Mathematical, Computational, Physical, Electrical and Computer Engineering

Commenced in January 1999 | Frequency: Monthly | Edition: International | Paper Count: 30 |

30

696

Contributions to Differential Geometry of Pseudo Null Curves in Semi-Euclidean Space

In this paper, first, a characterization of spherical
Pseudo null curves in Semi-Euclidean space is given. Then, to
investigate position vector of a pseudo null curve, a system of
differential equation whose solution gives the components of the
position vector of a pseudo null curve on the Frenet axis is
established by means of Frenet equations. Additionally, in view of
some special solutions of mentioned system, characterizations of
some special pseudo null curves are presented.

29

746

Role of Acoustic Pressure on the Dynamics of Moving Single-Bubble Sonoluminescence

Role of acoustic driving pressure on the
translational-radial dynamics of a moving single bubble
sonoluminescence (m-SBSL) has been numerically
investigated. The results indicate that increase in the
amplitude of the driving pressure leads to increase in the
bubble peak temperature. The length and the shape of the
trajectory of the bubble depends on the acoustic pressure and
because of the spatially dependence of the radial dynamics of
the moving bubble, its peak temperature varies during the
acoustical pulses. The results are in good agreement with the
experimental reports on m-SBSL.

28

777

Certain Subordination Results For A Class Of Analytic Functions Defined By The Generalized Integral Operator

We obtain several interesting subordination results for
a class of analytic functions defined by using a generalized integral operator.

27

1544

Some Characterizations of Isotropic Curves In the Euclidean Space

The curves, of which the square of the distance
between the two points equal to zero, are called minimal or isotropic
curves [4]. In this work, first, necessary and sufficient conditions to
be a Pseudo Helix, which is a special case of such curves, are
presented. Thereafter, it is proven that an isotropic curve-s position
vector and pseudo curvature satisfy a vector differential equation of
fourth order. Additionally, In view of solution of mentioned
equation, position vector of pseudo helices is obtained.

26

1676

Rheodynamic Lubrication of a Rectangular Squeeze Film Bearing with an Exponential Curvature Variation using Bingham Lubricants

The present work deals with analyses of the effects
of bearing curvature and non-Newtonian characteristics on the load capacity of an exponential rectangular squeeze film bearing using
Bingham fluids as lubricants. Bingham fluids are characterized by an
yield value and hence the formation of a “rigid" core in the region
between the plates is justified. The flow is confined to the region
between the core and the plates. The shape of the core has been
identified through numerical means. Further, numerical solutions for
the pressure distribution and load carrying capacity of the bearing
for various values of Bingham number and curvature parameter have
been obtained. The effects of bearing curvature and non-Newtonian
characteristics of the lubricant on the bearing performances have been
discussed.

25

2322

Periodicity for a Food Chain Model with Functional Responses on Time Scales

With the help of coincidence degree theory, sufficient
conditions for existence of periodic solutions for a food chain model
with functional responses on time scales are established.

24

2796

Increase in Solar Thermal Energy Storage by using a Hybrid Energy Storage System

The intermittent nature of solar energy and the energy
requirements of buildings necessitate the storage of thermal energy.
In this paper a hybrid system of storing solar energy has been
analyzed. Adding a LHS medium to a commercial solar water heater,
the required energy for heating a small room was obtained in
addition to preparing hot water. In other words, the suggested hybrid
storage system consists of two tanks: a water tank as a SHS medium;
and a paraffin tank as a LHS medium. A computing program was
used to find the optimized time schedule of charging the storage
tanks during each day, according to the solar radiation conditions.
The results show that the use of such system can improve the
capability of energy gathering comparing to the individual water
storage tank during the cold months of the year. Of course, because
of the solar radiation angles and shorten daylight in December &
January, the performance will be the same as the simple solar water
heaters (in the northern hemisphere). But the extra energy stored in
November, February, March & April, can be useful for heating a
small room for 3 hours during the cold days.

23

3193

N-Sun Decomposition of Complete, Complete Bipartite and Some Harary Graphs

Graph decompositions are vital in the study of
combinatorial design theory. A decomposition of a graph G is a
partition of its edge set. An n-sun graph is a cycle Cn with an edge
terminating in a vertex of degree one attached to each vertex. In this
paper, we define n-sun decomposition of some even order graphs
with a perfect matching. We have proved that the complete graph
K2n, complete bipartite graph K2n, 2n and the Harary graph H4, 2n have
n-sun decompositions. A labeling scheme is used to construct the n-suns.

