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 goal of the modern education system is to prepare
students to be able to adapt to ever-changing life situations. They
must be able to acquire required knowledge independently; apply
such knowledge in practice to solve various problems by using
modern technologies; think critically and creatively; competently use
information; be communicative, work in a team; and develop their
own moral values, intellect and cultural awareness. As a result, the
status of education significantly increases; new requirements to its
quality have been formed. In recent years the competency-based
approach in education has become of significant interest. This
approach is a strengthening of applied and practical characteristics of
a school education and leads to the forming of the key students’
competencies which define their success in future life. In this article,
the authors’ attention focuses on a range of key competencies,
educational, informational and communicative and on the possibility
to develop such competencies via STEM education. This research
shows the change in students’ attitude towards scientific disciplines
such as mathematics, general science, technology and engineering as
a result of STEM education. Two staged analyzed questionnaires
completed by students of forms II to IV in the republic of Trinidad
and Tobago allowed the authors to categorize students between two
levels that represent students’ attitude to various disciplines. The
significance of differences between selected levels was confirmed
with the use of Pearson’s chi-squared test. In summary, the analysis
of obtained data makes it possible to conclude that STEM education
has a great potential for development of core students’ competencies
and encourage the development of positive student attitude towards
the above mentioned above scientific disciplines.
Abstract: The teaching of computer programming for beginners
has been generally considered as a difficult and challenging task.
Several methodologies and research tools have been developed,
however, the difficulty of teaching still remains. Our work integrates
the state of the art in teaching programming with game software and
further provides metrics for the evaluation of student performance in
a collaborative activity of playing games. This paper aims to present a
multi-agent system architecture to be incorporated to the educational
collaborative game software for teaching programming that monitors,
evaluates and encourages collaboration by the participants. A
literature review has been made on the concepts of Collaborative
Learning, Multi-agents systems, collaborative games and techniques
to teach programming using these concepts simultaneously.
Abstract: This research paper presents the current practices of
teacher professional development, perceived as beneficial by teachers
themselves, in a private secondary school in Brunei Darussalam. This
is part of the findings of a larger qualitative study on teacher
empowerment, using ethnographic methods for data collection, i.e.
participant observation, interviews and document analysis. The field
work was carried out over a period of six months in 2013. An
analysis of the field data revealed multiple pathways of teacher
professional development existing in the school. The results indicate
that school leaders, the teacher community in the school, students,
and the teachers themselves were the agents in a school that
facilitated teacher empowerment. Besides contributing to the
knowledge base on teacher professional development, the results of
this study provide directions for educational policy makers in their
efforts to enhance professional development in secondary schools of
similar characteristics. For school leaders and the teacher community,
these findings offer guidelines for maximizing the opportunities for
these professional development practices, by strengthening
collegiality and by using the existing structures optimally for the
benefit of all concerned.
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: The Multiple Intelligences theory characterizes human
intelligence as a multifaceted entity that exists in all human beings
with varying degrees. The most important contribution of this theory
to the field of English Language Teaching (ELT) is its role in
identifying individual differences and designing more learnercentered
programs. The present study aims at investigating the
relationship between different elements of multiple intelligence and
grammar scores. To this end, 63 female Iranian EFL learner selected
from among intermediate students participated in the study. The
instruments employed were a Nelson English language test, Michigan
Grammar Test, and Teele Inventory for Multiple Intelligences
(TIMI). The results of Pearson Product-Moment Correlation revealed
a significant positive correlation between grammatical accuracy and
linguistic as well as interpersonal intelligence. The results of
Stepwise Multiple Regression indicated that linguistic intelligence
contributed to the prediction of grammatical accuracy.
