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Brazil has as a main source for production of electricity the dams using water to drive the turbines and as a secondary source are used the thermoelectric power plants that use fuel oil for electric power production. Both generate a large environmental impact, due to the fact of the dams need huge areas for its construction, which often leads to destruction of important ecosystems in the region where it will be installed the hydroelectric plant, besides the fact that they need the rainfall cycle so that the dams have the operating capacity, while the thermoelectric power plants burn fossil fuels thus increasing emissions of CO2 to the atmosphere. An alternative to the solution of the problems mentioned above is the use of renewable sources of energy, with emphasis on this work. Solar energy can be divided into two parts: thermal and photovoltaic. This work it is focused on thermal use of solar energy, with a Fresnel-type solar concentrator to heat water, which will trigger a cooling system environment with the use of desiccant rotors. The choice of type Fresnel collector gave the field of development of this hub is still in constant growth and by the fact that even occupy a relatively small area when compared to other solar thermal concentrators, in addition to its construction be simple and low cost when again compared to other solar concentrators. O Brasil tem como fonte principal para produção de energia elétrica as hidrelétricas que utilizam água para movimentar as turbinas e como fonte complementar são utilizadas as termoelétricas que usam óleo combustível para produção de energia elétrica. Ambas geram um grande impacto ambiental, devido ao fato das hidrelétricas necessitarem de enormes áreas para a construção das represas, o que muitas vezes acarreta na destruição de ecossistemas importantes para a região onde irá ser instalada a hidrelétrica, além do fato que elas necessitam do ciclo das chuvas para que as represas possuam capacidade de operação, enquanto que as termoelétricas queimam combustíveis fosseis, aumentando assim as emissões de CO2 para a atmosfera. Uma alternativa para a solução dos problemas citados anteriormente é a utilização de fontes renováveis de energia, dando ênfase neste trabalho a energia solar. A energia solar pode ser dividida em duas vertentes: térmica e fotovoltaica. Este trabalho está voltado para a utilização térmica da energia solar, através da utilização de um concentrador solar do tipo Fresnel para o aquecimento de água, a qual irá acionar um sistema de refrigeração de ambientes com a utilização de rotores dessecantes. A escolha do coletor do tipo Fresnel se deu pelo campo de desenvolvimento deste concentrador estar ainda em constante crescimento e pelo fato do mesmo ocupar uma área relativamente pequena quando comparado com outros concentradores solares térmicos, além de sua construção ser simples e de baixo custo quando novamente comparada a outros concentradores solares.

Photonic crystals for LED

Inspirándose en trabajos anteriores desarrollados por la Agencia Internacional de la Energía, que determinan las necesidades de calor de proceso en la industria y el potencial de aplicación de la energía solar de concentración, este informe realiza un estudio del estado actual de los sistemas solares de media temperatura, y sus aplicaciones potenciales en diferentes sectores industriales y sector servicios, conectados a la red o en aplicaciones distribuidas. Se realiza un análisis de los mercados solares de pequeña escala, y se comparan con aquellos donde dominan captadores solares de gran tamaño, especialmente diseñados para el sector termoeléctrico. Por otra parte, este informe analiza los distintos tipos de módulos solares de media temperatura, y las soluciones técnicas aplicadas en cada uno de ellos, para posteriormente realizar una valoración comparativa de las distintas tecnologías de concentración. Se describe el modelado óptico y térmico de estos sistemas, y se investigan aspectos como los nuevos diseños de espejos finos de primera superficie, basados en múltiples películas de polímeros ligeros y revestimientos de plata, aluminio y óxidos reflectantes. Igualmente, se investigan los nuevos desarrollos de estructuras específicamente diseñadas para módulos de pequeño tamaño, las cuales deben ser simples, ligeras y baratas, para que estos sistemas puedan ser competitivos frente a otros tipos de fuentes de energía. Se abordan otros aspectos, como los recubrimientos selectivos, los sistemas de seguimiento y los requerimientos de instalación. Finalmente se realiza un análisis de la productividad de estos sistemas y del coste de cada tipo de módulo solar. Inspired by previous work carried out by the International Energy Agency (IEA), which determined the needs of process heat in industry and the potential application of solar energy concentration, this report makes a study of the current state of solar systems of medium temperature, and its potential applications in various industries and service sector, for on-grid or off-grid applications. An analysis of small scale solar markets is performed, and compared with those on which large solar collectors dominate, specially designed for the thermoelectric sector. Moreover, this report analyzes the different types of solar modules medium temperature (CSP), and technical solutions applied in each one, in order to make a comparative assessment of the various solar concentration technologies. An optical and thermal modeling of such systems are described, and aspects such as new designs of first surface thin mirrors, based on multiple lightweight polymer films and reflective silvered or aluminized coatings, and reflective and protective oxides front films are also investigated. Similarly, this research focuses on new developments of structures specifically designed for small modules, which should be simple, light and cheap, so that these systems could be competitive with other energy sources. Other aspects, such as selective coatings, tracking systems and installation requirements are addressed as well. Finally, an analysis of the thermal efficiency of these systems and the cost of each type of solar module has been made. Ingeniería Industrial

