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Articles 31 - 60 of 175
Full-Text Articles in Physical Sciences and Mathematics
Molecular Dynamics Simulations Of Super Heated Ni_4 Cluster, M. Haluk Güven
Molecular Dynamics Simulations Of Super Heated Ni_4 Cluster, M. Haluk Güven
Turkish Journal of Physics
The fragmentation mechanism of the super heated Ni4 cluster is studied by employing the microcanonical molecular dynamics simulations and an empirical model potential. Ni$_{4}$ cluster is heated up above the bulk Ni evaporation point temperature and then classical trajectory analysis as well as RRK theory are used to calculate survival probability, evaporation rate, average kinetic energy release and dissociation energy.
Characterization Of Phenanthrene Single Crystals, M. Tariq Bhatti, Anwar Manzoor Rana, Mazhar Ali, Gul N. Shahid, M. Saleh
Characterization Of Phenanthrene Single Crystals, M. Tariq Bhatti, Anwar Manzoor Rana, Mazhar Ali, Gul N. Shahid, M. Saleh
Turkish Journal of Physics
Single crystals of phenanthrene were successfully grown from melt using Bridgeman Crystal Growth System Type 365. The starting material was purified by sublimation and zone refining techniques in specially designed crystal growth tubes. Phenanthrene single crystals grow with the plane of maximum growth corresponding to the ab-crystallographic plane, and cleave readily in this plane. The optical absorption spectra of phenanthrene single crystals and phenanthrene crystals dissolved in benzene, alcohol and acetone solutions were studied in the wavelength range (200 - 400 nm). The optical excitations i.e., \( \pi - \pi^{*} \) transitions, are attributed to the weak and strong optical …
Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye
Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye
Turkish Journal of Physics
Antiferromagnetic transition in $\alpha$-Mn-Fe alloys has been studied using resistivity-temperature measurements from 300 to 1.5 K. The results indicate that the transition temperature $T_N$ of the samples studied increases with increasing Fe concentration. This suggests that the N\'{e}el temperature is affected by Fe. Also, Fe plays a significant role in the local disorder on the magnetic moment of the ions in the complex manganese structure.
Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan
Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan
Turkish Journal of Physics
The radioluminescent proporties of silver-doped cadmium sulphide, CdS(Ag), crystals excited by 5.5 MeV $ \alpha $-particles from an $ ^{241}$Am radioactive source have been investigated. The emission spectra, decay profiles and thermal quenching curves were obtained accurately at temperatures between 80 K and 300 K. Two main radioluminescent emission bands centered at about 5760 \AA\ and 5940 \AA\ were observed. Their decay curves were found to be fast and nonexponential. From the thermal quenching of radioluminescence, the activation energies of centers responsible for these emissions were determined. The results are interpreted as the radioluminescence is possibly due to donor-acceptor pair …
Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab
Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab
Turkish Journal of Physics
Spinel nickel manganite has been synthesized using ceramic technique, from (2MnO$_{2}$+NiO) mixture reduced using LiAlH$_{4}$. Powder X-ray diffractometry (XRD) indicates the formation of cubic spinel (a=8.33 A^o), while IR absorption spectral features are rather broad, though similar to those of spinel. The d.c. electrical conductivity of the ceramic is much smaller than that reported for NiMn$_{2}$O$_{4}$. Even though the band gap remains the same, when the sintering temperature is increased from 950^oC to 1100 ^oC, all other changes are insignificant except that the porosity and particle size nearly halve. The characteristics of the system are discussed in terms of `lithiation'.
K-Vacancy Production In The Collision Of Highly Charged Relativistic Ions With Heavy Atoms, P. K. Khabibullaev, V. I. Matveev, D. U. Matrasulov
K-Vacancy Production In The Collision Of Highly Charged Relativistic Ions With Heavy Atoms, P. K. Khabibullaev, V. I. Matveev, D. U. Matrasulov
Turkish Journal of Physics
A general expression for the cross section of the inelastic collision of relativistic highly charged ion with heavy (relativistic) atoms is obtained using the generalized eikonal approximation. In the ultrarelativistic limit, the obtained formula coincides with a known exact one. As an application of the obtained result, probability and cross section of the K-vacany production in the $U^{92+} - U^{91+}$ collision are calculated.
Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak
Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak
Turkish Journal of Physics
In this study, the Kajiwara model has been applied to Cu-14.8at.\%Sn alloy with good agreement with experimental results. For this alloy, the austenite phase has a body centered cubic (bcc) lattice and the martensite phase has a monoclinic 9R superlattice. Using the lattice parameters of both phases, the calculated habit plane indices, magnitude of the lattice invariant shear and orientation relationships, have been compared with the observed results for this alloy.
Devitrification Of Volcanic Glasses In Konya Volcanic Units, Turkey, Zehra Karakaş, Selahatti̇n Kadi̇r
Devitrification Of Volcanic Glasses In Konya Volcanic Units, Turkey, Zehra Karakaş, Selahatti̇n Kadi̇r
Turkish Journal of Earth Sciences
The study area is composed of volcanic, sedimentary and volcano-sedimentary units, which are exposed south and southwest of the city of Konya. XRD analysis indicates that the volcanic units contain halloysite, kaolinite, smectite, illite and sepiolite type clay minerals and opal-CT, feldspar, quartz, minamiite and jarosite type non-clay minerals. SEM studies show that volcanic glasses, which are the main component of the volcanic units, appeared as curviplanar, vesicular-planar and in highly fractured shapes. Fractures and dissolution voids of the volcanic glasses are generally filled by hexagonal kaolinite, fibrous halloysite and smectite. Mineralogical and micromorphological observations indicate that clay minerals were …
Geochemistry And Significance Of Mafic Dyke Swarms In The Pozantı-Karsantı Ophiolite (Southern Turkey), Osman Parlak
Geochemistry And Significance Of Mafic Dyke Swarms In The Pozantı-Karsantı Ophiolite (Southern Turkey), Osman Parlak
Turkish Journal of Earth Sciences
The Pozantı-Karsantı ophiolite, which is one of a number of the Late Cretaceous oceanic lithospheric remnants in southern Turkey, is situated in the eastern Tauride belt and consists of three distinct thrust sheets: an ophiolitic melange, a metamorphic sole, and an ophiolitic stratigraphic sequence. These units (except the ophiolitic melange) are intruded by isolated microgabbro-diabase dykes at all structural levels. The dykes from the lower crustal rocks (cumulates) are subalkaline in character and chemically similar to island arc tholeiitic basalts and basaltic andesites. They are enriched in some LIL elements (Rb, Ba, K and Sr) and depleted in HFS elements …
Late Devonian Conodont Fauna Of The Gümüşali Formation, The Eastern Taurides, Turke, Şenol Çapkinoğlu, İsmet Gedi̇k
Late Devonian Conodont Fauna Of The Gümüşali Formation, The Eastern Taurides, Turke, Şenol Çapkinoğlu, İsmet Gedi̇k
Turkish Journal of Earth Sciences
The Late Devonian Gümüşali formation of the eastern Taurides is a terrigenous-carbonate rock sequence about 600 m thick, consisting mainly of quartz sandstone, quartz siltstone, shale, and carbonate rocks. Palaeontologic and sedimentologic data mainly indicate a shallow subtidal depositional environment. This sequence generally represents the shallow-water polygnathid-icriodid biofacies, and contains conodont faunas that range from the Upper falsiovalis Zone into the Upper praesulcata Zone. However, they do not correlate well to the Late Devonian standard conodont zonation because of the lack of zonally diagnostic species and the irregular vertical distributions of the present taxa. Herein, 54 taxa belonging to nine …
Late Devonian (Famennian) Conodonts From Denizliköyü, Gebze, Kocaeli, Northwestern Turkey, Şenol Çapkinoğlu
Late Devonian (Famennian) Conodonts From Denizliköyü, Gebze, Kocaeli, Northwestern Turkey, Şenol Çapkinoğlu
Turkish Journal of Earth Sciences
Late Devonian (Famennian) conodont faunas have been described from two incomplete stratigraphic sections (GD and GB) of the Ayineburnu member of the Tuzla formation, Denizliköyü, Gebze, Kocaeli, northwestern Turkey. The section GD comprises the Lower and Middle expansa Zones, and the section GB contains the Middle and Upper expansa Zones. Zonal indices for the Middle expansa Zone are identified in the section GB, whereas this zone is recognized on the basis of other key taxa in the section GD. Also, a new species of the Genus Branmehla, Branmehla gediki n.sp. is described from the section GD.
