Interactive visual analytics of hydrodynamic flux for the coastal zone     

Richard L. S. F. George  Peter E. Robins  Alan G. Davies  Panagiotis D. Ritsos  Jonathan C. Roberts 《Environmental Earth Sciences》2014,72(10):3753-3766

Researchers wish to study the potential impact of sea level rise from climate change, and visual analytic tools can allow scientists to visually examine and explore different possible scenarios from simulation runs. In particular, hydrodynamic flux is calculated to understand the net movement of water; but typically this calculation is tedious and is not easily achieved with traditional visualization and analytic tools. We present a visual analytic method that incorporates a transect profiler and flux calculator. The analytic software is incorporated into our visual analytics tool Vinca, and generates multiple transects, which can be visualized and analysed in several alternative visualizations; users can choose specific transects to compare against real-world data; users can explore how flux changes within a domain. In addition, we report how ocean scientists have used our tool to display multiple-view views of their data and analyse hydrodynamic flux for the coastal zone.  相似文献   

Transport of BTEX Vapours Through Granular Soils with Different Moisture Contents in the Vadose Zone     

Panagiotis C. Nerantzis  Mark R. Dyer 《Geotechnical and Geological Engineering》2010,28(1):1-13

The single-ring aromatic hydrocarbons benzene, toluene, ethylbenzene and m-xylene (BTEX) are common and dangerous pollutants in subsurface environments. The diffusive transport of BTEX vapours through the unsaturated zone of the ground is a potential health hazard to humans, living in the vicinity of petroleum fuel contaminated sites. Past studies have shown that gas transport through the vadose zone can be influenced by moisture content due to variations in gaseous permeability, phase partitioning and aerobic biodegradation. In this particular study laboratory soil column experiments were employed to compare the diffusive transport of BTEX vapours through a sand layer of high moisture content, where biodegradation of BTEX compounds occurred, with diffusion through air-dried sand. The presence of a thin soil layer of high moisture content reduced the gaseous concentrations of benzene and toluene and stopped the migration of ethylbenzene and m-xylene vapours, demonstrating its efficiency as a barrier on the diffusive transport of BTEX vapours in unsaturated soil.  相似文献   

Chemical composition of wet deposition in a Mediterranean site Athens,Greece related to the origin of air masses     

Panagiotis T. Nastos  Dimitrios Alexakis  Helen A. Kanellopoulou  Akindinos E. Kelepertsis 《Journal of Atmospheric Chemistry》2007,58(2):167-179

The goal of this study is to determine the chemical composition of rain, in the wider region of Athens, Greece for the time period 1st September 2001 to 31st August 2002. Two model automatic rain samplers were installed in the Meteorological Station of Laboratory of Climatology (latitude: 37° 58′ N, longitude: 23° 47′ E) inside the Athens University Campus and in a site at Heraklio Attica, a northern suburb of Athens (latitude: 38° 03′ N, longitude: 23° 45′ E). The concentrations (μeq l⁻¹) of the major cations (H⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺) and anions (Cl⁻, , και ), as well as pH and conductivity of rain in 39 total samples were determined. The figures of pH range from 6.4 to 8.4 and conductivity from 8 to 207 μS cm⁻¹. The analysis showed that Ca²⁺ ions are abundant within all examined samples, while and present the highest concentrations from the anions. In order to find out the origin of the air masses, the air mass back trajectories were calculated. Five sectors of the origin of air masses were revealed: the North, the South, the Local, the West and the East sector. Multivariate methods included Factor Analysis and Discriminant Analysis were applied to the examined ion concentrations and three main factors were extracted, which discriminated the ions according to their origin. The first group of ions is interpreted as the result of the anthropogenic activity, the second group represents the acidity–alkalinity independently of their source and the third one the marine influence.  相似文献   

The first photometric analysis of the near-contact binary star V370 Cygni     

Vassilios N. Manimanis  Panagiotis G. Niarchos 《Astrophysics and Space Science》2007,310(1-2):153-157

The first complete CCD light curves of the eclipsing binary system V370 Cygni have been obtained in the B, V, R and I filters during 5 consecutive nights in 2005 at Kryoneri Observatory, Greece. These curves were analyzed with the Wilson–Devinney program in order to determine the geometrical and physical parameters of the system. The analysis indicates a semi-detached configuration and a mildly evolved state of the system.   相似文献   

Registering randomly oriented scenes through moving object attributes     

Panagiotis Partsinevelos 《International journal of geographical information science》2013,27(11):1793-1807

  相似文献   

Near-contact binaries among short-period Algols: the case of BF Velorum with a pulsating component     

Vassilios N. Manimanis  Chloe Vamvatira-Nakou  Panagiotis G. Niarchos 《Astrophysics and Space Science》2009,323(2):115-121

A photometric analysis of the short-period Algol eclipsing binary system BF Velorum based for the first time on complete BVRI CCD light curves is presented. The new photometric solution obtained with the Wilson-Devinney program reveals that BF Vel is a near-contact semi-detached system with its secondary component filling its Roche lobe. Moreover, we discovered pulsations of one member of the binary system, the analysis of which shows main frequencies of 44.9386 and 33.6731 cycles/day. Absolute elements of the system were calculated, and the evolutionary status of its members was estimated.   相似文献   

The effect of air temperature and human thermal indices on mortality in Athens, Greece   总被引：2，自引：1，他引：1  

Panagiotis T. Nastos  Andreas Matzarakis 《Theoretical and Applied Climatology》2012,108(3-4):591-599

