Sharif Digital Repository

Token offerings, one of the new methods of financing in the blockchain industry, have provided startups with significant opportunities. In previous studies, most of the factors that determine the success of an initial offering have been examined, and operational performance has been less studied. In this study, the relationship between environmental, social, and corporate governance activities on operational performance and adoption has been presented. Previous studies have shown that more attention to environmental, social, and corporate issues leads to a higher amount of capital raised in the offering. We also address these issues among crowdfunding platforms, which attract more... 

Today in the most microwave and millimeterwave systems, one or more filters are used due to interference and noise phenomena. Microwave filters are manufactured in different environments such as waveguide, microstrip and SIW. For military and satellite applications that high power handling and low loss are in preference, the only appropriate environment is the waveguide. Other priority which is more important in satellite application is the low weight and small size of the product; Because of that, the idea of dual-mode waveguide filter was proposed in the early 70 decade. These kind of filters are able to produce two poles in one cavity resonator, which can decrease weight and size of the... 

New mathematical approaches for noise and oscillation analysis of oscillators are presented. First a new approach for computing the phase noise spectrum of microwave oscillators at every offset frequency from the carrier is introduced. This method uses the harmonic balance formulation to obtain time domain functions used in the existing time domain phase noise analysis methods to compute the phase noise spectrum. In spite of the large signal nature of the phase noise in oscillators, it is analytically proved that for the purpose of phase noise calculations for moderate offset frequencies, the phase noise process can be considered as a small signal stationary process. By this consideration, a... 

Shoreline monitoring and predicting has a very important role for policymakers and managers of coastal areas in future planning and achieving sustainable development. In this regard, to monitor the shorelines and predict its changes, a study has been conducted considering the effect of tides. In this study, the shoreline obtained from satellite images has been modified by using slope maps, slope direction and tidal data. Then these lines were monitored using the Digital Shoreline Analysis System (DSAS) and finally Bruun's rule along with the RCP scenario was used to predict changes in the shoreline. In this research, the coastlines of Bushehr Province in the Persian Gulf have been selected... 

Accurate modeling of clutter and detection of low observable targets within clutter are the major problems in radar signal processing applications. Recently, fractal geometry is applied to the analysis of high range resolution radar sea clutters. The intrinsic difference in the fractal dimension between sea clutter and the echoes from targets is extracted and used to detect targets. The box-counting method is widely used to estimate fractal dimension but it has some drawbacks never or rarely considered in literature. We explain the drawbacks and propose a new fractal dimension based detector to increase detection performance in comparison with traditional detectors. Both statistically... 

The synthetic aperture radar (SAR) is a microwave imaging radar that achieves high resolution while taking advantage of pulse compression technology and the Doppler effect. In typical radar systems, in order to obtain a good azimuth resolution, one should use an antenna with big aperture. However this is not possible in many cases. SAR has overcome this problem by moving the antenna and so making a synthetic aperture. In inverse SAR (ISAR) the radar antenna is static and synthetic aperture is created by the movement of target. Typical SAR imaging aims at the static targets and when the target is moving, it does not operate well. When detecting moving targets by SAR, both radar and target are... 

Shallow geothermal energy is a renewable and sustainable form of energy that has the potential to help alleviate the growing climate and energy crisis. The most common system used to extract shallow geothermal energy is the ground source heat pump (GSHP) system. The concept of using underground structures in exploiting shallow geothermal energy for space heating and cooling has received increasing attention. This study focuses on the use of geothermal tunnels as a means of extracting shallow geothermal energy.This research examines the effects of different heat transfer mechanisms, and highlights the effects of this phenomenon by focusing on the effects of natural convection around the... 

This study aims to propose a new correlation between in-situ horizontal stress and cone tip resistance in soils. Knowing the field in-situ stress state condition has an important role in stability assessment and stress-deformation analysis in a common geotechnical system. Although vertical stress could be measured easily, horizontal stress is still known as challenging work. Due to the difficulty in sampling undisturbed sand specimens, in-situ tests have been proposed in the previous literature to investigate the different characteristics of this soil. Cone Penetration Test (CPT) is one of the most used and accepted soil methods for soil investigation, identifying different soil parameters... 

This thesis presents turbulent partially premixed combustion modeling behind a bluff-body by using the Flamelet Generated Manifold. The objective of the present work is to develop a 4D FGM program to simulate partially premixed combustion at a reasonable computational cost. Pre-tabulated data of this manifold is obtained by using a correlated joint PDF. An in-house code is developed to build a pre-tabulated library in conjunction with a correlated PDF. Also, an exclusive OpenFOAM solver is created by employing the PIMPLE algorithm. This solver provides the link of the computational domain with the pre-tabulated chemistry. This program is used to simulate Cambridge-Sandia stratified burner... 

