Sharif Digital Repository

Using stochastic point source and finite fault modeling, the stochastic stress drop is estimated for 52 large shallow earthquakes listed in the 'Pacific Earthquake Engineering Research Center (PEER) Next Generation Attenuation of Ground Motions (NGA)' database. The Pseudo Spectral Acceleration (PSA) of 541 accelerograms, recorded at National Earthquake Hazards Reduction Program (NEHRP) C-class sites from 52 earthquakes are simulated and compared with the PSA listed in the PEER NGA database. The magnitude of the analyzed earthquakes ranged from M4:4 to M7:6. The stress drop is calibrated by trial and error and based on the analysis of residuals where the residual is defined as the log of the... 

Displacement experiments of the gas-oil system are performed on long core scale models by varying the petrophysical properties and flowing conditions. Experiments are conducted in situations where capillary, gravity and viscous forces are comparable. From oil production history and picture analysis, the threshold for the stability is determined. The experimental findings are comparable to the results of a gradient percolation theory. The effect of destabilized front velocity on relative permeability and residual saturation is investigated. The relative permeabilities determined by using analytical and numerical approaches indicate that higher displacement velocity leads to a higher gas... 

In this study, the self-adaptive evolutionary (SaE) agent is employed to structure the contributing elements to process the management of extreme learning machine (ELM) architecture based on a logical procedure. In fact, the SaE algorithm is utilized for possibility of enhancing the performance of the ELM to estimate daily soil temperature (ST) at 6 different depths of 5, 10, 20, 30, 50 and 100 cm. In the developed SaE-ELM model, the network hidden node parameters of the ELM are optimized using SaE algorithm. The precision of the SaE-ELM is then compared with the ELM model. Daily weather data sets including minimum, maximum and average air temperatures (Tmin, Tmax and Tavg), atmospheric... 

Thermal recovery by steam injection has proven to be an effective means of recovering heavy oil. Forecasts of reservoir response to the application of steam are necessary before starting a steam drive project. Thermal numerical models are available to provide forecasts. However, these models are expensive and consume a great deal of computer time. An alternative to numerical modeling is to use a semi-analytical model. The objective of the current study was to investigate thermal applications of horizontal wells for displacement and gravity drainage processes using analytical modeling as well as reservoir simulation. The main novelties presented in the paper are: a) the transient temperature... 

In this paper, dynamic modelling and control of WindPACT 1.5 MW wind turbine in Region 2 for extracting the maximum energy from wind is investigated (where the wind velocity is greater than ‘cut in’ and below ‘rated’ wind speeds). In this region, the generator torque must regulate the rotor speed in its optimal value while the blade pitch angle is considered constant in its optimal value. To achieve a more accurate model, wind turbine is modeled as an electromechanical system with two masses dynamics. A new method based on adaptive neuro fuzzy inference system (ANFIS) is considered for wind speed estimation; where rotor speed, output power and pitch angle are inputs of such system and... 

CdS is conventionally used as the n-type buffer layer in chalcopyrite (CIG(S, Se)) and Kesterite (CZT(S, Se)) solar cells. CdS is toxic and there are wide attempts to find substitutes for it. Here, we suggest SnS2 as a possible alternative. SnS2 films were deposited by pulsed laser deposition (PLD), characterized to estimate carrier concentration and electron affinity values, and the obtained values were used to model a CZT(S, Se) solar cell. The experimental values of a benchmark CZT(S, Se) cell with efficiency of 12.3% were employed to obtain the density and energy position of defects in CZT(S, Se) and validating the model. We observed that SnS2 results in almost identical performance as... 

Efficient environmental management calls for the consideration of multiple pollutants, for which two main types of transferable discharge permit (TDP) program have been described: separate permits that manage each pollutant individually in separate markets, with each permit based on the quantity of the pollutant or its environmental effects, and weighted-sum permits that aggregate several pollutants as a single commodity to be traded in a single market. In this paper, we perform a mathematical analysis of TDP programs for multiple pollutants that jointly affect the environment (i.e., interactive pollutants) and demonstrate the practicality of this approach for cost-efficient maintenance of...