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  • 101. Pasanen, Jari
    et al.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Locally clocked AFSMs using dynamic latch implementation1999In: Electronics, Circuits and Systems, 1999. Proceedings of ICECS '99. The 6th IEEE International Conference on: Vol 3, 1999, p. 1643-1646Conference paper (Refereed)
    Abstract [en]

    Asynchronous Finite State Machines (AFSMs) have been proposed to be used in designs where the demands on high speed or low power consumption are high. In this paper we present a synthesis procedure for a type of AFSMs called locally clocked state machines with dynamic latch implementation. The use of dynamic latches makes it possible to reduce input capacitances and the number of transistors. It also enables efficient implementation of gates with monotonic output transitions which is important in AFSM design. We (1) show what implications the use of dynamic gates have on the synthesis procedure, (2) define state constraints and requirements on these circuits, and (3) present a complete procedure for implementing AFSMs through an example

  • 102.
    Rusu, C.
    et al.
    RISE, Sensor Systems department, Acreo.
    Bader, Sebastian
    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.
    Alvandpour, A.
    Linköping University.
    Enoksson, P.
    Chalmers Univ. of Technology, Gothenburg.
    Braun, T.
    Fraunhofer-IZM, Berlin, Germany.
    Tiedke, S.
    aixACCT Systems GmbH, Aachen, Germany.
    Molin, R. Dal
    Cairdac, Clamart, France.
    Férin, G.
    Vermon SA, Tours, France.
    Torvinen, P.
    Spinverse Innovation Management Oy, Espoo, Finland.
    Liljeholm, J.
    Silex Microsystems AB, Järfälla.
    Challenges for Miniaturised Energy Harvesting Sensor Systems2018In: 2018 10th International Conference on Advanced Infocomm Technology (ICAIT), 2018, p. 214-217Conference paper (Refereed)
  • 103.
    Shahzad, Khurram
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Cheng, Peng
    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.
    Architecture exploration for a high-performance and low-power wireless vibration analyzer2013In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 2, p. 670-682Article in journal (Refereed)
    Abstract [en]

    Vibration based condition monitoring is considered to be the most effective method for analyzing the performance of rotating machinery and for early fault detection. Traditional vibration analyzers used for this purpose provide wired interface(s) to connect sensors with the system that analyzes the vibration data. A wireless vibration analyzer can be useful to monitor and analyze the vibration of rotating as well as inaccessible parts of the machinery. However, for a wireless vibration analyzer, both the performance and power consumption are of major concern, especially for real-time tri-axes (horizontal, vertical, and axial) vibration data processing and analyses at a high sampling rate. To evaluate the performance of such an analyzer, we explore different architectures in order to realize a high-performance and low-power wireless vibration analyzer that can be used in addition to traditional analyzers. For this purpose, four different architectures have been implemented in order to evaluate them in terms of performance, power consumption, cost, and design complexity.

  • 104.
    Shahzad, Khurram
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Cheng, Peng
    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.
    Feasibility study of on-Rotor Vibration Monitoring using AccelerometersManuscript (preprint) (Other academic)
    Abstract [en]

    Vibration based condition monitoring is the most widely accepted method for determining the defects and the performance degradation of rotating machinery. Common practices for monitoring vibration involve employing a displacement transducer for the rotor and an accelerometer for the stator. This paper presents a novel architecture for on-rotor vibration measurement based on accelerometers, and a high sampling rate vibration monitoring sensor node with analysis capability. A detailed analysis of the technological challenges and bottlenecks including bandwidth, wireless communication, processing capabilities and energy consumption of the proposed architecture are discussed. The experimental results of the rotor and the stator vibration are compared and are presented.   

