Sharif Digital Repository

The distance measurement is the corner stone of the modern cosmology. They are measured via ”Doppler Effect”, accordingly the distances in cosmology are obtained in red-shift space. Despite the cosmological background expansion, the peculiar velocities due to the local density contrast distort these measurements. One of the main challenges in upcoming cosmological studies is to distinguish the peculiar velocity effect from the background expansion.Supernova Type Ia as standard candles can be think of a crucial observation to address the above problem. In this thesis, we study the effect of cosmological perturbations on distance-redshift relation of the SNIa. The corrective effects are from weak... 

The aim of this research is to analyze the failure and investigate crack growth in graphene using peridynamic theory. The presence of spatial partial derivatives in the equations of classical continuum mechanics has led to the fact that methods based on this theory are not valid in displacement discontinuities such as cracks. Peridynamic theory emerges as a nonlocal reformulation of mechanics, uniquely well-suited for modeling discontinuities and dynamic fractures in both continuous and discrete media. Its adaptability extends to various dimensions, encompassing phenomena at the nanoscale. In the present study, based on the ordinary state-based peridynamic theory, we investigated the... 

Heat transfer in porous media has recently become an important subject in mechanical engineering. Heat transfer in porous media is central in many applications involving industrial devices (chemical engineering, heat exchangers, nuclear reactor, etc...) as well as complex geological formations (in situ combustion and pyrolysis, geothermal sites, etc...). On track to achieve heat transfer methods and heat transfer coefficients of porous materials, this investigation describes the design process of fabrication and experimental analysis of calculation the conduction heat transfer coefficient of the uniform porous materials. We report on thermal conductivity measurements performed on uniform... 

DNA sequence is the lifetime private information of each individual: it can reveal personal traits, health status, and medical risk of that individual, it can be abused by entities such as insurance companies, it can be used for identity theft, etc. Unfortunately, due to cost, regulations, or some restrictions, we may not be able to complete DNA sequencing in-house and have to outsource it to some unreliable companies in some foreign countries.This would compromise the DNA privacy from the beginning. This would raise the question that how we can guarantee the DNA privacy in the process of sequencing.Here we propose a solution for private DNA sequencing by exploiting the fact that the process... 

Free-standing TiO2 nanotube array (TNA) films were fabricated via two-step anodization of titanium sheet. The electrolyte consisted of DI water and ethylene glycol (99.9%, Merck) solution with volume ratio of 10:90, containing 0.5 M NH4F. Then, a few drops of 1M H3PO4 aquaes solution have been added to adjust pH at 5.7. The anodization process was performed at optimized applied voltage of 60 V for 200 min. Indeed it does in two-step for 50 and 150 min, and samples were sonicated of 40s between two steps. Then, to crystallize the grown structures, they were annealed in air at 500˚C for 80 minutes. Surface of TNA was modified by sequential-chemical bath deposition (S-CBD) method to fabricate... 

Removing nitrogen, as one the most surface and ground water contaminant is very important and in order to achieve this aim,nitrification and denitrification are effective and economical methods. In this work, moving bed biofilm reactor (MBBR) with initial denitrification structure, adapted from modified LUDZACK-ETTINGER (MLE) method used in order to industrial wastewater treatment with COD value in range of 900-2100 mg/lit and ammonium in range of 150-430 mg/lit in 3 hydrolic retention time of 18 , 12 and 8 hours.Aerobic reactor volume is 14.4 liter and anoxic reactor volume is 7.2 liter and reflux flow amount from aerobic reactor to anoxic reactor has considered being 3 times of anoxic... 

Monitoring of activities of elderly and intelligent decisions about their living environment is a key challenge in smart environments. In the case of such challenges, correctness of system performance is highly dependent on how the model is designed. In the ambient intelligence (AMI) modeling, formal modeling is one of the best approaches because it supports certainty. In addition, time, location and mobility in AMI are crucial requirements, particularly in emergency treatment services. Ambient calculus is a formalism for describing mobility, process migration and message transfer, but it cannot express metric time duration. In this paper we propose an extension of ambient calculus with time... 

