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  • 13501. Yeoh, Phee
    et al.
    Elkashlan, Maged
    Yang, Nan
    Benevides Da Costa, Daniel
    Duong, Quang Trung
    Blekinge Institute of Technology, School of Computing.
    MIMO multi-relay networks with TAS/MRC and TAS/SC in Weibull fading channels2012Conference paper (Refereed)
    Abstract [en]

    We examine transmit antenna selection with receiver maximal-ratio combining (TAS/MRC) and transmit antenna selection with receiver selection combining (TAS/SC) in multiple-input multiple-output (MIMO) relay networks. Amongst L two-hop relay links, a single relay offering the highest end-to-end signal-to-noise ratio (SNR) is activated. Assuming independent non-identically distributed Weibull fading between the hops, new closed-form asymptotic expressions for the outage probability and the symbol error rate are derived considering NS, NR, and ND antennas at the source, the relays, and the destination, respectively. Based on such expressions, the diversity order and the array gain for M-ary phase shift keying and M-ary quadrature amplitude modulation are analyzed. We highlight that the diversity order of TAS/MRC is the same as TAS/SC. As such, we explicitly characterize the SNR gap between TAS/MRC and TAS/SC as the ratio of their respective array gains. An interesting observation is reached that for equal per-hop SNRs, the SNR gap between the two protocols is independent of L.

  • 13502. Yeoh, Phee Lep
    et al.
    Elkashlan, Maged
    Duong, Quang Trung
    Blekinge Institute of Technology, School of Computing.
    Yang, Nan
    Leung, Cyril
    Cognitive MIMO relaying in Nakagami-m fading2013Conference paper (Refereed)
    Abstract [en]

    We propose transmit antenna selection with receive maximal-ratio combining (TAS/MRC) as an effective approach to reduce interference in cognitive multiple-input multiple-output (MIMO) relay networks. To demonstrate this, we derive new closed-form expressions for the exact and asymptotic outage probability of TAS/MRC with multiple antennas at the primary and secondary users. We consider underlay spectrum sharing where the secondary users (SUs) transmit in the presence of multiple primary users (PUs). We consider independent Nakagami-m fading in both the primary and secondary networks. Several important design insights are revealed. We find that TAS/MRC achieves a full diversity when the transmit power at the SUs is proportional to the peak interference power at the PUs. Furthermore, we highlight that this diversity gain is completely independent of the number of antennas at the PUs.

  • 13503. Yeoh, Phee Lep
    et al.
    Elkashlan, Maged
    Duong, Trung Q.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Yang, Nan
    da Costa, Daniel Benevides
    Transmit Antenna Selection for Interference Management in Cognitive Relay Networks2014In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 63, no 7, p. 3250-3262Article in journal (Refereed)
    Abstract [en]

    We propose transmit antenna selection (TAS) in decode-and-forward (DF) relaying as an effective approach to reduce the interference in underlay spectrum sharing networks with multiple primary users (PUs) and multiple antennas at the secondary users (SUs). We compare two distinct protocols: 1) TAS with receiver maximal-ratio combining (TAS/MRC) and 2) TAS with receiver selection combining (TAS/SC). For each protocol, we derive new closed-form expressions for the exact and asymptotic outage probability with independent Nakagami-m fading in the primary and secondary networks. Our results are valid for two scenarios related to the maximum SU transmit power, i.e., P, and the peak PU interference temperature, i.e., Q. When P is proportional to Q, our results confirm that TAS/MRC and TAS/SC relaying achieve the same full diversity gain. As such, the signal-to-noise ratio (SNR) advantage of TAS/MRC relaying relative to TAS/SC relaying is characterized as a simple ratio of their respective SNR gains. When P is independent of Q, we find that an outage floor is obtained in the large P regime where the SU transmit power is constrained by a fixed value of Q. This outage floor is accurately characterized by our exact and asymptotic results.

  • 13504. Yeoh, Phee Lep
    et al.
    Elkashlan, Maged
    Kim, Kyeong Jin
    Duong, Trung Quang
    Blekinge Institute of Technology, School of Computing.
    Karagiannidis, George K.
    Cognitive MIMO Relaying with Multiple Primary Transceivers2013In: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), 2013, p. 1956-1961Conference paper (Refereed)
    Abstract [en]

    We examine the impact of clusters of primary transceivers in cognitive multiple-input multiple-output (MIMO) relay networks with underlay spectrum sharing. In such a network, we propose antenna selection as an interference-aware design to satisfy the power constraints in the primary and secondary networks. To demonstrate this, we consider transmit antenna selection with maximal ratio combining (TAS/MRC) in the primary and secondary networks. With this in mind, we derive new closed-form asymptotic expressions for the outage probability and the symbol error rate (SER) over independent Nakagami-m fading channels. Our results lead to several new fundamental insights. In particular, we highlight that TAS/MRC achieves a full diversity gain when the maximum transmit power in the secondary network is proportional to the peak interference temperature in the primary network.

  • 13505. Yeoh, Phee Lep
    et al.
    Elkashlan, Maged
    Yang, Nan
    da Costa, Daniel B.
    Duong, Quang Trung
    Blekinge Institute of Technology, School of Computing.
    Unified Analysis of Transmit Antenna Selection in MIMO Multi-Relay Networks2013In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 62, no 2Article in journal (Refereed)
    Abstract [en]

    We present a unified asymptotic framework for transmit antenna selection in multiple-input multiple-output (MIMO) multi-relay networks with Rician, Nakagami-m, Weibull, and Generalized-K fading channels. We apply this framework to derive new closed-form expressions for the outage probability and symbol error rate (SER) of amplify-andforward relaying in MIMO multi-relay networks with two distinct protocols: 1) transmit antenna selection with receiver maximalratio combining (TAS/MRC), and 2) transmit antenna selection with receiver selection combining (TAS/SC). Based on these expressions, the diversity order and the array gain with M-ary phase shift keying and M-ary quadrature amplitude modulation are derived.We corroborate that the diversity order only depends on the fading distribution and the number of diversity branches, whereas the array gain depends on the fading distribution, the modulation format, the number of diversity branches, and the average per-hop signal-to-noise ratios (SNRs). We highlight that the diversity order of TAS/MRC is the same as TAS/SC, regardless of the underlying fading distribution. As such, we explicitly characterize the SNR gap between TAS/MRC and TAS/SC as the ratio of their respective array gains. An interesting observation is reached that for equal per-hop SNRs, the SNR gap between the two protocols is independent of the number of relays.

