Title: |
Risk based
assessment for offshore jacket platform in Niger delta, Nigeria
(corrosion and fatigue hazards) |
Author (s): |
M. A. Salau,
D. E. Esezobor and M. F. Omotoso |
Abstract: |
Offshore structures are imperative for
uninterrupted crude oil production which is the main stay of
Nigerian economy. Fatigue and corrosion have been identified
to be the most prevalent structural hazards in offshore
environment. Jacket platform may be exposed to certain
seawater wave which often leads to structural failure,
particularly when the platform is subjected to corrosion and
fatigue hazards. Therefore, corrosion and fatigue damage
requires detail evaluation to prevent jacket platform from
untimely failure. Risk based assessment method has been
identified as the appropriate tool to determine the risk
levels associated with component damages acted upon by several
hazards with different scenarios. The results of this work
revealed that simultaneously corroded and fatigued components
exhibit unacceptable risk level and is the appropriate
limiting damage scenario for marine structures underwater
inspection. This technique is proved to be accurate and the
most appropriate procedure for management of hazards, safety
and environmental protection. |
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Title: |
Investigation
of local polymer (cassava starches) as a substitute for imported
sample in viscosity and fluid loss control of water based
drilling mud |
Author (s): |
Ademiluyi
Taiwo, Joel O. F. and Amuda A. Kazeem |
Abstract: |
Comparative study of local polymer (cassava)
with an imported type in controlling viscosity and fluid loss
in water-based mud was investigated in this study. Five
different cassava starches were tested as viscosifiers and
fluid loss control additives in water based mud and compared
with Barazan D, an imported sample. Experimental results
indicated that at same concentration, the imported sample had
higher rheological properties compared with the local samples.
However, some of the newly developed local starch products
(with high amylose content and high water absorption capacity)
have similar or better filtration control properties than the
imported sample. Although the viscosity of the drilling fluid
produced from the local starches were lower than that of the
imported type, with proper quality control efforts of the
local samples, they could be used as a substitute for imported
grade for exploration and exploitation of oil and gas in
Nigeria. It is also hoped that this work will open new market
for non-food use of starches from cassava and thus expected to
provide economic benefit to Nigerian farmers and a way forward
to actualize vision 20-2020 agenda. |
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Title: |
Three phase
fault diagnosis based on RBF neural network optimized by PSO
algorithm |
Author (s): |
M. Sivakumar
and R. M. S. Parvathi |
Abstract: |
The present paper proposes a fault diagnosis
methodology of three phase inverter circuit base on radial
basis function (RBF) artificial neural network trained by
particle swarm optimization (PSO) algorithm. Using the
appropriate stimulus signal, fault features are extracted from
efficient points in frequency response of the circuit
directly, and then a fault dictionary is created by collecting
signatures of different fault conditions. Trained by the
examples contained in the fault dictionary, the RBF neural
network optimized by PSO has been demonstrated to provide
robust diagnosis to the difficult problem of soft faults in
three phase inverter circuits. The experimental result shows
that the proposed technique is succeeded in diagnosing and
locating faults effectively. |
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Title: |
Analytical
investigation of prestressed concrete structures incorporating
combined post-tensioned and post-compressed reinforcements |
Author (s): |
Adekunle
Philips Adewuyi and Shodolapo Oluyemi Franklin |
Abstract: |
Although strengthening of structures by
post-tensioning is much more common in practice, the authors
did locate innovative literature on the theory and
applications of post-compression which form the basis for this
study. This work analytically assesses the behaviour and
criteria for optimal performance of prestressed concrete
structures under the combined actions of post-tensioning and
post-compression. Magnel type diagrams are also developed to
show the feasible solution regions for different loading
conditions. The findings revealed that the prestressing forces
in the post-tensioned tendons are independent of the
eccentricity ratio, but increases perfectly curvilinearly up
to prestressing ratio of 0.7 beyond which the technique
becomes impracticable. On this basis, there is a realistic
reduction of 50 percent in the eccentricity and possibly the
overall depth of the concrete section over the conventional
