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low-pass-filter
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Design and Implenentation of a Bandpass Delta-sigma Modulator Using High-Q N-path Filter
, M.Sc. Thesis Sharif University of Technology ; Atarodi,Mojtaba (Supervisor) ; Sharifkhani, Mohammad (Co-Supervisor)
Abstract
Delta-Sigma Analog-to-Digital converters have been positioned themselves as robust reliable converters so far. The magic Of extracting high resolutions from low bit ADC has made them popular between designers. Previously, the noise-shaping magic was used in high-resolution applications such as high-quality audio signal converters. However, as the technology scales and proceeds, these converters are approaching RF applications, too. Power and OSR trade-off limits this progress. To increase OSR in bandpass delta-sigma modulators, more power should be consumed to increase the quality factor of loop filters. In this thesis, a systematic approach has been utilized. An n-path filter is employed...
Design and Simulation of Integrated Bio-Impedance Driver and Sensor Circuits
, M.Sc. Thesis Sharif University of Technology ; Sharifkhani, Mohammad (Supervisor)
Abstract
Cardiovascular diseases stand as leading contributors to human mortality and disability, with heart muscle diseases, particularly acute and chronic failures, prevalent among them. While various diagnostic methods exist, an accurate, non-invasive, portable, easily accessible, and minimally disruptive approach for monitoring, requiring no frequent clinic visits, takes precedence. Early diagnosis and continuous fluid status monitoring through bioimpedance measurements of chest size are crucial in mitigating the mortality associated with these diseases. Utilizing bioimpedance as a non-invasive signal, this system facilitates ongoing vital parameter monitoring, treatment strategy optimization,...
Comparison of uniform and random sampling for speech and music signals
, Article 2017 12th International Conference on Sampling Theory and Applications, SampTA 2017, 3 July 2017 through 7 July 2017 ; 2017 , Pages 552-555 ; 9781538615652 (ISBN) ; Shahsavari, S ; Marvasti, F ; Sharif University of Technology
Abstract
In this paper, we will provide a comparison between uniform and random sampling for speech and music signals. There are various sampling and recovery methods for audio signals. Here, we only investigate uniform and random schemes for sampling and basic low-pass filtering and iterative method with adaptive thresholding for recovery. The simulation results indicate that uniform sampling with cubic spline interpolation outperforms other sampling and recovery methods. © 2017 IEEE
A robust machine learning structure for driving events recognition using smartphone motion sensors
, Article Journal of Intelligent Transportation Systems: Technology, Planning, and Operations ; 2022 ; 15472450 (ISSN) ; Taheri Sarteshnizi, I ; Samimi, A ; Sarvi, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Driving behavior monitoring by smartphone sensors is one of the most investigated approaches to ameliorate road safety. Various methods are adopted in the literature; however, to the best of our knowledge, their robustness to the prediction of new unseen data from different drivers and road conditions is not explored. In this paper, a two-phase Machine Learning (ML) method with taking advantage of high-pass, low-pass, and wavelet filters is developed to detect driving brakes and turns. In the first phase, accelerometer and gyroscope filtered time series are fed into Random Forest and Artificial Neural Network classifiers, and the suspicious intervals are extracted by a high recall. Following...
Reduction of oscillations via fractional order pre-filtering
, Article Signal Processing ; Volume 107 , February , 2015 , Pages 407-414 ; 01651684 (ISSN) ; Sharif University of Technology
Elsevier
2015
Abstract
In this paper, an effective way is proposed for reduction of oscillations in the response of dynamical systems. In this regard, it is analytically shown that the undesirable oscillations in the response of dynamical systems can be reduced using a simple input shaping fractional order filter. The effectiveness of the proposed fractional calculus based technique is numerically verified in reduction of oscillations in a mass-spring-damper system, a low-pass Chebyshev filter, and a PI-controlled two-mass drive system
A new high-speed class-AB current-mode circuit
, Article 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007, New Orleans, LA, 27 May 2007 through 30 May 2007 ; 2007 , Pages 717-720 ; 02714310 (ISSN) ; Bakhtiar, M. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2007
Abstract
this paper presents a new class AB circuit for current-mode signal processing. The proposed circuit provides high-dynamic range, low distortion and accurate definition of quiescent current and it is well suited for high-speed applications. A third-order low-pass filter with a cutoff frequency of 200MHz and 51dB dynamic range is also presented. The Alter consumes 2.7mW from 1.8V supply. © 2007 IEEE
Ultra-low power frequency-shift keying demodulator based on injection-locking ring oscillator without using phase locked loop for wireless body area networks
, Article Electronics Letters ; Volume 53, Issue 16 , 2017 , Pages 1148-1150 ; 00135194 (ISSN) ; Safarian, A ; Sharif University of Technology
Abstract
An ultra-low power frequency-shift keying (FSK) demodulator based on injection-locking ring oscillator for wireless body area networks is presented. The proposed system uses the power-efficient injectionlocking ring oscillator (ILRO) to replace the LC oscillator which occupies much more area on chip with higher power consumption. In addition, through the ILRO, the frequency modulated input signal is converted to a full swing rectangular signal, which can be directly demodulated by a chain of down-conversion passive mixers, lowpass filters and a comparator. Power efficiency and simplicity of the proposed structure eliminate conventional FSK demodulator based on power-hungry phase locked...