  • 13506. Yeoh, Phee Lep
    et al.
    Elkashlan, Maged
    Yang, Nan
    da Costa, Daniel
    Duong, Quang Trung
    Blekinge Institute of Technology, School of Computing.
    Unified Analysis of Transmit Antenna Selection in MIMO Multirelay Networks2013In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 62, no 2, p. 933-939Article in journal (Refereed)
    Abstract [en]

    We present a unified asymptotic framework for transmit antenna selection in multiple-input multiple-output (MIMO) multirelay networks with Rician, Nakagami-m, Weibull, and generalized-K fading channels. We apply this framework to derive new closed-form expressions for the outage probability and symbol error rate (SER) of amplify-and-forward (AF) relaying in MIMO multirelay networks with two distinct protocols: 1) transmit antenna selection with receiver maximal-ratio combining (TAS/MRC) and 2) transmit antenna selection with receiver selection combining (TAS/SC). Based on these expressions, the diversity order and the array gain with M-ary phase-shift keying and M-ary quadrature-amplitude modulation are derived. We corroborate that the diversity order only depends on the fading distribution and the number of diversity branches, whereas the array gain depends on the fading distribution, the modulation format, the number of diversity branches, and the average per-hop signal-to-noise ratios (SNRs). We highlight that the diversity order of TAS/MRC is the same as TAS/SC, regardless of the underlying fading distribution. As such, we explicitly characterize the SNR gap between TAS/MRC and TAS/SC as the ratio of their respective array gains. An interesting observation is reached that for equal per-hop SNRs, the SNR gap between the two protocols is independent of the number of relays.

  • 13507. Yermeche, Zohra
    Soft-Constrained Subband Beamforming for Speech Enhancement2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    New speech acquisition applications are emerging as a result of advances in technology and the prevalence of mobile communication. While today voice control of consumer equipment is becoming a reality, communication technology has extended voice connectivity to personal computers and mobile communication devices with the aim of enabling natural communication in a variety of environments such as cars, restaurants and offices. The comfort and flexibility provided through the hands-free acquisition of speech in mobile telephony, speech recognition and hearing aids require robust techniques to deal with problems of environmental noise, reverberation, acoustic feedback and other interfering sounds which corrupt the received speech. For mobile environments, speech enhancement techniques should also provide an adaptation capacity to speaker motion with no perceptible degradations of the original speech. In this thesis, multi-microphone techniques for speech enhancement are developed. First, a framework for constrained beamforming is introduced. This framework allows us to control the tradeoff relationship between noise reduction, dereverberation and speech degradation. A constraint on the power minimization of the beamformer’s output is formulated to guarantee the integrity of the desired signal. It is shown that the robustness towards microphone mismatch of the soft-constrained beamforming structure is guaranteed by modeling the source as spatially spread. A subband recursive least-squares (RLS) beamformer is investigated and evaluated in real handsfree acoustical environments. The proposed methodology is defined to perform background noise and interference reduction, while a soft constraint built from calibration data in low noise conditions guarantees the undistorted filtering of the desired signal. This adaptive structure allows for a tracking of the noise characteristics, so as to efficiently accomplish its attenuation. A subband beamforming structure is used to improve the performance of the system and reduce the computational complexity. A real-time DSP implementation is described and evaluated for dual microphone speech enhancement. Furthermore, a novel blind soft-constrained beamforming approach for moving source speech enhancement is presented. It is based on a soft constraint defined for a delay-spread corresponding to a volume around the speech source location. A new speech-oriented time-delay estimation algorithm is combined with the beamformer to allow for speaker movement. The proposed method does not require any calibration data, knowledge of the array manifold or any other characteristics of the acoustical environment. Hence, it provides means to blindly enhance a dominant speaker in adverse noise conditions. This structure is further developed to allow for the detection and enhancement of multiple dominant speakers in a mixture of interferences and background noise. The use of a frequency-dependent constraint region opens the path for a trade-off between noise suppression and speech integrity.

  • 13508. Yermeche, Zohra
    Subband Beamforming for Speech Enhancement in Hands-Free Communication2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Speech enhancement by means of microphone array signal processing has a major role in voice communication applications such as audio-conferencing, hands-free telephony, voice recognition and hearing aids. In these communication scenarios, the speaker is positioned at a remote distance from the microphones, which causes problems of environment noise and interfering sound corrupting the received speech. Additionally, reverberations of the voice from walls or ceilings, also impairs the received speech signal. In the case of a duplex communication, the acoustic feedback constitutes another disturbance for the talker who hears his or her voice echoed. Successful speech enhancement solutions should achieve speech dereverberation, efficient noise and interference reduction, and for mobile environments, they should also provide an adaptation capacity to speaker motion. Microphone arrays spatially sample the sound pressure field. When combined with spatio-temporal filtering techniques known as {\em beamforming}, they can extract the sound source information from signals, of which only a mixture is observed. This is based on the inherent ability of sensor arrays to exploit the spatial correlation of multiple received signals. A subband beamforming structure can be used in order to improve the performance of the time-domain filters and reduce their computational complexity. Each of the received signals is decomposed into a set of narrow-band signals and the filtering operations of the beamformer are performed for each frequency band separately. The output of the subband beamformers are then used to reconstruct a full-band output signal. In this thesis an adaptive subband RLS beamforming approach is investigated and evaluated in real hands-free acoustical environments. The proposed methodology is defined such to perform background noise and acoustic coupling reduction, while producing an undistorted filtered version of the signal originating from a desired location. The beamformer recursively minimizes a Least Squares error based on the continuously received data. This adaptive structure allows for a tracking of the noise characteristics, such to accomplish its attenuation in an efficient manner. A soft constraint built from calibration data in low noise conditions guarantee the integrity of the desired signal without the need of any speech detection. Additionally, a new spatial filter bank design method for beamforming applications, which includes the constraint of signal passage at one position and closing in other undesired positions, is suggested. Furthermore, to allow for source mobility tracking, a soft constrained beamforming approach with built-in speaker localization, is proposed. The source of interest is modelled as a cluster of point sources and source motion is accommodated by revising the point source cluster. Real speech signals are used in the simulations and results show accurate speaker movement tractability with maintained noise and interference suppression of about 10-15 dB, when using a four-microphone array.

  • 13509. Yermeche, Zohra
    et al.
    Cornelius, Per
    Grbic, Nedelko
    Claesson, Ingvar
    Spatial Filter Bank Design for Speech Enhancement Beamforming Applications2004Conference paper (Refereed)
    Abstract [en]

    In this paper, a new spatial filter bank design method for speech enhancement beamforming applications is presented. The aim of this design is to construct a set of different filter banks that would include the constraint of signal passage at one position (and closing in other positions corresponding to known disturbing sources). By performing the directional opening towards the desired location in the fixed filter bank structure, the beamformer is left with the task of tracking and suppressing the continuously emerging noise sources. This algorithm has been implemented in MATLAB and tested on real speech recordings conducted in a car hands-free communication situation. Results show that a reduction of the total complexity can be achieved while maintaining the noise suppression performance and reducing the speech distortion.

