Abstract: Factors affecting construction unit cost vary
depending on a country’s political, economic, social and
technological inclinations. Factors affecting construction costs have
been studied from various perspectives. Analysis of cost factors
requires an appreciation of a country’s practices. Identified cost
factors provide an indication of a country’s construction economic
strata. The purpose of this paper is to identify the essential factors
that affect unit cost estimation and their breakdown using artificial
neural networks. Twenty five (25) identified cost factors in road
construction were subjected to a questionnaire survey and employing
SPSS factor analysis the factors were reduced to eight. The 8 factors
were analysed using neural network (NN) to determine the
proportionate breakdown of the cost factors in a given construction
unit rate. NN predicted that political environment accounted 44% of
the unit rate followed by contractor capacity at 22% and financial
delays, project feasibility and overhead & profit each at 11%. Project
location, material availability and corruption perception index had
minimal impact on the unit cost from the training data provided.
Quantified cost factors can be incorporated in unit cost estimation
models (UCEM) to produce more accurate estimates. This can create
improvements in the cost estimation of infrastructure projects and
establish a benchmark standard to assist the process of alignment of
work practises and training of new staff, permitting the on-going
development of best practises in cost estimation to become more
effective.
Abstract: The thermal conductivity of a fluid can be
significantly enhanced by dispersing nano-sized particles in it, and
the resultant fluid is termed as "nanofluid". A theoretical model for
estimating the thermal conductivity of a nanofluid has been proposed
here. It is based on the mechanism that evenly dispersed
nanoparticles within a nanofluid undergo Brownian motion in course
of which the nanoparticles repeatedly collide with the heat source.
During each collision a rapid heat transfer occurs owing to the solidsolid
contact. Molecular dynamics (MD) simulation of the collision
of nanoparticles with the heat source has shown that there is a pulselike
pick up of heat by the nanoparticles within 20-100 ps, the extent
of which depends not only on thermal conductivity of the
nanoparticles, but also on the elastic and other physical properties of
the nanoparticle. After the collision the nanoparticles undergo
Brownian motion in the base fluid and release the excess heat to the
surrounding base fluid within 2-10 ms. The Brownian motion and
associated temperature variation of the nanoparticles have been
modeled by stochastic analysis. Repeated occurrence of these events
by the suspended nanoparticles significantly contributes to the
characteristic thermal conductivity of the nanofluids, which has been
estimated by the present model for a ethylene glycol based nanofluid
containing Cu-nanoparticles of size ranging from 8 to 20 nm, with
Gaussian size distribution. The prediction of the present model has
shown a reasonable agreement with the experimental data available
in literature.
Abstract: We present a trigonometric scheme to approximate a
circular arc with its two end points and two end tangents/unit
tangents. A rational cubic trigonometric Bézier curve is constructed
whose end control points are defined by the end points of the circular
arc. Weight functions and the remaining control points of the cubic
trigonometric Bézier curve are estimated by variational approach to
reproduce a circular arc. The radius error is calculated and found less
than the existing techniques.
Abstract: Safety is one of the most important considerations
when buying a new car. While active safety aims at avoiding
accidents, passive safety systems such as airbags and seat belts
protect the occupant in case of an accident. In addition to legal
regulations, organizations like Euro NCAP provide consumers with
an independent assessment of the safety performance of cars and
drive the development of safety systems in automobile industry.
Those ratings are mainly based on injury assessment reference values
derived from physical parameters measured in dummies during a car
crash test.
The components and sub-systems of a safety system are designed
to achieve the required restraint performance. Sled tests and other
types of tests are then carried out by car makers and their suppliers
to confirm the protection level of the safety system. A Knowledge
Discovery in Databases (KDD) process is proposed in order to
minimize the number of tests. The KDD process is based on the
data emerging from sled tests according to Euro NCAP specifications.
About 30 parameters of the passive safety systems from different data
sources (crash data, dummy protocol) are first analysed together with
experts opinions. A procedure is proposed to manage missing data
and validated on real data sets. Finally, a procedure is developed to
estimate a set of rough initial parameters of the passive system before
testing aiming at reducing the number of tests.
