Abstract: Space Vector Pulse Width Modulation is popular for
variable frequency drives. The method has several advantages over
carried based PWM and is computation intensive. The
implementation of SVPWM for multilevel inverter requires special
attention and at the same time consumes considerable resources. Due
to faster processing power and reduced over all computational
burden, FPGAs are being investigated as an alternative for other
controllers. In this paper, a space vector PWM algorithm is
implemented using FPGA which requires less computational area and
is modular in structure. The algorithm is verified experimentally for
Neutral Point Clamped inverter using FPGA development board
xc3s5000-4fg900.
Abstract: This paper is aimed to study combustion characteristics
of low NOx burner using petroleum cokes as fuel. The petroleum coke,
which is produced through the oil refining process, is an attractive fuel
in terms of its high heating value and low price. But petroleum coke is
a challenging fuel because of its low volatile content, high sulfur and
nitrogen content, which give rise to undesirable emission
characteristics and low ignitability. Therefore, the research and
development regarding the petroleum coke burner is needed for
applying this industrial system. In this study, combustion and emission
characteristics of petroleum cokes burner are experimentally
investigated in an industrial steam boiler. The low NOx burner is
designed to control fuel and air mixing to achieve staged combustion,
which, in turn reduces both flame temperature and oxygen. Air
distribution ratio of triple staged air is optimized experimentally. The
result showed that NOx concentration is lowest when overfire air is
used, and the burner function at a fuel rich condition. That is, the
burner is operated at the equivalence ratio of 1.67 and overall
equivalence ratio including overfire air is kept 0.87.
Abstract: In an attempt to investigate the performance of single
basin solar still for climate conditions of Ludhiana a single basin
solar still was designed, fabricated and tested. The energy balance
equations for various parts of the still are solved by Gauss-Seidel
iteration method. Computer model was made and experimentally
validated. The validated computer model was used to estimate the
annual distillation yield and performance ratio of the still for
Ludhiana. The Theoretical and experimental distillation yield were
4318.79 ml and 3850 ml respectively for the typical day. The
predicted distillation yield was 12.5% higher than the experimental
yield. The annual distillation yield per square metre aperture area and
annual performance ratio for single basin solar still is 1095 litres and
0.43 respectively. The payback period for micro-stepped solar still is
2.5 years.
Abstract: Electrostatic interaction energy (ΔEEDL) is a part of the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, which, together with van der Waals (ΔEVDW) and acid base (ΔEAB) interaction energies, has been extensively used to investigate the initial adhesion of bacteria to surfaces. Electrostatic or electrical double layer interaction energy is considerably affected by surface potential; however it cannot be determined experimentally and is usually replaced by zeta (ζ) potential via electrophoretic mobility. This paper focusses on the effect of ionic concentration as a function of pH and the effect of mineral grain size on ζ potential. It was found that both ionic strength and mineral grain size play a major role in determining the value of ζ potential for the adhesion of P. putida to hematite and quartz surfaces. Higher ζ potential values lead to higher electrostatic interaction energies and eventually to higher total XDLVO interaction energy resulting in bacterial repulsion.
Abstract: The aim of the current work was to employ the finite
element method to model a slab, with a small hole across its width,
undergoing plastic plane strain deformation. The computational
model had, however, to be validated by comparing its results with
those obtained experimentally. Since they were in good agreement,
the finite element method can therefore be considered a reliable tool
that can help gain better understanding of the mechanism of ductile
failure in structural members having stress raisers. The finite element
software used was ANSYS, and the PLANE183 element was utilized.
It is a higher order 2-D, 8-node or 6-node element with quadratic
displacement behavior. A bilinear stress-strain relationship was used
to define the material properties, with constants similar to those of the
material used in the experimental study. The model was run for
several tensile loads in order to observe the progression of the plastic
deformation region, and the stress concentration factor was
determined in each case. The experimental study involved employing the visioplasticity
technique, where a circular mesh (each circle was 0.5 mm in
diameter, with 0.05 mm line thickness) was initially printed on the
side of an aluminum slab having a small hole across its width.
Tensile loading was then applied to produce a small increment of
plastic deformation. Circles in the plastic region became ellipses,
where the directions of the principal strains and stresses coincided
with the major and minor axes of the ellipses. Next, we were able to
determine the directions of the maximum and minimum shear
stresses at the center of each ellipse, and the slip-line field was then
constructed. We were then able to determine the stress at any point in
the plastic deformation zone, and hence the stress concentration
factor. The experimental results were found to be in good agreement
with the analytical ones.
