Sharif Digital Repository

The robot considered in this project is to test parts and equipment installed in marine vessels under sea movements and waves. After a thorough assessment amongst common solutions to problems of this kind, a Stewart-Gough based manipulator has been chosen so that all the requirements could be satisfied. Therefore, according to the information obtained through relevant organisations, the purpose of this project is to work on dynamics, control, and design of the structure of a 6DOF Stewart platform – based hydraulic motion simulator for heavy payloads for samples weighing up to 2.5 tons which can handle linear accelerations up to 10 m/s2, rotary accelerations up to 150 º/s2 performing at a... 

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... 

Concrete gravity dams are one of the most important infrastructures therefore their performance under seismic load is an important issue of concern for dam owners. It is necessary that these infrastructures to be able to continue their function after a disaster such as earthquake, as any damage can cause huge cost. For analysis of dams linear and nonlinear analyses are used. Because even operating loads will create cracks in the body of the dam, dam behavior can not always be considered linear. It is remarkable that these surface cracks can join together under seismic loads and this question the safety of dams. It is important to note that nonlinear analysis of concrete gravity dams is... 

Ramjets have many applications and in the speed range of Mach numbers 2 to 5 show the best performance in terms of specific fuel consumption. In many applications, including some anti-air missiles, cannon and mortars, solid fuel ramjet can be used to improve the system performance.
In this thesis, two activities are performed:
A) One dimensional simulation of the internal flow field of solid fuel ramjet by development of available softwares.
B) Optimization of design parameters of a specific ramjet motor based on the above simulation.
The main target of this thesis is simulation of internal ballistics, design and optimization of a solid fuel ramjet for a particular... 

The purpose of this project is to survey the created kind of inclusion in super alloyed based nickel. primarily, for this matter for the preparing of super alloyed based nickel, the vacuum induction melting furnace has been designed and built , then for surveying the kind of inclusion the effective parameters such as temperature , timing and material of crucible has been considered accordingly , the material of crucibles was considered based on mud-clay- graphitic- pure graphitic- aluminum- zirconium. From the obtained analysis samples of SEM has been distinguished which, with increasing of the temperature and the time ,the percentage of impurity will go up in super- alloyed and the... 

The environmental concerns in today's world, encourage the people involved in the plastic industry, along with the development of recycling culture, to produce and consume bio-based and biodegradable plastics. In this regard, during the last two decades, polylactic acid (PLA), which is a bio-based and biodegradable polymer, has experienced a high growth rate of production and is used in various applications such as packaging, textile and additive manufacturing. Along with the growth of the consumption of this polymer, the knowledge and development of its recycling methods have also been considered by researchers. Considering the expansion of the use of PLA blended with another biodegradable... 

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,... 

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... 

Recently, millimeter wave imaging (MMWI) technology is given more attention. This is as a result of three facts. First, despite the infrared or optical cameras, these systems can image a target, which is obscured by one or more optically barriers. Second, the electronics circuits in this band have seen great achievements in the current decade, which facilitate the implementation of MMWI structures. Third, there is no known health hazard for the systems operating in this band with moderate power. Therefore, in this project, a MMWI system based on compressed sensing (CS) for the concealed weapon detection application is proposed. This design consists of a linear antenna array, an appropriate... 

The burners studied in the combustion principles have different types due to the configuration of different types of flames, each of them studies a specific phenomenon of combustion, so researchers need to design burners with the ability to: create different types of combustion flow regimes, changing in mixing rate and performance at critical points are felt more and more. This document describes the process of designing and manufacturing a turbulent jet burner with variable mixing ratio and the ability to create a diverse range of flow regimes and different flame configurations. Mixing rate is the most important characteristic in the stability of premixed flames, so the distinctive feature... 

Due to the intensification of competition in real markets and the increase in customer needs, manufacturers are forced to implement value-adding techniques in their production management. Many companies begin their improvement efforts without considering the need for a comprehensive plan. As a result, their improvement efforts are not carried out in an integrated and complete manner and do not lead to complete and desirable results. The main objective of this study is to provide a framework that proposes a detailed vision of lean implementation in the machine-woven carpet industry, considering the value stream map as a tool to achieve improvement strategies in this industry. This framework... 

In this study, using a non-interference experimental method, the chemical luminosity of CH* in co-flow diffusion flames with soot and using natural gas hydrocarbon in a laminar flow regime has been investigated. In addition to experimental research, in current research, numerical simulation has been used to extract information such as temperature field, mass fraction of species, and flow structure and comparison and validation with experimental results. Numerical simulation has been used to simulate the mechanism of CH* species formation. Two different mechanisms have been used. In addition, the Soot simulation model from the Moss-Brookes model and radiation heat transfer mechanism... 

We live in the cyber era in which network-based technologies have become omnipresent. Meanwhile, threats and attacks are rapidly growing in cyberspace. Nowadays, some signature-based intrusion detection systems try to detect these malicious traffics. However, as new vulnerabilities and new zero-day attacks appear, there is a growing risk of bypassing the current intrusion detection systems. Many research studies have worked on machine learning algorithms for intrusion detection applications. Their major weakness is to consider the different aspects of network security concurrently. For example, continuous concept drift in normal and abnormal traffic, the permanent appearance of zero-day...