Sharif Digital Repository

Determining the porosity, water saturation and permeability values in the reservoir rock, are major steps in the petroleum engineering and formation evaluation. Today in the oil industry, these parameters are obtained using Helium gas injection technique on core (Plug) samples. However, the coring operation is difficult and costly. In addition, there isn't the possibility of coring in some of wells, such as horizontal wells. In fact, the present research is the modelling of artificial neural networks to estimate permeability in one of the Iranian oil field reservoirs by using oil well logging data. In this research, MLP neural network has been used and for network training, the evolutionary... 

Reducing the size of transistors has dramatically increased the impacts of NBTI, HCI, and EM phenomena in comparison with decade ago. These phenomena are able to have influence on properties of different parts of a chip to make it changed gradually; including threshold voltage of a transistor and electrical conductivity of interconnections. These changes are known as the aging of a transistors that diminish the performance and reliability of a chip. A common reason that plays a significant role in all these phenomena is temperature. The temperature becomes more important when the power density increases per unit area due to decreased size of transistors, which is a trend in multi-core... 

Deposition of solid particles present in the process air on the walls of furnaces is one of the challenges in industries. This phenomenon has various causes. For example, in a furnace, the temperature of particles increases as they pass in front of the furnace burners, and due to the softening of the particles, their chances of deposition increase when they collide with the walls. Over time, with the growth of deposited particle layers on the combustion chamber walls, the performance of the combustion system gradually becomes impaired. present research aims to design air jets intersecting with the process air path, with the purpose of reducing the temperature of particles prone to deposition... 

In many papers, GDP is used as a measure of economic growth, which is shown to possess a nonlinear structure. The study focuses on the nonlinear Granger causality between liquidity, government spending, oil revenues and economic growth by markov-switching vector autoregressive and markov- switching Granger causality approach for the period of 1369-1397 for Iran. The empirical results from MSAI(2)-VAR(4) suggest that Oil revenues and government spending have a significant impact on economic growth in both regimes. Also, markov- switching Granger causality results are quite different from the traditional Granger causality results, that suggests the nonlinear Granger causality has more... 

The use of microelectrode arrays in neural networks has offered a wonderful opportunity for evaluating numerous properties and interactions with excitable tissues such as the brain and spinal cord in the laboratory. In neural network applications, microelectrode arrays can be utilized to analyze nerve impulses or interact with neurons. They are either used to record neural data or to stimulate spinal cord nerves. Previous research has revealed that stimulating the spinal epidural region can help restore after spinal cord injuries (SCIs), which is the key to using them in the rehabilitation of living beings, including humans. According to the international campaign for the treatment of SCI... 

In this thesis, the simulation of HEMT for high frequency applications has been explored. It has been tried to examine the changes such as: gate recess, T-shaped gate, changing the channel length and doping of buffer layer on the performance of the proposed device. Simulation results show that the best way to improve the device performance, in particular its cut-off frequency, is increase in buffer layer doping density. Because it significantly increase the saturation current, electron mobility inside the channel, the transconductance and the cut-off frequency. If we need to lower the noise, the T-shaped gate can also be used. Also, by change in doping of donor layer, amount of 1017 cm-3 is... 

With the recent considerable developments in the Internet of Things (IoT), billions of resource-constrained devices are interconnected through the internet. Monitoring this huge number of IoT devices that are heterogeneous in terms of underlying communication protocols and data format is challenging. The majority of existing IoT device monitoring solutions heavily rely on centralized architectures. Since using centralized architectures comes at the expense of trusting an authority, it has several inherent drawbacks, including vulnerability to security attacks, lack of data privacy, and unauthorized data manipulation. Hence, a new decentralized approach is crucial to remedy these drawbacks.... 

Nowadays population growth, people housing demand and urbanization tendency has increased the land and house prices. So the constructers tend to build apartments. Time consuming and heavy costs of building and renovation has made the owners to rebuild the damages of their houses in case of an accident. Time and cost are the main factors in construction which includes rebuilding. Buildings and especially apartments renovation is expensive and prolonged. So the rebuilding tendency has been noted more than ever. In this study it has been tried to control costs and time by efficient management to save the rebuilding time and money. Two kinds of questionnaire has been applied to study different... 

The multilayer coating (Zn-Ni)1/(Zn-Ni)2 is deposited from a single bath with a zincate-sulfate compound and by changing the current density. The effect of current density and the number of layers on the chemical composition, surface morphology, roughness, phase structure, and corrosion resistance of multilayer coatings respectively using atomic absorption spectroscopy, FE-SEM microscope, roughness tests, X-ray analysis, and electrochemical techniques such as Tafel polarization and impedance was investigated and compared with single-layer coatings. Because the amount of nickel in the composition of the coatings is less than 27%, in all the studied currents, the deposition is anomalous. The... 

In this study, at first the V2O5 spent catalysts were characterized. The aim was to identifying whether these catalyst may be regenerated. Then, for feasibility study of them, three methods were applied: washing, diffusion and milling the spent catalysts for their subsequent reproduction. A variety of techniques such as XRD, XRF, AAS, TPR and TPO were applied in order to identify factors contributing in vanadium pentoxide catalysts deactivation. The results showed that approximately all of pollutants caused their performance deterioration, while they still have some active phases. Then, the polluted catalysts were washed (their yield increased from 43% to 72.2%). In the underside of the... 

Deep Neural Networks (DNNs) are widely used as a promising machine learning method in different applications and come with intensive computation and storage requirements. In recent years, several pieces of prior work have proposed different accelerators to improve DNNs processing. We observe that although the state-of-the-art DNN accelerators effectively process some network layers of certain shapes, they fail to keep computation resources fully utilized for many other layers. The reason is twofold: first, the mapping algorithm is unable to employ all compute cores for processing some layer types and dimension sizes, and second, the hardware cannot perform data distribution and aggregation... 

In this study, the change in friction damper’s optimal slip load in 3-D structures due to soil-structure interaction was evaluated. Using AISC-LRFD code, an 8 story shear building has been designed considering gravitational and equivalent static lateral loads. Then, the changes in friction damper’s optimal slip load due to PGA and soil type variation were studied. In this part two PGAs and two soil types were considered. Seven strong ground motions, recorded on soil types E and D was used for each of the two soil types. After normalizing the PGAs of selected records, these records were used for dynamic time history analyses. In the next step, the soil-structure interaction effect has been...