Abstract: This article is trying to determine the status of flue gas
that is entering the KWH heat exchanger from combustion chamber
in order to calculate the heat transfer ratio of the heat exchanger.
Combination of measurement, calculation and computer simulation
was used to create a useful way to approximate the heat transfer rate.
The measurements were taken by a number of sensors that are
mounted on the experimental device and by a thermal imaging
camera. The results of the numerical calculation are in a good
correspondence with the real power output of the experimental
device. That result shows that the research has a good direction and
can be used to propose changes in the construction of the heat
exchanger, but still needs enhancements.
Abstract: This study examines analytically the effect of tsunami loads on reinforced concrete (RC) frame buildings. The impact of tsunami wave loads and waterborne objects are analyzed using a typical substandard full-scale two-story RC frame building tested as part of the EU-funded Ecoleader project. The building was subjected to shake table tests in bare condition, and subsequently strengthened using Carbon Fiber Reinforced Polymers (CFRP) composites and retested. Numerical models of the building in both bare and CFRP-strengthened conditions are calibrated in DRAIN-3DX software to match the test results. To investigate the response of wave loads and impact forces, the numerical models are subjected to nonlinear dynamic analyses using force time-history input records. The analytical results are compared in terms of displacements at the floors and at the “impact point” of a boat. The results show that the roof displacement of the CFRP-strengthened building reduced by 63% when compared to the bare building. The results also indicate that strengthening only the mid-height of the impact column using CFRP is more effective at reducing damage when compared to strengthening other parts of the column. Alternative solutions to mitigate damage due to tsunami loads are suggested.
Abstract: The objective of this study was to identify the optimal
level of partial replacement of Portland cement by the ashes
originating from burning straw and bagasse from sugar cane (ASB).
Order to this end, were made five series of flat plates and cylindrical
bodies: control and others with the partial replacement in 20, 30, 40
and 50% of ASB in relation to the mass of the Ordinary Portland
cement, and conducted a mechanical testing of simple axial
compression (cylindrical bodies) and the four-point bending (flat
plates) and determined water absorption (WA), bulk density (BD)
and apparent void volume (AVV) on both types of specimens. Based
on the data obtained, it may be noted that the control treatment
containing only Portland cement, obtained the best results. However,
the cylindrical bodies with 20% ashes showed better results
compared to the other treatments. And in the formulations plates, the
treatment which showed the best results was 30% cement
replacement by ashes.
Abstract: Qatar, a Gulf country highly dependent on its oil and
gas revenues – is looking to innovate, diversify, and ultimately reach
its aim of creating a knowledge economy to prepare for its post-oil
era. One area that the country is investing in is Contemporary Art,
and world renowned artists such as Damien Hirst and Richard Serra –
have been commissioned to design site-specific art for the public
spaces of the city of Doha as well as in more remote desert locations.
This research discusses the changing presence, role and context of
public art in Doha, both from a historical and cultural overview, and
the different forms and media as well as the typologies of urban and
public spaces in which the art is installed. It examines the process of
implementing site-specific artworks, looking at questions of scale,
history, social meaning and formal aesthetics. The methodologies
combine theoretical research on the understanding of public art and
its role and placement in public space, as well as empirical research
on contemporary public art projects in Doha, based on documentation
and interviews and as well as site and context analysis of the urban or
architectural spaces within which the art is situated. Surveys and
interviews – using social media - in different segments of the
contemporary Qatari society, including all nationalities and social
groups, are used to measure and qualify the impacts and effects on
the population.
Abstract: Generally the natural environment is made up of air,
water and soil. The release of emission of industrial waste into
anyone of the components of the environment causes pollution.
Industrial pollution significantly threatens the inherent right of
people, to the enjoyment of a safe and secure environment. The aim
of this paper is to assess the effect of environmental pollution and
health risks of residents living near Ewekoro cement factory. The
research made use of IKONOS imagery for Geographical
Information System (GIS) to buffer and extract buildings that are less
than 1km to the factory, within 1km to 5km and above 5km to the
factory. Also questionnaire was used to elicit information on the
socio-economic factors, effect of environmental pollution on
residents and measures adopted to control industrial pollution on the
residents. Findings show that most buildings that fall between less
than 1km and 1km to 5km to the factory have high health risk in the
study area. The study recommended total relocation for the residents
of the study area to reduce health risk problems.
