Abstract: Sub-Saharan Africa is described as the second fastest
growing in mobile phone penetration in the world more than in the
United States or the European Union. Mobile phones have been used
to provide a lot of opportunities to improve people’s lives in the
region such as in banking, marketing, entertainment, and paying for
various bills such as water, TV, and electricity. However, the
potential of mobile phones to enhance teaching and learning has not
been explored. This study presents an experience of developing and
delivering SMS based quiz questions used to assess mastery of
subject content knowledge of science and mathematics secondary
school teachers in Tanzania. The SMS quizzes were used as a follow
up support mechanism to 500 teachers who participated in a project
to upgrade subject content knowledge of teachers in science and
mathematics subjects in Tanzania. Quizzes of 10-15 questions were
sent to teachers each week for 8 weeks and the results were analyzed
using SPSS. Results show that teachers who participated in chemistry
and biology subjects have better performance compared to those who
participated in mathematics and physics subjects. Teachers reported
some challenges that led to poor performance, This research has
several practical implications for those who are implementing or
planning to use mobile phones in teaching and learning especially in
rural secondary schools in sub-Saharan Africa.
Abstract: A solar receiver is designed for operation under
extremely uneven heat flux distribution, cyclic weather, and cloud
transient cycle conditions, which can include large thermal stress and
even receiver failure. In this study, the effect of different oil velocity
on convection coefficient factor and impact of wind velocity on local
Nusselt number by Finite Volume Method will be analyzed. This
study is organized to give an overview of the numerical modeling
using a MATLAB software, as an accurate, time efficient and
economical way of analyzing the heat transfer trends over stationary
receiver tube for different Reynolds number. The results reveal when
oil velocity is below 0.33m/s, the value of convection coefficient is
negligible at low temperature. The numerical graphs indicate that
when oil velocity increases up to 1.2 m/s, heat convection coefficient
increases significantly. In fact, a reduction in oil velocity causes a
reduction in heat conduction through the glass envelope. In addition,
the different local Nusselt number is reduced when the wind blows
toward the concave side of the collector and it has a significant effect
on heat losses reduction through the glass envelope.
Abstract: A method of effective planning and control of
industrial facility energy consumption is offered. The method allows
optimally arranging the management and full control of complex
production facilities in accordance with the criteria of minimal
technical and economic losses at the forecasting control. The method
is based on the optimal construction of the power efficiency
characteristics with the prescribed accuracy. The problem of optimal
designing of the forecasting model is solved on the basis of three
criteria: maximizing the weighted sum of the points of forecasting
with the prescribed accuracy; the solving of the problem by the
standard principles at the incomplete statistic data on the basis of
minimization of the regularized function; minimizing the technical
and economic losses due to the forecasting errors.
Abstract: Background: Maintaining the correct body balance is
essential in the prevention of falls in the elderly, which is especially
important for women because of postmenopausal osteoporosis and
the serious consequences of falls. One of the exercise methods which
is very popular among adults, and which may affect body balance in
the positive way is the Pilates method. The aim of the study was to
evaluate the effect of regular Pilates exercises on the ability to
maintain body balance in static conditions in adult healthy women.
Material and methods: The study group consisted of 20 healthy
women attending Pilates twice a week for at least 1 year. The control
group consisted of 20 healthy women physically inactive. Women in
the age range from 35 to 50 years old without pain in musculoskeletal
system or other pain were only qualified to the groups. Body balance
was assessed using MatScan VersaTek platform with Sway Analysis
Module based on Matscan Clinical 6.7 software (Tekscan Inc.,
U.S.A). The balance was evaluated under the following conditions:
standing on both feet with eyes open, standing on both feet with eyes
closed, one-leg standing (separately on the right and left foot) with
eyes open. Each test lasted 30 seconds. The following parameters
were calculated: estimated size of the ellipse of 95% confidence, the
distance covered by the Center of Gravity (COG), the size of the
maximum shift in the sagittal and frontal planes and load distribution
between the left and right foot, as well as between rear- and forefoot.
