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Adaptive CFAR processor for nonhomogeneous environments
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 36, Issue 3 PART 1 , 2000 , Pages 889-897 ; 00189251 (ISSN) ; Mohammad, K ; Bastani, H ; Sharif University of Technology
2000
Abstract
A new constant false alarm rate (CFAR) processor is presented, that exhibits a noticeable detection performance in the presence of interfering targets, as well as an excellent false alarm rate (FAR) regulation at the clutter power transition regions. The presented CFAR processor, which is designed to work on the logarithmic amplified video signals, can also easily adapt itself to new environmental conditions. Furthermore, in the steady state, its performance does not depend on the background noise power. Simulation results show the obvious preference of the presented processor to the conventional GOCA-LOG/CFAR, regarding FAR regulation at the clutter power transition regions. Noncoherent...
Measuring minimum critical flow for normal breath sounds
, Article 2005 27th Annual International Conference of the Engineering in Medicine and Biology Society, IEEE-EMBS 2005, Shanghai, 1 September 2005 through 4 September 2005 ; Volume 7 VOLS , 2005 , Pages 2726-2729 ; 05891019 (ISSN); 0780387406 (ISBN); 9780780387409 (ISBN) ; Moussavi, Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2005
Abstract
Relationship between respiratory sounds and flow has always been of interest for researchers and physicians. However, the flow-sound relationship at very low flow rate has been questionable because breath sounds must exceed a minimum flow in order to be audible and different from the background noise. This study aimed to find the minimum critical flow rates for respiratory sounds to be audible and different from background noise. Tracheal and lung sound signals of healthy subjects in two groups of adults (12 subjects) and children (9 subjects) were studied. The values of minimum critical flow were determined comparing the spectrogram of the respiratory sounds at very low flow with that of...
Cooperative abnormality detection in fluidic medium molecular communication
, Article 2020 Iran Workshop on Communication and Information Theory, IWCIT 2020 ; 26-28 May , 2020 ; Mirmohseni, M ; Nasiri Kenari, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In this paper, we study the problem of cooperative abnormality detection using mobile sensors in a fluidic medium, based on a molecular communication setup. The sensors are injected into the medium to search the environment for the abnormality. To reduce the effects of sensor imperfection, we propose a cooperative scheme where the sensors activate each other by releasing some molecules (i.e., markers), into the medium after they sense an abnormality. A number of fusion centers (FC) are placed at specific locations in the medium, which absorb all sensors arrived at their locations. By observing the states of the received sensors, each FC decides whether an abnormality exists in its...
Speech Enhancement Using Deep Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Sameti, Hossein (Supervisor)
Abstract
Quality and intelligibility are two aspects of speech that are affected by various factors, such as background noise and echo. The performance of many commercial and military speech-based systems depends on at least one of these aspects of speech. Therefore, this research aims to design an improvement model to remove background noise and reverberation from the speech signal. The model training framework is based on deep learning methods and has a supervised approach in the time domain. The input of this system is the raw waveform of the speech signal mixed with noise and reverberation, and the output is the enhanced waveform of this signal. An architecture is proposed in this thesis based on...
Ultrasound dosimetery using microbubbles
, Article IFMBE Proceedings, 20 June 2011 through 23 June 2011 ; Volume 35 IFMBE , June , 2011 , Pages 359-362 ; 16800737 (ISSN) ; 9783642217289 (ISBN) ; Zahedi, E ; Tavakkoli, J ; Sharif University of Technology
2011
Abstract
In this paper, a new technique based on nonlinear resonance of microbubbles is investigated in order to estimate the amplitude of an ultrasound wave pressure field. First, the existing theoretical model is reviewed. Then, an experimental setup consisting of a bubble generator and transmitting/receiving ultrasound transducers operating in the 1 MHz frequency range is described. The effect of background noise is also taken into account. Results show that the second harmonic oscillations are detectable, paving the way to develop a quantitative method for in vivo calibration of ultrasound waves
Multiuser detector for airborne co-located multiple input/multiple output radar using compressive measurements
, Article IET Radar, Sonar and Navigation ; Volume 11, Issue 2 , 2017 , Pages 260-268 ; 17518784 (ISSN) ; Salehi, J. A ; Hariri, A ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
This study presents and analyses a novel joint detection and parameters estimation of multiple targets using a co-located multiple input/multiple output radar with moving platform, in the presence of clutter and background noise. A notable feature of the proposed approach is that clutter cancellation is independent of received data. Moreover, to decrease the computational load, the authors propose to perform the target detection and parameters estimation by directly processing on the compressive measurements as opposed to Nyquist samples. © The Institution of Engineering and Technology
Graphic: Graph-based hierarchical clustering for single-molecule localization microscopy
, Article 18th IEEE International Symposium on Biomedical Imaging, ISBI 2021, 13 April 2021 through 16 April 2021 ; Volume 2021-April , 2021 , Pages 1892-1896 ; 19457928 (ISSN); 9781665412469 (ISBN) ; Aziznejad, S ; Unser, M ; Sage, D ; Sharif University of Technology
IEEE Computer Society
2021
Abstract
We propose a novel method for the clustering of point-cloud data that originate from single-molecule localization microscopy (SMLM). Our scheme has the ability to infer a hierarchical structure from the data. It takes a particular relevance when quantitatively analyzing the biological particles of interest at different scales. It assumes a prior neither on the shape of particles nor on the background noise. Our multiscale clustering pipeline is built upon graph theory. At each scale, we first construct a weighted graph that represents the SMLM data. Next, we find clusters using spectral clustering. We then use the output of this clustering algorithm to build the graph in the next scale; in...
