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  • 151.
    Blaschke, D.
    et al.
    University of Wroclaw.
    Klähn, T.
    University of Wroclaw.
    Łastowiecki, R.
    University of Wroclaw.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    How strange are compact star interiors?2010In: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 37, no 9Article in journal (Refereed)
    Abstract [en]

    We discuss a Nambu-Jona-Lasinio (NJL)-type quantum field theoretical approach to the quark matter equation of state with color superconductivity and construct hybrid star models on this basis. It has recently been demonstrated that with increasing baryon density, the different quark flavors may occur sequentially, starting with down-quarks only, before the second light quark flavor and at highest densities the strange quark flavor also appears. We find that color superconducting phases are favorable over non-superconducting ones, which entails consequences for thermodynamic and transport properties of hybrid star matter. In particular, for NJL-type models no strange quark matter phases can occur in compact star interiors due to mechanical instability against gravitational collapse, unless a sufficiently strong flavor mixing as provided by the Kobayashi-Maskawa-'t Hooft determinant interaction is present in the model. We discuss observational data on mass-radius relationships of compact stars which can put constraints on the properties of the dense matter equation of state.

  • 152.
    Blaschke, David
    et al.
    University of Wroclaw.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Klähn, Thomas
    University of Wroclaw.
    Berdermann, Jens
    Deutsches Elektronen-Synchrotron.
    Sequential deconfinement of quark flavors in neutron stars2009In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 80, no 6, p. 65807-Article in journal (Refereed)
    Abstract [en]

    A scenario is suggested in which the three light quark flavors are sequentially deconfined under increasing pressure in cold asymmetric nuclear matter as found, for example, in neutron stars. The basis for this analysis is a chiral quark matter model of Nambu–Jona-Lasinio (NJL) type with diquark pairing in the spin-1 single-flavor, spin-0 two-flavor, and three-flavor channels. Nucleon dissociation sets in at about the saturation density, n0, when the down-quark Fermi sea is populated (d-quark drip line) because of the flavor asymmetry induced by β equilibrium and charge neutrality. At about 3n0, u-quarks appear and a two-flavor color superconducting (2SC) phase is formed. The s-quark Fermi sea is populated only at still higher baryon density, when the quark chemical potential is of the order of the dynamically generated strange quark mass. Two different hybrid equations of state (EOSs) are constructed using the Dirac-Brueckner Hartree-Fock (DBHF) approach and the EOS of Shen et al. [H. Shen, H. Toki, K. Oyamatsu, and K. Sumiyoshi, Nucl. Phys. A637, 435 (1998)] in the nuclear matter sector. The corresponding hybrid star sequences have maximum masses of 2.1 and 2.0 M respectively. Two- and three-flavor quark-matter phases exist only in gravitationally unstable hybrid star solutions in the DBHF case, whereas the Shen-based EOSs produce stable configurations with a 2SC phase component in the core of massive stars. Nucleon dissociation via d-quark drip could act as a deep crustal heating process, which apparently is required to explain superbursts and cooling of x-ray transients.

  • 153.
    Blaschke, David
    et al.
    University of Wroclaw.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Skokov, Vladimir
    Joint Institute for Nuclear Physics.
    Accessibility of dense QCD phases in heavy-ion collisions2010In: "White book" of the future nuclotron-based ion collider facility (NICA) in Dubna, Russia, 2010Chapter in book (Other academic)
  • 154. Blaschke, David
    et al.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Skokov, Vladimir
    Typel, Stefan
    Accessibility of color superconducting quark matter phases in heavy-ion collisions2010In: Acta Physica Polonica B Proceedings Supplement, ISSN 1899-2358, Vol. 3, no 3, p. 741-745Article in journal (Refereed)
    Abstract [en]

    We discuss a hybrid equation of state (EoS) that fulfills constraints for mass-radius relationships and cooling of compact stars. The quark matter EoS is obtained from a Polyakov-loop Nambu-Jona-Lasinio (PNJL) model with color superconductivity, and the hadronic one from a relativistic mean-field (RMF) model with density-dependent couplings (DD-RMF). For the construction of the phase transition regions we employ here for simplicity a Maxwell construction. We present the phase diagram for symmetric matter which exhibits two remarkable features: (1) a "nose"-like structure of the hadronic-to-quark matter phase border with an increase of the critical density at temperatures below T \sim 150 MeV and (2) a high critical temperature for the border of the two-flavor color superconducting (2SC) phase, Tc >160 MeV. We show the trajectories of heavy-ion collisions in the plane of excitation energy versus baryon density calculated using the UrQMD code and conjecture that for incident energies of 4 . . . 8 A GeV as provided,  e.g., by the Nuclotron-M at JINR Dubna or by lowest energies at the future heavy-ion collision experiments CBM at FAIR and NICA at JINR, the color superconducting quark matter phase becomes accessible.

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  • 155.
    Blech, Jan Olaf
    et al.
    RMIT University, Melbourne.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David
    ISEP, Instituto Superior de Engenharia do Porto.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zoitl, Alois
    fortiss GmbH, Munich.
    A Comparison of Formal Verification Approaches for IEC 614992016In: 2016 IEEE 21st International Conference on Emerging Technologies and Factory Automation (ETFA): Berlin, 6-9 Sept. 2016, Piscataway, NJ: IEEE conference proceedings, 2016, article id 7733636Conference paper (Refereed)
    Abstract [en]

    Engineering and computer science have come up with a variety of techniques to increase the confidence in systems, increase reliability, facilitate certification, improve reuse and maintainability, improve interoperability and portability. Among them are various techniques based on formal models to enhance testing, validation and verification. In this paper, we are concentrating on formal verification both at runtime and design time of a system. Formal verification of a system property at design time is the process of mathematically proving that the property indeed holds. At runtime, one can check the validity of the property and report deviations by monitoring the system execution. Formal verification relies on semantic models, descriptions of the system and its properties. We report on ongoing verification work and present two different approaches for formal verification of IEC 61499-based programs. We provide two examples of ongoing work to exemplify the design and the runtime verification approaches

  • 156.
    Blomquist, Mats
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Non-contact measurement systems in robotics and telerobotics1999Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In robotics, and particularly in telerobotics, non-contact measurement methods are widely used. In this thesis, systems are investigated with the range camera as the main sensor component. It is desirable that remotely controlled robot systems have a high degree of autonomy. Two systems are described where a range camera is used to increase the autonomy of the system. The first is a system where a laser pointer tracks an edge of an object or a cable. In the second system a range camera is used to control the movement of a robot arm perpendicularly towards an object, in the intention of aligning a sensor probe to the surface of the object. A problem with range camera measurements is the occurrence of occlusion, i.e. the phenomenon when objects in the foreground hide the measured object. One example of such a system is when the range camera is used to measure irregular objects, as for example objects on a conveyor belt. In the thesis, we investigate a system where we use the range camera to estimate the size distribution of iron ore pellets on a conveyor belt while systematic errors in the measurements arise due to occlusion.

