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  • 251. Maddala, Sainath
    et al.
    Bartunek, Josef Ström
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Nilsson, Mikael
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Implementation and evaluation of NIST biometric image software for fingerprint recognition2010Conference paper (Refereed)
    Abstract [en]

    Fingerprints are rich in details which are in the form of discontinuities in ridges known as minutiae and are unique for each person. This paper describes implementation and evaluation of an existing fingerprint recognition system in MATLAB environment. The selected system is developed by National Institute of Standards and Technology (NIST) denoted as Biometric Image Software (NBIS). The NBIS source code is written in ANSI C programming language. To be able to evaluate the algorithm in MATLAB a C language MEX-files has been used. The NBIS support both minutiae extraction and minutiae matching functions that have been employed in the evaluation. The implemented system has been tested on a Fingerprint Verification Competition (FVC) database. The results are presented as Receiver Operating Characteristics (ROC) graphs

  • 252.
    Maddala, Sainath
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Reddy, Sandeep Kumar
    A simulator for depicting and comparing adaptive algorithms in signal processing2011Conference paper (Refereed)
    Abstract [en]

    In real time applications signal characteristic and signal noise cannot be determined and predicted which makes very hard while designing digital filters for noise suppression. To outstrip these problem adaptive filters are preferable in which filter coefficients are designed based on the situation by using adaptive algorithms. In this paper a simulator containing adaptive algorithms(Least Mean Square(LMS), Normalized Least Mean Square(NLMS), Recursive Least Square(RLS) , Signed Least Mean Square(SLMS), Signed Normalized Least Mean Square(SNLMS)) using different applications was developed in MATLAB using Graphical User Interphone(GUI). Performance of all algorithms had been observed and some of the results obtained for different applications had been depicted by using real time noise corrupted voice signal. This proposed simulator helps the end user for depicting and comparing adaptive algorithms for real time applications. Pros and cons of each algorithm are observed manually without any motive of mathematical and paper results.

  • 253.
    Maddala, Sainath
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Tangellapally, Sreekanth Rao
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Bartunek, Josef Ström
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Nilsson, Mikael
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Implementation and evaluation of NIST Biometric Image Software for fingerprint recognition2011Conference paper (Refereed)
    Abstract [en]

    Fingerprints are rich in details which are in the form of discontinuities in ridges known as minutiae and are unique for each person. This paper describes implementation and evaluation of an existing fingerprint recognition system in MATLAB environment. The selected system is developed by National Institute of Standards and Technology (NIST) denoted as Biometric Image Software (NBIS). The NBIS source code is written in ANSI C programming language. To be able to evaluate the algorithm in MATLAB a C language MEX-files has been used. The NBIS support both minutiae extraction and minutiae matching functions that have been employed in the evaluation. The implemented system has been tested on a Fingerprint Verification Competition (FVC) database. The results are presented as Receiver Operating Characteristics (ROC) graphs.

  • 254.
    Madhukiran, E. R C S
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Thota, Partha Saradhi
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Sridhar, Bitra
    Dileesh, Kanupuru
    Control of Buck converter by Polynomial, PID and PD controllers2012Conference paper (Refereed)
    Abstract [en]

    This paper presents the state space modeling approach of DC-DC Buck converter. The main aim of this work is, by considering the buck converter system of Ericsson BMR450 with the PID, Polynomial and PD controllers at feedback loop, thus running a MATLAB file with an appropriate simu-link block diagram, and comparing the three controller's performance by verifying their appropriate output graphs. The third order controller design is complicated and slow in response. The second order design is simple and gives better responses than third order Polynomial, PID and PD controllers.

  • 255.
    Mahmood, Shahid
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Unmanned Aerial Vehicles Communications.2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This Project deals with a small Unmanned Aerial Vehicle (UAV)Communication system. The considered distance between UAVs is 100 m to 10 km. These small UAVs are usually used for civil purposes like fire fighting, for farmers etc. This report represents the modem architecture for a small UAV radio network, which works with flexible transmission data rates (62 kbps to 744 kbps)by using an Orthogonal Frequency Division Multiplexing (OFDM) technique with adaptive resource allocation. It includes the instructions and architecture of an Fast Fourier Transform (FFT) processor for a single radix - 2 butterfly engine. The architecture is being modeled in Altera Hardware Descriptive Language (AHDL). For logic synthesis we have used Altera functions. An OFDM technique with adaptive modulation and codiing is used to readily achieve variable data rates and to provide a multipath resistant solution. We also investigate different FPGAs characteristics including memory, multiplexers and logic cells, to identify a low complexity and low cost solution. A Cyclone II FPGA is considered likely to implement the processing required for small UAV communication with the ground stations and between UAVs.

