Edge Detection by Adaptive Splitting II. The Three-Dimensional Case

In Llanas and Lantarón, J. Sci. Comput. 46, 485–518 (2011) we proposed an algorithm (EDAS-d) to approximate the jump discontinuity set of functions defined on subsets of ℝ d . This procedure is based on adaptive splitting of the domain of the function guided by the value of an average integral. The above study was limited to the 1D and 2D versions of the algorithm. In this paper we address the three-dimensional problem. We prove an integral inequality (in the case d=3) which constitutes the basis of EDAS-3. We have performed detailed computational experiments demonstrating effective edge detection in 3D function models with different interface topologies. EDAS-1 and EDAS-2 appealing properties are extensible to the 3D case

Three-level cell topology for a multilevel power supply to achieve High

This paper presents an envelope amplifier solution for envelope elimination and restoration (EER), that consists of a series combination of a switch-mode power supply (SMPS), based on three-level voltage cells and a linear regulator. This cell topology offers several advantages over a previously presented envelope amplifier based on a different multilevel topology (two-level voltage cells). The topology of the multilevel converter affects to the whole design of the envelope amplifier and a comparison between both design alternatives regarding the size, complexity and the efficiency of the solution is done. Both envelope amplifier solutions have a bandwidth of 2 MHz with an instantaneous maximum power of 50 W. It is also analyzed the linearity of the three-level cell solution, with critical importance in the EER technique implementation. Additionally, considerations to optimize the design of the envelope amplifier and experimental comparison between both cell topologies are included.

Wavelet-based image fusion in multi-view three-dimensional microscopy

Multi-view microscopy techniques such as Light-Sheet Fluorescence Microscopy (LSFM) are powerful tools for 3D + time studies of live embryos in developmental biology. The sample is imaged from several points of view, acquiring a set of 3D views that are then combined or fused in order to overcome their individual limitations. Views fusion is still an open problem despite recent contributions in the field. We developed a wavelet-based multi-view fusion method that, due to wavelet decomposition properties, is able to combine the complementary directional information from all available views into a single volume. Our method is demonstrated on LSFM acquisitions from live sea urchin and zebrafish embryos. The fusion results show improved overall contrast and details when compared with any of the acquired volumes. The proposed method does not need knowledge of the system's point spread function (PSF) and performs better than other existing PSF independent fusion methods.

Comparison of dynamic effects of high-speed traffic load on ballasted track using a simplified two-dimensional and full three-dimensional model.

The vertical dynamic actions transmitted by railway vehicles to the ballasted track infrastructure is evaluated taking into account models with different degree of detail. In particular, we have studied this matter from a two-dimensional (2D) finite element model to a fully coupled three-dimensional (3D) multi-body finite element model. The vehicle and track are coupled via a non-linear Hertz contact mechanism. The method of Lagrange multipliers is used for the contact constraint enforcement between wheel and rail. Distributed elevation irregularities are generated based on power spectral density (PSD) distributions which are taken into account for the interaction. The numerical simulations are performed in the time domain, using a direct integration method for solving the transient problem due to the contact nonlinearities. The results obtained include contact forces, forces transmitted to the infrastructure (sleeper) by railpads and envelopes of relevant results for several track irregularities and speed ranges. The main contribution of this work is to identify and discuss coincidences and differences between discrete 2D models and continuum 3D models, as wheel as assessing the validity of evaluating the dynamic loading on the track with simplified 2D models

Topology of a percolating soil pore network.

A connectivity function defined by the 3D-Euler number, is a topological indicator and can be related to hydraulic properties (Vogel and Roth, 2001). This study aims to develop connectivity Euler indexes as indicators of the ability of soils for fluid percolation. The starting point was a 3D grey image acquired by X-ray computed tomography of a soil at bulk density of 1.2 mg cm-3. This image was used in the simulation of 40000 particles following a directed random walk algorithms with 7 binarization thresholds. These data consisted of 7 files containing the simulated end points of the 40000 random walks, obtained in Ruiz-Ramos et al. (2010). MATLAB software was used for computing the frequency matrix of the number of particles arriving at every end point of the random walks and their 3D representation.

Three-Dimensional Analysis of Spiny Dendrites Using Straightening and Unrolling Transforms

Current understanding of the synaptic organization of the brain depends to a large extent on knowledge about the synaptic inputs to the neurons. Indeed, the dendritic surfaces of pyramidal cells (the most common neuron in the cerebral cortex) are covered by thin protrusions named dendritic spines. These represent the targets of most excitatory synapses in the cerebral cortex and therefore, dendritic spines prove critical in learning, memory and cognition. This paper presents a new method that facilitates the analysis of the 3D structure of spine insertions in dendrites, providing insight on spine distribution patterns. This method is based both on the implementation of straightening and unrolling transformations to move the analysis process to a planar, unfolded arrangement, and on the design of DISPINE, an interactive environment that supports the visual analysis of 3D patterns.

