Constraining the degree of the dominant mode in QQ Vir

We present early results of the application of a method which uses multicolor photometry and spectroscopy for ? discrimination. This method has been successfully applied to the pulsating hot subdwarf Balloon?090100001. Here we apply the method to QQ?Vir (PG1325+101). This star was observed spectroscopically and photometrically in 2008. Details on spectroscopy can be found in Telting et al. (Astrophys. Space Sci. 2010, this volume), while photometry and preliminary results on ? discrimination are provided here. The main aim of this work was to compare the value of the ? parameter derived for the main mode in QQ?Vir to previously published values derived by using different methods.     

Framework for assessing probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time

This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of a_max and M_w). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted.     

Origin of the Zálesí U–Ni–Co–As–Ag/Bi deposit,Bohemian Massif,Czech Republic: fluid inclusion and stable isotope constraints

The Zálesí vein-type deposit is hosted by Early Paleozoic high-grade metamorphic rocks on the northern margin of the Bohemian Massif. The mineralization is composed of three main stages: uraninite, arsenide, and sulfide. The mineral assemblages formed at low temperatures (~80 to 130°C, locally even lower) and low pressures (<100 bars). The salinity of the aqueous hydrothermal fluids (0 to 27 wt.% salts) and their chemical composition vary significantly. Early fluids of the oldest uraninite stage contain a small admixture of a clathrate-forming gas, possibly CO₂. Salinity correlates with oxygen isotope signature of the fluid and suggests mixing of brines [δ ¹⁸O around +2‰ relative to standard mean ocean water (SMOW)] with meteoric waters (δ ¹⁸O around −4‰ SMOW). The fluid is characterized by highly variable halogen ratios (molar Br/Cl = 0.8 × 10⁻³ to 5.3 × 10⁻³; molar I/Cl = 5.7 × 10⁻⁶ to 891 × 10⁻⁶) indicating a dominantly external origin for the brines, i.e., from evaporated seawater, which mixed with iodine-enriched halite dissolution brine. The cationic composition of these fluids indicates extensive interaction of the initial brines with their country rocks, likely associated with leaching of sulfur, carbon, and metals. The brines possibly originated from Permian–Triassic evaporites in the neighboring Polish Basin, infiltrated into the basement during post-Variscan extension and were finally expelled along faults giving rise to the vein-type mineralization. Cenozoic reactivation by low-salinity, low-δ ¹⁸O (around −10‰ SMOW) fluids of mainly meteoric origin resulted in partial replacement of primary uraninite by coffinite-like mineral aggregates.     

Assessing the potential for CO2 adsorption in a subbituminous coal,Huntly Coalfield,New Zealand,using small angle scattering techniques

Small angle scattering techniques (SAXS and SANS) have been used to investigate the microstructural properties of the subbituminous coals (R_max 0.42–0.45%) from the Huntly Coalfield, New Zealand. Samples were collected from the two thick (> 5 m) coal seams in the coalfield and have been analysed for methane and carbon dioxide sorption capacity, petrography, pore size distribution, specific surface area and porosity.Specific surface area (SSA) available for carbon dioxide adsorption, extrapolated to a probe size of 4 Å, ranged from 1.25 × 10⁶ cm^? 1 to 4.26 × 10⁶ cm^? 1 with total porosity varying from 16% to 25%. Porosity was found to be predominantly composed of microporosity, which contributed the majority of the available SSA. Although considerable variation was seen between samples, the results fit well with published rank trends.Gas holding capacity at the reservoir pressure (approximately 4 MPa) ranged from 2.63 to 4.18 m³/t for methane on a dry, ash-free basis (daf) and from 22.00 to 23.72 m³/t daf for carbon dioxide. The resulting ratio of CO₂:CH₄ ranged from 5.7 to 8.6, with an average of 6.7:1.Holding capacities for both methane and carbon dioxide on a dry ash free basis (daf) were found to be correlated with sample microporosity. However, holding capacities for the two gases on an as analysed (aa) basis (that is including mineral matter and moisture), showed no such correlation. Carbon dioxide (aa) does show a negative correlation with both specific surface area and microporosity. As the coals have low inorganic matter content, the reversal is thought to be related to moisture which is likely concentrated in the pore size range 12.5–125 Å. Methane holding capacity, both daf and aa, correlates with macroporosity, thus suggesting that the holding capacity of micropores is diminished by the presence of moisture in the pores.     

Optimization framework for calibration of constitutive models enhanced by neural networks

A two‐level procedure designed for the estimation of constitutive model parameters is presented in this paper. The neural network (NN) approach at the first level is applied to achieve the first approximation of parameters. This technique is used to avoid potential pitfalls related to the conventional gradient‐based optimization techniques, considered here as a corrector that improves predicted parameters. The feed‐forward NN (FFNN) and the modified Gauss–Newton algorithms are briefly presented. The proposed framework is verified for the elasto‐plastic modified Cam Clay model that can be calibrated based on standard triaxial laboratory tests, i.e. the isotropic consolidation test and the drained compression test. Two different formulations of the input data to the NN, enhanced by a dimensional reduction of experimental data using principal component analysis, are presented. The determination of model characteristics is demonstrated, first on numerical pseudo‐experiments and then on the experimental data. The efficiency of the proposed approach by means of accuracy and computational effort is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

On the behaviour of liquefied soil

Engineering mechanics of liquefied soil is presented. Firstly, experimental methods and their results are described in order to show that liquefied soil can be approximated as a viscous fluid. The experiments proposed allow for determination of dynamic viscosity of liquefied soil, which is of the order of 10⁶ Ns/m². This value agrees with some theoretical estimates. Then, the model of viscous fluid is applied to practically important problems, in order to predict sinking of structures in liquefied subsoil, and to describe underwater flows of seabed. Enclosed examples show that the model and methods proposed lead to realistic results and, therefore, can be applied in engineering calculations.     

