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  • 351.
    Dong, N.
    et al.
    University of Science and Technology of China.
    Yin, M.
    University of Science and Technology of China.
    Ning, Lixin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Guo, H.
    University of Science and Technology of China.
    Zhang, W.P.
    University of Science and Technology of China.
    Spectroscopic analysis of LiKGdF5 : Er3+, Sm3+ single crystal2006In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 424, no 1-2, p. 334-337Article in journal (Refereed)
    Abstract [en]

    Low temperature photoluminescence spectra were measured under the selective excitation to the energy levels of Gd3+,Er3+ and Sm3+, respectively. Corresponding transitions were assigned with the help of fluorescence decay measurements. By assuming that the rare earth ion is in C-2v symmetry instead of the actual C-2, crystal field calculations were carried out based on the deduced experimental energy level data of Er3+ and Sm3+. The theoretical result is in good agreement with the experimental data.

  • 352.
    Dreier, Till
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design and verification of a USB 3.0 readout system for Timepix3 hybrid pixel detectors2018Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis describes the design, implementation, and verification of a USB 3.0 readout system for Timepix3 detectors. Timepix3 is a hybrid pixel detector consisting of a 256x256 pixel matrix with a 55 μm pitch and a timing resolution of 1.56ns. It allows to measure energy and time simultaneously utilising an event-driven data stream with a maximum data rate of up to 5.12 Gb/s or up to 85 million hits per second. Our aim is to implement a readout system that allows to add processing algorithms into the firmware, reducing the amount of data and the post-processing time. USB 3.0 was selected as an interface, because it provides a sufficient data rate and is present on all modern computers. Furthermore, the selected Opal Kelly XEM6310 development board provides a framework handling the communication between the FPGA and the host computer, FPGA components, and an API.

    We implemented a hardware adapter board in collaboration with the University of Glasgow connecting the development board to the detector chip board converting the detector’s output signals from SLVS to LVDS signals. Moreover, we implemented FPGA firmware consisting of a detector interface, USB interface, and a core including a processing interface. A multi-platform desktop library was implemented in C/C++ using Qt, which is used to configure the readout system and handles high speed data streaming. Data analysis and verification is conducted using custom build Python scripts.

    Simulations of the firmware showed the expected behaviour. The firmware and library were verified by configuring the detector, reading back the configuration, and measurements with an Americium source. An equalisation and a global and per-pixel energy calibration have been done successfully. Moreover, the system has been used to create and correct an X-ray image. Furthermore, the USB 3.0 data streaming performance was evaluated and it could be shown that the system can sustain a stream of around 380 MB/s.

    The proposed readout system has been implemented and was verified in simulation and experiments with X-ray radiation. USB 3.0 data streaming performed better than anticipated reaching higher speeds as stated by Opal Kelly. Furthermore, the firmware and the library function as intended. The hardware adapter requires some changes to accommodate higher data speeds and the data chan- nels have to be moved to different pins to allow synchronisation to an external clock.

  • 353.
    Du, Yijun
    et al.
    University of Science and Technology of China, Hefei, China.
    Wu, Xiaopo
    University of Science and Technology of China, Hefei, China.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Wang, Gang
    University of Science and Technology of China, Hefei, China.
    Design of Sharp Roll-Off Band Notch with Fragment-Type Pattern Etched on UWB Antenna2018In: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 17, no 12, p. 2404-2408Article in journal (Refereed)
    Abstract [en]

    Fragment-type etch patterns are proposed and designed on ultra-wideband planar antenna to acquire sharp roll-off band notch. Multi-objective evolutionary algorithm is applied to achieve the optimization searching of the best fragment-type etch pattern by setting multiple objectives to acquire the exact notched band and challenge the roll-off criterion (ROC) of band notch. Efficiency of the design can be improved by properly presetting slits on the patch radiator. For demonstration, designs with different slit presetting are implemented and tested. With single slit preset, band notch of ROC=0.72 at the WLAN band ranging from 5.15 GHz to 5.85GHz is acquired. 

  • 354.
    Du, Yijun
    et al.
    Univ Sci & Technol China, Hefei, Anhui, Peoples R China.
    Wu, Xiaopo
    Univ Sci & Technol China, Hefei, Anhui, Peoples R China.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Wang, Gang
    Univ Sci & Technol China, Hefei, Anhui, Peoples R China; Chinese Acad Sci, Beijing, Peoples R China.
    Design of ultra-wideband antenna with high-selectivity band notches using fragment-type etch pattern2020In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 62, no 2, p. 912-918Article in journal (Refereed)
    Abstract [en]

    By specifying objective functions defining the two bands to be notched with high roll-off criteria (ROCs), optimization searching for the best fragment-type etch pattern on ultra-wideband (UWB) antenna is implemented by using multi-objective optimization. The optimization with too many objective functions requires special treatment to improve the searching efficiency. In this design, two slits are preset on appropriate positions on different sides of the UWB radiator to constrain the decision space for etch pattern searching and yield two initial notched bands to speed up the optimization. For demonstration, a UWB patch antenna is designed with dual-band notches of ROC = 0.63 at WiMAX band and ROC = 0.65 at WLAN band. Both the simulation and measurement results indicate that there is significant improvement of the selectivity of the dual-band notches.

  • 355.
    Duan, Jiatong
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Optimization and development of the welding system for fiber-optic duct joints2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At present, the fiber optic ducts are connected by a mechanical type of joint. In this method, two ducts cut in the right angle are pushed in from both sides of the

    joint, and takes approximately one second to joint ducts together. The problem with the existing joint technology is that if there is water inside of the joint, it will be damaged when the water freezes into ice, and then may cause leakage. There is a risk of explosion when compressed air to blow the fiber. Thus, a joint protection device (silicone rubber sleeve) was developed to seal the joint for protection utterly. However, this will cause the larger size of the entire joint and limit the number of single-duct joints next to each other in a multi-duct joint. Fiber optic ducts are made of High-Density Polyethylene, which is the best plastic for remelting and can be welded by using the electro-fusion welding method. Based on the thermoplasticity of this material, this thesis developed a plastic joint with a built-in conductive metal wire inside. The applied voltage will heat the wire, then remelt the duct surfaces to weld them together through the joint. The welding system uses a portable battery operating system, so there is no need to connect it to the grid. To prevent the battery

    from being damaged by supplying too much current, a capacitor bank is used to store high energy for the preheating joints. The system uses a microcontroller to control and monitor current and voltage to ensure uniform heating of the metal wire.

