Continuous Unitary Transformation and Quantum Phase Transition in Kondo-necklace Model

, M.Sc. Thesis Sharif University of Technology Rahimi Movassagh, Mahsa (Author) ; Langari, Abdollah (Supervisor)

Abstract

Strongly correlated electron systems are an interesting topic among condensed matter systems. The electrons in such systems are strongly correlated to each other in a way that the behavior of the systems cannot be described by single particle theories. One of the most famous of these systems are heavy fermionic materials which are called so due to heavy quasi particles mass.
This kind of materials have been investigated via different methods. The most im-portant model that can describe characteristics of these materials is Kondo lattice model. When we are only interested in magnetic properties of them, the model can be reduced to Kondo-necklace model which only involves with spin degrees...

A Comparative Approach between Deep Learning and MLE for Monitoring Multivariate Processes with Chaotic Trends

, M.Sc. Thesis Sharif University of Technology Rahimi Movassagh, Maryam (Author) ; Akhavan Niaki, Taghi (Supervisor)

Abstract

There are a variety of multivariate industrial processes in real world problems. It seems to be necessary to control them through strong tools such as control charts. One of the state-of-the-art methods to monitor processes is neural network. Neural networks are data processing systems inspired by human brain and they are capable of processing data with a variety of small processors working in parallel forming an integrated network to solve a problem. Chaotic models, one of the states of being out of control, are deterministic non-linear models which have extremely complex behavior under determined assumption. Researches have shown neural networks have excellent performance in such systems....

, M.Sc. Thesis Sharif University of Technology Boraghi, Mahsa Sadat (Author) ; Parsafar, Gholamabbas (Supervisor)

Abstract

In 2009, a general equation of state (EOS-III) based on an effective near-neighbor pair interaction of an extended Lennard-Jones (3, 6, 12) type has been introduced as : , where is the compressibility factor, p and ρ stand for pressure and molar density , respectively, T is Temperature , and e, f and g are the temperature dependent coefficient of the equation of state . the Z_th and Z_in are the thermal and internal contributions of pressure in the compressibility factor, respectively. this equation of state gives a good description of all types of nano- and bulk –solid and bulk fluid at entire temperature and pressure ranges for which thee is experimental data. Investigation show that...

Low Grade Heat Driven Multi-Effect Distillation and Desalination

, Book Rahimi, Bijan ; Chua, Hui Tong

Elsevier 2017

Abstract

Low Grade Heat Driven Multi-effect Distillation and Desalination describes the development of advanced multi-effect evaporation technologies that are driven by low grade sensible heat, including process waste heat in refineries, heat rejection from diesel generators or microturbines, and solar and geothermal energy. The technologies discussed can be applied to desalination in remote areas, purifying produced water in oil-and-gas industries, and to re-concentrate process liquor in refineries.
This book is ideal for researchers, engineering scientists, graduate students, and industrial practitioners working in the desalination, petrochemical, and mineral refining sectors, helping them...

Photoelectrocatalytic Performance of Mesoporous TiO2 Nanostructures Decorated with Cu-Ag-Zn Particles for CO2 Conversion

, M.Sc. Thesis Sharif University of Technology Adel Rastkhiz, Mahsa Sadat (Author) ; Simchi, Abdolreza (Supervisor)

Abstract

The rise in carbon dioxide levels has led to the manifestation of numerous environmental challenges. Currently, the absorption and conversion of carbon dioxide into valuable fuel resources such as synthetic gas, methane, and ethylene are deemed crucial from both environmental and economic standpoints. Despite the presentation of photocatalysts such as titanium oxide and electrocatalysts such as copper, silver, and zinc, their efficiency in CO2 conversion is found to be insufficient. One potential solution to this problem is the utilization of photoelectrocatalytic CO2 recovery. In this study, the aim was to enhance the photoelectrocatalytic reduction of CO2 by designing and manufacturing...

