Search for: subbands
0.006 seconds

    A low complexity NSAF algorithm

    , Article IEEE Signal Processing Letters ; Volume 19, Issue 11 , August , 2012 , Pages 716-719 ; 10709908 (ISSN) Rabiee, M ; Attari, M. A ; Ghaemmaghami, S ; Sharif University of Technology
    IEEE  2012
    This letter proposes a novel normalized subband adaptive filter (NSAF) algorithm, which applies variable step sizes to subband filters to improve the convergence performance of the conventional NSAF and update only a subset of the subbands per iteration to reduce its computational complexity. The selection process for each subband is based on the amount of improvement it makes to the mean square deviation at every iteration. Simulation results show significant reduction in computational complexity, faster convergence rate, and lower misadjustment error achieved using the proposed scheme  

    Filter-bank design based on dependencies between frequency components and phoneme characteristics

    , Article European Signal Processing Conference, 29 August 2011 through 2 September 2011 ; Septembe , 2011 , Pages 2142-2145 ; 22195491 (ISSN) Mohammadi, S. H ; Sameti, H ; Tavanaei, A ; Soltani Farani, A ; Sharif University of Technology
    Mel-frequency Cepstral coefficients are widely used for feature extraction in speech recognition systems. These features use Mel-scaled filters. A new filter-bank based on dependencies between frequency components and phoneme characteristics is proposed. F-ratio and mutual information are used for this purpose. A new filter-bank is designed in which frequency resolution of sub-band filters is inversely proportional to the computed dependency values. These new filterbank is used instead of Mel-scaled filters for feature extraction. A phoneme recognition experiment on FARSDAT Persian language database showed that features extracted using the proposed filter-bank reach higher accuracy (63.92%)... 

    Mean-square performance analysis of the family of selective partial update and selective regressor affine projection algorithms

    , Article Signal Processing ; Volume 90, Issue 1 , 2010 , Pages 197-206 ; 01651684 (ISSN) Esfand Abadi, M. S ; Palangi, H ; Sharif University of Technology
    In this paper we present a general formalism for the establishment and mean-square performance analysis of the family of selective partial update affine projection (SPU-AP), selective regressor affine projection (SR-AP), and selective partial update subband adaptive filter (SPU-SAF) algorithms. This analysis is based on energy conservation arguments and does not need to assume a Gaussian or white distribution for the regressors. We demonstrate through simulations that the results are useful in predicting the performance of these adaptive filter algorithms  

    A new framework based on recurrence quantification analysis for epileptic seizure detection

    , Article IEEE Journal of Biomedical and Health Informatics ; Volume 17, Issue 3 , 2013 , Pages 572-578 ; 21682194 (ISSN) Niknazar, M ; Mousavi, S. R ; Vosoughi Vahdat, B ; Sayyah, M ; Sharif University of Technology
    This study presents applying recurrence quantification analysis (RQA) on EEG recordings and their subbands: delta, theta, alpha, beta, and gamma for epileptic seizure detection. RQA is adopted since it does not require assumptions about stationarity, length of signal, and noise. The decomposition of the original EEG into its five constituent subbands helps better identification of the dynamical system of EEG signal. This leads to better classification of the database into three groups: Healthy subjects, epileptic subjects during a seizure-free interval (Interictal) and epileptic subjects during a seizure course (Ictal). The proposed algorithm is applied to an epileptic EEG dataset provided... 

    Distributed subband, rate and power allocation in OFDMA based two-tier femtocell networks using fractional frequency reuse

    , Article IEEE Wireless Communications and Networking Conference, WCNC, 1 April 2012 through 4 ; 2012 , Pages 2626-2630 ; 15253511 (ISSN) ; 9781467304375 (ISBN) Salati, A. H ; Nasiri Kenari, M ; Sadeghi, P ; Sharif University of Technology
    IEEE  2012
    Femtocell has appeared as a solution to increase both coverage and capacity of cellular networks. However, interference problem between the macrocell and the femtocell must be solved before any deployment. In this paper, we deal with the problem of joint subband, rate, and power allocation in OFDMA based two-tier femtocell networks. It is assumed that for macrocell users, spectrum allocation is accomplished through Fractional Frequency Reuse (FFR). Our objective is to maximize the femtocell user's throughput while maintaining as little as possible reduction in the macrocell users' performance. Our proposed algorithm is decentralized, and needs to be done only when femtocell access point is... 

