Abstract: Thermoacoustic refrigerator is a cooling device which
uses the acoustic waves to produce the cooling effect. The aim of this
paper is to explore the experimental and numerical feasibility of a
standing-wave thermoacoustic refrigerator. The effects of the stack
length, position of stack and operating frequency on the cooling
performance are carried out. The circular pore stacks are tested under
the atmospheric pressure. A low-cost loudspeaker is used as an
acoustic driver. The results show that the location of stack installed in
resonator tube has a greater effect on the cooling performance, than
the stack length and operating frequency, respectively. The
temperature difference across the ends of stack can be generated up
to 13.7°C, and the temperature of cold-end is dropped down by 5.3°C
from the ambient temperature.
Abstract: A model to predict the plastic zone size for material
under plane stress condition has been developed and verified
experimentally. The developed model is a function of crack size,
crack angle and material property (dislocation density). Simulation
and validation results show that the model developed show good
agreement with experimental results. Samples of low carbon steel
(0.035%C) with included surface crack angles of 45o, 50o, 60o, 70o
and 90o and crack depths of 2mm and 4mm were subjected to low
strain rate between 0.48 x 10-3 s-1 – 2.38 x 10-3 s-1. The mechanical
properties studied were ductility, tensile strength, modulus of
elasticity, yield strength, yield strain, stress at fracture and fracture
toughness. The experimental study shows that strain rate has no
appreciable effect on the size of plastic zone while crack depth and
crack angle plays an imperative role in determining the size of the
plastic zone of mild steel materials.
Abstract: Production fluids are transported from the platform to
tankers or process facilities through transfer pipelines. Water being
one of the heavier phases tends to settle at the bottom of pipelines
especially at low flow velocities and this has adverse consequences
for pipeline integrity. On restart after a shutdown, this could result in
corrosion and issues for process equipment, thus the need to have the
heavier liquid dispersed into the flowing lighter fluid. This study
looked at the flow regime of low water cut and low flow velocity oil
and water flow using conductive film thickness probes in a large
diameter 4-inch pipe to obtain oil and water interface height and the
interface structural velocity. A wide range of 0.1–1.0 m/s oil and
water mixture velocities was investigated for 0.5–5% water cut. Two
fluid model predictions were used to compare with the experimental
results.
Abstract: A number of studies have been conducted recently to
investigate the influence of randomly oriented fibers on some
engineering properties of cohesive and cohesionless soils. However,
few studies have been carried out on freezing-thawing behavior of
fine-grained soils modified with discrete fiber inclusions and additive
materials. This experimental study was performed to investigate the
effect of randomly distributed polypropylene fibers (PP) and some
additive materials [e.g.., borogypsum (BG), fly ash (FA) and cement
(C)] on freezing-thawing durability (mass losses) of a fine-grained
soil for 6, 12, and 18 cycles. The Taguchi method was applied to the
experiments and a standard L9 orthogonal array (OA) with four
factors and three levels were chosen. A series of freezing-thawing
tests were conducted on each specimen. 0-20% BG, 0-20% FA, 0-
0.25% PP and 0-3% of C by total dry weight of mixture were used in
the preparation of specimens. Experimental results showed that the
most effective materials for the freezing-thawing durability (mass
losses) of the samples were borogypsum and fly ash. The values of
mass losses for 6, 12 and 18 cycles in optimum conditions were
16.1%, 5.1% and 3.6%, respectively.
Abstract: Rotary entrainment is a phenomenon in which the
interface of two immiscible fluids are subjected to external flux by
means of rotation. Present work reports the experimental study on
rotary motion of a horizontal cylinder between the interface of air and
water to observe the penetration of gas inside the liquid. Experiments
have been performed to establish entrainment of air mass in water
alongside the cylindrical surface. The movement of tracer and seeded
particles has been tracked to calculate the speed and path of the
entrained air inside water. Simplified particle image velocimetry
technique has been used to trace the movement of particles/tracers at
the moment they are injected inside the entrainment zone and
suspended beads have been used to replicate the particle movement
with respect to time in order to determine the flow dynamics of the
fluid along the cylinder. Present paper establishes a thorough experimental analysis of the
rotary entrainment phenomenon between air and water keeping in
interest the extent to which we can intermix the two and also to study
its entrainment trajectories.