  • 13510. Yermeche, Zohra
    et al.
    Garcia, Pilar Márquez
    Grbic, Nedelko
    Claesson, Ingvar
    A Calibrated Subband Beamforming Algorithm for Speech Enhancement2002Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new calibrated adaptive frequency domain beamformer for speech enhancement. The beamformer is based on the principle of a soft constraint formed from calibration data, rather than precalculated from free-field assumptions. The benefit is that the real room acoustical properties will be taken into account. The proposed algorithm continuously estimates the spatial information for each frequency band, based on weighting of the received data. The update of the beamforming weights is done recursively where the initial precalculated correlation estimates of the speech constitute a soft constraint. The soft constraint secures the spatial-temporal passage of the desired source signal, without the need of any speech detection. The performance is evaluated in real world scenarios, both in a car-and a restaurant- environment. Interference and noise sup-pression of more than 15 dB is accomplished, while very small distortion is measured for the source signal.

  • 13511. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    A Delay-Based Constrained Beamformer for Blind Speech Enhancement and Dereverberation2007Conference paper (Refereed)
    Abstract [en]

    This paper presents a new microphone array method to enhance speech signals in a noisy reverberant environment. A time-delay estimation method is used for the speech source localization. The robustness of the localization method in high noise levels is provided by a subband Kurtosis-weighted structure. The estimated inter-sensor time-delays are directly used in an adaptive soft-constrained subband beamformer. Evaluation in a simulated environment with real speech sequences shows promising results.

  • 13512. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    Claesson, Ingvar
    Beamforming for Moving Source Speech Enhancement2005Conference paper (Refereed)
    Abstract [en]

    This paper presents a new constrained subband beamforming algorithm to enhance speech signals generated by a moving source in a noisy environment. The beamformer is based on the principle of a soft constraint defined for a specified region corresponding to a known source location. The soft constraint secures the spatial-temporal passage of the desired source signal in the adaptive update of the beamforming weights and guarantees the full rank property of the matrix inverted in the update. The source of interest is modelled as a cluster of stationary point sources and source motion is accommodated by revising the point source cluster. The source modelling and its direct exploitation in the beamformer through covariance estimates are presented. An algorithm for sound source localization is used for speaker movement tracking and this information is exploited to update the spatial distribution in the source model. Evaluation in a real environment with a moving speaker shows a significant noise and hands-free interference suppression within the conventional telephone bandwidth. This is achieved with a negligible impact on speech distortion.

  • 13513. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    Claesson, Ingvar
    Bind Subband Beamforming with Time-delay Constraints for Moving Source Speech Enhancement2007In: IEEE Transactions on Audio, Speech, and Language Processing, ISSN 1558-7916, E-ISSN 1558-7924, Vol. 15, no 8, p. 2360-2372 Article in journal (Refereed)
    Abstract [en]

    A new robust microphone array method to enhance speech signals generated by a moving person in a noisy environment is presented. This blind approach is based on a two-stage scheme. First, a subband time-delay estimation method is used to localize the dominant speech source. The second stage involves speech enhancement, based on the acquired spatial information, by means of a soft-constrained subband beamformer. The novelty of the proposed method involves considering the spatial spreading of the sound source as equivalent to a time-delay spreading, thus, allowing for the estimated intersensor time-delays to be directly used in the beamforming operations. In comparison to previous approaches, this new method requires no special array geometry, knowledge of the array manifold, or acquisition of calibration data to adapt the array weights. Furthermore, such a scheme allows for the beamformer to efficiently adapt to speaker movement. The robustness of the time-delay estimation of speech signals in high noise levels is improved by making use of the non-Gaussian nature of speech trough a subband Kurtosis-weighted structure. Evaluation in a real environment with a moving speaker shows promising results, with suppression levels of up to 16 dB for background noise and interfering (speech) signals, associated to a relatively small effect of speech distortion.

  • 13514. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    Claesson, Ingvar
    Blind Subband Beamforming for Speech Enhancement of Multiple Speakers2006Conference paper (Refereed)
    Abstract [en]

    A new blind microphone array method to enhance speech signals generated by multiple sources in a noisy environment is proposed. This approach is based on a two-stage scheme. A subband time-delay estimation algorithm is first used to localize the dominant speech sources. The speech enhancement is performed in a second stage, based on the acquired spatial information, by means of a spatially constrained subband beamformer. The robustness of this structure is ensured by the spatial constraint constructed to include the discrepancies in the acoustical environment model as well as errors in the time-delay estimation. Such scheme also allows for an efficient adaptation of the beamformer to speakers movement. The proposed subband approach for time-delay estimation exploits the sparseness of speech signals in the time-frequency domain to localize multiple speakers simultaneously. It also provides means to select the number of target sources. Evaluation in a real environment shows promising results.

  • 13515. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    Claesson, Ingvar
    Blind Subband Beamforming With Time-Delay Constraints for Moving Source Speech Enhancement2007In: IEEE Transactions on Audio, Speech, and Language Processing, ISSN 1558-7916, E-ISSN 1558-7924, Vol. 15, no 8, p. 2360-2372Article in journal (Refereed)
    Abstract [en]

    A new robust microphone array method to enhance speech signals generated by a moving person in a noisy environment is presented. This blind approach is based on a two-stage scheme. First, a subband time-delay estimation method is used to localize the dominant speech source. The second stage involves speech enhancement, based on the acquired spatial information, by means of a soft-constrained subband beamformer. The novelty of the proposed method involves considering the spatial spreading of the sound source as equivalent to a time-delay spreading, thus, allowing for the estimated intersensor time-delays to be directly used in the beamforming operations. In comparison to previous approaches, this new method requires no special array geometry, knowledge of the array manifold, or acquisition of calibration data to adapt the array weights. Furthermore, such a scheme allows for the beamformer to efficiently adapt to speaker movement. The robustness of the time-delay estimation of speech signals in high noise levels is improved by making use of the non-Gaussian nature of speech trough a subband Kurtosis-weighted structure. Evaluation in a real environment with a moving speaker shows promising results, with suppression levels of up to 16 dB for background noise and interfering (speech) signals, associated to a relatively small effect of speech distortion.

  • 13516. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    Claesson, Ingvar
    Moving Source Speech Enhancement Using Time-Delay Estimation2005Conference paper (Refereed)
    Abstract [en]

    This paper presents a new constrained subband beamforming algorithm to enhance speech signals generated by a moving source in a noisy environment. The beamformer is based on the principle of a soft constraint calculated from an estimated source position. The soft constraint secures the spatial-temporal passage of the desired source signal in the adaptive update of the beamforming weights and guaranties the full rank property of the covariance matrix inverted in the update. This approach allows for an efficient adaptation of the beamformer to speaker movement by using a tracking algorithm for sound source time-delay estimation. The proposed method has the benefit of taking into consideration the discrepancies in the acoustical environment model as well as errors in the time-delay estimation. Evaluation in a real environment with a moving speaker in a hands-free situation shows up to 10~dB noise suppression and 20~dB interference suppression within the conventional telephone bandwidth. This is achieved with a negligible impact on target signal distortion.

