Understanding the impact of line-of-sight in the ergodic spectral efficiency of cellular networks

In this paper we investigate the impact of lineof-sight (LoS) condition in the ergodic spectral efficiency of cellular networks. To achieve this goal, we have considered the kappa-mu shadowed model, which is a general model that provides an excellent fit to a wide set of propagation conditions. To overcome the mathematical complexity of the analysis, we have split the analysis between large and small-scale effects. Building on the proposed framework, we study a number of scenarios that range from heavily-fluctuating LoS to deterministic-LoS. Finally, we shed light on the interplay between fading severity and spectral efficiency by means of the amount of fading.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Materias primas de la Luna para emprender la colonización espacial

1 página.-- Reportaje.Peer reviewe

Potential of a Two-Stage Variable Compression Ratio Downsized Spark Ignition Engine for Passenger Cars under different driving conditions

[EN] With the aim of reducing pollutant emissions from internal combustion engines (ICE), the application of stoichiometrically operated spark ignition (SI) engines, for light-duty vehicles, has been overcoming the compression ignition (CI) engines market share throughout the past years. The ability of a substantial reduction of the primary harmful emissions (HC, CO, and NOx) through the use of the simple three-way catalyst (TWC) is the main reason for that. Nonetheless, with increasing attention to CO2 emissions, the development of highly efficient downsized SI engines turn to be of enormous interest. The synergies of multiple systems such as direct injection, turbocharger, and variable valve actuation are able to lead the SI efficiencies closer to those of CI engines. However, to enable high load operation on such downsized engines, the compression ratio (CR) must be reduced due to knock limitations, reducing the partial-load operations efficiency. The implementation of two-stage variable compression ratio (VCR) systems enables the extraction of high thermal efficiency with high CR at lower loads and extended knock-free high load operation with low CR. In this study, the evaluation of a two-stage VCR system applied to a state-of-the-art downsized SI engine was made through standard driving cycle simulations. The VCR mechanism is composed of an eccentric element in the small end of the connecting rod, which is rotated to increase/decrease the effective connecting rod length, achieving the CRs of 12.11:1 and 9.56:1. The engine was run in an eddy-current dynamometer test bench throughout the essential operating range to obtain the brake specific fuel consumption (BSFC) map. The VCR mechanism CR switching delay was also experimentally characterized to derive a function of the operating conditions. The measured map was entered into the map-based driving cycle simulation with a sub-model to account for the isolated effects of the transient period encompassing the compression ratio switching. The results show that slow CR transitions lead to fuel consumption penalties, which suggests the need for optimizing the control strategies of the VCR system. Even though this penalty, once the gear up-shift speed is optimized for each driving cycle, the VCR system still enables fuel consumption reductions up to 3% on the WLTC driving cycle, up to 4% on the proposed urban driving cycles and up to 3% on highway driving cycles with respect to the fixed CR.This research has been partially funded by FEDER and the Spanish Government through project RTI2018-102025-B-I00. The authors also acknowledge the Universitat Politecnica de Valencia for partially supporting this research through Convocatoria de ayudas a Primeros Proyectos de Lnvestigacion (PAID-06-18).López, JJ.; García Martínez, A.; Monsalve-Serrano, J.; Vielmo-Cogo, V.; Wittek, K. (2020). Potential of a Two-Stage Variable Compression Ratio Downsized Spark Ignition Engine for Passenger Cars under different driving conditions. Energy Conversion and Management. 203:1-15. https://doi.org/10.1016/j.enconman.2019.112251S115203Amelang S, Wehrmann B. Dieselgate – a timeline of Germany’s car emissions fraud scandal | Clean Energy Wire n.d. https://www.cleanenergywire.org/factsheets/dieselgate-timeline-germanys-car-emissions-fraud-scandal (accessed September 2, 2019).Luján, J. M., Bermúdez, V., Dolz, V., & Monsalve-Serrano, J. (2018). An assessment of the real-world driving gaseous emissions from a Euro 6 light-duty diesel vehicle using a portable emissions measurement system (PEMS). Atmospheric Environment, 174, 112-121. doi:10.1016/j.atmosenv.2017.11.056E, J., Pham, M., Zhao, D., Deng, Y., Le, D., Zuo, W., … Zhang, Z. (2017). Effect of different technologies on combustion and emissions of the diesel engine fueled with biodiesel: A review. Renewable and Sustainable Energy Reviews, 80, 620-647. doi:10.1016/j.rser.2017.05.250Jurić, F., Petranović, Z., Vujanović, M., Katrašnik, T., Vihar, R., Wang, X., & Duić, N. (2019). Experimental and numerical investigation of injection timing and rail pressure impact on combustion characteristics of a diesel engine. Energy Conversion and Management, 185, 730-739. doi:10.1016/j.enconman.2019.02.039E, J., Zhao, X., Qiu, L., Wei, K., Zhang, Z., Deng, Y., … Liu, G. (2019). Experimental investigation on performance and economy characteristics of a diesel engine with variable nozzle turbocharger and its application in urban bus. 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(2016). Influence of fuel properties on fundamental spray characteristics and soot emissions using different tailor-made fuels from biomass. Energy Conversion and Management, 108, 243-254. doi:10.1016/j.enconman.2015.11.010Benajes, J., Pastor, J. V., García, A., & Boronat, V. (2016). A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio. Energy Conversion and Management, 126, 497-508. doi:10.1016/j.enconman.2016.08.023Benajes, J., García, A., Monsalve-Serrano, J., & Villalta, D. (2018). Benefits of E85 versus gasoline as low reactivity fuel for an automotive diesel engine operating in reactivity controlled compression ignition combustion mode. Energy Conversion and Management, 159, 85-95. doi:10.1016/j.enconman.2018.01.015Wang, Z., Liu, H., & Reitz, R. D. (2017). Knocking combustion in spark-ignition engines. Progress in Energy and Combustion Science, 61, 78-112. doi:10.1016/j.pecs.2017.03.004Santos, H., & Costa, M. (2008). Evaluation of the conversion efficiency of ceramic and metallic three way catalytic converters. Energy Conversion and Management, 49(2), 291-300. doi:10.1016/j.enconman.2007.06.008Heck, R. M., & Farrauto, R. J. (2001). Automobile exhaust catalysts. Applied Catalysis A: General, 221(1-2), 443-457. doi:10.1016/s0926-860x(01)00818-3Feng, D., Wei, H., & Pan, M. (2018). Comparative study on combined effects of cooled EGR with intake boosting and variable compression ratios on combustion and emissions improvement in a SI engine. Applied Thermal Engineering, 131, 192-200. doi:10.1016/j.applthermaleng.2017.11.110European Environment Agency (EEA). Monitoring CO2 emissions from new passenger cars and vans in 2017. 