Role of collision angle during dissimilar Al/Cu magnetic pulse welding

, Article Science and Technology of Welding and Joining ; Volume 25, Issue 7 , 2020 , Pages 549-555 Pourabbas, M ; Abdollah Zadeh, A ; Sarvari, M ; Movassagh Alanagh, F ; Pouranvari, M ; Sharif University of Technology

Taylor and Francis Ltd 2020

Abstract

This paper investigates the influence of collision angle on the interface characteristics and mechanical properties of magnetic pulse welded AA4014 tubes/Cu rods. It is shown that the collision angle, which affects the collision velocity, plays a crucial role in controlling the thickness of intermetallic compounds (IMC) layer and defect formation at the weld interface. The creation of a thin and continuous IMC layer at the weld interface is responsible for the higher load-bearing capacity of the sample welded under a collision angle of 4°. The welds made at higher collision angles are featured by a thick IMC layer containing defects such as micro-cracks, pores and cavities, which reduced the...

Analysis and data-based reconstruction of complex nonlinear dynamical systems : using the methods of stochastic processes

, Book Rahimi Tabar, M. Reza

Springer International Publishing 2019

Abstract

This book focuses on a central question in the field of complex systems: Given a fluctuating (in time or space), uni- or multi-variant sequentially measured set of experimental data (even noisy data), how should one analyse non-parametrically the data, assess underlying trends, uncover characteristics of the fluctuations (including diffusion and jump contributions), and construct a stochastic evolution equation?
Here, the term "non-parametrically" exemplifies that all the functions and parameters of the constructed stochastic evolution equation can be determined directly from the measured data.
The book provides an overview of methods that have been developed for the analysis of...

Tipping Cascades in Complex Networks: Dynamics and Control

, M.Sc. Thesis Sharif University of Technology Shahrabi, Ali (Author) ; Rahimi Tabar, Mohammad Reza (Supervisor)

Abstract

Tipping points occur in diverse systems in various disciplines such as ecology, climate science, economy, sociology, and engineering. Critical thresholds in system parameters or state variables at which a tiny perturbation can lead to a qualitative change in the system exist in many subsystems in complex systems. These thresholds are called tipping points, and these subsystems are called tipping elements. Additionally, many systems with tipping points can be modeled as networks of coupled multistable subsystems. Domino-like tippings are called tipping cascades. Considering that these tipping cascades are primarily unprecedented, it is essential to study the dynamics and control of these...

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) Hemmatiyan, S ; 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...

Synthesis and Application of Preformed Viscoelastic Hydrogels in Enhanced Oil Recovery

, M.Sc. Thesis Sharif University of Technology Aqcheli, Farzad (Author) ; Taghikhani, Vahid (Supervisor) ; Baghban Salehi, Mahsa (Supervisor)

Abstract

Preformed particle gels (PPGs) due to its advatantage over commonly used in situ gels has been successfully applied for controlling excess water production in mature oil reservoirs. Field results of using PPGs in oil fields shows that commonly used PPGs are highly sensitive to hard reservoir conditions such as high temperature and salinity and can not effectively block fractures and high permeability layers.Objects of this study are synthesis and evaluating performance of this novel polymer based hydrogel in oil reservoirs with high temperature and salinity. Central composite design ( which is a experiment design approach) was used for synthesizing thirteen gel samples and optimal sample was...

Coating of Sewage Pipes with Appropriate Nanomaterials Aimed at Preventing Biological Growth (Algae+Biofilm)

, M.Sc. Thesis Sharif University of Technology Nezameddin, Mahsa Sadat (Author) ; Borghei, Mehdi (Supervisor) ; Ghasemi, Shahnaz (Co-Supervisor)

Abstract

Biological layers are one of the main problems related to water transfer with pipe lines which are formed through time in the inner surface of the pipes by the water nutrients. Hence, the inner surfaces in the pipe lines and water refineries should be made in order not to let these biological layers to be made. The reason is that when the biofilm is formed on these surfaces, the traversing water is polluted. Dredging of these pipes is not only necessary in most of the countries in the world and needs huge amounts of water but is also very complex and expensive.In this research, nanomaterials, namely ZnO, T〖iO〗_2،S〖iO〗_2 have been used to cover the surface of concrete and steel pipes (The...

