Landslide detection using ALOS optical and radar data. A case study from the Ilia prefecture.

Στην εργασία αυτή παρουσιάζεται  η χρήση οπτικών δεδομένων καθώς και ραντάρ δεδομένων  από  το  δορυφόρο ALOS   για  τον  εντοπισμό  μίας  κατολίσθησης.  Ο δορυφόρος ALOS   διαθέτει  τρεις  δέκτες.  Έναν  παγχρωματικό  δέκτη  (PRISM)  που λαμβάνει στερεοεικόνες, ένα   πολυφασματικό δέκτη (AVNIR-2) και ένα δέκτη ραντάρ (PALSAR).   Η περιοχή μελέτης εντοπίζεται στη Δυτική Πελοπόννησο στην περιοχή της Ανδρίτσαινας και  συγκεκριμένα  στο  χωριό  Συκιές.  Η  περιοχή  υπέστη  σημαντικές καταστροφές  από  τις  πυρκαγιές  του  2007.  Σαν  αποτέλεσμα πολλές  κατολισθήσεις καταγράφησαν  τα επόμενα  χρόνια. Η  συγκεκριμένη κατολίσθηση  σημειώθηκε  τον Ιανουάριο του 2009 συνεπεία πολύ έντονων βροχοπτώσεων και χαρτογραφήθηκε στο πεδίο  με  χρήση DGPS   .  Η  δυνατότητα  εντοπισμού  της  κατολίσθησης  από  τα δορυφορικά δεδομένα ALOS  εξετάζεται στην παρούσα εργασία και παρουσιάζονται τα αποτελέσματα. Γίνεται χρήση τεχνικών συμβολομετρίας για την επεξεργασία τριάντα εικόνων ραντάρ καθώς και χρήση φωτογραμμετρικών τεχνικών για την επεξεργασία των στερεοσκοπικών οπτικών δεδομένων.In this study the usefulness of the ALOS optical and radar data for landslide monitoring  is  examined.  ALOS  contains  three  sensors,  commonly  referred  to  as  the “three eyes” of ALOS. These sensors are: the Panchromatic Remote-Sensing Instrument for Stereo Mapping (PRISM), the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2), and the Phased Array type L-band Synthetic Aperture Radar (PALSAR). The area of study is located in a small village named Sykies near to the city of Andritsena in Western Peloponnese. The area suffered during the last years from enormous fires. As a result many landslides have been recorded. One of the latest Landslides has been recorded on January 2009 as a consequence of heavy rains. That landslide was mapped in situ using differential GPS. The possibility of detecting and mapping the specific landslide using ALOS data is examined in this study and the results are presented. Thirty ALOS radar images within a period of three years, two ALOS Prism data sets and two ALOS AVNIR collected over the same area within a year were used

AMELIORATING THE SPATIAL RESOLUTION OF HYPERION HYPERSPECTRAL DATA. THE CASE OF ANTIPAROS ISLAND

In this study seven fusion techniques and more especially the Ehlers, Gram-Schmidt, High Pass Filter, Local Mean Matching (LMM), Local Mean and Variance Matching (LMVM), Pansharp and PCA, were used for the fusion of Hyperion hyperspectral data with ALI panchromatic data. The panchromatic data have a spatial resolution of 10m while the hyperspectral data have a spatial resolution of 30m. All the fusion techniques are designed for use with classical multispectral data. Thus, it is quite interesting to investigate the assessment of the common used fusion algorithms with the hyperspectral data. The study area is Antiparos Island in the Aegean Sea

Using remote sensing multispectral data and GIS techniques for the geological mapping of Halki Island