  • 105.
    Shahzad, Khurram
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Cheng, Peng
    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.
    SENTIOF: An FPGA based high-performance and low-power wireless embedded platform2013In: 2013 Federated Conference on Computer Science and Information Systems, FedCSIS 2013: Proceedings, IEEE conference proceedings, 2013, p. 901-906Conference paper (Refereed)
    Abstract [en]

    Traditional wireless sensor nodes are designed with low-power modules that offer limited computational performance and communication bandwidth and therefore, are generally applicable to low-sample rate intermittent monitoring applications. Nevertheless, high-sample rate monitoring applications can be realized by designing sensor nodes that can perform high-throughput in-sensor processing, while maintaining low-power characteristics. In this paper, a high-performance and low-power wireless hardware platform is presented. With its compact size and modular structure enabling there to be an integrated customized sensor layer, it can be used for a wide variety of applications. In addition, the flexibility provided through dynamically configurable interfaces and power management, helps optimizing performance and power consumption for different applications.

  • 106.
    Shahzad, Khurram
    et al.
    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.
    A comparative study of in-sensor processing vs. raw data transmission using ZigBee, BLE and Wi-Fi for data intensive monitoring applications2014In: 2014 11th International Symposium on Wireless Communications Systems, ISWCS 2014 - Proceedings, IEEE conference proceedings, 2014, p. 519-524Conference paper (Refereed)
    Abstract [en]

    Wireless sensor nodes, as typically realized using IEEE 802.15.4 compatible low-power radio transceivers that offer limited throughput, are generally applicable to low-data rate intermittent monitoring applications. In order to realize high sample rate monitoring applications, it requires either transmitting raw data using a high-throughput radio transceiver or performing computation within the sensor node and then transmitting a small amount of information. In relation to a energy constrained wireless sensing node, a quantitative evaluation of raw data transmission using different short range wireless technologies and in-sensor processing is conducted in this paper. The results, associated with the energy consumption of two data intensive monitoring applications, suggest that in-sensor processing resulting in a small amount of data to be transmitted consumes less energy as compared to that of raw data transmission, even under ideal channel conditions.

  • 107.
    Shahzad, Khurram
    et al.
    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.
    A comparative study of raw data transmission using ZigBee, BLE and Wi-Fi vs. in-sensor processing for data intensive monitoring applicationsManuscript (preprint) (Other academic)
    Abstract [en]

    Wireless sensor nodes, as typically realized using IEEE 802.15.4 compatible low-power radio transceivers that offer limited throughput, are generally applicable to low-data rate intermittent monitoring applications. In order to realize high sample rate monitoring applications, it either requires transmitting raw data using a high-throughput radio transceiver or performing computation within the sensor node and then transmitting small amount of information. In relation energy constrained wireless sensing node, a quantitative evaluation of raw data transmission using different short range wireless technologies and in-sensor processing is carried out in this paper. The results, associated with the energy consumption of two data intensive monitoring applications, suggest that in-sensor processing resulting in small amount of transmission data consume less energy as compared to that of raw data transmission under ideal channel conditions.

  • 108.
    Shahzad, Khurram
    et al.
    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.
    An FPGA-Based High-Performance Wireless Vibration Analyzer2013In: NORCHIP 2013, 2013, p. Art. no. 6702038-Conference paper (Refereed)
    Abstract [en]

    In this article, an Field Programmable Gate Array (FPGA) based high-performance wireless vibration analyzer that performs high sample rate tri-axes (horizontal, vertical, and axial) vibration monitoring and analysis, is presented. The custom designed compact size wireless analyzer can be mounted on difficult to access as well as rotating parts of the machinery so as to perform vibration based condition monitoring. Based on the measured performance and power consumption, the analyzer not only achieves the performance goals for high-sample rate (i.e. at 50 kHz) tri-axes vibration data processing but, also achieves operational lifetime of more than three years for duty-cycle durations of more than 4 hours.

  • 109.
    Shahzad, Khurram
    et al.
    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.
    Investigating Energy Consumption of an SRAM-based FPGA for Duty-Cycle Applications2014In: Advances in parallel computing, 2014, p. 548-559Conference paper (Refereed)
    Abstract [en]

    In order to conserve energy, battery powered embedded systems are typically designed with very low-power modules that offer limited computational power and communication bandwidth and therefore, are generally applicable to low-sample-rate intermittent applications. On the other hand, enabling an embedded system with a high-throughput processing resource such as an FPGA, high-throughput processing performance that is typically required in high-sample rate monitoring applications can be achieved. However, the high power consumption associated with an FPGA poses a major challenge in attaining significant lifetime for a battery-powered embedded system. In this paper, we investigate energy consumption of an SRAM-based FPGA in relation to duty-cycle applications. In order to achieve long operational lifetime in an FPGA-based embedded system, the possible options to dynamically manage the power consumption are studied and discussed. The experimental results suggest that the SRAM-based FPGA, XC6SLX16 that provides ample logic resources in relation to typical high-sample rate monitoring applications, can be used in a battery operated embedded systems while minimizing the energy consumption to 2.56 mJ for inactive duration of 235 ms or above.

