3 research outputs found
Evaluation of electric and magnetic fields distribution and SAR induced in 3D models of water containers by radiofrequency radiation using FDTD and FEM simulation techniques
In this study, two software packages using different numerical techniques
FEKO 6.3 with Finite-Element Method (FEM) and XFDTD 7 with Finite Difference
Time Domain Method (FDTD) were used to assess exposure of 3D models of square,
rectangular, and pyramidal shaped water containers to electromagnetic waves at
300, 900, and 2400 MHz frequencies. Using the FEM simulation technique, the
peak electric field of 25, 4.5, and 2 V/m at 300 MHz and 15.75, 1.5, and 1.75
V/m at 900 MHz were observed in pyramidal, rectangular, and square shaped 3D
container models, respectively. The FDTD simulation method confirmed a peak
electric field of 12.782, 10.907, and 10.625 V/m at 2400 MHz in the pyramidal,
square, and rectangular shaped 3D models, respectively. The study demonstrated
an exceptionally high level of electric field in the water in the two identical
pyramid shaped 3D models analyzed using the two different simulation
techniques. Both FEM and FDTD simulation techniques indicated variations in the
distribution of electric, magnetic fields, and specific absorption rate of
water stored inside the 3D container models. The study successfully
demonstrated that shape and dimensions of 3D models significantly influence the
electric and magnetic fields inside packaged materials; thus, specific
absorption rates in the stored water vary according to the shape and dimensions
of the packaging materials.Comment: 22 pages, 30 figures and 2 table
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Modelling and analysis of complex electromagnetic problems using FDTD subgridding in hybrid computational methods. Development of hybridised Method of Moments, Finite-Difference Time-Domain method and subgridded Finite-Difference Time-Domain method for precise computation of electromagnetic interaction with arbitrarily complex geometries
The main objective of this research is to model and analyse complex electromagnetic problems
by means of a new hybridised computational technique combining the frequency domain
Method of Moments (MoM), Finite-Difference Time-Domain (FDTD) method and a subgridded
Finite-Difference Time-Domain (SGFDTD) method. This facilitates a significant advance in the
ability to predict electromagnetic absorption in inhomogeneous, anisotropic and lossy dielectric
materials irradiated by geometrically intricate sources. The Method of Moments modelling
employed a two-dimensional electric surface patch integral formulation solved by independent
linear basis function methods in the circumferential and axial directions of the antenna wires. A
similar orthogonal basis function is used on the end surface and appropriate attachments with
the wire surface are employed to satisfy the requirements of current continuity. The surface
current distributions on structures which may include closely spaced parallel wires, such as
dipoles, loops and helical antennas are computed. The results are found to be stable and showed
good agreement with less comprehensive earlier work by others.
The work also investigated the interaction between overhead high voltage transmission lines and
underground utility pipelines using the FDTD technique for the whole structure, combined with
a subgridding method at points of interest, particularly the pipeline. The induced fields above
the pipeline are investigated and analysed.
FDTD is based on the solution of Maxwell¿s equations in differential form. It is very useful for
modelling complex, inhomogeneous structures. Problems arise when open-region geometries
are modelled. However, the Perfectly Matched Layer (PML) concept has been employed to
circumvent this difficulty. The establishment of edge elements has greatly improved the
performance of this method and the computational burden due to huge numbers of time steps, in
the order of tens of millions, has been eased to tens of thousands by employing quasi-static
methods.
This thesis also illustrates the principle of the equivalent surface boundary employed close to
the antenna for MoM-FDTD-SGFDTD hybridisation. It depicts the advantage of using hybrid
techniques due to their ability to analyse a system of multiple discrete regions by employing the
principle of equivalent sources to excite the coupling surfaces. The method has been applied for
modelling human body interaction with a short range RFID antenna to investigate and analyse
the near field and far field radiation pattern for which the cumulative distribution function of
antenna radiation efficiency is presented. The field distributions of the simulated structures
show reasonable and stable results at 900 MHz. This method facilitates deeper investigation of
the phenomena in the interaction between electromagnetic fields and human tissues.Ministry of Higher Education Malaysia and Universiti Tun Hussein Onn Malaysia
(UTHM
Non-Destructive Bio-Assay of Single Living Cell
For more than a decade, researchers are trying to find out practical commercial tool for particle/cell detection and characterization with portable, low cost, specific and sensitive characteristics. The advance of Micro Electro Mechanical Systems (MEMS) and microfluidic technologies opened a major challenge for a large number of researchers, industrial health and bio companies to invest their time and budget into the avenue of point of care health instruments or devices helping the early detection of cancer cells within the human blood via circulating malignant cells.
Actual existing commercial flow cytometer that detects and identifies the type and size of cells are costly, time consuming and need the assistance of highly qualified operators. Moreover, in certain research activities, micro cytometers are investigated and assessed with different detection techniques such as optical, impedance spectroscopy, electromagnetic spectroscopy and many other techniques.
The aim of this research is to investigate an innovative mechanism that enables to characterize, identify and differentiate among various living cells including malignant tumor cells through the use of the electromagnetic energy detection technique. Cells are spatially centered in a microfluidic channel through dielectrophoresis technique then detected and characterized by measuring and interpreting the RF signal transmission of the cells passing one by one through the interrogation region in the microchannel.
The outcome of this research might help the clinical end user to gain certain important information about the condition of the patient, establish personalized treatment or track the effect of a treatment. Detection and counting of tumor cells may help identification of early stages of illness and help patient with early care that may significantly cut the overall cost of cancer management