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Articles 6961 - 6990 of 10319
Full-Text Articles in Physical Sciences and Mathematics
Adaptive Optimization Of Edca Parameters For Improved Qos In Multi-Media Applications, Alparslan Çi̇l, Mehmet Akar, Emi̇n Anarim
Adaptive Optimization Of Edca Parameters For Improved Qos In Multi-Media Applications, Alparslan Çi̇l, Mehmet Akar, Emi̇n Anarim
Turkish Journal of Electrical Engineering and Computer Sciences
IEEE 802.11e Enhanced Distributed Channel Access (EDCA) has been incorporated into the standard as an effective medium access mechanism in order to provide the desired QoS for multimedia applications such as VoIP and IPTV. This paper presents an adaptive optimization algorithm in EDCA which strives to provide improved QoS from both delay and throughput perspectives. As a first step towards this goal, a Markov model of the EDCA mechanism has been introduced, which is subsequently used to compute the estimates of throughput and delay. Based on the analytical model that is validated via real-time simulations in OPNET, a new algorithm …
Hybrid Mpi+Upc Parallel Programming Paradigm On An Smp Cluster, Zeki̇ Bozkuş
Hybrid Mpi+Upc Parallel Programming Paradigm On An Smp Cluster, Zeki̇ Bozkuş
Turkish Journal of Electrical Engineering and Computer Sciences
The symmetric multiprocessing (SMP) cluster system, which consists of shared memory nodes with several multicore central processing units connected to a high-speed network to form a distributed memory system, is the most widely available hardware architecture for the high-performance computing community. Today, the Message Passing Interface (MPI) is the most widely used parallel programming paradigm for SMP clusters, in which the MPI provides programming both for an SMP node and among nodes simultaneously. However, Unified Parallel C (UPC) is an emerging alternative that supports the partitioned global address space model that can be again employed within and across the nodes …
A Fixed Point Theorem For A Compact And Connected Set In Hilbert Space, Hülya Duru
A Fixed Point Theorem For A Compact And Connected Set In Hilbert Space, Hülya Duru
Turkish Journal of Mathematics
Let (H,) be a real Hilbert space and let K be a compact and connected subset of H. We show that every continuous mapping T:K \rightarrow K satisfying a mild condition has a fixed point.
Covers And Envelopes With Respect To A Semidualizing Module, Xiaoguang Yan, Xiaosheng Zhu
Covers And Envelopes With Respect To A Semidualizing Module, Xiaoguang Yan, Xiaosheng Zhu
Turkish Journal of Mathematics
Let R be a commutative ring and C be a semidualizing R-module. For a given class of R-modules Q, we define a class Q_C by M \in Q_C \Leftrightarrow Hom_R(C,M) \in Q. We prove that if Q \subseteq (R) is a Kaplansky class and closed under direct sums, then Q_C^{\bot} is special preenveloping. As corollaries, we can show that p_C^{n \bot} and f_C^{n \bot} are both special preenveloping. Finally, we show that I_C^n is covering, I_C^{n \bot} is enveloping and special preenveloping provided R is Noetherian.
Combinatorial Results For Order-Preserving And Order-Decreasing Transformations, Gonca Ayik, Hayrullah Ayik, Meti̇n Koç
Combinatorial Results For Order-Preserving And Order-Decreasing Transformations, Gonca Ayik, Hayrullah Ayik, Meti̇n Koç
Turkish Journal of Mathematics
Let O_n and C_n be the semigroup of all order-preserving transformations and of all order-preserving and order-decreasing transformations on the finite set X_n={1,2,\ldots ,n}, respectively. Let \fix (\alpha )={x\in X_n:x\alpha =x} for any transformation \alpha. In this paper, for any Y\subseteq X_n, we find the cardinalities of the sets O_{n,Y}={\alpha\in O_n:\fix (\alpha)=Y} and C_{n,Y}={\alpha\in C_n: \fix (\alpha )=Y}. Moreover, we find the numbers of transformations of O_n and C_n with r fixed points.
Weak-Projective Dimensions, Mohammad Javad Nikmehr, Zahra Poormahmood, Reza Nikandish
Weak-Projective Dimensions, Mohammad Javad Nikmehr, Zahra Poormahmood, Reza Nikandish
Turkish Journal of Mathematics
In this paper, the notions of weak-projective modules and weak-projective dimension over commutative domain R are given. It is shown that over semisimple rings with weak global dimension 1, these modules are equivalent to weak-injective modules. The weak-projective dimension measures how far away a domain is from being a Prüfer domain. Several properties of these modules are also presented.