Abstract: Liquid-Liquid Equilibrium (LLE) data are measured
for the ternary mixtures of water + 1-butanol + butyl acetate and
quaternary mixtures of water + 1-butanol + butyl acetate + glycerol at
atmospheric pressure at 313.15 K. In addition, isothermal
vapor–liquid–liquid equilibrium (VLLE) data are determined
experimentally at 333.15 K. The region of heterogeneity is found to
increase as the hydrophilic agent (glycerol) is introduced into the
aqueous mixtures. The experimental data are correlated with the
NRTL model. The predicted results from the solution model with the
model parameters determined from the constituent binaries are also
compared with the experimental values.
Abstract: The development of electric vehicle batteries have
resulted in very high energy density lithium-ion batteries. However,
this progress is accompanied by the risk of thermal runaway, which
can result in serious accidents. Heat pipes are heat exchangers that
are suitable to be applied in electric vehicle battery thermal
management for their lightweight, compact size and do not require
external power supply. This paper aims to examine experimentally a
Flat Plate Loop Heat Pipe (FPLHP) performance as a heat exchanger
in thermal management system of lithium-ion battery for electric
vehicle application. The heat generation of the battery was simulated
using a cartridge heater. Stainless steel screen mesh was used as the
capillary wick. Distilled water, alcohol and acetone were used as
working fluids with a filling ratio of 60%. It was found that acetone
gives the best performance that produces thermal resistance of 0.22
W/°C with 50°C evaporator temperature at heat flux load of 1.61
W/cm2.
Abstract: Typical load-bearing biological materials like bone,
mineralized tendon and shell, are biocomposites made from both
organic (collagen) and inorganic (biomineral) materials. This
amazing class of materials with intrinsic internally designed
hierarchical structures show superior mechanical properties with
regard to their weak components from which they are formed.
Extensive investigations concentrating on static loading conditions
have been done to study the biological materials failure. However,
most of the damage and failure mechanisms in load-bearing
biological materials will occur whenever their structures are exposed
to dynamic loading conditions. The main question needed to be
answered here is: What is the relation between the layout and
architecture of the load-bearing biological materials and their
dynamic behavior? In this work, a staggered model has been
developed based on the structure of natural materials at nanoscale and
Finite Element Analysis (FEA) has been used to study the dynamic
behavior of the structure of load-bearing biological materials to
answer why the staggered arrangement has been selected by nature to
make the nanocomposite structure of most of the biological materials.
The results showed that the staggered structures will efficiently
attenuate the stress wave rather than the layered structure.
Furthermore, such staggered architecture is effectively in charge of
utilizing the capacity of the biostructure to resist both normal and
shear loads. In this work, the geometrical parameters of the model
like the thickness and aspect ratio of the mineral inclusions selected
from the typical range of the experimentally observed feature sizes
and layout dimensions of the biological materials such as bone and
mineralized tendon. Furthermore, the numerical results validated with
existing theoretical solutions. Findings of the present work emphasize
on the significant effects of dynamic behavior on the natural
evolution of load-bearing biological materials and can help scientists
to design bioinspired materials in the laboratories.
Abstract: The design of high pressure water jet based polishing
equipment and its fabrication conducted in this study is reported
herein, together with some preliminary test results for assessing its
applicability for HMA surface polishing. This study also provides
preliminary findings concerning the test variables, such as the
rotational speed, the water jet pressure, the abrasive agent used, and
the impact angel that were experimentally investigated in this study. The preliminary findings based on four trial tests (two on large
slab specimens and two on small size gyratory compacted
specimens), however, indicate that both friction and texture values
tend to increase with the polishing durations for two combinations of
pressure and rotation speed of the rotary deck. It seems that the more
polishing action the specimen is subjected to; the aggregate edges are
created such that the surface texture values are increased with the
accompanied increase in friction values. It may be of interest (but
which is outside the scope of this study) to investigate if the similar
trend exist for HMA prepared with aggregate source that is sand and
gravel.
Abstract: In this study, to clarify the effectiveness of an
aluminum/chromium/tungsten-based-coated tool for cutting sintered
steel, tool wear was experimentally investigated. The sintered steel
was turned with the (Al60,Cr25,W15)N-, (Al60,Cr25,W15)(C,N)- and
(Al64,Cr28,W8)(C,N)-coated cemented carbide tools according to the
physical vapor deposition (PVD) method. Moreover, the tool wear of
the aluminum/chromium/tungsten-based-coated item was compared
with that of the (Al,Cr)N coated tool. Furthermore, to clarify the tool
wear mechanism of the aluminum/chromium/tungsten-coating film for
cutting sintered steel, Scanning Electron Microscope observation and
Energy Dispersive x-ray Spectroscopy mapping analysis were
conducted on the abraded surface. The following results were
obtained: (1) The wear progress of the (Al64,Cr28,W8)(C,N)-coated
tool was the slowest among that of the five coated tools. (2) Adding
carbon (C) to the aluminum/chromium/tungsten-based-coating film
was effective for improving the wear-resistance. (3) The main wear
mechanism of the (Al60,Cr25,W15)N-, the (Al60,Cr25,W15)(C,N)-
and the (Al64,Cr28,W8)(C,N)-coating films was abrasive wear.
