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  • 151.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    LPED: Channel Diagnostics in WSN Through Channel Coding and Symbol Error Statistics2014In: IEEE ISSNIP 2014 - 2014 IEEE 9th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, Conference Proceedings, Singapore: IEEE Sensors Council, 2014, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Three major obstacles to wireless communication are electromagnetic interference, multipath fading and signal attenuation. The former stems mainly from collocated wireless systems operating in the same frequency band, while the latter two originate from physical properties of the environment. Identifying the source of packet corruption and loss is crucial, since the adequate countermeasures for different types of threats are essentially different. This problem is especially pronounced in industrial monitoring and control applications, where IEEE 802.15.4 communication is expected to deliver data within tight deadlines, with minimal packet loss. This work presents the Lightweight Packet Error Discriminator (LPED) that distinguishes between errors caused by multipath fading and attenuation, and those inflicted by IEEE 802.11 interference. LPED uses Forward Error Correction to determine the symbol error positions inside erroneously received packets and calculates the error density, which is then fed to a discriminator for error source classification. The statistical constituents of LPED are obtained from an extensive measurement campaign in two different types of industrial environments. The classifier incurs no overhead and in ≥90% of cases a single packet is sufficient for a correct channel diagnosis. Experiments show that LPED accelerates link diagnostics by at least 190%, compared to the relevant state-of-the-art approaches.

  • 152.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    PREED: Packet Recovery by Exploiting the Determinism in Industrial WSN Communication2015In: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2015, Fortaleza, Brazil: IEEE Computer Society, 2015, p. 81-90Conference paper (Refereed)
    Abstract [en]

    The requirements of safety-critical wireless sensornetwork (WSN) applications, such as closed-loop control andtraffic safety, cannot be met by the IEEE 802.15.4-2006 standardnor its industrial WSN (IWSN) derivatives. The main problem inthat respect is the communication reliability, which is seriouslycompromised by 2.4-GHz interference, as well as multipathfading and attenuation (MFA) at industrial facilities. Meanwhile,communication blackouts in critical WSN applications maylead to devastating consequences, including production halts,damage to production assets and can pose a threat to safetyof human personnel. This work presents PREED, a method toimprove the reliability by exploiting the determinism in IWSNcommunication. The proposed solution is based on the analysisof bit error traces collected in real transmissions at four differentindustrial environments. A case study on WirelessHART packetformat shows that PREED recovers 42%-134% more packetsthan the competing approaches on links compromised by WLANinterference. In addition, PREED reduces one of the most trivialcauses of packet loss in IWSN, i.e. the corruption offrame lengthbyte, by 88% and 99%, for links exposed to WLAN interferenceand MFA, respectively.

  • 153.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. ABB Corp Res, S-72178 Vasteras, Sweden.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Scrutinizing Bit- and Symbol-Errors of IEEE 802.15.4 Communication in Industrial Environments2014In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 63, no 7, p. 1783-1794Article in journal (Refereed)
    Abstract [en]

    The knowledge of error nature in wireless channels is an essential constituent of efficient communication protocol design. To this end, this paper is the first comprehensive bit- and symbol-level analysis of IEEE 802.15.4 transmission errors in industrial environments. The intention with this paper is to extract the error properties relevant for future improvements of wireless communication reliability and coexistence of radio systems in these harsh conditions. An extensive set of bit-error traces was collected in a variety of scenarios and industrial environments, showing that error behavior is highly dependent on the cause of packet corruption. It is shown that errors inflicted by multipath fading and attenuation exhibit different properties than those imposed by IEEE 802.11 interference. The statistical behavior of these two patterns is concurrently investigated in terms of differences in bit-error distribution, error burst length, channel memory length, and the scale of packet corruption. With these conclusions at hand, abiding to the computational constraints of embedded sensors and the statistical properties of bit-errors, a Reed-Solomon $(15,k)$ block code is chosen to investigate the implications of bit-error nature on practical aspects of channel coding and interleaving. This paper is concluded by a number of findings of high practical relevance, concerning the optimal type, depth, and meaningfulness of interleaving.

  • 154.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Ubiquitous, yet Deceptive: Hardware-Based Channel Metrics on Interfered WSN Links2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 5, p. 1766-1778Article in journal (Refereed)
    Abstract [en]

    The ease of acquiring hardware-based link quality indicators is an alluring property for fast channel estimation in time- and safety-critical Wireless Sensor Network (WSN) applications, such as closed-loop control and interlocking. The two rudimentary hardware-based channel quality metrics, Received Signal Strength (RSS) and Link Quality Indicator (LQI), are the key constituents of channel estimation and a plethora of other WSN functionalities, from routing to transmit power control. Nevertheless, this study highlights three deficient aspects of these two indicators: 1) overall deceptiveness, i.e. the inability to reveal the presence of interference, falsely indicating excellent channel conditions in an unacceptably high fraction of cases; 2) the burstiness of missed detections, which compromises the attempts to eliminate the deceptiveness by averaging; 3) high mutual discrepancy of the two indicators, observed in 39-73% of packets, throughout different scenarios. The ability of RSS and LQI to indicate IEEE 802.11 interference is scrutinized in a variety of scenarios in typical industrial environments, using commercialoff- the-shelf hardware and realistic network topologies, giving the findings of this study a high general validity and practical relevance.

  • 155.
    Barac, Filip
    et al.
    Ericsson AB.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sisinni, Emiliano
    University of Brescia.
    Error Manifestation in Industrial WSN Communication and Guidelines for Countermeasures2017In: Wireless Sensor Systems for Extreme Environments: Space, Underwater, Underground and Industrial / [ed] H. F. Rashvand and A. Abedi, John Wiley & Sons, 2017Chapter in book (Refereed)
  • 156.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media. ABB Corporate Research, Sweden.
    Åkerberg, Johan
    ABB Corporate Research, Sweden.
    A Lightweight Routing Protocol for Industrial Wireless Sensor and Actuator Networks2011In: Proceedings of IECON 2011 - 37th Annual Conference on IEEE Industrial Electronics Society, Melbourne, Australia: IEEE Industrial Electronics Society , 2011, p. 2980-2985Conference paper (Refereed)
    Abstract [en]

    The applications of Industrial Wireless Sensor and Actuator Networks (IWSAN) are time-critical and subject to strict requirements in terms of end-to-end delay and reliability of data delivery. A notable shortcoming of the existing wireless industrial communication standards is the existence of overcomplicated routing protocols, whose adequacy for the intended applications is questionable [1]. This paper evaluates the potentials of flooding as a data dissemination technique in IWSANs. The concept of flooding is recycled by introducing minimal modifications to its generic form and compared with a number of existing WSN protocols, in a variety of scenarios. The simulation results of all scenarios observed show that our lightweight approach is able to meet stringent performance requirements for networks of considerable sizes. Furthermore, it is shown that this solution significantly outperforms a number of conventional WSN routing protocols in all categories of interest.

