Introduction     

Ján Šimkanin  Juraj Kyselica  Jozef Brestenský  Peter Guba 《地球物理与天体物理流体动力学》2019,113(1-2)

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The Košice meteorite fall: Atmospheric trajectory,fragmentation, and orbit     

Jiří Borovička  Juraj Tóth  Antal Igaz  Pavel Spurný  Pavel Kalenda  Jakub Haloda  Ján Svoreň  Leonard Kornoš  Elizabeth Silber  Peter Brown  Marek Husárik 《Meteoritics & planetary science》2013,48(10):1757-1779

The Ko?ice meteorite fall occurred in eastern Slovakia on February 28, 2010, 22:25 UT. The very bright bolide was imaged by three security video cameras from Hungary. Detailed bolide light curves were obtained through clouds by radiometers on seven cameras of the European Fireball Network. Records of sonic waves were found on six seismic and four infrasonic stations. An atmospheric dust cloud was observed the next morning before sunrise. After careful calibration, the video records were used to compute the bolide trajectory and velocity. The meteoroid, of estimated mass of 3500 kg, entered the atmosphere with a velocity of 15 km s^?1 on a trajectory with a slope of 60° to the horizontal. The largest fragment ceased to be visible at a height of 17 km, where it was decelerated to 4.5 km s^?1. A maximum brightness of absolute stellar magnitude about ?18 was reached at a height of 36 km. We developed a detailed model of meteoroid atmospheric fragmentation to fit the observed light curve and deceleration. We found that Ko?ice was a weak meteoroid, which started to fragment under the dynamic pressure of only 0.1 MPa and fragmented heavily under 1 MPa. In total, 78 meteorites were recovered in the predicted fall area during official searches. Other meteorites were found by private collectors. Known meteorite masses ranged from 0.56 g to 2.37 kg. The meteorites were classified as ordinary chondrites of type H5 and shock stage S3. The heliocentric orbit had a relatively large semimajor axis of 2.7 AU and aphelion distance of 4.5 ± 0.5 AU. Backward numerical integration of the preimpact orbit indicates possible large variations of the orbital elements in the past due to resonances with Jupiter.  相似文献   

A small-scale landslide susceptibility assessment for the territory of Western Carpathians     

Juraj Holec  Martin Bednarik  Marián Šabo  Jozef Minár  Isik Yilmaz  Marián Marschalko 《Natural Hazards》2013,69(1):1081-1107

This study presented herein compares the bivariate and multivariate landslide susceptibility mapping methods and presents the landslide susceptibility map of the territory of Western Carpathians in small scale. This study also describes pioneer work for the territory of Western Carpathians, overreaching state borders, using verified sophisticated statistical methods. In the susceptibility mapping, digital elevation model was first constructed using a GIS software, and parameter maps affecting the slope stability such as geology, seismicity, precipitation, topographical elevation, slope angle, slope aspect and land cover were considered. In the last stage of the analyses, landslide susceptibility maps were produced using bivariate and multivariate analyses, and they were then compared by means of their validations. The validation of the bivariate analysis data was performed using the results of bivariate analysis for landslide areas of Slovakia containing five classes of susceptibility in scale 1:500,000. The validation area is the area of Western Carpathians within Slovakia. Eighty-two per cent of area does not differ in more than one class. The validation of the multivariate analysis data was performed using the results from the Kysuce region in the northern part of Slovakia in scale 1:10,000. The raster calculator was used to express the difference between each pair of pixels within these two layers. Seventy-seven per cent of the pixels do not differ in more than 25 %, 94 % of the pixels do not differ in more than 50 %. The maximal possible difference is 100 % (one pixel with value 0 and other with value 1, or vice versa). Receiver operating characteristic analysis was also performed, the area under curve value for bivariate model was calculated to be 0.735, while it was 0.823 for multivariate. The results of the validation can be considered as satisfactory.  相似文献   

The 2011 Draconids: The First European Airborne Meteor Observation Campaign     

Jeremie Vaubaillon  Pavel Koten  Anastasios Margonis  Juraj Toth  Regina Rudawska  Maria Gritsevich  Joe Zender  Jonathan McAuliffe  Pierre-Dominique Pautet  Peter Jenniskens  Detlef Koschny  Francois Colas  Sylvain Bouley  Lucie Maquet  Arnaud Leroy  Jean Lecacheux  Jiri Borovicka  Junichi Watanabe  Jürgen Oberst 《Earth, Moon, and Planets》2015,114(3-4):137-157

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Effects of meteoroid shape on cosmogenic nuclide production processes          下载免费PDF全文

