Corrosion of Carbon Free and Bonded Refractories for Application in Steel Ingot Casting: An Approach for Improving Steel Quality

2019 ◽  
Vol 959 ◽  
pp. 166-176 ◽  
Author(s):  
Jens Fruhstorfer ◽  
Jana Hubálková ◽  
Thomas Leißner ◽  
Urs A. Peuker ◽  
Christos G. Aneziris
Keyword(s):  
Large Scale ◽  
Steel Ingot ◽  
Surface Region ◽  
Recycling Rate ◽  
Small Scale ◽  
Steel Making ◽  
Removal Of Impurities ◽  
Gaseous Form ◽  
General Appearance

Impurities and resulting inclusions are an issue when processing higher amounts of scrap during steel making. To increase the recycling rate, the removal of impurities from the scrap in form of inclusions is of great interest. In previous studies was found that inclusions attach primarily on carbon containing refractories, especially if on their surface an interfacial layer (1–3 µm thickness) was formed in-situ. This study investigates the formation mechanism of this in-situ layer in detail by application of computer tomography (CT) measurements on two scales. The large scale CT scans visualized the general appearance whereas the small scale measurement regarded the in-situ formed layer and the attached inclusions in detail. Based on these measurements, previous results and a literature review it was concluded that the layer formed mainly due to carbothermally reduced impurities which moved to the decarburized surface of the refractory in gaseous form and enhanced sintering of the surface region to develop the layer.

Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Samper ◽  
R. Juncosa ◽  
V. Navarro ◽  
J. Delgado ◽  
L. Montenegro ◽  
...  
Keyword(s):  
Large Scale ◽  
Reference Model ◽  
Numerical Models ◽  
Full Scale ◽  
Small Scale ◽  
Model Parameters ◽  
In Situ Test ◽  
Wide Range ◽  
Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

scholarly journals On the short-term variability of turbulence and temperature in the winter mesosphere

2018 ◽  
Vol 36 (4) ◽  
pp. 1099-1116
Author(s):  
Gerald A. Lehmacher ◽  
Miguel F. Larsen ◽  
Richard L. Collins ◽  
Aroh Barjatya ◽  
Boris Strelnikov
Keyword(s):  
Attitude Control ◽  
Large Scale ◽  
Lower Thermosphere ◽  
Density Fluctuations ◽  
Large Temperature ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Temperature Structure ◽  
Wind Shears

Abstract. Four mesosphere–lower thermosphere temperature and turbulence profiles were obtained in situ within ∼30 min and over an area of about 100 by 100 km during a sounding rocket experiment conducted on 26 January 2015 at Poker Flat Research Range in Alaska. In this paper we examine the spatial and temporal variability of mesospheric turbulence in relationship to the static stability of the background atmosphere. Using active payload attitude control, neutral density fluctuations, a tracer for turbulence, were observed with very little interference from the payload spin motion, and with high precision (<0.01 %) at sub-meter resolution. The large-scale vertical temperature structure was very consistent between the four soundings. The mesosphere was almost isothermal, which means more stratified, between 60 and 80 km, and again between 88 and 95 km. The stratified regions adjoined quasi-adiabatic regions assumed to be well mixed. Additional evidence of vertical transport and convective activity comes from sodium densities and trimethyl aluminum trail development, respectively, which were both observed simultaneously with the in situ measurements. We found considerable kilometer-scale temperature variability with amplitudes of 20 K in the stratified region below 80 km. Several thin turbulent layers were embedded in this region, differing in width and altitude for each profile. Energy dissipation rates varied between 0.1 and 10 mW kg−1, which is typical for the winter mesosphere. Very little turbulence was observed above 82 km, consistent with very weak small-scale gravity wave activity in the upper mesosphere during the launch night. On the other hand, above the cold and prominent mesopause at 102 km, large temperature excursions of +40 to +70 K were observed. Simultaneous wind measurements revealed extreme wind shears near 108 km, and combined with the observed temperature gradient, isolated regions of unstable Richardson numbers (0<Ri<0.25) were detected in the lower thermosphere. The experiment was launched into a bright auroral arc under moderately disturbed conditions (Kp∼5).

scholarly journals Magnetospheric Processes Possibly Related to the Origin of Cosmic Rays

1981 ◽  
Vol 94 ◽  
pp. 373-391
Author(s):  
Gerhard Haerendel
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Small Scale ◽  
Shear Stresses ◽  
Acceleration Process ◽  
Dayside Magnetopause ◽  
Field Lines ◽  
The Magnetic Field ◽  
Auroral Particles

