Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Rahele Mohammadi; Ali Mahloojifar
Volume 6, Issue 2 , June 2012, , Pages 141-152
Abstract
Self-paced BCI systems are more natural for real-life applications since these systems allow the user to control the system when desired. Detection of event periods in continuous EEG signal is one of the most important challenges in designing self-paced BCIs. In this paper, the Event related synchronization ...
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Self-paced BCI systems are more natural for real-life applications since these systems allow the user to control the system when desired. Detection of event periods in continuous EEG signal is one of the most important challenges in designing self-paced BCIs. In this paper, the Event related synchronization (ERS) is extracted from idle EEG signal using fractal dimensions in frequency range from 6 to 36 Hz and sparse representation based classifier. Our proposed method applied on EEG signal recorded during executing foot movement in 7 subjects. The average true positive rate and false positive rate equal to 90% and 5% were achieved.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Mohammad Hasan Moradi; Bahador Makki Abadi
Volume 2, Issue 2 , June 2008, , Pages 141-154
Abstract
Hish rate classification of Electromyogram (EMG) signals for controlling of prosthetic hands is still a hot topic among the rehabilitation research titles. Specially, when the degree of freedom in artificial hands increases, the classification rate decreases dramatically. In this paper, a new five layer ...
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Hish rate classification of Electromyogram (EMG) signals for controlling of prosthetic hands is still a hot topic among the rehabilitation research titles. Specially, when the degree of freedom in artificial hands increases, the classification rate decreases dramatically. In this paper, a new five layer classifier based on Neuro-Fuzzy-Genetic structure was introduced to increase the classification accuracy of EMG signals. The proposed classifier has a self- organized structure, which adaptively creates new rules according to the input features and trains the fuzzy rule weights based on the back propagation method. Finally, the genetic algorithm (GA) was employed for the final tuning stage. In this study, six subjects were asked to perform 9 different movements and their EMG signals were caught during the tasks from the six different forearm muscles. In order to remove the noises, the signals were filtered. Then the integral absolute average (IAV), Cepstrum coefficients and Wavelet Packet Coefficients with entropy pruning were extracted from the filtered signals as features. We used principal components analysis (PCA) for dimensionality reduction (234 to 10). The dimensionality reduction by PCA simplifies the structure of the classifier and reduces the processing time for the pattern recognition. The proposed classifier was applied on the features and the results were led to higher than 96.7% classification rate for the 9 classes of movement. To make a comparison, support vector machine (SVM) was employed (76% classification rate for 9 classes) and the results showed a drastic supremacy of the proposed method.
Nano-Biomaterials
Babak Farsadzadeh; Ali Asghar Behnamghader; Sedighe Joughedust
Volume 3, Issue 2 , June 2009, , Pages 151-160
Abstract
In this study hydroxyapatite (HA), flour-hydroxyapatite (FHA) and fluorapatite (FA) nanopowders synthesized by sol-gel route. Theses powders are used as biocompatible materials for bone replacement and teeth restoration. Ammonium fluoride (NH4F MERK), calcium nitrate [Ca(NO3)2,4H2O MERK] and triethyl ...
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In this study hydroxyapatite (HA), flour-hydroxyapatite (FHA) and fluorapatite (FA) nanopowders synthesized by sol-gel route. Theses powders are used as biocompatible materials for bone replacement and teeth restoration. Ammonium fluoride (NH4F MERK), calcium nitrate [Ca(NO3)2,4H2O MERK] and triethyl phosphite [TEP, (C2H5O) 3P MERK)] were used as F, Ca and P precursors respectively. Triethyl phosphite was first hydrolyzed in ethanol with a small amount of distilled water. To prepare FHA and FA, an appropriate amount of the NH4F powder was added directly to TEP solution. The appropriate amounts of TEP solution was added dropwise to the calcium nitrate solution to yield a stoichiometric ratio of Ca/P=1.67. The resulted solution stirred for 1 h and aged at 25°C for 24 h and 40°C for 72h afterward. After oven drying at 80°C, the powder samples were heat-treated at 550°C for 1 h in air. Microstructural characteristics, powder morphology, chemical structure and phase analysis and in vitro study were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), Zetasizer instrument and cell culture method. Fluoride-substituted hydroxyapatite powders (FHA) and Fluor apatite (FA) were successfully fabricated via a sol–gel technique with the incorporation of different levels of fluoride ions. Nearly complete substitution of the OH¯ by F¯ occurred with heat treatment, which was confirmed by FTIR analysis. The particle size distribution of powders evaluated by a zeta-sizer instrument was 100-160nm. The XRD results showed that the crystal size of powders is 20-50nm. The phase stability and crystallinity were different depending on the level of fluoride substitution. Moreover, the crystallinity and crystallite size of the powders increased with fluoride substitution. These improvements in the crystallization and phase stability of the apatite structure, resulting from the fluoride substitution via the sol– gel process, suggest enhanced performance of the FHA powders. The cellular response to the HA, FHA and FA powder was assessed by an in vitro culture method using fibroblastic L929 cells. After culturing for 3 days, the results showed that the number of cells increased with increasing fluoride substitution.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Nasrin Sho'ouri
Volume 14, Issue 2 , July 2020, , Pages 159-168
Abstract
Previous research has shown that eye movements in people with Attention Deficit Hyperactivity Disorder (ADHD) and healthy people were different, and it is possible that there is a difference between the two groups' EOG signals. Therefore, in the present study, the recorded EOG signals of 30 children ...