  • 13517. Yermeche, Zohra
    et al.
    Grbic, Nedelko
    Claesson, Ingvar
    Speech enhancement of multiple moving sources based on subband clustering time-delay estimation2006Conference paper (Refereed)
    Abstract [en]

    A new robust blind microphone array method to enhance speech signals generated by multiple moving sources in a noisy environment is presented. This approach is based on a two-stage scheme. A subband clustering time-delay estimation algorithm is first used to localize the dominant speech sources. The speech enhancement is performed in a second stage, based on the acquired spatial information, by means of a soft-constrained subband beamformer. The robustness of this structure is ensured by the spatial constraint constructed to include the discrepancies in the acoustical environment model as well as errors in the time-delay estimation. Such scheme also allows for an efficient adaptation of the beamformer to speakers movement. The proposed subband clustering approach for time-delay estimation exploits the sparseness of speech signals in the time-frequency domain to localize multiple speakers simultaneously. It also provides means to select the number of target sources. Evaluation in a real environment with moving speakers shows promising results.

  • 13518. Yermeche, Zohra
    et al.
    Sällberg, Benny
    Grbic, Nedelko
    Claesson, Ingvar
    Real-Time DSP Implementation of a Subband Beamforming Algorithm for Dual Microphone Speech Enhancement2007Conference paper (Refereed)
    Abstract [en]

    A real-time Digital Signal Processor (DSP) based implementation of a subband beamforming algorithm and its evaluation for dual microphone speech enhancement is presented. The algorithm, a calibrated constrained beamformer, is described theoretically and a real-time structure is proposed, including an efficient approach for multichannel data transformation. Measurements show that the battery driven DSP implementation supports 20 h operation-time, with an improved Signal-to-Noise Ratio (SNR) of up to 14~dB in high-noise factory environment. Further, less than half the provided computational performance of the DSP is used by the proposed method, hence, processing of additional tasks may be included.

  • 13519.
    Yerragudi, Panduranga Sri Charan
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Balija, Venkatesh
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Identication and Matching of Headstamp of Cartridge Using Iris Detection Algorithm2016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Identication of cartridge is very essential in the field of forensics, military or people who collect ammunitions. The cartridges can beidentied by their headstamps.This thesis presents work on identification and matching of cartridge headstamp from the image. The Libor Masek's open source iris recognition algorithm is considered for the identification of cartridge pattern from the image.The dataset is devoleped with the cartridge headstamp patterns and matching of cartridge headstamp patterns is implemented. For matching of the cartridge pattern the Hamming distance is considered as the metric to differentiate interclass and intraclass comparisons. Variance is used as a criteria to discard the unwanted areas of the cartridge headstamp pattern.Four distinct cartridge headstamp patterns are considered. Three cartridges of each headstamp pattern are considered for intra class comparisons. The validation of the method is performed.

  • 13520.
    Yerramsetty, Hemanth
    Blekinge Institute of Technology, School of Engineering.
    Microphone Array Wiener Beamformer and Speaker Localization With emphasis on WOLA Filter Bank2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    This thesis describes the design and implementation of a speech enhancement system that uses 4-channel microphone array beam forming and speech enhancement algorithms applied to a speech signal in a multiple source environment. To locate the accurate Direction of Arrival (DOA) from the source, it is necessary to design a suitable microphone array system with more efficient localization algorithm. The goal of the system is to improve the quality of the primary speech signal. A filter bank is a signal processing tool that can facilitate manipulation of signals in the frequency domain. The WOLA (Weighted Overlap and Add) filter is an efficient method used to implement a uniformly distributed multi-channel filter bank. The WOLA is generally used in applications that demand high quality filters in term of stop band rejection and filter shape. Beamformers work by means of steering an array of microphones towards a desired look direction through utilizing signal information rather than physically moving the array. In this research, Wiener beam former is examined the input signals are first split into frequency bands so that Wiener beam forming techniques can be used. There are many algorithms developed for estimating the number of sources and locating the DOA, such as Bayesian algorithm, kalman filtering, Generalized Cross Correlation (GCC) and Steered Response Power (SRP) algorithm. But SRP algorithm with its steered beam forming technique for speaker localization is more robust using microphone array. The Phase Alignment Transform (PHAT) has gained a lot of attention in the recent research for its quite robust response in low noise, but reverberant environment. So combining SRP-PHAT will become the robust localizer in reverberant environment. Experiments were done on recorded data of human talkers. The algorithm gives accurate DOA from the dominant speaker. In addition to these, listener opinion testing is performed.

  • 13521.
    Yevdokymenko, Maryna
    et al.
    Kharkiv Natl Univ Radio Elect, UKR.
    Shapovalova, Anastasiia
    Kharkiv Natl Univ Radio Elect, UKR.
    Voloshchuk, Olena
    Kharkiv Natl Univ Radio Elect, UKR.
    Carlsson, Anders
    Blekinge Inst Technol, Comp & Commun Syst Dept, Karlskrona, Sweden..
    Proactive Approach for Security of the Infocommunication Network Based on Vulnerability Assessment2018In: 2018 International Scientific-Practical Conference on Problems of Infocommunications Science and Technology, PIC S and T 2018 - Proceedings: PROBLEMS OF INFOCOMMUNICATIONS SCIENCE AND TECHNOLOGY (PIC S&T), IEEE , 2018, p. 609-612, article id 8632079Conference paper (Refereed)
    Abstract [en]

    The paper explores methods for assessing vulnerabilities and assessing the spread of an attack in an infocommunication network. A proactive approach to the quantitative assessment of network security, which allows us to assess risks at the user and network level through the presence of vulnerabilities is presented. The proposed solutions will be useful for decision making and will be further integrated into a single metric for displaying the integrated level of security of the infocommunication network.

  • 13522. Ygge, Fredrik
    Market-Oriented Programming and its Application to Power Load Management1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Market-oriented programming is a new approach to design and implementation of resource allocation mechanisms in computer systems. It has its roots in different disciplines, such as economics and computer science (in particular the area of multi-agent systems. This thesis is divided into two different parts, focusing on: 1) central foundations and mechanisms of market-oriented programming, and 2) the use of market-oriented programming in practical applications. Market-oriented programming is seen as a programming paradigm based on abstractions such as prices and demands. Concepts, terminology and theory from micro-economics form the foundations of the paradigm. Central aspects of these foundations are investigated and some new insights are presented. Furthermore, some relations between standard optimization/resource allocation approaches and markets are described, and novel theorems are introduced. A plethora of algorithms (some stemming from mathematical optimization and numerical analysis, and some new) for the main computational problem of market-oriented programming -- the computation of general equilibrium -- are described, analyzed and compared. Some issues of self-interested agents in market-oriented programming are also investigated. A published, and generally recognized, market-oriented approach to the application building climate control is analyzed in some detail. A new approach to this application, based on market-oriented programming, is introduced and shown to be superior to the analyzed approach in many ways. The case study pinpoints a number of potential pitfalls as well as advantages of market-oriented approaches to this and other applications. A second investigated application is power load management, i.e. the management of loads at the customers' side for obtaining more efficient energy systems management. The basis of the application is described and a new market-oriented approach is introduced and analyzed. The approach is shown to have a number of advantages compared to existing approaches to this problem. The main conclusion of the thesis is that there are some potential pitfalls of market-oriented programming, but when used with care it provides a highly natural and efficient means for resource allocation in computer systems.

