Wave field mapping with particle image velocimetry     

Dimitris Stagonas  Gerald Müller   《Ocean Engineering》2007,34(11-12):1781-1785

A number of different methods for the 3D measurement of the water surface in wave fields have been proposed in the literature, based mostly on refraction, photogrammetry and/or reflected light intensity. Although these methods can map the distorted water surface, they appear to be difficult in practical applications in hydraulic engineering laboratories. A novel wave mapping technique using particle image velocimetry to measure surface flow velocities, and linear wave theory to determine wave heights from the measured velocities, has been developed and validated for regular waves. The method allows for the mapping even of complex wave fields with simple means and appears robust enough for application in the laboratory.  相似文献   

Scour effects in piled structures—A sensitivity analysis     

Dimitris Diamantidis  Knut Arnesen 《Ocean Engineering》1986,13(5)

A sensitivity analysis is presented in this paper to judge the importance of several parameters influencing scour effects on piles of offshore foundations. The decrease of the pile reliability due to scour is also studied by applying the first-order reliability method. Suggestions for lateral pile resistance in design are included.  相似文献   

Shear-wave Velocity Structure around Teide Volcano: Results Using Microtremors with the SPAC Method and Implications for Interpretation of Geodetic Results     

Francisco J. Chávez-García  Francisco Luzón  Dimitris Raptakis  José Fernández 《Pure and Applied Geophysics》2007,164(4):697-720

Deformation analysis and simulation of volcanic edifices require the construction of models of elastic properties of those structures. In this paper we present an analysis of microtremor measurements recorded during the performance tests of two temporary seismic arrays installed in the eastern portion of the Teide caldera in 1994. We take advantage of recent developments of the SPAC method and use spatial cross-correlation computations to estimate phase velocity dispersion of Rayleigh waves at the location of the arrays. We show that the extension of the standard SPAC method is valid in the case of our data, justifying its use and supporting the generalization of the SPAC method to single station pairs. The phase velocity dispersion curve obtained was inverted to recover the shear-wave profile at the site of the arrays. Our results indicate that the subsoil structure of the caldera is laterally homogeneous at the scale of a few km about the location of the arrays. We obtained about 315 m of volcanic sediments overlying rocks with a shear-wave velocity of 2 km/s. These results are robust and are a starting point to further modelling of deformation, permanent or transient, at this volcanic edifice, which can be useful in the interpretation of different observed fields. In fact, the computation of deformations and gravity changes due to possible volcanic intrusions in two models; one considering the volcanic sediments and the other without considering them, provided different results in the near field.  相似文献   

Hydrodynamic features of the South Aegean Sea as derived from Argo T/S and dissolved oxygen profiles in the area     

Dimitris Kassis  Evangelia Krasakopoulou  Gerasimos Korres  George Petihakis  George S. Triantafyllou 《Ocean Dynamics》2016,66(11):1449-1466

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Energy poverty in Greek mountainous areas: a comparative study   总被引：1，自引：1，他引：0  

Lefkothea Papada  Dimitris Kaliampakos 《山地科学学报》2017,14(6):1229-1240

The paper studied the energy poverty in the mountainous areas of Greece through parallel primary surveys, in comparison with the country-level conditions. The surveys are based on objective financial and expenditure data as well as on subjective views about housing conditions. The objective approach showed that mountainous areas of Greece are burdened with much higher energy expenditure while also having lower annual incomes. Under these circumstances, the energy poverty rate skyrocketed to 73.5%. The subjective indicators reveal significant aspects of the problem, such as the intense problem of damp walls and mold growth at home or the restriction of other basic needs in order to cover heating needs. However, despite the proven high vulnerability of Greek mountainous areas, current energy policy actually ignores the special features of mountainous areas, implementing horizontal policies. Therefore, a specialized energy plan targeted to alleviating energy poverty in mountainous areas in Greece is an urgent imperative.  相似文献   

Macrobenthic community structure over the continental margin of Crete (South Aegean Sea, NE Mediterranean)     

Anastasios Tselepides  Konstantia-N. Papadopoulou  Dimitris Podaras  Wanda Plaiti  Drosos Koutsoubas 《Progress in Oceanography》2000,46(2-4)