  • 157.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Yu, Kan
    Mälardalen University College, Sweden.
    Gidlund, Mikael
    ABB AB, Corporate Research, Sweden.
    Åkerberg, Johan
    ABB AB, Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University College, Sweden.
    Towards Reliable and Lightweight Communication in Industrial Wireless Sensor Networks2012In: Procedings of the IEEE 10th International Conference on Industrial Informatics, INDIN 2012, IEEE conference proceedings, 2012, p. 1218-1224Conference paper (Refereed)
    Abstract [en]

    In this paper we address the issues of timeliness and transmission reliability of existing industrial communication standards. We combine a Forward Error Correction coding scheme on the Medium Access Control layer with a lightweight routing protocol to form an IEEE 802.15.4-conformable solution, which can be implemented into already existing hardware without violating the standard. After laying the theoretical foundations, we conduct a performance evaluation of the proposed solution. The results show a substantial gain in reliability and reduced latency, compared to the uncoded transmissions, as well as common Wireless Sensor Network routing protocols.

  • 158.
    Barg, Sobhi
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Mid Sweden University.
    Alam, Farhan Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Modeling of the Geometry Effect on the Core Loss and Verification with a Measurement Technique Based on the Seebeck Effect and FEA2019In: Power electronics converters / [ed] IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, the effect of the core geometry of non-toroidal magnetic cores on the magnetic loss is investigated. A frequency dependent core material-geometry loss factor is developed. This factor is function of the change in the non-toroidal core section and the Steinmetz parameter “β”. In addition, the temperature effect is included in the developed loss model for wide range of frequency and magnetic flux density. The model is applied for ER core and 3C92 ferrite material. The core loss measurements are performed using a Peltier cell. The principle of operation of the Peltier cell is based on the Seebeck effect, which convert the heat flow due to the temperature difference into electric power.  The calibration of the Peltier cell is validated with a resistive load and a relative error lower than 1% is achieved. The accuracy of the developed model is assessed with FEA and the experimental results. A maximum error of 10% is registered of the developed core loss model.

  • 159.
    Barg, Sobhi
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Multi‑objective Pareto and GAs nonlinear optimization approach for fyback transformer2019In: Electrical engineering (Berlin. Print), ISSN 0948-7921, E-ISSN 1432-0487, Vol. 101, no 3, p. 995-1006Article in journal (Refereed)
    Abstract [en]

    Design and optimization of high-frequency inductive components is a complex task because of the huge number of variables to manipulate, the strong interdependence and the interaction between variables, the nonlinear variation of some design variables as well as the problem nonlinearity. This paper proposes a multi-objective design methodology of a 200-W flyback transformer in continuous conduction mode using genetic algorithms and Pareto optimality concept. The objective is to minimize loss, volume and cost of the transformer. Design variables such as the duty cycle, the winding configuration and the core shape, which have great effects on the former objectives but were neglected in previous works, are considered in this paper. The optimization is performed in discrete research space at different switching frequencies. In total, 24 magnetic materials, 6 core shapes and 2 winding configurations are considered in the database. Accurate volume and cost models are also developed to deal with the optimization in the discrete research space. The bi-objective (loss–volume) and tri-objective (loss–volume–cost) optimization results are presented, and the variations of the design variables are analyzed for the case of 60 kHz. An example of a design (30 kHz) is experimentally verified. The registered efficiency is 88% at full load.

  • 160.
    Barile, Gianluca
    et al.
    University of l'Aquila, Via Gronchi, L'Aquila, Italy.
    Ferri, Giuseppe
    University of l'Aquila, Via Gronchi, L'Aquila, Italy.
    Parente, Francesca Romana
    University of l'Aquila, Via Gronchi, L'Aquila, Italy.
    Stornelli, Vincenzo
    University of l'Aquila, Via Gronchi, L'Aquila, Italy.
    Depari, Alessandro
    University of l'Aquila, Via Gronchi, L'Aquila, Italy.
    Flammini, Alessandra
    University of Brescia, Brescia, Italy.
    Sisinni, Emiliano
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. University of Brescia, Brescia, Italy.
    A standard CMOS bridge-based analog interface for differential capacitive sensors2017In: PRIME 2017 - 13th Conference on PhD Research in Microelectronics and Electronics, Proceedings, IEEE, 2017, p. 281-284, article id 7974162Conference paper (Refereed)
    Abstract [en]

    This work describes an analog electronic interface, based on a modified De Sauty AC bridge, performing a differential capacitive sensor estimation. A suitable feedback loop tunes a Voltage Controlled Resistor to balance the bridge. The electronic circuit has been designed in a standard integrated CMOS technology (AMS 0.35μm) with a low supply voltage (±1.5 V) and a reduced power consumption (lower than 4mW). PSpice simulation results show a very good agreement with theoretical expectations. The output voltage accuracy shows a 0.03V maximum absolute error for a range of ±50% of sensor variations from its baseline value. Very small baseline values are allowed (tens of μF). 

  • 161.
    Barile, Gianluca
    et al.
    University of L’Aquila, Italy.
    Ferri, Giuseppe
    University of L’Aquila, Italy.
    Parente, Francesca Romana
    University of L’Aquila, Italy.
    Stornelli, Vincenzo
    University of L’Aquila, Italy.
    Depari, Alessandro
    University of Brescia, Brescia, Italy.
    Flammini, Alessandra
    University of Brescia, Brescia, Italy.
    Sisinni, Emiliano
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. University of Brescia, Brescia, Italy.
    Linear Integrated Interface for Automatic Differential Capacitive Sensing2017In: Proceedings, Volume 1, Eurosensors 2017, 2017, Vol. 1, no 4Conference paper (Other academic)
    Abstract [en]

    In this work, the authors introduce a new full-analog front-end for differential capacitance sensors which provides a DC output voltage, directly proportional to the measurand variations. The readout circuit architecture is based on a De Sauty bridge as core of the capacitive sensing whereas the feedback circuitry performs the bridge autobalancing operation by means of changes in a multiplier output. The circuit is designed in a standard CMOS technology (AMS 0.35 µm) so is suitable for portable systems. Simulated results have shown a good agreement with the theoretical model being the percentage relative error less than 2.5%. Interface sensitivity is constant and values around 0.055 V/mm for the considered application.

  • 162.
    Barkland, Lars-Erik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and System science.
    Norder, Kim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and System science.
    En studie av Scrum för två personer och utveckling av mobilt gränssnitt2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A big portion of software development is the method which controls the flow ofthe creative process. Thru experience it has been shown how a lack oforganisation can have a profoundly negative effect on the development workand finally on the product itself. We take the Scrum method in a two-man formand analyze how the a small-scale version effects the roles, artefacts andactivities associated with the original Scrum method. The result of the workusing a small scale Scrum is presented along with the changes that have beendone during the work. The result and the final discussion show a positive effecton using a structured development method.Lately the use of small screen devices and their use of the Internet has widelyincreased . With this change in user interface comes new challenges designing aWeb handling a wide variety of user devices. In the process of developing aweb application techniques for small-screen interfaces was analyzed from thewhere Responsive Design was found to be the best choice concidering relevantlimitations. Design principals from the concept of Responsive Design isanalyzed and applied.

