Sharif Digital Repository

The aim of this thesis was to test predictive coding as a model of cortical organization and function in multisensory processing using a specific brain response, the mismatch negativity (MMN) in both Auditory and visual modalities, and a novel tool for connectivity analysis, dynamic causal modeling (DCM). Predictive coding models state that the brain perceives and makes inferences about the world by recursively updating predictions about sensory input. Thus, perception would result from comparing bottom-up input from the environment with top-down predictions. The generation of the MMN, an event related response elicited by violations in the regularity of a structured auditory or visual... 

There are some problems in calculation of heavy and huge equations which are ill-posed and nonlinear. They need to be solved by the processors. The errors are important in our measurements because this precision is very important in calculation. The Block Method approach solving Forward Problem in Electrical Impedance Tomography (EIT) results produce an exact solution only if the measurements are done with enough accuracy. In this thesis, a 3D model of EIT with Block Method is implemented by means of Digital Signal Processor (DSP) to obtain exact results. In this work it has used a powerful processor called TMS320C6416DSK to reduce the measurement error in equations. It has used Code... 

Electrical impedance tomography is considered as medical and industrial imaging methods which is inexpensive and safer than other imaging methods, but has low quality results. The purpose of this study is providing a practical method to increase its quality. Image reconstruction in EIT always is encountered with both direct and inverse problem. In the forward problem electric potential distribution is achieved from known distribution of electrical impedance and currents, but in the inverse problem, identifying of electrical impedance distribution is the target which is achieved by known electric potential and current distribution. In fact, solving inverse problem results the image... 

The fire event may cause danger to life and property. In general, most fire-detection devices are set on the wall or ceiling. . However, this method is not flexible enough to detect a fire occurrence, and this needs the use of many fire-detection devices in a building. Since it is not suitable, we use an active fire-detection device to detect a fire incident. In the past, smoke sensors were used for fire detection, but often the smoke sensors triggered a false alarm when someone smoked in the room. Therefore, multisensor fire-detection methods are one of the current important developments for fire- detection technology. We design a fire-detection module using an ionization smoke sensor... 

Studies in recent years have shown formation of strongly functionally linked sub-networks during rest, networks that are often referred to as resting-state networks. RSNs not only have basic information about the brain but also play a key role in detecting brain disorders, such as Alzheimer and Autism; Consequently, they have been remarkably noticed by neuroscientists. Numerous methods have been used in order to extract RSNs using resting-states fMRI time series. Independent component analysis (ICA) is the most common method, whi have been reported to show a high level of consistency neurophysiology; however, its results is unstable in subject-level. is weakness restricted the ICA... 

Falls are one of the major causes leading to injury of elderly people. Using wearable devices for fall detection has a high cost and may cause inconvenience to the daily lives of the elderly. In this project, we present an automated fall detection approach that requires only a low-cost depth camera. Our approach combines two computer vision techniques, spatio-temporal fall characterization and a learning-based classifier to distinguish falls from other daily actions. A dense set of spatio-temporal feature vectors are computed from video to provide a localized description of the action, and subsequently aggregated in an empirical covariance matrix to compactly represent the action. Then, we... 

Artificial neural networks are mathematical models inspired by the nervous system and brain. The types and applications of these networks are very widespread nowadays, and it seems that they can be used to track the signals well and estimate the data of the next. In this research, we try to present a model that can predict the future of the trend of noisy signals that have unpredictable behavior, or in other words, chaotic signals. Such research is also widely used in the medical sciences, including the diagnosis of epileptic seizures or heart attacks. In this research, a study with high volatility financial data has been done as an example on this issue and the proposed model tries to be... 

The retina is a light-sensitive layer of tissue at the back of the eyeball wall and is the initial stage of the brain's visual processing stages. This tissue contains more than 60 types of neurons placed in different neuronal layers. All the visual information received from the surrounding environment passes the retina and is encoded into neural signals. Therefore, studying the retina's functionality and bio-inspired modeling of its neurons and their connections are essential in recognizing visual dysfunctions caused by problems in the retina. Also, this modeling can help researchers in proposing solutions for building retinal prosthetics and, in general, performing simulations in the... 

In this thesis, LEON Processor was chosen for its compatible architecture that can be implemented on a wide range of FPGAs. The final designed processor is aimed to conquer soft and hard errors that occur due to cosmic radiations in SRAM cells of an FPGA. The system can finally resist all single SEUs that happen in flip flops and all 4 random errors that take place in each register of the register file. All the flip flops and latches are protected using a TMR scheme. The information redundancy in the regiester file to overcome all 4 random errors is 168% and the errors are corrected by means of a mechanesim that is masked from the processor core. In cache memory, each 32 bit data is... 

Due to the considerable changes taken place in the economic structures and financial systems, the role of banks as substantial economic organizations has become more important and highlighted. Therefore, it is required for banks to develop their services with the world-wide growth of information technology in order to meet the rising online needs of their customers. This goal could be better achieved by the alignment of electronic banking services with a perfect strategy for IT service management which has been made up of widely accepted best practices. Accordingly, the aim of this thesis is establishing a guideline from which banks can plan, implement, and measure their electronic banking... 

