Search for: correlation-coefficients
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    Prediction of reaction force on external indenter in cell injection experiment using support vector machine technique

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 2 , 2012 , Pages 537-543 ; 9780791845189 (ISBN) Abbasi, A. A ; Ahmadian, M. T ; Sharif University of Technology
    Evaluation of the reaction force on a tool which is used for exertion of force on biomaterials such as biological cells or soft tissues has applications in virtual reality based medical simulators or haptic tools. In this study, two least square based support vector machine (SVM) models have been constructed to predict the indentation or reaction force on mouse oocyte and embryo cells in cell injection experiment. Inputs of these two models are geometrical parameters of indented cell, namely dimple radius (a), dimple depth (w) and radius of the semicircular curve (R). Experimental data for calibration and prediction of the models have been captured from literatures. The performance of the... 

    Effect of deep breath on the correlation between the wrist and finger photoplethysmograms

    , Article 2012 19th Iranian Conference of Biomedical Engineering, ICBME 2012 ; 2012 , Pages 135-138 ; 9781467331302 (ISBN) Keikhosravi, A ; Zahedi, E ; Sharif University of Technology
    In this paper, a special probe is designed using an array of photodiodes and a 960 nm LED for recording the wrist photoplethysmogram (PPG). The design is based on Monte-Carlo simulation of light propagation in tissues. Two series of experiments were carried-out: normal breathing and deep breathing. In both experiments, finger and wrist PPG were simultaneously recorded from the index finger. In the first series of experiment, signals from 9 subjects were recorded and the correlation coefficient for the raw signals (AC+DC), the AC and DC components of wrist and finger PPG were (62.5% ± 12.1%), (91.2% ± 6.9%) and (61% ± 13.4%) respectively. In the second series of experiment (deep breathing),... 

    Single fault reliability analysis in FPGA implemented circuits

    , Article Proceedings - International Symposium on Quality Electronic Design, ISQED, 19 March 2012 through 21 March 2012 ; March , 2012 , Pages 49-56 ; 19483287 (ISSN) ; 9781467310369 (ISBN) Jahanirad, H ; Mohammadi, K ; Attarsharghi, P ; Sharif University of Technology
    Reliability analysis in FPGA implementation of logic circuits is an important issue in designing fault tolerant systems for faulty environments. In this paper an analytical method is developed for analyzing such systems. This method is based on signal probability propagation of faults from the location of appearance to final outputs of circuit. Single fault model is used for the faults occurred in routes and LUTs. In addition reconvergent fan-outs are handled using 16 correlation coefficients propagation approach. Experimental results show a good agreement between this method and Monte Carlo method for reliability analysis of MCNC benchmarks  

    Multivariate variability monitoring using EWMA control charts based on squared deviation of observations from target

    , Article Quality and Reliability Engineering International ; Volume 27, Issue 8 , 2011 , Pages 1069-1086 ; 07488017 (ISSN) Memar, A. O ; Niaki, S. T. A ; Sharif University of Technology
    Recent research works have shown that control statistics based on squared deviation of observations from target have the ability to monitor variability in both univariate and multivariate processes. In the current research, the properties of the control statistic S t that has been proposed by Huwang et al. (J. Quality Technology 2007; 39:258-278) are first reviewed and three new S t-based multivariate schemes are then presented. Extensive simulation experiments are performed to compare the performances of the proposed schemes with those of the multivariate exponentially weighted mean squared deviation (MEWMS) and the L 1-norm distance of the MEWMS deviation from its expected value (MEWMSL 1)... 

    Structural image representation for image registration

    , Article 2015 International Symposium on Artificial Intelligence and Signal Processing, AISP 2015, 3 March 2015 through 5 March 2015 ; March , 2015 , Pages 95-100 ; 9781479988174 (ISBN) Aghajani, K ; Shirpour, M ; Manzuri, M. T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Image registration is an important task in medical image processing. Assuming spatially stationary intensity relation among images, conventional area based algorithms such as CC (Correlation Coefficients) and MI (Mutual Information), show weaker results alongside spatially varying intensity distortion. In this research, a structural representation of images is introduced. It allows us to use simpler similarity metrics in multimodal images which are also robust against the mentioned distortion field. The efficiency of this presentation in non-rigid image registration in the presence of spatial varying distortion field is examined. Experimental results on synthetic and real-world data sets... 