Abstract: In this paper, we propose the variational EM inference
algorithm for the multi-class Gaussian process classification model
that can be used in the field of human behavior recognition. This
algorithm can drive simultaneously both a posterior distribution of a
latent function and estimators of hyper-parameters in a Gaussian
process classification model with multiclass. Our algorithm is based
on the Laplace approximation (LA) technique and variational EM
framework. This is performed in two steps: called expectation and
maximization steps. First, in the expectation step, using the Bayesian
formula and LA technique, we derive approximately the posterior
distribution of the latent function indicating the possibility that each
observation belongs to a certain class in the Gaussian process
classification model. Second, in the maximization step, using a derived
posterior distribution of latent function, we compute the maximum
likelihood estimator for hyper-parameters of a covariance matrix
necessary to define prior distribution for latent function. These two
steps iteratively repeat until a convergence condition satisfies.
Moreover, we apply the proposed algorithm with human action
classification problem using a public database, namely, the KTH
human action data set. Experimental results reveal that the proposed
algorithm shows good performance on this data set.
Abstract: The research explored the effect of morphemic analysis
awareness on ESL secondary school students’ vocabulary acquisition.
The quasi-experimental study was conducted with 100 ESL
secondary school students in two experimental groups (inflectional
and derivational) and one control group. The students’ vocabulary
acquisition was assessed through two measures: Morph-Analysis Test
and Morph-Vocabulary Test in the pretest and posttest before and
after an intervention programme. Results of ANCOVA revealed that
both the experimental groups achieved a significant score in Morph-
Analysis Test and Vocabulary-Morphemic Test. However, the
inflectional group obtained a fairly higher score than the derivational
group. Thus, the findings of the research are discussed in two main
areas. First, individual instructions of two types of morphemic
awareness have contributed significant results on inflectional and
derivational awareness among the ESL secondary school students.
Nevertheless, derivational morphology achieved a significant but
relatively smaller amount of effect on secondary school students’
morphological awareness compared to inflectional morphology in
this research. Second finding showed that the awareness of
inflectional and derivational morphology was found significantly
related to vocabulary achievement of ESL secondary school students.
Nevertheless, inflectional morphemic awareness had higher
significant effect on ESL secondary school students’ vocabulary
acquisition. Despite these findings, the study implies that morphemic
analysis awareness can serve as an alternative strategy for ESL
secondary school students in acquiring English vocabulary.
Abstract: The 1:1 cocrystal of 2-amino-4-chloro-6-
methylpyrimidine (2A4C6MP) with 4-methylbenzoic acid (4MBA)
(I) has been prepared by slow evaporation method in methanol,
which was crystallized in monoclinic C2/c space group, Z = 8, and a
= 28.431 (2) Å, b = 7.3098 (5) Å, c = 14.2622 (10) Å and β =
109.618 (3)°. The presence of unionized –COOH functional group in
cocrystal I was identified both by spectral methods (1H and 13C
NMR, FTIR) and X-ray diffraction structural analysis. The
2A4C6MP molecule interact with the carboxylic group of the
respective 4MBA molecule through N—H⋯O and O—H⋯N
hydrogen bonds, forming a cyclic hydrogen–bonded motif R2
2(8).
The crystal structure was stabilized by Npyrimidine—H⋯O=C and
C=O—H⋯Npyrimidine types hydrogen bonding interactions.
Theoretical investigations have been computed by HF and density
function (B3LYP) method with 6–311+G (d,p)basis set. The
vibrational frequencies together with 1H and 13C NMR chemical
shifts have been calculated on the fully optimized geometry of
cocrystal I. Theoretical calculations are in good agreement with the
experimental results. Solvent–free formation of this cocrystal I is
confirmed by powder X-ray diffraction analysis.
Abstract: A theoretical study of a humidification
dehumidification solar desalination unit has been carried out to
increase understanding the effect of weather conditions on the unit
productivity. A humidification-dehumidification (HD) solar
desalination unit has been designed to provide fresh water for
population in remote arid areas. It consists of solar water collector
and air collector; to provide the hot water and air to the desalination
chamber. The desalination chamber is divided into humidification
and dehumidification towers. The circulation of air between the two
towers is maintained by the forced convection. A mathematical
model has been formulated, in which the thermodynamic relations
were used to study the flow, heat and mass transfer inside the
humidifier and dehumidifier. The present technique is performed in
order to increase the unit performance. Heat and mass balance has
been done and a set of governing equations has been solved using the
finite difference technique. The unit productivity has been calculated
along the working day during the summer and winter sessions and
has compared with the available experimental results. The average
accumulative productivity of the system in winter has been ranged
between 2.5 to 4 (kg/m2)/day, while the average summer productivity
has been found between 8 to 12 (kg/m2)/day.
