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  • 1001. Zhang, Xiaojing
    et al.
    Lindberg, Therese
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Xiong, N.
    Vyatkin, Valeriy
    Mousavi, Atash
    Cooling Energy Consumption Investigation of Data Center IT Room with Vertical Placed Server2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 2047-2052Article in journal (Refereed)
    Abstract [en]

    As energy consumption by cooling data center IT equipment can be over 40 % of total energy consumption, efficient cooling for large data centers is essential for reducing operation costs. Modern data centers are complex systems involving IT facilities, power system, cooling and ventilation systems. In our previous work, literature study was made to investigate available data center energy consumption models; and energy consumption models for data center IT room with distributed air flow control were developed. In this paper, the models are further extended and developed to cover the combined distributed air flow control and vertical placed servers in raised floor ventilation system. Simulation of the three types of ventilation systems with Even load, Idle server and Uneven load scenarios showed that significant cooling energy consumed by a traditional ventilation system can be saved by applying the proposed new concept and method. (C) 2017 The Authors. Published by Elsevier Ltd.

  • 1002. Zibuschka, Jan
    et al.
    Fritsch, Lothar
    Norsk Regnesentral.
    A hybrid approach for highly available & secure storage of pseudo-SSO credentials2012In: Secure IT Systems: 17th Nordic Conference, NordSec 2012, Karlskrona, Sweden, October 31 – November 2, 2012. Proceedings, Springer, 2012, p. 169-183Conference paper (Refereed)
    Abstract [en]

    Abstract: We present a novel approach for password/credential storage in Pseudo-SSO scenarios based on a hybrid password hashing/password syncing approach that is directly applicable to the contemporary Web. The approach supports passwords without requiring modification of the server side and thus is immediately useful; however, it may still prove useful for storing more advanced credentials in future SSO and identity management scenarios, and offers a high level of security. Keywords. Single sign-on, authentication, syncing, hashing.

  • 1003.
    Zibuschka, Jan
    et al.
    Goethe University.
    Fritsch, Lothar
    Goethe University.
    Radmacher, Mike
    Goethe University.
    Scherner, Tobias
    Goethe University.
    Rannenberg, Kai
    Goethe University.
    Enabling privacy of real-life LBS: A platform for flexible mobile service provisioning2007In: New Approaches for Security, Privacy and Trust in Complex Environments, Springer, 2007, p. 325-336Conference paper (Refereed)
    Abstract [en]

    Privacy in computerized environments is perceived very differently depending on the respective point of view. Often "privacy enhancing technologies" - initiated by the user, as a measure of self-defense - are seen as conflicting with business goals such as cost-efficiency, revenue assurance, and options for further business development based on existing data. This paper presents the design and implementation of an architecture and prototype for privacy-friendly, interoperable location-based services (LBS), based on intermediation of location data via a location middleware component. The aim is to combine privacy-friendliness, efficiency, and market potential. Therefore the security interests of the stakeholders are analyzed and an architecture solution including an intermediary is introduced. Then the prototype implementation (at a mobile operator) is described and the usage of the prototype for a commercial service and product offer by the operator involved in the development is discussed.

  • 1004. Zola, Enria
    et al.
    Barcelo-Arroyo, Francisco
    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.
    Expected Bit Rate for Terminals Moving According to the Random Waypoint Model in a WLAN Cell2013Conference paper (Refereed)
    Abstract [en]

    The IEEE 802.11 standard defines the different bit rates and modulation schemes to which a WLAN device may adapt according to the channel quality. User mobility may also have an impact on the available bit rate. This paper presents a study of the bit rate evolution along time for devices that move according to the Random Waypoint mobility pattern in WLAN cells. Simulation has been applied in order to obtain statistical results that permit to characterize the evolution of the bit rate behavior along time and to compute average results in the ideal case (without interference) and in the presence of interfering devices. Our results can be useful in the solution of optimization problems in which decision on where to connect must be taken based on some minimum guaranteed bit rate. They also can be useful in the design of inter and intra-cell handover methods and load balancing schemes.

  • 1005. Zola, Enrica
    et al.
    Barcelo, Francisco
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Multi-objective Optimization of WLAN Associations with Improved Handover Costs2014In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 11Article in journal (Refereed)
    Abstract [en]

    The deployment of a large number of access points in public areas presents a new paradigm in which a given station may be served by more than one access point at a time. Recently, a network model has been proposed to derive the optimal association strategy for the stations by solving a linear optimization problem. According to that model, a station cannot download data while performing a handover. In this letter, we demonstrate that, even in static conditions (i.e., no mobility and constant load in the cell), an association strategy can force a handover. We thus propose a multi-objective optimization function that maximizes the download rates and minimizes the number of handovers. As a handover implies an extra cost due to necessary signaling to be exchanged, we propose a new handover cost function that takes into account the extra bandwidth. Using the new strategy, the system throughput slightly decreases, and the number of handovers is reduced.