Conjugate Convolution And Characterizations Of Inner Amenable Locally Compact Groups, Bahram Mohammadzadeh
Conjugate Convolution And Characterizations Of Inner Amenable Locally Compact Groups, Bahram Mohammadzadeh
Turkish Journal of Mathematics
For locally compact group G, we give some characterizations of inner amenability of G by conjugate convolution operations. Moreover, we study multiples of positive elements in group algebra L^1(G), whenever G is inner amenable.
A Class Of Generalized Shannon-Mcmillan Theorems For Arbitrary Discrete Information Source, Kangkang Wang
A Class Of Generalized Shannon-Mcmillan Theorems For Arbitrary Discrete Information Source, Kangkang Wang
Turkish Journal of Mathematics
In this study, a class of strong limit theorems for the relative entropy densities of random sum of arbitrary information source are discussed by constructing the joint distribution and nonnegative super martingales. As corollaries, some Shannon-McMillan theorems for arbitrary information source, mth-order Markov information source and non-memory information source are obtained and some results for the discrete information source which have been obtained by authors are extended.
On Generalized (\Alpha,\Beta)-Derivations Of Semiprime Rings, Faisal Ali, Muhammad Anwar Chaudhry
On Generalized (\Alpha,\Beta)-Derivations Of Semiprime Rings, Faisal Ali, Muhammad Anwar Chaudhry
Turkish Journal of Mathematics
We investigate some properties of generalized (\alpha,\beta)-derivations on semiprime rings. Among some other results, we show that if g is a generalized (\alpha,\beta)-derivation, with associated (\alpha,\beta)-derivation \delta, on a semiprime ring R such that [g(x),\alpha(x)]=0 for all x\in R, then \delta(x)[y,z]=0 for all x,y,z\in R and \delta is central. We also show that if \alpha,\nu,\tau are endomorphisms and \beta,\mu are automorphisms of a semiprime ring R and if R has a generalized (\alpha,\beta)-derivation g, with associated (\alpha,\beta)-derivation \delta, such that g([\mu(x),w(y)])=[\nu(x),w(y)]_{\alpha,\tau}, where w:R\rightarrow R is commutativity preserving, then [y,z]\delta(w(p))=0 for all y,z,p\in R.
Existence Of Mild Solutions For Abstract Mixed Type Semilinear Evolution Equations, Hong-Bo Shi, Wan-Tong Li, Hong-Rui Sun
Existence Of Mild Solutions For Abstract Mixed Type Semilinear Evolution Equations, Hong-Bo Shi, Wan-Tong Li, Hong-Rui Sun
Turkish Journal of Mathematics
This paper is concerned with the existence of global mild solutions and positive mild solutions to initial value problem for a class of mixed type semilinear evolution equations with noncompact semigroup in Banach spaces. The main method is based on a new fixed point theorem with respect to convex-power condensing operator.
Weingarten Quadric Surfaces In A Euclidean 3-Space, Min Hee Kim, Dae Won Yoon
Weingarten Quadric Surfaces In A Euclidean 3-Space, Min Hee Kim, Dae Won Yoon
Turkish Journal of Mathematics
In this paper, we study quadric surfaces in a Euclidean 3-space. Furthermore, we classify quadric surfaces in a Euclidean 3-space in terms of the Gaussian curvature and the mean curvature.
A Fredholm Alternative-Like Result On Power Bounded Operators, Ali̇ Ülger, Onur Yavuz
A Fredholm Alternative-Like Result On Power Bounded Operators, Ali̇ Ülger, Onur Yavuz
Turkish Journal of Mathematics
Let X be a complex Banach space and T:X\rightarrow X be a power bounded operator, i.e., \sup_{n \geq 0}\ T^n\
Rotational Embeddings In E^4 With Pointwise 1-Type Gauss Map, Kadri̇ Arslan, Bengü Kiliç Bayram, Betül Bulca, Young Ho Ki̇m, Cengi̇zhan Murathan, Günay Öztürk
Rotational Embeddings In E^4 With Pointwise 1-Type Gauss Map, Kadri̇ Arslan, Bengü Kiliç Bayram, Betül Bulca, Young Ho Ki̇m, Cengi̇zhan Murathan, Günay Öztürk
Turkish Journal of Mathematics
In the present article we study the rotational embedded surfaces in E^4. The rotational embedded surface was first studied by G. Ganchev and V. Milousheva as a surface in E^4. The Otsuki (non-round) sphere in E^4 is one of the special examples of this surface. Finally, we give necessary and sufficient conditions for the flat Ganchev-Milousheva rotational surface to have pointwise 1-type Gauss map.
