Simulations of Melting of Encapsulated CaCl2·6H2O for Thermal Energy Storage Technologies

We present in this work simulations using the finite difference approximation in 2D for the melting of an encapsulated phase-change material suitable for heat storage applications; in particular, we study CaCl2·6H2O in a cylindrical encapsulation of internal radius 8 mm. We choose this particular salt hydrate due to its availability and economic feasibility in high thermal mass building walls or storage. Considering only heat conduction, a thermostat is placed far from the capsule, providing heat for the melting of the phase-change material (PCM), which is initially frozen in a water bath. The difference in density between the solid and liquid phases is taken into account by considering a void in the solid PCM. A simple theoretical model is also presented, based on solving the heat equation in the steady state. The kinetics of melting is monitored by the total solid fraction and temperatures in the inner and outer surfaces of the capsule. The effect of different parameters is presented (thermostat temperature, capsule thickness, capsule conductivity and natural convection in the bath), showing the potential application of the method to select materials or geometries of the capsule

HEPPA-II model-measurement intercomparison project: EPP indirect effects during the dynamically perturbed NH winter 2008-2009

Funke, B. et. al..--This work is distributed under the Creative Commons Attribution 3.0 License.We compare simulations from three high-top (with upper lid above 120 km) and five medium-top (with upper lid around 80 km) atmospheric models with observations of odd nitrogen (NOx D NO+NO2), temperature, and carbon monoxide from seven satellite instruments (ACE-FTS on SciSat, GOMOS, MIPAS, and SCIAMACHY on Envisat, MLS on Aura, SABER on TIMED, and SMR on Odin) during the Northern Hemisphere (NH) polar winter 2008/2009. The models included in the comparison are the 3-D chemistry transport model 3dCTM, the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMO-NIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the modelling tools for SOlar Climate Ozone Links studies (SOCOL and CAO-SOCOL), and the Whole Atmosphere Community Climate Model (WACCM4). The comparison focuses on the energetic particle precipitation (EPP) indirect effect, that is, the polar winter descent of NOx largely produced by EPP in the mesosphere and lower thermosphere. A particular emphasis is given to the impact of the sudden stratospheric warming (SSW) in January 2009 and the subsequent elevated stratopause (ES) event associated with enhanced descent of mesospheric air. The chemistry climate model simulations have been nudged toward reanalysis data in the troposphere and stratosphere while being unconstrained above. An odd nitrogen upper boundary condition obtained from MIPAS observations has further been applied to medium-top models. Most models provide a good representation of the mesospheric tracer descent in general, and the EPP indirect effect in particular, during the unperturbed (pre-SSW) period of the NH winter 2008/2009. The observed NOx descent into the lower mesosphere and stratosphere is generally reproduced within 20 %. Larger discrepancies of a few model simulations could be traced back either to the impact of the models' gravity wave drag scheme on the polar wintertime meridional circulation or to a combination of prescribed NOx mixing ratio at the uppermost model layer and low vertical resolution. In March-April, after the ES event, however, modelled mesospheric and stratospheric NOx distributions deviate significantly from the observations. The too-fast and early downward propagation of the NO x tongue, encountered in most simulations, coincides with a temperature high bias in the lower mesosphere (0.2-0.05 hPa), likely caused by an overestimation of descent velocities. In contrast, upper-mesospheric temperatures (at 0.05-0.001 hPa) are generally underestimated by the high-top models after the onset of the ES event, being indicative for too-slow descent and hence too-low NOx fluxes. As a consequence, the magnitude of the simulated NOx tongue is generally underestimated by these models. Descending NOx amounts simulated with mediumtop models are on average closer to the observations but show a large spread of up to several hundred percent. This is primarily attributed to the different vertical model domains in which the NOx upper boundary condition is applied. In general, the intercomparison demonstrates the ability of state-of- the-art atmospheric models to reproduce the EPP indirect effect in dynamically and geomagnetically quiescent NH winter conditions. The encountered differences between observed and simulated NOx, CO, and temperature distributions during the perturbed phase of the 2009 NH winter, however, emphasize the need for model improvements in the dynamical representation of elevated stratopause events in order to allow for a better description of the EPP indirect effect under these particular conditions.This work has been conducted in the frame of the WCRP/ SPARC SOLARIS-HEPPA activity. The IAA team was supported by the Spanish MCINN under grant ESP2014-54362-P and EC FEDER funds. The MPI-MET team was supported by the Max Planck Gesellschaft (MPG), and computational resources were made available by Deutsches Klimarechenzentrum (DKRZ) through support from Bundesministerium fur Bildung und Forschung (BMBF). The FMI team was supported by the Academy of Finland through the projects 276926 (SECTIC: Sun-Earth Connection Through Ion Chemistry), 258165, and 265005 (CLASP: Climate and Solar Particle Forcing). CAO team was supported by the Russian Science Foundation under grant 15-17-10024. SOCOL team was funded by Swiss National Science Foundation (SNSF) grants 200021-149182 (SILA), 200020-163206 (SIMA), and CRSII2-147659 (FUPSOL-II). S. Bender, M. Sinnhuber, and H. Nieder (all KIT) gratefully acknowledge funding by the Helmholtz Association of German Research Centres (HGF), grant VH-NG-624. NCAR is sponsored by the National Science Foundation (NSF). Computing resources for WACCM simulations were provided by the Climate Simulation Laboratory at NCAR's Computational and Information Systems Laboratory, sponsored by the NSF and other agencies. Work at the Jet Propulsion Laboratory, California Institute of Technology, was carried out under a contract with the National Aeronautics and Space Administration. The Atmospheric Chemistry Experiment (ACE), also known as SciSat, is a Canadian-led mission mainly supported by the Canadian Space Agency. Odin is a Swedish-led satellite project funded jointly by Sweden (SNSB), Canada (CSA), Finland (TEKES), and France (CNES) and is part of European Space Agency's (ESA) third-party mission program. We thank two anonymous reviewers for helpful suggestions that led to improvements in the quality of the present work.Peer reviewe

