297 research outputs found

    Systematic procedure for the efficient design of folded waveguide comb-line filters

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    [EN] A systematic procedure for the efficient design of folded waveguide comb-line filters is presented. The proposed strategy is based on dividing the design process in more simple stages, in order to reduce the number of variables to be optimized in each step of the design process. The electrical response of an equivalent circuit model of the waveguide component considered in each step is used as a target response. Moreover, a method for obtaining an initial value for some key dimensions of the filter is also addressed. Finally, an S-band 6-pole folded comb-line filter has been successfully designed following the proposed design strategy.San-Blas, AA.; Pérez-Guijarro, J.; Boria Esbert, VE.; Guglielmi, M. (2019). Systematic procedure for the efficient design of folded waveguide comb-line filters. IEEE. 1-4. https://doi.org/10.1109/NEMO.2019.8853707S1

    Approximating Weighted Duo-Preservation in Comparative Genomics

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    Motivated by comparative genomics, Chen et al. [9] introduced the Maximum Duo-preservation String Mapping (MDSM) problem in which we are given two strings s1s_1 and s2s_2 from the same alphabet and the goal is to find a mapping π\pi between them so as to maximize the number of duos preserved. A duo is any two consecutive characters in a string and it is preserved in the mapping if its two consecutive characters in s1s_1 are mapped to same two consecutive characters in s2s_2. The MDSM problem is known to be NP-hard and there are approximation algorithms for this problem [3, 5, 13], but all of them consider only the "unweighted" version of the problem in the sense that a duo from s1s_1 is preserved by mapping to any same duo in s2s_2 regardless of their positions in the respective strings. However, it is well-desired in comparative genomics to find mappings that consider preserving duos that are "closer" to each other under some distance measure [19]. In this paper, we introduce a generalized version of the problem, called the Maximum-Weight Duo-preservation String Mapping (MWDSM) problem that captures both duos-preservation and duos-distance measures in the sense that mapping a duo from s1s_1 to each preserved duo in s2s_2 has a weight, indicating the "closeness" of the two duos. The objective of the MWDSM problem is to find a mapping so as to maximize the total weight of preserved duos. In this paper, we give a polynomial-time 6-approximation algorithm for this problem.Comment: Appeared in proceedings of the 23rd International Computing and Combinatorics Conference (COCOON 2017

    Synthesis of slow-wave structures based on capacitive-loaded lines through aggressive space mapping (ASM)

