Abstract: The substantial similarity of fatigue mechanism in a
new test rig for rolling contact fatigue (RCF) has been investigated. A
new reduced-scale test rig is designed to perform controlled RCF
tests in wheel-rail materials. The fatigue mechanism of the rig is
evaluated in this study using a combined finite element-fatigue
prediction approach. The influences of loading conditions on fatigue
crack initiation have been studied. Furthermore, the effects of some
artificial defects (squat-shape) on fatigue lives are examined. To
simulate the vehicle-track interaction by means of the test rig, a threedimensional
finite element (FE) model is built up. The nonlinear
material behaviour of the rail steel is modelled in the contact
interface. The results of FE simulations are combined with the critical
plane concept to determine the material points with the greatest
possibility of fatigue failure. Based on the stress-strain responses, by
employing of previously postulated criteria for fatigue crack initiation
(plastic shakedown and ratchetting), fatigue life analysis is carried
out. The results are reported for various loading conditions and
different defect sizes. Afterward, the cyclic mechanism of the test rig
is evaluated from the operational viewpoint. The results of fatigue
life predictions are compared with the expected number of cycles of
the test rig by its cyclic nature. Finally, the estimative duration of the
experiments until fatigue crack initiation is roughly determined.
Abstract: A new small–scale test rig developed for rolling
contact fatigue (RCF) investigations in wheel–rail material. This
paper presents the scaling strategy of the rig based on dimensional
analysis and mechanical modelling. The new experimental rig is
indeed a spinning frame structure with multiple wheel components
over a fixed rail-track ring, capable of simulating continuous wheelrail
contact in a laboratory scale. This paper describes the
dimensional design of the rig, to derive its overall scaling strategy
and to determine the key elements’ specifications. Finite element
(FE) modelling is used to simulate the mechanical behavior of the rig
with two sample scale factors of 1/5 and 1/7. The results of FE
models are compared with the actual railway system to observe the
effectiveness of the chosen scales. The mechanical properties of the
components and variables of the system are finally determined
through the design process.
Abstract: This study is purposed to develop an efficient fault
detection method for Global Navigation Satellite Systems (GNSS)
applications based on adaptive noise covariance estimation. Due to the
dependence on radio frequency signals, GNSS measurements are
dominated by systematic errors in receiver’s operating environment.
In the proposed method, the pseudorange and carrier-phase
measurement noise covariances are obtained at time propagations and
measurement updates in process of Carrier-Smoothed Code (CSC)
filtering, respectively. The test statistics for fault detection are
generated by the estimated measurement noise covariances. To
evaluate the fault detection capability, intentional faults were added to
the filed-collected measurements. The experiment result shows that
the proposed method is efficient in detecting unhealthy measurements
and improves GNSS positioning accuracy against fault occurrences.
Abstract: A single-phase closed thermosyphon has been
fabricated and experimented to utilize solar energy for water heating.
The working fluid of the closed thermosyphon is heated at the flatplate
collector and the hot water goes to the water tank due to density
gradient caused by temperature differences. This experimental work
was done using insulated water tank and insulated connecting pipe
between the tank and the flat-plate collector. From the collected data,
performance parameters such as instantaneous collector efficiency
and heat removal factor are calculated. In this study, the effects of
glazing were also observed. The water temperature rise and the
maximum instantaneous efficiency obtained from this experiment
with glazing using insulated water tank and insulated connecting pipe
are 17°C in a period of 5 hours and 60% respectively. Whereas the
water temperature rise and the maximum instantaneous efficiency
obtained from this experiment with glazing using non-insulated water
tank and non-insulated connecting pipe are 14°C in a period of 5
hours and 39% respectively.
Abstract: One of the biggest challenges facing Theological/
Religious Education in Nigeria is access to quality learning materials.
For instance at the Trinity (Union) Theological College, Umuahia, it
was difficult for lecturers to access suitable and qualitative materials
for instruction especially the ones that would suit the African context
and stimulate a deep rooted interest among the students. Some
textbooks written by foreign authors were readily available in the
School Library, but were lacking in the College bookshops for
students to own copies. Even when the College was able to order
some of the books from abroad, it did not usher in the needed
enthusiasm expected from the students because they were either very
expensive or very difficult to understand during private studies. So it
became necessary to develop contextual materials which were
affordable and understandable, though with little success. The
National Open University of Nigeria (NOUN)’s innovation in the
development and sharing of learning resources through its Open
Courseware is a welcome development and of great assistance to
students. Apart from NOUN students who could easily access the
materials, many others from various theological/religious institutes
across the nation have benefited immensely. So, the thesis of this
paper is that the promotion of open educational resources in
theological/religious education in Nigeria would facilitate a better
informed/equipped religious leadership, which would in turn impact
its adherents for a healthier society and national development.