New insights to study the accumulation and erosion processes of fine-grained organic sediments in combined sewer systems from a laboratory scale model

Versión aceptada de https://doi.org/10.1016/j.scitotenv.2020.136923[Abstract:] The deposition and resuspension of sediments are issues of considerable concern in combined sewer systems management. Sediments can produce the loss of hydraulic capacity and odour generation in sewers, and are also considered the main source of pollution due to their occasional uncontrolled discharges into the environment via Combined Sewer Overflows (CSO). Sewer sediments contain granular and cohesive organic fractions that can have a significant influence on bed resistance. In order to address the relationship between sewer sediment composition and its erodibility, accumulation and erosion experiments were performed in a flume test facility fed with wastewater. The flume was placed in a Wastewater Treatment Plant (WWTP), in which different circular pipe geometries were set. Wastewater flow inlet conditions and bed structures were monitored during the experiments. The photogrammetric technique Structure from Motion (SfM) was applied to record the bed deposit structures, providing accurate measurements of the accumulation rates. The SfM was also used to assess sediment transport and the characteristics of the bed forms after the erosion tests. In addition, velocity distributions and shear stress profiles were measured during the erosion tests to characterize flow resistance and sediment erosion. During both accumulation and erosion tests, sediments were sampled in order to analyse their physicochemical properties, thus highlighting the study of the biodegradability of the organic matter. Different deposition periods showed biological transformations in the bed deposit structure, which were seen to affect its cohesion, and in consequence, its erosion threshold. Tests with significant erosion rates agreed in broad terms with dimensionless sediment transport models derived from previous experimental studies performed with partly cohesive and organic materials in sewer pipes.This research was financed by the projects ‘SEDUNIT’ Ref. CGL2015-69094-R and ‘OVALPIPE II’ Ref. RTC-2016-4987-5 (MINECO/FEDER, EU). The authors would like to thank the companies EDAR Bens SA, EMALCSA and ABN Pipe Systems S.L.U. for their assistance with the experimental work