Diagenetic and other highly mineralized waters in the Polish Carpathians

Highly mineralized waters of different chemical types and origin occur in the flysch formations and their bedrocks in the western part of the Polish Carpathians. The marine sedimentation water of the flysch formations is not preserved, as the most mineralized and the heaviest isotopic values of flysch waters are characterized by δ¹⁸O and δ²H values in the ranges of 5–7‰ and −(20–30)‰, respectively. Their origin is related to the dehydration of clay minerals during burial diagenesis, with molecules of marine water completely removed by molecules of released bound water. They are relatively enriched in Na⁺ in respect to the marine water, supposedly due to the release of Na⁺ during the illitization of smectites and preferable incorporation of other cations from the primary brine into newly formed minerals. In some parts of younger formations, i.e. in the Badenian sediments, brines occur with isotopic composition close to SMOW and Cl⁻ contents greatly exceeding the typical marine value of about 19.6 g/L, supposedly due to ultrafiltration. Most probably, the marine water of the flysch formations was similarly enriched chemically in its initial burial stages. Final Cl⁻ contents in diagenetic waters depend on different Cl⁻ contents in the primary brines and on relationships between diagenetic and further ultrafiltration processes. In some areas, diagenetic waters migrate to the surface along fault zones and mix with young local meteoric waters becoming diluted, with the isotope composition scattering along typical mixing lines. In areas with independent CO₂ flow from great depths, they form chloride CO₂-rich waters. Common CO₂-rich waters are formed in areas without near-surface occurrences of diagenetic waters. They change from the HCO₃–Ca type for modern waters to HCO₃–Mg–Ca, HCO₃–Na–Ca and other types with elevated TDS, Mg²⁺ and/or Na⁻ contents for old waters reaching even those of glacial age. Bedrocks of the flysch are represented by Mesozoic and Paleozoic mudstones, sandstones and carbonates, and in some areas by Badenian sediments. Brines of the Mesozoic and Paleozoic bedrocks are usually significantly enriched in Ca²⁺ and Mg²⁺ in comparison with the Badenian brines. By analogy to the deepest brines in the adjacent Upper Silesian Coal Basin, they are supposed to originate from paleometeoric waters of a hot climate.     

LIBS analysis of geomaterials: Geochemical fingerprinting for the rapid analysis and discrimination of minerals

Laser-induced breakdown spectroscopy (LIBS) is a simple atomic emission spectroscopy technique capable of real-time, essentially non-destructive determination of the elemental composition of any substance (solid, liquid, or gas). LIBS, which is presently undergoing rapid research and development as a technology for geochemical analysis, has attractive potential as a field tool for rapid man-portable and/or stand-off chemical analysis. In LIBS, a pulsed laser beam is focused such that energy absorption produces a high-temperature microplasma at the sample surface resulting in the dissociation and ionization of small amounts of material, with both continuum and atomic/ionic emission generated by the plasma during cooling. A broadband spectrometer-detector is used to spectrally and temporally resolve the light from the plasma and record the intensity of elemental emission lines. Because the technique is simultaneously sensitive to all elements, a single laser shot can be used to track the spectral intensity of specific elements or record the broadband LIBS emission spectra, which are unique chemical ‘fingerprints’ of a material. In this study, a broad spectrum of geological materials was analyzed using a commercial bench-top LIBS system with broadband detection from ∼200 to 965 nm, with multiple single-shot spectra acquired. The subsequent use of statistical signal processing approaches to rapidly identify and classify samples highlights the potential of LIBS for ‘geochemical fingerprinting’ in a variety of geochemical, mineralogical, and environmental applications that would benefit from either real-time or in-field chemical analysis.     

The Košice meteorite fall: Recovery and strewn field

We provide the circumstances and details of the fireball observation, search expeditions, recovery, strewn field, and physical characteristics of the Ko?ice meteorite that fell in Slovakia on February 28, 2010. The meteorite was only the 15th case of an observed bolide with a recovered mass and subsequent orbit determination. Despite multiple eyewitness reports of the bolide, only three videos from security cameras in Hungary were used for the strewn field determination and orbit computation. Multiple expeditions of professionals and individual searchers found 218 fragments with total weight of 11.3 kg. The strewn field with the size of 5 × 3 km is characterized with respect to the space distribution of the fragments, their mass and size‐frequency distribution. This work describes a catalog of 78 fragments, mass, size, volume, fusion crust, names of discoverers, geographic location, and time of discovery, which represents the most complex study of a fresh meteorite fall. From the analytical results, we classified the Ko?ice meteorite as an ordinary H5 chondrite.