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geomagnetic-field
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A study of the effect of geomagnetic field on extensive air showers with small arrays
, Article Experimental Astronomy ; Volume 13, Issue 1 , 2002 , Pages 39-57 ; 09226435 (ISSN) ; Anvari, A ; Ghomi, M. K ; Purmohammad, D ; Samimi, J ; Rachti, M. L ; Sharif University of Technology
2002
Abstract
We have studied Extensive Air Showers (EAS) with two small arrays of 1 m2 scintillation detectors in Tehran, 1200 m above sea level. The distribution of air showers in zenith and azimuth angles has been studied and a cosn θ distribution with n = 7.2×0.2 was obtained for zenith angle distribution. An asymmetry has been observed in the azimuthal distribution of EAS of cosmic rays because of magnetic field of the Earth. Amplitudes of the first and the second harmonics of observed distribution depend on zenith angle as AI≈(0.02 + 0.35 sin2 θ)×0.02, and AII(0.03 + 0.42 sin4 θ)×0.03. Meanwhile, the uncertainties arising from the instrument, transit location of shower particles in the scintillator...
An investigation on anisotropy of cosmic rays with a small air shower array
, Article Experimental Astronomy ; Volume 15, Issue 1 , 2003 , Pages 13-27 ; 09226435 (ISSN) ; Ghomi, M. K ; Samimi, J ; Purmohammad, D ; Sharif University of Technology
2003
Abstract
We have studied anisotropy of cosmic rays with an Extensive AirShower(EAS) array in Tehran 1200 m above sea level. In analyzingthe data set, we have used appropriate techniques of analysis andconsidered environmental effects. An asymmetry has been observedin the azimuthal distribution of EAS of cosmic rays because ofmagnetic field of the Earth. © 2004 Kluwer Academic Publishers
Study of EASs inclination due to geomagnetic field by 50 TeV to 5 PeV CORSIKA simulated events
, Article 31st International Cosmic Ray Conference, ICRC 2009, Lodz, 7 July 2009 through 15 July 2009 ; 2009 ; Bahmanabadi, M ; Hedayati, H ; Sheidaei, F ; Anvari, A ; Samimi, J ; Sharif University of Technology
University of Lodz
2009
Abstract
Previously it was shown that the most important inclination of the EAS events due to geomagnetic field is the effect over the secondary particles of them and the contribution of the primary is so small [1]. These secondary particles are mostly e± and μ ±, so we limited our study over these particles. It was simulated over 520,000 EAS events with (ON) and without (OFF) geomagnetic field for our site (B0 = 28:1 μT i + 38:4 μT k, h = 1200m a.s.l.). It is observed a quite North-South anisotropy in ON events and a quite random anisotropy in OFF events. This anisotropy is comparable with the recorded results in our site (ALBORZ observatory), but the simulated anisotropy is a little more than the...
Mutual Effects between Earth's Magnetic Field and Marine Vehicles and their Modeling & Demagnetization
, M.Sc. Thesis Sharif University of Technology ; Sayyaadi, Hassan (Supervisor) ; Mehdigholi, Hamid (Supervisor)
Abstract
In the construction of naval vessels and some merchant ships, stealth to avoid detection is an important design feature. With recent advances in electromagnetic sensor technology, the war time threat to shipping posed by electromagnetically triggered mines is becoming more significant and consequently the need to understand, predict and reduce the electromagnetic signature of ships is growing.
The objective of this theoretical-practical work is to derive solutions to static ferromagnetic problems that include current-carrying coils, uniform inducing fields, and linear and homogeneous ferromagnetic bodies. The solutions obtained with the open source FEMM 4.2 software, is validated by...
The objective of this theoretical-practical work is to derive solutions to static ferromagnetic problems that include current-carrying coils, uniform inducing fields, and linear and homogeneous ferromagnetic bodies. The solutions obtained with the open source FEMM 4.2 software, is validated by...
Study on the Influence of Nanoparticle and Magnetic Field on Flow in Porous Media
,
M.Sc. Thesis
Sharif University of Technology
;
Molaei Dehkordi, Asghar
(Supervisor)
Abstract
In this thesis, the momentum and heat transfer of a ferrofluid in a partially filled vertical porous channel under the influence of nonuniform magnetic field has been investigated. In this magneto-thermo-echanical problem, our objective was to enhance the heat transfer which is attributable to both ferrofluid and porous medium unique characteristics. Accordingly, this problem is twofold and their relevant aspects would be discussed respectively. The ferrofluid flows upward, in the channel and a gradient magnetic field is generated by a permanent magnet in the vicinity of the channel. To solve the system of govering equations,COMSOL Multiphysics software has been used. The results shows that...
Robust integrated orbit and attitude estimation using geophysical data
, Article Aerospace Science and Technology ; Volume 93 , 2019 ; 12709638 (ISSN) ; Sharif University of Technology
Elsevier Masson SAS
2019
Abstract
Geophysical information such as the Earth geomagnetic field and gravity gradient (GG) data can provide a basis for autonomous concurrent orbit and attitude estimation (COAE) of satellites in low earth orbits (LEO), as magnetometers and gravity gradiometer measurements are in general functions of time, position as well as the vehicle's orientation. While gradiometer has recently been investigated just for orbit estimation (OE), the current study is focused on COAE via only utility of the GG data. To this aim, observability conditions are analyzed, where the sensitivity of the proposed COAE approach with respect to various system and roto-translational elements is also examined. Considering...