A Special Quasi-Linear Mapping And Its Degree, Aki̇f Abbasov
A Special Quasi-Linear Mapping And Its Degree, Aki̇f Abbasov
Turkish Journal of Mathematics
In this article, for the purpose of expanding to the mappings between Banach manifolds, a degree is determined in for the mappings between Banach spaces, which are from the obvious class.
Some Radius Problem For Certain Families Of Analytic Functions, Yaşar Polatoğlu, Meti̇n Bolcal
Some Radius Problem For Certain Families Of Analytic Functions, Yaşar Polatoğlu, Meti̇n Bolcal
Turkish Journal of Mathematics
The aim of this paper is to give bounds of the radius of $\alpha $-convexity for certain families of analytic functions in the unit disc. The radius of $\alpha $-convexity is generalization of the radius of convexity and the radius of starlikeness, and introduced by S.S.Miller; P.T.Mocanu and M.O.Reade [3,4]
An Efficient Algorithm To Determine The Periodic Steady-State Solutions Of Nonlinear Systems Using Extended Spectral Analysis, Gülay Tohumoğlu
An Efficient Algorithm To Determine The Periodic Steady-State Solutions Of Nonlinear Systems Using Extended Spectral Analysis, Gülay Tohumoğlu
Turkish Journal of Electrical Engineering and Computer Sciences
A new method for the solution of nonlinear periodic systems was developed. It avoids the time domain calculations of the whole network equations. In the proposed method, by forming the augmented network as linear and nonlinear subnetworks these subnetworks are formulated in complex frequency and time domain respectively. Using spectral analysis the steady-state periodic solution of the whole nonlinear network is reached by an iterative approach. The method can be applied efficiently to weak and strong nonlinear circuits equally well. When we divide the network into a large linear subnetwork and a small nonlinear subnetwork, this method can be applied …
Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy
Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy
Turkish Journal of Electrical Engineering and Computer Sciences
A hybrid method consisting of employing the mode matching method in conjunction with the Fourier transform technique is used to analyze the radiation of the dominant TEM-wave from an impedance loaded parallel-plate waveguide. The hybrid method that we adopt here reduces the related boundary value problem to a scalar modified Wiener-Hopf equation of the second kind. The solution involves infinitely many unknown constants satisfying an infinite system of linear algebraic equations susceptible to a numerical treatment. Some computational results illustrating the effects of various parameters on the radiation phenomenon are also presented.