This paper investigates whether there is any association between the daily mortality for the wider region of Athens, Greece and the thermal conditions, for the 10-year period 1992–2001. The daily mortality datasets were acquired from the Hellenic Statistical Service and the daily meteorological datasets, concerning daily maximum and minimum air temperature, from the Hellinikon/Athens meteorological station, established at the headquarters of the Greek Meteorological Service. Besides, the daily values of the thermal indices Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were evaluated in order to interpret the grade of physiological stress. The first step was the application of Pearson’s χ ² test to the compiled contingency tables, resulting in that the probability of independence is zero (p?=?0.000); namely, mortality is in close relation to the air temperature and PET/UTCI. Furthermore, the findings extracted by the generalized linear models showed that, statistically significant relationships (p?<?0.01) between air temperature, PET, UTCI and mortality exist on the same day. More concretely, on one hand during the cold period (October–March), a 10°C decrease in daily maximum air temperature, minimum air temperature, temperature range, PET and UTCI is related with an increase 13%, 15%, 2%, 7% and 6% of the probability having a death, respectively. On the other hand, during the warm period (April–September), a 10°C increase in daily maximum air temperature, minimum air temperature, temperature range, PET and UTCI is related with an increase 3%, 1%, 10%, 3% and 5% of the probability having a death, respectively. Taking into consideration the time lag effect of the examined parameters on mortality, it was found that significant effects of 3-day lag during the cold period appears against 1-day lag during the warm period. In spite of the general aspect that cold conditions seem to be favourable factors for daily mortality, the air temperature and PET/UTCI exceedances over specific thresholds depending on the distribution reveal that, very hot conditions are risk factors for the daily mortality.  相似文献   

Bayesian analysis of data and model uncertainty in 3D seismic travel-time tomography     

Michael Arvanitis  Panagiotis Vlamos 《Central European Journal of Geosciences》2009,1(2):227-231

We present a probabilistic analysis of seismic travel-time equations using the Bayesian Method. The assessment of models and data is crucial in 3D seismic travel-time tomography, and a method quantitatively assess the quality of both the data and the model is necessary in order to attain the most realistic results. The Bayesian method that we propose here is more effective than the frequentist approach, both in analysis time and uncertainty minimization, when processing large sets of tomographic data.  相似文献   

Variability of Climate in Meridional Balkans during the Periods 1675–1715 and 1780–1830 and its Impact on Human Life     

Eleni Xoplaki  Panagiotis Maheras  Juerg Luterbacher 《Climatic change》2001,48(4):581-615

The periods from 1675–1715 (Late Maunder Minimum; LMM)and 1780–1830 (Early Instrumental Period; EIP)delineate important parts of the so-called `Little IceAge' (LIA), in which Europe experienced predominantcooling. Documentary data, assembled from a number ofsources, in the course of the EU funded researchproject ADVICE (Annual to Decadal Variability ofClimate in Europe), has been used to locate anddescribe events in the southern Balkans and easternMediterranean. The resulting data has been usedfirstly to investigate the incidence of phenomena suchas crops sterility, famine and epidemics and theirrelationships with climate, and secondly to analysethe extent of variability, particularly the occurrenceof extreme events, such as severe winters (cold, wetor snowy), long periods of drought and wet periods.During the LMM and EIP, more such extreme situationswere apparent compared with the last 50 years of thetwentieth century. From the scattered data found for1675–1715 and 1780–1830, the winter and spring climatein southern Balkans and the eastern Mediterranean,especially during the LMM, can be characterised ascooler and relatively rainier with a highervariability compared with the recent decades.  相似文献   

Variation in noble gas isotopic composition of gas samples from the Aegean arc, Greece     

Aya Shimizu  Hirochika Sumino  Keisuke Nagao  Kenji Notsu  Panagiotis Mitropoulos 《Journal of Volcanology and Geothermal Research》2005,140(4):118-339

In contrast to most other arcs with oceanic plate subduction, the Aegean arc is characterized by continent–continent subduction. Noble gas abundances and isotopic compositions of 45 gas samples have been determined from 6 volcanoes along the arc, 2 islands in the back-arc region and 7 sites in the surrounding areas. The ³He/⁴He ratios of the samples ranged from 0.027R_A to 6.2R_A (R_A denotes the atmospheric ³He/⁴He ratio of 1.4×10⁻⁶), demonstrating that even the maximum ³He/⁴He ratio in the region is significantly lower than the maximum ratios of most oceanic subduction systems, which are equal to the MORB value of 8±1 R_A. Regional variations in the ³He/⁴He ratio were observed both along and across the arc. The maximum ³He/⁴He ratio was obtained from Nisyros volcano located in the eastern end of the arc, and the ratio decreased westward possibly reflecting the difference in potential degree of crustal assimilation or the present magmatic activity in each volcano. Across the volcanic arc, the ³He/⁴He ratio decreased with an increasing distance from the arc front, reaching a low ratio of 0.063R_A in Macedonia, which suggested a major contribution of radiogenic helium derived from the continental crust. At Nisyros, a temporal increase in ³He/⁴He ratio due to ascending subsurface magma was observed after the seismic crisis of 1995–1998 and mantle neon was possibly detected. The maximum ³He/⁴He ratio (6.2R_A) in the Aegean region, which is significantly lower than the MORB value, is not probably due to crustal assimilation at shallow depth or addition of slab-derived helium to MORB-like mantle wedge, but inherent characteristics of the subcontinental lithospheric mantle (SCLM) beneath the Aegean arc.  相似文献