Browsing by Subject "Least squares fit"

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    KD haberleşme için iyonkürenin plazma frekansı -yükseklik profilinin matematiksel modellenmesi
    (IEEE, 2014-04) Toker, C.; Arıkan F.; Arıkan, Orhan
    İyonkürenin plazma frekansı - yükseklik profili özellikle gökdalgası ile yapılan KD haberleşmesini önemli derecede etkilemektedir. Bu çalışmada, belirli bir coğrafik bölge üzerinden bulunan bu profilin, en küçük kareler yöntemi ile doğrusal ve küresel düzlem modellerine oturtulmakta incelenmiştir. IRI-PlasG ile gerçeğe yakın profiller elde edilerek, bahsi geçen modellerin Ankara çevresindeki bir bölge için bu profillere uygunluğu gösterilmektedir
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    Spatio-temporal interpolation of total electron content using a GPS network
    (IEEE, 2013) Deviren, M. N.; Arıkan, F.; Arıkan, Orhan
    Constant monitoring and prediction of Space Weather events require investigation of the variability of total electron content (TEC), which is an observable feature of ionosphere using dual-frequency GPS receivers. Due to various physical and/or technical obstructions, the recordings of GPS receivers may be disrupted resulting in data loss in TEC estimates. Data recovery is very important for both filling in the data gaps for constant monitoring of ionosphere and also for spatial and/or temporal prediction of TEC. Spatial prediction can be obtained using the neighboring stations in a network of a dense grid. Temporal prediction recovers data using previous days of the GPS station in a less dense grid. In this study, two novel and robust spatio-temporal interpolation algorithms are introduced to recover TEC through optimization by using least squares fit to available data. The two algorithms are applied to a regional GPS network, and for a typical station, the number of days with full data increased from 68% to 85%.