    Theemphasisof this thesis isplacedon the implementation of basic experiments to run the welding system. Multiple welding experiments show that the welding system can manually set parameters to control the welding current of different joints, thereby ensuring the welding quality. Using a 2.5Ω joint to weld ducts will approximately consume 120J from the battery, so a fully charged 42V, 4.4AH rechargeable battery can perform almost 5600 times of welding. The suitable range of joint resistance will decrease as the required energy consumption increases/ the welding time decreases.

  • 356. Duan, M.
    et al.
    Fröjdh, Christer
    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.
    Wang, W.
    Linnros, J.
    Petersson, Sture
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Deposition of Scintillating Layers of Bismuth Germanate (BGO) Films for X-ray detector applications1998In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 45, no 3, p. 525-527Article in journal (Refereed)
    Abstract [en]

    Bi4Ge3O12 films were deposited by pulsed laser ablation on glass and SiO2/Si substrates. The crystal structures of the films depend on the deposition temperature. XRD patterns indicate that the films deposited at substrate temperature less than 400°C are amorphous. The as deposited amorphous films can be crystallized by post rapid thermal annealing (RTA) in the temperature window from 750°C to 800°C for 2 minutes in a oxygen ambient environment. RBS measurements confirm that the films have the same chemical composition as that of the target. The surface morphology of the films were characterized by atomic force microscopy (AFM)

  • 357.
    Dubaric, Ervin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Bertilsson, Kent
    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.
    Simulations of Submicron MOSFETs in 2H, 4H and 6H-SiC2002In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 101, p. 14-17Article in journal (Refereed)
    Abstract [en]

    In this paper, we present numerical studies of the high frequency performance of a submicron MOSFET in 2H-, 4H- and 6H-SiC. The studies are based on simulations where commercial two-dimensional drift-diffusion and hydrodynamic carrier transport models have been used. The results have been compared with those obtained from full band Monte Carlo simulations. The Monte Carlo carrier transport model is based on data from a full potential band structure calculation using the Local Density Approximation to the Density Functional Theory. In 6H-SiC the bulk transport properties in the direction perpendicular to the c-axis, are slightly lower than in 2H- and 4H-SiC. However, in the direction parallel to the c-axis the transport properties are considerably less favourable than in the other two polytypes. The effects of these differences, on surface mobility device performance and carrier energy, have been studied.

  • 358.
    Dubaric, Ervin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Fröjdh, Christer
    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.
    Abdallah, Munir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Pettersson, C.S.
    Monte Carlo simulations of the imaging properties of scintillator coated X-ray pixel detectors2000In: IEEE Nuclear Science Symposium and Medical Imaging Conference: vol. 1, IEEE conference proceedings, 2000, Vol. 1, p. 6/282-6/285Conference paper (Refereed)
    Abstract [en]

    The imaging properties of X-ray pixel detectors depend on the quantum efficiency for X-rays, the generated signal for each X-ray photon and the distribution of the generated signal between different pixels. In a scintillator coated device the signal is generated both by X-ray photons captured in the scintillator and by X-ray photons captured directly in the semiconductor. Hence, the signal-to-noise ratio (SNR) in the image is then a function of the number of photons captured in each of these processes, and the yield of each process, in terms of electron-hole pairs (EHPs) produced in the semiconductor. The full process from the absorption of the X-ray photon to the final signal read out from the detector has been simulated with a combination of the Monte Carlo program MCNP and the commercial carrier transport simulation tool MEDICI. An in house program calculating the light transport between the scintillator and the semiconductor serves as a link

  • 359.
    Dubaric, Ervin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Fröjdh, Christer
    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.
    Resolution and Noise Properties of Scintillator Coated X-ray Detectors2001In: 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. 178-182Article in journal (Refereed)
    Abstract [en]

    The imaging properties of X-ray pixel detectors depend on the quantum efficiency of X-rays, the generated signal of each X-ray photon and the distribution of the generated signal between pixels. In a scintillator coated device the signal is generated both by X-ray photons captured in the scintillator and by X-ray photons captured directly in the semiconductor. The Signal-to-Noise Ratio in the image is then a function of the number of photons captured in each of these processes and the yield, in terms of electron-hole pairs produced in the semiconductor, of each process. The spatial resolution is primarily determined by the light spreading within the scintillator. In a pure semiconductor detector the signal is generated by one process only. The Signal-to-Noise Ratio in the image is proportional to the number of X-ray photons captured within the sensitive layer. The spatial resolution is affected by the initial charge cloud generated in the semiconductor and any diffusion of carriers between the point of interaction and the readout electrode. In this paper we discuss the theory underlying the imaging properties of scintillator coated X-ray imaging detectors. The model is verified by simulations using MCNP and by experimental results. The results from the two-layer detector are compared with those from a pure semiconductor X-ray detector.

  • 360.
    Dubaric, Ervin
    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.
    Kackell, P
    The effect of different transport models in simulations of a 4H-SiC ultra short channel MOSFET1999In: Proceedings of International Conference on Microelectronics (ICM'99), 22-24 Nov. 1999 , Kuwait, 1999, p. 247-250Conference paper (Other academic)
  • 361.
    Dubaric, Ervin
    et al.
    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.
    Fröjdh, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Norlin, Börje
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Monte Carlo simulation of the response of a pixellated 3D photodetector in silicon2002In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 487, no 1-2, p. 136-141Article in journal (Refereed)
    Abstract [en]

    The charge transport and X-ray photon absorption in three-dimensional (3D) X-ray pixel detectors have been studied using numerical simulations. The charge transport has been modelled using the drift-diffusion simulator MEDICI, while photon absorption has been studied using MCNP. The response of the entire pixel detector system in terms of charge sharing, line spread function and modulation transfer function, has been simulated using a system level Monte Carlo simulation approach. A major part of the study is devoted to the effect of charge sharing on the energy resolution in 3D-pixel detectors. The 3D configuration was found to suppress charge sharing much better than conventional planar detectors.

