A computer formulation for the analysis on continuous non prismatic folded plate structures of arbitrary cross-section

A computer solution to analyze nonprismatic folded plate structures is shown. Arbitrary cross-sections (simple and multiple), continuity over intermediate supports and general loading and longitudinal boundary conditions are dealt with. The folded plates are assumed to be straight and long (beam like structures) and some simplifications are introduced in order to reduce the computational effort. The formulation here presented may be very suitable to be used in the bridge deck analysis.

A survey on folded plate structures

A compact formulation of the linear theory of folded plate structures utilizing matrix methods is given. Different usual approximations and comparison between them are also shown

Non prismatic folded roof structure

The design of a prestressed concrete roof is described. A special linear elastic analysis of non-prismatic folded structures has been applied. The obtained results have been compared to the results deducted from a small scale model test. Conclusions about the efficiency of these type of structures are shown.

A plastic analysis of nonprismatic folded plate structures

A computer method for the plastic analysis of folded plate structures is presented. The method considers the specific characteristics of the folded plate structural model using a simplified one-dimensional theory. and it can be applied to the analysis of any type of folded pIates, either prismatic or nonprismatic, with arbitrary cross-section. A simple example is analyzed in order to show the possibilities of the procedure and some results of interest are presented

The folded plate model in structural analysis. Elastic, plastic and dynamic formulations for nonprismatic structures

A specific numerical procedure for the analysis of arbitrary nonprismatic folded plate structures is presented. An elastic model is studied and compared with a harmonic solution for a prismatic structure. An extension to the plastic analysis is developed, and the influence of the structural geometry and loading pattern is analyzed. Nonprismatic practical cases, with arbitrary geometry and loading are shown, as well in the elastic range as in the plastic one. Finally, a dynamic formulation is outlined

Development of Efficient Techniques for the Analysis and Design of Antennas in Dual-Reflectarray Configuration

This thesis contributes to the analysis and design of printed reflectarray antennas. The main part of the work is focused on the analysis of dual offset antennas comprising two reflectarray surfaces, one of them acts as sub-reflector and the second one acts as mainreflector. These configurations introduce additional complexity in several aspects respect to conventional dual offset reflectors, however they present a lot of degrees of freedom that can be used to improve the electrical performance of the antenna. The thesis is organized in four parts: the development of an analysis technique for dualreflectarray antennas, a preliminary validation of such methodology using equivalent reflector systems as reference antennas, a more rigorous validation of the software tool by manufacturing and testing a dual-reflectarray antenna demonstrator and the practical design of dual-reflectarray systems for some applications that show the potential of these kind of configurations to scan the beam and to generate contoured beams. In the first part, a general tool has been implemented to analyze high gain antennas which are constructed of two flat reflectarray structures. The classic reflectarray analysis based on MoM under local periodicity assumption is used for both sub and main reflectarrays, taking into account the incident angle on each reflectarray element. The incident field on the main reflectarray is computed taking into account the field radiated by all the elements on the sub-reflectarray.. Two approaches have been developed, one which employs a simple approximation to reduce the computer run time, and the other which does not, but offers in many cases, improved accuracy. The approximation is based on computing the reflected field on each element on the main reflectarray only once for all the fields radiated by the sub-reflectarray elements, assuming that the response will be the same because the only difference is a small variation on the angle of incidence. This approximation is very accurate when the reflectarray elements on the main reflectarray show a relatively small sensitivity to the angle of incidence. An extension of the analysis technique has been implemented to study dual-reflectarray antennas comprising a main reflectarray printed on a parabolic surface, or in general in a curved surface. In many applications of dual-reflectarray configurations, the reflectarray elements are in the near field of the feed-horn. To consider the near field radiated by the horn, the incident field on each reflectarray element is computed using a spherical mode expansion. In this region, the angles of incidence are moderately wide, and they are considered in the analysis of the reflectarray to better calculate the actual incident field on the sub-reflectarray elements. This technique increases the accuracy for the prediction of co- and cross-polar patterns and antenna gain respect to the case of using ideal feed models. In the second part, as a preliminary validation, the proposed analysis method has been used to design a dual-reflectarray antenna that emulates previous dual-reflector antennas in Ku and W-bands including a reflectarray as subreflector. The results for the dualreflectarray antenna compare very well with those of the parabolic reflector and reflectarray subreflector; radiation patterns, antenna gain and efficiency are practically the same when the main parabolic reflector is substituted by a flat reflectarray. The results show that the gain is only reduced by a few tenths of a dB as a result of the ohmic losses in the reflectarray. The phase adjustment on two surfaces provided by the dual-reflectarray configuration can be used to improve the antenna performance in some applications requiring multiple beams, beam scanning or shaped beams. Third, a very challenging dual-reflectarray antenna demonstrator has been designed, manufactured and tested for a more rigorous validation of the analysis technique presented. The proposed antenna configuration has the feed, the sub-reflectarray and the main-reflectarray in the near field one to each other, so that the conventional far field approximations are not suitable for the analysis of such antenna. This geometry is used as benchmarking for the proposed analysis tool in very stringent conditions. Some aspects of the proposed analysis technique that allow improving the accuracy of the analysis are also discussed. These improvements include a novel method to reduce the inherent cross polarization which is introduced mainly from grounded patch arrays. It has been checked that cross polarization in offset reflectarrays can be significantly reduced by properly adjusting the patch dimensions in the reflectarray in order to produce an overall cancellation of the cross-polarization. The dimensions of the patches are adjusted in order not only to provide the required phase-distribution to shape the beam, but also to exploit the crosses by zero of the cross-polarization components. The last part of the thesis deals with direct applications of the technique described. The technique presented is directly applicable to the design of contoured beam antennas for DBS applications, where the requirements of cross-polarisation are very stringent. The beam shaping is achieved by synthesithing the phase distribution on the main reflectarray while the sub-reflectarray emulates an equivalent hyperbolic subreflector. Dual-reflectarray antennas present also the ability to scan the beam over small angles about boresight. Two possible architectures for a Ku-band antenna are also described based on a dual planar reflectarray configuration that provides electronic beam scanning in a limited angular range. In the first architecture, the beam scanning is achieved by introducing a phase-control in the elements of the sub-reflectarray and the mainreflectarray is passive. A second alternative is also studied, in which the beam scanning is produced using 1-bit control on the main reflectarray, while a passive subreflectarray is designed to provide a large focal distance within a compact configuration. The system aims to develop a solution for bi-directional satellite links for emergency communications. In both proposed architectures, the objective is to provide a compact optics and simplicity to be folded and deployed.

