Estrategias evolutivas como una opción para la optimización de funciones no lineales con restricciones

Estrategias de evolución es una técnica bio-inspirada, eficiente y robusta para resolver problemas de optimización donde el espacio de soluciones es no restringido. Sin embargo, esta suposición es irreal en muchos casos porque el espacio de soluciones es limitado por fronteras complejas en la forma de restricciones tanto lineales como no lineales. En este artículo de investigación, se propone una modificación al algoritmo original de estrategias de evolución para optimizar problemas donde el espacio de soluciones es limitado usando restricciones complejas. El método propuesto es basado en el uso de una función de penalización la cual es cero dentro de la región factible, e igual al máximo valor dentro de la región factible cuando se considera un punto que es no factible. La aproximación propuesta es probada usando seis problemas de prueba bien conocidos. En todos los casos, esta aproximación encontró un punto óptimo igual o menor que los valores reportados en la literatura

On the relation between the external structure and the internal characteristics in the near-nozzle field of diesel sprays

[EN] In this paper, a high-resolution visualization technique has been used in combination with an extensively validated 0D model in order to relate the external structure of a diesel spray to the internal properties in the vicinity of the nozzle. For this purpose, three single-hole convergent nozzles with different diameters have been tested for several pressure conditions. The analysis of the obtained images shows that the spray width significantly changes along the very first millimeters of the spray. From the high resolution images captured, two parameters have been evaluated. The first one is the external non-perturbed length, where droplet detachment has not been observed. The second one is a transitional length, defined as the axial position where the spray width increases linearly after a transient behavior, making it possible to establish a spray cone angle definition. Furthermore, the internal liquid core length has been estimated for these nozzles using an extensively validated zero-dimensional model. The intact liquid core length has proved to be correlated with both the transitional length and the non-perturbed length with a very high degree of reliability. In the case of the transitional length, a quadratic correlation has been observed, whereas a linear relationship has been confirmed between the intact core length and the non-perturbed length. The results presented here may help to shed light on better understanding of such a complex process as atomization.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Ministerio de Economia y Competitividad, Spanish Government, under the project 'Comprension de la influencia de combustibles no convencionales en el proceso de injeccion y combustion tipo diesel' (project number TRA2012-36932) The PhD studies of D. Jaramillo have been funded by "Conselleria d'Educacio'Cultura i Esports'' of "Generalitat Valenciana'', Spain, by means of ''Programa Vali+ d per a personal investigador en formacio''. Reference ACIF/2015/040.Benajes, J.; Salvador, FJ.; Carreres, M.; Jaramillo-Císcar, D. (2017). On the relation between the external structure and the internal characteristics in the near-nozzle field of diesel sprays. Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering. 