  • 13523. Ygge, Fredrik
    Power Load Management as a Multi-Commodity Market1997Report (Other academic)
    Abstract [en]

    The current report investigates the application of market-oriented programming to power load management. Power load management (or load management for short) is the management of loads at the customer side in order to manage energy systems more efficiently. As energy systems are very large and heavily distributed (typically including millions of loads in an area covering counties or countries), efficient and conceptually attractive methods are required for making load management successful. This report demonstrates how market-oriented programming can be utilized to meet the above demands.

  • 13524. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Duality in Multi-Commodity Market Computations1997Report (Other academic)
    Abstract [en]

    In search for general equilibrium in multi-commodity markets, price-oriented schemes are normally used. That is, a set of prices (one price for each commodity) is updated until supply meets demand for each commodity. It is well known that in a two-commodity market resource-oriented schemes are conceivable. In this paper we demonstrate the duality between price- and resource-oriented schemes in the general multi-commodity case. We also discuss important properties of the two approaches. In resource-oriented schemes the resource constraint, which says that supply must equal demand, is always fulfilled, implying that at any time the auctioneer can provide a feasible allocation. This is not the case in price-oriented schemes outside market equilibrium. In this paper we introduce a novel any-time algorithm, Proportion, for the price-oriented scheme as well, that allows the auctioneer to deliver a suitable allocation at some deadline (possibly unknown in advance) also before market equilibrium is reached. We also show how the findings for the any-time algorithms can enable more efficient price-oriented markets.

  • 13525. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Duality in Multi-Commodity Market Computations1997Conference paper (Refereed)
  • 13526. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Making a Case for Multi-Agent Systems1997Conference paper (Refereed)
    Abstract [en]

    Multi agent systems (MAS) promise to offer solutions to problems where established, older paradigms fall short. To be able to keep promises, however, in depth studies of advantages and weaknesses of MAS solutions versus conventional ones in practical applications are needed. We offer one such study. Climate control in large buildings is one application area where MAS, and market oriented programming in particular, have been reported to be very successful. We have therefore constructed and implemented a variety of market designs for this problem, as well as different standard control engineering solutions. The paper gives a detailed analysis and comparison, so as to learn about differences between standard versus MAS approaches, and yielding new insights about benefits and limitations of computational markets.

  • 13527. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Making a Case for Multi-Agent Systems1997Report (Other academic)
    Abstract [en]

    Multi-Agent Systems (MAS) promise to offer solutions to problems were established, older paradigms fall short. To be able to keep promises, however, in-depth studies of advantages and weaknesses of MAS solutions versus conventional ones in practical applications are needed. In this paper we offer one such study. Climate control in large buildings is one application area where MAS, and market-oriented programming in particular, have been reported to be very successful. We have therefore constructed and implemented a variety of market designs for this problem, as well as different standard control engineering solutions. This paper gives a detailed analysis and comparison, so as to learn about differences between standard versus MAS approaches, and yielding new insights about benefits and limitations of computational markets.

  • 13528. Ygge, Fredrik
    et al.
    Akkermans, Hans
    On Resource-Oriented Multi-Commodity Market Computations1998Report (Other academic)
    Abstract [en]

    In search for general equilibrium in multi-commodity markets, price-oriented schemes are normally used. That is, a set of prices (one price for each commodity) is updated until supply meets demand for each commodity. In some cases such an approach is very inefficient, and a resource-oriented scheme can be highly competitive. In a resource-oriented scheme the allocations are updated until the market equilibrium is found. It is well known that in a two-commodity market resource-oriented schemes are possible. In this paper we show that resource-oriented algorithms can be used for the general multi-commodity case as well, and present and analyze a specific algorithm. The algorithm has been implemented and some performance properties, for a specific example, are presented.

  • 13529. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Power Load Management as a Computational Market1996Conference paper (Refereed)
    Abstract [en]

    Power load management enables energy utilities to reduce peak loads and thereby save money. Due to the large number of different loads, power load management is a complicated optimization problem. We present a new decentralized approach to this problem by modeling direct load management as a computational market. Our simulation results demonstrate that our approach is very efficient with a superlinear rate of convergence to equilibrium and an excellent scalability, requiring few iterations even when the number of agents is in the order of one thousand. A framework for analysis of this and similar problems is given which shows how nonlinear optimization and numerical mathematics can be exploited to characterize, compare and tailor problem-solving strategies in market-oriented programming.

  • 13530. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Power Load Management as a Computational Market1996Report (Other academic)
    Abstract [en]

    Power load management enables energy utilities to reduce peak loads and thereby save money. Due to the large number of different loads, power load management is a complicated optimization problem. We present a new decentralized approach to this problem by modeling direct load management as a computational market. Our simulation results demonstrate that our approach is very efficient with a superlinear rate of convergence to equilibrium and an excellent scalability, requiring few iterations even when the number of agents is in the order of one thousand. A framework for analysis of this and similar problems is given which shows how nonlinear optimization and numerical mathematics can be exploited to characterize, compare, and tailor problem-solving strategies in market-oriented programming.

  • 13531. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Smart Software as Customer Assistant in Large-Scale Distributed Load Management1997Report (Other academic)
    Abstract [en]

    Advanced information systems present a key enabling technology for innovative customer-oriented services by the utility industry. Real-time and two-way electronic information exchange with the customer over the power grid and other media is now possible. This provides the baseline for a host of new customer services, provided proper advantage is taken of a variety of recent advances in information technology. In this context, we discuss (a) how to engineer knowledge into systems and services, giving rise to smart software and intelligent systems, and (b) how to exploit this practically for novel ways to achieve distributed load management, dealing with thousands of devices simultaneously. A special characteristic of our concept is that the two-way information exchange for load-balancing purposes is based on market mechanisms similar to an auction. This auction is carried out by small smart software programs in devices (such as radiators) that represent and assist the customer. Field experiments with this intelligent and distributed new approach to power load management are currently performed.

  • 13532. Ygge, Fredrik
    et al.
    Akkermans, Hans
    Andersson, Arne
    A Multi-Commodity Market Approach to Power Load Management1998Report (Other academic)
    Abstract [en]

    Power load management is the concept of controlling the loads at the demand side in order to run energy systems more efficiently. Energy systems are inherently highly distributed and contain large number of loads, up to some million. This implies that computationally and conceptually attractive methods are required for this application. In this paper we give two novel theorems for how to decompose general resource allocation problems into markets. We also introduce a novel multi-commodity market design to meet the demands of power load management. The approach is demonstrated to lead to very high quality allocations, and to have a number of advantages compared to current methods.