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Previous research has shown that eye movements in people with Attention Deficit Hyperactivity Disorder (ADHD) and healthy people were different, and it is possible that there is a difference between the two groups' EOG signals. Therefore, in the present study, the recorded EOG signals of 30 children with ADHD and 30 healthy children were examined during performing an attentional related task. For this purpose, the scaling exponents of the two groups' EOG signals were calculated and the differences between the two groups were examined using statistical tests. The EOG signals were then classified using a Growing Neural Gas network. The results show that the scaling exponents of the EOG signals in children with ADHD were significantly higher than that of healthy children (p < 0.001). This result shows that the decay slope of power spectrum in ADHD children is more as compared to healthy children. In addition, the EOG signals were classified into two groups with a detection accuracy of 72.22±2.8%. The results of this study could be used to design a course of treatment with EOG biofeedback to treat or reduce the symptoms of people with ADHD.
Spinal Biomechanics
Karim Leilnahari; Nasser Fatouraee; Mohammad Saleh Ganjavian
Volume 5, Issue 2 , June 2011, , Pages 161-170
Abstract
Ergonomic factors have a direct influence on the quality of spine support during sleep. Previous studies have shown that a mattress with a homogeneous stiffness can not necessarily maintain the natural spinal alignment. Using mattresses with components of different stiffness could be considered as a ...
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Ergonomic factors have a direct influence on the quality of spine support during sleep. Previous studies have shown that a mattress with a homogeneous stiffness can not necessarily maintain the natural spinal alignment. Using mattresses with components of different stiffness could be considered as a possible solution instead. In this research a new mattress system having elements with different stiffness has been designed. The springs used in this mattress has been combined with a special slice of polyurethane foam, and each of them has its own specific spring constant. After acquiring the anthropometrical data of 25 male volunteers, they were asked to lie in a lateral position on soft and very stiff surfaces according to predefined conditions. Then the coordinates of the markers mounted on their spinous processes were registered through the optical tracking methods. In the next step the arrangement of the foam-spring elements were changed for each subject several times, in order to spinal alignment in a frontal plane was close to his normal alignment corresponding to the upright position. The post-processing of acquired data was considered off line.In order to qualify our experiments the BRG.LifeMod was used to model body position when lying on a mattress. The anthropometrical data of 4 subjects were used for the dimensional indexes of model. Several numerical models were built with several surfaces corresponding to the experimental essays. Once again the spinal alignment extracted. Results of both experimental and numerical modeling showed that the mattress with custom-made arrangement of the elements is an appropriate solution for the optimal support of the spine during sleep. The numerical modeling was able to predict the spinal alignment. The results of this research can be very useful in designing the custom-made sleep systems according to the ergonomic factors.
Tissue Engineering
Jafar Ai; Saeed Sarkar; Mohammad Ali Oghabian
Volume 4, Issue 2 , June 2010, , Pages 161-166
Abstract
Various reviews have shown that strong electromagnetic fields have negative effects on human health. This study focused on the effect of MRI radiation on liver functional test histometery of liver in adult male rats. For this purpose, we used an MRI device that could produce 1.5 T electromagnetic radiations, ...
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Various reviews have shown that strong electromagnetic fields have negative effects on human health. This study focused on the effect of MRI radiation on liver functional test histometery of liver in adult male rats. For this purpose, we used an MRI device that could produce 1.5 T electromagnetic radiations, and chose 22 Wistar rats as laboratory animal models. Rats were divided into two equal groups. The first group exposed to 1.5T electromagnetic radiation and RF radiation during a 30- minute MRI scan as experimental group. The control group experienced 1.5T electromagnetic radiation exposure without RF radiation by the same MRI device. The rats were anesthetized and blood samples were obtained from cardiac chambers to measure the serum levels of LDL, HDL, ALT, AST, ALP, total cholesterol, total protein, albumin, total billirobin, and direct bilirobin. Livers were then removed and the specimens fixed. Serial sections (5 μm thick) were prepared from livers and the diameter of hepatocytes and their nuclei were measured. The findings of the present study indicate that, there was a significant increase (P<0.5) in amount of HDL, ALT, AST, ALP, total billirobin, direct bilirobin and there was a significant decrease (P<0.5) in amount of total cholesterol, LDL, total protein, and albumin in experimental group by comparison with control group. But no significant differences were seen in the diameter of hepatocytes and their nuclei between both groups. The electromagnetic radiations of MRI device may influence the level of liver enzymes and liver function without any histomorphologically changes. Conducting clinical trial studies with human subjects is recommended.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Amin Janghorbani; Mohammad Hasan Moradi; Abdollah Arasteh
Volume 7, Issue 2 , June 2013, , Pages 163-174
Abstract
Acute hypotension episodes (AHEs) are one of the hemodynamic instabilities with high mortality rate that is frequent among many groups of patients. Prognosis of acute hypotension episodes can help clinicians to diagnose the cause of this physiological disorder and select proper treatment based on this ...
