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Performance Evaluation of Fecal Sludge Treatment Plant at Khulna City and Proposal for Sustainable Development
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, December 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 107-114)Bangladesh strides successfully towards full sanitation coverage which contributing to healthier life for every citizen. However, there is typically no management system in place for the accumulated fecal sludge in various containments connected to toilets. FSM (fecal sludge management) is a relatively new field, however, it is currently rapidly developing and gaining acknowledgement. Containment, emptying, transport, treatment and reuse are the basic elements of FSM. The present study is related to treatment part of FSM. Khulna the third largest city in Bangladesh having more than 1.5 million populations where people predominantly depend onsite sanitation technologies. There was no designated disposal site for collected fecal sludge and emptier had been habituated to discharge in nearby lowlands, water bodies or in drains which ultimately pollutes the environment and poses serious threat to human health. So, to fix up the situation, with the financial assistance of SNV Netherlands, Khulna city corporation (KCC) decided to establish a fecal sludge treatment plant (FSTP) at Rajbandh within the municipal landfill site boundary. The FSTP was built on a passive landfill site adopting the constructed wetlands (CW) treatment technology. This study aims at evaluating the treatment efficiency of Khulna FSTP and identifying the difficulties in operation and maintenance (O&M) at the field level and giving proposals for sustainable development.
In FSTP treated effluent, the BOD values were found to be varied from 16 mg/L to 25 mg/L while the allowable disposal limit is 40 mg/L for inland surface water bodies (ECR’97, Bangladesh). Total suspended solids (TSS) concentrations were observed in the range of 30~80 mg/L which is within the allowable limit of 100 mg/L. The nitrate and phosphate concentrations in treated effluent were always found to be far less than the acceptable limit. Escherichia coli (E.coli) in final effluent never exceeded 100N/100ml while the acceptable limit is 1000N/100ml. This study also focuses on operation and maintenance (O&M) issues. Field monitoring focused on various critical intervention issues such as: adjustment of water levels, maintenance of flow uniformity, vegetation management, odor control and maintenance of berms. Finally, some constitutive recommendations have been made for the FSTP which would ensure its long-term sustainability.Fatima NazninMaster of Science in Civil Engineerin
Studies on Volumetric and Sound Velocity of L-proline and L-lysine in Aqueous Nicotinamide 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, May, 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 161-168)In this study, volumetric and sound velocity method was used for the analysis of effect of
vitamin B3 (nicotinamide) on the structure of essential amino acids (L-proline and Llysine).
Densities and sound velocities of L-proline and L- lysine in water and in aqueous
0.03 mol.kg-1, 0.045 mol.kg-1, 0.06 mol.kg-1 and 0.09 mol.kg-1 nicotinamide solutions have
been studied at 293.15K to 318.15K 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 (δφv
0/δT)p
and Hepler’s constant (δ2φv
0/δT2)p. The acoustic properties such as adiabatic
compressibility (βs), apparent molar adiabatic compressibility (k), limiting apparent molar
adiabatic compressibility (φk
0), apparent molar adiabatic compressibility of transfer
(Δtrφk
0), acoustic impedance (Z), relative association (RA) 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 nicotinamide solutions are higher than that of amino acids in
aqueous solution. The increase of density with concentration of amino acids can be
attributed to solute-solvent interaction. The limiting apparent molar volumes (φv
0) are
positive at the studied temperatures for the binary and ternary mixtures indicate the
presence of solute-solvent interactions. 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-proline are negative
which suggest the existence of ion-hydrophobic and hydrophobic-hydrophobic group
interaction. But Δtrφv
0 values of L- lysine are positive which suggest the existence of ionhydrophilic
and hydrophilic-hydrophilic interactions. The values of limiting apparent
molar expansion (δφv
0/δT)p are positive which suggest the presence of solute-solvent
interactions in solutions of amino acids in nicotinamide. Hepler’s constant (δ2φv
0/δT2)p
values are small negative for all studied amino acids suggest the studied systems act as
structure makers. The values of partial molar volumes ( 2) increase with increasing of concentration of L-proline and L- lysine for the studied systems. This trend of 2 indicates
solute-solvent interactions increase with increasing concentration of amino acids.
The sound velocity increases with the increase of concentration of L-proline and L- lysine.
This may be attributed to the increase of compactness of the medium with the increase in
amino acids concentration. Sound velocities of amino acids in aqueous nicotinamide
solutions are higher than that of amino acids in aqueous solution. The adiabatic
compressibility (βs) decreases with the increase of concentration of L-proline and L- lysine.
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.