Abstract: Solar air heater is a type of heat exchanger which
transforms solar radiation into heat energy. The thermal performance
of conventional solar air heater has been found to be poor because of
the low convective heat transfer coefficient from the absorber plate to
the air. It is attributed to the formation of a very thin boundary layer
at the absorber plate surface commonly known as viscous sub-layer.
Thermal efficiency of solar air heater can be improved by providing
the artificial roughness on absorber plate is the most efficient
technique. In this paper an attempt is made to provide artificial
roughness by incorporating inclined multiple V-ribs in the underside
of the absorber plate. 60˚V – ribs are arranged inclined to the
direction of air flow. Performance of collector estimated theoretically
and experimentally. Results of the investigation reveal that thermal
efficiency of collector with multiple V-ribs increased by 14%.
Abstract: Several of the practical industrial control processes are
multivariable processes. Due to the relation amid the variables
(interaction), delay in the loops, it is very intricate to design a
controller directly for these processes. So first, the interaction of the
variables is analyzed using Relative Normalized Gain Array
(RNGA), which considers the time constant, static gain and delay
time of the processes. Based on the effect of RNGA, relative gain
array (RGA) and NI, the pair (control configuration) of variables to
be controlled by decentralized control is selected. The equivalent
transfer function (ETF) of the process model is estimated as first
order process with delay using the corresponding elements in the
Relative gain array and Relative average residence time array
(RARTA) of the processes. Secondly, a decentralized Proportional-
Integral (PI) controller is designed for each ETF simply using
frequency response specifications. Finally, the performance and
robustness of the algorithm is comparing with existing related
approaches to validate the effectiveness of the projected algorithm.
Abstract: The objective of meta-analysis is to combine results
from several independent studies in order to create generalization
and provide evidence base for decision making. But recent studies
show that the magnitude of effect size estimates reported in many
areas of research significantly changed over time and this can
impair the results and conclusions of meta-analysis. A number of
sequential methods have been proposed for monitoring the effect
size estimates in meta-analysis. However they are based on statistical
theory applicable only to fixed effect model (FEM) of meta-analysis.
For random-effects model (REM), the analysis incorporates the
heterogeneity variance, τ 2 and its estimation create complications.
In this paper we study the use of a truncated CUSUM-type test with
asymptotically valid critical values for sequential monitoring in REM.
Simulation results show that the test does not control the Type I error
well, and is not recommended. Further work required to derive an
appropriate test in this important area of applications.
Abstract: A key issue in seismic risk analysis within the context
of Performance-Based Earthquake Engineering is the evaluation of
the expected seismic damage of structures under a specific
earthquake ground motion. The assessment of the seismic
performance strongly depends on the choice of the seismic Intensity
Measure (IM), which quantifies the characteristics of a ground
motion that are important to the nonlinear structural response. Several
conventional IMs of ground motion have been used to estimate their
damage potential to structures. Yet, none of them has been proved to
be able to predict adequately the seismic damage. Therefore,
alternative, scalar intensity measures, which take into account not
only ground motion characteristics but also structural information
have been proposed. Some of these IMs are based on integration of
spectral values over a range of periods, in an attempt to account for
the information that the shape of the acceleration, velocity or
displacement spectrum provides. The adequacy of a number of these
IMs in predicting the structural damage of 3D R/C buildings is
investigated in the present paper. The investigated IMs, some of
which are structure specific and some are non structure-specific, are
defined via integration of spectral values. To achieve this purpose
three symmetric in plan R/C buildings are studied. The buildings are
subjected to 59 bidirectional earthquake ground motions. The two
horizontal accelerograms of each ground motion are applied along
the structural axes. The response is determined by nonlinear time
history analysis. The structural damage is expressed in terms of the
maximum interstory drift as well as the overall structural damage
index. The values of the aforementioned seismic damage measures
are correlated with seven scalar ground motion IMs. The comparative
assessment of the results revealed that the structure-specific IMs
present higher correlation with the seismic damage of the three
buildings. However, the adequacy of the IMs for estimation of the
structural damage depends on the response parameter adopted.
Furthermore, it was confirmed that the widely used spectral
acceleration at the fundamental period of the structure is a good
indicator of the expected earthquake damage level.