  • 256.
    Medic, Emir
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Soltani, Maziar
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Methods for characterization of digital, image-producing detectors within medical X-ray diagnostics2005Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    Construct a test object (phantom) that can generate a sharp edge in the X- ray image. Develop a program code in the high-level language MATLAB for determination of earlier mentioned parameters, MTF and DQE in particular. Work out radiation geometry, suitable for the purpose. Verify the usability through practical measurements on already existing clinical equipment at the hospital in Blekinge. Study the effect of radiation energy, dose of radiation, detector direction, spatial frequency, variation of sampling of the edge spread function (ESF), etc. Compare gained results with relevant literature. The practical meaning of the present case project is to: Make a clinically usable method for the quality safety of digital, medical X- ray equipment available at the hospital in Blekinge. Transfer, from the hospital in Blekinge to the Blekinge Institute of Technology, competence within medical radiation physics and medical technology, which could be interesting since the University is considering increasing their commitment within this area. The method can be spread within the informal co-operation, concerning medical radiation physics that is present within the hospitals outside the University districts in the southern region.

  • 257.
    Medic, Maziar Soltani Emir
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Methods for characterization of digital, imageproducing detectors within medical X-ray diagnostics2005Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    Since the end of the 1900th century ionized radiation, foremost X-ray radiation, have been used, with great success, within the medical field as a method for diagnostics as well as for therapeutically treatments. When it comes to X- ray diagnostics, the analogue film, detector and display medium have, in principle, been used the whole time. This is now rapidly changing, in a way that makes digital detectors dominate instead. Within the area of medical treatment, this means that methods must progress and be developed to measure and secure the quality of the imaging systems in a quick, easy and accurate way. The ability of the imaging system to reproduce the measured objects in a natural manner can be characterized by a number of different parameters such as; ESF (Edge spread function), LSF (Line spread function), MTF (Modulation transfer function), NPS (Noise power spectrum), and DQE (Detective quantum efficiency). These parameters can be received for each detector through experimental measurements of a sharp edge. The starting point of the project is the suggestions that are stated in the standard form IEC (622 20-1) determination of detective quantum efficiency, which was published by the end of 2003. Purpose of the project: • Construct a test object (phantom) that can generate a sharp edge in the X- ray image. • Develop a program code in the high-level language MATLAB for determination of earlier mentioned parameters, MTF and DQE in particular. • Work out radiation geometry, suitable for the purpose. • Verify the usability through practical measurements on already existing clinical equipment at the hospital in Blekinge. • Study the effect of radiation energy, dose of radiation, detector direction, spatial frequency, variation of sampling of the edge spread function (ESF), etc. • Compare gained results with relevant literature. The practical meaning of the present case project is to: • Make a clinically usable method for the quality safety of digital, medical X- ray equipment available at the hospital in Blekinge. • Transfer, from the hospital in Blekinge to the Blekinge Institute of Technology, competence within medical radiation physics and medical technology, which could be interesting since the University is considering increasing their commitment within this area. • The method can be spread within the informal co-operation, concerning medical radiation physics that is present within the hospitals outside the University districts in the southern region.

  • 258.
    Mehadi, Ahmed Shah
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Implementing Efficient iterative 3D Deconvolution for Microscopy2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Both Gauss-Seidel Iterative 3D deconvolution and Richardson-Lucy like algorithms are used due to their stability and high quality results in high noise microscopic medical image processing. An approach to determine the difference between these two algorithms is presented in this paper. It is shown that the convergence rate and the quality of these two algorithms are influenced by the size of the point spread function (PSF). Larger PSF sizes causes faster convergence but this effect falls off for larger sizes . It is furthermore shown that the relaxation factor and the number of iterations are influencing the convergence rate of the two algorithms. It has been found that increasing relaxation factor and number of iterations improve convergence and can reduce the error of the deblurred image. It also found that overrelaxation converges faster than underrelaxation for small number of iterations. However, it can be achieved smaller final error with under-relaxation. The choice of underrelaxation factor and overrelaxation factor value are highly problem specific and different from one type of images. In addition, when it comes to 3D iterative deconvolution, the influence of boundary conditions for these two algorithms is discussed. Implementation aspects are discussed and it is concluded that cache memory is vital for achieving a fast implementation of iterative 3D deconvolution. A mix of the two algorithms have been developed and compared with the previously mentioned Gauss-Seidel and the Richardson-Lucy-like algorithms. The experiments indicate that, if the value of the relaxation parameter is optimized, then the Richardson-Lucy-like algorithm has the best performance for 3D iterative deconvolution.

