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  • 5151. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Lagö, Thomas L
    Claesson, Ingvar
    Investigation of the Dynamic Properties of a Milling Tool Holder2009Report (Other academic)
    Abstract [en]

    Vibration problems during metal cutting occur frequently in the manufacturing industry. The vibration level depends on many different parameters such as the material type, the dimensions of the workpiece, the rigidity of tooling structure, the cutting data, and the operation mode. In milling, the cutting process subjects the tool to vibrations, and having a milling tool holder with a long overhang will most likely result in high vibration levels. As a consequence of these vibrations, the tool life is reduced, the surface finishing becomes poor, and disturbing sound appears. In this report, an investigation of the dynamic properties of a milling tool holder with moderate overhang has been carried out by means of experimental modal analysis and vibration analysis during the operating mode. Both the angular vibrations of the rotating tool and the vibrations of the machine tool structure were examined during milling. Also, vibration of the workpiece and the milling machine was examined during cutting. This re- port focuses on identifying the source/sources of the dominant milling vibration components and on determining which of these vibrations that are related to the structural dynamic properties of the milling tool holder.

  • 5152. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Lagö, Thomas L
    Håkansson, Lars
    Analysis of Dynamic Properties of Boring Bars Concerning Different Clamping Conditions2007Report (Other academic)
    Abstract [en]

    The boring bar is one of the most widely used type of tool holders in metal cutting operations. The turning process subjects the tool to vibrations, and cutting in deep workpiece cavities is likely to result in high vibration levels. The consequences of such vibration levels generally results in: reduced tool life, poor surface finishing and disturbing sound. Internal turning frequently requires a long and slender boring bar in order to machine inside a cavity, and the vibrations generally become highly correlated with one of the fundamental bending modes of the boring bar. Different methods can be applied to reduce the vibrations, the implementation of the most efficient and stable methods require in depth knowledge concerning the dynamic properties of the tooling system. Furthermore, the interface between the boring bar and the clamping house has a significant influence on the dynamic properties of the clamped boring bar. This report focuses on the dynamic properties of a boring bar that arise under different clamping conditions of the boring bar and are introduced by a clamping house (commonly used in the manufacturing industry). The dynamic properties of a boring bar (for different cases of boundary condition of the boring bar) are presented partly analytically but also experimentally.

  • 5153.
    Åkesson, Henrik
    et al.
    Blekinge Institute of Technology.
    Smirnova, Tatians
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Analysis of Dynamic Properties of Boring Bars Con-cerning Different Clamping Conditions2009In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 23, no 8, p. 2629-2647Article in journal (Refereed)
    Abstract [en]

    Boring bars are frequently used in the manufacturing industry to turn deep cavities in workpieces and are usually associated with vibration problems. This paper focuses on the clamping properties’ influence on the dynamic properties of clamped boring bars. A standard clamping housing of the variety commonly used in industry today has been used. Both a standard boring bar and a modified boring bar have been considered. Two methods have been used: Euler–Bernoulli beam modeling and experimental modal analysis. It is demonstrated that the number of clamping screws, the clamping screw diameter sizes, the screw tightening torques, the order the screws are tightened has a significant influence on a clamped boring bars eigenfrequencies and its mode shapes orientation in the cutting speed—cutting depth plane. Also, the damping of the modes is influenced. The results indicate that multi-span Euler–Bernoulli beam models with pinned boundary condition or elastic boundary condition modeling the clamping are preferable as compared to a fixed-free Euler–Bernoulli beam for modeling dynamic properties of a clamped boring bar. It is also demonstrated that a standard clamping housing clamping a boring bar with clamping screws imposes non-linear dynamic boring bar behavior.

  • 5154.
    Åkesson, Henrik
    et al.
    Blekinge Institute of Technology, Department of Telecommunications and Signal Processing.
    Sällberg, Benny
    Blekinge Institute of Technology, Department of Telecommunications and Signal Processing.
    Identification and Analysis of Nonlinear Systems2003Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    In classical mechanical engineering the predominant group of system analysis and identification tools relies on Linear Systems, where research have been carried out for over half a century. Usage of Linear Systems is most widely spread, often due to its simple mathematics and formulation for many engineering problems. Although linearizing is a means for simplifying a problem, it will introduce more or less severe modelling errors. In some cases the errors due to linearizing are too large to be practically acceptable, and therefore nonlinear structures and models are sometimes introduced. This thesis aims in implementing and evaluating some popular methods and algorithms for nonlinear structure analysis and identification, with emphasis on systems having nonlinear terms. Preferably the algorithms should be optimized in their computational load. The result are several algorithms for nonlinear analysis and identification. The ones giving best results were the frequency based methods Reverse Path and a Frequency Domain Structure Selection Method (FDSSA). The time domain based method, Nonlinear Autoregressive Moving Average with Exogenous Input (NARMAX), in which a lot of hope had been put, did perform very well in giving good system descriptions, but due to its nonphysical representation it was not suitable for usage in this thesis. The algorithms and methods were finally applied for two cases, a four system black-box case and an experimental test-rig case. The methods did perform well in three out of four systems in the first case, but the methods did not perform well for the second case, due to problems in applying correct levels of excitation force at the test-rig’s resonance frequencies.

