Abstract: The California Bearing Ratio (CBR) has been
acknowledged as an important parameter to characterize the bearing
capacity of earth structures, such as earth dams, road embankments,
airport runways, bridge abutments and pavements. Technically, the
CBR test can be carried out in the laboratory or in the field. The CBR
test is time-consuming and is infrequently performed due to the
equipment needed and the fact that the field moisture content keeps
changing over time. Over the years, many correlations have been
developed for the prediction of CBR by various researchers,
including the dynamic cone penetrometer, undrained shear strength
and Clegg impact hammer. This paper reports and discusses some of
the results from a study on the prediction of CBR. In the current
study, the CBR test was performed in the laboratory on some finegrained
subgrade soils collected from various locations in Victoria.
Based on the test results, a satisfactory empirical correlation was
found between the CBR and the physical properties of the
experimental soils.
Abstract: The main objective of this paper is study the influence
of carbon nano-tubes fibers and nano silica fibers on the
characteristic compressive strength and flexural strength on concrete
and cement mortar. Twelve tested specimens were tested with square
section its dimensions (4040 160) mm, divided into four groups.
The first and second group studied the effect of carbon nano-tubes
(CNTs) fibers with different percentage equal to 0.0, 0.11%, 0.22%,
and 0.33% by weight of cement and effect of nano-silica (nS) fibers
with different percentages equal to 0.0, 1.0%, 2.0%, and 3.0% by
weight of cement on the cement mortar. The third and fourth groups
studied the effect of CNTs fiber with different percentage equal to
0.0%, 0.11%, and 0.22% by weight of cement, and effect of nS fibers
with different percentages were equal to 0.0%, 1.0%, and 2.0% by
weight of cement on the concrete. The compressive strength and
flexural strength at 7, 28, and 90 days is determined. From analysis of
tested results concluded that the nano-fibers is more effective when
used with cement mortar more than used with concrete because of
increasing the surface area, decreasing the pore and the collection of
nano-fibers. And also by adding nano-fibers the improvement of
flexural strength of concrete and cement mortar is more than
improvement of compressive strength.
Abstract: In this study, composites were fabricated from oil
palm empty fruit bunch fiber and poly(lactic) acid by extrusion
followed by injection moulding. Surface of the fiber was pre-treated
by ultrasound in an alkali medium and treatment efficiency was
investigated by scanning electron microscopy (SEM) analysis and
Fourier transforms infrared spectrometer (FTIR). Effect of fiber
treatment on composite was characterized by tensile strength (TS),
tensile modulus (TM) and impact strength (IS). Furthermore,
biostrong impact modifier was incorporated into the treated fiber
composite to improve its impact properties. Mechanical testing
showed an improvement of up to 23.5% and 33.6% respectively for
TS and TM of treated fiber composite above untreated fiber
composite. On the other hand incorporation of impact modifier led to
enhancement of about 20% above the initial IS of the treated fiber
composite.
Abstract: The present study was undertaken to investigate the
effect of pre-aging and aging parameters (time and temperature) on
the mechanical properties of Al-Mg-Zn (7075) alloys. Ultimate
tensile strength, 0.5% offset yield strength and % elongation
measurements were carried out on specimens prepared from cast and
heat treated 7075 alloys. Aging treatments were carried out for the as
solution treated (SHT) specimens (after quenching in warm water).
The specimens were aged at different conditions; Natural aging was
carried out at room temperature for different periods of time. Double
aging was performed for SHT conditions (pre-aged at different time
and temperature followed by high temperature aging). Ultimate
tensile strength, yield strength and % elongation as a function of
different pre-aging and aging parameters are analyzed to acquire an
understanding of the effects of these variables and their interactions
on the mechanical properties of Be-treated 7075 alloys.
Abstract: The prepreg process among the CFRP (Carbon Fiber
Reinforced Plastic) forming methods is the short term of
‘Pre-impregnation’, which is widely used for aerospace composites
that require a high quality property such as a fiber-reinforced woven
fabric, in which an epoxy hardening resin is impregnated the reality.