Geología de las ultramafitas pre-andinas de Tapo y Acobamba, Tarma, en la Cordillera Oriental de Perú

Ultramafic rocks occur scattered along a 300 km long NNW-SSE trending belt, parallel to the central Peruvian Andes in the Cordillera Oriental, from Tarma (Junín Dept.) to Huancapallac and Tingo María (Huánuco Dept.). The Tarma occurrences (Tapo and Acobamba) are dealt with here, as the first step of a broader research. The Tapo massif comprises strongly tectonised serpentinites with scarce peridotitic relics, amphibolites and podiform chromitites. It was overthrust on early Carboniferous metasedimentary rocks of the Andean basement (Ambo Group), and it shows evidences of a pre-Andean deformational history, not observed in the Ambo Group; the basal thrust plane is folded by the Andean tectonics. The two smaller Acobamba occurrences are also allochtonous and show similar tectonic features. Major and trace element composition of amphibolites point to a tholeiitic basalt (to picrobasalt) protolith, compatible with an ocean-ridge or ocean-island environment. Small podiform chromitite lenses and chromite disseminations also occur; they are strongly deformed, metamorphosed and overprinted by hydrothermal alteration related to deformation, and were the subject of small scale mining. The ores comprise mainly chromite, ferritchromite, spinel, magnetite, ilmenite and scarce sulphides, as well as the secondary minerals stichtite and nimite. Results of this work exclude current interpretations of the Tarma ultramafites as autochtonous igneous intrusives, and point to a new interpretation for their emplacement.

Estructura de una red esencial de señalización que regula la homeostasis iónica en plantas

