Numerical investigation of unsteady processes in combustion using flame transfer function

Hydrogen has been recognized as a clean and sustainable energy carrier to help deliver significant emission reductions and is regarded as an accelerator in achieving a low carbon future. One of the main limitations of the use of hydrogen in combustion systems is the formation of instabilities in lean conditions. Flame instabilities are an undesirable effect, often difficult to predict and eliminate in practical applications. They refer to large amplitude oscillations of one or more characteristic frequencies, arising from the resonant interaction between oscillatory flow and unsteady heat release process [1]. These instabilities can have detrimental effects, such as component vibrations, increased heat transfer rates, flame blow-off or flashback [2]. The control of combustion instabilities is a key aspect to operate in lean conditions and reduce pollutant formation. The key differences of hydrogen as a fuel are its relatively higher adiabatic flame temperature, flame speed and diffusivity, which induce technical challenges to combustor operation. These include increased propensity for flashback and autoignition, as well as higher NOx emissions and different thermoacoustic instability characteristics arising from its higher reactivity and burning rates. In order to understand the influence of such instabilities on combustion it is necessary to characterize them in simplified configurations for which detailed measurements are available. To pursue this objective, an analysis of the flame in frequency is performed, by obtaining the Flame Transfer Function (FTF) when the flame is excited to velocity perturbations. A multi-slit Bunsen burner experiment investigated by V.N. Kornilov et al. [1] is chosen. The infrastructure developed to compute the FTF when applied to different combustion modelling approaches is validated by comparing numerical results against experiments. The results presented are focused on model assessment and validation, so only the methane case is presented

HPC-enabling technologies for high-fidelity combustion simulations

With the increase in computational power in the last decade and the forthcoming Exascale supercomputers, a new horizon in computational modelling and simulation is envisioned in combustion science. Considering the multiscale and multiphysics characteristics of turbulent reacting flows, combustion simulations are considered as one of the most computationally demanding applications running on cutting-edge supercomputers. Exascale computing opens new frontiers for the simulation of combustion systems as more realistic conditions can be achieved with high-fidelity methods. However, an efficient use of these computing architectures requires methodologies that can exploit all levels of parallelism. The efficient utilization of the next generation of supercomputers needs to be considered from a global perspective, that is, involving physical modelling and numerical methods with methodologies based on High-Performance Computing (HPC) and hardware architectures. This review introduces recent developments in numerical methods for large-eddy simulations (LES) and direct-numerical simulations (DNS) to simulate combustion systems, with focus on the computational performance and algorithmic capabilities. Due to the broad scope, a first section is devoted to describe the fundamentals of turbulent combustion, which is followed by a general description of state-of-the-art computational strategies for solving these problems. These applications require advanced HPC approaches to exploit modern supercomputers, which is addressed in the third section. The increasing complexity of new computing architectures, with tightly coupled CPUs and GPUs, as well as high levels of parallelism, requires new parallel models and algorithms exposing the required level of concurrency. Advances in terms of dynamic load balancing, vectorization, GPU acceleration and mesh adaptation have permitted to achieve highly-efficient combustion simulations with data-driven methods in HPC environments. Therefore, dedicated sections covering the use of high-order methods for reacting flows, integration of detailed chemistry and two-phase flows are addressed. Final remarks and directions of future work are given at the end. }The research leading to these results has received funding from the European Union’s Horizon 2020 Programme under the CoEC project, grant agreement No. 952181 and the CoE RAISE project grant agreement no. 951733.Peer ReviewedPostprint (published version

Optimal extensions of compactness properties for operators on Banach function spaces

[EN] Compactness type properties for operators acting in Banach function spaces are not always preserved when the operator is extended to a bigger space. Moreover, it is known that there exists a maximal (weakly) compact linear extension of a (weakly) compact operator if and only if its maximal continuous linear extension to its optimal domain is (weakly) compact. We show that the same happens if we consider AM-compactness for the operator, and we give some partial results regarding Dunford-Pettis operators. Narrow operators-considered as a family defined by a weak compactness type property-are also analyzed from this point of view. Finally, we provide some applications of the fact that an operator from a Banach function space extends to a narrow operator if and only if it is narrow. (C) 2015 Elsevier B.V. All rights reserved.J.M. Calabuig and M.A. Juan were supported by Ministerio de Economía y Competitividad (Spain) (project MTM2011-23164). E. Jiménez Fernández was supported by Junta de Andalucía and FEDER grant P09-FQM-4911 (Spain). E. Jiménez Fernández and E.A. Sánchez-Pérez were supported by Ministerio de Economía y Competitividad (Spain) (project MTM2012-36740-C02-02).Calabuig, JM.; Jiménez Fernández, E.; Juan Blanco, MA.; Sánchez Pérez, EA. (2016). Optimal extensions of compactness properties for operators on Banach function spaces. Topology and its Applications. 203:57-66. https://doi.org/10.1016/j.topol.2015.12.075S576620

Fractura bilateral de epitroclea: a propósito de 1 caso

Presentamos 1 caso infrecuente de fractura bilateral de epitroclea en un paciente varón de 15 años, tratado mediante osteosíntesis con agujas de Kirschner más transposición anterior de ambos nervios cubitales.We present an unfrequent case of bilateral fracture of the medial epicondyle, in a 15-year-old boy that was treated with Kirschner wires and anterior transposition of the ulnar nerve

