Burned area mapping and post-fire impact assessment in the Kassandra peninsula (Greece) using Landsat TM and Quickbird data     

Dimitris Palandjian  Ioannis Z. Gitas  Robert Wright 《国际地球制图》2013,28(3):193-205

The purpose of this study was to assess the environmental impacts of forest fires on part of the Mediterranean basin. The study area is on the Kassandra peninsula, prefecture of Halkidiki, Greece. A maximum likelihood supervised classification was applied to a post-fire Landsat TM image for mapping the exact burned area. Land-cover types that had been affected by fire were identified with the aid of a CORINE land-cover type layer. Results showed an overall classification accuracy of 95%, and 83% of the total burned area was ‘forest areas’. A normalized difference vegetation index threshold technique was applied to a post-fire Quickbird image which had been recorded six years after the fire event to assess the vegetation recovery and to identify the vegetation species that were dominant in burned areas. Four classes were identified: ‘bare soil’, ‘sparse shrubs’, ‘dense shrubs’ and ‘tree and shrub communities’. Results showed that ‘shrublands’ is the main vegetation type which has prevailed (65%) and that vegetation recovery is homogeneous in burned areas.  相似文献   

Assessment of concrete bridges subjected to ground motion with an arbitrary angle of incidence: static and dynamic approach     

Ioannis F. Moschonas  Andreas J. Kappos 《Bulletin of Earthquake Engineering》2013,11(2):581-605

A nonlinear static analysis methodology for the derivation of a set of pushover curves for any angle of incidence of the seismic action (multidirectional pushover curves) for bridges is developed, wherein the interaction between axial force and biaxial moments at critical pier sections or biaxial shear forces at the bearings is taken into account. Dynamic pushover curves (base shear vs. peak deck displacement) for arbitrary angle of incidence of the excitation, are derived for both unidirectional (single-component) and bidirectional (dual-component) ground motion. It is found that neglecting the minor horizontal component leads to underestimation of bridge response, especially along the bridge principal directions and that the angle of incidence of bidirectional excitation affects bridge response, but to a lesser extent than in the case of unidirectional excitation. The proposed procedure is then applied to a straight symmetric bridge, its results are checked against those from response-history analysis, and is found to be sufficiently accurate for practical application. Using the derived results it is also found that the design of the selected bridge is safe since for the design bidirectional earthquake the bridge starts to behave inelastically (the first plastic hinge forms), while its failure occurs for about four times the design seismic action.  相似文献   

Optimization and Modeling of the Photocatalytic Degradation of the Insect Repellent DEET in Aqueous TiO2 Suspensions     

Maria Antonopoulou  Ioannis Konstantinou 《洁净——土壤、空气、水》2013,41(6):593-600

Response surface methodology (RSM) and artificial neural networks (ANNs) based on a multivariate central composite design (CCD) were applied to model and optimize the photocatalytic degradation of N,N‐diethyl‐m‐toluamide (DEET). The individual and interaction effects of three main operating factors (mass of TiO₂, initial DEET concentration, and irradiation intensity) on process efficiency were estimated, proving their important effect on % DEET removal. Among the independent variables, TiO₂ concentration displayed the highest effect on DEET degradation followed by initial DEET concentration and UV intensity. The optimization and prediction capabilities of ANNs and RSM were compared on the basis of root mean squared error, mean absolute error, absolute average deviation, and correlation coefficient values. Results proved the usefulness and capability of the experimental design strategy for successful investigation and modeling of the photocatalytic process. Moreover, the selected ANN gave better estimation capabilities throughout the range of variables than RSM. Based on the models and the related experimental conditions, the optimal values of each parameter were determined. Under optimum conditions, DEET and total organic carbon (TOC) followed pseudo‐first order kinetics. Nearly complete degradation of DEET took place within 15 min whereas high TOC removal percentages (>85%) was achieved after 90 min irradiation time.  相似文献   

Note on the single-shock solutions of the Korteweg-de Vries-Burgers equation     

Ioannis Kourakis  Sharmin Sultana  Frank Verheest 《Astrophysics and Space Science》2012,338(2):245-249

The well-known shock solutions of the Korteweg-de Vries-Burgers equation are revisited, together with their limitations in the context of plasma (astro)physical applications. Although available in the literature for a long time, it seems to have been forgotten in recent papers that such shocks are monotonic and unique, for a given plasma configuration, and cannot show oscillatory or bell-shaped features. This uniqueness is contrasted to solitary wave solutions of the two parent equations (Korteweg-de Vries and Burgers), which form a family of curves parameterized by the excess velocity over the linear phase speed.  相似文献   

Basic thermodynamic parameters of a black hole resulting from a Yukawa type of correction to the metric     

Ioannis Haranas  Ioannis Gkigkitzis 《Astrophysics and Space Science》2012,337(2):693-702

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton’s “inverse-square law” of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. Therefore the existence of such a force would only coexist with gravity, and in principle could only be detected as a deviation from the inverse square law, or in the “universality of free fall” experiments. New experimental techniques such that of Sagnac interferometry can help explore the range of the Yukawa correction λ≥10¹⁴ m where such forces might be present. It may be, that future space missions might be operating in this range which has been unexplored for very long time. In this paper we derive the basic thermodynamic parameters of such a Yukawa stationary spherically symmetric black hole. First, the expression for the event horizon of such a black hole is derived, with the help of which the temperature, entropy and heat capacity of this particular black hole are obtained. We have also obtained analytical expressions for the change of mass of such black hole, and also its corresponding evaporation time.  相似文献   

