Sharif Digital Repository

More than half a century has passed since the start of research on seismic liquefaction phenomenon in cohesionless soils, and various researchers has proposed different correlations for liquefaction prediction based on in situ tests. However, there still exists a great uncertainty in liquefaction prediction correlations, and liquefaction still occurs in different parts of the world. Hence, the main objective of this research is to reduce uncertainty in seismic liquefaction initiation correlations. While the technical literature indicates that soil resistance can alter due to liquefaction and shaking events and soil resistance after the liquefaction is not necessarily indicative of it prior... 

Iodine isotopes are among the most significant medical radioisotopes with a wide range of applications in therapy and diagnosis. The I-131 isotope is usually synthesized by irradiation of natural tellurium in atomic reactors. But there is an alternative route in which this isotopes is produced along with two other significant medical radioisotopes (i.e. Mo-99, Xe-131) by neutronic irradiation of uranium in the reactors. To separate iodine isotopes especially in the extraction process of fission fragments, it is necessary to be selective adsorption of iodine on a selective adsorbent. One of the most selective adsorbent for this application is copper. The aim of this study is to compare the... 

Recently, cooperative communications have gained much interest due to its ability to mitigate fading in wireless networks through achieving spatial diversity while resolving the difficulties of installing multiple antennas on small communication terminals. There have been considerable research efforts on the performance analysis of cooperative diversity. This is while most of the current works assume that perfect knowledge of the channel information is available at the destination and/or relay terminals. However, in many practical scenarios, due to the errors caused by Doppler shift or noise on the pilot signals the perfect estimation of channel coefficients is not possible. In this thesis,... 

In the present study liquid thermophysical properties in electrospray has been studied. Other parameters such as electrical configuration do not change during this study. For this purpose Alcoholic fuels have been chosen because of their high energy density and their polarity that make them suitable for electrospraying. Electrical conductivity, surface tension, viscosity, density and permittivity are the most effective liquid properties in the electrospraying. The visualization method used for this study is shadowgraphy and light scattering method. In this study the range of flow rate and voltage is acquired for each operational mode and Q-V diagram has been obtained for all liquids... 

As demand for floght has been incrased, a critical questin to pose is that is it economic to use larger Ailplanes or smaller Airplanes with higher flight frequency should be use. It is self evident that in a large Airplane the whole seats can not be accupied in all cases. Conversly, in small Airplanes, in most cases the seats are accupied but for aqual demand there most be more flights.In order to increase the number of flights, new methods should be used in such a way that smaller Airplanes live the Runway as soon as possible.In this project with modelling all effective factor regarding to Landing of a commercial FAR_23 Airplane, the Landing distance and thr erquired time for living the... 

Prediction and prevention from asphaltene deposition is an essential topic in oil production systems that can enormously increase oil production costs. Many studies have been done to understand and predict the behavior of asphaltene-containing oils. Prediction and investigation of asphaltene precipitation are required to predict the asphaltene deposition problem. Changes in temperature, pressure, and composition can cause precipitation, and these changes are inevitable during production. This dissertation compares the thermodynamic models that can simulate asphaltene precipitation. Firstly, A comprehensive review was done to extract the maximum amount of experimental data from the literature... 

Since the construction of the first models of internal combustion engines in the nineteenth century, efficiency and, since the late twentieth century, pollution and fuel consumption has been the main issue for researchers and manufacturers who have always sought to improve it. Manufacturers of internal combustion engines are required to perform numerous tests to carefully study and increase the level of technology and reliability of their products. There have been two ways for them to do this; the first way is to use the experimental method; that is, making multiple samples that require a high cost that makes it impossible. The second way is to use engine simulation software, which can be... 

This research introduces an accelerated training approach for Vanilla Physics-Informed Neural Networks (PINNs) that addresses three factors affecting the loss function: the initial weight state of the neural network, the ratio of domain to boundary points, and the loss weighting factor. The proposed method involves two phases. In the initial phase, a unique loss function is created using a subset of boundary conditions and partial differential equation terms. Furthermore, we introduce preprocessing procedures that aim to decrease the variance during initialization and choose domain points according to the initial weight state of various neural networks. The second phase resembles... 

