Abstract: In this paper numerical studies have been carried out
to examine the pre-ignition flow features of high-performance solid
propellant rocket motors with two different port geometries but with
same propellant loading density. Numerical computations have been
carried out using a validated 3D, unsteady, 2nd-order implicit, SST k-
ω turbulence model. In the numerical study, a fully implicit finite
volume scheme of the compressible, Reynolds-Averaged, Navier-
Stokes equations is employed. We have observed from the numerical
results that in solid rocket motors with highly loaded propellants
having divergent port geometry the hot igniter gases can create preignition
pressure oscillations leading to thrust oscillations due to the
flow unsteadiness and recirculation. We have also observed that the
igniter temperature fluctuations are diminished rapidly thereby
reaching the steady state value faster in the case of solid propellant
rocket motors with convergent port than the divergent port
irrespective of the igniter total pressure. We have concluded that the
prudent selection of the port geometry, without altering the propellant
loading density, for damping the total temperature fluctuations within
the motor is a meaningful objective for the suppression and control of
instability and/or thrust oscillations often observed in solid propellant
rocket motors with non-uniform port geometry.
Abstract: The increasing volume of solid waste generated,
collected and disposed daily complicate adequate management of
solid waste by relevant agency like Niger State Environmental
Protection Agency (NISEPA). In addition, the impacts of solid waste
on the natural environment and human livelihood require
identification of cost-effective ways for sustainable municipal waste
management in Nigeria. These signal the need for identifying
environment-friendly initiative and local solution to address the
problem of municipal solid waste. A research field was secured at
Pago, Minna, Niger State which is located in the guinea savanna belt
of Nigeria, within longitude 60 361 4311 - 4511 and latitude 90 291
37.6111 - .6211 N. Poultry droppings, decomposed household waste
manure and NPK treatments were used. The experimental field was
divided into three replications and four (4) treatments on each
replication making a total of twelve (12) plots. The treatments were
allotted using Randomized Complete Block Design (RCBD) and
Data collected was analyzed using SPSS software and RCBD. The
result depicts variation in plant height and number of leaves at 50%
flowering; Poultry dropping records the highest height while the
number of leaves for waste manure competes fairly well with NPK
treatment. Similarly, the varying treatments significantly increase
vegetable yield, as the control (non-treatment) records the least yield
for the three vegetable samples. Adoption of this organic manure for
cultivation does not only enhance environment quality and attainment
of food security but will contribute to local economic development,
poverty alleviation as well as social inclusion.
Abstract: The aim of the current work was to employ the finite
element method to model a slab, with a small hole across its width,
undergoing plastic plane strain deformation. The computational
model had, however, to be validated by comparing its results with
those obtained experimentally. Since they were in good agreement,
the finite element method can therefore be considered a reliable tool
that can help gain better understanding of the mechanism of ductile
failure in structural members having stress raisers. The finite element
software used was ANSYS, and the PLANE183 element was utilized.
It is a higher order 2-D, 8-node or 6-node element with quadratic
displacement behavior. A bilinear stress-strain relationship was used
to define the material properties, with constants similar to those of the
material used in the experimental study. The model was run for
several tensile loads in order to observe the progression of the plastic
deformation region, and the stress concentration factor was
determined in each case. The experimental study involved employing the visioplasticity
technique, where a circular mesh (each circle was 0.5 mm in
diameter, with 0.05 mm line thickness) was initially printed on the
side of an aluminum slab having a small hole across its width.
Tensile loading was then applied to produce a small increment of
plastic deformation. Circles in the plastic region became ellipses,
where the directions of the principal strains and stresses coincided
with the major and minor axes of the ellipses. Next, we were able to
determine the directions of the maximum and minimum shear
stresses at the center of each ellipse, and the slip-line field was then
constructed. We were then able to determine the stress at any point in
the plastic deformation zone, and hence the stress concentration
factor. The experimental results were found to be in good agreement
with the analytical ones.