The values of limiting apparent molar adiabatic compressibility (φk
0) are negative. The
values of apparent molar adiabatic compressibility transfer (Δtrφk
0) are positive which
suggest the existence of strong ion-solvent interaction. At lower concentration, negative
values of Δtrφk
0 indicate that increase in hydrophobic-hydrophobic group interactions. The
small Sk values also indicates the dominating of solute–solvent interactions over solute –
solute interaction. The acoustic impedance, Z increases with the increase of concentration
of solution. The relative association, RA decreases linearly with increasing the
concentration of solute indicates the increase of solute-solvent interaction. The positive
hydration number (nH) values indicate an appreciable solvation of solutes.
Therefore, the water molecules around amino acids are less compressible than water
molecules in the bulk solution. The compressibility of ternary solution is less than binary
solution. This result suggests that the proteins or peptides generated from the studied
amino acids that will be denatured in ternary nicotinamide solution.Md. Golam AzamMaster of Science in Chemistr
Vibrational Properties of Disordered Carbon Nanotube
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, October 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 53-59).Carbon nanotube (CNT) is considered as an ideal candidate for next generation nanoelectronics
owing to unusual thermal, electrical, optical and other physical properties. It provides the
opportunity to understand one dimensional (ID) physics. Due to strong electron phonon coupling
in carbon-based nanomaterials, lattice vibrations have a significant effect on the electron
transport properties in CNT. From a realistic point of view, defects such as atomic vacancies,
adatoms, isotopes and impurities are very common during the synthesis of CNTs. Even small
concentration of vacancy changes the phonon properties of CNT significantly. Many studies on
the vibrational properties of CNT have been performed. However, these works are limited on
pristine CNT only. Here I have performed an in-depth theoretical analysis of the effect of
vacancy defects and curvature on phonon properties of (10,0) zigzag scmiconducting carbon
nanotube (ZCNT) and (10,10) armchair metallic carbon nanotube (ACNT).
In the first part of this work, a simple model to calculate the vibrational eigcnfrcqucncies
and cigcnvectors for I D disordered systems is developed using the forced vibrational method,
which is based on the mechanical resonance to extract the pure vibrational eigcnmodcs and
suitable to treat very large and complex disorder physical system. This model is then used to
study (10,0) ZCNT and (10,10) ACNT with different concentrations of atomic vacancies.
This dissertation reports some unique and interesting lindings based on computational
simulations on (10,0) and (10,10) CNTs both in low and high-frequency region. The correction
of force constant parameters due to the curvature effect of CNTs lead to the Raman active E29
mode phonon peaks are at 1576 cn11 and 1581 cm' for (10,0) and (10,10) CNTs, respectively. A
softening and shifting of the E2g mode towards the low-frequency region are observed with the
increasing of vacancies and curvature of CNTs. For vacancy concentrations of 10% or higher, the
E2g peak has been reduced into a shoulder or it has been completely disappeared. The other high
symmetry point's peaks in the h igh- frequency region are also broadened and softened for both
CNTs with the increase of defect density. Vacancy induces some new peaks at low-frequency
region of phonon density of states.
Due to scattering by atomic vacancies, the phonon wave function becomes localized in the
real space. To investigate phonon localization effect with vacancy type defects and curvature of
MI
CNTs, the mode pattern and localization length for K point in-plane TO mode at Raman D-band
frequency is calculated. Strong localization is observed with variation of vacancy concentration
and curvature of CNTs. With increasing defect densities localization effect shows stronger
confinement. The localization effect is stronger in (100) CNT than (10,10) CNT due to curvature
effect.
These findings show the significant impact of vacancy defects on the phonon properties
that strongly affect the electron transport properties of CNT-based nanodevices. These findings
will also open a route towards better understanding the thermal conductivity, specific heat
capacity, electron phonon interaction, resistivity and superconductivity in disordered CNT.Ashraful Hossain HowladerMaster of Science in Electrical and Electronic Engineerin
Modeling and Simulation of CNT based tunnel FET
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, February, 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 72-78).MOSFETs are commonly used in high speed integrated circuits and are yielding smaller, faster
and more functions at lower cost. Various problems exist with scaling of MOSFET devices
including shorl channel effects such as drain induced barrier lowering, parasitic capacitance,
velocity saturation e.t.c. which limit the performances of MOSFETs. Scaling issues of MOSFET
devices lead to lower ON to OFF current ratio limited by temperature constrained 60mV/dec
subthrcshold swing. A new type of device called 'Tunncl FET" is predicted to overcome these
difficulties. TFET can beat 60m V/dec sublhreshold swing of MOSFET. In tunnel FET, carriers
are transported by band to band tunneling and its OFF current is very low. This makes it ideal
candidate for ultra-low power electronics. Since the tunneling FET relies on the band to band
tunneling mechanism, the TFET using conventional material like silicon have very low on state
current due to its large indirect band gap. Carbon nanotube has a J)otential to be the appropriate
channel material in this new technology due to its unique quasi one dimensional properly such as
high electron mobility and high Fermi velocity. This new type of device requires rigorous
