Three-dimensional flow instability in a lid-driven isosceles triangular cavity

Linear three-dimensional modal instability of steady laminar two-dimensional states developing in a lid-driven cavity of isosceles triangular cross-section is investigated theoretically and experimentally for the case in which the equal sides form a rectangular corner. An asymmetric steady two-dimensional motion is driven by the steady motion of one of the equal sides. If the side moves away from the rectangular corner, a stationary three-dimensional instability is found. If the motion is directed towards the corner, the instability is oscillatory. The respective critical Reynolds numbers are identified both theoretically and experimentally. The neutral curves pertinent to the two configurations and the properties of the respective leading eigenmodes are documented and analogies to instabilities in rectangular lid-driven cavities are discussed.

Multibeam Network Design and Measurement for Triangular Array of Three Radiating Elements

Nowadays, more a more base stations are equipped with active conformal antennas. These antenna designs combine phase shift systems with multibeam networks providing multi-beam ability and interference rejection, which optimize multiple channel systems. GEODA is a conformal adaptive antenna system designed for satellite communications. Operating at 1.7 GHz with circular polarization, it is possible to track and communicate with several satellites at once thanks to its adaptive beam. The antenna is based on a set of similar triangular arrays that are divided in subarrays of three elements called `cells'. Transmission/Receiver (T/R) modules manage beam steering by shifting the phases. A more accurate steering of the antenna GEODA could be achieved by using a multibeam network. Several multibeam network designs based on Butler network will be presented

3x3 Multibeam Network for a Triangular Array of Three Radiating Elements

A multibeam antenna study based on Butler network will be undertaken in this document. These antenna designs combines phase shift systems with multibeam networks to optimize multiple channel systems. The system will work at 1.7 GHz with circular polarization. Specifically, result simulations and measurements of 3 element triangular subarray will be shown. A 45 element triangular array will be formed by the subarrays. Using triangular subarrays, side lobes and crossing points are reduced.

6x3 Microstrip Beam Forming Network for Multibeam Triangular Array

A six inputs and three outputs structure which can be used to obtain six simultaneous beams with a triangular array of 3 elements is presented. The beam forming network is obtained combining balanced and unbalanced hybrid couplers and allows to obtain six main beams with sixty degrees of separation in azimuth direction. Simulations and measurements showing the performance of the array and other detailed results are presented

Territory and the governmentalisation of social reproduction: parliamentary enclosure and spatial rationalities in the transition from feudalism to capitalism

Recent applications of Foucauldian categories in geography, spatial history and the history of town planning have opened up interesting new perspectives, with respect to both the evolution of spatial knowledge and the genealogy of territorial techniques and their relation to larger socio-political projects, that would be enriched if combined with other discursive traditions. This article proposes to conceptualise English parliamentary enclosureea favourite episode for Marxist historiography, frequently read in a strictly materialist fashioneas a precedent of a new form of sociospatial governmentality, a political technology that inaugurates a strategic manipulation of territory for social change on the threshold between feudal and capitalist spatial rationalities. I analyse the sociospatial dimensions of parliamentary enclosure’s technical and legal innovations and compare them to the forms of communal self-regulation of land use customs and everyday regionalisations that preceded it. Through a systematic, replicable mechanism of reterritorialisation, enclosure acts normalised spatial regulations, blurred regional differences in the social organisation of agriculture and erased the modes of autonomous social reproduction linked to common land. Their exercise of dispossession of material resources, social capital and community representations is interpreted therefore as an inaugural logic that would pervade the emergent spatial rationality later known as planning.

Non-degenerate developable triangular Bézier patches

In this talk we show a construction for characterising developable surfaces in the form of Bézier triangular patches. It is shown that constructions used for rectangular patches are not useful, since they provide degenerate triangular patches. Explicit constructions of non-degenerate developable triangular patches are provided.