3-dimensional binaural sound rendering using acoustic measurements stored in the SOFA format

Several groups all over the world are researching in several ways to render 3D sounds. One way to achieve this is to use Head Related Transfer Functions (HRTFs). These measurements contain the Frequency Response of the human head and torso for each angle. Some years ago, was only possible to measure these Frequency Responses only in the horizontal plane. Nowadays, several improvements have made possible to measure and use 3D data for this purpose. The problem was that the groups didn't have a standard format file to store the data. That was a problem when a third part wanted to use some different HRTFs for 3D audio rendering. Every of them have different ways to store the data. The Spatially Oriented Format for Acoustics or SOFA was created to provide a solution to this problem. It is a format definition to unify all the previous different ways of storing any kind of acoustics data. At the moment of this project they have defined some basis for the format and some recommendations to store HRTFs. It is actually under development, so several changes could come. The SOFA[1] file format uses a numeric container called netCDF[2], specifically the Enhaced data model described in netCDF 4 that is based on HDF5[3]. The SoundScape Renderer (SSR) is a tool for real-time spatial audio reproduction providing a variety of rendering algorithms. The SSR was developed at the Quality and Usability Lab at TU Berlin and is now further developed at the Institut für Nachrichtentechnik at Universität Rostock [4]. This project is intended to be an introduction to the use of SOFA files, providing a C++ API to manipulate them and adapt the binaural renderer of the SSR for working with the SOFA format. RESUMEN. El SSR (SoundScape Renderer) es un programa que está siendo desarrollado actualmente por la Universität Rostock, y previamente por la Technische Universität Berlin. El SSR es una herramienta diseñada para la reproducción y renderización de audio 2D en tiempo real. Para ello utiliza diversos algoritmos, algunos orientados a sistemas formados por arrays de altavoces en diferentes configuraciones y otros algoritmos diseñados para cascos. El principal objetivo de este proyecto es dotar al SSR de la capacidad de renderizar sonidos binaurales en 3D. Este proyecto está centrado en el binaural renderer del SSR. Este algoritmo se basa en el uso de HRTFs (Head Related Transfer Function). Las HRTFs representan la función de transferencia del sistema formado por la cabeza y el torso del oyente. Esta función es medida desde diferentes ángulos. Con estos datos el binaural renderer puede generar audio en tiempo real simulando la posición de diferentes fuentes. Para poder incluir una base de datos con HRTFs en 3D se ha hecho uso del nuevo formato SOFA (Spatially Oriented Format for Acoustics). Este nuevo formato se encuentra en una fase bastante temprana de su desarrollo. Está pensado para servir como formato estándar para almacenar HRTFs y cualquier otro tipo de medidas acústicas, ya que actualmente cada laboratorio cuenta con su propio formato de almacenamiento y esto hace bastante difícil usar varias bases de datos diferentes en un mismo proyecto. El formato SOFA hace uso del contenedor numérico netCDF, que a su vez esta basado en un contenedor más básico llamado HRTF-5. Para poder incluir el formato SOFA en el binaural renderer del SSR se ha desarrollado una API en C++ para poder crear y leer archivos SOFA con el fin de utilizar los datos contenidos en ellos dentro del SSR.

