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: One of the most important tasks in the risk
management is the correct determination of probability of default
(PD) of particular financial subjects. In this paper a possibility of
determination of financial institution’s PD according to the creditscoring
models is discussed. The paper is divided into the two parts.
The first part is devoted to the estimation of the three different
models (based on the linear discriminant analysis, logit regression
and probit regression) from the sample of almost three hundred US
commercial banks. Afterwards these models are compared and
verified on the control sample with the view to choose the best one.
The second part of the paper is aimed at the application of the chosen
model on the portfolio of three key Czech banks to estimate their
present financial stability. However, it is not less important to be able
to estimate the evolution of PD in the future. For this reason, the
second task in this paper is to estimate the probability distribution of
the future PD for the Czech banks. So, there are sampled randomly
the values of particular indicators and estimated the PDs’ distribution,
while it’s assumed that the indicators are distributed according to the
multidimensional subordinated Lévy model (Variance Gamma model
and Normal Inverse Gaussian model, particularly). Although the
obtained results show that all banks are relatively healthy, there is
still high chance that “a financial crisis” will occur, at least in terms
of probability. This is indicated by estimation of the various quantiles
in the estimated distributions. Finally, it should be noted that the
applicability of the estimated model (with respect to the used data) is
limited to the recessionary phase of the financial market.
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: This paper presents the electromagnetic interference
(EMI) shielding effectiveness of rice husk and carbon nanotubes
(RHCNTs) composites in the X-band region (8.2-12.4 GHz). The
difference weight ratio of carbon nanotubes (CNTs) were mix with
the rice husk. The rectangular waveguide technique was used to
measure the complex permittivity of the RHCNTs composites
materials. The complex permittivity is represented in terms of both
the real and imaginary parts of permittivity in X-band frequency. The
conductivity of RHCNTs shows increasing when the ratio of CNTs
mixture increases. The composites materials were simulated using
Computer Simulation Technology (CST) Microwave Studio
simulation software. The shielding effectiveness of RHCNTs and
pure rice husk was compared. The highest EMI SE of 30 dB is
obtained for RHCNTs composites of 10 wt % CNTs with 10mm
thickness.
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: 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: Due to the large amount of information in the World
Wide Web (WWW, web) and the lengthy and usually linearly
ordered result lists of web search engines that do not indicate
semantic relationships between their entries, the search for topically
similar and related documents can become a tedious task. Especially,
the process of formulating queries with proper terms representing
specific information needs requires much effort from the user. This
problem gets even bigger when the user's knowledge on a subject and
its technical terms is not sufficient enough to do so. This article
presents the new and interactive search application DocAnalyser that
addresses this problem by enabling users to find similar and related
web documents based on automatic query formulation and state-ofthe-
art search word extraction. Additionally, this tool can be used to
track topics across semantically connected web documents.
Abstract: Recently, there have been a lot of earthquakes in Japan.
It is necessary to promote seismic isolation devices for buildings. The
devices have been hardly diffused in attached houses, because the
devices are very expensive. We should develop a low-cost seismic
isolation device for detached houses. We suggested a new seismic
isolation device which uses a two-layer circular tube as a unit. If
hysteresis is produced in the two-layer circular tube under lateral
compression load, we think that the two-layer circular tube can have
energy absorbing capacity. It is necessary to contact the outer layer
and the inner layer to produce hysteresis. We have previously reported
how the inner layer comes in contact with the outer layer from a
perspective of analysis used mechanics of materials. We have clarified
that the inner layer comes in contact with the outer layer under a lateral
compression load. In this paper, we explored contact area between the
outer layer and the inner layer under a lateral compression load by
using FEA. We think that changing the inner layer’s thickness is
effective in increase the contact area. In order to change the inner
layer’s thickness, we changed the shape of the inner layer. As a result,
the contact area changes depending on the inner layer’s thickness.
Additionally, we experimented to check whether hysteresis occurs in
fact. As a consequence, we can reveal hysteresis in the two-layer
circular tube under the condition.
Abstract: This work presents a Computational Fluid Dynamics
(CFD) simulation of a butterfly valve used to control the flow of
combustible gas mixture in an industrial process setting.The work
uses CFD simulation to analyze the flow characteristics in the
vicinity of the valve, including the pressure distributions and
Frequency spectrum of the pressure pulsations downstream the valves
and the vortex shedding allow predicting the torque fluctuations
acting on the valve shaft and the possibility of generating mechanical
vibration and resonance.These fluctuations are due to aerodynamic
torque resulting from fluid turbulence and vortex shedding in the
valve vicinity.
The valve analyzed is located in a pipeline between two opposing
90o elbows, which exposes the valve and the surrounding structure to
the turbulence generated upstream and downstream the elbows at
either end of the pipe.CFD simulations show that the best location for
the valve from a vibration point of view is in the middle of the pipe
joining the elbows.
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: 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: This paper presents reliability indices evaluation of the
rotor core magnetization of the induction motor operated as a self
excited induction generator by using probability distribution approach
and Monte Carlo simulation. Parallel capacitors with calculated
minimum capacitive value across the terminals of the induction motor
operated as a SEIG with unregulated shaft speed have been connected
during the experimental study. A three phase, 4 poles, 50Hz, 5.5 hp,
12.3A, 230V induction motor coupled with DC Shunt Motor was
tested in the electrical machine laboratory with variable reactive loads.
Based on this experimental study, it is possible to choose a reliable
induction machines operated as a SEIG for unregulated renewable
energy application in remote area or where grid is not available.
Failure density function, cumulative failure distribution function,
survivor function, hazard model, probability of success and
probability of failure for reliability evaluation of the three phase
induction motor operating as a SEIG have been presented graphically
in this paper.
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: 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: With advances in solid-state power electronic devices
and microprocessors, various pulse-width-modulation (PWM)
techniques have been developed for industrial applications. This
paper presents the comparison of two different PWM techniques, the
sinusoidal PWM (SPWM) technique and the space-vector PWM
(SVPWM) technique applied to two level VSI for micro grid
applications. These two methods are compared by discussing their
ease of implementation and by analyzing the output harmonic spectra
of various output voltages (line-to-neutral voltages, and line-to-line
voltages) and their total harmonic distortion (THD). The SVPWM
technique in the under-modulation region can increase the
fundamental output voltage by 15.5% over the SPWM technique.