Abstract: The floor beams of steel buildings, cold-formed steel
floor joists in particular, often require large web openings, which may
affect their shear capacities. A cost effective way to mitigate the
detrimental effects of such openings is to weld/fasten reinforcements.
A difficulty associated with an experimental investigation to establish
suitable reinforcement schemes for openings in shear zone is that
moment always coexists with the shear, and thus, it is impossible to
create pure shear state in experiments, resulting in moment
influenced results. However, Finite Element Method (FEM) based
analysis can be conveniently used to investigate the pure shear
behaviour of webs including webs with reinforced openings. This
paper presents the details associated with the finite element analysis
of thick/thin-plates (representing the web of hot-rolled steel beam,
and the web of a cold-formed steel member) having a large
reinforced opening. The study considered simply-supported
rectangular plates subjected to in-plane shear loadings until failure
(including post-buckling behaviour). The plate was modelled using
geometrically non-linear quadrilateral shell elements, and non-linear
stress-strain relationship based on experiments. Total Langrangian
with large displacement/small strain formulation was used for such
analyses. The model also considered the initial geometric
imperfections. This study considered three reinforcement schemes,
namely, flat, lip, and angle reinforcements. This paper discusses the
modelling considerations and presents the results associated with the
various reinforcement schemes under consideration.
Abstract: Liver segmentation from medical images poses more
challenges than analogous segmentations of other organs. This
contribution introduces a liver segmentation method from a series of
computer tomography images. Overall, we present a novel method for
segmenting liver by coupling density matching with shape priors.
Density matching signifies a tracking method which operates via
maximizing the Bhattacharyya similarity measure between the
photometric distribution from an estimated image region and a model
photometric distribution. Density matching controls the direction of
the evolution process and slows down the evolving contour in regions
with weak edges. The shape prior improves the robustness of density
matching and discourages the evolving contour from exceeding liver’s
boundaries at regions with weak boundaries. The model is
implemented using a modified distance regularized level set (DRLS)
model. The experimental results show that the method achieves a
satisfactory result. By comparing with the original DRLS model, it is
evident that the proposed model herein is more effective in addressing
the over segmentation problem. Finally, we gauge our performance of
our model against matrices comprising of accuracy, sensitivity, and
specificity.
Abstract: As a result of the ambiguity and complexity
surrounding anaerobic digester foaming, efforts have been made by
various researchers to understand the process of anaerobic digester
foaming so as to proffer a solution that can be universally applied
rather than site specific. All attempts ranging from experimental
analysis to comparative review of other process has not fully
explained the conditions and process of foaming in anaerobic
digester. Studying the current available knowledge on foam
formation and relating it to anaerobic digester process and operating
condition, this piece of work presents a succinct and enhanced
understanding of foaming in anaerobic digesters as well as
introducing a simple method to identify the onset of anaerobic
digester foaming based on analysis of historical data from a field
scale system.
Abstract: Noninvasive diagnostics of diseases via breath
analysis has attracted considerable scientific and clinical interest for
many years and become more and more promising with the rapid
advancements in nanotechnology and biotechnology. The volatile
organic compounds (VOCs) in exhaled breath, which are mainly
blood borne, particularly provide highly valuable information about
individuals’ physiological and pathophysiological conditions.
Additionally, breath analysis is noninvasive, real-time, painless, and
agreeable to patients. We have developed a wireless sensor array
based on single-stranded DNA (ssDNA)-functionalized single-walled
carbon nanotubes (SWNT) for the detection of a number of
physiological indicators in breath. Seven DNA sequences were used
to functionalize SWNT sensors to detect trace amount of methanol,
benzene, dimethyl sulfide, hydrogen sulfide, acetone, and ethanol,
which are indicators of heavy smoking, excessive drinking, and
diseases such as lung cancer, breast cancer, and diabetes. Our test
results indicated that DNA functionalized SWNT sensors exhibit
great selectivity, sensitivity, and repeatability; and different
molecules can be distinguished through pattern recognition enabled
by this sensor array. Furthermore, the experimental sensing results
are consistent with the Molecular Dynamics simulated ssDNAmolecular
target interaction rankings. Thus, the DNA-SWNT sensor
array has great potential to be applied in chemical or biomolecular
detection for the noninvasive diagnostics of diseases and personal
health monitoring.