Στην εργασία αυτή παρουσιάζεται ο Γεωλογικός Χάρτης κλίμακας 1/50.000 Φύλλο "Νήσος  Χάλκη"  πουεκδόθηκε  από  το  ΙΓΜΕ.  Για  τη  δημιουργία  του  χάρτη  έγινε συνδυαστική χρήση δορυφορικών πολυφασματικών δεδομένων (Landsat TM   & ETM  and Terra    ASTER), και χαρτογράφησης στο πεδίο με χρήση DGPS   . Όλα τα δεδομένα εισήχθησαν στην ειδικά σχεδιασμένη γεωβάση του ΙΓΜΕ. Μετά τους απαραίτητους τοπολογικούς ελέγχους και τις αναγκαίες διορθώσεις τα δεδομένα ενοποιήθηκαν και έγινε η επεξεργασία τους με σκοπό τη δημιουργία του  τελικού χάρτη.In this paper we present the combined use of remote sensing and GIS techniques for the geological mapping of Halki Island at 1/50.000 scale. The geological formations, geotectonic units and tectonic structures were recognized in situ and mapped. Interpretation  of  multispectral  satellite  images  (Landsat  TM  &  ETM  and  Terra ASTER) has been carried out in order to detect the linear or not structures of the study area. Different band ratio was also used in order to distinguish and map the limits of the different geotectonic units. The in situ mapping was enhanced with data derived from the digital processing of the satellite data. All the analogical and digital data were imported in a geodatabase specially designed for geological data. After the necessary topological control and corrections, the data were unified and processed in order to create the final map layout at 1/50.000 scale.

On the Personalization of Personal Networks - Service Provision Based on User Profiles

In this paper, we present a user profile definition scheme featuring context awareness. Though the scheme has been designed to meet the needs of web applications deployed over heterogeneous devices, emphasis is given in the deployment of the profile scheme over Personal Networks (PNs), as the personalization of the deployed applications and services in PN environments is of great importance. The proposed scheme is presented as part of an integrated framework for user profile management that takes into account (and is therefore compliant to) the existing standardization attempts. The overall architecture and description of the profile management framework, taking into account security issues inside Personal Networks, is presented. The paper concludes by showcasing how user profiles have been incorporated in a selected pilot service of the EU IST research project MAGNET Beyond

Random Surfing Without Teleportation

In the standard Random Surfer Model, the teleportation matrix is necessary to ensure that the final PageRank vector is well-defined. The introduction of this matrix, however, results in serious problems and imposes fundamental limitations to the quality of the ranking vectors. In this work, building on the recently proposed NCDawareRank framework, we exploit the decomposition of the underlying space into blocks, and we derive easy to check necessary and sufficient conditions for random surfing without teleportation.Comment: 13 pages. Published in the Volume: "Algorithms, Probability, Networks and Games, Springer-Verlag, 2015". (The updated version corrects small typos/errors

Characterization of Stiffness and Damping in Textured Sector Pad Micro Thrust Bearings Using Computational Fluid Dynamics

In the present paper, a study of stiffness and damping in sector-pad micro thrust bearings with artificial surface texturing is presented, based on computational fluid dynamics (CFD) simulations. The bearing pads are modeled as consecutive three-dimensional independent microchannels, each consisting of a smooth rotating wall (rotor) and a partially textured stationary wall (stator). CFD simulations are performed, consisting in the numerical solution of the Navier-Stokes equations for incompressible isothermal flow. The goal of the present study is to characterize the dynamic behavior of favorable designs, identified in previous optimization studies, comprising parallel and convergent thrust bearings with rectangular texture patterns. To this end, a translational degree of freedom (DOF) along the thrust direction and a rotational (tilting) DOF of the rotor are considered. By implementing appropriate small perturbations around the equilibrium (steady-state) position and processing the simulation results, the stiffness and damping coefficients of the bearing are obtained for each DOF. The computed dynamic coefficients of textured thrust bearings are compared to those of conventional (smooth slider) designs. It is found that the dependence of bearing stiffness and damping on geometrical parameters exhibits the same trends for both DOFs. Both stiffness and damping are found to increase with bearing width. In general, increasing the bearing convergence ratio results in increased bearing stiffness and decreased damping. Finally, the present results demonstrate that properly textured parallel sliders are characterized by an overall dynamic performance that is superior to that of smooth converging sliders