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: 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: Discursive practices enacted by educators in
kindergarten create a blueprint for how the educational trajectories of
students with disabilities are constructed. This two-year ethnographic
case study critically examines educators’ relationships with students
considered to present challenging behaviors in one kindergarten
classroom located in a predominantly White middle class school
district in the Northeast of the United States. Focusing on the
language and practices used by one special education teacher and
three teaching assistants, this paper analyzes how teacher responses
to students’ behaviors constructs and positions students over one year
of kindergarten education. Using a critical discourse analysis it shows
that educators understand students’ behaviors as deficit and needing
consequences. This study highlights how educators’ responses reflect
students' individual characteristics including family background,
socioeconomics and ability status. This paper offers in depth analysis
of two students’ stories, which evidenced that the language used by
educators amplifies the social positioning of students within the
classroom and creates a foundation for who they are constructed to
be. Through exploring routine language and practices, this paper
demonstrates that educators outlined a blueprint of kindergartners,
which positioned students as learners in ways that became the ground
for either a limited or a promising educational pathway for them.
Abstract: In this article, we deal with a variant of the classical
course timetabling problem that has a practical application in many
areas of education. In particular, in this paper we are interested in
high schools remedial courses. The purpose of such courses is to
provide under-prepared students with the skills necessary to succeed
in their studies. In particular, a student might be under prepared in
an entire course, or only in a part of it. The limited availability
of funds, as well as the limited amount of time and teachers at
disposal, often requires schools to choose which courses and/or which
teaching units to activate. Thus, schools need to model the training
offer and the related timetabling, with the goal of ensuring the
highest possible teaching quality, by meeting the above-mentioned
financial, time and resources constraints. Moreover, there are some
prerequisites between the teaching units that must be satisfied. We
first present a Mixed-Integer Programming (MIP) model to solve
this problem to optimality. However, the presence of many peculiar
constraints contributes inevitably in increasing the complexity of
the mathematical model. Thus, solving it through a general-purpose
solver may be performed for small instances only, while solving
real-life-sized instances of such model requires specific techniques
or heuristic approaches. For this purpose, we also propose a heuristic
approach, in which we make use of a fast constructive procedure
to obtain a feasible solution. To assess our exact and heuristic
approaches we perform extensive computational results on both
real-life instances (obtained from a high school in Lecce, Italy) and
randomly generated instances. Our tests show that the MIP model is
never solved to optimality, with an average optimality gap of 57%.
On the other hand, the heuristic algorithm is much faster (in about the
50% of the considered instances it converges in approximately half of
the time limit) and in many cases allows achieving an improvement
on the objective function value obtained by the MIP model. Such an
improvement ranges between 18% and 66%.
Abstract: This paper presents a methodology for probabilistic
assessment of bearing capacity and prediction of failure mechanism
of masonry vaults at the ultimate state with consideration of the
natural variability of Young’s modulus of stones. First, the
computation model is explained. The failure mode corresponds to the
four-hinge mechanism. Based on this consideration, the study of a
vault composed of 16 segments is presented. The Young’s modulus of
the segments is considered as random variable defined by a mean
value and a coefficient of variation. A relationship linking the vault
bearing capacity to the voussoirs modulus variation is proposed. The
most probable failure mechanisms, in addition to that observed in the
deterministic case, are identified for each variability level as well as
their probability of occurrence. The results show that the mechanism
observed in the deterministic case has decreasing probability of
occurrence in terms of variability, while the number of other
mechanisms and their probability of occurrence increases with the
coefficient of variation of Young’s modulus. This means that if a
significant change in the Young’s modulus of the segments is proven,
taking it into account in computations becomes mandatory, both for
determining the vault bearing capacity and for predicting its failure
mechanism.
Abstract: Main objective of this paper is to establish a link
between inertial forces of the bearings used in construction of wind
power plant and its behavior. Using bearings with lower inertial
forces has the immediate effect of decreasing inertia rotor system,
with significant results in increased energy efficiency, due to
decreased friction forces between rollers and raceways. The F.E.M.
analysis shows the appearance of uniform contact stress at the ends of
the rollers, demonstrated the necessity of production of low mass
bearings. Favorable results are expected in the economic field, by
reducing material consumption and by increasing the durability of
bearings. Using low mass bearings with hollow rollers instead of
solid rollers has an impact on working temperature, on vibrations and
noise which decrease. Implementation of types of hollow rollers of
cylindrical tubular type, instead of expensive rollers with logarithmic
profile, will bring significant inertial forces decrease with large
benefits in behavior of wind power plant.