  • 5155.
    Åström, Freddie
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, The Institute of Technology.
    A Variational Approach to Image Diffusion in Non-Linear Domains2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Image filtering methods are designed to enhance noisy images captured in situations that are problematic for the camera sensor. Such noisy images originate from unfavourable illumination conditions, camera motion, or the desire to use only a low dose of ionising radiation in medical imaging. Therefore, in this thesis work I have investigated the theory of partial differential equations (PDE) to design filtering methods that attempt to remove noise from images. This is achieved by modeling and deriving energy functionals which in turn are minimized to attain a state of minimum energy. This state is obtained by solving the so called Euler-Lagrange equation. An important theoretical contribution of this work is that conditions are put forward determining when a PDE has a corresponding energy functional. This is in particular described in the case of the structure tensor, a commonly used tensor in computer vision.A primary component of this thesis work is to model adaptive image filtering such that any modification of the image is structure preserving, but yet is noise suppressing. In color image filtering this is a particular challenge since artifacts may be introduced at color discontinuities. For this purpose a non-Euclidian color opponent transformation has been analysed and used to separate the standard RGB color space into uncorrelated components.A common approach to achieve adaptive image filtering is to select an edge stopping function from a set of functions that have proven to work well in the past. The purpose of the edge stopping function is to inhibit smoothing of image features that are desired to be retained, such as lines, edges or other application dependent characteristics. Thus, a step from ad-hoc filtering based on experience towards an application-driven filtering is taken, such that only desired image features are processed. This improves what is characterised as visually relevant features, a topic which this thesis covers, in particular for medical imaging.The notion of what are relevant features is a subjective measure may be different from a layman's opinion compared to a professional's. Therefore, we advocate that any image filtering method should yield an improvement not only in numerical measures but also a visual improvement should be experienced by the respective end-user

  • 5156.
    Åström, Freddie
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A Tensor Variational Formulation of Gradient Energy Total Variation2015In: ENERGY MINIMIZATION METHODS IN COMPUTER VISION AND PATTERN RECOGNITION, EMMCVPR 2015, Springer Berlin/Heidelberg, 2015, Vol. 8932, p. 307-320Conference paper (Refereed)
    Abstract [en]

    We present a novel variational approach to a tensor-based total variation formulation which is called gradient energy total variation, GETV. We introduce the gradient energy tensor into the GETV and show that the corresponding Euler-Lagrange (E-L) equation is a tensor-based partial differential equation of total variation type. Furthermore, we give a proof which shows that GETV is a convex functional. This approach, in contrast to the commonly used structure tensor, enables a formal derivation of the corresponding E-L equation. Experimental results suggest that GETV compares favourably to other state of the art variational denoising methods such as extended anisotropic diffusion (EAD) and total variation (TV) for gray-scale and colour images.

  • 5157.
    Åström, Freddie
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    Felsberg, Michael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    On the Choice of Tensor Estimation for Corner Detection, Optical Flow and Denoising2015In: COMPUTER VISION - ACCV 2014 WORKSHOPS, PT II / [ed] C.V. Jawahar and Shiguang Shan, Springer, 2015, Vol. 9009, p. 15p. 16-30Conference paper (Refereed)
    Abstract [en]

    Many image processing methods such as corner detection,optical flow and iterative enhancement make use of image tensors. Generally, these tensors are estimated using the structure tensor. In this work we show that the gradient energy tensor can be used as an alternativeto the structure tensor in several cases. We apply the gradient energy tensor to common image problem applications such as corner detection, optical flow and image enhancement. Our experimental results suggest that the gradient energy tensor enables real-time tensor-based image enhancement using the graphical processing unit (GPU) and we obtain 40% increase of frame rate without loss of image quality.

  • 5158.
    Åström, Freddie
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Felsberg, Michael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Baravdish, George
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lundström, Claes
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Targeted Iterative Filtering2013Conference paper (Refereed)
    Abstract [en]

    The assessment of image denoising results depends on the respective application area, i.e. image compression, still-image acquisition, and medical images require entirely different behavior of the applied denoising method. In this paper we propose a novel, nonlinear diffusion scheme that is derived from a linear diffusion process in a value space determined by the application. We show that application-driven linear diffusion in the transformed space compares favorably with existing nonlinear diffusion techniques. 