231(3):360-371. https://doi.org/10.1177/0954407016639464S3603712313Desantes, J. M., Payri, R., Salvador, F. J., & Gil, A. (2006). Development and validation of a theoretical model for diesel spray penetration. Fuel, 85(7-8), 910-917. doi:10.1016/j.fuel.2005.10.023Kim, H. J., Park, S. H., & Lee, C. S. (2010). A study on the macroscopic spray behavior and atomization characteristics of biodiesel and dimethyl ether sprays under increased ambient pressure. Fuel Processing Technology, 91(3), 354-363. doi:10.1016/j.fuproc.2009.11.007Klein-Douwel, R. J. H., Frijters, P. J. M., Seykens, X. L. J., Somers, L. M. T., & Baert, R. S. G. (2009). Gas Density and Rail Pressure Effects on Diesel Spray Growth from a Heavy-Duty Common Rail Injector†. Energy & Fuels, 23(4), 1832-1842. doi:10.1021/ef8003569Lee, C. S., Lee, K. H., Reitz, R. D., & Park, S. W. (2006). EFFECT OF SPLIT INJECTION ON THE MACROSCOPIC DEVELOPMENT AND ATOMIZATION CHARACTERISTICS OF A DIESEL SPRAY INJECTED THROUGH A COMMON-RAIL SYSTEM. Atomization and Sprays, 16(5), 543-562. doi:10.1615/atomizspr.v16.i5.50Desantes, J. M., Payri, R., Salvador, F. J., & De la Morena, J. (2010). Influence of cavitation phenomenon on primary break-up and spray behavior at stationary conditions. Fuel, 89(10), 3033-3041. doi:10.1016/j.fuel.2010.06.004Payri, R., Salvador, F. J., Gimeno, J., & Soare, V. (2005). Determination of diesel sprays characteristics in real engine in-cylinder air density and pressure conditions. Journal of Mechanical Science and Technology, 19(11), 2040-2052. doi:10.1007/bf02916497Desantes, J. M., Salvador, F. J., López, J. J., & De la Morena, J. (2010). Study of mass and momentum transfer in diesel sprays based on X-ray mass distribution measurements and on a theoretical derivation. Experiments in Fluids, 50(2), 233-246. doi:10.1007/s00348-010-0919-8Salvador, F. J., Ruiz, S., Gimeno, J., & De la Morena, J. (2011). Estimation of a suitable Schmidt number range in diesel sprays at high injection pressure. International Journal of Thermal Sciences, 50(9), 1790-1798. doi:10.1016/j.ijthermalsci.2011.03.030Linne, M. A., Paciaroni, M., Berrocal, E., & Sedarsky, D. (2009). Ballistic imaging of liquid breakup processes in dense sprays. Proceedings of the Combustion Institute, 32(2), 2147-2161. doi:10.1016/j.proci.2008.07.040Kastengren, A. L., Tilocco, F. Z., Duke, D. J., Powell, C. F., Zhang, X., & Moon, S. (2014). TIME-RESOLVED X-RAY RADIOGRAPHY OF SPRAYS FROM ENGINE COMBUSTION NETWORK SPRAY A DIESEL INJECTORS. Atomization and Sprays, 24(3), 251-272. doi:10.1615/atomizspr.2013008642Kastengren, A., & Powell, C. F. (2014). Synchrotron X-ray techniques for fluid dynamics. Experiments in Fluids, 55(3). doi:10.1007/s00348-014-1686-8Som, S., & Aggarwal, S. K. (2010). Effects of primary breakup modeling on spray and combustion characteristics of compression ignition engines. Combustion and Flame, 157(6), 1179-1193. doi:10.1016/j.combustflame.2010.02.018Lebas, R., Menard, T., Beau, P. A., Berlemont, A., & Demoulin, F. X. (2009). Numerical simulation of primary break-up and atomization: DNS and modelling study. International Journal of Multiphase Flow, 35(3), 247-260. doi:10.1016/j.ijmultiphaseflow.2008.11.005Shinjo, J., & Umemura, A. (2010). Simulation of liquid jet primary breakup: Dynamics of ligament and droplet formation. International Journal of Multiphase Flow, 36(7), 513-532. doi:10.1016/j.ijmultiphaseflow.2010.03.008Shinjo, J., & Umemura, A. (2011). Detailed simulation of primary atomization mechanisms in Diesel jet sprays (isolated identification of liquid jet tip effects). Proceedings of the Combustion Institute, 33(2), 2089-2097. doi:10.1016/j.proci.2010.07.006Ménard, T., Tanguy, S., & Berlemont, A. (2007). Coupling level set/VOF/ghost fluid methods: Validation and application to 3D simulation of the primary break-up of a liquid jet. International Journal of Multiphase Flow, 33(5), 510-524. doi:10.1016/j.ijmultiphaseflow.2006.11.001Bermúdez, V., Payri, R., Salvador, F. J., & Plazas, A. H. (2005). Study of the influence of nozzle seat type on injection rate and spray behaviour. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 219(5), 677-689. doi:10.1243/095440705x28303Payri, F., Bermúdez, V., Payri, R., & Salvador, F. J. (2004). The influence of cavitation on the internal flow and the spray characteristics in diesel injection nozzles. Fuel, 83(4-5), 419-431. doi:10.1016/j.fuel.2003.09.010Payri, R., Molina, S., Salvador, F. J., & Gimeno, J. (2004). A study of the relation between nozzle geometry, internal flow and sprays characteristics in diesel fuel injection systems. KSME International Journal, 18(7), 1222-1235. doi:10.1007/bf02983297Salvador, F. J., Ruiz, S., Salavert, J., & De la Morena, J. (2012). Consequences of using biodiesel on the injection and air–fuel mixing processes in diesel engines. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 227(8), 1130-1141. doi:10.1177/0954407012463667Basak, N., & Das, D. (2009). Photofermentative hydrogen production using purple non-sulfur bacteria Rhodobacter sphaeroides O.U.001 in an annular photobioreactor: A case study. Biomass and Bioenergy, 33(6-7), 911-919. doi:10.1016/j.biombioe.2009.02.007Salvador, F. J., Romero, J.-V., Roselló, M.-D., & Martínez-López, J. (2010). Validation of a code for modeling cavitation phenomena in Diesel injector nozzles. Mathematical and Computer Modelling, 52(7-8), 1123-1132. doi:10.1016/j.mcm.2010.02.027Andriotis, A., & Gavaises, M. (2009). INFLUENCE OF VORTEX FLOW AND CAVITATION ON NEAR-NOZZLE DIESEL SPRAY DISPERSION ANGLE. Atomization and Sprays, 19(3), 247-261. doi:10.1615/atomizspr.v19.i3.30Salvador, F. J., Hoyas, S., Novella, R., & Martínez-López, J. (2011). Numerical simulation and extended validation of two-phase compressible flow in diesel injector nozzles. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 225(4), 545-563. doi:10.1177/09544070jauto1569Salvador, F. J., Martínez-López, J., Caballer, M., & De Alfonso, C. (2013). Study of the influence of the needle lift on the internal flow and cavitation phenomenon in diesel injector nozzles by CFD using RANS methods. Energy Conversion and Management, 66, 246-256. doi:10.1016/j.enconman.2012.10.011Hiroyasu, H. (2000). SPRAY BREAKUP MECHANISM FROM THE HOLE-TYPE NOZZLE AND ITS APPLICATIONS. Atomization and Sprays, 10(3-5), 511-527. doi:10.1615/atomizspr.v10.i3-5.130Sou, A., Hosokawa, S., & Tomiyama, A. (2007). Effects of cavitation in a nozzle on liquid jet atomization. International Journal of Heat and Mass Transfer, 50(17-18), 3575-3582. doi:10.1016/j.ijheatmasstransfer.2006.12.033Macian, V., Bermudez, V., Payri, R., & Gimeno, J. (2003). NEW TECHNIQUE FOR DETERMINATION OF INTERNAL GEOMETRY OF A DIESEL NOZZLE WITH THE USE OF SILICONE METHODOLOGY. Experimental Techniques, 27(2), 39-43. doi:10.1111/j.1747-1567.2003.tb00107.xOtsu, N. (1979). A Threshold Selection Method from Gray-Level Histograms. IEEE Transactions on Systems, Man, and Cybernetics, 9(1), 62-66. doi:10.1109/tsmc.1979.4310076Payri, R., Tormos, B., Salvador, F. J., & Araneo, L. (2008). Spray droplet velocity characterization for convergent nozzles with three different diameters. Fuel, 87(15-16), 3176-3182. doi:10.1016/j.fuel.2008.05.028DELACOURT, E., DESMET, B., & BESSON, B. (2005). Characterisation of very high pressure diesel sprays using digital imaging techniques. Fuel, 84(7-8), 859-867. doi:10.1016/j.fuel.2004.12.003Yue, Y., Powell, C. F., Poola, R., Wang, J., & Schaller, J. K. (2001). QUANTITATIVE MEASUREMENTS OF DIESEL FUEL SPRAY CHARACTERISTICS IN THE NEAR-NOZZLE REGION USING X-RAY ABSORPTION. Atomization and Sprays, 11(4), 471-490. doi:10.1615/atomizspr.v11.i4.100Desantes, J. M., Payri, R., Garcia, J. M., & Salvador, F. J. (2007). A contribution to the understanding of isothermal diesel spray dynamics. Fuel, 86(7-8), 1093-1101. doi:10.1016/j.fuel.2006.10.011Desantes, J. M., Arregle, J., Lopez, J. J., & Cronhjort, A. (2006). SCALING LAWS FOR FREE TURBULENT GAS JETS AND DIESEL-LIKE SPRAYS. Atomization and Sprays, 16(4), 443-474. doi:10.1615/atomizspr.v16.i4.6