2018. doi:10.2800/74986.Society of Motor Manufacturers and Traders (SMMT). Fall in new car market wake up call to policy makers as environmental goals at risk. 2019.Kalghatgi, G. T. (2015). Developments in internal combustion engines and implications for combustion science and future transport fuels. Proceedings of the Combustion Institute, 35(1), 101-115. doi:10.1016/j.proci.2014.10.002Su, J., Xu, M., Li, T., Gao, Y., & Wang, J. (2014). Combined effects of cooled EGR and a higher geometric compression ratio on thermal efficiency improvement of a downsized boosted spark-ignition direct-injection engine. Energy Conversion and Management, 78, 65-73. doi:10.1016/j.enconman.2013.10.041Zhen, X., Wang, Y., Xu, S., Zhu, Y., Tao, C., Xu, T., & Song, M. (2012). The engine knock analysis – An overview. Applied Energy, 92, 628-636. doi:10.1016/j.apenergy.2011.11.079Zhuang, Y., Qian, Y., & Hong, G. (2017). The effect of ethanol direct injection on knock mitigation in a gasoline port injection engine. Fuel, 210, 187-197. doi:10.1016/j.fuel.2017.08.060Zhou, L., Dong, K., Hua, J., Wei, H., Chen, R., & Han, Y. (2018). Effects of applying EGR with split injection strategy on combustion performance and knock resistance in a spark assisted compression ignition (SACI) engine. Applied Thermal Engineering, 145, 98-109. doi:10.1016/j.applthermaleng.2018.09.001Luján, J. M., Climent, H., Novella, R., & Rivas-Perea, M. E. (2015). Influence of a low pressure EGR loop on a gasoline turbocharged direct injection engine. Applied Thermal Engineering, 89, 432-443. doi:10.1016/j.applthermaleng.2015.06.039Li, T., Wang, B., & Zheng, B. (2016). A comparison between Miller and five-stroke cycles for enabling deeply downsized, highly boosted, spark-ignition engines with ultra expansion. Energy Conversion and Management, 123, 140-152. doi:10.1016/j.enconman.2016.06.038Lanzanova, T. D. M., Dalla Nora, M., Martins, M. E. S., Machado, P. R. M., Pedrozo, V. B., & Zhao, H. (2019). The effects of residual gas trapping on part load performance and emissions of a spark ignition direct injection engine fuelled with wet ethanol. Applied Energy, 253, 113508. doi:10.1016/j.apenergy.2019.113508Noce, T., da Silva, R. R., Morais, R., Sales, L. C. M., Hanriot, S. de M., & Sodré, J. R. (2018). Energy factors for flexible fuel engines and vehicles operating with gasoline-ethanol blends. Transportation Research Part D: Transport and Environment, 65, 368-374. doi:10.1016/j.trd.2018.09.002Wittek K, Geiger F, Andert J, Martins MES, Oliveira M. An Overview of VCR Technology and Its Effects on a Turbocharged DI Engine Fueled with Ethanol and Gasoline. SAE Tech Pap 2017:2017-36-0357. doi:10.4271/2017-36-0357.Hiyoshi R. Variable compression ratio engine. US2013/0327302A1, 2013.Moteki K, Fujimoto H, Aoyama S. Variable compression ratio mechanism of reciprocating internal combustion engine. US6505582B2, 2003.Larsen GJ. Reciprocating piston engine with a varying compression ratio. US5025757A, 1991.Wittek K. Hydraulic freewheel for an internal combustion engine with variable compression ratio. US9677469B2, 2017.Rao VDN, German DJ, Vrsek GA, Chottiner E, Madin MM. Variable compression ratio pistons and connecting rods. US6568357B1, 2003.Kleeberg H, Tomazic D, Dohmen J, Wittek K, Balazs A. Increasing Efficiency in Gasoline Powertrains with a Two-Stage Variable Compression Ratio (VCR) System. SAE Tech Pap 2013:2013-01-0288. doi:10.4271/2013-01-0288.Shelby MH, Leone TG, Byrd KD, Wong FK. Fuel Economy Potential of Variable Compression Ratio for Light Duty Vehicles. SAE Int J Engines 2017;10:2017-01-0639. doi:10.4271/2017-01-0639.Boretti, A., & Scalzo, J. (2012). Novel Crankshaft Mechanism and Regenerative Braking System to Improve the Fuel Economy of Light Duty Vehicles and Passenger Cars. SAE International Journal of Passenger Cars - Mechanical Systems, 5(4), 1177-1193. doi:10.4271/2012-01-1755Teodosio L, De Bellis V, Bozza F, Tufano D. Numerical Study of the Potential of a Variable Compression Ratio Concept Applied to a Downsized Turbocharged VVA Spark Ignition Engine. SAE Tech Pap 2017:2017-24–0015. doi:10.4271/2017-24-0015.Hoyer KS, Moore WR, Confer K. A Simulation Method to Guide DISI Engine Redesign for Increased Efficiency using Alcohol Fuel Blends. SAE Int J Engines 2010:2010-01-1203. doi:10.4271/2010-01-1203.Luján, J. M., García, A., Monsalve-Serrano, J., & Martínez-Boggio, S. (2019). Effectiveness of hybrid powertrains to reduce the fuel consumption and NOx emissions of a Euro 6d-temp diesel engine under real-life driving conditions. Energy Conversion and Management, 199, 111987. doi:10.1016/j.enconman.2019.111987Wittek, K., Geiger, F., Andert, J., Martins, M., Cogo, V., & Lanzanova, T. (2019). Experimental investigation of a variable compression ratio system applied to a gasoline passenger car engine. Energy Conversion and Management, 183, 753-763. doi:10.1016/j.enconman.2019.01.037Klein P. Zylinderdruckbasierte Fuellungserfassung für Verbrennungsmotoren 2009.Taylor JR. An introduction to error analysis. 2nd ed. 1997.Gao, J., Chen, H., Li, Y., Chen, J., Zhang, Y., Dave, K., & Huang, Y. (2019). Fuel consumption and exhaust emissions of diesel vehicles in worldwide harmonized light vehicles test cycles and their sensitivities to eco-driving factors. Energy Conversion and Management, 196, 605-613. doi:10.1016/j.enconman.2019.06.038Tsokolis, D., Tsiakmakis, S., Dimaratos, A., Fontaras, G., Pistikopoulos, P., Ciuffo, B., & Samaras, Z. (2016). Fuel consumption and CO2 emissions of passenger cars over the New Worldwide Harmonized Test Protocol. Applied Energy, 179, 1152-1165. doi:10.1016/j.apenergy.2016.07.091T.J. Barlow I. S. McCrae, and P.G. Boulter SL. A reference book of driving cycles for use in the measurement of road vehicle emissions. 2009.André, M. (2004). The ARTEMIS European driving cycles for measuring car pollutant emissions. 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Tratamiento quirúrgico con placa bloqueada en fracturas de fémur distal tipo C en pacientes mayores de 60 años