Adopting a narrative and historical approach within the context of
Nigeria’s educational system, the paper discusses: educational
traditions in Nigeria; challenges facing theological/religious
education in Nigeria; and benefits of open educational resources. The
study goes further to making recommendations on how OER could
positively influence theological/religious education in Nigeria. It is
expected that theologians, religious educators, and ODL practitioners
would find this work very useful.
Abstract: Aluminium and its alloys have excellent corrosion
resistant properties, ease of fabrication and high specific strength to
weight ratio. In this investigation an attempt has been made to study
the effect of different post weld heat treatment methods on the
mechanical and metallurgical properties of TIG welded joints of the
commercial aluminium alloy. Three different methods of post weld
heat treatments are solution heat treatment, artificial ageing and
combination of solution heat treatment and artificial aging are given
to TIG welded aluminium joints. Mechanical and metallurgical
properties of As welded joints of the aluminium alloys and post weld
heat treated joints of the aluminium alloys were examined.
Abstract: In structures, stress concentration is a factor of fatigue
fracture. Basically, the stress concentration is a phenomenon that
should be avoided. However, it is difficult to avoid the stress
concentration. Therefore, relaxation of the stress concentration is
important. The stress concentration arises from notches and circular
holes. There is a relaxation method that a composite patch covers a
notch and a circular hole. This relaxation method is used to repair
aerial wings, but it is not systematized. Composites are more
expensive than single materials. Accordingly, we propose the
relaxation method that a single material patch covers a notch and a
circular hole, and aim to systematize this relaxation method.
We performed FEA (Finite Element Analysis) about an object by
using a three-dimensional FEA model. The object was that a patch
adheres to a plate with a circular hole. And, a uniaxial tensile load acts
on the patched plate with a circular hole. In the three-dimensional FEA
model, it is not easy to model the adhesion layer. Basically, the yield
stress of the adhesive is smaller than that of adherents. Accordingly,
the adhesion layer gets to plastic deformation earlier than the adherents
under the yield load of adherents. Therefore, we propose the
three-dimensional FEA model which is applied a nonlinear elastic
region to the adhesion layer. The nonlinear elastic region was
calculated by a bilinear approximation. We compared the analysis
results with the tensile test results to confirm whether the analysis
model has usefulness. As a result, the analysis results agreed with the
tensile test results. And, we confirmed that the analysis model has
usefulness.
As a result that the three-dimensional FEA model was used to the
analysis, it was confirmed that an out-of-plane deformation occurred
to the patched plate with a circular hole. The out-of-plane deformation
causes stress increase of the patched plate with a circular hole.
Therefore, we investigated that the out-of-plane deformation affects
relaxation of the stress concentration in the plate with a circular hole
on this relaxation method. As a result, it was confirmed that the
out-of-plane deformation inhibits relaxation of the stress concentration
on the plate with a circular hole.
Abstract: Supermarkets are the most electricity-intensive type of
commercial buildings. The unsuitable indoor environment of a
supermarket provided by abnormal HVAC operations incurs waste
energy consumption in refrigeration systems. This current study
briefly describes significantly solid backgrounds and proposes easyto-
use analysis terminology for investigating the impact of HVAC
operations on refrigeration power consumption using the field-test
data obtained from building automation system (BAS). With solid
backgrounds and prior knowledge, expected energy interactions
between HVAC and refrigeration systems are proposed through
Pearson’s correlation analysis (R value) by considering correlations
between equipment power consumption and dominantly independent
variables (driving force conditions).The R value can be conveniently
utilized to evaluate how strong relations between equipment
operations and driving force parameters are. The calculated R values
obtained from field data are compared to expected ranges of R values
computed by energy interaction methodology. The comparisons can
separate the operational conditions of equipment into faulty and
normal conditions. This analysis can simply investigate the condition
of equipment operations or building sensors because equipment could
be abnormal conditions due to routine operations or faulty
commissioning processes in field tests. With systematically solid and
easy-to-use backgrounds of interactions provided in the present
article, the procedures can be utilized as a tool to evaluate the proper
commissioning and routine operations of HVAC and refrigeration
systems to detect simple faults (e.g. sensors and driving force
environment of refrigeration systems and equipment set-point) and
optimize power consumption in supermarket buildings. Moreover,
the analysis will be used to further study the FDD research for
supermarkets in future.