A new low power 2-2 cascaded Sigma-Delta modulator with the reduced number of op-amps for GSM transceiver applications
, Article 2003 10th IEEE International Conference on Electronics, Circuits and Systems, ICECS2003, Sharjah, 14 December 2003 through 17 December 2003 ; Volume 1 , 2003 , Pages 268-271 ; 0780381637 (ISBN); 9780780381636 (ISBN) ; Vahidfar, M. B ; Aslanzadeh, H ; Mehrmanesh, S ; Sharif University of Technology
2003
Abstract
A new single-bit cascaded 2-2 σ/δ (Sigma-Delta) modulator with only two op-amps, instead of four ones in conventional modulators, to decrease the static power consumption and area, is designed for GSM transceiver applications. The circuit consists of two new single op-amp, second-order, and low-pass loop filters to achieve a fourth-order quantization noise shaping. The modulator shows 84dB DR (Dynamic Range) for GSM signal bandwidth, while consuming 2.3mW from a 2.5V supply voltage. © 2003 IEEE
On application of high-order compact finite-difference schemes to compressible vorticity confinement method
, Article Aerospace Science and Technology ; Volume 46 , October–November , 2015 , Pages 398-411 ; 12709638 (ISSN) ; Hejranfar, K ; Ebrahimi, M ; Sharif University of Technology
Elsevier Masson SAS
2015
Abstract
The main goal of this study is to assess the application of high-order compact finite-difference schemes for the solution of the Euler equations in conjunction with the compressible vorticity confinement method on both uniform Cartesian and curvilinear grids. Here, the spatial discretization of the governing equations is performed by the fourth-order compact finite-difference scheme and the temporal term is discretized by the fourth-order Runge-Kutta method. To stabilize the numerical solution, appropriate dissipation terms are applied and a detail assessment is performed to study the effects of the values of confinement and dissipation coefficients on the solution to reasonably preserve the...
A tunable-Q 4-path bandpass filter with Gm-C second-order baseband impedances
, Article 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 244-248 ; 9781509059638 (ISBN) ; Babamir, S. M ; Behmanesh, B ; Atarodi, S. M ; Sharif University of Technology
Abstract
An active switched-capacitor 4-path bandpass filter suitable for multi-standard applications in ultra-high frequency (UHF) band with different channel bandwidths is designed and simulated in 0.18 μm CMOS technology. The baseband impedance of the filter is implemented as a second-order Gm-C low-pass filter which can be used to tune the channel bandwidth as well as the quality factor (Q) of the RF filter. The center frequency of the filter can be tuned from 100 MHz up to 1.5 GHz by changing the clock frequency applied to the filter while its bandwidth can be tuned by tuning impedance parameters in any center frequency. To do so, the baseband impedance utilizes a frequency dependent negative...
Inserting the effects of ion channels in mean field models: Application to generation of anesthetic slow waves
, Article EUROCON 2005 - The International Conference on Computer as a Tool, Belgrade, 21 November 2005 through 24 November 2005 ; Volume I , 2005 , Pages 378-381 ; 142440049X (ISBN); 9781424400492 (ISBN) ; Senhadji, L ; Shamsollahi, M. B ; Sharif University of Technology
2005
Abstract
In this paper, effects of general anesthesia on the electroencephalogram (EEC) has been modeled with an enhanced physiological mean field theory of electrocortical activity. Enhancement is done by inserting two intrinsic ion channels (IKNa and IAR) in Liley's mean field model. In addition to excitatory and inhibitory synapses, intrinsic ion channels can generate or manipulate the brain rhythms. IKNa and IAR can produce slow brain rhythms (delta band frequency) in deep levels of anesthesia. We represent the activities of each mentioned ion channels by cascading a nonlinear function and a first order low pass filter. Linearized and numerical solutions of the modified model show that the power...