  • 259.
    Mehmood, Asad
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Cheema, Waqas-Aslam
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Channel Estimation for LTE Downlink2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    3GPP LTE is the evolution of the UMTS in response to ever-increasing demands for high quality multimedia services according to users’ expectations. Since downlink is always an important factor in coverage and capacity aspects, special attention has been given in selecting technologies for LTE downlink. Novel technologies such as orthogonal frequency division multiplexing (OFDM) and multiple input, multiple output (MIMO), can enhance the performance of the current wireless communication systems. The high data rates and the high capacity can be attained by using the advantages of the two technologies. These technologies have been selected for LTE downlink. Pilot-assisted channel estimation is a method in which known signals, called pilots, are transmitted along with data to obtain channel knowledge for proper decoding of received signals. This thesis aims at channel estimation for LTE downlink. Channel estimation algorithms such as Least Squares (LS), Minimum Mean Square Error (MMSE) haven been evaluated for different channel models in LTE downlink. Performance of these algorithms has been measured in terms of Bit Error Rate (BER) and Symbol Error Rate (SER).

  • 260. Melin, Jan
    et al.
    Hultgren, Anders
    Lindström, Torsten
    Two types of limit cycles of a resonant converter modelled by a three-dimensional system2008In: Nonlinear Analysis: Hybrid Systems, ISSN 1751-570X, E-ISSN 1878-7460, Vol. 2, no 4, p. 1275-1286Article in journal (Refereed)
    Abstract [en]

    In this paper, the long-run dynamics of a controlled resonant converter, modelled as a piecewise system, is studied. The modelling of the resonant converter can be done using various approximations and the long-run dynamics of the two dimensional cases were earlier analysed. In this paper, we discuss results that can be extended to the three dimensional case. It seems that limit cycles describe the longrun dynamics in important situations in the three dimensional case, too. Our objective is to relate the limit cycles found previously in the two-dimensional case to those found now in the three dimensional approximation.

  • 261.
    Mian-Zubair, Zain
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Safdar, Hashim
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    PERFORMANCE EVALUATION OF RAKE RECEIVERS USING ULTRA WIDEBAND MULTIPATH CHANNELS2008Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    In this report, we derive the performance graphs for UWB communication systems using different combining techniques in a RAKE Receiver. Comparisons have also been made between the techniques and conclusions have been drawn based on the requirements. We also incorporate the effect of number of fingers on the performance of the receivers. The results obtained give us way to evaluate the performance of Rake reception of UWB signals in dense multipath channels. We present simulation results using IEEE 802.15.3a UWB channel models. We evaluate the performances of Rake Receivers with different pulse-widths and also the effect of inter-frame interference.

  • 262.
    Mikhael, George
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Stansic, Srdan
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Spatial Acoustic Measurement Device2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In industrial workplaces, such as factories, noise pollution is a prominent danger to the health of workers, and could cause physical and psychological harm to them. The purpose of this thesis is to formulate and implement a device that can help locate the origin of these noise sources. This paper deals with the design and implementation of a spatial acoustic measurement device that can locate the origin of dominant acoustical sources in an environment. The device is made up of an array of microphones in a filter-and-sum array. The filters are designed using the Least Squares filter design method. The end device was able to identify the location of an acoustical noise source. The amount of attenuation for non pass band angles achieved depended on the number of filter taps used, main lobe width, and the number of microphones selected.

  • 263. Mohammed, Abbas
    Advances in Signal Processing for Mobile Communication Systems2002Collection (editor) (Other academic)
  • 264. Mohammed, Abbas
    Detection of Loran-C Skywave Interference Using Subspace Signal Processing Algorithms2005Conference paper (Refereed)
  • 265. Mohammed, Abbas
    Forskning om Smarta Antenner och MIMO vid BTH2004Other (Other academic)
  • 266. Mohammed, Abbas
    Simulation of a UMTS System2001Conference paper (Other academic)
  • 267. Mohammed, Abbas
    The Impact of Antennas on the Bluetooth Link in Indoor Office Environments2005Conference paper (Refereed)
  • 268. Mohammed, Abbas
    et al.
    Arnon, Shelomi
    Grace, David
    Mondin, Marina
    Miura, R
    Advanced Communication Techniques and Applications for High-Altitude Platforms2008In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Article in journal (Refereed)
  • 269. Mohammed, Abbas
    et al.
    Arnon, ShelomiGrace, DavidMondin, MarinaMuira, Ryu
    Advanced Communication Techniques and Applications for High Altitude Platforms2007Other (Other academic)
  • 270. Mohammed, Abbas
    et al.
    Ballal, Tarig
    Grbic, Nedelko
    Blind Source Separation Using Time-Frequency Masking2007In: Radioengineering, ISSN 1210-2512, E-ISSN 1805-9600, Vol. 16, no 4, p. 96-100Article in journal (Refereed)
  • 271. Mohammed, Abbas
    et al.
    Hult, Tommy
    Detection and minimisation of ionospheric interference in Loran-C receivers2009Conference paper (Refereed)
    Abstract [en]