Entropic gravity resulting from a Yukawa type of correction to the metric for a solar mass black hole     

Ioannis Haranas  Ioannis Gkigkitzis 《Astrophysics and Space Science》2013,347(1):77-82

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton’s “inverse-square law” of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. In this paper we study the entropic gravity correction to the gravitational force on the horizon of a black hole whose metric has been modified by a Yukawa term. We find that the gravitational radius of such a black hole is given in-terms of the Lambert function, and the entropic force introduces a extra term that depends on the square of the coupling constant α of the Yukawa potential. In the case alpha equals zero we recover the Newtonian gravitational force on the horizon. In a first effort to obtain a relation between geometry and information, we calculate the Ricci scalar and through entropy we establish a relation to the number of information N where this is given in nats. Finally, we calculate a critical entropy value as well as a critical information number N _c for which the curvature becomes identically zero which implies that the space becomes flat.  相似文献   

Remediation of Sea Water Intrusion: A Case Study     

Ioannis K. Tsanis  Li-Fan Song 《Ground Water Monitoring & Remediation》2001,21(3):152-161

Sea water intrusion and remediation in the Upper Floridan Aquifer in South Carolina is simulated using the finite-element model SUTRA developed by the U.S. Geological Survey. A sensitivity analysis of the effect of the hydrogeologic parameters on the sea water recharge and seepage velocities is performed. An increase in confining unit and/or in aquifer conductivity results in an increase of the sea water recharge. An increase in aquifer porosity results in a decrease of the sea water recharge. Among the three remedial techniques simulated—reduced aquifer withdrawals, an injection well, and a combined injection and capture well—the reduced aquifer withdrawals and injection well are the best methods for preventing sea water intrusion.  相似文献   

Dependence of coda attenuation on frequency and lapse time in central Greece     

Ioannis Baskoutas 《Pure and Applied Geophysics》1996,147(3):483-496

The dependence of coda attenuationQ _c on frequency and lapse time was studied. Data from small local earthquakes, recorded at three stations (VMR, VSI and VFI) of the VOLNET network operating in central Greece, were used.Q _c was estimated by applying the single scattering model to bandpass-filtered seismograms, over a frequency range of 1 to 12 Hz. Analysis was performed every 10 s until the end on overlapping time windows.Q _c is found to depend on frequencyf in Hz according to a power law,Q _c =Q ₀ f ⁿ . ObservedQ ₀ ranges from 30 to 100 and the powern ranges from 0.90 to 0.70.Q ₀ increases andn decreases with lapse time increasing. A strong dependence ofQ _c on lapse time was also found. In the frequency range of 1 to 8 Hz and at a short lapse time,Q _c values were found to be similar for all three stations. On the other hand, at the longest analyzed time window (50 s), the estimatedQ _c values show a discrepancy which is more obvious at a higher frequency band. The scattering coefficient around the central station VSI is found to range from 0.029 to 0.0041 km^–1.Q _c from the single scattering model andQ _s from the amplitude ratio of directS to coda waves for the VSI station are similar. We believe dependence of coda attenuationQ _c on frequency and lapse time is caused by a combination of geotectonic features and depth variation asQ _s .  相似文献   

A methodology for the evaluation of the human-bioclimatic performance of open spaces     

Charalampopoulos  Ioannis  Tsiros  Ioannis  Chronopoulou-Sereli  Aik.  Matzarakis  Andreas 《Theoretical and Applied Climatology》2017,128(3-4):811-820

The purpose of this paper is to present a simple methodology to improve the evaluation of the human-biometeorological benefits of open spaces. It is based on two groups of new indices using as basis the well-known PET index. This simple methodology along with the accompanying indices allows a qualitative and quantitative evaluation of the climatic behavior of the selected sites. The proposed methodology was applied in a human-biometeorology research in the city of Athens, Greece. The results of this study are in line with the results of other related studies indicating the considerable influence of the sky view factor (SVF), the existence of the vegetation and the building material on human-biometeorological conditions. The proposed methodology may provide new insights in the decision-making process related to urban open spaces’ best configuration.

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Fractal analysis of normal faults in northwestern Aegean area, Greece     

Theodor Doutsos  Ioannis Koukouvelas 《Journal of Geodynamics》1998,26(2-4)

Normal faults within the Ptolemais coal field and large seismogenic faults in the northwestern Aegean remain fractal for displacement values larger than about 1m. The kinematic parameters on reverse drag profiles such as length of rollover, footwall uplift and wavelength of footwall uplift show that all three parameters have a power law relationship, expressed by a c exponent of about 1, with the maximum displacement which take place across the fault. Footwall uplift/hanging wall subsidence ratio is about 1/2.The displacement analysis help us to propose a growth model for larger seismogenic faults in the NW Aegean, as is the ‘Hepiros fault set’ and the ‘Aliakmon fault zone’. Faults within the ‘Aliakmon fault zone’ were independently developed, at the first stages of deformation, by tip line deformation and out-of plane bifurcation, whereas later, deformation continued by segment linkage. One of these faults the ‘Sarakina fault’ was reactivated during the 1995 earthquake to produce a 25 km long surface rupture. A long term slip rate of about 0.3 mm a⁻¹ has been estimated by taking into consideration that over the past 6 Ma a maximum displacement of 1700 m across this fault has taken place.  相似文献