Thermophysical Model for Online Optimization and Control of the Electric Arc Furnace

A dynamic, first-principles process model for a steelmaking electric arc furnace has been developed. The model is an integrated part of an application designed for optimization during operation of the furnace. Special care has been taken to ensure that the non-linear model is robust and accurate enough for real-time optimization. The model is formulated in terms of state variables and ordinary differential equations and is adapted to process data using recursive parameter estimation. Compared to other models available in the literature, a focus of this model is to integrate auxiliary process data in order to best predict energy efficiency and heat transfer limitations in the furnace. Model predictions are in reasonable agreement with steel temperature and weight measurements. Simulations indicate that industrial deployment of Model Predictive Control applications derived from this process model can result in electrical energy consumption savings of 1–2%.

The 3.1 μm absorption feature on asteroids (24) Themis and (65) Cybele is not due to surface water ice

<p>Previous research on Asteroids (24) Themis and (65) Cybele have shown the presence of an absorption feature at 3.1 μm reported to be directly linked to surface water ice. We searched for water vapor escaping from these asteroids with the Herschel Space Observatory HIFI (Heterodyne Instrument for the Far Infrared) Instrument. While no H<sub>2</sub>O line emission was detected, we obtained sensitive 3σ water production rate upper limits of Q(H<sub>2</sub>O)< 4.1×10<sup>26</sup> molecules s<sup>−1</sup> for Themis and Q(H<sub>2</sub>O) <7.6 × 10<sup>26</sup> molecules s<sup>−1</sup> for the case of Cybele. Using a thermophysical model, we merged data from the Subaru/Cooled Mid-Infrared Camera and Spectrometer and the Herschel SPIRE (Spectral and Photometric Imaging Receiver) instrument with the contents of a multi-observatory database and thus derived new radiometric properties for these two asteroids. For Themis, we obtained a thermal inertia G = 20 <sup>+25</sup><sub>-10</sub> J m<sup>−2</sup> s<sup>−1/2</sup> K<sup>−1</sup>, a diameter 192 <sup>+10</sup><sub>-7</sub> km, and a geometric V-band albedo p<sub>V</sub>=0.07±0.01. For Cybele, we found a thermal inertia G = 25<sup>+28</sup><sub>-19</sub> J m<sup>−2</sup> s<sup>−1/2</sup> K<sup>−1</sup>, a diameter 282±9 km, and an albedo pV=0.042±0.005. Using all inputs, we estimated that water ice intimately mixed with the asteroids’ dark surface material would cover <0.0017% (for Themis) and <0.0033% (for Cybele) of their surfaces, while an areal mixture with very clean ice (Bond albedo 0.8 for Themis and 0.7 for Cybele) would cover <2.2% (for Themis) and <1.5% (for Cybele) of their surfaces. Based on these very low percentage coverage values, it is clear that while surface (and subsurface) water ice may exist in small localized amounts on both asteroids, it is not the reason for the observed 3.1 μm absorption feature.</p>

Physical and Mathematical Model and Method for Computing Heat and Mass Transfer Processes in the System of a Stratum Featuring Horizontal Well

In order to solve scientific and engineering problems arising during analysis and development of hard-to-recover hydrocarbon reserves in high-viscosity oil deposits, we performed a numerical study of heat and mass transfer processes in a mixture of water and oil. We achieved these goals by developing a hydrodynamic and thermophysical model of non-steady-state quasi-three-dimensional heat and mass transfer in a stratum featuring a system of horizontal wells. We propose an analytical approach to plotting a dynamic computational grid in a natural semi-fixed coordinate system. We compute streamlines and equipotential lines using the analytical solution proposed, which is based on complex analysis. The object of our investigation is natural strata saturatedby a multiphase fluid. We used the physical and mathematical model and the calculation method proposed to develop a software package and conduct a series of numerical and parametric studies concerning the effects caused by thermophysical properties of rocks and fluids combined with various operation modes in a system of horizontal wells. The paper describes how these parameters affect the rate of oil production in a real high-viscosity oil deposit. We verified the results obtained against actual core sample investigation data and technological parameters of oil deposit development, and further compared them to known analytical solutions and commercial hydrodynamic simulators