While Cloud providers face problems during providing services to their clients, such as lack of resources or increasing idle resources in low workload; they can share their resources with other providers by participating in Cloud Federations, and take advantage of Cloud Computing benefits like high scalability and resource extension. Moreover collaborating Cloud Federations expands Geographical area of providers. The Resource Allocation Problem has been considered in many researches, but in fields like Cloud environment and Federated Clouds it comes with complications. This thesis analyzes an optimized mechanism based on game theoretic approach for Resource Allocation Problem in Federated... 

In recent years, with the growth of industrial societies, the amount of energy consumption in the world has been increasing. On the other hand, the most consumed energy sources in the world are non-renewable energy sources. For this reason, governments and industries have invested to facilitate and make renewable energy sources cheaper. One of these renewable energies is geothermal energy, which is one of the most economical ways to use this energy, using heat exchange systems in piles and foundations. Using a heat exchange fluid, energy piles transfer the heat of the earth's surface to the ground with a lower temperature in the hot seasons of the year and use the thermal energy of the... 

In the current situation, kidney transplantation is the most appropriate and least costly treatment for patients with end-stage renal disease (ESRD). Related or altruistic living donors, as well as deceased donors, are considered as a supply source for donated kidneys. Researches have shown deceased donor kidney may not work as well as a living donor kidney because the deceased donor kidney is outside the donor's body for a longer time. If the donor has an incompatibility with the patient (in terms of the blood group, HLA, etc.), a kidney exchange between the pairs can be used to resolve the issue and make the transplantation possible. Pairs with blood group compatibility have also... 

Considering the environmental pollution caused by the consumption of fossil fuels, replacing clean and renewable energies instead of fossil fuels has become one of the most critical issues across the world. The use of energy geostructures, especially energy piles, to exchange the heat between the superstructures and the ground is one of the approaches for taking advantage of clean energy. In order to maintain the safety and the serviceability of structures built on energy piles, it is necessary to study the effects of heat exchange between energy piles and the ground on the mechanical behavior of energy piles, as well as the effects of various parameters on the interaction between energy... 

The Piezocone penetration test is a common geotechnical field test used to assess soil properties. In interpreting the CPTu field measurements, soil drainage conditions are mostly considered completely drained or undrained; however, partial drainage conditions govern such soils as silts or clayey sand mixtures. The studies show that neglecting partial drainage conditions causes soil consolidation characteristics to be underestimated. Most studies have been conducted using calibration chambers and centrifuge tests on clayey soils. Due to the complications in modeling the piezocone test, few numerical studies have been performed in partially drained conditions, especially on coarse-grained... 

There are different approaches in modifications of General Relativity as the theory of gravity. The modified theories of gravity are important cases in this context, which mostly start by modifying the Einstein-Hilbert action, while keeping the general covariance. Within the modified theories of gravity, we consider two cases. The first is the f(R) theories of gravity, and the second is curvature squared theories of gravity with an action like S = ∫d4x pg( 116GR + (R)2 + R2 +(R)2). Curvature squared theories of gravity have interesting feautures, most important of which is renormalizability, in contrast with General Relativity. But this advantage, as noted by K.S. Stelle in 1977 comes at... 

Near Horizon Extremal Geometries (NHEG), are geometries which may appear in the near horizon region of the extremal black holes. These geometries have SL(2;R)U(1)n isometry, and constitute a family of solutions to the theory under consideration. In the first part of this report,their thermodynamic properties are reviewed, and their three universal laws are derived. In addition, at the end of the first part, the role of these laws in black hole thermodynamics is presented. In the second part of this thesis, we review building their classical phase space in the Einstein-Hilbert theory. The elements in the NHEG phase space manifold are built by appropriately chosen coordinate transformations of... 

Multiverse scenario has been recently addressed by physicists and they have found it useful in many areas of physics. In this dissertation, I have treated some issues about multiverse such as the kinds of multiverses, the arguments for or against multiverse, areas in which multiverse is introduced, etc. This dissertation has six chapters and an appendix. In the chapter one, some classifications of multiverse is introduced, and also some definitions of the concept of a world is presented. Then, my classification and definition of a multiverse and a world is introduced. In the chapter two, the concept of possible worlds in philosophy and its relationship with multiverse hypothesis is examined....