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  • 351.
    Chen, Jian
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Maintaining Stream Data Distribution Over Sliding Window2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In modern applications, it is a big challenge that analyzing the order statistics about the most recent parts of the high-volume and high velocity stream data. There are some online quantile algorithms that can

    keep the sketch of the data in the sliding window and they can answer the quantile or rank query in a very short time. But most of them take the

    GK algorithm as the subroutine, which is not known to be mergeable. In this paper, we propose another algorithm to keep the sketch that maintains the order statistics over sliding windows. For the fixed-size window, the existing algorithms can’t maintain the correctness in the process of updating the sliding window. Our algorithm not only can maintain the correctness but also can achieve similar performance of the optimal algorithm. Under the basis of maintaining the correctness, the insert time and query time are close to the best results, while others can't maintain the correctness. In addition to the fixed-size window algorithm, we also provide the time-based window algorithm that the window size varies over time. Last but not least, we provide the window aggregation algorithm which can help extend our algorithm into the distributed system.

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  • 352.
    Chen, Zhiqiang
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Evaluating the performance of a vibration energy harvester under complex excitation2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years, vibration energy harvesting has become a research hotspot in the field of energy harvesting. Energy harvester output power is the most important parameter in a vibration energy harvesting system. Assessing the harvester output power in different vibration environments is an important study issue to study. This thesis proposed a research method for harvester output based on the complex vibration environment simulated in the laboratory, a closed-loop control experimental system for the simulated vibration environment was established, the system can simulate a vibration environment with specific vibration frequency and acceleration, and automatically measure the harvester output power. Using FFT methods to analyse the harvester output voltage waveform, research the relationship between the harvester output power and the noise vibration signal frequency. Polynomial fitting modelling method is used for the harvester output power prediction in the 62.5Hz dominant frequency vibration environment. At the same time, researching the harvester output power in different dominant frequency and same vibration acceleration vibration environment which containing noise signal. Through the analysis of harvester output power, it was found that, for the case of the vibration environment dominant frequency is 62.5Hz, all noise frequency component of the vibration signal will reduce the output power of vibration energy harvester modelD, especially when the noise frequency is around 57.5Hz and67.5Hz, the output power of vibration energy harvester modelD is quite lower than the output power of harvester under the pure sinusoidal excitation signals. For the case of the vibration environment dominant frequency is not 62.5Hz, if the noise frequency component of the vibration signal close the harvester resonance frequency, it has a great impact on output power, and the output power of harvester is higher than the output power of harvester under the pure sinusoidal excitation signals. The presented research methods apply to most such studies, which can help user to analyse the effect of vibration noise on the harvester output and helps increase the harvester's output power. Research conclusions can provide user a reference in harvester selection.

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  • 353.
    Cheng, Peng
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Applications of embedded sensors in loader crane positioning and rotor RPM measurement2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, two novel applications involving embedded sensors arestudied, one dealing with loader crane positioning and the other involving rotorRevolutions Per Minute (RPM) measurement. The thesis presents a generalintroduction to the embedded sensor, its architecture and its use in mechanicalindustry, and provides the reader with an overview of conventional sensortechnologies within the fields of angle sensors and angular speed sensors, coveringtheir working principles, features, advantages and disadvantages and typicalapplications. The particular problems associated with the use of conventionalsensors in both loader crane positioning and rotor RPM measurement aredescribed and these problems provided the motivation for the designs of theembedded sensor systems developed in this thesis.In the case of the loader crane positioning, the origins of the project and thespecial requirements of the application are described in detail. In addition, apreliminary study is conducted in relation to the idea of a contactless joint angularsensor using MEMS inertial sensors in which four different methods, namely, theCommon-Mode-Rejection with Gyro Integration (CMRGI), Common-Mode-Rejection (CMR), Common-Mode-Rejection with Gyro Differentiation (CMRGD)and Distributed Common-Mode-Rejection (DCMR), are conceived, modeled andtested on a custom-designed prototype experimental setup. The results gatheredfrom these four methods are compared and analyzed in order to identify thedifferences in their performances. The methods, which proved to be suitable, arethen further tested using the prototype sensor setup on a loader crane and theperformance results are analyzed in order to make a decision in relation to the twomost suitable methods for the application of the loader crane positioning. Theresults suggested that the two most suitable were the CMRGD and the DCMR. Thepractical design issues relating to this sensor system are highlighted andsuggestions are made in the study. Additionally, possible future work for thisproject is also covered.In the first case for the rotor RPM measurement, the thesis presents themodeling and simulation of the stator-free RPM sensor idea using the Monte Carlomethod, which demonstrated the special features and performance of this sensor.The design aspects of the prototype sensor are described in detail and theprototype is tested on an experimental setup. The conclusions for the stator-freeRPM sensor are then made from the analysis of the experimental results and futurework in relation to this sensor is also proposed.In the second case of the rotor RPM measurement, the thesis presentsanother idea involving the laser mouse RPM sensor and the main focus of thestudy is on the performance characterization of the laser mouse sensor and theverification of the RPM sensor idea. Experiments are conducted using the test setup and results are gathered and analyzed and conclusions are drawn.Possibilities in relation to future work for this laser mouse RPM sensor are alsoprovided.The summary and the conclusion form the final chapter of the thesis andseveral important aspects of the designs relating to both the loader cranepositioning project and the rotor RPM measurement project are discussed.

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    Doctoral Thesis 114
  • 354.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Linnarsson, Fredrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Joint Angular Sensor Based on Distributed Biaxial MEMS Accelerometers2007In: IECON 2007: 33RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY, VOLS 1-3, CONFERENCE PROCEEDINGS, New York: IEEE conference proceedings, 2007, p. 2242-2247Conference paper (Refereed)
    Abstract [en]

    This paper presents the analysis for joint angle measurement on rigid body that is based on distributed biaxial MEMS accelerometers. It focuses on two methods, one called CMR and another DCMR, and utilizes the property of rigid body kinematics to explain their advantages and weaknesses. Unlike CMR method, DCMR method has no requirement on placing the sensors close to the joint center. This provides greater flexibility for the sensor installation. On the basis of the error model of CMR method, we give an analysis outlining the advantage of theoretically error-free DCMR method. The sensor calibration and alignment is described and both methods are characterized on a rigid body robot arm model. The experiment shows the angular error up to 0.4rad from CMR method whereas just 0.03rad from DCMR method. The noise level from both methods is also compared and analyzed. The result reveals a larger but tunable noise for DCMR method.

