Abstract: A magnetohydrodynamic mixed convective flow in a
cavity was studied in this paper. The lower surface of cavity was
heated from below whereas other walls of the cavity were thermally
isolated. The governing two-dimensional flow equations have been
solved by using finite volume code. The effects of magnetic field
were studied on flow and temperature field and heat transfer
performance at a wide range of parameters, Such as Hartmann
(0≤Ha≤100) and Reynolds (1≤Re≤100) numbers. The results showed
that as Hartman number increases the Nusselt number, representing
heat transfer from the cavity decreases.
Abstract: In our modern society electricity is vital to our health,
safety, comfort and well-being. While our daily use of electricity is
often taken for granted, public concern has arisen about potential
adverse health effects from electric and magnetic – electromagnetic –
fields (EMFs) produced by our use of electricity.
This paper aims to compare between the measured magnetic field
values and the simulated models for the indoor medium to low
voltage (MV/LV) distribution substations.
To calculate the magnetic flux density in the substations,
interactive software SUBCALC is used which is based on closed
form solution of the Biot-Savart law with 3D conductor model.
The comparison between the measured values and the simulated
models was acceptable. However there were some discrepancies, as
expected, may be due to the current variation during measurements.
Abstract: A nonlinear model of two-beam free-electron laser
(FEL) in the absence of slippage is presented. The two beams are
assumed to be cold with different energies and the fundamental
resonance of the higher energy beam is at the third harmonic of lower
energy beam. By using Maxwell-s equations and full Lorentz force
equations of motion for the electron beams, coupled differential
equations are derived and solved numerically by the fourth order
Runge–Kutta method. In this method a considerable growth of third
harmonic electromagnetic field in the XUV and X-ray regions is
predicted.
Abstract: The effect of magnetic field on germination
characteristics of two wheat Seeds has been studied under laboratory
conditions. Seeds were magnetically exposed to magnetic field
strengths, 125 or 250mT for different periods of time. Mean
germination time and the time required to obtain 10, 25, 50, 75 and
90%of seeds to germinate were calculated. The germination time for
each treatment were in general, higher than corresponding control
values, in the other word in treated seeds time required for mean seed
germination time increased nearly 3 hours in compared non treated
control seeds. T10 for doses D5, D6, D11 and D12 significantly higher
than the control values for both cultivars. Mean germination time
(MGT) in both cultivars significantly increased when the time of
seed exposed at magnetic field treatments increased , about 3 and 2
hour respectively for Omid and BCR cultivars.
Abstract: Numerical parametric study is conducted to study the effects of ampoule rotation on the flows and the dopant segregation in vertical bridgman (vb) crystal growth. Calculations were performed in unsteady state. The extended darcy model, which includes the time derivative and coriolis terms, has been employed in the momentum equation. It’s found that the convection, and dopant segregation can be affected significantly by ampoule rotation, and the effect is similar to that by an axial magnetic field. Ampoule rotation decreases the intensity of convection and stretches the flow cell axially. When the convection is weak, the flow can be suppressed almost completely by moderate ampoule rotation and the dopant segregation becomes diffusion-controlled. For stronger convection, the elongated flow cell by ampoule rotation may bring dopant mixing into the bulk melt reducing axial segregation at the early stage of the growth. However, if the cellular flow cannot be suppressed completely, ampoule rotation may induce larger radial segregation due to poor mixing.
Abstract: The possibility of intrinsic electromagnetic fields
within living cells and their resonant self-interaction and interaction
with ambient electromagnetic fields is suggested on the basis of a
theoretical and experimental study. It is reported that intrinsic
electromagnetic fields are produced in the form of radio-frequency
and infra-red photons within atoms (which may be coupled or
uncoupled) in cellular structures, such as the cell cytoskeleton and
plasma membrane. A model is presented for the interaction of these
photons among themselves or with atoms under a dipole-dipole
coupling, induced by single-photon or two-photon processes. This
resonance is manifested by conspicuous field amplification and it is
argued that it is possible for these resonant photons to undergo
tunnelling in the form of evanescent waves to a short range (of a few
nanometers to micrometres). This effect, suggested as a resonant
photon tunnelling mechanism in this report, may enable these fields
to act as intracellular signal communication devices and as bridges
between macromolecules or cellular structures in the cell
cytoskeleton, organelles or membrane. A brief overview of an
experimental technique and a review of some preliminary results are
presented, in the detection of these fields produced in living cell
membranes under physiological conditions.