  • 362.
    Dubaric, Ervin
    et al.
    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.
    Numerical modelling of the floating body enhanced breakdown in ultra small non-fully depleted SOI MOSFETs1999In: Physica scripta. T, ISSN 0281-1847, Vol. T79, p. 311-313Article in journal (Refereed)
  • 363.
    DuRussel II, Patrick
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Evaluation of Ant's wireless protocol for indoor navigation with RSSI2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Do we always have to be lost in the halls of a big school on an already stressful first day of class?

    This paper has evaluated a prototype indoor navigation system that uses a ANT wireless protocol. The protocol has been placed into nodes (small electrical devices, hardware) which are then placed around an area of interest (a map), like beacons, using RSSI (signal from the nodes) to help determine where the subject is located. The mobile application is made specific to Android with a search algorithm that is based off of vector analysis with weighted percentages. The idea being that if the position of each node is available, knowing the location between the nodes should be easily achievable. The nodes were build successfully along with an android application to verify each nodes functionally and see the nodes RSSI values. The algorithm works as expected but due to several factors was not able to be fully realized. In the actual test the system results where slow and did not update in real time. It was found that the ANT protocol does not have a fast packet reception when using the continuous scan feature made available by ANT.

    The results of the search algorithm were not good enough for a real time indoor navigation prototype. The search algorithm was slow. The system needs more inputs to accurately locate a subject indoors.

  • 364. Dutoit, B.
    et al.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Stavrev, S.
    Bi(2223) Ag Sheathed Tape Ic and Exponent n Characterization and Modelling under DC Applied Magnetic Field1999In: IEEE Transactions on Applied Superconductivity, ISSN 1051-8223, Vol. 9, no 2, p. 809-812Article in journal (Refereed)
  • 365. Dutoit, B.
    et al.
    Stavrev, S.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Bi(2223) Ag sheathed tape characterisation under DC applied magnetic field1998In: Proceedings of the Seventeenth International Cryogenic Engineering Conference: ICEC 17, Bristol, UK: IOP Publishing , 1998, p. 419-422Conference paper (Other scientific)
  • 366.
    Edblom, Hampus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Analys av reläskyddsinställningar för jordfelsskydd2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Well-adjusted relay protection for electrical substations is a necessity for personal safety and reliable operation. The aim of the report is to investigate whether non-directional protection with signaling alone is sufficient to protect the facility being investigated, and if directional protection has the advantage of improving fault detection, reducing the risk of unnecessary operation or reducing the function time. The facility under investigation is a 6.3 kV industrial network with resistance grounding. The report checks the insulation values and current tolerances for the equipment, which are then compared with calculated voltages and currents at single-phase earth faults. The report also briefly describes directional protection and its functions in relation to the issue of the potential benefit of directional protection. The result was that overvoltages due to earth faults are not a problem, but the fault current through the neutral point resistance is too large for signaling alone. In the case of earth faults with very low fault impedance, the neutral point resistance can handle the fault current for 30 seconds. After which the heat development results in the neutral point resistance being disconnected and the facility being isolated from the neutral point. According to the study, targeted protection is not needed in a facility like this. This is based on the fact that the cable paths are too short to cause capacitive currents large enough to cause unnecessary operation in non-directional protection, and that the network structure does not generate currents in unexpected directions. The result of the report shows that non-directional protection is sufficient, but that the operation function should be changed to tripping of faulty circuits

  • 367.
    Edrissi, Arian
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Styrsystem till avloppspumpstation: Vägledning vid val av automationsteknik2019Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this report the currently leading technologies for automation of sewage pump stations will be evaluated and compared. Based on this comparison a recommendation of a design will be done and the chosen control system will finally be assembled in a cabinet. The report shows that even thou there are energy savings to be done by using variable frequency drives it is rarely possible unless pumps are changed at the same time. When pumps are changed at the same time you have the opportunity to pick a pump that can handle the maximum inflow but at the same time have its best efficiency  point at lower speed. Pumps in sewage pump stations are often over dimensioned with regards to the most common inflow, lowering the speed will in this case result in lower efficiency and more losses. At one point the pump will not be able to overcome the static pressure in the system and will fail to produce any flow. Due to these reasons on/off control will be recommended which also is the most common method of today.

  • 368. Edvardsson, Sverker
    Molecular dynamics as a tool to calculating optical properties in rare-earth ion doped solids1993Doctoral thesis, monograph (Other academic)
  • 369.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Klintenberg, Mattias
    Role of the electrostatic model in calculating rare-earth crystal-field parameters1998In: Journal of alloys and compounds, ISSN 0925-8388, Vol. 275-277, p. 230-233Article in journal (Refereed)
  • 370.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Klintenberg, Mattias
    The use of CI calculated polarizabilities to study rare-earth CFP dependencies in the laser host RE:YLF1999In: Materials Science Forum, ISSN 0255-5476, Vol. 315/317, p. 407-414Article in journal (Refereed)
    Abstract [en]

    It has earlier been shown that the Sternheimer method is appropriate in deriving crystal field parameters (CFP) for Pr3+ and Nd3+ doped in YLF or Nd3+ in YAG. In this connection, the dipole (αD) and quadrupole (αQ) polarizabilities for the whole rare-earth (RE) series will be presented. These are needed for the self consistent lattice summations performed. The various rare-earth wavefunctions needed for the computations are derived from the well known relativistic full Hartree-Fock code by R. D. Cowan. The main CFP behaviour for the various RE dopants in YLF are seen to agree fairly well with the experimentally fitted parameters. Covalency effects are, as expected, observed to be more important for higher order parameters. It is also seen that the contribution to the crystal field due to covalency is approximately constant for a given Btp. This observation is also supported by calculations of Newman. The shielding, nuclear antishielding factors and radial integrals for the whole RE series are also presented.