technique. This qualifies this structural innovation as a
reliable candidate for long span structures. |
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Title: |
Variation of
ultimate bearing capacity of unsaturated clay with suction |
Author (s): |
Anuchit
Uchaipichat and Ekachai Man-koksung |
Abstract: |
A spread footing is sometimes selected for a
shallow foundation design on clay layers. Its ultimate bearing
capacity usually fluctuates with seasonal changes. Thus, a
series of laboratory bearing tests was performed on compacted
kaolin specimens with different values of matric suction,
which relates to water content. The values of matric suction
within the specimens were measured using the contact filter
paper technique. All tests were performed after measurement of
matric suction by penetrating the rod on the specimen surface
until failure. The test results on the normal scale plot show
an increase in ultimate bearing capacity with increasing
matric suction for all ranges of suction. The increase rate is
high at low suction range and decreases with increasing
suction. In the semi-log scale plot, the curve of results can
be divided into two parts at the point corresponding to the
point separating saturated from unsaturated state. |
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Title: |
The effects
of aspect ratio on heat transfer across air layers in a
slot-ventilated wall cavity |
Author (s): |
Akin Odewole
and Rodger Edwards |
Abstract: |
The effects of aspect ratio on heat transfer
across air layers (Pr ≈ 0.71) in a slot-ventilated wall cavity
were numerically studied in this paper for Rayleigh number, Raw
in the range of 1.4x105 to 12.0x105
using the Reynolds-Averaged Navier-Stokes (RANS) methodology.
Large horizontal aspect ratios of 40 and 60 for the wall
cavities investigated enable a two-dimensional approximation
to be employed in the study of the heat transfer
characteristics of the air layers over a range of temperature
that is representative of extreme winter and summer conditions
in the study. Using the RANS-based methodology, a small
temperature difference between the front and back wall of the
cavity reduces the cost of heating required for remediating
moisture and condensation in the wall cavity during the winter
in contrast to transferring a similar amount of energy using a
large temperature difference. A maximum deviation of about
5.11% obtained between the Nusselt number of the cavity flow
at a vertical aspect ratio,
of 40 and 60 shows that an increase in the
vertical aspect ratio of the cavity does not significantly
affect the heat transfer rate across the air layers.
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Title: |
The friction of different floor
finish-reducing indoor slips and falls |
Author (s): |
Yasser M. El-Sherbiny |
Abstract: |
Slips, and
falls can happen in any part of the flat or home, but is more
common on stairs and in the kitchens and bathrooms. The
present paper investigates the friction between rubber and
leather footwear on one side and different flooring materials
on the other side. Ceramics, Concrete and Granite tiles are
tested. Both dry and wet contamination agents are considered.
The ultimate results are set limits and measures, for walking
speeds and step size, which may guide the approach of reducing
indoor slips and fall injuries. |
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Title: |
An efficient
space-time coding for wireless communications with offset 4 -
phase shift keying |
Author (s): |
S. Nagarani
and C. V. Seshaiah |
Abstract: |
Channel Capacity has long been a block in
wireless communications. Various approaches are present in the
literatures which are very effective in enhancing signal
reception quality in fading channels. Various multiple antenna
approaches have been used in wireless communications to combat
the fading effect, which enhances both the channel capacity
and performance greatly. Transmit Antenna Selection (TAS) is a
well-known approach to improve diversity in multi-input
multi-output (MIMO) communication is. But the main drawback of
TAS is that, it is very sensitive to feedback errors. Hence,
Space-Time Coding (STC) is a communication approach for
wireless systems that inhabit multiple transmit antennas and
single or multiple receives antennas. In this paper,
Space-Time coding (STC) is employed in MIMO signaling scheme
which helps in providing better knowledge at the receiver and
no knowledge at the transmitter. Space-time trellis codes,
space-time block codes and Space-Time Differential Coding are
the STCs used in this paper. In this approach, the performance
of the STC code is improved by the proposed Extended Balanced
Space-Time Block Codes (EBSTBC). Also, this paper uses Offset
4- Phase-Shift Keying (O4-PSK) instead of 4- Phase-Shift
Keying (4-PSK). This will help in reducing the bit error rate.