Results: It was found that there is significant difference between the
groups in favor of the study group in the size of the confidence
ellipse and maximum shifts of COG in the sagittal plane during
standing on both feet, both with the eyes open and closed (p
Abstract: The purposes of hydraulic gate are to maintain the
functions of storing and draining water. It bears long-term hydraulic
pressure and earthquake force and is very important for reservoir and
waterpower plant. The high tensile strength of steel plate is used as
constructional material of hydraulic gate. The cracks and rusts,
induced by the defects of material, bad construction and seismic
excitation and under water respectively, thus, the mechanics
phenomena of gate with crack are probing into the cause of stress
concentration, induced high crack increase rate, affect the safety and
usage of hydroelectric power plant. Stress distribution analysis is a
very important and essential surveying technique to analyze
bi-material and singular point problems. The finite difference
infinitely small element method has been demonstrated, suitable for
analyzing the buckling phenomena of welding seam and steel plate
with crack. Especially, this method can easily analyze the singularity
of kink crack. Nevertheless, the construction form and deformation
shape of some gates are three-dimensional system. Therefore, the
three-dimensional Digital Image Correlation (DIC) has been
developed and applied to analyze the strain variation of steel plate with
crack at weld joint. The proposed Digital image correlation (DIC)
technique is an only non-contact method for measuring the variation of
test object. According to rapid development of digital camera, the cost
of this digital image correlation technique has been reduced.
Otherwise, this DIC method provides with the advantages of widely
practical application of indoor test and field test without the restriction
on the size of test object. Thus, the research purpose of this research is
to develop and apply this technique to monitor mechanics crack
variations of weld steel hydraulic gate and its conformation under
action of loading. The imagines can be picked from real time
monitoring process to analyze the strain change of each loading stage.
The proposed 3-Dimensional digital image correlation method,
developed in the study, is applied to analyze the post-buckling
phenomenon and buckling tendency of welded steel plate with crack.
Then, the stress intensity of 3-dimensional analysis of different
materials and enhanced materials in steel plate has been analyzed in
this paper. The test results show that this proposed three-dimensional
DIC method can precisely detect the crack variation of welded steel
plate under different loading stages. Especially, this proposed DIC
method can detect and identify the crack position and the other flaws
of the welded steel plate that the traditional test methods hardly detect
these kind phenomena. Therefore, this proposed three-dimensional
DIC method can apply to observe the mechanics phenomena of
composite materials subjected to loading and operating.
Abstract: Botanical gardens are very significant organizations
which protect the environment against the increasing environmental
problems, provide environmental education for people, offer
recreation possibilities, etc. This article describes botanical gardens
and their functions. The most important function of botanical garden
is to provide environmental education for people and improve
environmental awareness. Considering this function, some botanical
gardens were examined and opinions were suggested about the
subject.
Abstract: Unemployment among the youth is a significant
problem in South Africa. Large corporations and the public sector
simply cannot create enough jobs. Too many youths in South Africa
currently do not consider entrepreneurship as an option in order to
become independent. Unlike the youth of the Netherlands, South
African youth prefer to find employment in the public or private
sector. The Netherlands has a much lower unemployment rate than
South Africa and the Dutch are generally very entrepreneurial. From
early on, entrepreneurship is considered a desirable career option in
the Netherlands. The purpose of this study was to determine whether
there is a difference in the perceptions of some Dutch and South
African students in terms of unemployment and entrepreneurship.
Questionnaires were distributed to students at the North West
University's Vaal Triangle campus in Vanderbijlpark in Gauteng,
South Africa and the Technical University of Delft in the
Netherlands. A descriptive statistical analysis approach was followed
and the means for the independent questions were calculated. The
results demonstrate that the Dutch students are not as concerned
about unemployment after completion of their studies as this is not as
significant a problem as it is in South Africa. Both groups had
positive responses towards the posed questions, but the South African
group felt more strongly about the issues. Both groups of students felt
that there was a need for more practical entrepreneurship training.
The South African education system should focus on practical
entrepreneurship training from a young age.
Abstract: A Multi-dimensional computational fluid dynamics
(CFD) two-phase model was developed with the aim to simulate
the in-core coolant circuit of a pressurized heavy water reactor
(PHWR) of a commercial nuclear power plant (NPP). Due to the
fact that this PHWR is a Reactor Pressure Vessel type (RPV),
three-dimensional (3D) detailed modelling of the large reservoirs of
the RPV (the upper and lower plenums and the downcomer) were
coupled with an in-house finite volume one-dimensional (1D) code
in order to model the 451 coolant channels housing the nuclear fuel.
