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  • 1.
    Ahmad, Jawad
    et al.
    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.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Screen Printed Piezoresistive Sensors for Monitoring Pressure Distribution in Wheelchair2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748Article in journal (Refereed)
    Abstract [en]

    Prolonged sitting inadequacies cause pressure ulcer to many individuals, especially to disadvantaged with reduced mobility. The measurement of distributed pressure and detection of irregular sitting postures is essential for preventing the risk of developing pressure ulcer. In this paper, a pressure sensing system capable of recognizing sitting postures by means of measuring interface pressure through printed pressure sensors is presented. A thin and flexible large area sensor is screen-printed using silver flake and carbon particle inks and comprises 16 sensing elements. For the evaluation of practical usability, the sensor characterization is carried out by conducting stability, repeatability, drift and bending tests. The performance of the sensor is checked under varying environmental conditions. Sitting posture detection accuracy above 80 % is achieved using a classification algorithm for four different sitting postures. Pressure distribution is monitored at a scanning rate of 10 Hz. A low power and small form factor of read-out electronics enables a compact packaging inside the seat cushion. The presented sensor design targets smart wheelchairs, but it is extendable to much larger areas, for example to be used in beds. The proposed sensing system would be of a great assistance for caregivers and health professionals.

  • 2.
    Ahmad, Jawad
    et al.
    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.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Sitting Posture Recognition using Screen Printed Large Area Pressure Sensors2017In: Proceedings of IEEE Sensors, IEEE, 2017, p. 232-234Conference paper (Refereed)
    Abstract [en]

    In the biomedical sector, pressure sensors exhibit an important role towards monitoring and recognition of sitting posture for wheelchair users, which is helpful for pressure ulcer prevention and cure.  In this paper, a flexible and inexpensive screen printed large area pressure sensing system is presented. The large area sensor comprise three layers, is able to cancel-out false pressure detection, and achieves a sitting classification accuracy over 80 percent. The sensor matrix contains 16 sensors distributed over an area of 23.5 cm × 21.5 cm and the pressure points are monitored at a scanning rate of 77 Hz. The sensor system provides wireless communication and a Windows based GUI is developed that allows real-time presentation of pressure data by means of a pressure map. The presented sensor design targets smart wheelchairs but is suitable for any low cost and high throughput pressure distribution monitoring systems. 

  • 3.
    Ahmad, Nisar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design and Implementation of a High Frequency Flyback Converter2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The power supply designers choose flyback topology due to its promising features of design simplicity, cost effectiveness and multiple outputs handling capability. The designed product based on flyback topology should be smaller in size, cost effective and energy efficient. Similarly, designers focus on reducing the circuit losses while operating at high frequencies that affect the converter efficiency and performance. Based on the above circumstances, an energy efficient open loop high frequency flyback converter is designed and operated in MHz frequency region using step down multilayer PCB planar transformer. The maximum efficiency of 84.75% is observed and maximum output power level reached is 22.8W. To overcome the switching losses, quasi-resonant soft switching technique is adopted and a high voltage CoolMOS power transistor is used.

  • 4.
    Ahonen, Mikko
    et al.
    Institute of Environmental Health and Safety, Tallinn, Estonia.
    Koppel, Tarmo
    Tallinn University of Technology, Estonia.
    Voltage transients measurements and power line communication2016In: 2016 57th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), IEEE, 2016, p. 1-4Conference paper (Refereed)
    Abstract [en]

    Power line communication (PLC) connects energy producers with energy consumers. In the European Union stricter guidelines are under development to limit disturbances in the 2-150 kHz frequency range, because devices utilising PLC do not work. This study measured voltage transients in 22 locations and identified sources for noise. Home environments and public buildings were measured. Measurements were conducted in the frequency range of 150 kHz-500 kHz (according to EN 55011 to EN 55022) and in the lower frequency range of 3 kHz to 95 kHz. Results indicate that voltage transients are generated mostly by switching mode power supplies, pumps, rectifiers, inverters and even low quality smart meters. Several of these devices exceeded PLC standard level, 122 dBμV. Additionally we demonstrate that basic power quality recordings do not provide enough information to mitigate PLC problems occurring within microseconds and frequency specific voltage transient measurements are needed.

  • 5.
    Alfredsson, Jon
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Aunet, Snorre
    Department of Informatics, University of Oslo.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Basic Speed and Power Properties of Digital Floating-gate Circuits Operating in Subthreshold2005In: Proceedings of IFIP VLSI-SOC 2005: International Conference on Very Large Scale Integration, Edith Cowan Univ , 2005, p. 229-232Conference paper (Refereed)
    Abstract [en]

    For digital circuits with ultra-low power consumption,floating-gate circuits have been considered to be a techniquepotentially better than standard static CMOS circuits.By having a DC offset on the floating gates, theeffective threshold voltage of the floating-gate transistoris adjusted and the speed and power performance can bealtered. In this paper the basic performance related propertiessuch as power, delay, power-delay product (PDP),and energy-delay product (EDP) for floating-gate circuitsoperating in subthreshold are investigated. Based on circuitsimulations in a 120nm process technology, it isshown that for the best case, the power can be reducedapproximately by one order of magnitude at the expenseof increased delay, while the PDP is more or less constantin comparison to static CMOS. The EDP can be reducedby two orders of magnitude at the expense of reducednoise margins.

  • 6.
    Alqaysi, Hiba
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Fedorov, Igor
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Evaluating Coverage Effectiveness of Multi-Camera Domes Placement for Volumetric Surveillance2017In: ICDSC 2017 Proceedings of the 11th International Conference on Distributed Smart Cameras, New York, NY, USA: Association for Computing Machinery (ACM), 2017, Vol. F132201, p. 49-54Conference paper (Refereed)
    Abstract [en]

    Multi-camera dome is composed of a number of cameras arranged to monitor a half sphere of the sky. Designing a network of multi-camera domes can be used to monitor flying activities in open large area, such as birds' activities in wind parks. In this paper, we present a method for evaluating the coverage effectiveness of the multi-camera domes placement in such areas. We used GPS trajectories of free flying birds over an area of 9 km2 to analyze coverage effectiveness of randomly placed domes. The analysis is based on three criteria namely, detection, positioning and the maximum resolution captured. The developed method can be used to evaluate results of designing and optimizing dome placement algorithms for volumetric monitoring systems in order to achieve maximum coverage.