Hysteresis phenomena in transverse galloping of triangular cross-section bodies

Transverse galloping is a type of aeroelastic instability characterised by large amplitude, low frequency oscillation of a structure in the direction normal to the mean wind direction. It normally appears in bodies with small stiffness and structural damping, provided the incident flow velocity is high enough. In the simplest approach transverse galloping can be considered as a one-degree-of-freedom oscillator subjected to aerodynamic forces, which in turn can be described by using a quasi-steady description. In this frame it has been demonstrated that hysteresis phenomena in transverse galloping is related to the existence of inflection points in the curve giving the dependence with the angle of attack of the aerodynamic coefficient normal to the incident flow. Aiming at experimentally checking such a relationship between these inflection points and hysteresis, wind tunnel experiments have been conducted. Experiments have been restricted to isosceles triangular cross-section bodies, whose galloping behaviour is well documented. Experimental results show that, according to theoretical predictions, hysteresis takes place at the angles of attack where there are inflection points in the lift coefficient curve, provided that the body is prone to gallop at these angles of attack.

On the design and measurement of a novel non-orthogonal multi-beam network for triangular arrays of three radiating elements

An innovative dissipative multi-beam network for triangular arrays of three radiating elements is proposed. This novel network provides three orthogonal beams in θ0 elevation angle and a fourth one in the broadside steering direction. The network is composed of 90º hybrid couplers and fixed phase shifters. In this paper, a relation between network components, radiating element distance and beam steering directions will be shown. Application of the proposed dissipative network to the triangular cells of three radiating elements that integrate the intelligent antenna GEODA will be exhibited. This system works at 1.7 GHz, it has a 60º single radiating element beamwidth and a distance between array elements of 0.57 λ. Both beam patterns, theoretical and simulated, obtained with the network will be depicted. Moreover, the whole system, dissipative network built with GEODA cell array, has been measured in the anechoic chamber of the Radiation Group of Technical University of Madrid, demonstrating expected performance.

Study of a new 4×3 beam forming network for triangular arrays of three radiating elements

An innovative dissipative multi-beam network for triangular arrays of three radiating elements is proposed. This novel network provides three orthogonal beams in θ0 elevation angle and a fourth one in the broadside steering direction. The network is composed of 90º hybrid couplers and fixed phase shifters. In this paper, a relation between network components, radiating element distance and beam steering directions will be shown. Application of the proposed dissipative network to the triangular cells of three radiating elements that integrate the intelligent antenna GEODA will be exhibited. This system works at 1.7 GHz, it has a 60º single radiating element beamwidth and a distance between array elements of 0.57λ. Both beam patterns, theoretical and simulated, obtained with the network will be depicted. Moreover, the whole system, dissipative network built with GEODA cell array, has been measured in the anechoic chamber of the Radiation Group of Technical University of Madrid, demonstrating expected performance

Territory and the governmentalisation of social reproduction: parliamentary enclosure and spatial rationalities in the transition from feudalism to capitalism

Recent applications of Foucauldian categories in geography, spatial history and the history of town planning have opened up interesting new perspectives, with respect to both the evolution of spatial knowledge and the genealogy of territorial techniques and their relation to larger socio-political projects, that would be enriched if combined with other discursive traditions. This article proposes to conceptualise English parliamentary enclosureea favourite episode for Marxist historiography, frequently read in a strictly materialist fashioneas a precedent of a new form of sociospatial governmentality, a political technology that inaugurates a strategic manipulation of territory for social change on the threshold between feudal and capitalist spatial rationalities. I analyse the sociospatial dimensions of parliamentary enclosure’s technical and legal innovations and compare them to the forms of communal self-regulation of land use customs and everyday regionalisations that preceded it. Through a systematic, replicable mechanism of reterritorialisation, enclosure acts normalised spatial regulations, blurred regional differences in the social organisation of agriculture and erased the modes of autonomous social reproduction linked to common land. Their exercise of dispossession of material resources, social capital and community representations is interpreted therefore as an inaugural logic that would pervade the emergent spatial rationality later known as planning.

