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Full-Text Articles in Physical Sciences and Mathematics

A Decomposition Method For Solving Unsteady Convection-Diffusion Problems, Shaher Momani Jan 2008

A Decomposition Method For Solving Unsteady Convection-Diffusion Problems, Shaher Momani

Turkish Journal of Mathematics

In this study, a decomposition method for approximating the solutions of unsteady convection-diffusion problems is implemented. The approximate solution is calculated in the form of a convergent series with easily computable components. The calculations are accelerated by using the noise terms phenomenon for nonhomogeneous problems. Numerical examples are investigated to illustrate the pertinent features of the proposed algorithm.


Mirror Principle For Flag Manifolds, Vehbi̇ Emrah Paksoy Jan 2008

Mirror Principle For Flag Manifolds, Vehbi̇ Emrah Paksoy

Turkish Journal of Mathematics

In this paper, using mirror principle developped by Lian, Liu and Yau [8, 9, 10, 11, 12, 13] we obtained the A and B series for the equivariant tangent bundles over homogenous spaces using Chern polynomial. This is necessary to obtain related cohomology valued series for given arbitrary vector bundle and multiplicative characteristic class. Moreover, this can be used as a valuable testing ground for the theories which associates quantum cohomologies and J functions of non-abelian quotient to abelian quotients via quantization.


Basic Properties And Multipliers Space On L^{1}(G)\Cap L(P,Q)(G) Spaces, İlker Eryilmaz, Cenap Duyar Jan 2008

Basic Properties And Multipliers Space On L^{1}(G)\Cap L(P,Q)(G) Spaces, İlker Eryilmaz, Cenap Duyar

Turkish Journal of Mathematics

Let G be locally compact Abelian group with Haar measure. First is discussed some properties of L^{1}(G) \cap L(p,q)(G) spaces. Then is mentioned the multipliers space on L^{1}(G) \cap L(p,q) (G) spaces.


On Certain Type Of Modular Sequence Spaces, Manjul Gupta, Shesadev Pradhan Jan 2008

On Certain Type Of Modular Sequence Spaces, Manjul Gupta, Shesadev Pradhan

Turkish Journal of Mathematics

In this paper we consider a particular type of modular sequence spaces defined with the help of a given sequence \alpha = {\alpha_n} of strictly positive real numbers \alpha_n's and an Orlicz function M. Indeed, if we define M_n(x) = M(\alpha_nx) and \tildeM_n(x)=M(x/\alpha_n), x\in[0, \infty), we consider the modular sequence spaces l{M_n} and l{\tildeM_n}, denoted by l_M^{\alpha} and l_{\alpha}^M respectively. These are known to be BK-spaces and if M satisfies \Delta_2-condition, they are AK-spaces as well. However, if we consider the spaces l_{\alpha}^M and l_n^{\alpha} corresponding to two complementary Orlicz functions M and N satisfying \Delta_2-condition, they are perfect sequence …


Certain Rings Whose Simple Singular Modules Are Nil-Injective, Junchao Wei Jan 2008

Certain Rings Whose Simple Singular Modules Are Nil-Injective, Junchao Wei

Turkish Journal of Mathematics

In this paper, we first study some characterizations of left min-abel ring, strongly left min-abel ring and left MC2 ring. Next, we discuss and generalize some well known results for a ring whose simple singular left modules are nil- injective. Finally, as a byproduct of these results we are able to show that if R is a left GMC2 left Goldie ring whose every simple singular left R - module is YJ- injective, then R is a finite product of simple left Goldie ring.


On Non-Existence Of Lightlike Hypersurfaces Of Indefinite Kenmotsu Space Form, Nesi̇p Aktan Jan 2008

On Non-Existence Of Lightlike Hypersurfaces Of Indefinite Kenmotsu Space Form, Nesi̇p Aktan

Turkish Journal of Mathematics

In this paper, lightlike hypersurfaces of indefinite Kenmotsu space form are studied. Some characterizations of non-existence of lightlike hypersurfaces of indefinite Kenmotsu space form are given.


Real Gromov-Witten Invariants On The Moduli Space Of Genus 0 Stable Maps To A Smooth Rational Projective Space, Seongchun Kwon Jan 2008

Real Gromov-Witten Invariants On The Moduli Space Of Genus 0 Stable Maps To A Smooth Rational Projective Space, Seongchun Kwon

Turkish Journal of Mathematics

We characterize transversality, non-transversality properties on the moduli space of genus 0 stable maps to a rational projective surface. If a target space is equipped with a real structure, i.e, anti-holomorphic involution, then the results have real enumerative applications. Firstly, we can define a real version of Gromov-Witten invariants. Secondly, we can prove the invariance of Welschinger's invariant in algebraic geometric category.


