Amir Babaoghli; Hadi Soltanizadeh
Volume 13, Issue 3 , October 2019, , Pages 235-246
Abstract
Diseases associated with the retina and macula of the eye, causing permanent loss of vision or a great deal of loss of vision in people, leads to a decrease in the quality of life and a lot of problems in daily life. For this reason, the timely and correct identification of these diseases and disorders ...
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Diseases associated with the retina and macula of the eye, causing permanent loss of vision or a great deal of loss of vision in people, leads to a decrease in the quality of life and a lot of problems in daily life. For this reason, the timely and correct identification of these diseases and disorders has become important. The optical coherence tomography imaging method provides high precision in imaging and good information about the depth of the retina. This imaging technique is a great help in the accurate identification of macular-related diseases. Age-related macular degeneration is one of the most common retinal diseases. The purpose of this study is to design and implement a system that is reliable, fast and can detect the age-related macular degeneration by using optical coherence tomography image processing accurately and quickly. In these studies, histograms of orientational gradients and principal component analysis for extraction of features and AdaBoost ensemble classification method have been used to classify the data. The database used includes 269 patients and 115 healthy people. All three indicators of accuracy, sensitivity and specificity of the implemented system were measured at 100%.
Cardiovascular Biomechanics
Farzad Forouzandeh; Mahdie Haji-Bozorgi; Behrooz Meshkat; Nasser Fatouraee
Volume 8, Issue 3 , September 2014, , Pages 241-248
Abstract
Coronary Artery Diseases are one of the main reasonsof mortality. When these arteries occlude, usually a CoronaryArtery Bypass Graft (CABG) surgery is performed. Sine humanSaphenous Veins (SV) is used for CABG, they are of interest forresearchers. In this study human SV samples undergo inflationtest, ...
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Coronary Artery Diseases are one of the main reasonsof mortality. When these arteries occlude, usually a CoronaryArtery Bypass Graft (CABG) surgery is performed. Sine humanSaphenous Veins (SV) is used for CABG, they are of interest forresearchers. In this study human SV samples undergo inflationtest, using an inflation test device. Displacements of the samplesfor different pressures are analyzed, and average values are usedas input of a computational method. In the numerical simulationthe tissue is assumed as an elastic, isotropic, and homogenoussolid material, and its output is Young’s Modulus (E) ofthetissue. Results show that E of the SV increases linearly with thedistension pressure. Although simplifications were applied in thisstudy, it can be helpful for giving a basic insight aboutmechanical properties of human Saphenous Vein, which can befollowed by more realistic studies in the future.
Human Computer Interaction / HCI
Hadi Soltanizadeh; Pouria Sharifi; Ali Maleki
Volume 16, Issue 3 , December 2022, , Pages 241-255
Abstract
Losing of voice and larynx is a major problem for people with speech disorders. It creates serious and negative consequences on the quality of individual and group life of these people, especially in working environments. The development of an intelligent system based on electromyogram signals with the ...
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Losing of voice and larynx is a major problem for people with speech disorders. It creates serious and negative consequences on the quality of individual and group life of these people, especially in working environments. The development of an intelligent system based on electromyogram signals with the ability to recognize speech (without using sound) can be a window of hope for people who lost their larynx and voice due to cancer. Although progress and studies in this field are growing in our country and in different languages, but these studies have not been done for the Persian language. In this article, for the first time, recognition of Persian words was done using electromyogram of facial muscles. For this purpose, sEMG signals were collected from eight facial muscles and six volunteers while speaking twelve Persian words. Then, MFL, VAR, DAMV, LTKE, IQR and Cardinality features were extracted from each channel and each window from the signal, and the 432 features from each signal were reduced to 33 features using the PCA principal component analysis method. Finally, in order to recognize twelve Persian words, the features were given to SVM, KNN and RF classifiers. The average classification accuracy was 83.16%, 81.91% and 78.97%, respectively. Our evaluation in this article gives the hope that by using EMG signals it is possible to recognize the limited words of Persian language.
Biomechanics / Biomechanical Engineering
Hasan Sayyadi; Seyed Hamid Zare
Volume 9, Issue 3 , December 2015, , Pages 253-265
Abstract
The study focuses on the optimal design of a hybrid rotary MR with waveform boundary T-shaped rotor as prosthesis knee. In the biomechanical prosthesis knee MR fluid to create a variable braking torque depending on the magnetic field is used. By applying a magnetic field, the viscosity of the fluid is ...