  • 163. Barkowsky, M
    et al.
    Brunnström, Kjell
    Acreo ICT Swedish AB.
    Ebrahimi, T
    Karam, L
    Lebreton, P
    Le Callet, P
    Perkis, A
    Raake, A
    Subedar, M
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Xing, L
    You, J
    Subjective and Objective Visual Quality Assessment in the Context of stereoscopic 3DTV2013In: 3DTV System with Depth-Image-Based Rendering / [ed] Yu, L., Tanimoto, M., and Zhu, C., Springer, 2013, p. 413-437Chapter in book (Refereed)
    Abstract [en]

    Subjective and objective visual quality assessment in the context of stereoscopic three-dimensional TV (3D-TV) is still in the nascent stage and needs to consider the effect of the added depth dimension. As a matter of fact, quality assessment of 3D-TV cannot be considered as a trivial extension of two-dimensional (2D) cases. Furthermore, it may also introduce negative effects not experienced in 2D, e.g., discomfort or nausea. Based on efforts initiated within the cost action ICT 1003 QUALINET, this chapter discusses current challenges in relation to subjective and objective visual quality assessment for stereo-based 3D-TV. Two case studies are presented to illustrate the current state of the art and some of the remaining challenges. © Springer Science+Business Media New York 2013. All rights are reserved.

  • 164.
    Barkowsky, M
    et al.
    University of Nantes, France.
    Masala, E
    Politecnico di Torino, Italy.
    Van Wallendael, G
    Ghent University - iMinds, Belgium.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB, Sweden .
    Staelens, N
    Ghent University - iMinds, Belgium.
    Le Callet, P
    University of Nantes, France.
    Objective Video Quality Assessment - Towards large scale video database enhanced model development.2015In: IEICE transactions on communications, ISSN 0916-8516, E-ISSN 1745-1345, Vol. E98-B, no 1, p. 2-11Article in journal (Refereed)
    Abstract [en]

    The current development of video quality assessment algorithms suffers from the lack of available video sequences for training, verification and validation to determine and enhance the algorithm's application scope. The Joint Effort Group of the Video Quality Experts Group (VQEG-JEG) is currently driving efforts towards the creation of large scale, reproducible, and easy to use databases. These databases will contain bitstreams of recent video encoders (H.264, H.265), packet loss impairment patterns and impaired bitstreams, pre-parsed bitstream information into files in XML syntax, and well-known objective video quality measurement outputs. The database is continuously updated and enlarged using reproducible processing chains. Currently, more than 70,000 sequences are available for statistical analysis of video quality measurement algorithms. New research questions are posed as the database is designed to verify and validate models on a very large scale, testing and validating various scopes of applications, while subjective assessment has to be limited to a comparably small subset of the database. Special focus is given on the principles guiding the database development, and some results are given to illustrate the practical usefulness of such a database with respect to the detailed new research questions.

  • 165. Barkowsky, M.
    et al.
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Cousseau, R.
    Brunnstrom, K.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Le Callet, P.
    Subjective quality assessment of error concealment strategies for 3DTV in the presence of asymmetric transmission errors2010In: Proceedings of 2010 IEEE 18th International Packet Video Workshop (PV, 2010, p. 193-200Conference paper (Refereed)
    Abstract [en]

    The transmission of 3DTV sequences over packet based networks may result in degradations of the video quality due to packet loss. In the conventional 2D case, several different strategies are known for extrapolating the missing information and thus concealing the error. In 3D however, the residual error after concealment of one view might leads to binocular rivalry with the correctly received second view. In this paper, three simple alternatives are presented: frame freezing, a reduced playback speed, and displaying only a single view for both eyes, thus effectively switching to 2D presentation. In a subjective experiment the performance in terms of quality of experience of the three methods is evaluated for different packet loss scenarios. Error-free encoded videos at different bit rates have been included as anchor conditions. The subjective experiment method contains special precautions for measuring the Quality of Experience (QoE) for 3D content and also contains an indicator for visual discomfort. The results indicate that switching to 2D is currently the best choice but difficulties with visual discomfort should be expected even for this method.

  • 166.
    Barkowsky, Marcus
    et al.
    LUNAM Université, Université de Nantes, IRCCyN UMR CNRS 6597, France .
    Li, Jing
    LUNAM Université, Université de Nantes, IRCCyN UMR CNRS 6597, France .
    Han, Taehwan
    Youn, Sungwook
    Ok, Jiheon
    Lee, Chulhee
    Hedberg, Christer
    Dept. of Netlab, Acreo Swedish ICT AB, Sweden .
    Ananth, Indirajith Vijai
    Dept. of Netlab, Acreo Swedish ICT AB, Sweden .
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and System science. Dept. of Netlab, Acreo Swedish ICT AB, Sweden .
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Dept. of Netlab, Acreo Swedish ICT AB, Sweden .
    Le Callet, Patrick
    LUNAM Université, Université de Nantes, IRCCyN UMR CNRS 6597, France .
    Towards standardized 3DTV QoE assessment: Cross-lab study on display technology and viewing environment parameters2013In: Proceedings of SPIE - The International Society for Optical Engineering, 2013, p. Art. no. 864809-Conference paper (Refereed)
    Abstract [en]

    Subjective assessment of Quality of Experience in stereoscopic 3D requires new guidelines for the environmental setup as existing standards such as ITU-R BT. 500 may no longer be appropriate. A first step is to perform cross-lab experiments in different viewing conditions on the same video sequences. Three international labs performed Absolute Category Rating studies on a freely available video database containing degradations that are mainly related to video quality degradations. Different conditions have been used in the labs: Passive polarized displays, active shutter displays, differences in viewing distance, the number of parallel viewers, and the voting device. Implicit variations were introduced due to the three different languages in Sweden, South Korea, and France. Although the obtained Mean Opinion Scores are comparable, slight differences occur in function of the video degradations and the viewing distance. An analysis on the statistical differences obtained between the MOS of the video sequences revealed that obtaining an equivalent number of differences may require more observers in some viewing conditions. It was also seen that the alignment of the meaning of the attributes used in Absolute Category Rating in different languages may be beneficial. Statistical analysis was performed showing influence of the viewing distance on votes and MOS results.

