Seville: a successful experience of promotion of the mobility in bicycle in Europa's South

En apenas cuatro años la ciudad de Sevilla ha pasado de una participación marginal de la bicicleta en el conjunto de la movilidad urbana a cotas de participación en torno al 6% del reparto modal global de la ciudad. Éste ha sido el resultado de un proceso social y de unas políticas activas de promoción de la bicicleta que se analizan a lo largo de este artículo con el ánimo de identificar cuales han sido los factores determinantes de dicho éxito que podrían, en su caso, inspirar actuaciones similares en otras ciudades. Se analizan también las posibilidades de extensión de esta experiencia a otros ámbitos y en especial a la corona metropolitana de Sevilla, donde la participación de la bicicleta en el reparto modal es todavía muy escasa.Along no more than four years the city of Sevilla has evolved from a marginal participation of cycling in the urban mobility to participation rates around 6% of global modal sharing in the city. This has been the result of a social process and of some active policies aimed to the promotion of urban cycling, which are analyzed along this paper. Our main purpose is to identify the factors which have determined this success and that would, eventually, encourage similar actions in other cities. We also analyze the possibilities for extending this experience to other anvironments, specifically to the external conurbation of Sevilla, where the participation of cycling in the modal share is still marginal

The impact of Seville’s cycle path on the urban space: a preliminary analysis

El impacto de las infraestructuras de nueva creación en la ciudad consolidada es un elemento clave a la hora de evaluar su integración en la misma. En el caso de la red de vías ciclistas de Sevilla, este impacto ha sido considerable en muchos aspectos y ha sido analizado desde varios puntos de vista. No obstante, se echa de menos un análisis de su impacto directo sobre el espacio urbano, algo que resulta fundamental para contextualizar adecuadamente varios de los debates que están teniendo lugar en la ciudad en torno a dicha infraestructura. En este trabajo se desarrolla una metodología para el análisis de dicho impacto, a través de la evaluación cuantitativa de la ocupación neta de espacio urbano a consecuencia de las obras de reurbanización ligadas a la creación de la red básica de vías ciclistas de la ciudad. Del análisis se deduce que dicha ocupación ha sido un proceso complejo, que se ha traducido en una ocupación neta de calzada, seguida de superficie sin pavimentar y de zonas peatonales, por este orden, aunque mediante numerosos y complejos intercambios de usos en la superficie afectada. El análisis ha supuesto la elaboración de una base de datos cartográfica detallada de dichas ocupaciones, que esperamos sea de gran utilidad para ulteriores análisis y procesos de planificación. Asimismo, confiamos en que la metodología desarrollada pueda ser de utilidad para otros estudios similares.The impact of newly created infrastructures in dense cities is a key element for assessing their integration in urban contexts. In the case of the network of cycle paths of Seville, this impact has been important in many aspects, and has been analyzed from several points of view. Nevertheless, as far as we know, an analysis of its direct impact on the urban space is still lacking. This analysis is essential in order to properly contextualize some debates that are presently taking place in the city with regard to such infrastructure. The present work develops a methodology for the analysis of the impact of the implementation of new bike paths on urban spaces through the quantitative evaluation of the net occupation of such spaces, linked to the creation of these infrastructures. This methodology is applied to the analysis of the basic network of cycle paths of Seville. The analysis shows that this process resulted in a net occupation of carriageways, followed by unpaved surfaces and pedestrian areas. The process has been, however, quite complex, its net result being the resultant of many interchanges between these categories. The analysis has led to the elaboration of a detailed cartographic database of these occupations, which we hope will be of interest for further analysis and planning processes. We are also confident that the methodology developed in this paper may be useful in other similar contexts

Comments on "Internal impedance of conductors of rectangular cross section"

The alternate current (ac) internal impedance of rectangular cross-sectional conductors used as transmission lines and interconnects in microwave and digital printed circuits were analyzed. The difference between the real and imaginary parts of internal impedance to the existence of right-angle corners in the rectangular cross-sectional geometrics were studied. The corners are responsible for the nonconstant distribution of the currents along the periphery of the conductors. The consideration of incremental inductance was correlated to nonperfect nature of the conductors rather than internal inductance