Objetivo. Determinar el resultado clínico, radiológico y complicaciones asociadas del tratamiento con placa bloqueada en fracturas distales de fémur tipo C en pacientes mayores de 60 años. Material y métodos. Estudio descriptivo retrospectivo de 16 pacientes. Se registraron variables epidemiológicas, comorbilidades, complicaciones y resultados clínicos y radiológicos. Resultados. Edad media de 75,3 años. El seguimiento medio fue de 13,5 meses. La flexión media postoperatoria de la rodilla fue de 61,6º. Sólo un 12,5% de los pacientes no referían gonalgia ni precisaban ayudas para la deambulación al final del seguimiento. Radiológicamente, en un 68,7% la translación femoral era mayor de 5 mm, y en un 31,3% la reducción en el plano lateral no era correcta. Se consiguió la consolidación de la fractura en 13 pacientes (86,6%), con un tiempo medio de 10,2 semanas. Como complicaciones hubo una pseudoartrosis, una consolidación viciosa y una infección. Discusión. El tratamiento de la fractura distal de fémur con placa bloqueada viene avalado en la literatura como un método fiable. Sin embargo, en nuestra serie, hemos tenido un alto porcentaje de malos resultados clínicos con presencia de dolor en la rodilla y necesidad de ayudas para la deambulación.Objective. To evaluate functional and radiographic results, and complications, after surgical treatment with locked plate in fractures of the distal femur in patients 60 years old or older. Material and methods. We reviewed 16 patients. We recorded epidemiological variables, comorbidities, functional and radiographic results. Results. Mean aged of 75,3 years. Mean follow-up of 13,5 months. Mean knee flexion of 61,6º. Only 12,5% of the patients did not refer knee pain and walked unaided. Radiologically, in 68,7% of the patients femoral translation was greater than 5 mm, and in 31,3% lateral reduction was not correct. Fracture healed in 13 patients (86,6%), in a mean time of 10,2 weeks. There were 1 nonunion, 1 malunion, and 1 infection. Discussion. Locked plating is a realiable treatment for distal femoral fractures. But, in our elderly serie, we experienced bad clinical results with high percentage of knee pain and walking aid