Abstract: Interstitial free steels possess better formability and
have many applications in automotive industries. Forming limit
diagrams (FLDs) indicate the formability of materials which can be
determined by experimental and finite element (FE) simulations.
FLDs were determined experimentally by LDH test, utilizing optical
strain measurement system for measuring the strains in different
width specimens and by FE simulations in Interstitial Free (IF) and
Interstitial Free High Strength (IFHS) steels. In this study, the
experimental and FE simulated FLDs are compared and also the
stress based FLDs were investigated.
Abstract: In this study free vibration analysis of aluminum
honeycomb sandwich structures were carried out experimentally and
numerically. The natural frequencies and mode shapes of sandwich
structures fabricated with different configurations for clamped-free
boundary condition were determined. The effects of lower and upper
face sheet thickness, the core material thickness, cell diameter, cell
angle and foil thickness on the vibration characteristics were
examined. The numerical studies were performed with ANSYS
package. While the sandwich structures were modeled in ANSYS the
continuum model was used. Later, the numerical results were
compared with the experimental findings.
Abstract: We investigate experimentally and theoretically the
dynamics of a capacitive resonator under mixed frequency excitation
of two AC harmonic signals. The resonator is composed of a proof
mass suspended by two cantilever beams. Experimental
measurements are conducted using a laser Doppler Vibrometer to
reveal the interesting dynamics of the system when subjected to twosource
excitation. A nonlinear single-degree-of-freedom model is
used for the theoretical investigation. The results reveal combination
resonances of additive and subtractive type, which are shown to be
promising to increase the bandwidth of the resonator near primary
resonance frequency. Our results also demonstrate the ability to shift
the combination resonances to much lower or much higher frequency
ranges. We also demonstrate the dynamic pull-in instability under
mixed frequency excitation.
Abstract: In the immunologic sense, clinical infection is a state
of failure of the immune system to combat the pathogenic weapon of
the bacteria invading the host. A motile gram negative vibroid
organism associated with marked mono and poly nuclear cell
responses was traced during the examination of a clinical material
from an infected common carp Cyprinus carpio. On primary plate
culture, growth was shown to be pure, dense population of an
Aeromonas-like colony morphotype. The pure isolate was found to
be; Aerobic, facultatively anaerobic, non-halophilic, grew at 0C, and
37C, oxidase positive utilizes glucose through fermentative pathway,
resist 0/129 and novobiocin, produces alanine and lysine
decarboxylases but non-producing ornithine dehydrolases. Tests for
the in vitro determinants of pathogenicity has shown to be; Betahaemolytic
onto blood agar, gelatinase, casienase and amylase
producer. Three in vivo determinants of pathogenicity were tested as,
the lethal dose fifty, the pathogenesis and pathogenicity. It was
evident that 0.1 milliliter of the causal bacterial cell suspension of a
density 1 x 107 CFU/ml injected intramuscularly into an average of
100gms fish toke five days incubation period, then at the day six
morbidity and mortality were initiated. LD50 was recorded at the day
12 post-infection. Use of an LD50 doses to study the pathogenicity,
reveals mononuclear and polynuclear cell responses, on examining
the stained direct films of the clinical materials from the
experimentally infected fish. Re-isolation tests confirm that the reisolant
is same. The course of the infection in natural case was shown
manifestation of; skin ulceration, haemorrhage and descaling. On
evisceration, the internal organs were shown; congestion in the
intestines, spleen and, air sacs. The induced infection showed a
milder form of these manifestations. The grading of the virulence of
this organism was virulent causing chronic course of infections as
indicated from the pathogenesis and pathogenicity studies. Thus the
infectious bacteria were consistent with Aeromonas hydrophila, and
the infection was chronic.
Abstract: Biomass briquette gasification is regarded as a
promising route for efficient briquette use in energy generation, fuels
and other useful chemicals. However, previous research has been
focused on briquette gasification in fixed bed gasifiers such as
updraft and downdraft gasifiers. Fluidised bed gasifier has the
potential to be effectively sized to medium or large scale. This study
investigated the use of fuel briquettes produced from blends of rice
husks and corn cobs biomass, in a bubbling fluidised bed gasifier.