Wind tunnel analysis of the flow topology over complex topographies

El principal objetivo de este trabajo es aportar conocimiento para contestar la pregunta: ¿hasta que punto los ensayos en túnel aerodinámico pueden contribuir a determinar las características que afectan la respuesta dinámica de los aerogeneradores operando en terreno complejo?. Esta pregunta no es nueva, de hecho, el debate en la comunidad científica comenzó en el primer tercio del siglo pasado y aún está intensamente vivo. El método generalmente aceptado para enfrentar el mencionado problema consiste en analizar un caso de estudio determinado en el cual se aplican tanto ensayos a escala real como análisis computacionales y ensayos en túnel aerodinámico. Esto no es ni fácil ni barato. Esta es la razón por la cual desde el experimento de Askervein en 1988, los modelizadores del flujo atmosférico tuvieron que esperar hasta 2007 a que el experimento de Bolund fuese puesto en marcha con un despliegue de medios técnicos equivalentes (teniendo en cuenta la evolución de las tecnologías de sensores y computación). El problema contempla tantos aspectos que ambas experiencias fueron restringidas a condiciones de atmósfera neutra con efectos de Coriolis despreciables con objeto de reducir la complejidad. Este es el contexto en el que se ha desarrollado la presente tesis doctoral. La topología del flujo sobre la isla de Bolund ha sido estudiada mediante la reproducción del experimento de Bolund en los túneles aerodinámicos A9 y ACLA16 del IDR. Dos modelos de la isla de Bolund fueron fabricados a dos escalas, 1:230 y 1:115. El flujo de entrada en el túnel aerodinámico simulando la capa límite sin perturbar correspondía a régimen de transición (transitionally rough regime) y fue usado como situación de referencia. El modelo a escala 1:230 fue ensayado en el túnel A9 para determinar la presión sobre su superficie. La distribución del coeficiente de presión sobre la isla proporcionó una visualización y estimación de una región de desprendimiento sobre el pequeño acantilado situado al frente de la misma. Las medidas de presión instantánea con suficiente grado de resolución temporal pusieron de manifiesto la no estacionariedad en la región de desprendimiento. El modelo a escala 1:115 fue ensayado utilizando hilo caliente de tres componentes y un sistema de velocimetría por imágenes de partículas de dos componentes. El flujo fue caracterizado por el ratio de aceleración, el incremento normalizado de energía cinética turbulenta y los ángulos de inclinación y desviación horizontal. Los resultados a lo largo de la dirección 270°y alturas de 2 m y 5 m presentaron una gran similitud con los resultados a escala real del experimento de Bolund. Los perfiles verticales en las localizaciones de las torres meteorológicas mostraron un acuerdo significativo con los resultados a escala real. El análisis de los esfuerzos de Reynolds y el análisis espectral en las localizaciones de los mástiles meteorológicos presentaron niveles de acuerdo variados en ciertas posiciones, mientras que en otras presentaron claras diferencias. El mapeo horizontal del flujo, para una dirección de viento de 270°, permitió caracterizar el comportamiento de la burbuja intermitente de recirculación sobre el pequeño acantilado existente al frente de la isla así como de la región de relajación y de la capa de cortadura en la región corriente abajo de Bolund. Se realizaron medidas de velocidad con alta resolución espacial en planos perpendiculares a la dirección del flujo sin perturbar. Estas medidas permitieron detectar y caracterizar una estructura de flujo similar a un torbellino longitudinal con regiones con altos gradientes de velocidad y alta intensidad de turbulencia. Esta estructura de flujo es, sin duda, un reto para los modelos computacionales y puede considerarse un factor de riesgo para la operación de los aerogeneradores. Se obtuvieron y analizaron distribuciones espaciales de los esfuerzos de Reynolds mediante 3CHW y PIV. Este tipo de parámetros no constituyen parte de los resultados habituales en los ensayos en túnel sobre topografías y son muy útiles para los modelizadores que utilizan simulación de grades torbellinos (LES). Se proporciona una interpretación de los resultados obtenidos en el túnel aerodinámico en términos de utilidad para los diseñadores de parques eólicos. La evolución y variación de los parámetros del flujo a lo largo de líneas, planos y superficies han permitido identificar como estas propiedades del flujo podrían afectar la localización de los aerogeneradores y a la clasificación de emplazamientos. Los resultados presentados sugieren, bajo ciertas condiciones, la robustez de los ensayos en túnel para estudiar la topología sobre terreno complejo y su comparabilidad con otras técnicas de simulación, especialmente considerando el nivel de acuerdo del conjunto de resultados presentados con los resultados a escala real. De forma adicional, algunos de los parámetros del flujo obtenidos de las medidas en túnel son difícilmente determinables en ensayos a escala real o por medios computacionales, considerado el estado del arte. Este trabajo fue realizado como parte de las actividades subvencionadas por la Comisión Europea como dentro del proyecto FP7-PEOPLE-ITN-2008WAUDIT (Wind Resource Assessment Audit and Standardization) dentro de la FP7 Marie-Curie Initial Training Network y por el Ministerio Español de Economía y Competitividad dentro del proyecto ENE2012-36473, TURCO (Determinación en túnel aerodinámico de la distribución espacial de parámetros estadísticos de la turbulencia atmosférica sobre topografías complejas) del Plan Nacional de Investigación (Subprograma de investigación fundamental no orientada 2012). El informe se ha organizado en siete capítulos y un conjunto de anexos. En el primer capítulo se introduce el problema. En el capítulo dos se describen los medios experimentales utilizados. Seguidamente, en el capítulo tres, se analizan en detalle las condiciones de referencia del principal túnel aerodinámico utilizado en esta investigación. En