Alpha-enhancement in the MW: results from the SDSS spectroscopic stellar database

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Spontaneous Symmetry Breakdown in non-relativistic Quantum Mechanics

The advantages and disadvantages of some pedagogical non-relativistic quantum-mechanical models, used to illustrate spontaneous symmetry breakdown, are discussed. A simple quantum-mechanical toy model (a spinor on the line, subject to a magnetostatic interaction) is presented, that exhibits the spontaneous breakdown of an internal symmetry.Comment: 19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1111.1213. Equations (30) and (31) have been corrected. Other minor correction

ADSORPTION ESSAYS OF PALLADIUM IN MODIFIED SILICA GEL WITH THIOURONIUM GROUPS: EXPERIMENTAL AND THEORICAL STUDIES

Indexación: Web of Science; ScieloThe silylant 3-cloropropyltriethoxysilyl was anchored over silica gel in anhydrous conditions in order to react with thiourea to obtain modified silica gel with thiouronium. The aim to obtain an inorganic support that is able to hijack metals from the VIII group such as palladium. The product was characterized by Sbet and FTIR infrared spectroscopy. For the determination of the structure in the modified silica gel NMR spectra of silicon and carbon were preformed in solid state. The coordination form of the modified silica gel to the metal was studied computationally in the context of the DFT theory, using the ADF code. This was a collaborative work with "Fundación Chile" for the recuperation of precious metals from the mining industry.http://ref.scielo.org/gk7rm

Experimental aerothermal characterization of surface air-cooled oil coolers for turbofan engines

[EN] Thermal management is a major challenge for new generation turbofan aero-engines. One of the most promising heat exchangers are the so-called surface air-cooled oil coolers (SACOCs). In this study, an experimental methodology is proposed and implemented in order to characterize SACOCs mounted in turbofan bypass ducts. Three different SACOC geometries have been characterized under the same nominal operating point, while the actual velocity profile in the bypass was reproduced by means of a distortion screen upstream the test section. The heat exchangers were mounted in counterflow configuration and feature the same fin geometry in the oil side. The three prototypes varied only in the air side, being the first a baseline flat plate, the second a SACOC with standard trapezoidal fins and the third featuring optimized fins designed to reduce the pressure drop. Aerothermal results demonstrated that the effect of the SACOC on the bypass flow was confined to a region about the same height and width of the finned area, avoiding the need of reproducing the whole bypass duct. However, for this reduced-height experimental approach to be valid, we show that the velocity profile needs to be rearranged to match the specific section of the whole bypass. We also demonstrate how the optimized fin geometry achieved a 10% lower friction factor than the standard one at nominal flow conditions while increasing the overall heat transfer coefficient by 5.2%.This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union's Horizon 2020 research and innovation programme under grant agreement n° 831977: Aerodynamic upgrade of Surface Air-Cooled Oil Coolers (SACOC). A. Felgueroso is supported through the Programa de Apoyo para la Investigación y Desarrollo of the Universitat Politècnica de València under grant PAID-01-20 n° 21589. The authors also wish to thank Safran Aircraft Engines for their kind permission to share the data presented in this publication. Special thanks are also given to Mr. Adolfo Guzmán for his inestimable support during the experimental campaign.Broatch, A.; Olmeda, P.; Garcia Tiscar, J.; Felgueroso-Rodríguez, A.; Chávez-Modena, M.; González, LM.; Gelain, M.... (2022). Experimental aerothermal characterization of surface air-cooled oil coolers for turbofan engines. International Journal of Heat and Mass Transfer. 190:1-13. https://doi.org/10.1016/j.ijheatmasstransfer.2022.12277511319

Experimental aerothermal characterization of surface air-cooled oil coolers for turbofan engines

