Ferreira F.,CNR Institute of Electronics, Computer and Telecommunication Engineering |
Orsenigo F.,HCMR |
Veruggio G.,CNR Institute of Electronics, Computer and Telecommunication Engineering |
Pavlakis P.,HCMR |
And 2 more authors.
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2010
The article compares the performance of Feature Correlation and Phase Correlation algorithms for the motion estimation of an underwater vehicle. While feature correlation relies on the extraction and matching of features templates, Phase Correlation is a featureless approach, relying instead on the overall properties of the image. Three versions of Feature Correlation algorithm and two different implementations of the Phase Correlation algorithm are compared, on data collected by the HCMR Thetis submersible during the Nautilos Project in 2004; since the mission focused on different research priorities, the recordings are suboptimal regarding sea bottom mosaicking, featuring motion blurs, roll sweeps, geometric distortions and optical axis non-perpendicular to the bottom. The results show the effectiveness of feature correlation in dealing with blurred images, while in terms of computational time, both implementations of the phase correlation algorithm outperform any of the feature correlation algorithms by a large margin. © 2010 IFAC.
Gallart F.,IDAEA |
Prat N.,FEM |
Garca-Roger E.M.,FEM |
Latron J.,IDAEA |
And 19 more authors.
Hydrology and Earth System Sciences | Year: 2012
Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The structure and composition of biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. Therefore, the structural and functional characteristics of aquatic fauna to assess the ecological quality of a temporary stream reach cannot be used without taking into account the controls imposed by the hydrological regime. This paper develops methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the transient sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: Hyperrheic, Eurheic, Oligorheic, Arheic, Hyporheic and Edaphic. When the hydrological conditions lead to a change in the aquatic state, the structure and composition of the aquatic community changes according to the new set of available habitats. We used the water discharge records from gauging stations or simulations with rainfall-runoff models to infer the temporal patterns of occurrence of these states in the Aquatic States Frequency Graph we developed. The visual analysis of this graph is complemented by the development of two metrics which describe the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of temporary streams in four aquatic regimes in terms of their influence over the development of aquatic life is updated from the existing classifications, with stream aquatic regimes defined as Permanent, Temporary-pools, Temporary-dry and Episodic. While aquatic regimes describe the long-term overall variability of the hydrological conditions of the river section and have been used for many years by hydrologists and ecologists, aquatic states describe the availability of mesohabitats in given periods that determine the presence of different biotic assemblages. This novel concept links hydrological and ecological conditions in a unique way. All these methods were implemented with data from eight temporary streams around the Mediterranean within the MIRAGE project. Their application was a precondition to assessing the ecological quality of these streams. © Author(s) 2012.
News Article | November 1, 2016
Developed in the 1990s and early 2000s, LifeWatch is one of the large-scale European Research Infrastructures (ESFRI) created to support biodiversity science and its developments. Its ultimate goal is to model Earth's biodiversity based on large-scale data, to build a vast network of partners, and to liaise with other high-quality and viable research infrastructures (RI). Being one of the founding LifeWatch member states, Greece has not only implemented LifeWatchGreece, but it is all set and ready to "fulfill the vision of the Greek LifeWatch RI and establish it as the biodiversity Centre of Excellence for South-eastern Europe", according to the authors of the latest Biodiversity Data Journal's Editorial: Dr Christos Arvanitidis, Dr Eva Chatzinikolaou, Dr Vasilis Gerovasileiou, Emmanouela Panteri, Dr Nicolas Bailly, all affiliated with the Hellenic Centre for Marine Research (HCMR) and part of the LifeWatchGreece Core Team, together with Nikos Minadakis, Foundation for Research and Technology Hellas (FORTH), Alex Hardisty, Cardiff University, and Dr Wouter Los, University of Amsterdam. Making use of the technologically advanced open access Biodiversity Data Journal and its Collections feature, the LifeWatchGreece team is publishing a vast collection of peer-reviewed scientific outputs, including software descriptions, data papers, taxonomic checklists and research articles, along with the accompanying datasets and supporting material. Their intention is to demonstrate the availability and applicability of the developed e-Services and Virtual Laboratories (vLabs) to both the scientific community, as well as the broader domain of biodiversity management. The LifeWatchGreece Special Collection is now available in Biodiversity Data Journal, with a series of articles highlighting key contributions to the large-scale European LifeWatch RI. The Software Description papers explain the LifeWatchGreece Portal, where all the e-Services and the vLabs provided by LifeWatchGreece RI are hosted; the Data Services based on semantic web technologies, which provide detailed and specialized search paths to facilitate data mining; the R vLab which can be used for a series of statistical analyses in ecology, based on an integrated and optimized online R environment; and the Micro-CT vLab, which allows the online exploration, dissemination and interactive manipulation of micro-tomography datasets. The LifeWatchGreece Special Collection also includes a series of taxonomic checklists (preliminary, updated and/or annotated); a series of data papers presenting historical and original datasets; and a selection of research articles reporting on the outcomes, methodologies and citizen science initiatives developed by collaborating research projects, which have shared human, hardware and software resources with LifeWatchGreece RI. LifeWatchGreece relies on a multidisciplinary approach, involving several subsidiary initiatives; collaborations with Greek, European and World scientific communities; specialised staff, responsible for continuous updates and developments; and, of course, innovative online tools and already established IT infrastructure. Arvanitidis C, Chatzinikolaou E, Gerovasileiou V, Panteri E, Bailly N, Minadakis N, Hardisty A, Los W (2016) LifeWatchGreece: Construction and operation of the National Research Infrastructure (ESFRI). Biodiversity Data Journal 4: e10791. https:/ This work has been supported by the LifeWatchGreece infrastructure (MIS 384676), funded by the Greek Government under the General Secretariat of Research and Technology (GSRT), ESFRI Projects, National Strategic Reference Framework (NSRF).