An optimum MMSE post-filter for Adaptive Noise Cancellation in automobile environment
, Article 2012 11th International Conference on Information Science, Signal Processing and their Applications, ISSPA 2012 ; 2012 , Pages 431-435 ; 9781467303828 (ISBN) ; Sameti, H ; Veisi, H ; Sharif University of Technology
2012
Abstract
Adaptive Noise Cancellation (ANC) is an effective dual-channel technique for background noise reduction. Due to the presence of uncorrelated noise components at the two inputs in vehicular environments, ANC does not provide sufficient background noise reduction. To alleviate this problem, a complementary linear filter is added to ANC structure. Filter coefficients are determined to make the enhanced signal an MMSE estimation of speech signal. Therefore, the ANC structure is modified to a dual-channel Wiener structure. We prove that this structure is identical to the LMS type ANC which is followed by a Wiener post-filter. A new method is proposed for the noise spectrum estimation in the...
A Kalman filter approach to packet loss replacement in presence of additive noise
, Article 2012 11th International Conference on Information Science, Signal Processing and their Applications, ISSPA 2012 ; 2012 , Pages 310-314 ; 9781467303828 (ISBN) ; Ghorshi, S ; Tahaei, A ; Sharif University of Technology
2012
Abstract
A major problem in real-time packet-based communication systems, is misrouted or delayed packet which results in degraded perceived voice quality. If packets are not available on time, the packets are considered lost. The easiest solution in a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid degradation in speech quality due to packet loss, a suitable method or algorithm is needed to replace the missing segments of speech. In this paper, we introduce an adaptive filter for replacement of lost speech segment. In this method Kalman filter as a state-space based method will be used to predict the clean...
Kalman filter method for packet loss replacement in presence of background noise
, Article International Multi-Conference on Systems, Signals and Devices, SSD 2012 - Summary Proceedings, 20 March 2012 through 23 March 2012 ; March , 2012 ; 9781467315906 (ISBN) ; Ghorshi, S ; Tahaei, A ; Rahimi, A ; Sharif University of Technology
2012
Abstract
A major problem in real-time packet-based communication systems, is misrouted or delayed packets which results in degraded perceived voice quality. If packets are not available on time, the packets are considered as lost. The easiest solution in a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid degradation in speech quality due to packet loss, a suitable method or algorithm is needed to replace the missing segments of speech. In this paper, we introduce an adaptive filter for replacement of lost speech segment. In this method Kalman filter as a state-space based method will be used to predict the clean...
A new TH-CDMA scheme for dispersive infrared channel and its performance evaluation
, Article Journal of Optical Communications ; Volume 32, Issue 1 , 2011 , Pages 21-36 ; 01734911 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
2011
Abstract
Infrared indoor wireless communications using nondirected links are subject to severe multipath distortion which causes intersymbol interference (ISI). To lessen multipath distortion effect and thereby to improve the system performance, in this paper, we consider a new time-hopping based multiple access scheme for this channel, in which one pulse is transmitted in each bit interval. The position of the pulse is determined based on the output of a low rate error correcting code along with the user's dedicated PN code. We evaluate the multiple access performance of the system for correlation receiver considering background noise, dark current, and thermal noise. We compare the performance of...
Optimal wavelength allocation in hybrid quantum-classical networks
, Article European Signal Processing Conference, 28 August 2016 through 2 September 2016 ; Volume 2016-November , 2016 , Pages 483-487 ; 22195491 (ISSN) ; 9780992862657 (ISBN) ; Razavi, M ; Salehi, J. A ; Sharif University of Technology
European Signal Processing Conference, EUSIPCO
2016
Abstract
An efficient method for optimal allocation of wavelengths in a hybrid dense-wavelength-division-multiplexing system, carrying both quantum and classical data, is proposed. The transmission of quantum bits alongside intense classical signals on the same fiber faces major challenges arising from the background noise generated by classical channels. Raman scattering, in particular, is shown to have detrimental effects on the performance of quantum key distribution systems. Here, by using a nearly optimal wavelength allocation technique, we minimize the Raman induced background noise on quantum channels, hence maximize the achievable secret key generation rate for quantum channels. It turns out...