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The study focuses on the optimal design of a hybrid rotary MR with waveform boundary T-shaped rotor as prosthesis knee. In the biomechanical prosthesis knee MR fluid to create a variable braking torque depending on the magnetic field is used. By applying a magnetic field, the viscosity of the fluid is actively controlled to achieve the desired braking torque. After a brief description of the configuration of the rotary damper; achievable braking torque formulas is presented. In the following, optimization problem aims to find the optimal geometry in order to maximize the on-state braking torque while off-state torque and weight are within the permitted range. Depending on the application of the referred damper, the maximum braking torque, minimizing torque at off-state, minimizing damper’s weight and have uniform flux density are under consideration. The results of the optimized rotary damper are compared with the reference brake. Then, the performance improvement of the optimized MR brake is discussed.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Ramtin Zargari Marandi; Seyed Hojat Sabzpoushan
Volume 6, Issue 4 , June 2012, , Pages 279-285
Abstract
Recent research in pervasive computing field leads to use of novel techniques for human activity recognition. One of these techniques is electrooculography which helps to record eye movements and by analyzing these movements’ patterns it’s possible to recognize daily life activities like ...
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Recent research in pervasive computing field leads to use of novel techniques for human activity recognition. One of these techniques is electrooculography which helps to record eye movements and by analyzing these movements’ patterns it’s possible to recognize daily life activities like reading. Eye movement patterns during reading can be detected using only EOG signals from horizontal channel instead of both horizontal and vertical channels, so only horizontal channel electrode placement on subject’s face set up for hindrance reduction is used in this work. Despite of channels reduction and by using DTW-based string matching algorithm and reading reference template extraction using wavelet transform and encoding of EOG signal, the performance of classification between reading and non-reading data increased, As it shows 4% increase in maximum recognition rate and also low standard deviation in recognition rate in addition to 7% increase in mean of recall which demonstrate that the algorithm is more robust and reliable in comparison with previous algorithms encountering various situations and subjects.
Biomechanics of Bone / Bone Biomechanics
Mohammad Haghpanahi; Mehdi Pourdanial
Volume 1, Issue 4 , June 2007, , Pages 289-299
Abstract
A 3D anatomically accurate finite element model of the human first cervical vertebra (atlas), including cortical and cancellous bones, was developed in ANSYS 9 based on CT-scan images. The main objective was to investigate the effect of cancellous bone on the value and distribution of maximum and average ...
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A 3D anatomically accurate finite element model of the human first cervical vertebra (atlas), including cortical and cancellous bones, was developed in ANSYS 9 based on CT-scan images. The main objective was to investigate the effect of cancellous bone on the value and distribution of maximum and average Von Mises stress in Atlas. The results showed that the material property of cancellous bone has no significant effect on the location of maximum stress and the pattern of average stress distribution in anterior arch, the junction of posterior arch and lateral mass and the groove of the posterior arch. Although the presence of cancellous bone in the model yielded higher values for the maximum and average stresses. The boundary condition had a considerable effect on this increase. Altering the material property of cancellous bone under neutral and hyperextension loading configurations, affected the average stress only in cancellous bone in the lateral mass, but change in the material property of cortical bone resulted in average stress change both in the cortical and cancellous bones, and in the lateral displacement of the lateral mass as well. The interconnected effects of changing the material properties of these two bone tissues were also studied.
Biomechanics of Bone / Bone Biomechanics
Masoume Haghbin Nazarpak; Farzane Pourasgari; Mohammad Nabi Sarbolouki
Volume 3, Issue 4 , June 2009, , Pages 291-298
Abstract
The scaffolds for bone tissue engineering should consider the functional requirements: porosity, biocompatibility, and biodegradability. In this study, porous Poly (lactic-co-glycolic acid)/Hydroxyapatite composites were prepared with different weight ratios. Porous samples were fabricated by freeze-extraction ...
