Dragan Blagojevic | Beogradski Univerzitet (original) (raw)

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Papers by Dragan Blagojevic

International Association of Geodesy symposia, 2015

Station coordinates of a Local GPS permanent network (National permanent network of Serbia – AGRO... more Station coordinates of a Local GPS permanent network (National permanent network of Serbia – AGROS and national permanent network of Former Yugoslav Republic of Macedonia – MAKPOS) were computed and expressed by aligning them to ITRF2005 using selected high quality Eurasian Plate EPN stations that were included in the GPS processing, which form part of the ITRF2005 realization. By application of transformation formulae, this network solution was transformed into ETRF2000. The minimum constraints approach has been applied preserving original characteristic of the local GPS solution, and in the same time, the local GPS solution was expressed in the regional reference frame through the mathematical definition of the ETRS89.

Geofizika, 2017

This paper is dedicated to modeling extreme TEC (Total Electron Content) values at the territory ... more This paper is dedicated to modeling extreme TEC (Total Electron Content) values at the territory of Serbia. For the extreme TEC values, we consider the maximum values from the peak of the 11-year cycle of solar activity in the years 2013, 2014 and 2015 for the days of the winter and summer solstice and autumnal and vernal equinox. The average TEC values between 10 and 12 UT (Universal Time) were treated. As the basic data for all processing, we used GNSS (Global Navigation Satellite System) observation obtained by three permanent stations located in the territory of Serbia. Those data, we accept as actual, i.e. as a "true TEC values". The main objectives of this research were to examine the possibility to use two machine learning techniques: neural networks and support vector machine. In order to emphasize the quality of applied techniques, all results are adequately compared to the TEC values obtained by using International Reference Ionosphere global model. In addition, we separately analyzed the quality of techniques throughout temporal and spatial-temporal approach.

Geophysical Research Letters, Feb 12, 2021

California, with its mild wet winters and hot dry summers, experiences a Mediterranean type clima... more California, with its mild wet winters and hot dry summers, experiences a Mediterranean type climate, similar to the Mediterranean region, South Africa, central Chile, and Southwest Australia. With overall semi-arid conditions resulting from highly seasonal precipitation, water shortage has always been a major societal concern in these regions. Also increasing concentrations of greenhouse gases (GHGs) and general subtropical drying led to even more severe water shortages in several Mediterranean-type climates (

Springer eBooks, Nov 27, 2012

The paper presents preliminary results of coordinate time series analysis in Serbian network of p... more The paper presents preliminary results of coordinate time series analysis in Serbian network of permanent GNSS stations. Analysis methodology is outlined and resulting station velocities are briefly commented. Despite the short time span used, the crustal deformation trend was clearly identified, confirming the potential of the network of permanent stations for local and regional geodynamical studies.

Geografie, 2016

This study considers the spatial and temporal dimensions of demographic trends in Serbia between ... more This study considers the spatial and temporal dimensions of demographic trends in Serbia between 1961 and 2010. Using appropriate spatial autocorrelation statistics, spatial patterns of common demographic indicators including changes in population size, the rate of natural increase and infant mortality rate are investigated across municipalities of Serbia. Also, the impact of differential demographic rates according to ethnic origin on forming spatial clusters is implicitly considered. Different stages of demographic transition across municipalities at the start of the analyzed period determined the spatial pattern of clustered subregions; ethnic origin appeared to be a strong factor of differentiation regarding population dynamics. The two opposed areas regarding the transition of rates of natural increase and infant mortality were clustered; the southern included Kosovo and the least developed subregions of Central Serbia. The City of Belgrade and Kosovo have been the two hubs of ...

Survey Review, Jun 24, 2020

Horizontal coordinates transformation and residuals modelling on the territory of the Republic of... more Horizontal coordinates transformation and residuals modelling on the territory of the Republic of Srpska The paper describes the optimal model for coordinate transformation between ETRS89 and old national reference system in the Republic of Srpska. The Helmert`s parameters were estimated, based on a set of 1 741 common points. The average magnitude of residuals was 0.3 m per coordinate and the residual vectors were homogeneous at the local level. The basic model was complemented by a corrections grid that uses bilinear interpolation. The accuracy of the transformed horizontal positions obtained by this model is about 10 cm. In this way, a link between the ETRS89 and local reference system has been established on the overall territory of the Republic of Srpska.

