Abstract: Incompressible Navier-Stokes equations are reviewed
in this work. Three-dimensional Navier-Stokes equations are solved
analytically. The Mathematical derivation shows that the solutions
for the zero and constant pressure gradients are similar. Descriptions
of the proposed formulation and validation against two laminar
experiments and three different turbulent flow cases are reported in
this paper. Even though, the analytical solution is derived for nonreacting
flows, it could reproduce trends for cases including
combustion.
Abstract: The shortest path routing problem is a multiobjective
nonlinear optimization problem with constraints. This problem has
been addressed by considering Quality of service parameters, delay
and cost objectives separately or as a weighted sum of both
objectives. Multiobjective evolutionary algorithms can find multiple
pareto-optimal solutions in one single run and this ability makes them
attractive for solving problems with multiple and conflicting
objectives. This paper uses an elitist multiobjective evolutionary
algorithm based on the Non-dominated Sorting Genetic Algorithm
(NSGA), for solving the dynamic shortest path routing problem in
computer networks. A priority-based encoding scheme is proposed
for population initialization. Elitism ensures that the best solution
does not deteriorate in the next generations. Results for a sample test
network have been presented to demonstrate the capabilities of the
proposed approach to generate well-distributed pareto-optimal
solutions of dynamic routing problem in one single run. The results
obtained by NSGA are compared with single objective weighting
factor method for which Genetic Algorithm (GA) was applied.
Abstract: This paper presents a conceptual model of agreement
options for negotiation support in multi-person decision on
optimizing high-rise building columns. The decision is complicated
since many parties involved in choosing a single alternative from a
set of solutions. There are different concern caused by differing
preferences, experiences, and background. Such building columns as
alternatives are referred to as agreement options which are
determined by identifying the possible decision maker group,
followed by determining the optimal solution for each group. The
group in this paper is based on three-decision makers preferences that
are designer, programmer, and construction manager. Decision
techniques applied to determine the relative value of the alternative
solutions for performing the function. Analytical Hierarchy Process
(AHP) was applied for decision process and game theory based agent
system for coalition formation. An n-person cooperative game is
represented by the set of all players. The proposed coalition
formation model enables each agent to select individually its allies or
coalition. It further emphasizes the importance of performance
evaluation in the design process and value-based decision.
Abstract: The paper outlines the drivers behind the movement
from products to solutions in the Hi-Tech Business-to-Business
markets. The paper lists out the challenges in enabling the
transformation from products to solutions and also attempts to explore
strategic and operational recommendations based on the authors-
factual experiences with Japanese Hi-tech manufacturing
organizations. Organizations in the Hi-Tech Business-to-Business
markets are increasingly being compelled to move to a solutions model
from the conventional products model. Despite the added complexity
of solutions, successful technology commercialization can be achieved
by making prudent choices in defining a relevant solutions model, by
backing the solution model through appropriate organizational design,
and by overhauling the new product development process and
supporting infrastructure.
Abstract: Economic dispatch (ED) is considered to be one of the
key functions in electric power system operation. This paper presents
a new hybrid approach based genetic algorithm (GA) to economic
dispatch problems. GA is most commonly used optimizing algorithm
predicated on principal of natural evolution. Utilization of chaotic
queue with GA generates several neighborhoods of near optimal
solutions to keep solution variation. It could avoid the search process
from becoming pre-mature. For the objective of chaotic queue
generation, utilization of tent equation as opposed to logistic equation
results in improvement of iterative speed. The results of the proposed
approach were compared in terms of fuel cost, with existing
differential evolution and other methods in literature.
Abstract: The IDR(s) method based on an extended IDR theorem was proposed by Sonneveld and van Gijzen. The original IDR(s) method has excellent property compared with the conventional iterative methods in terms of efficiency and small amount of memory. IDR(s) method, however, has unexpected property that relative residual 2-norm stagnates at the level of less than 10-12. In this paper, an effective strategy for stagnation detection, stagnation avoidance using adaptively information of parameter s and improvement of convergence rate itself of IDR(s) method are proposed in order to gain high accuracy of the approximated solution of IDR(s) method. Through numerical experiments, effectiveness of adaptive tuning IDR(s) method is verified and demonstrated.