  • 5159.
    Öberg, T
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Materials Science. SIGNALS AND SYSTEMS.
    Modulation, Detection and Coding2001Book (Refereed)
  • 5160. Öberg, T.
    et al.
    Nilsson, B.
    Olofsson, N.
    Nordenvaad, Magnus Lundberg
    Sangfelt, E.
    Underwater communication link with iterative equalization2006In: OCEANS 2006, IEEE Communications Society, 2006Conference paper (Refereed)
    Abstract [en]

    In this paper an acoustic underwater communication link is presented. The channel has severe inter symbol interference, which is dealt with by an iterative linear equalizer and a Turbo code. Experiments has been performed in the Baltic Sea using a 4QAM signal with bandwidth 4 kHz at a center frequency of 12 kHz. The raw data rate is 8 kbit/s but after reduction for error correction coding the net bit rate is 2.88 kbit/s. With a source level of 180 dB re. 1mu/Pa @ 1m and a single hydrophone receiver, a reliable communication is shown up to a distance of 60 km. Very important for a successful decoding is the initial synchronization, which also is discussed.

  • 5161.
    Ödling, Per
    Luleå tekniska universitet.
    Design and analysis of digital receivers1995Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis consists of a summary and nine included papers, grouped into three parts. There is one journal paper, three reports written in the style of articles, four conference papers and one paper submitted to a conference. The thesis proposes and investigates a number of digital receivers, especially receivers based on the maximum a posteriori and maximum likelihood criteria. Signal processing methods and models are developed and applied to a number of estimation and detection problems in systems with time dispersion and additive Gaussian noise. Digital receivers in two application areas are investigated: telecommunications and ultrasonic distance measurements. Within telecommunications, particular attention is given to block transmission systems, where digital data is transmitted in independent blocks. With a geometric approach and reflecting on properties of the binary hypercube, it is shown that the minimum bit-error probability receiver (OBER) becomes the maximum likelihood sequence detector (MLSD) when the expected SNR used for designing the OBER goes to infinity. Likewise, the OBER reduces to the whitened matched filter with hard decisions in the limit when the expected SNR decreases. Furthermore, a novel detector is developed that makes MLSD-decisions on scattered bits in a block. This low-complexity detector can, if combined with a sub-optimal receiver such as a linear or decision- feedback equalizer, substantially reduce the system bit-error rate. Finally, using the geometric approach, the genie-aided detector, a device proposed by Forney for deriving performance bounds, is reconsidered and augmented with an explicit statistical description of the side information. This renders a more flexible tool, new performance bounds, and gives an instructive view on earlier work. Reduced complexity Viterbi detection is addressed by means of combined linearViterbi equalizers. These equalizers reduce the complexity of the Viterbi detector, a structure for implementing the MLSD, by linear pre-equalization of received data and by giving the Viterbi detector a truncated channel model. Three receivers in this class are introduced, one of which is intended for multiple-antenna reception in block transmission systems. In the field of ultrasonics, the problem of estimating the time-of-flight of an ultrasonic pulse is addressed under the assumption that the pulse has been distorted by an unknown, linear and time-dispersive system and by additive Gaussian noise. Two approaches for taking the linear distortion into account are presented. Both assume that the transmitted pulse is known and narrowband. Although the intended application is distance estimation using the ultrasonic pulse-echo method, the assumed basis of the time-of-flight estimation problem is more general: a known narrowband waveform is transmitted through a dispersive, linear system with additive Gaussian noise.

  • 5162. Ödling, Per
    Design and Analysis of Digital Receivers1995Doctoral thesis, comprehensive summary (Other academic)
  • 5163.
    Ödling, Per
    Luleå tekniska universitet.
    Low complexity digital receivers1993Licentiate thesis, comprehensive summary (Other academic)
  • 5164. Ödling, Per
    Low Complexity Digital Receivers1993Licentiate thesis, comprehensive summary (Other academic)
  • 5165. Ödling, Per
    et al.
    Börjesson, Per Ola
    Koski, Timo
    A Reduced Complexity Viterbi Equalizer used in Conjunction with a Pulse Shaping Method1992Conference paper (Refereed)
  • 5166.
    Ödling, Per
    et al.
    Luleå tekniska universitet.
    Eriksson, Håkan B.
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Making MLSD-decisions on some individual symbols thresholding the matched filter output1997In: Proceedings: 1997 IEEE International Symposium on Information Theory : Maritim Hotel and Congress Center, Ulm, Germany, June 29 - July 4, 1997, Piscataway, NJ: IEEE Communications Society, 1997, p. 75-Conference paper (Refereed)
    Abstract [en]

    We present a detector that, by thresholding the output of the matched filter, gives MLSD-decisions on binary, antipodally modulated symbols that have been corrupted by intersymbol interference and additive Gaussian noise. The detector is simple in structure, consisting of a whitened matched filter and two variable thresholds for each symbol to be detected. The detector will make decisions on some, but most often not all, of the symbols in a transmitted sequence, and those decisions will be the same decisions as the maximum likelihood sequence detector (MLSD) would have made. The number of symbols that are detected is stochastic, varying from sequence to sequence. The basis of the detector is a bound on a cross-product of the quadratic form in the log-likelihood function for the transmitted sequence

