|
ARPN Journal of Engineering and Applied
Sciences March 2011 | Vol. 6 No. 3 |
|
|
Title: |
Design of a
model of modern variable reluctance tachogenerator
(electromagnetic sensor) for measuring angular velocity of a
rotating shaft using frequency to digital conversion techniques. |
Author (s): |
Shalangwa D.
A. and Waba A. S. |
Abstract: |
The objective of this research
is to design a model of modern variable reluctance tachogenerator (electromagnetic sensor) for measuring angular
velocity of a rotating shaft using frequency to digital
conversion techniques. The method used in the design is an
adaptation of standard tachogenerator design although the
design utilized reasonable number of slots (60) in a disc, NE
572 as a special comparator and bubble resolver. These
improved the sensitivity, speed and eliminate ±1 error that is
inherent in most digital systems, respectively. The model was
tested with a DC motor; and was able to measured angular
velocity ranging from 100-1000rpm with their corresponding
frequencies 16Hz-160Hz. The model is capable of measuring
angular velocity of other devices if the speed of revolution
is not more than 10,000 rpm. |
|
|
|
Title: |
Dynamic
modeling and control of a two wheeled robotic vehicle with a
virtual payload |
Author (s): |
K. M. Goher, M. O. Tokhi and N. H. Siddique |
Abstract: |
One of the challenging issues to
consider in balancing a two-wheeled robotic machine (TWRM)
is when the load carried by the machine is changing position
along the vehicle intermediate body (IB). An issue of interest
in this case is the resulting impact on the system behaviour
due to changing position of the load. Further complications
arise with changing the size of the load. This work presents
investigations into controlling a TWRM with a payload
positioned at different locations along its IB. Two types of
control techniques are developed and implemented on the
system, the traditional proportional-derivative (PD) control
and fuzzy logic (FL) control. PD and PD-fuzzy logic control
techniques are developed to balance the vehicle with a payload
incorporating two different scenarios. Firstly, the payload is
positioned at different locations along its IB. Secondly, it
is considered to perform a continuous sliding motion along the
IB. The balancing of the robot has to be achieved during the
motion of the vehicle and the payload along the IB. An
external disturbance force is applied to the rod which
constitutes the IB in order to test the robustness of the
developed controllers. Investigations are carried out on the
effect of changing the level and duration of the disturbance
force, and changing the speed of the payload on the system
during the balancing mode. Simulation results of both control
algorithms are analyzed on a comparative basis. |
|
|
|
Title: |
Finite
difference analysis of curved deep beams on Winkler foundation |
Author (s): |
Adel A. Al-Azzawi
and Ali S. Shaker |
Abstract: |
This research deals with the linear elastic
behavior of curved deep beams resting on elastic foundations
with both compressional and frictional resistances. Timoshenko’s
deep beam theory is extended to include the effect of
curvature and the externally distributed moments under static
conditions. As an application to the distributed moment
generations, the problems of deep beams resting on elastic
foundations with both compressional and frictional restraints
have been investigated in detail. The finite difference method
was used to represent curved deep beams and the results were
compared with other methods to check the accuracy of the
developed analysis. Several important parameters are
incorporated in the analysis, namely, the vertical subgrade
reaction, horizontal subgrade reaction, beam width, and also
the effect of beam thickness to radius ratio on the
deflections, bending moments, and shear forces. The computer
program (CDBFDA) (Curved Deep Beam Finite Difference Analysis
Program) coded in Fortran-77 for the analysis of curved deep
beams on elastic foundations was formed. The results from this
method are compared with other methods exact and numerical and
check the accuracy of the solutions. Good agreements are
found, the average percentages of difference for deflections
and moments are 5.3% and 7.3%, respectively, which
indicate the efficiency of the adopted method for analysis. |
|
|
|
Title: |
Studies on
the production of caustic soda using solar powered diaphragm
cells |
Author (s): |
Babatope A.