Abstract: Geometric and mechanical properties all influence the
resistance of RC structures and may, in certain combination of
property values, increase the risk of a brittle failure of the whole
system.
This paper presents a statistical and probabilistic investigation on
the resistance of RC beams designed according to Eurocodes 2 and 8,
and subjected to multiple failure modes, under both the natural
variation of material properties and the uncertainty associated with
cross-section and transverse reinforcement geometry. A full
probabilistic model based on JCSS Probabilistic Model Code is
derived. Different beams are studied through material nonlinear
analysis via Monte Carlo simulations. The resistance model is
consistent with Eurocode 2. Both a multivariate statistical evaluation
and the data clustering analysis of outcomes are then performed.
Results show that the ultimate load behaviour of RC beams
subjected to flexural and shear failure modes seems to be mainly
influenced by the combination of the mechanical properties of both
longitudinal reinforcement and stirrups, and the tensile strength of
concrete, of which the latter appears to affect the overall response of
the system in a nonlinear way. The model uncertainty of the
resistance model used in the analysis plays undoubtedly an important
role in interpreting results.
Abstract: This review emphasizes the effectiveness of men’s
participation in preventing domestic violence, and whether nonviolent
(NV) boys’ and men’s perceptions of intimate partner
violence (IPV) prevention programs affect their involvement. The
main goals of this assessment were to investigate (1) how NV men
engaged in anti-violence prevention programs that empower women,
(2) what were the possible perceptions of NV men involved in
prevention programs (3) how to identify effective approaches and
strategies that encouraged NV men to become involved in prevention
programs. This critical review also included the overview of
prevention programs such as: The Mentors in Violence Prevention
Programs (MVP), The White Ribbon Campaign (WRC), and
Domestic Violence Prevention Enhancement and Leadership through
Alliances (DELTA). The review suggested that (1) the expanding
prevention programs need to reach more macro settings such as work
place, faith-based and other community based organizations, and (2)
territory prevention programs should expand through addressing the
long-term effects of violence.
Abstract: Waste silicon carbide (waste SiC) filled high-density
polyethylene (HDPE) with and without surface modifiers were
studied. Two types of surface modifiers namely; high-density
polyethylene-grafted-maleic anhydride (HDPE-g-MA) and 3-aminopropyltriethoxysilane have been used in this study. The
composites were produced using a two roll mill, extruder and shaped
in a hydraulic compression molding machine. The mechanical
properties of polymer composites such as flexural strength and
modulus, impact strength, tensile strength, stiffness and hardness
were investigated over a range of compositions. It was found that,
flexural strength and modulus, tensile modulus and hardness
increased, whereas impact strength and tensile strength decreased
with the increasing in filler contents, compared to the neat HDPE. At
similar filler content, the effect of both surface modifiers increased
flexural modulus, impact strength, tensile strength and stiffness but
reduced the flexural strength. Morphological investigation using
SEM revealed that the improvement in mechanical properties was
due to enhancement of the interfacial adhesion between waste SiC
and HDPE.
Abstract: In this paper, the effect of grades 32.4 and 42.5
Portland-limestone cements generally used for concrete production in
Nigeria on concrete compressive strength is investigated.
Investigation revealed that the compressive strength of concrete
produced with Portland-limestone cement grade 42.5 is generally
higher than that produced with cement grade 32.5. The percentage
difference between the compressive strengths of the concrete cubes
produced with Portland-limestone cement grades 42.5 and 32.5 is
inversely proportional to the richness of the concrete with the highest
and the least percentage difference associated with the 1:2:4 and
1:1:2 mix ratios respectively. It is recommended that cement grade
42.5 be preferred for construction in Nigeria as this will lead to the
construction of stronger concrete structures, which will reduce the
incidence of failure of building and other concrete structures at no
additional cost since the cost of both cement grades are the same.
Abstract: This study concerned the dynamic behavior of the
wind turbine rotor. Before all we have studied the loads applied to the
rotor, which allows the knowledge their effect on the fatigue, also
studied the rotor with longitudinal crack in order to determine stress,
strain and displacement. Firstly we compared the first six modes
shapes between cracking and uncracking of HAWT rotor. Secondly
we show show evolution of first six natural frequencies with
longitudinal crack propagation. Finally we conclude that the residual
change in the natural frequencies can be used as in shaft crack
diagnosis predictive maintenance.
