Sharif Digital Repository

In this investigation Magneto Mercury Reciprocating Micrpump (MMRM) the combination of Magneto-Hydrodynamic and Reciprocating micropumps has been analyzed. To achieve the analytical and numerical solution of one-tank and three-tank MMRM, the momentum, continuity, volume fraction and magnetohydrodynamic equations have been presented. The dimensionless analytical solution of one-phase and two-phase three dimensional MHD flow in the condition of using constant current and potential electrical source, has been offered.
The boundary between mercury and air has been tracked via VOF method in OpenFOAM software. VOF equation has been solved by explicit method with variable time step and maximum... 

Steel in Iran is mainly produced by EAFs. One of the most fundamental issues in the field of electric arc furnace is to foresight methods to reduce energy consumption and emissions. A model is presented in the present research work that avails itself to analysis of mass and energy recovery simultaneously. The proposed model includes three major elements: scrap pre-heating, sponge iron pre-heating and inert gases pre-heating. An important feature of this approach is to preheat sponge iron. Mathematical model for preheating scrap has been developed on the basis of CONSTEEL technology. Also the model for sponge iron and inert gases preheating has been formulated based on the literature review.... 

Direct steam generation (DSG) process using linear FRESNEL collectors has been developed widely in recent years and is one of the most promising solar technologies for thermal power generation, Industrial processes and domestic usage. In this process water as heat transfer fluid (HTF) is heated through a solar field. Continuous breakthroughs are being achieved on improvement of these collectors. A multi-phase CFD model is developed to calculate the wall temperature of linear Fresnel absorber tubes and fluid properties including temperature, velocity, and pressure. In order to design the collector field and identify the critical condition such as overheating of the absorber tubes, modeling of... 

The perpuse of this thesis is to design and fabricate a laboratory one degree of freedom stable platform under turbulences by model-based design method. To do this, different parts of the system were first modeled in the Solidworks software and then fabricated with various tools. With proper assembly of electronic and mechanical components, the original body of the system was created. Then, the controller motor with a stable platform which is attached to it was modeled and simulated in MATLAB software. Then, the parameters of the equations were calculated using standard identification tests and TCACS optimization algorithm. One of the challenges of this thesis is the malfunction of the... 

Neutron Radiography is one of the non-destructive testing methods of materials and due to its special application compared to gamma or X-ray imaging, it is highly regarded and developed in the world. A special application of neutron imaging is the imaging of materials with a low atomic number, even when coated with a material with a high atomic number. Neutron Radiography has different methods for capturing and recording images by neutrons. Among these methods, the following 7 methods can be mentioned: Neutron radiography (film), Track Etch, Digital neutron imaging, Neutron camera (DR System), Image plates (CR System), Flat panel silicon detectors (DR system) and Micro channel plates (DR... 

The Quantum Central Limit Theorem states that when you convolve a centered quantum state, the resulting sequence of states converges to a Gaussian quantum state with the same first and second moments as the original quantum state. Similar to the classical setting, there are various metrics to measure convergence in the Quantum Central Limit Theorem. In this thesis, we aim to examine this theorem under different metrics such as Quantum Relative Entropy and Trace distance, and to prove tight convergence rates for the Quantum Central Limit Theorem  

Magnetic shape memory alloys (MSMAs) are a new kind of smart materials which are great alternatives for energy harvesting systems due to some unmatched characteristics such as reversible large strain, high cycle fatigue and fast time response. In this work, an energy harvesting system using MSMA is studied. For this goal, a 3-D thermodynamic-based MSMA model is applied for predicting magnetomechanical behavior of the MSMA sample which is used in the energy harvester system. Since demagnetization effect, which has a great influence on the model’s outputs, has been neglected in the selected MSMA model, a new approach is presented for inserting demagnetization coefficients, regarding to the... 

The low female labor force participation rate in the Iranian labor market relative to the global average and even to countries that do not differ significantly from the socio-economic characteristics of our country is one of the important questions of the Iranian labor market. In this study, we seek to answer the question of whether the economic participation rate of married women will increase if the gender gaps in wages, job findings and job losses among women and men are eliminated in the Iranian labor market. To answer this question using household expenditure and income data and labor force data, we show that between the two categories of occupations, in terms of the share of women's... 

