Abstract: Sample of CsAg2I3 was prepared by solid state reaction. Then, microstructure parameters of this sample have been determined using wide angle X-ray scattering WAXS method. As well as, Cell parameters of crystal structure have been refined using CHEKCELL program. This analysis states that the lattice intrinsic strainof the sample is so small and the crystal size is on the order of 559Å.
Abstract: Samples of CoFe2-xCrxO4 where x varies from 0.0 to 0.5 were prepared by co-precipitation route. These samples were sintered at 750°C for 2 hours. These particles were characterized by X-ray diffraction (XRD) at room temperature. The FCC spinel structure was confirmed by XRD patterns of the samples. The crystallite sizes of these particles were calculated from the most intense peak by Scherrer formula. The crystallite sizes lie in the range of 37-60 nm. The lattice parameter was found decreasing upon substitution of Cr. DC electrical resistivity was measured as a function of temperature. The room temperature thermoelectric power was measured for the prepared samples. The magnitude of Seebeck coefficient depends on the composition and resistivity of the samples.
Abstract: Electrical resistivity is a fundamental parameter of metals or electrical conductors. Since resistivity is a function of temperature, in order to completely understand the behavior of metals, a temperature dependent theoretical model is needed. A model based on physics principles has recently been developed to obtain an equation that relates electrical resistivity to temperature. This equation is dependent upon a parameter associated with the electron travel time before being scattered, and a parameter that relates the energy of the atoms and their separation distance. Analysis of the energy parameter reveals that the equation is optimized if the proportionality term in the equation is not constant but varies over the temperature range. Additional analysis reveals that the theoretical equation can be used to determine the mean free path of conduction electrons, the number of defects in the atomic lattice, and the ‘equivalent’ charge associated with the metallic bonding of the atoms. All of this analysis provides validation for the theoretical model and provides insight into the behavior of metals where performance is affected by temperatures (e.g., integrated circuits and temperature sensors).
Abstract: The notions of I-vague groups with membership and
non-membership functions taking values in an involutary dually
residuated lattice ordered semigroup are introduced which generalize
the notions with truth values in a Boolean algebra as well as those
usual vague sets whose membership and non-membership functions
taking values in the unit interval [0, 1]. Moreover, various operations
and properties are established.
Abstract: We report the results of an lattice Boltzmann
simulation of magnetohydrodynamic damping of sidewall convection
in a rectangular enclosure filled with a porous medium. In particular
we investigate the suppression of convection when a steady magnetic
field is applied in the vertical direction. The left and right vertical
walls of the cavity are kept at constant but different temperatures
while both the top and bottom horizontal walls are insulated. The
effects of the controlling parameters involved in the heat transfer and
hydrodynamic characteristics are studied in detail. The heat and mass
transfer mechanisms and the flow characteristics inside the enclosure
depended strongly on the strength of the magnetic field and Darcy
number. The average Nusselt number decreases with rising values of
the Hartmann number while this increases with increasing values of
the Darcy number.
Abstract: The dynamics of Min proteins plays a center role in
accurate cell division. Although the nucleoids may presumably play
an important role in prokaryotic cell division, there is a lack of
models to account for its participation. In this work, we apply the
lattice Boltzmann method to investigate protein oscillation based on a
mesoscopic model that takes into account the nucleoid-s role. We
found that our numerical results are in reasonably good agreement
with the previous experimental results On comparing with the other
computational models without the presence of nucleoids, the
highlight of our finding is that the local densities of MinD and MinE
on the cytoplasmic membrane increases, especially along the cell
width, when the size of the obstacle increases, leading to a more
distinct cap-like structure at the poles. This feature indicated the
realistic pattern and reflected the combination of Min protein
dynamics and nucleoid-s role.
Abstract: In this paper we consider the problem of change
detection and non stationary signals tracking. Using parametric
estimation of signals based on least square lattice adaptive filters we
consider for change detection statistical parametric methods using
likelihood ratio and hypothesis tests. In order to track signals
dynamics, we introduce a compensation procedure in the adaptive
estimation. This will improve the adaptive estimation performances
and fasten it-s convergence after changes detection.
Abstract: In this study, a minimal submaximal element of LIT(X) (the lattice of all intuitionistic topologies for X, ordered by inclusion) is determined. Afterwards, a new contractive property, intuitionistic mega-connectedness, is defined. We show that the submaximality and mega-connectedness are not complementary intuitionistic topological invariants by identifying those members of LIT(X) which are intuitionistic mega-connected.
Abstract: We study a long-range percolation model in the hierarchical
lattice ΩN of order N where probability of connection between
two nodes separated by distance k is of the form min{αβ−k, 1},
α ≥ 0 and β > 0. The parameter α is the percolation parameter,
while β describes the long-range nature of the model. The ΩN is
an example of so called ultrametric space, which has remarkable
qualitative difference between Euclidean-type lattices. In this paper,
we characterize the sizes of large clusters for this model along the
line of some prior work. The proof involves a stationary embedding
of ΩN into Z. The phase diagram of this long-range percolation is
well understood.
