Sharif Digital Repository

In this paper, a biosignal analysis approach to determine the relation between a typical cell action current (potential) and its resulted biosignals is presented. This relation is a logical result that can be obtained from the electrophysiological concepts governing the biosignals generating phenomena and can tell us some facts about its generating organ. Therefore, one has an input (Action Current or AC), an output (biosignal) and an unknown system (black box) relating them together. In this study, a linear system modeling is proposed to identify that relationship. This system acts as a transfer function (or generating function) that generates different forms of biosignal from a unique... 

The vulnerability of microprocessors to soft errors is increasing due to continuous shrinking in fabrication process. Recent studies show that 1-5% of the SEUs (single event upset) can cause MBUs (multiple bit upsets). The probability of MBU generation due to SEU is increasing because of the reduction in minimum energy required to flip a memory bit in modern technologies. Register file is the most sensitive component in a microprocessor. In this paper, we present an innovative way to protect registers in a 64-bit register file for a RISC processor using extended Hamming (8, 4) code (SEC-DED code) and narrow-width values. A narrow-width value can be represented by half number of bits of the... 

In order to access to an accurate detection of electrocardiogram signal in medical approaches especially mobile health and wearable medical devices, development of noise cancellation algorithms seems essential. In this study, the power line noise in ECG signal is filtered using several methods including DFT based, IIR, FIR, adaptive, Kalman, Wavelet and higher order statistics filters. Signal-to-noise ratio (SNR) improvements of the filters are then compared. It is found that FIR and IIR filtering show higher SNR improvement  

Mapping and Scheduling are two central and critical steps in design flow of the Networks on Chips (NoCs). They deal with implementation of the applications on NoCs. In this paper a novel energy aware algorithm, called EAMS, for mapping and scheduling of concurrent applications to NoC platforms is developed. It is considered that, the NoC architecture consists of a set of heterogeneous IP cores. The introduced algorithm finds a mapping of the tasks of the application to available IP cores so that the overall energy consumption, meeting task deadlines, is minimized  

Introduction: Temporal lobe epilepsy (TLE) is the most common and drug resistant epilepsy in adults. Due to behavioral, morphologic and electrographic similarities, pilocarpine model of epilepsy best resembles TLE. This study was aimed at determination of the changes in electroencephalogram (EEG) sub-bands amplitude during focal seizures in the pilocarpine model of epilepsy. Analysis of these changes might help detection of a pre-seizure state before an oncoming seizure. Methods: Rats were treated by scopolamine (1mg/kg, s.c) to prevent cholinergic effects. After 30 min, pilocarpine (380 mg/kg, i.p) was administered to induce status epilepticus (SE) and 2 hours after SE, diazepam (20 mg/kg,... 

Non-invasive measurement of flow-mediated dilation (FMD) in the brachial artery for assessing endothelial function is costly and operator-dependent, limiting its application to research cases. In this paper, an approach based on a physiological model between normalized central blood pressure and finger photoplethysmogram is presented. Baseline model parameters are estimated using a genetic algorithm in 30 subjects consisting of ten normal blood pressure (BP), ten high-BP and ten elderly volunteers. Beat-to-beat fitness values after reactive hyperaemia are calculated using baseline (before cuff occlusion) data. Results show that stimulus-induced changes are fairly described with a first order... 

Effective classification of motor imagery electroencephalograph (EEG) data is an important challenge. Spatial filtering such as Common Spatial Pattern (CSP) and its variants are commonly used for this task. However, CSP effectiveness depends on the subject-specific frequency band. Even by optimally selecting a subject-specific frequency band, this method still fails for some subjects. On the other hand, some studies suggest that temporal features may discriminate classes more efficiently. This work proposes a hybrid method based on elastic net and Least Absolute Shrinkage and Selector Operator (LASSO) to optimally select between spatial and temporal features. This algorithm uses joint... 

The model introduced in this article for neural system describes both physiological and psychological concepts of neural system and is based on the models of individual elements of the system. This model includes psychological characteristics such as; perception, prediction, learning and response planning, and physiological features such as; sensory analysis, memory and motor execution. The model is designed in such a way that it describes the performance of the neural system for a key-pressing test. The key-pressing experiment consists of a screen with numbers from 1 to 9, which is shown to the operator where one of the numbers is specified by a special color and the operator is to push the... 

In this paper, distributed electroencephalographic (EEG) sources in the brain have been mapped with the objective of early diagnosis of Alzheimer's disease (AD). To this end, records from a montage of a high-density EEG from 17 early AD patients and 17 matched healthy control subjects were considered. Subjects were in eyes-closed, resting-state condition. Cortical EEG sources were modeled by the standardized low-resolution brain electromagnetic tomography (sLORETA) method. Relative logarithmic power spectral density values were obtained in the four conventional frequency bands (alpha, beta, delta, and theta) and 12 cortical regions. Results show that in the left brain hemisphere, the theta... 

Block method approach to solve EIT problem results exact solution if the measurements are done with enough accuracy. However, solving the EIT problem with this method brings complexity to the required calculations. In this article, the 3D model of EIT with block method is extracted. The required equations to solve the forward problem are then generated. To solve the problem, a series of extra equations are added to the set of equations. These equations helped to devise a non-iterative method to find the parameters in forward problem. ©2004 IEEE  

In wireless body area networks (WBANs) it is necessary to devise an energy-efficient MAC scheduling mechanism which is capable of meeting strict QoS requirements. In this paper, special characteristics of WBAN channels, namely, the slow fading, the periodicity of fading, and the correlation among the channels have been exploited to formulate the sensor scheduling problem as a partially observable Markov decision problem (POMDP). Specific algorithms based on value iteration and pruning have been proposed in order to reduce the computational burden associated with the corresponding POMDP. The proposed scheduling mechanism is compared against a TDMA scheduling for a three-sensor network, and an... 