Effect of actuation frequency on the performance of diffuser micropumps
, Article 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006, Limerick, 19 June 2006 through 21 June 2006 ; Volume 2006 B , 2006 , Pages 725-731 ; 0791847608 (ISBN); 9780791847602 (ISBN) ; Ahmadian, M. T ; Sharif University of Technology
2006
Abstract
Valveless piezoelectric micropumps are in wide practical use due to their ability to conduct particles with absence of interior moving mechanical parts. The objective of this paper is to obtain the fluid flow response to actuation frequency of a passive diffuser valve under harmonic pressures. In this regards a 2D model of a micropump valves and chambers is analyzed. The analysis is performed for 10Kpa back pressure on micropump chamber and actuation frequencies within the range of 1 Hz to 10 KHz. Results show the highest velocity in the direction of diffuser axis occurs at the narrow diffuser neck while flow direction reverses every half period. For low frequencies, a parabolic velocity...
A high-order compact finite-difference lattice Boltzmann method for simulation of steady and unsteady incompressible flows
, Article International Journal for Numerical Methods in Fluids ; Vol. 75, Issue. 10 , 2014 , Pages 713-746 ; ISSN: 02712091 ; Ezzatneshan, E ; Sharif University of Technology
Abstract
A high-order compact finite-difference lattice Boltzmann method (CFDLBM) is proposed and applied to accurately compute steady and unsteady incompressible flows. Herein, the spatial derivatives in the lattice Boltzmann equation are discretized by using the fourth-order compact FD scheme, and the temporal term is discretized with the fourth-order Runge-Kutta scheme to provide an accurate and efficient incompressible flow solver. A high-order spectral-type low-pass compact filter is used to stabilize the numerical solution. An iterative initialization procedure is presented and applied to generate consistent initial conditions for the simulation of unsteady flows. A sensitivity study is also...
Simulation of two-phase liquid-vapor flows using a high-order compact finite-difference lattice Boltzmann method
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 92, Issue 5 , November , 2015 ; 15393755 (ISSN) ; Ezzatneshan, E ; Sharif University of Technology
American Physical Society
2015
Abstract
A high-order compact finite-difference lattice Boltzmann method (CFDLBM) is extended and applied to accurately simulate two-phase liquid-vapor flows with high density ratios. Herein, the He-Shan-Doolen-type lattice Boltzmann multiphase model is used and the spatial derivatives in the resulting equations are discretized by using the fourth-order compact finite-difference scheme and the temporal term is discretized with the fourth-order Runge-Kutta scheme to provide an accurate and efficient two-phase flow solver. A high-order spectral-type low-pass compact nonlinear filter is used to regularize the numerical solution and remove spurious waves generated by flow nonlinearities in smooth regions...
Watermarking based on independent component analysis in spatial domain
, Article Proceedings - 2011 UKSim 13th International Conference on Modelling and Simulation, UKSim 2011, 30 March 2011 through 1 April 2011, Cambridge ; 2011 , Pages 299-303 ; 9780769543765 (ISBN) ; Rahmati, A ; Babaie Zadeh, M ; Sharif University of Technology
2011
Abstract
This paper proposes an image watermarking scheme for copyright protection based on Independent Component Analysis (ICA). In the suggested scheme, embedding is carried out in cumulative form in spatial domain and ICA is used for watermark extraction. For extraction there is no need to access the original image or the watermark, and extraction is carried out only with two watermarked images. Experimental results show that the new method has better quality than famous methods [1], [2], [3] in spatial or frequency domain and is robust against various attacks. Noise addition, resizing, low pass filtering, multiple marks, gray-scale reduction, rotation, JPEG compression, and cropping are some...