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    This article is focused on the automated synthesis of slow-wave structures based on microstrip lines loaded with patch capacitors. Thanks to the presence of the shunt capacitors, the effective capacitance of the line is enhanced, and the phase velocity of the structure can be made significantly smaller than the one of the unloaded line. The target is to achieve the layout of the slow-wave structure able to provide the required slow-wave ratio, characteristic (Bloch) impedance and electrical length (i.e., the usual specifications in the design of slow-wave transmission lines). To this end, a two-step synthesis method, based on the aggressive space mapping (ASM) algorithm, is proposed for the first time. Through the first ASM algorithm, the circuit schematic providing the target specifications is determined. Then, the second ASM optimizer is used to generate the layout of the structure. To illustrate the potential of the proposed synthesis method, three application examples are successfully reported. The two-step ASM algorithm is able to provide the layout of the considered structures from the required specifications, without the need of an external aid in the process.This work has been supported by MINECO-Spain (projects TEC2010-17512 METATRANSFER, TEC2010-21520-C04-01, TEC2013-47037-C5-1-R, CONSOLIDER EMET CSD2008-00066, TEC2013-40600-R and TEC2013-49221-EXP), Generalitat de Catalunya (project 2014SGR-157), Institucio Catalana de Recerca i Estudis Avancats (who has awarded Ferran Martin) and FEDER Funds. Marco Orellana acknowledges the support of the Universidad de Costa Rica, MICITT and CONICIT to study at the Univesitat Autonoma de Barcelona.Orellana, M.; Selga, J.; Sans, M.; Rodriguez Perez, AM.; Boria Esbert, VE.; Martín Antolín, JF. (2015). Synthesis of slow-wave structures based on capacitive-loaded lines through aggressive space mapping (ASM). International Journal of RF and Microwave Computer-Aided Engineering. 25(7):629-638. https://doi.org/10.1002/mmce.20901S629638257F. Martín J. Bonache M. Durán-Sindreu J. Naqui F. Paredes G. Zamora 1 25Gorur, A. (1994). A novel coplanar slow-wave structure. IEEE Microwave and Guided Wave Letters, 4(3), 86-88. doi:10.1109/75.275589Sor, J., Qian, Y., & Itoh, T. (2001). Miniature low-loss CPW periodic structures for filter applications. IEEE Transactions on Microwave Theory and Techniques, 49(12), 2336-2341. doi:10.1109/22.971618Shau-Gang Mao, & Ming-Yi Chen. (2001). A novel periodic electromagnetic bandgap structure for finite-width conductor-backed coplanar waveguides. IEEE Microwave and Wireless Components Letters, 11(6), 261-263. doi:10.1109/7260.928932Martín, F., Falcone, F., Bonache, J., Lopetegi, T., Laso, M. A. G., & Sorolla, M. (2003). New CPW low-pass filter based on a slow wave structure. Microwave and Optical Technology Letters, 38(3), 190-193. doi:10.1002/mop.11011Garcia-Garcia, J., Bonache, J., & Martin, F. (2006). Application of Electromagnetic Bandgaps to the Design of Ultra-Wide Bandpass Filters With Good Out-of-Band Performance. IEEE Transactions on Microwave Theory and Techniques, 54(12), 4136-4140. doi:10.1109/tmtt.2006.886155Bandler, J. W., Biernacki, R. M., Shao Hua Chen, Grobelny, P. A., & Hemmers, R. H. (1994). Space mapping technique for electromagnetic optimization. IEEE Transactions on Microwave Theory and Techniques, 42(12), 2536-2544. doi:10.1109/22.339794Bandler, J. W., Biernacki, R. M., Shao Hua Chen, Hemmers, R. H., & Madsen, K. (1995). Electromagnetic optimization exploiting aggressive space mapping. IEEE Transactions on Microwave Theory and Techniques, 43(12), 2874-2882. doi:10.1109/22.475649Koziel, S., Cheng, Q., & Bandler, J. (2008). Space mapping. IEEE Microwave Magazine, 9(6), 105-122. doi:10.1109/mmm.2008.929554Koziel, S., & Bandler, J. W. (2007). Space-Mapping Optimization With Adaptive Surrogate Model. IEEE Transactions on Microwave Theory and Techniques, 55(3), 541-547. doi:10.1109/tmtt.2006.890524S. Koziel Q.S. Cheng J.W. Bandler 1995 1998Koziel, S., Bandler, J. W., & Cheng, Q. S. (2010). Robust Trust-Region Space-Mapping Algorithms for Microwave Design Optimization. IEEE Transactions on Microwave Theory and Techniques, 58(8), 2166-2174. doi:10.1109/tmtt.2010.2052666Q.S. Cheng J.W. Bandler N.K. Nikolova S. Koziel 1 4L.J. Rogla J.E. Rayas-Sanchez V.E. Boria J. Carbonell 111 114P.J. Bradley 1 4P.J. Bradley 1 17 2013J. Selga A. Rodríguez V.E. Boria F. MartínJ. Selga A. Rodríguez J. Naqui M. Durán-Sindreu V.E. Boria F. Martín 2013J. Selga M. Sans A. Rodríguez J. Bonache V. Boria F. Martín 1 4Sans, M., Selga, J., Rodriguez, A., Bonache, J., Boria, V. E., & Martin, F. (2014). Design of Planar Wideband Bandpass Filters From Specifications Using a Two-Step Aggressive Space Mapping (ASM) Optimization Algorithm. IEEE Transactions on Microwave Theory and Techniques, 62(12), 3341-3350. doi:10.1109/tmtt.2014.2365477Broyden, C. G. (1965). A class of methods for solving nonlinear simultaneous equations. Mathematics of Computation, 19(92), 577-577. doi:10.1090/s0025-5718-1965-0198670-6Marqus, R., Martn, F., & Sorolla, M. (2007). Metamaterials with Negative Parameters. doi:10.1002/978047019173

    Thru-reflect-line calibration for substrate integrated waveguide devices with tapered microstrip transitions