Regarding the 1D code, suitable empirical correlations for taking into
account the in-channel distributed (friction losses) and concentrated
(spacer grids, inlet and outlet throttles) pressure losses were used.
A local power distribution at each one of the coolant channels
was also taken into account. The heat transfer between the coolant
and the surrounding moderator was accurately calculated using a
two-dimensional theoretical model. The implementation of subcooled
boiling and condensation models in the 1D code along with the use
of functions for representing the thermal and dynamic properties of
the coolant and moderator (heavy water) allow to have estimations
of the in-core steam generation under nominal flow conditions for a
generic fission power distribution. The in-core mass flow distribution
results for steady state nominal conditions are in agreement with the
expected from design, thus getting a first assessment of the coupled
1/3D model. Results for nominal condition were compared with
those obtained with a previous 1/3D single-phase model getting more
realistic temperature patterns, also allowing visualize low values of
void fraction inside the upper plenum. It must be mentioned that the
current results were obtained by imposing prescribed fission power
functions from literature. Therefore, results are showed with the aim
of point out the potentiality of the developed model.
Abstract: In this study, static and dynamic responses of a typical
reinforced concrete solid slab, designed to British Standard (BS 8110:
1997) and under self and live loadings for dance halls are reported.
Linear perturbation analysis using finite element method was
employed for modal, impulse loading and frequency response
analyses of the slab under the aforementioned loading condition.
Results from the static and dynamic analyses, comprising of the slab
fundamental frequencies and mode shapes, dynamic amplification
factor, maximum deflection, stress distributions among other
valuable outcomes are presented and discussed. These were gauged
with the limiting provisions in the design code with a view of
justifying valid optimization objective function for the structure that
can ensure both adequate strength and economical section for large
clear span slabs. This is necessary owing to the continued increase in
cost of erecting building structures and the squeeze on public finance
globally.
Abstract: The purpose of this paper is to contribute to the
enhancement of a hydroelectric plant protection by coordinating
protection measures / existing security and introducing new measures
under a risk management process. In addition, plan identifies key
critical elements of a hydroelectric plant, from its level vulnerabilities
and threats it is subjected to in order to achieve the necessary
protection measures to reduce the level of risk.
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.
Abstract: Excessive fretting wear at the taper-trunnion junction
(trunnionosis) apparently contributes to the high failure rates of hip
implants. Implant wear and corrosion lead to the release of metal
particulate debris and subsequent release of metal ions at the tapertrunnion
surface. This results in a type of metal poisoning referred to
as metallosis. The consequences of metal poisoning include;
osteolysis (bone loss), osteoarthritis (pain), aseptic loosening of the
prosthesis and revision surgery. Follow up after revision surgery,
metal debris particles are commonly found in numerous locations. Background: A stable connection between the femoral ball head
(taper) and stem (trunnion) is necessary to prevent relative motions
and corrosion at the taper junction. Hence, the importance of
component assembly cannot be over-emphasized. Therefore, the aim
of this study is to determine the influence of head-stem junction
assembly by press fitting and the subsequent
disengagement/disassembly on the connection strength between the
taper ball head and stem. Methods: CoCr femoral heads were assembled with High stainless
hydrogen steel stem (trunnion) by Push-in i.e. press fit; and
disengaged by pull-out test. The strength and stability of the two
connections were evaluated by measuring the head pull-out forces
according to ISO 7206-10 standards. Findings: The head-stem junction strength linearly increases with
assembly forces.
Abstract: Polycyclic Aromatic Hydrocarbons (PAHs) are
formed mainly because of incomplete combustion of organic
materials during industrial, domestic activities or natural occurrence.
Their toxicity and contamination of terrestrial and aquatic ecosystem
have been established. However, with limited validity index, previous
research has focused on PAHs isomer pair ratios of variable
physicochemical properties in source identification. The objective of
this investigation was to determine the empirical validity of Pearson
Correlation Coefficient (PCC) and Cluster Analysis (CA) in PAHs
source identification along soil samples of different land uses.
Therefore, 16 PAHs grouped, as Endocrine Disruption Substances
(EDSs) were determined in 10 sample stations in top and sub soils
seasonally. PAHs was determined the use of Varian 300 gas
chromatograph interfaced with flame ionization detector. Instruments
and reagents used are of standard and chromatographic grades
respectively. PCC and CA results showed that the classification of
PAHs along pyrolitic and petrogenic organics used in source
signature is about the predominance PAHs in environmental matrix.
