Abstract: The power converter that feeds high-frequency, highvoltage
transformers must be carefully designed due to parasitic
components, mainly the secondary winding capacitance and the
leakage inductance, that introduces resonances in relatively lowfrequency
range, next to the switching frequency. This paper
considers applications in which the load (resistive) has an
unpredictable behavior, changing from open to short-circuit condition
faster than the output voltage control loop could react. In this context,
to avoid overvoltage and over current situations, that could damage
the converter, the transformer or the load, it is necessary to find an
operation point that assure the desired output voltage in spite of the
load condition. This can done adjusting the frequency response of the
transformer adding an external inductance, together with selecting the
switching frequency to get stable output voltage independently of the
load.
Abstract: Quality control helps industries in improvements of its
product quality and productivity. Statistical Process Control (SPC) is
one of the tools to control the quality of products that turning practice
in bringing a department of industrial engineering process under
control. In this research, the process control of a turning
manufactured at workshops machines. The varying measurements
have been recorded for a number of samples of a rice polished
cylinder obtained from a number of trials with the turning practice.
SPC technique has been adopted by the process is finally brought
under control and process capability is improved.
Abstract: Essential oils are expensive phytochemicals produced
and extracted from specific species belonging to particular families in
the plant kingdom. In the United Arab Emirates country (UAE), is
located in the arid region of the world, nine species, from the
Lamiaceae family, having the capability to produce therapeutic grade
essential oils. These species include; Mentha spicata, Ocimum
forskolei, Salvia macrosiphon, Salvia aegyptiaca, Salvia macilenta,
Salvia spinosa, Teucrium polium, Teucrium stocksianum and Zataria
multiflora. Although, such potential species are indigenous to the
UAE, however, there are almost no studies available to investigate
the chemical composition and the quality of the extracted essential
oils under the UAE climatological conditions. Therefore, great
attention has to be given to such valuable natural resources, through
conducting highly supported research projects, tailored to the UAE
conditions, and investigating different extraction techniques,
including the application of the latest available technologies, such as
superficial fluid CO2. This is crucially needed; in order to accomplish
the greatest possibilities in the medicinal field, specifically in the
discovery of new therapeutic chemotypes, as well as, to achieve the
sustainability of this natural resource in the country.
Abstract: Taro Scarab beetles (Papuana uninodis, Coleoptera:
Scarabaeidae) inflict severe damage on important root crops and
plants such as Taro or Cocoyam, yam, sweet potatoes, oil palm and
coffee tea plants across Africa and Asia resulting in economic
hardship and starvation in some nations. Scoliid wasps and
Metarhizium anisopliae fungus - bio-control agents; are shown to be
able to control the population of Scarab beetle adults and larvae using
a newly created simulation model based on non-linear ordinary
differential equations that track the populations of the beetle life
cycle stages: egg, larva, pupa, adult and the population of the scoliid
parasitoid wasps, which attack beetle larvae. In spite of the challenge
driven by the longevity of the scarab beetles, the combined effect of
the larval wasps and the fungal bio-control agent is able to control
and drive down the population of both the adult and the beetle eggs
below the environmental carrying capacity within an interval of 120
days, offering the long term prospect of a stable and eco-friendly
environment; where the population of scarab beetles is: regulated by
parasitoid wasps and beneficial soil saprophytes.
Abstract: The presence of endocrine-disrupting compounds,
such as bisphenol A (BPA), in the environment can cause serious
health problems. However, there are controversial opinions. This
study investigated the reproductive, metabolic, oxidative and
immunologic-disrupting effects of bisphenol A in male rabbits.
Rabbits were divided into five groups. The first four rabbit groups
were administered oral BPA (1, 10, 50, or 100 mg/kg/day) for ten
weeks. The fifth group was administered corn oil as the vehicle. BPA
significantly decreased serum testosterone, estradiol and the free
androgen index (FAI) and significantly increased sex hormone
binding globulin (SHBG) compared with the placebo group. The
higher doses of BPA showed a significant decrease in follicular
stimulating hormone (FSH) and luteinizing hormone (LH). A
significant increase in blood glucose levels was identified in the BPA
groups. The non-significant difference in insulin levels is a novel
finding. The cumulative testicular toxicity of BPA was clearly
demonstrated by the dose-dependent decrease in absolute testes
weight, primary measures of semen quality and a significant increase
in testicular malonaldehyde (MDA). Moreover, BPA significantly
decreased total antioxidant capacity (TAC) and significantly
increased immunoglobulin G (IgG) at the highest concentration. Our
results suggest that BPA, especially at higher doses, is associated
with many adverse effects on metabolism, oxidative stress, immunity,
sperm quality and markers of androgenic action.