  • 7.
    Ambatipudi, Radhika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    High Frequency (MHz) Planar Transformers for Next Generation Switch Mode Power Supplies2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increasing the power density of power electronic converters while reducing or maintaining the same cost, offers a higher potential to meet the current trend inrelation to various power electronic applications. High power density converters can be achieved by increasing the switching frequency, due to which the bulkiest parts, such as transformer, inductors and the capacitor's size in the convertercircuit can be drastically reduced. In this regard, highly integrated planar magnetics are considered as an effective approach compared to the conventional wire wound transformers in modern switch mode power supplies (SMPS). However, as the operating frequency of the transformers increase from several hundred kHz to MHz, numerous problems arise such as skin and proximity effects due to the induced eddy currents in the windings, leakage inductance and unbalanced magnetic flux distribution. In addition to this, the core losses whichare functional dependent on frequency gets elevated as the operating frequency increases. Therefore, this thesis provides an insight towards the problems related to the high frequency magnetics and proposes a solution with regards to different aspects in relation to designing high power density, energy efficient transformers.The first part of the thesis concentrates on the investigation of high power density and highly energy efficient coreless printed circuit board (PCB) step-down transformers useful for stringent height DC-DC converter applications, where the core losses are being completely eliminated. These transformers also maintain the advantages offered by existing core based transformers such as, high coupling coefficient, sufficient input impedance, high energy efficiency and wide frequencyband width with the assistance of a resonant technique. In this regard, several coreless PCB step down transformers of different turn’s ratio for power transfer applications have been designed and evaluated. The designed multilayered coreless PCB transformers for telecom and PoE applications of 8,15 and 30W show that the volume reduction of approximately 40 - 90% is possible when compared to its existing core based counterparts while maintaining the energy efficiency of the transformers in the range of 90 - 97%. The estimation of EMI emissions from the designed transformers for the given power transfer application proves that the amount of radiated EMI from a multilayered transformer is lessthan that of the two layered transformer because of the decreased radius for thesame amount of inductance.The design guidelines for the multilayered coreless PCB step-down transformer for the given power transfer application has been proposed. The designed transformer of 10mm radius has been characterized up to the power level of 50Wand possesses a record power density of 107W/cm3 with a peak energy efficiency of 96%. In addition to this, the design guidelines of the signal transformer fordriving the high side MOSFET in double ended converter topologies have been proposed. The measured power consumption of the high side gate drive circuitvitogether with the designed signal transformer is 0.37W. Both these signal andpower transformers have been successfully implemented in a resonant converter topology in the switching frequency range of 2.4 – 2.75MHz for the maximum load power of 34.5W resulting in the peak energy efficiency of converter as 86.5%.This thesis also investigates the indirect effect of the dielectric laminate on the magnetic field intensity and current density distribution in the planar power transformers with the assistance of finite element analysis (FEA). The significanceof the high frequency dielectric laminate compared to FR-4 laminate in terms of energy efficiency of planar power transformers in MHz frequency region is also explored.The investigations were also conducted on different winding strategies such as conventional solid winding and the parallel winding strategies, which play an important role in the design and development of a high frequency transformer and suggested a better choice in the case of transformers operating in the MHz frequency region.In the second part of the thesis, a novel planar power transformer with hybrid core structure has been designed and evaluated in the MHz frequency region. The design guidelines of the energy efficient high frequency planar power transformerfor the given power transfer application have been proposed. The designed corebased planar transformer has been characterized up to the power level of 50W and possess a power density of 47W/cm3 with maximum energy efficiency of 97%. This transformer has been evaluated successfully in the resonant converter topology within the switching frequency range of 3 – 4.5MHz. The peak energy efficiency ofthe converter is reported to be 92% and the converter has been tested for the maximum power level of 45W, which is suitable for consumer applications such as laptop adapters. In addition to this, a record power density transformer has been designed with a custom made pot core and has been characterized in thefrequency range of 1 - 10MHz. The power density of this custom core transformer operating at 6.78MHz frequency is 67W/cm3 and with the peak energy efficiency of 98%.In conclusion, the research in this dissertation proposed a solution for obtaining high power density converters by designing the highly integrated, high frequency(1 - 10MHz) coreless and core based planar magnetics with energy efficiencies inthe range of 92 - 97%. This solution together with the latest semiconductor GaN/SiC switching devices provides an excellent choice to meet the requirements of the next generation ultra flat low profile switch mode power supplies (SMPS).

  • 8.
    Ambatipudi, Radhika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Multilayered Coreless Printed Circuit Board (PCB) Step-down Transformers for High Frequency Switch Mode Power Supplies (SMPS)2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Power Supply Unit (PSU) plays a vital role in almost all electronic equipment. The continuous efforts applied to the improvement of semiconductor devices such as MOSFETS, diodes, controllers and MOSFET drivers have led to the increased switching speeds of power supplies. By increasing the switching frequency of the converter, the size of passive elements such as inductors, transformers and capacitors can be reduced. Hence, the high frequency transformer has become the backbone in isolated AC/DC and DC/DC converters. The main features of transformers are to provide isolation for safety purpose, multiple outputs such as in telecom applications, to build step down/step up converters and so on. The core based transformers, when operated at higher frequencies, do have limitations such as core losses which are proportional to the operating frequency. Even though the core materials are available in a few MHz frequency regions, because of the copper losses in the windings of the transformers those which are commercially available were limited from a few hundred kHz to 1MHz. The skin and proximity effects because of induced eddy currents act as major drawbacks while operating these transformers at higher frequencies. Therefore, it is necessary to mitigate these core losses, skin and proximity effects while operating the transformers at very high frequencies. This can be achieved by eliminating the magnetic cores of transformers and by introducing a proper winding structure.

    A new multi-layered coreless printed circuit board (PCB) step down transformer for power transfer applications has been designed and this maintains the advantages offered by existing core based transformers such as, high voltage gain, high coupling coefficient, sufficient input impedance and high energy efficiency with the assistance of a resonant technique. In addition, different winding structures have been studied and analysed for higher step down ratios in order to reduce copper losses in the windings and to achieve a higher coupling coefficient. The advantage of increasing the layer for the given power transfer application in terms of the coupling coefficient, resistance and energy efficiency has been reported. The maximum energy efficiency of the designed three layered transformers was found to be within the range of 90%-97% for power transfer applications operated in a few MHz frequency regions. The designed multi-layered coreless PCB transformers for given power applications of 8, 15 and 30W show that the volume reduction of approximately 40-90% is possible when compared to its existing core based counterparts. The estimation of EMI emissions from the designed transformers proves that the amount of radiated EMI from a three layered transformer is less than that of the two layered transformer because of the decreased radius for the same amount of inductance.