Abstract: Localization of nodes is one of the key issues of
Wireless Sensor Network (WSN) that gained a wide attention in
recent years. The existing localization techniques can be generally
categorized into two types: range-based and range-free. Compared
with rang-based schemes, the range-free schemes are more costeffective,
because no additional ranging devices are needed. As a
result, we focus our research on the range-free schemes. In this paper
we study three types of range-free location algorithms to compare the
localization error and energy consumption of each one. Centroid
algorithm requires a normal node has at least three neighbor anchors,
while DV-hop algorithm doesn’t have this requirement. The third
studied algorithm is the amorphous algorithm similar to DV-Hop
algorithm, and the idea is to calculate the hop distance between two
nodes instead of the linear distance between them. The simulation
results show that the localization accuracy of the amorphous
algorithm is higher than that of other algorithms and the energy
consumption does not increase too much.
Abstract: Studying on the response of vegetation phenology to
climate change at different temporal and spatial scales is important for
understanding and predicting future terrestrial ecosystem dynamics
and the adaptation of ecosystems to global change. In this study, the
Moderate Resolution Imaging Spectroradiometer (MODIS)
Normalized Difference Vegetation Index (NDVI) dataset and climate
data were used to analyze the dynamics of grassland phenology as well
as their correlation with climatic factors in different eco-geographic
regions and elevation units across the Tibetan Plateau. The results
showed that during 2003–2012, the start of the grassland greening
season (SOS) appeared later while the end of the growing season
(EOS) appeared earlier following the plateau’s precipitation and heat
gradients from southeast to northwest. The multi-year mean value of
SOS showed differences between various eco-geographic regions and
was significantly impacted by average elevation and regional average
precipitation during spring. Regional mean differences for EOS were
mainly regulated by mean temperature during autumn. Changes in
trends of SOS in the central and eastern eco-geographic regions were
coupled to the mean temperature during spring, advancing by about
7d/°C. However, in the two southwestern eco-geographic regions,
SOS was delayed significantly due to the impact of spring
precipitation. The results also showed that the SOS occurred later with
increasing elevation, as expected, with a delay rate of 0.66 d/100m.
For 2003–2012, SOS showed an advancing trend in low-elevation
areas, but a delayed trend in high-elevation areas, while EOS was
delayed in low-elevation areas, but advanced in high-elevation areas.
Grassland SOS and EOS changes may be influenced by a variety of
other environmental factors in each eco-geographic region.
Abstract: Method of combined teaching laws of classical
mechanics and hydrostatics in non-inertial reference frames for
undergraduate students is proposed. Pressure distribution in a liquid
(or gas) moving with acceleration is considered. Combined effect of
hydrostatic force and force of inertia on a body immersed in a liquid
can lead to paradoxical results, in a motion of pendulum in particular.
The body motion under Stokes force influence and forces in rotating
reference frames are investigated as well. Problems and difficulties in
student perceptions are analyzed.
Abstract: In this paper comprehensive studies have been carried
out for the design optimization of a waste heat recovery system for
effectively utilizing the domestic air conditioner heat energy for
producing hot water. Numerical studies have been carried for the
geometry optimization of a waste heat recovery system for domestic
air conditioners. Numerical computations have been carried out using
a validated 2d pressure based, 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. At identical inflow and boundary
conditions various geometries were tried and effort has been taken for
proposing the best design criteria. Several combinations of pipe line
shapes viz., straight and spiral with different number of coils for the
radiator have been attempted and accordingly the design criteria has
been proposed for the waste heat recovery system design. We have
concluded that, within the given envelope, the geometry optimization
is a meaningful objective for getting better performance of waste heat
recovery system for air conditioners.