Visualization of Flow Pattern and Experimental investigation of Thermal Performance in a FerroFluid Charged Pulsating Heat Pipe
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
Nowadays, there is rapid development of practical engineeringsolutions to a multitude ofheating problems. Heat generated inmicro-devices used in manufacturing and electronics require specialsolutions. Pulsating Heat Pipes (PHPs) are novel and efficient technology in the field of heat transfer and previous researches show that using ferrofluid (magnetic nanofluid) in Pulsating Heat Pipes (PHPs) enhances the thermal performance in comparison with the case of distilled water under certain conditions by applying magnetic fields and the performance is dramatically improved at horizontal heating mode. In this research an experimental setup for visualizing two phase flows in a flat-plate Pulsating...
Experimental Investigation on Forced Convection Heat Transfer of Ferrofluids under an Alternating Magnetic Field
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
This research study presents an experimental investigation on forced convection heat transfer of an aqueous ferrofluid flow passing through a circular copper tube in the presence of a magnetic field. Both constant magnetic field and alternating magnetic field was examined. Moreover magnetic field layout and strength and modes of alternating magnetic field was investigated. The flow passes through the tube under a uniform heat flux and laminar flow conditions. The primary objective was to intensify the particle migration and disturbance of the boundary layer by utilizing the magnetic field effect on the nanoparticles for more heat transfer enhancement. Complicated convection regimes caused by...
Study on Very High Energy Cosmic Ray at Tehran Surface
, Ph.D. Dissertation Sharif University of Technology ; Samimi, Jalal (Supervisor)
Abstract
The cosmic ray astronomy was born in 1937 when Victor Hess flied with his balloon to the height of 17,500 feet. He found that the cosmic rays come from out of atmosphere. There are three fundamental questions from that time. The goal of all cosmic ray's experimental activities and related theories is finding out the answer of these questions. The first question is about the energy and composition spectrum of cosmic rays. The second one is finding the sources which can product the very high energy particles such as the protons with the energy of 1021eV found in some observatory such as AGASA and Haverah Park. The last question is the process of diffusion of cosmic rays in the galaxy. One of...
A method for determining the angular distribution of atmospheric muons using a cosmic ray telescope
, Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment ; Volume 916 , 2019 , Pages 1-7 ; 01689002 (ISSN) ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A cosmic ray telescope consisting of two scintillators (each one with a surface area of 0.14 m2, spaced 283 cm top of each other) was constructed to study the angular distribution of atmospheric muons. Using the CORSIKA code, the muons energy spectrum is parameterized in different energy regions at Tehran's altitude (1200 m above sea level ≡897 gcm−2), and by using a Monte Carlo program, the minimum energy recorded by the telescope is calculated. Due to the geomagnetic field, in the azimuth angle distribution of atmospheric muons, an anisotropy is observed in the East–West direction. The zenith angle distribution of the atmospheric muons follows the function cosnθ. Due to the relatively...
Investigation of Geomagnetic field effect on azimuth distribution of EAS events
, Article 30th International Cosmic Ray Conference, ICRC 2007, Merida, Yucatan, 3 July 2007 through 11 July 2007 ; Volume 4, Issue HE PART 1 , 2007 , Pages 11-14 ; Bahmanabadi, M ; Samimi, J ; Shadkam, A. H ; Sheydaei, F ; Anvari, A ; Sharif University of Technology
Universidad Nacional Autonoma de Mexico
2007
Abstract
EAS events are developing in the last few 10 kilometers of their path in the atmosphere. But geomagnetic field has been extended until a few thousand kilometers around the Earth. This field deflects charged particles and the deflection is different for different directions and observers. These differences depend on the amount and direction of the geomagnetic field (a dipole inside the earth) and direction of the charged particle. It was accurately investigated for 100 TeV primary particles from H0 = 20, 000 kilometers from the center of the earth (BH = 0.03 * B 0) to the ground and it was observed that the deflection is less than 10-6 degrees in azimuth angle φ. Therefore we investigated the...
A new non-linear algorithm for complete pre-flight calibration of magnetometers in the geomagnetic field domain
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 223, Issue 6 , 2009 , Pages 729-739 ; 09544100 (ISSN) ; Pourtakdoust, S. H ; Samani, M ; Sharif University of Technology
2009
Abstract
A new algorithm for complete pre-flight calibration of triple magnetometers is developed. The traditional approach for calibrating these sensors are based on a cumbersome procedure called 'swing' that involves levelling and rotating the vehicle containing the magnetometers through a series of known headings. Application of such a procedure is difficult and costly. Recently, new approaches have been developed to calibrate magnetometers without the need of attitude information. Such methods are used mostly for the calibration of biases and scale factors. Additionally in situations where misalignment errors are also to be estimated, they are usually modelled as errors of a non-orthogonal frame...