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Acute hypotension episodes (AHEs) are one of the hemodynamic instabilities with high mortality rate that is frequent among many groups of patients. Prognosis of acute hypotension episodes can help clinicians to diagnose the cause of this physiological disorder and select proper treatment based on this diagnosis. In this study two groups of features, physiological and chaotic features, were extracted from the physiological time series to be applied for prediction of AHEs in the future 1 hour time interval. The best set of the features from the extracted features were selected using Genetic Algorithm (GA) and were classified by SVM. The prediction accuracy for physiological features was 87.5% and for chaotic features was 85%. In order to improve prediction accuracy, physiological and chaotic features were employed simultaneously in feature selection and the best combination of these features was selected by GA and classified by SVM. The best prognosis accuracy, which was achieved in this study by classification of the selected features, was 95% that was better than other previously studies on the same database.
Targeted Drug Delivery / Smart Drug Delivery / Drug Targeting
Fariba Ourang; Mohammad Rafienia
Volume -1, Issue 2 , June 2005, , Pages 173-179
Abstract
Polyurethane micro spheres have been synthesized by solvent evaporation technique with castor oil, Polycaprolacton (PCL), Hexamethylen diisocyanate (HMDI) and Ethyl diamine (ED) as carriers for controlled drug delivery systems. Release behavior of micro spheres has been investigated using Bromocresol ...
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Polyurethane micro spheres have been synthesized by solvent evaporation technique with castor oil, Polycaprolacton (PCL), Hexamethylen diisocyanate (HMDI) and Ethyl diamine (ED) as carriers for controlled drug delivery systems. Release behavior of micro spheres has been investigated using Bromocresol purple die. Fourier transmission infrared (FTIR), Scanning Electron Microscope (SEM), Optical microscope, dissolution instrument and UV spectrophotometer were used to investigate the polymerization process, surface morphology, particle size, rate of release and calibration curve respectively. Results showed that urethane bonds were formed at 3300-3400cm-1 and 1650-1700 cm-1. SEM micrographs showed surface irregularities as a result of solvent evaporation. Particle sizes were higher for castor oil/HMDI rather than PCL/HMDI microbe ads and in both cases, particle size and Bromocresol purple die release increased with rising NCO/OH ratio.
Fluid-Structure Interaction in Biological Media / FSI
Saeed Bahrami; Mahmood Norouzi
Volume 10, Issue 2 , August 2016, , Pages 175-186
Abstract
Increasing the cardiovascular disease had led to the researchers to investigate the blood flow more than before. In this article the effects of artery elasticity on hemodynamic parameters with concerning the interaction between blood and the vessel’s wall had been investigated. The wall shear stress ...
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Increasing the cardiovascular disease had led to the researchers to investigate the blood flow more than before. In this article the effects of artery elasticity on hemodynamic parameters with concerning the interaction between blood and the vessel’s wall had been investigated. The wall shear stress had changed with different times and cannot send the congestion of the vessels. From this point the oscillatory shear index had been said the shear stress without the time average. In this study a 3D model from the left coronary bifurcation with 4 models of wall had been investigated. The result from a pulsatile flow from a non-newtonian flow with the method of two ways coupling by using the method of arbitrary Lagrangian–Eulerian had been calculated. The observation had showed a 13 percent decreasing in the profile of velocities at the bifurcation place in that in the hyperelastic model had the highest subtraction. Also by increasing the toughness of the wall the velocity profile and oscillator shear stress were increased. The average shear stress in the model of rigid had showed the 28 percent difference in comparison with the hyperelastic model. By comparing the results with clinical data showed that, the places with average shear stress 1.10 pa and less than that with presenting the oscillatory shear index is more than 0.3 that can be a potential dangerous places in forming atherosclerosis oscillatory shear index plaque especially in the posterior after the bifurcation. Meanwhile in the hyperelastic model the results are more precise than the other models.
Biological Systems Modeling
Mohsen Kamelian Rad; Mohammad Ali Ahmadi Pajouh; Mehrdad Saviz
Volume 15, Issue 2 , August 2021, , Pages 175-186
Abstract
Transcutaneous electrical stimulation of peripheral nerve fibers has always been an important field of research. Many studies indicate the possibility to block the conduction of nerve fibers by using high frequency alternating currents (HFAC). According to the fact that the stimulation of narrower fibers ...
