KUET Institutional Repository (Khulna University of Engineering & Technology)
Not a member yet
1045 research outputs found
Sort by
Study on the Genesis of Low Intensity Tropical Cyclones in the Bay of Bengal using WRF Model
No full textThis 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 Science in Physics, March-2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 98-101).In the present study, Weather Research and Forecasting (WRF) model is used to study the
genesis of TC Rashmi -2008, Nisha -2008, Bijly -2009 and Viyaru -2013 with low intensity
which formed on the Bay of Bengal as a depression on 03 UTC on 25 October 2008, 09 UTC
on 25 November 2008, 09 UTC on 14 April 2009 and 09 UTC on 10 May 2013. Latter they
intensified up to cyclonic storm. Four cases are also studies when there is no cyclone and
named as normal case. The model is configured in single domain, 9 km horizontal grid
spacing with 290×316 grids in the west-east and north-south directions and 32 vertical levels
and run the model using KF cumulus and YSU planetary boundary layer along with Final
Reanalysis (FNL) data (1o x1o) from National Centre for Environment Prediction (NCEP),
USA as initial and lateral boundary conditions (LBCs). Model is run in two steps for cyclone:
firstly the formation of depression and secondly the intensification up to cyclonic storm. For
the first step, model is run with 96, 72, 48 and 24 hour to trace the formative stage as
depression and for the second step, model is also run for 24 hour to test the
formation/intensification as cyclonic storm. For the normal cases, model is run with 96, 72,
48 and 24 hour. Wind speed (WS) at 10m, Vertical wind shear (VWS) between 850-200hPa,
Vertical profile of Horizontal wind (VHW), Vertical profile of Vertical wind (VVW),
Relative Vorticity (RV) (850 hPa), Sea Surface Temperature (SST), Mean Sea Level Pressure
(SLP), Relative Humidity (RH), Convective Available Potential Energy (CAPE) and
Convective Inhibition (CIN) obtained from cyclones and normal cases are computed. Then,
for first step, values obtained from cyclone cases are compared with those obtained from
normal cases and available data. Then, for second step, values obtained from cyclone cases
are discussed and compared with available observed data. Significant difference between the
parameters obtained from cyclone cases and normal cases are obtained. Results suggest that
circular shape of wind, close circle of SLP are observed in cyclone cases without exception.
RH exists from surface to middle levels. It may say that model simulates the depression and
cyclonic stages with more or less intensity with considerable lead timeDevbrota Kumar BiswasMaster of Science in Physic
Analyzing and Mitigating Power Quality Problems of Grid-Connected Wind Energy Systems
No full textThis thesis is submitted to the Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Electronic Engineering, April 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 77-83).To meet the excessive demand of electric power and maintain a sustainable development with
a greener world, the generation system now moves to renewable energy sources. Among the
renewable based distributed generation systems, the wind based one is becoming popular day
by day. When the wind based distributed generation (DG) and the distributed network (DN)
both are connected to establish a technologically upgraded system, then different types of
power quality problems arise in the system. In this thesis, the adverse impact of the resultant
harmonics of permanent magnet synchronous generator (PMSG) based wind turbine is
examined from every corner and also found a perfect remedy. For pointing out the harmonics
nature and magnitude of distribution systems, different types of non-linear loads, such as
resistive-inductive loads, induction motor with adjustable speed drive and arc furnace are
modeled. In faulty conditions, the voltage sag and swell issues are also overviewed here. In this
research, an AC/DC/AC converter is designed with voltage dependent current limiter and the
proposed current control mechanism of the generator’s converter is based on the straight line
theory. The proposed control mechanism for designing the voltage source converter of the
static synchronous compensator (STATCOM), which is connected to a battery, is governed by
the pulse width modulation technique. A proper integration between these two control
mechanisms creates a stable system and mitigates the power quality problems. The overall
performance of the proposed model is tested on a 12 bus radial network, with designed nonlinear
loads connected to it, using PSCAD/EMTDC software and afterwards laboratory tests
are carried out to examine the harmonics currents and voltages. From the analysis, it is
investigated that harmonic increases as the number of distributed generator increases and also
in faulty conditions. Moreover, the level of harmonic varies based on the position of the wind
generator and non-linear loads. The research outcome obtained from this comprehensive
analysis proved that the proposed control mechanism approach is successful to eliminate and
keep the voltage and current harmonics within a safe range, maintain the power system
stability as well as mitigate the voltage sag and swell.Aparupa DasMaster of Science in Electrical and Electronic Engineerin
An Approach to Ensure the Secrecy of Scene Images
No full textThis thesis is submitted to the Department of Computer Science and Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Engineering in Computer Science and Engineering, July 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 49-52).This thesis proposes a multi-stage encryption technique to enhance the level of secrecy of
image to facilitate its secure transmission through the public network. A vast number of
researches have been done on image secrecy. The existing image encryption techniques
like visual cryptography (VC), steganography, and watermarking etc. while are applied
individually; usually they cannot provide unbreakable secrecy. Through combining several
separate techniques, a hybrid multi-stage encryption technique is proposed in this thesis,
which provides nearly unbreakable image secrecy, while the encryption/decryption time
remains almost the same of the exiting techniques. The technique consecutively exploits
VC, steganography and one time pad (OTP). At first it encrypts the input image using VC,
i.e., splits the pixels of the input image into multiple shares to make it unpredictable. Then
after the pixel to binary conversion within each share, the exploitation of steganography
detects the least significant bits (LSBs) from each chunk within each share. At last, OTP
encryption technique is applied on LSBs along with randomly generated OTP secret key to
generate the ultimate cipher image. Besides, prior to sending the OTP key to the receiver,
first it is converted from binary to integer and then an asymmetric cryptosystem is applied
to encrypt it and thereby the key is delivered securely. Finally, the outcome, the time
requirement of encryption and decryption, the security and statistical analyses of the
proposed technique are evaluated and compared with existing techniques.Arindom MondalMaster of Science in Engineering in Computer Science and Engineerin