Proximinality In L^1(I,X), Sharifa Al-Sharif, R. Khalil Jan 2008

Proximinality In L^1(I,X), Sharifa Al-Sharif, R. Khalil

Turkish Journal of Mathematics

Let X be a Banach space and let (I,\Omega ,\mu) be a measure space. For 1 \leq p < \infty, let L^p(I,X) denote the space of Bochner p-integrable functions defined on I with values in X. The object of this paper is to give sufficient conditions for the proximinality of L^1(I,H)+L^1(I,G) in L^1(I,X), where H and G are two proximinal subspaces of X which include as a special case the proximality of L^1(I) \stackrel{\wedge}{\otimes} G + H \stackrel{\wedge}{\otimes} L^1(I) in L^1(I \times I).


A Condition For Warped Product Semi-Invariant Submanifolds To Be Riemannian Product Semi-Invariant Submanifolds In Locally Riemannian Product Manifolds, Mehmet Atçeken Jan 2008

A Condition For Warped Product Semi-Invariant Submanifolds To Be Riemannian Product Semi-Invariant Submanifolds In Locally Riemannian Product Manifolds, Mehmet Atçeken

Turkish Journal of Mathematics

In this article, we give a necessary and sufficient condition for warped product semi-invariant submanifolds to be Riemannian product semi-invariant submanifolds in a locally Riemannian product manifold whose factor manifolds are real space form.


Rickart-Type Annihilator Conditions On Formal Power Series, Ebrahim Hashemi Jan 2008

Rickart-Type Annihilator Conditions On Formal Power Series, Ebrahim Hashemi

Turkish Journal of Mathematics

Let R be an \alpha-rigid ring and R_0[[x;\alpha]] be the nearring of a formal skew power series in which addition and substitution are used as operations. It is shown that R is Rickart and any countable family of idempotents of R has a join in I(R) if and only if R_0[[x;\alpha]]\in R_{r1} if and only if R_0[[x;\alpha]]\in R_{\ell 1} if and only if R_0[[x;\alpha]]\in qR_{r2}. An example to show that, \alpha-rigid condition on R is not superfluous, is provided.


My Collaboration With Raj Mittra: Contributions To The Theory Of Perfectly Matched Layers, Mustafa Kuzuoğlu Jan 2008

My Collaboration With Raj Mittra: Contributions To The Theory Of Perfectly Matched Layers, Mustafa Kuzuoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

No abstract provided.


From Engineering Electromagnetics To Electromagnetic Engineering: Using Computational Electromagnetics For Synthesis Problems, Anton G. Tijhuis, Martijn C. Van Beurden, Bastiaan P. De Hon, Hubregt J. Visser Jan 2008

From Engineering Electromagnetics To Electromagnetic Engineering: Using Computational Electromagnetics For Synthesis Problems, Anton G. Tijhuis, Martijn C. Van Beurden, Bastiaan P. De Hon, Hubregt J. Visser

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a two-stage approach is proposed for using computational electromagnetics in antenna engineering. First, stochastic optimization techniques are used in combination with approximate models. Second, line-search techniques are combined with full-wave modeling. For the first stage, we show an illustrative example. The second stage is considered in detail; both the acceleration of the underlying field computations and the implementation of the optimization are discussed.


The Characteristic Basis Function Method (Cbfm): A Numerically Efficient Strategy For Solving Large Electromagnetic Scattering Problems, Eugenio Lucente, Gianluigi Tiberi, Agostino Monorchio, Giuliano Manara, Raj Mittra Jan 2008

The Characteristic Basis Function Method (Cbfm): A Numerically Efficient Strategy For Solving Large Electromagnetic Scattering Problems, Eugenio Lucente, Gianluigi Tiberi, Agostino Monorchio, Giuliano Manara, Raj Mittra

Turkish Journal of Electrical Engineering and Computer Sciences

The objective of this paper is to describe a numerically efficient strategy for solving large electromagnetic scattering problems. This novel approach, termed as the Characteristic Basis Function Method (CBFM), is based on utilizing Characteristic Basic Functions (CBFs)-special functions defined on macro domains (blocks)-that include a relatively large number of conventional sub-domains discretized by using triangular or rectangular patches. The CBFs can be derived either analytically (from PO solutions), or by applying the conventional MoM. Use of these basis functions leads to a significant reduction in the number of unknowns, and results in a substantial size reduction of the MoM matrix. …