Abstract: Distributed Generation (DG) can help in reducing the
cost of electricity to the costumer, relieve network congestion and
provide environmentally friendly energy close to load centers. Its
capacity is also scalable and it provides voltage support at distribution
level. Hence, DG placement and penetration level is an important
problem for both the utility and DG owner. DG allocation and capacity
determination is a nonlinear optimization problem. The objective
function of this problem is the minimization of the total loss of the
distribution system. Also high levels of penetration of DG are a new
challenge for traditional electric power systems. This paper presents a
new methodology for the optimal placement of DG and penetration
level of DG in distribution system based on General Algebraic
Modeling System (GAMS) and Genetic Algorithm (GA).
Abstract: South Africa has some regions which are susceptible
to moderate seismic activity. A peak ground acceleration of between
0.1g and 0.15g can be expected in the southern parts of the Western
Cape. Unreinforced Masonry (URM) is commonly used as a
construction material for 2 to 5 storey buildings in underprivileged
areas in and around Cape Town. URM is typically regarded as the
material most vulnerable to damage when subjected to earthquake
excitation. In this study, a three-storey URM building was analysed
by applying seven earthquake time-histories, which can be expected
to occur in South Africa using a finite element approach.
Experimental data was used to calibrate the in- and out-of-plane
stiffness of the URM. The results indicated that tensile cracking of
the in-plane piers was the dominant failure mode. It is concluded that
URM buildings of this type are at risk of failure especially if
sufficient ductility is not provided. The results also showed that
connection failure must be investigated further.
Abstract: Columns have traditionally been constructed of
reinforced concrete or structural steel. Much attention was allocated
to estimate the axial capacity of the traditional column sections to the
detriment of other forms of construction. Other forms of column
construction such as Concrete Filled Double Skin Tubes received
little research attention, and almost no attention when subjected to
eccentric loading. This paper investigates the axial capacity of
columns when subjected to eccentric loading. The experimental axial
capacities are compared to other established theoretical formulae on
concentric loading to determine a possible relationship. The study
found a good correlation between the reduction in axial capacity for
different column lengths and hollow section ratios.
Abstract: Preparation of nanoparticles of cerium oxide and
adsorption of bovine serum albumin on them were studied. Particle
size distribution and influence of pH on zeta potential of prepared
CeO2 were determined. Average size of prepared cerium oxide
nanoparticles was 9 nm. The simultaneous measurements of the
bovine serum albumin adsorption and zeta potential determination of
the (adsorption) suspensions were carried out. The adsorption
isotherms were found to be of typical Langmuir type; values of the
bovine serum albumin adsorption capacities were calculated.
Increasing of pH led to decrease of zeta potential and decrease of
adsorption capacity of cerium oxide nanoparticles. The maximum
adsorption capacity was found for strongly acid suspension (am =
118 mg/g). The samples of nanoceria with positive zeta potential
adsorbed more bovine serum albumin on the other hand, the samples
with negative zeta potential showed little or no protein adsorption.
Surface charge or better say zeta potential of CeO2 nanoparticles
plays the key role in adsorption of proteins on such type of materials.
Abstract: Electricity is recognized as fundamental to
industrialization and improving the quality of life of the people.
Harnessing the immense untapped hydropower potential in Tripura
region opens avenues for growth and provides an opportunity to
improve the well-being of the people of the region, while making
substantial contribution to the national economy. Gumti hydro power
plant generates power to mitigate the crisis of power in Tripura,
India. The first unit of hydro power plant (5MW) was commissioned
in June 1976 & another two units of 5 MW was commissioned
simultaneously. But out of 15MW capacity at present only 8MW-
9MW power is produced from Gumti hydro power plant during rainy
season. But during lean season the production reduces to 0.5MW due
to shortage of water. Now, it is essential to implement some
mitigation measures so that the further atrocities can be prevented
and originality will be possible to restore. The decision making
ability of the Analytic Hierarchy Process (AHP) and Concordance
Analysis Techniques (CAT) are utilized to identify the better decision
or solution to the present problem. Some related attributes are
identified by the method of surveying within the experts and the
available reports and literatures. Similar criteria are removed and
ultimately seven relevant ones are identified. All the attributes are
compared with each other and rated accordingly to their importance
over the other with the help of Pair wise Comparison Matrix. In the
present investigation different mitigation measures are identified and
compared to find the best suitable alternative which can solve the
present uncertainties involving the existence of the Gumti Hydro
Power Plant.
