Contratación pública y competencia: análisis económico, legislativo y recomendaciones para el sector en España y Andalucía

La contratación pública es una actividad de gran relevancia económica, representando en torno al 18% del PIB. Por ello, es importante que se introduzcan criterios y principios que fomenten la competencia. Con estos criterios se pretende mejorar la eficiencia y conseguir un mayor bienestar para la sociedad en general. Además, al tratarse de una actividad que se financia fundamentalmente con recursos públicos, la eficiencia debe de ser uno de los pilares básicos. Se trata de un sector sometido a una gran cantidad de regulación, que, además, sufre cambios constantes a lo largo del tiempo. Por ello, el presente trabajo se marca como objetivo servir como guía de las principales normas vigentes en el ámbito de la contratación y sus principales efectos sobre la competencia. También se analizan diversas guías emitidas por distintos organismos oficiales, que pretenden ayudar a resolver los principales problemas que presenta la contratación pública, teniendo en cuenta los principios de competencia. Por último, se realiza un análisis de diversos expedientes resueltos por las autoridades de defensa de la competencia, para estudiar las medidas tomadas en aquellos casos en los que se detecten limitaciones en la competencia.Universidad de Sevilla. Máster Universitario en Consultoría Económica y Análisis Aplicad

Refuerzo estructural y mejora energética vivienda unifamiliar en el barrio del Cabañal

[ES] El objetivo principal de este TFG consiste en realizar el refuerzo estructural de una vivienda, además de adaptarla a las nuevas exigencias de eficiencia energética. Se trata de una vivienda unifamiliar cuya planta baja ha sido reformada pero aún presenta problemas de humedades. La planta superior no ha sido modificada desde su fecha de construcción y presenta el mismo problema de humedad además de numerosas fisuras. Desde el punto de vista del acondicionamiento térmico de la vivienda, se está desperdiciando mucha energía debido a los puentes térmicos entre el exterior y el interior de la vivienda, y a la ausencia de aislantes tanto en cubierta como en algunos muros de fachada. Esto conlleva pérdidas económicas sustanciales. Con el fin de lograr el objetivo propuesto previamente y reconocidas las lesiones, se propondrán soluciones para evitar que se vuelvan a producir las patologías. Asimismo, se realizará un estudio de los elementos necesarios para mejorar la eficiencia energética y las soluciones adoptadas para esta mejora. Para finalizar se realizará un estudio del ahorro económico que supone realizar las mejoras en la vivienda. Llevando a cabo una comparativa entre el dinero invertido en la rehabilitación de la vivienda, el ahorro que supondrían estas mejoras a largo plazo y la amortización de estas.[EN] The aim of this Bachelor’s Thesis is the structural reinforcement of a single family house in the Cabanyal neighbourhood in the city of Valencia, besides adapting it to the new requirements of regulations about energetic efficiency. It’s a single family house whose ground floor has been remodelled; notwithstanding, it still presents a big amount of humidity problems. The upper floor has not been modified since its original building date and shows not just humidity problems but also a large number of fissures in the walls. For what it refers to the heating systems, a big amount of energy is being wasted because of the thermal bridges between the inside and the outside of the housing, and also due to the lack of thermal insulation in the roof as well as in some façade walls. These facts lead to important economic losses. In order to achieve the objectives, once the pathologies have been detected, the solutions needed to avoid the resurgence of these pathologies are exposed. A study of the essential elements required for the improvement of the energetic efficiency and the solutions adopted are also presented. Finally, it will be done a research about the economic savings these measures provide, comparing the funds invested in the housing rehabilitation and the savings that these measures and their amortization would represent.Rubio Perez, S. (2015). Refuerzo estructural y mejora energética vivienda unifamiliar en el barrio del Cabañal. http://hdl.handle.net/10251/55274.TFG