22

3292

A Global Condition for the Triviality of an Almost Split Quaternionic Structure on Split Complex Manifolds

Let M be an almost split quaternionic manifold on
which its almost split quaternionic structure is defined by a three
dimensional subbundle V of ( T M) T (M)
*
Ôèù and
{F,G,H} be a local basis for V . Suppose that the (global)
(1, 2) tensor field defined[V ,V ]is defined by
[V,V ] = [F,F]+[G,G] + [H,H], where [,] denotes
the Nijenhuis bracket. In ref. [7], for the almost split-hypercomplex
structureH = J α,α =1,2,3, and the Obata
connection ÔêçH
vanishes if and only if H is split-hypercomplex.
In this study, we give a prof, in particular, prove that if either
M is a split quaternionic Kaehler manifold, or if M is a splitcomplex
manifold with almost split-complex structure F , then the
vanishing [V ,V ] is equivalent to that of all the Nijenhuis brackets
of {F,G,H}. It follows that the bundle V is trivial if and only if
[V ,V ] = 0 .

21

3830

Flow Acoustics in Solid-Fluid Structures

The governing two-dimensional equations of a heterogeneous material composed of a fluid (allowed to flow in the absence of acoustic excitations) and a crystalline piezoelectric cubic solid stacked one-dimensionally (along the z direction) are derived and special emphasis is given to the discussion of acoustic group velocity for the structure as a function of the wavenumber component perpendicular to the stacking direction (being the x axis). Variations in physical parameters with y are neglected assuming infinite material homogeneity along the y direction and the flow velocity is assumed to be directed along the x direction. In the first part of the paper, the governing set of differential equations are derived as well as the imposed boundary conditions. Solutions are provided using Hamilton-s equations for the wavenumber vs. frequency as a function of the number and thickness of solid layers and fluid layers in cases with and without flow (also the case of a position-dependent flow in the fluid layer is considered). In the first part of the paper, emphasis is given to the small-frequency case. Boundary conditions at the bottom and top parts of the full structure are left unspecified in the general solution but examples are provided for the case where these are subject to rigid-wall conditions (Neumann boundary conditions in the acoustic pressure). In the second part of the paper, emphasis is given to the general case of larger frequencies and wavenumber-frequency bandstructure formation. A wavenumber condition for an arbitrary set of consecutive solid and fluid layers, involving four propagating waves in each solid region, is obtained again using the monodromy matrix method. Case examples are finally discussed.

20

3890

A Hyperbolic Characterization of Projective Klingenberg Planes

In this paper, the notion of Hyperbolic Klingenberg
plane is introduced via a set of axioms like as Affine Klingenberg
planes and Projective Klingenberg planes. Models of such planes are
constructed by deleting a certain number m of equivalence classes
of lines from a Projective Klingenberg plane. In the finite case, an
upper bound for m is established and some combinatoric properties
are investigated.

19

4112

Numerical Simulation of Inviscid Transient Flows in Shock Tube and its Validations

The aim of this paper is to develop a new two dimensional time accurate Euler solver for shock tube applications. The solver was developed to study the performance of a newly built short-duration hypersonic test facility at Universiti Tenaga Nasional “UNITEN" in Malaysia. The facility has been designed, built, and commissioned for different values of diaphragm pressure ratios in order to get wide range of Mach number. The developed solver uses second order accurate cell-vertex finite volume spatial discretization and forth order accurate Runge-Kutta temporal integration and it is designed to simulate the flow process for similar driver/driven gases (e.g. air-air as working fluids). The solver is validated against analytical solution and experimental measurements in the high speed flow test facility. Further investigations were made on the flow process inside the shock tube by using the solver. The shock wave motion, reflection and interaction were investigated and their influence on the performance of the shock tube was determined. The results provide very good estimates for both shock speed and shock pressure obtained after diaphragm rupture. Also detailed information on the gasdynamic processes over the full length of the facility is available. The agreements obtained have been reasonable.

18

4404

A Reproduction of Boundary Conditions in Three-Dimensional Continuous Casting Problem

The paper discusses a 3D numerical solution of the inverse boundary problem for a continuous casting process of alloy. The main goal of the analysis presented within the paper was to estimate heat fluxes along the external surface of the ingot. The verified information on these fluxes was crucial for a good design of a mould, effective cooling system and generally the whole caster. In the study an enthalpy-porosity technique implemented in Fluent package was used for modeling the solidification process. In this method, the phase change interface was determined on the basis of the liquid fraction approach. In inverse procedure the sensitivity analysis was applied for retrieving boundary conditions. A comparison of the measured and retrieved values showed a high accuracy of the computations. Additionally, the influence of the accuracy of measurements on the estimated heat fluxes was also investigated.