  • 167.
    Barkowsky, Marcus
    et al.
    Université de Nantes, France.
    Tourancheau, Sylvain
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Brunnström, Kjell
    NetLab: IPTV, Video and Display Quality, Acreo AB, 16440 Kista, Sweden.
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Andrén, Börje
    NetLab: IPTV, Video and Display Quality, Acreo AB, 16440 Kista, Sweden.
    Crosstalk Measurements of Shutter Glasses 3D Displays2011In: 49th Annual SID Symposium, Seminar, and Exhibition 2011, Display Week 2011, Wiley-Blackwell, 2011, p. 812-815Conference paper (Refereed)
    Abstract [en]

    Crosstalk is probably one of the main perceptual factors contributing to perceived image quality and visual comfort. The Video Quality Experts Group (VQEG) within their 3D video quality project is specifying a practical measurement procedure that will produce consistent results across laboratories. This paper is part of that effort. Two different method of measuring cross talk on shutter glasses stereo displays have been studied. One is based on time average luminance measurements and the other on temporal measurements. The results show that crosstalk is roughly 0.5% but that there are differences in the crosstalk between the two eyes in the shutter glasses.

  • 168.
    Bartosch, Nadine
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Correspondence-based pairwise depth estimation with parallel acceleration2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report covers the implementation and evaluation of a stereo vision corre- spondence-based depth estimation algorithm on a GPU. The results and feed- back are used for a Multi-view camera system in combination with Jetson TK1 devices for parallelized image processing and the aim of this system is to esti- mate the depth of the scenery in front of it. The performance of the algorithm plays the key role. Alongside the implementation, the objective of this study is to investigate the advantages of parallel acceleration inter alia the differences to the execution on a CPU which are significant for all the function, the imposed overheads particular for a GPU application like memory transfer from the CPU to the GPU and vice versa as well as the challenges for real-time and concurrent execution. The study has been conducted with the aid of CUDA on three NVIDIA GPUs with different characteristics and with the aid of knowledge gained through extensive literature study about different depth estimation algo- rithms but also stereo vision and correspondence as well as CUDA in general. Using the full set of components of the algorithm and expecting (near) real-time execution is utopic in this setup and implementation, the slowing factors are in- ter alia the semi-global matching. Investigating alternatives shows that results for disparity maps of a certain accuracy are also achieved by local methods like the Hamming Distance alone and by a filter that refines the results. Further- more, it is demonstrated that the kernel launch configuration and the usage of GPU memory types like shared memory is crucial for GPU implementations and has an impact on the performance of the algorithm. Just concurrency proves to be a more complicated task, especially in the desired way of realization. For the future work and refinement of the algorithm it is therefore recommended to invest more time into further optimization possibilities in regards of shared memory and into integrating the algorithm into the actual pipeline.

  • 169.
    Basir, Rabeea
    et al.
    School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Islamabad 44000, Pakistan.
    Qaisar, Saad
    School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Islamabad 44000, Pakistan.
    Ali, Mudassar
    School of Electrical Engineering and Computer Science, National University of Sciences and Technology, Islamabad 44000, Pakistan.
    Aldwairi, Monther
    College of Technological Innovation, Zayed University, Abu Dhabi 144534, UAE.
    Ashraf, Muhammad Ikram
    Centre for Wireless Communication, University of Oulu, 90014 Oulu, Finland.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Fog Computing Enabling Industrial Internet of Things: State-of-the-Art and Research Challenges2019In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 21, article id 4807Article in journal (Refereed)
    Abstract [en]

    Industry is going through a transformation phase, enabling automation and data exchange in manufacturing technologies and processes, and this transformation is called Industry 4.0. Industrial Internet-of-Things (IIoT) applications require real-time processing, near-by storage, ultra-low latency, reliability and high data rate, all of which can be satisfied by fog computing architecture. With smart devices expected to grow exponentially, the need for an optimized fog computing architecture and protocols is crucial. Therein, efficient, intelligent and decentralized solutions are required to ensure real-time connectivity, reliability and green communication. In this paper, we provide a comprehensive review of methods and techniques in fog computing. Our focus is on fog infrastructure and protocols in the context of IIoT applications. This article has two main research areas: In the first half, we discuss the history of industrial revolution, application areas of IIoT followed by key enabling technologies that act as building blocks for industrial transformation. In the second half, we focus on fog computing, providing solutions to critical challenges and as an enabler for IIoT application domains. Finally, open research challenges are discussed to enlighten fog computing aspects in different fields and technologies.

  • 170.
    Bassam, Diraoui
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lokal kompensering i Mellanspänningsnät2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vid byte av luftledningar mot jordkabel kommer kapacitiva felström-mar att genereras. De kapacitiva felströmmarna ökar med större kabel-area. Rapporten behandlar problematiken med för stora bidrag av kapacitiva jordfelströmmar och dess inverkan på hela elnätet.

    Arbetetsfrågeställningar kommer att behandla utlokaliserad kompen-sation, oselektiv reläskyddsfunktion och skillnaden mellan långa led-ningar och stora nät. Syftet med uppsatsen är att belysa behovet av att utlokalisera kompensationen, bestämma antal och täthet av spolar som minskar kapacitiva strömmar på Alnön, samt titta på skillnaderna mellan långa och många ledningar både på tätortens och också lands-bygdens nät.

    I teoridelen tas teorier om olika typer av jordfelsskydds funktioner upp, lokal kompensering och skillnader mellan korta och långa markkabelns nät.

    Projektet är utfört genom utforskning av de metoder som används för att begränsa dem genererade kapacitiva felströmmen vid användning av markkablar.

    I slutsatsen kommer jag fram till att för förbättring av ledningsskydds-funktion på landsbygden måste kapacitiva strömmar transporteras genom kabeln i kortare sträckor. Detta kommer att minska spänningsfal-let över kabelns resistans och reaktans, eller att fördela nätet till små fack.

  • 171.
    Baswade, Anand M.
    et al.
    Indian Institute of Technology, Hyderabad, India.
    Beltramelli, Luca
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. Mid Sweden University.
    Antony, Franklin A.
    Indian Institute of Technology, Hyderabad, India.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Reddy Tamma, Bheemarjuna
    Indian Institute of Technology, Hyderabad, India.
    Guntupalli, Lakshmikanth
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Modelling and Analysis of Wi-Fi and LAA Coexistence with Priority Classes2018In: 2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    The Licensed Assisted Access (LAA) is shown asa required technology to avoid overcrowding of the licensedbands by the increasing cellular traffic. Proposed by 3GPP,LAA uses a Listen Before Talk (LBT) and backoff mechanismsimilar to Wi-Fi. While many mathematical models have beenproposed to study the problem of the coexistence of LAAand Wi-Fi systems, few have tackled the problem of QoSprovisioning, and in particular analysed the behaviour of thevarious classes of priority available in Wi-Fi and LAA. Thispaper presents a new mathematical model to investigate theperformance of different priority classes in coexisting Wi-Fi andLAA networks. Using Discrete Time Markov Chains, we modelthe saturation throughput of all eight priority classes used byWi-Fi and LAA. The numerical results show that with the 3GPPproposed parameters, a fair coexistence between Wi-Fi and LAAcannot be achieved. Wi-Fi users in particular suffer a significantdegradation of their performance caused by the collision withLAA transmissions which has a longer duration compared toWi-Fi transmissions.