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    One of the main problems when exciting or measuring substrate integrated waveguide (SIW) devices lies in the need of a good interconnection with planar structures. In this reported work, the negative effects produced by the connectors and the tapered microstrip-to-SIW transitions are de-embedded from the measurements of the SIW structure by a thru-reflect-line calibration with an adequate and cheap SIW calibration kit.Díaz Caballero, E.; Belenguer Martínez, Á.; Esteban González, H.; Boria Esbert, VE. (2013). Thru-reflect-line calibration for substrate integrated waveguide devices with tapered microstrip transitions. Electronics Letters. 49(2):132-133. doi:10.1049/el.2012.3027S132133492Deslandes, D., & Wu, K. (2001). Integrated microstrip and rectangular waveguide in planar form. IEEE Microwave and Wireless Components Letters, 11(2), 68-70. doi:10.1109/7260.914305Henry, M., Free, C. E., Izqueirdo, B. S., Batchelor, J., & Young, P. (2009). Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis. IEEE Transactions on Advanced Packaging, 32(1), 93-100. doi:10.1109/tadvp.2008.2011284Chen, X.-P., Wu, K., & Li, Z.-L. (2007). Dual-Band and Triple-Band Substrate Integrated Waveguide Filters With Chebyshev and Quasi-Elliptic Responses. IEEE Transactions on Microwave Theory and Techniques, 55(12), 2569-2578. doi:10.1109/tmtt.2007.909603Deslandes, D., & Ke Wu. (2005). Analysis and design of current probe transition from grounded coplanar to substrate integrated rectangular waveguides. IEEE Transactions on Microwave Theory and Techniques, 53(8), 2487-2494. doi:10.1109/tmtt.2005.852778Engen, G. F., & Hoer, C. A. (1979). Thru-Reflect-Line: An Improved Technique for Calibrating the Dual Six-Port Automatic Network Analyzer. IEEE Transactions on Microwave Theory and Techniques, 27(12), 987-993. doi:10.1109/tmtt.1979.1129778Chih-Jung Chen, & Tah-Hsiung Chu. (2009). Measurement of Noncoaxial Multiport Devices Up to the Intrinsic Ports. IEEE Transactions on Microwave Theory and Techniques, 57(5), 1230-1236. doi:10.1109/tmtt.2009.201735

    Automated Design of Common-Mode Suppressed Balanced Wideband Bandpass Filters by Means of Aggressive Space Mapping

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    The automated and unattended design of balanced microstrip wideband bandpass filters by means of aggressive space mapping (ASM) optimization is reported in this paper. The proposed filters are based on multisection mirrored stepped impedance resonators (SIRs) coupled through quarter-wavelength transmission lines, acting as admittance inverters.This work was supported by MINECO-Spain (projects TEC2013-47037-C5-1-R, TEC2013-40600-R, TEC2013-49221-EXP), Generalitat de Catalunya (project 2014SGR-157), Institucio Catalana de Recerca i Estudis Avancats (who awarded Ferran Martin), and by FEDER funds.Sans, M.; Selga, J.; Velez, P.; Rodriguez Perez, AM.; Bonache Albacete, J.; Boria Esbert, VE.; Martin, F. (2015). Automated Design of Common-Mode Suppressed Balanced Wideband Bandpass Filters by Means of Aggressive Space Mapping. IEEE Transactions on Microwave Theory and Techniques. 63(12):3896-3908. https://doi.org/10.1109/TMTT.2015.2495180S38963908631

    Accurate consideration of metal losses at waveguide junctions using admittance and impedance integral equation formulations

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    [EN] At higher frequencies, metal loss effects in passive waveguide components become more pronounced and hazardous. In this paper, we propose two integral equation techniques, based on the generalized admittance and impedance matrices, for the accurate consideration of losses in the metal walls of waveguide junctions. Both techniques have been evaluated in terms of accuracy and numerical efficiency, and conclusions are drawn regarding the best properties of the admittance parameter formulation. Finally, combining such technique with a classical perturbative method for considering propagation losses, we have successfully predicted all loss effects in two real waveguide filters used for commercial applications.This work has been supported by research projects TIC2000-0591-C03-01 and TIC2000-0591-C03-03 and special action ESP2001-4547-PE.Taroncher Calduch, M.; Hueso, J.; Cogollos, S.; Gimeno. B.; Boria Esbert, VE.; Vidal Pantaleoni, A.; Esteban González, H.... (2005). Accurate consideration of metal losses at waveguide junctions using admittance and impedance integral equation formulations. Radio Science. 40(6):1-12. doi:10.1029/2004RS003225S11240

    Multipactor radiation analysis within a waveguide region based on a frequency-domain representation of the dynamics of charged particles