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Transcutaneous electrical stimulation of peripheral nerve fibers has always been an important field of research. Many studies indicate the possibility to block the conduction of nerve fibers by using high frequency alternating currents (HFAC). According to the fact that the stimulation of narrower fibers is always accompanied by activation of thicker fibers, in this study, current regions for selective stimulation of different nerve fibers without activating other fibers have been obtained. This success is achieved through the nerve conduction block using HFAC (5-20 KHz). Stimulation current regions is a part of the intensity-frequency diagram which by choosing the excitation parameters in this area, only some target fibers are stimulated according to their diameters. The McIntyre nerve fiber model was used to perform these simulations; The sodium-potassium pump model has also been added to it and its effects have been investigated. A unipolar electrode is considered which acts as a point current source at different distances from the nerve fibers, and selective excitation spaces are obtained for the Aδ and Aβ fibers. The appropriate frequency range for excitation of different fibers is 5 kHz and above, while the desired current for selective excitation of Aδ and Aβ fibers is given by two polynomial equations of order 2 and 3, respectively, which are fitted to the middle of selective parameter space of each nerve fiber. Also, the excitation current varies from about 0.8 to 1.8 mA for Aδ fibers and from about 0.55 to 0.95 mA for Aβ fibers. In all of the simulations mentioned in this article, the sinusoidal waveform is used.
Biomechanics / Biomechanical Engineering
Mahdi Bagheri Rouchi; Mehrdad Davoudi; Mohammad Parnianpour
Volume 13, Issue 2 , August 2019, , Pages 177-187
Abstract
According to the literature, changes in muscle activity patterns are considered as one of the causes of non-specific chronic low back pain. Recent studies have introduced muscle synergy as a valuable tool for analyzing how muscles work in body movements. In this way, a new study method is proposed for ...
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According to the literature, changes in muscle activity patterns are considered as one of the causes of non-specific chronic low back pain. Recent studies have introduced muscle synergy as a valuable tool for analyzing how muscles work in body movements. In this way, a new study method is proposed for modeling upper body and extracting time-varying muscle synergies in flexural motion of the waist. In this way, a new study method is proposed for modeling trunk and extracting time-varying muscle synergies in plane bending movements of lumbar flexion. Considering 18 effective muscles and function of the combined cost of the minimum jerk-energy, 24 different movements and their corresponding muscle patterns have been simulated. To evaluate the role of velocity, the pattern of muscle activity was divided into two parts: tonic, to overcome the gravity force, and phasic, proportional to the trunk movement velocity. In the following, three fast-reaching times of 0.75, 1, and 2 seconds were considered for each direction. The results showed that 77% of the lumbar muscle pattern of movement was achieved by four phasic synergies and four tonic synergies. The resulting synergies are quite influenced by the movement direction and velocity, so that each pair of phasic and tonic synergy is most effective in one of the main directions. On the other hand, the increase in velocity causes elevated amplitude coefficient and accelerated activation of phasic synergies compared to normal mode. Considering the 45° flexion combination with 30° left lateral bending, 77.2% of the muscle pattern of movement has been reconstructed using time-varying synergies. It can be argued that the use of muscle synergies expresses a good explanation for how muscles work in movement at different directions and velocities.
Biomedical Image Processing / Medical Image Processing
Sina Shamekhi; Mohammad Hossein Miranbaygi; Ali Gooya; Bahare Azarian
Volume 8, Issue 2 , June 2014, , Pages 183-202
Abstract
Two-dimensional gel electrophoresis (2DGE) is a basic and widely used method in proteomics. In this method, mixtures of proteins are separated due to the differences in their molecular weight and isoelectric points and a final image obtained from the separated protein spots is created. Due to the large ...
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Two-dimensional gel electrophoresis (2DGE) is a basic and widely used method in proteomics. In this method, mixtures of proteins are separated due to the differences in their molecular weight and isoelectric points and a final image obtained from the separated protein spots is created. Due to the large number of the protein spots in a 2DGE image and the importance of separation of overlapping proteins, the image processing of these images is a complex process. 2DGE images pose various noises and artifacts such as cracks, staining artifacts, and streaks that affect the reliability of the analysis. In this work, we have proposed a novel spots filter based on the scale-space second order structural Hessian and its eigenvalues for enhancing and separating the spots from the background. Furthermore, in this work, 2DGE images have been segmented and the locations of the spots have been detected. To evaluate and compare the proposed method, we have implemented three methods: Otsu thresholding, Watershed transform, and the method proposed by Mylona et al. Based on the regional spot volume evaluation, the TPR and FPR of the proposed method are 78.6 and 14.9, the TPR and FPR of the Otsu method are equal to 71.4 and 25.7 percent, and the TPR and FPR of the Watershed algorithm are 53.9 and 8.1 percent, respectively. Also, in the spot counts evaluation, the Precision and TPR of the proposed method are equal to 83.6 and 81.1 percent, and the Precision and TPR of Otsu method are 65.4 and 78.3, respectively. The Watershed transform has detected the spots with Precision and TPR equal to 27.7 and 68.2 percent, and the Precision and TPR of the method proposed by Mylona et al. are 74.0 and 72.7 percent, respectively. The results reveal the accuracy and superiority of the proposed method.