Slicing unconditional jumps with unnecessary control dependencies

[EN] Program slicing is an analysis technique that has a wide range of applications, ranging from compilers to clone detection software, and that has been applied to practically all programming languages. Most program slicing techniques are based on a widely extended program representation, the System Dependence Graph (SDG). However, in the presence of unconditional jumps, there exist some situations where most SDG-based slicing techniques are not as accurate as possible, including more code than strictly necessary. In this paper, we identify one of these scenarios, pointing out the cause of the inaccuracy, and describing the initial solution to the problem proposed in the literature, together with an extension, which solves the problem completely. These solutions modify both the SDG generation and the slicing algorithm. Additionally, we propose an alternative solution, that solves the problem by modifying only the SDG generation, leaving the slicing algorithm untouched.This work has been partially supported by the EU (FEDER) and the Spanish MCI/AEI under grants TIN2016-76843-C4-1-R and PID2019-104735RB-C41, by the Generalitat Valenciana under grant Prometeo/2019/098 (DeepTrust), and by TAILOR, a project funded by EU Horizon 2020 research and innovation programme under GA No 952215Galindo-Jiménez, CS.; Pérez-Rubio, S.; Silva, J. (2021). Slicing unconditional jumps with unnecessary control dependencies. Lecture Notes in Computer Science. 12561:293-308. https://doi.org/10.1007/978-3-030-68446-4_15S2933081256

Statistical Analysis of Students Behavioral and Attendance Habits in Engineering Education

[EN] This study aims at quantifying the relationship between the marks of students and their seating position in the classroom. The study is cross-sectional, quantitative, observational, and correlational. It analyzed data collected throughout two academic years about the students¿ marks (in different terms, courses, and degrees) and about their daily seating position (so, every change was recorded) for both theory and practice lessons. The quantitative data collected in the study was statistically analyzed. The main result is that the seating position is significantly correlated with the marks in the studied context (engineering schools with classrooms with 5-66 students). Other side results show a positive influence on marks of working alone with respect to sharing the computer with a classmate; indicate where do students who give up the course usually sit, and when in the academic term do, they give up. This article provides empirical data with regards to the relation between classroom seating and academic performance in engineering schools. The results obtained quantify this relation, but they cannot determine whether it is causal, consequential, or both. This study complements other studies that correlated motivation with seating preferences.This work has been partially supported by MINECO/AEI/FEDER (EU), under grant TIN2016-76843-C4-1-R; and Generalitat Valenciana, under grant PROMETEO-II/2015/013 (SmartLogic).Ibáñez, V.; Pérez-Rubio, S.; Silva, J.; Tamarit Muñoz, S. (2019). Statistical Analysis of Students Behavioral and Attendance Habits in Engineering Education. Educational Sciences: Theory & Practice. 19(4):48-64. https://doi.org/10.12738/estp.2019.4.004S486419

On the focusing enhancement of Soret zone plates with ultrasound directional transducers

All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).[EN] This work analyzes the influence of the distribution of transparent Fresnel regions over the focusing profile of Soret Zone Plates. It is shown that this effect becomes very significant in those fields where directional transducers are employed, such as microwaves or acoustics. A thorough analysis on both the lens transmission efficiency and the focusing enhancement factor is presented. Moreover, experimental measurements are also carried out, validating the theoretical model and demonstrating that the distribution of transparent Fresnel regions becomes a critical parameter in applications requiring directional emitters.This work was supported by Spanish MINECO TEC2015-70939-R and MICINN RTI2018-100792-B-I00 projects. S.P.-L. acknowledges financial support from Universitat Politecnica de Valencia Grant Program No. PAID-01-18.Pérez-López, S.; Fuster Escuder, JM.; Candelas Valiente, P.; Rubio Michavila, C. (2019). On the focusing enhancement of Soret zone plates with ultrasound directional transducers. Applied Physics Letters. 114(22):224101-1-224101-5. https://doi.org/10.1063/1.5100219S224101-1224101-511422Chen, J., Xiao, J., Lisevych, D., Shakouri, A., & Fan, Z. (2018). Deep-subwavelength control of acoustic waves in an ultra-compact metasurface lens. Nature Communications, 9(1). doi:10.1038/s41467-018-07315-6Liang, Z., & Li, J. (2012). Extreme Acoustic Metamaterial by Coiling Up Space. Physical Review Letters, 108(11). doi:10.1103/physrevlett.108.114301Li, Y., Liang, B., Tao, X., Zhu, X., Zou, X., & Cheng, J. (2012). Acoustic focusing by coiling up space. Applied Physics Letters, 101(23), 233508. doi:10.1063/1.4769984Li, Y., Yu, G., Liang, B., Zou, X., Li, G., Cheng, S., & Cheng, J. (2014). Three-dimensional Ultrathin Planar Lenses by Acoustic Metamaterials. Scientific Reports, 4(1). doi:10.1038/srep06830Xia, J., Zhang, X., Sun, H., Yuan, S., Qian, J., & Ge, Y. (2018). Broadband Tunable Acoustic Asymmetric Focusing Lens from Dual-Layer Metasurfaces. Physical Review Applied, 10(1). doi:10.1103/physrevapplied.10.014016Kipp, L., Skibowski, M., Johnson, R. L., Berndt, R., Adelung, R., Harm, S., & Seemann, R. (2001). Sharper images by focusing soft X-rays with photon sieves. Nature, 414(6860), 184-188. doi:10.1038/35102526Rodrigues Ribeiro, R. S., Dahal, P., Guerreiro, A., Jorge, P. A. S., & Viegas, J. (2017). Fabrication of Fresnel plates on optical fibres by FIB milling for optical trapping, manipulation and detection of single cells. Scientific Reports, 7(1). doi:10.1038/s41598-017-04490-2Hristov, H. D., & Herben, M. H. A. J. (1995). Millimeter-wave Fresnel-zone plate lens and antenna. IEEE Transactions on Microwave Theory and Techniques, 43(12), 2779-2785. doi:10.1109/22.475635Hristov, H. D., & Rodriguez, J. M. (2012). Design Equation for Multidielectric Fresnel Zone Plate Lens. IEEE Microwave and Wireless Components Letters, 22(11), 574-576. doi:10.1109/lmwc.2012.2224099Molerón, M., Serra-Garcia, M., & Daraio, C. (2014). Acoustic Fresnel lenses with extraordinary transmission. Applied Physics Letters, 105(11), 114109. doi:10.1063/1.4896276Calvo, D. C., Thangawng, A. L., Nicholas, M., & Layman, C. N. (2015). Thin Fresnel zone plate lenses for focusing underwater sound. Applied Physics Letters, 107(1), 014103. doi:10.1063/1.4926607Pérez-López, S., Fuster, J. M., Candelas, P., Rubio, C., & Belmar, F. (2018). On the use of phase correction rings on Fresnel zone plates with ultrasound piston emitters. Applied Physics Letters, 112(26), 264102. doi:10.1063/1.503671