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    [EN] A technique for the accurate computation of the electromagnetic fields radiated by a charged particle moving within a parallel-plate waveguide is presented. Based on a transformation of the time-varying current density of the particle into a time-harmonic current density, this technique allows the evaluation of the radiated electromagnetic fields both in the frequency and time domains, as well as in the near- and far-field regions. For this purpose, several accelerated versions of the parallel-plate Green's function in the frequency domain have been considered. The theory has been successfully applied to the multipactor discharge occurring within a two metal-plates region. The proposed formulation has been tested with a particle-in-cell code based on the finite-difference time-domain method, obtaining good agreement.The authors would like to thank ESA/ESTEC for having funded this research activity through the Contract "RF Breakdown in Multicarrier Systems" (Contract No. 19918/06/NL/GLC).Gimeno, B.; Sorolla, E.; Anza, S.; Vicente, C.; Gil, J.; Pérez, AM.; Boria Esbert, VE.... (2009). Multipactor radiation analysis within a waveguide region based on a frequency-domain representation of the dynamics of charged particles. Physical review. E, Statistical, nonlinear, and soft matter physics. 79(4):1-9. https://doi.org/10.1103/PhysRevE.79.046604S19794Figueroa, H., Gai, W., Konecny, R., Norem, J., Ruggiero, A., Schoessow, P., & Simpson, J. (1988). Direct Measurement of Beam-Induced Fields in Accelerating Structures. Physical Review Letters, 60(21), 2144-2147. doi:10.1103/physrevlett.60.2144Ng, K.-Y. (1990). Wake fields in a dielectric-lined waveguide. Physical Review D, 42(5), 1819-1828. doi:10.1103/physrevd.42.1819Rosing, M., & Gai, W. (1990). Longitudinal- and transverse-wake-field effects in dielectric structures. Physical Review D, 42(5), 1829-1834. doi:10.1103/physrevd.42.1829Gai, W., Kanareykin, A. D., Kustov, A. L., & Simpson, J. (1997). Numerical simulations of intense charged-particle beam propagation in a dielectric wake-field accelerator. Physical Review E, 55(3), 3481-3488. doi:10.1103/physreve.55.3481Burov, A., & Danilov, V. (1999). Suppression of Transverse Bunch Instabilities by Asymmetries in the Chamber Geometry. Physical Review Letters, 82(11), 2286-2289. doi:10.1103/physrevlett.82.2286Xiao, L., Gai, W., & Sun, X. (2001). Field analysis of a dielectric-loaded rectangular waveguide accelerating structure. Physical Review E, 65(1). doi:10.1103/physreve.65.016505Jing, C., Liu, W., Xiao, L., Gai, W., Schoessow, P., & Wong, T. (2003). Dipole-mode wakefields in dielectric-loaded rectangular waveguide accelerating structures. Physical Review E, 68(1). doi:10.1103/physreve.68.016502Stupakov, G., Bane, K. L. F., & Zagorodnov, I. (2007). Optical approximation in the theory of geometric impedance. Physical Review Special Topics - Accelerators and Beams, 10(5). doi:10.1103/physrevstab.10.054401Hatch, A. J., & Williams, H. B. (1954). The Secondary Electron Resonance Mechanism of Low‐Pressure High‐Frequency Gas Breakdown. Journal of Applied Physics, 25(4), 417-423. doi:10.1063/1.1721656Hatch, A. J., & Williams, H. B. (1958). Multipacting Modes of High-Frequency Gaseous Breakdown. Physical Review, 112(3), 681-685. doi:10.1103/physrev.112.681Vaughan, J. R. M. (1988). Multipactor. IEEE Transactions on Electron Devices, 35(7), 1172-1180. doi:10.1109/16.3387Gilardini, A. L. (1995). Multipacting discharges: Constant‐ktheory and simulation results. Journal of Applied Physics, 78(2), 783-795. doi:10.1063/1.360336Riyopoulos, S. (1997). Multipactor saturation due to space-charge-induced debunching. Physics of Plasmas, 4(5), 1448-1462. doi:10.1063/1.872319Kryazhev, A., Buyanova, M., Semenov, V., Anderson, D., Lisak, M., Puech, J., … Sombrin, J. (2002). Hybrid resonant modes of two-sided multipactor and transition to the polyphase regime. Physics of Plasmas, 9(11), 4736-4743. doi:10.1063/1.1514969Udiljak, R., Anderson, D., Ingvarson, P., Jordan, U., Jostell, U., Lapierre, L., … Sombrin, J. (2003). New method for detection of multipaction. IEEE Transactions on Plasma Science, 31(3), 396-404. doi:10.1109/tps.2003.811646De Lara, J., Perez, F., Alfonseca, M., Galan, L., Montero, I., Roman, E., & Garcia-Baquero, D. R. (2006). Multipactor prediction for on-board spacecraft RF equipment with the MEST software tool. IEEE Transactions on Plasma Science, 34(2), 476-484. doi:10.1109/tps.2006.872450Torregrosa, G., Coves, A., Vicente, C. P., Perez, A. M., Gimeno, B., & Boria, V. E. (2006). Time evolution of an electron discharge in a parallel-plate dielectric-loaded waveguide. IEEE Electron Device Letters, 27(7), 619-621. doi:10.1109/led.2006.877284Udiljak, R., Anderson, D., Lisak, M., Semenov, V. E., & Puech, J. (2007). Multipactor in a coaxial transmission line. I. Analytical study. Physics of Plasmas, 14(3), 033508. doi:10.1063/1.2710464Semenov, V. E., Zharova, N., Udiljak, R., Anderson, D., Lisak, M., & Puech, J. (2007). Multipactor in a coaxial transmission line. II. Particle-in-cell simulations. Physics of Plasmas, 14(3), 033509. doi:10.1063/1.2710466Anza, S., Vicente, C., Gimeno, B., Boria, V. E., & Armendáriz, J. (2007). Long-term multipactor discharge in multicarrier systems. Physics of Plasmas, 14(8), 082112. doi:10.1063/1.2768019Udiljak, R., Anderson, D., Lisak, M., Puech, J., & Semenov, V. E. (2007). Multipactor in a Waveguide Iris. IEEE Transactions on Plasma Science, 35(2), 388-395. doi:10.1109/tps.2007.892737Burton, R. J., de Jong, M. S., & Funk, L. W. (1991). Vacuum and multipactor performance of the hadron electron ring accelerator 52 MHz cavities. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 9(3), 2081-2084. doi:10.1116/1.577417Yamaguchi, S., Saito, Y., Anami, S., & Michizono, S. (1992). Trajectory simulation of multipactoring electrons in an S-band pillbox RF window. IEEE Transactions on Nuclear Science, 39(2), 278-282. doi:10.1109/23.277497Kishek, R., & Lau, Y. Y. (1995). Interaction of Multipactor Discharge and rf Circuit. Physical Review Letters, 75(6), 1218-1221. doi:10.1103/physrevlett.75.1218Lay-Kee Ang, Lau, Y. Y., Kishek, R. A., & Gilgenbach, R. M. (1998). Power deposited on a dielectric by multipactor. IEEE Transactions on Plasma Science, 26(3), 290-295. doi:10.1109/27.700756Kishek, R. A., Lau, Y. Y., Ang, L. K., Valfells, A., & Gilgenbach, R. M. (1998). Multipactor discharge on metals and dielectrics: Historical review and recent theories. 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    Empresas del IBEX-35: Consejeras y directivas de alta dirección