Optimizing the magnetoinductive lens: Improvement, limits, and possible applications

In this contribution, the basic concepts underlying the physics of magnetoinductive MI lenses are developed and the main practical limitations to their performances are analyzed. Strategies to overcome such limitations are proposed. Possible applications of MI lenses in magnetic resonance imaging are discussed.Ministerio de Ciencia y Educación de España-TEC2004-04249-C02-02Junta de Andalucía-P06-TIC-0136

Accurate modeling of split ring metamaterial lenses for magnetic resonance imaging applications

The usefulness of thin split ring metamaterial slabs for imaging applications, including magnetic resonance imaging applications, has attracted some attention in the past years. However, the small number of unit cells across these thin slabs prevents the direct application of continuous medium models for its characterization. The main aim of this contribution is to provide a rigorous model for these structures, also clarifying the usefulness of continuous medium approach for their characterization. The proposed model is a generalization of the classical Lorentz procedure to two dimensions and is able to deal with electrically thin slabs made of small resonant closed current loops. The obtained results are validated by full-wave electromagnetic simulations and compared with the continuous model approximation of the slab.Ministerio de Educación y Ciencia de España-TEC2007-68013-C02-01/TCM y CSD2008-00066Junta de Andalucía-P06-TIC-0136

Quasi-TM MoL/MoM approach for computing the transmission-line parameters of lossy lines

This paper presents a quasi-TM approach for the fundamental mode of transmission lines with semiconductor substrates and nonperfect metallic conductors. The approach has allowed us to develop a transmission-line model by properly defining frequency-dependent parameters in terms of the quasi-static electric potential and the electric current density along the propagation direction in the line. The previous quasi-TM analysis avoids the involved numerical root finding process typical in full-wave analysis, and overcomes the limitations of the conventional quasi-TEM approach to account for the effects of the longitudinal currents present both in the lossy substrates and in the nonperfect conductors. The transmission-line parameters have been computed by a hybrid technique that combines the method of lines with the method of the moments (MoM). The total CPU effort has been considerably reduced thanks to the possibility of finding closed-form expressions for the reaction integrals appearing in the MoM. Comparisons with previous computed and measured results show the validity of the present modelMinisterio de Educación y Ciencia TEC2004-04249-C02-02, TEC2004-0321

On the resonances and polarizabilities of split ring resonators

In this paper, the behavior at resonance of split ring resonators SRRs and other related topologies, such as the nonbianisotropic SRR and the broadside-coupled SRR, are studied. It is shown that these structures exhibit a fundamental resonant mode the quasistatic resonance and other higher-order modes which are related to dynamic processes. The excitation of these modes by means of a properly polarized time varying magnetic and/or electric fields is discussed on the basis of resonator symmetries. To verify the electromagnetic properties of these resonators, simulations based on resonance excitation by nonuniform and uniform external fields have been performed. Inspection of the currents at resonances, inferred from particle symmetries and full-wave electromagnetic simulations, allows us to predict the first-order dipolar moments induced at the different resonators and to develop a classification of the resonances based on this concept. The experimental data, obtained in SRR-loaded waveguides, are in agreement with the theory and point out the rich phenomenology associated with these planar resonant structures.MEC (España)-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comunidad Europea (programa Eureka)-2895 TELEMACAgencia de Subvenciones de la República Checa-102/03/044

Near-field enhanced imaging by a magnetized ferrite slab

This letter demonstrates the near-field imaging enhancement at microwave frequencies of two-dimensional sources by a ferrite slab magnetized to saturation. It is shown that this effect is based on the nonreciprocal amplification of magnetostatic surface waves (MSSW) across the ferrite slab. The inclusion of losses in our analysis has also made it possible to prove this effect for realistic yttrium iron garnet ferrite samples. For ferrite slabs of width d, the resolution at the image plane (at a distance 2d from the source) is better than the resolution in air at a distance d of the source, which leads to an equivalent air length of the ferrite slab less than zero. Since the constitutive parameters of saturated ferrites depend on the external magnetizing field, the operation frequency of the proposed imaging devices can be tuned by varying this biasing field.Ministerio de Ciencia y Tecnología TEC2004-03214, TEC2004-04249-C02-0