  • 355.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Nazar Ul Islam, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Torque sensor2018Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a torque sensor (1) comprising a body (2), at least one airtight chamber (3) provided in the body, a pressure sensor (4) measuring 1 the pressure in said at least one airtight chamber, and a pressure to torque converter (5) connected with the pressure sensor. Each airtight chamber is arranged to change its volume when the body is subjected to a torque, wherein the volume change causes a change of pressure of the enclosed air in the airtight chamber. The change of pressure is detected and converted to the corresponding torque.

  • 356.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Nazar Ul Islam, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Torque Sensor Based on Differential Air Pressure Using Volumetric Strain2017In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 11, p. 3269-3277, article id 7902159Article in journal (Refereed)
    Abstract [en]

    This paper proposes a torque sensor based on the differential air pressure measurement method using the volumetric strain of a mechanical sensing structure. A model of the measurement system based on the differential air pressure from the volumetric strain of the mechanical sensing structure is proposed and theoretically discussed. The error sources are identified and an error propagation model is presented for the proposed torque measurement method. Considering these error sources, a prototype torque sensor is presented as a case study for the method verification. Both the mechanical and readout electronics designs are discussed and analyzed. The mechanical sensitivity, resolution, and maximum stresses are analyzed using finite-element modeling. Based on the results from the simulation, a prototype torque sensor is manufactured and experimentally verified using a readout electronics design. For verification, the sensor prototype is measured under static torque to have a sensitivity of 0.04272V/N. m and a range of +/- 117N . m. Compared with the nominal mechanical sensitivity result from the FEM simulation, this measured sensitivity has a difference less than 6%. The noise analysis of the designed readout electronics shows that the resolution of 0.006% can be achieved with this design. Furthermore, hysteresis analysis shows an error of 0.012% of full scale. From these results, it is also shown that the actual performance of the sensor is mainly limited by the differential pressure sensor and the readout electronics design and is not by the mechanical design of the sensor.

  • 357.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Joint-angle Measurement Using Accelerometers and Gyroscopes: A Survey2010In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 59, no 2, p. 404-414Article in journal (Refereed)
    Abstract [en]

    This paper presents an analysis of rigid-body joint-angle measurement based on microelectromechanical-system (MEMS) biaxial accelerometers and uniaxial gyroscopes. In comparison to conventional magnetic and optical joint angular sensors, this new inertial sensing principle has the advantages of flexible installation and true contactless sensing. This paper focuses on the comparison of four different inertial-sensor combination methods that are reported in reference papers and utilizes the theory of rigid-body kinematics to explain and analyze their advantages and weaknesses. Experiments have also been conducted to further verify and strengthen the arguments put forward in the analysis. All experiments in this paper took place on a custom-built rigid-body robot arm model that can be manipulated by hand. Sensor calibration and accelerometer alignment issues are also described, and their details are discussed. The experiment results presented in this paper show significant differences with reference to the achieved angular accuracy for various situations when using the four different sensor combination methods. In some cases, the angular error based on one method is more than 0.04 rad, while that from another method is within +/-0.005 rad. The noise levels of angular readings from different methods are also experimentally compared and analyzed. The conclusion drawn serves to guide readers toward a suitable method for their particular application.

  • 358.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Linnarsson, Fredrik
    Cargotec Sweden AB, S-82450 Hudiksvall, Sweden.
    A Local Positioning System for Loader Cranes Based on Wireless Sensors-A Feasibility Study2011In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 60, no 8, p. 2881-2893Article in journal (Refereed)
    Abstract [en]

    This paper presents a feasibility study that deals with a local positioning system for a loader crane based on battery-powered wireless sensors and consists of two joint angular sensors and one telescopic boom length ranger. The practical challenges associated with using conventional sensors are described in order to provide the motivation behind the choice to use the sensing methods proposed in this paper. A novel method is tested using microelectromechanical system inertial sensors mounted around the crane joints to indirectly measure the joint angles, as well as an ultrasound time-of-flight ranging method to measure the telescopic boom length. The local positioning system's wireless sensor prototype designs are described in detail. Data from the angular sensor experiments conducted on a loader crane and the ultrasound ranging experiments conducted both in the laboratory and on the loader crane are presented and analyzed. The preliminary results from these experiments show that the performance of the new sensors is promising. The conclusion is drawn from the experimental results, and future work for this local positioning system is also described.

  • 359.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sobh, Mohamed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Contactless Rotor RPM Measurement Using Laser Mouse Sensors2012In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, no 3, p. 740-748Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental study using laser mouse sensors for the contactless revolutions per minute (RPM) measurement of a rotating shaft. The sensor performance characterization experiment is firstly conducted under different parameter setups. After the optimal parameter value has been found, the rotor RPM experiment is then conducted with a speed sweep from 500 to 3800 rpm, and data are gathered at 30 different speeds and processed using two different methods to convert the sensor readings into the RPM of the rotating shaft; the results are then displayed. The performance differences between the two methods are compared, and the observation is that both the linearity and the signal-to-noise ratio of the frequency correlation method are several times better than those for the amplitude correlation method. The conclusion summarizes the experimental results and the advantage associated with this new RPM sensing method and provides the motivation for its potential applications and its future works.

  • 360.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Szewczyk, Roman
    Industrial Research Institute for Automation and Measurements, Warsaw, Poland.
    Modified description of magnetic hysteresis in Jiles-Atherton model2018In: Automation 2018: Advances In Automation, Robotics And Measurement Techniques, Springer, 2018, Vol. 743, p. 648-654Conference paper (Refereed)
    Abstract [en]

    Paper presents new idea of modelling the magnetic hysteresis in the Jiles-Atherton model. Presented approach considers physical principles of magnetisation process and main assumptions of Jiles-Atherton model. As a result modified differential equation stating the model was proposed. This equation was verified on the base of magnetic hysteresis loops of non grain oriented electrical steel. Presented results indicate, that proposed approach to modelling the magnetic hysteresis loops well correspond with results of experimental measurements. 