  • 13533. Ygge, Fredrik
    et al.
    Astor, Eric
    Interacting Intelligent Software Agents in Demand Management1995Conference paper (Refereed)
    Abstract [en]

    Even though distributed computing and two-way communication with the customer is becoming a reality for many energy distribution companies, there is still a need to develop methodologies for more efficient energy management. In this paper we discuss current approaches to demand management, and then present ideas from other areas applied in energy management. We introduce concepts such as computational markets and software agents in this context. In addition, methods entirely based on distributed problem solving to address the computationally hard problems of resource allocation with vast number of clients are described. We also discuss how these methods can be used to perform cost/benefit analysis of demand management.

  • 13534. Ygge, Fredrik
    et al.
    Astor, Eric
    Interacting Intelligent Software Agents in Distribution management1995Report (Other academic)
    Abstract [en]

    Even though distributed computing and two-way communication with the customer is becoming a reality for many energy distribution companies, there still is a need to develop methodologies for more efficient energy management. In this paper we discuss current approaches to demand management, and then present ideas from other areas applied to energy management. We introduce concepts such as computational markets and software agents in this context. In addition, methods entirely based on distributed problem solving to address the computationally hard problems of resource allocation with vast number of clients are described. We also discuss how these methods can be used to perform cost/benefit analysis of demand management.

  • 13535. Ygge, Fredrik
    et al.
    Gustavsson, Rune
    Akkermans, Hans
    HOMEBOTS: Intelligent Agents for Decentralized Load Management1996Conference paper (Refereed)
  • 13536.
    Yi, Xin
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
    Data visualization in conceptual design: developing a prototype for complex data visualization2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today's highly competitive industries, engineers are driven to not only design a better product to fulfill users' needs but also demanded to develop a product in a short time to occupy the market. With the development of data collection and visualization technology, the application of data visualization into product development to enhance the ability of better product design is a significant trend. 

    Data visualization becomes more and more important since it could illustrate the valuable information, such as tacit needs and patterns which hidden from data, in a communicated way to help engineers get more inspiration for the conceptual design.

     

    It is not hard to collect data; however, the challenge is to visualize the valuable information from a large number of data concisely and intuitively. In recent years, there are some visualization techniques available for product design, while, most of them are implemented in the later stage of product development, few methods are applicable for conceptual design. Therefore, this thesis is carried out to explore appropriate visualization techniques to provide support for conceptual design.

     

    The aim of this thesis is, in an engineering environment, to investigate ways to visualize complex data legibly and intuitively to enhance engineers’ ability for conceptual design from better understanding the current machine. In order to achieve the objective, a conceptual design case of the improvement of wheel loader fuel consumption is applied, which consisted of plenty of data sets within various parameters, to explore how to reveal the hidden information of complex data for engineers.

     

    As the result of this thesis, a prototype contains a series of visualization techniques is proposed to demonstrate data information from a wheel loader under several visualization situations. The final prototype has the functions of visualizing different operations separately; visualizing the overall fuel consumption in one operation; cluster's patterns visualization; visualizing the impact of one variable on the whole value.

  • 13537.
    Yigit, Mert
    Blekinge Institute of Technology, School of Management.
    Organizational Ambidexterity: Balancing Exploitation and Exploration in Organizations2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Purpose: This paper aims to investigate necessity of ambidexterity for organizations. The main interest of this thesis is to investigate why organizations should be ambidextrous and how organizations can reach ambidexterity under the pressure of limited resources and competitive market condition. Findings: This thesis explored relations and tensions between exploitation and exploration in organizational and individual aspects. Findings in the research show that communication skill of the subunits in the case company need to be strengthened. Subunits need to be independent from each other. However, they should be aware of other subunits’ actions. In this sense, there is need for strong information flow between all units in the case company. Participation of employees and teamwork should be promoted by leaders. This thesis suggests that establishing special subunits for explorative activities would not only leverage explorative processes in the organizations but it would also leverage exploitative activities. This issue causes time management and scheduling problem for the employees and also individuals are distracted by focusing on conflicting dimensions such as explorative and exploitative tasks. Behavioral integrity is one of the most important subjects. Behavioral integrity is the key factor to provide consistency between subunits. Independent subunits with common vision lead firms to ambidexterity. Implications: The implications of this study contribute to achievement of organizational ambidexterity in companies. This thesis was started with introduction to importance of ambidexterity, organizational ambidexterity, exploration and exploitation in case of long and short term organizational performance in sight of knowledge based and managerial perspective. It also explored relations and tensions between these dimensions such as exploration and exploitation in terms of organizational and individual aspects, contextual and structural ambidexterity, social support and performance management, dynamic and ambidextrous capabilities with implication of case study research.

  • 13538.
    YILMAZ, FATIH
    Blekinge Institute of Technology, School of Engineering.
    Static and Dynamic Analysis of Älvsbacka Timber Bridge2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    ABSTRACT This thesis is part of a research project in the company of SP, Sweden to investigate the static and dynamic behaviors of Älvsbacka Timber Bridge that known as ‘a smart bridge’. In this context the investigation of project was carried out with simulations and experiments. The Simulation of the bridge was created by using the software program MULTIFRAME 4D®.The simulation analysis includes Finite Element Method, Modal Analysis, Static & Dynamic Force Analyzes. After all simulation analysis, in order to verify the results of the simulations, some experimental tests were performed at Älvsbacka Timber Bridge. The obtained real data which comes from the experimental tests were implemented by use MATLAB® software program. After all investigations, it was achieved as a conclusion of that the results of simulation and experiments showed a good correspondence.

  • 13539.
    Yilmaz, Gulay
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Sound Source Localization by Using Two Microphones2014Student thesis
    Abstract [en]

    This thesis work presents the way of locating the sound source by using two microphone. The idea to approach the goal is based on the Time di fference of Arrival Estimation (TDOA). There are several ways to the TDOA such as the generalized cross-correlation (GCC) and Steered Response Power (SRP).The most common technique used in TDOA estimation is the generalized cross-correlation (GCC). But Steered Response Power PHAT (SRP-PHAT) together with the Windowed Discrete Fourier Transform(WDFT) are mainly focused on this thesis work.

  • 13540.
    Ying, PuLe
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Fan, LingZhi
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Methods For Test Case Prioritization Based On Test Case Execution History2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Motivation: Test case prioritization can prioritize test cases, optimize the test execution, save time and cost. There are many different methods for test case prioritization, test case prioritization method based on test case execution history is one kind of them. Based on the test case execution history, it’s easier to increase the rate of fault detection, hence we want to do a study about test case prioritization methods based on the test case execution history. Meanwhile, executing the feasible methods to compare the effectiveness of them. For the motivation of the thesis may be regarded as an example for experiencing approach for comparing test case prioritizations based on test case execution history, or as a study case for identifying the suitable methods to use and help improve the effectiveness of the testing process.