  • 371.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Klintenberg, Mattias
    Thomas, John O.
    Use of polarized optical absorption to obtain structural information for Na1/Nd31 b9-alumina1996In: Physical Review B, Condensed matter, ISSN 0163-1829, Vol. 54, no 24, p. 17476-17 485Article in journal (Refereed)
    Abstract [en]

    Part of the optical absorption spectrum is calculated for the Nd31-doped Na1 b9-alumina using a moleculardynamics-~MD! based approach. The Judd/Ofelt ~J/O! theory is modified ~and several approximations removed! to treat polarized transition intensities for rare-earth ions in a solid host. Stark-level energies and eigenfunctions of the ground state ~4I9/2! and excited multiplets (4F3/2,2P1/2) are also calculated for the local environments involved. Energies and polarized transition intensities between individual Stark levels are thus calculated simultaneously for several hundreds of MD-generated environments; summation gives the total bandshape. A high proportion of Beevers-Ross-site occupation ~.50%! is indicated for low Nd31 concentrations in b9-alumina. The contrary is observed experimentally for high Nd31 concentrations, i.e., then midoxygen site occupation dominates. It is demonstrated that ions in different local environments contribute differently to the absorption spectrum and, particularly, how the polarization of the various transitions changes for ions occupying different sites. Temperature dependence aspects are also considered

  • 372.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Ning, Lixin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Åberg, D
    Lawrence Livermore National Laboratory, Livermore, CA 94551, USA .
    The connection between the dynamic intensity model and the vibronic intensity model for f-f transitions2006In: Journal of physics. B: Atomic, molecular and optical physics, ISSN 0953-4075, Vol. 39, no 9, p. 2127-2143Article in journal (Refereed)
    Abstract [en]

    In this paper we discuss intensity mechanisms of interest for rare-earth ions in optical materials. More specifically, we investigate the character of two models-first, a semi-classical dynamic intensity model, and second, a more traditional quantum mechanical vibronic intensity model. We focus on the case of f-f transitions and show that the predicted oscillator strengths then are the same under very reasonable approximations. We emphasize that this connection between the models cannot be made in the case of f-d transitions. The dynamic intensity model has an interesting classical interpretation. We show that it is very convenient to apply this approach together with classical dynamical techniques such as molecular dynamics simulation or the classical Monte Carlo method. The classical approach simplifies both the interpretation and calculation of vibronic oscillator strengths in complex systems. The concept of an effective temperature works as a bridge between the two models; so realistic predictions can be obtained even at low temperatures.

  • 373. Edvardsson, Sverker
    et al.
    Wolf, Mats
    Thomas, John O
    Sensitivity of optical absorption intensities for rare-earth ions1992In: Physical Review B, ISSN 0163-1829, Vol. 45, no 19, p. 10918-10923Article in journal (Refereed)
    Abstract [en]

    A technique is presented that uses molecular-dynamics simulation to generate the atomic positions needed to calculate the crystal-field parameters used in a Judd-Ofelt (JO) analysis. A slightly modified theory is used that permits analysis of both pi- and sigma-polarized absorption spectra. Different temperatures and ranges of calculation (up to 8 angstrom) around one rare-earth ion are used in the simulation of our test compound, Nd2O3. It is shown that as many of the surrounding ions as possible should be included in the calculations, and also that it is possible to probe the sensitivity of the different transitions in rare-earth-ion spectra. It is further shown that the behavior of the so-called hypersensitive transition for a rare-earth ion is a result of the sensitivity of the JO parameter OMEGA-2, which is proportional to the square of the electric field created by the surrounding ions.

  • 374. Edvardsson, Sverker
    et al.
    Wolf, Mats
    Thomas, John O.
    Flores, A
    Molecular dynamics simulation applied to the study of absorption spectra of Nd2031991In: The CP90 Europhysics Conference on Computational Physics : Amsterdam, the Netherlands, 10 - 13 September 1990 ; [proceedings]: Europhysics Conference on Computational Physics ; (Amsterdam) : 1990.09.10-13, Singapore: World Scientific , 1991, p. 560-Conference paper (Refereed)
  • 375.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Åberg, Daniel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    An atomic program for energy levels of equivalent electrons: lanthanides and actinides2001In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 133, no 2/3, p. 396-406Article in journal (Refereed)
    Abstract [en]

    A program written in C is presented to carry out brute force calculations in order to derive energy levels for an equivalent electronic configuration. Relativistic effects are partly neglected except for the spin-orbit interaction. Since the main relativistic effects are indirect, i.e. causing a contraction of the core which in turn causes the outer shells to expand, they are included to a high degree through the use of appropriate Slater integrals. The program is especially useful for primarily unfilled f-shells of the rare-earth or actinide ions. Modifications of the program to include spin−spin, spin−other orbit, Breit interaction etc. is straight forward. The program is also general in the sense that there is no need to find out or generate any Racah coefficients of fractional parentage. The complete energy matrix is diagonalized with all operators interacting simultaneously thus allowing mixing of all quantum numbers. This result in all energy eigenvalues and eigenvectors that in turn for example are partly responsible for the polarized dipole, quadrupole, … transitions within the unfilled shell. Free ion configuration interaction is accounted for through the use of standard CI operators. The Stark splitting can be studied via the standard crystal field Hamiltonian. Magnetic field influence on the energy levels may also be studied.

  • 376.
    Edvardsson, Sverker
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Åberg, Daniel
    Uppsala university.
    The energy matrix using determinantal product states applied to Ho:YAG2000In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 303-304, p. 280-284Article in journal (Refereed)
    Abstract [en]

    A program written in C is applied for calculations of energy levels and wavefunctions of the lanthanides or actinides. Standard non-relativistic phenomenological operators are used. Simple determinantal product states are used to form the basis set. The complete energy matrix is diagonalized with all operators interacting simultaneously thus allowing mixing of all quantum numbers. The crystal field splitting can also be studied via the standard crystal field hamiltonian as well as the magnetic field influence on the energy levels. The program is here applied to the technologically interesting trivalent ion holmium which is used to form extremely strong magnets as well as the medical eye-safe laser Ho:YAG. Both experimentally fitted and calculated self-consistent crystal field parameters are used to study the energy structure. Crystal ionic polarizabilities with electron correlation included are partly calculated. Zeeman split levels are also studied.

