KUET Institutional Repository (Khulna University of Engineering & Technology)
Not a member yet
1045 research outputs found
Sort by
Low-Cost Rechargeable Battery Using Pencil Graphite as Ion Intercalation / De-Intercalation Electrode
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Chemistry, June 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 63-73).Remarkable improvement in utilizing renewable energy has pioneered to a critical demand for the large-scale energy storage system considering cost, safety and environmental aspect. Zn/Al-ion batteries are eco-friendly and advantageous over acid or alkali-based batteries as it is possible to utilize Zn metal as the negative electrode in aqueous medium. Here a Zn/Al-ion battery is developed using Pencil graphite, coated with graphene by cyclic voltammetry (CV), as the positive electrode and Zn metal as the negative electrode in an aqueous AlCl3/Zn(CH3COO)2 (0.5/0.5M) electrolyte. The Zn/Al-ion cell shows average discharge voltage plateaus around 1.0 V which offers a specific cathode capacity of ~54.1 mAh g−1 at a constant current density of 55 mA g−1 and exhibits capacity retention of more than ~95.8% over 100 cycles without any formation of dendrite at the negative electrode (Zn). Reversible Al3+ or [Al(H2O)6]3+ ion intercalation/de-intercalation storage process involving graphene coated pencil graphite (positive electrode) during charge-discharge cycling is proposed on the basis of CV, Electrochemical impedance spectroscopy (EIS), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) analysis.Md. Jahidul IslamMaster of Science in Chemistr
A Technique for DNA Cryptography Based on Dynamic Mechanisms
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, September 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 58-61).This thesis proposes a dynamic technique for DNA cryptography based on dynamic
sequence table and dynamic DNA encoding mechanisms along with an asymmetric
cryptosystem. The main focusing area of the thesis is to deploy a completely dynamic
approach which includes generating dynamic sequence table to produce ciphertext,
dividing the ciphertext into a number of chunks, applying public key to encrypt each chunk
and finally dynamic DNA encoding is used to merge the chunk of each ciphertext. Firstly,
the plaintext is transformed into its corresponding DNA bases. Secondly, ASCII characters
are randomly assigned to each sequence of DNA bases in the dynamic sequence table.
Herein, the position of the DNA bases changes dynamically through iteration process. The
generated ciphertext is divided into a fixed sized of chunks and to encrypt each chunk an
symmetric cryptosystem is employed. Dynamic DNA encoding is formed using adequate
random strings and efficient mathematical series and it is used to set how much random
strings will be taken to merge all the ciphertext of chunks together. The usage of dynamic
sequence table, public key cryptography, random string and dynamic DNA encoding
altogether enhance the secrecy of data. According to the National Institute of Standards and
Technology (NIST), an empirical test is performed to analyze the randomness of the
ciphertext. Finally the encryption and decryption time is compared between the proposed
technique and other existing techniques.Md. Rafiul BiswasMaster of Science in Engineering in Computer Science and Engineerin
A Compressive Sensing Approach to Analyze the Performance of wideband Cognitive Radio Networks
No full textThis thesis is submitted to the Department of Electronics and Communication Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electronics and Communication Engineering, April 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 52-58).In the field of wireless communication systems, Cognitive Radio (CR) technology is the talk of the time for the best utilization of spread spectrum frequency. In the Wideband range, traditional Narrowband Sensing methods are not suitable to apply for performing Spectrum Sensing, as of making a single binary decision (Primary User present or absent) in the entire Wideband signal, thus cannot locate individual spectral opportunities that rely within the Wideband Spectrum. The Compressive Sensing (CS) can recover sparse signals at Sub-Nyquist rates and it depends on this principle of sparsity, so that a brief representation of the signal is possible when expressed in a suitable form. This research work has proposed a model of CR receiver sensing module which can be able to estimate a significant part (which is highly sparse among the segments of the spectrum) of the entire Wideband Spectrum with lower computational complexity. This propose work aims to analyze the compression ratio, i.e. M/N, with