Abstract: This research paper portrays a comparative analysis of
thermomechanical behaviour of Shielded Metal Arc Welding
(SMAW) and Gas Tungsten Arc Welding (GTAW) of low carbon
steel of AISI 1020 grade butt joints. The thermal history has been
obtained by experimental work. We have focused on temperature
dependent cooling rate as depicted by Adam’s two-dimensional
model. The effect of moving point heat source of SMAW and GTAW
on mechanical properties has been judged by optical and scanning
electron micrographs of different regions in weld joints. The
microhardness study has been carried to visualize the joint strength
due to formation of different phases.
Abstract: The effects of the contact ball-lens on the soda lime
glass in laser thermal cleavage with a cw Nd-YAG laser were
investigated in this study. A contact ball-lens was adopted to generate
a bending force on the crack formation of the soda-lime glass in the
laser cutting process. The Nd-YAG laser beam (wavelength of 1064
nm) was focused through the ball-lens and transmitted to the soda-lime
glass, which was coated with a carbon film on the surface with a
bending force from a ball-lens to generate a tensile stress state on the
surface cracking. The fracture was controlled by the contact ball-lens
and a straight cutting was tested to demonstrate the feasibility.
Experimental observations on the crack propagation from the leading
edge, main section and trailing edge of the glass sheet were compared
with various mechanical and thermal loadings. Further analyses on the
stress under various laser powers and contact ball loadings were made
to characterize the innovative technology. The results show that the distributions of the side crack at the
leading and trailing edges are mainly dependent on the boundary
condition, contact force, cutting speed and laser power. With the
increase of the mechanical and thermal loadings, the region of the side
cracks might be dramatically reduced with proper selection of the
geometrical constrains. Therefore the application of the contact
ball-lens is a possible way to control the fracture in laser cleavage with
improved cutting qualities.
Abstract: The paper will focus on the strategic development
deriving from the evolution of the traditional courtyard spatial
organization towards a new, contemporary sustainable way of living.
New sustainable approaches that engulf the social issues, the notion
of place, the understanding of weather architecture blended together
with the bioclimatic behavior will be seen through a series of
experimental case studies in the island of Cyprus, inspired and
originated from its traditional wisdom, ranging from small scale of
living to urban interventions. Weather and nature will be seen as co-architectural authors with
architects. Furthermore, the building will be seen not as an object but
rather as a vessel of human activities. This will further enhance the
notion of merging the material and immaterial, the built and unbuilt,
subject-human, and the object-building. This eventually will enable
to generate the discussion of the understanding of the building in
relation to the place and its inhabitants, where the human topography
is more important than the material topography. The specificities of
the divided island and the dealing with sites that are in vicinity with
the diving Green Line will further trigger explorations dealing with
the regeneration issues and the social sustainability offering
unprecedented opportunities for innovative sustainable ways of
living. Opening up a discourse with premises of weather-nature, materialimmaterial,
human-material topographies in relation to the contested
sites of the borders will lead us to develop innovative strategies for a
profound, both technical and social sustainability, which fruitfully
yields to innovative living built environments, responding to the ever
changing environmental and social needs. As a starting point, a case study in Kaimakli in Nicosia, a
refurbishment with an extension of a traditional house, already
engulfs all the traditional/ vernacular wisdom of the bioclimatic
architecture. The project focusses on the direct and quite obvious
bioclimatic features such as south orientation and cross ventilation.
Furthermore, it tries to reinvent the adaptation of these parameters in
order to turn the whole house to a contemporary living environment.
In order to succeed this, evolutions of traditional architectural
elements and spatial conditions are integrated in a way that does not
only respond to some certain weather conditions, but they integrate
and blend the weather within the built environment. A series of
innovations aiming at maximum flexibility is proposed. The house
can finally be transformed into a winter enclosure, while for the most
part of the year it turns into a ‘camping’ living environment. Parallel to experimental interventions in existing traditional units,
we will proceed examining the implementation of the same
developed methodology in designing living units and complexes.
Malleable courtyard organizations that attempt to blend the
traditional wisdom with the contemporary needs for living, the
weather and nature with the built environment will be seen tested in
both horizontal and vertical developments. Social activities are seen as directly affected and forged by the
weather conditions thus generating a new social identity of people where people are directly involved and interacting with the weather.