Smart Biomaterials
Fardin Nematzadeh; Abolfazl Majidi
Volume 16, Issue 2 , September 2022, , Pages 183-194
Abstract
Teeth, as one of the most important organs of the body, play an essential role in beauty and one of the best ways to treat its disorder and damage is the use of orthodontics. Smart wires are widely used in orthodontics for tidying teeth and for reasons such as superelastic behavior, corrosion resistance, ...
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Teeth, as one of the most important organs of the body, play an essential role in beauty and one of the best ways to treat its disorder and damage is the use of orthodontics. Smart wires are widely used in orthodontics for tidying teeth and for reasons such as superelastic behavior, corrosion resistance, high fatigue life, good compatibility and reversible strain. In this paper, the finite element method was used to investigate the mechanical behavior of smart orthodontic wires according to the standard by applying tensile force and considering their metallurgical properties. The macroscopic model for describing the properties of matter was based on Helmholtz thermodynamic free energy. The results showed that with a 10°C changes in clinical temperature from 26°C to 36°C, the upper and lower plateau stresses and the strain elastic energy decreased about 10% and 18.28% respectively. Also with 10°C change in clinical temperature from 36°C to 46°C, the upper and lower plateau stresses and the strain elastic energy increased approximately 18% and 47.26% respectively. In conclusion, the smart orthodontic wire due to the lower level of the difference between the upper and lower plateau stresses, less elastic strain energy, complete hysteresis loop dependent on superelastic behavior and high correlation of experimental and numerical results related to force-strain changes showed better performance. This numerical study can provide a method to study the mechanical behavior of smart orthodontic wires with respect to the effects of metallurgical and mechanical properties for the effectiveness of the length of treatment in the tooth.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Farin Kahroba; Maryam Mohebbi; Hamed Danandeh Hesar
Volume 11, Issue 2 , June 2017, , Pages 187-199
Abstract
Sudden cardiac death (SCD) is one of the most significant and common causes of heart related deaths around the world. It is believed that SCD can be predicted using signatures and features extracted from ECG signal. These signatures may be seen as arrhythmia or abnormalities in the ECG signal. In this ...
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Sudden cardiac death (SCD) is one of the most significant and common causes of heart related deaths around the world. It is believed that SCD can be predicted using signatures and features extracted from ECG signal. These signatures may be seen as arrhythmia or abnormalities in the ECG signal. In this paper, a monitoring index is introduced for early detection of SCD. This index is acquired by filtering the ECG signal using a nonlinear ECG dynamical model and extended Kalman filter (EKF). The nonlinear dynamical model was a modified version of polar ECG dynamical model proposed by Mc. Sharry et.al. In our algorithm, first the ECG dynamical model is extracted. Then an EKF is applied on the signal. Using the fidelity index extracted from the innovation signal yielded by EKF, a novel algorithm detects the SCD related arrhythmias and abnormalities. The proposed method was evaluated on Physionet Sudden Cardiac Death Holter database. Twenty records corresponding to patients having SCD and eighteen records corresponding to healthy patients were extracted from this database. The evaluation results showed that our proposed monitoring index correctly detected 17 SCDs out of 20 (85% accuracy).
Speech processing
Mansour Sheykhan
Volume 1, Issue 3 , June 2007, , Pages 227-240
Abstract
In the first version of our Farsi Text-To-Speech (TTS) system, a Recurrent Neural Network (RNN) was used to generate prosody parameters (pitch contour, duration, energy and pause), and a Harmonic + Noise Model (HNM) speech synthesizer was used to concatenate the single units of diphones. To improve the ...
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In the first version of our Farsi Text-To-Speech (TTS) system, a Recurrent Neural Network (RNN) was used to generate prosody parameters (pitch contour, duration, energy and pause), and a Harmonic + Noise Model (HNM) speech synthesizer was used to concatenate the single units of diphones. To improve the performance of TTS, in this paper, two modifications are presented. In the first one is a neural-statistical hybrid model in which RNN plays the role of prosody parameterizer and the combination of decision trees and Gaussian Mixture Models (GMMs) gives the probability distributions of targets and transitions in each context a equivalent cluster. Another modification is about developing a unit selection speech synthesizer in which syllable is selected as the basic synthesis unit and, due to the first modification, an effective unit selection strategy is also conducted. To evaluate the performance of the system, the rating scales presented in the recommendation P.85 of the International Telecommunication Union (ITU) were used and the Mean Opinion Score (MOS) over six scales was achieved as 3.6.