el capítulo tres se presentan resultados de ensayos de presión superficial sobre un modelo de la isla. Los principales resultados del experimento de Bolund se reproducen en el capítulo cinco. En el capítulo seis se identifican diferentes estructuras del flujo sobre la isla y, finalmente, en el capitulo siete, se recogen las conclusiones y una propuesta de lineas de trabajo futuras. ABSTRACT The main objective of this work is to contribute to answer the question: to which extend can the wind tunnel testing contribute to determine the flow characteristics that affect the dynamic response of wind turbines operating in highly complex terrains?. This question is not new, indeed, the debate in the scientific community was opened in the first third of the past century and it is still intensely alive. The accepted approach to face this problem consists in analysing a given case study where full-scale tests, computational modelling and wind tunnel testing are applied to the same topography. This is neither easy nor cheap. This is is the reason why since the Askervein experience in 1988, the atmospheric flow modellers community had to wait till 2007 when the Bolund experiment was setup with a deployment of technical means equivalent (considering the evolution of the sensor and computing techniques). The problem is so manifold that both experiences were restricted to neutral conditions without Coriolis effects in order to reduce the complexity. This is the framework in which this PhD has been carried out. The flow topology over the Bolund Island has been studied by replicating the Bolund experiment in the IDR A9 and ACLA16 wind tunnels. Two mock-ups of the Bolund island were manufactured at two scales of 1:230 and 1:115. The in-flow in the empty wind tunnel simulating the incoming atmospheric boundary layer was in the transitionally rough regime and used as a reference case. The 1:230 model was tested in the A9 wind tunnel to measure surface pressure. The mapping of the pressure coefficient across the island gave a visualisation and estimation of a detachment region on the top of the escarpment in front of the island. Time resolved instantaneous pressure measurements illustrated the non-steadiness in the detachment region. The 1:115 model was tested using 3C hot-wires(HW) and 2C Particle Image Velocimetry(PIV). Measurements at met masts M3, M6, M7 and M8 and along Line 270°were taken to replicate the result of the Bolund experiment. The flow was characterised by the speed-up ratio, normalised increment of the turbulent kinetic energy, inclination angle and turning angle. Results along line 270°at heights of 2 m and 5 m compared very well with the full-scale results of the Bolund experiment. Vertical profiles at the met masts showed a significant agreement with the full-scale results. The analysis of the Reynolds stresses and the spectral analysis at the met mast locations gave a varied level of agreement at some locations while clear mismatch at others. The horizontal mapping of the flow field, for a 270°wind direction, allowed to characterise the behaviour of the intermittent recirculation bubble on top of the front escarpment followed by a relaxation region and the presence of a shear layer in the lee side of the island. Further detailed velocity measurements were taken at cross-flow planes over the island to study the flow structures on the island. A longitudinal vortex-like structure with high mean velocity gradients and high turbulent kinetic energy was characterised on the escarpment and evolving downstream. This flow structure is a challenge to the numerical models while posing a threat to wind farm designers when siting wind turbines. Spatial distribution of Reynold stresses were presented from 3C HW and PIV measurements. These values are not common results from usual wind tunnel measurements and very useful for modellers using large eddy simulation (LES). An interpretation of the wind tunnel results in terms of usefulness to wind farm designers is given. Evolution and variation of the flow parameters along measurement lines, planes and surfaces indicated how the flow field could affect wind turbine siting. Different flow properties were presented so compare the level of agreement to full-scale results and how this affected when characterising the site wind classes. The results presented suggest, under certain conditions, the robustness of the wind tunnel testing for studying flow topology over complex terrain and its capability to compare to other modelling techniques especially from the level of agreement between the different data sets presented. Additionally, some flow parameters obtained from wind tunnel measurements would have been quite difficult to be measured at full-scale or by computational means considering the state of the art. This work was carried out as a part of the activities supported by the EC as part of the FP7- PEOPLE-ITN-2008 WAUDIT project (Wind Resource Assessment Audit and Standardization) within the FP7 Marie-Curie Initial Training Network and by the Spanish Ministerio de Economía y Competitividad, within the framework of the ENE2012-36473, TURCO project (Determination of the Spatial Distribution of Statistic Parameters of Flow Turbulence over Complex Topographies in Wind Tunnel) belonging to the Spanish National Program of Research (Subprograma de investigación fundamental no orientada 2012). The report is organised in seven chapters and a collection of annexes. In chapter one, the problem is introduced. In chapter two the experimental setup is described. Following, in chapter three, the inflow conditions of the main wind tunnel used in this piece of research are analysed in detail. In chapter three, preliminary pressure tests results on a model of the island are presented. The main results from the Bolund experiment are replicated in chapter five. In chapter six, an identification of specific flow strutures over the island is presented and, finally, in chapter seven, conclusions and lines for future works related to the presented one are included.