In today’s competitive world, productivity is one of the main components that guarantee the success and profitability of an industry or a project. This research has studied productivity of dam construction projects in Iran that are usually classified as mega projects. First, the major factors influencing productivity of dam construction projects in Iran were identified and evaluated. Three main sources of information namely; literature review, records and lesson learned from previous projects and experts’ opinions were used to identify these factors. Then, 41 main factors influencing productivity were selected and the effect of each factor was measured based on the results obtained from... 

Given the increasing concerns about climate change and the depletion of fossil fuel resources, the use of renewable energy as a sustainable and environmentally friendly solution has gained significant importance. This study examines a building that utilizes solar and geothermal energy to meet its heating and cooling needs. The system is analyzed from energy, exergy, and economic perspectives. Initial system design results showed that chilled water at 7°C and hot water at 59.13°C are produced. Among the three types of collectors examined, the thermal photovoltaic collector was selected for its simultaneous electricity and heat production and optimal efficiency for combination with an... 

In the last few decades, due to population growth and lack of habitable space, the need for construction of taller buildings with more stories has become an important topic. Design of these high-rise structures include different complex tasks in which the finance of the project is the most important parameter. In order to find an efficient and financially feasible design, engineers have always been looking for new approaches and materials. One of the structural systems to be used for tall buildings is the outrigger system. In this system, the surrounding columns are connected to the central core by deep beams or walls to reduce the core forces. In other words, in this method, a new load... 

The research examines the influence of Kant’s practical philosophy on John Rawls’ theory of justice, under the concept of “autonomy”. In the initial chapter, foundational concepts of the study such as “autonomy” and “duty” are discussed in detail within the context of prevailing views in moral philosophy, particularly deontological ethics. The overarching idea of this chapter is to establish a general conceptual framework for posing the main research question. The second chapter of this research specifically and independently elucidates Kant’s practical philosophy and clarifies his interpretation of the concept of “autonomy”. The aim of structuring this chapter is to demonstrate that... 

An isopropanol supercritical reducing environment was prepared by fabricating a high temperature, high pressure autoclave, in order to make a hybridized structure of zinc oxide and graphene oxide, entitled as ZnO-G. In this novel structure, the oxygen acts as bridging element between zinc and carbon, that connects a wide band gap semiconductor to a narrow banded one. The hybridization mechanism is studied by FTIR analysis, and morphology is shown by FE-SEM. The micrographs obtained from the thin film show a stacked pile of ZnO-G disks, like a button, dispersed on a crack free layer. In addition, the crystallographic structure was revealed by comparing low angle X-ray diffraction patterns to... 

For neurodegenerative diseases like Multiple Sclerosis, Alzheimer’s, or Parkinson’s disease early detection is required to slow progression and prevent disease onset. To do so, identifying early signs and symptoms of the disease as well as modifying lifestyle can play a crucial role. Nowadays, the increasing use of smart gadgets and sensors has paved the way for collecting behavioral data and therefore analyzing and extracting meaningful patterns. In this study, lifestyle and cognitive performance data have been collected via a platform called OptiMind. Previous studies have shown that the Integrated Cognitive Assessment (ICA) can identify patients with neurodegenerative disorders (such as... 

Laser-assisted machining is nowadays considered as an alternative to conventional machining processes including ceramics grinding, which has provided the basis for extensive experimental and numerical studies in this field. Since the main difference between laser-assisted machining and conventional machining is in the presence of lasers, the main purpose of this study was to investigate the effects of laser on the laser assisted machining process. In this regard, in the first step the process of laser heating to the ceramic workpiece has been studied experimentally and numerically by finite element method. The material used in this research is a slip cast fused silica ceramic. The...