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Lower extremity kinematic coupling during single and double leg landing and gait in female junior athletes with dynamic knee valgus
, Article BMC Sports Science, Medicine and Rehabilitation ; Volume 13, Issue 1 , 2021 ; 20521847 (ISSN) ; Sheikhhoseini, R ; Jafarian, M ; Esmaeili, A ; Sharif University of Technology
BioMed Central Ltd
2021
Abstract
Background: Dynamic knee valgus (DKV) is a common lower extremity movement disorder among females. This study aimed to investigate kinematic couplings between lower extremity joints in female junior athletes with DKV during single and double-leg landing and gait. Methods: Twenty-six physically active female junior athletes (10–14 years old) with DKV were recruited. Kinematic couplings between rearfoot, tibia, knee, and hip were extracted using eight Vicon motion capture cameras and two force plates. Zero-lag cross-correlation coefficient and vector coding were used to calculate kinematic couplings between joints during physical tasks. Paired t-test and Wilcoxon tests were run to find...
Analysis of Well log Data Using Detrended Fluctuation Analysis and its Comparison with Other Methods (Multifractal Analysis of Well Log Data)
, M.Sc. Thesis Sharif University of Technology ; Sahimi, Mohammad (Supervisor) ; Massihi, Mohsen (Supervisor) ; Jafari, Gholam Reza (Supervisor)
Abstract
One of the main challenges in characterization and simulation of larg scale porous media is spatial heterogeneity and variability of porous media properties such as porosity, density, and lithology at different scales. These information can be achieved at different scale from coring, well logging or seismic data. Well logs are an efficient way to obtain rock and fluid properties of geological patterns specially water resources and hydrocarbon reservoirs. One of the characteristics of geophysical well logs is their complex behavior which seems to imply a multifractal nature.In this study we investigate multifractality and presence of long range correlations in petrophysical well log data such...
Spectral classification and multiplicative partitioning of constant-weight sequences based on circulant matrix representation of optical orthogonal codes [electronic resource]
, Article IEEE Transactions on Information Theory ; 2010 vol. 56, no. 9 ; Salehi, Jawad A ; $item.subfieldsMap.a ; Sharif University Of TechnologyLevels of complexity in turbulent time series for weakly and high Reynolds number
, Article Physica A: Statistical Mechanics and its Applications ; Volume 391, Issue 11 , 2012 , Pages 3151-3158 ; 03784371 (ISSN) ; Sharif University of Technology
2012
Abstract
We use the detrended fluctuation analysis (DFA), the detrended cross correlation analysis (DCCA) and the magnitude and sign decomposition analysis to study the fluctuations in the turbulent time series and to probe long-term nonlinear levels of complexity in weakly and high turbulent flow. The DFA analysis indicate that there is a time scaling region in the fluctuation function, segregating regimes with different scaling exponents. We discuss that this time scaling region is related to inertial range in turbulent flows. The DCCA exponent implies the presence of power-law cross correlations. In addition, we conclude its multifractality for high Reynold's number in inertial range. Further, we...
Investigating the impact of correlated white noises on the bistability behavior in an optical three-level bistable system
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 32, Issue 1 , 2015 , Pages 76-82 ; 07403224 (ISSN) ; Sadighi Bonabi, R ; Sharif University of Technology
Abstract
The effect of correlated white noises on the optical bistability behavior of three-level atomic systems is theoretically investigated. Noise-induced bistability is demonstrated in an atomic optical bistable system consisting of three-level atoms in Ë-type configurations confined in an optical ring cavity. The output field as a result of enhanced Kerr nonlinearity induced by atomic coherence in the electromagnetically induced transparency system is variable due to the noises in laser parameters and the cooperativity parameter. Therefore, noise is mainly responsible for such induced bistability in the system. It is found that with the cross-correlation noises, the hysteresis loop of optical...
Spectral classification and multiplicative partitioning of constant-weight sequences based on circulant matrix representation of optical orthogonal codes
, Article IEEE Transactions on Information Theory ; Volume 56, Issue 9 , 2010 , Pages 4659-4667 ; 00189448 (ISSN) ; Salehi, J. A ; Sharif University of Technology
Abstract
Considering the space of constant-weight sequences as the reference set for every optical orthogonal code (OOC) design algorithm, we propose a classification method that preserves the correlation properties of sequences. First, we introduce the circulant matrix representation of optical orthogonal codes and, based on the spectrum of circulant matrices, we define the spectral classification of the set Sn,w of all (0, 1)-sequences with length n, weight w, and the first chip 1. Then, as a method for spectrally classifying the set Sn,w, we discuss an algebraic structure called multiplicative group action. Using the above multiplicative group action, we define an equivalence relation on Sn,w in...