  • 157.
    Blomquist, Mats
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Burman, Per
    Index Braille, Gammelstad.
    The WinBraille Approach to Producing Braille Quickly and Effectively2002In: Computer Helping People with Special Needs: 8th International Conference, ICCHP 2002, Linz, Austria, July 15-20, 2002. Proceedings, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2002, p. 618-619Chapter in book (Other academic)
    Abstract [en]

    With WinBraille it is possible to emboss directly from a word processor like Microsoft Word on any of Index Braille's embossers, and on-the-fly contract the document into grade 2 Braille. The benefit of WinBraille is that it has a simple interface for the novice, but is still powerful for the advanced user. WinBraille contains Windows drivers for Index Braille's embossers, the WinBraille application, contraction rules for more than 20 languages, a contraction rule editor, predefined profiles and templates for immediate access, and macros to directly emboss from Microsoft Word. The combination of Word macros, drivers, predefined contraction rules, profiles and templates makes the system suitable for the user with no or limited knowledge of Braille and Braille printing. We describe how the WinBraille's approach can facilitate the daily work for people who normally do not print Braille, but occasionally have to produce materials to be read by blind or visually impaired people. We also explore some of WinBraile's less advanced features, like Braille formatting and how to select different profiles and templates.

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  • 158.
    Blomquist, Mats
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Burman, Per
    Index Braille, Gammelstad.
    Blenkhorn, Paul
    Department of Computation, UMIST, Manchester.
    Emboss contracted Braille directly from your word-processor using WinBraille2002In: 2002 Conference Proceedings - Technology and Persons with Disabilities Conference, California State University, Northridge , 2002Conference paper (Refereed)
    Abstract [en]

    With WinBraille, a free program from Index Braille, Sweden, it is possible to emboss directly from a word-processor like Microsoft Word on any of Index Braille's embossers, and on-the-fly contract the document into grade 2 Braille. WinBraille contains: Windows drivers for Index Braille embossers; emboss-direct macros for well known Windows programs like Microsoft Word; a built-in editor for viewing and editing the text in prior to embossing; and a translation engine for Braille contraction translations.

  • 159.
    Blomquist, Mats
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Ericsson, Hans-Ola
    Luleå University of Technology, Department of Arts, Communication and Education, Music and dance.
    Next generation stop combination systems2002Conference paper (Refereed)
    Abstract [en]

    A new system concept is described for storing and retrieving stop combinations in mechanically controlled pipe organs. The system combines many features found in currently used systems, but have, so far, not been combined in one single system. Characterized features are: Both "generals" and "divisionals", as found in many anglican organs, as well as a list of consecutive com-bination steps, common in continental systems; Micro-tonal registrations with precision better than 2% of the stop piston range, if the mechanical system can compete; Time-dependent activation of specified combinations; Individual PIN-code and password for a personal set of combination lists; An aesthetically appealing design which fits both in new and in historical organs. We also describe a novel method to easily insert practically an unlimited number of extra combination steps between two already defined steps.

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  • 160.
    Blomquist, Mats
    et al.
    Luleå University of Technology.
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Range camera on conveyor belts: estimating size distribution and systematic errors due to occlusion1999In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 118, p. 118-126Article in journal (Refereed)
    Abstract [en]

    When range cameras are used for analyzing irregular material on a conveyor belt there will be complications such as missing segments caused by occlusion. Also, a number of range discontinuities will be present. In the framework towards stochastic geometry, conditions are found for the cases when range discontinuities take place. The test objects are pellets for the steel industry. An illuminating laser plane will give range discontinuities at the edges of each individual object. These discontinuities are used to detect and measure the chord created by the intersection of the laser plane and the object. From the measured chords we derive the average diameter and its variance. An improved method is to use a pair of parallel illuminating light planes to extract two chords. The estimation error for this method is not larger than the natural shape fluctuations (the difference in diameter) for the pellets. The laser-camera optronics is sensitive enough both for material on a conveyor belt and free falling material leaving the conveyor.

  • 161.
    Blomquist, Mats
    et al.
    Luleå University of Technology.
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Tracking range discontinuities in dynamic scenes: a smart range camera1994In: Intelligent robots and computer vision XIII: algorithms and computer vision: 31 October - 2 November 1994, Boston, Massachusetts, SPIE - International Society for Optical Engineering, 1994, p. 249-260Conference paper (Refereed)
    Abstract [en]

    The problem studied in this paper is algorithms for fast and reliable extraction of range discontinuities in dynamic scenes. The application is to control the motion of a robot using a range scanning sensor. When estimating the pose of the objects in a scene, it is obvious that range discontinuities and flat surfaces have the largest information content. The concept studied consists of a smart camera chip together with a scanning illuminating laser. Feedback loops are closed between the chip and the scanning laser so as to follow along different types of range discontinuities in the scene. More explicitly: two types of feedback laws are outlined so as to track along range discontinuities both with and without occlusion; the laser can also track along a `generalized cylinder', say, a cable free in space or laying on an uneven surface; the tracking accuracy is estimated as the laser follows along the `curve of discontinuity'. The results are too preliminary and are not in this paper. In an earlier study, the Hough transform was found to be very robust in extracting the coordinates of planar surfaces. The edge parameters in this study are thus complementary to these surface parameters. Compared with complete range scanning of the entire scene, it seems possible to gain at least one order of magnitude in speed. This is important since these extracted range features are inside the feedback loop of the robot

  • 162.
    Blomstedt, Fredrik
    et al.
    BnearIT AB, Luleå, Sweden.
    Ferreira, Luis Lino
    CISTER/INESC TEC, ISEP, Porto, Portugal.
    Klisics, Markus
    BnearIT AB, Luleå, Sweden.
    Christos, Chrysoulas
    CISTER/INESC TEC, ISEP, Porto, Portugal.
    de Soria, Iker Martinez
    TECNALIA Research & Innovation, Bilbao, Spain.
    Morin, Brice
    SINTEF ICT, Oslo, Norway.
    Zabasta, Anatolijs
    Riga Technical University, Riga, Latvia.
    Eliasson, Jens
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Johansson, Mats
    Luleå University of Technology.
    Varga, Pal
    Budapest University of Technology and Economics, Budapest, Hungary.
    The Arrowhead Approach for SOA Application Development and Documentation2015In: IECON 2014: 40th Annual Conference of the IEEE Industrial Electronics Society, Dallas, TX, USA , Oct. 29 2014 - Nov. 1 2014, Piscataway, NJ: IEEE Communications Society, 2015, p. 2631-2637Conference paper (Refereed)
    Abstract [en]

    The Arrowhead project aims to address the technical and applicative issues associated with cooperative automation based on Service Oriented Architectures. The problems of developing such kind of systems are mainly due to the lack of adequate development and service documentation methodologies, which would ease the burden of reusing services on different applications. The Arrowhead project proposes a technical framework to efficiently support the development of such systems, which includes several tools for documentation of services and to support the development of SOA-based installations. The work presented in this paper describes the approach which has been developed for the first generation pilots to support the documentation of their structural services. Each service, system and system- of-systems within the Arrowhead Framework must be documented and described in such way that it can be implemented, tested and deployed in an interoperable way. This paper presents the first steps of realizing the Arrowheadvision for interoperable services, systems and systems-of-systems.