Orthogonal frequency division multiplexed quantum key distribution in the presence of Raman noise
, Article Proceedings of SPIE - The International Society for Optical Engineering, 5 April 2016 through 7 April 2016 ; Volume 9900 , 2016 ; 0277786X (ISSN) ; 9781510601451 (ISBN) ; Razavi, M ; Salehi, J. A ; Sharif University of Technology
SPIE
2016
Abstract
In this paper, we investigate the performance of orthogonal frequency division multiplexed quantum key distribution (OFDM-QKD) in an integrated quantum-classical wavelength-division-multiplexing system. The presence of an intense classical signal alongside the quantum one generates Raman background noise. Noise reduction techniques should, then, be carried out at the receiver to suppress this crosstalk noise. In this work, we show that OFDM-QKD enables efficient filtering, in time and frequency domains, making it an attractive solution for the high-rate links at the core of quantum-classical networks
Noise reduction in OCT skin images
, Article Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 12 February 2017 through 14 February 2017 ; Volume 10137 , 2017 ; 16057422 (ISSN) ; 9781510607194 (ISBN) ; Fatemizadeh, E ; Adabi, S ; Mehregan, D ; Daveluy, S ; Nasiriavanaki, M ; Gimi, B ; Krol, A ; Sharif University of Technology
Abstract
OCT skin images suffer from artifacts. Speckle is the main artifact while the other one is called background noise. In this study, we propose an algorithm that significantly reduces the background noise before applying a speckle reduction method. The results show that the diagnostically relevant features in the images become clearer after applying the proposed method. We used sub-pixel weighted median filtering for speckle reduction. The results from background noise removal in combination with the proposed speckle reduction algorithm show a significant improvement in the clarity of diagnostically relevant features in in-vivo human skin images. © 2017 SPIE
Design and implementation of vector quantizer for a 600 bps vocoder based on MELP
, Article 11th International Conference on Advanced Communication Technology, ICACT 2009, Phoenix Park, 15 February 2009 through 18 February 2009 ; Volume 2 , 2009 , Pages 1487-1490 ; 17389445 (ISSN); 9788955191387 (ISBN) ; Ardebilipour, M ; Sameti, H ; IEEE Communications Society, IEEE ComSoc; IEEE Region 10 and IEEE Daejeon Section; Korean Institute of Communication Sciences, KICS; lEEK Communications Society, IEEK ComSoc; Korean Institute of Information Scientists and Engineers, KIISE; et al ; Sharif University of Technology
2009
Abstract
This paper describes a vector quantization of a 600 bps speech coding parameters based on the Mixed Excitation Linear Prediction (MELP) model, which was accepted as a standard in communication on narrow-band HF channels. The MELP speech coders are robust in difficult background noise environments and intended mostly for military communications. To reduce the bit rate, a joint vector quantization of multi-frame is developed that takes advantage of inherent inter-frame redundancy of the MELP parameters. By grouping parameters of 4 frames into a multi-frame and using vector quantization, bit rate is decreased 4 times and output speech is still intelligible
A new lattic LP-based post filter for adaptive noise cancellers in mobile and vehicular applications
, Article Proceedings of the 8th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2008, 16 December 2008 through 19 December 2008, Sarajevo ; 2008 , Pages 407-412 ; 9781424435555 (ISBN) ; Sameti, H ; Veisi, H ; Abutalebi, H. R ; Sharif University of Technology
2008
Abstract
Adaptive Noise Cancellation (ANC) is a well-known technique for background noise reduction in automobile and vehicular environments. The noise fields in automobile and other vehicle interior obey the diffuse noise field model closely. On the other hand, the ANC does not provide sufficient noise reduction in the diffuse noise fields. In this paper, a new multistage post-filter is designed for ANC as a solution to diffuse noise conditions. The designed post-filter is a single channel Linear Prediction (LP) based speech enhancement system. The LP is performed by an adaptive lattice filter and attempts to extract speech components by using intermediate ANC signals. The post-filter has no...
Fluorescent microscopy using localized excitation source with gold nanotriangles: A computational study
, Article Photonics and Nanostructures - Fundamentals and Applications ; Volume 9, Issue 3 , 2011 , Pages 219-224 ; 15694410 (ISSN) ; Rashidian, B ; Vossoughi, M ; Sharif University of Technology
2011
Abstract
A new method for fluorescent microscopy has been proposed. Proposed method uses indirect excitation of fluorophores with nanometer localized illuminating source. Localized source is created at corners of gold nanotriangles which are deposited on glass substrate. Actually the combination of gold nanotriangle (deposited on glass) acts as active substrate (where species will be placed) for our proposed method. The structure will be scanned with a focused beam of laser (or combination of beams). Due to electric field enhancement in corners and edges of nanotringle (because of surface plasmons), third order nonlinear effect will be enhanced accordingly. Enhancement in third order nonlinearity...