Abstract: This paper deals with the synthesis of fuzzy state feedback controller of induction motor with optimal performance. First, the Takagi-Sugeno (T-S) fuzzy model is employed to approximate a non linear system in the synchronous d-q frame rotating with electromagnetic field-oriented. Next, a fuzzy controller is designed to stabilise the induction motor and guaranteed a minimum disturbance attenuation level for the closed-loop system. The gains of fuzzy control are obtained by solving a set of Linear Matrix Inequality (LMI). Finally, simulation results are given to demonstrate the controller-s effectiveness.
Abstract: The equations governing the flow of an electrically conducting, incompressible viscous fluid over an infinite flat plate in the presence of a magnetic field are investigated using the homotopy perturbation method (HPM) with Padé approximants (PA) and 4th order Runge–Kutta method (4RKM). Approximate analytical and numerical solutions for the velocity field and heat transfer are obtained and compared with each other, showing excellent agreement. The effects of the magnetic parameter and Prandtl number on velocity field, shear stress, temperature and heat transfer are discussed as well.
Abstract: Magnetic carbon nanotubes composites were obtained
by filling carbon nanotubes with paramagnetic iron oxide particles.
Detailed investigation of magnetic behaviour of resulting composites
was done at different temperatures. Measurements indicate that these
functionalized nanotubes are superparamagnetic at room temperature;
however, no superparamagnetism was observed at 125 K and 80 K.
The blocking temperature TB was estimated at 145 K. These magnetic
carbon nanotubes have the potential of being used in a wide range of
applications, in particular, the production of nanofluids, which can be
controlled and steered by appropriate magnetic fields.
Abstract: The aim of this paper is to investigate twodimensional unsteady flow of a viscous incompressible fluid about stagnation point on permeable stretching sheet in presence of time dependent free stream velocity. Fluid is considered in the influence of transverse magnetic field in the presence of radiation effect. Rosseland approximation is use to model the radiative heat transfer. Using time-dependent stream function, partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations. Numerical solutions of these equations are obtained by using Runge-Kutta Fehlberg method with the help of Newton-Raphson shooting technique. In the present work the effect of unsteadiness parameter, magnetic field parameter, radiation parameter, stretching parameter and the Prandtl number on flow and heat transfer characteristics have been discussed. Skin-friction coefficient and Nusselt number at the sheet are computed and discussed. The results reported in the paper are in good agreement with published work in literature by other researchers.
Abstract: For investigations of electromagnetic field
distributions in biological structures by Finite Element Method
(FEM), a method for automatic 3D model building of human
anatomical objects is developed. Models are made by meshed
structures and specific electromagnetic material properties for each
tissue type. Mesh is built according to specific FEM criteria for
achieving good solution accuracy. Several FEM models of
anatomical objects are built. Formulation using magnetic vector
potential and scalar electric potential (A-V, A) is used for modeling
of electromagnetic fields in human tissue objects. The developed
models are suitable for investigations of electromagnetic field
distributions in human tissues exposed in external fields during
magnetic stimulation, defibrillation, impedance tomography etc.
Abstract: In this research, a 2-D computational analysis of
steady state free convection in a rectangular enclosure filled with an
electrically conducting fluid under Effect of Magnetic Field has been
performed. The governing equations (mass, momentum, and energy)
are formulated and solved by a finite volume method (FVM)
subjected to different boundary conditions. A parametric study has
been conducted to consider the influence of Grashof number (Gr),
Prantdl number (Pr) and the orientation of magnetic field on the flow
and heat transfer characteristics. It is observed that Nusselt number
(Nu) and heat flux will increase with increasing Grashof and Prandtl
numbers and decreasing the slope of the orientation of magnetic field.
Abstract: Cardiac pulse-related artifacts in the EEG recorded
simultaneously with fMRI are complex and highly variable. Their
effective removal is an unsolved problem. Our aim is to develop an
adaptive removal algorithm based on the matching pursuit (MP)
technique and to compare it to established methods using a visual
evoked potential (VEP). We recorded the VEP inside the static
magnetic field of an MR scanner (with artifacts) as well as in an
electrically shielded room (artifact free). The MP-based artifact
removal outperformed average artifact subtraction (AAS) and
optimal basis set removal (OBS) in terms of restoring the EEG field
map topography of the VEP. Subsequently, a dipole model was fitted
to the VEP under each condition using a realistic boundary element
head model. The source location of the VEP recorded inside the MR
scanner was closest to that of the artifact free VEP after cleaning
with the MP-based algorithm as well as with AAS. While none of the
tested algorithms offered complete removal, MP showed promising
results due to its ability to adapt to variations of latency, frequency
and amplitude of individual artifact occurrences while still utilizing a
common template.