analysis with various structures and parameters and hence to find out optimum condition for
practical device realization, in this thesis we proposed and simulated two double gate CNTTFF.T
structures: (i) Oxide only over the channel (OXOC structure) (ii) Oxide extended over source to
drain (OXESD structure), taking into account of different device parameters including dielectric
strength and thickness of gate oxide materials, channel length, doping concentration and gale
underlap. Here the transtr characteristics, on/off current (h)N/h]:J) ratio and subthreshold slope
of the device are studied using Non Equilibrium Greens Function (NEGF) formalism in tight
binding frameworks. The results are obtained by solving the NEGF and Poisson's equation selfconsistently
in NanoTCAD ViDES environment and found that OXOC structure shows
significantly better performance than OXESD structure in all cases having highest ON current of
4046 j..tA/tm and suhthreshold swing of 10. 19 mV/decade so far reported for CNT TFET. The
results obtained from the simulation for both of the device structures are explained by the energy
band diagram and electric field. The presented study is expected to be useful for realizing the
switching device capable of operating at high speed and low power applications.Md. Shamim SarkerMaster of Science in Electrical and Electronic Engineerin
Analysis of High Performance Controlled Permanent Magnet Brushless DC Motor Drives without Position Sensor
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, July 2017..Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 153-157).Permanent Magnet Brushless DC (PMBLDC) motor is a new generation of converter fed
machines (CFMs) becoming more and more popular. PMBLDC motors are extensively used
as industrial motors due to its fast dynamic response, high power density, large torque to
inertia ratio, high efficiency with increased reliability, less noise, long life, silent operation,
compact fonn, low maintenance and better controllability. For innumerous applications,
PMBLDC motors are used as replacement for AC motors.
PMBLDC motor is a trapezoidal shaped back EMF permanent magnet synchronous motor
with solid state commutation system. The absence of a commutator and brushes or slip rings
in the PMBLDC motors reduces maintenance needs and raises mechanical reliability. In solid
state commutation system, rotor position information must be needed for proper commutation
sequence with proper control algorithms. Motor performance degrades due to improper
control action.
In this study, an adaptive PT speed controller based field oriented vector controlled current
fed delta modulated PMBLDC motor drive is designed. An adaptive P1 controller is proposed
based on motor speed error. Scalar control of this PMBLDC motor is also performed at direct
axis current component is equal to 1.0 and at direct axis current component equal to
quadrature axis current component. The performance of these control drives is compared
under different conditions.
In this thesis, a novel approach to enhance the torque handling capacity of a PMBLDC motor
is invented. The novelty is that, torque handling capacity of a PMBLDC motor can be
increased up to 25% from the conventional 120 conduction square wave current fed drive by
only changing the pattern of reference current of a field oriented vector controlled PMBLDC
motor drive. Toque handling capacity has to be enhanced without exceeding the maximuni
current rating of the PMBLDC motor. The performances of trapezoidal, square and sinusoidal
current fed field oriented vector controlled PMBLDC motor drives are compared on the basis
of response time, load torque handling capacity, dynamic speed and load torque changing
condition, settling time of the system and torque pulsation.
In conventional PMBLDC motor, for proper commutation of the phase currents rotor position
information must be obtained from the position sensors. But there are some vital
disadvantages of position sensor including high cost, installation difficulty of mechanics, and
poor reliability. Moreover, misalignments in position sensors, running in extreme ambient
conditions, or electromagnetic interference introduce error in the position information.
Instead of rotor position or speed sensor, two novel algorithms are proposed in this thesis to
estimate the rotor position and speed to perform the operation of position sensorless field
oriented vector control of PMBLDC motor. For algorithm I, both rotor position and speed of
the motor are determined from the estimated flux linkage. For algorithm 2, only rotor position
of the PMBLDC motor is determined from the estimated flux and the speed of the motor is
detected by the estimated developed electromagnetic torque and power equation. The
performance of flux estimation algorithm, rotor position estimator, speed estimator is
depicted by the comparative study between the actual and estimated flux, rotor position and
speed respectively.
The performance of the proposed algorithms for sensorless operation is also justified through
the sensorless trapezoidal current fed field oriented PMBLDC motor drive. In this drive, both
the advantages of position sensorless operation and enhanced torque handling capacity are
incorporated due to establish a novel high performance control drive for PMBLDC motor.
A novel position sensorless two phase conduction direct torque controlled PMBLDC motor
drive is also proposed in this study. Without considering flux control, two-phase conduction
direct torque control (DTC) of a PMBLDC motor on the basis of electromagnetic torque,
rotor position and speed estimation is pictured in the proposed drive system. The performance
of the proposed position sensorless direct torque controlled PMBLDC motor drive is
compared with the performance of conventional position sensored two phase conduction
direct torque controlled PMBLDC motor drive in terms of starting, dynamic speed and load
torque changing characteristics.Protik Chandra BiswasMaster of Science in Electrical and Electronic Engineerin