Thermophysical model for icy cometary dust particles

Context. Cometary dust particles are subjected to various forces after being lifted off the nucleus. These forces define the dynamics of dust, trajectories, alignment, and fragmentation, which, in turn, have a significant effect on the particle distribution in the coma. Aims. We develop a numerical thermophysical model that is applicable to icy cometary dust to study the forces attributed to the sublimation of ice. Methods. We extended the recently introduced synoptic model for ice-free dust particles to ice-containing dust. We introduced an additional source term to the energy balance equation accounting for the heat of sublimation and condensation. We use the direct simulation Monte Carlo approach with the dusty gas model to solve the mass balance equation and the energy balance equation simultaneously. Results. The numerical tests show that the proposed method can be applied for dust particles covering the size range from tens of microns to centimetres with a moderate computational cost. We predict that for an assumed ice volume fraction of 0.05, particles with a radius, r ≫ 1 mm, at 1.35 AU, may disintegrate into mm-sized fragments due to internal pressure build-up. Particles with r < 1 cm lose their ice content within minutes. Hence, we expect that only particles with r > 1 cm may demonstrate sustained sublimation and the resulting outgassing forces.

Thermophysical model of the Moon from 3.7 to 15 μm

&lt;p&gt;We present a thermophysical model (TPM) of the Moon which matches the observed, global, disk-integrated thermal flux densities of the Moon in the mid-infrared wavelength range for a phase angle range from -90&amp;#176; to +90&amp;#176;.&lt;br /&gt;The model was tested and verified against serendipitous multi-channel HIRS measurements of the Moon obtained by different meteorological satellites (NOAA-11, NOAA-14, NOAA-15, NOAA-17, NOAA-18, NOAA-19, MetOp-A, MetOp-B). The sporadic intrusions of the Moon in the deep space view of these instruments have been extracted in cases where the entire Moon was within the instruments' field of view. The HIRS long-wavelengths channels 1-12 cover the range from 6.5 to 15 &amp;#956;m, the short-wavelengths channels 13-19 are in the 3.7 to 4.6 &amp;#956;m range.&lt;/p&gt; &lt;p&gt;The model is based on an asteroid TPM concept (Lagerros 1996, 1997, 1998; M&amp;#252;ller &amp; Lagerros 1998, 2002), using the known global properties of the Moon (like size, shape, spin properties, geometric albedo, thermal inertia, surface roughness, see Keihm 1984; Racca 1995; Rozitis &amp; Green 2011; Hayne et al. 2017), combined with a model for the spectral hemispherical emissivity which varies between 0.6 and 1.0 in the HIRS wavelength range (Shaw 1998; ECOSTRESS data base: https://ecostress.jpl.nasa.gov/). The spectral emissivity as well as characteristics of the surface roughness are crucial to explain the well-calibrated measurements.&lt;/p&gt; &lt;p&gt;Our Moon model fits the flux densities for the currently available 22 epochs (each time up to 19 channels) with an absolute accuracy of 5-10%. The phase curves at the different wavelengths are well explained. The spectral energy distributions are very sensitive to emissivity and roughness properties. Here, we see minor variations in the model fits, depending on the origin (phase and aspect angle related) of the thermal emission. We also investigated the influence of reflected sunlight at short wavelengths.&lt;/p&gt; &lt;p&gt;Our TPM of the Moon has a wide range of applications: (i) for Earth-observing weather satellites in the context of field of view and photometric calibration (e.g., Burgdorf et al. 2020); (ii) for interplanetary space missions (e.g., Hayabusa2, OSIRIS-REx or BepiColombo) with infrared instruments on board for an in-space characterization of instrument properites (e.g., Okada et al. 2018); (iii) to shed light on the thermal mid-infrared properties of the lunar surface on a global scale; and, (iv) to benchmark thermophysical model techniques for asteroids in the regime below 10 &amp;#956;m (e.g., observed by WISE in the W1 and W2 bands at 3.4 and 4.6 &amp;#956;m, by Spitzer-IRAC at 3.55 and 4.49 &amp;#956;m or from ground in M band at around 5 &amp;#956;m).&lt;/p&gt; &lt;p&gt;&lt;br /&gt;References:&lt;br /&gt;Burgdorf M., et al. 2020, Remote Sens. 12, 1488; Hayne, P. et al. 2017, JGRE 122, 237; Keihm, S.J. 1984, Icarus 60, 568; Lagerros 1996, &amp;#160;A&amp;A 310, 1011; Lagerros 1997, A&amp;A 325, 1226; Lagerros 1998, A&amp;A 332, 1123; M&amp;#252;ller &amp; Lagerros 1998, A&amp;A 338, 340; M&amp;#252;ller &amp; Lagerros 2002, A&amp;A 381, 324; Okada T. et al. 2018, P&amp;SS 158, 46; Racca G. 1995, P&amp;SS 43, 835; Rozitis &amp; Green 2011, MNRAS 415, 2042.&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt;