Jozef Masarik  Juraj Beňo 《Meteoritics & planetary science》2015,50(2):318-325

The shape of meteorites is one of the major factors influencing the production of cosmogenic nuclides. Numerical simulations using the Los Alamos Code System (LCS) particle production and transport codes were done to investigate particle fluxes and production rates of cosmogenic nuclides ¹⁰Be, ²⁶Al, and ⁶⁰Co in meteoroids of spherical, ellipsoidal, and cylindrical shapes. The calculations show that fluxes of nuclear active particles and also production rates of cosmogenic nuclides are sensitive to the shape of the irradiated parent body.  相似文献   

Internally consistent thermodynamic data for magnesium sulfate hydrates     

Klaus-Dieter Grevel  Juraj Majzlan 《Geochimica et cosmochimica acta》2009,73(22):6805-6299

Experimental studies on the stability of several Mg-sulfate hydrates including epsomite (MgSO₄·7H₂O), hexahydrite (MgSO₄·6H₂O), starkeyite (MgSO₄·4H₂O), and kieserite (MgSO₄·H₂O) as a function of temperature and relative humidity are in poor agreement with calculations based on thermodynamic properties of these substances taken from the literature. Therefore, we synthesized four different MgSO₄ hydrates and measured their enthalpies of formation by solution calorimetry at T = 298.15 K. The resulting enthalpies of formation from the elements are:

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Δ_fH⁰₂₉₈ (epsomite) = −3387.7 ± 1.3 kJmol⁻¹

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Δ_fH⁰₂₉₈ (hexahydrite) = −3088.1 ± 1.1 kJmol⁻¹

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Δ_fH⁰₂₉₈ (sanderite, MgSO₄·2H₂O) = −1894.9 ± 1.3 kJmol⁻¹

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Δ_fH⁰₂₉₈ (kieserite) = −1612.4 ± 1.3 kJmol⁻¹

Using mathematical programming (MAP) techniques, standard thermodynamic values consistent both with our calorimetric data and previously published humidity brackets could be derived:

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Epsomite: Δ_fH⁰₂₉₈ = −3388.7 kJmol⁻¹, S⁰₂₉₈ = 371.3 Jmol⁻¹ K⁻¹, Δ_fG⁰₂₉₈ = −2871.0 kJmol⁻¹

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Hexahydrite: Δ_fH⁰₂₉₈ = −3087.3 kJmol⁻¹, S⁰₂₉₈ = 348.5 Jmol⁻¹ K⁻¹, Δ_fG⁰₂₉₈ = −2632.3 kJmol⁻¹

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Starkeyite: Δ_fH⁰₂₉₈ = −2496.1 kJmol⁻¹, S⁰₂₉₈ = 259.9 Jmol⁻¹ K⁻¹, Δ_fG⁰₂₉₈ = −2153.8 kJmol⁻¹

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Kieserite: Δ_fH⁰₂₉₈ = −1611.5 kJmol⁻¹, S⁰₂₉₈ = 126.0 Jmol⁻¹ K⁻¹, Δ_fG⁰₂₉₈ = −1437.9 kJmol⁻¹

Additionally, heat capacity measurements and standard entropy determinations of several magnesium sulfate hydrate minerals from the literature are analyzed and judged against estimates obtained from a linear combination of the heat capacities of MgSO₄ and hexagonal ice. The results of the MAP analysis are compared to these estimates to conclude that heat capacity and entropy correlate well with the number of waters of hydration. However, even the good correlation is not good enough to capture the fine variations in these properties. Consequently, their experimental measurement is inevitable if reliable thermodynamic data are sought. Our MAP thermodynamic data show that epsomite, hexahydrite, and kieserite have stability fields in the T-%RH space. Starkeyite is metastable. Although no MAP data could have been derived for pentahydrite (MgSO₄·5H₂O) and sanderite, their transient existence suggest that both of them are metastable as well.  相似文献   

Landscape change analysis and assessment (case studies in Slovakia and Bulgaria)     

Jan Feranec  Monika Kopecka  Rumiana Vatseva  Anton Stoimenov  Jan Otahel  Juraj Betak  Karol Husar 《Central European Journal of Geosciences》2009,1(1):106-119

Landscape change assessment was conducted in selected areas of Slovakia and Bulgaria in 1990–2000 using CORINE land cover (CLC) data layer analysis. Assessment of causes that led to these changes was undertaken, with an emphasis on those that determined the extensification of agriculture. The LC data were obtained under the CLC90 and I&CLC2000 projects, jointly managed by the European Environment Agency in Copenhagen, Denmark and the Joint Research Centre of the European Commission in Ispra, Italy. The CLC1990-2000-changes data layer was generated by overlaying the CLC90 and CLC2000 data layers for change in areas of a minimum 5 ha. The analysed causes of changes (driving forces) were then classified. Land cover (LC) changes characterizing urbanization processes occurred only in the Trnava and Tatras areas. Intensification of agriculture was also higher in these two areas. LC changes characterizing the extensification of agriculture were dominant in Plovdiv and Trnava. Deforestation and forestation were identified in all areas (Trnava, Tatras, Plovdiv, and Burgas). The basic reasons of these changes were related to the transformation of national economies from being centrally planned to market controlled, following the fall of socialism and before the countries joined the European Union.  相似文献   