Using a 2D shallow water model to assess Large-Scale Particle Image Velocimetry (LSPIV) and Structure from Motion (SfM) techniques in a street-scale urban drainage physical model

Versión aceptada de https://doi.org/10.1016/j.jhydrol.2019.05.003[Abstract:] Physically-based numerical modelling of surface processes in urban drainage, such as pollutant wash-off or the assessment of flood risks, requires appropriate calibration and terrain elevation data to properly simulate the overland flows and thus to achieve useful results. Accordingly, this study aims to obtain an accurate representation of the runoff generated by three different rain intensities, 30, 50 and 80 mm/h, in a full-scale urban drainage physical model of 36 m2. The study focuses firstly on applying the Structure from Motion (SfM) photogrammetric technique to carry out a high-resolution and accurate topographic survey. This topography was implemented in a 2D shallow water model and the results were compared with those obtained using traditional data point measured topography. Negligible differences were found when comparing the two models with measured discharges at the physical model gully pots. However, significant differences were obtained in the velocity distributions, especially in the shallowest flow areas where drainage channels of a few millimeters’ depth appeared in the high resolution topographic survey. Results from the numerical model were compared with overland flow velocities, determined by applying a modified Large Scale Particle Image Velocimetry (LSPIV) methodology using fluorescent particles. With the SfM topography, the 2D model was able to obtain a better representation of the experimental data, since small scale irregularities of the pavement surface could be represented in the model domain. At the same time, LSPIV was presented as a very suitable tool for the accurate measurement of runoff velocities in urban drainage models, avoiding the interference of raindrop features in the recorded images and with overland water depths in the order of few millimeters.This work was partially supported by the Spanish Ministry of Science, Innovation and Universities [grants number RTI2018-094217-B-C33, UNLC15-DE-2862 and CGL2015-69094-R MINECO/FEDER, UE]. The first author was in receipt of a Spanish Ministry of Science, Innovation and Universities predoctoral grant [FPU14/01778]. The authors would also like to acknowledge the support of Esteban Sañudo in the development of experiments, and the fruitful discussions with Luis Cea, Beatriz Náscher and Paco Vallés

Retrieval of nitric oxide in the mesosphere and lower thermosphere from SCIAMACHY limb spectra

We use the ultra-violet (UV) spectra in the range 230-300 nm from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) to retrieve the nitric oxide (NO) number densities from atmospheric emissions in the gamma-bands in the mesosphere and lower thermosphere. Using 3-D ray tracing, a 2-D retrieval grid, and regularisation with respect to altitude and latitude, we retrieve a whole semi-orbit simultaneously for the altitude range from 60 to 160 km. We present details of the retrieval algorithm, first results, and initial comparisons to data from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Our results agree on average well with MIPAS data and are in line with previously published measurements from other instruments. For the time of available measurements in 2008-2011, we achieve a vertical resolution of 5-10 km in the altitude range 70-140 km and a horizontal resolution of about 9 from 60 S-60 N. With this we have independent measurements of the NO densities in the mesosphere and lower thermosphere with approximately global coverage. This data can be further used to validate climate models or as input for them. © 2013 Author(s).S. Bender and M. Sinnhuber thank the Helmholtz-society for funding this project under the grant number VH-NG-624. The IAA team (M. Lopez-Puertas and B. Funke) was supported by the Spanish MINECO under grant AYA2011-23552 and EC FEDER funds. The SCIAMACHY project was funded by German Aerospace (DLR), the Dutch Space Agency, SNO, and the Belgium ministry. ESA funded the Envisat project. The University of Bremen as Principal Investigator has led the scientific support and development of SCIAMACHY and the scientific exploitation of its data products. We acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology.Peer Reviewe