    Multi-layered coreless PCB gate drive transformers were designed for signal transfer applications and have successfully driven the double ended topologies such as the half bridge, the two switch flyback converter and resonant converters with low gate drive power consumption of about half a watt. The performance characteristics of these transformers have also been evaluated using the high frequency magnetic material made up of NiZn and operated in the 2-4MHz frequency region.

    These multi-layered coreless PCB power and signal transformers together with the latest semiconductor switching devices such as SiC and GaN MOSFETs and the SiC schottky diode are an excellent choice for the next generation compact SMPS.

  • 9.
    Ambatipudi, Radhika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kotte, Hari Babu
    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.
    Comparison of Two Layered and Three Layered Coreless Printed Circuit Board Step-Down Power Transformers2011In: 2011 INTERNATIONAL CONFERENCE ON INSTRUMENTATION, MEASUREMENT, CIRCUITS AND SYSTEMS (ICIMCS 2011), VOL 2: FUTURE COMMUNICATION AND NETWORKING, Shenzhen: IEEE conference proceedings, 2011, p. 59-62Conference paper (Refereed)
    Abstract [en]

    In this paper the comparative results of two layered and three layered coreless Printed Circuit Board (PCB) step down 2:1 power transformers operating in MHz frequency were addressed. The  two different step down transformers approximately having same self inductances, one in two layer and the other in three layer were designed and evaluated for the given power transfer application. The performance characteristics of these transformers under similar conditions were measured and the comparative parameters of these transformers in terms of their resistances, self, leakage, mutual inductances, and coupling coefficient are analyzed. For the given output power, the measured energy efficiency of the three layered transformer is improved by 3% and the area is reduced by 32% compared to two layered transformer. The efficiency of the three layered transformer is 94.5% approximately for an output power level of 25W at an operating frequency of 2.5MHz

  • 10.
    Ambatipudi, Radhika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kotte, Hari Babu
    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.
    Coreless Printed Circuit Board (PCB) StepdownTransformers for DC-DC ConverterApplications2010In: PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, ISSUE 70, OCTOBER 2010, ISSN:1307-6892, France: World Academy of Science Engineering and Technology , 2010, p. 380-389Conference paper (Refereed)
    Abstract [en]

    In this paper, multilayered coreless printed circuit board (PCB) step-down power transformers for DC-DC converter applications have been designed, manufactured and evaluated. A set of two different circular spiral step-down transformers were fabricated in the four layered PCB. These transformers have been modelled with the assistance of high frequency equivalent circuit and characterized with both sinusoidal and square wave excitation. This paper provides the comparative results of these two different transformers in te rms of their resistances, self, leakage, mutual inductances, coupling coefficient and also their energy efficiencies. The operating regions for optimal performance of these transformers for power transfer applications are determined. These transformers were tested for the output power levels of about 30 Watts within the input voltage range of 12-50 Vrms. The energy efficiency for these step down transformers is observed to be in the range of 90%-97% in MHz frequency region.

  • 11.
    Ambatipudi, Radhika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kotte, Hari Babu
    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.
    Effect of Air Gap on the Performance of Hybrid Planar Power Transformer in High Frequency (MHz) Switch Mode Power Supplies (SMPS)2012In: Proceedings of INDUCTICA 2012, Coil Winding, Insulation and Electrical Manufacturing International Conference and Exhibition (CWIEME), Berlin, Germany 26-28 June 2012, 2012Conference paper (Refereed)
    Abstract [en]

    A half bridge transformer with novel winding strategy was designed and tested up to the output power level of 50W with a maximum energy efficiency of 98% in 1-6 MHz frequency region. In this paper, the effect of air gap on the performance of the designed transformer for high frequency (MHz) Switch Mode Power Supplies (SMPS) was studied and analyzed. The air gap of the transformer was varied from 0 – 2mm and the effect on self, leakage, mutual inductances, coupling coefficient and power transfer capability was recorded in 1 - 6MHz. The parameters of the transformer with different air gaps were extracted using network analyzer. The transformer was excited with sinusoidal voltages using power amplifier and the performance characteristics such as input impedance, power transfer capability and hence the energy efficiency was measured. At a particular operating frequency of 3MHz, the maximum power transferred for the given excitation voltage with 0mm air gap was found to be 22W whereas it is only 8W with the 2mm air gap . The measured energy efficiency of the transformer at 3MHz with 0mm and 2mm air gap was found to be 93% and 79% respectively. With this study, for the given power transfer application, at a particular high frequency operation of converter, an optimum air gap without sacrificing the energy efficiency and core saturation was proposed

  • 12.
    Ambatipudi, Radhika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kotte, Hari Babu
    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.
    Effect of Dielectric Material on the Performance of Planar Power Transformers in MHz Frequency Region2012In: Proceedings of INDUCTICA 2012, Coil Winding, Insulation and Electrical Manufacturing International Conference and Exhibition (CWIEME), Berlin, Germany 26-28 June 2012, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper, the effect of two different dielectric materials in planar printed circuit board (PCB) transformers applicable for power transfer applications in MHz frequency region is discussed. The 2-D model of the planar transformer was developed and the effect of the dielectric material on the magnetic field and the current distribution in the transformer was analyzed. Based on the FEA analysis, the power transformers of two different dielectric materials were designed, manufactured and characterized by using ‘S’ parameters obtained from network analyzer in order to determine the performance of dielectrics at high frequencies. The electrical parameters such as inductances, capacitances and resistances of the transformers were obtained and the changes in these parameters with the variation of the dielectric material were analyzed in the MHz frequency. This paper discusses the effect of dielectric material on the magnetic field distribution and the current density which results in the variation of the coupling coefficient and the eddy current losses of the transformer. By changing the dielectric material from a traditional FR-4 to a Rogers, the coupling coefficient was improved by a maximum of 5% and the copper losses of transformer were also decreased in the MHz frequency region. The power gain/energy efficiency obtained from the network analyzer with a resonant capacitor is verified with those obtained using a power amplifier and the simulations. An overall energy efficiency improvement of about 2-5% was achieved with a Rogers’s material in MHz frequency region compared to traditional FR-4 laminate.