The human actions and interaction with the built, material
environment in order to respond to weather will be seen as the result
of balancing the social with the technological sustainability, the
immaterial, and the material aspects of the living environment.
Abstract: Direct Torque Control (DTC) is an AC drive control
method especially designed to provide fast and robust responses. In
this paper a progressive algorithm for direct torque control of threephase
induction drive system supplied by photovoltaic arrays using
voltage source inverter to control motor torque and flux with
maximum power point tracking at different level of insolation is
presented. Experimental results of the new DTC method obtained by
an experimental rapid prototype system for drives are presented.
Simulation and experimental results confirm that the proposed system
gives quick, robust torque and speed responses at constant switching
frequencies.
Abstract: Electrical Muscle Stimulation (EMS) has been
introduced and globally gained increasing attention on its usefulness.
Continuous application of EMS may lead to the increment of muscle
mass and indirectly will increase the strength. This study can be used
as an alternative to help people especially those living a sedentary
lifestyle to improve their muscle activity without having to go
through a heavy workout session. Therefore, this study intended to
investigate the effectiveness of EMS training program in 5 weeks
interventions towards male body composition. It was a quasiexperimental
design, held at the Impulse Studio Bangsar, which
examined the effects of EMS training towards skeletal muscle mass
among the subjects. Fifteen subjects (n = 15) were selected to assist
in this study. The demographic data showed that, the average age of
the subjects was 43.07 years old ± 9.90, height (173.4 cm ± 9.09) and
weight was (85.79 kg ± 18.07). Results showed that there was a
significant difference on the skeletal muscle mass (p = 0.01 < 0.05),
upper body (p = 0.01 < 0.05) and lower body (p = 0.00 < 0.05).
Therefore, the null hypothesis has been rejected in this study. As a
conclusion, the application of EMS towards body composition can
increase the muscle size and strength. This method has been proven
to be able to improve athlete strength and thus, may be implemented
in the sports science area of knowledge.
Abstract: Local steel slag is produced as a by-product during the
oxidation of steel pellets in an electric arc furnace. Using local steel
slag waste as a hundred substitutes of crashed stone in construction
materials would resolve the environmental problems caused by the
large-scale depletion of the natural sources of crashed stone. This
paper reports the experimental study to investigate the influence of a
hundred replacement of crashed stone as a coarse aggregate with
local steel slag, on the fresh and hardened geopolymer concrete
properties. The investigation includes traditional testing of hardening
concrete, for selected mixes of cement and geopolymer concrete. It
was found that local steel slag as a coarse aggregate enhanced the
slump test of the fresh state of cement and geopolymer concretes.
Nevertheless, the unit weight of concretes was affected. Meanwhile,
the good performance was observed when fly ash used as geopolymer
concrete based.
Abstract: Large-scale machine tools for the manufacturing of
large work pieces, e.g. blades, casings or gears for wind turbines,
feature pose-dependent dynamic behavior. Small structural damping
coefficients lead to long decay times for structural vibrations that
have negative impacts on the production process. Typically, these
vibrations are handled by increasing the stiffness of the structure by
adding mass. This is counterproductive to the needs of sustainable
manufacturing as it leads to higher resource consumption both in
material and in energy. Recent research activities have led to higher
resource efficiency by radical mass reduction that is based on controlintegrated
active vibration avoidance and damping methods. These
control methods depend on information describing the dynamic
behavior of the controlled machine tools in order to tune the
avoidance or reduction method parameters according to the current
state of the machine. This paper presents the appearance, consequences and challenges
of the pose-dependent dynamic behavior of lightweight large-scale
machine tool structures in production. It starts with the theoretical
introduction of the challenges of lightweight machine tool structures
resulting from reduced stiffness. The statement of the pose-dependent
dynamic behavior is corroborated by the results of the experimental
modal analysis of a lightweight test structure. Afterwards, the
consequences of the pose-dependent dynamic behavior of lightweight
machine tool structures for the use of active control and vibration
reduction methods are explained. Based on the state of the art of
pose-dependent dynamic machine tool models and the modal
investigation of an FE-model of the lightweight test structure, the
criteria for a pose-dependent model for use in vibration reduction are
derived. The description of the approach for a general posedependent
model of the dynamic behavior of large lightweight
machine tools that provides the necessary input to the aforementioned
vibration avoidance and reduction methods to properly tackle
machine vibrations is the outlook of the paper.