[EN] Thermal management is a major challenge for new generation turbofan aero-engines. One of the most promising heat exchangers are the so-called surface air-cooled oil coolers (SACOCs). In this study, an experimental methodology is proposed and implemented in order to characterize SACOCs mounted in turbofan bypass ducts. Three different SACOC geometries have been characterized under the same nominal operating point, while the actual velocity profile in the bypass was reproduced by means of a distortion screen upstream the test section. The heat exchangers were mounted in counterflow configuration and feature the same fin geometry in the oil side. The three prototypes varied only in the air side, being the first a baseline flat plate, the second a SACOC with standard trapezoidal fins and the third featuring optimized fins designed to reduce the pressure drop. Aerothermal results demonstrated that the effect of the SACOC on the bypass flow was confined to a region about the same height and width of the finned area, avoiding the need of reproducing the whole bypass duct. However, for this reduced-height experimental approach to be valid, we show that the velocity profile needs to be rearranged to match the specific section of the whole bypass. We also demonstrate how the optimized fin geometry achieved a 10% lower friction factor than the standard one at nominal flow conditions while increasing the overall heat transfer coefficient by 5.2%.This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union's Horizon 2020 research and innovation programme under grant agreement n° 831977: Aerodynamic upgrade of Surface Air-Cooled Oil Coolers (SACOC). A. Felgueroso is supported through the Programa de Apoyo para la Investigación y Desarrollo of the Universitat Politècnica de València under grant PAID-01-20 n° 21589. The authors also wish to thank Safran Aircraft Engines for their kind permission to share the data presented in this publication. Special thanks are also given to Mr. Adolfo Guzmán for his inestimable support during the experimental campaign.Broatch, A.; Olmeda, P.; Garcia Tiscar, J.; Felgueroso-Rodríguez, A.; Chávez-Modena, M.; González, LM.; Gelain, M.... (2022). Experimental aerothermal characterization of surface air-cooled oil coolers for turbofan engines. International Journal of Heat and Mass Transfer. 190:1-13. https://doi.org/10.1016/j.ijheatmasstransfer.2022.12277511319