  • 110.
    Shahzad, Khurram
    et al.
    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.
    Quantitative Evaluation of an FPGA based Wireless Vibration Monitoring System in relation to Different Sampling Rates2014In: Proceedings of the International Conference on Sensing Technology, ICST, IEEE Computer Society, 2014, Vol. 2014, p. 510-516Conference paper (Refereed)
    Abstract [en]

    In order to achieve the high-processing performance  required in typical computationally intensive high-sample rate monitoring applications, a Field Programmable Gate Array (FPGA) is often used as a hardware accelerator.  Given the design complexity, increased power consumption and additional cost of an FPGA, it is desirable to determine the sampling rates for which the use of an FPGA as hardware accelerator results in most effective solution. For this purpose, a computationally intensive application is realized on an FPGA based architecture so as to determine the sampling rates for which it achieves the highest performance and consumes the least amount of energy as compared to that of a micro-controller based architecture. Based on the measured performance and energy consumption for a computationally intensive application, tri-axes/three-channel vibration based condition monitoring, the results suggest that the FPGA based architecture is the most appropriate solution for sampling frequencies of 4 kHz and above.

  • 111.
    Thim, Jan
    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.
    O'Nils, Matthias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Abdalla, Suliman
    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.
    Realizing increased sub-pixel spatial resolution in X-ray imaging using displaced multiple images2011In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 633, no Suppl 1, p. S247-S249Article in journal (Refereed)
    Abstract [en]

    A method, generally called oversampling, to reach sub-pixel resolution by taking slightly displaced images of an object is investigated for X-ray applications. By mounting the sensor on a high precision step motor table it is possible to increase the spatial resolution from 55 ÎŒm×55 ÎŒm to at least 20 ÎŒm×20 ÎŒm, which is required for quality assurance measurements in several industry processes. The performance compared to physically smaller pixels is shown, and the effects of charge sharing on the method are investigated. The suggested method is relatively cost effective compared to using X-ray microscopy. © 2010 Elsevier B.V. All rights reserved.

  • 112.
    Thim, Jan
    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.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Abdalla, Suliman
    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.
    Realizing increased sub-pixel spatial resolution in X-ray imaging using displaced multiple images2009In: 11th International Workshop on Radiation Imaging Detectors, 2009Conference paper (Refereed)
    Abstract [en]

    In X-Ray imaging with pixel detector systems, the resolution of the image taken is dependant on the pixel size in the detector readout electronics. Depending on the functionality of the readout electronics, the surface space on the readout chip for each pixel has a minimum size, which sets the spatial resolution of the taken images. For applications where it is required to image extremely small structures in a material, the spatial resolution of the X-Ray detector system sets the limit, and readout systems with high functionality cannot be considered. One way to reach sub-pixel resolution is to use a nanofocus source to achieve an X-ray microscopy setup [1]. However, this type of X-ray source is still too expensive to be an alternative for quality assurance systems used in the industry. In this paper we focus on a much simpler way of increasing spatial resolution that has proven effective in images for visible light. By mounting either the objects for imaging or the image sensor system on a step motor table and take multiple images slightly dislocated from one another, an increase in sub-pixel spatial resolution can be achieved.