    The subspace eigen-decomposition algorithms are applied to the problem of detecting ionospheric interfering signals affecting the performance of Loran-C receivers. In particular, we are interested in measuring the delay of these interfering Loran-C skywave components. The performance of these algorithms are evaluated and compared with our Fourier-based method. The simulation results show that many of the subspace eigen-decomposition algorithms yields good estimation accuracy and that they can also operate successfully with noisy signals.

  • 272. Mohammed, Abbas
    et al.
    Hult, Tommy
    Evaluation of Depolarization Effects on the Performance of High Altitude Platforms (HAPs)2008Conference paper (Refereed)
    Abstract [en]

    In this paper we study the depolarization effects caused by, rain and ice particles in the troposphere on the performance of a multiple HAP (High Altitude Platforms) system employing multi-polarized compact MIMO antenna configurations. In order to reinforce the analysis, we first propose a novel multi-channel simulator that produces realistic time-series of the fading process affecting signal transmission in HAP systems. The proposed simulator takes into account the temporal, spatial and polarization properties affecting these processes. Finally, we analyse the impact of depolarization on the total capacity of the system. Simulation results show a significant drop in performance as the cross polar discrimination decreases

  • 273. Mohammed, Abbas
    et al.
    Hult, Tommy
    Evaluation of depolarization effects on the performance of satellite communications2009Conference paper (Refereed)
    Abstract [en]

    In this paper we study the depolarization effects caused weather conditions and scattering structures at ground level on the performance of a multiple satellite system employing multi-polarized compact MIMO antenna configurations. In order to reinforce the analysis, we first propose a novel multi-channel simulator that produces realistic time-series of the fading process affecting signal transmission in satellite communication environments. The proposed simulator takes into account the temporal, spatial and polarization properties affecting these processes. Finally, we analyse the impact of depolarization on the total capacity of the tetrahedron Compact MIMO antenna system. Simulation results show a significant drop in performance as the cross polar discrimination decreases.

  • 274. Mohammed, Abbas
    et al.
    Hult, Tommy
    Evaluation of the Bluetooth Link and Antennas Performance for Indoor Office Environments by Measurement Trials and FEMLAB Simulations2005Conference paper (Refereed)
    Abstract [en]

    Antennas that are able to direct the transmitted and received signals' energy are of great interest for future wireless communication systems. The directivity implies reduced transmit power and interference, and hence potential for increased capacity. In this paper we present the results of measurement trails and FEMLAB simulations of the Bluetooth link employing different antennas in NLOS for indoor office environments. The results show the potential improvement in system performance gained from the use of directive antennas and the great dependency of the results on the antenna parameters (gain and efficiency) and the overall impact on the quality and coverage of the Bluetooth link. The results are also expected to provide an insight into the performance of antennas for other indoor wireless technologies such as ultra wideband (UWB) radio communications where the antenna impact and design is expected to be even more critical.

  • 275. Mohammed, Abbas
    et al.
    Hult, Tommy
    Multiple HAPS and Polarization Diversity for Enhanced Data Rate Communications2006Conference paper (Refereed)
  • 276. Mohammed, Abbas
    et al.
    Hult, Tommy
    Performance Evaluation of a MIMO Satellite Diversity System2008Conference paper (Refereed)
    Abstract [en]

    In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with satellite diversity techniques in order to increase the data rates in satellite communication systems. We will also investigate the effects of separation angles between satellites and the spatial correlation and mutual coupling between the separate antenna elements on system performance. Simulation results show that although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single satellite case. Simulations also show the existence of an optimum separation angle between satellites that maximizes capacity.