Abstract: Molluca Collision Zone is located at the junction of
the Eurasian, Australian, Pacific and the Philippines plates. Between
the Sangihe arc, west of the collision zone, and to the east of
Halmahera arc is active collision and convex toward the Molluca Sea.
This research will analyze the behavior of earthquake occurrence in
Molluca Collision Zone related to the distributions of an earthquake
in each partition regions, determining the type of distribution of a
occurrence earthquake of partition regions, and the mean occurence
of earthquakes each partition regions, and the correlation between the
partitions region. We calculate number of earthquakes using partition
method and its behavioral using conventional statistical methods. In
this research, we used data of shallow earthquakes type and its
magnitudes ≥4 SR (period 1964-2013). From the results, we can
classify partitioned regions based on the correlation into two classes:
strong and very strong. This classification can be used for early
warning system in disaster management.
Abstract: Kigelia africana (Lam.) Benth. (Bignoniaceae) is a
reputed traditional remedy for various human ailments such as skin
diseases, microbial infections, melanoma, stomach troubles,
metabolic disorders, malaria and general pains. In spite of the fruit
being widely used for purposes related to its antibacterial and
antifungal properties, the chemical constituents associated with the
activity have not been fully identified. To elucidate the active
principles, we evaluated the antimicrobial activity of fruit extracts
and purified fractions against Staphylococcus aureus, Enterococcus
faecalis, Moraxella catarrhalis, Escherichia coli, Candida albicans
and Candida tropicalis. Shade-dried fruits were powdered and
extracted with hydroalcoholic (1:1) mixture by soaking at room
temperature for 72 h. The crude extract was further fractionated by
column chromatography, with successive elution using hexane,
dichloromethane, ethyl acetate, acetone and methanol. The
dichloromethane and ethyl acetate fractions were combined and
subjected to column chromatography to furnish a wax and oil from
the eluates of 20% and 40% ethyl acetate in hexane, respectively. The
GC-MS and GC×GC-MS results revealed that linoleic acid, linolenic
acid, palmitic acid, arachidic acid and stearic acid were the major
constituents in both oil and wax. The crude hydroalcoholic extract
exhibited the strongest activity with MICs of 0.125-0.5 mg/mL,
followed by the ethyl acetate (MICs = 0.125-1.0 mg/mL),
dichloromethane (MICs = 0.250-2.0 mg/mL), hexane (MICs = 0.25-
2.0 mg/mL), acetone (MICs = 0.5-2.0 mg/mL) and methanol (MICs =
1.0-2.0 mg/mL), whereas the wax (MICs = 2.0-4.0 mg/mL) and oil
(MICs = 4.0-8.0 mg/mL) showed poor activity. The study concludes
that synergistic interactions of chemical constituents could be
responsible for the antimicrobial activity of K. africana fruits, which
needs a more holistic approach to understand the mechanism of its
antimicrobial activity.
Abstract: The reachable set bounding estimation for distributed
delay systems with disturbances is a new problem. In this paper,we
consider this problem subject to not only time varying delay and
polytopic uncertainties but also distributed delay systems which is
not studied fully untill now. we can obtain improved non-ellipsoidal
reachable set estimation for neural networks with time-varying delay
by the maximal Lyapunov-Krasovskii fuctional which is constructed
as the pointwise maximum of a family of Lyapunov-Krasovskii
fuctionals corresponds to vertexes of uncertain polytope.On the other
hand,matrix inequalities containing only one scalar and Matlabs
LMI Toolbox is utilized to give a non-ellipsoidal description of the
reachable set.finally,numerical examples are given to illustrate the
existing results.
Abstract: In new energy development, wind power has boomed.
It is due to the proliferation of wind parks and their operation in
supplying the national electric grid with low cost and clean resources.
