Abstract: This paper focuses on the study of DC-to-DC
converters, which are suitable for low-voltage high-power
applications. The output voltages generated by renewable energy
sources such as photovoltaic arrays and fuel cell stacks are
generally low and required to be increased to high voltage levels.
Development of DC-to-DC converters, which provide high step-up
voltage conversion ratios with high efficiencies and low voltage
stresses, is one of the main issues in the development of renewable
energy systems. A procedure for three converters−conventional
DC-to-DC converter, interleaved boost converter, and isolated flyback
based converter, is illustrated for a given set of specifications. The
selection among the converters for the given application is based on
the voltage conversion ratio, efficiency, and voltage stresses.
Abstract: Polymeric composites are being increasingly used as
repair material for repairing critical infrastructures such as building,
bridge, pressure vessel, piping and pipeline. Technique in repairing
damaged pipes is one of the major concerns of pipeline owners.
Considerable researches have been carried out on the repair of
corroded pipes using composite materials. This article attempts a
short review of the subject matter to provide insight into various
techniques used in repairing corroded pipes, focusing on a wide range
of composite repair systems. These systems including pre-cured
layered, flexible wet lay-up, pre-impregnated, split composite sleeve
and flexible tape systems. Both advantages and limitations of these
repair systems were highlighted. Critical technical aspects have been
discussed through the current standards and practices. Research gaps
and future study scopes in achieving more effective design
philosophy are also presented.
Abstract: This experimental study consists of a characterization
of epoxy grout where an amount of 2% of graphene nanoplatelets
particles were added to commercial epoxy resin to evaluate their
behavior regarding neat epoxy resin. Compressive tests, tensile tests
and flexural tests were conducted to study the effect of graphene
nanoplatelets on neat epoxy resin. By comparing graphene-based and
neat epoxy grout, there is no significant increase of strength due to
weak interface in the graphene nanoplatelets/epoxy composites.
From this experiment, the tension and flexural strength of graphenebased
epoxy grouts is slightly lower than ones of neat epoxy grout.
Nevertheless, the addition of graphene has produced more consistent
results according to a smaller standard deviation of strength.
Furthermore, the graphene has also improved the ductility of the
grout, hence reducing its brittle behaviour. This shows that the
performance of graphene-based grout is reliably predictable and able
to minimise sudden rupture. This is important since repair design of
damaged pipeline is of deterministic nature.
Abstract: Hard coatings are widely used in cutting and forming
tool industries. Titanium Nitride (TiN) possesses good hardness,
strength, and corrosion resistance. The coating properties are
influenced by many process parameters. The coatings were deposited
on steel substrate by changing the process parameters such as
substrate temperature, nitrogen flow rate and target power in a D.C
planer magnetron sputtering. The structure of coatings were analysed
using XRD. The hardness of coatings was found using Micro
hardness tester. From the experimental data, a regression model was
developed and the optimum response was determined using Response
Surface Methodology (RSM).
Abstract: Rapid developments in technology in the present age
have made it necessary for communities to follow technological
developments and adapt themselves to these developments. One of
the fields that are most rapidly affected by these developments is
undoubtedly education. Determination of the attitudes of preservice
teachers, who live in an age of technology and get ready to raise
future individuals, is of paramount importance both educationally and
professionally. The purpose of this study was to analyze attitudes of
preservice teachers towards technology and some variables that
predict these attitudes (gender, daily duration of internet use, and the
number of technical devices owned). 329 preservice teachers
attending the education faculty of a large university in central Turkey
participated, on a volunteer basis, in this study, where relational
survey model was used as the research method. Research findings
reveal that preservice teachers’ attitudes towards technology are
positive and at the same time, the attitudes of male preservice
teachers towards technology are more positive than their female
counterparts. As a result of the stepwise multiple regression analysis
where factors predicting preservice teachers’ attitudes towards
technology, it was found that duration of daily internet use was the
strongest predictor of attitudes towards technology.
