Development of a matlab based software package for ionosphere modeling

Download

index.pdf

Date

2009

Author

Nohutcu, Metin

Metadata

Show full item record

Item Usage Stats

415
views

546
downloads

Modeling of the ionosphere has been a highly interesting subject within the scientific community due to its effects on the propagation of electromagnetic waves. The development of the Global Positioning System (GPS) and creation of extensive ground-based GPS networks started a new period in observation of the ionosphere, which resulted in several studies on GPS-based modeling of the ionosphere. However, software studies on the subject that are open to the scientific community have not progressed in a similar manner and the options for the research community to reach ionospheric modeling results are still limited. Being aware of this need, a new MATLAB® based ionosphere modeling software, i.e. TECmapper is developed within the study. The software uses three different algorithms for the modeling of the Vertical Total Electron Content (VTEC) of the ionosphere, namely, 2D B-spline, 3D B-spline and spherical harmonic models. The study includes modifications for the original forms of the B-spline and the spherical harmonic approaches. In order to decrease the effect of outliers in the data a robust regression algorithm is utilized as an alternative to the least squares estimation. Besides, two regularization methods are employed to stabilize the ill-conditioned problems in parameter estimation stage. The software and models are tested on a real data set from ground-based GPS receivers over Turkey. Results indicate that the B-spline models are more successful for the local or regional modeling of the VTEC. However, spherical harmonics should be preferred for global applications since the B-spline approach is based on Euclidean theory.

Subject Keywords

Civil engineering., Ionosphere

URI

http://etd.lib.metu.edu.tr/upload/12611229/index.pdf
https://hdl.handle.net/11511/19121

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Performance of a precast concrete beam-to-beam connection subject to reversed cyclic loading Korkmaz, HH; Tankut, T (Elsevier BV, 2005-08-01) This study was performed as one phase of an extensive research program focusing on the seismic behaviour of precast connections carried out in Middle East Technical University. The primary objective of the research program was to observe and investigate the seismic behaviour of the connection detail proposed by the collaborating company and the specimens with improved details, in order to develop a 11 moment resisting precast concrete beam-to-beam connection". In this study, six beam-beam connection subasse...
Predicting the shear strength of reinforced concrete beams using artificial neural networks Mansour, MY; Dicleli, Murat; Lee, JY; Zhang, J (Elsevier BV, 2004-05-01) The application of artificial neural networks (ANNs) to predict the ultimate shear strengths of reinforced concrete (RC) beams with transverse reinforcements is investigated in this paper. An ANN model is built, trained and tested using the available test data of 176 RC beams collected from the technical literature. The data used in the ANN model are arranged in a format of nine input parameters that cover the cylinder concrete compressive strength, yield strength of the longitudinal and transverse reinforc...
Spatial sensitivity of seismic hazard results to different background seismic activity and temporal earthquake occurrence models Yilmaz, Nazan; Yücemen, Mehmet Semih (Elsevier BV, 2011-07-01) Spatial sensitivity of seismic hazard results to different models with respect to background seismic activity and earthquake occurrence in time is investigated. For the contribution of background seismic activity to seismic hazard, background area source with uniform seismicity and spatially smoothed seismicity models are taken into consideration. For the contribution of faults, through characteristic earthquakes, both the memoryless Poisson and the time dependent renewal models are utilized. A case study, ...
An experimental study on the performance of box type floating breakwaters with screens Kürüm, Mustafa Onur; Ergin, Ayşen; Department of Civil Engineering (2008) In the present thesis the performance of box type floating breakwaters (FBs) with screens under regular waves is examined experimentally in a wave flume. The experiments were conducted in the Coastal and Harbor Engineering Laboratory wave flume, Civil Engineering Department, Middle East Technical University, Ankara. The influence of incident wave characteristics and certain geometric characteristics, such as the width and draft of the structure, on its effciency is examined. Three different widths of the st...
Use of simulated ground motions for the evaluation of energy response of simple structural systems Karim Zadeh Naghshineh, Shaghayegh; Askan Gündoğan, Ayşegül; Erberik, Murat Altuğ (Elsevier BV, 2019-08-01) The literature on energy-based seismic design and assessment methodologies of structural systems mostly relies on real ground motion datasets. However, certain bias exists due to lack of homogeneity in available ground motion datasets. In this study, a large set of ground motions is simulated. Next, the effects of various parameters on seismic behavior of SDOF systems in terms of energy are studied using nonlinear time history analyses. The stochastic finite-fault simulations are performed on the western pa...

Citation Formats

M. Nohutcu, “Development of a matlab based software package for ionosphere modeling,” Ph.D. - Doctoral Program, Middle East Technical University, 2009.