Abstract: In oases, the surface water resources are becoming
increasingly scarce and groundwater resources, which generally have
a poor quality due to the high levels of salinity, are often
overexploited. Water saving have therefore become imperative for
better oases sustainability. If drip irrigation is currently recommended
in Morocco for saving water and valuing, its use in the sub-desert
areas does not keep water safe from high evaporation rates. An
alternative to this system would be the use of subsurface drip
irrigation. This technique is defined as an application of water under
the soil surface through drippers, which deliver water at rates
generally similar to surface drip irrigation. As subsurface drip
irrigation is a recently introduced in Morocco, a better understanding
of the infiltration process around a buried source, in local conditions,
and its impact on plant growth is necessarily required. This study
aims to contribute to improving the water use efficiency by testing
the performance of subsurface irrigation system, especially in areas
where water is a limited source. The objectives of this research are
performance evaluation in arid conditions of the subsurface drip
irrigation system for young date palms compared to the surface drip.
In this context, an experimental test is installed at a farmer’s field in
the area of Erfoud (Errachidia Province, southeastern Morocco),
using the subsurface drip irrigation system in comparison with the
classic drip system for young date palms. Flow measurement to
calculate the uniformity of the application of water was done through
two methods: a flow measurement of drippers above the surface and
another one underground. The latter method has also helped us to
estimate losses through evaporation for both irrigation techniques. In
order to compare the effect of two irrigation modes, plants were
identified for each type of irrigation to monitor certain agronomic
parameters (cumulative numbers of palms and roots development).
Experimentation referred to a distribution uniformity of about 88%;
considered acceptable for subsurface drip irrigation while it is around
80% for the surface drip irrigation. The results also show an increase
in root development and in the number of palm, as well as a
substantial water savings due to lower evaporation losses compared
to the classic drip irrigation.
The results of this study showed that subsurface drip irrigation is
an efficient technique, which allows sustainable irrigation in arid
areas.
Abstract: Currently, seismic probabilistic risk assessments
(SPRA) for nuclear facilities use In-Structure Response Spectra
(ISRS) in the calculation of fragilities for systems and components.
ISRS are calculated via dynamic analyses of the host building
subjected to two orthogonal components of horizontal ground
motion. Each component is defined as the median motion in any
horizontal direction. Structural engineers applied the components
along selected X and Y Cartesian axes. The ISRS at different
locations in the building are also calculated in the X and Y directions.
The choice of the directions of X and Y are not specified by the
ground motion model with respect to geographic coordinates, and are
rather arbitrarily selected by the structural engineer. Normally, X and
Y coincide with the “principal” axes of the building, in the
understanding that this practice is generally conservative. For SPRA
purposes, however, it is desirable to remove any conservatism in the
estimates of median ISRS. This paper examines the effects of the
direction of horizontal seismic motion on the ISRS on typical nuclear
structure. We also evaluate the variability of ISRS calculated along
different horizontal directions. Our results indicate that some central
measures of the ISRS provide robust estimates that are practically
independent of the selection of the directions of the horizontal
Cartesian axes.
Abstract: The knowledge of biodiesel density over large ranges
of temperature and pressure is important for predicting the behavior
of fuel injection and combustion systems in diesel engines, and for
the optimization of such systems. In this study, cottonseed oil was
transesterified into biodiesel and its density was measured at
temperatures between 288 K and 358 K and pressures between 0.1
MPa and 30 MPa, with expanded uncertainty estimated as ±1.6 kg⋅m-
3. Experimental pressure-volume-temperature (pVT) cottonseed data
was used along with literature data relative to other 18 biodiesels, in
order to build a database used to test the correlation of density with
temperarure and pressure using the Goharshadi–Morsali–Abbaspour
equation of state (GMA EoS). To our knowledge, this is the first that
density measurements are presented for cottonseed biodiesel under
such high pressures, and the GMA EoS used to model biodiesel
density. The new tested EoS allowed correlations within 0.2 kg·m-3
corresponding to average relative deviations within 0.02%. The built
database was used to develop and test a new full predictive model
derived from the observed linear relation between density and degree
of unsaturation (DU), which depended from biodiesel FAMEs
profile. The average density deviation of this method was only about
3 kg.m-3 within the temperature and pressure limits of application.
These results represent appreciable improvements in the context of
density prediction at high pressure when compared with other
equations of state.
