Sharif Digital Repository

As global temperatures are progressively rising and climate change is affecting the occurrence of droughts and floods throughout the world, the use of green and renewable energy sources, including geothermal energy, has become more prevalent to reduce the emissions of greenhouse gases and carbon dioxide in the atmosphere. To investigate the possibility of utilizing deep geothermal energy, field, experimental, and numerical studies are required. Due to the lack of field and experimental data regarding deep geothermal energy reservoirs, numerical modeling is necessary in order to evaluate their performance. Numerical analysis using a coupled thermal-hydraulic-mechanical approach was conducted... 

In this thesis, we introduce limited-sharing multi-party computation; in which there is a network of workers (processors) and a set of sources, each having access to a massive matrix as a private input. These sources aim to offload the task of computing a polynomial function of the matrices to the workers, while preserving the privacy of data. We also assume that the load of the link between each source and each worker is upper bounded by a fraction of each input. The objective is to minimize the number of workers needed to perform the computation, such that even if an arbitrary subset of t 1 workers, for some t 2 N, collude, they cannot gain any information about the input matrices. This... 

In recent years, Rheological behavior and heat transfer of nanofluid studies have been increasing considerably and results show significant progress in this area. In this study we analyze the laboratory examination of the influence of parameters of volume fraction and temperature on thermal conductivity coefficient, dynamic viscosity of new and useful nanofluid carbon nanotube in engine oil. Most of fluid comparing to solid has lower thermal conductivity coefficient therefore solid particles increase thermal conductivity coefficient. On the other hand by adding particles, the dynamic viscosity of nanofluid also increases. Since nanoparticles have high volume ratio to surface (SSA) they have... 

Machine tools are highly value-added devices. Thus, design and fabrication of these tools is essential for industrial development. Nowadays, it is preferable to manufacture products with minimum machine set-ups. So, these tools should be capable of achieving both high accuracy and fine surface finish. Manufacturing industries demands for giant components with complex yet accurate features such as sheet metal forming dies. Gantry machines are the obvious choice for manufacturing these components because of their high maneuverability. Meanwhile, their large structure has relatively low stiffness and a tendency to vibrate. Thus far, they have operated in low rotation speed and cutting depth, to... 

The constitutive modeling of heterogeneous micro-structure of solids based on multi-scale theories has become the subject of intensive research. One of the most important problem at this scale is the interfacial effects of constituents. Investigation of thermal conduction in this area leads to a phenomenon known as Inter-facial Boundary resistance. The general reasons behind this phenomenon are imperfect contact interface and changing in energy carriers properties known as Kapitza resistance. A computational homogenization of conduction tensor by considering inter-facial resistance and effective factors on it, is proposed. In order to capture discontinuous field around this area and its... 

Pulse tube refrigerator due to the relatively high efficiency, high reliability of linear compressor and the absence of moving parts in the cold area is known as one of the best options to generate up to one kW of cooling power at temperatures from 4 to 123 K. More recently, the use of the device at a temperature of about 150 K, makes use of it even outside of cryogenic temperature. The most important part of the device is regenerator, so understanding the nature of the flow and interaction of gas and solid network in the retrievers is necessary. In this study, Inertance pulse tube refrigerator (IPTR) is simulated using Ansys Fluent in two different conditions. In the first condition the... 

In local transportation service companies, there is a need for estimation of arrival times (ETA) for customers. These companies not having the sufficient number of active online users, they are not able to obtain a proper estimation for ETA from that data. However, there are some overseas companies that have the established user base, and provide access to necessary data with a service fee. It is possible to solve this problem using the data which they provide.In this thesis, the problem of learning a hidden graph for the purpose of aiding local companies is explained and different aspects of it are introduced. In order to tackle this problem, first we define the idea of vertex separators,... 

AdS/CFT correspondence is a suitable framework for studying strongly coupled gauge theories. It corresponds a strongly coupled gauge theory to a classical gravity theory with an extra dimension. Quark-gluon plasma which is produced in accelerators is strongly coupled. We use AdS/CFT correspondence to calculate Meson thermalization time by approximating the collisions by a sudden change of baryon number chemical potential. On the gravity side, this is followed with an apparent horizon formation on probe-brane which is the signal of thermalization  

The purpose of the study was four-fold: first to investigate the predictive adequacy of the Task-Induced Involvement Load Hypothesis which contends that higher-load inducing tasks yield better retention rates in incidental learning situations, second, to examine whether type of dictionary search could affect vocabulary retention, third, to investigate the effect of translation direction on retention rate, and finally to determine the most effective tasks. To meet these ends, six groups of EFL learners - all male, aging 19-25, majoring in various fields of engineering sciences were assigned to the study. Each one of the groups performed distinct tasks which were as follow: reading... 

In recent years, quantum sensing based on spin defects in solid-state materials, particularly nitrogen vacancy defects in diamond, has been a significant research topic in the field of quantum technologies. Its applications have been demonstrated in various areas such as biology, microelectronics chips, and condensed matter physics. The aim of this research is to construct a magnetic imaging microscope based on an ensemble of diamond crystals using the continuous wave optically detected magnetic resonance method (CW-ODMR). By constructing an epifluorescence microscope and simultaneously exciting the diamond sample with green light and microwave radiation, it is possible to obtain information... 

In this project the effect of rolling temperature on mechanical properties and microstructure evolution of a low carbon steel was studied. The steel was rolled up to a nominal strain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Micreohardnessand tensile tests were used to characterize the recrystallization kinetics. Optical and scanning electron microscopic examinations were carried out to evaluate the mechanical, grain size, and the kinetics of static recrystallization by the Avrami equation. The results indicated that the volume fraction of static recrystallization increases with the increase in annealing period. The Avrami exponent... 

In this dissertation we aim to survey the concepts and results concerning Total Domination Set. Consider graph G = (V;E). Let S be a subset of V . S is Total Domination Set in G if every vertex in V is adjacent to at least one vertex in S.Furthermore, we call S a k-Total Domination Set if every vertex in V is adjacent to at least k vertices in S. The size of the smallest Total Domination and k-Total Domination Set in a graph G is respectively called the Total Domination and k-Total Domination Number of G.Now, if there is a sequence of subsets of V like S = V0; V1; V2; : : : ; Vl = V so that for each i, every vertex in Vi is connected to at least k vertices in Vi1, S is a Dynamical k-Total... 

Hydraulic fracture propagation occures in fractured saturated porous media due to fluid leakage from the crack faces and the consequent fluid pressure. In many cases, hydraulic fracturing may be considered as a detrimental phenomenon which endangers stability of human made structures like rock-fill dames. However, in recent decades the hydraulic fracturing has been an appealing method for increasing the production rate of low-permeability oil and gas reservoirs in petroleum industries.
In order to efficiently assess the behavior of saturated madia one needs to consider the coupling between the solid and fluid phases of the medium. To do so, the coupled formulation refered to as u-p... 

Lattice modeling is one of the most effective methods of simulation of crack initiation and propagation in heterogeneous materials. In this method, not only the impurities can be modeled in detail, but also micro crack initiations and crack ramifications can be observed. Lattice model simulations have shown remarkable results in both force-displacement charts and visual crack formations in heterogeneous materials, especially concrete. Simulation of mechanical behavior of concrete has always been a controversial issue in lattice modeling; and, so far, many researchers have proposed different methods. However, high computation demands, has preserved researchers from any major work on the...