  • 5167.
    Ödling, Per
    et al.
    Luleå tekniska universitet.
    Eriksson, Håkan B.
    Luleå tekniska universitet.
    Börjesson, Per-Ola
    Luleå tekniska universitet.
    Making MLSD decisions using a data-dependent threshold device1996In: Proceedings of the 1996 SNRV and NUTEK Conference on Radio Sciences and Telecommunications in Luleå and Kiruna June 3-6, 1996: RVK 96 / [ed] Lars H. Zetterberg, Luleå: Luleå tekniska universitet, 1996, p. 245-249Conference paper (Refereed)
    Abstract [en]

    This paper presents a detector for obtaining MLSD decisions on binary symbols that has been corrupted by intersymbol interference and additive Gaussian noise. The basis of the detector is a bound on a cross-product of the quadratic form in the log-likelihood function for the transmitted sequence. The detector will only make decisions on some of the symbols in a transmitted sequence, but those decisions will be the same decisions as the MLSD would have made. The number of symbols to be detected is stochastic, varying from sequence to sequence. The detector is simple in structure, consisting of a whitened matched filter and two variable thresholds for each symbol to be detected. Because the detector in general does not detect the complete sequence of symbols, but has a very good performance on those symbols that are detected, it is suitable as a complement to some existing detector that is inferior to the maximum likelihood sequence detector.

  • 5168.
    Ödling, Per
    et al.
    Luleå tekniska universitet.
    Eriksson, Håkan B.
    Luleå tekniska universitet.
    Koski, Timo
    Kungliga tekniska högskolan, KTH.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    When are the MLSD respectively the matched filter receiver optimal with respect to the BER?1995In: Proceedings: 1995 IEEE International Symposium on Information Theory, Whistler, British Columbia, Canada, 17 - 22 September, 1995, Piscataway, NJ: IEEE Communications Society, 1995, p. 331-Conference paper (Refereed)
    Abstract [en]

    We reconsider the minimum/optimal bit-error probability receiver (OBER) for intersymbol interference channels with Gaussian noise and the reception of finite blocks of bits. We view the OBER as a function with two inputs: the received sequence and an expected signal-to-noise ratio; and one output: the estimated block of bits. Assuming that all sequences are equally probable to be transmitted we prove two results about the behaviour of the OBER. We show that the OBER coincides with the maximum likelihood sequence detector (MLSD) when designed for high signal-to-noise ratios and that it collapses to a matched filter followed by a hard-limiting device for low expected signal-to-noise ratios

  • 5169.
    Ödling, Per
    et al.
    Luleå tekniska universitet.
    Koski, Timo
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    A reduced complexity viterbi equalizer used in conjunction with a pulse shaping method1992In: Proceedings of Nordic Radio Symposium: NRS 92 : wave propagation, personal, mobile and satellite communications / in co-operation with AUC - Aalborg University / [ed] Chr. Christensen, Aalborg: Aalborg University , 1992, p. 91-94Conference paper (Refereed)
    Abstract [en]

    The complexity of the Viterbi algorithm can be reduced by linear pre-equalization. We introduce a linear preprocessor using the weighted least squares filtering of [10]. The geometric technique of L.Barbosa [3] is evoked for analytical representation of the complexity reduction by pre-equalization, and for evaluation of error performance. We give results on the bit error rate of the WLS preprocessor and of the linear preprocessor of Falconer and Magee [6].

  • 5170. Ödling, Per
    et al.
    Koski, Timo
    Börjesson, Per Ola
    A Reduced Complexity Viterbi Equalizer used in Conjunction with a Pulse Shaping Method1992Conference paper (Refereed)
  • 5171. Ödling, Per
    et al.
    Koski, Timo
    Börjesson, Per Ola
    A Reduced Complexity Viterbi Equalizer used in Conjunction with a Pulse Shaping Method1992Conference paper (Refereed)
    Abstract [en]

    The complexity of the Viterbi algorithm can be reduced by linear pre-equalization. The authors introduce a linear preprocessor using the weighted least squares filtering (WLS). The geometric technique of L. Barbosa (see IEEE Trans. Inf. Theory, vol.35, no.2, p.419-27, 1989) is evoked for analytical representation of the complexity reduction by pre-equalization, and for evaluation of error performance. They evaluate the bit error rate of the WLS preprocessor and of the linear preprocessor of Falconer and Magee (see Bell System Tech. Journal, vol.52, no.9, p.1541-62, 1973)

  • 5172.
    Ödmark, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Model based pulse shaping for detection of gamma rays2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To analyse drill samples in a mine, a scanner that uses a gamma ray detector can be used. The scanner can analyse the drill sample to quickly see the elements present in the sample without destroying it. To improve the performance of the scanner, the electric signal from the detector needs to be less noisy, and different pulse shaping methods, filters and smoothers can be used on the sampled data to achieve an improved performance.

