Optimal boundary geometry in an elasticity problem: a systematic adjoint approach

p. 509-524In different problems of Elasticity the definition of the optimal geometry of the boundary, according to a given objective function, is an issue of great interest. Finding the shape of a hole in the middle of a plate subjected to an arbitrary loading such that the stresses along the hole minimizes some functional or the optimal middle curved concrete vault for a tunnel along which a uniform minimum compression are two typical examples. In these two examples the objective functional depends on the geometry of the boundary that can be either a curve (in case of 2D problems) or a surface boundary (in 3D problems). Typically, optimization is achieved by means of an iterative process which requires the computation of gradients of the objective function with respect to design variables. Gradients can by computed in a variety of ways, although adjoint methods either continuous or discrete ones are the more efficient ones when they are applied in different technical branches. In this paper the adjoint continuous method is introduced in a systematic way to this type of problems and an illustrative simple example, namely the finding of an optimal shape tunnel vault immersed in a linearly elastic terrain, is presented.Garcia-Palacios, J.; Castro, C.; Samartin, A. (2009). Optimal boundary geometry in an elasticity problem: a systematic adjoint approach. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/654

Synthetic 3D Pap smear nucleus generation

Gómez Aguilar, S. (2010). Synthetic 3D Pap smear nucleus generation. http://hdl.handle.net/10251/10215

Ultracompact electro-optic phase modulator based on III-V-on-silicon microdisk resonator

This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.002379. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.[EN] A novel ultracompact electro-optic phase modulator based on a single 9 ¥ìm-diameter III-V microdisk resonator heterogeneously integrated on and coupled to a nanophotonic waveguide is presented. Modulation is enabled by effective index modification through carrier injection. Proof-of-concept implementation involving binary phase shift keying modulation format is assembled. A power imbalance of ¡-0.6  dB between both symbols and a modulation rate up to 1.8 Gbps are demonstrated without using any special driving technique.The authors gratefully acknowledge the financial support given by the European Seventh Framework Programme through the projects GOSPEL, WADIMOS, and HISTORIC; the Generalitat Valenciana through the Microwave Photonics Excellency Award programme GVA PROMETEO 2008/092; and also the Plan Nacional I+D TEC2011-29120-C05-05 and TEC2008-06145.Lloret Soler, JA.; Kumar, R.; Sales Maicas, S.; Ramos Pascual, F.; Morthier, G.; Mechet, P.; Spuesens, T.... (2012). Ultracompact electro-optic phase modulator based on III-V-on-silicon microdisk resonator. Optics Letters. 37(12):2379-2381. https://doi.org/10.1364/OL.37.002379237923813712Wooten, E. L., Kissa, K. M., Yi-Yan, A., Murphy, E. J., Lafaw, D. A., Hallemeier, P. F., … Bossi, D. E. (2000). A review of lithium niobate modulators for fiber-optic communications systems. IEEE Journal of Selected Topics in Quantum Electronics, 6(1), 69-82. doi:10.1109/2944.826874Li, Y., Wang, R., Bhardwaj, A., Ristic, S., & Bowers, J. (2010). High Linearity InP-Based Phase Modulators Using a Shallow Quantum-Well Design. IEEE Photonics Technology Letters, 22(18), 1340-1342. doi:10.1109/lpt.2010.2054076Png, C. E., Chan, S. P., Lim, S. T., & Reed, G. T. (2004). Optical Phase Modulators for MHz and GHz Modulation in Silicon-On-Insulator (SOI). Journal of Lightwave Technology, 22(6), 1573-1582. doi:10.1109/jlt.2004.827655Chiu, W.-C., Chang, C.-C., Wu, J.-M., Lee, M.-C. M., & Shieh, J.-M. (2011). Optical phase modulators using deformable waveguides actuated by micro-electro-mechanical systems. Optics Letters, 36(7), 1089. doi:10.1364/ol.36.001089Lin, Y.-H., & Tsou, Y.-S. (2011). A polarization independent liquid crystal phase modulation adopting surface pinning effect of polymer dispersed liquid crystals. Journal of Applied Physics, 110(11), 114516. doi:10.1063/1.3666053Kim, S.-K., Yuan, W., Geary, K., Hung, Y.-C., Fetterman, H. R., Lee, D.-G., … Oh, I. (2005). Electro-optic phase modulator using metal-defined polymer optical waveguide. Applied Physics Letters, 87(1), 011107. doi:10.1063/1.1991998Soref, R., & Bennett, B. (1987). Electrooptical effects in silicon. IEEE Journal of Quantum Electronics, 23(1), 123-129. doi:10.1109/jqe.1987.1073206Espinola, R. L., Tsai, M. C., Yardley, J. T., & Osgood, R. M. (2003). Fast and low-power thermooptic switch on thin silicon-on-insulator. IEEE Photonics Technology Letters, 15(10), 1366-1368. doi:10.1109/lpt.2003.818246Feng, N.-N., Liao, S., Feng, D., Dong, P., Zheng, D., Liang, H., … Asghari, M. (2010). High speed carrier-depletion modulators with 14V-cm V_πL integrated on 025μm silicon-on-insulator waveguides. Optics Express, 18(8), 7994. doi:10.1364/oe.18.007994Xu, Q., Schmidt, B., Pradhan, S., & Lipson, M. (2005). Micrometre-scale silicon electro-optic modulator. Nature, 435(7040), 325-327. doi:10.1038/nature03569Xu, Q., Manipatruni, S., Schmidt, B., Shakya, J., & Lipson, M. (2007). 125 Gbit/s carrier-injection-based silicon micro-ring silicon modulators. Optics Express, 15(2), 430. doi:10.1364/oe.15.000430Kuo, Y., Chen, H.-W., & Bowers, J. E. (2008). High speed hybrid silicon evanescent electroabsorption modulator. Optics Express, 16(13), 9936. doi:10.1364/oe.16.009936Hui-Wen Chen, Ying-Hao Kuo, & Bowers, J. E. (2008). A Hybrid Silicon–AlGaInAs Phase Modulator. IEEE Photonics Technology Letters, 20(23), 1920-1922. doi:10.1109/lpt.2008.2004790Van Campenhout, J., Romeo, P. R., Van Thourhout, D., Seassal, C., Regreny, P., Di Cioccio, L., … Baets, R. (2008). Design and Optimization of Electrically Injected InP-Based Microdisk Lasers Integrated on and Coupled to a SOI Waveguide Circuit. Journal of Lightwave Technology, 26(1), 52-63. doi:10.1109/jlt.2007.912107Van Thourhout, D., Spuesens, T., Selvaraja, S. K., Liu, L., Roelkens, G., Kumar, R., … Grenouillet, L. (2010). Nanophotonic Devices for Optical Interconnect. IEEE Journal of Selected Topics in Quantum Electronics, 16(5), 1363-1375. doi:10.1109/jstqe.2010.2040711Liu, L., Van Campenhout, J., Roelkens, G., Soref, R. A., Van Thourhout, D., Rojo-Romeo, P., … Baets, R. (2008). Carrier-injection-based electro-optic modulator on silicon-on-insulator with a heterogeneously integrated III-V microdisk cavity. Optics Letters, 33(21), 2518. doi:10.1364/ol.33.00251