New Insights for Benefit of Legume Inclusion in Grazing Systems

The benefits and challenges of legume inclusion in grazing systems have been well documented over time and across different regions. Recent investigations have provided novel insights into the benefits of legume inclusion in grazing systems. Our objective is not to provide a wide overview of the benefits of legume inclusion but to explore novel insights of recent advancements made from studies evaluating legume inclusion in grazing systems. Efficiency of resource use through legume inclusion in grazing systems can reduce the water footprint associated with beef production through improvements in forage nutritive value and animal performance. These efficiencies also translate into improvements in nutrient cycling and nutrient transfer, which are critical for sustaining productivity of grazing systems. Moreover, evidence exists highlighting the importance of root contact between grasses and legumes for sharing N. Provisioning of floral resources from legumes has also been shown to be important for providing habitat for pollinator species. Lastly, soil microbial abundance of microorganisms associated with N2 fixation can be altered according to species present within a pasture, especially when legumes are present. Insights derived from such recent studies continue to provide evidence for the need to continue to develop legume-based grazing agroecosystems

Numerical analysis of flow characteristics in diesel injectors nozzles with convergent-divergent orifices

[EN] The geometry of diesel injector nozzles is known to significantly affect the characteristic spray behavior and emissions formation. In this paper, a novel nozzle concept, consisting of orifices with a convergent-divergent shape, is investigated through Computational Fluid Dynamics techniques. Three of these nozzles, characterized by different degrees of conicity, are compared to a nozzle with cylindrical orifices, which acts as a baseline. A homogeneous equilibrium model, validated against experimental data in previous works by the authors, is used to calculate the eventual cavitation formation inside these orifices. Additionally, the characteristics of the flow at the orifice outlet are analyzed for the four aforementioned nozzles in terms of their steady-state mass flow, effective outlet velocity and area coefficient. The results show that convergent-divergent nozzles exhibit a high cavitation intensity, located in the transition between the convergent and the divergent sections. This high cavitation intensity tends to compensate for the expected velocity decrease induced by the divergent shape, producing effective velocity values similar to those achieved by the cylindrical nozzle in many of the simulated conditions. The characteristics of the flow, together with the higher spray opening angles expected due to the divergent section of the nozzle, may improve atomization and fuel-air mixing processes.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Ministerio de Economia y Competitividad, of the Spanish Government, Project 'Estudio de la interaccion chorro-pared en condiciones realistas de motor' (Grant Number TRA2015-67679-c2-1-R). The PhD studies of David Jaramillo have been funded by "Conselleria d'Educacio Cultura i Esports" of "Generalitat Valenciana", Spain, by means of "Programa Vali+d per a personal investigador en formacio" (reference ACIF/2015/040).Salvador, FJ.; De La Morena, J.; Carreres, M.; Jaramillo-Císcar, D. (2017). Numerical analysis of flow characteristics in diesel injectors nozzles with convergent-divergent orifices. Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering. 231(14):1935-1944. https://doi.org/10.1177/0954407017692220S193519442311

Simulations of micro-sphere/shell 2D silica photonic crystals for radiative cooling

Altres ajuts: the CERCA Program/Generalitat de Catalunya.L'article s'ha publicat sota la OSA Open Access Publishing Agreement https://www.osapublishing.org/submit/review/pdf/OSACopyTransferOAAgrmnt(2017-09-05).pdfPassive daytime radiative cooling has recently become an attractive approach to address the global energy demand associated with modern refrigeration technologies. One technique to increase the radiative cooling performance is to engineer the surface of a polar dielectric material to enhance its emittance atwavelengths in the atmospheric infrared transparency window (8-13 ìm) by outcoupling surface-phonon polaritons (SPhPs) into free-space. Here we present a theoretical investigation of new surface morphologies based upon self-assembled silica photonic crystals (PCs) using an in-house built rigorous coupled-wave analysis (RCWA) code. Simulations predict that silica micro-sphere PCs can reach up to 73 K below ambient temperature, when solar absorption and conductive/convective losses can be neglected. Micro-shell structures are studied to explore the direct outcoupling of the SPhP, resulting in near-unity emittance between 8 and 10 ìm. Additionally, the effect of material composition is explored by simulating soda-lime glass micro-shells, which, in turn, exhibit a temperature reduction of 61 K below ambient temperature. The RCWA code was compared to FTIR measurements of silica micro-spheres, self-assembled on microscope slides

Arc-continent collision and orocline formation: Closing of the Central American seaway