Abstract: This survey paper shows the recent state of model
comparison as it’s applies to Model Driven engineering. In Model
Driven Engineering to calculate the difference between the models is
a very important and challenging task. There are number of tasks
involved in model differencing that firstly starts with identifying and
matching the elements of the model. In this paper, we discuss how
model matching is accomplished, the strategies, techniques and the
types of the model. We also discuss the future direction. We found
out that many of the latest model comparison strategies are geared
near enabling Meta model and similarity based matching. Therefore
model versioning is the most dominant application of the model
comparison. Recently to work on comparison for versioning has
begun to deteriorate, giving way to different applications. Ultimately
there is wide change among the tools in the measure of client exertion
needed to perform model comparisons, as some require more push to
encourage more sweeping statement and expressive force.
Abstract: This paper presents a study on the effect of
second-order slip and jump on forced convection through a long
isothermally heated or cooled planar microchannel. The fully
developed solutions of thermal flow fields are analytically obtained on
the basis of the second-order Maxwell-Burnett slip and Smoluchowski
jump boundary conditions. Results reveal that the second-order term in
the Karniadakis slip boundary condition is found to contribute a
negative velocity slip and then to lead to a higher pressure drop as well
as a higher fluid temperature for the heated-wall case or to a lower
fluid temperature for the cooled-wall case. These findings are contrary
to predictions made by the Deissler model. In addition, the role of
second-order slip becomes more significant when the Knudsen
number increases.
Abstract: Concrete is strong in compression however weak in
tension. The tensile strength as well as ductile property of concrete
could be improved by addition of short dispersed fibers. Polyethylene
terephthalate (PET) fiber obtained from hand cutting or mechanical
slitting of plastic sheets generally used as discrete reinforcement in
substitution of steel fiber. PET fiber obtained from the former process
is in the form of straight slit sheet pattern that impart weaker
mechanical bonding behavior in the concrete matrix. To improve the
limitation of straight slit sheet fiber the present study considered two
additional geometry of fiber namely (a) flattened end slit sheet and
(b) deformed slit sheet. The mix for plain concrete was design for a
compressive strength of 25 MPa at 28 days curing time with a watercement
ratio of 0.5. Cylindrical and beam specimens with 0.5% fibers
volume fraction and without fibers were cast to investigate the
influence of geometry on the mechanical properties of concrete. The
performance parameters mainly studied include flexural strength,
splitting tensile strength, compressive strength and ultrasonic pulse
velocity (UPV). Test results show that geometry of fiber has a
marginal effect on the workability of concrete. However, it plays a
significant role in achieving a good compressive and tensile strength
of concrete. Further, significant improvement in term of flexural and
energy dissipation capacity were observed from other fibers as
compared to the straight slit sheet pattern. Also, the inclusion of PET
fiber improved the ability in absorbing energy in the post-cracking
state of the specimen as well as no significant porous structures.
Abstract: This paper seeks to assess the implications of
insurance to foreign direct investment inflow in Nigeria. Multiple
linear regression technique and correlation matrix test were employed
to measure the extent to which foreign direct investment was
influenced. The result showed that insurance premium (IP), asset size
of insurance industry (AS), and total investment of the industry (TI)
impacted significantly and positively on foreign direct investment
inflow in Nigeria. There should be effective risk transfer mechanism
and financial intermediation, which gives the investor confidence in
the risk management strength of the host country.
Abstract: Electrohydraulic servo system have been used in
industry in a wide number of applications. Its dynamics are highly
nonlinear and also have large extent of model uncertainties and
external disturbances. In this paper, a robust back-stepping control
(RBSC) scheme is proposed to overcome the problem of disturbances
and system uncertainties effectively and to improve the tracking
performance of EHS systems. In order to implement the proposed
control scheme, the system uncertainties in EHS systems are
considered as total leakage coefficient and effective oil volume. In
addition, in order to obtain the virtual controls for stabilizing system,
the update rule for the system uncertainty term is induced by
the Lyapunov control function (LCF). To verify the performance and
robustness of the proposed control system, computer simulation of
the proposed control system using Matlab/Simulink Software
is executed. From the computer simulation, it was found that the
RBSC system produces the desired tracking performance and has
robustness to the disturbances and system uncertainties of EHS
systems.
