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Articles 10141 - 10170 of 10730
Full-Text Articles in Physical Sciences and Mathematics
Three-Channel General-Purpose Astrophotometer, Romualdas Kalytis
Three-Channel General-Purpose Astrophotometer, Romualdas Kalytis
Turkish Journal of Physics
The high-speed three-channel photometer suitable for the time-series observations of the "Whole Earth Telescope" (WET) project as well as for multicolor photometry is described. The photometer, designed for the Capodimonte Astronomical Observatory, Italy, is the latest version of the WET photometers developed by the WET group of Vilnius University since 1992. The main optical and mechanical layouts of the optico-mechanical module as well as the block-diagram of electronics are presented. The main specifications of the photometer expected after its completion are given.
Photometric Imaging With Distributive Solar Analogy, Zeki̇ Eker
Photometric Imaging With Distributive Solar Analogy, Zeki̇ Eker
Turkish Journal of Physics
The importance of DSA (Distributive Solar Analogy) when modeling starspots from a photometric data is discussed. It's advantage over the other modeling techniques to confine the solution parameters, especially the spot latitudes are described. Unlike the other photometric techniques which tries to locate limited number of cool surface spots, DSA aims to model global distribution of all virtually existing spots.
Exclusive Disjunctions In Indefinite And Maybe Information In Relational Databases, Taflan İ. Gündem
Exclusive Disjunctions In Indefinite And Maybe Information In Relational Databases, Taflan İ. Gündem
Turkish Journal of Electrical Engineering and Computer Sciences
Incorporating indefinite information into databases has been studied extensively. In this paper, we propose a structure called an E-table to represent maybe information and inclusive and exclusive disjunctions. We define the type of redundancies in E-tables and show how to eliminate them. Also we present an extended relational algebra to operate on E-tables. In this paper we expand the concepts and operations defined by Lin and Sunderraman [1] in order to accommodate exclusive disjunctions in relational databases.
Canonical Framings For 3 -Manifolds, Rob Kirby, Paul Melvin
Canonical Framings For 3 -Manifolds, Rob Kirby, Paul Melvin
Turkish Journal of Mathematics
No abstract provided.
On Symplectic Fillings Of 3-Manifolds, Paola Lisca
On Symplectic Fillings Of 3-Manifolds, Paola Lisca
Turkish Journal of Mathematics
No abstract provided.
Alternative Polynomial And Holomorphic Dunford-Pettis Properties, Walden Freedman
Alternative Polynomial And Holomorphic Dunford-Pettis Properties, Walden Freedman
Turkish Journal of Mathematics
Alternatives to the Polynomial Dunford-Pettis property and the Holomorphic Dunford-Pettis property, called the PDP1 and HDP1 properties, respectively, are introduced. These are shown to be equivalent to the DP1 property, an alternative Dunford-Pettis property previously introduced by the author, thus mirroring the equivalence of the three original properties.
Some Theorems Involving Inequalities On P-Valent Functions, Hüseyi̇n Irmak, Ömer Faruk Çeti̇n
Some Theorems Involving Inequalities On P-Valent Functions, Hüseyi̇n Irmak, Ömer Faruk Çeti̇n
Turkish Journal of Mathematics
In this paper, some theorems involving inequalities on $p$-valent functions (that is $p$-valenty close-to-convex functions, $p$-valently starlike functions, and $p$-valently convex functions) are given. Moreover, some applications in the theorems which are important for geometric function theory are also included. Keywords: Analytic, $p$-valent, $p$-valently colse-to-convex functions, $p$-valently starlike functions, $p$-valently convex functions, open unit disk, and Jack's Lemma.
The Structure Of A Solvmanifold's Heegaard Splittings, Darly Cooper, Martin Scharlemann
The Structure Of A Solvmanifold's Heegaard Splittings, Darly Cooper, Martin Scharlemann
Turkish Journal of Mathematics
No abstract provided.
