Abstract: This paper presented the results of an experimental
investigation into the axial fatigue behavior of a 5086 aluminum
alloy which have several notch-aspect ratios a0/c0 and notch
thickness ratio a/t with semi-elliptical surface cracks. Tests were
conducted in la b air for stress levels of 50 % of their yield
strength. Experiments were carried out for various notch to
thickness ratios. Crack growth rates of test specimens both in
surface and depth directions were determined by using die
penetration method. Fuzzy Logic method was used to predict the
deep direction crack growth because the dept of the crack is
considerably difficult to measure.
Abstract: Multilevel inverters supplied from equal and constant
dc sources almost don-t exist in practical applications. The variation
of the dc sources affects the values of the switching angles required
for each specific harmonic profile, as well as increases the difficulty
of the harmonic elimination-s equations. This paper presents an
extremely fast optimal solution of harmonic elimination of multilevel
inverters with non-equal dc sources using Tanaka's fuzzy linear
regression formulation. A set of mathematical equations describing
the general output waveform of the multilevel inverter with nonequal
dc sources is formulated. Fuzzy linear regression is then
employed to compute the optimal solution set of switching angles.
Abstract: Over the past few years, XML (eXtensible Mark-up
Language) has emerged as the standard for information
representation and data exchange over the Internet. This paper
provides a kick-start for new researches venturing in XML databases
field. We survey the storage representation for XML document,
review the XML query processing and optimization techniques with
respect to the particular storage instance. Various optimization
technologies have been developed to solve the query retrieval and
updating problems. Towards the later year, most researchers
proposed hybrid optimization techniques. Hybrid system opens the
possibility of covering each technology-s weakness by its strengths.
This paper reviews the advantages and limitations of optimization
techniques.
Abstract: In this paper, numerical simulation is used to
investigate the thermal performance of liquid cooling heatsink with
microchannels due to geometric arrangement. Commercial software
ICEPAK is utilized for the analysis. The considered parameters
include aspect ratio, porosity and the length and height of
microchannel. The aspect ratio varies from 3 to 16 and the length of
microchannel is 10mm, 14mm, and 18mm. The height of
microchannel is 2mm, 3mm and 4mm. It is found short channel have
better thermal efficiency than long channel at 490Pa. No matter the
length of channel the best aspect ratio is 4. It is also noted that pressure
difference at 2940Pa the best aspect ratio from 4 to 8, it means pressure
difference affect aspect ratio, effective thermal resistance at low
pressure difference but lower effective thermal resistance at high
pressure difference.
Abstract: Turbulence modeling of large-scale flow over a vegetated surface is complex. Such problems involve large scale computational domains, while the characteristics of flow near the surface are also involved. In modeling large scale flow, surface roughness including vegetation is generally taken into account by mean of roughness parameters in the modified law of the wall. However, the turbulence structure within the canopy region cannot be captured with this method, another method which applies source/sink terms to model plant drag can be used. These models have been developed and tested intensively but with a simple surface geometry. This paper aims to compare the use of roughness parameter, and additional source/sink terms in modeling the effect of plant drag on wind flow over a complex vegetated surface. The RNG k-ε turbulence model with the non-equilibrium wall function was tested with both cases. In addition, the k-ω turbulence model, which is claimed to be computationally stable, was also investigated with the source/sink terms. All numerical results were compared to the experimental results obtained at the study site Mason Bay, Stewart Island, New Zealand. In the near-surface region, it is found that the results obtained by using the source/sink term are more accurate than those using roughness parameters. The k-ω turbulence model with source/sink term is more appropriate as it is more accurate and more computationally stable than the RNG k-ε turbulence model. At higher region, there is no significant difference amongst the results obtained from all simulations.
Abstract: Aluminum alloy sheets have several advantages such
as the lightweight, high-specific strength and recycling efficiency.