Abstract: The need to protect our cultural heritage was stressed
on revitalization of historical city centers in communities. The main
aim of this research is to attract finance and activities to the historical
city centers through the citizens and municipalities participation
while cities expanded their boundaries toward suburban areas. Today
the main problems which facing to the most historical city centers, is
loss of their centrality through effect of urbanization on any point of
the cities which is the most important issue on neglect and
abandonment of the historical central area by decentralizing living,
commerce and public areas. This article evaluate the ways in which
city center revitalization can be effect on vitality and viability of the
central area in case of Naghshe Jahan square which situated at the
center of Isfahan city, Iran. Constructed between 1598 and 1629, it is
now an important historical site, and one of UNESCO's World
Heritage Sites.
Abstract: Over the last two decades, externally bonded fiber
reinforced polymer (FRP) composites bonded to concrete substrates
has become a popular method for strengthening reinforced concrete
(RC) highway and railway bridges. Such structures are exposed to
severe cyclic loading throughout their lifetime often resulting in
fatigue damage to structural components and a reduction in the
service life of the structure. Since experimental and numerical results
on the fatigue performance of FRP-to-concrete joints are still limited,
the current research focuses on assessing the fatigue performance of
externally bonded FRP-to-concrete joints using a direct shear test.
Some early results indicate that the stress ratio and the applied cyclic
stress level have a direct influence on the fatigue life of the externally
bonded FRP. In addition, a calibrated finite element model is
developed to provide further insight into the influence of certain
parameters such as: concrete strength, FRP thickness, number of
cycles, frequency, and stiffness on the fatigue life of the FRP-toconcrete
joints.
Abstract: Fresh concrete has one of dynamic properties known
as slump. Slump of concrete is design to compatible with placing
method. Due to hydration reaction of cement, the slump of concrete
is loss through time. Therefore, delayed concrete probably get reject
because slump is unacceptable. In order to recover the slump of
delayed concrete the second dose of superplasticizer (naphthalene
based type F) is added into the system, the slump recovery can be
done as long as the concrete is not setting. By adding superplasticizer
as solution for recover unusable slump loss concrete may affects
other concrete properties. Therefore, this paper was observed setting
times and compressive strength of concrete after being re-dose with
chemical admixture type F (superplasticizer, naphthalene based) for
slump recovery. The concrete used in this study was fly ash concrete
with fly ash replacement of 0%, 30% and 50% respectively. Concrete
mix designed for test specimen was prepared with paste content (ratio
of volume of cement to volume of void in the aggregate) of 1.2 and
1.3, water-to-binder ratio (w/b) range of 0.3 to 0.58, initial dose of
superplasticizer (SP) range from 0.5 to 1.6%. The setting times of
concrete were tested both before and after re-dosed with different
amount of second dose and time of dosing. The research was
concluded that addition of second dose of superplasticizer would
increase both initial and final setting times accordingly to dosage of
addition. As for fly ash concrete, the prolongation effect was higher
as the replacement of fly ash increase. The prolongation effect can
reach up to maximum about 4 hours. In case of compressive strength,
the re-dosed concrete has strength fluctuation within acceptable range
of ±10%.
Abstract: This paper describes the development of new class of
epoxy based rice husk filled jute reinforced composites. Rice husk
flour is added in 0%, 1%, 3%, 5% by weight. Epoxy resin and
triethylenetetramine (T.E.T.A) is used as matrix and hardener
respectively. It investigates the mechanical properties of the
composites and a comparison is done for monolithic jute composite
and the filled ones. The specimens are prepared according to the
ASTM standards and experimentation is carried out using INSTRON
8801. The result shows that with the increase of filler percentage the
tensile properties increases but compressive and flexural properties
decreases.