uDDS: A Middleware for Real-time Wireless Embedded Systems

[EN] A Real-Time Wireless Distributed Embedded System (RTWDES) is formed by a large quantity of small devices with certain computing power, wireless communication and sensing/actuators capabilities. These types of networks have become popular as they have been developed for applications which can carry out a vast quantity of tasks, including home and building monitoring, object tracking, precision agriculture, military applications, disaster recovery, industry applications, among others. For this type of applications a middleware is used in software systems to bridge the gap between the application and the underlying operating system and networks. As a result, a middleware system can facilitate the development of applications and is designed to provide common services to the applications. The development of a middleware for sensor networks presents several challenges due to the limited computational resources and energy of the different nodes. This work is related with the design, implementation and test of a micro middleware for RTWDES; the proposal incorporates characteristics of a message oriented middleware thus allowing the applications to communicate by employing the publish/subscribe model. Experimental evaluation shows that the proposed middleware provides a stable and timely service to support different Quality of Service (QoS) levels. © 2011 Springer Science+Business Media B.V.This work was developed as a part of the D2ARS Project supported by CYTED. UNESCO code 120325;330417;120314;120305.González, A.; Mata, W.; Villaseñor, L.; Aquino, R.; Simó Ten, JE.; Chávez, M.; Crespo Lorente, A. (2011). uDDS: A Middleware for Real-time Wireless Embedded Systems. Journal of Intelligent and Robotic Systems. 64(3-4):489-503. https://doi.org/10.1007/s10846-011-9550-zS489503643-4Akyildiz, I.F., Su, W., Sankarasubramaniam, Y., Cayirci, E.: A survey on sensor networks. IEEE Commun. Mag. 40, 102–114 (2002)Aquino, R., González, A., Rangel, V., García, M. Villaseñor, L.A., Edwards-Block, A.: Wireless communication protocol based on EDF for wireless body sensor networks, k. Journal of Applied Sciences and Technology 6(2), 104–114 (2008)Bonnet, P., Gehrke, J.E., Seshadri, P.: Querying the physical world. IEEE Pers. Commun. 7(5), 10–15 (2000)Boonma, P., Suzuki, J.: TinyDDS: an interoperable and configurable publish/subscribe middleware for wireless sensor networks. In: Hinze, A., Buchmann, A. (eds.) Handbook of Research on Advanced Distributed Event-based Systems. Publish/Subscribe and Message Filtering Technologies, IGI Global (2009)Cerpa, A., Elson, J., Hamilton, M., Zhao, J.: Habitat monitoring: application driver for wireless communications technology. ACM SIGCOMM Workshop on Data Communications in Latin America and the Caribbean, Costa Rica (2002)Corsaro, A., Schmidt, D.C.: The design and performace of real-time java middleware. IEEE Trans. Parallel Distrib. Syst. 14(11), issn 1045–9219, 1155–1167 (2003)Culler, D.E., Hong, W.: Wireless sensor networks introduction. Commun. ACM 47(6), 30–33 (2004)Estrin, D., Govindan, R., Heidemann, J.S., Kumar, S.: Next century challenges: scalable coordination in sensor networks. In: Mobile Computing and Networking, pp. 263–270 (1999)Heinzelman, W.B., Murphy, A.L., Carvalho, H.S.: Middleware to support sensor network applications. IEEE Netw. 18, 6–14 (2004)Hill, J., Szewczyk, R., Woo, A., Hollar, S., Culler, D., Pister, K.: System architecture directions for networked sensors. ACM SIGOPS Oper. Syst. Rev. 34(5), 93–104 (2000)Levis, P., Culler, D.: Mate: a tiny virtual machine for sensor networks. In: Proceedings of the 10th International Conference on Achitectural Support for Programming Languages and Operating Systems. San Jose, CA (2002)Liu, T., Martonosi, M.: Impala: a middleware system for managing autonomic, parallel sensor systems. In: Proceedings of the Ninth ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming. San Diego, CA (2003)Mata, W., González, A., Aquino, R., Crespo, A., Ripoll, I., Capel, M.: A wireless networked embedded sistem with a new real-time Kernel PaRTiKle. Electronics, Robotics and Automotive Mechanics Conference, CERMA 2007. ISBN 0-7695-2974-7. Cuernavaca, México (2007)Mata, W., González, A., Crespo, A.: A proposal for real-time middleware for wireless sensor networks. Workshop on Sensor Networks and Applications (WseNA’08). Gramado, Brasil (2008)Mata, W., González, A., Fuentes, G., Fuentes, R., Crespo, A., Carr, D.: Porting jRate(RT-Java) to a POSIX real-time Linux Kernel. Tenth Real-Time Linux Workshop. Colotlán, Jalisco México (2008)MiLAN Project: Available: http://www.futurehealth.rochester.edu/milan (2008)OMG, Data Distribution Service for Real-Time Systems Version 1.2. OMG Technical Document (2007)OMG, Model Driven Architecture (MDA), Document Number ormsc/2001-07-01. Technical report, OMG (2001)OMG, Overview and guide to OMGs architecture, OMG Technical Document formal/03-06-01 (2003)Pardo-Castellote, G., Farabaugh, B., Warren, R.: An Introduction to DDS and Data-centric Communications. Available: http://www.omg.org/news/whitepapers/Intro_To_DDS.pdf (2005)Peiro, S., Masmano, M., Ripoll, I., Crespo, A.: PaRTiKle OS, a replacement of the core of RTLinux. In: 9th Real-Time Linux Workshop (2007)Peiro, S., Masmano, M., Ripoll, I., Crespo, A.: PaRTiKle LPC, port to the LPC2000. Tehth Real-Time Linux Workshop. Colotlán, Jalisco M’exico (2008)Pottie, G.J., Kaiser, W.J.: Wireless integrated networks sensors. Commun. ACM 43(5), 52–58 (2000)Souto, E., Guimaraes, G., Vasconcelos, G., Vieira, M., Rosa, N., Ferraz, C., Kelner, J.: Mires: a publish/subscribe middleware for sensor networks. Pers Ubiquit Comput 10(1), 37–44 (2006)St Ville, L., Dickman, P.: Garnet: a middleware architecture for distributing data streams originating in wireless sensor networks. In: Proceedings. 23rd International Conference on Distributed Computing Systems Workshops (2003

The Super Metal Rich Component of the Galaxyx

We present the results obtained by comparing mid-resolution stellar spectra of super metal rich candidates with synthetic spectra computed in the wavelength range 4850-5400 Å. Atmospheric parameters, derived by using the flux fitting method, are illustrated for a sample of representative stars. The final aim of the project is the definition of a fully consistent metallicity scale for SMR stars