Las plantas son organismos sésiles que han desarrollado la capacidad para detectar variaciones sutiles en su ambiente y producir respuestas adaptativas mediante rutas de señalización. Los estímulos causados por el estrés biótico y abiótico son numerosos y dependiendo del tiempo de exposición y su intensidad, pueden reducir la tasa de crecimiento de las plantas y la producción. Los cambios en la concentración del calcio citosólico libre constituyen una de las primeras reacciones intracelulares a las situaciones de estrés abiótico. En esta situación, el calcio actúa como segundo mensajero y las variaciones en su concentración son descodificadas por proteínas de unión a calcio. Las más conocidas son las manos-EF y los dominios C2. Los dominios C2 han sido descritos como dominios de unión a lípidos dependientes de calcio. Estos dominios se consideran proteínas periféricas solubles en agua que se asocian de manera reversible a los lípidos de la membrana mediante una o dos regiones funcionales: el sitio de unión a calcio y el sitio polibásico. A pesar de que se conoce la estructura molecular de algunos dominios C2, se desconocen aspectos relacionados como las reglas que dirigen su forma de interaccionar con los diferentes fosfolípidos y proteínas, la posición que ocupan en la bicapa lipídica y su papel en la transmisión de señales. En esta tesis se ha estudiado una proteína de Arabidopsis thaliana (At3g17980) representativa de una nueva familia de proteínas con dominios C2, que consiste únicamente de un dominio C2. Esta proteína, llamada AtC2.1, ha sido clonada en el vector pETM11, expresada en E. coli y purificada a homogeneidad en dos pasos cromatográficos. Se obtuvieron cristales de AtC2.1 de buena calidad mediante técnicas de difusión de vapor. La proteína fue co-cristalizada con calcio, fosfocolina (POC) y el fosfolípido 1,2-dihexanoil-sn-glicero-3-fosfo-L-serina (PSF). Se recogieron ocho conjuntos de datos de difracción de rayos X empleando radiación sincrotrón. Los cristales difractaron hasta 1.6 Å de resolución. Siete de ellos pertenecían al grupo ortorrómbico P212121, con las dimensiones de la celdilla unidad a = 35.3, b = 88.9, c = 110.6 Å, y un cristal pertenecía al grupo espacial monoclínico C2, con a = 124.84, b = 35.27, c = 92.32 Å y = 121.70º. La estructura se resolvió mediante la técnica MR-SAD utilizando el cinc como dispersor anómalo. La estructura cristalina mostró que la molécula forma un dímero en el que cada protómero se pliega como un dominio C2 típico, con la topología tipo II y presenta una inserción de 43 aminoácidos que la diferencia de los dominios C2 conocidos. El mapa de densidad electrónica mostró dos átomos de calcio por protómero. Se resolvieron las estructuras de AtC2.1 en complejo con POC o PSF. En ambos complejos, el análisis cristalográfico detectó máximos de densidad electrónica en la región correspondiente al sitio polibásico formado por las hebras 2, 3 5 y el lazo 3. Éstos se interpretaron correctamente como dos moléculas de POC y un átomo de cinc, en un complejo, y como la cabeza polar del PSF en el otro. AtC2.1 define un sitio de interacción con lípidos dependiente de cinc. En conclusión, en este trabajo se presenta la estructura tridimensional de AtC2.1, miembro representativo de una familia de proteínas de Arabidopsis thaliana, identificadas como proteínas que interaccionan con los receptores de ABA. Estas proteínas están constituidas únicamente por un dominio C2. El análisis conjunto de los datos biofísicos y cristalográficos muestra que AtC2.1 es un sensor de calcio que une lípidos usando dos sitios funcionales. Estos datos sugieren un mecanismo de inserción en membrana dependiente de calcio que trae consigo la disociación de la estructura dimérica y, por consiguiente, un cambio en las propiedades de superficie de la molécula. Este mecanismo proporciona las bases del reconocimiento y transporte de los receptores de ABA y/o otras moléculas a la membrana celular. Plants are sessile organisms that have developed the capacity to detect slight variations of their environment. They are able to perceive biotic and abiotic stress signals and to transduce them by signaling pathways in order to trigger adaptative responses. Stress factors are numerous and, depending on their exposition time and their concentration, can reduce plant growth rate, limiting the productivity of crop plants. Changes in the cytosolic free calcium concentration are observed as one of the earliest intracellular reactions to abiotic stress signals. Calcium plays a key role as a second messenger, and calcium concentration signatures, called calcium signals, are decodified by calcium binding proteins. The main calcium binding structures are the EF-hand motif and the C2 domains. C2 domain is a calcium dependent lipid-binding domain of approximately 130 amino acids. C2 domain displays two functional regions: the Ca-binding region and the polybasic cluster. Both of them can interact with the membrane phospholipids. Despite the number of C2 domain 3D structures currently available, questions about how they interact with the different target phospholipids, their precise spatial position in the lipid bilayer, interactions with other proteins and their role in transmitting signals downstream, have not yet been explored. In this work we have studied an uncharacterized protein from Arabidopsis thaliana (At3g17980) consisting of only a single C2 domain, as member of a new protein C2-domain family. This protein called AtC2.1 was cloned into the pETM11 vector and expressed in E. coli, allowing the purification to homogeneity in two chromatographic steps. Good quality diffracting crystals were obtained using vapor-diffusion techniques. Crystals were co-crystalized with calcium; phosphocholine (POC) and/or the phospholipid 1,2-dihexanoyl-sn-glycero-3-phospho-L-serine (PSF). Eight data set were collected with synchrotron radiation. Crystals diffracted up to 1.6 Å resolution and seven of them belong to the orthorhombic space group P212121, with unit-cell parameters a = 35.3, b = 88.9, c = 110.6 Å. Another crystal was monoclinic, space group C2, with a = 124.84, b = 35.27, c = 92.32 Å and = 121.70º. The structural model was solved by MR-SAD using Zn2+ as anomalous scatterer. The crystal structure shows that the molecule is a dimer. Each monomer was folded as a canonical C2 domain with the topology II with a 43 residues insertion. The electron density map reveals two calcium ions per molecule. Structures of AtC2.1, complexed with POC and PSF, have been solved. Well-defined extra electron densities were found, in both complexes, within the concave surface formed by strands 2, 3, 5 and loop 3 of AtC2.1. These densities were clearly explained by the presence of the two POC molecules, one zinc atom and head groups of PSF, occupying the cavity of the polybasic site. AtC2.1 defines a new metal dependent lipid-binding site into the polybasic site. In conclusion, in this thesis it is presented the molecular structure of AtC2.1, a representative member of a family of Arabidopsis thaliana C2 domain proteins, of unknown function, but identified as a molecular interacting unit of the ABA receptors. The joint analyses of the biophysical and crystallographic data show that AtC2.1 is a calcium sensor that binds lipids in two sites and suggest a model of calcium-dependent membrane insertion mechanism that will involve either dimer dissociation or a strong rearrangement of the dimeric structure. This mechanism may be the basis for the recognition and delivery of ABA receptors or other protein molecules to cell membranes.