Analysis And Optimization Of Mobile Phone Antenna Radiation Performance In The Presence Of Head And Hand Phantoms, Erdem Ofli, Chung-Huan Li, Nicolas Chavannes, Niels Kuster Jan 2008

Analysis And Optimization Of Mobile Phone Antenna Radiation Performance In The Presence Of Head And Hand Phantoms, Erdem Ofli, Chung-Huan Li, Nicolas Chavannes, Niels Kuster

Turkish Journal of Electrical Engineering and Computer Sciences

A commercial clam shell phone CAD model is used to numerically investigate the effect of a hand phantom on mobile phone antenna radiation performance. The simulation results show that the grip of the hand phantom is the most important parameter to antenna performance. The antenna is converted into a parameterized form, then optimized to achieve the targeted multi-band performance in real-usage conditions.


Dual-Band Split-Ring Antenna Design For Wlan Applications, S. Cumhur Başaran, Yunus E. Erdemli̇ Jan 2008

Dual-Band Split-Ring Antenna Design For Wlan Applications, S. Cumhur Başaran, Yunus E. Erdemli̇

Turkish Journal of Electrical Engineering and Computer Sciences

A dual-band microstrip antenna based on split-ring elements is introduced for WLAN (2.4/5.2 GHz) applications. The proposed split-ring antenna (SRA) has a compact novel design which provides about 2% impedance-bandwidth without a need for additional matching network. Analysis and design of the proposed microstrip antenna is carried out by means of full-wave simulators based on the finite-element method.


Method Of Moments Solution By Using Sinc-Type Basis Functions For The Scattering From A Finite Number Of Conducting Strip Gratings, Taner Oğuzer, Fadil Kuyucuoğlu Jan 2008

Method Of Moments Solution By Using Sinc-Type Basis Functions For The Scattering From A Finite Number Of Conducting Strip Gratings, Taner Oğuzer, Fadil Kuyucuoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

A numerical method of moments (MoM) solution is applied to the electromagnetic scattering from a periodic finite conducting strip array when the incident electromagnetic plane wave E and H polarizations illuminate the grating. For such grating strip geometry, we deal with singular integral equations arising from Neumann and Dirichlet boundary conditions. MoM is applied using band-limited sinc functions as basis and testing functions. The Galerkin approach is followed in MoM formulation. The properties of the sinc function, with the infinite integral, are exploited in the computations of the main matrix elements. Also, the error in our approach goes to zero …


Zero Crossing Counter For Accuracy Improvement Of Fmcw Range Detection, Si̇nan Kurt, Şi̇mşek Demi̇r, Altunkan Hizal Jan 2008

Zero Crossing Counter For Accuracy Improvement Of Fmcw Range Detection, Si̇nan Kurt, Şi̇mşek Demi̇r, Altunkan Hizal

Turkish Journal of Electrical Engineering and Computer Sciences

For civil and military purposes FMCW radars are widely used. The theoretical background is well-established. Nevertheless, improvement of various aspects of these radars is still required. Signal processing is one of the crucial points of the system which determines the capabilities of the radar. In this study a zero crossing detector implementation, which can be efficiently used for target detection and range calculation in short range FMCW range detector is proposed. The duration between consecutive zero-crossings are used as the data instead of the number of cycles per unit time. Experimental evaluation of its performance is also given.


A Novel Theoretical Procedure To Determine Absorption And Gain Coefficients In A Symmetric Single Step-Index Quantum Well Laser, Mustafa Temi̇z, Özgür Önder Karakilinç, Mehmet Ünal Jan 2008

A Novel Theoretical Procedure To Determine Absorption And Gain Coefficients In A Symmetric Single Step-Index Quantum Well Laser, Mustafa Temi̇z, Özgür Önder Karakilinç, Mehmet Ünal

Turkish Journal of Electrical Engineering and Computer Sciences

If the indices n_{II}, n_{I,III} of the regions, the thickness 2a of the active region (AR) and the wavelength \lambda for a single symmetric step-index quantum well laser (SSSIQWL) are given, the normalized propagation constant (NPC) \alpha is obtained. In this novel method, absorption and gain coefficients for the SSSIQWL have been obtained in terms of the NPCs \alpha in the even and odd fields, directly.