Two processes are discussed which violate the frozen-in condition in a highly conducting plasma, reconnection and the auroral acceleration process. The first applies to situations in which . It plays an important role in the interaction of the solar wind with the Earth's magnetic field and controls energy input into as well as energetic particle release from the magnetosphere. Detailed in situ studies of the process on the dayside magnetopause reveal its transient and small-scale nature. The auroral acceleration process occurs in the low magnetosphere (β « 1) and accompanies sudden releases of magnetic shear stresses which exist in large-scale magnetospheric-ionospheric current circuits. The process is interpreted as a kind of breaking. The movements of the magnetospheric plasma which lead to a relief of the magnetic tensions occur in thin sheets and are decoupled along the magnetic field lines by parallel electric potential drops. It is this voltage that accelerates the primary auroral particles. The visible arcs are then traces of the magnetic breaking process at several 1000 km altitude.

scholarly journals Instabilities in Pressure Confined Beams and Morphology of Extended Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 229-230
Author(s):  
A. Ferrari ◽  
S. Massaglia ◽  
E. Trussoni ◽  
L. Zaninetti
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Small Scale ◽  
Relativistic Electrons ◽  
Confined Fluid ◽  
Extended Radio ◽  
Cascade Processes ◽  
Intrinsic Correlation

Several authors have suggested that radio jet morphologies resolved in extragalactic sources are the effects of large-scale Kelvin-Helmholtz instabilities in high-speed, pressure-confined fluid beams ejected from parent active galactic nuclei (Ferrari et al. 1978, 1979, 1981; Hardee 1979;Benford et al. 1980). In particular results from studies for cylindrical geometries indicate how to connect the “wiggles” (observed in 3C449, NGC 6251, M87 and Cen A) with helical perturbations and the “knots” (observed in NGC 315, M87, Cen Aetc.) with pinching modes. Correspondingly small scale MHD perturbations, generated by the same instability or nonlinear cascade processes, are efficient in accelerating relativistic electrons via stochastic scatterings (Lacombe 1977; Ferrari et al. 1979). This picture may satisfy both the requirements for in situ re-acceleration and the intrinsic correlation between morphology and emission.

scholarly journals Incidence of rough and irregular atmospheric ice particles from Small Ice Detector 3 measurements

2013 ◽  
Vol 13 (9) ◽  
pp. 24975-25012 ◽  
Author(s):  
Z. Ulanowski ◽  
P. H. Kaye ◽  
E. Hirst ◽  
R. S. Greenaway ◽  
R. J. Cotton ◽  
...  
Keyword(s):  
Light Scattering ◽  
Large Scale ◽  
Extreme Values ◽  
Mixed Phase ◽  
Radiative Properties ◽  
Small Scale ◽  
In Situ Data ◽  
Ice Particles ◽  
Test Particles

Abstract. The knowledge of properties of ice crystals such as size, shape, concavity and roughness is critical in the context of radiative properties of ice and mixed phase clouds. Limitations of current cloud probes to measure these properties can be circumvented by acquiring two-dimensional light scattering patterns instead of particle images. Such patterns were obtained in situ for the first time using the Small Ice Detector 3 (SID-3) probe during several flights in a variety of mid-latitude mixed phase and cirrus clouds. The patterns are analyzed using several measures of pattern texture, selected to reveal the magnitude of particle roughness or complexity. The retrieved roughness is compared to values obtained from a range of well-characterized test particles in the laboratory. It is found that typical in situ roughness corresponds to that found in the rougher subset of the test particles, and sometimes even extends beyond the most extreme values found in the laboratory. In this study we do not differentiate between small-scale, fine surface roughness and large-scale crystal complexity. Instead, we argue that both can have similar manifestations in terms of light scattering properties and also similar causes. Overall, the in situ data is consistent with ice particles with highly irregular or rough surfaces being dominant. Similar magnitudes of roughness were found in growth and sublimation zones of cirrus. The roughness was found to be negatively correlated with the halo ratio, but not with other thermodynamic or microphysical properties found in situ. Slightly higher roughness was observed in cirrus forming in clean oceanic airmasses than in a continental, polluted one. Overall, the roughness and complexity is expected to lead to increased shortwave cloud reflectivity, in comparison with cirrus composed of more regular, smooth ice crystal shapes. These findings put into question suggestions that climate could be modified through aerosol seeding to reduce cirrus cover and optical depth, as the seeding may result in decreased shortwave reflectivity.