Dos décadas de estructuras plegadas de hormigón. Inicio y ocaso de un movimiento

This paper deals with the development and achievements of structures conformed by concrete folded plates. It explores the origins of its analysis and calculation and shows an overview of the main folded plate structures between 1950 and 1970. Great number of technical articles and publications on folded structures appeared in these two decades, to quickly decline shortly after. At least in a symbolic sense, their end can be certified by a memorable and monographic IASS symposium held in 1970 on such structures. More than four decades after the last of the large-scale structures of this type was erected, a review of achievements and possible causes of decadence seems to be pertinent, furthermore considering the growing and renewed interest in the geometry of folds and facets of the last years.

Beitrag zur Entwicklung der Querschnittsgestaltung im Verbundbrückenbau

Die grafische Darstellung des Verbundquerschnittes mit einer oberen Betonplatte und einem darunter liegenden Stahlträger war seit seiner Vorstellung in den 1950er Jahren ein Symbol, das weit über die Theorie hinausging und weite Verbreitung in der Praxis des Verbundbrückenbaus fand. Seit den 1970er bzw. 1980er Jahren hat dieses Bild – bedingt durch neue und freiere Formen, Beton und Stahl miteinander zu kombinieren – seine Symbolhaftigkeit verloren. In Deutschland und Spanien wurde der Doppelverbund mit unten liegenden Betonplatten in Bereichen mit negativen Momenten eingeführt, in Frankreich werden Stahlträger auch in vorgespannten Betonquerschnitten eingebettet. Beide Ansätze haben dazu beigetragen, dass in der Gegenwart die Materialien Stahl und Beton im Verbundbau frei miteinander kombiniert werden können. On the development of sections in composite bridges. A comprehensive theory of composite construction was established in Germany by Sattler in 1953. The theoretical image of the composite section with a superior concrete slab and a lower metallic structure was shaped in addition to the analytical resolution. Theory and graphical representation were going to be known together in Europe. This figure was repeated in all theoretical and academic publications, so becoming an authentic icon of the composite section. Its translation to the bridge deck in flexion was obvious: the superior slab defines the tread platform, while the metallic structure was left off-hook at the bottom. Nevertheless, in continuous decks the section is not optimal at all in zones of negative bending moments. But the overcoming of the graphical representation of the theory did not happen immediately. It was produced after a process in which several European countries played an active role and where different mechanisms of technological transference were developed. One approach to this overcoming is the “double composite action”, with a lower concrete slab in areas of a negative bending moment. The first accomplishments, a bridge in Orasje built in 1968 with 134 m span, as well as the publications of the system proposed by Fabrizio de Miranda in 1971 did not extend nor had continuity. Spanish bridges by Fernández Ordoñez and Martínez Calzón used double composite action for the first time in 1979. The German team of Leonhard, Andrä und partners, has used it since the end of the 1980's to solve bridges of great span. Once the technology has been well known thanks to the ASCE International Congress and the Spanish International Meetings organised by the “Colegio de Ingenieros de Caminos”, double composite action has been integrated well into the structural vocabulary everywhere. In France the approach was different. What Michel Virlogeux calls “double floor composite section” was reached as an evolution of prestressed concrete bridges. In an experimental process widely known, the external prestressing allows weight reduction by diminishing the thickness of the concrete webs. The following step, in the 1980's, was the substitution of the webs by metallic elements: stiffened plates, trusses or folded plates. A direct result of this development is the Brass de la Plaine Bridge in the Reunion Island in 2001 with 280 m span. Both approaches have contributed to a freedom of design in composite construction in steel and concrete today.

