Testing Texture of VHR Panchromatic Data as a Feature of Land Cover Classification     

Stanis⌈aw Lewiński  Sebastian Aleksandrowicz  Marek Banaszkiewicz 《Acta Geophysica》2015,63(2):547-567

While it is well-known that texture can be used to classify very high resolution (VHR) data, the limits of its applicability have not been unequivocally specified. This study examines whether it is possible to divide satellite images into two classes associated with “low” and “high” texture values in the initial stage of processing VHR images. This approach can be effectively used in object-oriented classification. Based on the panchromatic channel of KOMPSAT-2 images from five areas of Europe, datasets with down-sampled pixel resolutions of 1, 2, 4, 8, and 16 m were prepared. These images were processed using different texture analysis techniques in order to discriminate between basic land cover classes. Results were assessed using the normalized feature space distance expressed by the Jeffries–Matusita distance. The best results were observed for images with the highest resolution processed by the Laplacian filter. Our research shows that a classification approach based on the idea of “low” and “high” textures can be effectively applied to panchromatic data with a resolution of 8 m or higher.  相似文献   

Radiation mechanisms and geometry of Cygnus X-1 in the soft state     

Marek Gierli&#;ski  rzej A. Zdziarski  Juri Poutanen  Paolo S. Coppi  Ken Ebisawa  W. Neil Johnson 《Monthly notices of the Royal Astronomical Society》1999,309(2):496-512

We present X-ray/ γ -ray spectra of Cyg X-1 observed during the transition from the hard to the soft state and in the soft state by ASCA , RXTE and CGRO /OSSE in 1996 May and June. The spectra consist of a dominant soft component below ∼2 keV and a power-law-like continuum extending to at least ∼800 keV. We interpret them as emission from an optically thick, cold accretion disc and from an optically thin, non-thermal corona above the disc. A fraction f ≳0.5 of total available power is dissipated in the corona.
We model the soft component by multicolour blackbody disc emission taking into account the torque-free inner-boundary condition. If the disc extends down to the minimum stable orbit, the ASCA RXTE data yield the most probable black hole mass of M _X≈10 M_⊙ and an accretion rate,     , locating Cyg X-1 in the soft state in the upper part of the stable, gas-pressure-dominated, accretion-disc solution branch.
The spectrum of the corona is well modelled by repeated Compton scattering of seed photons from the disc off electrons with a hybrid, thermal/non-thermal distribution. The electron distribution can be characterized by a Maxwellian with an equilibrium temperature of kT _e∼30–50 keV, a Thomson optical depth of τ ∼0.3 and a quasi-power-law tail. The compactness of the corona is 2≲ℓ_h≲7, and a presence of a significant population of electron–positron pairs is ruled out.
We find strong signatures of Compton reflection from a cold and ionized medium, presumably an accretion disc, with an apparent reflector solid angle, Ω/2π∼0.5–0.7. The reflected continuum is accompanied by a broad iron K α line.  相似文献   

Cosmic strings in Lyra geometry     

Jerzy Matyjasek  Marek Rogatko 《Astrophysics and Space Science》1992,198(2):299-308

Exact cylindrically-symmetric solutions of Sen equations both with and without the source term in Lyra geometry are presented. It is found that the exterior vacuum solution, when continuously joined to the interior solution describing the uniform density cylinder of finite radius, may represent a cosmic string. The rate of light deflection that is independent of the impact parameter suggests that the solution has the gravitational lensing property, and for typical values of the linear mass density it yields predictions similar to general relativity.  相似文献   

Modeling of cometary evolution by kinetic theory: Method and first results     

Marek Banaszkiewicz  Hans Rickman 《Earth, Moon, and Planets》1996,72(1-3):203-210

Physical evolution of Jupiter family (JF) comets is considered as a simultaneous process of erosion and fading. Dynamical effects are limited to discrete changes of the perihelion distance, that result in changes of the evaporation rate. Assuming that the JF comet population is in a steady state, a distribution function of this population in the two dimensional phase space consisting of radius and active fraction of the nucleus surface is found as the solution of a set of kinetic equations, each one of them for a different perihelion distance. With use of the distribution function some statistical properties of the comet population, like the total number of comets in the considered region of the phase space, the number of objects that evaporate or get dormant per unit time, etc., are obtained. The cumulative distribution function with respect to the absolute brightness is calculated and compared with the observed one as a check on the considered models.  相似文献   

Heterochromatin and NOR location in northern pike (Esox lucius)   总被引：2，自引：0，他引：2  

Malgorzata Jankun  Pawel Woznicki  Grzegorz Dajnowicz  Krystyna Demska-Zakes  Marek J. Luczynski  Miroslaw Luczynski 《Aquatic Sciences - Research Across Boundaries》1998,60(1):17-21

  相似文献   

Multicolour Photometry of AM Her During 1994–96     

Diana Kjurkchieva  Dragomir Marchev  Marek Drozdz 《Astrophysics and Space Science》1998,262(4):453-476