Solubility of CO2 in three cellulose-dissolving ionic liquids

The solubility of CO2 in three cellulose-dissolving ionic liquids (1-ethyl-3-methylimidazolium diethylphosphate, [Emim][DEP], 1-allyl-3-methylimidazolium chloride, [Amim][Cl], and 1-butyl-3-methylimidazolium chloride, [Bmim][Cl]) at temperatures within 298 and 356 K and pressures up to 6.5 MPa was determined using a Van Ness-type apparatus (static isochoric). It was demonstrated that this device can work in isothermal and isoplethal modes, being the latter faster and more precise. Moreover, it was possible to determine CO2 solubilities in metastable liquid [Bmim][Cl]. Experimental data were modeled using the Extended Henry's law correlation and the group contribution equation of state. New parameters for the binary interaction of CO2 with ionic liquid groups were calculated.Fil: Pérez, Eduardo. Universidad de Valladolid; EspañaFil: de Pablo, Laura. Universidad de Valladolid; EspañaFil: Segovia, J. Juan. Universidad de Valladolid; EspañaFil: Moreau, Alejandro. Universidad de Valladolid; EspañaFil: Sánchez, Francisco Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Bermejo, María Dolores. Universidad de Valladolid; Españ

Déficit de atención e hiperactividad en adultos con adicción a sustancias: ¿TDAH o síndrome secundario al abuso de sustancias?

Existe un cuerpo de investigación, sometido a fuertes intereses comerciales, para considerar la existencia del trastorno por déficit de atención e hiperactividad (TDAH) en adultos, que informa de presuntas prevalencias muy elevadas en población adicta. Otros estudios sugieren cifras mucho menores y más acordes con las observadas en población infantil, utilizando todos, y no sólo algunos, de los criterios diagnósticos establecidos. Puesto que el diagnóstico en el momento actual debe ser meramente sindrómico, los síntomas manifestados por los afectados son de interés crucial. A partir de diversos autoinformes de síntomas de TDAH (ASRS de la OMS), de disfunción ejecutiva (DEX, FrSBe) y de condiciones asociadas (MCMI-II, DII-Short), los datos del presente estudio muestran que es más probable que los síntomas de inatención e hiperactividad observados en sujetos adictos en tratamiento se deban a efectos derivados de la adicción que a condiciones mórbidas previas al abuso de sustancias

El género Amanita Pers. ex Hooker en la provincia de León

Se citan 23 taxa del género Amanita en la provincia de León (Noroeste de España).Se acompaña una clave para su determinación, su distribución provincial, ecología, así como su relación con las series de vegetación.Twenty three taxa of genus Amanita in León province (NW Spain) are quoted.An identification key of all these taxa is provided, as well as their provincial distribution, ecology and their relation with the vegetation serie

Molecular dynamics simulation of surface phenomena due to high electronic excitation ion irradiation in amorphous silica

We studied by means of an atomistic model based on molecular dynamics the thermal evolution of surface atoms in amorphous silica under high electronic excitation produced by irradiation with swift heavy ions. The model was validated with the total and differential yields measured in sputtering experiments with different ions and ion energies showing a very good quantitative prediction capability. Three mechanisms are behind the evolution of the surface region: (1) an ejection mechanism of atoms and clusters with kinetic energy exceeding their binding energy to the sample surface, which explains the experimentally observed angular distributions of emitted atoms, and the correlation of the total sputtering yield with the electronic stopping power and the incidence angle. (2) A collective mechanism of the atoms in the ion track originated by the initial atom motion outwards the track region subsequently followed by the return to the resulting low-density region in the track center. The collective mechanism describes the energy dissipation of bulk atoms and the changes in density, residual stress, defect formation and optical properties. (3) A flow mechanism resulting from the accumulation and subsequent evolution of surface atoms unable to escape. This mechanism is responsible for the crater rim formation.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was funded by the projects Radiafus-5 (PID2019-105325RB-C32) of Spanish Ministry of Science, Technofusion (S2018/EMT-4437) of Madrid Regional Government and Eurofusion (EH150531176). The authors acknowledge the computer resources and technical assistance provided by the Centro de Supercomputación y Visualización de Madrid (CeSViMa) CESVIMA-MAGERIT. AP acknowledges the support of FONDECYT under grants 3190123. EMB thanks support from grant ANPCyT PICTO-UUMM-2019-00048. JK was supported by the Beatriz Galindo Program (BEAGAL18/00130) from the Ministerio de Educación y Formación Profesional of Spain

Urinary Excretion of Mimosine Derivatives by Cows with and without Experience in Consumption of \u3cem\u3eLeucaena leucocephala\u3c/em\u3e

Leucaena leucocephala is a leguminous tree widely distributed in the tropical regions of the world. In Mexico, it has been incorporated into silvopastoral systems and is highly regarded, owing to its high content of crude protein. Nonetheless, L. leucocephala contains secondary metab-olites, such as mimosine, a non-protein free amino acid, which may induce toxic effects in unadapted ruminants that consume the forage (Hammond 1995). Although Synergistes jonesii, an anaerobic bacterium, has the ability to degrade 3,4-DHP and 2,3-DHP to non-toxic compounds (Allison et al. 1992), in Mexico its presence has not yet been confirmed. Recent work has suggested the occurrence of sub-clinical toxicity to 3,4-DHP and 2,3-DHP in cattle grazing L. leucocephala in Australia and Thailand (Graham 2007; Dalzell et al. 2012; Phaikaew et al. 2012). Several options such as the transfer of rumen liquor and the adaptation of ruminants to the intake of L. leucocephala have been studied in an attempt to reduce the excretion of mimosine and its metabolites (Palmer et al. 2010). The aim of the present work was to evaluate the effect of the experience of consumption of L. leucocephala on excretion of mimosine derivatives (3,4-DHP and 2,3-DHP) in the urine of cattle