Abstract: A numerical study has been conducted to investigate the influence of fin pitch and relative humidity on the heat transfer performance of the fin-and-tube heat exchangers having plain fin geometry under dehumidifying conditions. The analysis is done using the ratio between the heat transfer coefficients in totally wet conditions and those in totally dry conditions using the appropriate correlations for both dry and wet conditions. For a constant relative humidity, it is found that the heat transfer coefficient increases with the increase of the air frontal velocity. By contrast, the fin efficiency decreases when the face velocity is increased. Apparently, this phenomenon is attributed to the path of condensate drainage. For the influence of relative humidity, the results showed an increase in heat transfer performance and a decrease in wet fin efficiency when relative humidity increases. This is due to the higher amount of mass transfer encountered at higher relative humidity. However, it is found that the effect of fin pitch on the heat transfer performance depends strongly on the face velocity. At lower frontal velocity the heat transfer increases with fin pitch. Conversely, an increase in fin pitch gives lower heat transfer coefficients when air velocity is increased.
Abstract: This paper presents an algorithm of particle swarm
optimization with reduction for global optimization problems. Particle
swarm optimization is an algorithm which refers to the collective
motion such as birds or fishes, and a multi-point search algorithm
which finds a best solution using multiple particles. Particle
swarm optimization is so flexible that it can adapt to a number
of optimization problems. When an objective function has a lot of
local minimums complicatedly, the particle may fall into a local
minimum. For avoiding the local minimum, a number of particles are
initially prepared and their positions are updated by particle swarm
optimization. Particles sequentially reduce to reach a predetermined
number of them grounded in evaluation value and particle swarm
optimization continues until the termination condition is met. In order
to show the effectiveness of the proposed algorithm, we examine the
minimum by using test functions compared to existing algorithms.
Furthermore the influence of best value on the initial number of
particles for our algorithm is discussed.
Abstract: one of the significant factors for improving the
accuracy of Land Surface Temperature (LST) retrieval is the correct
understanding of the directional anisotropy for thermal radiance. In
this paper, the multiple scattering effect between heterogeneous
non-isothermal surfaces is described rigorously according to the
concept of configuration factor, based on which a directional thermal
radiance model is built, and the directional radiant character for urban
canopy is analyzed. The model is applied to a simple urban canopy
with row structure to simulate the change of Directional Brightness
Temperature (DBT). The results show that the DBT is aggrandized
because of the multiple scattering effects, whereas the change range of
DBT is smoothed. The temperature difference, spatial distribution,
emissivity of the components can all lead to the change of DBT. The
“hot spot" phenomenon occurs when the proportion of high
temperature component in the vision field came to a head. On the other
hand, the “cool spot" phenomena occur when low temperature
proportion came to the head. The “spot" effect disappears only when
the proportion of every component keeps invariability. The model
built in this paper can be used for the study of directional effect on
emissivity, the LST retrieval over urban areas and the adjacency effect
of thermal remote sensing pixels.
Abstract: In this paper we will develop a sequential life test approach applied to a modified low alloy-high strength steel part used in highway overpasses in Brazil.We will consider two possible underlying sampling distributions: the Normal and theInverse Weibull models. The minimum life will be considered equal to zero. We will use the two underlying models to analyze a fatigue life test situation, comparing the results obtained from both.Since a major chemical component of this low alloy-high strength steel part has been changed, there is little information available about the possible values that the parameters of the corresponding Normal and Inverse Weibull underlying sampling distributions could have. To estimate the shape and the scale parameters of these two sampling models we will use a maximum likelihood approach for censored failure data. We will also develop a truncation mechanism for the Inverse Weibull and Normal models. We will provide rules to truncate a sequential life testing situation making one of the two possible decisions at the moment of truncation; that is, accept or reject the null hypothesis H0. An example will develop the proposed truncated sequential life testing approach for the Inverse Weibull and Normal models.
Abstract: In recent years multi-agent systems have emerged as one of the interesting architectures facilitating distributed collaboration and distributed problem solving. Each node (agent) of the network might pursue its own agenda, exploit its environment, develop its own problem solving strategy and establish required communication strategies. Within each node of the network, one could encounter a diversity of problem-solving approaches. Quite commonly the agents can realize their processing at the level of information granules that is the most suitable from their local points of view. Information granules can come at various levels of granularity. Each agent could exploit a certain formalism of information granulation engaging a machinery of fuzzy sets, interval analysis, rough sets, just to name a few dominant technologies of granular computing. Having this in mind, arises a fundamental issue of forming effective interaction linkages between the agents so that they fully broadcast their findings and benefit from interacting with others.