Multicolour photometry of the polar AM Her was obtained during 3 observational seasons (1994/95/96). The star was in its high state for most of the observations. It was in its low state in '96 April. It was established that these two states differ not only in the average light level but in the larger amplitudes of variations at low state than at high state. Moreover the energy distributions of the two states differ in the stronger dependence of the flux on ν at high state than at low state. The Fourier analysis of the photometric data shows variability with the spectroscopic (orbital) period. The amplitudes of this variability in all colours are about two times bigger at low state than at high state. An attempt to explain the photometric behaviour of AM Her by a model of dominant emission of two hot spots at the magnetic poles of the white dwarf was made and the spot parameters were determined. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications     

Andrzej A. Zdziarski  Juri Poutanen  Joanna Mikolajewska  Marek Gierli&#;ski  Ken Ebisawa  & W. Neil Johnson 《Monthly notices of the Royal Astronomical Society》1998,301(2):435-450

  相似文献   

Tolman's cosmological models     

Michael Heller  Marek Szydlowski 《Astrophysics and Space Science》1983,90(2):327-335

Oscillating Tolman universes have been identified as solutions of the Friedmann equation with the bulk viscosity dissipation. Their dynamics and some thermodynamical properties are briefly discussed. Problems such as the Eternal Return philosophy and its modern incarnation into the doctrine of the Universe as a global oscillator, Tipler's no-return theorem, etc., are touched upon.  相似文献   

The influence of atmospheric circulation on the intensity of urban heat island and urban cold island in Poznań, Poland     

Marek?Pó?rolniczakEmail authorView author&#;s OrcID profile  Leszek?Kolendowicz  Agnieszka?Majkowska  Bartosz?Czernecki 《Theoretical and Applied Climatology》2017,127(3-4):611-625

The study has analyzed influence of an atmospheric circulation on urban heat island (UHI) and urban cold island (UCI) in Poznań. Analysis was conducted on the basis of temperature data from two measurement points situated in the city center and in the ?awica airport (reference station) and the data concerning the air circulation (Nied?wied?’s calendar of circulation types and reanalysis of National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR)). The cases with UHI constitute about 85 % of all data, and UCI phenomena appear with a frequency of 14 % a year. The intensity of UHI phenomenon is higher in the anticyclonic circulation types. During the year in anticyclonic circulation, intensity of UHI is 1.2 °C on average while in cyclonic is only 0.8 °C. The occurring of UHI phenomena is possible throughout all seasons of the year in all hours of the day usually in anticyclonic circulation types. The cases with highest UHI intensity are related mostly to nighttime. The cases of UCI phenomena occurred almost ever on the daytime and the most frequently in colder part of the year together with cyclonic circulation. Study based on reanalysis data indicates that days with large intensity of UHI (above 4, 5, and 6 °C) are related to anticyclonic circulation. Anticyclonic circulation is also promoting the formation of the strongest UCI. Results based on both reanalysis and the atmospheric circulation data (Nied?wied?’s circulation type) confirm that cases with the strongest UHI and UCI during the same day occur in strong high-pressure system with the center situated above Poland or central Europe.  相似文献   

Carbon dioxide seasonality in dynamically ventilated caves: the role of advective fluxes     

Lang  Marek  Faimon  Jiří  Godissart  Jean  Ek  Camille 《Theoretical and Applied Climatology》2017,129(3-4):1355-1372

The seasonality in cave CO₂ levels was studied based on (1) a new data set from the dynamically ventilated Comblain-au-Pont Cave (Dinant Karst Basin, Belgium), (2) archive data from Moravian Karst caves, and (3) published data from caves worldwide. A simplified dynamic model was proposed for testing the effect of all conceivable CO₂ fluxes on cave CO₂ levels. Considering generally accepted fluxes, i.e., the direct diffusive flux from soils/epikarst, the indirect flux derived from dripwater degassing, and the input/output fluxes linked to cave ventilation, gives the cave CO₂ level maxima of 1.9 × 10⁻² mol m⁻³ (i.e., ∼ 440 ppmv), which only slightly exceed external values. This indicates that an additional input CO₂ flux is necessary for reaching usual cave CO₂ level maxima. The modeling indicates that the additional flux could be a convective advective CO₂ flux from soil/epikarst driven by airflow (cave ventilation) and enhanced soil/epikarstic CO₂ concentrations. Such flux reaching up to 170 mol s⁻¹ is capable of providing the cave CO₂ level maxima up to 3 × 10⁻² mol m⁻³ (70,000 ppmv). This value corresponds to the maxima known from caves worldwide. Based on cave geometry, three types of dynamic caves were distinguished: (1) the caves with the advective CO₂ flux from soil/epikarst at downward airflow ventilation mode, (2) the caves with the advective soil/epikarstic flux at upward airflow ventilation mode, and (3) the caves without any soil/epikarstic advective flux. In addition to CO₂ seasonality, the model explains both the short-term and seasonal variations in δ¹³C in cave air CO₂.

  相似文献