  • 377.
    Eggestig, Lars
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Wodajo, Mintesinot
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Integration of BankID Services in a PhoneGap Based Mobile Application2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Security concerns became high with the rapid technology advancement andwith the open nature of the internet. BankID is the leading electronic identificationsystem in Sweden which is used by around 5 million people in a variety ofpublic and private services. BankID allows users to securely authenticate themselvesand digitally sign important documents and transactions over the internet.In 2011, BankID Security App was launched to be used in mobile smartphones and tablet computers. In this paper, different components of the PublicKey Infrastructure (PKI) which is a cryptographic technique that enables usersto safely communicate over the insecure internet has been studied in detail. Furthermore,a test BankID-integrated PhoneGap based app on the Android platformis implemented and a performance evaluation and security analysis wereperformed. The test implementation of the BankID-integrated app on theAndroid platform provides user authentication and digital signing functions.The implemented backend system consists of a server with digital certificateand a database. The performance test emphasizes on the measurement of the accesstime between the components of the system and usability of the application.Access time measurement includes a reasonable amount of time in whichthe user is able to perform different activities in the system. In usability assessmentnumber of actions to perform a certain task and the ease of the user interfacehas been taken into consideration. The security analysis aims to identifypotential security flaws in the system and discuss possible solutions. The potentialsecurity risks we identified during the implementation of the system are theman-in-the-middle-attack, the Heartbleed bug, losing the mobile device andphysical access to the backend system. The potential security risks in the systemwere examined with regard to severity and probability of occurrence. Finally,the thesis project has been discussed in terms of the future work and system expansions.The result of the thesis will be used as a base in production developmentby Dewire, the company for which the thesis work has been conducted.

  • 378.
    Ehn, Sebastian
    et al.
    Tech Univ Munich, Phys Dept, Lehrstuhl Biomed Phys, James Franck Str, D-85748 Garching, Germany.
    Epple, Franz Michael
    Tech Univ Munich, Phys Dept, Lehrstuhl Biomed Phys, James Franck Str, D-85748 Garching, Germany.
    Fehringer, Andreas
    Tech Univ Munich, Phys Dept, Lehrstuhl Biomed Phys, James Franck Str, D-85748 Garching, Germany.
    Pennicard, David
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany.
    Graafsma, Heinz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany.
    Noel, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Biomed Phys, James Franck Str, D-85748 Garching, Germany.
    Pfeiffer, Franz
    Tech Univ Munich, Phys Dept, Lehrstuhl Biomed Phys, James Franck Str, D-85748 Garching, Germany.
    X-ray deconvolution microscopy2016In: Biomedical Optics Express, ISSN 2156-7085, E-ISSN 2156-7085, Vol. 7, no 4, p. 1227-1239Article in journal (Refereed)
    Abstract [en]

    Recent advances in single-photon-counting detectors are enabling the development of novel approaches to reach micrometer-scale resolution in x-ray imaging. One example of such a technology are the MEDIPIX3RX-based detectors, such as the LAMBDA which can be operated with a small pixel size in combination with real-time on-chip charge-sharing correction. This characteristic results in a close to ideal, box-like point spread function which we made use of in this study. The proposed method is based on raster-scanning the sample with sub-pixel sized steps in front of the detector. Subsequently, a deconvolution algorithm is employed to compensate for blurring introduced by the overlap of pixels with a well defined point spread function during the raster-scanning. The presented approach utilizes standard laboratory x-ray equipment while we report resolutions close to 10 mu m. The achieved resolution is shown to follow the relationship p/n with the pixel-size p of the detector and the number of raster-scanning steps n. (C) 2016 Optical Society of America

  • 379.
    Ekenberg, Love
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Danielson, Mats
    Dept. of Computer and Systems Sciences, Stockholm University.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sundgren, David
    Dept. of Computer and Systems Sciences, Stockholm University.
    Second-Order Risk Constraints in Decision Analysis2014In: Axioms, ISSN 2075-1680, Vol. 3, no 1, p. 31-45Article in journal (Refereed)
    Abstract [en]

    Recently, representations and methods aimed at analysing decision problems where probabilities and values (utilities) are associated with distributions over them (second-order representations) have been suggested. In this paper we present an approach to how imprecise information can be modelled by means of second-order distributions and how a risk evaluation process can be elaborated by integrating procedures for numerically imprecise probabilities and utilities. We discuss some shortcomings of the use of the principle of maximising the expected utility and of utility theory in general, and offer remedies by the introduction of supplementary decision rules based on a concept of risk constraints taking advantage of second-order distributions.

  • 380.
    Ekström, Marcus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Communication tool in virtual reality – A telepresence alternative: An alternative to telepresence – bringing the shared space to a virtual environment in virtual reality2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Videoconferencing is one of the most common telepresence methods today and educational videos is rising in popularity among distance learners. Traditional videoconferencing is unable to convey gestures and mutual eye contact between participants. This study aim to propose a Virtual Reality telepresence solution using game engines. A literature study confirmed the effectiveness achieved in VR is comparable to the effectiveness in face-to-face meetings. The suggested solution implements whiteboard functionality from a real-life perspective, confirming it is possible to include new functionality and directly transfer old functionality to the VR system from the communication systems today. The system was evaluated based on the response time, packet loss, bandwidth, frame rate and through user tests. The evaluation shows it is possible to design a telepresence system with VR capable of passing the Turing Test for Telepresence. The participants of the user tests did not experience discomfort and they were positively inclined to the telepresence system. Though, discomfort may emerge if the VR character is used with a common office workstation. Future studies in this topic would involve modifications of the third person camera, making the head's rotation follow the direction of the camera view and implementing movable eye pupils on the VR character using the upcoming eye-tracking accessory.

  • 381.
    Ekström, Rasmus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Smarta Elnät – En utredning: En utredning kring hur ett mindre energibolag kan utveckla sitt elnät till det smartare.2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The electricity network is in many places facing an eventful future where much will happen in a short period of time. Many network owners today have a network that is somewhat outdated and in short in need of upgrading and modernization, a modernization towards a smarter network. As the government sets new demands on the electricity meter of the future, Sweden's network owners are faced with a lot of other demands and challenges to be addressed. In this work, the definition of smart grids is investigated and how a small electricity grid should prioritize its investments and developments in its grid in a near future.Elnätsbranschen står på många punkter inför en händelserik framtid där mycket kommer att hända på kort tid. Många nätägare står idag med ett nät som är något föråldrat och inom kort i behov av en upprustning och modernisering, en modernisering mot ett smartare elnät. I takt med att regeringen ställer nya krav på framtidens elmätare så ställs Sveriges nätägare inför en hel del andra krav och utmaningar man måste ta itu med. I Detta arbete så undersöks definitionen av smarta elnät och hur en mindre elnätsägare bör prioritera sina investeringar och utvecklingar i sitt elnät i den närmaste framtiden.