    Design and evaluation of a novel triaxial isometric trunk muscle strength measurement system

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 223, Issue 6 , 2015 , Pages 755-766 ; 09544119 (ISSN) Azghani, M. R ; Farahmand, F ; Meghdari, A ; Vossoughi, G ; Parnianpour, M ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Maximal strength measurements of the trunk have been used to evaluate the maximum functional capacity of muscles and the potential mechanical overload or overuse of the lumbar spine tissues in order to estimate the risk of developing musculoskeletal injuries. A new triaxial isometric trunk strength measurement system was designed and developed in the present study, and its reliability and performance was investigated. The system consisted of three main revolute joints, equipped with torque sensors, which intersect at L5 - S1 and adjustment facilities to fit the body anthropometry and to accommodate both symmetric and asymmetric postures in both seated and standing positions. The dynamics of... 

    Membrane interactions control residue fluctuations of outer membrane porins

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 81, Issue 5 , May , 2010 ; 15393755 (ISSN) Besya, A. B ; Mobasheri, H ; Ejtehadi, M. R ; Sharif University of Technology
    Bacterial outer membrane porins (Omp) that have robust β -barrel structures, show potential applications for nanomedicine devices in synthetic membranes and single molecule detection biosensors. Here, we explore the conformational dynamics of a set of 22 outer membrane porins, classified into five major groups: general porins, specific porins, transport Omps, poreless Omps and composed pores. Normal mode analysis, based on mechanical vibration theory and elastic network model, is performed to study the fluctuations of residues of aforementioned porins around their equilibrium positions. We find that a simple modification in this model considering weak interaction between protein and... 

    A distortion outer bound for communicating correlated gaussian sources over a gaussian MAC

    , Article IEEE Communications Letters ; Volume 21, Issue 7 , 2017 , Pages 1457-1460 ; 10897798 (ISSN) Setayesh, M ; Behroozi, H ; Khalaj, B. H ; Sharif University of Technology
    In this letter, we consider two problems of sending a bivariate Gaussian source through a two-user Gaussian non-orthogonal multiple-access channel. We provide a new distortion outer bound for the considered joint source-channel coding problems, which significantly reduces the gap between inner and outer bounds of the distortion for correlation coefficients below a threshold. Furthermore, numerical results show, that under some conditions, our proposed outer bound matches with the inner bound obtained via the separate source-channel coding scheme, which proves the optimality of this scheme. © 1997-2012 IEEE  

    Correlation between trunk-pelvis inter-segmental coordination parameters during walking and disability level in chronic low back pain patients

    , Article Journal of Biomedical Physics and Engineering ; Volume 8, Issue 2 , 2018 , Pages 193-202 ; 22517200 (ISSN) Ebrahimi, S ; Kamali, F ; Razeghi, M ; Haghpanah, A ; Sharif University of Technology
    Shiraz University of Medical Sciences  2018
    Background: Chronic low back pain (CLBP) disability has been particularly frustrating because its treatment has been a great therapeutic challenge. Disability has been suggested to depend on different factors that should be found and considered in the medical management. The inter-segmental coordination is often impaired in CLBP subjects; however, to the best of our knowledge, there is no evidence about the relationship between the existence of coordination problems and disability in CLBP patients. Objective: To evaluate the correlation between sagittal plane trunk-pelvis intersegmental coordination parameters during walking and disability level in CLBP patients. Methods: Kinematic data were... 

    Kinetic studies of Bisphenol A in aqueous solutions by enzymatic treatment

    , Article International Journal of Environmental Science and Technology ; Volume 16, Issue 2 , Febraury , 2018 , Pages 821–832 ; 17351472 (ISSN) Ghobadi Nejad, Z ; Borghei, S. M ; Yaghmaei, S ; Sharif University of Technology
    Center for Environmental and Energy Research and Studies  2018
    Bisphenol A (BPA), which is a major component in the production of various consumer products, is one of the most significant endocrine-disrupting chemicals. In this research, the biocatalytic elimination of Bisphenol A using laccase produced by Phanerochaete chrysosporium was examined and optimized. The response surface methodology was used to study the effect of independent variables such as pH, temperature, initial laccase activity, initial Bisphenol A concentration, and the interactive effects of each variable on the removal of Bisphenol A and residual enzyme activity. Based on response surface plots, the maximum Bisphenol A removal (93%) was detected at a pH value of 8, temperature 40... 