  • 163.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dadhich, Siddharth
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Uhlin, Erik
    Volvo CE AB, Bolindervägen 100, 631 85 Eskilstuna, Sweden.
    Marklund, Ulf
    Boliden Mineral AB, Kontorsvägen 1, 936 81 Boliden, Sweden.
    Häggström, Derny
    Oryx Prototyping AB, Tvistevägen 48, 907 36 Umeå, Sweden.
    Remote Controlled Short-Cycle Loading of Bulk Material in Mining Applications2015In: IFAC-PapersOnLine, E-ISSN 2405-8963, Vol. 48, no 17, p. 54-59Article in journal (Refereed)
    Abstract [en]

    High-capacity wireless IP networks with limited delays are nowadays being deployed in both underground and open-pit mines. This allows for advanced remote control of mining machinery with improved feedback to operators and extensive monitoring of machine status, wear and fatigue. Wireless connectivity varies however depending on channel impairments caused by obstacles, multi-path fading and other radio issues. Therefore remote control and monitoring should be capable of adapting their sending rates to handle variations in communications quality. This paper presents key challenges in advanced remote control and monitoring of working machines via high-capacity wireless IP networks in mining environments. We reason about these challenges in context of underground short-cycle load, haul and dump operation with large-volume built wheel-loaders and present a generic communication solution for an operator assistance concept capable of adapting to varying communication properties

  • 164.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Christofferson, André
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Chiquito, Alex
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Rodahl, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Synnes, Kåre
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Application-scoped Access Control for the Construction Industry2021In: 2021 26th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), IEEE, 2021, p. 1-8Conference paper (Refereed)
    Abstract [en]

    The construction industry is characterized by its extensive and dynamic collaborations between contractors providing various services and expertise. In such eco-systems, the secure sharing of information, data and equipment challenges the access control needs to be application agnostic. Furthermore, it needs fine-grained access policies including means for abstraction to ease administration, and support for delegated authorization in Service-Oriented Architecture (SOA) based systems. In this paper, we explore the use of delegated access using OAuth 2.0 with Attribute-Based Access Control (ABAC) for the collaborative sharing of equipment at construction sites. In particular, we investigate the use of contextual attributes to capture the dynamic aspects, such as location and urgency, in the booking of construction lifts. Through this study, we propose a solution based on the IoT Application-scoped Access Control as a Service (IAACaaS) architecture model combined with NIST Next Generation Access Control (NGAC). We present an architecture for a general Identity and Access Management (IAM) system for the construction industry, and provide a design and guide for implementation of this architecture in terms how key functionalities should be captured as reusable micro-services. Moreover, we describe how these micro-services can be combined to make the system a general and reusable solution providing access control for collaborative sharing of data, information and equipment at construction sites.

  • 165.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Dhanrajani, Siddhant
    Karlsruhe Institute of Technology (KIT), wbk Institute of Production Science, Kaiserstr. 12, 76131 Karlsruhe, Germany.
    Abdalla, Abdelrahman H.
    Politecnico di Milano, Department of Mechanical Engineering, Via la Masa 1, 20156, Milan, Italy.
    Diani, Marco
    Politecnico di Milano, Department of Mechanical Engineering, Via la Masa 1, 20156, Milan, Italy.
    Klenk, Felix
    Karlsruhe Institute of Technology (KIT), wbk Institute of Production Science, Kaiserstr. 12, 76131 Karlsruhe, Germany.
    Colledani, Marcello
    Politecnico di Milano, Department of Mechanical Engineering, Via la Masa 1, 20156, Milan, Italy.
    Palm, Emanuel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Demand-supply matching through auctioning for the circular economy2021In: 10th CIRP Sponsored Conference on Digital Enterprise Technologies (DET 2020) – Digital Technologies as Enablers of Industrial Competitiveness and Sustainability / [ed] Jozsef Vancza; Paul Maropoulos, Elsevier, 2021, p. 82-87Conference paper (Refereed)
    Abstract [en]

    The circular economy aims to reduce the consumption of resources and energy by exploiting multiple use-cycles of components and materials. The creation of new circular businesses hinges on efficient alignment between market demands of circular products with the supply of End-of-life components and materials. In this paper, we address the digitization of a matchmaking tool for the circular economy by defining demand-supply matching (DSM) in context of business link identification and cross-sectorial matchmaking. We further specify a DSM process and p resent our DSM tool, which facilitates publication and search for supplier offerings and demander needs, selection of auctioning candidates, and digitized auctioning and contract definition. By that, this tool supports the alignment of market demands with matching supply offerings. In particular, it combines the steps of publishing, searching, selecting, auctioning and contract definition into one tool, which we argue can make matchmaking more efficient compared to addressing these steps separately. Finally, we present the design of the tool and discuss its merits in light of the needed acceptance for automating business link identification and contractual interactions.

  • 166.
    Bodén, Ida
    et al.
    Umeå universitet.
    Norén, L
    Luleå University of Technology.
    Wisten, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Geladi, Paul
    Umeå universitet.
    Nyström, J
    Umeå universitet.
    Lindholm-Sethsom, B
    Umeå universitet.
    Development and optimization of a novel skin impedance instrument2005In: Proceedings of the 13th Nordic-Baltic Conference of BioMedical Engineering and Medical Physics: NBC'05 / [ed] R Lundström; B Andersson; H Grip, Swedish Society for Medical Engineering and Medical Physics , 2005, p. 162-163Conference paper (Refereed)
    Abstract [en]

    A novel skin impedance instrument is presented. The reproducibility and stability of the measurements where evaluated with multivariate techniques and a tendency to separate different skin types with skin impedance measurements is seen.

  • 167.
    Borg, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    On electronics for measurement systems2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis collects the work performed by the author on electronics for measurement systems. The first part is the work performed on the EISCAT 3D ionospheric research radar, including two papers on the investigations on required performance, electronics design, and proof of concept signal processing. The thesis also contains work on a calibration system for mitigating signal path variations in large antenna arrays with distributed front-end electronics, enabling accurate beamforming of the received signal. Although the proposed system could in theory be entirely free from systematic errors, very large receiver dynamic range would be required in systems with many channels. Thus, in this work the measurement accuracy degradation arising when trying to reduce the dynamic range requirements has been investigated. A second part is on electronics for ultrasonic measurement systems. As one part of this part of the work, the systematic errors that arise in ultrasonic transit-time flow-meters when not utilizing the reciprocity of the flow-meter have been investigated experimentally. Based on this an integrated circuit for driving ultrasonic transducers using an arbitrary excitation waveform while maintaining constant interface impedance was designed and evaluated. By driving the ultrasonic transducer directly from a DAC the clock to output delay uncertainty was minimized. This, combined with matched on-chip receiver isolation switches enable on-line calibration against an on-chip reference DAC. These two and a work on a low-noise CMOS amplifier for ultrasonic applications are covered in three papers attached to this thesis. The third and final part is on evaluation of charge coupled devices, presented in the last paper of the thesis. It proposes a method for separating measured charge transfer inefficiency of a CCD into incomplete transfer of free charge and charge trapping in the substrate. We derive a generic model for the combined effects of charge trapping and incomplete transfer. This model further allows the charge transfer defects of a single gate to be calculated from the combined transfer inefficiency of a larger CCD. As proof of concept the method is applied to measurement data from a CCD manufactured using a 0.18 μm PINNED photo diode CMOS process.