Randomness in topological models

p. 914-925There are two aspects of randomness in topological models. In the first one, topological idealization of random patterns found in the Nature can be regarded as planar representations of three-dimensional lattices and thus reconstructed in the space. Another aspect of randomness is related to graphs in which some properties are determined in a random way. For example, combinatorial properties of graphs: number of vertices, number of edges, and connections between them can be regarded as events in the defined probability space. Random-graph theory deals with a question: at what connection probability a particular property reveals. Combination of probabilistic description of planar graphs and their spatial reconstruction creates new opportunities in structural form-finding, especially in the inceptive, the most creative, stage.Tarczewski, R.; Bober, W. (2010). Randomness in topological models. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/695

Implementation of a Human-Computer Interface for Computer Assisted Translation and Handwritten Text Recognition

A human-computer interface is developed to provide services of computer assisted machine translation (CAT) and computer assisted transcription of handwritten text images (CATTI). The back-end machine translation (MT) and handwritten text recognition (HTR) systems are provided by the Pattern Recognition and Human Language Technology (PRHLT) research group. The idea is to provide users with easy to use tools to convert interactive translation and transcription feasible tasks. The assisted service is provided by remote servers with CAT or CATTI capabilities. The interface supplies the user with tools for efficient local edition: deletion, insertion and substitution.Ocampo Sepúlveda, JC. (2009). Implementation of a Human-Computer Interface for Computer Assisted Translation and Handwritten Text Recognition. http://hdl.handle.net/10251/1431