Implementation of two color method to investigate late cycle soot oxidation process in a CI engine under low load conditions

[EN] Soot emissions from diesel engines are an important concern in meeting emissions regulations. Soot emissions are the result of two competing processes: soot formation and soot oxidation. Mechanisms of soot formation are discussed extensively in the literature. Equivalence ratio at lift-off length along with residence time and gas temperature play an important role for soot formation in a diffusion flame. Mixing capability and bulk gas temperature are the most important parameters that influence the in-cylinder soot oxidation process. Normally, research studies of soot formation-oxidation processes have been developed under controlled and not completely representative conditions of engine operation in the field. Therefore, the main objective of this work was to develop a simplified methodology to evaluate in cylinder soot oxidation under 'real' engine conditions. In particular the impact of mixing process and bulk gas temperature on late cycle soot oxidation was evaluated. The experimental measurements were made in a production light-duty diesel engine varying those parameters that have been demonstrated in the literature as the most relevant in soot formation - oxidation processes; injection pressure, ambient density and intake air temperature. To measure soot, two color method was applied by means of an optoelectronic pyrometer. To evaluate the mixing capability a specific "tracer" Apparent Combustion Time (ACT(-1)) based on the experimental heat release and injection parameters was defined. The relationship between both parameters was used to explain the soot oxidation process. (C) 2016 Elsevier Ltd. All rights reserved.The authors acknowledge General Motors Global Research & Development for supporting this research.López, JJ.; Martín, J.; García Martínez, A.; Villalta-Lara, D.; Warey, A. (2017). Implementation of two color method to investigate late cycle soot oxidation process in a CI engine under low load conditions. Applied Thermal Engineering. 113:878-890. doi:10.1016/j.applthermaleng.2016.11.095S87889011

Labo-micro: entorno de test para la verificación de microprocesadores experimentales sobre circuitos FPGA.