Therefore, aluminum alloy sheets in sheet forming have been used in various areas as automotive components and so forth. During the
process of sheet forming, wrinkling which is caused by compression stress might occur and the formability of sheets was affected by
occurrence of wrinkling. A few studies of uniaxial compressive test by
using square tubes, pipes and sheets were carried out to clarify the each wrinkling behavior. However, on uniaxial compressive test,
deformation behavior of the sheets hasn-t be cleared. Then, it is necessary to clarify the relationship between the buckling behavior
and the forming conditions. In this study, the effect of dimension of the sheet in the buckling behavior on compression test of aluminum alloy sheet was cleared by experiment and FEA. As the results, the buckling
deformation was classified by three modes in terms of the distribution of equivalent plastic strain.
Abstract: This paper is a simple and systematic approaches to the design and analysis a pulse width modulation (PWM) based sliding mode controller for buck DC-DC Converters. Various aspects of the design, including the practical problems and the proposed solutions, are detailed. However, these control strategies can't compensate for large load current and input voltage variations. In this paper, a new control strategy by compromising both schemes advantages and avoiding their drawbacks is proposed, analyzed and simulated.
Abstract:
Innovation is becoming more and more important in
modern society. There are a lot of researches on different kinds of
innovation but marketing innovation is one kind of innovation that
has not been studied frequently before. Marketing innovation is
defined as a new way in which companies can market themselves to
potential or existing customers.
The study shows some key elements for marketing innovation that
are worth paying attention to when implementing marketing
innovation projects. Examples of such key elements are: paying
attention to the neglected market, suitable market segmentatio
reliable market information, public relationship, increased customer
value, combination of market factors, explore different marketing
channels and the use of technology in combination with what? Beside
the key elements for marketing innovation, we also present some
risks that may occur, such as cost, market uncertainty, information
leakage, imitation and overdependence on experience.
By proposing a set of indicators to measure marketing innovation,
the article offers solutions for marketing innovation implementation
so that any organization can achieve optimal results.
Abstract: The integral form of equations of motion of composite
beams subjected to varying time loads are discretized using a
developed finite element model. The model consists of a straight five
node twenty-two degrees of freedom beam element. The stability
analysis of the beams is studied by solving the matrix form
characteristic equations of the system. The principle of virtual work
and the first order shear deformation theory are employed to analyze
the beams with large deformation and small strains. The regions of
dynamic instability of the beam are determined by solving the
obtained Mathieu form of differential equations. The effects of nonconservative
loads, shear stiffness, and damping parameters on
stability and response of the beams are examined. Several numerical
calculations are presented to compare the results with data reported
by other researchers.
Abstract: The paper compares different channel models used for
modeling Broadband Power-Line Communication (BPLC) system.
The models compared are Zimmermann and Dostert, Philipps,
Anatory et al and Anatory et al generalized Transmission Line (TL)
model. The validity of each model was compared in time domain
with ATP-EMTP software which uses transmission line approach. It
is found that for a power-line network with minimum number of
branches all the models give similar signal/pulse time responses
compared with ATP-EMTP software; however, Zimmermann and
Dostert model indicates the same amplitude but different time delay.
It is observed that when the numbers of branches are increased only
generalized TL theory approach results are comparable with ATPEMTP
results. Also the Multi-Carrier Spread Spectrum (MC-SS)
system was applied to check the implication of such behavior on the
modulation schemes. It is observed that using Philipps on the
underground cable can predict the performance up to 25dB better
than other channel models which can misread the actual performance
of the system. Also modified Zimmermann and Dostert under
multipath can predict a better performance of about 5dB better than
the actual predicted by Generalized TL theory. It is therefore
suggested for a realistic BPLC system design and analyses the model
based on generalized TL theory be used.