However, that this process requires continuous researches and
developments for its commercialization because the delamination
characteristically develops between the layers when a great weight is
loaded from outside to supplement such demerit, three lamination
methods among the prepreg lamination methods of CFRP were
designed to minimize the delamination between the layers due to
external impacts. Further, the newly designed methods and the
existing lamination methods were analyzed through a mechanical
characteristic test, Interlaminar Shear Strength test. The Interlaminar
Shear Strength test result confirmed that the newly proposed three
lamination methods, i.e. the Roll, Half and Zigzag laminations,
presented more excellent strengths compared to the conventional Ply
lamination. The interlaminar shear strength in the roll method with
relatively dense fiber distribution was approximately 1.75% higher
than that in the existing ply lamination method, and in the half method,
it was approximately 0.78% higher.
Abstract: Equal channel angular pressing (ECAP) of
commercial Al-Mg-Si alloy was conducted using two strain rates.
The ECAP processing was conducted at room temperature and at
250°C. Route A was adopted up to a total number of four passes in
the present work. Structural evolution of the aluminum alloy discs
was investigated before and after ECAP processing using optical
microscopy (OM). Following ECAP, simple compression tests and
Vicker’s hardness were performed. OM micrographs showed that, the
average grain size of the as-received Al-Mg-Si disc tends to be larger
than the size of the ECAP processed discs. Moreover, significant
difference in the grain morphologies of the as-received and processed
discs was observed. Intensity of deformation was observed via the
alignment of the Al-Mg-Si consolidated particles (grains) in the
direction of shear, which increased with increasing the number of
passes via ECAP. Increasing the number of passes up to 4 resulted in
increasing the grains aspect ratio up to ~5. It was found that the
pressing temperature has a significant influence on the
microstructure, Hv-values, and compressive strength of the processed
discs. Hardness measurements demonstrated that 1-pass resulted in
increase of Hv-value by 42% compared to that of the as-received
alloy. 4-passes of ECAP processing resulted in additional increase in
the Hv-value. A similar trend was observed for the yield and
compressive strength. Experimental data of the Hv-values
demonstrated that there is a lack of any significant dependence on the
processing strain rate.
Abstract: The problem of psychologist training remains a key
priority in Armenia. During the Soviet period, the notion of a
psychologist was obscure not only in Armenia but also in other
Soviet republics. The breakup of the Soviet Union triggered a gradual
change in this area activating the cooperation with specialists from
other countries. The need for recovery from the psychological trauma
caused by the 1988 earthquake pushed forward the development of
practical psychology in Armenia. This phenomenon led to positive
changes in perception of and interest to a psychologist
profession.Armenian universities started designing special programs
for psychologists’ preparation. Armenian psychologists combined
their efforts in the field of training relevant specialists.
During the recent years, the Bologna educational system was
introduced in Armenia which led to implementation of education
quality improvement programs. Nevertheless, even today the issue of
psychologists’ training is not yet settled in Armenian universities. So
far graduate psychologists haven’t got a clear idea of personal and
professional qualities of a psychologist. Recently, as a result of
educational reforms, the psychology curricula underwent changes,
but so far they have not led to a desired outcome. Almost all curricula
in certain specialties are aimed to form professional competencies
and strengthen practical skills.
A survey conducted in Armenia aimed to identify what are the
ideas of young psychology specialists on the image of a psychologist.
The survey respondents were 45 specialists holding bachelor’s degree
as well as 30 master degree graduates, who have not been working
yet. The research reveals that we need to change the approach of
preparing psychology practitioners in the universities of Armenia.
Such an approach to psychologist training will make it possible to
train qualified specialists for enhancement of modern psychology
theory and practice.
Abstract: Laser beam welding of dissimilar sheet metal
combinations such as Ti/Al, SS/Al and Cu/Al are increasingly
demanded due to high energy densities with less fusion and heat
affected zones. A good weld joint strength involves combinations of
dissimilar metals and the formation of solid solution in the weld pool.