  • 172.
    Becker, J.
    et al.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Bianco, L.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Dinapoli, R.
    Paul-Scherrer-Institut(PSI), Villigen, Switzerland .
    Göttlicher, P.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Graafsma, Heinz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Greiffenberg, D.
    Paul-Scherrer-Institut(PSI), Villigen, Switzerland .
    Gronewald, M.
    University of Bonn, Bonn, Germany .
    Henrich, B. H.
    Paul-Scherrer-Institut(PSI), Villigen, Switzerland .
    Hirsemann, H.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Jack, S.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Klanner, R.
    University of Hamburg, Hamburg, Germany .
    Krüger, H.
    University of Bonn, Bonn, Germany .
    Klyuev, A.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Lange, S.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Marras, A.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Mozzanica, A.
    Paul-Scherrer-Institut(PSI), Villigen, Switzerland .
    Schmitt, B.
    Paul-Scherrer-Institut(PSI), Villigen, Switzerland .
    Schwandt, J.
    University of Hamburg, Hamburg, Germany .
    Sheviakov, I.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Shi, X.
    Paul-Scherrer-Institut(PSI), Villigen, Switzerland .
    Trunk, U.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Zimmer, M.
    DESY, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, Germany .
    Zhang, J.
    University of Hamburg, Hamburg, Germany .
    High speed cameras for X-rays: AGIPD and others2013In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 8, no 1, p. Art. no. C01042-Article in journal (Refereed)
    Abstract [en]

    Experiments at high pulse rate Free Electron Laser (FEL) facilities require new cameras capable of acquiring 2D images at high rates, handling large signal dynamic ranges and resolving images from individual pulses. The Adaptive Gain Integrated Pixel Detector (AGIPD) will operated with pulse rates and separations of 27000/s and 220 ns, respectively at European XFEL. Si-sensors, ASICs, PCBs, and FPGA logic are developed for a 1 Mega-pixel camera with 200 μm square pixels with per-pulse occupancies 104. Data from 3520 images/s will be transferred with 80 Gbits/s to a DAQ-system. The electronics have been adapted for use in other synchrotron light source detectors. 

  • 173.
    Becker, J.
    et al.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Bianco, L.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Göttlicher, P.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Graafsma, Heinz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Hirsemann, H.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Jack, S.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Klyuev, A.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Lange, S.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Marras, A.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Rah, S.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Sheviakov, I.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Trunk, U.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Zhang, J.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Zimmer, M.
    Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany .
    Klanner, R.
    University of Hamburg, Germany .
    Schwandt, J.
    University of Hamburg, Germany .
    Dinapoli, R.
    PSI, Villigen, Switzerland.
    Greiffenberg, D.
    PSI, Villigen, Switzerland.
    Mozzanica, A.
    PSI, Villigen, Switzerland.
    Schmitt, B.
    PSI, Villigen, Switzerland.
    Shi, X.
    PSI, Villigen, Switzerland.
    Krüger, H.
    University of Bonn, Germany .
    The high speed, high dynamic range camera AGIPD2013In: IEEE Nuclear Science Symposium Conference Record, IEEE conference proceedings, 2013, p. Art. no. 6829504-Conference paper (Refereed)
    Abstract [en]

    The European X-Ray Free Electron Laser (XFEL) will provide ultra short, highly coherent X-ray pulses which will revolutionize scientific experiments in a variety of disciplines spanning physics, chemistry, materials science, and biology. One of the differences between the European XFEL and other free electron laser sources is the high pulse frequency of 4.5 MHz. The European XFEL will provide pulse trains, consisting of up to 2700 pulses separated by 220 ns (600 μs in total) followed by an idle time of 99.4 ms, resulting in a supercycle of 10 Hz. Dedicated fast 2D detectors are being developed, one of which is the Adaptive Gain Integrating Pixel Detector (AGIPD). AGIPD is based on the hybrid pixel technology. The design goals of the recently produced, radiation hard Application Specific Integrated Circuit (ASIC) with dynamic gain switching amplifiers are (for each pixel) a dynamic range of more than 10 4 12.4 keV photons in the lowest gain, single photon sensitivity in the highest gain, an analog memory capable of storing 352 images, and operation at 4.5 MHz frame rate. A vetoing scheme allows to maximize the number of useful images that are acquired by providing the possibility to overwrite any previously recorded image during the pulse train. The AGIPD will feature a pixel size of (200 μm)2 and a silicon sensor with a thickness of 500 μm. The image data is read out and digitized between pulse trains. © 2013 IEEE.

  • 174.
    Becker, J.
    et al.
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany .
    Marras, A.
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany .
    Klyuev, A.
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany .
    Westermeier, F.
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany .
    Trunk, U.
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany .
    Graafsma, Heinz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany .
    Performance tests of an AGIPD 0.4 assembly at the beamline P10 of PETRA III2013In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 8, no 6, p. Art. no. P06007-Article in journal (Refereed)
    Abstract [en]

    The Adaptive Gain Integrating Pixel Detector (AGIPD) is a novel detector system, currently under development by a collaboration of DESY, the Paul Scherrer Institute in Switzerland, the University of Hamburg and the University of Bonn, and is primarily designed for use at the European XFEL. To verify key features of this detector, an AGIPD 0.4 test chip assembly was tested at the P10 beamline of the PETRA III synchrotron at DESY. The test chip successfully imaged both the direct synchrotron beam and single 7.05 keV photons at the same time, demonstrating the large dynamic range required for XFEL experiments. X-ray scattering measurements from a test sample agree with standard measurements and show the chip's capability of observing dynamics at the microsecond time scale.

  • 175.
    Becker, J.
    et al.
    Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany.
    Pennicard, D.
    Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany.
    Graafsma, Heinz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    The detector simulation toolkit HORUS2012In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 7, no 10, p. Art. no. C10009-Article in journal (Refereed)
    Abstract [en]

    In recent years, X-ray detectors used and developed at synchrotron sources and Free Electron Lasers (FELs) have become increasing powerful and versatile. However, as the capabilities of modern X-ray cameras grew so did their complexity and therefore their response functions are far from trivial. Since understanding the detecting system and its behavior is vital for any physical experiment, the need for dedicated powerful simulation tools arose. The HPAD Output Response fUnction Simulator (HORUS) was originally developed to analyze the performance implications of certain design choices for the Adaptive Gain Integrating Pixel Detector (AGIPD) and over the years grew to a more universal detector simulation toolkit covering the relevant physics in the energy range from below 1 keV to a few hundred keV. HORUS has already been used to study possible improvements of the AGIPD for X-ray Photon Correlation Spectroscopy (XPCS) at the European XFEL and its performance at low beam energies. It is currently being used to study the optimum detector layout for Coherent Diffration Imaging (CDI) at the European XFEL. Simulations of the charge summing mode of the Medipix3 chip have been essential for the improvements of the charge summing mode in the Medipix3 RX chip. HORUS is universal enough to support arbitrary hybrid pixel detector systems (within limitations). To date, the following detector systems are predefined within HORUS: The AGIPD, the Large Pixel Detector (LPD), the Cornell-Stanford Pixel Array Detector (CSPAD), the Mixed-Mode (MMPAD) and KEKPAD, and the Medipix2, Medipix3 and Medipix3 RX chips. © 2012 IOP Publishing Ltd and Sissa Medialab srl.