Abstract: For sterilization of Phalaenopsis culture medium without autoclaving, selected single sterilizing agents and in combinations were added to a 25ml Hyponex medium in a 120ml glass container. Treated liquid and solid media, supplemented with sterilizing agents, were compared to a control medium, autoclaved at 121°C for 15min. It was found that 90(L of 10% povidone-iodine, 150(L of 5.25% sodium hypochlorite, 150(L of 2% mercurochrome, 90(L of 2.5% iodine + 2.5% potassium iodine in combination with 10% providone-iodine (1:3) and 30(L of 2.5% iodine + 2.5% potassium iodide in combination with 2% mercurochrome showed 100% sterile conditions in liquid medium but provided 75, 100, 50, 75 and 80% sterile conditions, respectively, in solid medium. For growth of Phalaenopsis protocorms, 90(L of 10% povidone-iodine in liquid Hyponex medium gave the comparable growth of protocorms to control medium while 150(L of 5.25% sodium hypochlorite in solid medium provided the promising growth of protocorms. Growth of protocorms, whole fresh weight, numbers of leaf and root, root length and number of protocorm-like bodies, was discussed.
Abstract: Even it has been recognized that Shape Memory
Alloys (SMA) have a significant potential for deployment actuators,
the number of applications of SMA-based actuators to the present
day is still quite small, due to the need of deep understanding of the
thermo-mechanical behavior of SMA, causing an important need for
a mathematical model able to describe all thermo-mechanical
properties of SMA by relatively simple final set of constitutive
equations. SMAs offer attractive potentials such as: reversible strains
of several percent, generation of high recovery stresses and high
power / weight ratios. The paper tries to provide an overview of the
shape memory functions and a presentation of the designed and
developed temperature control system used for a gripper actuated by
two pairs of differential SMA active springs. An experimental setup
was established, using electrical energy for actuator-s springs heating
process. As for holding the temperature of the SMA springs at certain
level for a long time was developed a control system in order to
avoid the active elements overheating.
Abstract: Estimation of natural frequency of structures is very
important and isn-t usually calculated simply and sometimes
complicated. Lack of knowledge about that caused hard damage and
hazardous effects.
In this paper, with using from two different models in FEM
method and based on hydrodynamic mass of fluids, natural frequency
of an especial bearing (Fig. 1) in an electric field (or, a periodic
force) is calculated in different stiffness and different geometric. In
final, the results of two models and analytical solution are compared.
Abstract: A climate dependent model is proposed to simulate
the population of Aedes aegypti mosquito. In developing the model,
average temperature of Shah Alam, Malaysia was used to determine
the development rate of each stage of the life cycle of mosquito.
Rainfall dependent function was proposed to simulate the hatching
rate of the eggs under several assumptions. The proposed transition
matrix was obtained and used to simulate the population of eggs,
larvae, pupae and adults mosquito. It was found that the peak of
mosquito abundance comes during a relatively dry period following a
heavy rainfall. In addition, lag time between the peaks of mosquito
abundance and dengue fever cases in Shah Alam was estimated.
Abstract: Lignocellulosic materials are considered the most
abundant renewable resource available for the Bioethanol
Production. Water Hyacinth is one of potential raw material of the
world-s worst aquatic plant as a feedstock to produce Bioethanol.
The purposed this research is obtain reduced of matter for
biodegradation lignin in Biological pretreatment with White Rot
Fungi eg. Phanerochaete Chrysosporium using Solid state
Fermentation methods. Phanerochaete Chrysosporium is known to
have the best ability to degraded lignin, but simultaneously it can also
degraded cellulose and hemicelulose. During 8 weeks incubation,
water hyacinth occurred loss of weight reached 34,67%, while loss
of lignin reached 67,21%, loss of cellulose reached 11,01% and loss
of hemicellulose reached 36,56%. The kinetic of losses lignin using
regression linear plot, the results is obtained constant rate (k) of
reduction lignin is -0.1053 and the equation of reduction of lignin
is y = wo - 0, 1.53 x
Abstract: In this paper the complete rotor system including
elastic shaft with distributed mass, allowing for the effects of oil film
in bearings. Also, flexibility of foundation is modeled. As a whole
this article is a relatively complete research in modeling and
vibration analysis of rotor considering gyroscopic effect, damping,
dependency of stiffness and damping coefficients on frequency and
solving the vibration equations including these parameters. On the
basis of finite element method and utilizing four element types
including element of shaft, disk, bearing and foundation and using
MATLAB, a computer program is written. So the responses in
several cases and considering different effects are obtained. Then the
results are compared with each other, with exact solutions and results
of other papers.