  • 361.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Yang, Yan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Design and Implementation of a Stator-Free RPM Sensor Prototype Based on MEMS Accelerometers2012In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, no 3, p. 775-785Article in journal (Refereed)
    Abstract [en]

    This paper presents the design and implementation of a prototype of a stator-free revolutions-per-minute (RPM) sensor based on two microelectromechanical-system uniaxial accelerometers. This paper first introduces the operating principle of the stator-free RPM sensor. It then discusses the associated architecture and design issues of this new sensing method. It then describes the detail of the prototype sensor hardware and software design of the common-mode rejection method and its signal processing. Experiments using the prototype sensor have been also conducted to further verify and strengthen the arguments put forward in the previous discussion. All experiments in this paper took place on a lathe machine in a laboratory. Sensor calibration under a MATLAB environment is also described. Experimental results confirm the interesting property of this sensor, namely, that it provides higher precision at higher RPM. The conclusion summarizes the design considerations, the experimental results, and the motivation in relation to future works for this stator-free RPM sensing method.

  • 362.
    Cheng, Peng
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Yang, Yan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Stator-free RPM Sensor Using Accelerometers - A Statistical Performance Simulation by Monte Carlo Method2011In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 11, no 12, p. 3368-3376Article in journal (Refereed)
    Abstract [en]

    This paper presents an statistical performance simulation for rigid-body revolutions per minute (RPM) measurement based on two uni-axial accelerometers mounted on rotor. In comparison with other existing sensing methods that are based on two coupled parts, namely stator and rotor and which include conventional electro-magnetic RPM sensors and photo-electric RPM sensors, this new stator-free inertial sensing principle has the advantage of high bandwidth at low RPM, true contact-free sensing and flexible installation. The paper first focuses on the description of the operating principle and the common mode rejection (CMR) method of the stator-free RPM sensor, and then its error model is developed and the error sources are statistically simulated based on Monte Carlo method. The simulation result presents a most interesting property of this sensor, that is, it gives lower precision at lower RPM and higher precision at higher RPM. The conclusion summarizes the modeling analysis result and motivates potential application for this new RPM sensing method.

  • 363.
    Cheng, Xin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hardware centric machine vision for high precision measurement of reference structures in optical navigation2012Licentiate thesis, comprehensive summary (Other academic)
  • 364.
    Cheng, Xin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Abdul Waheed, Malik
    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.
    Color Symbol Design and Its Classification for Optical NavigationManuscript (preprint) (Other academic)
    Abstract [en]

    We explored the color symbol design and its recognition in image as reference structure for optical navigation. A colors pair was first determined as foreground and background from HSI color palette and then a color symbol was designed as reference structure. The advantage of using this selected color symbol is a significant reduction, up to 97%, of segmented image components as compared to the grey scale image used. The reduction of segmented components in image will result in saving the hardware resources e.g. memory and processing power which are very important constraint for embedded platforms. A color symbol pattern was designed, comprising of three concentric circles with selected color pair. Inside the inner most circle is the Area Of Interest (AOI), the contents of AOI depends on the particular application. A hardware centric image analysis algorithm is developed for easy and robust recognition. Image components are identified after preprocessing, segmentation and labeling. The color symbol can be recognized at a classification step. Evaluating a variety of viewing angles and reading distances ranging from 30 to 150 degrees and from 1 to 10 meters gives a classification success rate of 72 percent of the positions.

  • 365.
    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.
    Abdul Waheed, Malik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Optimized Color Pair Selection for Label Design2011In: Proceedings Elmar - International Symposium Electronics in Marine, Zadar, Croatia: IEEE conference proceedings, 2011, p. 115-118Conference paper (Refereed)
    Abstract [en]

    We present in this paper a technique for designing reference labels that can be used for optical navigation. We optimize the selection of foreground and background colors used for the printed reference labels. This optimization calibrates for individual color responses among printers and cameras such that the Signal to Noise Ratio (SNR) is maximized. Experiments show that we get slightly smaller SNR for the color labels compared to using a monochrome technique. However, the number of segmented image components is reduced significantly by as much as 78 percent. This reduction of number of image components will in turn reduce the memory storage requirement for the computing embedded system.

  • 366.
    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.

  • 367.
    Chmeissani, M
    et al.
    IFAE Barcelona .
    Fröjdh, Christer
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gal, O
    CEA France.
    Llopart, X
    CERN.
    Ludwig, J
    Albert-Ludwigs-Universität-Freiburg.
    Ponchut, C
    ESRF.
    Russo, P
    INFN, Italy.
    Tlustos, L
    CERN.
    First experimental tests with a CdTe photon counting pixel detector hybridized with a Medipix2 readout chip2004In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 51, no 5, p. 2379-2385Article in journal (Refereed)
    Abstract [en]

    We present preliminary tests of hybrid pixel detectors consisting of the Medipix2 readout chip bump-bonded to a 1-mm-thick CdTe pixel detector. This room temperature imaging system for single photon counting has been developed within the Medipix2 European Collaboration for various imaging applications with X-rays and gamma rays, including dental radiography, mammography, synchrotron radiation, nuclear medicine, and radiation monitoring in nuclear facilities. The Medipix2 + CdTe hybrid detector features 256 × 256 square pixels, a pitch of 55 μm, a sensitive area of 14×14 mm2. We analyzed the quality of the detector and bump-bonding and the response to nuclear radiation of the first CdTe hybrids. The CdTe pixel detectors, with Pt ohmic contacts, showed an ohmic response when negatively biased up to less than 60 V (electrons collection mode). Tests were also performed in holes collection mode, where a nonresistive behavior was observed above +15 V. We performed a series of imaging tests at low voltage bias with gamma radioactive sources and with an X-ray tube. Under uniform irradiation, we observed for all detectors the presence of numerous, stable structures in the form of small circles of about 200 μm diameter, with the central pixels showing a reduced counting efficiency with respect to the periphery (in electrons counting regime). Also long filament structures have been observed. Further investigations will reveal whether they are due to an intrinsic detector response (e.g., due to Te inclusions) or to the bump-bonding process.

  • 368.
    Chmieliauskas, Darius
    et al.
    Vilnius Gediminas Technical University, Lithuania.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-).
    Paulikas, Sarunas
    Vilnius Gediminas Technical University, Lithuania.
    Thar, Kyi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-).
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and Electrical Engineering (2023-).
    Q-Learning Inspired Method for Antenna Azimuth Selection in Cellular Networks2023In: 2023 Workshop on Microwave Theory and Technology in Wireless Communications (MTTW), IEEE conference proceedings, 2023Conference paper (Refereed)
    Abstract [en]

    Cellular networks are becoming increasingly complex, requiring careful optimization of parameters such as antenna propagation pattern, tilt, direction, height, and transmitted reference signal power to ensure a high-quality user experience. In this paper, we propose a new method to optimize antenna direction in a cellular network using Q-learning. Our approach involves utilizing the open-source quasi-deterministic radio channel generator to generate radio frequency (RF) power maps for various antenna configurations. We then implement a Q-learning algorithm to learn the optimal antenna directions that maximize the signal-to-interference-plus-noise ratio (SINR) across the coverage area. The learning process takes place in the constructed open-source OpenAI Gym environment associated with the antenna configuration. Our tests demonstrate that the proposed Q-learning-based method outperforms random exhaustive search methods and can effectively improve the performance of cellular networks while enhancing the quality of experience (QoE) for end users.