Design and Manufacture of Polymeric Nanocomposite in Order to Control the Production and Migration of Sand in Reservoirs

, Ph.D. Dissertation Sharif University of Technology Saghandali, Farzin (Author) ; Taghikhani, Vahid (Supervisor) ; Baghban Salehi, Mahsa (Supervisor)

Abstract

Sand production from oil reservoirs leads to various problems, such as well productivity reduction, operating equipment corrosion, and increased production costs. Therefore, controlling sand production in unconsolidated reservoirs is crucial for operating companies. Chemical injection into the formation in order to strengthen and reduce sand production is one of the most important methods of sand control. In this study, a hydrogel nanocomposite was designed and its effectiveness in sand control was investigated. Various tests were carried out to define and assess its efficacy, as follows: Morphological tests demonstrated the creation of a dense, homogeneous, and porous structure. Structural...

Effects of Higher Order Interactions and Data-Driven Stability Analysis in Tipping Networks

, M.Sc. Thesis Sharif University of Technology Nikpanjeh, Fatemeh (Author) ; Rahimi Tabar, Rahimi Tabar (Supervisor)

Abstract

Recent studies in various fields such as the environment, climate, economics, and neuroscience have shown that many systems exhibit dynamic responses based on catastrophic shifts—sudden and unexpected changes in the system's state and behavior in response to environmental changes. One of the simplest cases of these shifts occurs when the dynamical bifurcation diagram of a system has a tipping point, which serves as a critical threshold for system parameters, allowing small disturbances to lead to significant changes in the system's state. Research on many natural systems has revealed that tipping elements as the subsystems of a complex system are not independent, and the tipping of one...

Capabilities, difficulties and obstacles for energy recovery from MSW’ as a sustainable option for waste management in Iran

, Article WIT Transactions on Ecology and the Environment ; Vol. 186 , 16-18 December , 2014 , pp. 789-798 ; ISSN: 17433541 ; ISBN: 9781845648374 Rahimi, E ; Sharif University of Technology

2014

Abstract

Increasing concerns about unbridled fossil fuel consumption and a growing generation of municipal solid waste (MSW) in Iran and related environmental challenges require adoption of more sustainable approaches in energy and waste management. Energy recovery from waste can play an important role to achieve environmentally sustainable development that has been defined for the country as a main policy. Iran’s growing urban population generates massive amounts of MSW that mostly end up in landfills. A population of 75 million is generating 50,000 tonnes of MSW every day that mostly are buried in landfills. Detrimental emissions from landfills and many other long-lasting environmental issues have...

Mixing performance of T, Y, and oriented Y-micromixers with spatially arranged outlet channel: evaluation with villermaux/dushman test reaction

, Article Microsystem Technologies ; 2016 , Pages 1-14 ; 09467076 (ISSN) Rahimi, M ; Azimi, N ; Parsamogadam, M. A ; Rahimi, A ; Masahy, M. M ; Sharif University of Technology

Springer Verlag 2016

Abstract

This study aims to investigate the micromixing performance of three basic types of spatial shaped micromixers. New configurations of T, Y, and oriented Y-spatial mixers were designed with change in the angles of the confluence and the outlet channel to achieve the efficient micromixing. These micromixers offer advantages that are not attainable with the typical types of these mixers. Experimental tests were carried out in the laminar flow regime and the mixing efficiency was evaluated using Villermaux/Dushman test reaction. The geometries of the channels were cylindrical with the length of 30 mm and the diameter of 800 μm. The experimental results show that the angle of outlet channel has a...

Mixing performance of T, Y, and oriented Y-micromixers with spatially arranged outlet channel: evaluation with Villermaux/Dushman test reaction

, Article Microsystem Technologies ; Volume 23, Issue 8 , 2017 , Pages 3117-3130 ; 09467076 (ISSN) Rahimi, M ; Azimi, N ; Parsamogadam, M. A ; Rahimi, A ; Masahy, M. M ; Sharif University of Technology

Springer Verlag 2017

Abstract

This study aims to investigate the micromixing performance of three basic types of spatial shaped micromixers. New configurations of T, Y, and oriented Y-spatial mixers were designed with change in the angles of the confluence and the outlet channel to achieve the efficient micromixing. These micromixers offer advantages that are not attainable with the typical types of these mixers. Experimental tests were carried out in the laminar flow regime and the mixing efficiency was evaluated using Villermaux/Dushman test reaction. The geometries of the channels were cylindrical with the length of 30 mm and the diameter of 800 μm. The experimental results show that the angle of outlet channel has a...