     

  • 13.
    Ambatipudi, Radhika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Kotte, Hari Babu
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    High Performance Planar Power Transformer with High Power Density in MHz Frequency Region for Next Generation Switch Mode Power Supplies2013In: 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference And Exposition (APEC 2013), IEEE conference proceedings, 2013, p. 2139-2143Conference paper (Refereed)
    Abstract [en]

    The authors report the utilization of the core based transformer for power transfer applications with high power density and high energy efficiency in the MHz frequency region. A custom made POT core center tapped transformer of 4:1:1 turn’s ratio using novel winding strategy with the core diameter of 16mm is designed and evaluated. The designed transformer has been characterized using sinusoidal excitation for a given output power in the frequency range of 1 – 10MHz and determined the operating frequency region of the transformer. The power tests of the transformer has been carried out up to the power level of 62W at an operating frequency of 6.78MHz with a peak energy efficiency of 98.5% resulting in the record power density of ~1100W/in3. The designed transformer has been characterized using class E isolated DC-DC converter topology at an output power of approximately 18W. The simulated energy efficiency of the converter is 88.5% under the full load condition. This work provides the significant step for the development of next generation high power density isolated converters (both AC/DC and DC/DC) in MHz frequency region

  • 14.
    Ambatipudi, Radhika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kotte, Hari Babu
    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.
    Radiated Emissions of Multilayered Coreless Printed Circuit Board Step-Down Power Transformers in Switch Mode Power Supplies2011In: 8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia 2011, IEEE conference proceedings, 2011, p. 960-965Conference paper (Refereed)
    Abstract [en]

    This paper addressesradiatedEMI issues in Coreless PCB step-down transformers used for power transfer applications. In case of SMPS circuits, since the waveforms are not sinusoidal in nature, most of theradiatedemissionsare not only from fundamental frequency component but also from harmonic contents. According to antenna theory,radiatedEMI for three different power transformers of different radii were estimated for fundamental frequency of 2MHz to 300MHz. The computations were made for both sinusoidal and square wave excitations and at a load power of 20W. The calculatedradiatedpower obtained for simulated waveforms and for practical measured current waveforms are in good agreement with each other up to certain bandwidth. These computational results confirm thatradiatedpower can be reduced in three layered 2:1 transformer compared to two layered 2:1 transformer. Also theradiatedemissionsare negligible in case of sinusoidal excitations compared to square wave excitations. © 2011 IEEE.

  • 15.
    Andersson, Henrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Öhlund, Thomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Forsberg, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Örtegren, Jonas
    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.
    Evaluation of InkAid surface treatment to enhance print quality of ANP silver nano-particle ink on plastic substrates2010In: Large Area, Organic & Printed Electronics (LOPE-C) 2010, Frankfurt, 2010, p. 241-245Conference paper (Refereed)
  • 16.
    Andersson, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    3D Video Playback: A modular cross-platform GPU-based approach for flexible multi-view 3D video rendering2010Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The evolution of depth‐perception visualization technologies, emerging format standardization work and research within the field of multi‐view 3D video and imagery addresses the need for flexible 3D video visualization. The wide variety of available 3D‐display types and visualization techniques for multi‐view video, as well as the high throughput requirements for high definition video, addresses the need for a real‐time 3D video playback solution that takes advantage of hardware accelerated graphics, while providing a high degree of flexibility through format configuration and cross‐platform interoperability. A modular component based software solution based on FFmpeg for video demultiplexing and video decoding is proposed,using OpenGL and GLUT for hardware accelerated graphics and POSIX threads for increased CPU utilization. The solution has been verified to have sufficient throughput in order to display 1080p video at the native video frame rate on the experimental system, which is considered as a standard high‐end desktop PC only using commercial hardware. In order to evaluate the performance of the proposed solution a number of throughput evaluation metrics have been introduced measuring average frame rate as a function of: video bit rate, video resolution and number of views. The results obtained have indicated that the GPU constitutes the primary bottleneck in a multi‐view lenticular rendering system and that multi‐view rendering performance is degraded as the number of views is increased. This is a result of the current GPU square matrix texture cache architectures, resulting in texture lookup access times according to random memory access patterns when the number of views is high. The proposed solution has been identified in order to provide low CPU efficiency, i.e. low CPU hardware utilization and it is recommended to increase performance by investigating the gains of scalable multithreading techniques. It is also recommended to investigate the gains of introducing video frame buffering in video memory or to move more calculations to the CPU in order to increase GPU performance.

  • 17.
    Appelsved, Ivan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Dosimetry of ionizing radiation with an artificial neural network: With an unsorted, sequential input2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis the verification of a neural network’s proficiency at labeling ionizing radiation particles from the unsorted output of a timepix3 camera is attempted. Focus is put on labeling single particles in separate data sequences with slightly preprocessed input data. Preprocessing of input data is done to simplify the patterns that should be recognized. Two major choices were available for this project, Elman-network and Jordan-network. A more complicated type was not an option because of the longer time needed to implement them. The network type chosen was Elman because of freedom in context size. The neural network is created and trained with the TensorFlow API in python with labeled data that was not created by hand. The network recognized the length difference between gamma particles and alpha particles. Beta particles were not considered by the network. It is concluded that the Elman-style network is not proficient in labeling the sequences, which were considered short enough and to have simple enough input data. A more modern network type is therefore likely required to solve this problem.

  • 18.
    Ashraf, Shakeel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design and Integration of Infrared Absorber Structures into Polymer Membranes based Thermal Detectors2015Licentiate thesis, comprehensive summary (Other academic)
  • 19.
    Ashraf, Shakeel
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Mattsson, Claes
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Rödjegard, Henrik
    Design of a multilayered absorber structure based on SU-8 epoxy for broad and efficient absorption inMid-IR sensitive thermal detectors2014In: Proceedings, 2014, p. 938-941Conference paper (Refereed)
    Abstract [en]

    This paper reports on design, simulation and fabrication of a multilayered interferometric absorption structure with a broad absorption in the mid-infrared band. This region is used for IR based CH4 and CO2 detection. The structure consists of five layers of different thickness. The structure consists of one mirror layer of aluminium, two SU-8 epoxy layers and two thin titanium layers. This structure has been fabricated on a silicon substrate and verified for its absorption properties through Fourier transform infrared spectroscopy. The fabricated structure has been compared with simulations are performed using transfer matrix theory. The structure shows more than 90% absorption in the wavelength range of 3.20μm - 5.35μm for simulations and 3.13μm - 5.47μm for FT-IR measurements. The transmission and reflection of SU-8 epoxy was measured using FT-IR (that), resulting in a calculated absorption between 10 - 20% in the area of interest (3μm - 6μm). The use of SU-8 epoxy as dielectric medium, allows for direct integration of the structure into the membrane of a SU-8 membrane based thermopile. The integration results in minimum increase of the thermal capacitance and conductance, which results in maximum detector sensitivity and minimum time constant.