Olufemi, Williams O. Ozowe and Ololade O. Komolafe |
Abstract: |
An experimental study was
performed using an array of solar panels to power asbestos and
non-asbestos diaphragm type electrolytic cells whose anodes
consisted of carbon rods and cathodes made up of stainless
steel plate for the electrolysis of a 25% w/w sodium chloride
solution, with the aim of producing caustic soda. The asbestos
and non-asbestos diaphragms served to hinder the formation of
unwanted substances as well as permit reasonable production of
the desired products. Quantitative analysis showed that the
quantity and concentration of caustic soda produced varied
with the current and voltage obtained from the solar panels
which were dependent upon the intensity of the sun on any
particular day and the length of time the panels were exposed
to sunlight. The asbestos and non-asbestos diaphragm cells
exhibited various characteristic performances, which is a
reflection of their design, fabrication, composition and
operation parameters. The non-asbestos diaphragm cell showed
similar trend with the conventional asbestos diaphragm cell
performances indicating higher yield of caustic soda per d.c.
Watt. The research served as an encouraging inquisitive
foundation into the possibility of producing caustic soda
directly from solar powered electrolytic diaphragm cells in
comparison with present conventional modes of electrochemical
production. |
|
|
|
Title: |
The effect of
two oxygenates on diesel engine emissions |
Author (s): |
P. Baskar, K.
Nanthagopal and T. Elango |
Abstract: |
Improvement of fuel properties
is essential for the suppression of diesel pollutant emissions
along with the optimization of combustion-related design
factors and exhaust after-treatment equipment. Studies
conducted in the past have shown that a significant reduction
of pollutants using oxygenates as alcohols, ethers, glycol
ethers, methylals and carbonates. The present paper
experimentally investigates the influence of oxygenated diesel
fuels on the emissions with the use of two different synthetic
oxygenated compounds namely Diphenyl ether (DPE) and Diet
helene glycol dim ethyl ether (DIGLYME). Several diesel fuel
blends, which contain 10% and 15% by volume of DPE and DIGLYME,
were prepared and the effect of these blends on emission
characteristics were studied on a twin cylinder direct
injection diesel engine. The blends were tested under the
different load conditions and the results shows, there is
significant reduction of engine emissions of hydrocarbon and
carbon mono oxide emissions while the coefficient of light
absorption of smoke opacimeter decreases by about 50% for
DPE10, DIGLYME10 blend and it was reduced by about 60%for
DPE15 and DIGLYME15 blend . |
|
|
|
Title: |
Peristaltic
pumping of a Jeffrey fluid in a porous tube |
Author (s): |
S. V. H. N.
Krishna Kumari P., M. V. Ramana Murthy, Y. V. K. Ravi Kumar and
S. Sreenadh |
Abstract: |
Peristaltic pumping of a Jeffrey
fluid in a porous tube is studied under long wavelength and
low Reynolds number assumptions. Solutions are obtained by
using Beavers - Joseph and Saffman boundary conditions. The
effect of various parameters on the pumping characteristics is
studied and discussed through graphs. Comparison of various
wave forms (namely sinusoidal, triangular and trapezoidal) on
the flow is discussed. |
|
|
|
Title: |
Selective
modal space control approach for smart composite cylindrical
shell structure |
Author (s): |
G. Vijaya Kumar, K. Mohana Rao, J. Suresh Kumar and S. Raja |
Abstract: |
This paper presents selective
modal space control approach (SMSC) to address the vibration
suppression of critical elastic modes of composite cylindrical
shell, using collocated/non collocated sensor/actuator. A four
node, electro-mechanically coupled field consistent facet
shell finite element is used to model the shell vibration.