Abstract: In this investigation, anatase TiO2 thin films were
grown by radio frequency magnetron sputtering on glass substrates at
a high sputtering pressure and room temperature. The anatase films
were then annealed at 300-600 °C in air for a period of 1 hour. To
examine the structure and morphology of the films, X-ray diffraction
(XRD) and atomic force microscopy (AFM) methods were used
respectively. From X-ray diffraction patterns of the TiO2 films, it was
found that the as-deposited film showed some differences compared
with the annealed films and the intensities of the peaks of the
crystalline phase increased with the increase of annealing
temperature. From AFM images, the distinct variations in the
morphology of the thin films were also observed. The optical
constants were characterized using the transmission spectra of the
films obtained by UV-VIS-IR spectrophotometer. Besides, optical
thickness of the film deposited at room temperature was calculated
and cross-checked by taking a cross-sectional image through SEM.
The optical band gaps were evaluated through Tauc model. It was
observed that TiO2 films produced at room temperatures exhibited
high visible transmittance and transmittance decreased slightly with
the increase of annealing temperatures. The films were found to be
crystalline having anatase phase. The refractive index of the films
was found from 2.31-2.35 in the visible range. The extinction
coefficient was nearly zero in the visible range and was found to
increase with annealing temperature. The allowed indirect optical
band gap of the films was estimated to be in the range from 3.39 to
3.42 eV which showed a small variation. The allowed direct band
gap was found to increase from 3.67 to 3.72 eV. The porosity was
also found to decrease at a higher annealing temperature making the
film compact and dense.
Abstract: In recent years, copulas have become very popular in
financial research and actuarial science as they are more flexible in
modelling the co-movements and relationships of risk factors as compared
to the conventional linear correlation coefficient by Pearson.
However, a precise estimation of the copula parameters is vital in
order to correctly capture the (possibly nonlinear) dependence structure
and joint tail events. In this study, we employ two optimization
heuristics, namely Differential Evolution and Threshold Accepting to
tackle the parameter estimation of multivariate t distribution models
in the EML approach. Since the evolutionary optimizer does not rely
on gradient search, the EML approach can be applied to estimation of
more complicated copula models such as high-dimensional copulas.
Our experimental study shows that the proposed method provides
more robust and more accurate estimates as compared to the IFM
approach.
Abstract: Because of the global warming and the rising sea level, residents living in southwestern coastland, Taiwan are faced with the submerged land and may move to higher elevation area. It is desirable to discuss the key consideration factor for selecting the migration location under five dimensions of ಯ security”, “health”, “convenience”, “comfort” and “socio-economic” based on the document reviews. This paper uses the Structural Equation Modeling (SEM) and the questionnaire survey. The analysis results show that the convenience is the most key factor for residents in Taiwan.
Abstract: In this paper, we present a technical and an economic
assessment of several sources of renewable energy in Saudi Arabia;
mainly solar, wind, hydro and biomass. We analyze the
environmental and climatic conditions in relation to these sources
and give an overview of some of the existing clean energy
technologies. Using standardized cost and efficiency data, we carry
out a cost benefit analysis to understand the economic factors
influencing the sustainability of energy production from renewable
sources in light of the energy cost and demand in the Saudi market.
Finally, we take a look at the Saudi petroleum industry and the
existing sources of conventional energy and assess the potential of
building a successful market for renewable energy under the
constraints imposed by the flow of subsidized cheap oil. We show
that while some renewable energy resources are well suited for
distributed or grid connected generation in the kingdom, their
viability is greatly undercut by the well developed and well
capitalized oil industry.