  • 382.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Control of the Drying Section in a Paper Machine During a Web Break: Reglermöte 2004, Göteborg2004Conference paper (Other academic)
    Abstract [en]

    A new control strategy for steam pressure control in the drying cylinders during web breaks is presented. The development is performed using a new physical model implemented in Matlab Simulink. The goal of the control strategy is to obtain the same drying properties after the web break as before the break as fast as possible.

  • 383.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Dryer section control in paper machines during web2006In: 13th Nordic Process Control Workshop Köpenhamn 2006, 2006Conference paper (Other academic)
  • 384.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Dryer Section Control in Paper Machines During Web Breaks2004Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Web breaks in the dryer section of a paper machine cause loss of production and quality problems. After a web break, the steam pressure in the cylinders must be reduced to avoid overheating. The goal of this project is to determine optimal steam pressure trajectories during web breaks, so that the production is restarted with the same drying properties of the cylinder as before the break. A detailed physical dynamic model of the drying cylinder has been developed. The model describes the relations between the steam valve position, the steam pressure, the cylinder temperature, and the paper temperature. The model is based on partial differential equations that describe heat conductivity for the cylinder and the paper web, and mass balances of water and dry material in the paper. The accuracy of the model has been verified through experiments made at the M-real paper mill in Husum, Sweden. Verifications are made both during normal operation and during web breaks. The dynamic model has been reduced in order to derive simple transfer functions between the steam pressure and the cylinder temperature, and between a logic signal that is active during web breaks and the cylinder temperature, respectively. The transfer functions obtained were used to find the optimal steam pressure trajectory during web breaks. A new feed-forward strategy for steam pressure control during web breaks is presented. The strategy has been tested on a paper machine with good results. The strategy is built on feed-forward compensation and has been well received at the mill.

  • 385.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Steam Pressure Control During Web Breaks in the Paper Machine: Control Systems 2004, Quebec City, Canada2004Conference paper (Other academic)
    Abstract [en]

    A new control strategy for steam pressure control in the drying cylinders during web breaks is presented. The development is performed using a new physical model implemented in Simulink. The goal of the control strategy is that the cylinder temperatures are retained when the production is restarted after the web break.

  • 386.
    Ekvall, Jenny
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Hägglund, Tore
    Improved web break strategy using a new approach for steam pressure control in paper machines2008In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, no 10, p. 1151-1160Article in journal (Refereed)
    Abstract [en]

    This paper presents a new strategy for steam pressure control during web breaks in the paper machine. The aim was to restart paper production with the same drying properties of the cylinder as before the break. A detailed physical dynamic model of the drying cylinder has been developed. The accuracy of the model has been verified through experiments made at the M-real paper mill in Husum, Sweden. Verifications are made both during normal operation and during web breaks. The dynamic model has been reduced in order to derive simple transfer functions which were used to find the optimal steam pressure trajectory during web breaks. The resulting strategy has been tested on a paper machine with good results and it has been well received at the mill.

  • 387.
    El Amrani, Redouane
    et al.
    Reims Management School, University of Reims, France.
    Sarkar, Sumantra
    Georgia State University, CIS Department, J. Mack Robinson School of Business.
    Truex, Duane
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Examination of the Post-Implementation Role of Competency Centers in ERP and BI: An International/Cross Cultural Investigation2010Conference paper (Refereed)
    Abstract [en]

    This study in progress paper describes a research program studying the role of ERP and BI competency centers (CC) in a range of firms from six countries in Europe, North America and Austral-Asia. The goal of this research is to understand the relative contribution of CC in improving IS and business unit performance and to map structures and models of extant successful competency centers worldwide. We deploy a mixed-method design combining qualitative and quantitative approaches appropriate to descriptive and exploratory research.

  • 388.
    Eldefrawy, Mohamed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Butun, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Pereira, Nuno
    Polytechnic of Porto (IPP), Porto, Portugal.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Formal security analysis of LoRaWAN2019In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 148, p. 328-339Article in journal (Refereed)
    Abstract [en]

    Recent Low Power Wide Area Networks (LPWAN) protocols are receiving increased attention from industry and academia to offer accessibility for Internet of Things (IoT) connected remote sensors and actuators. In this work, we present a formal study of LoRaWAN security, an increasingly popular technology, which defines the structure and operation of LPWAN networks based on the LoRa physical layer. There are previously known security vulnerabilities in LoRaWAN that lead to the proposal of several improvements, some already incorporated into the latest protocol specification. Our analysis of LoRaWAN security uses Scyther, a formal security analysis tool and focuses on the key exchange portion of versions 1.0 (released in 2015) and 1.1 (the latest, released in 2017). For version 1.0, which is still the most widely deployed version of LoRaWAN, we show that our formal model allowed to uncover weaknesses that can be related to previously reported vulnerabilities. Our model did not find weaknesses in the latest version of the protocol (v1.1), and we discuss what this means in practice for the security of LoRaWAN as well as important aspects of our model and tools employed that should be considered. The Scyther model developed provides realistic models for LoRaWAN v1.0 and v1.1 that can be used and extended to formally analyze, inspect, and explore the security features of the protocols. This, in turn, can clarify the methodology for achieving secrecy, integrity, and authentication for designers and developers interested in these LPWAN standards. We believe that our model and discussion of the protocols security properties are beneficial for both researchers and practitioners. To the best of our knowledge, this is the first work that presents a formal security analysis of LoRaWAN.

  • 389.
    Eldefrawy, Mohamed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. Halmstad Högskola.
    Ferrari, Nico
    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.
    Dynamic User Authentication Protocol for Industrial IoT without Timestamping2019In: 2019 15th IEEE International Workshop on Factory Communication Systems (WFCS), IEEE, 2019, article id 8757984Conference paper (Refereed)
    Abstract [en]

    Internet of Things (IoT) technology has succeed ingetting a great attention in the industry where it has been ableand still can solve many industrial intractable issues. The emergingtechnology is suffering from severe security shortcomings.Authentication is a cornerstone of IoT security as it presents the measures of checking the legitimacy of communication’s entities.The Industrial IoT (IIoT) technology has special conditions, resulting from a lack of resources and a shortage of security skills. As far as we can tell, from the literature, IIoT user authentication has not been studied extensively. In 2017 Tai et al. presented an authenticated key agreement for IoT networks. Here we prove that Tai et al. is susceptible to sever security weaknesses, such as;i. stolen smart card attack, ii. unknown key share attack, iii. node capturing attack. In this research article, we offer an innovative IIoT user authentication scheme that can achieve secure remote user authentication without timestamping that requires precise synchronization, it only needs Hashing and Xor-ing. We examine the efficiency of our presented scheme using Tmote Sky node over an MSP430 microcontroller using COOJA simulator as well aswe show its correctness using Scyther verification tool.