A Note On Weighted A_P(G)-Modules, Serap Öztop
A Note On Weighted A_P(G)-Modules, Serap Öztop
Turkish Journal of Mathematics
Let G be a locally compact abelian group and w be a weight function on G. In this paper, we show that the space A_{p,w}(G) is a Banach module over the Figà-Talamanca Herz algebra A_p(G) and study the multiplier space from A_p(G) to A_{p,w}(G).
Hypersurfaces With Constant Mean Curvature In A Real Space Form, Shichang Shu, Sanyang Liu
Hypersurfaces With Constant Mean Curvature In A Real Space Form, Shichang Shu, Sanyang Liu
Turkish Journal of Mathematics
Let M^n be an n\(n \geq 3)-dimensional complete connected and oriented hypersurface in M^{n+1}(c)(c \geq 0) with constant mean curvature H and with two distinct principal curvatures, one of which is simple. We show that (1) if c=1 and the squared norm of the second fundamental form of M^n satisfies a rigidity condition (1.3), then M^n is isometric to the Riemannian product S^1(\sqrt{1-a^2}) \times S^{n-1}(a); (2) if c=0, H \neq 0 and the squared norm of the second fundamental form of M^n satisfies S \geq n^2H^2/(n-1), then M^n is isometric to the Riemannian product S^{n-1}(a)\times R or S^1(a) \times R^{n-1}
Effects Of Silar Cycle On The Electrical Characteristics Of Cd/Cdse/N-Si/Au-Sb Structure, Betül Güzeldi̇r, Mustafa Sağlam, Aytünç Ateş
Effects Of Silar Cycle On The Electrical Characteristics Of Cd/Cdse/N-Si/Au-Sb Structure, Betül Güzeldi̇r, Mustafa Sağlam, Aytünç Ateş
Turkish Journal of Physics
Cd/CdSe/n-Si/Au-Sb structures have been fabricated by Successive Ionic Layer Adsorption and Reaction (SILAR) method under various SILAR cycles. The characteristics parameters of these structures such as barrier height, ideality factor, series resistance are calculated from the current-voltage (I-V) measurements and the barrier height, carrier concentration are calculated from reverse bias capacitance-voltage (C-V) measurements at 300 kHz frequency and room temperature. Furthermore, the density distribution and rectifying ratio of these structure have been calculated from the I-V measurements as a function of SILAR cycle. It has been seen that the changes of characteristic parameters such as barrier height, ideality factor and …
Theoretical Calculation Of Energy Levels Of Pb Iii, Chao Zhou, Jian Jian Cao, Liang Liang, Ling Zhang
Theoretical Calculation Of Energy Levels Of Pb Iii, Chao Zhou, Jian Jian Cao, Liang Liang, Ling Zhang
Turkish Journal of Physics
In this paper, the results of theoretical calculation of five Rydberg series energy levels 5d_{3/2} \to np_{1/2} (n=6--20), 5d_{3/2} \to nf_{5/2} (n=5--20), 5d_{5/2} \to np_{3/2} (n=6--20), 5d_{5/2} \to nf_{7/2} (n=5-20) and 5d_{5/2} \to nf_{5/2} (n=5-20) for Pb III ions are presented using the weakest bound electron potential model (WBEPM) theory, considering foreign level perturbation corrections. The theoretically calculated results agree very well with present known experimental data, and some energy levels without experimental values are predicted.