  • 369.
    Christensen, M. J.
    et al.
    European Spallat Source, Copenhagen, Denmark.
    Shelly, M.
    European Spallat Source, Copenhagen, Denmark.
    Nilsson, J.
    European Spallat Source, Copenhagen, Denmark.
    Mukai, A.
    European Spallat Source, Copenhagen, Denmark.
    Al Jebali, R.
    European Spallat Source ERIC, Lund; Glasgow Univ, Glasgow, Lanark, Scotland.
    Khaplanov, A.
    European Spallat Source ERIC, Lund.
    Lupberger, M.
    CERN, Geneva, Switzerland.
    Messi, F.
    European Spallat Source ERIC, Lund; Lund Univ, Lund.
    Pfeiffer, D.
    European Spallat Source ERIC, Lund; CERN, Geneva, Switzerland.
    Piscitelli, F.
    European Spallat Source ERIC, Lund.
    Blum, T.
    Niels Bohr Inst, Copenhagen, Denmark.
    Sogaard, C.
    Niels Bohr Inst, Copenhagen, Denmark.
    Skelboe, S.
    Niels Bohr Inst, Copenhagen, Denmark.
    Hall-Wilton, Richard
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. European Spallat Source ERIC, Lund.
    Richter, T.
    European Spallat Source ERIC, Lund.
    Software-based data acquisition and processing for neutron detectors at European Spallation Source-early experience from four detector designs2018In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 13, no 11, article id T11002Article in journal (Refereed)
    Abstract [en]

    European Spallation Source (ESS) will deliver neutrons at high flux for use in diverse neutron scattering techniques. The neutron source facility and the scientific instruments will be located in Lund, and the Data Management and Software Centre (DMSC), in Copenhagen. A number of detector prototypes are being developed at ESS together with its European in-kind partners, for example: SoNDe, Multi-Grid, Multi-Blade and Gd-GEM. These are all position sensitive detectors but use different techniques for the detection of neutrons. Except for digitization of electronics readout, all neutron data is anticipated to be processed in software. This provides maximum flexibility and adaptability and allows deep inspection of the raw data for commissioning which will reduce the risk of starting up new detector technologies. But it also requires development of high performance software processing pipelines and optimized and scalable processing algorithms. This report provides a description of the ESS system architecture for the neutron data path. Special focus is on the interface between the detectors and DMSC which is based on UDP over Ethernet links. The report also describes the software architecture for detector data processing and the tools we have developed, which have proven very useful for efficient early experimentation, and can be run on a single laptop. Processing requirements for the SoNDe, Multi-Grid, Multi-Blade and Ge-GEM detectors are presented and compared to event processing rates archived so far.

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  • 370.
    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.

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  • 371. 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)
  • 372. Ciamulski, T.
    et al.
    Hjelm, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sypniewski, M.
    Custumisation of FDTD simulator kernel for parallel computing in advanced applications2006In: ICSES'06 - International Conference on Signals and Electronic Systems, Proceedings, 2006, p. 649-652Conference paper (Other academic)
    Abstract [en]

    A commercial FDTD simulation software is the basis of an ongoing parallelization project. In the first phase of the project the work is aiming at optimization of the program on shared memory computers. In this paper we present the initial methods of parallelization with the achieved performance on a Sun Fire 15K NUMA computer. The achieved results are discussed, together with the possible paths to improve the speedup.

  • 373. Ciamulski, T
    et al.
    Sypniewski, M
    Wieckowski, A
    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.
    Parallel FDTD Processing on Shared Memory Computers2007In: The 23rd annual review of Progress in Applied computational electromagnetics: March 19-23, 2007 Verona, Italy, 2007Conference paper (Other academic)
    Abstract [en]

    An ongoing European project on customization of electromagnetic simulation tool is ready to present significantly improved performance of parallel version of a professional FDTD simulator. The first stage of the work is concentrated on solution for computers with the shared memory architecture. The relevance and feasibility study of the solution for contemporary computers is shown. Possible ways to reach further performance improvements as well as solutions for distributed memory machines are discussed.

  • 374.
    Ciamulski, Tomasz
    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.
    Sypniewski, Maciej
    Parallel FDTD calculation efficiency on computers with shared memory architecture2007In: 2007 WORKSHOP ON COMPUTATIONAL ELECTROMAGNETICS IN TIME-DOMAIN, New York: IEEE conference proceedings, 2007, p. 33-36Conference paper (Refereed)
    Abstract [en]

    Fast parallel processing of the FDTD method is becoming very important, and its efficiency on different multiprocessor computer architectures should be carefully examined. Is it possible to have the same versatile parallel FDTD simulator working efficiently on a set of very different computer architectures? In contrast to distributed memory systems, shared memory systems can be built with a variety of memory configuration types (and subtypes) as well as combined with distributed memory systems. The paper focuses on viability of different shared memory architectures for parallel FDTD processing. Our analysis concerns the processing method suitable for both shared and distributed memory systems. The results of experiments comparing parallel processing efficiency on different shared memory machines are presented.

  • 375.
    Ciamulski, Tomasz
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sypniewski, M
    Warsaw University of Technology, Radioelectronics, 00 665 Warsaw, Poland.
    Different implementations of parallel processing for FDTD simulator2008In: 2008 17th International Conference on Microwaves, Radar and Wireless Communications, MIKON 2008, New York: IEEE conference proceedings, 2008, p. 641-643, article id 4630317Conference paper (Refereed)
    Abstract [en]

    Parallel processing in FDTD as well as other electromagnetic simulation methods is growing in importance. It allows not only to calculate faster but also to cope with large structures. Parallel processing can be implemented in different ways. The implementation depends mainly on computer architecture and programming libraries under different operating systems. Usually, different approach has to be taken also for a newly created program in contrary to rebuilding, existing serial program into a parallel version. A European project for development of a parallel version of existing, professional FDTD simulator is presented The simulator was principally designated for serial execution Consecutive steps of code transition from serial into versatile parallel version are described

  • 376.
    Ciamulski, Tomasz
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sypniewski, M
    Linear and superlinear speedup in parallel FDTD processing2007In: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), IEEE conference proceedings, 2007, p. 4448-4451Conference paper (Refereed)
  • 377.
    Claeson, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Mixing strings of Lithium-Ion and Lead-Acid in parallel2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this survey has been to test and analyse the behaviour of battery systems mixing parallel strings of lithium and lead acid.