A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar
A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar
Turkish Journal of Electrical Engineering and Computer Sciences
A lossy electric power system that contains thermal units and a pumped-storage hydraulic unit is considered in this paper. The total cost of thermal units in an operation cycle is minimized under some possible electric and hydraulic constraints of the units. The operation cycle is divided into time intervals where the system loads are assumed to remain constant. The proposed solution technique has two main parts. In the first part, the active thermal generations and active generation or pumping power of the pumped-storage unit in all time intervals are determined by using units' active generation incremental costs and pseudo spot …
A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol
A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, two mathematical ways of building a fuzzy model of both linear and nonlinear systems are presented and compared. In order to determine a model for a nonlinear system, the phase plane is divided into sub-regions and a linear model is assigned for each of these regions. This linear model is represented either in state-space or ARX model form. To determine the pre-selected parameters of the linear system model under study, least-square identification method is used. Then these linear models are arranged in a fuzzy manner to characterize the overall system behavior. The results show that this method …
Comparison Of Simulation Algorithms For The Hopfield Neural Network: An Application Of Economic Dispatch, Tankut Yalçinöz, Hali̇s Altun
Comparison Of Simulation Algorithms For The Hopfield Neural Network: An Application Of Economic Dispatch, Tankut Yalçinöz, Hali̇s Altun
Turkish Journal of Electrical Engineering and Computer Sciences
This paper is mainly concerned with an investigation of the suitability of Hopfield neural network structures in solving the power economic dispatch problem. For Hopfield neural network applications to this problem three important questions have been answered: what the size of the power system is; how efficient the computational method; and how to handle constraints. A new mapping process is formulated and a computational method for obtaining the weights and biases is described. A few simulation algorithms used to solve the dynamic equation of the Hopfield neural network are discussed. The results are compared with those of a classical technique, …
Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel
Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel
Turkish Journal of Electrical Engineering and Computer Sciences
The effect of intersymbol interference on distance spectra for trellis coded 8-PSK, 16-QAM and 32-AMPM modulation schemes is evaluated using the methods proposed by Schlegel. Distance spectra of 16-state 8-PSK scheme are computed for different intersymbol interference channels. It is seen that on channels with intersymbol interference the spectral lines are spread into a nearly continuous spectrum and the minimum Euclidean distance between codewords decreases severely. Hence, although the main contribution at large signal to noise ratios comes from the minimum Euclidean distance ( d_{free} ) , higher spectral components also become very important at moderate values of the signal …
Knowledge-Based Navigation For Autonomous Road Vehicles, Murat Eki̇nci̇, Franches W.J.Gibbs, Barry T. Thomas
Knowledge-Based Navigation For Autonomous Road Vehicles, Murat Eki̇nci̇, Franches W.J.Gibbs, Barry T. Thomas
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a computer vision system for an autonomous road vehicle (ARV) that is capable of negotiating complex road networks including road junctions in real time. The ultimate aim of the system is to enable the vehicle to drive automatically along a given complex road network whose geometric description is known. This computer vision system includes three main techniques which are necessary for an ARV: a) road following, b) road junction detection, c) manoeuvring at the road junction. The road following algorithm presents a method of executing a number of algorithms using different methods concurrently, fusing their outputs together …
Decentralised H_{\Infty} Load Frequency Controller Design Based On Ssvs, Hasan Çi̇men
Decentralised H_{\Infty} Load Frequency Controller Design Based On Ssvs, Hasan Çi̇men
Turkish Journal of Electrical Engineering and Computer Sciences
The decentralised load-frequency controller design problem concerned is translated into an equivalent problem of decentralised controller design for a multi-area multi-input multi-output (MIMO) control system. It is shown that subject to a condition based on the structured singular values (SSVs), each local area load-frequency controller can be designed independently. The stability condition for the overall system can be stated as to achieve a sufficient interaction margin. It is demonstrated by computer simulation that within this general framework, local H$_{\infty}$ controllers can be designed to achieve satisfactory performances for a sample two-area power system.
Information And Average Information Rates Of A Graphical Access Structure On Six Vertices, Mustafa Atici
Information And Average Information Rates Of A Graphical Access Structure On Six Vertices, Mustafa Atici
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper we study the optimal information and average information rates of secret sharing schemes which are all connected graphs on six vertices. There are $102$ connected graphs on six vertices that are not complete multipartite graphs. Of these $102$ graphs, we determined the optimal information rate of $71$ graphs, and the optimal average information rate of $88$ graphs.
Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler
Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler
Turkish Journal of Electrical Engineering and Computer Sciences
Precise and fast control chart pattern (CCP) recognition is important for monitoring process environments to achieve appropriate control and to produce high quality products. CCPs can exhibit six types of pattern: normal, cyclic, increasing trend, decreasing trend, upward shift and downward shift. Except for normal patterns, all other patterns indicate that the process being monitored is not functioning correctly and requires adjustment. This paper describes a new type of neural network for speeding up the training process and to compare three training algorithms in terms of speed, performance and parameter complexity for CCP recognition. The networks are multilayered perceptrons trained …
On Torsion-Free Barely Transitive Groups, Mahmut Kuzucuoğlu
On Torsion-Free Barely Transitive Groups, Mahmut Kuzucuoğlu
Turkish Journal of Mathematics
B. Hartley asked the following question: Does there exist a torsion free barely transitive group? Existence of torsion free simple barely transitive group is also unknown. We answer the latter question negatively in a special case. Moreover we proved the following: Let $G$ be a simple barely transitive group, and $H$ be a stabilizer of a point. If for a non-identity element $x \in G$, $C_G (x)$ is infinite then, $C_G (x)$ cannot contain $H$.