Code family for modified spectral-amplitude-coding OCDMA systems and performance analysis
, Article Journal of Optical Communications and Networking ; Volume 2, Issue 6 , May , 2010 , Pages 344-354 ; 19430620 (ISSN) ; Jamshidi, K ; Sharif University of Technology
2010
Abstract
A novel family of codes for modified spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) is introduced. The proposed codes exist for more processing gains than the previously reported codes do. In the network using these codes, the number of users can be extended without any essential changes in the previous transmitters. In this study, we propose a construction method for these codes and compare their performance with previously reported codes
An efficient real-time voice activity detection algorithm using teager energy to energy ratio
, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 1420-1424 ; 9781728115085 (ISBN) ; Pakravan, M. R ; Razavi, M. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
We define a new feature called Teager Energy to Energy and mathematically show that it provides distinguished values for pure tone and white noise signals. We then employ the Teager Energy to Energy feature to propose an efficient procedure for voice activity detection and use simulation results to evaluate its performance in different noisy environments. Furthermore, we experimentally demonstrate the performance of the proposed voice activity detection technique in a real-time voice processing embedded system. Experimental and simulation results show that the introduced procedure provides more reliable results with a reasonable amount of computational complexity in comparison with its...
HAL-RD: Cross-correlating heterogeneous alerts and logs using resource dependencies
, Article 35th Annual ACM Symposium on Applied Computing, SAC 2020, 30 March 2020 through 3 April 2020 ; 2020 , Pages 1726-1735 ; Abadi, M ; Nowroozi, A ; ACM Special Interest Group on Applied Computing (SIGAPP) ; Sharif University of Technology
Association for Computing Machinery
2020
Abstract
Many organizations today use a variety of security and monitoring tools at various levels of defense. These tools often generate heterogeneous alerts and logs when an attack occurs. Because of the large volume and dispersion of these alerts and logs, the manual cross-correlation of them is a time-consuming and labor-intensive task. The main challenge is that heterogeneous alerts and logs generated as a result of an attack stage do not necessarily have common features, or there are no explicit relationships between them that can be used for cross-correlation. In this paper, we overcome this deficiency by presenting HAL-RD, a novel technique that uses resource dependencies to cross-correlate...
Phase Noise Measurement of Microwave Oscillator Using Interferometric Technique and Cross Correlation Method
, M.Sc. Thesis Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
In this thesis interferometric method is used in the frequency discriminator based on classic delay line technique for phase noise measurement of microwave oscillators at X-band. In this method no reference oscillator is needed for phase noise measurement. Beacause of carrier suppression, we can use low noise amplifier in linear regimeandthereforethe added noise to the phase detector, is reduced and the sensitivity of the system is improved consequently. Moreover cross correlation method isapplied to improve the sensitivity of classic delay line frequency discriminator technique. It has been shown that up to 15 dB improvement is achievable at far from carrier offsets.
Statistical analysis of sidelobes in random phase-modulated radars
, Article Proceedings of 2011 IEEE CIE International Conference on Radar, RADAR 2011, 24 October 2011 through 27 October 2011, Chengdu ; Volume 1 , October , 2011 , Pages 485-489 ; 9781424484416 (ISBN) ; Bahadori, M ; Tohidi, E ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
2011
Abstract
Target detection in noise radar is always done by computing cross-correlation between transmitted and received signals. In this process, side lobes of a strong target emerge and make some troubles in detection of weak ones (Masking Effect). Therefore, finding methods to suppress this effect becomes important. These methods can be implemented at the transmitter or receiver or at both to achieve more improvement. There are many new methods developed for the receiver side and a few methods applicable at the transmitter side. The main idea of suppressing side lobes at the transmitter is to design a specific noise signal instead of using purely random noise. In this paper we begin with...
EEG-based functional networks in schizophrenia
, Article Computers in Biology and Medicine ; Volume 41, Issue 12 , 2011 , Pages 1178-1186 ; 00104825 (ISSN) ; Knyazeva, M. G ; Sharif University of Technology
2011
Abstract
Schizophrenia is often considered as a dysconnection syndrome in which, abnormal interactions between large-scale functional brain networks result in cognitive and perceptual deficits. In this article we apply the graph theoretic measures to brain functional networks based on the resting EEGs of fourteen schizophrenic patients in comparison with those of fourteen matched control subjects. The networks were extracted from common-average-referenced EEG time-series through partial and unpartial cross-correlation methods. Unpartial correlation detects functional connectivity based on direct and/or indirect links, while partial correlation allows one to ignore indirect links. We quantified the...
Fuzzy based algorithm for acoustic source localization using array of microphones
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 2102-2105 ; 9781509059638 (ISBN) ; Bagheri Shouraki, S ; Iranmehr, E ; Sharif University of Technology
Abstract
This paper focuses on localizing acoustic source using fuzzy logic. For this purpose, an array of microphones are used as sensors. The Time Delay Estimation (TDE) is performed by correlation between received signals from each pair of microphones. In this paper, instead of assuming a crisp value as a TDOA, we introduce fuzzy number of TDOA in which the absolute value of the cross correlation function is normalized and then assumed as TDOA membership function for each pair of microphones. Truth value of presenting acoustic source is computed in region of interest based on achieved TDOA membership functions. Computing this truth value is represented in this paper based on fuzzy logic. The...