    The underlying theory of why batteries of different chemistries behaves together was investigated in order to understand the resulting tests.

    Several tests were made with different products, loads and chargers in order to confirm this theory and to discover cases where the system works good and where it works bad.

    Based on this understanding a script was made in order to find a point of the least annual cost. Annual cost was then compared with systems of Lead acid only and Lithium only.

    The final goal for the script was so that a salesman can input known parameters for a backup site. Script is then adding a small Lithium battery in parallel with a fixed Lead acid battery and, increasing Lithium in size and estimating depth of discharge for Lithium and Lead acid at each step, until desired breakpoint.

    A point of minimum system cost together with Li size is then represented together with the recommended current limits.

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  • 378.
    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.

  • 379. Colas, P
    et al.
    Colijn, A P
    Fornaini, A
    Giomataris, Y
    van der Graaf, H
    Heijne, E H M
    Llopart Cudié, Xavier
    Schmitz, J
    Timmermans, J
    Visschers, J L
    The readout of a GEM or Micromegas-equipped TPC by means of the Medipix2 CMOS sensor as direct anode2004In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 535, no 1-2, p. 506-510Article in journal (Refereed)
    Abstract [en]

    We have applied the Medipix2 pixel CMOS chip as direct anode readout for a TPC. For the gas amplification two options have been investigated: (i) a three-stage GEM system and (ii) a Micromegas mesh. The structure of the cloud of primary electrons, left after interactions of 55Fe quanta with the gas is visible with unprecedented precision. This proof-of-principle is an essential step in our project to realize a monolithic pixel sensor with integrated Micromegas, to be developed specially for the readout of TPCs, and applicable for drift chambers in general.

  • 380.
    Colombo, Roberto M.
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology. University of Brescia.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sisinni, Emiliano
    Ferrari, Paolo
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Low-cost SDR-based Tool for Evaluating LoRa Satellite Communications2022In: 2022 IEEE International Symposium on Measurements and Networking, M and N 2022 - Proceedings, IEEE conference proceedings, 2022Conference paper (Refereed)
    Abstract [en]

    LoRa (Long Range) technology, with great success in providing coverage for massive Internet-of-things (IoT) deployments, is recently being considered to complement the terrestrial networks with Low Earth Orbit (LEO) satellite connectivity. The objective is to extend coverage to remote areas for various verticals, such as logistics, asset tracking, transportation, utilities, agriculture, and maritime. However, only limited studies have realistically evaluated the effects of ground-to-satellite links due to the high cost of traditional tools and methods to emulate the radio channel. In this paper, compared to an expensive channel emulator, we propose and develop an alternative method for the experimental study of LoRa satellite links using lower-cost software defined radio (SDR). Since the working details of LoRa modulation are limited to the reverse-engineered imitations, we employ such a version on SDR platform and add easily controllable adverse channel effects to evaluate LoRa for satellite connectivity. In our work, the emulation of the Doppler effect is considered as a key aspect for testing the reliability of LoRa satellite links. Therefore, after demonstrating the correctness of the (ideal) L oRa transceiver implementation, achieving a low packet error ratio (PER) with a commercial L oRa receiver, the baseband signal is distorted to emulate the Doppler effect, mimicking a real LoRa satellite communication. The Doppler effect is related to time-on-air (ToA), bounded to communication parameters and orbit height. Higher ToAs and lower orbits decrease the link duration, mainly because of dynamic Doppler effect. 

  • 381.
    Comstedt, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Effect of additional compression features on h.264 surveillance video2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In video surveillance business, a recurring topic of discussion is quality versus data usage. A higher quality allows for more details to be captured at the cost of a higher bit rate, and for cameras monitoring events 24 hours a day, limiting data usage can quickly become a factor to consider. The purpose of this thesis has been to apply additional compression features to a h.264 video steam, and evaluate their effects on the videos overall quality. Using a surveillance camera, recordings of video streams were obtained. These recordings had constant GOP and frame rates. By breaking down one of these videos to an image sequence, it was possible to encode the image sequence into video streams with variable GOP/FPS using the software Ffmpeg. Additionally a user test was performed on these video streams, following the DSCQS standard from the ITU-R recom- mendation. The participants had to subjectively determine the quality of video streams. The results from the these tests showed that the participants did not no- tice any considerable difference in quality between the normal videos and the videos with variable GOP/FPS. Based of these results, the thesis has shown that that additional compression features can be applied to h.264 surveillance streams, without having a substantial effect on the video streams overall quality.

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  • 382.
    Conti, Caroline
    et al.
    University of Lisbon, Portugal.
    Soares, Luis Ducla
    University of Lisbon, Portugal.
    Nunes, Paulo
    University of Lisbon, Portugal.
    Perra, Cristian
    University of Cagliari, Italy.
    Assunção, Pedro Amado
    Institute de Telecomunicacoes and Politecenico de Leiria, Portugal.
    Sjöström, Mårten
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Li, Yun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Olsson, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Light Field Image Compression2018In: 3D Visual Content Creation, Coding and Delivery / [ed] Assunção, Pedro Amado, Gotchev, Atanas, Cham: Springer, 2018, p. 143-176Chapter in book (Refereed)
  • 383.
    Crema, C.
    et al.
    University of Brescia, Brescia, Italy.
    Depari, A.
    University of Brescia, Brescia, Italy.
    Flammini, A.
    University of Brescia, Brescia, Italy.
    Sisinni, Emiliano
    University of Brescia, Brescia, Italy.
    Haslwanter, T.
    University of Applied Sciences Upper Austria, Linz, Austria.
    Salzmann, S.
    University of Applied Sciences Upper Austria, Linz, Austria.
    IMU-based solution for automatic detection and classification of exercises in the fitness scenario2017In: SAS 2017 - 2017 IEEE Sensors Applications Symposium, Proceedings, IEEE, 2017, article id 7894068Conference paper (Refereed)
    Abstract [en]

    Causal relationship between physical activity and prevention of several diseases has been known for some time. Recently, attempts to quantify dose-response relationship between physical activity and health show that automatic tracking and quantification of the exercise efforts not only help in motivating people but improve health conditions as well. However, no commercial devices are available for weight training and calisthenics. This work tries to overcome this limit, exploiting machine learning technique (particularly Linear Discriminant Analysis, LDA) for analyzing data coming from wearable inertial measurement units, (IMUs) and classifying/counting such exercises. Computational requirements are compatible with embedded implementation and reported results confirm the feasibility of the proposed approach, offering an average accuracy in the detection of exercises on the order of 85%.