Intrinsic Equations For A Relaxed Elastic Line On An Oriented Hypersurface In The Minkowski Space R^N_1, Nevi̇n Gürbüz, Ali̇ Görgülü
Intrinsic Equations For A Relaxed Elastic Line On An Oriented Hypersurface In The Minkowski Space R^N_1, Nevi̇n Gürbüz, Ali̇ Görgülü
Turkish Journal of Mathematics
We gived the intrinsic equations for a relaxed elastic line on an oriented surface in ${\Bbb {R}}_1^3$ ([1],[2]). In this paper, we derived the intrinsic equations for a relaxed elastic line on an oriented time-like hypersurface and space-like hypersurface in the Minkowski space ${\Bbb {R}}_1^n$ and gived additional results about relaxed elastic lines on various timelike and spacelike hypersurface in the Minkowski space ${\Bbb {R}}_1^n$.
Efficient Presentations For Some Direct Products Of Groups, Bi̇lal Vatansever, David M. Gill
Efficient Presentations For Some Direct Products Of Groups, Bi̇lal Vatansever, David M. Gill
Turkish Journal of Mathematics
In this paper we give efficient presentations for $A_4\times D_n$, where n is odd number, or n is even number and (n,3)=1. We also give efficient presentations for $A_5\times D_n$ where n is an even or odd number.
Oscillation Criteria For Second Order Nonlinear Differential Equations With Damping, Aydin Ti̇ryaki̇, Ağacik Zafer
Oscillation Criteria For Second Order Nonlinear Differential Equations With Damping, Aydin Ti̇ryaki̇, Ağacik Zafer
Turkish Journal of Mathematics
Oscillation criteria are given for second order nonlinear differential equations with damping of the form $$(a(t) \psi (x ) \dot x)\dot{}+ p(t) \dot x + q (t) f (x ) = 0,\quad t\geq t_0,$$ where $p$ and $q$ are allowed to change signs on $[t_0,\infty)$. We employ the averaging technique to obtain sufficient conditions for oscillation of solutions of the above equation. Our results generalize and extend some known oscillation criteria in the literature.
Some Graph Type Hypersurfaces In A Semi-Euclidean Space, Ikawa Toshihiko, Honda Kyoko
Some Graph Type Hypersurfaces In A Semi-Euclidean Space, Ikawa Toshihiko, Honda Kyoko
Turkish Journal of Mathematics
We consider some graph type hypersurfaces in a semi-Euclidean space $\Bbb R^{n+1}_{q}$ and give conditions of the dimension $n+1$ and the index $q$ when a hypersurface is lightlike, totally geodesic and minimal.
Conjugacy Classes Of Elliptic Elements In The Picard Group, Ni̇hal Yilmaz, İsmai̇l Naci̇ Cangül
Conjugacy Classes Of Elliptic Elements In The Picard Group, Ni̇hal Yilmaz, İsmai̇l Naci̇ Cangül
Turkish Journal of Mathematics
The Picard group $\mathbf{P}$ is a discrete subgroup of $PSL(2,\Bbb{C})$ with Gaussian integer coefficients. Here it is shown that the total number of conjugacy classes of elliptic elements of order 2 and 3 in $\mathbf{P}$, which is given as seven by B. Fine $\left[ 3\right] $, can actually be reduced to four and using this, the conditions for the maximal Fuchsian subgroups of $\mathbf{P}$ to have elliptic elements of orders 2 and 3 are found.
On Characterization Of Metric Completeness, Guo-Jing Jiang
On Characterization Of Metric Completeness, Guo-Jing Jiang
Turkish Journal of Mathematics
We give seven necessary and sufficient conditions for a metric space to be complete.