Closure of the Central American seaway was a local tectonic event with potentially global biotic and environmental repercussions. We report geochronological (six U/Pb LA-ICP-MS zircon ages) and geochemical (19 XRF and ICP-MS analyses) data from the Isthmus of Panama that allow definition of a distinctive succession of plateau sequences to subduction-related protoarc to arc volcaniclastic rocks intruded by Late Cretaceous to middle Eocene intermediate plutonic rocks (67.6 ± 1.4 Ma to 41.1 ± 0.7 Ma). Paleomagnetic analyses (24 sites, 192 cores) in this same belt reveal large counterclockwise vertical-axis rotations (70.9° ± 6.7°), and moderate clockwise rotations (between 40° ± 4.1° and 56.2° ± 11.1°) on either side of an east-west trending fault at the apex of the Isthmus (Rio Gatun Fault), consistent with Isthmus curvature. An Oligocene-Miocene arc crosscuts the older, deformed and segmented arc sequences, and shows no significant vertical-axis rotation or deformation. There are three main stages of deformation: 1) left-lateral, strike-slip offset of the arc (∼100 km), and counterclockwise vertical-axis rotation of western arc segments between 38 and 28 Ma; 2) clockwise rotation of central arc segments between 28 and 25 Ma; and 3) orocline tightening after 25 Ma. When this reconstruction is placed in a global plate tectonic framework, and published exhumation data is added, the Central American seaway disappears at 15 Ma, suggesting that by the time of northern hemisphere glaciation, deep-water circulation had long been severed in Central America

Comparative genomics of apomictic root-knot nematodes:Hybridization, ploidy, and dynamic genome change

The Root-Knot Nematodes (RKN; genus Meloidogyne) are important plant parasites causing substantial agricultural losses. The Meloidogyne incognita group (MIG) of species, most of which are obligatory apomicts (mitotic parthenogens), are extremely polyphagous and important problems for global agriculture. While understanding the genomic basis for their variable success on different crops could benefit future agriculture, analyses of their genomes are challenging due to complex evolutionary histories that may incorporate hybridization, ploidy changes, and chromosomal fragmentation. Here we sequence 19 genomes, representing five species of key RKN collected from different geographic origins. We show that a hybrid origin that predated speciation within the MIG has resulted in each species possessing two divergent genomic copies. Additionally, the apomictic MIG species are hypotriploids, with a proportion of one genome present in a second copy. The hypotriploid proportion varies among species. The evolutionary history of the MIG genomes is revealed to be very dynamic, with non-crossover recombination both homogenising the genomic copies, and acting as a mechanism for generating divergence between species. Interestingly, the automictic MIG species M. floridensis differs from the apomict species in that it has become homozygous throughout much of its genome

Epithelial immunomodulation by aerosolized Toll-like receptor agonists prevents allergic inflammation in airway mucosa in mice

Allergic asthma is a chronic inflammatory respiratory disease associated with eosinophilic infiltration, increased mucus production, airway hyperresponsiveness, and airway remodeling. Epidemiologic data reveal that the prevalence of allergic sensitization and associated diseases has increased in the twentieth century. This has been hypothesized to be partly due to reduced contact with microbial organisms (the hygiene hypothesis) in industrialized society. Airway epithelial cells, once considered a static physical barrier between the body and the external world, are now widely recognized as immunologically active cells that can initiate, maintain, and restrain inflammatory responses, such as those that mediate allergic disease. Airway epithelial cells can sense allergens via expression of myriad Toll-like receptors (TLRs) and other pattern-recognition receptors. We sought to determine whether the innate immune response stimulated by a combination of Pam2CSK4 (“Pam2”, TLR2/6 ligand) and a class C oligodeoxynucleotide ODN362 (“ODN”, TLR9 ligand), when delivered together by aerosol (“Pam2ODN”), can modulate the allergic immune response to allergens. Treatment with Pam2ODN 7 days before sensitization to House Dust Mite (HDM) extract resulted in a strong reduction in eosinophilic and lymphocytic inflammation. This Pam2ODN immunomodulatory effect was also seen using Ovalbumin (OVA) and A. oryzae (Ao) mouse models. The immunomodulatory effect was observed as much as 30 days before sensitization to HDM, but ineffective just 2 days after sensitization, suggesting that Pam2ODN immunomodulation lowers the allergic responsiveness of the lung, and reduces the likelihood of inappropriate sensitization to aeroallergens. Furthermore, Pam2 and ODN cooperated synergistically suggesting that this treatment is superior to any single agonist in the setting of allergen immunotherapy