Abstract: The research investigates the causes of unemployment
in Namibia, Nigeria and South Africa and the role of Capital
Accumulation in reducing the unemployment profile of these
economies as proposed by the post-Keynesian economics. This is
conducted through extensive review of literature on the NAIRU
models and focused on the post-Keynesian view of unemployment
within the NAIRU framework. The NAIRU (non-accelerating
inflation rate of unemployment) model has become a dominant
framework used in macroeconomic analysis of unemployment. The
study views the post-Keynesian economics arguments that capital
accumulation is a major determinant of unemployment.
Unemployment remains the fundamental socio-economic challenge
facing African economies. It has been a burden to citizens of those
economies. Namibia, Nigeria, and South Africa are great African
nations battling with high unemployment rates. The high
unemployment rate in the country led the citizens to chase away
foreigners in the country claiming that they have taken away their
jobs. The study proposes there is a strong relationship between
capital accumulation and unemployment in Namibia, Nigeria, and
South Africa, and capital accumulation is responsible for high
unemployment rates in these countries. For the economies to achieve
steady state level of employment and satisfactory level of economic
growth and development, there is need for capital accumulation to
take place. The countries in the study have been selected after a
critical research and investigations. They are selected based on the
following criteria; African economies with high unemployment rates
above 15% and have about 40% of their workforce unemployed. This
level of unemployment is the critical level of unemployment in
Africa as expressed by International Labour Organization (ILO). And
finally, the African countries experience a slow growth in their Gross
fixed capital formation. Adequate statistical measures have been
employed using a time-series analysis in the study and the results
revealed that capital accumulation is the main driver of
unemployment performance in the chosen African countries. An
increase in the accumulation of capital causes unemployment to
reduce significantly. The results of the research work will be useful
and relevant to federal governments and ministries, departments and
agencies (MDAs) of Namibia, Nigeria and South Africa to resolve
the issue of high and persistent unemployment rates in their
economies which are great burden that slows growth and
development of developing economies. Also, the result can be useful
to World Bank, African Development Bank and International Labour
Organization (ILO) in their further research and studies on how to
tackle unemployment in developing and emerging economies.
Abstract: The question of legal liability over injury arising out
of the import and the introduction of GM food emerges as a crucial
issue confronting to promote GM food and its derivatives. There is a
greater possibility of commercialized GM food from the exporting
country to enter importing country where status of approval shall not
be same. This necessitates the importance of fixing a liability
mechanism to discuss the damage, if any, occurs at the level of
transboundary movement or at the market. There was a widespread consensus to develop the Cartagena
Protocol on Biosafety and to give for a dedicated regime on liability
and redress in the form of Nagoya Kuala Lumpur Supplementary
Protocol on the Liability and Redress (‘N-KL Protocol’) at the
international context. The national legal frameworks based on this
protocol are not adequately established in the prevailing food
legislations of the developing countries. The developing economy
like India is willing to import GM food and its derivatives after the
successful commercialization of Bt Cotton in 2002. As a party to the
N-KL Protocol, it is indispensable for India to formulate a legal
framework and to discuss safety, liability, and regulatory issues
surrounding GM foods in conformity to the provisions of the
Protocol. The liability mechanism is also important in the case where
the risk assessment and risk management is still in implementing
stage. Moreover, the country is facing GM infiltration issues with its
neighbors Bangladesh. As a precautionary approach, there is a need
to formulate rules and procedure of legal liability to discuss any kind
of damage occurs at transboundary trade. In this context, the
proposed work will attempt to analyze the liability regime in the
existing Food Safety and Standards Act, 2006 from the applicability
and domestic compliance and to suggest legal and policy options for
regulatory authorities.
