M.Phil.
http://hdl.handle.net/20.500.12228/52
2024-03-28T13:45:52ZSensitivity of Tropical Cyclone Mahasen to Physical Parameterization Schemes using Weather Research & Forecasting (WRF) model
http://hdl.handle.net/20.500.12228/470
Sensitivity of Tropical Cyclone Mahasen to Physical Parameterization Schemes using Weather Research & Forecasting (WRF) model
Debnath, Samir Kumar
In this study, the sensitivity of numerical simulations of tropical cyclone to physical
parameterizations is carried out with a view to determine the best set of physics options for
prediction of cyclones originating in the north Indian Ocean. For this purpose, the tropical
cyclone Mahasen that formed in the Bay of Bengal and crossed Bangladesh-Myanmar coast
in the month of May, 2013 has been simulated by the advanced (or state of science)
mesoscale Weather Research and Forecasting (WRF) model with the available physical
parameterizations. To determine on the prediction of track and intensity of Tropical Cyclone
Mahasen has been used single domain with latitude from 2.0450 N to 26.4800N and longitude
from 73.960 E to 97.040E. Domain has been used 12 km horizontal resolution. Different run
and different physical parameterizations have been used available in the model. The different
physical parameterizations schemes are KF, BMJ , GF, OSAS and Grell-3 for Cumulus;
YSU, MYJ, GBM, MYNN3, ACM2, MYNN2, BouLac, UW, TEMF and MRF for Planetary
Boundary Layer; WSM6, Kessler, Purdue Lin, WSM3, WSM5, Eta, Thompson, Morrison
2-mom, CAM5.1, SBU-Ylin, WDM5, WDM6, NSSL 2-mom, NSSL 2-mom-CCN, NSSL
1-mom and NSSL 1-momlfo for Microphysics; UNLS, TDS, RUC, NLS, CLM4.0 and PXS
for Land surface model; Dudhia, GSFC ARW+Chem(τ), CAM, RRTMG, New Goddard and
FLG for Short Wave Radiation; RRTM, CAM Long wave (CAM), RRTMG, New Goddard
FLG and Held-Suarez for Long Wave Radiation that have been used for the purpose to test
the Sensitivity of Tropical Cyclone Mahasen to Physical Parameterization Schemes using
Weather Research & Forecasting (WRF) model. Three parameters track, wind speed and
CSLP has been used for calculating Root Mean Square Error (RMSE) to find the best
physical made using parameterizations option with respect to observed. Finally Betts Miller
Janjic (BMJ) for Cumulus, Medium Range Forecast Model (MRF) for Planetary Boundary
Layer (PBL), WRF Single Moment 3-class simple ice scheme (WSM3) for Microphysics
(MP), Unified Noah land-Surface Model (UNLS) for Land surface model (LSM), Dudhia
(MM5) for Short Wave Radiation (SWR) and Rapid Radiative Transfer Model (RRTM) for
Long Wave Radiation (LWR) were found the best among available physics option.
This thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Philosophy in Physics, January 2018.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 107-115).
2018-01-01T00:00:00ZMultiple Correlation Between Rainfall of Post-Monsoon Season and the Different Meteorological Parameters of the Monsoon Season Over Bangladesh
http://hdl.handle.net/20.500.12228/441
Multiple Correlation Between Rainfall of Post-Monsoon Season and the Different Meteorological Parameters of the Monsoon Season Over Bangladesh
Pervin, Shaheena
In this thesis work attempt has been made to investigate the correlation between
the monthly and seasonal rainfall of post monsoon with the dry bulb and wet bulb
temperature and rainfall of different months of monsoon and the season itselt First of all
the raw data, collected &oni BMD, has been processed to obtain monthly and seasonal
average of them. Also the standard deviation in terms of months and seasons have been
computed. Using the processed data the correlation coefficients have been computed.
We have considered 30 stations all over Bangladesh under all 6 divisions during
1951 - 2000. The computations are made station wise. In this process we have analyzed
the following topics: -
Averages dry bulb temperature (DBT) and wet bulb temperature (WBT) of the month
of June, July, August and September and of monsoon season. Average rainfall of the
month of June, July, August, September, October and November and of monsoon and
post monsoon season.
• The Standard deviation of all the above mentioned cases.
• Correlation coefficients between the monthly I seasonal rainfall of post monsoon and
monthly / seasonal DBT, WBT and rainfall of monsoon season. Correlation
coefficients between the monthly / seasonal rainfall of post monsoon and monthly /
seasonal DBT & WBT, WBT & rainfall, DBT & rainfall of monsoon season. And
finally correlation coefficients between the monthly / seasonal rainfall of post
monsoon and monthly / seasonal DBT, WB'I' & rainfall of monsoon season.
From the analysis we have found that in October the amount of rainfall at
Sandwip and Patuakhali is the highest and that in the November is at Bhola and Cox's
Bazar region. In November the Standard deviation of average rainfall is comparatively
high in the southern region. We also observe that November rainfall and WBT of
monsoon months are positively correlated except northeast-southern region in July and
northeast and Bhola region in June and August of the country.
Also regression equations have been developed on considering October and
Novcmbcr rainthll as dependent variable and dry bulb temperature, wet bulb temperature
and rainfall of monsoon as independent variables. Where the correlation coefficients are
high, there these equations will be useful for the prediction purpose.
This thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Philosophy, October 2005.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 103-104).