Possible effects of Mercury surface temperatures on the exosphere

&lt;div&gt; &lt;p&gt;The&amp;#160;BepiColombo&amp;#160;mission is the first European mission to Mercury; the spacecraft will reach its destination in December 2025, and&amp;#8239;will&amp;#160;study in detail the surface, the exosphere and the magnetosphere of the planet.&amp;#160;&lt;/p&gt; &lt;/div&gt; &lt;div&gt; &lt;p&gt;We have developed a thermophysical model with the aim to analyze the dependence of the temperature of the surface and of the layers close to it on the assumptions on the thermophysical properties of the soil. The code solves the one-dimensional heat equation, assumes purely conductive heat propagation and no internal heat sources; the surface is assumed to be composed of a regolith layer with high porosity and density increasing&amp;#8239;with&amp;#160;depth. The illumination conditions are calculated by using a Mercury shape model and the SPICE routines [1].&amp;#160;&lt;/p&gt; &lt;/div&gt; &lt;div&gt; &lt;p&gt;The model will help us to interpret the data that will be provided by the instruments onboard the&amp;#160;BepiColombo&amp;#160;mission. Preliminary calculations have been carried out to analyze the thermal response of the soil as a function of thermal conductivity. The model is currently also used to study the sodium content in the planet's exosphere, whose origin is under investigation [2]; the MESSENGER mission has measured the exospheric sodium content as a function of time, detecting an increase at the &quot;cold poles&quot; (so called because of their lower than average temperature). We therefore want to study the effect of surface temperatures on the sodium content in the exosphere; for this purpose, the temperature distribution calculated with the code is used together with an atmospheric circulation model that calculates the exospheric sodium content [3].&amp;#160;&lt;/p&gt; &lt;/div&gt; &lt;div&gt; &lt;p&gt;A simplified version of the thermophysical code&amp;#8239;is almost ready to be&amp;#160;available to the scientific community through MATISSE [4], the software developed at the SSDC in ASI&amp;#160;and available at&amp;#160;https://tools.ssdc.asi.it/Matisse.&amp;#160;&lt;/p&gt; &lt;/div&gt; &lt;p&gt;[1] Acton, C. H. (1996), Planetary and Space Science, 44, 65-70&lt;br /&gt;[2] Cassidy, T., et al. (2016), GRL, 43, 11 121-128&lt;br /&gt;[3] Mura, A., et al. (2009), Icarus, 1, 1-11&lt;br /&gt;[4] Zinzi, A., et al. (2016), Astronomy &amp; Computing, 15, 16-28&lt;/p&gt;