Tyurina Components And Rational Cycles For Rational Singularities, Meral Tosun
Tyurina Components And Rational Cycles For Rational Singularities, Meral Tosun
Turkish Journal of Mathematics
In this paper, we give a geometric proof of Pinkham's theorem on the positive cycles supported on the exceptional divisor of a rational singularity. In order to do this, we give several properties of the Tyurina components of the exceptional divisor and of the points of blowing-up surface of a rational singularity.
The Revovery Of Copper And Cobalt From Oxidized Copper Ore And Converter Slag, Berri̇n Zi̇yadanoğullari, Recep Zi̇yadanoğullari
The Revovery Of Copper And Cobalt From Oxidized Copper Ore And Converter Slag, Berri̇n Zi̇yadanoğullari, Recep Zi̇yadanoğullari
Turkish Journal of Chemistry
The aim of this study was to develop a method for obtaining copper and cobalt from oxidized copper ore and converter slag. In order to convert the copper and cobalt into sulfate compounds the main step was to roast the samples obtained by sulfurization and transfer the samples into solution. First the oxidized copper ore was roasted, followed by the mixture of converter slag and oxidized copper ore. Since the levels of copper and cobalt were low, the sulfurization process was carried out under autoclave conditions. The samples obtained were roasted. The yields of copper and cobalt passed into the …
Nonextensivity And Quantum Groups, Metin Arik
Nonextensivity And Quantum Groups, Metin Arik
Turkish Journal of Physics
Classical set theory is nonextensive since the mathematical definition of a set excludes the possibility that more than one copy of the same element can be in a set. We show that the description of random sets in terms of an algebra of creation operators and their hermitean conjugates yields an interpretation of the unitary quantum group SU_q(d) as the symmetry associated with the construction of d random sets from a given source set of M=(1-q)^{-1} elements.
Q-Calculus And Irreversible Dynamics On A Hierarchical Lattice, Ayşe Erzan, Ayşe Gorbon
Q-Calculus And Irreversible Dynamics On A Hierarchical Lattice, Ayşe Erzan, Ayşe Gorbon
Turkish Journal of Physics
On a lattice with equal spacing on the logarithmic scale, a momentum operator that respects the asymmetry of this nonlinear lattice yields a kinetics that can be understood in terms of diffusion on an underlying ultrametric space, if one also identifies the cannonical commutator with the time dilation operator. The motion to which this non-conventional kinetics corresponds is irreversible, with an explicit violation of time reversal symmetry resulting from the spreading with time of a probability distribution over a larger and larger volume of the phase space.
A New Formalism For Nonextensive Physical Systems: Tsallis Thermostatistics, Uğur Tirnakli, Fevzi Büyükkiliç, Doğan Demi̇rhan
A New Formalism For Nonextensive Physical Systems: Tsallis Thermostatistics, Uğur Tirnakli, Fevzi Büyükkiliç, Doğan Demi̇rhan
Turkish Journal of Physics
Although Boltzmann-Gibbs (BG) statistics provides a suitable tool which enables us to handle a large number of physical systems satisfactorily, it has some basic restrictions : (i) the range of the microscopic interactions must be small compared to the linear size of the macroscopic systems (short-range interactions) , (ii) the time range of the microscopic memory must be small compared to the observation time (Marcovian processes) and (iii) the system must evolve in an Euclidean-like space-time. In the case of a breakdown in one and/or the others of these restrictions, BG statistics fails. More precisely, the situation could be classified …
Statistical Physics, Neural Networks, Brain Studies, Gerard Toulouse
Statistical Physics, Neural Networks, Brain Studies, Gerard Toulouse
Turkish Journal of Physics
An overview of some aspects of a vast domain, located at the crossroads of physics, biology and computer science is presented: 1) During the last fifteen years, physicists advancing along various pathways have come into contact with biology (computational neurosciences) and engineering (formal neural nets). 2) This move may actually be viewed as one component in a larger picture. A prominent trend of recent years, observable over many countries, has been the establishment of interdisciplinary centers devoted to the study of: cognitive sciences; natural and artificial intelligence; brain, mind and behaviour; perception and action; learning and memory; robotics; man-machine communication, …
The Renormalization-Group Microscope: The Local Statistical Mechanics Of Heterogeneous Systems, Dicle Yeşi̇lleten, A. Nihat Berker
The Renormalization-Group Microscope: The Local Statistical Mechanics Of Heterogeneous Systems, Dicle Yeşi̇lleten, A. Nihat Berker
Turkish Journal of Physics
Renormalization-group theory is developed to yield all local microscopic thermodynamic densities in heterogeneous systems. Local energy densities and local magnetizations are thus obtained for random-bond systems, random-field systems, and spin-glasses, in two and three dimensions. Different order-disorder mechanisms in these diverse systems, such as chaotic ordering and domain-wall melting, become quantitatively evident.
