Browsing by Subject "Geology"

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Akademiden siyasete uzanan mücadele dolu bir yaşam: Şuayip Üşenmez
(Bilkent University, 2021) Bayazıt, Mirabel Alsu; Karayazı, Burçe; Üşenmez, Gönül Beril; Özbek, Nehir Zeynep; Zilcioğlu, Kutay
Cumhuriyet sonrası Türk Siyasi Tarihinin anlaşılabilirliği açısından önemli siyasetçilerinin hayatlarının araştırılması önemli bir yer oynamaktadır. Hem siyasi hem de akademik alanda yaptığı çalışmalardan ötürü Şuayip Üşenmez’in hayat hikayesi ilham alınması açısından araştırılmaya değerdir. Doğduğu yer Yozgat’ta sahip olduğu imkansızlıklara rağmen eğitimini sürdürmek uğruna bolca çaba sarf eden Üşenmez, jeoloji alanında akademisyen olarak yükselmeye başladı. Akademisyenlik hayatına araştırma görevlisi olarak başladığı Ankara Üniversitesi’nden doktorasını aldıktan sonra Gazi Üniversitesi’nde devam etti. Lisans eğitimi sırasında Alparslan Türkeş ile tanışması ile aktif siyasete atılan Üşenmez, Türkeş’in önderlik ettiği Cumhuriyetçi Köylü Millet Partisi’nin Ankara Gençlik Kolları Başkanı oldu. Akademisyenlik kariyerini ilerlettiği dönemlerde pasif bir şekilde siyasette yerini alan Şuayip Üşenmez, o dönemde Milliyetçi Hareket Partisi’nin başkanı olan Türkeş’e gayri resmi danışmanlık yaptı. Bu pasif siyaset hayatını içeren dönemde Türkiye siyasetinde yankı uyandıran 12 Eylül 1980 darbesi gerçekleşti. 1999 yılında seçilen 57. Türkiye Hükümetinde Milliyetçi Hareket Partisinden memleketi Yozgat’ın milletvekili oldu. Dönemin siyasi ve ekonomik buhranlarının beraberinde gelmesi ile milletvekilliğinden Devlet Bakanlığına atandı. Türkiye siyasetinde önemli izler bırakan 12 Eylül 1980 darbesi ve 1999 Ekonomik Krizinin yaşandığı dönemlerde siyasette rolü olan Üşenmez, dönemin siyasi tarihinin araştırılması sırasında büyük katkılar bulunabileceği öngörüldü. Bu araştırmada Üşenmez’in bireysel deneyimleri ile Türk siyasi tarihine farklı bir bakış açısı ile bakılması hedef kılınmıştır. Milliyetçi Hareket Partisi’nin kuruluşu, 12 Eylül 1980 darbesi ve 1999 Ekonomik Krizinin yaşandığı dönemlerde Türk siyasetçilerinin yaşadıkları, Şuayip Üşenmez’in yaşamı ve hem jeoloji alanında hem de siyasette bulunduğu katkıları bu araştırma kapsamında incelenmektedir.
Open Access
Building detection using directional spatial constraints
(IEEE, 2010) Akçay, H. Gökhan; Aksoy, Selim
We propose an algorithm for automatic detection of buildings with complex shapes and roof structures in very high spatial resolution remotely sensed images. First, an initial oversegmentation is obtained. Then, candidate building regions are found using shadow and sun azimuth angle information. Finally, the building regions are selected by clustering the candidate regions using minimum spanning trees. The experiments on Ikonos scenes show that the algorithm is able to detect buildings with complex appearances and shapes. © 2010 IEEE.
Open Access
Detection of compound structures using hierarchical clustering of statistical and structural features
(IEEE, 2011) Akçay, H. Gokhan; Aksoy, Selim
We describe a new procedure that combines statistical and structural characteristics of simple primitive objects to discover compound structures in images. The statistical information that is modeled using spectral, shape, and position data of individual objects, and structural information that is modeled in terms of spatial alignments of neighboring object groups are encoded in a graph structure that contains the primitive objects at its vertices, and the edges connect the potentially related objects. Experiments using WorldView-2 data show that hierarchical clustering of these vertices can find high-level compound structures that cannot be obtained using traditional techniques. © 2011 IEEE.
Open Access
Detection of compound structures using multiple hierarchical segmentations
(IEEE, 2012) Akçay, H. Gökhan; Aksoy, Selim
In this paper, our aim is to discover compound structures comprised of regions obtained from hierarchical segmentations of multiple spectral bands. A region adjacency graph is constructed by representing regions as vertices and connecting these vertices that are spatially close by edges. Then, dissimilarities between neighboring vertices are computed using statistical and structural features, and are assigned as edge weights. Finally, the compound structures are detected by extracting the connected components of the graph whose edges with relatively large weights are removed. Experiments using WorldView-2 images show that grouping of these vertices according to different criteria can extract high-level compound structures that cannot be obtained using traditional techniques. © 2012 IEEE.
Open Access
Finding compound structures in images using image segmentation and graph-based knowledge discovery
(IEEE, 2009-07) Zamalieva, Daniya; Aksoy, Selim; Tilton J. C.
We present an unsupervised method for discovering compound image structures that are comprised of simpler primitive objects. An initial segmentation step produces image regions with homogeneous spectral content. Then, the segmentation is translated into a relational graph structure whose nodes correspond to the regions and the edges represent the relationships between these regions. We assume that the region objects that appear together frequently can be considered as strongly related. This relation is modeled using the transition frequencies between neighboring regions, and the significant relations are found as the modes of a probability distribution estimated using the features of these transitions. Experiments using an Ikonos image show that subgraphs found within the graph representing the whole image correspond to parts of different high-level compound structures. ©2009 IEEE.
Open Access
Progressive compression of digital elevation data using meshes
(IEEE, 2009-07) Köse, Kıvanç; Yılmaz, E.; Çetin, A. Enis
In this paper a new Digital Elevation Map (DEM) image compression algorithm is proposed. DEM image can be threated as a grayscale image, whose pixel values are the elevation values of the map points. The grayscale DEM image is compressed using an adaptive wavelet based image compression algorithm. The method, which is an extension of the progressive mesh compression takes advantage of the multiresolution property of the wavelets while coding the map images. This makes it possible to decode different resolutions of the map from the encoded bit stream providing a multiresolution display of a given map. Experimental results are presented. ©2009 IEEE.
Open Access
Unsupervised classification of remotely sensed images using Gaussian mixture models and particle swarm optimization
(IEEE, 2010) Arı, Çağlar; Aksoy, Selim
Gaussian mixture models (GMM) are widely used for un-supervised classification applications in remote sensing. Expectation-Maximization (EM) is the standard algorithm employed to estimate the parameters of these models. However, such iterative optimization methods can easily get trapped into local maxima. Researchers use population-based stochastic search algorithms to obtain better estimates. We present a novel particle swarm optimization-based algorithm for maximum likelihood estimation of Gaussian mixture models. The proposed approach provides solutions for important problems in effective application of population-based algorithms to the clustering problem. We present a new parametrization for arbitrary covariance matrices that allows independent updating of individual parameters during the search process. We also describe an optimization formulation for identifying the correspondence relations between different parameter orderings of candidate solutions. Experiments on a hyperspectral image show better clustering results compared to the commonly used EM algorithm for estimating GMMs. © 2010 IEEE.