Comparison of numerical models for vibro-acoustic analysis of structural panels in low modal density range engaging air layers

During launch, satellite and their equipment are subjected to loads of random nature and with a wide frequency range. Their vibro-acoustic response is an important issue to be analysed, for example for folded solar arrays and antennas. The main issue at low modal density is the modelling combinations engaging air layers, structures and external fluid. Depending on the modal density different methodologies, as FEM, BEM and SEA should be considered. This work focuses on the analysis of different combinations of the methodologies previously stated used in order to characterise the vibro-acoustic response of two rectangular sandwich structure panels isolated and engaging an air layer between them under a diffuse acoustic field. Focusing on the modelling of air layers, different models are proposed. To illustrate the phenomenology described and studied, experimental results from an acoustic test on an ARA-MKIII solar array in folded configuration are presented along with numerical results.

Chaperonas moleculares y tolerancia a estrés abiótico en especies arbóreas

Las temperaturas extremas, la sequía y otros estreses abióticos limitan la producción forestal de forma significativa, causando grandes pérdidas económicas en el sector. Los árboles, al ser organismos sésiles, han desarrollado una serie de estrategias para percibir dichos factores, activando respuestas defensivas apropiadas. Entre ellas ocupa un lugar preeminente la síntesis de proteínas con actividad chaperona molecular. Las chaperonas moleculares interaccionan con proteínas desnaturalizadas total o parcialmente, promoviendo su correcto plegamiento y ensamblaje. Las chaperonas moleculares que se sintetizan de forma predominante en plantas, pero no en otros eucariotas, pertenecen a la familia sHSP (small heat-shock proteins). Se trata de una familia inusualmente compleja y heterogénea, cuyos miembros son de pequeño tamaño (16-42 kD) y poseen un dominio “alfa-cristalina” muy conservado. Estas proteínas están implicadas en protección frente a estrés abiótico mediante la estabilización de proteínas y membranas, si bien su mecanismo de acción se conoce de forma incompleta. A pesar del evidente potencial aplicado de las proteínas sHSP, son muy escasos los estudios realizados hasta el momento con un enfoque netamente biotecnológico. Por otra parte, casi todos ellos se han llevado a cabo en especies herbáceas de interés agronómico o en especies modelo, como Arabidopsis thaliana. De ahí que las sHSP de arbóreas hayan sido mucho menos caracterizadas estructural y funcionalmente, y ello a pesar del interés económico y ecológico de los árboles y de su prolongada exposición vital a múltiples factores estresantes. La presente Tesis Doctoral se centra en el estudio de sHSP de varias especies arbóreas de interés económico. El escrutinio exhaustivo de genotecas de cDNA de órganos vegetativos nos ha permitido identificar y caracterizar los componentes mayoritarios de tallo en dos especies productoras de madera noble: nogal y cerezo. También hemos caracterizado la familia completa en chopo, a partir de su secuencia genómica completa. Mediante expresión heteróloga en bacterias, hemos analizado el efecto protector de estas proteínas in vivo frente a distintos tipos de estrés abiótico, relevantes para el sector productivo. Los resultados demuestran que las proteínas sHSP-CI: (i) aumentan la viabilidad celular de E.coli frente a casi todos estos factores, aplicados de forma individual o combinada; (ii) ejercen un rol estabilizador de las membranas celulares frente a condiciones adversas; (iii) sirven para mejorar la producción de otras proteínas recombinantes de interés comercial. El efecto protector de las proteínas sHSP-CI también ha sido analizado in planta, mediante la expresión ectópica de CsHSP17.5-CI en chopos. En condiciones normales de crecimiento no se han observado diferencias fenotípicas entre las líneas transgénicas y los controles, lo que demuestra que se pueden sobre-expresar estas proteínas sin efectos pleiotrópicos deletéreos. En condiciones de estrés térmico, por el contrario, los chopos transgénicos mostraron menos daños y un mejor crecimiento neto. En línea con lo anterior, las actividades biológicas de