Sharif Digital Repository

According to a novel approach of National Petrochemical Company to deployment of quality concepts on petrochemical projects and effort to develop the excellence models & paragons in various fields like managing contractors of petrochemical project and plans, “Project Based Organizations Excellence Model” presented by Project Management Research and Development Center of National Petrochemical Company as a new pattern of performance improvement in this companies. Implementation of this model in organization also required many infrastructures as knowledge and wisdom, managerial concept, dynamic and process vision that appear gradually. The purpose of this thesis is the development and also... 

A356 Aluminium alloy has an abundant application in the aerospace and automobile industries. One of the most important problems of the alloy is in it’s microstructure after solidification with long dendrite grain of Aluminium.It is stated that solidied grains can be refined by electromagnetic vibration and an alternative electric feild applied simultaneously. To make electric field, electric current passed through the specimen. In order to change in microstructure, electromagnetic vibration was used. Then the effect of intensity of electromagnetic field and alternative electric current on microstructure was examined.Grain refining carried out at electric current 80A and magnetic flux of 13,... 

The comfort of occupants has been a key driver behind the adoption of smart building technologies in recent years. To achieve this goal, machine learning methods have seen significant growth, with deep reinforcement learning emerging as particularly advantageous. Unlike advanced control strategies such as model predictive control, deep reinforcement learning does not require a physical model. Instead, learning occurs through the direct interaction of an intelligent agent with the environment, without the need for predefined datasets. This approach is further strengthened by its ability to adapt to dynamic conditions and effectively operate in large state spaces. Given that heating and... 

In this thesis a computational method for the design of optimum nozzle contour with consideration for chemical reactions has been presented. This method combines the method of characteristics, CFD and an optimization algorithm to develop a nozzle suitable for a specific operational condition. First using the method of characteristics an isentropic nozzle contour is achieved. then using the FLUENT solver, this initial contour is solved for flow containing finite-rate reactions and boundary layer effects and by iterating this process combined with an optimization algorithm, an optimum nozzle is found. Properties took into consideration in this method, in addition to chemical reaction between... 

Convolutional neural networks (CNNs) are at the heart of several machine learning applications, while they suffer from computational complexity due to their large number of parameters and operations. Recently, all-optical implementation of the CNNs has achieved many attentions, however, the recently proposed optical architectures for CNNs cannot fully utilize the tremendous capabilities of optical processing, due to the required electro-optical conversions in-between successive layers. Therefore, in our first study, we proposed OP-AlexNet which has five convolutional layers and three fully connected layers. Array of 4f optical correlators is considered as the optical convolutional layer,... 

Although Machine Learning (ML) and especially Deep Learning (DL) has shown significant success in solving complex problems, recent studies have shown that ML algorithms are vulnerable to adversarial attacks. So far, ML algorithms have been designed to run in benign environments. However, the increasing use of ML algorithms in security-sensitive applications motivated adversaries to focus on their vulnerabilities. In the adversarial environment, an adversary can interfere in the training and inference processes of ML algorithms. Adversarial examples are one of the most critical vulnerabilities of ML models at the inference time. Adversarial examples are maliciously crafted inputs that cause... 

Today’s large networks, such as global enterprise networks, carry heavy network traffic from a wide range of diverse protocols. Scalable and accurate classifcation of network traffic is of the most importance to security policy enforcement of large networks. The complexity of current network traffic along with the high speed links makes traffic classification more difficult. The dynamicity of heavy network traffic have necessitated the need for traffic classification algorithms which are adaptable to new concepts. The changes in traffic characteristic over time lead to concept drift, which is an important challenge in this domain. Data stream classification methods have been introduced to... 

Considering the environmental pollution caused by the consumption of fossil fuels, replacing clean and renewable energies instead of fossil fuels has become one of the most critical issues across the world. The use of energy geostructures, especially energy piles, to exchange the heat between the superstructures and the ground is one of the approaches for taking advantage of clean energy. In order to maintain the safety and the serviceability of structures built on energy piles, it is necessary to study the effects of heat exchange between energy piles and the ground on the mechanical behavior of energy piles, as well as the effects of various parameters on the interaction between energy... 

In a solar central system plant about 40% of energy losses occurs in the heliostat field. Furtheremore, half of the investment costs for construction of the plant is related to the heliostat field. Therefore, an optimal design of the heliostat field is necessary for reduction of levelized cost of energy in solar tower power plants. In this study, in order to optimally design the heliostat field, first energy performance of the helistat field in one year is simulated. Solar power and sun’s position at each moment of the day is determined by mathematical relations. Then, loss factors in the field are modelled and heliostat field layout is designed by an algorithm. Finally, by using PSO... 

The power generation system of this type of power plants operates on the air flowing through the power plant’s chimney and colliding with the turbine blades within the chimney. When the solar collector warms the nearby air and thus expands the air by absorbing the sunlight, a difference is created in the density. Then, this difference in the density creates the phenomenon of buoyancy, making the air pass to the top of the chimney through the collector.This study simulated and optimized a solar chimney power plant. The simulation and optimization were performed based on the information of Manzanares Solar Chimney Power Plant in Spain (located in 150 km from the south of Madrid). It was... 

The issue under discussion in this paper is to optimize the fuel consumption of the Toyota Prius hybrid car. In order to solve this problem, the ADVISOR design model used by NREL in the Matlab / Simulink environment has been used. Various parts of this model are described. The optimization performed on this issue is based on the emotional controller. This controller works by simulating learning in animals based on encouraging and punishing them. With the introduction of the controller, the model and its inclusion in the fuel consumption control and its implementation have achieved good results. In the initial state and the controller in the model, the fuel consumption was 4.9 liters per 100...