Abstract: The research investigates the effects of super plasticizer and molarity of sodium hydroxide alkaline solution on the workability, microstructure and compressive strength of self compacting geopolymer concrete (SCGC). SCGC is an improved way of concreting execution that does not require compaction and is made by complete elimination of ordinary Portland cement content. The parameters studied were superplasticizer (SP) dosage and molarity of NaOH solution. SCGC were synthesized from low calcium fly ash, activated by combinations of sodium hydroxide and sodium silicate solutions, and by incorporation of superplasticizer for self compactability. The workability properties such as filling ability, passing ability and resistance to segregation were assessed using slump flow, T-50, V-funnel, L-Box and J-ring test methods. It was found that the essential workability requirements for self compactability according to EFNARC were satisfied. Results showed that the workability and compressive strength improved with the increase in superplasticizer dosage. An increase in strength and a decrease in workability of these concrete samples were observed with the increase in molarity of NaOH solution from 8M to 14M. Improvement of interfacial transition zone (ITZ) and micro structure with the increase of SP and increase of concentration from 8M to 12M were also identified.
Abstract: This paper deals with a delayed single population model on time scales. With the assistance of coincidence degree theory, sufficient conditions for existence of periodic solutions are obtained. Furthermore, the better estimations for bounds of periodic solutions are established.
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: Genetic algorithms (GAs) have been widely used for
global optimization problems. The GA performance depends highly
on the choice of the search space for each parameter to be optimized.
Often, this choice is a problem-based experience. The search space
being a set of potential solutions may contain the global optimum
and/or other local optimums. A bad choice of this search space
results in poor solutions. In this paper, our approach consists in
extending the search space boundaries during the GA optimization,
only when it is required. This leads to more diversification of GA
population by new solutions that were not available with fixed search
space boundaries. So, these dynamic search spaces can improve the
GA optimization performances. The proposed approach is applied to
power system stabilizer optimization for multimachine power system
(16-generator and 68-bus). The obtained results are evaluated and
compared with those obtained by ordinary GAs. Eigenvalue analysis
and nonlinear system simulation results show the effectiveness of the
proposed approach to damp out the electromechanical oscillation and
enhance the global system stability.
Abstract: In this paper, a new dependable algorithm based on an adaptation of the standard variational iteration method (VIM) is used for analyzing the transition from steady convection to chaos for lowto-intermediate Rayleigh numbers convection in porous media. The solution trajectories show the transition from steady convection to chaos that occurs at a slightly subcritical value of Rayleigh number, the critical value being associated with the loss of linear stability of the steady convection solution. The VIM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions to the considered model and other dynamical systems. We shall call this technique as the piecewise VIM. Numerical comparisons between the piecewise VIM and the classical fourth-order Runge–Kutta (RK4) numerical solutions reveal that the proposed technique is a promising tool for the nonlinear chaotic and nonchaotic systems.
Abstract: From the beginning of creation, human being has ever
fought against the ecosystem by changes has made in environment.
The most environmental changes on the nature have been done after
starting the concentrated life in the same region. Dams are one of the
most important buildings in water resources and transferring. These
buildings have been made from old times without access to
hydrological, hydraulically, hydro mechanical information. Dams
have positive and negative effects on environment. Constructing a
dam relatively causes equal ecological consequences. According to
different criteria, environmental effects of dams can lead short term
and long term damages. These effects may influence on the situation
and treatment of meteorology, biology, culture, ancient works, etc
and severely causes to change and complicate it. So considering
importance of positive effects of dam construction, it is necessary to
minimize negative environmental effects of dams to achieve a stable
development. In this article the considered effects and their solutions
in influencing on assessment of destructive environmental effects of
dams construction have been surveyed and presented.
Abstract: Multi criteria decision analysis (MDCA) covers both
data and experience. It is very common to solve the problems with
many parameters and uncertainties. GIS supported solutions improve
and speed up the decision process. Weighted grading as a MDCA
method is employed for solving the geotechnical problems. In this
study, geotechnical parameters namely soil type; SPT (N) blow
number, shear wave velocity (Vs) and depth of underground water
level (DUWL) have been engaged in MDCA and GIS. In terms of
geotechnical aspects, the settlement suitability of the municipal area
was analyzed by the method. MDCA results were compatible with
the geotechnical observations and experience. The method can be
employed in geotechnical oriented microzoning studies if the criteria
are well evaluated.
Abstract: Evolvable hardware (EHW) refers to a selfreconfiguration
hardware design, where the configuration is under
the control of an evolutionary algorithm (EA). A lot of research has
been done in this area several different EA have been introduced.