Abstract: Speech enhancement is a long standing problem with
numerous applications like teleconferencing, VoIP, hearing aids and
speech recognition. The motivation behind this research work is to
obtain a clean speech signal of higher quality by applying the optimal
noise cancellation technique. Real-time adaptive filtering algorithms
seem to be the best candidate among all categories of the speech
enhancement methods. In this paper, we propose a speech
enhancement method based on Recursive Least Squares (RLS)
adaptive filter of speech signals. Experiments were performed on
noisy data which was prepared by adding AWGN, Babble and Pink
noise to clean speech samples at -5dB, 0dB, 5dB and 10dB SNR
levels. We then compare the noise cancellation performance of
proposed RLS algorithm with existing NLMS algorithm in terms of
Mean Squared Error (MSE), Signal to Noise ratio (SNR) and SNR
Loss. Based on the performance evaluation, the proposed RLS
algorithm was found to be a better optimal noise cancellation
technique for speech signals.
Abstract: In this research the effects of adding silica and
alumina nanoparticles on flow ability and compressive strength of
cementitious composites based on Portland cement were investigated.
In the first stage, the rheological behavior of different samples
containing nanosilica, nanoalumina and polypropylene, polyvinyl
alcohol and polyethylene fibers were evaluated. With increasing of
nanoparticles in fresh samples, the slump flow diameter reduced.
Fibers reduced the flow ability of the samples and viscosity
increased. With increasing of the micro silica particles to cement
ratio from 2/1 to 2/2, the slump flow diameter increased. By adding
silica and alumina nanoparticles up to 3% and 2% respectively, the
compressive strength increased and after decreased. Samples
containing silica nanoparticles and fibers had the highest compressive
strength.
Abstract: Bio-composites derived from plant fiber and/or bioderived
polymer, are likely more ecofriendly and demonstrate
competitive performance with petroleum based composites. In this
research, the bio phenol-formaldehyde (bio-PF) was used as a matrix
and oil palm empty fruit bunch fiber (EFB) as reinforcement. The
matrix was synthesized via liquefaction and condensation to enhance
the combination of phenol and formaldehyde, during the process.
Then, the bio-PF was mixed with different percentage of EFB (5%,
10%, 15% and 20%) and molded at 180oC. The samples that viewed
under scanning electron microscopy (SEM) showed an excellent
wettability and interaction between EFB and matrix. Samples of 10%
EFB gave the optimum properties of impact and hardness meanwhile
sample 15% of EFB gave the highest reading of flexural modulus
(MOE) and flexural strength (MOR). For thermal stability analysis, it
was found that the weight loss and the activation energy (Ea) of the
bio-composites samples were decreased as the filler content
increased.
Abstract: In this paper, a nonlinear Finite Element Analysis
(FEA) was carried out using ANSYS software to build a model able
of predicting the behavior of Reinforced Concrete (RC) beams with
unbonded reinforcement. The FEA model was compared to existing
experimental data by other researchers. The existing experimental
data consisted of 16 beams that varied from structurally sound beams
to beams with unbonded reinforcement with different unbonded
lengths and reinforcement ratios. The model was able to predict the
ultimate flexural strength, load-deflection curve, and crack pattern of
concrete beams with unbonded reinforcement. It was concluded that
when the when the unbonded length is less than 45% of the span,
there will be no decrease in the ultimate flexural strength due to the
loss of bond between the steel reinforcement and the surrounding
concrete regardless of the reinforcement ratio. Moreover, when the
reinforcement ratio is relatively low, there will be no decrease in
ultimate flexural strength regardless of the length of unbond.
