Performance evaluation of hybrid transfer switches in grounded and ungrounded medium-voltage electrical systems

, Article CIGRE/IEEE PES International Symposium Quality and Security of Electric Power Delivery Systems, CIGRE/PES 2003, 8 October 2003 through 10 October 2003 ; 2003 , Pages 91-96 ; 2858730156 (ISBN); 9782858730155 (ISBN) Yasaman, H ; Mokhtari, H ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2003

Abstract

Application of a fast hybrid transfer switch (HTS) as a suitable tool for protection of sensitive electrical loads against power quality problems has attracted much attentions these days. In this paper, methods for desired control of a HTS which consists of a fast fault-detection method and a suitable firing and transfer strategy are proposed. Simulation results of a HTS under various operating conditions for two types of medium-voltage electrical systems, i.e. grounded (star connection) and ungrounded (delta connection) systems, with respect to total transfer time are presented. The results show the capability of the HTS and the proposed control methods in fast transferring of sensitive...

Cosmic Neutrinos at Neutrino Telescopes CP-violation, Source Properties and Beyond the Standard Model Physics

, Ph.D. Dissertation Sharif University of Technology Esmaili Taklimi, Arman (Author) ; Farzan, Yasaman (Supervisor)

Abstract

In this thesis, we studied the oscillation of neutrino flavors and the measurement of mixing parameters through the detection of cosmic neutrinos at neutrino telescopes. Most of the astrophysical explosions predict the emission of neutrino flux and kilometer-scale detectors are under construction for the observation of these neutrinos. Detection of astrophysical neutrinos opens a new window to understand the neutrino properties and also the properties of astrophysical sources.In this thesis first we review the phenomenology of neutrino flavor oscillation and characteristics of neutrino mass matrix. By introducing a new class of invariants (under general transformation of lepton fields bases)...

Dynamics of Two Coupled Neurons of Different Types of Excitability

, Ph.D. Dissertation Sharif University of Technology Yasaman, Somayeh (Author) ; Razvan, Mohammad Reza (Supervisor)

Abstract

Excitability is one of the most important characteristics of a neuron. In 1948, Hodgkin identified three different types of excitability of neurons. Excitability an all of its types can be observed in Hodgkin-Huxley model of neuronal dynamics (H-H model) as a four-dimensional system of differential equations and in at least two dimensional reductions of H-H type models. By applying the theory of dynamical systems (e.g. bifurcation theory), one can give a mathematical definition of excitability.Excitability of the neuron is equivalent to that the neuronal model is near a bifurcation through which the state of the system approaches to a stable limit cycle. In this thesis, a two-dimensional...

Global analysis of a delay SVEIR epidemiological model

, Article Iranian Journal of Science and Technology, Transaction A: Science ; Volume 37, Issue A4 , 2013 , Pages 483-489 ; 10286276 (ISSN) Farajzadeh Tehrani, N ; Razvan, M. R ; Yasaman, S ; Sharif University of Technology

2013

Abstract

This paper is concerned with global analysis of a delay SVEIR epidemiological model in a population of varying size. By using Lyapunov stability method and LaSalle's invariance principle for delay systems, we prove that when there is no endemic equilibrium, the disease free equilibrium is globally asymptotically stable, otherwise the endemic equilibrium is globally stable

Particles in the early Universe: Interface of Cosmology and Particles Massive Neutrinos and Cosmology

, M.Sc. Thesis Sharif University of Technology Rezaie, Mehdi (Author) ; Golshani, Mehdi (Supervisor) ; Farzan, Yasaman (Supervisor)

Abstract

Neutrino flavor oscillations are clear evidence of massive neutrinos. It has been for more than a decade that neutrino physics became one of active topics in the field of particle physics and various experiments started studying the flavor oscillation of neutrinos. Unfortunately, experiments studying the flavor oscillations are only sensitive to the mass square difference, and they are incapable of providing more information about the absolute mass scale of neutrinos. Additionally, sterile neutrinos having non-standard interactions are under vast investigations and studies. Determination of neutrino masses and their effective number is among the most challenging problems by which...

Molecular Dynamics Simulation of Fluid-Fluid and Solid-Fluid Interactions in Underground Hydrogen Storage

, M.Sc. Thesis Sharif University of Technology Haghighatnejad, Yasaman (Author) ; Mahani, Hassan (Supervisor) ; Ayatollahi, Shahaboddin (Supervisor) ; Pourkhiabani, Nahid (Co-Supervisor) ; Esmaeilbeig, Mohammad Amin (Co-Supervisor)

Abstract

Hydrogen is recognized as a clean energy carrier, playing a crucial role in energy transition. Subsurface formations, such as aquifers with large storage capacities, present economically viable options for hydrogen storage. However, optimizing the storage and recovery of hydrogen depends significantly on the wetting behavior of surfaces under various conditions. Determination of the wetting properties under different conditions is challenging due to experimental limitations, safety concerns, and the time required for tests, all of which can impact the efficiency of the process. For this reason, limited data are available in the published literature on the wettability of...