Robust image watermarking using independent component analysis
, Article Proceedings - 3rd International Symposium on Information Processing, ISIP 2010, 12 November 2010 through 14 November 2010, Qingdao ; 2010 , Pages 363-367 ; 9780769542614 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
2010
Abstract
This paper proposes an image watermarking scheme for copyright protection based on Independent Component Analysis (ICA). In the suggested scheme, we divide the original image into blocks and use the ICA to project the image into a basis with its components as statistically independent as possible. The data embedding is carried out in cumulative form in the ICA basis and also the ICA is used for watermark extraction. The extraction process could be either non-blind, through a straightforward procedure, or blind, via a tricky method we propose. Experimental results show that the new method outperforms some well-known image watermarking methods [1], [2], [3] in spatial or frequency domain and...
TCP retransmission timer adjustment mechanism using system identification
, Article Proceedings of the 2004 American Control Conference (AAC), Boston, MA, 30 June 2004 through 2 July 2004 ; Volume 3 , 2004 , Pages 2328-2332 ; 07431619 (ISSN); 0780383354 (ISBN) ; Rad, A. H. M ; American Automatic Control Council; International Federation of Automation Control, IFAC ; Sharif University of Technology
2004
Abstract
In this paper, the TCP retransmission timer adjustment mechanism is approached from the system's theoretic point of view. TCP uses a simple recursive system identification algorithm to capture both time variant and time invariant Internet behavior and provides a dynamic Round-Trip Time (RTT) predictor. Based on real Internet data collection, it is observed that when the retransmission timer is adjusted by using the proposed predictor instead of the traditional RTT estimator, its performance increases significantly
An ant-based rate allocation algorithm for media streaming in peer to peer networks: Extension to multiple sessions and dynamic networks
, Article Journal of Network and Computer Applications ; Volume 34, Issue 1 , 2011 , Pages 327-340 ; 10848045 (ISSN) ; Salavati, A. H ; Pakravan, M. R ; Sharif University of Technology
Abstract
In this paper, we introduce a novel algorithm for rate allocation in media streaming P2P networks where multimedia contents are distributed among network members and streamed toward any requesting peer. The proposed algorithm is based on ant-colony optimization. It is capable of handling network dynamism, which is an inherent property of unstructured P2P networks. Another advantage of our algorithm is its ability to get over uncertainties in network state information, particularly the rate of supplying peers that could happen due to lack of accurate measurements. In addition, the suggested method does not rely on any information about the topology of the network. We have investigated both...
A compact mixer and DAC for implementation of a direct conversion OQPSK transmitter
, Article 2007 IEEE Region 10 Conference, TENCON 2007, Taipei, 30 October 2007 through 2 November 2007 ; 2007 ; 1424412722 (ISBN); 9781424412723 (ISBN) ; Mehrmanesh, S ; Zamanlooy, B ; Atarodi, M ; Sharif University of Technology
2007
Abstract
A compact low power circuit for implementation of a direct conversion OQPSK modulator is proposed. The circuit consists of a digital to analog converter, a low pass filter and an up-converter mixer. By embedding these three blocks, the circuit performance is enhanced and the total power consumption is reduced. The mixer is designed base on a Gilbert cell with on chip inductor loads. Instead of transconductance transistors of Gilbert cell, a fully deferential current mode DAC is used and proficiently a low pass filter is embedded between them and therefore the linearity of total system is improved. All of circuits are designed based on 0.18 μm CMOS technology with a single 1.8 volt power...
Experimental and analytical model analysis of Babolsar's steel arch bridge
, Article 3rd International Conference on Bridge Maintenance, Safety and Management - Bridge Maintenance, Safety, Management, Life-Cycle Performance and Cost, Porto, 16 July 2006 through 19 July 2006 ; 2006 , Pages 235-237 ; 0415403154 (ISBN); 9780415403153 (ISBN) ; Kazemi, M. T ; Lark, B ; Tabrizian, Z ; Sharif University of Technology
Taylor and Francis/ Balkema
2006
Abstract
The paper presents the experimental and analytical model analysis of a steel-girder arch bridge. The field test is carried out by ambient vibration testing under traffic excitations. Both the peak picking method in the frequency domain and the stochastic subspace identification method in the time domain are used for the output-only model identification. A good agreement in identified frequencies has been found between the two methods. It is further demonstrated that the stochastic subspace method provides better mode shapes. The three-dimensional finite element models are constructed and an analytical model analysis is then performed to generate natural frequencies and mode shapes in the...