    In this master thesis, the electric noise model of the electronics around the detector was modeled, and analysed. Different pulse shaping method, filters and smoothers was also tested to see which method gave the best performance in FWHM sense. The Full Width at Half Maximum (FWHM) is the energy resolution of a detector, and is defined as the full width of a photopeak at the half maximum. The noise model of the schematic for the preamplifier was made by hand with support from MATLAB. The resulting noise model was compared between MATLAB and LTspice, and the conclusion is that the JFET is the main contributor of the significant noise, contributing to 98 % of the total noise at 10 GHz.

    The adopted filters and pulse shaping method are, matched filter, custom filter, CR-RC shaping, mean filter, median filter and clustering. The results from the tests indicated that custom filter with a FWHM of 1.96 keV and CR-RC with a FWHM of 1.67 keV shaping were more accurate than the matched filter with the FWHM of 5.1 keV. But the results also showed that it is important to take into account the waveform variance, due to inherent properties in the detector, with this consideration the FWHM of CR-RC shaper was improved from 2.29 keV to 1.67 keV. The clustering method was the most promising method but due to time constraints this method was never fully tested and no FWHM value was achieved.

  • 5173.
    Öhrn, K
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Materials Science. SIGNALS AND SYSTEMS.
    Ahlén, A
    Sternad, M
    A probabilistic approach to multivariable robust filtering and open-loop control1995In: IEEE TRANSACTIONS ON AUTOMATIC CONTROL, ISSN 0018-9286, Vol. 40, no 3, p. 405-418Article in journal (Refereed)
    Abstract [en]

    A new approach to robust filtering, prediction, and smoothing of discrete-time signal vectors is presented. Linear time-invariant filters are designed to be insensitive to spectral uncertainty in signal models. The goal is to obtain a simple design method

  • 5174.
    Öjefors, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Signaler och system. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signal Processing. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Lindblom, J
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Signaler och system. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signal Processing. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Kurup, Danesh G
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Signaler och system. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signal Processing. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Bäcklund, Ylva
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Fasta tillståndets elektronik. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signal Processing. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics.
    Municio, F
    Ryhanen, T
    Scheck, HO
    High gain micromachined slot-coupled patch-antenna for 60 GHz WLAN application2001In: 8th COST 260 Meeting on Smart Antenna Computer Aided Design & Technology, Université de Rennes, France, 2001Conference paper (Refereed)
  • 5175.
    Öjefors, Erik
    et al.
    Universität Siegen, Institut für Höchstfrequenztechnik und Quantenelektronik, Siegen, Germany.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Monolitic Integrated Antennas in Silicon Technology. Kapitel i bok2008In: Wave Antennas, Packaging and Beyond: (kapitel i bok) / [ed] Duixian Liu, John Wiley & Sons, USA , 2008Chapter in book (Other academic)
  • 5176.
    Örneskans, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Signal-filtration methodology for estimation of fuel level2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Knowing how much fuel there is in a car is important for a predictable driving experience. Such knowledge will dictate how a person drives, when to refuel and how long they can drive. However unprocessed fuel level signals are highly noisy and therefore misleading.To ensure a good and predictable driving experience it is important to estimate the fuel level. The way this thesis has tackled this problem is by comparing and evaluating different filtering methods.The estimation algorithms were designed based on a saddle type tank developed by Volvo Car Corporation. The fuel level sensor consists of a floater arm and can only detect fuel levels within its maximal and minimal positions. The tank size can deviate from the standard volume and it will affect the measurement. Acceleration, angular orientation and fuel consumption are all factors that disturb fuel level estimation and therefore their relationship to the estimation problem is investigated. An experiment was devised to investigate the relationship between angular orientation, fuel volume and fuel level readings. ARX based models were made including angular orientation or acceleration. The relationship was concluded to be non-linear. The Kalman, $H_{\infty}$, Particle and Recursive Least Squares filters were compared. The Kalman and RLS filters had the most desirable traits and were therefore further developed. Both Kalman and RLS resulted in smooth estimates on the driving cycles tested.The Kalman filter provided a steadier estimate and could be easily tuned for faster convergence to zero. The Kalman filter can easily be changed to accommodate parametric uncertainties which improve its robust qualities.However the relationship between angular orientation and fuel level readings are non-linear. Therefore the RLS method was considered more robust for a reduced biased fuel reading under angular orientations. In conclusion the most desirable filter is a filter that provides the best traits from both filters.

  • 5177.
    Östberg, Micael
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Norgren, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Intelligent Gripper2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The human hand is a great generic gripper as it can grasp objects of unknown shapes, weights and surfaces. Most robotic grippers in today's industry have to be custom made and tuned for each application by engineers, thus many man hours are required to get the desired behavior and repeatability. To be able to adapt some of the capabilities of the human hand into robust industrial robotic grippers would enhance their usability and ease the tuning by engineers once installed.