Assessment Of The Degree Of Mix Of Powder Mixtures, Orhan Vai̇zoğlu
Assessment Of The Degree Of Mix Of Powder Mixtures, Orhan Vai̇zoğlu
Turkish Journal of Physics
The older methods for the determination of the degree of a random mix was solely based on the calculation of a simple standard deviation. Physical characteristics like, density, average particle weight and size of each component was not considered. Therefore, the evaluation, when the state of a random mix is reached, was somewhat superficial. Poole, Taylor, and Wall [1] have derived equations, where the physical characteristics of the components were taken into consideration. By this means, it is possible to calculate, in advance, the theoretical coefficient of variation and the corresponding confidence limits. One can then experimentally follow under which …
Spectral Broadening Functions, Slavek Rucinski
Spectral Broadening Functions, Slavek Rucinski
Turkish Journal of Physics
Many astrophysical phenomena involving velocity fields produce broadening of spectral lines. Frequently, the cross-correlation function (CCF) is used to extract information about this broadening from segments of high resolution spectra. CCF has become the standard tool for handing extraction of radial-velocity and broadening information from high resolution spectra as it permits integration of information which is common to many spectral lines into one function which is easy to calculate, visualize and interpret. However, it can be argued that this is not the best tool for applications such as determinations of metallicities ([Fe/H]), for finding locations of star spots on active …
Angular Momentum Evolution In Close Late-Type Binaries, Carla Maceroni
Angular Momentum Evolution In Close Late-Type Binaries, Carla Maceroni
Turkish Journal of Physics
Accurate monitoring of the orbital period of late-type close binaries can provide important information on their secular evolution and on the structural changes of their components on very short timescales (i.e. decades). The orbital period turns out to be a powerful tool of investigation: it can be measured to great accuracy even with simple equipments and its change produces an easily detectable cumulative effect over time. This paper focuses on two physical mechanisms that cause orbital periods changes in late type binaries with negligible mass loss from the system: the dynamical evolution due to magnetic braking in tidally locked systems, …
Cyclic Nature Of The Orbital Period Variations Of Some Algol-Type Binaries, Seli̇m O. Selam, Osman Demi̇rcan
Cyclic Nature Of The Orbital Period Variations Of Some Algol-Type Binaries, Seli̇m O. Selam, Osman Demi̇rcan
Turkish Journal of Physics
The long-term period variations of the classical algol-type binaries XZ And, U Cep, \beta Per, RT Per, ST Per and TX UMa were studied by using all available observed times of eclipse minima. The (O-C) diagrams formed by the times of eclipse minima were found to be representable by one or more cyclic variations superimposed on a secular parabolic variation. The secular variations in the orbital periods should be caused by the mass transfer between the component stars and the mass loss from the systems. For our sample of Algol systems, none of the cyclic variations were found caused by …
Short-Period Rs Cvn And W Uma Binaries: How Are They Related?, Frans Van't Veer
Short-Period Rs Cvn And W Uma Binaries: How Are They Related?, Frans Van't Veer
Turkish Journal of Physics
Two groups of late-type very close main sequence binaries, the so-called short-period RS Canum Venaticorum (RS CVn) and W Ursae Majoris (W UMa) systems, are important for the understanding of the structure and evolutionary consequencies of angular momentum loss (AML) resulting from magnetic stellar winds of fast rotating solar type stars. The components of RS CVn stars are close to their Roche lobes, but still detached, whereas W UMa binaries are contact systems; both are rotating fast. One of the crucial problems is trying to answer the question if there is a dynamical relation between the two types of binaries …