  • 384.
    Crema, Claudio
    et al.
    University of Brescia, Brescia, Italy.
    Depari, Alessandro
    University of Brescia, Brescia, Italy.
    Flammini, Alessandra
    University of Brescia, Brescia, Italy.
    Sisinni, Emiliano
    University of Brescia, Brescia, Italy.
    Vezzoli, Angelo
    University of Brescia, Brescia, Italy.
    Bellagente, Paolo
    University of Brescia, Brescia, Italy.
    Virtual Respiratory Rate Sensors: An Example of A Smartphone-Based Integrated and Multiparametric mHealth Gateway2017In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 66, no 9, p. 2456-2463, article id 7949106Article in journal (Refereed)
    Abstract [en]

    In the last few years, several wearables appeared in the market, for fitness and healthcare applications. Such smart devices have been proposed as a possible solution for lowering the costs of healthcare, leading to the mHealth revolution. In the typical scenario, each wearable, embedding sensors, processing units and communication modules, adopts a smartphone for data collection, data displaying, and remote communication. In this paper, authors modify this paradigm simplifying the wearables (e.g., relying only on simple analog front ends and communication interfaces) and exploiting the (relatively large) computational capability of the smartphone, not only for implementing gateway features but also for processing raw biosignals as well. Several experiments verify the feasibility of the proposed approach and demonstrate that 'local' biosensor virtualization is possible, expanding possibilities of mHealth. In particular, tests have been carried out to evaluate the performance of hearth rate computation and respiratory rate virtual sensor, starting from a single-lead electrocardiogram signal. 

  • 385.
    Croci, Gabriele
    et al.
    Univ Milano Bicocca, Milan, Italy; CNR, Milan, Italy; INFN, Milan, Italy.
    Muraro, Andrea
    CNR, Milan, Italy.
    Cippo, Enrico Perelli
    CNR, Milan, Italy.
    Tardocchi, Marco
    CNR, Milan, Italy.
    Grosso, Giovanni
    Univ Milano Bicocca, Milan, Italy.
    Albani, Georgia
    Univ Milano Bicocca, Milan, Italy.
    Angella, Giuliano
    CNR, IENI, Milan, Italy.
    Defendi, Ilario
    Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, Garching, Germany.
    Hall-Wilton, Richard
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. ESS, ERIC, Lund.
    Höglund, Carina
    ESS, ERIC, Lund; Linköping Univ, Linköping.
    Raspino, Davide
    Rutherford Appleton Lab, STFC, ISIS Facil, Didcot, Oxon, England.
    Rhodes, Nigel
    Rutherford Appleton Lab, STFC, ISIS Facil, Didcot, Oxon, England.
    Robinson, Linda
    ESS, ERIC, Lund.
    Schmidt, Susan
    ESS, ERIC, Lund.
    Schooneveld, Erik
    Rutherford Appleton Lab, STFC, ISIS Facil, Didcot, Oxon, England.
    Zeitelhack, Karl
    Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, Garching, Germany.
    Gorini, Giuseppe
    CNR, IFP, Milan, Italy; ESS, ERIC, Lund.
    A high-efficiency thermal neutron detector based on thin 3D (B4C)-B-10 converters for high-rate applications2018In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 123, no 5, article id 52001Article in journal (Refereed)
    Abstract [en]

    new position-sensitive thermal neutron detector based on boron-coated converters has been developed as an alternative to today's standard He-3-based technology for application to thermal neutron scattering. The key element of the development is a novel 3D (B4C)-B-10 converter which has been ad hoc designed and realized with the aim of combining a high neutron conversion probability via the B-10(n, alpha)(7) Li reaction together with an efficient collection of the produced charged particles. The developed 3D converter is composed of thin aluminium grids made by a micro-waterjet technique and coated on both sides with a thin layer of( 10)B(4)C. When coupled to a GEM detector this converter allows reaching neutron detection efficiencies close to 50% at neutron wavelengths equal to 4 angstrom. In addition, the new detector features a spatial resolution of about 5 min and can sustain counting rates well in excess of 1 MHz/cm(2). The newly developed neutron detector will enable time-resolved measurements of different kind of samples in neutron scattering experiments at high flux spallation sources and can find a use in applications where large areas and custom geometries of thermal neutron detectors are foreseen. 

  • 386. Cui, Enfang
    et al.
    Yang, Dong
    Zhang, Hongke
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Improving Power Stability of Energy Harvesting Devices with Edge Computing Assisted Time Fair Energy Allocation2021In: IEEE Transactions on Green Communications and Networking, ISSN 2473-2400, Vol. 5, no 1, p. 540-551Article in journal (Refereed)
    Abstract [en]

    Due to the time-varying characteristics of energy harvesting sources, it is a challenge for energy harvesting to provide stable energy output. In this paper, the time fair energy allocation (TFEA) problem is investigated, and an utility maximization framework is proposed to guarantee both time fairness and energy efficiency of energy allocation. Then we propose a prediction based energy allocation scheme. First, a deep learning predictor is used to predict the harvested energy. Second, we transform the TFEA problem into an Euclidean shortest path problem and propose a fast time fair energy allocation algorithm (FTF) based on inflection points search. Our algorithm can significantly decrease the iteration number of the shortest path search and reduce the computation time. In addition, we propose an edge computing assisted energy allocation framework, in which the computing tasks are offloaded to edge gateways. The proposed scheme is evaluated in the scenario of metro vehicles health monitoring. Experiment results show that the time consumption of FTF is at least 92.2% lower than traditional algorithms, while the time fairness of FTF is the best. The total time cost and energy cost of our edge computing scheme is also competitive compared with traditional local computing schemes. 

