Photoelectric light curves of RT coronae borealis and their analysis     

C. Ibanoĝlu  A. Y. Ertan  O. Tümer  S. Evren  Z. Tunca 《Astrophysics and Space Science》1985,112(1):133-143

The first photoelectric light curves of the RS CVn-type eclipsing binary RT CrB are presented. There is no indication about the existence of wave like distortion on its light curve. The light curves were analyzed by using Wood's and Nelson, Davis, and Etzel's methods. The radii of the components are nearly identical. The solutions indicate that the cooler component has a later spectral type between K0 and K2.  相似文献   

Die Serpentingesteine von Bernstein und Steinbach (Burgenland)     

Inei Evren 《Mineralogy and Petrology》1972,17(2):101-122

Zusammenfassung Die Serpentine von Bernstein und Steinbach (mittleres Burgenland) werden als Intrusionen im festen Zustand gedeutet.Während man für Bernstein und seine Umgebung auf Grund fehlender Reliktminerale lediglich eine Einstufung des Serpentinisierungsvorganges in die Grünschieferfazies vornehmen kann, lassen zahlreiche Relikte und das Auftreten verschiedener Pyroxeniteinschlüsse im Serpentin von Steinbach Aussagen über die vormetamorphe Genese dieses Gesteinskörpers zu, dessen Herkunft aus dem oberen Erdmantel abgeleitet wird. Die Serpentinisierung fand unter Bedingungen der Albit-Epidot-Amphibolit-Fazies statt. Daraus und aus allgemeinen Überlegungen ist eine Zuordnung des Serpentinkörpers von Steinbach zur Sieggraben-Schäffern-Serie gegeben, während das Vorkommen von Bernstein der Rechnitzer Serie angehört.

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The serpentinites of Bernstein and Steinbach (Burgenland, Austria)

Summary The serpentinites of Bernstein and Steinbach (Burgenland, Austria) are interpreted to be intrusions at solid state.Numerous relics and the occurrence of various inclusions of pyroxenites in the Steinbach serpentinite indicate its origin from the Upper Mantle. The serpentinization took place under the conditions of the albite-epidote-amphibolite facies.The absence of relics in the Bernstein rocks only permits a classification of the serpentinization itself which corresponds to the greenschist facies. Transfered to the local geological and tectonical situation a coordination of the Steinbach serpentinite body to the Sieggraben-Schäffern series and the Bernstein serpentinites to the Rechnitzer Serie can be accepted.

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Mit 4 Abbilungen  相似文献   

Photoelectric photometry of Z herculis     

S. Evren  A. Y. Ertan  Z. Tunca  C. Ibanoĝlu  M. Kurutaç  O. Tümer 《Astrophysics and Space Science》1982,87(1-2):51-59

Two-colour light curves of Z Her were obtained observing the system from 1978 to 1981. The wave-like distortion at outside eclipses were derived. The amplitudes of the wave increase and its minimum migrates towards the decreasing orbital phase with a period of about 1.4 yr. An attempt was made to represent the wave-like distortions with a truncated Fourier series. The representation was found to be unsatisfactory since the distribution of the present observations is not regular but forms separate groups along the time axis. Therefore, further observations to cover the phases evenly in between the minima are needed.  相似文献   

Light curve variations in V471 Tauri     

Evren  S.  Ibanoğlu  C.  Tunca  Z.  Tümer  O. 《Astrophysics and Space Science》1986,120(1):97-106

The light curves of V471 Tau obtained in four successive years from 1981 to 1984 are presented. The light variations due to the tidally distorted red dwarf have been computed and subtracted out from the light curves obtained so far. A pure shape of the wave-like distortion has therefore been derived. The period of the retrograde migration has been found to be 182.17 days. On the other hand, the mean brightness of the system seems to vary with a period of about 18 years. The amplitude of the variation is greater at longer wavelength. The periodic variation of the mean brightness resembles the solar cycle of about 11.2 years, which depends upon the number of spots or spot groups.  相似文献   

Light curve variations of RT lacertae     

C. Ibanoğlu  M. Kurutaç  O. Tümer  S. Evren  Z. Tunca  A. Y. Ertan 《Astrophysics and Space Science》1980,72(1):61-70

The eclipsing variable RT Lac, which is classified as an RS CVn-type binary by Hall, was observed in two colours,B andV, during the summer seasons of 1978 and 1979. The observations made during two successive seasons indicate that, outside eclipses, the system has brightened by about 0.12 and 0.15 magnitudes on average inB andV, respectively. Moreover, RT Lac was even fainter when observed by Milone in 1965. While the total brightness of the system remained unchanged at mid-secondary, it increased at mid-primary and outside eclipses. This may be interpreted as indicating that the cooler component is responsible for the peculiar light variations.  相似文献   