Abstract: Bloom’s Taxonomy has been changed during the
years. The idea of this writing is about the revision that has happened
in both facts and terms. It also contains case studies of using
cognitive Bloom’s taxonomy in teaching geometric solids to the
secondary school students, affective objectives in a creative
workshop for adults and psychomotor objectives in fixing a
malfunctioned refrigerator lamp. There is also pointed to the
important role of classification objectives in adult education as a way
to prevent memory loss.
Abstract: High Order Thinking Skills (HOTS) are suggested
today as essential for the cognitive development of students and as
preparing them for real life skills. Teachers are encouraged to use
HOTS activities in the classroom to help their students develop
higher order skills and deep thinking. So it is essential to prepare preservice
teachers to write and use HOTS activities for their students.
This paper describes a model for integrating HOTS activities with
GeoGebra in pre-service teachers’ preparation. This model describes
four aspects of HOTS activities and working with them: activity
components, preparation procedure, strategies and processes used in
writing a HOTS activity and types of the HOTS activities. In
addition, the paper describes the pre-service teachers' difficulties in
preparing and working with HOTS activities, as well as their
perceptions regarding the use of these activities and GeoGebra in the
mathematics classroom. The paper also describes the contribution of
a HOTS activity to pupils' learning of mathematics, where this HOTS
activity was prepared and taught by one pre-service teacher.
Abstract: The goal of this paper is to present the diagnostic
contribution that the screening instrument, Mini-Mental State
Examination-2: Expanded Version (MMSE-2:EV), brings in
detecting the cognitive impairment or in monitoring the progress of
degenerative disorders. The diagnostic signification is underlined by
the interpretation of the MMSE-2:EV scores, resulted from the test
application to patients with mild and major neurocognitive disorders.
The cases were selected from current practice, in order to cover vast
and significant neurocognitive pathology: mild cognitive impairment,
Alzheimer’s disease, vascular dementia, mixed dementia, Parkinson’s
disease, conversion of the mild cognitive impairment into
Alzheimer’s disease. The MMSE-2:EV version was used: it was
applied one month after the initial assessment, three months after the
first reevaluation and then every six months, alternating the blue and
red forms. Correlated with age and educational level, the raw scores
were converted in T scores and then, with the mean and the standard
deviation, the z scores were calculated. The differences of raw scores
between the evaluations were analyzed from the point of view of
statistic signification, in order to establish the progression in time of
the disease. The results indicated that the psycho-diagnostic approach
for the evaluation of the cognitive impairment with MMSE-2:EV is
safe and the application interval is optimal. In clinical settings with a
large flux of patients, the application of the MMSE-2:EV is a safe
and fast psychodiagnostic solution. The clinicians can draw objective
decisions and for the patients: it does not take too much time and
energy, it does not bother them and it doesn’t force them to travel
frequently.
Abstract: A Rice Sheller is used for obtaining polished white
rice from paddy. There are about 3000 Rice Shellers in Punjab and
50000 in India. During the process of shelling lot of dust is emitted
from different unit operations like paddy silo, paddy shaker, bucket
elevators, huskers, paddy separator etc. These dust emissions have
adverse effect on the health of the workers and the wear and tear of
the shelling machinery is fast. All the dust emissions spewing out of
these unit operations of a rice Sheller were contained by providing
suitable hoods and enclosures while ensuring their workability. These
were sucked by providing an induced draft fan followed by a high
efficiency cyclone separator that has got an overall dust collection
efficiency of more than 90%. This cyclone separator replaced two
cyclone separators and a filter bag house, which the Rice Sheller was
already having. The dust concentration in the stack after the
installation of cyclone separator is well within the stipulated
standards. Besides controlling pollution, there is improvement in the
quality of products like bran and the life of shelling machinery has
enhanced. The payback period of this technology is less than four
shelling months.