Abstract: This paper presents the details of a numerical study of
buckling and post buckling behaviour of laminated carbon fiber
reinforced plastic (CFRP) thin-walled cylindrical shell under axial
compression using asymmetric meshing technique (AMT) by
ABAQUS. AMT is considered to be a new perturbation method to
introduce disturbance without changing geometry, boundary
conditions or loading conditions. Asymmetric meshing affects both
predicted buckling load and buckling mode shapes. Cylindrical shell
having lay-up orientation [0^o/+45^o/-45^o/0^o] with radius to thickness
ratio (R/t) equal to 265 and length to radius ratio (L/R) equal to 1.5 is
analysed numerically. A series of numerical simulations
(experiments) are carried out with symmetric and asymmetric
meshing to study the effect of asymmetric meshing on predicted
buckling behaviour. Asymmetric meshing technique is employed in
both axial direction and circumferential direction separately using
two different methods, first by changing the shell element size and
varying the total number elements, and second by varying the shell
element size and keeping total number of elements constant. The
results of linear analysis (Eigenvalue analysis) and non-linear
analysis (Riks analysis) using symmetric meshing agree well with
analytical results. The results of numerical analysis are presented in
form of non-dimensional load factor, which is the ratio of buckling
load using asymmetric meshing technique to buckling load using
symmetric meshing technique. Using AMT, load factor has about 2%
variation for linear eigenvalue analysis and about 2% variation for
non-linear Riks analysis. The behaviour of load end-shortening curve
for pre-buckling is same for both symmetric and asymmetric meshing
but for asymmetric meshing curve behaviour in post-buckling
becomes extraordinarily complex. The major conclusions are:
different methods of AMT have small influence on predicted
buckling load and significant influence on load displacement curve
behaviour in post buckling; AMT in axial direction and AMT in
circumferential direction have different influence on buckling load
and load displacement curve in post-buckling.
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: Solenoid operated electromagnetic control valve
(ECV) playing an important role for car’s air conditioning control
system. ECV is used in external variable displacement swash plate
type compressor and controls the entire air conditioning system by
means of a pulse width modulation (PWM) input signal supplying
from an external source (controller). Complete form of ECV contains
number of internal features like valve body, core, valve guide,
plunger, guide pin, plunger spring, bellows etc. While designing the
ECV; dimensions of different internal items must meet the standard
requirements as it is quite challenging. In this research paper,
especially the dimensioning of ECV body and its three pressure ports
through which the air/refrigerant passes are considered. Here internal
leakage test analysis of ECV body is being carried out from its
discharge port (Pd) to crankcase port (Pc) when the guide valve is
placed inside it. The experiments have made both in ordinary and
digital system using different assumptions and thereafter compare the
results.
Abstract: Digital image correlation (DIC) is a contactless fullfield
displacement and strain reconstruction technique commonly
used in the field of experimental mechanics. Comparing with
physical measuring devices, such as strain gauges, which only
provide very restricted coverage and are expensive to deploy widely,
the DIC technique provides the result with full-field coverage and
relative high accuracy using an inexpensive and simple experimental
setup. It is very important to study the natural patterns effect on the
DIC technique because the preparation of the artificial patterns is
time consuming and hectic process. The objective of this research is
to study the effect of using images having natural pattern on the
performance of DIC. A systematical simulation method is used to
build simulated deformed images used in DIC. A parameter (subset
size) used in DIC can have an effect on the processing and accuracy
of DIC and even cause DIC to failure. Regarding to the picture
parameters (correlation coefficient), the higher similarity of two
subset can lead the DIC process to fail and make the result more
inaccurate. The pictures with good and bad quality for DIC methods
have been presented and more importantly, it is a systematic way to
evaluate the quality of the picture with natural patterns before they
install the measurement devices.
Abstract: At certain depths during large diameter displacement
pile driving, rebound well over 0.25 inches was experienced,
followed by a small permanent-set during each hammer blow. High
pile rebound (HPR) soils may stop the pile driving and results in a
limited pile capacity. In some cases, rebound leads to pile damage,
delaying the construction project, and the requiring foundations
redesign. HPR was evaluated at seven Florida sites, during driving of
square precast, prestressed concrete piles driven into saturated, fine
silty to clayey sands and sandy clays. Pile Driving Analyzer (PDA)
deflection versus time data recorded during installation, was used to
develop correlations between cone penetrometer (CPT) pore-water
pressures, pile displacements and rebound. At five sites where piles
experienced excessive HPR with minimal set, the pore pressure
yielded very high positive values of greater than 20 tsf. However, at
the site where the pile rebounded, followed by an acceptable
permanent-set, the measured pore pressure ranged between 5 and 20
tsf. The pore pressure exhibited values of less than 5 tsf at the site
where no rebound was noticed. In summary, direct correlations
between CPTu pore pressure and rebound were produced, allowing
identification of soils that produce HPR.