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hemmatiyan--shayan
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Quantum Phase Transition in Kondo-Necklace Model: Concurrence Measure Within Perturbative Continuous Unitary Transformation Formalism
, M.Sc. Thesis Sharif University of Technology ; Langari, Abdollah (Supervisor)
Abstract
In this thesis, we consider the Kondo-necklace model to investigate the quantum phase transition between the Kondo-singlet and antiferromagnetic phases. There is no exact solution for this model. We would like to study the quantum critical behaviour of this model on one, two and three dimensional spaces in addition to ladder geometry. In this respect, we looked for a proper method which can give us some information for our model on any spaces mentioned above. Therefore, we implemented the perturbation continuous unitary transformation (PCUT) for the Kondo-necklace model. By using this method, we can not only calculate the ground state energy for 1, 2, 3 dimension and n-leg ladder...
Techno-Economic Comparison of Different Gas Turbine Inlet Cooling Techniques
, M.Sc. Thesis Sharif University of Technology ; Hakkaki Fard, Ali (Supervisor)
Abstract
Inlet air cooling is a simple and economical method to increase the power output of gas turbines. High-pressure fogging systems and mechanical chillers are two common methods. High water consumption, damage to compressor blades by water droplets, and inefficiency in humid climates are disadvantages of high-pressure fogging systems. Mechanical chillers have high electricity consumption and initial costs. In this research, an earth-to-air heat exchanger (EAHE) is introduced as a new method for inlet air cooling of gas turbines and is technically and economically compared with the two common methods in the long term in the climate of Tehran city. Temperature distribution in the ground is...
Aerodynamic Design of 100 kW Transonic Ducted Fan
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
The purpose of this research is the aerodynamic design of a 100 kW transonic ducted fan. Today, the aviation industry is moving towards the design of electric driven aircraft propulsion. Transonic ducted fans are one of the viable options that have been used in medium and heavy aircrafts due to their high specific power. In this research, the meanline model has been used for the initial design. By applying the design constraints, design limitations, design and functional parameters, the initial design point is found and then a sensitivity analysis is performed with respect to the effective design parameters to obtain the optimal design point. For the initial design of the transonic ducted...
Design and Optimization of Carbon Capture System from Exhaust Gases in the Process Industries
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Seif, Shayan (Co-Supervisor)
Abstract
Carbon dioxide is one of the main geenhouse gases emitted from factories as well as transportation vehicles that adversely affect the atmosphere and cause global warming. Among the proposed solutions to reduce carbon dioxide in the atmosphere, carbon dioxide separation would be the most viable medium-term approach. However, the high cost of carbon dioxide separation prevents the development of carbon dioxide absorption technologies. Therefore, it seems that integrating separation and production processes is the most efficient way to save energy and reduce carbon emissions. This method decrease a high proportion of the energy consumption in upstream operations (carbon dioxide removal,...
Quantum phase transitions in the Kondo-necklace model: Perturbative continuous unitary transformation approach
, Article Journal of Physics Condensed Matter ; Volume 27, Issue 15 , March , 2015 ; 09538984 (ISSN) ; Rahimi Movassagh, M ; Ghassemi, N ; Kargarian, M ; Rezakhani, A. T ; Langari, A ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
The Kondo-necklace model can describe magnetic low-energy limit of strongly correlated heavy fermion materials. There exist multiple energy scales in this model corresponding to each phase of the system. Here, we study quantum phase transition between the Kondo-singlet phase and the antiferromagnetic long-range ordered phase, and show the effect of anisotropies in terms of quantum information properties and vanishing energy gap. We employ the 'perturbative continuous unitary transformations' approach to calculate the energy gap and spin-spin correlations for the model in the thermodynamic limit of one, two, and three spatial dimensions as well as for spin ladders. In particular, we show that...