  • 1006. Zola, Enrica
    et al.
    Dely, Peter
    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.
    Barcelo-Arroyo, Francisco
    Robust Association for Multi-radio Devices under Coverage of Multiple Networks2013Conference paper (Refereed)
  • 1007. Zola, Enrica
    et al.
    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.
    Energy Efficient Control of Virtual Machine Consolidation under Uncertain Input Parameters for the Cloud2015In: Proceedings of the Workshop on Engineering and Control for Reliable Cloud Services, Ghent, Belgium, September 2015, 2015Conference paper (Refereed)
  • 1008.
    Zola, Enrica
    et al.
    UPC, Dept Network Engn, Barcelona, Spain.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Energy Efficient Virtual Machine Consolidation under Uncertain Input Parameters for Green Data Centers2015In: 2015 IEEE 7th International Conference on Cloud Computing Technology and Science (CloudCom), IEEE, 2015, p. 436-439Conference paper (Refereed)
    Abstract [en]

    Reducing the energy consumption of data centers and the Cloud is very important in order to lower CO2 footprint and operational cost (OPEX) of a Cloud operator. To this extent, it becomes crucial to minimise the energy consumption by consolidating the number of powered-on physical servers that host the given virtual machines (VMs). In this work, we propose a novel approach to the energy efficient VM consolidation problem by applying Robust Optimisation Theory. We develop a mathematical model as a robust Mixed Integer Linear Program under the assumption that the input to the problem (e.g. resource demands of the VMs) is not known precisely, but varies within given bounds. A numerical evaluation shows that our model allows the Cloud Operator to tradeoff between the power consumption and the protection from more severe and unlikely deviations of the uncertain input.

  • 1009.
    Zola, Enrica
    et al.
    Universitat Politècnica de Catalunya (UPC), Barcelona.
    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.
    Optimising for Energy or Robustness? Trade-off for VM Consolidation under Uncertainty2016In: Optimization Letters, ISSN 1862-4472, E-ISSN 1862-4480Article in journal (Refereed)
    Abstract [en]

    Reducing the energy consumption of virtualized datacenters and the Cloud is very important in order to lower CO2 footprint and operational cost of a Cloud operator. However, there is a trade-off between energy consumption and perceived application performance. In order to save energy, Cloud operators want to consolidate as many Virtual Machines (VM) on the fewest possible physical servers, possibly involving overbooking of resources. However, that may involve SLA violations when many VMs run on peak load. Such consolidation is typically done using VM migration techniques, which stress the network. As a consequence, it is important to find the right balance between the energy consumption and the number of migrations to perform. Unfortunately, the resources that a VM requires are not precisely known in advance, which makes it very difficult to optimise the VM migration schedule. In this paper, we therefore propose a novel approach based on the theory of robust optimisation. We model the VM consolidation problem as a robust Mixed Integer Linear Program and allow to specify bounds for e.g. resource requirements of the VMs. We show that, by using our model, Cloud operators can effectively trade-off uncertainty of resource requirements with total energy consumption. Also, our model allows us to quantify the price of the robustness in terms of energy saving against resource requirement violations.

  • 1010.
    Zola, Enrica
    et al.
    Dept. of Network Engineering, UPC - BarcelonaTECH, Spain.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kim, Wooseong
    Dept. of Computer Engineering, Gachon University, S.Korea.
    Joint User Association and Energy Aware Routing for Green Small Cell mmWave Backhaul Networks2017In: 2017 IEEE Wireless Communication and Networking Conference (WCNC), Proceedings, San Francisco, USA: IEEE conference proceedings, 2017Conference paper (Refereed)
    Abstract [en]

    A dense deployment of small cells is one of the key characteristics envisioned for future 5G mobile networks in order to provide the required capacity increase. To cut cabling costs, small cells are foreseen to form multihop topologies using high capacity backhaul wireless links in the mmWave bands. Such small cells are deployed within the coverage area of a macro cell (eNB) to provide localized capacity where needed according to the well known Heterogeneous Network concept (HetNet). However, green networking will be very important because powering on unnecessarily a massive amount of small cells may lead to increased OPEX and CO2 emission. In this paper, we propose an optimization model that minimizes the total power consumption of 5G HetNets deployments while providing the required capacity and coverage. Our model jointly optimizes the user association, routing in the multihop backhaul and decides to power on or off the small cells to serve the user demands. Our numerical evaluation show significant power savings over a large range of traffic demand distributions while keeping the blocking probability low.