Fisuración y deformaciones en tabiquerías

A diferencia de otros parámetros, el efecto de la existencia de huecos en la aparición y desarrollo de los procesos de fisuración en los paños de fábrica no ha sido considerado por las distintas normativas existentes en la actualidad. En nuestros días se emplea una variada gama de tipologías de elementos de cerramiento para realizar las particiones en las obras de edificación, cada una de ellas con características mecánicas diferentes y distinta metodología de ejecución, siendo de aplicación la misma normativa relativa al cálculo y control de las deformaciones. Tal y como expresamos en el Capitulo 1, en el que se analiza el Estado del Conocimiento, los códigos actuales determinan de forma analítica la flecha probable que se alcanza en los elementos portantes estructurales bajo diferentes condiciones de servicio. Las distintas propuestas que existen respecto para la limitación de la flecha activa, una vez realizado el cálculo de las deformaciones, bien por el método de Branson ó mediante los métodos de integración de curvaturas, no contemplan como parámetro a considerar en la limitación de la flecha activa la existencia y tipología de huecos en un paño de fábrica soportado por la estructura. Sin embargo se intuye y podríamos afirmar que una discontinuidad en cualquier elemento sometido a esfuerzos tiene influencia en el estado tensional del mismo. Si consideramos que, de forma general, los procesos de fisuración se producen al superarse la resistencia a tracción de material constitutivo de la fábrica soportada, es claro que la variación tensional inducida por la existencia de huecos ha de tener cierta influencia en la aparición y desarrollo de los procesos de fisuración en los elementos de partición o de cerramiento de las obras de edificación. En los Capítulos 2 y 3 tras justificar la necesidad de realizar una investigación encaminada a confirmar la relación entre la existencia de huecos en un paño de fábrica y el desarrollo de procesos de fisuración en el mismo, se establece este aspecto como principal Objetivo y se expone la Metodología para su análisis. Hemos definido y justificado en el Capítulo 4 el modelo de cálculo que hemos utilizado para determinar las deformaciones y los procesos de fisuración que se producen en los casos a analizar, en los que se han considerado como variables: los valores de la luz del modelo, el estado de fisuración de los elementos portantes, los efectos de la fluencia y el porcentaje de transmisión de cargas desde el forjado superior al paño de fábrica en estudio. Además se adoptan dos valores de la resistencia a tracción de las fábricas, 0.75MPa y 1.00MPa. La capacidad de representar la fisuración, así como la robustez y fiabilidad ha condicionado y justificado la selección del programa de elementos finitos que se ha utilizado para realizar los cálculos. Aprovechando la posibilidad de reproducir de forma ajustada las características introducidas para cada parámetro, hemos planteado y realizado un análisis paramétricos que considera 360 cálculos iterativos, de cuya exposición es objeto el Capítulo 5, para obtener una serie representativa de resultados sobre los que se realizará el análisis posterior. En el Capítulo 6, de análisis de los resultados, hemos estudiado los valores de deformaciones y estados de fisuración obtenidos para los casos analizados. Hemos determinado la influencia que tiene la presencia de huecos en la aparición de los procesos de fisuración y en las deformaciones que se producen en las diferentes configuraciones estructurales. Las conclusiones que hemos obtenido tras analizar los resultados, incluidas en el Capítulo 7, no dejan lugar a dudas: la presencia, la posición y la tipología de los huecos en los elementos de fábricas soportadas sobre estructuras deformables son factores determinantes respecto de la fisuración y pueden tener influencia en las deformaciones que constituyen la flecha activa del elemento, lo que obliga a plantear una serie de recomendaciones frente al proyecto y frente a la reglamentación técnica. La investigación desarrollada para esta Tesis Doctoral y la metodología aplicada para su desarrollo abre nuevas líneas de estudio, que se esbozan en el Capítulo 8, para el análisis de otros aspectos que no han sido cubiertos por esta investigación a fin de mejorar las limitaciones que deberían establecerse para los Estados Límite de Servicio de Deformaciones correspondientes a las estructuras de edificación. SUMMARY. Unlike other parameters, the effect of the existence of voids in the arising and development of cracking processes in the masonry walls has not been considered by current Codes. Nowadays, a huge variety of enclosure elements types is used to execute partitions in buildings, each one with different mechanical characteristics and different execution methodology, being applied the same rules concerning deflection calculation and control. As indicated in Chapter 1, which analyzes the State of Art, current codes analytically determine the deflection likely to be achieved in structural supporting elements under different service conditions. The different proposals that exist related to live deflection limitation, once performed deformations calculation, either by Branson´s method or considering curvatures integration methods, do not consider in deflection limitation the existence and typology of voids in a masonry wall structured supported. But is sensed and it can be affirmed that a discontinuity in any element under stress influences the stress state of it. If we consider that, in general, cracking processes occur when masonry material tensile strength is exceeded, it is clear that tension variation induced by the existence of voids must have some influence on the emergence and development of cracking processes in enclosure elements of building works. In Chapters 2 and 3, after justifying the need for an investigation to confirm the relationship between the existence of voids in a masonry wall and the development of cracking process in it, is set as the main objective and it is shown the analysis Methodology. We have defined and justified in Chapter 4 the calculation model used to determine the deformation and cracking processes that occur in the cases analyzed, in which were considered as variables: model span values, bearing elements cracking state, creep effects and load transmission percentage from the upper floor to the studied masonry wall. In addition, two masonry tensile strength values 0.75MPa and 1.00MPa have been considered. The cracking consideration ability, robustness and reliability has determined and justified the selection of the finite element program that was used for the calculations. Taking advantage of the ability of accurately consider the characteristics introduced for each parameter, we have performed a parametric analyses that considers 360 iterative calculations, whose results are included in Chapter 5, in order to obtain a representative results set that will be analyzed later. In Chapter 6, results analysis, we studied the obtained values of deformation and cracking configurations for the cases analyzed. We determined the influence of the voids presence in the occurrence of cracking processes and deformations in different structural configurations. The conclusions we have obtained after analyzing the results, included in Chapter 7, leave no doubt: the presence, position and type of holes in masonry elements supported on deformable structures are determinative of cracking and can influence deformations which are the element live deflection, making necessary to raise a number of recommendations related to project and technical regulation. The research undertaken for this Doctoral Thesis and the applied methodology for its development opens up new lines of study, outlined in Chapter 8, for the analysis of other aspects that are not covered by this research, in order to improve the limitations that should be established for Deflections Serviceability Limit States related to building structures.

