Time filter

Source Type

Julea A.,Romanian Space Science Institute | Julea A.,European Commission - Joint Research Center Ispra | Julea T.,Romanian Space Science Institute | Ionescu C.,Romanian Space Science Institute | And 2 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

The temporal evolution of pixel values in Satellite Image Time Series (SITS) is considered criterion for the characterization, discrimination and identification of terrestrial objects and phenomena. Due to the exponential behavior of sequences number with specialization, Sequential Data Mining techniques need to be applied. The spatial aspect of the data was taken into account by the introduction of connectivity measures that characterize the pixels tendency to form objects. The conjunction of corresponding Connectivity Constraints (CC) with the Support Constraint (SC) leads to the extraction of Grouped Frequent Sequential Patterns (GFSP), a concept with proved capability for preliminary description and localization of terrestrial events. This work is focused on efficient SITS extraction of evolutions that fulfil SC and CC. Experiments performed on Bucharest urban interferometric SITS are used to illustrate the potential of the approach to find interesting evolution patterns. © 2014 IEEE.

Cucu-Dumitrescu C.,Advanced Studies and Research Center
IEEE Geoscience and Remote Sensing Letters | Year: 2014

This letter presents a technique to derive cloud-and shadow-masks from satellite images. The technique is based on a mutual confirmation algorithm that uses all available solar bands, but no thermal infrared bands. The process of mutual confirmation consists of first searching and then identifying partial geometrical overlap between first-guess (preliminary) bright (cloud candidates) and associated dark (cloud shadow candidates) pixels in the image. The thresholds needed for the algorithm to operate are adjusted dynamically and are scene dependent, but need no additional information about radiometric calibration or solar geometry. The algorithm's success rate (percentage of correct classification compared to a manual/visual mask) when applied on a handful of Landsat-5 scenes is found to exceed 95% for cloud pixels and 90% for shadow pixels. © 2013 IEEE.

Poenaru V.D.,Romanian Space Agency | Poenaru V.D.,University of Agronomical Sciences and Veterinary Medicine | Badea A.,Romanian Space Agency | Badea A.,University of Agronomical Sciences and Veterinary Medicine | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Mining is an important activity contributing to the economic development with long lasting environmental impacts. A major disaster took place in 2001 in Ocnele Mari salt mining area located in the central-south part of Romania when the artificial lake brine was poured in rural areas, devastating homes and polluting the Olt River. Towards a sustainable and harmonious development of the Ocnele Mari area, the Romanian Authorities decided to ecology and rehabilitate it. This ongoing project is focused on land degradation monitoring from 2001 disasters until now. High Resolution Spotlight TerraSar-X synthetic aperture radar data acquired within TerraSAR-X proposal LAN0778 are used to analyze terrain deformation by interferometric techniques knowing the mine subsidence is not constant; periods of relative stability are followed by quick deformation. The rocks forming in the region situated above the salt cushion have very low mechanical resistance and high intergranular fissured permeability so the hill's slopes are affected by landslides which are reactivated periodically. Additionally, analysis of the vegetation coverage (leaf area index and normalized difference vegetation index) from the optical data gathered by different sensors such as LANDSAT and MODIS combined with the meteorological data (temperature, wind speed, humidity and solar radiation) provide indicators for the land degradation. The results will be validating on ancillary data. Satellite derived information in conjunction with in-situ measurements can provide valuable information for existing conservation development models for defining the essential elements of a planning process designed to maximize the values provided by salt ponds from Ocnele Mari. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Poncos V.,Advanced Studies and Research Center | Teleaga D.,Advanced Studies and Research Center | Boukhemacha M.A.,Technical University of Civil Engineering Bucharest | Toma S.A.,Advanced Studies and Research Center | Serban F.,Advanced Studies and Research Center
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

This work focuses on monitoring the ground motion and infrastructure stability in an urban environment, namely in the city of Bucharest. Bucharest is a fast developing city with the average construction rate of 8-20% new buildings with respect to the existing ones. Consequently, the civil engineering industry faced new challenges related to the need of having taller buildings with deeper underground levels, a developing network of subway lines and more bridges with large diameter piles' foundations. All these new works have an important impact upon the upper ground stability. The PSI (Persistent Scatterer Interferometry) technique is used to extract the ground deformation in Bucharest from archived C-band ESA data and from more recent TerraSAR-X data. The conducted analysis constitutes historical case studies for Bucharest City covering the intervals 1992-1999, 2003-2009 and 2011-2012. © 2014 IEEE.