About the freedom of free forms

p. 907-913This paper deals with the arrival of freedom at the world of structures giving birth a new generation of forms: the free forms. Its purpose is to analyze, to discuss and to comment critically this singular fact as well as their implications on the designers' task. It is more a philosophical than a technical paper. For centuries man has imagined new forms for their structures but he has not been always able to analyze and to build them. Before the arrival of the electronic calculus, the representation and analysis of structural forms could be limited to those ones belonging to the Euclidean Geometry. The computers broke those limitations and they gave wide freedom to the designers to conceive a new generation of forms; these new forms were called "free forms". Nowadays any form imagined can be represented, it can be analyzed and it can be built. Nevertheless not any imagined form can become a structural free form. Perhaps it could be a beautiful sculptural form, but not necessarily a structural one. For being a structural form, the inescapable laws of the mechanics must be satisfied. Moreover a structural free form can become an architectural free form just only when aesthetical, functional, environmental and social requirements, among others, are accomplished. Freedom has widened the horizons of creativity for the designers' task. Simultaneously new responsibilities have come altogether with this freedom. Today free form designers face permanent challenges; designers must be familiar with the menus of new and multiple tools created by the modern technology and they must be trained to make the right use of them. They must handle those wide menus in order to select the most appropriated options to generate, to model and to analyze the new free forms. At the same time they must select the most appropriated new materials and techniques to build these free forms. Finally, designer must be fully conscious of the high impact of their engineering and architectural works on the people and physical environment without forgetting their commitment to the society.Andres, OA. (2010). About the freedom of free forms. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/695

Comportamiento mecánico de cerramientos de fábrica de ladrillo no portante

Las fachadas de fábrica de ladrillo no portantes son uno de los cerramientos más utilizados en la arquitectura residencial actual en España. Se trata de una tipología con siglos de historia pero que todavía sigue vigente debido a la tradición de la industria cerámica y su facilidad de ejecución y mantenimiento. Este tipo de cerramiento se construye tradicionalmente en España apoyando su hoja exterior en los forjados del edificio, lo cual conlleva problemas de estabilidad de esta hoja, problemas de aislamiento térmico y de estanquidad frente al agua. Se han encontrado multitud de edificios con estas lesiones clasificándolas en función de su origen. Para suplir estos inconvenientes surge la fachada autoportante, heredera del cavity wall, que se separa de los forjados dejando una cámara de aire continua. Esta fachada transmite las cargas verticales, debidas al peso propio, directamente a cimentación, y transmite las cargas horizontales, debidas al viento, a la estructura del edificio mediante anclajes metálicos. El objetivo de esta tesis es realizar un estudio sobre el comportamiento mecánico de los cerramientos de ladrillo para proponer mejoras que eviten los problemas de estabilidad y resistencia. Para ello se estudia la normativa actual, se analizan los modelos de comportamiento y ensayos realizados. Después de analizar los modelos de comportamiento de la fábrica existentes se emplea el método de los elementos finitos. Con este modelo se estudia el comportamiento del cerramiento, tanto del cerramiento tradicional como del cerramiento autoportante continuo por delante de la estructura. Se realiza una investigación sobre su comportamiento frente a acciones horizontales observando la influencia del tamaño de los huecos, la geometría de los anclajes, el efecto de cargas verticales y la posible colaboración de la hoja interior. Este método permite prever la aparición de fisuras con objeto de evitarlas mediante el refuerzo de la fábrica, comprobando además la eficacia de los refuerzos. Una vez realizado el estudio, se proponen soluciones constructivas para ejecutar los cerramientos resolviendo los requisitos de estabilidad y resistencia, evitando la aparición de fisuras, y teniendo en cuenta otros aspectos como el aislamiento y la impermeabilización.Cubel Arjona, FJ. (2013). Comportamiento mecánico de cerramientos de fábrica de ladrillo no portante [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/2885

Dried chicory root (Cichorium intybus L.) as a natural fructan source in rabbit diet: effects on growth performance, digestion and caecal and carcass traits

[EN] Three experimental diets were formulated including (per kg) 100 g oats (control diet), 50 g chicory root (Chicory 5 diet) or 100 g chicory root (Chicory 10 diet) at the expense of oats. The diets differed with respect to starch and fructan contents. In the performance trial, 120 Hyplus rabbits were randomly allocated to three groups (two rabbits per cage) and fed one of the three experimental diets between 31 and 73 days of age. At the end of the trial period, 20 rabbits per treatment were slaughtered and used for evaluation of carcass traits. In addition, the coefficients of total tract apparent digestibility (CTTAD) of the diets and caecal traits were determined from 45 to 49 days of age in 10 rabbits per treatment. The diets did not differ significantly in terms of weight gain, feed intake, feed conversion ratio, health status or carcass traits of rabbits. The CTTADs of crude protein (P=0.041) and ether extract (P=0.006) were lower in rabbits fed the Chicory 10 diet than in rabbits fed the control diet. The CTTAD of starch (P<0.001) was lower, whereas that of fructans (P<0.001) higher, in rabbits fed the diets based on chicory root. The caecum weight (P=0.037), the weight of its contents (P=0.025) and the lactic acid (P=0.028) concentration were higher in rabbits fed the Chicory 10 diet than in control rabbits. On the contrary, rabbits fed with the chicory diets showed lower caecal pH (P=0.048) than rabbits fed the control diet. There was a tendency towards a lower caecal dry matter content and higher total VFA concentration in rabbits fed the chicory diets. It may be concluded that chicory root can serve as a natural source of inulin-type fructans in rabbit feed. Diet supplementation with 10% dried chicory root beneficially affected the caecal fermentative activity in the rabbits, without significant reductions in the nutritive value of the diet, growth performance or carcass quality.Financial support for this study was provided by the institutional research project MZE 0002701404Volek, Z.; Marounek, M. (2011). Dried chicory root (Cichorium intybus L.) as a natural fructan source in rabbit diet: effects on growth performance, digestion and caecal and carcass traits. World Rabbit Science. 19(3):143-150. https://doi.org/10.4995/wrs.2011.85014315019