    Objectives: The aim of this thesis is to look for a suitable test case prioritization method that can support risk based testing, in which test case execution history is employed as the key criterion of evaluation. For this research, there are three main objectives. First, explore and summarize methods of test case prioritization based on test case history. Next, identify what are differences among the test case prioritization methods. Finally, execute the methods which we selected, and compare the effectiveness of methods.

    Methods: To achieve the first and the second study objectives, a systematic literature review has been conducted using Kitchenham guidelines. To achieve the third study objective, an experiment was conducted following Wohlin guidelines.

    Results: In our thesis: 1) We conducted a systematic literature review and selected 15 relevant literatures. We extracted data of the literatures and then we synthesized the data. We found that the methods have different kinds of inputs, test levels, maturity levels, validation and "automated testing or manual testing". 2) We selected two feasible methods from those 15 literatures, Method 1 is Adaptive test-case prioritization and Method 2 is Similarity-based test quality metric. We executed the methods within 17 test suites. Comparing the result of two methods and non-prioritization, the mean Average Percentage of Defects Found (APFD) of Adaptive test-case prioritization execution result (86.9%) is significantly higher than non-prioritization (51.5%) and Similarity-based test quality metric (47.5%), it means that the Adaptive test-case prioritization has higher effectiveness.

    Conclusion: In our thesis, existing test case prioritization methods based on test case execution history are extracted and listed out through systematic literature review. The summary of them and the description of differences can be available in the thesis. The 15 relevant literatures and the synthesized data may be as a guideline for relevant software researchers or testers. We did the statistical test for the experimental result, we can see two different test case prioritization methods have different effectiveness.

  • 13541.
    YiPing, Jin
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering. Shanghai Second Polytechnic University.
    Long, Tao
    Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering. Kungming University of science and technology.
    Boat Storage System2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays, people have a boat of themselves become more and more popular. People use their boat for fishing trip and taking holiday. However, most of them do not want to take care of their boat by themselves. One of the reasons might be the place of a boat occupied. Recently, a method has been used is to store boat on the Boat Hotel. They pay for the rent of a boat garage and also hire someone to take care of their boat. Place the boat on the boat shelf with several layers is the most common method. They use forklift to take in/out the boat when boat owner need use their boat. On the conditional of this situation, if we want to take a boat which is inside of boat shelf, then we need take all outside boat out.  It’s really an inefficiency way, so we need improve it.

    In this study, we aim to design a Boat Storage System based on the existing shelf and meet all requirement of existing boat. This system should be reliable, efficient, economic, operable and flexible.

    The main function of the Boat Storage System is to take in/off the boat more quickly and automatically and efficiently. The system is similar with the stereo parking garage. Which have a paternoster controlled by PLC program. Consider of the boat is heavier than the car. Our storage structure should be more stable.

    Our design only need one person to operate it. The whole process will cost few seconds. This building will be established in the water. Therefore, the owner only need to push the button and then the boat will be prepared in the water automatically.

    The modelling and assembly was designed in Autodesk Inventor 2017. This hardware circuit of PLC was drawn in AutoCAD. The software to design the PLC is GX Works 2. And we used ANSYS Workbench 17.2 to analysis the structure. The analysis will prove the structure is safety and strong enough. And the simulation will prove the system is possible. Our conclusion is that this system has a good future and general application in the market.

  • 13542.
    Yiran, Zhou
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    Yilei, Liu
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    The Challenges and Mitigation Strategies of Using DevOps during Software Development2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 13543. Yiu, K. F. C
    et al.
    Chan, K. Y
    Grbic, Nedelko
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Nordholm, Sven
    A Hybrid Design Of Beamformers For Voice Control Devices2012In: Pacific Journal of Optimization, ISSN 1348-9151, E-ISSN 1349-8169, Vol. 8, no 3, p. 533-544Article in journal (Refereed)
    Abstract [en]

    In this paper, a new approach to designing beamformers for voice control device is proposed. It is well-known that under a strong near-field noise with low signal-to-noise ratios (SNR), the performance of speech recognition is deteriorated significantly. However, designing the beamformer for enhancing speech recognition is a slow process and might not be adapted easily to the changing noise environment. In order to lower the complexity of the design, we intend to exploit the combination of existing optimal beamformer designs, which can be implemented in parallel. These include the least-squares technique and the signal-to-noise ratio maximization technique. We show here that for a given pre-trained speech recognizer and for a finite set of speech commands, neither method has a satisfactory performance in speech recognition accuracy under very low SNRs. However, since the two techniques have different characteristics in speech distortion and noise suppression, we show that it is possible to enhance the speech recognition accuracy by combining these two optimal designs.

  • 13544. Yiu, Ka Fai Cedric
    et al.
    Grbic, Nedelko
    Nordholm, Sven
    Teo, Kok Ley
    A hybrid method for the design of oversampled uniform DFT filter banks2006In: Signal Processing, ISSN 0165-1684 , Vol. 86, no 7, p. 1355-1364Article in journal (Refereed)
    Abstract [en]

    Subband adaptive filters have been proposed to speed up the convergence and to lower the computational complexity of time domain adaptive filters. However, subband processing causes signal degradations due to aliasing effects and amplitude distortions. This problem is unavoidable due to further filtering operations in subbands. In this paper, the problem of aliasing effect and amplitude distortion is studied. The prototype filter design problem is formulated as a multi-criteria optimization problem and all the Pareto optima are sought. Since the problem is highly nonlinear and nonsmooth, a new hybrid optimization method is proposed. Different prototype filters are used and their performances are compared. Moreover, the effect of the number of subbands, the oversampling factors and the length of prototype filter are also studied. We find that prototype filters designed via Kaiser or Dolph–Chebyshev window provide the best overall performance. Also, there is a critical oversampling factor beyond which the improvement in performance is not justified. Finally, if the length of the prototype filter increases with the number of subbands, an increase in the subband level will not deteriorate the performance.

  • 13545. Yiu, Ka Fai Cedric
    et al.
    Grbic, Nedelko
    Nordholm, Sven
    Teo, Kok Ley
    Multicriteria Design of Oversampled Uniform DFT Filter Banks2004In: IEEE Signal Processing Letters, ISSN 1070-9908, E-ISSN 1558-2361, Vol. 11, no 6, p. 541-544Article in journal (Refereed)
    Abstract [en]

    Subband adaptive filters have been proposed to avoid the drawbacks of slow convergence and high computational complexity associated with time domain adaptive filters. However, subband processing causes signal degradations due to aliasing effects and amplitude distortions. This problem is unavoidable due to further filtering operations in subbands. In this letter, the problems of aliasing effect and amplitude distortion are studied. Prototype filters which are optimized with respect to those properties are designed and their performances are compared. Moreover, the effect of the number of subbands, the oversampling factors and the length of the prototype filter are also studied. Using the multicriteria formulation, all Pareto optimums are sought via the nonlinear programming technique. We find that the prototype filter designed via the Kaiser window provides the best overall performance among the methods we studied. Also, there is a critical oversampling factor beyond which the improvement of performance is diminishing. Finally, if the length of the prototype filter increases with the number of subbands, an increase in the number of subbands will not deteriorate the performance.