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  • 168.
    Borg, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Performance and spatial sensitivity variations of single photon avalanche diodes manufactured in an image sensor CMOS process2015In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 36, no 11, p. 1118-1120Article in journal (Refereed)
    Abstract [en]

    In this letter we present the results from a series of single-photon avalanche diode (SPAD) structures implemented in a commercial 0.18 μm CMOS process intended for CMOS image sensors. Variations without effect on the performance and variations that produced non-functional devices are described. Devices based on the P+/NWELL and deep-NWELL/P-EPI SPADs junctions were found to work well in this process. When biased for 10% QE the best 10 μm diameter P+/NWELL SPADs exhibited a DCR of about 1 kHz, whereas the DCR of the deep-NWELL/P-EPI SPADs was only 10 Hz under the same conditions. We also show that the former type exhibited local sensitivity variations within the SPADs ranging from a factor 4 at low excess voltage to 1.2 at an excess voltage of about 0.5 V. No significant sensitivity variations were found for the deep- NWELL/P-EPI SPADs, but they were found to exhibit significant sensitivity outside the central junction, contributing from 8.3 % at low excess voltage to approximately 70% at high excess voltage

  • 169. Borg, Johan
    et al.
    Hyyppä, Kalevi
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Projekt: ESIS2010Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Samlingsprojekt för alla ESIS-projekt

  • 170.
    Borg, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Johansson, Jonny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    An ultrasonic transducer interface IC with integrated push-pull 40 Vpp, 400 mA current output, 8-bit DAC and integrated HV multiplexer2011In: IEEE Journal of Solid-State Circuits, ISSN 0018-9200, E-ISSN 1558-173X, Vol. 46, no 2, p. 475-484Article in journal (Refereed)
    Abstract [en]

    We present an ultrasonic transducer interface IC that includes an 8-bit, 40 V pp , 400 mA current output DAC for arbitrary waveform transducer excitation and a ±25 V analog multiplexer. The IC was fabricated using a 0.35 μm, 50 V CMOS process. The design eliminates the need for an external power amplifier as the piezoelectric transducer is driven directly from a segmented push-pull current output DAC, which simplifies the overall system design. This approach has the advantage of simple and rapid glitch-free power-up/down, which is especially important in integrated high-output-power drivers. The DAC has been evaluated when operating at a 150 MHz sampling rate with a ±400 mA output current and a 50 Ω load. Measured performance includes 37 dB SNDR and 46 dB SFDR at 10 MHz output frequency. By implementing an additional reference DAC and extending the receiver isolation switch into an analog multiplexer, we enable on-line calibration for the purpose of reducing the driver and receiver signal path uncertainty. Measurements show a greater than ten-fold improvement in delay uncertainty to approximately 20 ps for temperature variations of 0 to 70 degrees Celsius.

  • 171.
    Borg, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Johansson, Jonny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Delay insensitive signal-injection calibration for large antenna arrays using passive hierarchical networks2017In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, no 1, p. 190-195, article id 7747455Article in journal (Refereed)
    Abstract [en]

    Efficient beamforming of phased-array antennas requires that the phase delay of each channel is accurately known. One technique for achieving this is to distribute a calibration or local-oscillator reference signal through a delay-insensitive signal distribution network. In this paper, we propose using passive hierarchical signal distribution networks to distribute such signals, a method that scales significantly better with the size of the array than existing signal distribution methods. We analyze the impact of impedance variations within the network on the phase accuracy and propose a calibration front-end architecture. This front end also enables the return loss and coupling between antennas to be monitored for diagnostic purposes. We present an implementation of this front end that was applied to a small prototype antenna array, and show that this implementation exhibited low sensitivity to delays within the calibration network, reduced the temperature-dependent phase error of the front ends substantially, and can be used for performing antenna return-loss measurements

  • 172.
    Borg, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Johansson, Jonny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Evaluation of a surface-channel CCD manufactured in a pinned active-pixel-sensor CMOS process2011In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 58, no 8, p. 2660-2664Article in journal (Refereed)
    Abstract [en]

    This paper presents measurements on a surfacechannel CCD with gates implemented using single-layer polysilicongates. The device was manufactured in a 0.18 μm PINNEDphoto diode CMOS process commercially available from UMC.The CCD was built with a field-plate covering all gates as wellas the space between them, which allows the potential in the gapbetween non-overlapping gates to be manipulated.We present charge transfer efficiency measurements performedat clock frequencies of 1 MHz and 5 MHz, at multiplebackground packet sizes, and field-plate voltages. We furtherpropose and apply a method for separating CTI in four-phaseCCDs due to trapping from the inefficiency stemming from otherphenomena.The measurements show a single stage CTI ranging from 1.7×10−4 with a moderate background charge and substantial fieldplatevoltage, to 0.007 at zero field-plate voltage and the highestbackground charge tested. The CTI can be reduced significantly(more than a factor of 10 in some cases) by applying a significantnegative voltage at the field-plate. This, and the fact that only aminor part of the CTI can be attributed to trapping, indicatesthat the performance of the device is limited by the presence ofpotential hollows in the gaps between the gates.

  • 173.
    Borg, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Johansson, Jonny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Optimization of the design of an integrated ultrasonic preamplifier2008In: Proceedings of the International Congress on Ultrasonics: Vienna, April 9-13, 2007, International Congress on Ultrasonics , 2008Conference paper (Refereed)
    Abstract [en]

    Traditionally BJT or BiCMOS amplifiers have been used to achieve equivalent input noise densities of 1 nV√Hz or less, as desirable in some ultrasonic applications. Due to an increasing demand on increased integration it can be necessary to implement the amplifier in a CMOS process. As part of this design process we applied the particle swarm optimization to the problem of optimizing an amplifier specifically for operation in the 2-4 MHz frequency band. We present measurements on the manufactured circuit with performance comparable to the best available BJT-based amplifiers available today.

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  • 174.
    Borg, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Johansson, Jonny
    van Deventer, Jan
    Delsing, Jerker
    Reciprocal operation of ultrasonic transducers: experimental results2006In: Proceedings: 2006 IEEE Ultrasonics Symposium : Vancouver, Canada, 3 - 6 October 2006, Piscataway, NJ: IEEE Communications Society, 2006, p. 1013-1016Conference paper (Refereed)
    Abstract [en]

    Ultrasonic transit-time flow-meters estimate fluid or gas flows from the difference in times of flight of upstream and downstream acoustic pulses. However, any delay differences arising from sources other than the flow to be measured will cause a troublesome "zero flow" offset error.In theory, the transducers used in the measurement system should not influence the zero flow error, as electroacoustic systems based on piezoelectric transducers have been shown to be reciprocal (when the media is stationary). However, care is required when designing the electrical interfaces for the piezoelectric transducers, if reciprocity in the system is to be utilized.This work presents technique and measurements that apply reciprocity to an ultrasonic transit-time flow-meter. Specialized electrical transducer interfaces with options to drive the transducers from either low or high impedance sources were used. Combined with a high-impedance receive mode these options made it possible to change the conditions for reciprocity in the system.We show reduced delay difference in 9 cases out of 10 when trying to utilize the reciprocal property compared to when we disregard it in favor for larger excitation energy. The delay improvements were accompanied by reduced differences between the center frequencies of the signals from the two paths.