Many metal pairs suffer from significant intermetallic phase
formation during welding which greatly reduces their strength. The
three different sheet metal mentioned above is critically reviewed and
phase diagram for the combinations are given. The aim of this study
is to develop an efficient metal combinations and the influence on
their interfacial characteristics. For that the following parameters
such as weld geometry, residual distortion, micro hardness,
microstructure and mechanical properties are analyzed
systematically.
Abstract: Early pre-code reinforced concrete structures present
undetermined resistance to earthquakes. This situation is particularly
unacceptable in the case of essential structures, such as healthcare
structures and pilgrims' houses. Amongst these, an existing old RC
building in Madinah city (KSA) is seismically evaluated with and
without infill wall and their dynamic characteristics are compared
with measured values in the field using ambient vibration
measurements (AVM). After updating the mathematical models for
this building with the experimental results, three dimensional
pushover analysis (Nonlinear static analysis) was carried out using
commercial structural analysis software incorporating inelastic
material properties for concrete, infill and steel. The purpose of this
analysis is to evaluate the expected performance of structural systems
by estimating, strength and deformation demands in design, and
comparing these demands to available capacities at the performance
levels of interest. The results summarized and discussed.
Abstract: Composite materials, due to their unique properties
such as high strength to weight ratio, corrosion resistance, and impact
resistance have huge potential as structural materials in automotive,
construction and transportation applications. However, these
properties often come at higher cost owing to complex design
methods, difficult manufacturing processes and raw material cost.
Traditionally, tapered laminated composite structures are
manufactured using autoclave manufacturing process by ply drop off
technique. Autoclave manufacturing though very powerful suffers
from high capital investment and higher energy consumption. As per
the current trends in composite manufacturing, Out of Autoclave
(OoA) processes are looked as emerging technologies for
manufacturing the structural composite components for aerospace
and defense applications. However, there is a need for improvement
among these processes to make them reliable and consistent. In this
paper, feasibility of using out of autoclave process to manufacture the
variable thickness cantilever beam is discussed. The minimum weight
design for the composite beam is obtained using constant stress beam
concept by tailoring the thickness of the beam. Ply drop off
techniques was used to fabricate the variable thickness beam from
glass/epoxy prepregs. Experiments were conducted to measure
bending stresses along the span of the cantilever beam at different
intervals by applying the concentrated load at the free end.
Experimental results showed that the stresses in the bean at different
intervals were constant. This proves the ability of OoA process to
manufacture the constant stress beam. Finite element model for the
constant stress beam was developed using commercial finite element
simulation software. It was observed that the simulation results
agreed very well with the experimental results and thus validated
design and manufacturing approach used.
Abstract: The effect of the inclusion of thyme and rosemary
essential oils into chitosan films, as well as the microbiological and
physical properties when storing chitosan film with and without the
mentioned inclusion was studied. The film forming solution was
prepared by dissolving chitosan (2%, w/v), polysorbate 80 (4% w/w
CH) and glycerol (16% w/w CH) in aqueous lactic acid solutions
(control). The thyme (TEO) and rosemary (REO) essential oils (EOs)
were included 1:1 w/w (EOs:CH) on their combination 50/50
(TEO:REO). The films were stored at temperatures of 5, 20, 33°C
and a relative humidity of 75% during four weeks. The films with
essential oil inclusion did not show an antimicrobial activity against
strains. This behavior could be explained because the chitosan only
inhibits the growth of microorganisms in direct contact with the
active sites. However, the inhibition capacity of TEO was higher than
the REO and a synergic effect between TEO:REO was found for S.
enteritidis strains in the chitosan solution.
Some physical properties were modified by the inclusion of
essential oils. The addition of essential oils does not affect the
mechanical properties (tensile strength, elongation at break, puncture
deformation), the water solubility, the swelling index nor the DSC
behavior. However, the essential oil inclusion can significantly
decrease the thickness, the moisture content, and the L* value of
films whereas the b* value increased due to molecular interactions
between the polymeric matrix, the loosing of the structure, and the
chemical modifications. On the other hand, the temperature and time
of storage changed some physical properties on the chitosan films.