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The scaffolds for bone tissue engineering should consider the functional requirements: porosity, biocompatibility, and biodegradability. In this study, porous Poly (lactic-co-glycolic acid)/Hydroxyapatite composites were prepared with different weight ratios. Porous samples were fabricated by freeze-extraction method, coated with triblock copolymer and sterilized by UV. Then, human mesenchymal stem cells were cultured on scaffolds. Microstructural studies with SEM suggest the formation of about 50 micrometer size porous structure and interconnected porosity so that cells adhesion within the structure is well in depth in coated samples. DAPI fluorescence microscopy showed cells adhesion to the coated scaffolds and cells diffusion into the pores. Also, direct assay of cell proliferation performed with MTT test showed that, cells grew on the scaffold similar to or more than control samples result. Therefore, these findings suggest that the triblock-coated Poly (lactic-coglycolic acid)/ Hydroxyapatite porous composite scaffolds could provide cells adhesion and proliferation and are appropriate matrices for bone tissue engineering.
Biomedical Imaging / Medical Imaging
Neda Sardaripour; Alireza Sedghi; Ali Yoonessi; Ali Khadem; Hamid Abrishami Moghaddam
Volume 12, Issue 4 , January 2019, , Pages 299-315
Abstract
During vision process, the information produced by rod and cone photoreceptors is compressed in retina and then is transmitted by three separated pathways of ganglion cells, Magno, Parvo and Konio, to the upper level processing centers. There are electrophysiological and psychophysical evidences that ...
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During vision process, the information produced by rod and cone photoreceptors is compressed in retina and then is transmitted by three separated pathways of ganglion cells, Magno, Parvo and Konio, to the upper level processing centers. There are electrophysiological and psychophysical evidences that these three pathways show characteristic patterns of malfunction in multiple sclerosis (MS) patients. Although fMRI can provide accurate localization of the neural activities in these pathways, there is no fMRI study on malfunctions of these pathwyas in MS yet. So by employing the differences in structure and function of these cells, we generated three different visual stimuli with different spatial and temporal frequencies to stimulate each pathway separately. These stimuli were shown to the subject inside MRI scanner by a calibrated projector located outside of scanner room. The fMRI data were acquired from two groups of normal and MS subjects (each including 5 subjects) by using a standard protocol. Finally, the activation results in visual lobe and LGN were analyzed in within-group and between-group levels. The group analysis of fMRI data was performed by using general linear modeling (GLM) and fixed-effect method via FSL software and results showed patterns of malfunctions in visual cortex and LGN in MS group. Also, among Magno, Parvo, and Konio cellular pathways in LGN, just the activation of Magno cellular pathway showed significant malfunction in MS group.
Cardiovascular Biomechanics
Vahid Abouie; Farzad Towhidkhah; Vahid Reza Nafisi; Hani Sharifian
Volume 5, Issue 4 , June 2011, , Pages 305-311
Abstract
Today, Dialysis hypotension during hemodialysis process is the most common problems for about 20 to 30 percent of dialysis patients. In order to avoid this hypotension, blood pressure should be measured during dialysis process continuously and noninvasively But it is practically impossible and few devices ...
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Today, Dialysis hypotension during hemodialysis process is the most common problems for about 20 to 30 percent of dialysis patients. In order to avoid this hypotension, blood pressure should be measured during dialysis process continuously and noninvasively But it is practically impossible and few devices for noninvasive and continuous blood pressure measurement are very expensive. Considering this subject, the parameters related to blood pressure should be used to reach this goal. The blood concentrations and heart rate changes are associated with blood pressure in dialysis patients, so in this study, we determined a model by these two parameters in order to predict the blood pressure of hemodialysis patients. After measuring blood concentration, Heart rate and blood pressure from 14 dialysis patients, using neural network model, we determined a new model that can predict blood pressure in dialysis patient by using blood concentration and heart rate data with 3.8 percent error between the real pressure and the pressure that predicted by the model.
Biological Computer Modeling / Biological Computer Simulation
Pejman Ghassemi; Mohammad Hossein Miranbaygi
Volume 2, Issue 4 , June 2008, , Pages 305-315
Abstract
In this research we present a new method to evaluate changes in size and refractive index of Titanium dioxide (TiO2) nanoparticles which are the main component of anti-UV creams. The main objective of this research is assessing the impact of changing in size and refractive index of TiO2 on the polarization ...