  • 1011. Zola, Erica
    et al.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Minimizing the Impact of Handover in WLAN: A Study on Performance Optimization2015In: Proceedings of SWE-CTW 2015, May 27th – 29th, Karlstad, Sweden, 2015Conference paper (Refereed)
  • 1012. Zuccato, Albin
    A Decision Matrix Approach to Prioritize Holistic Security Requirements in E-Commerce2005Conference paper (Refereed)
  • 1013. Zuccato, Albin
    A Holistic Information Security Management Frameworkapplied for electronic and mobile commerce2002Conference paper (Refereed)
  • 1014. Zuccato, Albin
    A modified mean value approach to assess securityrisks2002Conference paper (Refereed)
  • 1015. Zuccato, Albin
    Holistic Information Security Management Framework for electronic commerce2005Doctoral thesis, monograph (Other academic)
  • 1016. Zuccato, Albin
    Holistic security management framework applied in electronic commerce2007In: Computers & Security 26(3), p. 256-265Article in journal (Refereed)
  • 1017. Zuccato, Albin
    Holistic security requirement engineering for electronic commerce2004In: Holistic security requirement engineering for electronic commerceArticle in journal (Refereed)
  • 1018. Zuccato, Albin
    Introducing privacy risks in a companies information system security risk analysis2004Conference paper (Refereed)
  • 1019. Zuccato, Albin
    Legislation and economical aspects of ElectronicMoney with special viewpoint on Europe1999Conference paper (Refereed)
  • 1020. Zuccato, Albin
    Privacy Risk Management in a Business Environment2003In: / [ed] John Sören Pettersson, 2003Chapter in book (Other academic)
  • 1021. Zuccato, Albin
    Towards a systemic holistic security management2002Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Information System Security and its management "is a parasite on the profit" Gerald Kovacich.



    This thesis presents research intended to both modify the understanding for, and to introduce information system security not only as a cost factor but also as a business enabler for eCommerce systems. To achieve this, system theoretic concepts will be applied to information security management, taking technology, sociology and business aspects into consideration. The first aspects dealt with are security conception and system specification. A set of requirements for electronic money systems has been developed. However, security management does not only consist of requirement specifications, but must also open for an economically and socially acceptable implementation. Therefore we have developed a holistic framework for security management. This framework describes the activities and workflows that lead to satisfactory security levels in eCommerce. To be able to develop an understandable framework we apply black boxing in order to hide details. The development progress results in investigations of some of the black boxes mentioned. To motivate the need of inclusion in the framework, two of these inquires will be presented, where the first one deals with the improvement of a risk assessment methodology for faster application in e-commerce, and the second one with the influence of the Internet on privacy.

  • 1022. Zuccato, Albin
    et al.
    Fischer-Hübner, S.
    Symbolic and structuring effects of the Internet on privacy2005In: Perspectives and Policies on ICT in Society, J. Berleur, C. Avgerou (Eds.), Springer Science & Business Media, May 2005, 2005Chapter in book (Other academic)
    Abstract [en]

    Technology has influenced human lives since the beginning of mankind. Sociologists have described the effects that technology has on society as structuring or symbolic. We will use the same concepts to investigate the capability of the Internet to influence privacy. We analyse the structuring and symbolic effects of technology on privacy and thereby demonstrate some potentials of Internet technology and their effect on our life in society

  • 1023. Zuccato, Albin
    et al.
    Marquet, Bertrand
    Papillon, Serge
    Aldén, Magnus
    Service oriented modeling of communication infrastructure for assurance2006Conference paper (Refereed)
  • 1024.
    Älveborn, Andreas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Lönnerstrand, Marcus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Kontextbaserad information genom iBeacon: En implementation i iOS och Android2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the present day the need for relevant information at the right time and place is growing; so called context-based information. By using iBeacon based solutions this need can be largely satisfied. This dissertation explores uses for iBeacon as well as providing ideas for development. One concept which has been implemented is a mobile application for distribution of context based information in "mobility-expos". The concept has been developed for iOS and Android. The applications use a web service to facilitate distribution of information. The implementation is described in detail and important design choices are discussed and motivated.

  • 1025.
    Åhs, Gustaf
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Samuelsson, Viktor
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Certifieringswebb2017Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    This report presents the work performed to develop a web application, ranging from producing a requirements specification to the implementation and a demonstration of a prototype. The availability of a web application may come with various restrictions. The restriction in this case is that access is only given to employees at Sogeti Karlstad listed on the company's server. Access to the application by other offices in Sweden is not yet implemented.