  • 390.
    Eldefrawy, Mohamed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Pereira, Nuno
    The Polytechnic of Porto (IPP), Portugal.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Key Distribution Protocol for Industrial Internet of Things without Implicit Certificates2019In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 6, no 1, p. 906-917Article in journal (Refereed)
    Abstract [en]

    The deployment of the Internet of Things (IoT) in industry, called the Industrial IoT (IIoT), is supporting the introduction of very desirable improvements such as increasing production flexibility, self-organization and real-time and quick response to events. However, security and privacy challenges are still to be well addressed. The IIoT requires different properties to achieve secure and reliable systems and these requirements create extra challenges considering the limited processing and communication power available to IIoT field devices. In this research article, we present a key distribution protocol for IIoT that is computationally and communicationally lightweight (requires a single message exchange) and handles node addition and revocation, as well as fast re-keying. The scheme can also resist the consequences of node capture attacks (we assume that captured nodes can be detected by the Gateway and previous works have shown this assumption to be acceptable in practice), server impersonation attacks and provides forward/backward secrecy. We show formally the correctness of our protocol and evaluate its energy consumption under realistic scenarios using a real embedded platform compared to previous state-of-the-art key-exchange protocols, to show our protocol reliability for IIoT.

  • 391.
    Eliassi Sarzali, Sohran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design and Implementation of Circle Fitting on Largely Incomplete Circular Objects2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In many applications, e.g. medical, industrial and military systems, it is of interest to fit a circle to scattered data points belonging to a complete or incomplete circular arc. As an example, circle fitting can be applied in the industry, for quality control, when investigation is required to verify if a manufactured circular object has the desired radius or not. A variety of methods have been developed to handle the circle fitting problem. Some methods are relatively complex and provide more accurate circle fitting, whereas some are simple and fast but lacks accuracy. Furthermore, some methods handle circle fitting better on incomplete circular objects. However, for practical machine vision implementations, there seems to be a lack of study when it comes to circle fitting on largely incomplete circular arcs. Largely incomplete circular arcs refer to short arcs having corresponding angles of few degrees, e.g. less than 10°. Hence, this thesis deals with design and implementation of circle fitting on largely incomplete circular objects. The goal is to investigate the shortest circular arc, i.e. the shortest possible angle that, can be fitted to a circle with an accuracy of at least 98%.

    The approach includes studying related work, developing a vision based algorithm for circle fitting on incomplete circular objects and conducting experiments using live stream 2D images.

    We designed and implemented an algorithm, based on a circle fitting algorithm, called Hyper fit. Our experimental set-up, with a 5-Megapixel camera, showed that it is possible to fit a circle, with an accuracy of 98%, to a short circular arc with an angle of only 1.95° of a complete circle. 1.95° corresponds to 0.54% of a complete circles circumference. Results showed that, using a high-resolution camera, it is possible to fit accurate circles on largely incomplete circular arcs. Moreover, the implementation achieved the real-time requirement, as it could process at least 3 fps (frames per second).

  • 392.
    Elvinsson, David
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Analoghantering i Siemens Open Library: Modifiering och jämförelse2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Higher expectations on sustainability, safety and ergonomics, sets higher demands on an increasing number of areas, including PLC- and HMI-programming. The purpose of this work has been to modify an analog input block with associated faceplate and faceplate icon from Siemens Open Library. A comparsion has been made between the different types of programming, according to such aspects as; safety, sustainability, cycle-time, visual aspects and ergonomics. The programmings have also been compared to two different standards; SSG 5262 and ISO 13849-1. The aim with this thesis work has been to examine how an increased functionality can affect other aspects, such as ergonomics, cycle-time, safety and sustainability. PLC:s, a type of programmable computer, can only read bit patterns and for to be able to read analog signals, the PLC needs an AD-converter. PLC:s from Siemens convert the signal to a resolution of 16 bit and also provides error code when the input signal is too high or too low. With communication between humans and machines, some form of interface is needed and the open source library ”Open Library” from Siemens, provides such interfaces in the form of faceplates. In the library, there are functions that are already programmed, motor control beeing one of them. The program code was written in the FBD language and the standard IEC 61131-3 describes the structure of this and other languages used for PLC programming. After a litterature study on the subject, an implementation of new functions was made, according to requests from the company ÅF-consult. The new functions that were programmed were; a hysteresis function for alarm boundaries, filter function with damping, graphic representation of the filtered signal, display of trend curves, sensor type and help window in the faceplate. A logging function was also programmed, with a button that saved input values in a datablock. The cycle-time was measured to somewhat longer than one millisecond for an average cycle-time for each PLC-block. The longest cycle-time for the original block was 72.892 milliseconds and the longest for the modification was 158.174 milliseconds. The faceplate was made about 90 percent larger, to accomodate the new functions. The colors and the text sizes, were edited to better match the guidelines written in SSG 5262. The original faceplate has smaller text sizes and different colors on process values, than advocated by SSG 5262. Neither of the programmings is completely according to ISO 13849-1, even if they contain safety-related functions. With regards to visual- and ergonomical aspects, both the original and the modified faceplate could be said to be ”pleasant for the eyes”, with few colors. From an ergonomic view the modification can be viewed as somewhat better because of larger text sizes and standardized process value colors. From a sustainability- and ethical perspective, it is difficult to determine which programming is best, because more functions can give longer cycle-times and thereby eventually higher energy consumption, but can give value in the form of time-savings and possibly money-savings.