Online Tuning Of Set-Point Regulator With A Blending Mechanism Using Pi Controller, Engi̇n Yeşi̇l, Müjde Güzelkaya, İbrahi̇m Eksi̇n, Ö. Aydin Teki̇n Jan 2008

Online Tuning Of Set-Point Regulator With A Blending Mechanism Using Pi Controller, Engi̇n Yeşi̇l, Müjde Güzelkaya, İbrahi̇m Eksi̇n, Ö. Aydin Teki̇n

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new control structure that exploits the advantages of one degree of freedom (1-DOF) and two degree of freedom (2-DOF) control structures with an online tuned set-point regulator with blending mechanism (SPR-BM) is proposed. In this structure, the filtered output of the reference and the pure reference signals are blended so that the overall performance of the system is ameliorated with respect to load disturbance rejection and set-point following. Internal Model Control (IMC) based PI controller is used as the primary controller and the blending dynamics are determined with the aim of producing a system output that …


A New Approach Using Temporal Radial Basis Function In Chronological Series, Mustapha Guezouri Jan 2008

A New Approach Using Temporal Radial Basis Function In Chronological Series, Mustapha Guezouri

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we present an extended form of Radial Basis Function network called Temporal-RBF (T-RBF) network. This extended network can be used in decision rules and classification in Spatio-Temporal domain applications, like speech recognition, economic fluctuations, seismic measurements and robotics applications. We found that such a network complies with relative ease to constraints such as capacity of universal approximation, sensibility of node, local generalisation in receptive field, etc. For an optimal solution based on a probabilistic approach with a minimum of complexity, we propose two TRBF models (1 and 2). Application to the problem of Mackey-Glass time series has …


Dispersion Analysis Of The Adi-Fdtd And S-Fdtd Methods, Mehmet Kuşaf, Abdullah Y. Öztoprak Jan 2008

Dispersion Analysis Of The Adi-Fdtd And S-Fdtd Methods, Mehmet Kuşaf, Abdullah Y. Öztoprak

Turkish Journal of Electrical Engineering and Computer Sciences

Numerical dispersion performances of ADI-FDTD and S-FDTD methods have been compared. It has been shown that for time steps below the stability limits of the S-FDTD method it has much better dispersion performance compared with the ADI-FDTD method and that the S-FDTD method can be usefully employed for space increments in the order of \lambda/25 to \lambda/50.


Pattern Synthesis With Uniform Circular Arrays For The Reduction Of Wcdma Intercell Interference, Mohammed Al-Husseini, Elias Yaacoub, Karim Y. Kabalan, Ali El-Hajj Jan 2008

Pattern Synthesis With Uniform Circular Arrays For The Reduction Of Wcdma Intercell Interference, Mohammed Al-Husseini, Elias Yaacoub, Karim Y. Kabalan, Ali El-Hajj

Turkish Journal of Electrical Engineering and Computer Sciences

The deployment of advanced antenna arrays at the base stations of cellular systems is a key technique in reducing intercell interference, and thus increasing the number of served users. Uniform circular arrays (UCAs) provide 360 degrees of coverage, their patterns are steering-invariant and their sidelobe levels are controllable. This paper investigates the use of UCAs having specially synthesized patterns at the base stations of WCDMA cellular systems. The decrease in the ratio of intercell interference to intracell power resulting from the use of these arrays in a beam-steering scheme will be assessed, and the advantages and disadvantages of each pattern …


Distance Relaying Algorithm For Double-Circuit Transmission Line With Compensation For Reactance Effect Under Standard Availability Of Measurements, Jan Izykowski, Marcin Bozek Jan 2008

Distance Relaying Algorithm For Double-Circuit Transmission Line With Compensation For Reactance Effect Under Standard Availability Of Measurements, Jan Izykowski, Marcin Bozek

Turkish Journal of Electrical Engineering and Computer Sciences

This paper deals with non-pilot distance protection of a double-circuit transmission line. Negative impact of the reactance effect, appearing in measuring a fault loop impedance, on operation of the relay is discussed. An adaptive algorithm allowing one to prevent the relay from mis- or mal-operation caused by the reactance effect is introduced. The algorithm is designed for a standard availability of measurements from one end of the double-circuit line, i.e. when three-phase voltage and current from the faulted line circuit, and additionally zero-sequence current from the healthy line circuit, are provided as the relay input signals. The algorithm is based …