Estimation of Hardgrove grindability index of Turkish coals by neural networks     

Gülhan Özbayoğlu  A. Murat Özbayoğlu  M. Evren Özbayoğlu 《International Journal of Mineral Processing》2008

In this research, different techniques for the estimation of coal HGI values are studied. Data from 163 sub-bituminous coals from Turkey are used by featuring 11 coal parameters, which include proximate analysis, group maceral analysis and rank. Non-linear regression and neural network techniques are used for predicting the HGI values for the specified coal parameters. Results indicate that a hybrid network which is a combination of 4 separate neural networks gave the most accurate HGI prediction and all of the neural network models outperformed non-linear regression in the estimation process.  相似文献   

Simulation of multiphase flow in fractured reservoirs using a fracture-only model with transfer functions     

Evren Unsal  Stephan K. Matthäi  Martin J. Blunt 《Computational Geosciences》2010,14(4):527-538

We present a fracture-only reservoir simulator for multiphase flow: the fracture geometry is modeled explicitly, while fluid movement between fracture and matrix is accommodated using empirical transfer functions. This is a hybrid between discrete fracture discrete matrix modeling where both the fracture and matrix are gridded and dual-porosity or dual-permeability simulation where both fracture and matrix continua are upscaled. The advantage of this approach is that the complex fracture geometry that controls the main flow paths is retained. The use of transfer functions, however, simplifies meshing and makes the simulation method considerably more efficient than discrete fracture discrete matrix models. The transfer functions accommodate capillary- and gravity-mediated flow between fracture and matrix and have been shown to be accurate for simple fracture geometries, capturing both the early- and late-time average behavior. We verify our simulator by comparing its predictions with simulation results where the fracture and matrix are explicitly modeled. We then show the utility of the approach by simulating multiphase flow in a geologically realistic fracture network. Waterflooding runs reveal the fraction of the fracture–matrix interface area that is infiltrated by water so that matrix imbibition can occur. The evolving fraction of the fracture–matrix interface area turns out to be an important characteristic of any particular fracture system to be used as a scaling parameter for capillary driven fracture–matrix transfer.  相似文献   

Spectroscopic and photometric observations of selected Algol-type binaries – I. V1665 Aquilae and AG Arietis     

C. &#;bano&#;lu  S. Evren  G. Ta&#;  Ö. Çak&#;rl&#;  Z. Bozkurt  M. Af&#;ar  A. Frasca  E. Sipahi  H. A. Dal  O. Özdarcan  D. Zengin Çamurdan  M. Çamurdan  D. Gandolfi 《Monthly notices of the Royal Astronomical Society》2007,380(4):1422-1432

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Photoelectric photometry of the peculiar system RT Lacertae     

S. Evren  Z. Tunca  C. Ibanoğlu  O. Tümer 《Astrophysics and Space Science》1985,108(2):383-392

The observations of the peculiar eclipsing binary RT Lac were continued during the observing seasons of 1982 and 1983. The salient properties of the light curves were presented. The shallowest primary eclipse was observed in 1983. When the light curves, obtained in six years sucessively, are interpreted together it is seen that the variations of the brightness at mid-primary and second maximum are too similar to each other. The colour variations at mid-primary also follow those variations in the brightness. These circumstances indicate that the starspot hypothesis is insufficient alone to explain all the phenomena observed. The earlier spectral type G9 companion may be intrinsically variable and the unusual distortion on the light curves following the secondary eclipse may arise from the gas-stream from larger K star to the G9 star.  相似文献   

Two-colour photoelectric investigation of AR Lacertae     

M. Kuturaç  C. Ibanoğlu  Z. Tunca  A. Y. Ertan  S. Evren  O. Tümer 《Astrophysics and Space Science》1981,77(2):325-346

The RS CVn-type eclipsing binary AR Lac has been observed in two colours,B andV, in 1978 and 1979. Several times of minima have been obtained during the observations and the new light elements have been calculated. The orbital period of the system was found to be decreasing with an amount of 14.6 s century^–1.The light curves of the system obtained inB andV show a significant wave-like distortion outside eclipses. The amplitudes of the wave-like distortion inB andV are about 0 _. ^m 09 and 0 _. ^m 10 in 1978, and, 0 _. ^m 12 and 0 _. ^m 13 in 1979, respectively. The minima of the wave-like distortion have shifted with an amount of 0 _. ^p 40 in one year, thus indicating the migration period of the wave-like distortion is about 2.5 yr.A noticeable variation of light during the totality of primary minimum has also been observed. This variation can be attributed to the distortion wave which has been moving towards decreasing phases.  相似文献