Variability of NOx in the polar middle atmosphere from October 2003 to March 2004: Vertical transport vs. local production by energetic particles

We use NO, NO2 and CO from MIPAS/ENVISAT to investigate the impact of energetic particle precipitation onto the NOx budget from the stratosphere to the lower mesosphere in the period from October 2003 to March 2004, a time of high solar and geomagnetic activity. We find that in the winter hemisphere the indirect effect of auroral electron precipitation due to downwelling of upper mesospheric/lower thermospheric air into the stratosphere prevails. Its effect exceeds even the direct impact of the very large solar proton event in October/November 2003 by nearly 1 order of magnitude. Correlations of NOx and CO show that the unprecedented high NOx values observed in the Northern Hemisphere lower mesosphere and upper stratosphere in late January and early February are fully consistent with transport from the upper mesosphere/lower thermosphere and subsequent mixing at lower altitudes. In the polar summer Southern Hemisphere, we observed an enhanced variability of NO and NO2 on days with enhanced geomagnetic activity, but this seems to indicate enhanced instrument noise rather than a direct increase due to electron precipitation. A direct effect of electron precipitation onto NOx can not be ruled out, but, if any, it is lower than 3 ppbv in the altitude range 40-56 km and lower than 6 ppbv in the altitude range 56-64 km. An additional significant source of NOx due to local production by precipitating electrons below 70 km exceeding several parts per billion as discussed in previous publications appears unlikely. © Author(s) 2014.M. Sinnhuber gratefully acknowledges funding by the Helmholtz Society HGF (contract VH-NG-624). The IAA team was supported by the Spanish MINECO under grant AYA2011-23552 and EC FEDER funds. We acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology.Peer Reviewe

Aerosols and Water Ice in Jupiter's Stratosphere from UV-NIR Ground-based Observations

Jupiter's atmosphere has been sounded in transmission from the UV to the IR, as if it were a transiting exoplanet, by observing Ganymede while passing through Jupiter's shadow. The spectra show strong extinction due to the presence of aerosols and haze in Jupiter's atmosphere and strong absorption features of methane. Here, we report a new detailed analysis of these observations, with special emphasis on the retrievals of the vertical distribution of the aerosols and their sizes, and the properties and distribution of the stratospheric water ice. Our analysis suggests the presence of aerosols near the equator in the altitude range of 100 hPa up to at least 0.01 hPa, with a layer of small particles (mean radius of 0.1 μm) in the upper part (above 0.1 hPa), an intermediate layer of aerosols with a radius of 0.3 μm, extending between ∼10 and 0.01 hPa, and a layer with larger sizes of ∼0.6 μm at approximately 100-1 hPa. The corresponding loads for each layer are ∼2 × 10 g cm, ∼3.4 × 10 g cm, and ∼1.5 × 10 g cm, respectively, with a total load of ∼2.0 × 10 g cm. The lower and middle layers agree well with previous measurements; but the finer particles of 0.1 μm above 0.01 hPa have not been reported before. The spectra also show two broad features near 1.5 and 2.0 μm, which we attribute to a layer of very small (∼10 nm) HO crystalline ice in Jupiter's lower stratosphere (∼0.5 hPa). While these spectral signatures seem to be unequivocally attributable to crystalline water ice, they require a large amount of water ice to explain the strong absorption features.© 2018. The American Astronomical Society. All rights reserved.We are very grateful to Rafael Escribano, Victor Herrero, Anni Maattanen, Beatriz Mate, Agustin Sanchez-Lavega, and Miguel Angel Satorre for very valuable discussions on the water ice topic. The IAA team was supported by the Spanish MICINN under projects ESP2014-54362-P, ESP2017-87143-R, and EC FEDER funds. This work is also partly financed by the Spanish Ministry of Economics and Competitiveness through grant ESP2013-48391-C4-2-R. M.G.C. is also supported by the MINECO under its >Ramon y Cajal> subprogram