Power Distortion Issues In Wind Turbine Power Systems Under Transient States, Tadeusz Lobos, Jacek Rezmer, Tomasz Sikorski, Zbigniew Waclawek Jan 2008

Power Distortion Issues In Wind Turbine Power Systems Under Transient States, Tadeusz Lobos, Jacek Rezmer, Tomasz Sikorski, Zbigniew Waclawek

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper time-frequency methods have been investigated for complex investigations of transient states in wind power plants. Application of parallel processing in time and frequency domain brought new findings in description of wind power plants working under transient conditions. Proposed algorithms represents standard Short-Time Fourier Transform (STFT) as well as alternative methods associated with Cohen's class: Choi-Williams Distribution (CWD) and Zhao-Atlas-Marks Distribution (ZAMD). In order to explore advantages and disadvantages of the method several experiments were performed using model of squirrel-cage induction machine connected directly to the grid. Investigated phenomena concerned power distortion caused by switching-on capacitor banks and …


Ergodicity Conditions In A Simple Best Effort Queueing Networks, Abdeldjebbar Kandouci, Abdelmadjid Ezzine, Toufik Guendouzi Jan 2007

Ergodicity Conditions In A Simple Best Effort Queueing Networks, Abdeldjebbar Kandouci, Abdelmadjid Ezzine, Toufik Guendouzi

Turkish Journal of Mathematics

No abstract provided.


Semi-Slant Submanifolds Of A Nearly Kaehler Manifold, Viqar Azam Khan, Meraj Ali Khan Jan 2007

Semi-Slant Submanifolds Of A Nearly Kaehler Manifold, Viqar Azam Khan, Meraj Ali Khan

Turkish Journal of Mathematics

The aim in the present paper is to study some basic geometric properties of semi-slant submanifolds of a nearly Kaehler manifold.


On Cartan Spaces With (\Alpha, \Beta)-Metric, H. G. Nagaraja Jan 2007

On Cartan Spaces With (\Alpha, \Beta)-Metric, H. G. Nagaraja

Turkish Journal of Mathematics

É. Cartan [2] has originally introduced a Cartan space, which is considered as dual of Finsler space. H. Rund [10], F. Brickell [1] and others studied the relation between these two spaces. The theory of Hamilton spaces was introduced and studied by R. Miron ([8 , [9]). He proved that Cartan space is a particular case of Hamilton space. T. Igrashi ([5], [6]) introduced the notion of the (\alpha, \beta)-metric in Cartan spaces and obtained the metric tensor and the invariants \rho and r which characterize the special classes of Cartan spaces with (\alpha, \beta)-metric. This paper presents a study …


On Graded Secondary Modules, Shahabaddin Ebrahimi Atani, F. Farzalipour Jan 2007

On Graded Secondary Modules, Shahabaddin Ebrahimi Atani, F. Farzalipour

Turkish Journal of Mathematics

Let G be a group with identity e, and let R be a G-graded commutative ring. Here we study the graded primary submodules of a G-graded R-module and examine when graded submodules of a graded representable module are graded representable. A number of results concerning of these class of submodules are given.


The Compact Metric Space Of The Lattice Of Varieties And ^{*}-Varieties Of C^{*}-Algebras, G. Khalilzadeh, Mohammad Hasan Faroughi Jan 2007

The Compact Metric Space Of The Lattice Of Varieties And ^{*}-Varieties Of C^{*}-Algebras, G. Khalilzadeh, Mohammad Hasan Faroughi

Turkish Journal of Mathematics

Variety of Banach algebras is a non-empty class of Banach algebras in which there exist a family of laws such that all of its members satisfy all of the laws. In this paper, we have used merely mathematical items such as Banach algebras and varieties including Banach algebras in order to change the space of all varieties of Banach algebras into a compact metric space. We prove some theorems in the metric space of zero at infinity varieties, define the ^*-varieties of ^{*}-algebra and prove many theorems about ^*-varieties of C^*-algebras.


Equilibria In A Dipersal Model For Structured Populations, Maref Y. M. Alzoubi Jan 2007

Equilibria In A Dipersal Model For Structured Populations, Maref Y. M. Alzoubi

Turkish Journal of Mathematics

We derive a model for structured population with a two-phase life cycle. Growth and reproduction occur during the first phase. The first phase is followed by a dispersal phase in which individuals are allowed to move throughout a habitat. Also, we prove the existence of a branch of positive equilibria using bifurcation results of Rabinowitz.