    Consider the case that an image sensor system with a pixel size of 55x55 µm is available for an imaging application that requires a resolution of 20x20 µm. The application is material characterization and allows for multiple images to be taken for one sample. In this case, increasing the sub-pixel resolution by nine times (3x3) will result in a pixel size of about 18x18 µm, which would meet the requirements. This can be realized by taking nine images dislocated 1/3 of the pixel width from each other. If the upper left pixel of the centre image has coordinates (0,0) the upper left pixel of all the nine images will have coordinates (-1/3,1/3), (0,1/3), (1/3,1/3), (-1/3,0), (0,0), (1/3,0), (-1/3,-1/3), (0,-1/3) and (1/3,-1/3). The result of a direct combination of these images is illustrated in Figure 1, where one of nine images is shown at the left. Combining the images without images processing with an algorithm will yield the image in the centre, which can be compared to how the image would look in full 9x resolution (right image). As can be seen, some details are lost and the image is blurred compared to a full resolution image. However, with an image processing algorithm in the combination phase this effect can be reduced and the image quality increased.

    This paper shows simulated and measured results from using dislocation imaging in X-Ray imaging systems, where the test case system will be the MEDIPIX2 system [2]. An investigation of different image processing algorithms suitable for this type of imaging is conducted. An investigation is also done to show whether detectors with large size pixels compared to the standard size in a MEDIPIX system can be combined with the described sub-pixel scaling technique. The result of this combination is used to investigate the charge sharing effects on the MEDIPIX system.

    [1] Norlin B., Fröjdh C., Nuclear Instruments and Methods, sect. A (2009), doi:10.1016/j.nima.2009.03.155[2] Llopart X., Campbell M., Dinapoli R., san Segundo D., Pernigotti E., IEEE Transactions on Nuclear Science, Vol. 49, Issue 5, Part 1, pp. 2279-2283, October 2002.

    Figure 1. Image (left) with 50x50 pixels, with the resulting combination of nine images forming an image with a sub-pixel resolution of 150x150 pixel (centre), compared to a full resolution reference image (right).

  • 113.
    Thim, Jan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Reza, Salim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nawaz, Khalid
    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.
    O´Nils, Mattias
    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.
    Suitable Post Processing Algorithms for X-Ray Imaging using Oversampled Displaced Multiple Images2011In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 6, no 2, p. Art. no. C02001-Article in journal (Refereed)
    Abstract [en]

    X-ray imaging systems such as photon counting pixel detectors have a limited spatial resolution of the pixels, based on the complexity and processing technology of the readout electronics. For X-ray imaging situations where the features of interest are smaller than the imaging system pixel size, and the pixel size cannot be made smaller in the hardware, alternative means of resolution enhancement require to be considered. Oversampling with the usage of multiple displaced images, where the pixels of all images are mapped to a final resolution enhanced image, has proven a viable method of reaching a sub-pixel resolution exceeding the original resolution. The effectiveness of the oversampling method declines with the number of images taken, the sub-pixel resolution increases, but relative to a real reduction of imaging pixel sizes yielding a full resolution image, the perceived resolution from the sub-pixel oversampled image is lower. This is because the oversampling method introduces blurring noise into the mapped final images, and the blurring relative to full resolution images increases with the oversampling factor. One way of increasing the performance of the oversampling method is by sharpening the images in post processing. This paper focus on characterizing the performance increase of the oversampling method after the use of some suitable post processing filters, for digital X-ray images specifically. The results show that spatial domain filters and frequency domain filters of the same type yield indistinguishable results, which is to be expected. The results also show that the effectiveness of applying sharpening filters to oversampled multiple images increase with the number of images used (oversampling factor), leaving 60-80% of the original blurring noise after filtering a 6 x 6 mapped image (36 images taken), where the percentage is depending on the type of filter. This means that the effectiveness of the oversampling itself increase by using sharpening filters, and more images taken can be considered worth the effort.

  • 114.
    Unander, Tomas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Printed touch sensor for interactive packaging and display2007In: Polytronic 2007: the 6th International IEEE Conference on Polymers and Adhesives in Microelectronics and Photonics, IEEE conference proceedings, 2007, p. 12-17Conference paper (Other academic)
    Abstract [en]

    In this work we present a study on the performance of printed touch sensor fabricated using conductive ink on paper substrates. The sensor system is intended to add values in surveillance of packages or in interactive point-of-purchase displays. The printed sensor changes its capacitance when it is touched or manipulated. The capacitance variations are readout using either a wireless or wired communication link. The most advanced system will utilize RFID or ZigBee readout technology while the simplest systems utilize a simple analog wire solution. The sensor technology has been developed to be easily integrated into high quality prints targeting applications such as large area touch sensitive commercial stands, flat keyboards at point-of-purchase and touch and manipulation surveillance in logistic chains.