Abstract: Expansive soils are often encountered in many parts
of the world, especially in arid and semi-arid fields. Such kind of
soils, generally including active clay minerals in low water content,
enlarge in volume by absorbing the water through the surface and
cause a great harm to the light structures such as channel coating,
roads and airports. The expansive soils were encountered on the path
of Apa-Hotamış conveyance channel belonging to the State
Hydraulic Works in the region of Konya. In the research done in this
area, it is predicted that the soil has a swollen nature and the soil
should be filled with proper granular equipments by digging the
ground to 50-60 cm. In this study, for purpose of helping the other
research to be done in the same area, it is thought that instead of
replacing swollen soil with the granular soil, by stabilizing it with
polypropylene fiber and using it its original place decreases effect of
swelling percent, in this way the cost will be decreased. Therefore,
laboratory tests were conducted to study the effects of polypropylene
fiber on swelling characteristics of expansive soil. Test results
indicated that inclusion of fiber reduced swell percent of expansive
soil. As the fiber content increased, the unconfined compressive
strength was increased. Finally, it can be said that stabilization of
expansive soils with polypropylene fiber is an effective method.
Abstract: Below-knee amputees commonly experience
asymmetrical gait patterns. It is generally believed that ischemia is
related to the formation of pressure sores due to uneven distribution
of forces. Micro-vascular responses can reveal local malnutrition.
Changes in local skin blood supply under various external loading
conditions have been studied for a number of years. Radionuclide
clearance, photo-plethysmography, trans-cutaneous oxygen tension
along with other studies showed that the blood supply would be
influenced by the epidermal forces, and the rate and the amount of
blood supply would decrease with increased epidermal loads being
shear forces or normal forces. Several cases of socket designs were
investigated using Finite Element Model (FEM) and Design of
Experiment (DOE) to increase flexibility and minimize the pressure
at the limb/socket interface using ultra high molecular weight
polyethylene (UHMWPE) and polyamide 6 (PA6) or Duraform. The
pressure reliefs at designated areas where reducing thickness is
involved are seen to be critical in determination of amputees’ comfort
and are very important to clinical applications. Implementing a hole
between the Patellar Tendon (PT) and Distal Tibia (DT) would
decrease stiffness and increase prosthesis range of motion where
flexibility is needed. In addition, displacement and prosthetic energy
storage increased without compromising mechanical efficiency and
prosthetic design integrity.
Abstract: The main objective of MEAL is to develop a
pedagogical tool aimed to help teachers and nutritionists (students
and professionals) to acquire, train, promote and deliver to children
basic nutritional education and healthy eating behaviours
competencies. MEAL is focused on eating behaviours and not only in
nutritional literacy, and will use new technologies like Information
and Communication Technologies (ICTs) and serious games (SG)
platforms to consolidate the nutritional competences and habits.
Abstract: The aim of study was to analyze the functioning the
new model of criminal corporate responsibility in Poland. The need
to introduce into the Polish legal system liability of corporate
(collective entities) has resulted, among others, from the Polish
Republic's international commitments, in particular related to
membership in the European Union. The study showed that responsibility of collective entities under
the Act has a criminal nature. The main question concerns the ability
of the collective entity to be brought to guilt under criminal law
sense. Polish criminal law knows only the responsibility of individual
persons. So far, guilt as a personal feature of action, based on the
ability of the offender to feel in his psyche, could be considered only
in relation to the individual person, while the said Act destroyed this
conviction. Guilt of collective entity must be proven under at least
one of the three possible forms: the guilt in the selection or
supervision and so called organizational guilt. In addition, research in
article has resolved the issue how the principle of proportionality in
relation to criminal measures in response of collective entities should
be considered. It should be remembered that the legal subjectivity of
collective entities, including their rights and freedoms, is an
emanation of the rights and freedoms of individual persons which
create collective entities and through these entities implement their
rights and freedoms. The whole study was proved that the adopted Act largely reflects
the international legal regulations but also contains the unknown and
original legislative solutions.