Generally speaking a web browser is a software application for surfing the World Wide Web. A user with web browser can request some web pages on the Internet. This request would be sent to web server and would be analyzed. The result would be shown to end user by web browser GUI. A web browser has different parts such as HTML parser, Renderer, browser engine and GUI. The GUI is one of the most important parts of each web browser, because the end users interact with GUI. The classical GUI for surfing has been used in various platforms, such as the PC and Laptop Operating systems. Because of the technological advances and the introduction of tablets and other touch screen devices i. e, smart... 

The existence of motor synergies in motor system as a tool for reducing degrees of freedom has been always debated. In the last two decades some experiments in vertebrates show the existence of motor primitives in spinal cord. In additional by recording electromyogram from frog some regular patterns have been shown. Recently, a motor coordination model based on stochastic optimal feedback control has extracted synergies by mathematical formulation. In addition, according to this model synergies are the optimal solution of the problem and not for simplifying it. However, this model is investigated in linear dynamics. In this thesis, first, an inverse method for extracting synergies is... 

Block Method approach solving Forward Problem in Electrical Impedance Tomography (EIT) results exact solution if the measurements are done with enough accuracy. Solving Forward problem with this method brings complexity to required calculations and sufficient speed is needed to extract required data in minimum time. In this thesis, 3D model of EIT with Block Method is implemented by means of Digital Signal Processor (DSP) to obtain maximum speed. Program code is written both in MATLAB and Code Composer Studio in efficient way to decrease clock cycles of CPU. Moreover, some part of algorithm is modified and the desired speed is obtained. At the end, two kinds of DSP, Fixed-point (TMS320C6416)... 

Magnetic resonance imaging (MRI) is a highly efficient method that can provide acceptable contrast between soft tissues. But the big disadvantage of this method is that its acquisition is slow. To find the reason of being time-consuming should the procedure be surveyed. In the magnetic resonance imaging, location information obtained using phase and frequency encoding gradients. So the output is matrix of image data in the frequency domain, which is called k space. For the formation of the k space phase, need to apply gradients several times and this is the main reason of dullness of the system. Therefore, in this project using software methods try to reduce the scan time as possible. Among... 

Electrical Impedance Tomography, (EIT), is one of the medical imaging technologies, similar to CT-Scan or X-Ray. It can also be used in industrial process monitoring. In this technique a reconstructed image of the inner part of a conductive subject can be made with an array of external electrodes which are connected to the boundary of the subject (e.g., body). It is inexpensive, fast, small and portable. In this imaging method, the image of electrical conductivity (or impedance) distribution of the internal part of a typical subject is reconstructed. The Image reconstruction process is done by injecting an accurate current into the boundary of the subject, measuring voltages around the... 

The implementation of high-order multiple-input multiple-output (MIMO) detectors in complex domain, which finds applications in advanced wireless standards such as WiMAX and Long Term Evolution (LTE) systems, has always been a challenge in the literature. To address this challenge, two novel detection algorithms with their high-throughput VLSI architectures for a 4×4, 64-QAM complex MIMO detector are proposed in this thesis. The proposed architectures can easily be extended to high-order constellation schemes. For the first algorithm Complexity analysis and the synthesis results in a 0.13μm CMOS technology show that compared to the reported VLSI implementations in the complex domain, the... 

Dementia is one of the most common disorders among the elderly population. Statistical analyses show that among several subtypes of dementia, Alzheimer’s disease (AD) is the most frequent cause of dementia and this number is projected to increase. AD not only results in impairment of learning and memory but also in the moderate stages of illness, motor functions are profoundly disturbed, and ultimately will affect the patient's lifetime. The proposed drug treatments for this disease only reduce its progress probability. Therefore, early diagnosis for effective treatment of Alzheimer's disease is one of the critical issues in the field of dementia. This project is an effort to extract... 

Schizophrenia is a devastating disorder that steals the opportunity of having a normal life from the sufferers. Drugs used in treating this disorder usually target psychotic symptoms and do not affect negative symptoms effectively. One of the deficits falling into this category is the impaired reversal learning. These patients usually learn the rules but do not renounce them after the contingencies of reward have been reversed. To investigate the reasons of this impairment, first a hypothesis of how different parts of the brain communicate during reversal learning is proposed using the physiological evidence. Then considering the known relation between the actor-critic model of the... 

Measurement is the start point of identification and analysis of a physical quantity. By recording body movements, one obtains an efficient insight of musculoskeletal performance. Furthermore it leads to quantification of physic-structural health of human. In addition this information can be applied to many human related applications such as: balance survey, sport analysis, muscular pathology, physiology method performance evaluation, etc.With reference to statistics of the elderly fall, the large number of medications with bilateral effects such as instability and drowsiness, arthritis resulted from daily movement misconduct, there is a need for a preemptive system to overcome these... 

Blood is the most important liquid in human body. Red blood cells (RBCs) are the main part of blood. RBCs are rounded, but this shape would be changed during different disease. Blood tests taken to diagnose blood diseases. Current instruments do not provide any information about RBCs morphology, and an expert recognize the RBCs morphology by looking at blood smear under microscope. Regards to low accuracy and performance of this method, an automate method must be presented. Capturing images from blood smear under microscope is simple and low-cost. Although there is few methods on RBCs detection and very limited one on RBCs recognition on the literature, no general method to recognize most of...