  • 387.
    Dadash Pour Khalkhali, Mohammad Mehdi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    User Experience Enhancement in 3D Video Conferencing2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    3D video conferencing is continuously evolving to make the visual experience realistic. The main advantage of 3D video conferencing deals with the addition of depth perception which enhances the user experience. The configuration of capturing and rendering equipments and the location of scene objects play an essential role in the quality of the user experience. An incorrect configuration of equipment parameters or an inconsistent distribution of scene components could cause an uncomfortable user experience, yielding in user sickness and dizziness.

    The aim of this thesis is therefore to provide the tools and methods to assure a comfortable user experience when using Ericsson’s stereoscopic 3D video conferencing system. To achieve this goal, an investigation on the capturing and rendering systems has been performed to identify possible conflicts. This investigation has shown that accommodation-convergence rivalry, comfortable viewing range and stereo framing violation are the major sources of user discomfort in 3D video conferencing.

    An algorithm for continuous analysis of produced stereoscopic content has been proposed. In particular, it detects wrong equipment configuration and problematic content in real time by means of automatic adjustments or user interaction, either at initiation phase or during the call session at capturing side. To validate and evaluate the efficiency of the implemented solution, a subjective test with participation of the 3D experts has been carried out. It has been shown that the proposed solution can detect targeted problems with high accuracy and apply corrective actions. It is important to note that manual solutions are not immune to problems. Nevertheless, it has also been shown that automatic solutions can considerably compensate manual methods inconsistency and provide a comfortable user experience. 

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    User Experience Enhancemen in 3D Video Conferencing
  • 388.
    Dahlin, Karl
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    An Evaluation of Spring WebFlux: With focus on built in SQL features2020Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today’s society the need for more hardware efficient software since some people think that the doubling of computer power for the same price that Moore’s law predicted is no more. Reactive programming can be a

    step in the right direction, this has led to an increase in interest in reactive programming. This object of this thesis is to evaluate the possibility of using reactive programming and R2DBC in Java to communicate with a relation database. This has been done by creating two Spring applications

    one using the standards JDBC and servlet stack and one using R2DBC and the reactive stack. Then connecting them to a MySQL database and selecting and inserting values in to and from it and measuring the CPU usage, memory usage and execution time. In addition to this the possibilities to handle BLOBs in a good enough way were researched. The study shows that there are both advantages and disadvantages with using R2DBC it has basic support and it is based on good idea but at the time of this thesis it still needs more development before it can be used fully.

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  • 389.
    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.

     

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  • 390. 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.

  • 391.
    Damghanian, Mitra
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    The Sampling Pattern Cube: A Framework for Representation and Evaluation of Plenoptic Capturing Systems2013Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Digital cameras have already entered our everyday life. Rapid technological advances have made it easier and cheaper to develop new cameras with unconventional structures. The plenoptic camera is one of the new devices which can capture the light information which is then able to be processed for applications such as focus adjustments. The high level camera properties, such as the spatial or angular resolution are required to evaluate and compare plenoptic cameras. With complex camera structures that introduce trade-offs between various high level camera properties, it is no longer straightforward to describe and extract these properties. Proper models, methods and metrics with the desired level of details are beneficial to describe and evaluate plenoptic camera properties.

    This thesis attempts to describe and evaluate camera properties using a model based representation of plenoptic capturing systems in favour of a unified language. The SPC model is proposed and it describes which light samples from the scene are captured by the camera system. Light samples in the SPC model carry the ray and focus information of the capturing setup. To demonstrate the capabilities of the introduced model, property extractors for lateral resolution are defined and evaluated. The lateral resolution values obtained from the introduced model are compared with the results from the ray-based model and the ground truth data. The knowledge about how to generate and visualize the proposed model and how to extract the camera properties from the model based representation of the capturing system is collated to form the SPC framework.

    The main outcomes of the thesis can be summarized in the following points: A model based representation of the light sampling behaviour of the plenoptic capturing system is introduced, which incorporates the focus information as well as the ray information. A framework is developed to generate the SPC model and to extract high level properties of the plenoptic capturing system. Results confirm that the SPC model is capable of describing the light sampling behaviour of the capturing system, and that the SPC framework is capable of extracting high level camera properties with a higher descriptive level as compared to the ray-based model. The results from the proposed model compete with those from the more elaborate wave optics model in the ranges that wave nature of the light is not dominant. The outcome of the thesis can benefit design, evaluation and comparison of the complex capturing systems.

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    MitraDamghanianLicThesis
  • 392.
    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.
    Extraction of the lateral resolution in a plenoptic camera using the SPC model2012In: 2012 International Conference on 3D Imaging, IC3D 2012 - Proceedings, IEEE conference proceedings, 2012, p. Art. no. 6615137-Conference paper (Refereed)
    Abstract [en]

    Established capturing properties like image resolution need to be described thoroughly in complex multidimensional capturing setups such as plenoptic cameras (PC), as these introduce a trade-off between resolution and features such as field of view, depth of field, and signal to noise ratio. Models, methods and metrics that assist exploring and formulating this trade-off are highly beneficial for study as well as design of complex capturing systems. This work presents how the important high-level property lateral resolution is extracted from our previously proposed Sampling Pattern Cube (SPC) model. The SPC carries ray information as well as focal properties of the capturing system it models. The proposed operator extracts the lateral resolution from the SPC model throughout an arbitrary number of depth planes resulting in a depth-resolution profile. We have validated the resolution operator by comparing the achieved lateral resolution with previous results from more simple models and from wave optics based Monte Carlo simulations. The lateral resolution predicted by the SPC model agrees with the results from wave optics based numerical simulations and strengthens the conclusion that the SPC fills the gap between ray-based models and wave optics based models, by including the focal information of the system as a model parameter. The SPC is proven a simple yet efficient model for extracting the depth-based lateral resolution as a high-level property of complex plenoptic capturing system.

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    fulltext
  • 393.
    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.

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    fulltext
  • 394.
    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.