Munteanu E.,Advanced Studies and Research Center | Ursu L.,National Institute for Aerospace Research Elie Carafoli
UPB Scientific Bulletin, Series D: Mechanical Engineering | Year: 2010

The present work continues some recent researches of the authors ([1], [2]) in the vibration active control domain for a composite wing model by using MFC (Macro-Fiber-Composite) piezo actuators. The robustness characteristics of the optimal control LQR (Linear Quadratic Regulator) are recovered by the Kalman filter applying a special construction for the estimator. The obtained control law is called LQG/LTR (Linear Quadratic Gaussian/Loop Transfer Recovery). Moreover, including an internal model in the compensator of the system confers more robustness properties and remarkable performances.

Poncos V.,Advanced Studies and Research Center | Teleaga D.,Advanced Studies and Research Center | Bondar C.,National Research and Development Institute for Marine Geology and Geoecology | Oaie G.,National Research and Development Institute for Marine Geology and Geoecology
Journal of Hydrology | Year: 2013

In this work, an interferometric ALOS PalSAR dataset acquired between 2007 and 2010 is used to measure water level changes for the first time within a hydrographical unit of the Danube Delta in Romania at the Black Sea. When the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique was applied, it revealed a previously unknown and spectacular dynamic of the water levels in Danube Delta. The results are presented in the form of water level change maps for different periods of time. The DInSAR measurements for a number of locations are compared with extrapolated water level change values obtained from an existing mathematical model of the hydrological regime in the Danube Delta. The comparison shows a very good correlation between DInSAR measurements and the mathematical model, showing that this method using L-band ALOS PalSAR data and applied to a wetland area of Danube Delta can be used to increase the spatial density of water level measurements and contributes to a better understanding of hydrological processes. © 2013 Elsevier B.V.

Cucu-Dumitrescu C.,Advanced Studies and Research Center | Teleaga D.,Advanced Studies and Research Center | Serban F.,Advanced Studies and Research Center
2012 9th International Conference on Communications, COMM 2012 - Conference Proceedings | Year: 2012

SAR scenes are different from optical satellite images, with a strange look for the non-specialists. The objects from the ground are sometimes difficult to be told apart, even by a trained eye. A well known trademark of the SAR scenes is the noisy like appearance (speckle or salt & pepper effect). What we demonstrate is that, even in these twisted conditions, a straightforward segmentation is still possible, if the initial scene is properly preprocessed and an adapted algorithm is applied. © 2012 IEEE.

Zavalan L.,Polytechnic University of Bucharest | Teleaga D.,Advanced Studies and Research Center | Stoia-Djeska M.,Polytechnic University of Bucharest
AIP Conference Proceedings | Year: 2013

This paper investigates the pseudo-compressibility method for the incompressible Euler equations with a FVPM (Finite-Volume-Particle Method) discretization. The code uses Roe's upwind method with a Linear Data Reconstruction for the convective terms. The study focuses on the verification of the code. The method of manufactured solutions is used to examine the global discretization error and to verify the order of accuracy. © 2013 AIP Publishing LLC.

Sterian S.,Polytechnic University of Bucharest | Teleaga D.,Advanced Studies and Research Center | Zavalan L.,Advanced Studies and Research Center
Applied Mechanics and Materials | Year: 2014

This paper presents an application of the Finite Volume Particle Method to incompressible flows. The two-dimensional incompressible Navier-Stokes solver is based on Chorin’s projection method with finite volume particle discretization. The Finite Volume Particle Method is a meshless method for fluid dynamics which unifies advantages of particle methods and finite volume methods in one scheme. The method of manufactured solutions is used to examine the global discretization error and finally a comparison between finite volume particle method simulations of an incompressible flow around a fixed circular cylinder and the numerical simulations with the CFD code ANSYS FLUENT 14.0 is presented. © (2014) Trans Tech Publications, Switzerland.

Munteanu E.,Advanced Studies and Research Center
Control Engineering and Applied Informatics | Year: 2010

The paper presents a possible way to obtain a numerical model for structural vibration active control. Using data and analysis results from different commercial software tools, such as ANSYS, ZAERO and MATLAB, one can find an optimal model to test the system dynamic response and design an active control law. Different algorithms for resolving the eigenvalue problem and different methods for system order reduction are presented here. A wing composite model as a representative aerospace structure is design and numerical tested for flutter.

Loading Advanced Studies and Research Center collaborators
Loading Advanced Studies and Research Center collaborators