Abstract: As smartphones are equipped with various sensors,
there have been many studies focused on using these sensors to create
valuable applications. Human activity recognition is one such
application motivated by various welfare applications, such as the
support for the elderly, measurement of calorie consumption, lifestyle
and exercise patterns analyses, and so on. One of the challenges one
faces when using smartphone sensors for activity recognition is that
the number of sensors should be minimized to save battery power. In
this paper, we show that a fairly accurate classifier can be built that
can distinguish ten different activities by using only a single sensor
data, i.e., the smartphone accelerometer data. The approach that we
adopt to deal with this twelve-class problem uses various methods.
The features used for classifying these activities include not only the
magnitude of acceleration vector at each time point, but also the
maximum, the minimum, and the standard deviation of vector
magnitude within a time window. The experiments compared the
performance of four kinds of basic multi-class classifiers and the
performance of four kinds of ensemble learning methods based on
three kinds of basic multi-class classifiers. The results show that
while the method with the highest accuracy is ECOC based on
Random forest.
Abstract: Useful lifetime evaluation of chevron rubber spring
was very important in design procedure to assure the safety and
reliability. It is, therefore, necessary to establish a suitable criterion
for the replacement period of chevron rubber spring. In this study, we
performed characteristic analysis and useful lifetime prediction of
chevron rubber spring. Rubber material coefficient was obtained by
curve fittings of uniaxial tension equibiaxial tension and pure shear
test. Computer simulation was executed to predict and evaluate the
load capacity and stiffness for chevron rubber spring. In order to
useful lifetime prediction of rubber material, we carried out the
compression set with heat aging test in an oven at the temperature
ranging from 50°C to 100°C during a period 180 days. By using the
Arrhenius plot, several useful lifetime prediction equations for rubber
material was proposed.
Abstract: By enhancing the applicatıon of grounds for
establishment and due to the lack of appropriate sites, engineers
attempt to seek out a new method to reduce the weakness of soils. İn
aspect of economic situation, various ways have been used to
decrease the weak grounds. Because of the rapid development of
infrastructural facilities, spreading the construction operation is an
obligation. Furthermore, in various sites with the really bad soil
situation, engineers have considered obvious problems. One of the
most essential ways for developing the weak soils is stone column.
Obviously, the method was introduced in France in 1830 to improve
a native soil initially. Stone columns have an expanding range of
usage in different rough foundation sites all over the world to
increase the bearing capacity, to reduce the whole and differential
settlements, to enhance the rate of consolidation, to stabilize slopes
stability of embankments and to increase the liquefaction resistance
as well. A recent procedure called installing vertical nails along the
round stone columns in order to make better the performance of
considered columns is offered. Moreover, thanks to the enhancing the
nail diameter, number and embedment nail depth, the positive points
of vertical circumferential nails increases. Based on the result of this
study, load caring capacity will be develop with enhancing the length
and the power of reinforcements in vertical encasement stone column
(CESC). In this study, the main purpose is comparing two methods of
stone columns (installed a nail surrounding the stone columns and
using geogrid on clay) for enhancing the bearing capacity, decreasing
the whole and various settlements.
Abstract: An investigation has been presented to analyze the
effect of internal heat source on the onset of Hadley-Prats flow in
a horizontal fluid saturated porous medium. We examine a better
understanding of the combined influence of the heat source and mass
flow effect by using linear stability analysis. The resultant eigenvalue
problem is solved by using shooting and Runga-Kutta methods for
evaluate critical thermal Rayleigh number with respect to various
flow governing parameters. It is identified that the flow is switch from
stabilizing to destabilizing as the horizontal thermal Rayleigh number
is enhanced. The heat source and mass flow increases resulting a
stronger destabilizing effect.