different number of Primary User (PUs) present in the wideband frequency from the Receiver Operating Characteristics (ROC) curves. Additionally, it is also analyzed that how the compression ratio, M/N characteristics varies with signal-t-noise ratio (SNR) in the wideband frequency from the ROC curves. This work investigates the probability of detection, Pd versus SNR for a fixed M/N and the throughput of a CR network against sensing period for a fixed frame length and vice versa. This proposed work also aims to find the requirement of less computational complexity and physical memory. Eventually, from the wide investigations through our proposed research work, it is found that the proposed method provides better throughput for fixed frame length as well as fixed sensing slot duration as well as frame duration the throughput is greater for shorter sensing time period. It can hopefully state in the final point that the proposed method proves its significance in CR system.S. M. Bulbul AhmmedMaster of Science in Electronics and Communication Engineerin
Volumetric and Sound Velocity Studies on L-Lysine and L-Arginine in Aqueous Sodium Benzoate Solution at Different Temperature
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Chemistry, September 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 133-140).In this study, a general volumetric and sound velocity method was used to analyze the
effects of sodium benzoate (SB) on the structure of essential amino acids (L-lysine,
L-arginine). Densities and sound velocities of L-lysine and L-arginine in aqueous and in
aqueous 0.05 mol.kg-1, 0.2 mol.kg-1, 0.35 mol.kg-1 and 0.5 mol.kg-1 SB solutions have been
studied at 293.15K to 313.15K with an interval of 5K. The density data have been used to
calculate apparent molar volume (φv), limiting apparent molar volume (φv
0), limiting
apparent molar volume transfer (Δtrφv
0), apparent molar expansibilities ( 0
E ) and Helper’s
constant ( E / T) p 0 . The acoustic properties such as adiabatic compressibility (βs),
apparent molar adiabatic compressibility (k), limiting apparent molar adiabatic
compressibility (φk
0), apparent molar adiabatic compressibility transfer (Δtrφk
0), acoustic
impedance (Z) and hydration number (nH) have been calculated by densities and sound
velocities data.
The densities increase with the increase of concentration of amino acids. Densities of
amino acids in aqueous SB solutions are higher than that of amino acids in aqueous
solution. The limiting apparent molar volumes (φv
0) and the values of experimental slope
(Sv) are positive. The smaller values of Sv as compared to φv
0 values suggest the
dominance of solute-solvent interaction over the solute-solute interaction.
The limiting apparent molar volume transfer (Δtrφv
0) values of L-lysine and L-arginine in
SB solutions are negative. This indicate that ion-hydrophobic and hydrophobichydrophobic
group interaction are dominating over the hydrophilic-hydrophilic interaction.
The values of limiting apparent molar expansion ( 0
E ) are positive. These trends in
limiting apparent molar expansions for these amino acids in each concentration of SB
solutions indicating the presence of solute-solvent interaction. The Hepler’s constant
p ( E / T) 0 values of binary system are entirely positive for all studied amino acids suggest
the studied systems act as structure makers. In ternary system some values are small
negative and some values are positive. Hepler’s constant p ( E / T) 0 in ternary solutions indicating the structure making properties of amino acids in SB solutions. The values of
partial molar volumes (V̅ 2) increase with increasing of concentration of L-lysine,
L-arginine for the studied systems.
As the concentration of amino acids increases, the adiabatic compressibility (βs) decreases.
This indicates the water molecules around the amino acids are less compressible than the
water molecules in the bulk solution. The negative apparent molar adiabatic
compressibility (k) values indicate the greater loss of structural compressibility of water
implying a greater ordering effect by the solute on the solvent. Δtrφk
0 values of L-lysine are
positive whereas Δtrφk
0 of L-arginine are negative. This indicate that hydrophilichydrophilic
and ion-hydrophilic interaction are dominating for L-lysine systems whereas
hydrophobic-hydrophobic and ion-hydrophobic interactions are dominating for L-arginine
systems. The small Sk values also indicates the solute-solvent interactions.
The increase in acoustic impedance Z, indicates the presence of effective solvent-solvent
interactions with the increase in solution concentration. The positive hydration number (nH)
values indicate an admirable solubility of the solutes.