Assessment of past flood changes across Europe based on flood-generating processes     

Yeshewatesfa Hundecha  Juraj Parajka  Alberto Viglione 《水文科学杂志》2020,65(11):1830-1847

ABSTRACT

A rainfall–runoff model was employed to identify four major flood-generating processes corresponding to flood events identified from daily discharge data from 614 stations across Europe in the period 1961–2010: long-rain, short-rain, snowmelt, and rain-on-dry-soil flood events. Trend analyses were performed on the frequency of occurrence of each of the flood types continentally and in five geographical regions of Europe. Continentally, the annual frequency of flood events did not show a significant change over the investigation period. However, the frequency of both winter and summer long-rain events increased significantly, while that of summer snowmelt events decreased significantly. Regionally, the frequency of winter short and long-rain events increased significantly in Western Europe, while the frequency of summer snowmelt and short-rain events decreased in Northern Europe. The frequency of summer snowmelt events in Eastern Europe and winter short-rain events in Southern Europe showed a declining trend.  相似文献   

Spatial and temporal variability of event runoff characteristics in a small agricultural catchment     

Xiaofei Chen  Juraj Parajka  Borbála Széles  Peter Strauss  Günter Blöschl 《水文科学杂志》2020,65(13):2185-2195

ABSTRACT

The objective of this study is to investigate the factors that control event runoff characteristics at the small catchment scale. The study area is the Hydrological Open Air Laboratory, Lower Austria. Event runoff coefficient (Rc), recession time constant (Tc) and peak discharge (Qp) are estimated from hourly discharge and precipitation data for 298 events in the period 2013–2015. The results show that the Rc and their variability tend to be largest for the tile drainages (mean Rc = 0.09) and the main outlet (mean Rc = 0.08) showing larger Rc in January/February and smaller Rc in July/August. Tc does not vary much between the systems and tends to be largest at the main outlet (mean Tc = 6.5 h) and smallest for the tile drainages (mean Tc = 4.5 h). Groundwater levels explain the temporal variability of Rc and Tc more than soil moisture or precipitation, suggesting a role of shallow flow paths.  相似文献   

Testing Nano-Powder and Fused-Glass Mineral Reference Materials for In Situ Rb-Sr Dating of Glauconite,Phlogopite, Biotite and Feldspar via LA-ICP-MS/MS     

Ahmad Redaa  Juraj Farkaš  Sarah Gilbert  Alan S. Collins  Stefan Löhr  Davood Vasegh  Marnie Forster  Morgan Blades  Thomas Zack  Andrea Giuliani  Roland Maas  Andre Baldermann  Martin Dietzel  Dieter Garbe-Schönberg 《Geostandards and Geoanalytical Research》2023,47(1):23-48

Reference materials (RMs) with well-characterised composition are necessary for reliable quantification and quality control of isotopic analyses of geological samples. For in situ Rb-Sr analysis of silicate minerals via laser ablation inductively coupled plasma tandem mass spectrometry (LA-ICP-MS/MS) with a collision/reaction cell, there is a general lack of mineral-specific and matrix-matched RMs, which limits wider application of this new laser-based dating technique to certain minerals. In this work, pressed nano-powder pellets (NP) of four RMs, GL-O (glauconite), Mica-Mg (phlogopite), Mica-Fe (biotite) and FK-N (K-feldspar), were analysed and tested for in situ Rb-Sr dating, complemented by isotope dilution (ID) MC-ICP-MS Rb-Sr analyses of GL-O and Mica-Mg. In addition, we attempted to develop alternative flux-free and fused ‘mineral glasses’ from the above RMs for in situ Rb-Sr dating applications. Overall, the results of this study showed that among the above RMs only two NP (Mica-Mg-NP and GL-O-NP) were suitable and robust for in situ dating applications. These two nano-powder reference materials, Mica-Mg-NP and GL-O-NP, were thus used as primary RMs to normalise and determine Rb-Sr ages for three natural minerals: MDC phlogopite and GL-O glauconite grains, and also Mica-Fe-NP (biotite). Our in situ analyses of the above RMs yielded Rb-Sr ages that are in good agreement (within 8%) of published ages, which suggests that both Mica-Mg-NP and GL-O-NP are suitable RMs for in situ Rb-Sr dating of phlogopite, glauconite and biotite. However, using secondary RMs is recommended to monitor the quality of the obtained ages.  相似文献