  • 176.
    Beganovic, Nejra
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Moulik, Bedatri
    Amity University.
    Ali M., Ahmed
    University of Duisburg-Essen.
    Söffker, Dirk
    University of Duisburg-Essen.
    Lifetime Model Development for Integration in Power Management of HEVs By Terms of Minimizing Fuel Consumption and Battery Degradation2019In: Proceedings of the Annual Conference of the PHM Society 2019, PHM Society , 2019, Vol. 11, p. 1-8, article id 784Conference paper (Refereed)
    Abstract [en]

    Along with increasingly frequent use of electric and hybrid electric vehicles, the constraints and demands placed on them become stricter. The most noticeable challenge considering Hybrid Electric Vehicles (HEVs) is to provide an optimal power flow between multiple electric sources alongside provided as less as possible aging of energy storage components. To provide efficient battery usage with respect to battery life, it becomes unavoidable to develop battery lifetime models, which not only reflect the State-of-Heath (SoH) but also allow battery lifetime prediction. The lifetime-oriented battery models have to be integrated into power management. To be used efficiently and to provide optimal power split ensuring mitigation of battery degradation without sacrificing desired power consumption, accurate modeling of battery degradation is of utmost importance. This implies that gradual battery degradation, which is directly affected by applied loading profiles, has to be monitored and used as additional control input. Moreover, the lifetime model developed in this case has to provide model outputs also in the timeframe of power management. In this contribution, a machine state-based lifetime model for electric battery source was developed. In this particular case, different degradation states as well as machine state transitions are identified in accordance with current operating conditions. Here, the change in charge / discharge rate (C-rate), overcharging / undercharging of the battery (depth-of-discharge), and the temperature are taken into consideration to define machine model states. The End-of-Lifetime (EoL) is defined as the deviation between nominal and current ampere-hour (Ah) throughput. The proposed machine state-based lifetime model is verified based on existing battery lifetime models using simulation setup. The developed lifetime model in this way serves as a prerequisite for its integration into power management with an aim to provide the trade-off between aforementioned conflicting objectives; fuel consumption and battery degradation.

  • 177.
    Bejugam, Santosh
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Tremor quantification and parameter extraction2011Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Tremor is a neuro degenerative disease causing involuntary musclemovements in human limbs. There are many types of tremor that arecaused due to the damage of nerve cells that surrounds thalamus of thefront brain chamber. It is hard to distinguish or classify the tremors asthere are many reasons behind the formation of specific category, soevery tremor type is named behind its frequency type. Propermedication for the cure by physician is possible only when the disease isidentified.Because of the argument given in the above paragraph, there is a needof a device or a technique to analyze the tremor and for extracting theparameters associated with the signal. These extracted parameters canbe used to classify the tremor for onward identification of the disease.There are various diagnostic and treatment monitoring equipment areavailable for many neuromuscular diseases. This thesis is concernedwith the tremor analysis for the purpose of recognizing certain otherneurological disorders. A recording and analysis system for human’stremor is developed.The analysis was performed based on frequency and amplitudeparameters of the tremor. The Fast Fourier Transform (FFT) and higherorderspectra were used to extract frequency parameters (e.g., peakamplitude, fundamental frequency of tremor, etc). In order to diagnosesubjects’ condition, classification was implemented by statisticalsignificant tests (t‐test).

  • 178. Bellotti, E
    et al.
    Farahmand, M
    Goano, M
    Ghilliano, E
    Garetto, C
    Ghione, G
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Brennan, K.F.
    Ruden, P.P.
    Simulation of carrier transport in wide band gap semiconductors2001In: International Journal of High Speed Electronics and Systems, ISSN 0129-1564, Vol. 11, no 2, p. 525-584Article in journal (Refereed)
  • 179. Bellotti, E
    et al.
    Farahmand, M
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Brennan, KF
    Ruden, PP
    Shul, Randy J
    Monte Carlo based calculation of transport parameters for wide band gap device simulation2001In: Materials Research Society symposia proceedings, Warrendale: Materials Research Society , 2001, , p. T6241-T6246p. T6241-T6246Conference paper (Refereed)
    Abstract [en]

    We present Monte Carlo based calculations of transport parameters useful in the simulation of III-nitride and SiC based devices. The calculations are performed using a full band ensemble Monte Carlo model that includes numerical formulations of the phonon scattering rates and impact ionization transition rates. Calculations are made for the wurtzite and zincblende phases of GaN, the wurtzite phase of InN, and the 3C (cubic) and 4H phases of SiC. The basic transport parameters determined are saturation drift velocity, and the ionization coefficients as a function of applied electric field. Results from the various materials are finally compared.

  • 180. Bellotti, E.
    et al.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Brennan, K.F.
    Ruden, P.P.
    Ensemble Monte Carlo calculation of hole transport in bulk 3C-SiC1999In: Journal of Applied Physics, ISSN 0021-8979, Vol. 85, no 6, p. 3211-3217Article in journal (Refereed)
  • 181. Bellotti, E.
    et al.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Brennan, K.F.
    Ruden, P.P.
    Trew, R.
    Monte Carlo calculation of hole initiated impact ionization in 4H phase SiC2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, no 8, p. 3864-3871Article in journal (Refereed)
    Abstract [en]

    In this article, we present a comprehensive, full band theoretical study of the high field, hole transport properties of the 4H phase of silicon carbide (4H-SiC). The calculations are performed using a full band ensemble Monte Carlo simulation that includes numerically tabulated impact ionization rates, and phonon and ionized impurity scattering rates. In addition, the simulation includes a mechanism, interband tunneling, by which the holes can move between bands in the proximity of band intersection points, It is found that there exists a significant anisotropy in the calculated steady-state hole drift velocity for fields applied parallel and perpendicular to the c-axis direction. Good agreement with experimental measurements of the hole initiated impact ionization coefficient for fields applied along the c axis is obtained, provided that interband tunneling in the proximity of band intersections is included in the model. If interband tunneling is not included, the calculated ionization coefficients are orders of magnitude lower than the experimental measurements. © 2000 American Institute of Physics.