  • 115.
    Wang, Xiasong
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Rödjegård, H
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Martin, H
    Larsson, B
    High performance CO2 measurement based on pressure modulation2010In: Proceedings of 24th Eurosensors Conference, Elsevier, 2010, p. 1208-1211Conference paper (Refereed)
    Abstract [en]

    Herein pressure modulation is proposed as a method to increase the resolution as well as to eliminate long term drift of NDIR gas sensors. Measurements are presented that verifies the theoretical predictions of possibility to drift compensation and resolution improvement. The resolution is increased 8.6 times when the pressure is changed from atmospheric to 900 kPa. The method can be applied to existing sensors for both resolution improvement and drift compensation.

  • 116.
    Xu, Ye
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bader, Sebastian
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Magno, Michele
    Dept. of Information Technology and Electrical Engineering, ETH Zurich.
    Mayer, Philipp
    Dept. of Information Technology and Electrical Engineering, ETH Zurich.
    Oelmann, Bengt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Energy-autonomous On-rotor RPM Sensor Using Variable Reluctance Energy Harvesting2019In: 2019 IEEE 8th International Workshop on Advances in Sensors and Interfaces (IWASI), IEEE, 2019, p. 175-180, article id 08791251Conference paper (Refereed)
    Abstract [en]

    Energy-autonomous wireless sensor systems have the potential to enable condition monitoring without the need for a wired electrical infrastructure or capacity-limited batteries. In this paper, a robust and low-cost energy-autonomous wireless rotational speed sensor is presented, which harvests energy from the rotary motion of its host using the variable reluctance principle. A microelectromechanical system (MEMS) gyroscope is utilized for angular velocity measurements, and a Bluetooth Low Energy System-on-Chip (SoC) transmits the acquired samples wirelessly. An analysis on the individual subsystems is performed, investigating the output of the energy transducer, the required energy by the load, and energy losses in the whole system. The results of simulations and experimental measurements on a prototype implementation show that the system achieves energy-autonomous operation with sample rates between 1 to 50 Hz already at 10 to 40 rotations per minute. Detailed investigations of the system modules identify the power management having the largest potential for further improvements.

  • 117.
    Xu, Ye
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bader, Sebastian
    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.
    A Survey on Variable Reluctance Energy Harvesters in Low-Speed Rotating Applications2018In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 18, no 8, p. 3426-3435Article in journal (Refereed)
    Abstract [en]

    Energy harvesting converts ambient energy to electrical energy that can be used to power, for example, sensors and sensor systems. Variable reluctance energy harvesting is a suitable candidate for the conversion of rotary kinetic motion, an energy form commonly found in industrial applications. The implementation of a variable reluctance energy harvester, however, has a significant effect on its performance and is not well studied. In this paper, we therefore conduct a survey on different structures of variable reluctance energy harvesters. Six existing structures, previously used in variable reluctance sensors, are presented and analyzed according to their approaches for magnetic flux change improvement. Together with a newly proposed structure, these structures are evaluated based on a finite element analysis, and their results are compared. It is demonstrated that the choice of structure considerably affects the power output of the harvester and is dependent on the improvement approaches the structure utilizes. The newly proposed structure outperforms all existing structures with respect to power output and power density, which comes at a cost of higher parasitic torque generation. A 53-fold power improvement over the reference and an 1.2-fold power improvement over the next best structure is observed. As a result, applications of variable reluctance energy harvesting become viable even at low angular velocities.