Versión electrónica de la ponencia presentada en V Congreso de Tecnologías Aplicadas a la Enseñanza de la Electrónica, celebrado en Las Palmas de Gran Canarias en 2002En este documento se presenta un entorno de verificación que permite comprobar el funcionamiento de un microprocesador diseñado en VHDL para ser implementado en un circuito reconfigurable del tipo FPGA. Se ha desarrollado un conjunto de herramientas que permiten a) volcar el diseño en la FPGA, b) utilizar un microcontrolador externo para cargar el programa de prueba y c) observar los resultados de su ejecución a través de una memoria de doble puerto situada entre la FPGA y el microcontrolador

Uso de hardware reconfigurable a través de servicios Web en aplicaciones distribuidas

Este artículo propone una solución sencilla para la utilización de hardware reconfigurable en el contexto de aplicaciones distribuidas. Se ha elegido la tecnología de Servicios Web para proporcionar el acceso remoto a la plataforma reconfigurable. El objetivo es aprovechar las características propias de este tipo de servicios que facilitan el desarrollo de aplicaciones distribuidas junto con las ventajas de utilizar hadrware específico para acelerar el tiempo de ejecución de una tarea crítica. En particular, se ha desarrollado un servicio web para ofrecer, de forma remota, toda la funcionalidad de la plataforma RC1000PP a través de Intenet. Además de las funciones básicas se propone una metodología para el desarrollo de rutinas especializadas de alto nivel, que una vez publicadas, se ofertan para su integración como elemento de proceso en una aplicación distribuida. Con un ejemplo se comprueban las ventajas de esta metodología y se presentan los resultados preliminares del desarrollo de una aplicación.Este trabajo ha sido financiado por la Comunidad Autónoma de Madrid con el número de proyecto 07T/0052/2003-3, y parcialmente financiado por el Programa Europeo No: 100671-CP-1-2002-1-FR-MINERVA-M

On the entropy of a stealth vector-tensor black hole

We apply Wald's formalism to a Lagrangian within generalised Proca gravity that admits a Schwarzschild black hole with a non-trivial vector field. The resulting entropy differs from that of the same black hole in General Relativity by a logarithmic correction modulated by the only independent charge of the vector field. We find conditions on this charge to guarantee that the entropy is a non-decreasing function of the black hole area, as is the case in GR. If this requirement is extended to black hole mergers, we find that for Planck scale black holes, a non-decreasing entropy is possible only if the area of the final black hole is several times larger than the initial total area of the merger. Finally, we discuss some implications of the vector Galileon entropy from the point of view of entropic gravity

Effects of cavitation in common-rail diesel nozzles on the mixing process

[EN] A study to experimentally analyze the effect of cavitation on the mixing process in diesel nozzles was carried out. The mixing process was studied through the spray cone angle. It was characterized in two different scenarios: with the liquid length (nearly realistic conditions, that is, evaporative but non-reactive spray) and the heat release fraction (fully realistic conditions, that is, evaporative and reactive spray). In both studied scenarios, the increase in spray cone angle caused by the cavitation phenomenon, which leads to a better mixing process, has been confirmed. Nevertheless, when the variations of the effective injection velocity and the spray cone angle obtained by comparing a cylindrical nozzle (i.e. a nozzle that promotes the cavitation phenomenon) with a conical nozzle (i.e. a nozzle that inhibits this phenomenon) were analyzed together, it was found that, for the cases studied here, the mixing process worsens with the cylindrical nozzle.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors thank the FPU program of the Spanish Ministry of Education for supporting the PhD studies of Oscar A de la Garza (grant: AP2008-01913) and also thank the PSA Peugeot-Citroen, National Council of Science and Technology (CONACYT) of the Mexican Government (project: CB-239943) and the Royal Academy of Engineering, United Kingdom (project: NRCP/1415/238) for supporting this research.López, JJ.; De La Garza De Leon, O.; De La Morena, J.; Martínez Martínez, S. (2017). Effects of cavitation in common-rail diesel nozzles on the mixing process. International Journal of Engine Research. 18(10):1017-1034. https://doi.org/10.1177/1468087417697759S10171034181