Two-dimensional mesh optimization in the finite element method

The solution to the problem of finding the optimum mesh design in the finite element method with the restriction of a given number of degrees of freedom, is an interesting problem, particularly in the applications method. At present, the usual procedures introduce new degrees of freedom (remeshing) in a given mesh in order to obtain a more adequate one, from the point of view of the calculation results (errors uniformity). However, from the solution of the optimum mesh problem with a specific number of degrees of freedom some useful recommendations and criteria for the mesh construction may be drawn. For 1-D problems, namely for the simple truss and beam elements, analytical solutions have been found and they are given in this paper. For the more complex 2-D problems (plane stress and plane strain) numerical methods to obtain the optimum mesh, based on optimization procedures have to be used. The objective function, used in the minimization process, has been the total potential energy. Some examples are presented. Finally some conclusions and hints about the possible new developments of these techniques are also given.

Resilient Wireless Sensor Networks Using Topology Control: A Review

Wireless sensor networks (WSNs) may be deployed in failure-prone environments, and WSNs nodes easily fail due to unreliable wireless connections, malicious attacks and resource-constrained features. Nevertheless, if WSNs can tolerate at most losing k − 1 nodes while the rest of nodes remain connected, the network is called k − connected. k is one of the most important indicators for WSNs’ self-healing capability. Following a WSN design flow, this paper surveys resilience issues from the topology control and multi-path routing point of view. This paper provides a discussion on transmission and failure models, which have an important impact on research results. Afterwards, this paper reviews theoretical results and representative topology control approaches to guarantee WSNs to be k − connected at three different network deployment stages: pre-deployment, post-deployment and re-deployment. Multi-path routing protocols are discussed, and many NP-complete or NP-hard problems regarding topology control are identified. The challenging open issues are discussed at the end. This paper can serve as a guideline to design resilient WSNs.