Design of Binary-Sequence Zone Plates in High Wavelength Domains

[EN] The design of zone plates is an important topic in many areas of physics, such as optics, X-rays, microwaves or ultrasonics. In this paper, a zone plate design method, which provides high flexibility in the shaping of the focusing profile, is analyzed. This flexibility is achieved through the use of binary sequences that produce zone plates with different properties and applications. It is shown that this binary-sequence method works properly at low wavelengths, but requires a modification term to work accurately in high wavelength domains. This additional term extends this powerful design method to any wavelength. Simulation results show acoustic focusing profiles for Fresnel, Fibonacci and Cantor zone plates operating at a wavelength of 1.5 mm without any distortion.This work was supported by the Spanish MINECO (TEC2015-70939-R).Fuster Escuder, JM.; Pérez-López, S.; Candelas Valiente, P.; Rubio Michavila, C. (2018). Design of Binary-Sequence Zone Plates in High Wavelength Domains. Sensors. 18(8):2604-1-2604-8. https://doi.org/10.3390/s18082604S2604-12604-8188Tamura, S., Yasumoto, M., Kamijo, N., Takeuchi, A., Uesugi, K., Terada, Y., & Suzuki, Y. (2009). Quasi-blazed type multilayer zone plate for X-rays. Vacuum, 84(5), 578-580. doi:10.1016/j.vacuum.2009.03.037Hristov, H. D., & Rodriguez, J. M. (2012). Design Equation for Multidielectric Fresnel Zone Plate Lens. IEEE Microwave and Wireless Components Letters, 22(11), 574-576. doi:10.1109/lmwc.2012.2224099Yang, R., Tang, W., & Hao, Y. (2011). A broadband zone plate lens from transformation optics. Optics Express, 19(13), 12348. doi:10.1364/oe.19.012348Calvo, D. C., Thangawng, A. L., Nicholas, M., & Layman, C. N. (2015). Thin Fresnel zone plate lenses for focusing underwater sound. Applied Physics Letters, 107(1), 014103. doi:10.1063/1.4926607Stout-Grandy, S. M., Petosa, A., Minin, I. V., Minin, O. V., & Wight, J. (2006). A Systematic Study of Varying Reference Phase in the Design of Circular Fresnel Zone Plate Antennas. IEEE Transactions on Antennas and Propagation, 54(12), 3629-3637. doi:10.1109/tap.2006.886552Fuster, J., Candelas, P., Castiñeira-Ibáñez, S., Pérez-López, S., & Rubio, C. (2017). Analysis of Fresnel Zone Plates Focusing Dependence on Operating Frequency. Sensors, 17(12), 2809. doi:10.3390/s17122809Kennedy, J. E., Wu, F., ter Haar, G. R., Gleeson, F. V., Phillips, R. R., Middleton, M. R., & Cranston, D. (2004). High-intensity focused ultrasound for the treatment of liver tumours. Ultrasonics, 42(1-9), 931-935. doi:10.1016/j.ultras.2004.01.089Monsoriu, J. A., Calatayud, A., Remon, L., Furlan, W. D., Saavedra, G., & Andres, P. (2013). Bifocal Fibonacci Diffractive Lenses. IEEE Photonics Journal, 5(3), 3400106-3400106. doi:10.1109/jphot.2013.2248707Saavedra, G., Furlan, W. D., & Monsoriu, J. A. (2003). Fractal zone plates. Optics Letters, 28(12), 971. doi:10.1364/ol.28.000971Ferrando, V., Giménez, F., Furlan, W. D., & Monsoriu, J. A. (2015). Bifractal focusing and imaging properties of Thue–Morse Zone Plates. Optics Express, 23(15), 19846. doi:10.1364/oe.23.019846Machado, F., Ferrando, V., Furlan, W. D., & Monsoriu, J. A. (2017). Diffractive m-bonacci lenses. Optics Express, 25(7), 8267. doi:10.1364/oe.25.00826