Vida Khalili; Jafar Khalil Allafi; Hosein Maleki Ghaleh
Volume 6, Issue 3 , June 2012, , Pages 231-238
Abstract
In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized ...
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In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized using triethylenamine as dispersant. Surface characteristics, adhesion strength, stability and bioactivity of the composite coating were subsequently studied. EDX examination of the composite coating surface revealed homogeneous dispersion of carbon nanotubes all over coating. Also, the bonding strength of composite coating was found to be about 24 MPa. Compared to NiTi sample coated with hydroxyapatite and coated with hydroxyapatite/carbon nanotubes, the bode and nyquist plots of NiTi samples with hydroxyapatite/carbon nanotubes composite coating suggested that the composite coating was chemically more stable and provided corrosion resistance for NiTi SMA. In-vitro bioactivity test in SBF showed that the presence of CNTs in HA/CNTs composite coating does not have negative effect on ability of apatite formation.
Biomechanics of Bone / Bone Biomechanics
Shahab Mansourbaghaei; Majid Haghayegh; Seyed Mohammad Rajaei
Volume 3, Issue 3 , June 2009, , Pages 243-253
Abstract
An analytical method to predict the response of the inclined impact of a fluid filled elastic spherical shell having an arbitrary thickness with an elastic toroid is investigated in this paper which can be a model for analytical evaluation of blunt impact on the human head. The study is performed under ...
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An analytical method to predict the response of the inclined impact of a fluid filled elastic spherical shell having an arbitrary thickness with an elastic toroid is investigated in this paper which can be a model for analytical evaluation of blunt impact on the human head. The study is performed under a combination of Hertzian contact theory and the local effect of membrane and bending of the shell in order to state the implicit equation to determine the transmitted force. With respect to the analytical responses, it is concluded that transmitted force decreases and contact duration increases by increasing of attack angle in constant initial velocity. In addition, closed form solution is presented to obtain impact parameters including the duration, the maximum transferred load and the maximum acceleration of the shell which particularly important for the researchers. Therefore investigation of the important quantities of the impact problem with closed form solution is possible. On the other hand, limiting cases will be discussed in next step and the concluded results are validated by finite element methods to verify the response of the model. In this step, a good agreement between analytical responses and numerical results is observed that reveals the correctness of analytical equations. In the final step of this research, obtained results are compared with experimental data.
Biomedical Image Processing / Medical Image Processing
Poune Roshani Tabrizi; Reza Aghaeizade Zoroofi
Volume 2, Issue 3 , June 2008, , Pages 247-266
Abstract
Drowsiness detection is vital in preventing traffic accidents. In this project, we propose three new algorithms for pupil and iris detection, lips localization and eyes state analysis, which we incorporate into a four step system for drowsiness detection: face detection, drowsiness parameters extraction ...
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Drowsiness detection is vital in preventing traffic accidents. In this project, we propose three new algorithms for pupil and iris detection, lips localization and eyes state analysis, which we incorporate into a four step system for drowsiness detection: face detection, drowsiness parameters extraction from eyes, drowsiness parameter extraction from mouth and drowsiness level determination. Many current efforts, which are based on face analysis, focus only on using a single visual cue to characterize driver's state of alertness. This approach that relies on a single visual cue may encounter difficulty when the required visual features cannot be acquired accurately or reliably. There are few systems that use several visual cues to characterize driver's state of alertness. These systems are based on IR illuminators or training data. IR illuminators can be hazardous to eye health. Thus, our proposed system determines drowsiness level using a combination of several visual cues and contextual information. Also, it requires no training data at any step or IR illuminators. We analyzed and compared different parts of the systems with other methods using IMM, HCE, CVL database and 30 video sequences in two drowsy and active states from 15 persons. Finally, we achieved excellent drowsiness level results from the study population. We determined drowsiness level as follows: 1. The eyes and mouth state (detecting whether they were open or closed) was analyzed as 94.3% and 95.1 %, respectively; 2. Drowsiness level was determined in different situations such as normal blinking, fast blinking, normal speaking, yawning and long eye closure and 3. The participants were given a warning message when the drowsiness level reached over the threshold of 0.95.
Mohammad Javad Abolhassani; Yousef Salimpour; Parisa Rangraz
Volume 4, Issue 3 , June 2010, , Pages 249-256
Abstract
An otoacoustic emission is a low-level acoustic signal which is generated in cochlea. It could be recorded with a sensitive probe in the outer ear canal. OAEs are considered to be related to the amplification function of the cochlea. Outer hair cells are the elements that enhance cochlear sensitivity ...