A 3d Model For Thickness And Diffusion Capacitance Of Emitter-Base Junction Determination In A Bifacial Polycrystalline Solar Cell Under Real Operating Condition, Senghane Mbodji, Babacar Mbow, Fabe Idrissa Barro, Gregoire Sissoko
A 3d Model For Thickness And Diffusion Capacitance Of Emitter-Base Junction Determination In A Bifacial Polycrystalline Solar Cell Under Real Operating Condition, Senghane Mbodji, Babacar Mbow, Fabe Idrissa Barro, Gregoire Sissoko
Turkish Journal of Physics
This paper aims at presenting the behaviour of the space charge region for an n^+-p-p^+ bifacial solar cell under monochromatic illumination. It also deals with mathematical relations in the describing and the use of new approach that involves both junction and back surface recombination velocities with a 3D modelling study. Based on the normalized carriers' density, versus base depth, the space-charge layer thickness (Z_{0,u}) is studied for various parameters such as grain size g, grain boundaries recombination velocity S_{gb}, wavelength \lambda and for different operating conditions. Therefore, the relationship between Z_{0,u} and the diffusion capacitance C_u show that junction in …
Stress-Strain Characteristics, Dynamic Recrystallization, Grain Growth, And Melting Point Of The Binary And Ternary Solder Alloys, Shakib Moqbel Ali Mohammed Alsowidy, Mohammed Ali Shukri
Stress-Strain Characteristics, Dynamic Recrystallization, Grain Growth, And Melting Point Of The Binary And Ternary Solder Alloys, Shakib Moqbel Ali Mohammed Alsowidy, Mohammed Ali Shukri
Turkish Journal of Physics
An advanced solder alloy, Pb-10wt%Sn-3wt%Zn, has been developed to improve the mechanical properties of the Pb-10wt%Sn based solders. Deformation behavior of Pb-10wt%Sn and Pb-10wt%Sn-3wt%Zn alloys was investigated in tension at strain rates from 0.005% to 0.25% s^{-1} in the temperature range 383--433 K. The stress-strain characteristics curves showed two deformation modes: (i) continuous work softening and fracture following a sharp stress in Pb-10wt%Sn, (ii) work hardening with steady-state flow and fracture just after yielding in Pb-10wt%Sn-3wt%Zn. In the work softening type, relatively coarse grains ranging from 30 to 60 \mu m are produced by dynamic recrystallization (DRX). In the work …
Role Of Metallic Zn And In Additives In The Electrical And Dielectric Properties Of Se_{0.85}Te_{0.15} Glassy Alloy, Jyoti Sharma, Santosh Kumar
Role Of Metallic Zn And In Additives In The Electrical And Dielectric Properties Of Se_{0.85}Te_{0.15} Glassy Alloy, Jyoti Sharma, Santosh Kumar
Turkish Journal of Physics
In this paper we report the effect of metallic Zn and In additives on the electrical and dielectric properties of Se_{0.85}Te_{0.15} glassy system. The temperature and frequency dependence of the dielectric parameters in glassy Se_{0.85}Te_{0.15}, Se_{0.75}Te_{0.15}In_{0.10} and Se_{0.75}Te_{0.15}Zn_{0.10} alloys are studied by measuring capacitance and dissipation factor in the frequency range (1 kHz--5 MHz) and temperature range (300--350 K). Direct current (dc) measurements were also performed in the aforesaid temperature range to assess the dc conduction losses. Results are interpreted in terms of a theoretical model which is based on two electron hopping over a potential barrier and is applicable …
On Graded Prime And Primary Submodules, Kürşat Hakan Oral, Ünsal Teki̇r, Ahmet Göksel Ağargün
On Graded Prime And Primary Submodules, Kürşat Hakan Oral, Ünsal Teki̇r, Ahmet Göksel Ağargün
Turkish Journal of Mathematics
Let G be a multiplicative group. Let R be a G-graded commutative ring and M a G-graded R-module. Various properties of graded prime submodules and graded primary submodules of M are discussed. We have also discussed the graded radical of graded submodules of multiplication graded R-modules.
Coverings Of Lie Groupoids, İlhan İçen, M. Habi̇l Gürsoy, A. Fati̇h Özcan
Coverings Of Lie Groupoids, İlhan İçen, M. Habi̇l Gürsoy, A. Fati̇h Özcan
Turkish Journal of Mathematics
In this work we constitute the category of coverings of the Lie fundamental groupoid associated with a connected smooth manifold. We show that this category is equivalent to the category of universal coverings of a connected smooth manifold. In addition, we prove the equivalence of the category of coverings of a Lie groupoid and the category of actions of this Lie groupoid on a connected smooth manifold. Also we present two side results related to actions of Lie groupoids on the manifolds and coverings of Lie groupoids.
Krull Dimension Of Types In A Class Of First-Order Theories, Domenico Zambella
Krull Dimension Of Types In A Class Of First-Order Theories, Domenico Zambella
Turkish Journal of Mathematics
We study a class of first-order theories whose complete quantifier-free types with one free variable either have a trivial positive part or are isolated by a positive quantifier-free formula---plus a few other technical requirements. The theory of vector spaces and the theory fields are examples. We prove the amalgamation property and the existence of a model-companion. We show that the model-companion is strongly minimal. We also prove that the length of any increasing sequence of prime types is bounded, so every formula has finite Krull dimension.
Approximation By Complex Potentials Generated By The Gamma Function, Sorin G. Gal
Approximation By Complex Potentials Generated By The Gamma Function, Sorin G. Gal
Turkish Journal of Mathematics
In this paper we find the exact orders of approximation of analytic functions by the complex versions of several potentials (including the Flett potential) generated by the Gamma function and by some singular integrals.