  • 20.
    Ashraf, Shakeel
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Mattsson, Claes
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Rödjegard, Henrik
    SenseAir AB, Delsbo, Sweden.
    Integration of an interferometric IR absorber into an epoxy membrane based CO2 detector2014In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 9, no 5, p. Art. no. C05035-Article in journal (Refereed)
    Abstract [en]

    Measurements of carbon dioxide levels in the environment are commonly performedby using non-dispersive infrared technology (NDIR). Thermopile detectors are often used in NDIRsystems because of their non-cooling advantages. The infrared absorber has a major influence onthe detector responsivity. In this paper, the fabrication of a SU-8 epoxy membrane based Al/Bithermopile detector and the integration of an interferometric infrared absorber structure of wavelength around 4 µ m into the detector is reported. The membrane of thermopile detector has beenutilized as a dielectric medium in an interferometric absorption structure. By doing so, a reduction in both thermal conductance and capacitance is achieved. In the fabrication of the thermopile,metal evaporation and lift off process had been used for the deposition of serially interconnectedAl/Bi thermocouples. Serial resistance of fabricated thermopile was measured as 220 kΩ. Theresponse of fabricated thermopile detector was measured using a visible to infrared source of radiation flux 3.23 mW mm−2. The radiation incident on the detector was limited using a band passfilter of wavelength 4.26 µ m in front of the detector. A responsivity of 27.86 V mm2W−1at roomtemperature was achieved using this setup. The fabricated detector was compared to a referencedetector with a broad band absorber. From the comparison it was concluded that the integratedinterferometric absorber is functioning correctly.

  • 21.
    Balliu, Enkeleda
    et al.
    Polytechnic of Turin.
    Massimo, Olivero
    Polytechnic of Turin.
    Andrea, Braglia
    Polytechnic of Turin.
    Alessio, Califano
    Polytechnic of Turin.
    Guido, Perrone
    Polytechnic of Turin.
    Pulsed thulium doped fiber laser at 1.94 μm based on a seed diode2013In: Proc. SPIE 8601, Fiber Lasers X: Technology, Systems, and Applications, 860133 (February 26, 2013) / [ed] Proc. SPIE, SPIE - International Society for Optical Engineering, 2013, Vol. 8601Conference paper (Other academic)
    Abstract [en]

    A fiber laser operating at 1.94μm in pulsed regime has been developed in a MOPA configuration. The seed consists of a custom-developed board hosting a laser diode, whose current is modulated to achieve the desired pulse shape, duration and repetition rate. The pulses are amplified through a thulium-doped fiber amplifier pumped at 793 nm. The design of the amplifier stage has been performed by dynamic simulation of a rate-equations model and compared to the experimental measurements. Simulations and experimental measurements have exhibited comparable results, devising the realization of an effective pulsed laser system whose parameters can be easily tuned through the seed. 

  • 22.
    Bassam, Diraoui
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lokal kompensering i Mellanspänningsnät2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

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

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

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

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

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

  • 23.
    Berg, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Nätanalys: Identifiering av felställe i kabelnät2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

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

  • 24.
    Bertilsson, Kent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nästa generations kompakta spänningsomvandlare2012In: Thule, Kungl. Skytteanska Samfundets Årsbok 2012, ISSN 0280-8692, Vol. 1, no 1, p. 153-157Article in journal (Other (popular science, discussion, etc.))
  • 25.
    Björk, Carl Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    PID tuning with Ant Colony Optimization (ACO): A framework for a step response based tuning algorithm2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The building automation industry lacks an affordable, simple, solution for autonomous PID controller tuning when overhead variables fluctuate. In this project, requested by Jitea AB, a solution was developed, utilising step response process modelling, numerical integration of first order differential equations, and Ant Colony Optimization (ACO). The solution was applied to two control schemes; simulated outlet flow from a virtual water tank, and the physical air pressure in the ventilation system of a preschool in Sweden. An open-loop step response provided the transfer function in each case, which, after some manipulation, could be employed to predict the performance of any given set of PID parameters, based on a weighted cost function. This prediction model was used in ACO to find optimal settings. The program was constructed in both Structured Control Language and Structured Text and documented in an approachable way. The results showed that the program was, in both cases, able to eliminate overshoot and retain the settling time (with a slightly raised rise time) achieved with settings tuned per the current methods of Jitea AB. Noise and oscillations present in the physical system did not appear to have any major negative influence on the tuning process. The program performed above Jitea AB’s expectation, and will be tested in more scenarios, as it showed promise. Autonomous implementation could be of societal benefit through increased efficiency and sustainability in a range of processes. In future studies, focus should be on improving the prediction model, and further optimising the ACO variables.

  • 26.
    Bjørvik, Sindre
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Using delay line ultrasonic transducer to measure temperature and compensate2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ultrasonic non-destructive testing are widely used in many branches of the indus-

    try for measurements of materials characteristics.  In some cases there is a need

    for  ultrasonic  transducers  to  measure  at  higher  temperatures,  but  these sensors lack proper sensing quality at elevated temperatures.  With the years it has been developed  several  approaches  to  make  ultrasonic  transducers  able  to  measure  at higher temperatures.

    During this thesis an ultrasonic transducer with a delay line will be used to measure

    thickness of a steel pipe at temperatures up to 300C, the delay line will work as a

    temperature estimator and use the estimated temperature to compensate measure-

    ment errors which is created from higher temperatures.  A measurement system is

    created to make the ultrasonic transducer gather thickness and temperature data,

    this system will then be placed inside ovens for testing.