Subsequently, a linear quadratic regulator (LQR) is designed
in modal domain to conduct the vibration control simulation
studies. The results of active vibration control (AVC) of a
laminated composite cylindrical shell, equipped with
piezoelectric composite actuators i.e., Macro Fiber Composite
(MFC) and PZT sensors are presented. The effectiveness of MFC
in controlling shell vibration is evaluated. An effort has
been made to addresses the question of whether performance is
affected by the collocation/non-collocation of the sensors and
actuator. |
|
|
|
Title: |
Fibre
reinforced concrete using domestic waste plastics as fibres |
Author (s): |
R. Kandasamy
and R. Murugesan |
Abstract: |
Fibre Reinforced Concrete (FRC)
is a composite material consisting of cement based matrix with
an ordered or random distribution of fibre which can be Steel,
Nylon, Polythene etc. The addition of steel fibre increases
the properties of concrete, viz., flexural strength, impact
strength and shrinkage properties to name a few. A number of
papers have already been published on the use of steel fibres
in concrete and a considerable amount of research has been
directed towards studying the various properties of concrete
as well as reinforced concrete due to the addition of steel
fibres. Hence, an attempt has been made in the present
investigations to study the influence of addition of polythene
fibers (domestic waste plastics) at a dosage of 0.5% by weight
of cement. The properties studied include compressive strength
and flexural strength. The studies were conducted on a M20 mix
and tests have been carried out as per recommended procedures
of relevant codes. The results are compared and conclusions
are made. |
|
|
|
Title: |
Impact of a
concrete room on the performance of cellular telephone
communications for low bit rate applications |
Author (s): |
M. S. H. Al-Salameh and Y. S. A. Al-Mashhadani |
Abstract: |
In this paper, a new propagation
model, in macro-cellular wireless communication systems, is
derived. The model characterizes the base station to mobile
radio channel when the propagated signal is being obstructed
by lossy concrete room in which the mobile phone moves. The
analysis is performed by using ray-tracing techniques combined
with uniform theory of diffraction (UTD), in addition to using
a UTD modified heuristic diffraction coefficient for
non-perfectly conducting wedges. The maximum considered ray
reflections are three, single and double diffractions are also
considered in this study. Therefore, all expected significant
ray contributions in multipath channel are included. These
rays include direct, reflected, refracted and diffracted
paths, or any combination of the mentioned paths. The
mathematical propagation model is derived, after which the
model is implemented by different computer programs written in
Matlab. For low bit rate applications (narrowband systems),
the attenuation and fading of the propagated signal are the
main causes of signal degradation. Therefore, the signal
strength, as a function of mobile location inside the room,
was computed for base station with an antenna array. The
depolarization effect on propagated signal as well as the
cumulative distribution function (CDF) and probability density
function (PDF), that are useful for statistical prediction
models, are studied. Details of the present model that may
facilitate implementation are given. Comparison with
measurements revealed acceptable agreement. The results of
this research work should be useful in radio link design of
macro-cellular land mobile communication systems. |
|
|
|
Title: |
Ultra-short
laser pulse interaction with nickel films |
Author (s): |
E.
Annan and H. V. Snelling |
Abstract: |
Laser induced forward transfer
method involves three sequence of events (i) laser pulse heats
up the front surface of the film until it melts (ii) the melt
front propagates through the film until it reaches the back
surface and finally (iii) at or close to melt-through the
metal vapour pressure at the front propels the molten film to
the substrate. Many authors have shown potentials of this
method in direct writing and photo-mask repair. In this paper,
we present laser induced forward technique applied to nickel
films of thicknesses 98nm, 200nm and 322nm by using Ti:
Sapphire femtosecond laser. Direct ablation of nickel films
resulted in threshold energy values 0.03µJ, 0.56µJ and 2.49µJ
for film thickness 98nm, 200nm and 322nm respectively.
Backside ablation threshold energies were found to be 0.37µJ,
3.05µJ, and 4.55 µJ for 98nm, 200nm, and 322nm film
thicknesses respectively. The feasibility of the transfer
process is also demonstrated on nickel film on silicon wafer.
Elevated features observed on films during ablation are
explained. |
|
|
|
Title: |
Experimental
study on D I diesel engine performance and emission
characteristics (NOx) with COME- diesel blends |
Author (s): |
P.