Hence, there is an increased need to establish a proactive
maintenance for wind turbine machines based on remote control and
monitoring. That is necessary with a real-time wireless connection in
offshore or inaccessible locations while the wired method has many
flaws. The objective of this strategy is to prolong wind turbine
lifetime and to increase productivity. The hardware of a remote
control and monitoring system for wind turbine parks is designed. It
takes advantage of GPRS or Wi-Max wireless module to collect data
measurements from different wind machine sensors through IP based
multi-hop communication. Computer simulations with Proteus ISIS
and OPNET software tools have been conducted to evaluate the
performance of the studied system. Study findings show that the
designed device is suitable for application in a wind park.
Abstract: The psychological impact of peer influence on its
individual group members, can make them resist HIV/AIDS
counselling and testing. This study investigated the correlate of peer
influence and resistance to HIV/AIDS counselling and testing among
students in tertiary institutions in Kano state, Nigeria. To achieve
this, three null hypotheses were postulated and tested. Cross-
Sectional Survey Design was employed in which 1512 sample was
selected from a student population of 104,841.Simple Random
Sampling was used in the selection. A self-developed 20-item scale
called Peer Influence and Psychological Resistance Inventory
(PIPRI) was used for data collection. Pearson Product Moment
Correlation (PPMCC) via test-retest method was applied to estimate a
reliability coefficient of 0.86 for the scale. Data obtained was
analyzed using t-test and PPMCC at 0.05 level of confidence. Results
reveal 26.3% (397) of the respondents being influenced by their peer
group, while 39.8% showed resistance. Also, the t-tests and PPMCC
statistics were greater than their respective critical values. This shows
that there was a significant gender difference in peer influence and a
difference between peer influence and resistance to HIV/AIDS
counselling and testing. However, a positive relationship between
peer influence and resistance to HIV/AIDS counselling and testing
was shown. A major recommendation offered suggests the use of
reinforcement and social support for positive attitudes and
maintenance of safe behaviour among students who patronize
HIV/AIDS counselling.
Abstract: Cement-based grouts has been used successfully to
repair cracks in many concrete structures such as bridges, tunnels,
buildings and to consolidate soils or rock foundations. In the present
study the rheological characterization of cement grout with
water/binder ratio (W/B) is fixed at 0.5. The effect of the replacement
of cement by bentonite (2 to 10% wt) in presence of superplasticizer
(0.5% wt) was investigated. Several rheological tests were carried out
by using controlled-stress rheometer equipped with vane geometry in
temperature of 20°C. To highlight the influence of bentonite and
superplasticizer on the rheological behavior of grout cement, various
flow tests in a range of shear rate from 0 to 200 s-1 were observed.
Cement grout showed a non-Newtonian viscosity behavior at all
concentrations of bentonite. Three parameter model Herschel-
Bulkley was chosen for fitting of experimental data. Based on the
values of correlation coefficients of the estimated parameters, The
Herschel-Bulkley law model well described the rheological behavior
of the grouts. Test results showed that the dosage of bentonite
increases the viscosity and yield stress of the system and introduces
more thixotropy. While the addition of both bentonite and
superplasticizer with cement grout improve significantly the fluidity
and reduced the yield stress due to the action of dispersion of SP.
Abstract: Nations are still finding it quite difficult to win mega
sport competitions despite the major contribution of sport to society
in terms of social and economic development, personal health, and in
education. Even though the world of sports has been transformed into
a huge global economy, it is important to note that the first step of
sport is usually its introduction to children at school through physical
education or PE. In other words, nations who do not win mega sport
competitions also suffer from a weak and neglected PE system. This
problem of the neglect of PE systems is the main motivation of this
research aimed at examining the factors affecting the perceived
awareness of physical education teachers on the ICTs that are
adoptable for the teaching and learning of physical education. Two
types of research objectives will materialize this aim: relevant
theories will be identified in relation to the analysis of the perceived
ICT awareness of PE teachers and subsequent models will be
compiled and designed from existing literature; the empirical testing
of such theories and models will also be achieved through the survey
of PE teachers from the Camperdown magisterial district of the
KwaZulu-Natal province of South Africa. The main hypothesis at the
heart of this study is the relationship between the demographics of PE
teachers, their behavior both as individuals and as social entities, and
their perceived awareness of the ICTs that are adoptable for PE, as
postulated by existing literature; except that this study categorizes
human behavior under performance expectancy, computer attitude,
and social influence. This hypothesis was partially confirmed by the
survey conducted by this research in the sense that performance
expectancy and teachers’ age, gender, computer usage, and class size
were found to be the only factors affecting their awareness of ICTs
for physical education.