The experiment is done with different PSK and with different
bit rates. When the frame error probability is evaluated, the
proposed EBSTBC system shows lesser error probability when
compared to the previous STC codes. |
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Title: |
Effects of
thermal properties on temperature and moisture profiles and the
performance of PCC pavements |
Author (s): |
Upender
Kodide M.S. |
Abstract: |
To understand the effects of thermal properties
on temperature and the moisture profile in Portland cement
concrete (PCC) pavements, an Enhanced Integrated Climatic
Model (EICM) analysis was performed for a typical PCC pavement
section in Louisiana. The EICM analysis showed that the
temperature in the middle layer of PCC pavement decreased as
thermal conductivity increased, and the temperature remained
constant for higher thermal conductivity values. Temperature
was measured at several depths of a concrete block embedded in
soil and was compared to the temperature profile predicted by
the EICM. Measured temperatures inside the concrete block were
higher than the temperatures predicted by the EICM. The
measured temperatures reached a peak hour temperature gradient
on the hottest time of day, but the EICM model did not predict
the peak hour temperature gradient. MEPDG analysis was
performed to estimate the effect of thermal properties on the
distress of PCC pavements. From the analysis it was found that
thermal cracking increased with the decrease of thermal
conductivity. It was also noticed that an Integrated Climatic
Model (ICM) stability failure occurred for a set of thermal
conductivity and heat capacity readings in the MEPDG analysis.
A passing line is proposed to separate the ICM stability
passing zone and failure zone. |
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Title: |
The effects
of temperature and blending on the specific gravity and
viscosity of Jatropha methyl ester |
Author (s): |
Kimilu R. K., Nyangaya J. A. and Onyari J. M. |
Abstract: |
The specific
gravity and viscosity of biodiesel fuels are key properties in
determining the suitability for use of such fuels in diesel
engines. Though generally higher than those of #2 diesel fuel
(DF2), they have been mostly reduced by blending with DF2 and
preheating to achieve comparable values as DF2. The objectives
of this study were to investigate the effects of temperature
and blending on specific gravity and viscosity of Jatropha
methyl ester, and also investigate the effect of modifying
Clements blending equation by substituting volume fraction for
mass fraction. Correlation models were developed to predict
the variation of specific gravity and viscosity with both
temperature and % biodiesel in a blend. Blends of Jatropha
methyl ester (JME) and DF2 on volume basis were prepared and
investigated in the temperature range 15-60°C together with
the pure fuels. Blends B20, B35, B50 and B75 were made.
Specific gravity was determined using specific gravity method
whereas viscosity was evaluated was determined using the
Ostwald viscometer. Specific gravity of JME was found to be
generally 4.83% higher than that of DF2. Blending with DF2
lowered the specific gravity significantly, and a correlation
model was developed for use to approximate the specific
gravity of any JME-DF2 fuel blend. Preheating the fuels
lowered the specific gravity as temperature increased.
Correlation models were developed to predict the specific
gravity of the test fuels as function of both temperature and
amount of JME in the blend. Calculating specific gravity using
the Specific gravity blending equation proposed by Clements
was found to give results within ± 0.5% of the measured values
with mass fraction replaced by volume fraction. The viscosity
of JME was found to be 42.09% higher than that of DF2.
Blending with DF2 resulted in significant viscosity reduction,
which varied linearly with the amount of DF2 in the blend.