Abstract: In this research article a comprehensive investigation
has been carried out to determine the effect of thermal cycle on
temperature dependent process parameters developed during gas
tungsten arc (GTA) welding of high carbon (AISI 1090) steel butt
joints. An experiment based thermal analysis has been performed to
obtain the thermal history. We have focused on different
thermophysical properties such as thermal conductivity, heat transfer
coefficient and cooling rate. Angular torch model has been utilized to
find out the surface heat flux and its variation along the fusion zone as
well as along the longitudinal direction from fusion boundary. After
welding and formation of weld pool, heat transfer coefficient varies
rapidly in the vicinity of molten weld bead and heat affected zone. To
evaluate the heat transfer coefficient near the fusion line and near the
rear end of the plate (low temperature region), established correlation
has been implemented and has been compared with empirical
correlation which is noted as coupled convective and radiation heat
transfer coefficient. Change in thermal conductivity has been
visualized by analytical model of moving point heat source. Rate of
cooling has been estimated by using 2-dimensional mathematical
expression of cooling rate and it has shown good agreement with
experimental temperature cycle. Thermophysical properties have been
varied randomly within 0 -10s time span.
Abstract: Marine Protected Areas can benefit from nature based
tourism, monitoring environmental impacts and also become target
for human presence. From more than 3 million tourists visiting
Cozumel Island every year, an average of 2,8 million arrive by cruise
ship, and 41% are estimated to have motivation for water activities.
The destination is relying so much on the tourism activity, that scuba
diving and snorkeling in the National Park Reef of Cozumel sustain
the major economic activity. In order to achieve the sustainable
development indicator designed for regional environmental
development, the PNAC offers a training course to tourism providers
to access the protected area. This way, the update of the last 5 years
of such training is directed to diving staff, boat crew and
professionals, making them able to assist in managing the natural
resource. Moreover, the case study is an example to be used for
raising awareness among tourists visiting protected areas.
Abstract: The present study involved analysis of certain
characteristics of the perennial ryegrass (Lolium perenne L.)
genotypes collected from the natural flora of Ankara, and explores a
correlation among them. In order to evaluate the plants for breeding
purpose as per Turkey's environmental conditions, the perennial
ryegrass plants were collected from natural pasture of Ankara in 2004
and were utilized for the study. Seeds of the collected plants were
sown in pots and seedlings were prepared in a greenhouse. In 2005,
the seedlings were transplanted at 50 × 50 cm2 intervals in
Randomized Complete Blocks Design in an experimental field. In
2007 and 2008, data were recorded from the observations and
measurements of 568 perennial ryegrasses. The plant characteristics,
which were investigated, included re-growth time in spring, color,
density, growth habit, tendency to form inflorescence, time of
inflorescence, plant height, length of upper internode, spike length,
leaf length, leaf width, leaf area, leaf shape, number of spikelets per
spike, seed yield per spike and 1000 grain weight and the correlation
analyses were made using this data. Correlation coefficients were
estimated between all paired combinations of the studied traits. The
yield components exhibited varying trends of association among
themselves. Seed yield per spike showed significant and positive
association with the number of spikelets per spike, 1000 grain weight,
plant height, length of upper internode, spike length, leaf length, leaf
width, leaf area and color, but significant and negative association
with the growth habit and re-growth time in spring.
Abstract: The purpose of this study was to investigate
perceptions of climate change risk to forest ecosystems and forestbased
communities as well as perceived effectiveness of adaptation
strategies for climate change as well as challenges for adaptation.
Data was gathered using a pre-tested semi-structured questionnaire.
Simple random selection technique was applied. For the majority of
issues, the responses were obtained on multi-point likert scales, and
the scores provided were, in turn, used to estimate the means and
other useful estimates. A composite knowledge index developed
using correct responses to a set of self-rated statements were used to
evaluate the issues. The mean of the knowledge index was 0.64. Also
all respondents recorded values of the knowledge index above 0.25.
Increase forest fire was perceived by respondents as the greatest risk
to forest eco-system. Decrease access to water supplies was perceived
as the greatest risk to livelihoods of forest based communities. The
most effective adaptation strategy relevant to climate change risks to
forest eco-systems and forest based communities livelihoods in
Kathmandu valley in Nepal as perceived by the respondents was
reforestation and afforestation. As well, lack of public awareness was
perceived as the major limitation for climate change adaptation.
