Geomatik Uygulama ve Araştırma Merkezi, (GEOMER) / Geomatics Application and Research Center

Permanent URI for this collectionhttps://hdl.handle.net/11413/6776

Browse

Browsing Geomatik Uygulama ve Araştırma Merkezi, (GEOMER) / Geomatics Application and Research Center by Language "en_US"

Filter results by typing the first few letters
Now showing 1 - 5 of 5
  • No Thumbnail Available
    PublicationMetadata only
    Observation of Kinetic Alfven Waves and Mirror Mode Structure by THEMIS in Central Plasma Sheet
    (2015-06-16) Guyer, Sinan; Can, Zehra; 2759
    Substorms are effective indicator for many physical phenomena in magnetosphere. The central plasma sheet is the main research area in this study which is located in the nightside of the magnetosphere. Since plasma structure shows variability during the substorm, examination of the plasma changes can be observed. This variability contains low frequency structure and instability. The goal of the study is observation of this low frequency, namely kinetic Alfven wave structure and the mirror-mode structure which can be found in high beta plasma condition during substorm time. Charged particles can be accelarated by the KAWs because of their parallel electric field. The energization and acceleration mechanism can be driven by KAWs in central plasma sheet. Both these low frequency structures are important to understand of plasma responds during the substorm. Observations are made with THEMIS-E probe in tail-science, stage 23 of mission which provides a good opportunity for the researchers in order to investigate substorms.
  • No Thumbnail Available
    PublicationMetadata only
    Relations between the GNSS, InSAR, and the other techniques for prediction of earthquakes
    (Springer Heidelberg, Tiergartenstrasse 17, D-69121 Heidelberg, Germany, 2015-09) Urusan, Ahmet Y.
    It is a well-known fact that the earthquakes have a lot of different parameters. Modern technology allows us to observe an important part of these settings. For example, when an earthquake occurs, its location, time, and depth, etc., values are measured by a seismometer. Recently, using the modern technologies, Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) give us a chance to predict earthquakes in the short or long term. For avoiding the destruction the force of an earthquake can bring to human beings, it is inevitable to use the newer techniques. To predict out about the expected main shock, someone must begin to study firstly earthquakes which have already occurred. In this research, the seismometer and acceleration-meter data have been evaluated and compared by the geodetic measuring data of the InSAR and GPS data for Van earthquake on 23 October 2011. The area of research made out by the InSAR technique and the deformations produced by the GPS technique are being tested under centimeter precision. Additionally, the ionospheric total electron content values obtained by the GPS method have been considered, and the ionospheric distortions acquired from the closest Continuously Operating Reference Stations-Turkey stations, particularly Muradiye station, have been observed. Also, they have been interpreted geophysically.
  • No Thumbnail Available
    PublicationMetadata only
    The Earth's magnetic field lines and earthquake relations
    (Amer Inst Physics, 2 Huntington Quadrangle, Ste 1No1, Melville, Ny 11747-4501 USA, 2011) Ürüşan, Ahmet Yücel; 114677
    Earthquake is one of the natural disasters and very important for human life. A lot of people die every year all over the world due to earthquakes. It is very difficult to develop early warning method for earthquakes because of it has 3000 parameters. The earthquake scientists and other people involved are very hard working about this matter. Governments allocate a significant budget for earthquakes. In this study, the earth magnetic field has been researched for early warning. The questions are any tectonic plate movement is effect of the Earth magnetic field lines or changing of the Earth magnetic field lines are effect any tectonic plate. Greater than 7 M earthquakes have been chosen in this study. And 12 years period changing graphics of the earth magnetic field lines where the chosen earthquake locals have been taken.
  • No Thumbnail Available
    PublicationMetadata only
    The Ionospheric Refractivity Effects on the GPS Signals
    (IEEE, 345 E 47Th St, New York, Ny 10017 Usa, 2013) Ünver, Onur; Guyer, Sinan; Uzel, Turgut; Can, Zehra; 9308; 2759
    The communication between the global navigation satellites and ground observation stations is provided by the electromagnetic waves that emits from the satellites. When the satellite signals pass through the Ionosphere, they are refracted by the different Ionospheric layers. The precise determination of the Ionospheric refractivity index is crucial for the evaluation of the Ionospheric delay that depends on the refraction ratio. The electromagnetic waves that passes through the Magnetoionic medium interacts with the medium depending upon the free electron content and plasma frequency. As a consequence of that interaction the medium shows the dispersive and refractive effects on the waves. The phase and group velocity of an electromagnetic wave in the vacuum are equal and advances with the speed of light, on the other hand in the plasma medium there is a relativistic difference between the phase and group velocities, and this difference depends on the refractivity index of the medium. The refractivity shows varieties depending upon the free electron content of the medium, external magnetic field, gyrofrequency of electrons and plasma frequency. In the earth's atmosphere the layer that locates the altitude 501000 km and contains free electrons and positive ions as a result of the effects of the solar radiation and solar energetic particles is called as Ionosphere. In the Ionosphere, the thermal effects on the electrons are low level so this region is termed "cold plasma". In the Ionospheric researches, due to mass of the positive ions higher than mass of the electrons, ion motions are neglected. In terms of quality and quantity, Ionosphere shows the Magnetoionic medium effects on the electromagnetic waves. In this study, the variations of the Ionospheric refractivity index on the GPS signals due to different Ionospheric conditions is examined and made a comparison with the results of the literature.
  • No Thumbnail Available
    PublicationMetadata only
    The neural network in coordinate transformation
    (Amer Inst Physics, 2 Huntington Quadrangle, Ste 1No1, Melville, Ny 11747-4501 USA, 2011) Ürüşan, Ahmet Yücel; 114677
    In international literature, Coordinate operations is divided into two categories. They are coordinate conversion and coordinate transformation. Coordinates converted from coordinate system A to coordinate system B in the same datum (mean origine, scale and axis directions are same) by coordinate conversion. There are two different datum in coordinate transformation. The basis of each datum to a different coordinate reference system. In Coordinate transformation, coordinates are transformed from coordinate reference system A to coordinate referance system B. Geodetic studies based on physical measurements. Coordinate transformation needs identical points which were measured in each coordinate reference system (A and B). However it is difficult (and need a big reserved budget) to measure in some places like as top of mountain, boundry of countries and seaside. In this study, this sample problem solution was researched. The method of learning which is one of the neural network methods, was used for solution of this problem.