Abstract: This paper proposes an efficient lattice-reduction-aided
detection (LRD) scheme to improve the detection performance of
MIMO-OFDM system. In this proposed scheme, V candidate symbols
are considered at the first layer, and V probable streams are
detected with LRD scheme according to the first detected V candidate
symbols. Then, the most probable stream is selected through a ML
test. Since the proposed scheme can more accurately detect initial
symbol and can reduce transmission of error to rest symbols, the
proposed scheme shows more improved performance than conventional
LRD with very low complexity.
Abstract: A zero-field ferromagnetic Ising model is utilized to
simulate the propagation of infection in a population that assumes a
square lattice structure. The rate of infection increases with
temperature. The disease spreads faster among individuals with low J
values. Such effect, however, diminishes at higher temperatures.
Abstract: In this paper, Lattice Boltzmann Method (LBM) is used to study laminar flow with mixed convection heat transfer inside a two-dimensional inclined lid-driven rectangular cavity with aspect ratio AR = 3. Bottom wall of the cavity is maintained at lower temperature than the top lid, and its vertical walls are assumed insulated. Top lid motion results in fluid motion inside the cavity. Inclination of the cavity causes horizontal and vertical components of velocity to be affected by buoyancy force. To include this effect, calculation procedure of macroscopic properties by LBM is changed and collision term of Boltzmann equation is modified. A computer program is developed to simulate this problem using BGK model of lattice Boltzmann method. The effects of the variations of Richardson number and inclination angle on the thermal and flow behavior of the fluid inside the cavity are investigated. The results are presented as velocity and temperature profiles, stream function contours and isotherms. It is concluded that LBM has good potential to simulate mixed convection heat transfer problems.
Abstract: Simultaneous transient conduction and radiation heat
transfer with heat generation is investigated. Analysis is carried out
for both steady and unsteady situations. two-dimensional gray
cylindrical enclosure with an absorbing, emitting, and isotropically
scattering medium is considered. Enclosure boundaries are assumed
at specified temperatures. The heat generation rate is considered
uniform and constant throughout the medium. The lattice Boltzmann
method (LBM) was used to solve the energy equation of a transient
conduction-radiation heat transfer problem. The control volume finite
element method (CVFEM) was used to compute the radiative
information. To study the compatibility of the LBM for the energy
equation and the CVFEM for the radiative transfer equation, transient
conduction and radiation heat transfer problems in 2-D cylindrical
geometries were considered. In order to establish the suitability of the
LBM, the energy equation of the present problem was also solved
using the the finite difference method (FDM) of the computational
fluid dynamics. The CVFEM used in the radiative heat transfer was
employed to compute the radiative information required for the
solution of the energy equation using the LBM or the FDM (of the
CFD). To study the compatibility and suitability of the LBM for the
solution of energy equation and the CVFEM for the radiative
information, results were analyzed for the effects of various
parameters such as the boundary emissivity. The results of the LBMCVFEM
combination were found to be in excellent agreement with
the FDM-CVFEM combination. The number of iterations and the
steady state temperature in both of the combinations were found
comparable. Results are found for situations with and without heat
generation. Heat generation is found to have significant bearing on
temperature distribution.
Abstract: In this paper we report the technique of optical
induction of 2 and 3-dimensional (2D and 3D) photonic lattices in
photorefractive materials based on diffraction grating self replication
-Talbot effect. 1D and 2D different rotational symmery diffraction
masks with the periods of few tens micrometers and 532 nm cw laser
beam were used in the experiments to form an intensity modulated
light beam profile. A few hundred micrometric scale replications of
mask generated intensity structures along the beam propagation axis
were observed. Up to 20 high contrast replications were detected for
1D annular mask with 30
Abstract: In pressure vessels contain hydrogen, the role of
hydrogen will be important because of hydrogen cracking problem. It
is difficult to predict what is happened in metallurgical field spite of a
lot of studies have been searched. The main role in controlling the
mass diffusion as driving force is related to stress. In this study, finite
element analysis is implemented to estimate material-s behavior
associated with hydrogen embrittlement. For this purpose, one model
of a pressure vessel is introduced that it has definite boundary and
initial conditions. In fact, finite element is employed to solve the
sequentially coupled mass diffusion with stress near a crack front in a
pressure vessel. Modeling simulation intergrarnular fracture of AISI
4135 steel due to hydrogen is investigated. So, distribution of
hydrogen and stress are obtained and they indicate that their
maximum amounts occur near the crack front. This phenomenon is
happened exactly the region between elastic and plastic field.