Venkateswara Rao and M. Lokanadha Rao |
Abstract: |
The biodiesel from edible oils
is non-toxic, biodegradable and renewable alternate fuel that
can be used as a substitute for diesel in diesel engines. The
objective of present work is to study performance and emission
characteristics of single cylinder, direct injection diesel
engine with coconut oil methyl ester (COME) and blends with
diesel in varying proportions. Experiments were conducted when
the engine fuelled with pure diesel and the blends of diesel-
COME by volume for full load range. The exhaust conditions
were measured using exhaust gas analyzer similarly AVL smoke
meter for measuring smoke density. Results were compared
graphically in performance of the engine for specific fuel
consumption, brake thermal efficiency, exhaust temperatures
and in exhaust emissions for concentrations of NOx
and smoke density. |
|
|
|
Title: |
Voltage sag
influence on fatigue life of the drivetrain of fixed speed wind
turbines |
Author (s): |
Badrinath Veluri, David Santos Martin and Henrik Myhre Jensen |
Abstract: |
Occurrence of voltage sags due
to electrical grid faults and other network disturbances
generate transients of the generator electromagnetic torque
which result in significant high stresses and noticeable
vibrations for the wind turbine mechanical system and may also
have a detrimental effect on the fatigue life of important
drivetrain components. The high penetration of wind energy in
the electrical grids demands new requirements for the
operation of wind energy conversion systems. Although fixed
speed wind turbine technology is nowadays replaced by variable
speed wind turbines. In some countries (Spain and Germany)
with high wind energy penetration it is mandatory or under
bonus to retrofit these fixed speed wind turbines and provide
ride through capability. An electro-mechanical model is built
to simulate the grid disturbances that easily excite the
asynchronous generators poorly damped by the stator flux
oscillations which cause high transients of the generator
electromagnetic torque. This paper focuses in estimating the
resulting significant stresses transients due to the
electromagnetic torque transients, which transmits to the wind
turbine mechanical system that may have a detrimental effect
on the fatigue life of drivetrain components. The capability
to simulate these phenomena is a novel aspect in the present
effort. |
|
|
|
Title: |
Approximate
method to singularity behaviour of nonlinear problems in fluid
dynamics |
Author (s): |
M. S.
Alam and R. A. Rouf |
Abstract: |
The singularity behaviour of
nonlinear problems in fluid dynamics is numerically
investigated. The behaviour of the first painleve transcendent is introduced as a model
problem. Then the laminar unsteady flow of a viscous fluid
away from a plane stagnation point is studied as second model
problem. We have applied approximate method to these problems
with the aid of algebraic programming language MAPLE. Analysis
based on approximate method suggests that the convergence of
the series of shear stress is limited by a pair of
singularities. The location and nature of the singularities in
the complex plane are presented. The shear stress in real
plane is also depicted graphically. |
|
|
|
Title: |
Effects of
different pretreatments on drying characteristics of banana
slices |
Author (s): |
Abano E. E. and
Sam-Amoah L. K. |
Abstract: |
The effects of different
pretreatments and temperature on the drying characteristics of
ripe Gros Michel banana slices were investigated. 5 and 7 mm
thick slices of bananas were pretreated with four different
pretreatments such as ascorbic acid, lemon juice, salt
solution, honey dip and a control for 10 minutes, each
replicated three times. Pretreated banana slices were dried in
a cabinet oven dryer using a completely randomized design at
60 and 70°C and their drying characteristics such as rate of
drying, moisture diffusivity, re-hydration ratio, and
coefficient of re-hydration were studied. The moisture content
of the fresh ripe bananas for both the untreated and treated
samples was found to be in the range of 75-77% (w b) which
reduced to 16.8 to 27% after oven drying for various
thicknesses and temperatures of air drying for 16 hours. The
moisture diffusivity during oven drying varied from 7.89E-5 to
14.94E-5 m/s2, and increased with drying air temperature. The
5 mm thick slices at a drying air temperature of 70 dried
better than the others and resulted in about 13% savings in
time. The minimum re-hydration ratio of 1.215 was obtained for
7 mm thick slices treated with ascorbic acid and the maximum
re-hydration ratio of 1.716 was obtained for lemon juice
samples. This means that the lemon juice treated dried bananas
will reconstitute more moisture when exposed to air. |
|
|
|
|
|
|
| |