Abstract: The quality of concrete is usually defined by compressive strength, but flexural strength is the most important characteristic of concrete in a pavement which control the mix design of concrete instead of compressive strength. Therefore, the aggregates which are selected for the pavements are affected by higher flexural strength. Roller Compacting Concrete Pavement (RCCP) is not a new construction method. The other characteristic of this method is no bleeding and less shrinkage due to the lower amount of water. For this purpose, a roller is needed for placing and compacting. The surface of RCCP is not smooth; therefore, the most common use of this pavement is in an industrial zone with slower traffic speed which requires durable and tough pavement. For preparing a smoother surface, it can be achieved by asphalt paver. RCCP decrease the finishing cost because there are no bars, formwork, and the lesser labor need for placing the concrete. In this paper, different aspect of RCCP such as mix design, flexural, compressive strength and focus on the different part of RCCP on detail have been investigated.
Abstract: Carbon dioxide is one of the major greenhouse gas
(GHG) contributors. It is an obligation of the industry to reduce the
amount of carbon dioxide emission to the acceptable limits.
Tremendous research and studies are reported in the past and still the
quest to find the suitable and economical solution of this problem
needed to be explored in order to develop the most plausible absorber
for carbon dioxide removal. Amino acids can be potential alternate
solvents for carbon dioxide capture from gaseous streams. This is due
to its ability to resist oxidative degradation, low volatility and its
ionic structure. In addition, the introduction of promoter-like
piperazine to amino acid helps to further enhance the solubility. In
this work, the effect of piperazine on thermo physical properties and
solubility of β-Alanine aqueous solutions were studied for various
concentrations. The measured physicochemical properties data was
correlated as a function of temperature using least-squares method
and the correlation parameters are reported together with it respective
standard deviations. The effect of activator piperazine on the CO2
loading performance of selected amino acid under high-pressure
conditions (1bar to 10bar) at temperature range of (30 to 60)oC was
also studied. Solubility of CO2 decreases with increasing temperature
and increases with increasing pressure. Quadratic representation of
solubility using Response Surface Methodology (RSM) shows that
the most important parameter to optimize solubility is system
pressure. The addition of promoter increases the solubility effect of
the solvent.
Abstract: This paper deals with using of prevailing operation
system MS Office (SmartArt...) for mathematical models, using
DYVELOP (Dynamic Vector Logistics of Processes) method. It
serves for crisis situations investigation and modelling within the
organizations of critical infrastructure. In first part of paper, it will be
introduced entities, operators, and actors of DYVELOP method. It
uses just three operators of Boolean algebra and four types of the
entities: the Environments, the Process Systems, the Cases, and the
Controlling. The Process Systems (PrS) have five “brothers”:
Management PrS, Transformation PrS, Logistic PrS, Event PrS and
Operation PrS. The Cases have three “sisters”: Process Cell Case,
Use Case, and Activity Case. They all need for the controlling of
their functions special Ctrl actors, except ENV – it can do without
Ctrl. Model´s maps are named the Blazons and they are able
mathematically - graphically express the relationships among entities,
actors and processes. In second part of this paper, the rich blazons of
DYVELOP method will be used for the discovering and modelling of
the cycling cases and their phases. The blazons need live PowerPoint
presentation for better comprehension of this paper mission. The
crisis management of energetic crisis infrastructure organization is
obliged to use the cycles for successful coping of crisis situations.
Several times cycling of these cases is necessary condition for the
encompassment for both emergency events and the mitigation of
organization´s damages. Uninterrupted and continuous cycling
process brings for crisis management fruitfulness and it is good
indicator and controlling actor of organizational continuity and its
sustainable development advanced possibilities. The research reliable
rules are derived for the safety and reliable continuity of energetic
critical infrastructure organization in the crisis situation.
Abstract: This paper presents numerical analysis in terms of
buckling resistance of GFRP sandwich infill panels system under the
influence of increased temperature on the foam core. Failure mode
under in-plane compression is studied by means of numerical analysis
with ABAQUS platform. Parameters considered in this study are
contact length and both the type of foam for core and the variation of
its module elastic under the thermal influence. Increment of
temperature is considered in static cases and only applied to core.
