Sharif Digital Repository

Current design codes provide empirical equations for the drift capacity of unreinforced masonry (URM) walls that are based on results of quasi-static cyclic shear-compression tests. Yet different experimental campaigns have used various approaches of imposing fixed-fixed boundary conditions at the wall top which may affect the test results. This article investigates, by means of numerical simulations, the influence of experimental setups on the force and drift capacities of in-plane loaded URM walls subjected to double-fixed conditions. It is shown that controlling the shear span or the top rotation while keeping the axial force constant leads to very similar results. Controlling the axial... 

Empirical drift capacity models for in-plane loaded unreinforced masonry (URM) walls are derived from results of quasi-static cyclic shear-compression tests. The experimentally determined drift capacities are, however, dependent on the applied demand, i.e., on the loading protocol that is used in the test. These loading protocols differ between test campaigns. The loading protocols applied in tests are also different from the displacement histories to which URM walls are subjected in real earthquakes. In the absence of experimental studies on the effect of loading histories on the wall response, this article presents numerical simulations of modern unreinforced clay block masonry walls that... 

Bioremediation of soil and groundwater sites contaminated by petroleum hydrocarbons is known as a technically viable, cost-effective, and environmentally sustainable technology. The purpose of this study is to investigate laboratory-scale bioremediation of petroleum-hydrocarbon contaminated soil through development of eight bioreactors, two bioreactors for each bioremediation mode. The modes were: (1) natural attenuation (NA); (2) biostimulation (BS) with oxygen and nutrients; (3) bioaugmentation (BA) with hydrocarbon degrading isolates; (4) a combination of biostimulation and bioaugmentation (BS-BA). Total petroleum hydrocarbons (TPH) mass balance over the bioreactors showed about 2% of... 

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,... 

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 this research, a web-based simulator is developed, which can be used for generating image sequences of moving spermatozoa cells. It can be used for assessment of multiple object tracking algorithms, especially Computer Aided Sperm Analysis (CASA) systems. The developed software has many useful parameters such as blurring images or adding noise and it also gives full control of sperm counts and types. To illustrate performance of the developed simulator, three parameters (spermatozoa population, standard deviation of Gaussian blur filter and noise intensity) have been swept and the results of three different multiple object tracking algorithms were compared as an application of this... 

Electrical impedance tomography (EIT) is a simple, economic and healthy technique to capture images from the internal area of the body. Although EIT is cheaper and smaller than other imaging systems and requires no ionizing radiation, the resolution associated with this technique is intrinsically limited and the image reconstruction algorithms proposed up to now are not efficient enough. In addition to low resolution EIT is an ill-posed inverse problem. Block method in EIT is based on electrical properties of materials and used to enhance image resolution and also to improve the reconstruction algorithm. Recently an inverse solution for EIT based on block method has been developed, however,... 

Electrical impedance tomography is a simple and economic medical imaging technology which permits regional assessment of the electrical properties of organs within the body based on measurements made from electrodes on the surface of the body. Block method is a new solution for electrical impedance tomography used to enhance image resolution and to improve reconstruction algorithm. Image reconstruction by block method is an ill-posed and nonlinear problem also has memory and time consuming process which can be improved by using modified equations. Improving forward solution for block electrical impedance tomography method can make linear equations for image reconstruction algorithm  

Wireless broadband access has gained so much attention in recent years. IEEE 802.16d as a standard in this field has provided MAC layer and PHY layer specifications. It has adopted OFDM method for one of PHY specifications that uses 256 subcarriers. In this paper we verify the effects of subchannelization option in uplink, on bit error rates in 16QAM modulation. Simulation results show that considerable improvement is obtained using half of the subcarriers  

Brain is the most complicated organ of body. It controls the activity of all other organs. Understanding its function and its language could give us a direct communication pathway for connecting with injured motor organ and it could be the core of functional repairing. Neurons are the vertices of a vast network that generates the brain signals. Neuronal recordings capture brain activity signatures. The processing of these signals can help to translate brain's language. Usually it follows three main stages: spike detection and extraction, spike sorting, and intention extraction from the encoded signal. In this work, we introduce an original idea based on Hidden Markov Models (HMM) which helps... 