On the Extension of the Analytic Nodal Diffusion Solver ANDES to Sodium Fast Reactors

Within the framework of the Collaborative Project for a European Sodium Fast Reactor, the reactor physics group at UPM is working on the extension of its in-house multi-scale advanced deterministic code COBAYA3 to Sodium Fast Reactors (SFR). COBAYA3 is a 3D multigroup neutron kinetics diffusion code that can be used either as a pin-by-pin code or as a stand-alone nodal code by using the analytic nodal diffusion solver ANDES. It is coupled with thermalhydraulics codes such as COBRA-TF and FLICA, allowing transient analysis of LWR at both fine-mesh and coarse-mesh scales. In order to enable also 3D pin-by-pin and nodal coupled NK-TH simulations of SFR, different developments are in progress. This paper presents the first steps towards the application of COBAYA3 to this type of reactors. ANDES solver, already extended to triangular-Z geometry, has been applied to fast reactor steady-state calculations. The required cross section libraries were generated with ERANOS code for several configurations. The limitations encountered in the application of the Analytic Coarse Mesh Finite Difference (ACMFD) method –implemented inside ANDES– to fast reactors are presented and the sensitivity of the method when using a high number of energy groups is studied. ANDES performance is assessed by comparison with the results provided by ERANOS, using a mini-core model in 33 energy groups. Furthermore, a benchmark from the NEA for a small 3D FBR in hexagonal-Z geometry and 4 energy groups is also employed to verify the behavior of the code with few energy groups.

