Sharif Digital Repository

Solid fuel ignition transient in dump combustor geometry is numerically studied. The objective of this work is to gain insight into the ignition of the fuel and its controlling parameters in back-step turbulent flow. The system of governing equations is solved with a finite volume approach using a structured grid in which the AUSM+ scheme is used to calculate the gas phase convective fluxes. The Spalart-Allmaras turbulence model is used in these simulations. First, the auto-ignition of solid fuel subject to an inlet oxidizer flow at elevated temperatures is considered and distinct intervals in ignition delay time are studied. We have demonstrated that for inlet oxidizer streams with high... 

In this manuscript we used the method of coset construction to describe theories of spontaneous symmetry breaking. The mathematical details are included in chapter 2. The utility of the method is that without any knowledge of the UV part of a theory we can construct IR part by just knowing the symmetry breaking pattern. We used the method for some symmetry breaking patterns to construct general relativity, massive gravity and also some symmetry breaking patterns corresponding to conformal gravity  

The system considered on this structure is for the design on mid-high Buildings from 15 and 20 floors above the base level and n floors below the base level and the limitation of the number of floors is due to the computer facility and restrictions. There is going to be an irregularity in some chosen floor at lower-floor, mid-floor, or upper-floor which is assuming one floor from the structure to have a different height with respect to the others. The height of the considered floor is going to increase up to 25% with respect to the other floors and the design of outriggers with these three assumptions is going to be assessed separately. In this system, a central core of steel is constructed... 

Today, telecommunication links transmit information wirelessly at high rates; The transmission channel is not ideal and the transmitted signal undergoes changes in the channel and then reaches the receiver; Also, the processing blocks in the transmitter and receiver are not completely similar and ideal; These two factors make it difficult for the receiver to recover the transmitted information and actually receives a signal that bears little resemblance to the transmitted signal. The most important effect that the channel has on the transmitted signal is due to the multi-path of the channel between the transmitter and the receiver, which causes a signal to reach the receiver through the... 

In recent years, after the emergence of the benefits of optical wire communication, which successfully replaced electromagnetic technologies in some applications. Attention to wireless optical communication technologies has also increased. These technologies will also find their place in telecommunication systems after maturing according to the specific characteristics of light in the coming years. This thesis is a report on the implementation of a LiFi system, which aims to create a wireless local area network based on optical communication. Previously, reports have been written about the implementation of this system, but in this thesis, for the first time, the implementation of hardware... 

This thesis addresses cuff-less blood pressure (BP) estimation, for systolic blood pressure (SBP) and diastolic blood pressure (DBP) estimation with the aid of the processing of vital signals. Both with and without calibration per person approaches for BP estimation are considered. A data acquisition hardware is designed for high-resolution sampling of phonocardiogram (PCG), Photoplethysmogram (PPG) and electrocardiogram (ECG). Using these signals, pulse transit time (PTT) and pulse arrival time (PAT) indexes, which would be used for BP estimation with calibration, are extracted. For the BP estimator model using the calibration, A nonlinear model based on PTT or PAT, via modeling the vessels... 

In most real combustion systems, flow is turbulent (e.g., diesel engines). Therefore, a reliable turbulence modeling approach is necessary to design and analyze a system with turbulent flow. Direct numerical simulation (DNS), Large eddy simulation (LES), and Reynolds-averaged Navier-Stokes (RANS) are the three most mature Computational fluid dynamics (CFD) methods for turbulent flow simulations. Because of LES’s good accuracy and acceptable computational cost. In this project, LES is chosen to simulate the turbulent flow field.Modeled turbulence subgrid scales' interaction with nonlinear flow parameters, needs modeling. In supercritical and transcritical conditions, Equation-of-state is a... 

The purpose of this study is to simulate a turbulent premixed flame with the help of the Laminar Flamelet Decomposition method. Numerical simulation is considered the main approach for studying this flame. A Bunsen-type premixed burner, which has a novel approach to making different levels of turbulence, has been used for modeling the premixed flame. To reduce the cost of numerical calculations, the Reynolds-averaged Navier-Stokes approach has been chosen for the CFD simulation. In this study, the Laminar Flamelet Decomposition model is the main combustion model for analyzing the turbulent premixed flame and with this method, the rate of reactions for all the reaction species will be... 

An a priori analysis is performed to assess the performances of Laminar Flamelet Decomposition (LFD) and Conditional Source-term Estimation (CSE) methods in predicting conditional and unconditional filtered production rates and mass fractions for turbulent premixed flames over a wide range of Karlovitz numbers, which is an indicator for the level of turbulence-chemistry interaction in premixed combustion.In LFD, it is assumed that a turbulent flame is composed of strained laminar flamelets. By presuming the functional form of the probability density function (PDF) of the progress variable and inverting the integral equation for the unconditional filtered mass fractions of one of the species,... 

The first part of this thesis describes the synthesis and characterization of several Mn, Fe and Mo complexes containing tridentate Schiff base and oxazoline ligands and their reactivities as catalysts in the oxidation of organic compounds like olefins and sulfides, as well. The crystal structures of newly prepared cis-dioxo-bis[2-(2′-hydroxyphenyl)-oxazolinato]molybdenum(VI), cis-[MoO2(phox)2] and (N-hydroxyphenyl-salicylidenamine)(acetylacetonato)ethanol iron(III), [FeIII(N-OPh-sal)(acac)EtOH] complexes have been described by X-ray crystallography. Due to the difficulties in the preparation of suitable single crystals of novel... 

This research introduces temperature measurement by a non-intrusive pyrometric method of the ratio of two colors of soot. For pyrometry, the spectral sensitivity of the Nikon D7100 camera was obtained by developing a neural network based on the results of photographing colored papers and their spectrum, and this camera was used for temperature measurement. Based on the dependence of soot radiation on temperature and the spectral sensitivity of the camera, a calibration chart has been extracted on the ratio of the green channel to the red channel of the camera with the soot temperature, which is used to produce the temperature contour using the flame image. The temperature contour of...