    The goal of the development of this particular web application is to simplify the management of certificates currently using Excel spreadsheets and improve accessibility of the information for Sogeti employees.An important requirement was to create a sense of competition among employees in order to increase the number of certificates taken, which results in increased value for Sogeti as well as for those employees.

    In the last two chapters of the report, the project's technical and non-technical parts are evaluated both in their entirety and in some detail of different parts of the project. This information can be useful for future students about what to take into consideration before committing to a new project. All of the essential requirements in the requirement specification were fulfilled which led to a successful project.

  • 1026.
    Öborn, Malin
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Berg, David
    Karlstad University, Faculty of Economic Sciences, Communication and IT.
    Utbyggnad av Diamond: ett generellt dokumenthanteringssystem2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 1027.
    Österdahl, Fredrik
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Hendo, Ilias
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Themes in Totara: Creating and cloning2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this paper is to give the reader an insight into the graphical interface of a Learning Management system, the theme, how it functions and its importance. The main point is how the creation of new themes can be done, and two different approaches are examined and compared.The use of learning management systems have been growing rapidly over the past years. Modern learning, be it basic school, higher education or professional training, is almost always supported by some learning management system where both instructors and participators share learning material, assignments, discussion, among other things.The theme of a learning management system is of great importance and can have a substantial impact on the efficiency of the actual learning process. Themes might also differ in their purpose, thus depending on the target audience, creating a specific theme might be desirable.The work done in this paper examines the structure and function of themes in the web based Totara learning management system, and looks at two different approaches to creating new themes. These approaches involve creating something from scratch, and cloning an already existing theme.The conclusion drawn from the work done in this paper is that the most efficient way of creating a new theme, is through cloning an already existing theme. Only when time and experience is plentiful, and a full control over the theme structure is desirable, is creating a theme from scratch a viable option.

  • 1028.
    Österling Sicking, Sigrid
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Hegna Tengstål, Vidar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Tjänstebaserad Business Intelligence med Power BI i en webbapplikation2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Business Intelligence is about helping companies making business beneficial decisions by analysing and visualising data with the help of tools and applications. QBIM is a company in Karlstad that provides their customers with service based BI in various branches. They use a software called Power BI to compile the data from their customers and display the results in their portal SKI-ANALYTICS. The portal has as of now many flaws, and this report will focus on identify and improve those flaws. This goal will be split up and done in three parts; Q&A embedding, report embedding and mobile adaptation. The improvements will be implemented with the use of Power BI REST API and Power BI JavaScript API. The result is a more user friendly and attractive customer portal, where the three part goals are implemented. The report also includes a discussion on pros and cons of the use of an API that severely limits the freedom of the developer.

  • 1029.
    Östersjö, Rasmus
    Karlstad University.
    Sparse Merkle Trees: Definitions and Space-Time Trade-Offs with Applications for Balloon2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This dissertation proposes an efficient representation of a sparse Merkle tree (SMT): an authenticated data structure that supports logarithmic insertion, removal, and look-up in a verifiable manner. The proposal is general in the sense that it can be implemented using a variety of underlying non-authenticated data structures, and it allows trading time for space by the use of an abstract model which represents caching strategies. Both theoretical evaluations and performance results from a proof-of-concept implementation are provided, and the proposed SMT is applied to another authenticated data structure referred to as Balloon. The resulting Balloon has preserved efficiency in the expected case, and is improved with respect to worst case scenarios.

  • 1030.
    Özgü, Alay
    et al.
    Simula Metropolitan Center for Digital Engineering, Norge.
    Mancuso, Vincenzo
    IMDEA Networks Institute, Spanien.
    Brunström, Anna
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Alfredsson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Mellia, Marco
    Politecnico di Torino, Italien.
    Bernini, Giacomo
    Nextworks, Italien.
    Lonsethagen, Hakon
    Telenor Research, Norge.
    End to End 5G Measurements with MONROE: Challenges and Opportunities2018Conference paper (Refereed)
    Abstract [en]

    To be able to support diverse requirements of massive number of connected devices while also ensuring good user experience, 5G networks will leverage multi-access technolo- gies, deploy supporting operational mechanisms such as SDN and NFV, and require enhanced protocols and algorithms. For 4G networks, MONROE has been key to provide a common measurement platform and a set of methodologies available to the wider community. Such common grounds will become even more important and more challenging with 5G. In this paper, we elaborate on some key requirements for the design and implementation of 5G technologies and highlight the key challenges and needs for new solutions as seen in the context of 5G end-to-end measurements. We then discuss the opportunities that MONROE provides and more specifically, how a 5G-capable MONROE platform could facilitate these efforts.

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