varias enzimas resultaron más protegidas frente a la inactivación por calor, corroborando la actividad chaperona propuesta para la familia sHSP y su conexión con la tolerancia al estrés abiótico. En lo que respecta a la multiplicación y propagación de chopo in vitro, una forma de cultivo que comporta estrés para las plantas, todas las líneas transgénicas se comportaron mejor que los controles en términos de producción de biomasa (callos) y regeneración de brotes, incluso en ausencia de estrés térmico. También se comportaron mejor durante su cultivo ex vitro. Estos resultados tienen gran potencial aplicado, dada la recalcitrancia de muchas especies vegetales de interés económico a la micropropagación y a la manipulación in vitro en general. Los resultados derivados de esta Tesis, aparte de aportar datos nuevos sobre el efecto protector de las proteínas sHSP citosólicas mayoritarias (clase CI), demuestran por vez primera que la termotolerancia de los árboles puede ser manipulada racionalmente, incrementando los niveles de sHSP mediante técnicas de ingeniería genética. Su interés aplicado es evidente, especialmente en un escenario de calentamiento global. ABSTRACT Abiotic stress produces considerable economic losses in the forest sector, with extreme temperature and drought being amongst the most relevant factors. As sessile organisms, plants have acquired molecular strategies to detect and recognize stressful factors and activate appropriate responses. A wealth of evidence has correlated such responses with the massive induction of proteins belonging to the molecular chaperone family. Molecular chaperones are proteins which interact with incorrectly folded proteins to help them refold to their native state. In contrast to other eukaryotes, the most prominent stress-induced molecular chaperones of plants belong to the sHSP (small Heat Shock Protein) family. sHSPs are a widespread and diverse class of molecular chaperones that range in size from 16 to 42k Da, and whose members have a highly conserved “alpha-crystallin” domain. sHSP proteins play an important role in abiotic stress tolerance, membrane stabilization and developmental processes. Yet, their mechanism of action remains largely unknown. Despite the applied potential of these proteins, only a few studies have addressed so far the biotechnological implications of this protein family. Most studies have focused on herbaceous species of agronomic interest or on model species such as Arabidopsis thaliana. Hence, sHSP are poorly characterized in long-lived woody species, despite their economic and ecological relevance. This Thesis studies sHSPs from several woody species of economic interest. The most prominent components, namely cytosolic class I sHSPs, have been identified and characterized, either by cDNA library screening (walnut, cherry) or by searching the complete genomic sequence (poplar). Through heterologous bacterial expression, we analyzed the in vivo protective effects of selected components against abiotic stress. Our results demonstrate that sHSP-CI proteins: (i) protect E. coli cells against different stressful conditions, alone or combined; (ii) stabilize cell membranes; (iii) improve the production of other recombinant proteins with commercial interest. The effects of CsHSP17.5-CI overexpression have also been studied in hybrid poplar. Interestingly, the accumulation of this protein does not have any appreciable phenotypic effects under normal growth conditions. However, the transgenic poplar lines showed enhanced net growth and reduced injury under heat-stress conditions compared to vector controls. Biochemical analysis of leaf extracts revealed that important enzyme activities were more protected in such lines against heat-induced inactivation than in control lines, lending further support to the chaperone mode of action proposed for the sHSP family. All transgenic lines showed improved in vitro and ex vitro performance (calli biomass, bud induction, shoot regeneration) compared to controls, even in the absence of thermal stress. Besides providing new insights on the protective role of HSP-CI proteins, our results bolster the notion that heat stress tolerance can be readily manipulated in trees through genetic engineering. The applied value of these results is evident, especially under a global warming scenario.