Abstract: Starch/chitosan blend have been prepared via the
solution casting technique. Ionic conductivity for the system was
conducted over a wide range of frequency between 50 Hz-1 MHz and
at temperatures between 303 K and 373 K. Sample with 35 wt% of
NH4NO3 shows the highest conductivity of 3.89 ± 0.79 x 10-5 Scm-1
at room temperature. Conductivity-temperature relationship suggests
that samples are Arrhenian. Power law exponent was obtained
through dielectric loss variation and the trend suggests that the
conduction mechanism of the ions can be represented by the
correlated barrier hopping (CBH) model.
Abstract: This paper addresses the problem of asymptotic tracking
control of a linear parabolic partial differential equation with indomain
point actuation. As the considered model is a non-standard
partial differential equation, we firstly developed a map that allows
transforming this problem into a standard boundary control problem
to which existing infinite-dimensional system control methods can
be applied. Then, a combination of energy multiplier and differential
flatness methods is used to design an asymptotic tracking controller.
This control scheme consists of stabilizing state-feedback derived
from the energy multiplier method and feed-forward control based
on the flatness property of the system. This approach represents
a systematic procedure to design tracking control laws for a class
of partial differential equations with in-domain point actuation. The
applicability and system performance are assessed by simulation
studies.
Abstract: Polarization-interferometric nonlinear confocal
microscopy is proposed for measuring a nano-sized particle with
optical anisotropy. The anisotropy in the particle was
spectroscopically imaged through a three-dimensional distribution of
third-order nonlinear dielectric polarization photoinduced.
Abstract: One of the mayor problems of programming a cruise
circuit is to decide which destinations to include and which don-t.
Thus a decision problem emerges, that might be solved using a linear
and goal programming approach. The problem becomes more
complex if several boats in the fleet must be programmed in a limited
schedule, trying their capacity matches best a seasonal demand and
also attempting to minimize the operation costs. Moreover, the
programmer of the company should consider the time of the
passenger as a limited asset, and would like to maximize its usage.
The aim of this work is to design a method in which, using linear and
goal programming techniques, a model to design circuits for the
cruise company decision maker can achieve an optimal solution
within the fleet schedule.
Abstract: All climate models agree that the temperature in
Greece will increase in the range of 1° to 2°C by the year 2030 and
mean sea level in Mediterranean is expected to rise at the rate of 5
cm/decade. The aim of the present paper is the estimation of the
coastline displacement driven by the climate change and sea level
rise. In order to achieve that, all known statistical and non-statistical
computational methods are employed on some Greek coastal areas.
Furthermore, Kalman filtering techniques are for the first time
introduced, formulated and tested. Based on all the above, shoreline
change signals and noises are computed and an inter-comparison
between the different methods can be deduced to help evaluating
which method is most promising as far as the retrieve of shoreline
change rate is concerned.
Abstract: In this paper, a fuzzy algorithm and a fuzzy multicriteria
decision framework are developed and used for a practical
question of optimizing biofuels policy making. The methodological
framework shows how to incorporate fuzzy set theory in a decision
process of finding a sustainable biofuels policy among several policy
options. Fuzzy set theory is used here as a tool to deal with
uncertainties of decision environment, vagueness and ambiguities of
policy objectives, subjectivities of human assessments and imprecise
and incomplete information about the evaluated policy instruments.
Abstract: Here, in this work we study correspondence the energy density New agegraphic and the energy density Gauss- Bonnet models in flat universe. We reconstruct Λ and Λ ω for them with 0 ( ) 0 h a t = a t .
Abstract: In this project electrical and optical properties of
BaZrO3 have been accomplished through the full-potential
linear augmented plane wave (FP-LAPW) by applying Wein2k
software. In this study band structure, density of state, gap energy,
refractive index and optical conduction have been studied. The results
of calculations show that BaZrO3 is an insulator with an indirect gap
in which 3.2 ev and studied refractive index equal 2.07. These results
are in accordance with the ones obtained in experimental researches.
Abstract: The available data on the cross sections of electronimpact
excitation of krypton 5s and 5p configuration levels out of the
ground state are represented in convenient and compact form. The
results are obtained by regression through all known published data
related to this process.
Abstract: The parametrical study of Shrouded Contra-rotating
Rotor was done in this paper based on 2D axisymmetric simulations.