Epoxy resins are relatively brittle and have low resistance to crack propagation. It is common to add rubber particles to improve crack resistance in epoxies, although these particles may deteriorate the strength of the matrix. Different nanomaterials are used to overcome the inherent brittleness of epoxies and to keep the mechanical properties. Among them, carbon nanotubes has been attracted many attentions. Fractue behavior and mechanical properties of two kind of novel nanocomposites, i.e, epoxy/carbon nanotube and epoxy/rubber/carbon nanotube are investigated in current study. Electron microscopy investigations were done to assure the CNTs distribution and fracture mechanisms as well.... 

Wildfires are complex phenomena with many indeterminate and highly unpredictable driving factors that have remained unresolved. During the last decade, machine learning methods have successfully excelled in wildfire prediction as an alternative to traditional field research methods by elucidating the relationship between historical wildfire events and various important variables. The main purpose of this research is to evaluate the random forest machine learning approach and the logistic regression statistical approach to prepare a wildfire susceptibility map using data related to historical wildfires and effective variables in the Okanogan region in Washington province of the United States... 

Fatigue crack growth can have harmful effects on the reliability rotary machine. While an early warning to crack, can be used to extend the life of these expensive machines and increase reliability.Structural Vibration Condition Monitoring as a primary fault detection method, achieved to a lot amazing result and for this reason studies vibration behavior of cracked rotational shaft is a big issue for engineers of dynamic machine.In this research, first check the fault detection methods based on structural vibration condition monitoring, mode shape methods were extracted. Then by modeling rotational shaft in computer and creation of crack on it, fault detection quality of these methods have... 

It is important to provide an appropriate and economically method with technical and engineering considerations to stabilize excavated underground spaces. The necessity of this, especially for the construction of underground metro stations located in the cities which faces many problems, is more evident. In this research, it has been tried to introduce an optimal method according to the type of area for the construction of the underground station. In order to obtain stress and strain condition in structural elements and surface deformations due to different stages of excavating, numerical modeling in FLAC3D has been used. By examining the parameters that affect the sustainability of this... 

In the present study, the effects of increasing the value of shale gas production, either due to increased production or price increases, have been studied on economic variables such as employment, wage, property value and the number of births. In this regard, the data for each of these variables was used at the county level in the United States of America between 2000 and 2011. In order to estimate the desired effects, counties are divided into two types of boom and non-boom counties. The findings indicate that increasing natural gas production will lead to more employment and wage growth in boom counties than non-boom counties. Also, during the period of increasing production, the value of... 

Co-movement between inflation and nominal interest in response to an interest rate shock, dubbed neo-fisherianism, has been the subject of contentious debate since the advent of non-inflationary ZLB environment. We design an economic model rich with banking features to understand the economic responses to permanent and long-term interest rate shocks. We find that responses to a permanent positive interest rate shock depend on the monetary authorities’ speculation of the new long-term inflation rate, with the most probable outcome being a permanent increase in inflation. Responses to a long-term positive interest rate shock depict an increase and then decrease in inflation. We also discover... 

In this study, we aim to learn representations from microscopic cell images that effectively capture the features of drugs affecting the cells, allowing us to identify effective drugs for treating a disease. We employ two parallel learning paths using predictive and generative models. Specifically, we have achieved a predictive model on the RxRx19a dataset that, unlike previous models, is interpretable, optimized, and robust to dras- tic changes in drug properties. Additionally, we have developed the first generative model on this dataset, which not only generates high-quality images but also discovers a meaningful latent space. This latent space divides the representation into relevant... 

Influence of excavating the Tehran metro line 7 tunnel on surface settlement, stresses and deformations induced in Towhid tunnel is investigated using numerical modeling. Construction of Metro tunnel as the new one must be carried out without imposing any damage to the Towhid tunnel as the existing tunnel. Towhid tunnel is a set of twin tunnels along the Chamran highway in Tehran. The tunnels were constructed using sequential excavation method and lined with cast in place reinforced concrete; on the other side metro line 7 is being constructed using 2 EPB tunnel boring machines and lined with reinforced concrete segments. This research consists of the study of the effects of pillar width,... 

Foam injection for enhanced oil recovery is concerned by petroleum engineers because it decreases adverse effects of fingering and gravity segregation caused by the injected fluid .Obviously foam stability is an important factor in the efficiency of this process. So investigating it is an imperative. One of the ways that less studied and can improve foam stability is using of nanoparticles. In this project effect of nanoparticles on foam stability and displacement mechanism during foam flooding has been discussed.
Study consisted of two sets of experiments. In the first part, the static foam stability in the presence of silica nanoparticles has been investigated. Also influence of...