Abstract: The global demand for long-tailed macaques for
medical experimentation has continued to increase. Fulfillment of
Indonesian export demands has been mostly from natural habitats,
based on a harvesting quota. This quota has been determined
according to the total catch for a given year, and not based on
consideration of any demographic parameters or physical
environmental factors with regard to the animal; hence threatening
the sustainability of the various populations. It is therefore necessary
to formulate a method for calculating a sustainable harvesting quota,
based on population parameters in natural habitats. Considering the
possibility of variations in habitat characteristics and population
parameters, a time series observation of demographic and
physical/biotic parameters, in various habitats, was performed on 13
groups of long-tailed macaques, distributed throughout the West
Java, Lampung and Yogyakarta areas of Indonesia. These provinces
were selected for comparison of the influence of human/tourism
activities. Data on population parameters that was collected included
data on life expectancy according to age class, numbers of
individuals by sex and age class, and ‘ratio of infants to reproductive
females’. The estimation of population growth was based on a
population dynamic growth model: the Leslie matrix. The harvesting
quota was calculated as being the difference between the actual
population size and the MVP (minimum viable population) for each
sex and age class. Observation indicated that there were variations within group size
(24–106 individuals), gender (sex) ratio (1:1 to 1:1.3), life expectancy
value (0.30 to 0.93), and ‘ratio of infants to reproductive females’
(0.23 to 1.56). Results of subsequent calculations showed that
sustainable harvesting quotas for each studied group of long-tailed
macaques, ranged from 29 to 110 individuals. An estimation model
of the MVP for each age class was formulated as Log Y = 0.315 +
0.884 Log Ni (number of individual on ith age class). This study also
found that life expectancy for the juvenile age class was affected by
the humidity under tree stands, and dietary plants’ density at sapling,
pole and tree stages (equation: Y=2.296 – 1.535 RH + 0.002 Kpcg –
0.002 Ktg – 0.001 Kphn, R2 = 89.6% with a significance value of
0.001). By contrast, for the sub-adult-adult age class, life expectancy
was significantly affected by slope (equation: Y=0.377 = 0.012 Kml,
R2 = 50.4%, with significance level of 0.007). The infant-toreproductive-
female ratio was affected by humidity under tree stands,
and dietary plant density at sapling and pole stages (equation: Y = -
1.432 + 2.172 RH – 0.004 Kpcg + 0.003 Ktg, R2 = 82.0% with
significance level of 0.001). This research confirmed the importance
of population parameters in determining the minimum viable
population, and that MVP varied according to habitat characteristics
(especially food availability). It would be difficult therefore, to
formulate a general mathematical equation model for determining a
harvesting quota for the species as a whole.