  • 118.
    Xu, Ye
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Bader, Sebastian
    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.
    Design, modeling and optimization of an m-shaped variable reluctance energy harvester for rotating applications2019In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 195, p. 1280-1294Article in journal (Refereed)
    Abstract [en]

    The variable reluctance principle can be used to convert rotational kinetic energy into electrical energy, creating a Variable Reluctance Energy Harvester (VREH) based on electromagnetic induction. This can be used to implement self-sustaining wireless sensors in rotating applications. In this paper, we present and investigate a novel design of a VREH with high volumetric power density that targets low-speed rotating applications. The design uses an m-shaped pole-piece and two opposing magnets. We theoretically analyze key design parameters that influence the VREH’s output power, and relate these parameters to geometrical design factors of the proposed structure. Key design factors include the coil height, the permanent magnet height and the tooth height. A method based on numerical simulations is introduced, enabling to determine the optimal geometrical dimensions of the proposed structure under given size-constraints. The results demonstrate that the method leads to optimal structure configurations, which has been evaluated for different cases and is verified experimentally. Good agreement between numerical simulations and experiments are reported with deviations in output power estimation below 3%. The optimized m-shaped VREH, moreover, provides output power levels sufficient for wireless sensor operation, even in low-speed rotating applications.

  • 119.
    Xue, Shang
    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.
    A Coding Method for UVLC Targeting Efficient Decoder Architecture2003In: Proceedings of the 3rd IEEE Internatioal Symposium on Image and Signal Processing and Analysis, Rome, Italy, September, 2003, 2003, p. 428-433Conference paper (Refereed)
    Abstract [en]

    Variable length code (VLC) is used in a large variety of lossless compression applications. A specially designed VLC, called "Universal Variable Length Code" (UVLC), is utilized in the latest video coding standard H.26L under development. In this work we propose a coding method that we call "Alternating Coding" (ALT coding) for UVLC. An efficient UVLC decoder is designed (ALT decoder) on the basis of it. ALT coding facilitates a much easier decoding scheme for UVLC. It frees the decoder from codeword tables and the sizes of the barrel shifters are reduced. The codeword tables and barrel shifters usually occupy the largest portion of the area in the traditional VLC decoders and they are also performance limiting in terms of speed and power consumption. We compare the ALT decoder with one of the most efficient VLC decoders called "VLC decoder using plane separation" (PLS). Our results show that the ALT decoder increases 25% in speed, decreases 41% in size, and consumes 45% power of the PLS decoder.

  • 120.
    Xue, Shang
    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.
    Alternating Coding for Universal Variable Length Code2003In: Procceedings of the IEEE International Conference on Image Processing, Barcelona, Spain, September, 2003, IEEE , 2003, p. 477-480Conference paper (Refereed)
    Abstract [en]

    Variable length code (VLC) is used in a large variety of lossless compression applications. A specially designed VLC, called "Universal Variable Length Code" (UVLC), is utilized in the latest video coding standard H.26L under development. In this work we propose a new coding method under the name "Alternating Coding" (ALT coding) and apply it to the UVLC The ALT coded UVLC yields the same high coding efficiency as the original UVLC, but ALT coding also enables immediate decoding, immediate error detection and location in a UVLC packet. It improves the error resiliency and error robustness of the UVLC packet by applying an "error speculation". Results show that the ALT coded UVLC packet always outperforms the original UVLC packet in terms of error resiliency and robustness. Moreover the simple pattern of ALT coded UVLC can greatly simplify the UVLC decoder architecture and therefore enables small, fast, and low-power decoder design.

  • 121.
    Xue, Shang
    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.
    Comparative study of low-voltage performance of standard-cell flip-flops2001In: ICECS 2001: 8TH IEEE INTERNATIONAL CONFERENCE ON ELECTRONICS, CIRCUITS AND SYSTEMS, VOLS I-III, CONFERENCE PROCEEDINGS, New York: IEEE , 2001, p. 953-957Conference paper (Other academic)
    Abstract [en]

    The static single-phase D flip-flop is the basic memory element in the standard cell based design methodology for digital integrated circuits. In low-power high-speed performance designs, pipelining in conjunction with voltage scaling has proven to be an efficient approach to achieve the targeted low-power performance. The efficiency of the flip-flop at low power supply voltages will therefore play an increasingly important role. In this paper a comparison of the efficiency of six different D flip-flops operating at different voltages are presented and discussed. All circuits in this paper have been designed in a 0.6 mum CMOS technology and the results have been obtained from analog simulation. This study shows that power savings are possible in power-driven synthesis by including different flip-flops that are based on different design styles in the standard cell library.