Abstract: A novel method to produce a fast high voltage solid
states switch using Insulated Gate Bipolar Transistors (IGBTs) is
presented for discharge-pumped gas lasers. The IGBTs are connected
in series to achieve a high voltage rating. An avalanche transistor is
used as the gate driver. The fast pulse generated by the avalanche
transistor quickly charges the large input capacitance of the IGBT,
resulting in a switch out of a fast high-voltage pulse. The switching
characteristic of fast-high voltage solid state switch has been estimated
in the multi-stage series-connected IGBT with the applied voltage of
several tens of kV. Electrical circuit diagram and the mythology of
fast-high voltage solid state switch as well as experimental results
obtained are presented.
Abstract: Present study is aimed on the cutting process of circular
cross-section rods where the fracture is used to separate one rod
into two pieces. Incorporating the phenomenological ductile fracture
model into the explicit formulation of finite element method, the
process can be analyzed without the necessity of realizing too many
real experiments which could be expensive in case of repetitive
testing in different conditions. In the present paper, the steel AISI
1045 was examined and the tensile tests of smooth and notched
cylindrical bars were conducted together with biaxial testing of the
notched tube specimens to calibrate material constants of selected
phenomenological ductile fracture models. These were implemented
into the Abaqus/Explicit through user subroutine VUMAT and used
for cutting process simulation. As the calibration process is based
on variables which cannot be obtained directly from experiments,
numerical simulations of fracture tests are inevitable part of the
calibration. Finally, experiments regarding the cutting process were
carried out and predictive capability of selected fracture models is
discussed. Concluding remarks then make the summary of gained
experience both with the calibration and application of particular
ductile fracture criteria.
Abstract: In this study, we aim to demonstrate a microgrid
system experimental simulation for an easy understanding of a
large-scale microgrid system. This model is required for industrial
training and learning environments. However, in order to create an
exact representation of a microgrid system, the laboratory-scale
system must fulfill the requirements of a grid-connected inverter, in
which power values are assigned to the system to cope with the
intermittent output from renewable energy sources. Aside from that,
during fluctuations in load capacity, the grid-connected system must
be able to supply power from the utility grid side and microgrid side in
a balanced manner. Therefore, droop control is installed in the
inverter’s control board to maintain a balanced power sharing in both
sides. This power control in a stand-alone condition and droop control
in a grid-connected condition must be implemented in order to
maintain a stabilized system. Based on the experimental results, power
control and droop control can both be applied in the system by
comparing the experimental and reference values.
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: This paper present the experimental work of double
unit tunnel form building (TFB) subjected to in-plane lateral cyclic
loading. A one third scale of 3-storey double unit of TFB is tested
until its strength degradation. Then, the TFB is repaired and
retrofitted using additional shear wall, steel angle and CFRP sheet.
The crack patterns, lateral strength, stiffness, ductility and equivalent
viscous damping (EVD) were analyzed and compared before and
after repair and retrofit. The result indicates that the lateral strength
increases by 22% in pushing and 27% in pulling direction. Moreover,
the stiffness and ductility obtained before and after retrofit increase
tremendously by 87.87% and 39.66%, respectively. Meanwhile, the
energy absorption measured by equivalent viscous damping obtained
after retrofit increase by 12.34% in pulling direction. It can be
concluded that the proposed retrofit method is capable to increase the
lateral strength capacity, stiffness and energy absorption of double
unit TFB.
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 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: 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: Life Cycle Cost (LCC) is one of the goals and key
pillars of the construction management science because it comprises
many of the functions and processes necessary, which assist
organisations and agencies to achieve their goals. It has therefore
become important to design and control assets during their whole life
cycle, from the design and planning phase through to disposal phase.
LCCA is aimed to improve the decision making system in the
ownership of assets by taking into account all the cost elements
including to the asset throughout its life.
Current application of LCC approach is impractical during
misunderstanding of the advantages of LCC. This main objective of
this research is to show a different relationship between capital cost
and long-term running costs. One hundred and thirty eight actual
building projects in United Kingdom (UK) were used in order to
achieve and measure the above-mentioned objective of the study. The
result shown that LCC is one of the most significant tools should be
considered on the decision making process.