Water molecules around amino acids have less shrinkage than water molecules in bulk
solutions. The compressive strength of the ternary solution is less than that of the binary
solution. This result suggests that the proteins or peptides generated from the studied
amino acids will be denatured in ternary SB solutions.Master of Science in Chemistr
Modeling of Spatial and Morphological Changes in Bhairab-Atai-Rupsha River Confluence
No full textThis thesis is submitted to the Department of Civil Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering, March 2018.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 146-149).The Rupsha River, also known as Pasur, which is formed of the union of the Bhairab
and Atai rivers. At present, much of its water is from the Gorai diverted through the
Nabaganga. From near Batiaghata upazila the Rupsa changes its name to Kazibacha,
which is given up near Chalna in favour of Pasur. Near the Mongla port, the Pasur
receives Mongla river, and near the forest outpost at Chandpai it receives the
Mirgamari cross-channel from the Bhola, both on the left-bank. On the right bank the
Manki, Dhaki and Bhadra are linked to the Shibsa system. In the lower delta, the
Rupsa-Pasur is second only to the Meghna in size. Formerly it was third, after
the Gorai-Madhumati, but with the considerable diversion of the Ganges water at
upstream and due to less flow in the Gorai, the Gorai-Modhumati flow dwindled and as
a result the Pasur gradually become bigger. Notable Nabaganga also receives flow from
Modhumati. The Bhairab-Atai-Rupsha confluence system is the life line at upstream,
situated at the center of Khulna city. Bhairab and Atai are the only gateways to reach to
the upstream through Rupsha and Pasur. Therefore, morphological and environmental
pattern study, of this three rivers system and their catchment area is very important. In
this study, morphological behavior of total length of Atai and Rupsa River and two of
the confluences in between their accumulated length is accomplished. Moreover,
environmental and land surface pattern of the catchment area are studied in different
point of view, such as Land Surface Temperature (LST), vegetation cover, amount of
water body, barren and urban area etc.
Two types of solver, named Nays2DH and River2D of iRIC 2.3 version software
package, are used for modeling flow pattern in channel meander and confluence
respectively. ArcGIS 10.4.1 version software package is used to study the
environmental and land surface pattern of the catchment area. All the morphological
data are collected from Bangladesh Water development Board (BWDB). Necessary
satellite data, for selecting catchment area and environmental study, are collected from
different website of the National Aeronautics and Space Administration (NASA), as
https://glovis.usgs.gov/, https://earthexplorer.usgs.gov/ etc. The catchment area is
selected from SRTM 1 Arc-Second Global digital elevation model (DEM) data. Before
morphological modeling, a previous experimental work and related numerical models
are compared with present numerical model, to observe applicability of the present
study. During morphological modeling of meander and confluence, both high and ebbtide
condition is considered, as this river system is under tidal influence. For the
simulation of high and ebb-tide condition, fixed discharge is considered and discharge
data are collected from the Mongla Port Authority (MPA). Satellite image processing
technique is used, during modeling of environmental and land surface pattern of the
catchment area.
From modeling of river meander, positions are recognized along the length of Atai and
Rupsha River, where flow velocity is decreased. From flow velocity and elevation
relationship of the model, it is observed that velocity is decreased significantly, where
flow depth is lower. It happens mainly because of channel bed friction, which
significantly affects the channel flow. Also, it is found that secondary current is strong at both banks of the river, which creates a three dimensional effect and reduce the
primary flow velocity magnitude near the banks. This flow velocity reduction causes
siltation to a particular position of the channel, which brings inefficient navigability. So
from this model, position of necessary future dredging work can be determined.
Determination of separation zone is an important task to understand the complex flow
pattern near the estuary of the confluence. During modeling of the confluence, these
separation zones are detected both for high- tide and ebb-tide condition. So, from the
separation zones, place of siltation near the estuary also be detected. Formation of
separation zone is largely dependent on the channel geometry near the estuary. A
hypothesis is proposed to reduce the intensity of the separation zone, by changing the
geometry near the estuary. After changing geometry, the confluences are remodeled
and a partial success is observed as separation zone is reduced in size and in some case
eliminated.
Lastly the modeling of environmental and land surface pattern of the catchment area
shows that, at present large vegetation areas like Sundarban is under drought condition,
while at past it was totally different. The reason may be increase of salinity in the
western part of Bangladesh. Also, it is observed that barren area is mostly replaced by
small vegetation like crop field. Lastly Land Surface Temperature (LST) decreases
recently rather than the past because of replacement of barren area by small vegetation.
A morphological model developed in this study largely reflects the flow pattern in
Bhairab, Atai and Rupsha river geometries. Also the environmental and land surface
pattern model of the catchment area reflects the present land surface pattern as
compared with past years. From these models, several decisions can be made to keep
the channel and estuaries functional as well as the catchment area habitable. This type
of model based study addressed in this research, really convenient, helpful, cheap and
less time consuming for predicting and making an engineering decision for different
morphological and environmental condition.Chandan MondalMaster of Science in Civil Engineerin