The Experts below are selected from a list of 336636 Experts worldwide ranked by ideXlab platform
D A Gryaznykh - One of the best experts on this subject based on the ideXlab platform.
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thermonuclear burning ignition and propagation in Surface Layers of neutron stars 1 general study and one zone model without mass flow
Astronomy Letters, 2013Co-Authors: D A GryaznykhAbstract:We develop and study a general model describing ignition and propagation of burning. It is applied to explosive thermonuclear burning in Surface Layers of neutron stars. For this purpose an one-zone model of a thin Surface layer is developed. We study thermonuclear burning ignition and propagation along the layer with its help.
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thermonuclear burning ignition and propagation in Surface Layers of neutron stars 2 multi zone model with mass inflow
Astronomy Letters, 2013Co-Authors: D A GryaznykhAbstract:To study thermonuclear burning ignition and propagation in Surface Layers of neutron stars we develop a multi-zone model of a thin layer dynamics. It takes into account evolution of the layer composition due to flow of matter (accretion) and thermonuclear reactions. Two simplest variants—one-zone single-component and two-zone two-component models—enable to study qualitatively X-ray bursts dynamics for accretion of pure helium matter or hydrogen, helium and heavier elements mixture. Temporal parameters of X-ray bursts are determined from these models. They are compared with observational data.
Yann Kerr - One of the best experts on this subject based on the ideXlab platform.
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l band relative permittivity of organic soil Surface Layers a new dataset of resonant cavity measurements and model evaluation
Remote Sensing, 2016Co-Authors: Simone Bircher, Elena Zakharova, Jean-pierre Wigneron, François Demontoux, Stephen Razafindratsima, M Drusch, Yann KerrAbstract:Global Surface soil moisture products are derived from passive L-band microwave satellite observations. The applied retrieval algorithms include dielectric models (relating soil water content to relative permittivity) developed for mineral soils. First efforts to generate equivalent models for areas where organic Surface Layers are present such as in the high-latitude regions have recently been undertaken. The objective of this study was to improve our still insufficient understanding of L-band emission of organic substrates in prospect of enhancing soil moisture estimations in the high latitudes undergoing most rapid climatic changes. To this end, L-band relative permittivity measurements using a resonant cavity were carried out on a wide range of organic Surface layer types collected at different sites. This dataset was used to evaluate two already existing models for organic substrates. Some samples from underlying mineral Layers were considered for comparison. In agreement with theory the bulk relative permittivity measured in organic substrate was decreased due to an increased bound water fraction (where water molecules are rotationally hindered) compared to the measured mineral material and corresponding output of the dielectric model for mineral soils used in satellite algorithms. No distinct differences in dielectric response were detected in the measurements from various organic layer types, suggesting a generally uniform L-band emission behavior. This made it possible to fit a simple empirical model to the data obtained from all collected organic samples. Outputs of the two existing models both based on only one organic Surface layer type were found to lie within the spread of our measured data, and in close proximity to the derived simple model. This general consensus strengthened confidence in the validity of all these models. The simple model should be suitable for satellite soil moisture retrieval applications as it is calibrated on a wide range of organic substrate types and the entire wetness range, and does not require any auxiliary input that may be difficult to obtain globally. This renders it generically applicable wherever organic Surface Layers are present.
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Soil moisture sensor calibration for organic soil Surface Layers
Geoscientific Instrumentation Methods and Data Systems Discussions, 2016Co-Authors: Simone Bircher, Elena Zakharova, Jean-pierre Wigneron, Mie Andreasen, Johanna Vuollet, Juho Vehviläinen, Kimmo Rautiainen, François Jonard, Lutz Weihermüller, Yann KerrAbstract:This paper's objective is to present generic calibration functions for organic Surface Layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finnish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology (HOBE). For the Decagon 5TE sensor such a function is currently not reported in the literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral Layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified. For the Decagon 5TE, apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large specific Surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger nonlinearity in the sensor response and signal saturation in the high-level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land Surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic Surface layer at the Sodankylä site was significantly improved when the here-proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic Surface Layers at the Sodankylä and HOBE sites are based on the here-proposed natural log fit. The newly derived ThetaProbe fit functions should be used for hand-held applications only, but prove to be of value for the acquisition of instantaneous large-scale soil moisture estimates.
Yu L Girjakova - One of the best experts on this subject based on the ideXlab platform.