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  • 175.
    Borngrund, Carl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Automation of Navigation During the Short-loading Cycle Using Machine Vision2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Earth-moving machines are machines used in a wide range of industries, such as the construction industry, to perform tasks related to earthworks.Currently, the vast majority of earth-moving machines are human-operated where expert operators perform these industry vital tasks.One such task is the short-loading cycle which is a repetitive work cycle performed in high quantities within the construction industry.This work cycle aims to use a wheel-loader to move material from a pile or from the ground to the tipping body of a dump truck.Not only is this task repetitive and performed in high quantities, but it is also representative of the knowledge required to perform a wide set of other work cycles, hence a good candidate for automation.

    Skilled operators use their sensory input to perform the tasks required, such as tactile, sound and sight.One of the most important senses leveraged during normal operations is sight, as it is used to locate dynamic objects and detect dangers.Thus to be able to replace the driver of an earth-moving machine with an autonomous system, the system requires similar vision capabilities.Machine Vision is a field where the goal is to use some type of vision sensor, such as cameras, to extract relevant high-level information from images or video streams.This thesis aims to examine how machine vision can be used within the short-loading cycle to facilitate performing said work cycle autonomously.

    The main findings in this thesis are threefold: Firstly, two knowledge gaps are identified in the domain of automation during the short-loading cycle.These relate to the loading of heterogeneous material and navigation during loading and unloading.Secondly, we show that it is possible to train a deep learning model to detect the cab, wheels and tipping body of a scale-model dump truck while mimicking the approach towards the load carrier during the short-loading cycle.This model can then be applied to real vehicles to detect the same objects, with no additional training.Lastly, we show that linear interpolation can be used to perform semi-automatic labelling of camera-based video data of the approach of a wheel-loader towards a dump truck during the short-loading cycle.This technique decreases the annotation workload by around 95% while retaining comparable performance.

    The future direction of this work includes using techniques such as reinforcement learning to teach a model to perform the navigation required during the short-loading cycle.Future work also includes using world models to learn representations of underlying structures in the environment, open-ended learning to transfer the learned knowledge to adjacent work cycles and using machine vision to find the point of attack for scooping heterogeneous material.

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  • 176.
    Borngrund, Carl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Dump truck object detection dataset including scale-models2020Data set
    Abstract [en]

    Object detection is a vital part of any autonomous vision system and to obtain a high performing object detector data is needed. The object detection task aims to detect and classify different objects using camera input and getting bounding boxes containing the objects as output. This is usually done by utilizing deep neural networks.When training an object detector a large amount of data is used, however it is not always practical to collect large amounts of data. This has led to multiple different techniques which decreases the amount of data needed. Examples of such techniques are transfer learning and domain adaptation. Working with construction equipment is a time consuming process and we wanted to examine if it was possible to use scale-model data to train a network and then used that network to detect real objects with no additional training.This small dataset contains training and validation data of a scale dump truck in different environments while the test set contains images of a full size dump truck of similar model. The aim of the dataset is to train a network to classify wheels, cabs and tipping bodies of a scale-model dump truck and use that to classify the same classes on a full-scale dump truck.

  • 177.
    Borngrund, Carl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Towards Deep-learning-based Autonomous Navigation in the Short-loading Cycle2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Earth-moving machines, such as wheel loaders, are a type of heavy-duty machinery used within the construction industry to perform vital tasks, such as digging, transporting, and mining applications. One of these tasks is the short-loading cycle, where an operator manoeuvres the wheel loader to move material from a pile to the tipping body of a dump truck, through navigation, scooping, and dumping. The short-loading cycle is a repetitive task performed in high quantities, often as part of a larger refinement process, making it interesting for automation.

    The main objective of this thesis work is to investigate challenges facing the automation of the short-loading cycle, focusing in particular on subtasks that can be efficiently addressed with deep learning methods. A secondary objective is to examine how alternative development paths, such as scale models, or simulations, can be used to enable data-driven automation of the short-loading cycle, as directly experimenting on real vehicles has a high associated cost when large numbers of timesteps are needed to gather enough data.

    To investigate the two objectives, the literature is systematically reviewed to identify research gaps, challenges, and the usage of deep learning techniques. Secondly, a set of deep learning techniques is investigated to address perception and actuation problems identified as challenging and important for the automation of the short-loading cycle.

    The investigation of deep learning techniques involves training and validating a realtime object detector neural network to identify key components (wheels, tipping body, and cab) on a scale model dump truck while testing on a real vehicle. This resulted in a localisation and classification degradation of only 14% between the scale model and the real dump truck, with no additional training. In addition, an examination to minimize the annotation workload of humans found that it is possible to decrease the workload by 95% while still retaining similar detection performance by leveraging linear interpolation.

    Lastly, this thesis presents an investigation regarding the usage of reinforcement learning for navigation during the short-loading cycle. The results indicate that training the agent in simulation is currently required as the agent obtains the maximum reward after timesteps in the order of millions before being capable of performing the task. The results suggest that the trained agent is capable of bridging the gap between simulation and reality to complete a simplified version of the navigation task during the short-loading cycle.

    The experiments presented in this thesis provide proof of concept that indicates deep learning techniques can aid in the realisation of an autonomous solution. Moreover, the results show that development paths allowing for experiments providing large numbers of timesteps can facilitate the practical use of such techniques.

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  • 178.
    Borngrund, Carl
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Andreasson, Henrik
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Automating the Short-Loading Cycle: Challenges, Survey and Integration FrameworkManuscript (preprint) (Other academic)
  • 179.
    Borngrund, Carl
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Machine Vision for Construction Equipment by Transfer Learning with Scale Models2020In: 2020 International Joint Conference on Neural Networks (IJCNN), IEEE, 2020, article id 21108Conference paper (Refereed)
    Abstract [en]

    Machine vision is required by autonomous heavy construction equipment to navigate and interact with the environment. Wheel loaders need the ability to identify different objects and other equipment to perform the task of automatically loading and dumping material on dump trucks, which can be achieved using deep neural networks. Training such networks from scratch requires the iterative collection of potentially large amounts of video data, which is challenging at construction sites because of the complexity of safely operating heavy equipment in realistic environments. Transfer learning, for which pretrained neural networks can be retrained for use at construction sites, is thus attractive, especially if data can be acquired without full-scale experiments. We investigate the possibility of using scalemodel data for training and validating two different pretrained networks and use real-world test data to examine their generalization capability. A dataset containing 268 images of a 1:16 scale model of a Volvo A60H dump truck is provided, as well as 64 test images of a full-size Volvo A25G dump truck. The code and dataset are publicly available 1 . The networks, both pretrained on the MS-COCO dataset, were fine-tuned to the created dataset, and the results indicate that both networks can learn the features of the scale-model dump truck (validation mAP of 0.82 for YOLOv3 and 0.95 for RetinaNet). Both networks can transfer these learned features to detect objects on a full-size dump truck with no additional training (test mAP of 0.70 for YOLOv3 and 0.79 for RetinaNet).