  • 182.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Guntupalli, Lakshmikanth
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Modeling of Enhanced Distributed Channel Access with Station Grouping: A Throughput Analysis2018In: Proc. IEEE 88th Vehicular Technology Conference (VTC'18-fall), Chicago, USA, Aug. 2018., IEEE conference proceedings, 2018, article id 8690814Conference paper (Refereed)
    Abstract [en]

    Machine to Machine (M2M) communication networksare expected to connect a large number of power constrained devices in long range applications with differentquality of service (QoS) requirements. Medium access control with QoS support such as the Enhanced Distributed Channel Access (EDCA) defined by IEEE 802.11e provides traffic differentiation and corresponding priority classes, which guarantees QoSaccording to the needs of applications. In this paper, we employa station grouping mechanism for enhancing the scalability of EDCA to handle the massive number of access attempts expected in large M2M networks. Furthermore, we develop a discrete time Markov chain (DTMC) model to analyze the performance of EDCA with station grouping. Using the developed DTMC model, we calculate throughput for each access category as well as for different combinations of grouping and EDCA parameters. Thenumerical results show that the model can precisely reveal the behavior of EDCA mechanism. Moreover, it is demonstrated that employing the proposed grouping mechanism for EDCA increasesthe normalized throughput significantly for all classes of priority.

  • 183.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Interference Modelling in a Multi-Cell LoRa System2018In: 2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    As the market for low-power wide-area network (LPWAN) technologies expands and the number of connected devices increases, it is becoming important to investigate the performance of LPWAN candidate technologies in dense deployment scenarios. In dense deployments, where the networks usually exhibit the traits of an interference-limited system, a detailed intra- and inter-cell interference analysis of LPWANs is required. In this paper, we model and analyze the performance of uplink communication of a LoRa link in a multi-cell LoRa system. To such end, we use mathematical tools from stochastic geometry and geometric probability to model the spatial distribution of LoRa devices. The model captures the effects of the density of LoRa cells and the allocation of quasi-orthogonal spreading factors (SF) on the success probability of the LoRa transmissions. To account for practical deployment of LoRa gateways, we model the spatial distribution of the gateways with a Poisson point process (PPP) and Matèrn hard-core point process (MHC). Using our analytical formulation, we find the uplink performance in terms of success probability and potential throughput for each of the available SF in LoRa’s physical layer. Our results show that in dense multi-cell LoRa deployment with uplink traffic, the intercell interference noticeably degrades the system performance.

  • 184.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Modelling of EnergyConsumption in IEEE 802.11.ah Networks for M2M Traffic2016In: Proceedings of SNCNW 2016: The 12th Swedish National Computer Networking Workshop, 2016, p. 38-41Conference paper (Refereed)
    Abstract [en]

    IEEE 802.11ah is a sub-1 GHz standard designed to meet the requirements of future machine-to-machine (M2M) communications. The standard should be able to support use cases for the M2M communications with thousands of stations capable of generating both periodic and aperiodic traffic for a single access point. In some cases, like environmental and agricultural monitoring. the nodes are typically powered by battery or through energy harvesting. For this application it is important for the communication to be energy efficient. IEEE 802.11ah introduces new energy saving mechanisms and a novel channel access mechanism to achieve this objective even for networks with a large nodes number. This work proposes a mathematical model to compute the energy consumption of an IEEE 802.11ah network.

  • 185.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Hybrid MAC Mechanism for Energy Efficient Communication in IEEE 802.11ah2017In: Proceedings of the 2017 IEEE International Conference on Industrial Technology (ICIT), IEEE, 2017, p. 1295-1300, article id 7915550Conference paper (Refereed)
    Abstract [en]

    Many applications for machine-to-machine (M2M) communications are characterized by large numbers of devices with sporadic transmissions and subjected to low energy budgets. This work addresses the importance of energy consumption by proposing a new Medium Access Control (MAC) mechanism for improving the energy efficiency of IEEE 802.11ah, a standard targeting M2M communication. We propose to use the features of IEEE 802.11ah MAC to realize a hybrid contention-reservation mechanism for the transmission of uplink traffic. In the proposed mechanism, any device with a buffered packet will first notify the Access Point (AP) during a contention phase before being given a reserved timeslot for the data transmission. We develop a mathematical model to analyse the energy consumption ofthe proposed mechanism and of IEEE 802.11ah. The results show that for a monitoring scenario, the proposed contention reservation mechanism reduces the energy consumption for a successful uplink data transmission by up to 55%.

  • 186.
    Berg, Miguel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Capacity, robustness, and complexity of radio resource management in bunched personal communication systems1999Licentiate thesis, monograph (Other academic)
  • 187.
    Berg, Miguel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Concept for hybrid random/dynamic radio resource management1998In: Proceedings of the 1998 9th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC '98. Part 3; Boston, MA, USA; 8 Sept. - 11 Sept. 1998. Vol. 1, IEEE , 1998, p. 424-428Conference paper (Refereed)
    Abstract [en]

    Third generation mobile communication systems will allow many different services with varying demands on data rate and delay. For those systems, the fixed radio resource management (RRM) techniques used in today's low rate systems will not be appropriate to ensure efficient utilization of the radio spectrum. Dynamic RRM is necessary in order to cope with the large variations in data rate. We study the bunch concept which is a hybrid between random and dynamic RRM. Within a small synchronized cluster (bunch) we use dynamic radio resource allocation combined with SIR-based power control and between the bunches we use time/frequency hopping to average the interference. We propose an improved RRM algorithm and evaluate the performance of the bunch concept for a Manhattan scenario with mixed traffic. The performance is improved while the computational complexity is reduced compared to our previously published results for the bunch concept. We also show that the performance of a single bunch system is close to the theoretical upper bound.

  • 188.
    Berg, Miguel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Maintaining high Capacity for Centralized DCA with Limited Measurements and Signaling1999In: Proceedings of the 1999 10th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC '99, Osaka, Japan, Sept 12 - 15, 1999, IEEE , 1999Conference paper (Refereed)
    Abstract [en]

    Centralized dynamic channel allocation strategies can, in theory, achieve very high capacity in terms of achievable load at a certain quality level. Unfortunately, these strategies have often been considered non-feasible in practice due to the massive amount of measurements and signaling typically required. In this paper we evaluate some methods to maintain high performance while drastically reducing the measurement and signaling requirements. Our DCA algorithm is based on measurements of the link gain matrix. We show that for a microcellular Manhattan environment, only the gains from the three strongest beacons have to be measured and signaled by each mobile in order to achieve almost the same capacity as an ideal system where all beacons can be measured

  • 189.
    Berg, Miguel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Performance of Mobile Station Location Methods in a Manhattan Microcellular Environment2001In: 3GW 2001, San Fransisco, June 2001, 2001Conference paper (Refereed)
    Abstract [en]

    Positioning of users in cellular systems is an area attracting large interest and the number of applications for the location information is growing rapidly. Large-scale deployment of such applications will require methods for positioning that are simple enough to be used in mobile phones. In this paper, we evaluate the location accuracy for some different algorithms in a microcellular environment. We propose some simple but quite accurate methods and compare them with commonly known methods. Our results show that in the studied environment, all our proposed algorithms can at least manage the US E911 phase II requirements of positioning emergency calls within 125 m, 67 percent of the time.