Abstract: In order to study the effect of drought stress on grain
yield, yield components and associated traits of durum wheat
cultivars, an experiment was done as split plot arrangement using
randomized complete block design with three replications in Ilam
province, Iran in 2009-2010 cropping season. Different levels of
irrigation (Full irrigation, drought stress at stem elongation,
Flowering and grain formation stages) were considered as a main plot
and three durum wheat cultivars (Yavaros, Seimareh and Karkheh)
were assigned as a sub plot. The results showed that drought stress
was significant on grain yield, spike.m-2, grain. Spike-1, 1000-grain
weight, biological yield, harvest index and protein content. Drought
stress at all stages caused a loss in grain yield and its components.
Full irrigation had the highest grain yield and yield components.
Drought stress at stem elongation, flowering and grain formation
stages caused a reduction in spike.m-2, grain.spike-1 and 1000-grain
weight, respectively. Protein content was significantly affected by
drought stress. The highest protein content was obtained from
drought stress at grain formation stage. Cultivars had an influence on
grain yield and yield components. Yavaros and Seimareh cultivars
had the highest and lowest grain yield, respectively. Interaction effect
between drought stress and cultivar had a significant effect on grain
and yield components. Full irrigation and Yavaros cultivar had the
highest grain yield and drought stress at grain formation stage and
Seimareh cultivar had the lowest grain yield, respectively.
Abstract: The development of the agricultural sector in Ghana
has been reliant on the use of irrigation systems to ensure food
security. However, the manual operation of these systems has not
facilitated their maximum efficiency due to human limitations.
This paper seeks to address this problem by designing and
implementing an efficient, cost effective automated system which
monitors and controls the water flow of irrigation through
communication with an authorized operator via text messages. The
automatic control component of the system is timer based with an
Atmega32 microcontroller and a real time clock from the SM5100B
cellular module. For monitoring purposes, the system sends periodic
notification of the system on the performance of duty via SMS to the
authorized person(s). Moreover, the GSM based Irrigation
Monitoring and Control System saves time and labour and reduces
cost of operating irrigation systems by saving electricity usage and
conserving water.
Field tests conducted have proven its operational efficiency and
ease of assessment of farm irrigation equipment due to its costeffectiveness
and data logging capabilities.
Abstract: Renewable energy is derived from natural processes
that are replenished constantly. Included in the definition is
electricity and heat generated from solar, wind, ocean, hydropower,
biomass, geothermal resources, and bio-fuels and hydrogen derived
from renewable resources. Each of these sources has unique
characteristics which influence how and where they are used. This
paper presents the modeling the simulation of solar and hydro hybrid
energy sources in MATLAB/SIMULINK environment. It simulates
all quantities of Hybrid Electrical Power system (HEPS) such as AC
output current of the inverter that injected to the load/grid, load
current, grid current. It also simulates power output from PV and
Hydraulic Turbine Generator (HTG), power delivered to or from grid
and finally power factor of the inverter for PV, HTG and grid. The
proposed circuit uses instantaneous p-q (real-imaginary) power
theory.
Abstract: In this paper a scheme is proposed for generating
a programmable current reference which can be implemented
in the CMOS technology. The current can be varied over a
wide range by changing an external voltage applied to one
of the control gates of FGMOS (Floating Gate MOSFET).
For a range of supply voltages and temperature, CMOS
current reference is found to be dependent, this dependence
is compensated by subtracting two current outputs with the
same dependencies on the supply voltage and temperature.
The system performance is found to improve with the
use of FGMOS. Mathematical analysis of the proposed
circuit is done to establish supply voltage and temperature
independence. Simulation and performance evaluation of the
proposed current reference circuit is done using TANNER
EDA Tools. The current reference shows the supply and
temperature dependencies of 520 ppm/V and 312 ppm/oC,
respectively. The proposed current reference can operate down
to 0.9 V supply.
Abstract: In this paper, numerical solution of system of
Fredholm and Volterra integral equations by means of the Spline
collocation method is considered. This approximation reduces the
system of integral equations to an explicit system of algebraic
equations. The solution is collocated by cubic B-spline and the
integrand is approximated by the Newton-Cotes formula. The error
analysis of proposed numerical method is studied theoretically. The
results are compared with the results obtained by other methods to
illustrate the accuracy and the implementation of our method.