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An otoacoustic emission is a low-level acoustic signal which is generated in cochlea. It could be recorded with a sensitive probe in the outer ear canal. OAEs are considered to be related to the amplification function of the cochlea. Outer hair cells are the elements that enhance cochlear sensitivity and frequency selectivity and hence act as the energy sources for amplification. Otoacoustic emission is transmitted through oval window to the outer ear canal, the distortion effects of middle ear and outer ear on the recorded signal are inevitable. Currently all clinical applications of otoacoustic emission are based on distorted measurement. For estimating the original otoacoustic emission produced in cochlea the middle ear and the outer ear effects must be compensated. The computational model of the auditory periphery is used to design a compensation filter for the estimation of the otoacoustic emission right after production and before entering the middle ear. Using Middle ear reverse transfer function and primary input signal Fourier transforms, OAE estimation before middle ear was obtained. The results of comparison of the estimated signal with the recorded one indicate that, due to the noise reduction and increase in reproducibility as a main criteria in hearing screening, the assessment based on the estimated otoacoustic emission is closer to the real response of the auditory system.
Biological Computer Modeling / Biological Computer Simulation
Somayeh Raiesdana
Volume 12, Issue 3 , November 2018, , Pages 249-263
Abstract
Sleep is an essential process to maintain and improve human activities, while many details related to sleep are still not well understood. Decreased or fragmented sleep is a health risk that might result in heart disease or diabetes on one hand and degradation of consciousness and cognition on the other ...
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Sleep is an essential process to maintain and improve human activities, while many details related to sleep are still not well understood. Decreased or fragmented sleep is a health risk that might result in heart disease or diabetes on one hand and degradation of consciousness and cognition on the other hand. Sleep fragmentation is a phenomenon in which an individual's sleep is intermittently disrupted by arousal caused by external factors (noise) or internal factors (apnea) although sleep deprivation does not completely occur. Computational modeling is a suitable framework for understanding complex biological mechanisms. In this paper, the fundamental phenomena underlying the sleep-wake transition was reviewed and simulated. The dynamical behavior of model was then investigated and afterwards the factors that might cause obstructive sleep apnea were implemented and evaluated. The model includes two main neuronal populations: the ascending arousal system in the brain stem that is responsible for awakening and a neuronal population in the hypothalamus, called VLPO, which mediates sleep. These populations have mutual inhibition on each other causing a flip-flop or switching behavior between sleep and wake. The results of modeling in this paper showed hysteresis in the sleep-wake cycle, the size of which is affected by factors causing arousal. In OSA, intermittent and unstable transitions as well as the shrinking of bistable zone is expected. The model could reproduce some experimental results related to obstructive apneas.
Neuro-Muscular Engineering
Amir Hosein Eskandari; Ehsan Sedaghat Nejad; Seyed Javad Mousavi; Mohsen Asghari; Mohammad Parnianpour
Volume 5, Issue 3 , June 2011, , Pages 257-273
Abstract
Selection of muscle activation pattern to reach a specific goal by considering the complexities of neuromuscular system and the way it overcomes these complications, is of researchersinterest in motor control. One proposed solutionfor resolving thesecomplexities is the concept of simple module (synergies) ...
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Selection of muscle activation pattern to reach a specific goal by considering the complexities of neuromuscular system and the way it overcomes these complications, is of researchersinterest in motor control. One proposed solutionfor resolving thesecomplexities is the concept of simple module (synergies) that the combination of them leads to more complex activities. In the present work, the existence and arrangement of synergies in the lumbar spine are proved. For this purpose, a model with 18-muscles in level L4-L5 is utilized in the static condition. In order to obtaina muscular and stability synergies, muscle activation, which are obtained by exerting moments in 2D and 3D spaces and angular stiffness to the model,are used. The results show that six muscular synergies suffice to be able to reach any point in the moment space. Also, three stability synergies can reconstruct a part of joint angular stiffness space. In addition, the obtained muscular synergies are robust against changes in the amplitude of exerted moment. In this study, it is shown that one can generates any task involves producing determined moment and angular stiffness in the joint, by combining muscular and stability synergies together.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Mohsen Mohammadvali’ee; Ali Mahloojifar
Volume 7, Issue 3 , June 2013, , Pages 265-276
Abstract
One of the most important goals for increasing the recognition and treatment revenue is transmitting the vital data to medical care team, more quickly. Nowadays, use of new technologies for transmission of data is extending every day. In this research, for transmitting electrocardiogram, first we code ...