This study proposes a new method for the detection of a weak scatterer among strong scatterers using prior-information ultrasound (US) imaging. A perfect application of this approach is in vivo cell detection in the bloodstream, where red blood cells (RBCs) serve as identifiable strong scatterers. In vivo cell detection can help diagnose cancer at its earliest stages, increasing the chances of survival for patients. This work combines time-domain US with frequency-domain compressive US imaging to detect a 20-μ MCF-7 circulating tumor cell (CTC) among a number of RBCs within a simulated venule inside the mouth. The 2D image reconstructed from the time-domain US is employed to simulate the... 

Electrical Impedance Tomography (EIT) is a visualization of the internal electric conductivity of an object using measurements performed on its surfaces. As an Inverse problem, the solution can be approximated by means of Artificial Neural Networks. In this paper, an Artificial Neural Network solution to this Inverse Problem is presented. Based on the electrical voltage and current measurements on the boundary of the object, the conductivity distribution has been found and the resulting error is calculated. The error is compared for different Neural Network architectures to detect and minimize the errors caused by the solution method. Also, different Neural Networks were tested in the noisy... 

In assembly level programming we need to know the mnemonic of each assembly instruction. But it is not so easy to remember mnemonics of all instructions, while the instruction set of Pentium processor includes 280 instructions. In this paper we introduce a new programming approach to assembly level programming in which most important assembly instructions (about 100 instructions) can be substituted for simple equivalents. These equivalent instructions are based on simple familiar operators and make a large simplification in assembly programming. This new language has a free format structure and hence is called Free Format Assembly Language. Evaluating the performance of this language using a... 

Seizures are defined as manifest of excessive and hypersynchronous activity of neurons in the cerebral cortex and represent a frequent malfunction of the human central nervous system. Therefore, the search for precursors and predictors of a seizure is of utmost clinical relevance and may even guide us to a deep understanding of the seizure generating mechanisms. In this study we analyzed invasive electroencephalogram (EEG) recordings in rats with experimentally induced generalized epilepsy with a nonlinear method called, dissimilarity index. In order to predict epileptic seizures automatically, Bhattacharyya distance between trajectory matrix of reference window, during an interval quite... 

In this paper, a novel service that uses audio watermarking for covert communication through telephone system is presented. This system is suitable for ISDN and PSIN networks and it can be modified for using in mobile systems. We use a Direct sequence spread spectrum algorithem with perceptual modeling of HAS for embedding watermark into the audio or speed signals. The watermark is robust against telephone channel attacks such as AWGN , Low pass filtering, D/A-A/D conversion, Downsampling down to 64 slips and A-Law or μ-Law conversion. This system is also robust against audio format conversion such as wave (windows PCM) format to mp3 (down o 64 kbps compression. © 2006 IEEE  

2D block method (2D BM) is a new approach to solve inverse problem as one of the most challenging case in Electrical Impedance Tomography (EIT). In this method, a tissue is modeled by some blocks to construct a medical image of a body limb. Recently, a non-iterative linear inverse solution is introduced to solve the inverse problem in the 2D BM. But effect of measurement error has not been considered for non-iterative linear inverse solution yet. In this paper, an appropriate method is proposed to investigate the error propagation in 2D BM. The effect of measurement error is considered as well through different examples. Results show that the BM is very sensitive to the measurement error and... 

The Block method approach to solve EIT problem leads to an exact solution if the measurements are done without error. Non-iterative method is a feasible approach on solving 3D EIT forward problem. However, the effect of the measurement error has not been considered in this method yet. In this article, the 3D model of EIT with block method has been considered. The required equations to solve the forward problem are then generated. To solve the forward problem, non-iterative method has been employed. Effect of the measurement error on forward problem for a 3D model of EIT are generated. It has been shown that for a sample 3D model, measurement error can propagate exponentially. ©2007 IEEE  

This study presents a new method for epilepsy detection based on autoregressive (AR) estimation of EEG signals. In this method, optimum order for AR model is determined by Bayesian Information Criterion (BIC) and then AR parameters of EEG signals (from EEG data set of epilepsy center of the University of Bonn, Germany) and their sub-bands (created with the help of wavelet decomposition) are extracted based on it. These parameters are used as a feature to classify the EEG signals into Healthy, Interictal (seizure free) and Ictal (during a seizure) groups using multilayer perceptron (MLP) classifier. Correct classification scores at the range of 91% to 96% reveals the potential of our approach... 

A new approach is introduced to estimate the formal information of neurons. Formal Information, mainly discusses about the aspects of the response that is related to the stimulus. Estimation is based on introducing a mathematical nonlinear model with Hammerstein-Wiener system estimator. This method of system identification consists of three blocks to completely describe the nonlinearity of input and output and linear behaviour of the model. The introduced model is trained by 166 spikes of neurons and other 166 spikes are used to test and validate the model. The simulation results show the R-Value of 92.6 % between estimated and reference information rate. This shows improvement of 1.41 % in...