Moncheva S.,Institute of Oceanology BAS |
Pantazi M.,HCMR |
Pautova L.,Russian Academy of Sciences |
Boicenco L.,NIMRD Grigore Antipa |
And 2 more authors.
Turkish Journal of Fisheries and Aquatic Sciences | Year: 2012
The quality of biological data has gained recognition as an essential part of international monitoring programmes, in response to the demand for strategic environmental evaluations such as the EU WFD, the MSFD and informed decisions for environmental sound management. The paper presents the results of an intercalibration exercise among four Black Sea phytoplankton laboratories (NIMRD-RO, IBSS-UKR, IO-RAS - RUS and IO-BAS - BLG) conducted under SESAME FP6 Project with the objectives: 1) to assess the degree of comparability of phytoplankton and chlorophyll a data produced by routine in-house methods; 2) to formulate recommendations for progress towards harmonization of the research methodology in the Black Sea. The statistical treatment of the results reveal that at the level of total phytoplankton abundance and biomass as well as chlorophyll a the data were in a good agreement, while for some taxonomic classes (Prymnesiophyceae and small flagellates) the differences were significant. The counted sample volume proves essential for detection of species diversity and the methods of species specific biovolume measurements - for the total biomass. As a follow up Guidelines for QC/QA of phytoplankton data and check-list with suggested shapes for biovolume calculation were produced under UP-Grade Black Sea SCENE FP7 Project that offer key options for progress. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey.
Favali P.,Instituto Nazionale Of Geofisica |
Beranzoli L.,INGV |
Materia P.,INGV |
Picard J.B.,French Research Institute for Exploitation of the Sea |
And 17 more authors.
MTS/IEEE OCEANS 2015 - Genova: Discovering Sustainable Ocean Energy for a New World | Year: 2015
EMSO (European Multidisciplinary Seafloor and water-column Observatory; http://www.emso-eu.org) is a large-scale European Research Infrastructure (RI) of the ESFRI roadmap composed of fixed-point, seafloor and water-column observatories with the basic scientific objective of near- and realtime, long-term monitoring of environmental processes related to the interaction between the geosphere, biosphere, and hydrosphere. It is geographically distributed in key sites of European waters, spanning from the Arctic, through the Atlantic and Mediterranean Sea to the Black Sea. © 2015 IEEE.
Delfanti R.,ENEA |
Ozsoy E.,METU - MEMS Center |
Kaberi H.,HCMR |
Schirone A.,ENEA |
And 5 more authors.
Journal of Marine Systems | Year: 2014
The vertical profiles of 137Cs were determined in the North Aegean, Marmara and Black Seas, to assess inventories and fluxes of the radionuclide in these basins. The inventory of 137Cs in the Western Black Sea integrated from the surface down to 400m water depth is 3.4±0.1kBqm-2, which is surprisingly close to the amount determined in 1988, decay corrected to 2007 (2.9±0.1kBqm-2). On the other hand, based on the comparison of profiles roughly 20years apart, it is estimated that about 1kBqm-2 has been transferred from above the halocline to depths below the halocline, emphasizing the effective redistribution of tracers within the same period. We estimate that about 12TBqy-1 of 137Cs presently leaves the Black Sea with the upper layer flow through the Bosphorus and only 2TBqy-1 is returned with the lower layer inflow of Mediterranean water from the Marmara Sea. Accounting for river fluxes, estimated on the order of 2TBqy-1 few years after the Chernobyl accident, and possibly decreased by now, we can thus estimate a net rate of loss of about 8-10TBqy-1.Investigating the effective redistribution in the upper water column, the supply by the inflowing Mediterranean water alone does not explain the increase of 137Cs concentration and inventory at intermediate depths in the Western Black Sea. The most important mechanism transferring 137Cs and dissolved contaminants from the surface water to the sub-pycnocline layer appears to be the turbulent entrainment of a larger quantity of Black Sea water into the inflowing plume of Mediterranean water through mixing processes on the southwestern shelf and continental slope following its exit from the Bosphorus. This process produces an extra export of some10TBqy-1 of 137Cs from the surface to the sub-pycnocline depths of the Black Sea, a quantity comparable in magnitude to the total export out from the basin. It is the entrainment flux resulting from the mixing, and the further advection and penetration of this water into the Black Sea deeper layer (200-600m) that seems to maintain the inventory with little change over time. Through these two processes the Black Sea surface layer (0-50m) loses every year about 4% of its total inventory of 137Cs. © 2013 Elsevier B.V.