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In this research we present a new method to evaluate changes in size and refractive index of Titanium dioxide (TiO2) nanoparticles which are the main component of anti-UV creams. The main objective of this research is assessing the impact of changing in size and refractive index of TiO2 on the polarization state of backscattered light. The proposed technique is based on modeling the propagated polarized laser beam inside a phantom and evaluating the change in the polarization of backscattered light. The phantom is simulated by software to have the polarization properties of anti-UV creams. As scattering particles (TiO2) in these creams configure polarization properties, then through modeling we have simulated the phantom with matrix of resin epoxy that has unit refractive index including Titanium dioxide nanoparticles. It will be shown that size parameter and relative refractive index of these particles influence cream's properties like purity, quality, coating power and degree of filtration and directly affect its polarization properties. The measurement technique which is presented here is based on scattering polarimetry. To assess the scattering phenomenon, the polarization state of incident and backscattered light is analyzed by simulating a laboratory polarimeter. Then polarization information of the simulated phantom is extracted as Mueller matrix and degree of polarization index. All modeling and simulations are performed in MATLAB 2006 and the results are presented towards the end part of the paper. The main outcome of this research is the ability of extracting and the recognition of those elements of the Mueller matrix which are very sensitive to changes in size parameter and relative refractive index of TiO2. That will define the main markers for quality assessment of anti-UV creams.
Zohre Dehghani Bidgoli; Mohammad Hossein Miranbaygi; Rasoul Malekfar; Ehsanollah Kabir; Tahere Khamechian
Volume 4, Issue 4 , June 2010, , Pages 307-316
Abstract
In this research, we investigated cancerous tissues from several organs of the human body using Raman spectroscopy. Different specimens with different pathologic labels (normal & cancerous) were borrowed from a pathology laboratory, and were investigated using two different Raman spectroscopy systems. ...
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In this research, we investigated cancerous tissues from several organs of the human body using Raman spectroscopy. Different specimens with different pathologic labels (normal & cancerous) were borrowed from a pathology laboratory, and were investigated using two different Raman spectroscopy systems. Since one of the goals of this investigation was detection of cancer, independent of type of the system, we introduced some algorithms for removing systemic differences from the spectra. Then we removed noise and fluorescence signals using a new wavelet created with LWT. The best classification result was 83% in differentiating between normal and cancerous specimens using the SVM classifier
Neural Network / Biological & Artificial Neural Network / BNN & ANN
Seyedeh Sadaf Razavinezhad; Amir mohammad Fallah; Seyed Abolghasem Mirroshandel
Volume 14, Issue 4 , February 2021, , Pages 307-320
Abstract
Diabetes is a common disease all around the world. It is a difficult and incurable but controllable disease, so it is important to control and prevent its complications. Thus, low error and smart methods are used to predict blood glucose levels and prevent dangerous complications to control it effectively. ...
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Diabetes is a common disease all around the world. It is a difficult and incurable but controllable disease, so it is important to control and prevent its complications. Thus, low error and smart methods are used to predict blood glucose levels and prevent dangerous complications to control it effectively. In this regard, different methods were investigated. In this research, two models based on deep learning technique are used which produce efficient and optimal results. These models are composed of different combinations of long short-term memory and feed forward neural networks which predict the patient's future blood glucose levels with considerable accuracy and speed. To achieve more comprehensive model, 81,200 blood glucose data was evaluated through 203 patients. In addition, 27 effective features in patients' blood glucose levels are considered in this regard. Furthermore, cross-validation method which is suitable for time series was used for more accurate evaluation. The results showed that Autoregressive Integrated Moving Average model could not predict blood glucose levels considering this amount of data and system hardware limitations, while the models based on deep learning had good performance and good speed. Furthermore, the second proposed model for the prediction horizons of 5, 10, and 15 minutes outperformed the first one with 13.8%, 16%, and 18.9%, respectively. Therefore, the second proposed model can be more reliable for predicting blood glucose. So, it can be used in smart warning systems to prevent hypoglycemia, which is a dangerous and widespread problem of type 1 diabetes.
Bioelectrics
Sobhan Sheykhivand; Tohid Yousefi Rezaii; Zohreh Mousavi; Saeed Meshgini
Volume 11, Issue 4 , February 2018, , Pages 313-325
Abstract
Using an intelligent method to automatically detect sleep patterns in medical applications is one of the most important challenges in recent years to reduce the workload of physicians in analyzing sleep data through visual inspection. In this paper, a single-channel EEG-based algorithm is used to automatically ...