Analysis of Fresnel Zone Plates Focusing Dependence on Operating Frequency

[EN] The focusing properties of Fresnel Zone Plates (FZPs) against frequency are analyzed in this work. It is shown that the FZP focal length depends almost linearly on the operating frequency. Focal depth and focal distortion are also considered, establishing a limit on the frequency span at which the operating frequency can be shifted. An underwater FZP ultrasound focusing system is demonstrated, and experimental results agree with the theoretical analysis and simulations.Spanish MINECO (TEC2015-70939-R) supported this work.Fuster Escuder, JM.; Candelas Valiente, P.; Castiñeira Ibáñez, S.; Pérez López, S.; Rubio Michavila, C. (2017). Analysis of Fresnel Zone Plates Focusing Dependence on Operating Frequency. Sensors. 17(12):2809-1-2809-10. https://doi.org/10.3390/s17122809S2809-12809-10171

Leveraging energy saving capabilities of current EEE interfaces via pre-coalescing

The low power idle mode implemented by Energy Efficient Ethernet (EEE) allows network interfaces to save up to 90% of their nominal energy consumption when idling. There is an ample body of research that recommends the use of frame coalescing algorithms—that enter the low power mode as soon as there is no more traffic waiting to be sent, and delay the exit from this mode until there is an acceptable amount of traffic queued—to minimize energy usage while maintaining an acceptable performance. However, EEE capable hardware from several manufactures delays the entrance to the low power mode for a considerable amount of time (hysteresis). In this paper we augment existing EEE energy models to account for the hysteresis delay and show that, using the configuration ranges provided by manufacturers, most existing EEE networking devices are unable to obtain significant energy savings. To improve their energy efficiency, we propose to implement frame coalescing directly at traffic sources, before reaching the network interface. We also derive the optimum coalescing parameters to obtain a given target energy consumption at the EEE device when its configuration parameters are known in advance.Agencia Estatal de Investigación | Ref. TEC2017-85587-

End-to-end active queue management with Named-Data Networking

The innovative information-based Named-Data Networking (NDN) architecture provides a good opportunity to rethink many of the design decisions that are taken for granted in the Internet today. For example, active queue management (AQM) tasks have been traditionally implemented in the routers to alleviate network congestion before their buffers fill up. However, AQM operations could be performed on an end-to-end basis by taking advantage of NDN features. In this paper, we provide an implementation of an AQM algorithm for the NDN architecture that we use to drive a classical AIMD-based congestion control protocol at the receivers. To accomplish this, we take advantage of the 64-bit Congestion Mark field present in the link layer of NDN packets to encode both rate and delay information about each transmission queue along a network path. In order to make the solution scalable, this information is delivered stochastically, guaranteeing that receivers get accurate and updated information about every pertinent queue. This information is enough to implement the well-known controlled delay (CoDel) AQM algorithm. Simulation results show that our client-located CoDel implementation is able to react to congestion when the bottleneck queuing delay surpasses the 5 ms target set by the usual in-network CoDel implementation and, at the same time, get a fair and efficient share of the available transmission capacityAgencia estatal de investigación | Ref. PID2020-113240RB-I00Universidade de Vigo/CISU