Research on the combination of water and membranes as a structural building material

p. 3024-3033The aim of this paper is to investigate the combination of water and membranes for temporary architectural applications. Water as a construction material, can be useful for three different purposes: first of all, thanks to its thermal mass, it can be used as a medium for cooling down or heating up buildings (Pronk et al [6]); secondly water is uncompressible and, in combination with air, can be used as part of a structural element; thirdly the mass of water could work as a sound barrier so it can be used as sound insulation material (Rodrigues and Coutinho [7]). This paper shows the result of the structural behaviour. There is another paper about sound insulation properties of water. The research in both structural and sound insulation fields was carried out in the laboratories of Technische Universiteit Eindhoven, The Netherlands. The prototype is a "waterbeam" of 2 m span. Starting from the Tensairity(R) technology principle (Luchsinger et al [8]) developed by Airlight, the purpose of this experiment is to replace the iron struts with a second membrane chamber filled with water. Water works well in compression and air prevents buckling. The result is a rigid structural element made by non-rigid material (water, air, membranes and cables) with a significant reduction of weight and cost of transportation compared to the traditional iron beam but also compared with the Tensairity(R) system. Different bending tests were carried out. In each test, the two chambers of the beam were filled with air or water to understand the material behaviour.The comparison between the results shows that water works slightly better than air (stiffness increase of a range of 8-13% in the elements filled with water). Water application in architecture showed promising results. Further investigation (pure compression tests on columns, multiple layers sound barrier) should be carried out. These results could give architects new design opportunities and solutions concerning temporary buildings and moveable architecture. Moreover the company and building construction industry could develop innovative structural elements and new insulation components.Pronk, A.; Maffei, R.; Martin, H. (2009). Research on the combination of water and membranes as a structural building material. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/670

Calibration of a wide angle stereoscopic system

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.003064. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Inaccuracies in the calibration of a stereoscopic system appear with errors in point correspondences between both images and inexact points localization in each image. Errors increase if the stereoscopic system is composed of wide angle lens cameras. We propose a technique where detected points in both images are corrected before estimating the fundamental matrix and the lens distortion models. Since points are corrected first, errors in point correspondences and point localization are avoided. To correct point location in both images, geometrical and epipolar constraints are imposed in a nonlinear minimization problem. Geometrical constraints define the point localization in relation to its neighbors in the same image, and eipolar constraints represent the location of one point referred to its corresponding point in the other image. © 2011 Optical Society of America.Ricolfe Viala, C.; Sánchez Salmerón, AJ.; Martínez Berti, E. (2011). Calibration of a wide angle stereoscopic system. Optics Letters. 36(16):3064-3067. doi:10.1364/OL.36.003064306430673616Zhang, Z., Ma, H., Guo, T., Zhang, S., & Chen, J. (2011). Simple, flexible calibration of phase calculation-based three-dimensional imaging system. Optics Letters, 36(7), 1257. doi:10.1364/ol.36.001257Longuet-Higgins, H. C. (1981). A computer algorithm for reconstructing a scene from two projections. Nature, 293(5828), 133-135. doi:10.1038/293133a0Ricolfe-Viala, C., & Sanchez-Salmeron, A.-J. (2010). Lens distortion models evaluation. Applied Optics, 49(30), 5914. doi:10.1364/ao.49.005914Armangué, X., & Salvi, J. (2003). Overall view regarding fundamental matrix estimation. Image and Vision Computing, 21(2), 205-220. doi:10.1016/s0262-8856(02)00154-3Devernay, F., & Faugeras, O. (2001). Straight lines have to be straight. Machine Vision and Applications, 13(1), 14-24. doi:10.1007/pl0001326