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Using an intelligent method to automatically detect sleep patterns in medical applications is one of the most important challenges in recent years to reduce the workload of physicians in analyzing sleep data through visual inspection. In this paper, a single-channel EEG-based algorithm is used to automatically identify sleep stages using discrete wavelet transform and a hybrid model of simulated annealing and neural network. The signal is decomposed using a discrete wavelet transform into seven levels and statistical properties of each level is calculated. To optimize and reduce the dimensions of feature vectors, hybrid model of simulated annealing algorithm and multi-layered neural network are used. Then ANOVA test is applied to validate the selected features. Finally the classification is performed on the validated features by a perceptron neural network with a hidden layer, which provides an average of 90% classification ccuracy for 2 to 6-class classification of different steps of sleep EEG. Suggesting that the proposed method has higher degree of success in classifying sleep stages compared to the existing methods.
Bioelectrics
Farzaneh Manzari; Peyvand Ghaderyan
Volume 15, Issue 4 , March 2022, , Pages 313-328
Abstract
Obsessive-Compulsive Disorder (OCD) is the fourth most common mental disorder and the tenth cause of disability worldwide. This disorder can lead to cognitive impariments in attention, memory, thinking, auditory processing of words and visual cognition. Previous studies have demonstrated that OCD is ...
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Obsessive-Compulsive Disorder (OCD) is the fourth most common mental disorder and the tenth cause of disability worldwide. This disorder can lead to cognitive impariments in attention, memory, thinking, auditory processing of words and visual cognition. Previous studies have demonstrated that OCD is associated with changes in connectivity between different lobes of the brain. Hence, the quantification of symmetry and connectivity between different brain regions has attracted great attention. This study has provided a new efficient approach based on analytic representation of EEG signals and statistical features to quantify the difference of intrinsic components of brain activity between brain lobes. For this purpose, phase spectra and amplitude envelopes of the analytic EEG signals have been extracted and analyzed. Furthermore, Non-Negative Least Square sparse classification method has been used for discriminating between healthy control group and OCD patients. The detection capability of the proposed method has been studied in 19 healthy subjects and 11 patients, performing simple flanker tasks. The obtained results have demonstrated the effectiveness of the combined amplitude and phase information in OCD detection with high average accuracy rate of 93.78 %. In comparison between different regions, the inter-hemispheric features and those extracted from the frontal lobe and frontal-parietal network have shown more efficiency in diagnosing the OCD. This study has also highlighted more importance of amplitude information in the OCD detection.
Sports Engineering / Sports Biomechanics
Abbass Farjad Pezeshk; Heydar Sadeghi; Mohammad Shariatzadeh Joneidy; Zahra Safaie Pour
Volume 10, Issue 4 , January 2017, , Pages 315-324
Abstract
Background and Aim: The Stiffness of human could have the substantial effect on motion efficiency by the influence in Stretch-Shortening cycle. The purpose of this study was to investigate the relationship between mechanics of the negative and positive phases of hopping; to identify the effect of ...
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Background and Aim: The Stiffness of human could have the substantial effect on motion efficiency by the influence in Stretch-Shortening cycle. The purpose of this study was to investigate the relationship between mechanics of the negative and positive phases of hopping; to identify the effect of stiffness and stretch shortening cycle on the optimal performance of the cyclic movements. Materials and Methods: To calculate the leg stiffness, knee and ankle joint stiffness and also angular velocity of the 30 young male with the age range of 18-33 and weight range of 60-88 kg during hopping, we used motion analysis and force platform system. Results: the results of the Principle component analysis showed that all of the ankles related parameters were classified on the first PC. Pearson correlation coefficient also showed that there are a significant relationship between joint stiffness, negative and positive mechanical energy and angular velocity (P<0.05, P<0.01). Conclusion: Due to results of this study, it seems that during cyclic motions, the common mechanism for performing strength and power activity is not useful for having the maximum advantage from stretch shortening cycle, though the ankle joint stiffness reduction is an efficient way to decrease required energy for performing these activities.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Nasrin Shourie; Seyed Mohammad Firouzabadi; Kambiz Badie
Volume 7, Issue 4 , June 2013, , Pages 321-331
Abstract
In this article, differences between multichannel EEG signals of artists and nonartists were investigated during visual perception and mental imagery of some paintings and at resting condition using scaling exponent. It was found that scaling exponent is significantly higher for artists as compared to ...
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In this article, differences between multichannel EEG signals of artists and nonartists were investigated during visual perception and mental imagery of some paintings and at resting condition using scaling exponent. It was found that scaling exponent is significantly higher for artists as compared to nonartists during the three mentioned states, suggesting that scaling exponent may reflect the influence of artistic expertise. No significant difference in scaling exponent was observed between the visual perception and the mental imagery tasks. In addition, the two groups were classified using scaling exponent of channel C4 and Neural Gas classifier during the visual perception, the mental imagery and the resting condition. The average classification accuracies were 50%, 58.12% and 70%, respectively. The obtained results suggest that discriminability in scaling exponent decreases during the performance of similar cognitive tasks.
