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Ü. Ertan M. A. Alpar M. H. Erkut K. Y. Ekşi Ş. Çalışkan 《Astrophysics and Space Science》2007,308(1-4):73-77
The anomalous X-ray pulsar 4U 0142+61 was recently detected in the mid infrared bands with the SPITZER Observatory (Wang, Chakrabarty and Kaplan: Nature 440, 772 (2006)). This observation is the first instance for a disk around an AXP. From a reanalysis of optical and infrared data, we show that the observations indicate that the disk is likely to be an active disk rather than a passive dust disk beyond the light cylinder, as proposed in the discovering paper. Furthermore, we show that the irradiated accretion disk model can also account for all the optical and infrared observations of the anomalous X-ray pulsars in the persistent state. 相似文献
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Doğan Bülent Aşci Metin Karakaş Ahmet Pekşen Ertan Erener Arzu Çepni Murat Selim Yavuzyilmaz Selin Alahmad Mohammad Sertçelik Fadime Sertçelik İbrahim Kurtuluş Cengiz 《Natural Hazards》2021,109(2):1675-1716
Natural Hazards - The Northern Branch of the North Anatolian Fault System controls and deforms the Izmit Basin and the Sapanca Lake Basin in the study area. Unlike the Sapanca Lake Basin, the... 相似文献
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A. Y. Ertan O. Tumer Z. Tunca C. Ibanoĝlu M. Kurutac S. Evren 《Astrophysics and Space Science》1982,87(1-2):255-268
The eclípsing binary AR Lac has been observed in two colours,B andV, in 1980 and 1981. The new times of minimal obtained during the observatons indicate that the period of the system is still continuing its decrease. The wave-like distortions outside eclipses have two maxima and are very similar in shape in successive two years. 相似文献
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C. Ibanoĝlu S. Evren O. Tümer A. Y. Ertan Z. Tunca 《Astrophysics and Space Science》1983,95(2):409-416
Two-colour photoelectric observations of LX Per carried out at Ege University Observatory in 1981 and 1982 observing seasons are presented. The light curve of the system has a wave-like distortion which migrates towards the decreasing orbital phase. The period of the retrograde migration of the wave-like distortion has been determined as 475 days. The amplitude of the wave appears to change with time periodically. 相似文献
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S. Evren C. Ibanoglu O. Tümer Z. Tunca A. Y. Ertan 《Astrophysics and Space Science》1983,95(2):401-408
In this paper we present the observations of AR Lac, which were obtained in 1982. The variations in the light curves, occurred in the time interval as short as two months, indicated that the system was very active in 1982 like in 1979. The times of the minima obtained in this study indicate that the orbital period of the system continues to decrease. The decrease in the period was recalculated using all the times of minima obtained photoelectrically between 1961 and 1982 and found to be 17.0±1.4 s century?1. 相似文献
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Ertan Bol Akın Önalp Ersin Arel Sedat Sert Aşkın Özocak 《Bulletin of Earthquake Engineering》2010,8(4):859-873
Ground failures in the form of liquefaction, loss of bearing capacity and soil softening have been observed during the 1999 Marmara (Turkey) earthquake. Research to understand the failure phenomena has been carried out since the earthquakes. This paper attempts to provide explanations to the liquefaction failure of silts in seismic conditions. Findings from a large amount of data collected in the city of Adapazari on the physical and mechanical properties of soils is presented. A geomorphological map of the city has shown that there are surprising horizontal and vertical variations of the facies due to the activity of rivers in the past. Cases of liquefaction appear to have concentrated in former backswamp areas where silts and sandy silts were deposited by crevasse splays. Properties of the soils in zones of liquefaction and non-liquefaction have been determined down to a reasonable depth by measuring the average size, clay content and liquidity index as well as cone penetration resistances with porewater pressures to discover that there is significant discrepancy among those profiles susceptible to liquefaction and non-liquefying deposits. A set of “Adapazari Criteria” is proposed which is intended to improve over the “Chinese Criteria” and is simple enough to be universally applicable. This classification is similar to the existing criteria but emphasizes more on the clay content in addition to measuring the liquid limit and the liquidity index as well as the average size. 相似文献
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We examine the one-dimensional direct current method in anisotropic earth formation. We derive an analytic expression of a simple, two-layered anisotropic earth model. Further, we also consider a horizontally layered anisotropic earth response with respect to the digital filter method, which yields a quasi-analytic solution over anisotropic media. These analytic and quasi-analytic solutions are useful tests for numerical codes. A two-dimensional finite difference earth model in anisotropic media is presented in order to generate a synthetic data set for a simple one-dimensional earth. Further, we propose a particle swarm optimization method for estimating the model parameters of a layered anisotropic earth model such as horizontal and vertical resistivities, and thickness. The particle swarm optimization is a naturally inspired meta-heuristic algorithm. The proposed method finds model parameters quite successfully based on synthetic and field data. However, adding 5 % Gaussian noise to the synthetic data increases the ambiguity of the value of the model parameters. For this reason, the results should be controlled by a number of statistical tests. In this study, we use probability density function within 95 % confidence interval, parameter variation of each iteration and frequency distribution of the model parameters to reduce the ambiguity. The result is promising and the proposed method can be used for evaluating one-dimensional direct current data in anisotropic media. 相似文献
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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