Therefore, hydrogen is highly mobile and can diffuse through crystal
lattice so that this zone is potential to trap high volume of hydrogen.
Consequently, crack growth and fast fracture will be happened.
Abstract: Recently, nanomaterials are developed in the form of nano-films, nano-crystals and nano-pores. Lanthanide phosphates as a material find extensive application as laser, ceramic, sensor, phosphor, and also in optoelectronics, medical and biological labels, solar cells and light sources. Among the different kinds of rare-earth orthophosphates, yttrium orthophosphate has been shown to be an efficient host lattice for rare earth activator ions, which have become a research focus because of their important role in the field of light display systems, lasers, and optoelectronic devices. It is in this context that the 4fn- « 4fn-1 5d transitions of rare earth in insulating materials, lying in the UV and VUV, are the aim of large number of studies .Though there has been a few reports on Eu3+, Nd3+, Pr3+,Er3+, Ce3+, Tm3+ doped YPO4. The 4fn- « 4fn-1 5d transitions of the rare earth dependent to the host-matrix, several matrices ions were used to study these transitions, in this work we are suggesting to study on a very specific class of inorganic material that are orthophosphate doped with rare earth ions. This study focused on the effect of Ce3+ concentration on the structural and optical properties of Ce3+ doped YPO4 yttrium orthophosphate with powder form prepared by the Sol Gel method.
Abstract: The square-lattice Ising model is the simplest system
showing phase transitions (the transition between the paramagnetic
phase and the ferromagnetic phase and the transition between the
paramagnetic phase and the antiferromagnetic phase) and critical
phenomena at finite temperatures. The exact solution of the squarelattice
Ising model with free boundary conditions is not known for
systems of arbitrary size. For the first time, the exact solution of
the Ising model on the square lattice with free boundary
conditions is obtained after classifying all )
spin configurations with the microcanonical transfer matrix. Also, the
phase transitions and critical phenomena of the square-lattice Ising
model are discussed using the exact solution on the square
lattice with free boundary conditions.
Abstract: Semiconductor materials with coatings have a wide range of applications in MEMS and NEMS. This work uses transfermatrix method for calculating the radiative properties. Dopped silicon is used and the coherent formulation is applied. The Drude model for the optical constants of doped silicon is employed. Results showed that for the visible wavelengths, more emittance occurs in greater concentrations and the reflectance decreases as the concentration increases. In these wavelengths, transmittance is negligible. Donars and acceptors act similar in visible wavelengths. The effect of wave interference can be understood by plotting the spectral properties such as reflectance or transmittance of a thin dielectric film versus the film thickness and analyzing the oscillations of properties due to constructive and destructive interferences. But this effect has not been shown at visible wavelengths. At room temperature, the scattering process is dominated by lattice scattering for lightly doped silicon, and the impurity scattering becomes important for heavily doped silicon when the dopant concentration exceeds1018cm-3 .
Abstract: Whereas in the third generation nuclear reactors,
dimensions of core and also the kind of coolant and enrichment
percent of fuel have significantly changed than the second
generation, therefore in this article the aim is based on a
comparative investigation between two same power reactors of
second and third generations, that the neutronic parameters of both
reactors such as: K∞, Keff and its details and thermal hydraulic
parameters such as: power density, specific power, volumetric heat
rate, released power per fuel volume unit, volume and mass of clad
and fuel (consisting fissile and fertile fuels), be calculated and
compared together. By this comparing the efficiency and
modification of third generation nuclear reactors than second
generation which have same power can be distinguished.
In order to calculate the cited parameters, some information
such as: core dimensions, the pitch of lattice, the fuel matter, the
percent of enrichment and the kind of coolant are used. For
calculating the neutronic parameters, a neutronic program entitled:
SIXFAC and also related formulas have been used. Meantime for
calculating the thermal hydraulic and other parameters, analytical
method and related formulas have been applied.
Abstract: The increasing importance of data stream arising in a
wide range of advanced applications has led to the extensive study of
mining frequent patterns. Mining data streams poses many new
challenges amongst which are the one-scan nature, the unbounded
memory requirement and the high arrival rate of data streams. In this
paper, we propose a new approach for mining itemsets on data
stream. Our approach SFIDS has been developed based on FIDS
algorithm. The main attempts were to keep some advantages of the
previous approach and resolve some of its drawbacks, and
consequently to improve run time and memory consumption. Our
approach has the following advantages: using a data structure similar
to lattice for keeping frequent itemsets, separating regions from each
other with deleting common nodes that results in a decrease in search
space, memory consumption and run time; and Finally, considering
CPU constraint, with increasing arrival rate of data that result in
overloading system, SFIDS automatically detect this situation and
discard some of unprocessing data. We guarantee that error of results
is bounded to user pre-specified threshold, based on a probability
technique. Final results show that SFIDS algorithm could attain
about 50% run time improvement than FIDS approach.