  • 190.
    Berg, Miguel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Radio Resource Management in Bunched Personal Communication Systems2002Doctoral thesis, monograph (Other academic)
  • 191.
    Berg, Miguel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    The Bunch Concept1997In: Workshop, KTH, 29 August 1997, 1997Conference paper (Other academic)
  • 192.
    Berg, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Nätanalys: Identifiering av felställe i kabelnät2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The report is a study of error management and localization in underground cable network with very little overhead line. Error management is treated with the theoretical troubleshooting model and theoretical model with practical feedback. The work relates to the fact that troubleshooting has been complicated when the supply safety in the electricity grid increases. Difficult troubleshooting is followed by a difficult reset work in case of malfunctioning in the network and it leads to longer interruptions.The grid is built with main feed and radial feeds. In the cable stretches, an interval of the short-circuit current occurs with a minimum and a maximum current below the distance. Depending on how the network is built, multiples of same error current is created, that create harder error-handling. The analysis examines which locations in the grid, which help increase the number of alternative malfunctions and if there is any alternative method to solve the problem. The report deals with the connection between currents in main feed and in radial feeds along the line. There appears to be a connection between the emergences of currents with similar current values in several places. A network consisting of a main feed and a plurality of radial feeds, the occurrence of streams in several places is a disadvantage in the troubleshooting task and the work is adversely affected and the troubleshooting work becomes more difficult.

  • 193.
    Bergman, Jens
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Wallin, Fredrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    3D-portal: Kommunikation i 3D2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In todays society internet is used for communication between each other aroundthe world. The first video call was made around the year 1940 and it is time fora development, where 3D is something that can make video calls more real. Tomake this possible a system was constructed that would be able to get data fromdifferent time-of-flight cameras and color cameras and audio devices. That datashould later on be compressed and transmitted over internet to be able to play iton someone else’s 3D-display. To prevent the feeling of delay in the call, allparts together must happen in real time. The development methods that havebeen used is pair programming and a variation of test-driven development. Thesystem has been evaluated by time messurements, image quality and data sizeto find a good balance between time and quality. The system was constructedby five parts: capturing of images and audio, image upscaling, compression anddecompression, network streaming and also rendering. The result showed thatthe parts affected by data size and image quality could achieve a good balancebetween time and quality. However, all goals could not be achieved becausesome parts where too slow for the real time goal to be achieved and also someparts could not be constructed in time. Since the system was built up modularlythe parts that did not achieve the goals can be improved or replaced. Based onthe results, solution proposals was made to improve the results for a possiblefurther development.

  • 194.
    Bergström, David
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Kaplan, Alexander
    Powell, J
    Laser absorption measurements in opaque solids2005In: 10th NOLAMP Conference : the 10th Nordic Laser Materials Processing Conference, 17-19 August 2005, Luleå Sweden, Luleå: Luleå University of Technology , 2005, p. 444-Conference paper (Refereed)
    Abstract [en]

    In LaserMaterial Processing, an understanding of the fundamental absorption mechanisms plays a vital role in determining the optimum processing parameters and conditions. The absorptance, which characterizes how much a material absorbs, can alter during a processing application, as a result of melting, boiling, structural changes of the surface, oxidation, plasma formation, etc. To gain knowledge of these complex processes, a combination of experimental as well as of theoretical work is required. In this paper, an overview of the most common experimental methods and techniques to measure laser absorption in opaque solids, such as metals, will be presented.

  • 195.
    Bertilson, Kent
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hjelm, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Petersson, Sture
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Monte Carlo Simulation of 4H and 6H-SiC short channel MOSFETs2001In: High Temperature Electronics Network. HITEN ; 4 (Oslo) : 2001.06.05-08: Proceedings of the International Conference on High Temperature Electronics : held in Oslo, Norway, 5th - 8th June 2001, Oxford: Oxford Applied Technology Ltd, , 2001, p. 199-Conference paper (Refereed)
  • 196.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nästa generations kompakta spänningsomvandlare2012In: Thule, Kungl. Skytteanska Samfundets Årsbok 2012, ISSN 0280-8692, Vol. 1, no 1, p. 153-157Article in journal (Other (popular science, discussion, etc.))
  • 197.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Simulation and Optimization of SiC Field Effect Transistors2004Doctoral thesis, monograph (Other scientific)
  • 198.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Transformer2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A printed circuit board transformer comprises at least one primary winding and one secondary winding, each in the form of at least one layer of turns inside or at the surface of a printed circuit board. The transformer is designed for a step-up/down-operation. Each of the two layers (10, 11) has an elongated winding element (12, 13, 13′) substantially following an elongated winding element of the other layer while being in an overlapping relationship therewith as seen perpendicularly to said printed circuit board over substantially the entire extension of said winding elements. A second (11) of the layers belonging to the secondary winding has a fewer number of turns than the first (10) of said layers belonging to said primary winding.

  • 199.
    Bertilsson, Kent
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Dubaric, Ervin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hjelm, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Petersson, Sture
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Monte Carlo simulation of vertical MESFETs in 2H, 4H and 6H-SiC2001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 3-7, p. 1283-1286Article in journal (Refereed)
    Abstract [en]

    The 4H-SiC static induction transistor (SIT) is a very competitive device for high frequency and high power applications (3-6 GHz range). The large breakdown voltage and the high thermal conductivity of 4H-SiC allow transistors with extremely high current density at high voltages. The SIT transistor shows better output power capabilities but the unity current-gain frequency is lower compared to a MESFET device. In this work we show, using a very accurate numerical model, that a compromise between the features given by the SIT structure and the ordinary MESFET structure can be obtained using the vertical MESFET structure. The device dimension has been selected very aggressively to demonstrate the performance of an optimized technology. We also present results from drift-diffusion simulations of devices, using transport parameters obtained from the Monte Carlo simulation. The simulations indicate that 2H-SiC is superior to both 4H and 6H-SiC for vertical devices. For lateral devices, 2H-SiC is slightly faster compared to an identical 4H-SiC device

  • 200.
    Bertilsson, Kent
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Dubaric, Ervin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Petersson, Sture
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Simulation of a low atmospheric-noise modified four-quadrant position sensitive detector2001In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 466, no 1, p. 183-187Article in journal (Refereed)
    Abstract [en]

    A modified four-quadrant position sensitive detector (PSD) is developed. This structure is less sensitive to atmospheric turbulence that is a major drawback with the traditional four-quadrant detector. The inter-electrode resistance is as high as for the four-quadrant detector, which is an advantage compared to the lateral effect PSD. The linearity for the modified four-quadrant detector is good in the whole active range of sensing. The structures are limited to small sensing areas with well focused beams and are suitable for use in detectors up to 1 mm in size.

1234567 151 - 200 of 1580
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