Performance analysis of asynchronous optical code division multiple access with spectral-amplitudecoding
, Article IET Communications ; Vol. 8, Issue. 6 , April , 2014 , pp. 956-963 ; ISSN: 17518628 ; Muller, R. R ; Marvasti, F ; Sharif University of Technology
Abstract
In this study, the performance of a spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) system in the asynchronous regime is evaluated using a Gaussian approximation of the decision variable for codes with fixed cross-correlation used in SAC-OCDMA systems. The authors consider the effect of phase-induced intensity noise (PIIN), thermal noise and shot noise. Moreover, the validity of the Gaussian approximation is confirmed by a Kolmogorov-Smirnov fitness test. For sake of comparison, the bit error rate (BER) of the asynchronous SAC-OCDMA system is also plotted numerically in comparison with the BER of the synchronous SAC-OCDMA. They show that a SAC-OCDMA system without...
Comparing receiver-based and transmitter-based techniques to decrease masking effect in noise radars
, Article International Radar Symposium, IRS 2011 - Proceedings, 7 September 2011 through 9 September 2011 ; September , 2011 , Pages 538-543 ; 9783927535282 (ISBN) ; Nayebi, M. M ; Sharif University of Technology
2011
Abstract
In noise radars, measuring the cross-correlation between transmitted and received signals is known as a common method of signal processing. However, it brings a lot of unwelcome sidelobes which can lean to masking weak echoes of far targets. There are many classical and modern methods of masking effect removal which are based on signal processing in the receiver side. A method of waveform design for decreasing this effect is presented and its efficiency is compared to purely random waveform generation method and CLEAN algorithm. Moreover, performance of collaborative using of receiver-based and transmitter-based techniques is considered
Suppressing sidelobe levels in random phase modulated radar
, Article IEEE National Radar Conference - Proceedings, 23 May 2011 through 27 May 2011 ; May , 2011 , Pages 530-532 ; 10975659 (ISSN) ; 9781424489022 (ISBN) ; Nayebi, M. M ; Sharif University of Technology
2011
Abstract
Signal processing in noise radar is always done by calculating the cross-correlation between transmitted and received signals. Strong echoes of near targets present relatively high sidelobes in the correlation output, so they can conceal weak echoes of weak targets (masking effect). Many classical and modern methods for alleviating this effect have been offered, however, most of them are based on signal processing in the receiver side. In this paper, a new method of waveform design, able to decrease masking effect, is presented. Contrary to the other methods, this method keeps the matched filter structure in receiver unchanged and does not need performing any extra process in the receiver...
Demythifying the belief in cryptocurrencies decentralized aspects. A study of cryptocurrencies time cross-correlations with common currencies, commodities and financial indices
, Article Physica A: Statistical Mechanics and its Applications ; Volume 556 , October , 2020 ; Jafari, G ; Rouhani, S ; Ausloos, M ; Sharif University of Technology
Elsevier B. V
2020
Abstract
The main question of this article is about whether cryptocurrencies, within their decentralization aspects, are a real commodity or/and a virtual currency. To resolve such a dilemma, we compare 7 cryptocurrencies with a sample of the three types of monetary systems: 28 fiat money, 2 commodities, 2 commodity based indices, and 3 financial market indices. We use the matrix correlation method. We display dendrograms and observe “hierarchy clustering”, as a function of data coarse graining. In fact, we confirm that the cryptocurrencies are not decentralized. We observe also that most of the currencies in the world are not significantly correlated or present a weak correlation with...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PLoS ONE ; Volume 16, Issue 1 January 2021 , 2021 ; 19326203 (ISSN) ; Dijujin, N. H ; Koohi, S ; Sharif University of Technology
Public Library of Science
2021
Abstract
In this study, optical technology is considered as SA issues’ solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PLoS ONE ; Volume 16, Issue 1 , 2021 ; 19326203 (ISSN) ; Dijujin, N. H ; Koohi, S ; Sharif University of Technology
Public Library of Science
2021
Abstract
In this study, optical technology is considered as SA issues’ solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Synchronizability of EEG-based functional networks in early alzheimer's disease
, Article IEEE Transactions on Neural Systems and Rehabilitation Engineering ; Volume 20, Issue 5 , 2012 , Pages 636-641 ; 15344320 (ISSN) ; Jalili, M ; Knyazeva, M. G ; Sharif University of Technology
IEEE
2012
Abstract
Recently graph theory and complex networks have been widely used as a mean to model functionality of the brain. Among different neuroimaging techniques available for constructing the brain functional networks, electroencephalography (EEG) with its high temporal resolution is a useful instrument of the analysis of functional interdependencies between different brain regions. Alzheimer's disease (AD) is a neurodegenerative disease, which leads to substantial cognitive decline, and eventually, dementia in aged people. To achieve a deeper insight into the behavior of functional cerebral networks in AD, here we study their synchronizability in 17 newly diagnosed AD patients compared to 17 healthy...