GEODA-GRUA: Adaptive Multibeam Conformal Antenna for Satellites Communications

The GEODA-GRUA is one conformal adaptive antenna array designed for satellite communications. Operating at 1.7 GHz with circular polarization, it is possible to track and communicate with several satellites at once being able to receive signals in full azimuth and within the range of 5° to broadside elevation thanks to its adaptive beam. The complex structure of the antenna array has 2700 radiating elements based on a set of 60 similar triangular arrays that are divided in 15 subarrays of 3 radiating elements. A control module governs each transmission/receiver (T/R) module associated to each cell in order to manage beam steering by shifting phases.

De la ciudad en vibración al ser resonante: Una investigación a propósito de los conciertos de campanas de Llorenç Barber

Este trabajo tiene la vocación de dibujar el mapa de los dominios de oportunidad que hay a disposición de un arquitecto, al imaginar el aspecto sonoro de la ciudad en relación con la campana. Muchas de las dimensiones señaladas, tanto conocidas como desconocidas, son sencillamente despertadas al estudio de lo que un diseñador del espacio sonoro, como Llorenç Barber, viene a decirnos, desde una disciplina aparentemente contactada, pero muchas veces paralela a la arquitectónica. Tomando los conciertos de campanas celebrados hasta la fecha como puestas en práctica real de la condición instrumental de más de doscientas ciudades de todo el mundo, el estudio analiza los hallazgos, éxitos y fracasos, obtenidos a lo largo de estos últimos veinticinco años de experiencia, como resultados explícitos de un trabajo sonoro en la ciudad, probado, contrastado y afinado, del que extraer indicaciones concretas susceptibles de ser aplicadas en el diseño del espacio urbano. Mediante un análisis triangular de vértices definidos: emisor-campana, medio-ciudad, receptor-ciudadano; la investigación aborda los aspectos relativos a la producción y recepción del fenómeno sonoro generado por la campana en la ciudad. En relación con la producción, una parte del trabajo se dedica al estudio de los efectos acústicos observados, ordenado por escalas graduales en las que se produce una distribución del sonido susceptible de diseño: el vaso de la campana, la sala de campanas, el campanario, el cuerpo del edificio, la ciudad y el territorio. A modo de cajas de resonancia y leídas como muñecas rusas, unas dentro de otras, los espacios identificados muestran cualidades sonoras específicas, definidas tanto por sus condiciones geométricas, formales, constructivas o de uso; como por las correspondientes a las subsiguientes cajas que alojan. A fin de esclarecer la influencia de tales cuestiones en el aspecto sonoro de la ciudad, se propone un modelo ordenado de conexión y desconexión de escalas, utilizando una paramétrica puramente técnica creada ex profeso, junto con variables metodológicas más tradicionales. Al mismo tiempo, y tratando de esclarecer cómo, al ser puesta en vibración, la ciudad es aprehendida, disfrutada y rememorada por el ciudadano-oyente, otra parte del trabajo se dedica al estudio de los aspectos relativos a su recepción aural en deambulación compartida. En este caso la investigación se propone reclamar otras dimensiones más subversivas que, si bien escapan a los modos habituales de trabajar del arquitecto, se revelan intensamente en la experiencia plurifocal, multiplicando los efectos a considerar: efectos funcionales y significativos, de reconocimiento, integración y pertenencia a un cuerpo territorial y social de coordenadas históricas y geográficas de nuevo significadas; efectos perceptuales de inmersión, ubicuidad, temporalidad o inestabilidad; efectos estéticos, de rememoración, interpretación simbólica y recreación poética; e incluso efectos políticos, descubriendo un espacio urbano en continua regeneración, lugar para la exposición en su doble acepción, para la exhibición y el peligro, o como contenedor situacional del más profundo sentido ciudadano. Para afinar la relevancia de lo obtenido en cada una de las dimensiones señaladas, el trabajo se articula en tres aproximaciones graduales: el corpus general de los conciertos celebrados hasta la fecha; los conciertos celebrados en España; los tres conciertos para Madrid: Magna Mater (1991), Festi Clamores (2000) y Aurea Catena (2007). Si bien el modelo propuesto nace a la luz de los conciertos de campanas de Llorenç Barber, a escala de una ciudad entera y con una intención compositiva individual, se entiende que sería útil para el uso