    Developing group contribution models for the estimation of Atmospheric Lifetime and Minimum Ignition Energy

    , Article Chemical Engineering Science ; Volume 226 , 2020 Eini, S ; Jhamb, S ; Sharifzadeh, M ; Rashtchian, D ; Kontogeorgis, G. M ; Sharif University of Technology
    Elsevier Ltd  2020
    The Atmospheric Lifetime (ALT) of a compound represents the potential for the atmospheric accumulation of chemicals. Chemicals with a long lifetime are more resistant to natural decomposition and remain in the environment for a longer period. Minimum Ignition Energy (MIE) is one of the most important properties when evaluating hazardous chemicals. Despite the significance of these environment and safety-related properties, currently, there are no group contribution (GC) models that enable their predictive modeling. The present research aims at filling this gap. To this end, experimental data were collected from literature and the GC model parameters were estimated using the weighted... 

    Blood pressure estimation using photoplethysmogram signal and its morphological features

    , Article IEEE Sensors Journal ; Volume 20, Issue 8 , 2020 , Pages 4300-4310 Hasanzadeh, N ; Ahmadi, M. M ; Mohammadzade, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    In this paper, we present a machine learning model to estimate the blood pressure (BP) of a person using only his photoplethysmogram (PPG) signal. We propose algorithms to better detect some critical points of the PPG signal, such as systolic and diastolic peaks, dicrotic notch and inflection point. These algorithms are applicable to different PPG signal morphologies and improve the precision of feature extraction. We show that the logarithm of dicrotic notch reflection index, the ratio of low-to high-frequency components of heart rate (HR) variability signal, and the product of HR multiplied by the modified Normalized Pulse Volume (mNPV) are the key features in accurately estimating the BP... 

    On the positive definiteness of polarity coincidence correlation coefficient matrix

    , Article IEEE Signal Processing Letters ; Volume 15 , January , 2008 , Pages 73-76 ; 10709908 (ISSN) Haddadi, F ; Nayebi, M. M ; Aref, M. R ; Sharif University of Technology
    Polarity coincidence correlator (PCC), when used to estimate the covariance matrix on an element-by-element basis, may not yield a positive semi-definite (PSD) estimate. Devlin et al. (Devlin, 1975) claimed that element-wise PCC is not guaranteed to be PSD in dimensions p > 3 for real signals. However, no justification or proof was available on this issue. In this letter, it is proved that for real signals with p ≤ 3 and for complex signals with p ≤ 2, a PSD estimate is guaranteed. Counterexamples are presented for higher dimensions which yield invalid covariance estimates. © 2007 IEEE  

    Artificial neural network modeling of mechanical alloying process for synthesizing of metal matrix nanocomposite powders

    , Article Materials Science and Engineering A ; Volume 466, Issue 1-2 , 2007 , Pages 274-283 ; 09215093 (ISSN) Dashtbayazi, M. R ; Shokuhfar, A ; Simchi, A ; Sharif University of Technology
    An artificial neural network model was developed for modeling of the effects of mechanical alloying parameters including milling time, milling speed and ball to powder weight ratio on the characteristics of Al-8 vol%SiC nanocomposite powders. The crystallite size and lattice strain of the aluminum matrix were considered for modeling. This nanostructured nanocomposite powder was synthesized by utilizing planetary high energy ball mill and the required data for training were collected from the experimental results. The characteristics of the particles were determined by X-ray diffraction, scanning and transmission electron microscopy. Two types of neural network architecture, i.e. multi-layer... 

    Is there a reliable and invariant set of muscle synergy during isometric biaxial trunk exertion in the sagittal and transverse planes by healthy subjects?

    , Article Journal of Biomechanics ; Volume 48, Issue 12 , Sep , 2015 , Pages 3234-3241 ; 00219290 (ISSN) Sedaghat Nejad, E ; Mousavi, S. J ; Hadizadeh, M ; Narimani, R ; Khalaf, K ; Campbell Kyureghyan, N ; Parnianpour, M ; Sharif University of Technology
    Elsevier Ltd  2015
    It has been suggested that the central nervous system simplifies muscle control through basic units, called synergies. In this study, we have developed a novel target-matching protocol and used non-negative matrix factorization (NMF) technique to extract trunk muscle synergies and corresponding torque synergies. Isometric torque data at the L5/S1 level and electromyographic patterns of twelve abdominal and back muscles from twelve healthy participants (five females) were simultaneously recorded. Each participant performed a total number of 24 isometric target-matching tasks using 12 different angular directions and 2 levels of uniaxial and biaxial exertions. Within- and between-subject... 