Lo intermedio como lugar : lo intersticial, lo fronterizo y lo impreciso en la arquitectura contemporánea

1. Nuestra investigación se centra en el estudio de los “ámbitos o espacios intermedios” en momentos de la arquitectura contemporánea, en un período de transición entre finales de los años 80 y nuestros días. Pretendemos analizar cómo se presenta el ámbito intermedio en el objeto o lugar arquitectónico y su función o relación con el entorno cercano, desde el proyecto hasta su repercusión en la experiencia vivida. 2. El concepto de intermedio entendido como ámbito o espacio intersticial, fronterizo y ambivalente (o multivalente), atraviesa en la presente investigación el campo de la etimología, de la ciencia, del pensamiento y del arte, para detenerse en la arquitectura actual, llevándose a cabo una indagación concreta en el proceso de concepción, en la propuesta formal, espacial y funcional, así como en la percepción y demás experiencias o vivencias en el lugar arquitectónico. 3. En primer lugar nos proponemos estudiar y explorar el concepto de “intermedio” en sus características, funciones y ubicaciones dentro de la cultura contemporánea, detectando sus antecedentes culturales más importantes, para a continuación aplicarlo reflexivamente a obras significativas de arquitectura. La investigación se enfoca en la modalidad figural (imprecisa) de lo intermedio (en alusión al “figural” deleuziano), cuyas metáforas base son lo translúcido, la penumbra y la espuma, vinculadas al actual paradigma cultural de la complejidad (C. Jencks). A continuación se analizan las relaciones o implicaciones de dicha modalidad figural en obras de arquitectos como Eisenman, Holl, Tschumi, Ito, Fujimoto, Van Berkel y Bos, y Siza, comprobando su valor operativo y poniendo de manifiesto su sentido e importancia en la actualidad y en la disciplina. El estudio tiene como trasfondo el concepto de in-between de la obra de Eisenman, y utiliza conceptos de la filosofía del límite de Trías como algunos de sus principales fundamentos. 4. En cada una de las obras de arquitectura presentadas esta modalidad imprecisa se traduce en un ámbito o espacio intermedio figural específico. Son obras en las que real y virtual, matricial y objetual, arquitectura y territorio, existente y nuevo, colectivo e individual, social e íntimo, interior y exterior, y demás usos y funciones se entrelazan o funden. Son arquitecturas cuya geometría ya no se encuentra tan determinada por aspectos bi o tridimensionales del dibujo o de la construcción. A través de la manipulación de estas geometrías más o menos complejas, dinámicas e intersticiales, estas obras reflejan (o intuyen) las premisas del actual Zeitgeist: un cambio de esquemas de objetos a relaciones basado en un pensamiento más holístico, transdisciplinar, sistémico o complejo (E. Morin), y una nueva conciencia colectiva sobre la realidad que anuncia la crisis de la percepción, el cambio de paradigma y nuevos valores (F. Capra). Emerge otra forma de sentir y percibir el mundo, los lugares y los espacios, que poco a poco está cambiando el modo de pensar y dibujar la arquitectura, y consecuentemente de interaccionar con ella. 5. El sentido del espacio intermedio figural, emerge en las cada vez más complejas cualidades morfológico-espaciales y funcionales de una parte importante de la arquitectura actual. Arquitectura, geometría y tecnología informática están más entrelazadas que nunca, y de un modo más libre, para así poder indagar en nuevas formas de pensar y crear lugares en que los “espacios intermedios” que investigamos son un testimonio. El espacio arquitectónico se vuelve afectivo e interactivo, un lugar intermedio figural, formalizado por espacialidades intersticiales que parecen aludir a lo líquido, donde la forma es más matriz que configuración, el espacio más espacialidad que compartimiento, la función más versátil y multivalente que específica o autónoma, y la perplejidad, la imaginación y la evocación se entrecruzan y vuelven patentes. 6. La arquitectura de los lugares intermedios valora no solamente el “plano”, la “configuración” y la “transparencia”, sino sobre todo el “espacio” y la “relación” en sus interrelaciones con los usuarios y demás contextos. De la identidad a la relacionalidad, de la representación a la presentación, es una arquitectura que propone “otros espacios” que más que espacios son topografías y espacialidades intersticiales, de tensión, transición, transformación, relación, intercambio e interacción. Son lugares intermedios reales y virtuales, que se sirven tanto de la morfología como de la topología para conquistar nuevas espacialidades, pretendiendo salir de la estricta operación de “forming”/”morphing”/formación/”conformación” para explorar la de “spacing”/espaciamiento. Son lugares que se basan en conceptos como la zona de indiscernibilidad de Deleuze, la imagen- flujo de Buci-Glucksmann, la suspensión-entre de Sloterdijk, o el espacio no-objetivo al que se refiere José Gil, plasmándose en la arquitectura contemporánea como tropos de lo intersticial. 7. Son los lugares intermedios de la arquitectura actual, de espacialidad háptica, más “afectiva”, generativa e interactiva, donde ese ámbito intermedio transforma y es transformado, “afecta”, “con-mueve” (nos hace mover/accionar) y evoca otros lugares, otras posibilidades de espacio habitable u ocupable. Emerge lo intermedio como lugar, algo que anuncia y exhibe, de manera paradigmática y manifiesta, el monumento de Eisenman en Berlín. ABSTRACT 1. Our research focuses on the study of “in-between spaces or environments” at particular times in contemporary architecture, in a transition period from the end of the 1980’s through to today. We aim to analyse how in-between environments are presented in the architectural object or place and their function or their relationship with the nearby surroundings, from the project through to the experience had. 2. In this research, the in-between concept, understood as an interstitial, border and ambivalent (or multi-purpose) environment or space, is assessed from the viewpoint of etymology, science, thought and art, to conclude in current architecture, with specific exploration of the conception process, of the formal, spatial and functional proposal, together with the perception and other experiences in the architectural place. 3. Firstly, we aim to study and explore the “in-between” concept as regards its features, functions and locations within contemporary culture, revealing its most important cultural background, to then apply it reflexively to important works of architecture. The research focuses on the figural (imprecise) mode of in-between (in allusion to Deleuze’s “figural” approach) whose base metaphors are the translucent, semi-darkness and foam, linked to the current cultural paradigm of complexity (C. Jenks). We then go on to assess the relationships or implications of said figural mode in architectural works by Eisenman, Holl, Tschumi, Ito, Fujimoto, Van Berkel and Bos, and Siza, verifying their operational worth and revealing their meaning and importance today and in this discipline. The backdrop of the study is the in-between concept of Eisenman’s work and it also uses concepts from the philosophy of the limit of Trías as its main underpinnings. 