Abstract: Sewer deposits have been identified as a major cause
of dysfunctions in combined sewer systems regarding sewer
management, which induces different negative consequents resulting
in poor hydraulic conveyance, environmental damages as well as
worker’s health. In order to overcome the problematics of
sedimentation, flushing has been considered as the most operative
and cost-effective way to minimize the sediments impacts and
prevent such challenges. Flushing, by prompting turbulent wave
effects, can modify the bed form depending on the hydraulic
properties and geometrical characteristics of the conduit. So far, the
dynamics of the bed-load during high-flow events in combined sewer
systems as a complex environment is not well understood, mostly due
to lack of measuring devices capable to work in the “hostile” in
combined sewer system correctly. In this regards, a one-episode
flushing issue from an opening gate valve with weir function was
carried out in a trunk sewer in Paris to understand its cleansing
efficiency on the sediments (thickness: 0-30 cm). During more than
1h of flushing within 5 m distance in downstream of this flushing
device, a maximum flowrate and a maximum level of water have
been recorded at 5 m in downstream of the gate as 4.1 m3/s and 2.1
m respectively. This paper is aimed to evaluate the efficiency of this
type of gate for around 1.1 km (from the point -50 m to +1050 m in
downstream from the gate) by (i) determining bed grain-size
distribution and sediments evolution through the sewer channel, as
well as their organic matter content, and (ii) identifying sections that
exhibit more changes in their texture after the flush. For the first one,
two series of sampling were taken from the sewer length and then
analyzed in laboratory, one before flushing and second after, at same
points among the sewer channel. Hence, a non-intrusive sampling
instrument has undertaken to extract the sediments smaller than the
fine gravels. The comparison between sediments texture after the
flush operation and the initial state, revealed the most modified zones
by the flush effect, regarding the sewer invert slope and hydraulic
parameters in the zone up to 400 m from the gate. At this distance,
despite the increase of sediment grain-size rages, D50 (median grainsize)
varies between 0.6 mm and 1.1 mm compared to 0.8 mm and 10
mm before and after flushing, respectively. Overall, regarding the
sewer channel invert slope, results indicate that grains smaller than
sands (< 2 mm) are more transported to downstream along about 400
m from the gate: in average 69% before against 38% after the flush
with more dispersion of grain-sizes distributions. Furthermore, high
effect of the channel bed irregularities on the bed material evolution
has been observed after the flush.
Abstract: This study integrates a larger research empirical
project that examines second language (SL) learners’ profiles and
valid procedures to perform complete and diagnostic assessment in
schools. 102 learners of Portuguese as a SL aged 7 and 17 years
speakers of distinct home languages were assessed in several
linguistic tasks. In this article, we focused on writing performance in
the specific task of narrative essay composition. The written outputs
were measured using the score in six components adapted from an
English SL assessment context (Alberta Education): linguistic
vocabulary, grammar, syntax, strategy, socio-linguistic, and
discourse. The writing processes and strategies in Portuguese
language used by different immigrant students were analysed to
determine features and diversity of deficits on authentic texts
performed by SL writers. Differentiated performance was based on
the diversity of the following variables: grades, previous schooling,
home language, instruction in first language, and exposure to
Portuguese as Second Language. Indo-Aryan languages speakers
showed low writing scores compared to their peers and the type of
language and respective cognitive mapping (such as Mandarin and
Arabic) was the predictor, not linguistic distance. Home language
instruction should also be prominently considered in further research
to understand specificities of cognitive academic profile in a
Romance languages learning context. Additionally, this study also
examined the teachers’ representations that will be here addressed to
understand educational implications of second language teaching in
psychological distress of different minorities in schools of specific
host countries.
Abstract: Work presented is interested in the characterization of
the quasistatic mechanical properties and in fatigue of a composite
laminated in jute/epoxy. The natural fibers offer promising prospects
thanks to their interesting specific properties, because of their low
density, but also with their bio-deterioration. Several scientific
studies highlighted the good mechanical resistance of the vegetable
fiber composites reinforced, even after several recycling. Because of
the environmental standards that become increasingly severe, one
attends the emergence of eco-materials at the base of natural fibers
such as flax, bamboo, hemp, sisal, jute. The fatigue tests on
elementary vegetable fibers show an increase of about 60% of the
rigidity of elementary fibers of hemp subjected to cyclic loadings. In
this study, the test-tubes manufactured by the method infusion have
sequences of stacking of 0/90° and ± 45° for the shearing and tensile
tests. The quasistatic tests reveal a variability of the mechanical
properties of about 8%. The tensile fatigue tests were carried out for
levels of constraints equivalent to half of the ultimate values of the
composite. Once the fatigue tests carried out for well-defined values
of cycles, a series of static tests of traction type highlights the
influence of the number of cycles on the quasi-static mechanical
behavior of the laminate jute/epoxy.