    At  higher  temperatures  a  problem  with  high  attenuation  of  signal  occurred  due to bad coupling and made it hard to find thickness values,  but the temperature

    estimations showed good results at stable temperatures.

  • 27.
    Brundin, Andreas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Hydraulisk testbänk: Automatiserad diagnostik av flödesgivare i en hydraulisk testbänk2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Hydrauliska testbänkar används för att testa nya och reparerade hydraulventiler och pumpar för att utvärdera deras uthållighet vad gäller tid och tryck. Testbänkar består vanligen av sensorer och mätare som operatören övervakar. Detta arbete behandlar ett diagnostiseringsprogram för en hydraulisk testbänk med avseende på dess flödesmätare. Den testbänk som behandlas är en hydraulisk testbänk med tillhörande hydraul aggregat inklusive sju flödesmätare. Testbänken har även ett tillhörande HMI. HMI:t har en inbyggd PLC och är av modellen Beijer iX T12B-SM. Målet är att designa ett diagnostiseringsprogram som varnar operatören när flödesmätarnas värden inte befinner sig inom den toleransnivå som önskas. Metoden för att konstruera ett diagnostiseringsprogram har fyra faser där den första fasen är att utföra en litteraturstudie gällande de faktorer som kan ha en inverkan på utformningen av diagnostiseringen. Faktorerna innefattar metoder för diagnostisering, utformningen av ett HMI och förväntningar på de flödesmätare som studeras. I den andra fasen utförs mätningar på flödesgivarna som ligger till grund för fas tre. Tredje fasen består i att programmera diagnostiseringsprogrammet. Den fjärde fasen går ut på att programmera visualiseringen av diagnosticeringen. Efter mätningar med flödesgivarna visar det sig att de har den toleransnivå som tillverkaren har utlovat. Vissa problem uppstår i samband med mätningarna då en pump inte fungerar som tänkt samt att en flödesmätare har lägre värden än förväntat. Diagnostiseringsprogrammet tillsammans med HMI:t motsvarar det syftet som finns med arbetet och larmar operatören som förväntat. För framtiden skulle det vara intressant att vidareutveckla diagnostiseringen så att alla aktuella flödesmätare jämför sina värden med varandra och larmar när fel uppstår.

  • 28.
    Bäcklund, Ylva
    et al.
    Uppsala universitet, Institutionen för materialvetenskap.
    Vangbo, Mattias
    Uppsala universitet, Institutionen för materialvetenskap.
    Rangsten, Pelle
    Uppsala universitet, Institutionen för materialvetenskap.
    Hedlund, Christer
    Uppsala universitet, Institutionen för materialvetenskap.
    Wet etching of single crystal quartz1998In: Workshop of Physical Chemistry of Wet Chemical Etching of Silicon, May 17-19, Holten, The Netherlands, 1998Conference paper (Refereed)
  • 29.
    Bäckman, Fredrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Hur påverkar olinjära laster en reservkraftsgenerator?2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A facility full with computers needs backup-power to guarantee the function. Loads in this facility will produce current and voltage harmonics that can pollute and cause trouble with the quality of electricity. Coromatic are interested in knowing more about how these loads can affect the generator. A measurement was performed on a facility when they ran a functional test. The results indicated that THD increased, the third harmonic turned out to be the single harmonic with the highest value. The value is within the boundaries for THDV according to SS-EN 50160 and 61000-2-2, except for the third harmonic. Its value was far too high. No action is propsed to deal with the problem at the moment. This thesis has provided Coromatic with valuable information too consider when they building new systems.

  • 30.
    Cheng, Xin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Malik, Waheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hardware Centric Machine Vision for High Precision Center of Gravity Calculation2010In: PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, 2010, p. 736-743Conference paper (Refereed)
    Abstract [en]

    We present a hardware oriented method for real-time measurements of object’s position in video. The targeted application area is light spots used as references for robotic navigation. Different algorithms for dynamic thresholding are explored in combination with component labeling and Center Of Gravity (COG) for highest possible precision versus Signal-to-Noise Ratio (SNR). This method was developed with a low hardware cost in focus having only one convolution operation required for preprocessing of data.

  • 31.
    Chuanliang, Xie
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Finite Element Analysis of PZT-based Air Flow Sensor2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis proposes a novel air flow sensor based on PZT material which is used to measure air velocity in an experimental tunnel or indoor ventilation. The work focuses on designing and verifying the sensor model through finite element analysis (FEA) simulation using COMSOL Multiphysics software.

    This thesis is devoted to developing a sensor model with a focus on a low-velocity range up to 2 m/s and high sensitivity. The design of the sensor should be robust and reliable for different flow patterns, temperature, and atmospheric pressure variation. The sensor model consists of a fixed cylinder which connects with a bilayer cantilever made of PZT and PDMS material. The laminar flow from the sensor inlet is transformed into the turbulent flow when passing by the fixed cylinder. This structure of bilayer cantilever is designed to generate self-induced oscillation on PZT to overcome the charge leakage over the sensor impedance. Resonance optimization of the sensor structure is investigated to obtain better SNR and performance by adjusting the dimension of the cantilever.

    From the conducted simulation results, the relationship between the dominant frequency of output voltage generated by PZT and air velocity can be described linearly. In conclusion, it is shown that proposed sensor has a sensitivity of 0.1 m/s and a range of 0.2 to 2 m/s.

  • 32. Chunjiang, Y
    et al.
    Tabikl, A
    Leckner, Bo
    Zhang, Wennan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Modeling of deposition and emission of alkalis in boiler systems: Mid-term reporting for project JOR3CT980306 of 4th EU-framework Programme2000Report (Other scientific)
  • 33.
    Coates, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Standardization: A practical study of industry standards and their applications.2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis project is to apply programming standardization to a practical PLC project. The practical programming task was carried out at ÅF Sundsvall. Two industry standards were chosen for analysis; IEC 61131-3 for PLC Programming, and SSG 5262 for HMI design. The project is programmed in TIA Portal V14, and hardware includes a Siemens 1200 series CPU, and TP700 Comfort HMI panel. The practical task involved in this project is to program and be able to simulate a sewage pump station. Both the PLC logic and HMI will use code which is scavenged from previous ÅF projects. This code was analyzed from a perspective of the chosen standards and certain incompatibilities were mentioned. In order for the code to satisfy the standards, modifcation was made to remedy the incompatibilities. Further, certain changes were made to the existing code in regards to general modernization. The station was successfully simulated based on the requirements placed on it and process information was presented in an efective manner.