  • 277. Mohammed, Abbas
    et al.
    Hult, Tommy
    Performance Evaluation of the Bluetooth Link for Indoor Propagation by Measurement Trials and FEMLAB Simulations2005Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the wave propagation and link quality of the Bluetooth wireless short range communication system in LOS office environments and assess its performance by employing various omindirectional and directive antennas. The measurement results show that the antenna type and its parameters have a huge impact on the quality and coverage of the Bluetooth link. We will also confirm some of the measurement results and observations by using FEMLAB simulation of the same building.

  • 278. Mohammed, Abbas
    et al.
    Hult, Tommy
    The Effects of MIMO Antenna System Parameters and Carrier Frequency on Active Control Suppression of EM Fields2007In: Radioengineering, ISSN 1210-2512, E-ISSN 1805-9600, Vol. 16, no 1, p. 31-35Article in journal (Refereed)
    Abstract [en]

    In this paper we propose a new approach employing adaptive active control algorithms combined with a Multiple-Input Multiple-Output (MIMO) antenna system to suppress the electromagnetic field at a certain volume in space (e.g., at the human head). We will investigate the effects of the size and number of MIMO antenna elements on the system performance and test the algorithms at different carrier frequencies (e.g., GSM bands and UMTS).

  • 279. Mohammed, Abbas
    et al.
    Kamal, Hany
    AbdulWahaab, Shehab
    2G/3G Inter-RAT Handover Performance Analysis2007Conference paper (Refereed)
  • 280. Mohammed, Abbas
    et al.
    Samawi, Saad
    Investigation of the Bluetooth Link in NLOS Indoor Office Environments2004Conference paper (Refereed)
  • 281. Mohammed, Abbas
    et al.
    Samawi, Saad
    Measurement Trials of the Bluetooth Link in NLOS Indoor Office Environments2004Conference paper (Refereed)
  • 282.
    Murthy, Muddala Suryanarayana
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Elnourani, Mohamed Gafar Ahmed
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Active Noise Control of a Radial Fan2009Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    This thesis work aims at investigating the use of an active noise control (ANC) system on a radial fan. This was done by studying the fan structure and its potential working environment (the ducts). This includes measuring the sound levels on several positions and select suitable positions to apply the ANC system. Moreover, the tested ANC system was implemented on the ventilation system and acceptable results were obtained. Further analyses were made based on the obtained results and some explanations were derived to investigate the reason behind the ANC systems incapability to attenuate the noise generated by the fan at some frequencies.

  • 283.
    Navarro, Alvaro Palomo
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Adaptive Subband Equalization in Wireless Systems2006Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [en]

    The trend in communication is very clear; everything goes towards wireless communication systems. Since, the wireless channel is very hostile channel due to capacity limiting effects like co-channel interference, inter symbol interference, multi-path propagation and noise, these system require very good channel equalizers in order to combat these effects. However, since the mobile devices in mobile systems are usually very small these channel equalizations schemes need to be very low computationally complexity (i.e. low power consummation) in order to of any practical use. One method to implement powerful channel equalization schemes in a very efficiently is to implement them with help sub-band processing. In fact, you can implement very complex algorithm in the sub-band to a fraction of complexity of the fullband implementation. This is due to the fact that instead of solving one large problem we are solving many small ones instead. Therefore, this master thesis will investigate the performance of low complexity adaptive sub-band channel equalizers evaluated on a wireless channel. The thesis will also compare blind schemes (no training sequence) with non-blind schemes in order to investigate performance trade offs. The thesis will mostly focus on the Constant Modulus Algorithm (CMA) and its sub-bands versions.

  • 284.
    Nedfors, Claes
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Hallengren, Dan
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Klassificering av hastighetsskyltar2006Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    Many people are involved in severe traffic related accident every year. Many of these accidents are strongly linked to too high speed. One way to decrease the speed transgressions and the number of accidents could be to implement a system that help the driver keeping the current speed limit. This thesis presents a method for classifying speed signs using computer vision. The classifier is a part of a system for speed tracking and notifying. This system assists a driver by notifying him/her of the current speed limit. This is done by computer vision, i.e. a camera connected to a computer reads the current trac environment and the frames are processed by the computer. A computer vision system is commonly composed by a detector and a classifier. The detector scans the frames from the camera and locates possible speed signs. The possible speed sign locations are passed to the classifier. The classifiers task is to decide if the possible location contains a speed sign and if it does contain a speed sign, to proclaim its speed. The classifier in this thesis is based on cross correlation. The algorithm is evaluated against a database, which includes images with coordinates for speed signs marked by hand. If the weather conditions are not to extreme and if the detector has good accuracy the classifier will make the right decision in close to 100% of the cases.