The paper provides an overview of height and gravity reference systems of Europe and a brief desc... more The paper provides an overview of height and gravity reference systems of Europe and a brief description of their implementation. For each system we have given definitions of the system, as well as changes in definitions over time. In paper we have briefly described European Vertical Reference System-EVRS, United European Leveling Network-UELN, European Vertical Reference Network as well as densification action - EUVN_DA. Gravimetric reference systems are described by the Potsdam reference system, through a system IGSN71 (International Gravity Standardization Network 1971), as well as a series of actions aimed at defining a new gravity reference systems of Europe.U radu je dat pregled visinskih i gravimetrijskih referentnih sistema Evrope i kratak opis njihovih realizacija. U opisu svakog sistema date su definicije sistema, kao i promene definicija u vremenu. U pogledu visinskih sistema i mreža dati su kratki opisi EVROPSKOG VERTIKALNOG REFERENTNOG SISTEMA (European Vertical Referen...

Geodetska sluba, 2010

Page 1. Геодетска служба бр. 113 35 ВЕРТИКАЛНИ И ГРАВИМЕТРИЈСКИ РЕФЕРЕНТНИ СИСТЕМИ ЕВРОПЕ Др Драг... more Page 1. Геодетска служба бр. 113 35 ВЕРТИКАЛНИ И ГРАВИМЕТРИЈСКИ РЕФЕРЕНТНИ СИСТЕМИ ЕВРОПЕ Др Драган Благојевић 1 Др Олег Одаловић 2 Ненад Тесла, дипл.геод.инж.23 Владимир Миленковић , дипл.геод.инж.4 ...

Geodetska sluba, 2007

Page 1. Приказ књиге Др Драган Благојевић, др Бранислав Бајат 50 _____ Геодетска служба 107/2007 ...

Geodetski vestnik, 2016

To understand general ionosphere properties over Serbia, an analysis of temporal and spatial iono... more To understand general ionosphere properties over Serbia, an analysis of temporal and spatial ionosphere Total Electron Content (TEC) over the region was performed. The present research focuses on daily, seasonal and spatial ionosphere variations, based on TEC series calculated from the GNSS ie. GPS measurements. This analysis provides for characterization of ionosphere nature and fine structure over Serbia, both locally and regionally. For the days with high solar activity changes of TEC values ranges from minimum 4 Total Electron Content Units (TECU), in night hours, up to 55 TECU around the noon. It is shown that that changes are equivalent to the to the delay of GPS signals approximately 8.8 m in in vertical direction during the (maximum) daily conditions and the delay of 0.6 m during the (minimum) night conditions. Also, it is shows that a seasonal TEC differences follows directly Son activity during the seasons, and maximal differences of TEC values between the seasons reaching values of 45 TECU, again in the years of high Son's activities. For spatial changes all gained results indicate that there exist changes in all directions which cannot be recognized as constant bias or a trend.

Topography has a great influence on many characteristics which are connected to the distinct area... more Topography has a great influence on many characteristics which are connected to the distinct area on Earth such as hydrology, microclimate characteristics, vegetation cover properties, geological structures, mineral deposits, plant characteristic etc. Digital terrain models represent segments of spatial data bases related to presentation of terrain features and landforms. Square grid elevation models (DEMs) have emerged as the most widely used structure during the past decade because of their simplicity and simple computer implementation. They have become an important segment of Topographic Information Systems (TIS), storing natural and artificial landscape in forms of digital models. This kind of data structure is especially suitable for morphometric terrain evaluation and analysis which is very important in modeling Earth surface and atmospheric processes or environmental modeling applications. Treating topographic parameters like slope, aspects and terrain curvature as the first ...