  • 393.
    Emil, Estlind
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    PLC Lab Station: Solution for Automatic Unloading of Paper Reels2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Automatic control of processes is a field that has evolved extensively over theyears to reduce downtime, improve quality and increase the productivity ofprocesses in manufacturing industries. ÅF Consult is a consult organization thatprovides industrial solutions worldwide. In order to test equipment andintroduce employees and students to control systems, a PLC based lab station isnecessary. The methodology used in the project is based on a literature study,followed by the solution approach and finally an evaluation. A DistributedControl System setup using a Siemens S7-300 and a Siemens S7-400 PLC hasbeen developed. The PLCs communicate using PROFIBUS DP. The station isdivided into two major parts: a conveyor belt with transportation functionalityand a robotic arm with pick-and-place functionality. The station is providedwith equipment similar to systems currently used in paper and pulp industries.Existing solutions for unloading of paper reels in the paper and pulp industriesare non-universal due to extra equipment like pre-installed rails in trailers. Anautomated solution for unloading using a robotic arm is therefore presented,designed to reduce paper reel handling and to have the possibility to unload toany trailer. The lab station is implemented according to ÅF Consults demandsof a portable, field related station. The low budget resulted in cheap equipmentthat lack accuracy, mainly resulting in issues relating to the ability to control therobotic arm properly. The unloading solution is emulated as a lab task on thestation, showing that a control setup similar to the lab station would be a goodapproach for a real implementation solution.

  • 394.
    Engelke, U.
    et al.
    Commonwealth Scientific and Industrial Research Organisation (CSIRO), Hobart, Australia.
    Darcy, D.P.
    Dolby Laboratories, San Francisco, USA.
    Mulliken, G.H.
    Dolby Laboratories, San Francisco, USA.
    Bosse, S.
    Fraunhofer Institute for Telecommunications, Berlin, Germany.
    Martini, M.G.
    Kingston University, London, UK.
    Arndt, S.
    Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Antons, J.-N.
    Technische Universiat Berlin, Germany.
    Chan, K.Y.
    Curtin University, Perth, Australia.
    Ramzan, N.
    University of the West of Scotland, Hamilton, UK.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. Acreo Swedish ICT AB.
    Psychophysiology-based QoE Assessment: A Survey2017In: IEEE Journal on Selected Topics in Signal Processing, ISSN 1932-4553, E-ISSN 1941-0484, Vol. 11, no 1, p. 6-21, article id 7569001Article in journal (Refereed)
    Abstract [en]

    We present a survey of psychophysiology-based assessment for Quality of Experience (QoE) in advanced multimedia technologies. We provide a classification of methods relevant toQoE and describe related psychological processes, experimental design considerations, and signal analysis techniques. We summarise multimodal techniques and discuss several important aspects of psychophysiology-based QoE assessment, including the synergies with psychophysical assessment and the need for standardised experimental design. This survey is not considered to be exhaustive but serves as a guideline for those interested to further explore this emerging field of research.

  • 395.
    Engholm, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Materials optimization for optical fiber amplifiers and fiber lasers2008Doctoral thesis, comprehensive summary (Other scientific)
  • 396.
    Engholm, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Hammarling, Krister
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Andersson, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sandberg, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. RISE Acreo.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    A Bio-Compatible Fiber Optic pH Sensor Based on a Thin Core Interferometric Technique2019In: Photonics, ISSN 2304-6732, Vol. 6, no 1, article id 11Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for compact, reliable and versatile sensor concepts for pH-level monitoring within several industrial, chemical as well as bio-medical applications. Many pHsensors concepts have been proposed, however, there is still a need for improved sensor solutionswith respect to reliability, durability and miniaturization but also for multiparameter sensing. Here wepresent a conceptual verification, which includes theoretical simulations as well as experimentalevaluation of a fiber optic pH-sensor based on a bio-compatible pH sensitive material not previouslyused in this context. The fiber optic sensor is based on a Mach-Zehnder interferometric technique,where the pH sensitive material is coated on a short, typically 20-25 mm thin core fiber splicedbetween two standard single mode fibers. The working principle of the sensor is simulated by usingCOMSOL Multiphysics. The simulations are used as a guideline for the construction of the sensorsthat have been experimentally evaluated in different liquids with pH ranging from 1.95 to 11.89. The results are promising, showing the potential for the development of bio-compatible fiber optic pH sensor with short response time, high sensitivity and broad measurement range. The developedsensor concept can find future use in many medical- or bio-chemical applications as well as inenvironmental monitoring of large areas. Challenges encountered during the sensor developmentdue to variation in the design parameters are discussed.

  • 397.
    Engholm, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lashgari, K.
    Edvardsson, Sverker
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Westin, G.
    Norin, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Atomically designed precursors in optical fiber amplifiers: The thermal stability of the heteroimetallic ErAl_3(OPri)_12 in a solution-coated silica soot2005In: Journal of Applied Physics, ISSN 0021-8979, Vol. 97, no 11, p. 113104-Article in journal (Refereed)
  • 398.
    Engholm, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Norin, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Comment on:"Photodarkeningin Yb-doped aluminosilicate fiber induced by 488nm irradiation"2007In: Optical Letter, ISSN 0146-9592, Vol. 33, no 11, p. 1216.-Article in journal (Refereed)
    Abstract [en]

    We present some strong evidence against the assignment of an ytterbium-related oxygen deficiency center (ODC) near 230 nm in Yb-doped aluminosilicate glass in the Letter by Yoo

  • 399.
    Engholm, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Norin, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Divalent Ytterbium in Ytterbium Doped Aluminosilicate Glass - Aspects on Photodarkening in Fiber Lasers2007In: 2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5, New York: IEEE conference proceedings, 2007, p. 1902-1903Conference paper (Refereed)
    Abstract [en]

    We show that divalent ytterbium ions are present in ytterbium doped aluminosilicate glass. The presence of Yb^2+-ions may influence the formation of induced color centers in ytterbium doped fiber lasers leading to reduced performance.

  • 400.
    Engholm, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Norin, Lars
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Materials optimization for ytterbium-doped high power fiber lasers2008In: 2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9, New York: IEEE conference proceedings, 2008, p. 232-233Conference paper (Refereed)
    Abstract [en]

    In this paper we will present paths to reduce the extent of photodarkening in ytterbium. doped fiber lasers based on the aluminosilicate glass matrix. This will enable higher powers and longer operating lifetimes.

567891011 351 - 400 of 1605
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