Photometric Imaging Of Starspots, Techniques And Reliability, Zeki̇ Eker
Photometric Imaging Of Starspots, Techniques And Reliability, Zeki̇ Eker
Turkish Journal of Physics
Historical development of the starspot hypothesis and the unsolved problems associated with it are presented. The "non{uniqueness" attributed to the spot solutions is a major problem which could still discredit current efforts of starspot modeling by photometric or spectroscopic data. The basics of the starspot photometry(direct and inverse photometric problem, and the error analysis of the inverse problem) are presented. Since an analytical formulation exists to compute synthetic light curves from the physical parameters of spots, and recomputing original parameters analytically from the synthetic curves are also possible, the starspot hypothesis is a consistent physical problem. According to the error …
The Light And Colour Variations Of Mm Her, Günay Taş
The Light And Colour Variations Of Mm Her, Günay Taş
Turkish Journal of Physics
RS CVn type eclipsing binary MM Herculis have been observed using B, V, R filters in 1997 and obtained light and colour curves were examined together with the earlier 12 light and colour curves obtained between 1976 and 1997. It was seen that the system is bluer, while it is fainter. Such finding probably reveals the evolutionary effect of the photospheric bright facular structures surrounding starspots.
Magnetic Activity In The Extreme Ultraviolet, Mihalis Mathioudakis
Magnetic Activity In The Extreme Ultraviolet, Mihalis Mathioudakis
Turkish Journal of Physics
The wealth of astronomical observations obtained in the extreme ultraviolet in recent years, have allowed comprehensive studies of the stellar transition regions and coronae to be carried out. For the first time we have been able to resolve individual coronal lines of various elements formed over a large temperature range (10^{5} - 10^{7.2} K). The temperature, densities, abundances and magnetic field strengths of the stellar coronae can now be determined. Here we review some of the observations in the field of cool stars and discuss the implications on atmospheric heating requirements.
Solar Flares, E. Rennan Pekünlü
Solar Flares, E. Rennan Pekünlü
Turkish Journal of Physics
In this paper, the dynamics, the magnetohydrodynamics and the energetics of flaring magnetic loops are reviwed. It is also emphasized that the presented model is in no way a unique one. The most commonly occurring type is labelled as B type flares. This paper reviews the general features of a B type flare.
Dynamical Evolution Of The Rs Cvn-Type Binaries, Osman Demi̇rcan
Dynamical Evolution Of The Rs Cvn-Type Binaries, Osman Demi̇rcan
Turkish Journal of Physics
The orbital angular momentum (orbital AM) of a sample of forty RS CVn-type binaries with the orbital periods P \leq 10 days were estimated and the orbital AM distribution with respect to P was critically interpreted as the orbital AM evolution of these systems caused by the magnetic breaking process with the existence of spin-orbit coupling. The empirical relations (between the orbital AM loss, mass loss and period variation) derived from the diagram of the orbital AM distribution were used in deriving a semi-empirical formula for the dynamical evolution of the RS CVn-type binaries. The magnetic breaking induced dynamical evolution …
Facular Structures On Cool Stars, Serdar Evren
Facular Structures On Cool Stars, Serdar Evren
Turkish Journal of Physics
Activity has many manifestations, from dark spots to bright regions, to the presence of the heated chromosphere, to the superheated corona. Sunspots are extended, strongly magnetic regions on the Sun. Photospheric faculae are generally visible only at the limb. Polar faculae are smaller than the main-zone faculae. The contributions of the active region faculae and the facular network are at least as important as the solar spots in augmenting the solar emission.