  • 285.
    Negusse, Senay Amanuel
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Improving Intra Pixel prediction for H.264 video coding Senay2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    H.264 is the latest most efficient video coding standard developed by joint collaboration between ITU-T’s Study Group 16 Question 6 (Video Coding Experts Group VCEG) and ISO’s MPEG forming a group known as the Joint Video Team (JVT). The JVT has added additional features to the previous video coding standards (MPEG-4 and H.263) which has allowed the current H.264 to provide a much more efficient compression ability giving a bit rate reduction of about 50 % of the previous standards for the same video quality. This thesis is among the ongoing studies that deal with trying to improve the intra prediction scheme of H.264. It aims to modify the directional extrapolation scheme of the standard intra prediction and add a combined usage based on the local structure of previously reconstructed pixels surrounding the area to be coded. A new method of searching the direction of the local structure of an area using optimal filters is deployed. The method is based on the least squares algorithm. A modified coder structure is implemented in an attempt to obtain improved coding efficiency using the new prediction. The result based on visual inspection and objective evaluation of the new modified prediction against standard H.264 intra prediction is presented.

  • 286. Nilsson, Andreas
    Chrominance Assisted Sharpening of Images2004Report (Other academic)
    Abstract [en]

    This paper presents a method to sharpen an image with less amplification of the noise than conventional methods. The proposed design method uses unsharp filtering for the sharpening part and differences in the chrominance data to decide if sharpening should be performed or not. The basic idea is to only do the sharpening if there are any changes in the chrominance information. Examples are included of sharpened images with less amplification of the noise.

  • 287.
    Nilsson, Hans
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Olsson, Johan
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Bildanalys för navigering i autonoma sensor-platformar2005Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [sv]

    Det bör vara möjligt att skapa verktyg för att beskriva scenarion och med hjälp av tillgänglig mjukvara för visualisering kunna spela upp både verkliga och simulerad bilddata. Detta examensarbete beskriver hur några sådana verktyg tagits fram. Till förfogande fanns en stor mängd bilddata, insamlad på ett militärt övningsområde som dessutom finns representerad som en syntetisk omvärldsmodell. Insamlingen gjordes med en UAV (Unmanned Aerial Vehicle)- prototyp, som var utrustad med videokamera, IR-kamera och tröghetsnavigeringssystem. För att simulerad bilddata skulle få ett verklighetstroget intryck placerades markfordon ut i den syntetiska modellen på exakt samma position som under fältförsöken. Markfordonens position mättes in med DGPS och UAV:ns hastighet, position och rotation bestäms med GPS och tröghetsnavigeringssystem. Resultatet, i form av lagrad tröghetsnavigerings- och sensorstyrnings-data, ges efter en Kalmanfiltrering och blir vanligtvis noggrannare än vad som erhålls från de respektive delsystemen. Tyngdpunkten i arbetet låg i att ta fram Matlab-funktioner som plockar ut rätt vy vid rätt tidpunkt och åskådliggör detta på ett tydligt sätt, samt att placera ut markfordonen enligt de givna koordinaterna. Visualiseringen görs i SceneServer, ett program för hantering av 3Dbilder. För att samtidigt kunna presentera IR-kameran, videokameran och SceneServer-vyn vid en exakt tidpunkt skapades ett Matlab-GUI (Graphical User Interface), där en specifik tidpunkt anges och där resultatet presenteras. Dessutom nns möjligheten att skapa en AVI (Audio Video Interleaved)-sekvens mellan två tidpunkter där de tre vyerna ska vara synkroniserade. Även om verktygen för att simulera hela scenarion med fordonsförflyttningar inte hann färdigutvecklas helt, så blev resultatet med själva visualiseringsfunktionerna mycket goda, och man vet nu att att det är möjligt att genomföra visualiseringar av denna typ.

  • 288. Nilsson, Kristian
    et al.
    Zackrisson, Johan
    Pettersson, Mats
    Remote Access of Computer Controlled Experiments2008In: International Journal of Online Engineering, ISSN 1868-1646, E-ISSN 1861-2121, Vol. 4, no 4, p. 52-56Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a way for students to access and operate laboratory equipment, controlled by a laboratory computer via a remote access program. In this way, the solution is not dependent on the specific laboratory equipment, as long as the equipment can be remotely controlled. The system can easily be altered to be used in another laboratory setup. Students are able to make reservations of experiment sessions through a web interface, which is administrated by the system administrator. The solution proposed in this paper is one way to speed up the development of remote accessible laboratories. Most of the proposed solution is based on open source software and the hardware is built on ordinary consumer parts, which makes the proposed remote laboratory architecture cost effective.