Performance Evaluation of Rhamnolipid & Sophorolipid Biosurfactants Capable of Wettability Change and Oil Recovery Increase

, M.Sc. Thesis Sharif University of Technology Aghaei, Sadegh (Author) ; Taghikhani, Vahid (Supervisor) ; Baghban Salehi, Mahsa (Supervisor) ; Mokhtarani, Babak (Co-Supervisor)

Abstract

As fossil fuels are still the world's most important source of energy, as well as the maturity of most of the world's oil reservoirs, there is a need for enhanced oil recovery methods to meet the world's increasing oil demands. MEOR methods are new and promising methods that are still in the research and development stage. One of the MEOR methods is the use of biosurfactants, which increase the oil recovery by two mechanisms: 1) reducing the interfacial tension between water and oil and 2) changing the wettability of the rock. In this study, the performance of two glycolipid biosurfactants, rhamnolipid and sophorolipid, in increasing oil recovery has been investigated. Initially, surface...

Investigation of the Effect of Asphaltene on the Stability of Water-oil Emulsion

, M.Sc. Thesis Sharif University of Technology Hosseini, Amir (Author) ; Taghikhani, Vahid (Supervisor) ; Baghban Salehi, Mahsa (Supervisor) ; Masihi, Mohsen (Supervisor)

Abstract

During the production of crude oil from reservoirs, the production of quantities of formation water along with this oil, causes the crude oil does not have the necessary indicators for transportation, refining and ultimately export. The presence of water and salt along with crude oil causes corrosion of refinery and transmission equipment and makes oil unfavorable in terms of economic efficiency (both for domestic use and for export). water and salt produce stable emulsion with oil that can be stable for a long time and can not be easily separated from crude oil. Therefore, separation of water and salt from crude oil is one of the most important issues in the oil industry. Breaking this...

Butanol Production from Bagasse Sugarcane Black Liquor by Native Strain and Clostridium Acetobutylicum Species

, M.Sc. Thesis Sharif University of Technology Hassani Atashgah, Milad (Author) ; Shayegan, Jalaleddin (Supervisor) ; Vossoughi, Manouchehr (Supervisor) ; Sedighi, Mahsa (Co-Supervisor)

Abstract

Considering the limitations of fossil fuels in recent years, as well as increasing demand for biofuels, it is anticipated that future attention to biofuels will increase further. Among biofuels, due to some disadvantages of bioethanol and biodiesel fuel, there is a tendency to use biobutanol, which does not have the disadvantages of the mentioned fuels. The cost of chemical production of butanol also led researchers to use biotechnology production of butanol. According to studies, butanol production can be achieved by fermenting some sugars such as glucose, xylose, and ... by anaerobic microorganism, but the cost of using these sugars has resulted in the use of natural sources of these...

Providing A New Solution to Enhance Oil Recovery (Eor) by Using Properties of Imidazolium Ionic Liquids and Synthesis of Microgels

, M.Sc. Thesis Sharif University of Technology Harighi, Hooman (Author) ; Taghikhani, Vahid (Supervisor) ; Baghban Salehi, Mahsa (Supervisor) ; Mokhtarani, Babak (Co-Supervisor)

Abstract

The methods of Enhanced Oil Recovery (EOR) from reservoirs have been taken into consideration recently due to the decline in oil reserves and the rise in energy demand. Studies and investigations indicate the tremendous potential of chemical approaches based on injecting ionic liquids into the porous media with the goal of improving oil recovery. Additionally, hydrogels and polymers, which are two of the process' primary materials, are thought to be good alternatives. In the current study, a hydrogel based on carboxymethyl cellulose was first created and synthesized. Ionic liquids based on imidazolium and triflate anion were then added, and their effectiveness in enhancing the properties...