ordenado de cualquier profesional interesado en el aspecto sonoro de la ciudad, faceta escasamente atendida, dicho sea de paso, desde la disciplina arquitectónica. ABSTRACT This work has the vocation of drawing out the numerous opportunities an architect has at his disposal, upon imagining the sonorous aspect of the city in relation to the bell. Many of the dimensions indicated, both known and unknown, are just awakened to the study of what a sound space designer, as Llorenç Barber, comes to tell us, from a discipline apparently contacted, but often parallel to the architecture. Taking the bell concerts held so far as actual implementation of the instrumental condition of over two hundred cities around the world, the study analyzes the findings, successes and failures, obtained over the last twenty years of experience, as explicit results of a sound work in the city, tested, verified and refined, from which to extract specific indications that can be applied in the design of urban space. By triangular analyzing of defined vertices: sender-bell, half-city, receptor-citizen; the research addresses issues relating to the production and reception of sound phenomenon generated by the bell in the city. In relation to production, part of the work is devoted to the study of observed acoustic effects, ordered gradual scale which produces a distribution of sound capable of design: the glass of the bell, the bell room, the bell tower and the body of the building, the city and territory. By way of sounding boards and read as if they were Russian dolls, one inside the other, the show spaces identified specific sound qualities, defined both for their geometric, formal, constructive use, such as those for hosting the subsequent boxes. In order to clarify the influence of such issues in the sound aspect of the city, we propose an ordered pattern of connection and disconnection of scales, using a purely parametric technique created on purpose, along with more traditional methodological variables. At the same time, and trying to clarify how, when set in vibration, the city is apprehended, enjoyed and remembered for the citizen-listener, another part of the work is devoted to the study of aspects of aural reception in shared ambulation. In this case the research aims to claim more subversive than other dimensions, but beyond the usual ways in which an architect works, the experience reveals intensely plurifocal multiplying effects to consider: functional effects and significant recognition and integration belonging to a body of territorial and social historical and geographical coordinates of new meaning and perceptual effects of immersion, ubiquity, timeliness or instability; aesthetic effects of recall, interpretation and recreation of symbolic poetic; and even political effects, revealing a continuous urban space regeneration site for the exhibition in its double meaning, for display and danger, or as a citizen sense container. To sharpen the relevance of what was obtained in each of the dimensions mentioned, the work is divided into three incremental approaches: the general corpus of the concerts held so far, the concerts in Spain, the three concerts for Madrid: Magna Mater (1991), Festi Clamores (2000) and Aurea Catena (2007). While the proposed model comes in the light of the bells concert Llorenç Barber, the scale of a whole city and individual compositional intent, it is understood that it would be useful for the orderly use of any professional interested in the sound aspect of the city, an aspect sparsely attended, incidentally, from the architectural discipline.

Analytical evaluation of uncertainty on active antenna arrays

An analytical method for evaluating the uncertainty of the performance of active antenna arrays in the whole spatial spectrum is presented. Since array processing algorithms based on spatial reference are widely used to track moving targets, it is essential to be aware of the impact of the uncertainty sources on the antenna response. Furthermore, the estimation of the direction of arrival (DOA) depends on the array uncertainty. The aim of the uncertainties analysis is to provide an exhaustive characterization of the behavior of the active antenna array associated with its main uncertainty sources. The result of this analysis helps to select the proper calibration technique to be implemented. An illustrative example for a triangular antenna array used for satellite tracking is presented showing the suitability of the proposed method to carry out an efficient characterization of an active antenna array.