scholarly journals Commission 49: The Interplanetary Plasma and the Heliosphere (Plasma Interplanetaire Et L’Heliosphere)

1991 ◽  
Vol 21 (1) ◽  
pp. 581-591
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Small Scale ◽  
International Astronomical Union ◽  
Astrophysical Plasma ◽  
International Astronomical ◽  
Physics Literature ◽  
Interplanetary Plasma ◽  
Vast Range

The heliosphere is a unique laboratory for in situ studies of fundamental astrophysical plasma processes on a vast range of scales. Commission 49 of the International Astronomical Union is devoted to the study of the heliosphere and the plasma processes therein. Traditionally Commission 49 has worked with other IAU Commissions on solar-heliosphere relations, solar wind-planet/comet interactions, and the solar wind-interstellar medium interaction. During the last few years, we have aimed to improve communications between the members of Commission 49 and the plasma physicists in other areas of astrophysics. To that end, this Report focuses on the plasma processes in the heliosphere. The report consists of two reviews: “MHD Flows in the Heliosphere” by S. Suess, which emphasizes the large-scale processes; and “Plasma Processes in the Heliosphere” by F. Verheest, which emphasizes the small-scale processes. These reviews and the accompanying bibliographies should be valuable to plasma physicists in many different fields as a source of ideas and as a guide to the recent heliospheric plasma physics literature. Copies of the Report can be obtained by writing to me at NASA/GSFC; Code 692; Greenbelt, MD 20771, USA.

scholarly journals Large- to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (southwest Pacific)

2018 ◽  
Vol 15 (8) ◽  
pp. 2411-2431 ◽  
Author(s):  
Louise Rousselet ◽  
Alain de Verneil ◽  
Andrea M. Doglioli ◽  
Anne A. Petrenko ◽  
Solange Duhamel ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Mass ◽  
Finite Size ◽  
Small Scale ◽  
General Direction ◽  
The North ◽  
Mesoscale Structures ◽  
Surface Circulation ◽  
Biogeochemical Parameters

Abstract. The patterns of the large-scale, meso- and submesoscale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE cruise (February–April 2015). Multi-disciplinary original in situ observations were achieved along a zonal transect through the WTSP and their analysis was coupled with satellite data. The use of Lagrangian diagnostics allows for the identification of water mass pathways, mesoscale structures, and submesoscale features such as fronts. In particular, we confirmed the existence of a global wind-driven southward circulation of surface waters in the entire WTSP, using a new high-resolution altimetry-derived product, validated by in situ drifters, that includes cyclogeostrophy and Ekman components with geostrophy. The mesoscale activity is shown to be responsible for counter-intuitive water mass trajectories in two subregions: (i) the Coral Sea, with surface exchanges between the North Vanuatu Jet and the North Caledonian Jet, and (ii) around 170∘ W, with an eastward pathway, whereas a westward general direction dominates. Fronts and small-scale features, detected with finite-size Lyapunov exponents (FSLEs), are correlated with 25 % of surface tracer gradients, which reveals the significance of such structures in the generation of submesoscale surface gradients. Additionally, two high-frequency sampling transects of biogeochemical parameters and microorganism abundances demonstrate the influence of fronts in controlling the spatial distribution of bacteria and phytoplankton, and as a consequence the microbial community structure. All circulation scales play an important role that has to be taken into account not only when analysing the data from OUTPACE but also, more generally, for understanding the global distribution of biogeochemical components.

scholarly journals Daily to annual net primary production in the North Sea determined using autonomous underwater gliders and satellite Earth observation

2021 ◽  
Author(s):  
Benjamin Loveday ◽  
Timothy Smyth ◽  
Anıl Akpinar ◽  
Tom Hull ◽  
Mark Inall ◽  
...  
Keyword(s):  
Time Series ◽  
Primary Production ◽  
North Sea ◽  
Large Scale ◽  
Net Primary Production ◽  
Earth Observation ◽  
Small Scale ◽  
The North ◽  
The North Sea