  • 395.
    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.
    Erdmann, Arne
    Raytrix Gmbh.
    Perwass, Christian
    Raytrix Gmbh.
    Spatial resolution in a multi-focus plenoptic camera2014In: IEEE International Conference on Image Processing, ICIP 2014, IEEE conference proceedings, 2014, p. 1932-1936, article id 7025387Conference paper (Refereed)
    Abstract [en]

    Evaluation of the state of the art plenoptic cameras is necessary for design and application purposes. In this work, spatial resolution is investigated in a multi-focus plenoptic camera using two approaches: empirical and model-based. The Raytrix R29 plenoptic camera is studied which utilizes three types of micro lenses with different focal lengths in a hexagonal array structure to increase the depth of field. The modelbased approach utilizes the previously proposed sampling pattern cube (SPC) model for representation and evaluation of the plenoptic capturing systems. For the experimental resolution measurements, spatial resolution values are extracted from images reconstructed by the provided Raytrix reconstruction method. Both the measurement and the SPC model based approaches demonstrate a gradual variation of the resolution values in a wide depth range for the multi focus R29 camera. Moreover, the good agreement between the results from the model-based approach and those from the empirical approach confirms suitability of the SPC model in evaluating high-level camera parameters such as the spatial resolution in a complex capturing system as R29 multi-focus plenoptic camera.

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    Damghanian_Spatial_resolution
  • 396.
    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.
    Navarro Fructuoso, Hector
    Department of Optics, University of Valencia, Spain.
    Martinez Corral, Manuel
    Department of Optics, University of Valencia, Spain.
    Investigating the lateral resolution in a plenoptic capturing system using the SPC model2013In: Proceedings of SPIE - The International Society for Optical Engineering: Digital photography IX, SPIE - International Society for Optical Engineering, 2013, p. 86600T-Conference paper (Refereed)
    Abstract [en]

    Complex multidimensional capturing setups such as plenoptic cameras (PC) introduce a trade-off between various system properties. Consequently, established capturing properties, like image resolution, need to be described thoroughly for these systems. Therefore models and metrics that assist exploring and formulating this trade-off are highly beneficial for studying as well as designing of complex capturing systems. This work demonstrates the capability of our previously proposed sampling pattern cube (SPC) model to extract the lateral resolution for plenoptic capturing systems. The SPC carries both ray information as well as focal properties of the capturing system it models. The proposed operator extracts the lateral resolution from the SPC model throughout an arbitrary number of depth planes giving a depth-resolution profile. This operator utilizes focal properties of the capturing system as well as the geometrical distribution of the light containers which are the elements in the SPC model. We have validated the lateral resolution operator for different capturing setups by comparing the results with those from Monte Carlo numerical simulations based on the wave optics model. The lateral resolution predicted by the SPC model agrees with the results from the more complex wave optics model better than both the ray based model and our previously proposed lateral resolution operator. This agreement strengthens the conclusion that the SPC fills the gap between ray-based models and the real system performance, by including the focal information of the system as a model parameter. The SPC is proven a simple yet efficient model for extracting the lateral resolution as a high-level property of complex plenoptic capturing systems.

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    fulltext
  • 397.
    Dancila, Dragos
    et al.
    Angstrom Laboratory, Division of Solid-State Electronics, Uppsala University, Uppsala, Sweden .
    Moossaavi, Reza
    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.
    Zhang, Zhibin
    Angstrom Laboratory, Division of Solid-State Electronics, Uppsala University, Uppsala, Sweden .
    Rydberg, Anders
    Angstrom Laboratory, Division of Solid-State Electronics, Uppsala University, Uppsala, Sweden .
    Antennas on Paper Using Ink-Jet Printing of Nano-Silver Particles for Wireless Sensor Networks in Train Environment2016In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 58, no 4, p. 754-759Article in journal (Refereed)
    Abstract [en]

    This article presents the design, manufacturing, and measurements of antennas on paper, realized using ink-jet printing of conductive inks based on nano-silver particles (nSPs). The extraction of the substrate characteristics such as the dielectric constant and dielectric loss is performed using a printed ring resonator technique. The characterization of the nSPs conductive inks assesses different parameters as sintering time and temperature. Two antennas are realized corresponding to the most common needs for wireless sensor networks in Trains Environment. The first one is a patch antenna characterized by a broadside radiation pattern and suited for operation on metallic structures. The second one is a quasi-yagi antenna, with an end fire radiation pattern and higher directivity, without requiring a metallic ground plane. Both antennas present a good matching (S11 < -20 dB and S11 < -30 dB, respectively) and acceptable efficiency (55% and 45%, respectively) for the paper substrate used at the center frequency of 2.4 GHz, corresponding to the first channel of the IEEE 802.15.4 band.

  • 398.
    Danielson, Mats
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Ekenberg, Love
    Dept. of Computer and Systems Sciences, Stockholm University.
    Larsson, Aron
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Generalised Risk Constraints in Decision Trees with Second-Order Probabilities2012In: Advances in Economics, Risk Management, Political and Law Science / [ed] D. Pavelkova, J. Strouhal, M. Pasekova, WSEAS Press , 2012, p. 376-383Conference paper (Refereed)
    Abstract [en]

    Recently, representations and methods analysing decision problems where probabilities and values (utilities) are associated with belief 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 impreciseprobabilities and utilities. We discuss some shortcomings in the use of the principle of maximising the expectedutility 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.

  • 399.
    Danielson, Mats
    et al.
    Dept. of Computer and Systems Sciences, Stockholm University.
    Ekenberg, Love
    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.
    Riabacke, Mona
    Dept. of Computer and Systems Sciences, Stockholm University.
    Weighting Under Ambiguous Preferences and Imprecise Differences in a Cardinal Rank Ordering Process2013In: International Journal of Computational Intelligence Systems, ISSN 1875-6883, Vol. 7, no 1, p. 105-112Article in journal (Refereed)
    Abstract [en]

    The limited amount of good tools for supporting elicitation of preference information in multi-criteria decision analysis (MCDA) causes practical problem. In our experiences, this can be remedied by allowing more relaxed input statements from decision-makers, causing the elicitation process to be less cognitively demanding. Furthermore, it should not be too time consuming and must be able to actually use of the information the decision-maker is able to supply. In this paper, we propose a useful weight elicitation method for MAVT/MAUT decision making, which builds on the ideas of rank-order methods, but increases the precision by adding numerically imprecise cardinal information as well.

  • 400.
    Darborg, Alex
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Real-time face recognition using one-shot learning: A deep learning and machine learning project2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Face recognition is often described as the process of identifying and verifying people in a photograph by their face. Researchers have recently given this field increased attention, continuously improving the underlying models. The objective of this study is to implement a real-time face recognition system using one-shot learning. “One shot” means learning from one or few training samples. This paper evaluates different methods to solve this problem. Convolutional neural networks are known to require large datasets to reach an acceptable accuracy. This project proposes a method to solve this problem by reducing the number of training instances to one and still achieving an accuracy close to 100%, utilizing the concept of transfer learning.

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