlösningsuppgifter påverkar hur eleverna resonerar kring rimlighet. Resultatet från undersökningen visar också att olika typer av uppgifter påverkar hur mycket eleverna reflekterar över verkligheten. Det har även framkommit under studiens gång att det är väldigt viktigt att kunna uppfatta det muntliga resonemanget som eleverna för att kunna bedöma hur eleverna kommer fram till lösningar och svar. Mycket av förmågan att bedöma rimlighet framkommer endast genom muntliga resonemanget och är därför väldigt svårt att se i skrivna svar.

  • 150.
    Casas, Israel
    et al.
    The University of Sydney, Sydney, Australia.
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (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 environments2018Ingår i: Journal of Computational Science, ISSN 1877-7503, E-ISSN 1877-7511, Vol. 26, s. 318-331Artikel i tidskrift (Refereegranskat)
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