    This thesis discusses the development of a robust intelligent gripper for industrial use, based on piezo sensors which have the ability to both sense slippage and detect objects. First, an experimental sensor prototype was developed successfully using an amplification circuit and algorithms implemented in LabView. Secondly, a final prototype containing a signal board, an FPGA board, a simple gripper with linear units and more robust sensor modules where developed.

    The thesis further discusses which parts of the intelligent gripper that have been successfully implemented within the project time frame and which parts that needs to be further implemented, tested and improved.

  • 5178. Östlin, Erik
    On Radio Wave Propagation Measurements and Modelling for Cellular Mobile Radio Networks2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To support the continuously increasing number of mobile telephone users around the world, mobile communication systems have become more advanced and sophisticated in their designs. As a result of the great success with the second generation mobile radio networks, deployment of the third and development of fourth generations, the demand for higher data rates to support available services, such as internet connection, video telephony and personal navigation systems, is ever growing. To be able to meet the requirements regarding bandwidth and number of users, enhancements of existing systems and introductions of conceptually new technologies and techniques have been researched and developed. Although new proposed technologies in theory provide increased network capacity, the backbone of a successful roll-out of a mobile telephone system is inevitably the planning of the network’s cellular structure. Hence, the fundamental aspect to a reliable cellular planning is the knowledge about the physical radio channel for wide sets of different propagation scenarios. Therefore, to study radio wave propagation in typical Australian environments, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Telecommunications Cooperative Research Centre (ATcrc) in collaboration developed a cellular code division multiple access (CDMA) pilot scanner. The pilot scanner measurement equipment enables for radio wave propagation measurements in available commercial CDMA mobile radio networks, which in Australia are usually deployed for extensive rural areas. Over time, the collected measurement data has been used to characterise many different types of mobile radio environments and some of the results are presented in this thesis. The thesis is divided into an introduction section and four parts based on peer-reviewed international research publications. The introduction section presents the reader with some relevant background on channel and propagation modelling. Also, the CDMA scanner measurement system that was developed in parallel with the research results founding this thesis is presented. The first part presents work on the evaluation and development of the different revisions of the Recommendation ITU-R P.1546 point-to-area radio wave propagation prediction model. In particular, the modified application of the terrain clearance angle (TCA) and the calculation method of the effective antenna height are scrutinized. In the second part, the correlation between the smallscale fading characteristics, described by the Ricean K-factor, and the vegetation density in the vicinity of the mobile receiving antenna is investigated. The third part presents an artificial neural network (ANN) based technique incorporated to predict path loss in rural macrocell environments. Obtained results, such as prediction accuracy and training time, are presented for different sized ANNs and different training approaches. Finally, the fourth part proposes an extension of the path loss ANN enabling the model to also predict small-scale fading characteristics.

  • 5179.
    Östman, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Detection and Tracking of Human Targets using Ultra-Wideband Radar2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis was to assess the plausibility of using two Ultra- Wideband radars for detecting and tracking human targets. The detection has been performed by two different types of methods, constant false-alarm rate methods and a type of CLEAN algorithm. For tracking the targets, multiple hypothesis tracking has been studied. Particle filtering has been used for the state prediction, considering a significant amount of uncertainty in a motion model used in this thesis project. The detection and tracking methods have been implemented in MATLAB. Tracking in the cases of a single target and multiple targets has been investigated in simulation and experiment. The simulation results in these cases were compared with accurate ground truth data obtained using a VICON optical tracking system. The detection methods showed poor performance when using data that had been collected by the two radars and post-processed to enhance target features. For single targets, the detections were accurate enough to continuously track a target moving randomly in a controlled area. In the multiple target cases the tracker was not able to distinguish the multiple moving subjects.

  • 5180.
    Özcelikkale, Ayca
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Koseoglu, Mehmet
    Dept. of Electrical and Computer Engineering, University of California, Los Angeles, USA.
    Srivastava, Mani
    Dept. of Electrical and Computer Engineering, University of California, Los Angeles, USA.
    Optimization vs. reinforcement learning for wirelessly powered sensor networks2018In: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC)286-290, 2018, p. 286-290Conference paper (Refereed)
  • 5181.
    Özdogan, Özgecan
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Massive MIMO With Spatially Correlated Rician Fading Channels2019In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 67, no 5, p. 3234-3250Article in journal (Refereed)
    Abstract [en]

    This paper considers multi-cell massive multiple-input multiple-output systems, where the channels are spatially correlated Rician fading. The channel model is composed of a deterministic line-of-sight path and a stochastic non-line-of-sight component describing a practical spatially correlated multipath environment. We derive the statistical properties of the minimum mean squared error (MMSE), element-wise MMSE, and least-square channel estimates for this model. Using these estimates for maximum ratio combining and precoding, rigorous closed-form uplink (UL) and downlink (DL) achievable spectral efficiency (SE) expressions are derived and analyzed. The asymptotic SE behavior, when using the different channel estimators, are also analyzed. The numerical results show that the SE is higher when using the MMSE estimator than that of the other estimators, and the performance gap increases with the number of antennas.