Vibrational quenching of CO2(010) by collisions with O(3P) at thermal energies: A quantum-mechanical study

10 pages, 6 figures, 1 table, 1 appendix.-- PACS nrs.: 34.50.Ez; 33.20.Tp; 33.15.Mt; 31.15.Ar.The CO2(010)–O(3P) vibrational energy transfer (VET) efficiency is a key input to aeronomical models of the energy budget of the upper atmospheres of Earth, Venus, and Mars. This work addresses the physical mechanisms responsible for the high efficiency of the VET process at the thermal energies existing in the terrestrial upper atmosphere (150 K ≤ T ≤ 550 K). We present a quantum-mechanical study of the process within a reduced-dimensionality approach. In this model, all the particles remain along a plane and the O(3P) atom collides along the C(2v) symmetry axis of CO2, which can present bending oscillations around the linear arrangement, while the stretching C–O coordinates are kept fixed at their equilibrium values. Two kinds of scattering calculations are performed on high-quality ab initio potential energy surfaces (PESs). In the first approach, the calculations are carried out separately for each one of the three PESs correlating to O(3P). In the second approach, nonadiabatic effects induced by spin-orbit couplings (SOC) are also accounted for. The results presented here provide an explanation to some of the questions raised by the experiments and aeronomical observations. At thermal energies, nonadiabatic transitions induced by SOC play a key role in causing large VET efficiencies, the process being highly sensitive to the initial fine-structure level of oxygen. At higher energies, the two above-mentioned approaches tend to coincide towards an impulsive Landau-Teller mechanism of the vibrational to translational (V-T) energy transfer.This work has been partially supported by the European Project No. R113-2003-506079 and the DGICYT Spanish Grant Nos. FIS2004-02461 and CTQ-2004-02415/BQU. One of the authors (M.P.d.L.-C.) was supported by the "Ramón y Cajal" Programme and another author (M.L.-P.) by the Spanish projects Nos. REN2001-3249/CLI, ESP2004-01556, and by EC FEDER funds. The calculations presented here were performed at CINECA (the SuperComputer Center of the University of Bologna), the Instituto de Matemáticas y Física Fundamental (CSIC), and CESGA (the SuperComputer Center of Galicia).Peer reviewe

Transdiagnostic model of psychological factors and sex differences in depression in a large sample of Ecuador

Background/Objective: depression represents a leading cause of disability and a major contributor to the overall global burden of disease with women systematically reporting a higher prevalence than men. This study aimed to examine the predictive value and relation of three transdiagnostic psychological factors (perceived stress, psychological inflexibility and loneliness) on depression and its sex differences for the general population in a large sample of Ecuador. Method: a non-probabilistic and non-clinical sample of 16.074 people from across Ecuador were online surveyed using a cross-sectional design. The structural equation model was based on scores from standardized questionnaires as measures of depression, psychological perceived stress, psychological inflexibility, and loneliness. Results: women reported significantly higher levels of depression, mediated by differences in perceived stress, psychological inflexibility and loneliness. Perceived stress was the most important predictor of depression and mediated the effect of loneliness on depression. Complementarily, psychological inflexibility partially mediated the effect of perceived stress and loneliness on depression. The overall model accounted for the 78% of the total variance in depression. Conclusions: results of this study provide a novel and robust transdiagnostic model of sex differences on depression and insights on how to design effective programs for preventing depression targeting modifiable transdiagnostic risk factors.The study was funded by the Particular Technical University of Loja (Ecuador) (PROY-INV-PSI2020-2781). Additional funding to P.R. was provided by the European Union— 'NextGenerationEU' through the Grant for the Requalification of the Spanish University System for 2021-2023 at the Public University of Navarra (Resolution 1402/2021)