Tzoraki O.,University of Aegean |
De Girolamo A.-M.,CNR Institute of Neuroscience |
Gamvroudis C.,Technical University of Crete |
International Journal of River Basin Management | Year: 2016
A new approach, the ‘Naturalness Status' (NS), is suggested to classify the hydrologic alteration of temporary rivers from natural conditions based on the Hydrological Status Tool (HS-Tool). The HS-Tool considers two metrics: the degree and the predictability of dry flow conditions for both natural flow and its alterations, at each water body in actual and natural conditions. The Soil and Water Assessment Tool (SWAT) model is simulating the river flow of Evrotas water bodies, Greece, under natural, actual and climate-impacted conditions. The majority of Evrotas water bodies (72%) experience good (low-impacted) NS for the examined period (1990–2010), despite their intermittent flow regime. Severe flow alteration is predicted for 57% of Evrotas water bodies (high-impacted NS), while selecting the KNMI-RACMO2 future climate projections scenario (2020–2060) as input into the SWAT model. Hydrologic extreme drought phenomena or anthropogenic pressures in water regime can be quantified by the NS. The method is intended to be used in basin decision-making analysis at fulfilling the Water Framework Directive goals. © 2015 International Association for Hydro-Environment Engineering and Research.
PubMed | HCMR and FORTH Institute of Computer Science
Type: | Journal: Biodiversity data journal | Year: 2016
Biodiversity data is characterized by its cross-disciplinary character, the extremely broad range of data types and structures, and the variety of semantic concepts that it encompasses. Furthermore there is a plethora of different data sources providing resources for the same piece of information in a heterogeneous way. Even if we restrict our attention to Greek biodiversity domain, it is easy to see that biodiversity data remains unconnected and widely distributed among different sources.To cope with these issues, in the context of the LifeWatch Greece project, i) we supported cataloguing and publishing of all the relevant metadata information of the Greek biodiversity domain, ii) we integrated data from heterogeneous sources by supporting the definitions of appropriate models, iii) we provided means for efficiently discovering biodiversity data of interest and iv) we enabled the answering of complex queries that could not be answered from the individual sources. This work has been exploited, evaluated and scientificaly confirmed by the biodiversity community through the services provided by the LifeWatch Greece portal.
Kontoyiannis H.,HCMR |
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011
The East Mediterranean deep thermohaline cell is a series of processes that refer to the water sinking during winter at specific locations and the subsequent spreading that fills the deep near-bottom layers of the East Mediterranean with oxygen-rich water masses. These waters tend to preserve the hydrologic characteristics (temperature, salinity, and transparency) of their formation region. Hydrographic sections offshore from Cape Passero (west Ionian Sea) and near the southwest tip of Peloponnisos (east Ionian Sea), in the framework of the deep-neutrino-telescope-related KM3net program, cut through a bottom plume of Adriatic water at ∼3500 m in the southwest Ionian and a deep vein at ∼3200 m of Cretan water in the southeast Ionian. In the period 20062009, the Adriatic plume, originally characterized by a strong signal of locally higher salinity and oxygen and lower transparency in the near-bottom 500 m, tends to weaken and shrink within the near-bottom ∼200 m in 2009. This weakening trend may be associated with the relatively warm/mild winters following 2006. It may be typical inter-annual variability or a signature of global warming in which case an expected prolonged continuation can potentially affect the deep oxygen supply. © 2010 Elsevier B.V. All rights reserved.
Ferreira F.,CNR Institute of Neuroscience |
Orsenigo F.,HCMR |
Veruggio G.,CNR Institute of Neuroscience |
Pavlakis P.,HCMR |
And 2 more authors.
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2010
The performance of different visual approaches for estimating the motion of an underwater Remotely Operated Vehicle (ROV) is discussed. The paper compares three different techniques: feature correlation, Speeded Up Robust Features (SURF), both based on feature extraction and matching, and phase correlation, which instead does not rely on image features. The three algorithms accuracy and performance are compared using a batch of data collected in typical operating conditions with the Romeo ROV. In estimating vehicle speed, phase correlation outperformed SURF in terms of robustness and precision, giving similar results to those obtained with feature correlation. In terms of computational time, phase correlation outperformed both feature-based methods.