Maryam Fatemi; Mohammad Reza Daliri
Volume 13, Issue 4 , December 2019, , Pages 327-336
Abstract
Controlling of neuroprostheses to restore grasping ability in patients with paralyzed or amputated upper limbs is one of the important applications of BCI systems. The ability to get objects is necessary for daily works so, for a reliable function of the neuroprostheses, it is necessary for the user ...
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Controlling of neuroprostheses to restore grasping ability in patients with paralyzed or amputated upper limbs is one of the important applications of BCI systems. The ability to get objects is necessary for daily works so, for a reliable function of the neuroprostheses, it is necessary for the user to control the amount of force needed for grasping. For this reason, increasing the accuracy of continuous force decoding is an important issue for the convenient function of these BCI systems. In most studies in the field of force decoding, linear models such as wiener filter, Kalman filter, PLS, etc. are used to decode force. So far, the effect of using nonlinear models is not investigated on force decoding. The goal of this study is to investigate the effect of using nonlinear regression models based on kernel functions on the accuracy of force decoding in Vistar rats using local field potential signals. To do this, we choose ridge regression, PCR and PLS methods and use the Gaussian kernel function to construct a generalized nonlinear model for the force decoding. Evaluating kernel ridge, kernel PCR and kernel PLS methods shows that considering nonlinear relations between brain signal’s features improves decoding accuracy. The mean coefficient of determination (R2) improves 12.7% in kernel ridge toward ridge regression, 25.5% in kernel PCR toward PCR and 19.1% in kernel PLS toward PLS method. The best decoding accuracy has been achieved by the kernel ridge regression method and the mean correlation coefficient between the estimated and measured force is 0.72 and R2 is 0.62.
Biological Computer Modeling / Biological Computer Simulation
Seyed Hojat Sabzpoushan; Niloofar Shahidi; Azadeh Ghajarjazy
Volume 9, Issue 4 , February 2015, , Pages 351-360
Abstract
Abnormal oscillations of ventricular cell action potential can lead to cardiac arrhythmias. Early afterdepolarizations (EADs) is one kind of these oscillations that have been widely studied in the field of cardiac arrhythmias diagnosis and therapies. Nowadays although ventricular cell models have been ...
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Abnormal oscillations of ventricular cell action potential can lead to cardiac arrhythmias. Early afterdepolarizations (EADs) is one kind of these oscillations that have been widely studied in the field of cardiac arrhythmias diagnosis and therapies. Nowadays although ventricular cell models have been developed, yet dynamical mechanisms of EADs remain unknown that need more researches. In this paper, using phase plane analysis of a minimal model of ventricular cell, we show that EADs are occurred as a result of Hopf and homoclinic bifurcations in ventricular cell. We also show that during period pacing, chaos happens at the transition from no EAD to EADs. This result provides a distinct explanation for the EAD behavior of the cardiac cells and also explains EADs dynamics in accordance with experiment results. While this research was performed for ventricular cells, but the achieved results can be extend to other excitable systems and used in the prediction of oscillation due to the changes of system parameters.
Cardiovascular Biomechanics
Navid Soltani; Abbas Nasiraei Moghaddam; Nasser Faturaee; Saeed Seyri; Aisa Rassoli
Volume 8, Issue 4 , February 2015, , Pages 359-370
Abstract
Experimental tests and equations on the continuum mechanics are used in order to obtain the constitutive models of soft tissue using in predictive heart simulation. Considering the myocardium as one of the important tissues, in this paper first the morphology and structure of myocardium has been reviewed ...
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Experimental tests and equations on the continuum mechanics are used in order to obtain the constitutive models of soft tissue using in predictive heart simulation. Considering the myocardium as one of the important tissues, in this paper first the morphology and structure of myocardium has been reviewed and the mechanical response of passive form of this tissue has been investigated. The myocardium of left ventricle was considered as non linear elastic, in-compressible and non homogeneous material and using of bi-axial test in 3 lambs myocardium on fiber direction; a constitutive model of this tissue has been proposed. The model so constructed is then evaluated against the biaxial data, and values of the material constants have been obtained by curve fitting so the final model states the strain-energy function as cauchy's invariants which can be helpful in heart simulation.