4. In each of the architectural works presented, this imprecise mode is translated into a specific in-between environment or space. They are works in which real and virtual, matricial and objectual, architecture and territory, existing and new, collective and individual, social and intimate, interior and exterior and other uses and functions all intertwine or blend together. They are architectures the geometry of which is not so much determined by bi- or tri-dimensional aspects of the drawing or construction. Through the manipulation of these more or less complex, dynamic and interstitial geometries, these works reflect (or insinuate) the premises of the current Zeitgeist: A change in the scheme of objects to relationships towards a more holistic, transdisciplinary, systemic or complex thought (E. Morin), and a new collective conscience about the reality which announces the crisis of perception, the change in paradigm and new values (F. Capra). Another way of feeling and perceiving the world, places and spaces, which little by little is changing the way of thinking and drawing architecture and hence of interacting with it. 5. The meaning of figural in-between space emerges in the increasingly complex, morphological-spatial and functional qualities of a large part of architecture today. Architecture, geometry and computer technology are more than ever intertwined in a freer way to inquire into other ways of thinking and making places, where the “in-between” spaces we research are a testimony. Architectural space becomes affective and interactive, a figural in-between place, formed by interstitial spatiality which seems to allude to something liquid, where shape is more matrix than configuration, space more spatiality than compartment, its function more versatile and multi-purpose than specific or autonomous, and perplexity, imagination and evocation criss-cross each other, becoming obvious. 6. The architecture of in-between places values not only “flat”, “configuration” and “transparency”, but above all “space” and the “relationship” in its interrelations with users and other contexts. From identity to relationality, from representation to presentation, it is an architecture that proposes “other spaces”, which more than spaces are topographies and interstitial spatialities, of tension, transition, transformation, relation, exchange and interaction. They are real and virtual in-between places, that take in both morphology and topology to conquer new spatialities, aiming to depart from the strict “forming”/”morphing” operation in order to explore “spacing”. They are places that derive both from Deleuze’s indiscernibility zone concept, from Buci-Glucksmann´s image-flow concept, from Sloterdijk’s suspension-between, and from the non-objective space referred to by José Gil, and they are embodied in contemporary architecture as tropes of the interstitial. 7. They are the in-between places in architecture today, of haptic spatiality, more “affective”, generative and interactive, where that in-between environment transforms and is transformed, “affects”, “moves” (it makes us move/act) and evokes other places, other possibilities of habitable or occupiable space. The in-between emerges as a place, which paradigmatically and declaredly, Eisenman´s monument in Berlin announces and exhibits. RESUMO 1. A investigação centra-se no estudo dos “âmbitos ou espaços intermédios” em momentos da arquitectura contemporânea, no período de transição entre os finais dos anos 80 e os nossos dias. Pretende-se analisar como se apresenta o âmbito intermédio no objecto ou lugar arquitectónico e sua função ou relação com o meio envolvente, desde o projecto até à sua repercussão na experiencia vivenciada. 2. O conceito de intermédio entendido como âmbito ou espaço intersticial, fronteiriço e ambivalente (ou multivalente), atravessa na presente investigação o campo da etimologia, da ciência, do pensamento e da arte, para deter-se na arquitectura actual, realizando-se uma indagação concreta no processo de concepção, na proposta formal, espacial e funcional, assim como na percepção e demais experiencias ou vivencias no lugar arquitectónico. 3. Em primeiro lugar, explora-se o conceito de “intermédio” nas suas características, funções e concretizações na cultura contemporânea, detectando os seus antecedentes culturais mais importantes, para em seguida aplicá-lo reflexivamente a obras significativas de arquitectura. A investigação centra-se na modalidade figural (imprecisa) do intermédio (alusão ao figural deleuziano) cujas metáforas base são o translúcido, a penumbra e a espuma, relacionadas com o actual paradigma da complexidade (C. Jencks). Em seguida analisam-se as relações ou implicações da referida modalidade figural em obras de arquitectos como Eisenman, Holl, Tschumi, Ito, Fujimoto, Van Berkel e Bos, e Siza, como modo de comprovar o seu valor operativo e revelar o seu sentido e importância na actualidade e na disciplina. O estudo tem como referencia o conceito de in-between da obra de Eisenman, e utiliza conceitos da filosofia do limite de Trias como alguns dos seus principais fundamentos. 4. Em cada uma das obras de arquitectura apresentadas esta modalidade imprecisa traduz-se num âmbito ou espaço intermédia figural especifico. São obras nas quais real e virtual, matricial e objectual, arquitectura e território, existente e novo, colectivo e individual, social e intimo, interior e exterior, e outros usos e funções se entrelaçam ou fundem. São arquitecturas cuja geometria já não está tão determinada por aspectos bi ou tridimensionais do desenho ou da construção. Através do uso destas geometrias mais ou menos complexas, dinâmicas e intersticiais, estas obras reflectem (ou intuem) as premissas do actual zeitgeist: uma mudança de esquemas de objectos a relações para um pensamento mais holístico, transdisciplinar, sistémico ou complexo (E. Morin) e uma nova consciência colectiva sobre a realidade, que anuncia a crise da percepção, a mudança de paradigma e novos valores (F. Capra). Emerge uma outra forma de sentir e perceber o mundo, os lugares e os espaços, que gradualmente vai alterando o modo de pensar e desenhar a arquitectura, e consequentemente de interagir com ela. 5. O sentido do espaço intermédio figural, emerge nas cada vez mais complexas qualidades morfológico-espaciais e funcionais de uma parte importante da arquitectura actual. Cada vez mais, arquitectura, geometria e tecnologia informática, relacionam-se de um modo mais livre para indagar outras formas de pensar e fazer lugares, onde os espaços intermédios que investigamos são um testemunho. O espaço arquitectónico torna-se afectivo e interactivo, um lugar intermédio figural, formalizado por espacialidades intersticiais que parecem aludir ao estado liquido, onde a forma é mais matriz que configuração, o espaço mais espacialidade que compartimento, a função mais versátil e multivalente que especifica ou autónoma, e a perplexidade, a imaginação e a evocação entrecruzam-se e tornam-se patentes. 6. A arquitectura dos lugares intermédios valoriza não só o “plano”, a “configuração” e a “transparência”, mas sobretudo o” espaço” e a ”relação” nas suas inter-relações com os utentes e restante contextos. Da identidade à relacionalidade, da representação à apresentação, é uma arquitectura que propõe “outros espaços”, que além de espaços são topografias e espacialidades intersticiais, de tensão, transição, transformação, relação, intercambio e interacção. São lugares intermédios reais e virtuais que utilizam tanto a morfologia como a topologia para conquistar novas espacialidades, pretendendo ultrapassar a estrita operação de “forming”/“morphing”/formação para explorar a de “spacing”/espaçamento. São lugares que se apoiam tanto no conceito de zona de indescernibilidade de Deleuze, como na de imagem-fluxo de Buci-Glucksmann como no de suspensão–entre de Sloterdijk ou de espaço-não objectivo que refere José Gil, e se plasmam na arquitectura contemporânea como tropos do intersticial. 7. São os lugares intermédios da arquitectura actual, de espacialidade háptica, mais “afectiva”, generativa e interactiva, onde esse âmbito intermédio transforma e é transformado, “afecta”, ”co-move “(nos faz mover/agir) e evoca outros lugares, outras possibilidades de espaço habitável ou ocupável. Emerge o intermédio como lugar que, paradigmática e manifestamente, o monumento de Eisenmann em Berlim, anuncia e exibe.