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    La presencia de mujeres en la empresa es cada vez más común y necesaria para lograr una mayor equidad de género en el ámbito laboral. A lo largo de la historia, las mujeres se han enfrentado a barreras y discriminación en el mundo laboral, pero hoy en día, la situación está cambiando gracias a las luchas feministas, a una mayor conciencia social sobre la importancia de la igualdad de oportunidades y al apoyo legislativo. Las mujeres aportan una visión y perspectiva diferente en la organización, lo que puede repercutir en una mayor creatividad, innovación y, por ende, rentabilidad. Sin embargo, todavía existen obstáculos y desafíos que enfrentan las mujeres en el ámbito laboral, como la brecha salarial de género, la falta de representación en cargos directivos y de liderazgo, y la discriminación basada en estereotipos de género. Además, su presencia en cargos directivos y de liderazgo puede fomentar la diversidad y la inclusión en la empresa, por ello es importante conocer la incidencia de la mujer en las empresas que cotizan en el Índice bursátil IBEX-35. Para ello, se utiliza el análisis de datos secundarios de la Comisión Nacional del Mercado de Valores (CNMV) y se aplica el algoritmo de Pichat a partir de la distancia de Hamming para conocer esas actuaciones. De esta forma, se pretende determinar si se cumple con las recomendaciones de la normativa actual en este campo. Es importante seguir trabajando en la eliminación de estas barreras para lograr una mayor igualdad de oportunidades en el mundo laboral y promover el desarrollo profesional y personal de todas las personas, independientemente de su género
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