Indeed, it is proven that the effect of temperature alters the mechanical
properties of the entire panel system. Moreover, the rises of
temperature result in a decrease in strength of the panel. This is due to
the polymeric nature of this material. Additionally, the contact length
also displays the effect on performance of infill panel. Their
significance factors are based on type of polymer for core. Therefore,
by comparing difference type of core material, the variation can be
reducing.
Abstract: In this paper, von Mises and Drucker-Prager yield criteria, as typical ones that consider the effect of intermediate principal stress σ2, have been selected and employed for investigating the influence of σ2 on the solution of a typical stability problem. The bearing capacity factors have been calculated under plane strain condition (strip footing) and axisymmetric condition (circular footing) using the method of stress characteristics together with the criteria mentioned. Different levels of σ2 relative to the other two principal stresses have been considered. While a higher σ2 entry in yield criterion gives a higher bearing capacity; its entry in equilibrium equations (axisymmetric) causes substantial reduction.
Abstract: Hydrogen produced by means of polymer electrolyte
membrane electrolyzer (PEME) is one of the most promising
methods due to clean and renewable energy source. In the process,
some energy loss due to mass transfer through a PEM is caused by
diffusion, electro-osmotic drag, and the pressure difference between
the cathode channel and anode channel. In PEME, water molecules
and ionic particles transferred between the electrodes from anode to
cathode, Extensive mixing of the hydrogen and oxygen at anode
channel due to gases cross-over must be avoided. In recent times the
consciousness of safety issue in high pressure PEME where the
oxygen mix with hydrogen at anode channel could create, explosive
conditions have generated a lot of concern. In this paper, the steady
state and simulation analysis of gases crossover in PEME on the
temperature and pressure effect are presented. The simulations have
been analysis in MATLAB based on the well-known Fick’s Law of
molecular diffusion. The simulation results indicated that as
temperature increases, there is a significant decrease in operating
voltage.
Abstract: This study focuses on the stress analysis of Mandibular
Advancement Devices (MADs), which are considered as a standard
treatment of snoring that promoted by American Academy of Sleep
Medicine (AASM). Snoring is the most significant feature of
sleep-disordered breathing (SDB). SDB will lead to serious problems
in human health. Oral appliances are ensured in therapeutic effect and
compliance, especially the MADs. This paper proposes a new MAD
design, and the finite element analysis (FEA) is introduced to precede
the stress simulation for this MAD.
Abstract: Opportunistic Routing (OR) increases the
transmission reliability and network throughput. Traditional routing
protocols preselects one or more predetermined nodes before
transmission starts and uses a predetermined neighbor to forward a
packet in each hop. The opportunistic routing overcomes the
drawback of unreliable wireless transmission by broadcasting one
transmission can be overheard by manifold neighbors. The first
cooperation-optimal protocol for Multirate OR (COMO) used to
achieve social efficiency and prevent the selfish behavior of the
nodes. The novel link-correlation-aware OR improves the
performance by exploiting the miscellaneous low correlated forward
links. Context aware Adaptive OR (CAOR) uses active suppression
mechanism to reduce packet duplication. The Context-aware OR
(COR) can provide efficient routing in mobile networks. By using
Cooperative Opportunistic Routing in Mobile Ad hoc Networks
(CORMAN), the problem of opportunistic data transfer can be
tackled. While comparing to all the protocols, COMO is the best as it
achieves social efficiency and prevents the selfish behavior of the
nodes.
Abstract: Rivers have transient storage or dead zones where
injected pollutants or solutes are entrapped for considerable period of
time, known as residence time, before being released into the main
flowing zones of rivers. In this study, a new empirical expression for
residence time, implementing genetic programming on published
dispersion data, has been derived. The proposed expression uses few
hydraulic and geometric characteristics of rivers which are normally
known to the authorities. When compared with some reported
expressions, based on various statistical indices, it can be concluded
that the proposed expression predicts the residence time of pollutants
in natural rivers more accurately.