The study adopted a combination of numerical equations and Aspen
Plus simulation software, to predict the product gas (syngas)
composition base on briquette density and biomass composition
(blend ratio of rice husks to corn cobs). The Aspen Plus model was
based on an experimentally validated model from the literature. The
results based on a briquette size 32 mm diameter and relaxed density
range of 500 to 650kg/m3, indicated that fluidisation air required in
the gasifier increased with increase in briquette density, and the
fluidisation air showed to be the controlling factor compared with the
actual air required for gasification of the biomass briquettes. The
mass flowrate of CO2 in the predicted syngas composition increased
with an increase in air flow, in the gasifier, while CO decreased and
H2 was almost constant. The ratio of H2 to CO for various blends of
rice husks and corn cobs did not significantly change at the designed
process air, but a significant difference of 1.0 was observed between
10/90 and 90/10 % blend of rice husks and corn cobs.
Abstract: This study is aiming at establishing the relationship
between the optical signal of flame and an equivalent ratio of flame. In
this experiment, flame optical signal in a furnace is measured using
photodiode. The combustion system is composed of metal fiber burner
and vertical furnace, and flame chemiluminescence is measured at
various experimental conditions. In this study, the flame
chemiluminescence of laminar premixed flame is measured using
commercially available photodiode. It is experimentally investigated
the relationship between equivalent ratio and photodiode signal. In
addition, the strategy of combustion control method is proposed using
the optical signal and fuel pressure.
The results showed that certain relationship between optical data of
photodiode and equivalence ratio exists, and this leads to the
successful application of this system for instantaneous measurement of
equivalence ration of the combustion system.
Abstract: Fast speed drives for Permanent Magnet Synchronous
Motor (PMSM) is a crucial performance for the electric traction
systems. In this paper, PMSM is derived with a Model-based
Predictive Control (MPC) technique. Fast speed tracking is achieved
through optimization of the DC source utilization using MPC. The
technique is based on predicting the optimum voltage vector applied
to the driver. Control technique is investigated by comparing to the
cascaded PI control based on Space Vector Pulse Width Modulation
(SVPWM). MPC and SVPWM-based FOC are implemented with the
TMS320F2812 DSP and its power driver circuits. The designed MPC
for a PMSM drive is experimentally validated on a laboratory test
bench. The performances are compared with those obtained by a
conventional PI-based system in order to highlight the improvements,
especially regarding speed tracking response.
Abstract: In the present research work we present the optical
emission studies of the Indium (In) – Tin (Sn) plasma produced by
the first (1064 nm) harmonic of an Nd: YAG nanosecond pulsed
laser. The experimentally observed line profiles of neutral Indium (In
I) and Tin (SnI) are used to extract the electron temperature (Te)
using the Boltzmann plot method. Whereas, the electron number
density (Ne) has been determined from the Stark broadening line
profile method. The Te is calculated by varying the distance from the
target surface along the line of propagation of plasma plume and also
by varying the laser irradiance. Beside we have studied the variation
of Ne as a function of laser irradiance as well as its variation with
distance from the target surface.
Abstract: This paper presents the design and characterization of
analog readout interface circuits for ion sensitive field effect
transistor (ISFET) and ion selective electrode (ISE) based sensor.
These interface circuits are implemented using MIMOS’s 0.35um
CMOS technology and experimentally characterized under 24-leads
QFN package. The characterization evaluates the circuit’s
functionality, output sensitivity and output linearity. Commercial
sensors for both ISFET and ISE are employed together with glass
reference electrode during testing. The test result shows that the
designed interface circuits manage to readout signals produced by
both sensors with measured sensitivity of ISFET and ISE sensor are
54mV/pH and 62mV/decade, respectively. The characterized output
linearity for both circuits achieves above 0.999 Rsquare. The readout
also has demonstrated reliable operation by passing all qualifications
in reliability test plan.
Abstract: In wastewater treatment processes, aeration introduces
air into a liquid. In these systems, air is introduced by different
devices submerged in the wastewater. Smaller bubbles result in more
bubble surface area per unit of volume and higher oxygen transfer
efficiency. Jet pumps are devices that use air bubbles and are widely
used in wastewater treatment processes. The principle of jet pumps is
their ability to transfer energy of one fluid, called primary or motive,
into a secondary fluid or gas. These pumps have no moving parts and
are able to work in remote areas under extreme conditions. The
objective of this work is to study experimentally the characteristics of
the jet pump and the size of air bubbles in the laboratory water tank.
The effect of flow rate ratio on pump performance is investigated in
order to have a better understanding about pump behavior under
various conditions, in order to determine the efficiency of receiving
air bubbles different sizes. The experiments show that we should take
care when increasing the flow rate ratio while seeking to decrease
bubble size in the outlet flow. This study will help improve and
extend the use of the jet pump in many practical applications.