    Test-retest reliability of postural stability measures during quiet standing in patients with a history of nonspecific low back pain

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 22, Issue 3 , 2010 , Pages 255-262 ; 10162372 (ISSN) Mazaheri, M ; Salavati, M ; Negahban, H ; Parnianpour, M ; Sharif University of Technology
    As balance is the foundation for all voluntary motor skills, considerable research has been conducted to evaluate postural control in patients with low back pain (LBP). Although reliability is a population-specific property, to the authors' knowledge, there has been no study to determine the test-retest reliability of the center of pressure (COP) measures in the general population of LBP patients. As many as 11 patients with a history of nonspecific LBP randomly completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed) in two sessions. The COP data were used to calculate standard deviation of amplitude,... 

    Test-retest reliability of Kinect's measurements for the evaluation of upper body recovery of stroke patients

    , Article BioMedical Engineering Online ; Volume 14, Issue 1 , 2015 ; 1475925X (ISSN) Mobini, A ; Behzadipour, S ; Saadat, M ; Sharif University of Technology
    BioMed Central Ltd  2015
    Background: Performance indices provide quantitative measures for the quality of motion, and therefore, assist in analyzing and monitoring patients' progress. Measurement of performance indices requires costly devices, such as motion capture systems. Recent developments of sensors for game controllers, such as Microsoft Kinect, have motivated many researchers to develop affordable systems for performance measurement applicable to home and clinical care. In this work, the capability of Kinect in finding motion performance indices was assessed by analyzing intra-session and inter-session test-retest reliability. Method: Eighteen stroke patients and twelve healthy subjects participated in this... 

    A new deep convolutional neural network design with efficient learning capability: Application to CT image synthesis from MRI

    , Article Medical Physics ; Volume 47, Issue 10 , 2020 , Pages 5158-5171 Bahrami, A ; Karimian, A ; Fatemizadeh, E ; Arabi, H ; Zaidi, H ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    Purpose: Despite the proven utility of multiparametric magnetic resonance imaging (MRI) in radiation therapy, MRI-guided radiation treatment planning is limited by the fact that MRI does not directly provide the electron density map required for absorbed dose calculation. In this work, a new deep convolutional neural network model with efficient learning capability, suitable for applications where the number of training subjects is limited, is proposed to generate accurate synthetic computed tomography (sCT) images from MRI. Methods: This efficient convolutional neural network (eCNN) is built upon a combination of the SegNet architecture (a 13-layer encoder-decoder structure similar to the... 

    The estimation of formation permeability in a carbonate reservoir using an artificial neural network

    , Article Petroleum Science and Technology ; Vol. 30, issue. 10 , Apr , 2010 , p. 1021-1030 ; ISSN: 10916466 Yeganeh, M ; Masihi, M ; Fatholah,i S ; Sharif University of Technology
    Reservoir permeability is an important parameter that its reliable prediction is necessary for reservoir performance assessment and management. Although many empirical formulas are derived regarding permeability and porosity in sandstone reservoirs, these correlations cannot be accurately depicted in carbonate reservoir for the wells that are not cored and for which there are no welltest data. Therefore, having a framework for estimation of these parameters in reservoirs with neither coring samples nor welltest data is crucial. Rock properties are characterized by using different well logs. However, there is no specific petrophysical log for estimating rock permeability; thus, new methods... 

    Prediction of natural gas flow through chokes using support vector machine algorithm

    , Article Journal of Natural Gas Science and Engineering ; Vol. 18, issue , 2014 , pp. 155-163 ; ISSN: 18755100 Nejatian, I ; Kanani, M ; Arabloo, M ; Bahadori, A ; Zendehboudi, S ; Sharif University of Technology
    In oil and gas fields, it is a common practice to flow liquid and gas mixtures through choke valves. In general, different types of primary valves are employed to control pressure and flow rate when the producing well directs the natural gas to the processing equipment. In this case, the valve normally is affected by elevated levels of flow (or velocity) as well as solid materials suspended in the gas phase (e.g., fine sand and other debris). Both surface and subsurface chokes may be installed to regulate flow rates and to protect the porous medium and surface facilities from unusual pressure instabilities.In this study a reliable, novel, computer based predictive model using Least-Squares...