  • 13546. Yiu, Ka Fai Cedric
    et al.
    Ho, Chun Hok
    Grbic, Nedelko
    Lu, Yao
    Shi, Xiaoxiang
    Luk, Wayne
    Reconfigurable Acceleration of Microphone Array Algorithms for Speech Enhancement2008Conference paper (Refereed)
    Abstract [en]

    Microphone arrays play an important role in noise reduction and speech enhancement. Their algorithms are based on beamforming, which reduces the level of localized and ambient noise signals while minimizing distortion to speech from the desired direction via spatial filtering. This paper describes a class of subband beamforming algorithms. The similarity between different algorithms is discussed. To enhance computational efficiency, the algorithms are implemented in frequency domain. A hardware architecture, with bitwidth optimization, is proposed to support the algorithms. An implementation with 7 instances on a Xilinx XC4VSX55 FPGA at 175MHz can run 41.7 times faster than the corresponding pure software implementation on a 3.2GHz Pentium 4 PC. ©2008 IEEE.

  • 13547. Yiu, KFC
    et al.
    Gao, MJ
    Shiu, TJ
    Wu, SY
    Tran, Trung Quang
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Claesson, Ingvar
    Blekinge Institute of Technology, School of Engineering, Department of Electrical Engineering.
    A fast algorithm for the optimal design of high accuracy windows in signal processing2013In: Optimization Methods and Software, ISSN 1055-6788, E-ISSN 1029-4937, Vol. 28, no 4, p. 900-916Article in journal (Refereed)
    Abstract [en]

    This paper presents a new optimal window design method with a general window design specification for the passband and stopband. The design problem is formulated as a semi-infinite linear programming problem. With suitable discretizations, an exchange algorithm is employed. The convergence of the proposed algorithm is established. In the formulation, since the stopband is minimized, the method can be employed for the design of very highly optimized windows.

  • 13548. Ylinenpää, Håkan
    et al.
    Larsson, Tobias
    Luleå University of Technology.
    Westerberg, Mats
    Open approaches and methods to enable Functional Product Development2007Conference paper (Refereed)
    Abstract [en]

    There is a need to develop approaches and methods for accessing necessary information early into the process of developing innovative (functional) products. Such information is normally located outside the focal company, and thus requires communication and tools/methods that enable decoding weak signals from different sources, not least from end users, i.e., human beings. Information based on human criterions, e.g., perceptions, experiences, activities and goals, is recognised as vital to communicate into the development process of innovative products. In this context, concepts such as Business Intelligence, Bench Learning, Lead-User Innovation, and Needfinding have been developed. In general, the logic behind such approaches is to avoid tunnel-vision and the Not-Invented-Here syndrome by widening the space for input into the product development process, and thereby identify more (and more potential) routes for further product and service development.

  • 13549.
    Yngvesson, Robert
    Blekinge Institute of Technology, Faculty of Engineering, Department of Spatial Planning.
    Promoting physical activities in urban landscapes: A case study of Rosenholm, Karlskrona, Sweden2014Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Sedentary lifestyle means less normal physical activity, less fitness among the population at large. This may lead to lower health, increased risk of cardiac disease. Less fitness also influences the psychological state of mind, leading to lower self-esteem. To remedy this, more physical activity should be encouraged among the people. To these physical and psychological needs the fact that more and more people live or are in daily contact with cities is added, which means the urban landscapes play a role in motivating physical activity. Different urban landscapes affect the motivation in different ways. This thesis investigated how physical activity is affected by urban landscapes socially, environmentally, economically and by policies, and how to implement a multifunctional exercise area in Rosenholm, Karlskrona, Sweden. Methods such as literature review, interviews, site analyzes and case studies were made in order to get promote theories based on research to design an “Innovative Complete and Optimal Training-track” in Rosenholm together with a development group initiated by “Blekinge Health Arena”. Motivating physical activity can be promoted by measures belonging to the field of urban design, by taking physical, economic, social and cultural factors into account together with policies in all levels. Policymaking is an essential way to increase physical activities among the population and to affect the built environment, which is discussed in this thesis. In order to promote physical activities in urban areas there is no simple solution to apply in order to get results. There is no design to fit them all. Simply creating good opportunities to perform physical activity by means of urban landscapes cannot solve the fact that the public health is decreasing by lack of physical activity. This is as much, if not more, a matter of motivation and change in behavior. But in order to get motivation and to change behavior an environment offering opportunities and possibilities to perform physical activity and at the same time offers socializing is a good start. There are so many dimensions and aspects that need to be considered and are specific in each and every case. A design proposal was made in the Rosenholm case study where various aspects discussed in this thesis were considered displayed by maps, renderings and images.

  • 13550.
    Ynner, Patricia
    et al.
    Blekinge Institute of Technology, Faculty of Engineering, Department of Health.
    Eliasson, Anna
    Blekinge Institute of Technology, Faculty of Engineering, Department of Health.
    Hur patienter med psykossjukdomar upplever att vara inlagda inom den psykiatriska slutenvården: En innehållsanalys baserad på patografier2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bakgrund: En psykossjukdom är ett tillstånd då verklighetsuppfattningen förändras med tillkommande symtom som vanföreställningar, hallucinationer samt förvirring. Vårdpersonal har generellt en sämre attityd mot patienter med psykossjukdomar och det finns begränsad med forskning om hur patienterna upplever detta.

    Syfte: Syftet med studien var att beskriva hur patienter med psykossjukdomar upplever att vara inlagda inom psykiatrisk slutenvård.

    Metod: En kvalitativ innehållsanalys med induktiv ansats baserad på fem patografier. Analysen inspirerades av Lundman och Hällgren Graneheims modell för innehållsanalys med meningsenheter, kondensering, koder, underkategorier och kategorier.

    Resultat: Analysen ledde fram till fyra kategorier och två underkategorier. Tydlig rollfördelning mellan vårdpersonal och patient, Bristen på information och förtroende, Negativa affekter och negativ tillvaro och Medmänsklighet från vårdpersonal med tillhörande underkategorier vikten av goda handlingar och bevarad värdighet och självbestämmande.

    Slutsats: Studien visade att patienterna hade delade upplevelser av att vara inlagda inom den psykiatriska slutenvården. De negativa upplevelserna var fler än de positiva. Det framkom dock ur de positiva upplevelserna att vårdpersonal som utgick från Joyce Travelbees human-to-human-relationship model, om än omedvetet, gjorde att patienterna och vårdpersonalen etablerade betydelsefulla vårdrelationer och att patienterna då fann en mening med att vara inlagda.

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