Kinetics and mechanism of 4,4-dicyano-5-ethyl-1,5-heptadiene rearrangement reaction, a pericyclic type reaction, were studied with ab initio calculations in gas and solution phases. This reaction is one of the cope rearrangement in which secondary kinetic isotope effect is observed. Theoretical study on these reactions showed that probability of radicalic mechanism is inconsiderable and reaction proceeds through out a concerted mechanism with cyclic transition state. Isotope effect was studied by replacement of H1, H2 and H4,H5 with deuterium. The isotope effect data confirmed the concerted mechanism. Solvent effects on this reaction were studied by CPCM model. Solvation energies at... 

ZnO nano particles and mordnite zeolite nano particles were prepared by precipitation method and hydrothermal method,respectively. The influence of solvent and surfactant in ZnO nano particles synthesis were studied to reform the structure of nano particles.These nano particles were based on different supports to improve and enhance their photocatalytic activities. Synthesized catalysts characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform-infra red spectra (FTIR), UV-Vis spectroscopy and BET techniques. To investigated photocatalytic activity of the synthesized catalysts under UV irradiation, they were used to degradation bio-environmental... 

Polymer flooding is a famous enhanced oil recovery method and is used to reduce mobility ratio of displacing fluid to displaced fluid by forming a stable front in displacing process. Due to high costs, polymer flooding faces economical risks and from this point of view, performance investigation of polymer flooding in laboratory scale was concerned. In this project, performance of 7 types of polymers which have different rheological properties were investigated in fractured/non-fractured carbonated and sandstone reservoirs. These polymers consists of 4 commercial polymers, one branched polymer, one synthetic polymer and one polymer composite which have different molecular weight,... 

The objective of this investigation was obtaining sound Friction Stir Welded (FSWed) Commercially Purity Titanium using suitable Tool’s Materials (for Shoulder and Pin) in order to be able to work in high temperature (>1000 ˚C) with great mechanical properties and minimum wear during process. Consequently, different materials and designs for Tool, such as High Speed Steel tool, Tungsten based tool, Tungsten Carbide (WC-Co) based tool and diverse tool geometry and designs like simple design, threaded design, fixed pin and inserted pin (adjustable pin) was used. The results demonstrated that using simple cylindrical WC-Co for pin and Tungsten for shoulder resulted in joints with the best... 

Up to now many different mechanisms have been proposed for a swimming micro robot, but most of the previously designed micro robots are not able to perform three- dimensional maneuver and the motion of the proposed swimmers are limited along a straight line or in a plane. Some important issues that must be ruled in designing micro robots include: reduced number of actuators, high maneuverability, high motion controllability and elimination of lateral drift. In this study the aim is to design a micro swimmer with the aforementioned capabilities as much as possible. In this regard, many different ideas based on the quadrotor motion, flagellated bacteria and spiral flagellated bacteria, Fish... 

Some have argued that two-way markets, such as the online rideshar-ing platforms, which divide their services into different segments and provides each of these segments to the independent workforce based on an articulate and transparent income criterion, are more attrac-tive to women, which in turn, can reduce income disparities. This is due to the flexibility in working hours as well as the transparency of the labor payment process. In this study, using micro-data related to the trips of male and female drivers of Tap30, we find out that there is a 2.2 % gender earning gap between drivers. Furthermore, the fac-tors affecting the possible income difference are identified. On the one hand,... 

Water plays an essential role in the daily lives of humans, plants, and animals. Due to the lack of safe water on the planet, in recent years there have been many challenges in the field of water treatment, which has made water desalination technology always one of the most advanced technologies. The most advanced technology in this field is the use of nanotechnology in water and wastewater treatment, especially the use of Membrane processes such as reverse osmosis. Unlike conventional reverse osmosis membranes, nanoporous membranes can ensure rapid water transfer during the displacement process. The purpose of this thesis is to introduce new monolayers that have an incredible performance in... 

In this study, three recent predictors of severity of coronary stenosis including fractional flow reserve (FFR), instantaneous wave free-ratio (iFR) and coronary flow reserve (CFR), are calculated for a number of patient-specific models of left coronary arteries. These patients are admitted to Tehran heart center. The main aim is presenting the optimum numerical and clinical detection technique to assess the severity of coronary stenosis. The effect of geometric features of stenosis is studied on the results of the FFR, iFR, and CFR in order to determine their accuracy. It is observed that CFR does not have a good estimate of the amount of disease. But, iFR, as a less risky test than FFR,...