Abstract. Shelf-seas play a key role in both the global carbon cycle and coastal marine ecosystems through the drawn-down and fixing of carbon, as measured through phytoplankton net primary production (NPP). Measuring NPP in situ, and extrapolating this to the local, regional and global scale presents challenges however because of limitations with the techniques utilised (e.g. radiocarbon isotopes), data sparsity and the inherent biogeochemical heterogeneity of coastal and open-shelf waters. Here, we introduce a powerful new technique based on the synergistic use of in situ glider profiles and satellite Earth Observation measurements which can be implemented in a real-time or delayed mode system. We apply this system to a fleet of gliders successively deployed over a 19-month time-frame in the North Sea, generating an unprecedented fine scale time-series of NPP in the region (Loveday and Smyth, 2020). At the large-scale, this time-series gives close agreement with existing satellite-based estimates of NPP for the region and previous in situ estimates. What has not been elucidated before is the high-frequency, small-scale, depth-resolved variability associated with bloom phenology, mesoscale phenomena and mixed layer dynamics.

scholarly journals Large to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (SouthWest Pacific)

2017 ◽  
Author(s):  
Louise Rousselet ◽  
Alain de Verneil ◽  
Andrea M. Doglioli ◽  
Anne A. Petrenko ◽  
Solange Duhamel ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Mass ◽  
Finite Size ◽  
Small Scale ◽  
General Direction ◽  
The North ◽  
Mesoscale Structures ◽  
Surface Circulation ◽  
Biogeochemical Parameters

Abstract. The patterns of the large-scale, meso- and submesoscale surface circulation on biogeochemical and biological distributions are examined in the Western Tropical South Pacific (WTSP) in the context of the OUTPACE cruise (Feb–April 2015). Multi-disciplinary original in situ observations were achieved along a zonal transect through the WTSP and their analysis was coupled with satellite data. The use of Lagrangian diagnostics allows for the identification of water mass pathways, mesoscale structures, and submesoscale features such as fronts. In particular, we confirmed the existence of a global wind-driven southward circulation of surface waters in the entire WTSP, using a new high-resolution altimetry-derived product, validated by in situ drifters, that includes cyclogeostrophy and Ekman components with geostrophy. Two subregions show counter-intuitive water mass trajectories due to mesoscale circulation: i) the Coral Sea with surface exchanges between the North Vanuatu Jet and the North Caledonian Jet; and ii) the zonal band between 180° W and 170° W with an eastward propagation whereas a westward general direction dominates. Fronts and small-scale features, detected with Finite-Size Lyapunov Exponents (FSLE), are correlated with 25 % of surface tracer gradients which reveals the significance of such structures in the generation of submesoscale surface gradients. Additionally, two high-frequency sampling transects of biogeochemical parameters and micro-organism abundances demonstrate the influence of fronts in controlling the spatial distribution of bacteria and phytoplankton, and as a consequence the microbial community structure. All circulation scales play an important role that has to be taken into account when analysing the data from OUTPACE but also, more generally, to understand the global distribution of biogeochemical components.

Hyperresolution Land Surface Modeling in the Context of SMAP Cal–Val

2015 ◽  
Vol 17 (1) ◽  
pp. 345-352 ◽  
Author(s):  
Camille Garnaud ◽  
Stéphane Bélair ◽  
Aaron Berg ◽  
Tracy Rowlandson
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Land Surface ◽  
Large Scale ◽  
Initial Conditions ◽  
Surface Condition ◽  
Soil Conditions ◽  
Small Scale ◽  
In Situ Observations

Abstract This study explores the performance of Environment Canada’s Surface Prediction System (SPS) in comparison to in situ observations from the Brightwater Creek soil moisture observation network with respect to soil moisture and soil temperature. To do so, SPS is run at hyperresolution (100 m) over a small domain in southern Saskatchewan (Canada) during the summer of 2014. It is shown that with initial conditions and surface condition forcings based on observations, SPS can simulate soil moisture and soil temperature evolution over time with high accuracy (mean bias of 0.01 m3 m−3 and −0.52°C, respectively). However, the modeled spatial variability is generally much weaker than observed. This is likely related to the model’s use of uniform soil texture, the lack of small-scale orography, as well as a predefined crop growth cycle in SPS. Nonetheless, the spatial averages of simulated soil conditions over the domain are very similar to those observed, suggesting that both are representative of large-scale conditions. Thus, in the context of the National Aeronautics and Space Administration’s (NASA) Soil Moisture Active Passive (SMAP) project, this study shows that both simulated and in situ observations can be upscaled to allow future comparison with upcoming satellite data.

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