Every time a specific EA is chosen for solving a particular problem,
all its components, such as population size, initialization, selection
mechanism, mutation rate, and genetic operators, should be selected
in order to achieve the best results. In the last three decade a lot of
research has been carried out in order to identify the best parameters
for the EA-s components for different “test-problems". However
different researchers propose different solutions. In this paper the
behaviour of mutation rate on (1+λ) evolution strategy (ES) for
designing logic circuits, which has not been done before, has been
deeply analyzed. The mutation rate for an EHW system modifies
values of the logic cell inputs, the cell type (for example from AND
to NOR) and the circuit output. The behaviour of the mutation has
been analyzed based on the number of generations, genotype
redundancy and number of logic gates used for the evolved circuits.
The experimental results found provide the behaviour of the mutation
rate to be used during evolution for the design and optimization of
logic circuits. The researches on the best mutation rate during the last
40 years are also summarized.
Abstract: In this paper, we have applied the homotopy perturbation
method (HPM) for obtaining the analytical solution of unsteady
flow of gas through a porous medium and we have also compared the
findings of this research with some other analytical results. Results
showed a very good agreement between results of HPM and the
numerical solutions of the problem rather than other analytical solutions
which have previously been applied. The results of homotopy
perturbation method are of high accuracy and the method is very
effective and succinct.
Abstract: Cavitation, usually known as a destructive
phenomenon, involves turbulent unsteady two-phase flow. Having
such features, cavitating flows have been turned to a challenging
topic in numerical studies and many researches are being done for
better understanding of bubbly flows and proposing solutions to
reduce its consequent destructive effects. Aeration may be regarded
as an effective protection against cavitation erosion in many
hydraulic structures, like gated tunnels. The paper concerns
numerical simulation of flow in discharge gated tunnel of a dam
using ing RNG k -ε model coupled with the volume of fluid (VOF)
method and the zone which is susceptible of cavitation inception in
the tunnel is predicted. In the second step, a vent is considered in the
mentioned zone for aeration and the numerical simulation is done
again to study the effects of aeration. The results show that aeration
is an impressively useful method to exclude cavitation in mentioned
tunnels.
Abstract: Fick's second law equations for unsteady state
diffusion of salt into the potato tissues were solved numerically. The
set of equations resulted from implicit modeling were solved using
Thomas method to find the salt concentration profiles in solid phase.
The needed effective diffusivity and equilibrium distribution
coefficient were determined experimentally. Cylindrical samples of
potato were infused with aqueous NaCl solutions of 1-3%
concentrations, and variations in salt concentrations of brine were
determined over time. Solute concentrations profiles of samples were
determined by measuring salt uptake of potato slices. For the studied
conditions, equilibrium distribution coefficients were found to be
dependent on salt concentrations, whereas the effective diffusivity
was slightly affected by brine concentration.
Abstract: Unsteady magnetohydrodynamics (MHD) boundary
layer flow and heat transfer over a continuously stretching surface in
the presence of radiation is examined. By similarity transformation,
the governing partial differential equations are transformed to a set of
ordinary differential equations. Numerical solutions are obtained by
employing the Runge-Kutta-Fehlberg method scheme with shooting
technique in Maple software environment. The effects of
unsteadiness parameter, radiation parameter, magnetic parameter and
Prandtl number on the heat transfer characteristics are obtained and
discussed. It is found that the heat transfer rate at the surface
increases as the Prandtl number and unsteadiness parameter increase
but decreases with magnetic and radiation parameter.
Abstract: In this work, we consider the number of integer solutions
of Diophantine equation D : y2 - 2yx - 3 = 0 over Z and
also over finite fields Fp for primes p ≥ 5. Later we determine the
number of rational points on curves Ep : y2 = Pp(x) = yp
1 + yp
2
over Fp, where y1 and y2 are the roots of D. Also we give a formula
for the sum of x- and y-coordinates of all rational points (x, y) on
Ep over Fp.
Abstract: A method for solving linear and non-linear Goursat
problem is given by using the two-dimensional differential transform
method. The approximate solution of this problem is calculated in
the form of a series with easily computable terms and also the exact
solutions can be achieved by the known forms of the series solutions.
The method can easily be applied to many linear and non-linear
problems and is capable of reducing the size of computational work.
Several examples are given to demonstrate the reliability and the
performance of the presented method.