  • 5182.
    Özdogan, Özgecan
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Uplink Spectral Efficiency of Massive MIMO with Spatially Correlated Rician Fading2018In: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC), IEEE , 2018, p. 216-220Conference paper (Refereed)
    Abstract [en]

    This paper considers the uplink (UL) of a multicell Massive MIMO (multiple-input multiple-output) system with spatially correlated Rician fading channels. The channel model is composed of a deterministic line-of-sight (LoS) path and a stochastic non-line-of-sight (NLoS) component describing a spatially correlated multipath environment. We derive the statistical properties of the minimum mean squared error (MMSE) and least-square (LS) channel estimates for this model. Using these estimates for maximum ratio (MR) combining, rigorous closed-form UL spectral efficiency (SE) expressions are derived. Numerical results show that the SE is higher when using the MMSE estimator than the LS estimator, and the performance gap increases with the number of antennas. Moreover, Rician fading provides higher achievable SEs than Rayleigh fading since the LoS path improves the sum SE.

  • 5183.
    Özkan, Emre
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Lundquist, Christian
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    A Bayesian Approach to Jointly Estimate Tire Radii and Vehicle Trajectory2011In: Proceedings of the International IEEE Conference on Intelligent Transportation Systems, Washington DC, USA: IEEE conference proceedings, 2011, p. 1-6Conference paper (Refereed)
    Abstract [en]

    High-precision estimation of vehicle tire radii is considered, based on measurements on individual wheel speeds and absolute position from a global navigation satellite system (GNSS). The wheel speed measurements are subject to noise with time-varying covariance that depends mainly on the road surface. The novelty lies in a Bayesian approach to estimate online the time-varying radii and noise parameters using a marginalized particle filter, where no model approximations are needed such as in previously proposed algorithms based on the extended Kalman filter. Field tests show that the absolute radius can be estimated with millimeter accuracy, while the relative wheel radius on one axle is estimated with submillimeter accuracy.

  • 5184.
    Özkan, Emre
    et al.
    Middle East Tech Univ, Dept Elect & Elect Engn, Ankara, Turkey.
    Wahlström, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Godsill, Simon J.
    Univ Cambridge, Dept Engn, Cambridge CB2 1TN, England.
    Rao-Blackwellised Particle Filter for Star-ConvexExtended Target Tracking Models2016In: 2016 19th International Conference on Information Fusion, 2016, p. 1193-1199Conference paper (Refereed)
    Abstract [en]

    In this paper, we explore the potential gains in using Sequential Monte Carlo (SMC) methods for extended target tracking (ETT) models based on Gaussian processes (GP). The existing random hypersurface based ETT models use Extended/Unscented Kalman filter for inference, which may lead to poor performance under high uncertainty. Particle filters (PFs) are known to provide robust performance in the cases where the non-linear Kalman filtering solutions fail. We design a Rao-Blackwellised particle filter (RBPF) where we exploit the conditional linear Gaussian structure of the GP parameters. We illustrate the gain in the performance with simulations.

  • 5185.
    Čirkić, Mirsad
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Efficient MIMO Detection Methods2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    For the past decades, the demand in transferring large amounts of data rapidly and reliably has been increasing drastically. One of the more promising techniques that can provide the desired performance is multiple-input multiple-output (MIMO) technology where multiple antennas are placed at both the transmitting and receiving side of the communication link. This performance potential is extremely high when the dimensions of the MIMO system are increased to an extreme (in the number of hundreds or thousands of antennas). One major implementation difficulty of the MIMO technology is the signal separation (detection) problem at the receiving side of the MIMO link, which holds for medium-size MIMO systems and even more so for large-size systems. This is due to the fact that the transmitted signals interfere with each other and that separating them can be very difficult if the MIMO channel conditions are not beneficial, i.e., the channel is not well-conditioned.

    The main problem of interest is to develop algorithms for practically feasible MIMO implementations without sacrificing the promising performance potential that such systems bring. These methods involve inevitably different levels of approximation. There are computationally cheap methods that come with low accuracy and there are computationally expensive methods that come with high accuracy. Some methods are more applicable in medium-size MIMO than in large-size MIMO and vice versa. Some simple methods for instance, which are typically inaccurate for medium-sized settings, can achieve optimal accuracy for certain large-sized settings that offer close-to-orthogonal spatial signatures. However, when the dimensions are overly increased, then even these (previously) simple methods become computationally burdensome. In different MIMO setups, the difficulty in detection shifts since methods with optimal accuracy are not the same. Therefore, devising one single algorithm which is well-suited for feasible MIMO implementations in all settings is not easy.