Fluid-Structure Interaction in Biological Media / FSI
Hamed Avari; Farzan Ghalichi; Majid Ahmadlouy Darab
Volume 2, Issue 1 , June 2008, , Pages 39-46
Abstract
Adjusting the rhythm of breath is one of the important parameters that a successful athlete must consider. In this paper, the relationship between man's activity and respiration rhythm is studied. A numerical simulation is carried out on a 2D axi-symmetric model using computational fluid dynamics (CFD) ...
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Adjusting the rhythm of breath is one of the important parameters that a successful athlete must consider. In this paper, the relationship between man's activity and respiration rhythm is studied. A numerical simulation is carried out on a 2D axi-symmetric model using computational fluid dynamics (CFD) method. The model considers the oxygen uptake in the pulmonary capillaries in alveolar microcirculation system. The geometry consists of three main parts: a stationary capillary membrane, a moving plasma region and four semi-circular-shaped RBCs. Results show an inverse relationship between saturation time of RBCs and respiration rhythm. Using an inversion factor, a relationship is presented to assess the proper respiration rhythm for different exercise states.
Biomechanics of Bone / Bone Biomechanics
Abdorreza Sheikh Mehdi Mesgar; Zahra Mohammadi; Fathollah Moztarzadeh; Mahtab Ashrafi Khouzani; Zeinab Sadat Mohammadi
Volume 1, Issue 1 , June 2007, , Pages 39-51
Abstract
Amorphous carbonated calcium phosphates (ACCPs) with different carbonate contents and Ca/P ratios were reproducible synthesized by the reaction parameters as low temperature, high pH value, using initial solutions of calcium and phosphate at low concentrations, and various amounts of carbonate, as well ...
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Amorphous carbonated calcium phosphates (ACCPs) with different carbonate contents and Ca/P ratios were reproducible synthesized by the reaction parameters as low temperature, high pH value, using initial solutions of calcium and phosphate at low concentrations, and various amounts of carbonate, as well as freeze drying of the precipitates. The addition of carbonate to the solutions led to form precipitates with higher Ca/P ratios with respect to the initial solutions. Heat treatment of freezedried ACCPs at 500 °C had no influence on their amorphous structure. The results of elemental carbon and thermal analysis showed that the carbonate may be eliminated in a wide range of temperature (500−1150oC). Dissolution rate of ACCPs in the simulated bone resorption medium was dependent to the contents of carbonate and remaining water. Dissolution rate of the specimens with higher carbonate contents was controlled by the carbonate content, but the amount of remaining water had major influence on the dissolution rate of the precipitates with lower carbonate contents. The dissolution kinetics was found to follow a shrinking-core model, with product layer as the ratedetermining step. Formation of an amorphous calcium phosphate and/or thermodynamically desirable dicalcium phosphate dihydrate as possible product layer prevents complete resorption of ACCPs under bone resorption conditions, and promotes osteoblastic activation process through nucleation and growth of biological apatite.
Scaffolding / Bio-Scaffolds
Seyedeh Sara Kamali; Haniye Abdi Kordlar; Maryam Saadatmand; Shohreh Mashayekhan
Volume 14, Issue 1 , May 2020, , Pages 43-53
Abstract
Successful cell culture in large scale 3D scaffolds in tissue engineering is still challenging and requires full control over physical, chemical and mechanical properties of the applied scaffolds. Recently, using printers for the fabrication of 3D scaffold with a structural arrangement of fibers has ...
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Successful cell culture in large scale 3D scaffolds in tissue engineering is still challenging and requires full control over physical, chemical and mechanical properties of the applied scaffolds. Recently, using printers for the fabrication of 3D scaffold with a structural arrangement of fibers has been extensively developed, because it is possible to define the structure of scaffold geometry before manufacturing. The aim of this study was the investigation of the effective geometrical parameters on the 3D symmetric porous scaffold from the mass and momentum transport phenomena point of view. In this way, the mass and momentum transfer equations were solved using COMSOL Multiphysics software. In 3D scaffolds, the optimum model is the one that can provide a more appropriate environment for the cultured cells leading an increase in the attached cell number. The oxygen concentration reaching the bone cells should be greater than 0.02 mol/m3 in order to prevent cell death. Moreover, the fluid shear stress regime must be such that (between 10-5 to 10-3 Pa) it could not cause cell detachment. After studying the results of the simulation and changing the different parameters such as fiber diameter, fiber distance and the width of the channels, the appropriate structure was obtained regarding maximum shear stress and minimum oxygen concentration, and then the effect of fluid flow rate on maximum shear stress was examined for the appropriate structure. The optimized model with a fiber diameter of 0.25 mm, a fiber distance of 0.25 mm, and a channel width of 0.25 mm was proposed that fluid flow inlet velocity was 5×10-5 m/s.