Vibro-acoustic analysis of spacecraft structures with thin air layers

Esta Tesis presenta un estudio sobre el comportamiento vibroacústico de estructuras espaciales que incluyen capas de aire delgadas, así como sobre su modelización numérica. Las capas de aire pueden constituir un elemento fundamental en estos sistemas, como paneles solares plegados, que se consideran el caso de estudio en este trabajo. Para evaluar la influencia de las capas de aire en la respuesta dinámica del sistema se presenta el uso de modelos unidimensionales. La modelización de estos sistemas se estudia para los rangos de baja y alta frecuencia. En el rango de baja frecuencia se propone un conjunto de estrategias de simulación basadas en técnicas numéricas que se utilizan habitualmente en la industria aeroespacial para facilitar la aplicación de los resultados de la Tesis en los modelos numéricos actuales. Los resultados muestran el importante papel de las capas de aire en la respuesta del sistema. El uso de modelos basados en elementos finitos o de contorno para estos elementos proporciona resultados equivalentes aunque la aplicabilidad de estos últimos puede estar condicionada por la geometría del problema. Se estudia asimismo el uso del Análisis Estadístico de la Energía (SEA) para estos elementos. Una de las estrategias de simulación propuestas, que incluye una formulación energética para el aire que rodea a la estructura, se propone como estimador preliminar de la respuesta del sistema y sus frecuencias propias. Para el rango de alta frecuencia, se estudia la influencia de la definición del propio modelo SEA. Se presenta el uso de técnicas de reducción para determinar una matriz de pérdidas SEA reducida para definiciones incompletas del sistema (si algún elemento que interactúa con el resto no se incluye en el modelo). Esta nueva matriz tiene en cuenta la contribución de las subestructuras que no se consideran parte del modelo y que suelen ignorarse en el procedimiento habitual para reducir el tamaño del mismo. Esta matriz permite también analizar sistemas que incluyen algún componente con problemas de accesibilidad para medir su respuesta. Respecto a la determinación de los factores de pérdidas del sistema, se presenta una metodología que permite abordar casos en los que el método usual, el Método de Inyección de Potencia (PIM), no puede usarse. Se presenta un conjunto de métodos basados en la técnicas de optimización y de actualización de modelos para casos en los que no se puede medir la respuesta de todos los elementos del sistema y también para casos en los que no todos los elementos pueden ser excitados, abarcando un conjunto de casos más amplio que el abordable con el PIM. Para ambos rangos de frecuencia se presentan diferentes casos de análisis: modelos numéricos para validar los métodos propuestos y un panel solar plegado como caso experimental que pone de manifiesto la aplicación práctica de los métodos presentados en la Tesis. ABSTRACT This Thesis presents an study on the vibro-acoustic behaviour of spacecraft structures with thin air layers and their numerical modelling. The air layers can play a key role in these systems as solar wings in folded configuration that constitute the study case for this Thesis. A method based on one-dimensional models is presented to assess the influence of the air layers in the dynamic response of the system. The modelling of such systems is studied for low and high frequency ranges. In the low frequency range a set of modelling strategies are proposed based on numerical techniques used in the industry to facilitate the application of the results in the current numerical models. Results show the active role of the air layers in the system response and their great level of influence. The modelling of these elements by means of Finite Elements (FE) and Boundary Elements (BE) provide equivalent results although the applicability of BE models can be conditioned by the geometry of the problem. The use of Statistical Energy Analysis (SEA) for these systems is also presented. Good results on the system response are found for models involving SEA beyond the usual applicability limit. A simulation strategy, involving energetic formulation for the surrounding fluid is proposed as fast preliminary approach for the system response and the coupled eigenfrequencies. For the high frequency range, the influence of the definition of the SEA model is presented. Reduction techniques are used to determine a Reduced SEA Loss Matrix if the system definition is not complete and some elements, which interact with the rest, are not included. This new matrix takes into account the contribution of the subsystems not considered that are neglected in the usual approach for decreasing the size of the model. It also allows the analysis of systems with accessibility restrictions on some element in order to measure its response. Regarding the determination of the loss factors of a system, a methodology is presented for cases in which the usual Power Injection Method (PIM) can not be applied. A set of methods are presented for cases in which not all the subsystem responses can be measured or not all the subsystems can be excited, as solar wings in folded configuration. These methods, based on error minimising and model updating techniques can be used to calculate the system loss factors in a set of cases wider than the PIM’s. For both frequency ranges, different test problems are analysed: Numerical models are studied to validate the methods proposed; an experimental case consisting in an actual solar wing is studied on both frequency ranges to highlight the industrial application of the new methods presented in the Thesis.

Transversal load distribution on bridge decks

An orthotropic rectangular plate is analysed. The plate has been considered simply supported in two opposite edges and general boundary conditions along the remainder edges. Matrix formulation, very convenient for programming on a digital computer, is used through the text. This technique is applied to an actual bridge deck and the results are compared with those obtained by means of the Guyon-Massonet-Rowe method

La transformación de la fachada en la arquitectura del siglo XX : evolución de los elementos arquitectónicos hacia el espacio