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structural phase condition unelastic and plastic behavior and nanohardness of the tini Surface Layers modified by an ion and electron irradiation
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: L L Meisner, A I Lotkov, V P Sivokha, V P Rotshtein, E G Barmina, Yu L GirjakovaAbstract:Abstract Structural-phase conditions, nano- and microhardness of the Ti49.5Ni50.5 alloy Surface Layers modified by the high-dose ion implantation (HDII) and the pulsed low-energy high-current electron beam (LEHCEB) were studied by Auger electron spectroscopy, grazing incidence X-ray diffraction analysis and the CSEM Nano Hardness Tester. It was found that the Ni-depleted Surface layer (>160 nm) was observed for the samples treated by LEHCEB at pressure ∼10−4 mbar. Irradiation in oil-less vacuum does not change the Ni, Ti and O concentration depth profiles. The influence by means LEHCEB and then by HDII (by Zr+ or Ti+ ions) leads to the formation of a Ti–Zr–(Ni
Simone Bircher - One of the best experts on this subject based on the ideXlab platform.
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l band relative permittivity of organic soil Surface Layers a new dataset of resonant cavity measurements and model evaluation
Remote Sensing, 2016Co-Authors: Simone Bircher, Elena Zakharova, Jean-pierre Wigneron, François Demontoux, Stephen Razafindratsima, M Drusch, Yann KerrAbstract:Global Surface soil moisture products are derived from passive L-band microwave satellite observations. The applied retrieval algorithms include dielectric models (relating soil water content to relative permittivity) developed for mineral soils. First efforts to generate equivalent models for areas where organic Surface Layers are present such as in the high-latitude regions have recently been undertaken. The objective of this study was to improve our still insufficient understanding of L-band emission of organic substrates in prospect of enhancing soil moisture estimations in the high latitudes undergoing most rapid climatic changes. To this end, L-band relative permittivity measurements using a resonant cavity were carried out on a wide range of organic Surface layer types collected at different sites. This dataset was used to evaluate two already existing models for organic substrates. Some samples from underlying mineral Layers were considered for comparison. In agreement with theory the bulk relative permittivity measured in organic substrate was decreased due to an increased bound water fraction (where water molecules are rotationally hindered) compared to the measured mineral material and corresponding output of the dielectric model for mineral soils used in satellite algorithms. No distinct differences in dielectric response were detected in the measurements from various organic layer types, suggesting a generally uniform L-band emission behavior. This made it possible to fit a simple empirical model to the data obtained from all collected organic samples. Outputs of the two existing models both based on only one organic Surface layer type were found to lie within the spread of our measured data, and in close proximity to the derived simple model. This general consensus strengthened confidence in the validity of all these models. The simple model should be suitable for satellite soil moisture retrieval applications as it is calibrated on a wide range of organic substrate types and the entire wetness range, and does not require any auxiliary input that may be difficult to obtain globally. This renders it generically applicable wherever organic Surface Layers are present.
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Soil moisture sensor calibration for organic soil Surface Layers
Geoscientific Instrumentation Methods and Data Systems Discussions, 2016Co-Authors: Simone Bircher, Elena Zakharova, Jean-pierre Wigneron, Mie Andreasen, Johanna Vuollet, Juho Vehviläinen, Kimmo Rautiainen, François Jonard, Lutz Weihermüller, Yann KerrAbstract:This paper's objective is to present generic calibration functions for organic Surface Layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finnish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology (HOBE). For the Decagon 5TE sensor such a function is currently not reported in the literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral Layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified. For the Decagon 5TE, apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large specific Surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger nonlinearity in the sensor response and signal saturation in the high-level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land Surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic Surface layer at the Sodankylä site was significantly improved when the here-proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic Surface Layers at the Sodankylä and HOBE sites are based on the here-proposed natural log fit. The newly derived ThetaProbe fit functions should be used for hand-held applications only, but prove to be of value for the acquisition of instantaneous large-scale soil moisture estimates.
C. Chen - One of the best experts on this subject based on the ideXlab platform.
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characteristics of thin Surface Layers of cobalt based alloys deposited by laser cladding
Surface & Coatings Technology, 2006Co-Authors: C. ChenAbstract:Thin Surface Layers of cobalt-based alloys (Stellite 6 and Tribaloy T-900) and 410 stainless steel (SS) were deposited on mild steel substrates by a coaxial laser cladding process. This process could produce a thin Surface layer of less than 0.5 mm with low energy input. Laser-clad Stellite 6 and Tribaloy T-900 specimens exhibited refined dendritic microstructure. The interdendritic eutectics consisted of either small carbides or intermetallic compounds randomly distributed in a cobalt-rich solid solution, unlike the lamellar structure as observed in conventional weld overlays. The hardness values of the laser-clad Layers were generally higher than those of conventional welding deposits owing to the refined effect. The wear and corrosion resistance of S-6 and T-900 specimens were considerably better compared to those of laser-clad 410 SS specimens. In addition, the T-900 specimen had substantially lower corrosion rates than the S-6 specimen in hydrochloric acid solution. Experimental results indicated that wear and corrosion characteristics of the T-900 specimen were excellent; however, preheating was required to avoid cracking in the laser cladding process.