  • 180.
    Borngrund, Carl
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Andreasson, Henrik
    Centre for Applied Autonomous Sensor Systems, Örebro University, Sweden.
    Autonomous Navigation of Wheel Loaders using Task Decomposition and Reinforcement Learning2023In: 2023 IEEE 19th International Conferenceon Automation Science and Engineering (CASE), IEEE, 2023Conference paper (Refereed)
  • 181.
    Borngrund, Carl
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science. Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Andreasson, Henrik
    Learning the Approach During the Short-loading Cycle Using Reinforcement LearningManuscript (preprint) (Other academic)
  • 182.
    Borngrund, Carl
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Hammarkvist, Tom
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Semi-Automatic Video Frame Annotation for Construction Equipment Automation Using Scale-Models2021In: IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, IEEE, 2021Conference paper (Refereed)
    Abstract [en]

    Data collection and annotation is a time consuming and costly process, yet necessary for machine vision. Automation of construction equipment relies on seeing and detecting different objects in the vehicle’s surroundings. Construction equipment is commonly used to perform frequent repetitive tasks, which are interesting to automate. An example of such a task is the short-loading cycle, where the material is moved from a pile into the tipping body of a dump truck for transport. To complete this task, the wheel loader needs to have the capability to locate the tipping body of the dump truck. The machine vision system also allows the vehicle to detect unforeseen dangers such as other vehicles and more importantly human workers. In this work, we investigate the viability to perform semi-automatic annotation of video data using linear interpolation. The data is collected using scale-models mimicking a wheel-loaders approach towards a dump truck during the short-loading cycle. To measure the viability of this type of solution, the workload is compared to the accuracy of the model, YOLOv3. The results indicate that it is possible to maintain the performance while decreasing the annotation workload by about 95%. This is an interesting result for this application domain, as safety is critical and retaining the vision system performance is more important than decreasing the annotation workload. The fact that the performance seems to retain with a large workload decrease is an encouraging sign.

  • 183.
    Borngrund, Carl
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Deep-learning-based vision for earth-moving automation2022In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891, Vol. 133, article id 104013Article, review/survey (Refereed)
    Abstract [en]

    Earth-moving machines are heavy-duty vehicles designed for construction operations involving earthworks. The tasks performed by such machines typically involve navigation and interaction with materials such as soil, gravel, and blasted rock. Skilled operators use a combination of visual, sound, tactile and possibly motion feedback to perform tasks efficiently. We survey the literature in this research area and analyse the relative importance of different sensor system modalities focusing on deep-learning-based vision and automation for the short-cycle loading task. This is a common and repetitive task that is attractive to automate. The analysis indicates that computer vision, in combination with onboard sensors, is more critical than coordinate-based positioning. Furthermore, we find that data-driven approaches, in general, have high potential in terms of productivity, adaptability, versatility and wear and tear with respect to automation system solutions. The main knowledge gaps identified relate to loading non-fine heterogeneous material and navigation during loading and unloading.

  • 184.
    Borowski, Holly
    et al.
    Research and Engineering Center for Unmanned Vehicles, University of Colorado-Boulder, United States.
    Isoz, Oscar
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Eklöf, Fredrik Marsten
    NAVWAR Research, Swedish Defense Research Agency, Sweden.
    Lo, Sherman
    Stanford GPS Laboratory, Stanford University, United States.
    Akos, Dennis
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. Stanford GPS Laboratory, Stanford University, United States; Aerospace Engineering Sciences Department, University of Colorado, United States.
    Detecting false signals with automatic gain control2012In: GPS World, ISSN 1048-5104, Vol. 23, no 4, p. 38-43Article in journal (Refereed)
    Abstract [en]

    A component of most GPS receiver front-ends, the automatic gain control (AGC) can flag potential jamming and spoofing attacks. The detection method is simple to implement and accessible to most GPS receivers. It may be used alone or as a complement other anti-spoofing architectures. This article presents results from a baseline AGC characterization, develos a simple spoofing detection method, and demonstrate the results of that method on receiver data gathered in the presence of a live spoofing attack.

  • 185.
    Bota, András
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Gardner, Lauren
    Department of Civil and Systems Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
    A Generalized Framework for the Estimation of Edge Infection Probabilities2023In: Algorithms, E-ISSN 1999-4893, Vol. 16, no 8, article id 390Article in journal (Refereed)
    Abstract [en]

    Modeling the spread of infections in networks is a well-studied and important field of research. Most infection and diffusion models require a real value or probability at the edges of the network as an input, but this is rarely available in real-life applications. The Generalized Inverse Infection Model (GIIM) has previously been used in real-world applications to solve this problem. However, these applications were limited to the specifics of the corresponding case studies, and the theoretical properties, as well as the wider applicability of the model, are yet to be investigated. Here, we show that the general model works with the most widely used infection models and is able to handle an arbitrary number of observations on such processes. We evaluate the accuracy and speed of the GIIM on a large variety of realistic infection scenarios.

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  • 186.
    Bota, András
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. Integrated Science Lab, Department of Physics, Umeå University, 90187, Umeå, Sweden.
    Holmberg, Martin
    Integrated Science Lab, Department of Physics, Umeå University, 90187, Umeå, Sweden.
    Gardner, Lauren
    Department of Civil and Systems Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.
    Rosvall, Martin
    Integrated Science Lab, Department of Physics, Umeå University, 90187, Umeå, Sweden.
    Socioeconomic and environmental patterns behind H1N1 spreading in Sweden2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, article id 22512Article in journal (Refereed)
    Abstract [en]

    Identifying the critical factors related to influenza spreading is crucial in predicting and mitigating epidemics. Specifically, uncovering the relationship between epidemic onset and various risk indicators such as socioeconomic, mobility and climate factors can reveal locations and travel patterns that play critical roles in furthering an outbreak. We study the 2009 A(H1N1) influenza outbreaks in Sweden’s municipalities between 2009 and 2015 and use the Generalized Inverse Infection Method (GIIM) to assess the most significant contributing risk factors. GIIM represents an epidemic spreading process on a network: nodes correspond to geographical objects, links indicate travel routes, and transmission probabilities assigned to the links guide the infection process. Our results reinforce existing observations that the influenza outbreaks considered in this study were driven by the country’s largest population centers, while meteorological factors also contributed significantly. Travel and other socioeconomic indicators have a negligible effect. We also demonstrate that by training our model on the 2009 outbreak, we can predict the epidemic onsets in the following five seasons with high accuracy.

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  • 187.
    Bridgwater, Alexander
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Bóta, András
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Identifying regions most likely to contribute to an epidemic outbreak in a human mobility network2021In: 2021 Swedish Artificial Intelligence Society Workshop (SAIS), IEEE, 2021, p. 1-4Conference paper (Refereed)
    Abstract [en]

    The importance of modelling the spreading of infectious diseases as part of a public health strategy has been highlighted by the ongoing coronavirus pandemic. This includes identifying the geographical areas or travel routes most likely to contribute to the spreading of an outbreak. These areas and routes can then be monitored as part of an early warning system, be part of intervention strategies, e.g. lockdowns, aiming to mitigate the spreading of the disease or be a focus of vaccination campaigns.