However, perceived risks as well as effective adaptation strategies
showed an inconsistent association with knowledge indicators and
social-cultural variables. The results provide useful information to
any party who involve with climate change issues in Nepal, since
such attempts would be more effective once the people’s perceptions
on these aspects are taken into account.
Abstract: Climate change would cause mean sea level to rise +1
m by 2100. To prevent coastal floods resulting from the sea level
rising, different flood control structures have been built, with
acceptable protection levels. Gothenburg with the River Göta älv
located on the southwest coast of Sweden is a vulnerable city to the
accelerated rises in mean sea level. We evaluated using a sea barrage
in the River Göta älv to protect Gothenburg during this century. The
highest sea level was estimated to 2.95 m above the current mean sea
level by 2100. To verify flood protection against such high sea levels,
both barriers have to be closed. To prevent high water level in the
River Göta älv reservoir, the barriers would be open when the sea
level is low. The suggested flood control structures would
successfully protect the city from flooding events during this century.
Abstract: Columns have traditionally been constructed of
reinforced concrete or structural steel. Much attention was allocated
to estimate the axial capacity of the traditional column sections to the
detriment of other forms of construction. Other forms of column
construction such as Concrete Filled Double Skin Tubes received
little research attention, and almost no attention when subjected to
eccentric loading. This paper investigates the axial capacity of
columns when subjected to eccentric loading. The experimental axial
capacities are compared to other established theoretical formulae on
concentric loading to determine a possible relationship. The study
found a good correlation between the reduction in axial capacity for
different column lengths and hollow section ratios.
Abstract: At-site flood frequency analysis is used to estimate
flood quantiles when at-site record length is reasonably long. In
Australia, FLIKE software has been introduced for at-site flood
frequency analysis. The advantage of FLIKE is that, for a given
application, the user can compare a number of most commonly
adopted probability distributions and parameter estimation methods
relatively quickly using a windows interface. The new version of
FLIKE has been incorporated with the multiple Grubbs and Beck test
which can identify multiple numbers of potentially influential low
flows. This paper presents a case study considering six catchments in
eastern Australia which compares two outlier identification tests
(original Grubbs and Beck test and multiple Grubbs and Beck test)
and two commonly applied probability distributions (Generalized
Extreme Value (GEV) and Log Pearson type 3 (LP3)) using FLIKE
software. It has been found that the multiple Grubbs and Beck test
when used with LP3 distribution provides more accurate flood
quantile estimates than when LP3 distribution is used with the
original Grubbs and Beck test. Between these two methods, the
differences in flood quantile estimates have been found to be up to
61% for the six study catchments. It has also been found that GEV
distribution (with L moments) and LP3 distribution with the multiple
Grubbs and Beck test provide quite similar results in most of the
cases; however, a difference up to 38% has been noted for flood
quantiles for annual exceedance probability (AEP) of 1 in 100 for one
catchment. This finding needs to be confirmed with a greater number
of stations across other Australian states.
Abstract: A novel method to produce a fast high voltage solid
states switch using Insulated Gate Bipolar Transistors (IGBTs) is
presented for discharge-pumped gas lasers. The IGBTs are connected
in series to achieve a high voltage rating. An avalanche transistor is
used as the gate driver. The fast pulse generated by the avalanche
transistor quickly charges the large input capacitance of the IGBT,
resulting in a switch out of a fast high-voltage pulse. The switching
characteristic of fast-high voltage solid state switch has been estimated
in the multi-stage series-connected IGBT with the applied voltage of
several tens of kV. Electrical circuit diagram and the mythology of
fast-high voltage solid state switch as well as experimental results
obtained are presented.
Abstract: This paper deals with the problem of automatic rule
generation for fuzzy systems design. The proposed approach is based
on hybrid artificial bee colony (ABC) optimization and weighted least
squares (LS) method and aims to find the structure and parameters of
fuzzy systems simultaneously. More precisely, two ABC based fuzzy
modeling strategies are presented and compared. The first strategy
uses global optimization to learn fuzzy models, the second one
hybridizes ABC and weighted least squares estimate method. The
performances of the proposed ABC and ABC-LS fuzzy modeling
strategies are evaluated on complex modeling problems and compared
to other advanced modeling methods.