  • 289. Nilsson, Kristian
    et al.
    Zackrisson, Johan
    Pettersson, Mats
    Remote Access of Computer Controlled Experiments2008Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a way for students to access and operate laboratory equipment, controlled by a laboratory computer via a remote access program. In this way, the solution is not dependent on the specific laboratory equipment, as long as the equipment can be remotely controlled. The system can easily be altered to be used in another laboratory setup. Students are able to make reservations of experiment sessions through a web interface, which is administrated by the system administrator. The solution proposed in this paper is one way to speed up the development of remote accessible laboratories. Most of the proposed solution is based on open source software and the hardware is built on ordinary consumer parts, which makes the proposed remote laboratory architecture cost effective.

  • 290.
    Nilsson, Mikael
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    First Order Hidden Markov Model: Theory and Implementation Issues2005Report (Refereed)
    Abstract [en]

    This report explains the theory of Hidden Markov Models (HMMs). The emphasis is on the theory aspects in conjunction with the implementation issues that are encountered in a floating point processor. The main theory and implementation issues are based on the use of a Gaussian Mixture Model (GMM) as the state density in the HMM, and a Continuous Density Hidden Markov Model (CDHMM) is assumed. Suggestions and advice related to the implementation are given for a typical pattern recognition task.

  • 291. Nilsson, Mikael
    On Feature Extraction and Classification in Speech and Image Processing2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The natural world is home to innumerable patterns in various forms, which humans are able to locate and interpret by means of the senses. This thesis presents and explores different techniques that mimic such behavior through the use of artificial sensors and computational power, i.e. aspects of machine learning with particular emphasis on pattern recognition. Theory and practical issues are explored with respect to two main operations; feature extraction and classification. On the topic of feature extraction, this thesis introduces a new signal processing transform, denoted the Successive Mean Quantization Transform (SMQT). The relevant theory, extensions and numerical transformations are presented, along with possible usage of this transform in various situations. Two different classifiers are investigated; the hidden Markov model and the sparse network of winnows. The hidden Markov model is a stochastic model which has been used successfully in the context of various pattern recognition applications. During the implementation of a complete system using the hidden Markov model, a number of possible numerical issues can arise. The relevant theory behind these numerical issues is presented, as are a number of possible solutions. The sparse network of winnows is a general purpose classifier. In the context of this thesis, it is tailored for the task of fast binary classification using lookup tables. Further, a scheme is proposed to split up this classifier in order to perform faster classification. This scheme is denoted the split up sparse network of winnows. The sections of this thesis dedicated to feature extraction and classification present a number of tools which are utilized further in three applications. The first application is concerned with the enhancement of noise degraded speech. Specifically, this application addresses the task of reducing non-stationary noise from speech using the hidden Markov model. The second application addresses the task of automatic image enhancement. For this task, the Successive Mean Quantization Transform is investigated. The final application is concerned with face detection. For this task, illumination problems and speed issues are discussed, along with proposed solutions.

  • 292. Nilsson, Mikael
    et al.
    Bartunek, Josef Ström
    Nordberg, Jörgen
    Claesson, Ingvar
    Human Whistle Detection and Frequency Estimation2008Conference paper (Refereed)
    Abstract [en]

    Human whistle could be a way to perform activation of different kind of devices, for example turn on and off a light in a smart room. Therefore, in this paper a human whistle detection and frequency estimation system is presented. Further, an investigation of human whistling and a robust non-linear feature extraction is presented. A system for robust performance due to sensor change and various noise situations is proposed using these features. Experiments in various noise situations are conducted.

  • 293. Nilsson, Mikael
    et al.
    Bartunek, Josef Ström
    Nordberg, Jörgen
    Claesson, Ingvar
    On Histograms and Spatiograms: Introduction of the Mapogram2008Conference paper (Refereed)
    Abstract [en]

    This paper introduces the concept of a mapogram. A mapogram may be viewed as a special form of spatiogram,which is a histogram containing additional spatial information. Additionally, this paper presents theory relevant to the creation of a proposed mapogram. A similarity measure derived from the Bhattacharyya coefficient is obtained in order to make comparisons between mapograms. Examples using a mapogram are given.