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  

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  

In this paper we have presented a hardware implementation of 32-bit Fault-tolerant ALU (Arithmetic and Logic Unit) which is compared with the current techniques, Residue code, Triple Modular Redundancy (TMR) with single voting and TMR with triplicated voter that are widely used in space application to mitigate the upsets, in terms of area penalty. We consider BCH (Bose, Chaudhuri, and Hocquenghem) codec (encoder, decoder) using the prototyping FPGA (Field Programmable Gate Array). The new implementation of ALU employing BCH code on Spartan-3 FPGA has been provided. The results show that our fault tolerant method has the lowest hardware overhead and it can correct any 5-bit error in any... 

Several researches have been done to identify visual system characteristics. Some of them are based on the processing of the brain signal recordings. Visual evoked potentials (VEPs) are electrical signals which are produced in response to the visual stimuli and recorded by means of electrodes placed on the head. These signals are usually characterized by the amplitude and latency of their peaks. Different types of visual stimuli and visual system characteristics can affect the shape and hence the characteristics of VEPs. In this paper, proper visual stimuli were used and VEPs were recorded in order to classify visual acuity. To achieve this goal, visual evoked potentials were recorded and... 

Several researches have been done to identify visual system characteristics. Some of them are based on the processing of the brain signal recordings. Visual evoked potentials (VEPs) are electrical signals which are produced in response to the visual stimuli and recorded by means of electrodes placed on the head. These signals are usually characterized by the amplitude and latency of their peaks. Different types of visual stimuli and visual system characteristics can affect the shape and hence the characteristics of VEPs. In this paper, proper visual stimuli were used and VEPs were recorded in order to classify visual acuity. To achieve this goal, visual evoked potentials were recorded and... 

Density currents (DCs) or gravity currents are driven by gravity in a fluid environment with density variation. Smoothed Particle Hydrodynamics (SPH) has been proved to have capabilities such as free surface modeling and accurate tracking of the immiscible-fluids interface that can be useful in the context of gravity currents. However, SPH applications to gravity currents have been limited to often-coarse simulations of high density-ratio currents. In this work, the SPH projection method is tried to solve currents with very low density-ratios (close to one), at a resolution, that captures the Kelvin-Helmholtz instabilities at the fluids interface. Existing implementations of the SPH... 

The adsorption of proteins at liquid interfaces happens at rather low bulk concentrations due to their rather high surface activity. In contrast typical surfactants start to decrease the surface tension at bulk concentration in the range of mmol/l and reach a minimum value at about two or three orders of magnitude higher concentration. The two proteins studied here, β-lactoglobulin and β-casein, adsorb already remarkably at much lower concentrations, i.e. less than 1. μmol/l. When smallest amounts of a non-ionic surfactant are added to low concentrated protein solutions, changes in the surface tension are observed which cannot be explained by the existing theoretical models. An agreement... 

The formation of condensate banking in the near well-bore region will lead to the reduction in gas relative permeability and loss of well deliverability. This loss is investigated by conducting a series of fine grid numerical compositional simulation with the gas condensate and dry gas reservoir data. Also, a method for calculation of condensate blockage skin factor is introduced in which the skin factor is calculated using dry gas and gas condensate simulation production data. The authors also found that absolute permeability and pressure drawdown of the producing well have significant influence on the well gas deliverability and condensate blockage skin factor  

Through the activation process of T cells, actin filaments move from the cell periphery toward the cell center. The moving filaments engage with T cell receptors and thus contribute to transportation of the signaling molecules. To study the connection between the moving actin filaments and T cell receptors, an experiment available in the literature has measured filaments flow velocity passing over a region of confined clusters of receptors. It shows that flow velocity decreases in the proximity of the receptors, and then regains its normal value after traversing the region, suggesting a dissipative friction-like connection. In this work, we develop a minimal theoretical model to re-examine...