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91.
The second part of the First Byurakan Survey is aimed at detecting all bright (B < 16.5) UV-excess starlike objects in a large
area of the sky. By comparison with other major surveys such as the ROSA T All Sky Survey, the ROSAT WGACAT catalogue of point
sources, the IRAS survey, the 6cm Green Bank, the 1.4GHz NRAO VLA, and the 92cm Westerbork Northern sky surveys and with the
catalogue of mean UBVdata on stars, we estimate the number of AGNs present in the FBS survey and its completeness. We have made spectroscopic observations
of nine of the most promising FBS candidates. We have found six new QSOs, bringing the total number of known QSOs in this
survey to 42. By comparison with the Bright Quasar Survey, we found that the completeness of this last survey is of the order
of 70% rather than 30–50% as suggested by several authors.
Based party on observations collected at the Observatorie de Haute-Provence (CNRS, France). The APS databases are supported
by the National Foundation, the National Aeronautics and Space Administration, and the University of Minnesota, and are available
at hup:// aps.umn.edu. The Digitized Sky Survey was produced at the Space Telescope Science Institute (STScI) under U.S. Government
Grant NAG W-2166.
Published in Astrofizika, Vol. 42, No. 1, pp. 5–22, January–March, 1999. 相似文献
92.
Lifelines are networks extending spatiallyover large areas. Transportation systems, pipelines,communication and power transmission systems areexamples of lifelines. The performance of a lifelineafter a major earthquake is particularly vital for acommunity because of the emergency services that areusually required after such events. Performancemeasures are usually expressed in terms of quantitiesthat are assessed based on statistical andprobabilistic methodologies. The major performancemeasure is the probability of reaching from aspecified point to another one successfully after acatastrophic event, such as an earthquake. Evaluationof this performance measure requires a seismic hazardmethodology, capacity determination techniques andnetwork reliability assessment methods. By combiningthese three aspects in one model, it is possible tocalculate the reliability of any lifeline system underseismic danger. The aim of this paper is to present aprobabilistic model for the evaluation of the seismicreliability of lifeline networks having multiplesources. The seismic reliability of a waterdistribution system located in Bursa, Turkey isassessed in order to show the implementation of theproposed model. The numerical calculations are carriedout by the LIFEPACK software, which is developed forthis purpose. 相似文献
93.
Burak Aydog˘an Berna Ayat Mehmet N. Öztürk Esin Özkan Çevik Yalçın Yüksel 《Ocean Engineering》2010,37(5-6):443-453
Owing to their complex character, modeling flow patterns of narrow straits has always been a challenge, even with the numerical techniques of today. This study was aimed at predicting vertical current profiles of a given point in a narrow strait, the Strait of Istanbul. On account of the speed and simplicity it offers, and of its remarkable success in solving complex problems, the feed forward back propagation (FFBP) artificial neural network (ANN) technique was chosen for this study. The model was built on 7039 hours of concurrent measurements of current profiles, meteorological conditions, and surface elevations. The model predicted 12 outputs of East and North velocity components at different depths in a given location. Various alternative models with different inputs and neuron numbers were evaluated attaining the best model by trial and error. Predictions from proposed ANN model were in accordance with the observations with average root mean square error of 0.16 m/s. The same input parameters were then used to build models that predicted current velocities 1–12 h into the future. Results of these predictions show good overall agreement with observations and that FFBP ANN can be used as a reliable tool for forecasting current profiles in straits. 相似文献
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98.
François Bache Speranta‐Maria Popescu Marina Rabineau Christian Gorini Jean‐Pierre Suc Georges Clauzon Jean‐Louis Olivet Jean‐Loup Rubino Mihaela Carmen Melinte‐Dobrinescu Ferran Estrada Laurent Londeix Rolando Armijo Bertrand Meyer Laurent Jolivet Gwénaël Jouannic Estelle Leroux Daniel Aslanian Antonio Tadeu Dos Reis Ludovic Mocochain Nikola Dumurdžanov Ivan Zagorchev Vesna Lesić Dragana Tomić M. Namık Çağatay Jean‐Pierre Brun Dimitrios Sokoutis Istvan Csato Gülsen Ucarkus Ziyadin Çakır 《Basin Research》2012,24(2):125-153
The Messinian Salinity Crisis is well known to have resulted from a significant drop of the Mediterranean sea level. Considering both onshore and offshore observations, the subsequent reflooding is generally thought to have been very sudden. We present here offshore seismic evidence from the Gulf of Lions and re‐visited onshore data from Italy and Turkey that lead to a new concept of a two‐step reflooding of the Mediterranean Basin after the Messinian Salinity Crisis. The refilling was first moderate and relatively slow accompanied by transgressive ravinement, and later on very rapid, preserving the subaerial Messinian Erosional Surface. The amplitude of these two successive rises of sea level has been estimated at ≤500 m for the first rise and 600–900 m for the second rise. Evaporites from the central Mediterranean basins appear to have been deposited principally at the beginning of the first step of reflooding. After the second step, which preceeded the Zanclean Global Stratotype Section and Point, successive connections with the Paratethyan Dacic Basin, then the Adriatic foredeep, and finally the Euxinian Basin occurred, as a consequence of the continued global rise in sea level. A complex morphology with sills and sub‐basins led to diachronous events such as the so‐called ‘Lago Mare’.This study helps to distinguish events that were synchronous over the entire Mediterranean realm, such as the two‐step reflooding, from those that were more local and diachronous. In addition, the shoreline that marks the transition between these two steps of reflooding in the Provence Basin provides a remarkable palaeogeographical marker for subsidence studies. 相似文献
99.
Sermin Çam Kaynar Muslim Murat Saç F. Serap Ereeş 《Environmental Earth Sciences》2014,71(4):1581-1592
In this study, radioactivity measurements in the environment of Akhisar, Gölmarmara, Gördes and Sindirgi regions in Western Turkey were investigated in order to evaluate the implications of any excess radioactivity in the environment of geological formation. The radioactivity concentrations of 40K, 238U and 232Th radionuclides in the soil samples were measured by a NaI(Tl) gamma spectrometer system, and the radium activity concentrations in the water samples were also analyzed by an ZnS(Ag) alpha counter by the collector chamber method. The radioactivity of 40K, 238U and 232Th in soils ranged 2.80–2,347.77, 9.90–256.19 and 9.66–106.53 Bq kg?1, respectively. The activity of 226Ra in the water samples ranged from 0.03 Bq L?1 (0.89pCi/L) to 0.80 Bq L?1 (21.58pCi/L). In addition, the external terrestrial gamma dose rate in air (nGy h?1), annual effective dose rate (mSv year?1) and radium equivalent activity (Bq kg?1) were calculated and compared with international standard values. 相似文献
100.
S. Selam B. Albayrak M. Yilmaz H. V. Şenavci İ Özavci C. Çetintaş 《Astrophysics and Space Science》2005,296(1-4):305-308
Photoelectric UBV light curves of the recently discovered eclipsing binary HX UMa were obtained and studied to determine the preliminary physical
parameters of the system for the first time. The observations were taken at the TüBİTAK1 – Turkish National Observatory (TUG) on three nights in April 2003. A simultaneous analysis of the light and radial velocity
curves yields a typical A-type contact binary with a high degree of overcontact. The influence of the close visual companion
to the total light of the system was taken into account during the analysis.
1TüBİTAK: The Scientific and Technical Research Council of Turkey. 相似文献