    In this paper we present our work in developing a network-based infection model between the municipalities of Sweden in order to identify the areas most likely to contribute to an epidemic. We first construct a human mobility model based on the well-known radiation model, then we employ a network-based compartmental model to simulate epidemic outbreaks with various parameters. Finally, we adopt the influence maximization problem known in network science to identify the municipalities having the largest impact on the spreading of infectious diseases.

    We only present the first part of our work in this paper. In the future, we plan to investigate the robustness of our model in identifying high-risk areas by simulating outbreaks with various parameters. We also plan to extend our work to selecting the most likely infection paths contributing to the spreading of infectious diseases.

  • 188.
    Brodnik, Andrej
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Karlsson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Munro, Ian
    Faculty of Education, University of Primorska.
    Nilsson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    An O(1) solution to the prefix sum problem on a specialized memory architecture2006In: PFourth IFIP International Conference on Theoretical Computer Science - TCS 2006: IFIP 19th World Computer Congress, TC-1, Foundations of Computer Science, August 23-24, 2006, Santiago, Chile / [ed] Gonzalo Navarro; Leopoldo Bertossi; Yoshiharu Kohayakawa, New York: Encyclopedia of Global Archaeology/Springer Verlag, 2006, p. 103-114Conference paper (Refereed)
    Abstract [en]

    In this paper we study the Prefix Sum problem introduced by Fredman. We show that it is possible to perform both update and retrieval in O(1) time simultaneously under a memory model in which individual bits may be shared by several words. We also show that two variants (generalizations) of the problem can be solved optimally in Θ(lgN) time under the comparison based model of computation.

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  • 189.
    Brodnik, Andrej
    et al.
    Luleå University of Technology. Department of Theoretical Computer Science, Institute of Math- ematics, Physics, and Mechanics, Ljubljana, Slovenia.
    Nilsson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    A static data structure for discrete advance bandwidth reservations on the Internet2003In: Proceedings of Swedish National Computer Networking Workshop: SNCNW 2003, Stockholm, 2003Conference paper (Refereed)
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  • 190. Brodnik, Andrej
    et al.
    Nilsson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    An efficient data structure for advance bandwidth reservations on the Internet2002In: Proceedings of CSEE 2002: Second Annual Conference on Computer Science and Electrical Engineering. The third Annual Symposium on Computer Science and Electrical Engineering, 2002Conference paper (Refereed)
    Abstract [en]

    In this contribution we present a problem of resource reservation during some time. We show that the problem has a lower bound of Ω (log n) per operation on average and also give a matching upper bound algorithm.

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  • 191. Brodnik, Andrej
    et al.
    Nilsson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Data structure for a time-based bandwidth reservations problem2003Report (Other academic)
    Abstract [en]

    We discuss a problem of handling resource reservations. The resource can be reserved for some time, it can be freed or it can be queried what is the largest amount of reserved resource during a time interval. We show that the problem has a lower bound of $\Omega(\log n)$ per operation on average and we give a matching upper bound algorithm. Our solution also solves a dynamic version of the related problems of a prefix sum and a partial sum.

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  • 192. Brodnik, Andrej
    et al.
    Nilsson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Static data structure for discrete advance bandwidth reservations on the internet2003Report (Other academic)
    Abstract [en]

    In this paper we present a discrete data structure for reservations of limited resources. A reservation is defined as a tuple consisting of the time interval of when the resource should be reserved, $I_R$, and the amount of the resource that is reserved, $B_R$, formally $R=\{I_R,B_R\}$. The data structure is similar to a segment tree. The maximum spanning interval of the data structure is fixed and defined in advance. The granularity and thereby the size of the intervals of the leaves is also defined in advance. The data structure is built only once. Neither nodes nor leaves are ever inserted, deleted or moved. Hence, the running time of the operations does not depend on the number of reservations previously made. The running time does not depend on the size of the interval of the reservation either. Let $n$ be the number of leaves in the data structure. In the worst case, the number of touched (i.e. traversed) nodes is in any operation $O(\log n)$, hence the running time of any operation is also $O(\log n)$.

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  • 193.
    Brännvall, Rickard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Machine learning based control of small-scale autonomous data centers2020Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The low-latency requirements of 5G are expected to increase the demand for distributeddata storage and computing capabilities in the form of small-scale data centers (DC)located at the edge, near the interface between mobile and wired networks. These edgeDC will likely be of modular and standardized designs, although configurations, localresource constraints, environments and load profiles will vary and thereby increase theDC infrastructure diversity. Autonomy and energy efficiency are key objectives for thedesign, configuration and control of such data centers. Edge DCs are (by definition)decentralized and should continue operating without human intervention in the presenceof disturbances, such as intermittent power failures, failing components and overheating.Automatic control is also required for efficient use of renewable energy, batteries and theavailable communication, computing and data storage capacity.

    These objectives demand data-driven models of the internal thermal and electricprocesses of an autonomous edge DC, since the resources required to manually defineand optimize the models for each DC would be prohibitive. In this thesis machinelearning methods that are implemented in a modular design are evaluated for thermalcontrol of such modular DCs. Experiments with small server clusters are presented, whichwere performed in order to investigate what parameters that are important in the designof advanced control strategies for autonomous edge DC. Furthermore, recent transferlearning results are discussed to understand how to develop data driven models thatcan be deployed to modular DC in varying configurations and environmental contextswithout training from scratch.

    The first study demonstrates how a data driven thermal model for a small clusterof servers can be calibrated to sensor data and used for constructing a model predictivecontroller for the server cooling fan. The experimental investigations of cooling fancontrol continues in the next study which explores operational sweet-spots and energyefficient holistic control strategies. The machine learning based controller from the firststudy is then re-purposed to maintain environmental conditions in an exhaust chamberfavourable for drying apples, as part of a practical study how excess heat produced bycomputation can be used in the food processing industry. A fourth study describes theRISE EDGE lab - a test bed for small data centers - built with the intention to exploreand evaluate related technologies for micro-grids with renewable energy and batteries,5G connectivity and coolant storage. Finally the last work presented develops the modelfrom the first study towards an application for thermal based load balancing.