Therefore, the distribution of PAHs in the studied stations revealed
the presence of trace quantities of the vast majority of the sixteen
PAHs, which may ultimately inhabit the actual source signature
authentication. Therefore, factors to be considered when evaluating
possible sources of PAHs could be; type and extent of bacterial
metabolism, transformation products/substrates, and environmental
factors such as salinity, pH, oxygen concentration, nutrients, light
intensity, temperature, co-substrates, and environmental medium are
hereby recommended as factors to be considered when evaluating
possible sources of PAHs.
Abstract: Non-linear dynamic time history analysis is
considered as the most advanced and comprehensive analytical
method for evaluating the seismic response and performance of
multi-degree-of-freedom building structures under the influence of
earthquake ground motions. However, effective and accurate
application of the method requires the implementation of advanced
hysteretic constitutive models of the various structural components
including masonry infill panels. Sophisticated computational research
tools that incorporate realistic hysteresis models for non-linear
dynamic time-history analysis are not popular among the professional
engineers as they are not only difficult to access but also complex and
time-consuming to use. In addition, commercial computer programs
for structural analysis and design that are acceptable to practicing
engineers do not generally integrate advanced hysteretic models
which can accurately simulate the hysteresis behavior of structural
elements with a realistic representation of strength degradation,
stiffness deterioration, energy dissipation and ‘pinching’ under cyclic
load reversals in the inelastic range of behavior. In this scenario,
push-over or non-linear static analysis methods have gained
significant popularity, as they can be employed to assess the seismic
performance of building structures while avoiding the complexities
and difficulties associated with non-linear dynamic time-history
analysis. “Push-over” or non-linear static analysis offers a practical
and efficient alternative to non-linear dynamic time-history analysis
for rationally evaluating the seismic demands. The present paper is
based on the analytical investigation of the effect of distribution of
masonry infill panels over the elevation of planar masonry infilled
reinforced concrete [R/C] frames on the seismic demands using the
capacity spectrum procedures implementing nonlinear static analysis
[pushover analysis] in conjunction with the response spectrum
concept. An important objective of the present study is to numerically
evaluate the adequacy of the capacity spectrum method using
pushover analysis for performance based design of masonry infilled
R/C frames for near-field earthquake ground motions.
Abstract: The article includes the results and conclusions from
empirical researches that had been done. The research focuses on the
impact of investments made in small and medium-sized enterprises
financed from EU funds on the competitiveness of these companies.
The researches includes financial results in sales revenue and net
income, expenses, and many other new products/services on offer,
higher quality products and services, more modern methods of
production, innovation in management processes, increase in the
number of customers, increase in market share, increase in
profitability of production and provision of services. The main
conclusions are that, companies with direct investments under this
measure shall apply the modern methods of production. The
consequence of this is to increase the quality of our products and
services. Furthermore, both small and medium-sized enterprises have
introduced new products and services. Investments were carried out,
thus enabling better work organization in enterprises. Entrepreneurs
would guarantee higher quality of service, which would result in
better relationships with their customers, what is more, noting the rise
in number of clients. More than half of the companies indicated that
the investments contributed to the increase in market share. Same
thing as for market reach and brand recognition of particular
company. An interesting finding is that, investments in small
enterprises were more effective than medium-sized enterprises.
Abstract: The importance of agribusiness development is
proved in accordance with the trends in the agricultural sector of
Georgia. Agribusiness environment and the consequences of the
agricultural reforms are evaluated. The factors hindering the
development of agribusiness are revealed and the ways for
overcoming these problems are suggested. SWOT analysis is done in
order to identify the needs of agribusiness. The needs of agribusiness
development in Georgia are evaluated by priorities: prevention of
diseases and reduction of the harm caused by these diseases,
accessibility of long-term agricultural loans with low interest rates,
improving qualification of farmers, the level of education and usage
of modern technologies, changes in legislation, accessibility to high
quality agricultural machinery, and the development of infrastructure.
Based on the outcomes of the research, agribusiness development
strategies in Georgia are suggested and appropriate priorities of
economic policy are determined. Conclusions are made and based on
these conclusions, some recommendations are suggested.