Abstract: When a lightning strike falls near an overhead power
line, the intense electromagnetic field radiated by the current of the
lightning return stroke coupled with power lines and there induced
transient overvoltages, which can cause a back-flashover in electrical
network. The indirect lightning represents a major danger owing to
the fact that it is more frequent than that which results from the direct
strikes.
In this paper we present an analysis of the electromagnetic
coupling between an external electromagnetic field generated by the
lightning and an electrical overhead lines, so we give an important
and original contribution: We are based on our experimental
measurements which we carried in the high voltage laboratories of
EPFL in Switzerland during the last trimester of 2005, on the recent
works of other authors and with our mathematical improvement a
new particular analytical expression of the electromagnetic field
generated by the lightning return stroke was developed and presented
in this paper. The results obtained by this new electromagnetic field
formulation were compared with experimental results and give a
reasonable approach.
Abstract: Electric impedance imaging is a method of
reconstructing spatial distribution of electrical conductivity inside a
subject. In this paper, a new method of electrical impedance imaging
using eddy current is proposed. The eddy current distribution in the
body depends on the conductivity distribution and the magnetic field
pattern. By changing the position of magnetic core, a set of voltage
differences is measured with a pair of electrodes. This set of voltage
differences is used in image reconstruction of conductivity
distribution. The least square error minimization method is used as a
reconstruction algorithm. The back projection algorithm is used to
get two dimensional images. Based on this principle, a measurement
system is developed and some model experiments were performed
with a saline filled phantom. The shape of each model in the
reconstructed image is similar to the corresponding model,
respectively. From the results of these experiments, it is confirmed
that the proposed method is applicable in the realization of electrical
imaging.
Abstract: The line sleeves on power transmission line connects
two conductors while the transmission line is constructing. However,
the line sleeves sometimes cause transmission line break down,
because the line sleeves are deteriorated and decayed by acid rain.
When the transmission line is broken, the economical loss is huge.
Therefore the line sleeves on power transmission lines should be
inspected periodically to prevent power failure. In this paper, Korea
Electric Power Research Institute reviewed several robots to inspect
line status and proposes a robot to inspect line sleeve by measuring
magnetic field on line sleeve. The developed inspection tool can
reliable to move along transmission line and overcome several
obstacles on transmission line. The developed system is also applied
on power transmission line and verified the efficiency of the robot.
Abstract: The effect of a uniform magnetic field on the
formation of drops of specific size has been investigated numerically
in a T-shaped microchannel. Previous researches indicated that the
drop sizes of secondary stream decreases, with increasing main
stream flow rate and decreasing interfacial tension. In the present
study the effect of a uniform magnetic field on the main stream is
considered, and it is proposed that by increasing the Hartmann
number, the size of the drops of the secondary stream will be
decreased.
Abstract: Staphylococcus aureus, one of the microflora in a
human external auditory canal (EAC) is frequently exposed to highfrequency
electromagnetic field (HF-EMF) generated by mobile
phones. It is normally non-pathogenic but in certain circumstances, it
can cause infections. This study investigates the changes in the
physiology of S. aureus when exposed to HF-EMF of a mobile
phone. Exponentially grown S. aureus were exposed to two
conditions of EMF irradiation (standby-mode and on-call mode) at
four durations; 15, 30, 45 and 60 min. Changes in the viability and
biofilm production of the S. aureus were compared between the two
conditions of exposure. EMF from the standby-mode has enhanced
the growth of S. aureus but during on-call, the growth was
suppressed. No significant difference in the amount of biofilm
produced in both modes of exposure was observed. Thus, HF-EMF
of mobile phone affects the viability of S. aureus but not its ability to
produce biofilm.
Abstract: A fundamental model consisting of charged particles
moving in free space exposed to alternating and direct current (ACDC)
electromagnetic fields is analyzed. Effects of charged particles
initial position and initial velocity to cyclotron resonance frequency
are observed. Strong effects are observed revealing that effects of
electric and magnetic fields on a charged particle in free space
varies with the initial conditions. This indicates the frequency where
maximum displacement occur can be changed. At this frequency
the amplitude of oscillation of the particle displacement becomes
unbounded.
Abstract: This work offers a study of new simple compact model
of dual-drain Magnetic Field Effect Transistor (MAGFET) including
geometrical effects and biasing dependency. An explanation of the
sensitivity is investigated, involving carrier deflection as the dominant
operating principle. Finally, model verification with simulation results
is introduced to ensure that acceptable error of 2% is achieved.