    Temporal resolution enhancement of video sequences using transform domain

    , Article Proceedings of the 2008 International Conference on Image Processing, Computer Vision, and Pattern Recognition, IPCV 2008, 14 July 2008 through 17 July 2008, Las Vegas, NV ; 2008 , Pages 185-190 ; 1601320787 (ISBN); 9781601320780 (ISBN) Atrianfar, H ; Atrianfar, M ; Atrianfar, H ; Sharif University of Technology
    Temporal interpolation has been recently proposed as a solution for increasing temporal resolution or even for predicting missing or corrupted frames within a video sequence . In this paper new technique on temporal interpolation are presented, by mainly exploiting properties of the very popular and highly efficient transforms such as Discrete Cosine Transform and Discrete Wavelet Transform . Novelty of the approach is that resolution enhancement is done by adding the new coefficients in transform domain . In addition we further give a method for computing PSNR of the frames . Finally simulation on a number of video sequences is presented in order to compare the performance of this two... 

    A robust wavelet-based approach to fingerprint indentification

    , Article Proceedings of the 2012 IEEE International Conference on Multimedia and Expo Workshops, ICMEW 2012 ; 2012 , Pages 413-417 ; 9780769547299 (ISBN) Omidyeganeh, M ; Javadtalab, A ; Ghaemmaghami, S ; Shirmohammadi, S ; Sharif University of Technology
    IEEE  2012
    A robust fingerprint recognition system based on marginal statistics of 2D wavelet transform is introduced which significantly improves the accuracy of previous wavelet based approaches due to 1) a better selection of features extracted from the wavelet transform, and 2) a more accurate distance measure to find the similarity between fingerprints. A combination of Jain and Poincare algorithms is employed to locate the fingerprint reference point. The main part of the fingerprint image is chosen as a rectangle with the reference point at its center. The image is then divided into nonoverlapping sub-images, the wavelet transform is applied to the bi-level sub-images, and Generalized Gaussian... 

    Conductor-insulator transition and electronic structure of Ca-doped BiFeO 3 films

    , Article Materials Letters ; Volume 83 , 2012 , Pages 124-126 ; 0167577X (ISSN) Ahadi, K ; Nemati, A ; Mahdavi, S. M ; Sharif University of Technology
    Elsevier  2012
    The electronic conductor-insulator transition in Ca-doped BiFeO 3 films grown by pulsed-laser deposition technique has been investigated. Nature of the transition is resolved to be Mott type through the control of band-filling. Calcium resolved to have colossal effect on enhancing the electrical conductivity of BiFeO 3, but it did not affect band gap of the mother phase perceptibly. UV-visible study yielded band gap of 2.72-2.81 eV (at 300 K) for different concentrations of calcium. Both UV-visible and photoluminescence spectra revealed sub-band gap transitions at 2.17 and 2.38 eV, of which the latter might be ascribed to the oxygen vacancies  

    Wideband spectrum sensing in unknown white Gaussian noise

    , Article IET Communications ; Volume 2, Issue 6 , 2008 , Pages 763-771 ; 17518628 (ISSN) Taherpour, A ; Gazor, S ; Nasiri Kenari, M ; Sharif University of Technology
    The spectrum sensing of a wideband frequency range is studied by dividing it into multiple subbands. It is assumed that in each subband either a primary user (PU) is active or absent in a additive white Gaussian noise environment with an unknown variance. It is also assumed that at least a minimum given number of subbands are vacant of PUs. In this multiple interrelated hypothesis testing problem, the noise variance is estimated and a generalised likelihood ratio detector is proposed to identify possible spectrum holes at a secondary user (SU). Provided that it is known that a specific PU can occupy a subset of subbands simultaneously, a grouping algorithm which allows faster spectrum...