  • 294. Nilsson, Mikael
    et al.
    Dahl, Mattias
    Claesson, Ingvar
    A cepstrum domain HMM-based speech enhancement method applied to nonstationary noise2005Conference paper (Refereed)
    Abstract [en]

    This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by means of parallel model combination, using a log-normal approximation. During the compensation. the mean of every mixture in the speech and noise model is stored. The stored means are then used in the enhancement process to create the most likely speech and noise power spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.

  • 295. Nilsson, Mikael
    et al.
    Dahl, Mattias
    Claesson, Ingvar
    Gray-Scale Image Enhancement using the SMQT2005Conference paper (Refereed)
    Abstract [en]

    This paper explores the Successive Mean Quantization Transform (SMQT) for automatic enhancement of gray-scale images. The transform is in the paper presented using set theory. The image enhancement capabilities and properties of the transform are analyzed. The transform is capable to perform both a nonlinear and a shape preserving stretch of the image histogram. Experiments and comparisons to histogram equalization are conducted.

  • 296. Nilsson, Mikael
    et al.
    Dahl, Mattias
    Claesson, Ingvar
    The Successive Mean Quantization Transform2005Conference paper (Refereed)
    Abstract [en]

    This paper presents the Successive Mean Quantization Transform (SMQT). The transform reveals the organization or structure of the data and removes properties such as gain and bias. The transform is described and applied in speech processing and image processing. The SMQT is considered as an extra processing step for the mel frequency cepstral coefficients commonly used in speech recognition. In image processing the transform is applied in automatic image enhancement and dynamic range compression.

  • 297. Nilsson, Mikael
    et al.
    Nordberg, Jörgen
    Claesson, Ingvar
    Face Detection using Local SMQT Features and Split Up SNoW Classifier2007Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is threefold: firstly, the local Successive Mean Quantization Transform features are proposed for illumination and sensor insensitive operation in object recognition. Secondly, a split up Sparse Network of Winnows is presented to speed up the original classifier. Finally, the features and classifier are combined for the task of frontal face detection. Detection results are presented for the MIT+CMU and the BioID databases. With regard to this face detector, the Receiver Operation Characteristics curve for the BioID database yields the best published result. The result for the CMU+MIT database is comparable to state-of-the-art face detectors. A Matlab version of the face detection algorithm can be downloaded from http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=13701&o bjectType=FILE

  • 298. Nilsson, Mikael
    et al.
    Nordberg, Jörgen
    Håkansson, Lars
    Claesson, Ingvar
    Feature Extraction and Classification Approaches in Condition Based Monitoring2007Conference paper (Refereed)
    Abstract [en]

    Creating a supervision tool in Condition Based Monitoring (CBM) for manufacturing processes by means of a pattern recognition approach, with emphasis on the feature extraction and classification is usually a difficult task. In particular manufacturing methods like drilling, turning, milling, boring and grinding are of concern for the discussion. The issue of machine tool downtime and degraded productivity and production costs continues to plague the industry and thus urge for reliable CBM systems enabling to predict or detect vibration, estimating tool wear and detect tool breakage. Extracting relevant information and choosing a suitable classifier is far from trivial for a given CBM scenario and requires knowledge of the process involved. This paper will discuss some common techniques used and also aim to indicate possible new approaches utilizing emerging techniques from other disciplines. In particular, nonlinear techniques such as Local Binary Pattern (LBP) and variants thereof are investigated as possible techniques for feature extraction. Generative as well as discriminative classifiers are also discussed.

  • 299. Nilsson, Mikael
    et al.
    Sattar, Farook
    Chngt, Hui Kheng
    Claesson, Ingvar
    Automatic Enhancement and Subjective Evaluation of Dental X-ray Images Using the SMQT2005Conference paper (Refereed)
    Abstract [en]

    This paper investigates the Successive Mean Quantization Transform (SMQT) for enhancement of dental X-ray images. The aim is to provide an automatic tool for enhancing the dental X-rays that would aid an interpreter, who is typically a specialist in dentistry. The evaluation is performed based on a subjective test by a clinical expert/endodontist who has vast experience in dental X-ray analysis and diagnosis. Based on the subjective test for a number of dental images, this SMQT based enhancement method is found to provide a useful tool for enhancing the diagnostic value of dental X-ray images. © 2005 IEEE.

  • 300. Nordberg, Jörgen
    Blind Subband Channel Equalisation2004Conference paper (Refereed)
    Abstract [en]

    The wireless communication channel are characterized by its multipath richness. To reverse the effects of even a moderate delay spread, in the linear equalization case, will require an estimation of high order filters.

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