17

4739

Exact Solution of Some Helical Flows of Newtonian Fluids

This paper deals with the helical flow of a Newtonian
fluid in an infinite circular cylinder, due to both longitudinal and
rotational shear stress. The velocity field and the resulting shear
stress are determined by means of the Laplace and finite Hankel
transforms and satisfy all imposed initial and boundary conditions.
For large times, these solutions reduce to the well-known steady-state
solutions.

16

5692

On Suborbital Graphs of the Congruence Subgroup r 0(N)

In this paper we examine some properties of suborbital graphs for the congruence subgroup r 0 (N) . Then we give necessary and sufficient conditions for graphs to have triangels.

15

6047

Trace Emergence of Ants- Traffic Flow, based upon Exclusion Process

Biological evolution has generated a rich variety of
successful solutions; from nature, optimized strategies can be
inspired. One interesting example is the ant colonies, which are able
to exhibit a collective intelligence, still that their dynamic is simple.
The emergence of different patterns depends on the pheromone trail,
leaved by the foragers. It serves as positive feedback mechanism for
sharing information.
In this paper, we use the dynamic of TASEP as a model of
interaction at a low level of the collective environment in the ant-s
traffic flow. This work consists of modifying the movement rules of
particles “ants" belonging to the TASEP model, so that it adopts with
the natural movement of ants. Therefore, as to respect the constraints
of having no more than one particle per a given site, and in order to
avoid collision within a bidirectional circulation, we suggested two
strategies: decease strategy and waiting strategy. As a third work
stage, this is devoted to the study of these two proposed strategies-
stability. As a final work stage, we applied the first strategy to the
whole environment, in order to get to the emergence of traffic flow,
which is a way of learning.

14

6260

Hydrodynamic Force on Acoustically Driven Bubble in Sulfuric Acid

Using a force balanced translational-radial dynamics,
phase space of the moving single bubble sonoluminescence (m-
SBSL) in 85% wt sulfuric acid has been numerically calculated. This
phase space is compared with that of single bubble sonoluminescence
(SBSL) in pure water which has been calculated by using the mere
radial dynamics. It is shown that in 85% wt sulfuric acid, in a general
agreement with experiment, the bubble-s positional instability
threshold lays under the shape instability threshold. At the onset of
spatial instability of moving sonoluminescing (SL) bubble in 85%
wt sulfuric acid, temporal effects of the hydrodynamic force on the
bubble translational-radial dynamics have been investigated. The
appearance of non-zero history force on the moving SL bubble is
because of proper condition which was produced by high viscosity of
acid. Around the moving bubble collapse due to the rapid contraction
of the bubble wall, the inertial based added mass force overcomes the
viscous based history force and induces acceleration on the bubble
translational motion.

13

7073

The Pell Equation x2 − (k2 − k)y2 = 2t

Let k, t, d be arbitrary integers with k ≥ 2, t ≥ 0 and
d = k2 - k. In the first section we give some preliminaries from
Pell equations x2 - dy2 = 1 and x2 - dy2 = N, where N be any
fixed positive integer. In the second section, we consider the integer
solutions of Pell equations x2 - dy2 = 1 and x2 - dy2 = 2t. We
give a method for the solutions of these equations. Further we derive
recurrence relations on the solutions of these equations

12

8086

A New Condition for Conflicting Bifuzzy Sets Based On Intuitionistic Evaluation

Fuzzy sets theory affirmed that the linguistic value for
every contraries relation is complementary. It was stressed in the
intuitionistic fuzzy sets (IFS) that the conditions for contraries
relations, which are the fuzzy values, cannot be greater than one.
However, complementary in two contradict phenomena are not
always true. This paper proposes a new idea condition for conflicting
bifuzzy sets by relaxing the condition of intuitionistic fuzzy sets.
Here, we will critically forward examples using triangular fuzzy
number in formulating a new condition for conflicting bifuzzy sets
(CBFS). Evaluation of positive and negative in conflicting
phenomena were calculated concurrently by relaxing the condition in
IFS. The hypothetical illustration showed the applicability of the new
condition in CBFS for solving non-complement contraries
intuitionistic evaluation. This approach can be applied to any
decision making where conflicting is very much exist.