Fluid-Structure Interaction in Biological Media / FSI
Borhan Alhoseini Hamedani; Mehdi Navidbakhsh; Hosein Ahmaditafti
Volume 5, Issue 1 , June 2011, , Pages 45-56
Abstract
In this paper, study of mechanical properties of human blood vessels is considered, especially those of related to the Coronary Artery Bypass Graft (CABG). Unfortunately more than 30% of saphenous grafts are re-occluded within 10 years while mammary artery shows better results. In this study elastomechanical ...
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In this paper, study of mechanical properties of human blood vessels is considered, especially those of related to the Coronary Artery Bypass Graft (CABG). Unfortunately more than 30% of saphenous grafts are re-occluded within 10 years while mammary artery shows better results. In this study elastomechanical properties of human saphenous vein, which is common in CABG, is studied. Stress-stretch behavior of these samples after a cyclic loading was obtained and large deformation formulation was used to obtain real stress and stretch ratio of these vessels. Then a fourth order polynomial was used to show nonlinear behavior of these results. Results show that blood vessel stiffness in longitudinal direction is two times greater than circumferential direction, while it is more than 74% stretchable in the circumferential direction. So modulus of elasticity in longitudinal direction is greater than circumferential direction. If we continue stretching until final rupture after maximum strength, longitudinal samples will be broken down faster than circumferential samples because of collagen fibers orientation.
Cell Biomechanics / Cell Mechanics / Mechanobiology
Seyed Hojat Sabzpoushan; Fateme Pourhasan Zadeh; Azar Badangiz
Volume 4, Issue 1 , June 2010, , Pages 45-52
Abstract
The heart tissue is an excitable media. Cellular Automata is an approach describing cardiac action potential propagation. One of the advantages of Cellular Automata approach over the differential equations based models is its high speed in large scale simulations. Prior Cellular Automata models are not ...
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The heart tissue is an excitable media. Cellular Automata is an approach describing cardiac action potential propagation. One of the advantages of Cellular Automata approach over the differential equations based models is its high speed in large scale simulations. Prior Cellular Automata models are not able to eliminate flat edges in the simulated patterns or have large neighborhoods. Moreover, they are not able to match the shape of ventricular action potential to the real ones. In this paper, we present a new model which prevents flat edges creation by using minimum number of neighbors. we also rather preserve the real shape of action potential by using linear curve fitting of a well known electrophysiological model.
Biomedical Image Processing / Medical Image Processing
Bahram Momen Mehrabani; Mohammad Javad Abolhassani; Alireza Ahmadian; Javad Alirezaie
Volume 3, Issue 1 , June 2009, , Pages 47-54
Abstract
The main purpose of this work is introducing a novel method of temperature monitoring using B-Mode Ultrasound digital images. Thermal dependence of sound speed causes a virtual displacement of scatterer particles. The virtual displacement is computed using speckle tracking methods. Horn-Shunck algorithm ...
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The main purpose of this work is introducing a novel method of temperature monitoring using B-Mode Ultrasound digital images. Thermal dependence of sound speed causes a virtual displacement of scatterer particles. The virtual displacement is computed using speckle tracking methods. Horn-Shunck algorithm was applied to a tissue mimicking phantom to measure the virtual displacement. A heating resistor was used in this phantom to generate temperature elevation. The DICOM ultrasound images were acquired using commercial SIMENES ultrasound imaging system with 10MHz linear probe. The accuracy of noninvasive temperature estimation was measured comparing with invasive temperature measurement. The phantom is warmed up to the 8. The mean error of temperature estimation was found to be 0.4°C and peak error 0.9°C. Fast temperature estimation can be achieved using Optical-Flow methods. This Method is a differential based motion estimation method that estimates displacement by calculating the optical pattern changes caused by movements between two frames. Noise sensitivity is the main infirmity of Horn-Schunck method.