This could have occurred because of chemical changes, such as
swelling in the presence of high humidity air and the reacetylation of
amino groups. In the majority of cases, properties such as moisture
content, tensile strength, elongation at break, puncture deformation,
a*, b*, chrome, 7E increased whereas water resistance, swelling
index, L*, and hue angle decreased.
Abstract: The design, manufacture, and operation of thin-walled
pressure vessels must be based on maximum safe operating pressure
and an adequate factor of safety (FoS). This research paper first
reports experimental evaluation of longitudinal and hoops stresses
based on working pressure as well as maximum pressure; and then
includes a critical study of factor of safety (FoS) in the design of a
glass fiber pressure vessel. Experimental work involved the use of
measuring instruments and the readings from pressure gauges.
Design calculations involved the computations of design stress and
FoS; the latter was based on breaking strength of 55 MPa for the
glass fiber (pressure-vessel material). The experimentally determined
FoS value has been critically compared with the general FoS allowed
in the design of glass fiber pressure vessels.
Abstract: This paper investigates the activity of the rectus
femoris (RF) and biceps femoris (BF) in healthy subjects during salat
(prostration) and specific exercise (squat exercise) using
electromyography (EMG). A group of undergraduates aged between
19 to 25 years voluntarily participated in this study. The myoelectric
activity of the muscles were recorded and analyzed. The finding
indicated that there were contractions of the muscles during the salat
and exercise with almost same EMG’s level. From the result,
Wilcoxon’s Rank Sum test showed significant difference between
prostration and squat exercise (p
Abstract: Cost of governance in Nigeria has become a challenge
to development and concern to practitioners and scholars alike in the
field of business and social science research. In the 2010 national
budget of NGN4.6 trillion or USD28.75billion for instance, only a
pantry sum of NGN1.8trillion or USD11.15billion was earmarked for
capital expenditure. Similarly, in 2013, out of a total national budget
of NGN4.92trillion or USD30.75billion, only the sum of
NGN1.50trllion or USD9.38billion was voted for capital expenditure.
Therefore, based on the data sourced from the Nigerian Office of
Statistics, Central bank of Nigeria Statistical Bulletin as well as from
the United Nations Development Programme, this study examined
the causes of high cost of governance in Nigeria. It found out that the
high cost of governance in the country is in the interest of the ruling
class, arising from their unethical behaviour – corrupt practices and
the poor management of public resources. As a result, the study
recommends the need to intensify the war against corruption and
mismanagement of public resources by government officials as
possible solution to overcome the high cost of governance in Nigeria.
This could be achieved by strengthening the constitutional powers of
the various anti-corruption agencies in the area of arrest, investigation
and prosecution of offenders without the interference of the executive
arm of government either at the local, state or federal level.
Abstract: Due to water shortage, application of saline water for
irrigation is an urgent in agriculture. In this study the effect of
calcium and potassium application as additive in saline root media for
reduce salinity adverse effects was investigated on tomato growth in
a hydroponic system with unequal distribution of salts in the root
media, which was divided in to two equal parts containing full
Johnson nutrient solution and 40 mMNaCl solution, alone or in
combination with KCl (6 mM), CaCl2 (4 mM), K+Ca (3+2 mM) or
half-strength Johnson nutrient solution. The root splits were
exchanged every 7 days. Results showed that addition of calcium,
calcium-potassium and nutrition elements equivalent to half the
concentration of Johnson formula to the saline-half of culture media
minimized the reduction in plant growth caused by NaCl, although
addition of potassium to culture media wasn’t effective. The greatest
concentration of sodium was observed at the shoot of treatments
which had smallest growth. According to the results of this study, in
case of dynamic and non-uniform distribution of salts in the root
media, by addition of additive to the saline solution, it would be
possible to use of saline water with no significant growth reduction.