Analysis, reliability and optimization of reinforced concrete 2-D structures

In this paper a consistent analysis of reinforced concrete (RC) two-dimensional (2-D) structures,namely slab structures subjected to in-plane and out-plane forces, is presented. By using this method of analysis the well established methodology for dimensioning and verifying RC sections of beam structures is extended to 2-D structures. The validity of the proposed analysis results is checked by comparing them with some published experimental test results. Several examples show some of these proposed analysis features, such as the influence of the reinforcement layout on the service and ultimate behavior of a slab structure and the non straightforward problem of the optimal dimension at a slab point subjected to several loading cases. Also, in these examples, the method applications to design situations as multiple steel families and non orthogonal reinforcement layout are commented.

Two-dimensional isostatic meshes in the finite element method

In a Finite Element (FE) analysis of elastic solids several items are usually considered, namely, type and shape of the elements, number of nodes per element, node positions, FE mesh, total number of degrees of freedom (dot) among others. In this paper a method to improve a given FE mesh used for a particular analysis is described. For the improvement criterion different objective functions have been chosen (Total potential energy and Average quadratic error) and the number of nodes and dof's of the new mesh remain constant and equal to the initial FE mesh. In order to find the mesh producing the minimum of the selected objective function the steepest descent gradient technique has been applied as optimization algorithm. However this efficient technique has the drawback that demands a large computation power. Extensive application of this methodology to different 2-D elasticity problems leads to the conclusion that isometric isostatic meshes (ii-meshes) produce better results than the standard reasonably initial regular meshes used in practice. This conclusion seems to be independent on the objective function used for comparison. These ii-meshes are obtained by placing FE nodes along the isostatic lines, i.e. curves tangent at each point to the principal direction lines of the elastic problem to be solved and they should be regularly spaced in order to build regular elements. That means ii-meshes are usually obtained by iteration, i.e. with the initial FE mesh the elastic analysis is carried out. By using the obtained results of this analysis the net of isostatic lines can be drawn and in a first trial an ii-mesh can be built. This first ii-mesh can be improved, if it necessary, by analyzing again the problem and generate after the FE analysis the new and improved ii-mesh. Typically, after two first tentative ii-meshes it is sufficient to produce good FE results from the elastic analysis. Several example of this procedure are presented.

Membrane-bound state of the colicin E1 channel domain as an extended two-dimensional helical array

Atomic level structures have been determined for the soluble forms of several colicins and toxins, but the structural changes that occur after membrane binding have not been well characterized. Changes occurring in the transition from the soluble to membrane-bound state of the C-terminal 190-residue channel polypeptide of colicin E1 (P190) bound to anionic membranes are described. In the membrane-bound state, the α-helical content increases from 60–64% to 80–90%, with a concomitant increase in the average length of the helical segments from 12 to 16 or 17 residues, close to the length required to span the membrane bilayer in the open channel state. The average distance between helical segments is increased and interhelix interactions are weakened, as shown by a major loss of tertiary structure interactions, decreased efficiency of fluorescence resonance energy transfer from an energy donor on helix V of P190 to an acceptor on helix IX, and decreased resonance energy transfer at higher temperatures, not observed in soluble P190, implying freedom of motion of helical segments. Weaker interactions are also shown by a calorimetric thermal transition of low cooperativity, and the extended nature of the helical array is shown by a 3- to 4-fold increase in the average area subtended per molecule to 4,200 Å2 on the membrane surface. The latter, with analysis of the heat capacity changes, implies the absence of a developed hydrophobic core in the membrane-bound P190. The membrane interfacial layer thus serves to promote formation of a highly helical extended two-dimensional flexible net. The properties of the membrane-bound state of the colicin channel domain (i.e., hydrophobic anchor, lengthened and loosely coupled α-helices, and close association with the membrane interfacial layer) are plausible structural features for the state that is a prerequisite for voltage gating, formation of transmembrane helices, and channel opening.

Crystal structure of 2,5-diketo-d-gluconic acid reductase A complexed with NADPH at 2.1-Å resolution

The three-dimensional structure of Corynebacterium 2,5-diketo-d-gluconic acid reductase A (2,5-DKGR A; EC 1.1.1.-), in complex with cofactor NADPH, has been solved by using x-ray crystallographic data to 2.1-Å resolution. This enzyme catalyzes stereospecific reduction of 2,5-diketo-d-gluconate (2,5-DKG) to 2-keto-l-gulonate. Thus the three-dimensional structure has now been solved for a prokaryotic example of the aldo–keto reductase superfamily. The details of the binding of the NADPH cofactor help to explain why 2,5-DKGR exhibits lower binding affinity for cofactor than the related human aldose reductase does. Furthermore, changes in the local loop structure near the cofactor suggest that 2,5-DKGR will not exhibit the biphasic cofactor binding characteristics observed in aldose reductase. Although the crystal structure does not include substrate, the two ordered water molecules present within the substrate-binding pocket are postulated to provide positional landmarks for the substrate 5-keto and 4-hydroxyl groups. The structural basis for several previously described active-site mutants of 2,5-DKGR A is also proposed. Recent research efforts have described a novel approach to the synthesis of l-ascorbate (vitamin C) by using a genetically engineered microorganism that is capable of synthesizing 2,5-DKG from glucose and subsequently is transformed with the gene for 2,5-DKGR. These modifications create a microorganism capable of direct production of 2-keto-l-gulonate from d-glucose, and the gulonate can subsequently be converted into vitamin C. In economic terms, vitamin C is the single most important specialty chemical manufactured in the world. Understanding the structural determinants of specificity, catalysis, and stability for 2,5-DKGR A is of substantial commercial interest.