  • 34.
    Dahlström Lif, Oscar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Fastighetsautomation: En projektering2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Building automation is used to automate processes in buildings and can be used for HVAC, lightning, security and more. This work relates to a BAS for HVAC in a building owned by SKIFU. It also relates to find what the current system is and a do comparison between two systems chosen by SKIFU, Schneider Electric and Regin. The method to find out what the current system is, is to make field studies and examine the documentation connected to the building. To be able to do the comparison between Schneider Electric and Regin a study of literature and the manufacturer’s website is made. The existing system is a Honeywell Excel 5000 system and it uses LonTalk and BACnet as communication standards. The system has DHC, DUCs and numerus actuators and sensors. The new systems Schneider Electric and Regin have different communication standards, KNX for Schneider Electric and EXOline, BACnet, M-bus and Modbus for Regin.  Schneider Electric does not need DHC and DUCs due to micro controllers is integrated in KNX units. With KNX the flexibility is high due to over 400 companies produce KNX certified units. Regin with their many standards in communication is also flexible but gateways may cause packet loss. The author of this work think that KNX is the system that should be chosen because of KNX as communication standard, and the communication is the main difference between the systems.  The conclusion is that the system used at cikellokstallet is a Honeywell system and if SKIFU are going to change system a KXN based system should be used, based on KNX does not need any gateways and KNX is the most used standard on the market.

     

  • 35. Dai, X W
    et al.
    Yin, X L
    Guangzhou Inst. of Energy Conversion, Chinese Academy of Sciences, China.
    Wu, C Z
    Guangzhou Inst. of Energy Conversion, Chinese Academy of Sciences, China.
    Zhang, W N
    Guangzhou Inst. of Energy Conversion, Chinese Academy of Sciences, China.
    Chen, Y
    Guangzhou Inst. of Energy Conversion, Chinese Academy of Sciences, China.
    Pyrolysis of waste tires in a circulating fluidized-bed reactor2001In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 26, no 4, p. 385-399Article in journal (Refereed)
    Abstract [en]

    Using a circulating fluidized bed (CFB) as the main reactor, an integrated process development unit was operated aiming at the pyrolysis of waste tires. The main chemical processes in the CFB can be divided into two zones corresponding to pyrolysis and secondary reactions. The pyrolysis of tire powder was carried out at various pyrolysis temperatures, particle sizes of tire powder and feed positions. The effects of temperature, residence time and heating rate on pyrolysis were analyzed based on the experimental data. The main trends are that (1) a long residence time contributes to secondary reactions and (2) lower temperature and heating rate favor carbonization, which reduces the oil yield. Analysis of the pyrolytic oil shows that the predominant components are aromatics, followed by alkanes, non-hydrocarbons and asphalt.

  • 36.
    Damghanian, Mitra
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Performance analysis in Lytro camera: Empirical and model based approaches to assess refocusing quality2014In: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, IEEE conference proceedings, 2014, p. 559-563Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the performance of Lytro camera in terms of its refocusing quality. The refocusing quality of the camera is related to the spatial resolution and the depth of field as the contributing parameters. We quantify the spatial resolution profile as a function of depth using empirical and model based approaches. The depth of field is then determined by thresholding the spatial resolution profile. In the model based approach, the previously proposed sampling pattern cube (SPC) model for representation and evaluation of the plenoptic capturing systems is utilized. For the experimental resolution measurements, camera evaluation results are extracted from images rendered by the Lytro full reconstruction rendering method. Results from both the empirical and model based approaches assess the refocusing quality of the Lytro camera consistently, highlighting the usability of the model based approaches for performance analysis of complex capturing systems.

  • 37.
    Damghanian, Mitra
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    The Sampling Pattern Cube: A Representation and Evaluation Tool for Optical Capturing Systems2012In: Advanced Concepts for Intelligent Vision Systems / [ed] Blanc-Talon, Jacques, Philips, Wilfried, Popescu, Dan, Scheunders, Paul, Zemcík, Pavel, Berlin / Heidelberg: Springer Berlin/Heidelberg, 2012, , p. 12p. 120-131Conference paper (Refereed)
    Abstract [en]

    Knowledge about how the light field is sampled through a camera system gives the required information to investigate interesting camera parameters. We introduce a simple and handy model to look into the sampling behavior of a camera system. We have applied this model to single lens system as well as plenoptic cameras. We have investigated how camera parameters of interest are interpreted in our proposed model-based representation. This model also enables us to make comparisons between capturing systems or to investigate how variations in an optical capturing system affect its sampling behavior.

  • 38.
    de Pano, Edwin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Using Fiber Bragg Grating for High Frequency Measurements of Acoustic Waves2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fiber optical sensors are a new type of sensor-technology which has been in development for over 30 years, and the interest for the fiber technology has increased exponentially. The reason for this is because of its many advantages such as; electromagnetic immunity, size and weight reductions, and cost reduction. Even though the fiber optic sensor has many advantages, it still faces other challenges. A fiber optical sensor can for example be used to measure acoustic waves, which is a typical application for the sensor. However, one of the challenges is that the fiber optic sensor can be disturbed by an unknown thermal fluctuation. In this project we will develop technology for a control algorithm which will compensate for this unknown thermal fluctuation. During this project the fiber optical sensor; Fiber Bragg Grating, will be used to measure acoustic waves on a steel plate. For initial test a tuneable laser diode has been used, which then was be replaced with a superluminescent diode and a reference Fiber Bragg Grating. The results were that it was possible to measure acoustic waves with a tuneable laser diode. However when replacing the laser diode with a superluminescent diode and a reference Fiber Bragg Grating, the optical power was too low for the photodetector to

    measure any change in optical power.

  • 39.
    Do Thi, Minh Huyen
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Design and Construction Of A Paper Thin Magnetostatic Loudspeaker: using Arduino Mega 2560, MusicShield v1.13 and MPR1212012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This focus of this report is on design and the aim is to build a magnetostatic speaker and a music loudspeaker from scratch by assembling the sensors together and thus, making a simple but very thin foil loudspeaker. The Arduino sensor is programmed in C language in order to make the capaci-tive sensor to have the ability to control the functions of the music player and LEDs.At the end of the process, the product will be able to play music through the thin loudspeaker by touching the capacitive sensor.