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One of the most important goals for increasing the recognition and treatment revenue is transmitting the vital data to medical care team, more quickly. Nowadays, use of new technologies for transmission of data is extending every day. In this research, for transmitting electrocardiogram, first we code the signal into a matrix of codes, then we will use bluetooth technology to transmit data from offset device to target device. Signal coding will affect in sending and storing data. This suite of codes that form for the first time in this method, include number and type of extermumes, time of occurring them, samples of signal and etc. We complete the coding, using arithmetic coding. The input of arithmetic coding is the extracted suite of coefficients and the output is arithmetic codes. We use SD-200 serial bluetooth modules produced by SENA™ in transmission of coding coefficients. The transmitter sends extracted coefficients and receptor receives them and reconstructs the primary signal. For testing and evaluating the method, we use MIT–BIH arrhythmia database. In our method, when average Percentage of Root Mean Square Differential (PRD) is equal to 5.93%, Compression Ratio (CR) and Cross Correlation (CC) is equal to 8.69 and 99.8%, respectively. Beside, when PRD is about 10.21%, CR and CC is 13.03 and 99.47%, respectively. The maximum standard deviation of compression ratio in two states is 4.17.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Saeideh Davoodi; Mohammad Reza Daliri
Volume 11, Issue 3 , September 2017, , Pages 265-273
Abstract
Variety of brain region function represent that interactions between different frequency bands, employ general mechanisms of neural communications. Moreover, a method which recently used for information encoding in the brain is phase synchronization that is a process by which two or more cyclic signals ...
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Variety of brain region function represent that interactions between different frequency bands, employ general mechanisms of neural communications. Moreover, a method which recently used for information encoding in the brain is phase synchronization that is a process by which two or more cyclic signals tends to oscillate with a repeating sequence of relative phase angle. Some evidence demonstrated the important role of phase synchronization in cognitive tasks. In this paper we investigated the role of phase synchronization in a new visual discrimination task. For this purpose we collected electroencephalography signals from fifteen subjects during a color discrimination task. The machine learning algorithm, support vector machine (SVM), was used to find out whether this criterion can distinguish two different colors in the mentioned task. The results show that classification accuracy of 75% is achieved using phase synchronization feature. Also efficient frequency bands and contribution of effective electrodes were shown.
Reza Foodeh; Vahid Shalchyan; Mohammad Reza Daliri
Volume 10, Issue 3 , October 2016, , Pages 267-277
Abstract
Extracting discriminative features is a crucial step in brain-computer interfaces (BCIs) that could affect directly on the classification performance. Common spatial patterns (CSP) is a commonly used algorithm for such propose in motor imagery based BCI systems. CPS tries to extract the most appropriate ...
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Extracting discriminative features is a crucial step in brain-computer interfaces (BCIs) that could affect directly on the classification performance. Common spatial patterns (CSP) is a commonly used algorithm for such propose in motor imagery based BCI systems. CPS tries to extract the most appropriate spatial patterns in the electroencephalogram (EEG) signals to discriminate different motor imagery classes. Before applying CSP, Usually EEG signals are filtered out in 8-30 Hz to capture event related desynchronization (ERD) specific frequency rhythms called mu and beta bands. However, this frequency band could be highly subject specific. Therefore, optimizing spectral and spatial filters jointly could improve the classification accuracy. In this paper, we proposed a novel learning algorithm to derive spatial and spectral filters simultaneously using an evolutionary learning algorithm called particle swarm optimization (PSO). Furthermore, we utilized mutual information between extracted features and class labels as a cost function in the learning algorithm. Our simulations on BCI competition IV, dataset 1 reveals that the proposed method significantly outperforms the conventional CSP and filter bank CSP (FBCSP) with two different filter bank architectures.
Samira Rezvani Ardakani; Sajad Mohammad-Ali-Nezhad; Reza Ghasemi
Volume 13, Issue 3 , October 2019, , Pages 273-289
Abstract
Epilepsy is one of the most important neurological disorders in the world. In order to suppress epileptic seizures, various control algorithms have been used. Time to control and reduce attacks and robustness of the controller against variations of pathologic parameters and unwanted oscillations are ...
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Epilepsy is one of the most important neurological disorders in the world. In order to suppress epileptic seizures, various control algorithms have been used. Time to control and reduce attacks and robustness of the controller against variations of pathologic parameters and unwanted oscillations are important to control epileptic seizure. In order to consider these requirements and considering that one of the methods used to suppress epileptic waves is the change in mean soma (electric) potential of the excitatory neurons, this paper applies a fixed-time integral super twisting sliding mode controller to the combination of cortical and optogenetic models. First, the ion current produced in ion channels in optogenetic method is applied to the state variable of the mean electric potential of the excitatory neurons of the cortical model and the cortical and optogenetic models are combined and the controlled voltage applied to the system is applied to neurons of the epileptic zone of the brain as optic photons via the optogenetic model. Then, the mentioned controller is applied to the hybrid model so that the healthy model is tracked by the epileptic model in a fixed time. Finally, using the fixed-time integral super twisting sliding mode controller, the convergence error of the epileptic state to the healthy state has become zero. The amplitude of the control signal is reduced compared to the classic sliding mode control and technical problems and unwanted oscillations which are the shortcomings of the classic sliding mode controller are resolved.