Abstract: Wireless Sensor Networks (WSNs), which sense
environmental data with battery-powered nodes, require multi-hop
communication. This power-demanding task adds an extra workload
that is unfairly distributed across the network. As a result, nodes run
out of battery at different times: this requires an impractical
individual node maintenance scheme. Therefore we investigate a new
Cooperative Sensing approach that extends the WSN operational life
and allows a more practical network maintenance scheme (where all
nodes deplete their batteries almost at the same time). We propose a
novel cooperative algorithm that derives a piecewise representation
of the sensed signal while controlling approximation accuracy.
Simulations show that our algorithm increases WSN operational life
and spreads communication workload evenly. Results convey a
counterintuitive conclusion: distributing workload fairly amongst
nodes may not decrease the network power consumption and yet
extend the WSN operational life. This is achieved as our cooperative
approach decreases the workload of the most burdened cluster in the
network.
Abstract: NiFe2O4 (nickel ferrite), ZnFe2O4 (zinc ferrite) and
Ni0.5Zn0.5Fe2O4 (nickel-zinc ferrite) were prepared by
mechanochemical route in a planetary ball mill starting from mixture
of the appropriate quantities of the Ni(OH)2/Fe(OH)3,
Zn(OH)2/Fe(OH)3 and Ni(OH)2/Zn(OH)2/Fe(OH)3 hydroxide
powders. In order to monitor the progress of chemical reaction and
confirm phase formation, powder samples obtained after 25 h, 18 h
and 10 h of milling were characterized by X-ray diffraction (XRD),
transmission electron microscopy (TEM), IR, Raman and Mössbauer
spectroscopy. It is shown that the soft mechanochemical method, i.e.
mechanochemical activation of hydroxides, produces high quality
single phase ferrite samples in much more efficient way. From the IR
spectroscopy of single phase samples it is obvious that energy of
modes depends on the ratio of cations. It is obvious that all samples
have more than 5 Raman active modes predicted by group theory in
the normal spinel structure. Deconvolution of measured spectra
allows one to conclude that all complex bands in the spectra are made
of individual peaks with the intensities that vary from spectrum to
spectrum. The deconvolution of Raman spectra allows to separate
contributions of different cations to a particular type of vibration and
to estimate the degree of inversion.
Abstract: This research tested the performance of alternative
warehouse designs concerning the picking process. The chosen
performance measures were Travel Distance and Total Fulfilment
Time. An explanatory case study was built up around a model
implemented with SIMUL8. Hypotheses were set by selecting
outcomes from the literature survey matching popular empirical
findings. 17.4% reductions were found for Total Fulfilment Time and
Resource Utilisation. The latter was then used as a proxy for
operational efficiency. Literal replication of theoretical data-patterns
was considered as an internal validity sign. Assessing the estimated
changes benefits ahead of implementation was found to be a
contribution to practice.
Abstract: In present study, a large deposit of oolitic iron ore of
Late Carboniferous-Permotriassic-Lower Jurassic age was discovered
in Wadi Halfa and Argein areas, North Sudan. It seems that the iron
ore mineralization exists in the west and east bank of the River Nile
of the study area that are found on the Egyptian-Sudanese border.
The Carboniferous-Lower Jurassic age strata were covered by 67
sections and each section has been examined and carefully described.
The iron-ore in Wadi Halfa occurs as oolitic ironstone and contained
two horizons: (A) horizon and (B) horizon. Only horizon (A) was
observed in southern Argein area. The texture of the ore is variable
depending on the volume of the component. In thin sections, the
average of the ooids was ranged between 90%-80%. The matrix
varies between 10%-20% by volume and detritus quartz in other
component my reach up to 30% by volume in sandy massive ore.
Ooids size ranges from 0.2mm-1.00 mm on average in very coarse
ooids may attend up to 1 mm in size. The matrix around the ooids is
dominated by iron hydroxide, carbonate, fine, and amorphous silica.
The probable ore reserve estimate of 1.234 billion at a head grade of
41.29% Fe for the Wadi Halfa Oolitic Ironstone Formation. The iron
ore shows higher content of phosphorus ranges from 6.15% to 0.16%,
with mean 1.45%. The new technology Hatch–Ironstone Chloride
Segregation (HICS) can be used to produce commercial-quality of
iron and reduce phosphorus and silica to acceptable levels for steel
industry. The presence of infrastructures in addition to the presence
of massive quantities of iron ore would make exploitation
economically.