On The Coronal Activity Of The Rs Cvn-Type Binaries, Osman Demi̇rcan, Hasan Ak
On The Coronal Activity Of The Rs Cvn-Type Binaries, Osman Demi̇rcan, Hasan Ak
Turkish Journal of Physics
We re-analysed the behaviour of coronal activity of the RS CVn-type binaries as a function of stellar and orbital parameters. Highly significant correlations were found between the x-ray luminosity L_x and the stellar radius R, the Roche lobe filling fraction \Gamma, and the Alfven radius RA. The correlations of L_x with the mass M, the absolute magnitude M_V, the surface gravity g, the Roche lobe filling fraction \Gamma, and the Alfven radius RA are likely to be due to correlations of these quantities with the stellar radius R. Surprisingly, no correlation of L_x on the color (B-V), the rotation velocity …
Co-Ordinated Multi-Wavelength Observations Of The Rs Cvn System Cf Tuc, Edwin Budding, K. L. Jones, O. B. Slee, L. Watson
Co-Ordinated Multi-Wavelength Observations Of The Rs Cvn System Cf Tuc, Edwin Budding, K. L. Jones, O. B. Slee, L. Watson
Turkish Journal of Physics
A `multi-site, multi-wavelength' campaign on the eclipsing RS CVn binary CF Tuc was carried out in 1996 over both optical (photometry and spectroscopy) and radio (microwave) ranges. The microwave data was taken with the Australia Telescope Compact Array (ATCA). It covered slightly more than one complete orbital cycle at 4.8 and 8.64 GHz in one continuous run. There was also coverage of about 25% of the light curve at 1.38 and 2.38 GHz. High dispersion spectroscopy was obtained using the McLellan 1m telescope and échelle spectrograph at Mt John University Observatory (New Zealand). Supporting photometry came from various smaller-scale facilities …
The Experimental Studies On Zr Photoelectron Spectra, I. Buribayev, N. A. Nurmatov, N. Talipov
The Experimental Studies On Zr Photoelectron Spectra, I. Buribayev, N. A. Nurmatov, N. Talipov
Turkish Journal of Physics
Photoelectron spectra (PES) taken from crystalline Zr at 8.4 eV and 10 eV have been studied by a high resolution photoelectron analyzer, with \Delta E = 0.1 eV, and the results were compared to the results calculated for electron density of states in the valence band. Photoelectron work function (WF) measured from the atomically clean Zr surface by Fowler isothermal curves was found to be 3.95 eV \pm 0.02 eV. It was shown that a small dose of residual gas, namely CO, absorbed on the Zr surface, resulted in a decrease of the WF by 0.15-0.25 eV as well as …
The Structure Of Liquid Alkali Metals Calculated By The Thermodynamic Perturbation Theory, H. Bi̇rtan Kavanoz, İdri̇s Gümüş
The Structure Of Liquid Alkali Metals Calculated By The Thermodynamic Perturbation Theory, H. Bi̇rtan Kavanoz, İdri̇s Gümüş
Turkish Journal of Physics
The structure of a hard sphere fluid has been calculated numerically via the Percus-Yevick (PY) and hypernetted-chain (HNC) closure relations and used as a reference system to calculate the structure of liquid alkali metals under the optimized random-phase approximation (ORPA) using the effective ion-ion pair potential formed by the Heine-Abarenkov (HA), and the empty-core (EC) pseudopotentials. The results are compared with experimental results. The calculations made by the reference system under the HNC closure relation are in better agreement with experimental results than those found under the PY closure relation.