Esta tesis doctoral, bajo el título “La transformación de la fachada en la arquitectura del siglo XX. Evolución de los elementos arquitectónicos hacia el espacio único”, examina –siguiendo el método deductivo mediante investigación documental y de campo– los principales mecanismos proyectuales que han originado una transformación arquitectónica en la fachada. El término fachada, leído normalmente como sinónimo de arquitectura, ha sido analizado bajo taxonomías historiográficas, sociopolíticas, formales, compositivas o materiales. Más allá de estas clasificaciones, esta investigación determina cómo han evolucionado los elementos arquitectónicos hacia el espacio único, transformando con ello tanto la realidad física como el concepto de fachada. Proyectar, como diría Robert Venturi1. 1966, tanto desde el exterior al interior como desde el interior al exterior, produce las tensiones necesarias que ayudan a generar la arquitectura. De ahí la importancia del estudio de la transformación de la fachada como faccia, máscara, disfraz o sistema de representación, a la fachada como un diafragma activo, como un espacio de relación o como un límite donde se produce una experiencia arquitectónica con nuevos significados. El término fachada, del latín facies y del italiano facciata, fue creado como tal durante el siglo XVI, aunque como elemento arquitectónico es una realidad clásica y un concepto humanista reinventado en el Renacimiento. A principios del siglo XX la fachada se transforma radicalmente, con la aparición del vidrio plano de grandes dimensiones, y se despoja de su carga historicista. La transparencia literal hace desaparecer (negar) la fachada. La fachada se construye con nuevos materiales, nuevas tecnologías, y responde a un espacio global que espera a ser colonizado por una sociedad en constante mutación; un espacio que irá siendo cada vez más complejo a lo largo del siglo pasado y que tendrá como una de sus principales consecuencias un mayor grado de abstracción en la fachada. Para desarrollar con mayor precisión las intenciones de este trabajo se analiza la acepción de fachada en la que se encuadra la línea de investigación de la tesis doctoral. Siguiendo las indicaciones del Profesor Kenneth Frampton, se ha optado por dedicar precisamente a este análisis el primer capítulo, de precedentes, con el fin de hacer una relectura de la fachada barroca en clave contemporánea. La fachada barroca se estudia como un punto de inflexión, y origen de la transformación, frente al clasicismo de siglos precedentes. Se plantea por tanto como el primero de los mecanismos proyectuales motivo de estudio. Estos mecanismos han sido sometidos a una clasificación que responde a diversos tipos de espacio arquitectónico que han provocado la transformación de la fachada, analizando cada uno de ellos con un filtro bajo el cual se ha desarrollado un estudio pormenorizado. De esta manera se examinan la transformación compositiva de la fachada por medio del espacio dinámico (capítulo 00_precedentes) en San Carlo alle Quattro Fontane de Francesco Borromini, la transformación constructiva de la fachada por medio del espacio membrana (capítulo 01) en la Villa Tugendhat de Mies van der Rohe, la transformación diagramática de la fachada por medio del espacio pliegue (capítulo 02) en la terminal portuaria de Yokohama de FOA, la transformación tecnológica de la fachada por medio del espacio estructura (capítulo 03) en la mediateca de Sendai de Toyo Ito y, finalmente, la transformación fenomenológica de la fachada por medio del espacio múltiple (capítulo 04) en el pabellón de vidrio del Museo Toledo de SANAA. La investigación se completa con el análisis de una serie de textos que acompañan a cada uno de los capítulos, generando así un cuerpo de conocimiento global junto al análisis documental y las visitas de campo de cada uno de los casos de estudio considerados. ABSTRACT This doctoral thesis entitled “The Transformation of the Façade in Twentieth Century Architecture. The Evolution of Architectural Elements Towards a Single Space“ employs a deductive methodology incorporating both archival and field research, to examine the main design strategies that have given rise to the architectural transformation of the façade. The term façade, usually read as a synonym for architecture, has been analyzed under historiographic, sociopolitical, formal, compositive and material taxonomies. Far beyond these classifications, this study determines how architectural elements have evolved towards a single space, consequently transforming both the physical reality and the concept of façade. As Robert Venturi would say,1 to design from the inside-out and from the outside-in can create valid tensions that help generate architecture, hence the importance of this study of the transformation of the façade as a faccia, a mask, disguise or representation system, to the façade as an active diaphragm, a connective space or a limit within which architectural events with new meaning take place. The term fachada (Spanish for façade), from the Latin facies and the Italian facciata, appeared as such during the sixteenth century, although as an architectural element it is a classical ingredient and a humanist concept reinvented during the Renaissance. At the beginning of the 20th century, the façade is radically transformed with the introduction of large format plate glass, stripping it of its historicist content. Literal transparency causes the façade to disappear. The façade is built with new materials, new technologies, responding to a global space to be occupied by an everchanging society. It is a space that becomes increasingly more complex throughout the last century and which will have, as a consequence, a larger degree of abstraction in the façade. In order to more precisely focus this investigation, the meaning of the façade has been scrutinized. Following Professor Kenneth Frampton’s advice, the first chapter -Precedents- is precisely dedicated to this analysis, in order to understand the baroque façade read in a contemporary manner. The baroque façade has been studied as a turning point, the origin of the transformation of the façade, as compared to the classicism of previous centuries. For this reason it is considered the first design strategy to be studied. These strategeies have been sorted into a classification of architectural spaces that have caused the transformation of the façade, all of which having been analyzed using a methodology allowing for detailed study. Thus, this investigation examines the compositional transformation of the façade by means of a dynamic space (chapter 00: Precedents) in San Carlo alle Quattro Fontane by Francesco Borromini, the constructive transformation of the façade by means of a membrane space (chapter 01) in the Tugendhat Villa by Mies van der Rohe, the diagrammatic transformation of the façade by means of a folded space (chapter 02) in the Yokohama International Port Terminal by FOA, the technological transformation of the façade by means of a structure space (chapter 03) in the Sendai Mediathèque by Toyo Ito, and finally, the technological transformation of the façade by means of multiple space (chapter 04) in the Glass Pavilion of the Toledo Museum of Art by SANAA. The research is supplemented by the analysis of a series of texts presented alongside each chapter; creating a global body of knowledge together alongside the documentary analysis and on site analysis of each of the case studies considered.