Macrobenthic faunal composition, abundance, biomass and diversity together with a suite of sedimentary environmental parameters were investigated on a seasonal basis in order to determine factors regulating faunal distribution over the oligotrophic continental margin of the island of Crete (South Aegean Sea, North Eastern Mediterranean). Macrofaunal species composition was similar to that of the western Mediterranean and the neighboring Atlantic having several common dominant species. Mean benthic biomass, abundance and diversity decreased with depth, with a major transition zone occurring at 540 m, beyond which values declined sharply. At comparable depths biomass and abundance values were considerably lower to those found in the Atlantic, high-lighting the extreme oligotrophy of the area. The continental margin of Crete was characterised by a high diversity upper continental shelf environment (dominated by surface deposit feeding polychaetes) and a very low diversity slope and deep-basin environment (dominated by carnivorous and filter feeding polychaetes). Classification and ordination analyses revealed the existence of four principle clusters divided by a faunal boundary between 200 and 540 m, as well as beyond 940 m depth. Significant correlations between macrofauna and sediment parameters led to the conclusion that besides depth, food availability (as manifested by the concentration of chloroplastic pigments) is the principle regulating factor in the system. Such being the case, the prevailing hydrographic features that structure the pelagic food web and are directly responsible for the propagation of organic matter to the benthos also affect its community structure.  相似文献   

Safety level of damaged RoPax ships: Risk modelling and cost-effectiveness analysis     

Luis Guarin  Dimitris Konovessis  Dracos Vassalos 《Ocean Engineering》2009,36(12-13):941-951

This paper elaborates on results of a recent risk analysis study for RoPax vessels, carried out as part of the activities of the SAFEDOR Integrated Project, targeting possible improvements on safety levels following large scale flooding. The study is based on a comprehensive analysis of accident statistics for the period 1994–2004, through which a high-level risk model (in the form of event trees) is established. This is then used to determine the current safety level of RoPax vessels (in various risk metrics, such as individual risk, potential loss of life and on an F–N curve), reconfirming that even though safety levels are improving, risk is still “high in the ALARP region”. In search of ways to further improve the situation possible risk control options are examined, by performing a sensitivity analysis on the effects of the Attained Index of Subdivision A onto the safety levels and by evaluating their cost-effectiveness.  相似文献   

Last glacial geomorphologic records in Mt Chelmos,North Peloponnesus,Greece     

Kosmas Pavlopoulos  Aris Leontaritis  Constantin D. Athanassas  Chara Petrakou  Dimitris Vandarakis  Kosnstantinos Nikolakopoulos  Leonidas Stamatopoulos  Katherina Theodorakopoulou 《山地科学学报》2018,15(5):948-965

This study deals with the analysis of the glacial processes that have affected the relief of Mt Chelmos in northern Peloponnesus, Greece during middle and Late Pleistocene. The goal was to compile a combined geomorphological-geological map of the study area which would enable the chronological stratification of the glacial landforms cropping up on Mt. Chelmos. Chronological stratification was further aided by optically stimulated luminescence (OSL) dating. The map served as the basis upon which the reconstruction and discussion on the phases of the Middle-Late Quaternary paleoclimatic history of Mt. Chelmos have been made. A sophisticated semiautomated method was first used to analyze the Digital Elevation Model (DEM), combined with Aster, Quickbird and ALOS imagery in order to identify glacial and periglacial, as well as karstic features. Then, these features along with other nonrecognizable features from the remote-sensing images were documented in the field. In this way, several glacial landforms were identified, such as moraines and cirques, indicating extended glaciation phases during the middle and Late Pleistocene. Additionally, a ground moraine located at an altitude of 1900-2050 m, within the Spanolakos glacial valley, was dated using the OSL-dating method. The resulting ages indicate a phase of glacier advance/stabilization during MIS-5b (89-86 ka), which is in consistence with pollenrecord evidence from Greece and the Mediterranean.  相似文献   

Ca(OH)2 Pre‐Treated Bentonite for Phosphorus Removal and Recovery From Synthetic and Real Wastewater          下载免费PDF全文

Giorgos Markou  Dimitris Mitrogiannis  Vassilis Inglezakis  Koenraad Muylaert  Nikolaos Koukouzas  Nikolaos Tsoukalas  Efstratios Kamitsos  Dimitrios Palles  Ioannis Baziotis 《洁净——土壤、空气、水》2018,46(2)

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Assessing the economic value of vernacular architecture of mountain regions using contingent valuation     

Stella GIANNAKOPOULOU  Dimitris DAMIGOS  Dimitris KALIAMPAKOS 《山地科学学报》2011,8(5):629-640

Human pressure on mountain resources poses certain threats to their natural and man-made environment. Although there are many parameters involved, one of the driving forces behind this situation is the emphasis given so far only to the market value of mountain goods and services, ignoring the true social and environmental costs of using mountain resources. Towards this direction, the use of non-market valuation techniques could prove to be beneficial. Bearing in mind the above remarks, the paper presents an application of the Contingent Valuation Method, which aims at estimating the monetary value of a mountain settlement’s vernacular architecture, namely Metsovo. For this purpose, the survey focuses on Metsovo visitors’ willingness to pay a single annual voluntary contribution to an institution that would be founded in order to undertake all necessary actions required to preserve the town’s traditional character. The results are very promising and indicate that vernacular architecture holds a significant economic value that could justify the implementation of appropriate policies towards the protection of vernacular settlements in mountain areas.  相似文献