Abstract: Carbon fiber reinforced polymersarewidely used to strengthen steel structural elements. These structural elements are normally subjected to static, dynamic and fatigue loadings during their life-time. CFRP laminate is commonly used to strengthen these structures under the subjected loads. A number of studies have focused on the characteristics of CFRP sheets bonded to steel members under static, dynamic and fatigue loadings. However, there is a gap in understanding the bonding behavior between CFRP laminates and steel members under impact loading. This paper shows the effect of high load rates on this bond. CFRP laminate CFK 150/2000 was used to strengthen steel joints using Araldite 420 epoxy. The results show that applying a high load rate significantly affects the bond strength but has little influence on the effective bond length.
Abstract: Geopolymer concretes are new class of construction
materials that have emerged as an alternative to Ordinary Portland
cement concrete. Considerable researches have been carried out on
material development of geopolymer concrete; however, a few studies
have been reported on the structural use of them. This paper presents
the bond behaviors of reinforcement embedded in fly ash based
geopolymer concrete. The development lengths of reinforcement for
various compressive strengths of concrete, 20, 30 and 40 MPa, and
reinforcement diameters, 10, 16 and 25 mm, are investigated. Total 27
specimens were manufactured and pull-out test according to EN 10080
was applied to measure bond strength and slips between concrete and
reinforcements. The average bond strengths decreased from 23.06MPa
to 17.26 MPa, as the diameters of reinforcements increased from
10mm to 25mm. The compressive strength levels of geopolymer
concrete showed no significant influence on bond strengths in this
study. Also, the bond-slip relations between geopolymer concrete and
reinforcement are derived using non-linear regression analysis for
various experimental conditions.
Abstract: Learning through creation of contextual games is a
very promising approach when undertaking interdisciplinary and
international group projects. During 2013 and 2014 the authors
organized two intensive student projects. The two projects were in
different countries and different conditions. Between them, the two
projects involved 68 students and 12 mentors from five EU countries
and from various academic disciplines. In this paper we share our
experience of these two projects and we suggest approaches that can
be utilized to strengthen the chances of succeeding in short (12-15
days long) intensive student projects.
Abstract: This paper investigates the viability of using carbon
fiber reinforced epoxy composites modified with carbon nanotubes to
strengthening reinforced concrete (RC) columns. Six RC columns
was designed and constructed according to ASCE standards. The
columns were wrapped using carbon fiber sheets impregnated with
either neat epoxy or CNTs modified epoxy. These columns were then
tested under concentric axial loading. Test results show that;
compared to the unwrapped specimens; wrapping concrete columns
with carbon fiber sheet embedded in CNTs modified epoxy resulted
in an increase in its axial load resistance, maximum displacement,
and toughness values by 24%, 109% and 232%, respectively. These
results reveal that adding CNTs into epoxy resin enhanced the
confinement effect, specifically, increased the axial load resistance,
maximum displacement, and toughness values by 11%, 6%, and
19%, respectively compared with columns strengthening with carbon
fiber sheet embedded in neat epoxy.
Abstract: Self-compacting concrete (SCC) developed in Japan
in the late 80s has enabled the construction industry to reduce
demand on the resources, improve the work condition and also
reduce the impact of environment by elimination of the need for
compaction. Fuzzy logic (FL) approaches has recently been used to
model some of the human activities in many areas of civil
engineering applications. Especially from these systems in the model
experimental studies, very good results have been obtained. In the
present study, a model for predicting compressive strength of SCC
containing various proportions of fly ash, as partial replacement of
cement has been developed by using Fuzzy Inference System (FIS).
For the purpose of building this model, a database of experimental
data were gathered from the literature and used for training and
testing the model. The used data as the inputs of fuzzy logic models
are arranged in a format of five parameters that cover the total binder
content, fly ash replacement percentage, water content,
superplasticizer and age of specimens. The training and testing results
in the fuzzy logic model have shown a strong potential for predicting
the compressive strength of SCC containing fly ash in the considered
range.