Correlation models were proposed to approximate the viscosity
of any blend as a function temperature in the range from 15°C
to 60°C, and as a function of % biodiesel. Results showed that
blends with up to 50% JME conformed to both specific gravity
and viscosity without need of preheating. |
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Title: |
Bending
analysis of composite laminated plates using higher-order shear
deformation theory with zig-zag function |
Author (s): |
T. Dharma
Raju and J. Suresh Kumar |
Abstract: |
In this paper an analytical procedure is
developed, to investigate the bending characteristics of
laminated composite plates based on higher order shear
displacement model with zig-zag function. This zig-zag
function improves slope discontinuities at the interfaces of
laminated composite plates. The equation of motion is obtained
using the dynamic version of Hamilton’s principle. The
solutions are obtained using Navier’s and numerical methods
for anti-symmetric cross-ply and angle-ply laminates with a
specific type of simply supported boundary conditions SS-1 and
SS-2 respectively. In this paper the Numerical results are
presented for bending of anti-symmetric cross-ply and
angle-ply laminated plates. All the solutions presented are
close agreement with the theory of elasticity and closed form
solutions available in the literature. |
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Title: |
Review and
modeling the methods of radius estimating techniques for
horizontal curves |
Author (s): |
Asma Th.
Ibraheem and Waseem Wathiq Hammodat |
Abstract: |
The establishment of figures on
the ground is an important task of the field surveyor, not
only in engineering construction but also in cadastral
surveying. It is a relatively easy task to peg out the
boundary of a rectangular concrete slab, but considerably more
difficult to establish the location of points along an
elevated curved highway. Thus Radii measurements are important
for many reasons such as: Setting curve advisory speeds;
predicting vehicle operating speeds; Spacing curve delineation
treatments such as post-delineators, chevrons, and
raised retro reflective pavement markers; performing highway
safety audits; and evaluating traffic crashes. Many groups,
including transportation agencies, accident investigators, and
transportation researchers, would find an accurate, quick, and
safe method to estimate the radius of horizontal curves
particularly useful. The present work explains the ten methods
of estimating radius; a)
Basic ball bank indicator (BBI),
b) Advanced
BBI,
c) Chord
length,
d) Compass,
e) Field
survey,
f) Global
Positioning System (GPS) unit,
g)
Lateral acceleration,
h)
Plan sheet,
i) Speed
advisory plate and
j) Vehicle
yaw rate.
Also each method was programmed
as a software named RET (Radius Estimating Techniques). It
represent of a collection of subroutines for each method. This
program is written in Mathematical Computer Aided Design
language (MCAD). It also includes a subroutine written in
Visual BASIC language for calculating the super elevation of a
designed or existing horizontal curves.
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Title: |
Seismic
strengthening of partially infill RC buildings using brick
inserts- Experimental investigation on 3D model structure |
Author (s): |
R. Suresh
Babu, R. Venkatsubramani and G. S. Venkatasubramani |
Abstract: |
In partially infill structures,
columns with short gap will behave as short column during
earthquake and attract larger forces due to inplane stiffness
of the infills and can damage the column seriously due to
excessive shear forces, which is known as captive column
effect. Since it is complex to consider the contribution of
strength and stiffness of these partial infills, structure is
analysed and designed as bare frames. But actual structural
behaviour for partial infill structures during earthquake is
with captive column effect. One of the major failure of
structure during earthquake is due to captive column effect.
Several literature and research papers were published in the
area of seismic strengthening of existing structures. To
overcome this type of failure in the structure due to this
effect, it should be ensure that the shear forces should flow
smoothly by means of a strut action. This is achieved by
inserting a brick masonry adjacent to columns in the partially
infill areas in order to ensure shear flow is smooth and thus
improving the lateral capacity of the structure. An
experimental investigation was carried out in the ‘3D’ model
structure to study the effect of this captive column effect
and to reduce this effect by introducing brick insert adjacent
to column face. This study clearly indicates that with the
help of brick insert, captive column effect is reduced,
lateral capacity increases and thus preventing critical damage
to the structure by the seismic load during earthquake. A
Comparative study was made between experimental and analytical
method by using - ANSYS 10 and the values are found to be
nearly equal. |
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