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    fulltext
  • 194.
    Brännvall, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. ICE Data Center, RISE Research Institutes of Sweden AB, 973 47 Luleå, Sweden.
    Gustafsson, Jonas
    ICE Data Center, RISE Research Institutes of Sweden AB, 973 47 Luleå, Sweden.
    Sandin, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Modular and Transferable Machine Learning for Heat Management and Reuse in Edge Data Centers2023In: Energies, E-ISSN 1996-1073, Vol. 16, no 5, article id 2255Article in journal (Refereed)
    Abstract [en]

    This study investigates the use of transfer learning and modular design for adapting a pretrained model to optimize energy efficiency and heat reuse in edge data centers while meeting local conditions, such as alternative heat management and hardware configurations. A Physics-Informed Data-Driven Recurrent Neural Network (PIDD RNN) is trained on a small scale-model experiment of a six-server data center to control cooling fans and maintain the exhaust chamber temperature within safe limits. The model features a hierarchical regularizing structure that reduces the degrees of freedom by connecting parameters for related modules in the system. With a RMSE value of 1.69, the PIDD RNN outperforms both a conventional RNN (RMSE: 3.18), and a State Space Model (RMSE: 2.66). We investigate how this design facilitates transfer learning when the model is fine-tuned over a few epochs to small dataset from a second set-up with a server located in a wind tunnel. The transferred model outperforms a model trained from scratch over hundreds of epochs.

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    fulltext
  • 195.
    Brännvall, Rickard
    et al.
    Research Institutes of Sweden.
    Kovács, György
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Rizk, Aya
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Digital Services and Systems.
    Lehtonen, Viktor
    Eriksson, Ann-Christin
    Edman, Tobias
    Liwicki, Marcus
    National Space Data Lab on Kubernetes2019Conference paper (Other academic)
    Abstract [en]

    The National Space Data Lab is a collaboration project between Swedish National Space Agency, RISE Research Institutes of Sweden, Luleå University of Technology and AI Sweden. It will be a national knowledge and data hub for Swedish authorities’ work on earth observation data and for the development of AI-based analysis of data, generated in space systems. The platform is deployed on Kubernetes.

    Purpose

    • Increase the availability of space data for the benefit of developing society and industry

    • Provide platform for accessing space data and analytical tools

  • 196.
    Brännvall, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Mattson, Louise
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Lundmark, Erik
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Vesterlund, Mattias
    RISE ICE Data Center, Research Institutes of Sweden, Luleå, Sweden.
    Data Center Excess Heat Recovery: A Case Study of Apple Drying2020In: ECOS 2020: Proceedings of the 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Enviromental Impact of Energy Systems / [ed] Ryohei Yokoyama, Yoshiharu Amano, ECOS 2020 Local Organizing Committee , 2020, p. 2165-2174Conference paper (Refereed)
    Abstract [en]

    Finding synergies between heat producing and heat consuming actors in an economy provides opportunity for more efficient energy utilization and reduction of overall power consumption. We propose to use low-grade heat recovered from data centers directly in food processing industries, for example for the drying of fruit and berries. This study analyses how the heat output of industrial IT-load on servers can dry apples in a small-scale experimental set up.To keep the temperatures of the server exhaust airflow near a desired set-point we use a model predictive controller (MPC) re-purposed to the drying experiment set-up from a previous work that used machine learning models for cluster thermal management. Thus, conditions with for example 37 C for 8 hours drying can be obtained with results very similar to conventional drying of apples.The proposed solution increases the value output of the electricity used in a data center by capturing and using the excess heat that would otherwise be exhausted. The results from our experiments show that drying foods with excess heat from data center is possible with potential of strengthening the food processing industry and contribute to food self-sufficiency in northern Sweden.

  • 197.
    Brännvall, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. RISE AB, Research Institutes of Sweden, Luleå, Sweden.
    Sarkinen, Jeffrey
    RISE AB, Research Institutes of Sweden, Luleå, Sweden.
    Svartholm, Joar
    RISE AB, Research Institutes of Sweden, Luleå, Sweden.
    Gustafsson, Jonas
    RISE AB, Research Institutes of Sweden, Luleå, Sweden.
    Summers, Jon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics. RISE AB, Research Institutes of Sweden, Luleå, Sweden.
    Digital Twin for Tuning of Server Fan Controllers2019In: 2019 IEEE 17th International Conference on Industrial Informatics (INDIN), IEEE, 2019, p. 1425-1428Conference paper (Other academic)
    Abstract [en]

    Cooling of IT equipment consumes a large proportion of a modern data centre's energy budget and is therefore an important target for optimal control. This study analyses a scaled down system of six servers with cooling fans by implementing a minimal data driven time-series model in TensorFlow/Keras, a modern software package popular for deep learning. The model is inspired by the physical laws of heat exchange, but with all parameters obtained by optimisation. It is encoded as a customised Recurrent Neural Network and exposed to the time-series data via n-step Prediction Error Minimisation (PEM). The thus obtained Digital Twin of the physical system is then used directly to construct a Model Predictive Control (MPC) type regulator that executes in real time. The MPC is then compared in simulation with a self-tuning PID controller that adjust its parameters on-line by gradient descent.

  • 198.
    Brännvall, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. Research Institutes of Sweden, Digital Systems, Computer Science, ICE Datacenter.
    Siltala, Mikko
    Research Institutes of Sweden, Digital Systems, Computer Science, ICE Datacenter.
    Gustafsson, Jonas
    Research Institutes of Sweden, Digital Systems, Computer Science, ICE Datacenter.
    Sarkinen, Jeffrey
    Research Institutes of Sweden, Digital Systems, Computer Science, ICE Datacenter.
    Vesterlund, Mattias
    Research Institutes of Sweden, Digital Systems, Computer Science, ICE Datacenter.
    Summers, Jon
    Research Institutes of Sweden, Digital Systems, Computer Science, ICE Datacenter.
    EDGE: Microgrid Data Center with Mixed Energy Storage2020In: e-Energy '20: Proceedings of the Eleventh ACM International Conference on Future Energy Systems, Association for Computing Machinery (ACM), 2020, p. 466-473Conference paper (Refereed)
    Abstract [en]

    Low latency requirements are expected to increase with 5G telecommunications driving data and compute to EDGE data centers located in cities near to end users.

    This article presents a testbed for such data centers that has been built at RISE ICE Datacenter in northern Sweden in order to perform full stack experiments on load balancing, cooling, micro-grid interactions and the use of renewable energy sources. This system is described with details on both hardware components and software implementations used for data collection and control. A use case for off-grid operation is presented to demonstrate how the test lab can be used for experiments on edge data center design, control and autonomous operation.

    Download full text (pdf)
    E2DC2020_Edge_Setup
  • 199.
    Brännvall, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. RISE ICE - Research Institutes of Sweden, Sweden.
    Öhman, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Kovács, György
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Liwicki, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Cross-Encoded Meta Embedding towards Transfer Learning2020In: ESANN 2020 - Proceedings, ESANN , 2020, p. 631-636Conference paper (Refereed)
    Abstract [en]

    In this paper we generate word meta-embeddings from already existing embeddings using cross-encoding. Previous approaches can only work with words that exist in each source embedding, while the architecture presented here drops this requirement. We demonstrate the method using two pre-trained embeddings, namely GloVE and FastText. Furthermore, we propose additional improvements to the training process of the meta-embedding. Results on six standard tests for word similarity show that the meta-embedding trained outperforms the original embeddings. Moreover, this performance can be further increased with the proposed improvements, resulting in a competitive performance with those reported earlier.

  • 200. Bucht, Thore
    et al.
    Kjellmert, Bo
    Löfqvist, Torbjörn
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Experimentell metodik1995 (ed. 5)Book (Other (popular science, discussion, etc.))
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