2005-10-01T00:00:00ZEffects of Two Step Annealing on Complex Permeability of Fe-Cu-Nb-Si-B Nanocrystalline Soft Magnetic Materials
http://hdl.handle.net/20.500.12228/440
Effects of Two Step Annealing on Complex Permeability of Fe-Cu-Nb-Si-B Nanocrystalline Soft Magnetic Materials
Noor, Saroaut
The typical nanocrystalline alloy known as Finemet with the composition
Fe73.5Cu jNb3Si135B9 has been studied for the soft magnetic properties. The crystalline
phases that evolved after crystallization were studied by X-ray diffraction, crystallization
temperature by DTA and magnetic properties by VSM and impedance analyzer. The change
of magnetic properties with annealing temperature, Ta in the range 400-700°C and annealing
time 1-60 minutes have been investigated. The effect of a two-step annealing on the
permeability Fe735Cu)Nb3Si135B9 alloy has been studied.
The grain size was determined from the line broadening of the fundamental peak using
Scherrers method. Annealed at 555°C, the grain size, the solute silicon content of a-Fe(Si)
grains and the improvement in magnetic softness saturate as a function of time. As
compared to a nanocrystalline alloy obtained by conventional one-step annealing at around
the crystallization temperature, the alloy subjected to preannealing at Ta = 400°C and
subsequent high temperature annealing at Ta=555°C shows similar soft magnetic properties.
An enhancement of initial permeability with increasing annealing temperature was observed
until the annealing temperature TL = 475°C and corresponds to the amorphous relaxed
structure. An abrupt deteroriation of permeability takes place at the beginning of
crystalization beyond which permeability rises dramatically attaining a maximum value at
Ta = 555°C which is attributed to the nanometri grain size effect as a result of averaging out
of effective magnetic anisotropy by exchange interaction and decrease of magnetoelastic
energy. A sharp decrease of permeability above 580°C is assumed to be connected with
iron-boride phase at the beginning of second crystallization stage. The initial permeability
for the optimum annealed sample has been found to be 20786 as compared with 284 for its
amorphous counterpart. The behavior of very high permeability is explained on the basis of
random anisotropy model. From the temperature dependence of magnetization the Curie
temperature of the amorphous state and crystallized ferromagnetic phases like Fe(Si) and
iron-boride phases and the onset of crystallization temperatures of these phases have been
determined. Saturation magnetization measured on the amorphous and annealed samples at
different annealing temperature gradually increases with Ta and show a maximum at the
medium stage of nanocrysallization at Ta 525°C beyond which magnetization decreases.
The results are interpreted on the basis of irreversible structural relaxation as well as
enrichment of the nanograins with Si.
This thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Philosophy, March 2005.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 110-114).
2005-03-01T00:00:00ZSynthesis and Characterization of MgFe204 Ferrite Nanoensemble for Biomedical Application
http://hdl.handle.net/20.500.12228/439
Synthesis and Characterization of MgFe204 Ferrite Nanoensemble for Biomedical Application
Debnath, Nipa
Magnetic nanoparticles have drawn tremendous attraction from both
fundamental aspect as well as applications in biomedicine such as magnetic bio-separation, detection of biological entities, magnetic resonance imaging, magnetic
fluid hyperthermia and targeted drug delivery due to their fascinating magnetic
properties. Superparamagnetic nanoparticles have become the focus of this study
because their superparamagnetic, biocompatible and hydrophilic properties would be
revealed after modifying the particle surface by suitable surfactants. Considerable
research in this area has provided valuable in sites; however, suitable magnetic
materials that can be fulfill all the requirements of MRI and hyperthermia applications
are still under investigation. This thesis reports on an investigation into the synthesis, control, and stabilization of high quality magnesium ferrite nanoparticles for biomedical
application. A new understanding of the factors effecting nanoparticle growth in a coprecipitation methodology has been determined. Then the ferrimagnetic MgFe204
r nanoparticles were modified by annealed temperature from 200 to 1400°C using box
furnace. The crystal structural, mean particle size and magnetic properties of the
modified ferrimagnetic MgFe204 nanoparticles were measured to investigate the
effect of each process on the synthesized nanoparticles. The structural, morphological,
magnetic properties of these synthesized products were characterized by using X-ray
diffraction (XRD), Vibrating sample magnetometer (VSM), Mössbauer spectroscopy
and NMR analysis. XRD patterns of as-dried powder yielded single phase. No impurity peaks were detected. With the increase of annealing temperature, the width of peaks decreases which reflects the coarsening of particles. The smallest crystallite size about 3 nm was obtained for as-dried sample while the largest value 71.86 nm was obtained from the highest studied temperature 1400°C. The crystallite size of the nanoparticles abruptly increased with the annealing temperature. Magnetization measurements have been accomplished by VSM. It was found that saturation magnetization increases with the increase particle size. The small particles first exhibit superparamagnetic behavior at
the early stage and then transform to ferromagnetic behavior when particle size passes
the superparamagnetic limit. Interesting experimental results on the size dependent
magnetic properties at different temperatures have been found. Other structural and
magnetic properties such as chemical isomer shift, quadruple splitting and hyperfine
IL field were determined by Mössbauer spectroscopy. Superparamagnetic/ferromagnetic
transition with the increase of particle size has also confirmed by this analysis.
Mössbauer spectroscopy measurements are shown to evidence collective inter-particle
correlations between the nanoparticles. The magnesium ferrite nanoparticles were
then coated with biocompatible Chitosan (CS) and Polyethylene glycol (PEG). NMR
spectroscopy was studied to investigate the spin-spin or T2 relaxivity values to
determine its applicability in magnetic resonance images as MRI contrast agents.
This thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Philosophy in Physics, Septmber 2015.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 122-136).
2015-09-01T00:00:00Z