The calculations were made with an actuator disk as double rotor
model. It objects to explore and quantify the effects of different shroud
geometry parameters mainly using the performance of power loading
(PL), which could evaluate the whole propulsion system capability as
5 Newtontotal thrust generationfor hover demand. The numerical
results show that:The increase of nozzle radius is desired but limited
by the flow separation, its optimal design is around 1.15 times rotor
radius, the viscosity effects greatly constraint the influence of nozzle
shape, the divergent angle around 10.5° performs best for chosen
nozzle length;The parameters of inlet such as leading edge curvature,
radius and internal shape do not affect thrust great but play an
important role in pressure distribution which could produce most part
of shroud thrust, they should be chosen according to the reduction of
adverse pressure gradients to reduce the risk of boundary separation.
Abstract: This research paper presents numerical studies of the
characteristics of warhead fragmentation in terms of initial velocities,
spray angles of fragments and fragment mass distribution of high
explosive (HE) warhead. The behavior of warhead fragmentation
depends on shape and size of warhead, thickness of casing, type of
explosive, number and position of detonator, and etc. This paper
focuses on the effects of material properties of warhead casing, i.e.
failure strain, initial yield and ultimate strength on the characteristics
of warhead fragmentation. It was found that initial yield and ultimate
strength of casing has minimal effects on the initial velocities and
spray angles of fragments. Moreover, a brittle warhead casing with
low failure strain tends to produce higher number of fragments with
less average fragment mass.
Abstract: In this article, a high vacuum system for the evaporation of organic semiconductors is introduced and a mathematical model is given. Based on the exact input output linearization a deposition rate controller is designed and tested with different evaporation materials.
Abstract: In present work are considered the scheme of
evaluation the transition probability in quantum system. It is based on
path integral representation of transition probability amplitude and its
evaluation by means of a saddle point method, applied to the part of
integration variables. The whole integration process is reduced to
initial value problem solutions of Hamilton equations with a random
initial phase point. The scheme is related to the semiclassical initial
value representation approaches using great number of trajectories. In
contrast to them from total set of generated phase paths only one path
for each initial coordinate value is selected in Monte Karlo process.
Abstract: Ovshinsky initiated scientific research in the field of
amorphous and disordered materials that continues to this day. The
Ovshinsky Effect where the resistance of thin GST films is
significantly reduced upon the application of low voltage is of
fundamental importance in phase-change - random access memory
(PC-RAM) devices.GST stands for GdSbTe chalcogenide type
glasses.However, the Ovshinsky Effect is not without controversy.
Ovshinsky thought the resistance of GST films is reduced by the
redistribution of charge carriers; whereas, others at that time including
many PC-RAM researchers today argue that the GST resistance
changes because the GST amorphous state is transformed to the
crystalline state by melting, the heat supplied by external heaters. In
this controversy, quantum mechanics (QM) asserts the heat capacity of
GST films vanishes, and therefore melting cannot occur as the heat
supplied cannot be conserved by an increase in GST film
temperature.By precluding melting, QM re-opens the controversy
between the melting and charge carrier mechanisms. Supporting
analysis is presented to show that instead of increasing GST film
temperature, conservation proceeds by the QED induced creation of
photons within the GST film, the QED photons confined by TIR. QED
stands for quantum electrodynamics and TIR for total internal
reflection. The TIR confinement of QED photons is enhanced by the
fact the absorbedheat energy absorbed in the GST film is concentrated
in the TIR mode because of their high surface to volume ratio. The
QED photons having Planck energy beyond the ultraviolet produce
excitons by the photoelectric effect, the electrons and holes of which
reduce the GST film resistance.
Abstract: The presented paper shows the possibility of using
holographic interferometry for measurement of temperature field in
moving fluids. There are a few methods for identification of velocity
fields in fluids, such us LDA, PIV, hot wire anemometry. It is very
difficult to measure the temperature field in moving fluids. One of the
often used methods is Constant Current Anemometry (CCA), which
is a point temperature measurement method. Data are possibly
acquired at frequencies up to 1000Hz. This frequency should be
limiting factor for using of CCA in fluid when fast change of
temperature occurs. This shortcoming of CCA measurements should
be overcome by using of optical methods such as holographic
interferometry. It is necessary to employ a special holographic setup
with double sensitivity instead of the commonly used Mach-Zehnder
type of holographic interferometer in order to attain the parameters
sufficient for the studied case. This setup is not light efficient like the
Mach-Zehnder type but has double sensitivity. The special technique
of acquiring and phase averaging of results from holographic
interferometry is also presented. The results from the holographic
interferometry experiments will be compared with the temperature
field achieved by methods CCA method.