  • 40.
    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.

  • 41.
    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.

  • 42.
    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).

  • 43.
    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.

  • 44.
    Esebamen, Omeime
    et al.
    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.
    Thungström, Göran
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Spectral Performance of Photon Counting Pixel Detector Using Attenuation Spectra for Test Samples2009In: AIP Conference Proceedings Volume 1204, New York: American Institute of Physics (AIP), 2009, p. 177-179Conference paper (Refereed)
    Abstract [en]

    When a material is placed along the path of an X-ray beam using a broad range of energy X-ray source, the energy dependence of the attenuation for the X-ray photons will be substantially dissimilar for different materials. The process at which X-ray radiation loses its penetrating strength as it travels through a material will be significantly larger for photons with energy above k-edge energy of that material than for those with slightly lower energy. Hence energy resolved X-ray imaging can be used to achieve colour images revealing the material content of the test sample. The attenuation of the spectrum done by scanning an energy window through the spectrum was measured for a number of samples of different materials. The test samples include Sn, Gd and I with K-edge energy at 29 keV, 50 keV and 33 keV, respectively, using a Feinfocus microfocus X-ray source (FTP-105.02) with Medipix2 photon counting chip.

  • 45.
    Faria, Gregorio Couto
    et al.
    Stanford University, Instituto de Física de São Carlos (IFSC).
    Duong, Duc Trong
    Stanford University.
    Dahlström, Christina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rivnay, Jonathan
    École Nationale Supérieure des Mines de Saint Étienne.
    Malliaras, George
    École Nationale Supérieure des Mines de Saint Étienne.
    Owens, Roisin
    École Nationale Supérieure des Mines de Saint Étienne.
    Salleo, Alberto
    Stanford University.
    Modeling Transient Drain Current Response in Biofunctionalized Organic Electrochemical Transistors2015Conference paper (Other academic)
  • 46.
    Fedorov, Igor
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Alqaysi, Hiba
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Placement Strategy of Multi-Camera Volumetric Surveillance System for Activities Monitoring2017In: ICDSC 2017 Proceedings of the 11th International Conference on Distributed Smart Cameras, New York, NY, USA: Association for Computing Machinery (ACM), 2017, Vol. F132201, p. 113-118Conference paper (Refereed)
    Abstract [en]

    The design of multi-camera surveillance system comes with many advantages, for example it facilitates as understanding how flying objects act in a given volume. One possible application is for the observation interaction of birds and calculate their trajectories around wind turbines to create promising systems for preventing bird collisions with turbine blades. However, there are also challenges, such as finding the optimal node placement and camera calibration. To address these challenges we investigated a trade-off between calibration accuracy and node requirements, including resolution, modulation transfer function, field of view and angle baseline. We developed a strategy for camera placement to achieve improved coverage for golden eagle monitoring and tracking. This strategy based on the modified resolution criterion taking into account the contrast function of the camera and the estimation of the base angle between the cameras.

  • 47.
    Fedorov, Igor
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Alqaysi, Hiba
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Towards calibration of outdoor multi-camera visual monitoring system2018In: ACM International Conference Proceeding Series, New York, NY, US: ACM Digital Library, 2018, , p. 6Conference paper (Refereed)
    Abstract [en]

    This paper proposes a method for calibrating of multi-camera systems where no natural reference points exist in the surrounding environment. Monitoring the air space at wind farms is our test case. The goal is to monitor the trajectories of flying birds to prevent them from colliding with rotor blades. Our camera calibration method is based on the observation of a portable artificial reference marker made out of a pulsed light source and a navigation satellite sensor module. The reference marker can determine and communicate its position in the world coordinate system at centimeter precision using navigartion sensors. Our results showed that simultaneous detection of the same marker in several cameras having overlapping field of views allowed us to determine the markers position in 3D world coordinate space with an accuracy of 3-4 cm. These experiments were made in the volume around a wind turbine at distances from cameras to marker within a range of 70 to 90 m.

  • 48.
    Forsman, Björn
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Zhang, Wennan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Alkali Metal Release During Rapid Pyrolysis of Fuel Blends Containing 2005In: Proceedings. 14th European conference and technology exhibition biomass for energy industry and climate protection, Paris, Oct. 2005, 2005Conference paper (Other scientific)
    Abstract [en]

    In the present study the influence of different fuel blends and additives on the release of gaseous alkali metals during rapid pyrolysis of biomass has been investigated. A single particle reactor has been used together with a molecular beam mass spectrometer (MBMS) to study the release of gaseous alkali-containing emissions during pyrolysis. A hot platinum filament was used as the ionization source and alkali-containing compounds that hit the hot filament dissociate and alkali ions leave the Pt -filament and are detected in the MBMS. The fuels used were wood (spruce) and wood waste. The additives included peat, different sewage sludge samples, sludge from the pulp and paper industry and fly ash from co-combusted wood and sewage sludge. Experimental results show time resolved mass loss curves of biomass particles during rapid pyrolysis combined with released amounts of sodium (Na) and potassium (K). The results indicate that the new combined instrument successfully detects gaseous alkali metals, and a difference in the release of Na and K during pyrolysis due to the use of the additives is observed. Additives consisting of sewage sludge ash reduced the release of alkali, probably due to the presence of mullite in the ash together with the sorption effect of fine particles.

  • 49.
    Forsman, Björn
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Zhang, Wennan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Svenson, J.
    Pettersson, J.B.C.
    ALKALI METAL RELEASE DURING RAPID PYROLYSIS OF FUEL BLENDS CONTAINING BIOMASS AND DIFFERENT ADDITIVES.2005In: Proceedings of the 14th European Biomass Conference: Biomass for Energy, Industry and Climate Protection, 2005Conference paper (Other academic)
  • 50.
    Fröjdh, Anna
    et al.
    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.
    Fröjdh, Christer
    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.
    An alpha particle detector for measuring radon levels2010In: Proceedings of Nuclear Science Symposium Conference Record (NSS/MIC), 2010, IEEE conference proceedings, 2010, p. 460-461Conference paper (Refereed)
    Abstract [en]

    An alpha particle detector for measuring radon levels through measurement of radon progeny concentration has been developed. The detector is a silicon diode optimized for these measurements. Different alternating and non-alternating guard ring structures and different doping profiles have been investigated.

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