  • 122.
    Xue, Shang
    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.
    Efficient VLSI Implementation of a VLC Decoder for Golomb-Rice Code using Alternating Coding2003In: IEEE Norchip´03, Riga, Latvia, November 2003, 2003Conference paper (Refereed)
  • 123.
    Xue, Shang
    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.
    Efficient VLSI Implementation of a VLC Decoder for Universal Variable Length Code using Alternating Coding2003In: ISVLSI 2003: IEEE COMPUTER SOCIETY ANNUAL SYMPOSIUM ON VLSI, PROCEEDINGS - NEW TRENDS AND TECHNOLOGIES FOR VLSI SYSTEMS DESIGN, IEEE Computer Society, 2003, p. 207-208, article id 1183467Conference paper (Refereed)
    Abstract [en]

    Variable length code (VLC) is used in a large variety of lossless compression applications. A specially designed VLC, called "Universal Variable Length Code" (UVLC), is utilized in the latest video coding standard H.26L under development. In this work we develop an efficient decoder for UVLC by utilizing the special properties of UVLC which perform coding in an alternating way (ALT). We compare the ALT decoder with the decoder called "VLC decoder using plane separation" (PLS) which is claimed to be one of the most effective VLC decoders. Our results show that the ALT decoder is 1.34 times faster, 1.7 times smaller, and consumes 45% power in comparison to the PLS decoder

  • 124.
    Xue, Shang
    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.
    Error Resilient coding of DCT coefficients using alternating coding of UVLC2003In: Norsig, Bergen, Norway,  October 2003, 2003Conference paper (Refereed)
  • 125.
    Xue, Shang
    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.
    Parallel Variable-length Decoder Architecture for Alternated Coded GR-Codes2003In: IEEE Norchip´03, Riga, latvia, november, 2003, 2003Conference paper (Refereed)
  • 126.
    Xue, Shang
    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.
    Unary Prefixed Huffman Coding for a Group of Quantized Generalized Gaussian Sources2006In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 54, no 7, p. 1164-1169Article in journal (Refereed)
    Abstract [en]

    We propose a coding algorithm called unary prefixed Huffman (UPH) coding for a family of infinite sources called quantized generalized Gaussian (GG) sources. Compared with the existing codes for these GG sources, the UPH algorithm provides a more adaptive approach, and its coding efficiency is upper bounded by entropy +2.

  • 127.
    Xue, Shang
    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.
    Unary-Prefixed Encoding of the Lengths of Consecutive Zeros in a Bit Vector2005In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 41, no 6, p. 346-347Article in journal (Refereed)
    Abstract [en]

    A unary-prefixed encoding (UPE) algorithm for coding the lengths of zeros in a bit vector is proposed. While the lengths of consecutive zeros in a bit vector can be mapped to integer sources with a geometrical distribution (when the bits in the bit vector are independent of each other), the actual case, in a real-world situation, is more often that the distributions are exponential, with high peaks and heavier tails (when the bits in a bit vector are correlated). For the geometric distribution, the UPE code set can be proven to be optimal. For integer sources with high peaks and heavier tails, the UPE almost always provides better compression compared to existing suboptimal codes.

  • 128.
    Xue, Shang
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Xu, Youzhi
    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.
    Hybrid Golomb codes for a group of quantised GG sources2003In: IEE Proceedings - Vision Image and Signal Processing, ISSN 1350-245X, E-ISSN 1359-7108, Vol. 150, no 4, p. 256-260Article in journal (Refereed)
    Abstract [en]

    The authors develop a class of codes for quantised generalised Gaussian (GG) sources. This new class of codes, that are called hybrid Golomb (HG) codes, are hybrids of Golomb-Rice (GR) codes and exp-Golomb (EG) codes. They integrate the properties of both GR and EG codes, which makes their performance more robust under variable source parameters. The efficiencies of the three classes of codes are compared and it is shown that the set of HG codes have efficiencies of approximately 70% or greater for a wide range of parameter values, whereas GR and EG codes can have efficiencies lower than 20%. The efficiencies of the set of HG codes are also compared with the set of EG codes that have the best performance under parameter scaling. It is shown that. this set of HG codes still achieve a higher efficiency.

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