11

9094

Convective Heat Transfer Enhancement in an Enclosure with Fin Utilizing Nano Fluids

The objective of the present work is to conduct
investigations leading to a more complete explanation of single phase
natural convective heat transfer in an enclosure with fin utilizing
nano fluids. The nano fluid used, which is composed of Aluminum
oxide nano particles in suspension of Ethylene glycol, is provided at
various volume fractions. The study is carried out numerically for a
range of Rayleigh numbers, fin heights and aspect ratio. The flow and
temperature distributions are taken to be two-dimensional. Regions
with the same velocity and temperature distributions are identified as
symmetry of sections. One half of such a rectangular region is chosen
as the computational domain taking into account the symmetry about
the fin. Transport equations are modeled by a stream functionvorticity
formulation and are solved numerically by finite-difference
schemes. Comparisons with previously published works on the basis
of special cases are done. Results are presented in the form of
streamline, vector and isotherm plots as well as the variation of local
Nusselt number along the fin under different conditions.

10

11125

On Generalizing Rough Set Theory via using a Filter

The theory of rough sets is generalized by using a
filter. The filter is induced by binary relations and it is used to
generalize the basic rough set concepts. The knowledge
representations and processing of binary relations in the style of
rough set theory are investigated.

9

12784

The Number of Rational Points on Elliptic Curves and Circles over Finite Fields

In elliptic curve theory, number of rational points on
elliptic curves and determination of these points is a fairly important
problem. Let p be a prime and Fp be a finite field and k ∈ Fp. It
is well known that which points the curve y2 = x3 + kx has and
the number of rational points of on Fp. Consider the circle family
x2 + y2 = r2. It can be interesting to determine common points of
these two curve families and to find the number of these common
points. In this work we study this problem.

8

12984

A Method to Calculate Frenet Apparatus of the Curves in Euclidean-5 Space

In this paper, a method to calculate Frenet Apparatus
of the curves in five dimensional Euclidean space is presented.

7

13395

Solving Fully Fuzzy Linear Systems by use of a Certain Decomposition of the Coefficient Matrix

In this paper, we give a certain decomposition of the
coefficient matrix of the fully fuzzy linear system (FFLS) to obtain
a simple algorithm for solving these systems. The new algorithm
can solve FFLS in a smaller computing process. We will illustrate
our method by solving some examples.

6

13579

New Classes of Salagean type Meromorphic Harmonic Functions

In this paper, a necessary and sufficient coefficient are given for functions in a class of complex valued meromorphic harmonic univalent functions of the form f = h + g using Salagean operator. Furthermore, distortion theorems, extreme points, convolution condition and convex combinations for this family of meromorphic harmonic functions are obtained.

5

14409

Fuzzy Ideals in Near-subtraction Semigroups

In this paper,we introduce a notion of fuzzy ideals in near-subtraction semigroups and study their related properties.

4

14954

The Proof of Two Conjectures Related to Pell-s Equation x2 −Dy2 = ± 4

Let D ≠ 1 be a positive non-square integer. In this
paper are given the proofs for two conjectures related to Pell-s
equation x2 -Dy2 = ± 4, proposed by A. Tekcan.

3

15254

Computational Simulation of Imploding Current Sheath Trajectory at the Radial Phase of Plasma Focus Performance

When the shock front (SF) hits the central electrode
axis of plasma focus device, a reflected shock wave moves radially
outwards. The current sheath (CS) results from ionization of filled
gas between two electrodes continues to compress inwards until it
hits the out-going reflected shock front. In this paper the Lagrangian
equations are solved for a parabolic shock trajectory yielding a first
and second approximation for the CS path. To determine the
accuracy of the approximation, the same problem is solved for a
straight shock.

2

15309

Public Key Cryptosystem based on Number Theoretic Transforms

In this paper a Public Key Cryptosystem is proposed
using the number theoretic transforms (NTT) over a ring of integer
modulo a composite number. The key agreement is similar to
ElGamal public key algorithm. The security of the system is based on
solution of multivariate linear congruence equations and discrete
logarithm problem. In the proposed cryptosystem only fixed numbers
of multiplications are carried out (constant complexity) and hence the
encryption and decryption can be done easily. At the same time, it is
very difficult to attack the cryptosystem, since the cipher text is a
sequence of integers which are interrelated. The system provides
authentication also. Using Mathematica version 5.0 the proposed
algorithm is justified with a numerical example.

1

15984

Regularization of the Trajectories of Dynamical Systems by Adjusting Parameters

A gradient learning method to regulate the trajectories
of some nonlinear chaotic systems is proposed. The method is
motivated by the gradient descent learning algorithms for neural
networks. It is based on two systems: dynamic optimization system
and system for finding sensitivities. Numerical results of several
examples are presented, which convincingly illustrate the efficiency
of the method.