    This thesis addresses the general MIMO detection problem in two ways. One part treats a development of new and more efficient detection techniques for the different MIMO settings. The techniques that are proposed in this thesis demonstrate unprecedented performance in many relevant cases. The other part revolves around utilizing already proposed detection algorithms and their advantages versus disadvantages in an adaptive manner. For well-conditioned channels, low-complexity detection methods are often sufficiently accurate. In such cases, performing computationally very expensive optimal detection would be a waste of computational power. This said, for MIMO detection in a coded system, there is always a trade-off between performance and complexity. Intuitively, computational resources should be utilized more efficiently by performing optimal detection only when it is needed, and something simpler when it is not. However, it is not clear whether this is true or not. In trying to answer this, a general framework for adaptive computational-resource allocation to different (“simple” and “difficult”) detection problems is proposed. This general framework is applicable to any MIMO detector and scenario of choice, and it is exemplified using one particular detection method for which specific allocation techniques are developed and evaluated.

  • 5186.
    Čirkić, Mirsad
    Linköping University, Department of Electrical Engineering.
    Modular General-Purpose Data Filtering for Tracking2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In nearly allmodern tracking systems, signal processing is an important part with state estimation as the fundamental component. To evaluate and to reassess different tracking systems in an affordable way, simulations that are in accordance with reality are largely used. Simulation software that is composed of many different simulating modules, such as high level architecture (HLA) standardized software, is capable of simulating very realistic data and scenarios.

    A modular and general-purpose state estimation functionality for filtering provides a profound basis for simulating most modern tracking systems, which in this thesis work is precisely what is created and implemented in an HLA-framework. Some of the most widely used estimators, the iterated Schmidt extended Kalman filter, the scaled unscented Kalman filter, and the particle filter, are chosen to form a toolbox of such functionality. An indeed expandable toolbox that offers both unique and general features of each respective filter is designed and implemented, which can be utilized in not only tracking applications but in any application that is in need of fundamental state estimation. In order to prepare the user to make full use of this toolbox, the filters’ methods are described thoroughly, some of which are modified with adjustments that have been discovered in the process.

    Furthermore, to utilize these filters easily for the sake of user-friendliness, a linear algebraic shell is created, which has very straight-forward matrix handling and uses BOOST UBLAS as the underlying numerical library. It is used for the implementation of the filters in C++, which provides a very independent and portable code.

  • 5187.
    Čirkić, Mirsad
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    On the Complexity of Very Large Multi-User MIMO Detection2014In: 2014 IEEE 15th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), IEEE, IEEE Press, 2014, p. 55-59Conference paper (Refereed)
    Abstract [en]

    This work discusses efficient techniques for detection in large-size multi-user multiple-input multiple-output (MIMO) systems that are highly overdetermined. We exemplify the application of conjugate gradient methods in the setup of our interest and compare its performance with respect to methods based on the Neumann series expansion. We bring to light some important insights on the performance versus complexity tradeoffs that have not been uplifted before.

  • 5188.
    Čirkić, Mirsad
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    SUMIS: Near-Optimal Soft-In Soft-Out MIMO Detection with Low and Fixed Complexity2014In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 62, no 12, p. 3084-3097Article in journal (Refereed)
    Abstract [en]

    The fundamental problem of interest here is soft-input soft-output multiple-input multiple-output (MIMO) detection. We propose a method, referred to as subspace marginalization with interference suppression (SUMIS), that yields unprecedented performance at low and fixed (deterministic) complexity. Our method provides a well-defined tradeoff between computational complexity and performance. Apart from an initial sorting step consisting of selecting channel-matrix columns, the algorithm involves no searching nor algorithmic branching; hence the algorithm has a completely predictable run-time and allows for a highly parallel implementation. We numerically assess the performance of SUMIS in different practical settings: full/partial channel state information, sequential/iterative decoding, and low/high rate outer codes. We also comment on how the SUMIS method performs in systems with a large number of transmit antennas.

  • 5189.
    Čirkić, Mirsad
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Persson, Daniel
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Allocation of Computational Resources for Soft MIMO Detection2011In: IEEE Journal of Selected Topics in Signal Processing, ISSN 1932-4553, Vol. 5, no 8, p. 1451-1461Article in journal (Refereed)
    Abstract [en]

    We consider soft MIMO detection for the case of block fading. That is, the transmitted codeword spans over several independent channel realizations and several instances of the detection problem must be solved for each such realization. We develop methods that adaptively allocate computational resources to the detection problems of each channel realization, under a total per-codeword complexity constraint. Our main results are a formulation of the problem as a mathematical optimization problem with a well-defined objective function and constraints, and algorithms that solve this optimization problem efficiently computationally.

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