A Beurling-Type Theorem In Bergman Spaces, Ali Abkar
A Beurling-Type Theorem In Bergman Spaces, Ali Abkar
Turkish Journal of Mathematics
It is known that Beurling's theorem concerning invariant subspaces is not true in the Bergman space (in contrast to the Hardy space case). However, Aleman, Richter, and Sundberg proved that every cyclic invariant subspace in the Bergman space \lpad, 0
Geometrical Objects Associated To A Substructure, Fatma Özdemi̇r, Mircea Craşmareanu
Geometrical Objects Associated To A Substructure, Fatma Özdemi̇r, Mircea Craşmareanu
Turkish Journal of Mathematics
Several geometric objects, namely global tensor fields of (1,1)-type, linear connections and Riemannian metrics, associated to a given substructure on a splitting of tangent bundle, are studied. From the point of view of lifting to entire manifold, two types of polynomial substructures are distinguished according to the vanishing of not of the sum of the coefficients. Conditions of parallelism for the extended structure with respect to some remarkable linear connections are given in two forms, firstly in a global description and secondly using the decomposition in distributions. A generalization of both Hermitian and anti-Hermitian geometry is proposed.
Simulation Of Storage Time Versus Reverse Bias Current For P^+N And Pin Diodes, Mehmet Serhat Keserli̇oğlu, Hasan Hüseyi̇n Erkaya
Simulation Of Storage Time Versus Reverse Bias Current For P^+N And Pin Diodes, Mehmet Serhat Keserli̇oğlu, Hasan Hüseyi̇n Erkaya
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, the reverse-recovery behaviors of pin and p^+n diodes were simulated as a function of the reverse current and carrier lifetime. For this purpose, a 1-D simulation program was written to solve the semiconductor equations. MatLab partial differential equation solver was used. The reverse recovery response of pin and p^+n diodes was obtained for various values of a resistor in series and of carrier lifetime. The transient response for voltage and current was determined.
A New Lvi Assisted Psfb Dc-Dc Converter, Ahmet Faruk Bakan
A New Lvi Assisted Psfb Dc-Dc Converter, Ahmet Faruk Bakan
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a new Phase Shifted Full Bridge (PSFB) Pulse Width Modulated (PWM) isolated dc-dc converter is proposed. In the proposed converter, resonant inductor is replaced with Linear Variable Inductor (LVI) that is controlled by output current. The soft switching operation range is increased and the dependency of ZVS operation on the load current is decreased. The required energy for ZVS operation at low current levels is obtained by means of the high value of the LVI. The value of LVI decreases approximately linearly with increasing current. At high current levels parasitic resonance and duty cycle loss are decreased. …
Electromagnetic Scattering From Layered Strip Geometries: The Method Of Moments Study With The Sinc Basis, Taner Oğuzer, Fadil Kuyucuoğlu, İbrahi̇m Avgin
Electromagnetic Scattering From Layered Strip Geometries: The Method Of Moments Study With The Sinc Basis, Taner Oğuzer, Fadil Kuyucuoğlu, İbrahi̇m Avgin
Turkish Journal of Electrical Engineering and Computer Sciences
Electromagnetic scattering from strips of layers is analyzed using the method of moments (MoM) for both polarizations in spatial domain with the sinc-type orthogonal sets as basis and testing functions. We exploited the sinc function's properties of exponential convergence, the orthogonality, easy convolution and better handling of singular kernels in MoM procedure resulting in fast performance and reasonable accuracy even in ordinary MoM treatment. We transferred the integral of the Hankel function multiplied by sinc functions to Hankel function introducing a slight error with large band width. We proved that this relative error during the generation of the main matrix …
Vibrations Control Of Light Rail Transportation Vehicle Via Pid Type Fuzzy Controller Using Parameters Adaptive Method, Muzaffer Meti̇n, Rahmi̇ Güçlü
Vibrations Control Of Light Rail Transportation Vehicle Via Pid Type Fuzzy Controller Using Parameters Adaptive Method, Muzaffer Meti̇n, Rahmi̇ Güçlü
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a conventional PID type fuzzy controller and parameter adaptive fuzzy controller are designed to control vibrations actively of a light rail transport vehicle which modeled as 6 degree-of-freedom system and compared performances of these two controllers. Rail vehicle model consists of a passenger seat and its suspension system, vehicle body, bogie, primary and secondary suspensions and wheels. The similarity between mathematical model and real system is shown by comparing uncontrolled simulation results and vibration measurements. For carrying a comfortable travel, rail vehicle body and passenger seat vibrations are minimized by adding a controller between rail vehicle body …