Desde un grupo de trabajo en el Instituto Superior Técnico de Lisboa queremos desarrollar un equipo que sea capaz de transmitir luz solar por medio de fibra óptica. Este campo está aún por explorar y nuestro principal objetivo es, mediante el uso de una lente de Fresnel, conseguir transmitir la radiación solar desde un punto de recepción hasta otro punto de utilización. Nos podemos preguntar de qué nos va a servir realizar esta transmisión de radiación. Pues bien, podemos usar este recurso como fuente de energía para fundición, usar la radiación solar para realizar una catálisis química en un reactor o, simplemente, para iluminación. Este es un gran proyecto y mi cometido en él es el de desarrollar una especie de persiana que, mediante el sistema de control oportuno, se encargará de regular la intensidad luminosa que va a recibir nuestra lente de Fresnel. Realizamos esta regulación porque las lentes de Fresnel no funcionan como las placas solares que almacenan el exceso de radiación en baterías, sino que tenemos que disipar la radiación electromagnética que no nos interesa para conseguir, en el punto de utilización, que nuestra fibra óptica transmita siempre la misma cantidad de luz solar

Durr is one of the world's leading suppliers of products, systems and services, mainly for automobile manufacturing. The range of products and services covers important stages of vehicle production. As a systems supplier, Durr plans and builds complete paint shops and final assembly facilities. Industrial Solar – formerly known as Mirroxx – is the leading manufacturer of Fresnel process heat collectors and can look back on seven years operating experience with its systems. Automotive industry is under considerable strain to make their products more environmentally sound. Not only the cars themselves, but also the whole value chain has to become more sustainable. One production process, which contributes a significant share to the carbon footprint of a car, is the curing of a car's paint. As the temperatures in the convection ovens are up to 200 °C the application of market available flatplate or vacuum tube collectors was not an option, as these collector types cannot provide such high temperatures. Also the thermal power needed for a convection oven is well above the typical power range of solar collectors, which were originally designed for domestic hot water applications. A pilot system of a solar driven convection oven has been installed on the Durr Campus in Bietigheim-Bissingen near Stuttgart/Germany. An Industrial Solar Fresnel collector consisting of six modules with a total aperture area of 132 m2 heats pressurized water to an outlet temperature of 180 °C. A fossil fired backup boiler complements the solar thermal system to meet the thermal power demand of the convection oven. Finally the heat is dissipated in the convection oven via a pressurized water – air heat exchanger.

A century ago Cosmic Rays were discovered by Victor Hess during one of the very first scientific balloon flights. Ever since, Cosmic Ray physics and stratospheric balloons have shared a common history – either through genuine discoveries or by using balloon platforms as technology test beds for new satellite missions. This thesis, carried out within the JEM-EUSO collaboration, is about such a pathfinder balloon mission. Our ultimate science goal is the study of Ultra-High Energy Cosmic Rays (UHECR), the most energetic particles known in the Universe. Having macroscopic energies of over 10^20 eV, UHECRs are of yet unknown cosmic origin and are extremely rare. They penetrate our atmosphere at a rate of about one event per km2 and century, producing energetic atmospheric air showers, detectable through the ultraviolet fluorescence light they emit. The technique that our collaboration proposes for their detection consists of a spaceborne observatory, JEM-EUSO. Its objective is to monitor a very large volume of the Earth’s nighttime atmosphere from above, recording a significant sample of ultraviolet light tracks initiated by UHECRs.In order to demonstrate the technologies and methods featured in the future space instrument, the EUSO-Balloon pathfinder has been developed by the JEM-EUSO collaboration. On August 25, 2014, EUSO-Balloon was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. From a float altitude of 38 km, the instrument operated during the entire astronomical night, observing UV-light from a variety of groundcovers and from hundreds of simulated air showers, produced by flashers and a laser during a two-hour helicopter under-flight. These results have been made possible by the restitution of the instruments attitude carried out at IRAP, i.e. an exhaustive analysis of the flight data from various attitude sensors on board of the balloon gondola.Also, a precise understanding of the Fresnel optics was required to analyze the data of the first EUSO-balloon flight. The all new optical system, integrated and tested at IRAP, has been characterized during two measurement campaigns. To test this large refractive system, a new test method has been developed. The optics performance, i.e. the efficiency and point spread function, came as something of a surprise, since none of the numerical models had predicted the observed behavior. These measurements are used in the analysis of the flight data and for the deep understanding of these brand-new Fresnel optics, key element in the design of the JEM-EUSO instrument.; Les rayons cosmiques ont été découverts il y a un siècle par Victor Hess à bord d'un vol scientifique en ballon. La physique des rayons cosmiques et les ballons stratosphériques ont partagé depuis lors une histoire commune, que ce soit pour d'authentiques découvertes ou en utilisant les ballons comme plateformes de test technologique pour de nouvelles missions satellites.Cette thèse, développée au sein de la collaboration JEM-EUSO, traite d'un démonstrateur en ballon stratosphérique. Notre but scientifique final est l'étude des Rayons Cosmiques de Ultra-Haute Energie (RCUHE), les particules les plus énergétiques connues dans l'Univers. Les RCUHES ont des énergies macroscopiques de plus de 10^20eV mais étant extrêmement rares, leurs origines sont encore inconnues. Ces derniers pénètrent notre atmosphère à une fréquence de un par km2 par siècle, produisant une gerbe atmosphérique géante, détectable notamment par la lumière de fluorescence ultraviolette qu'elle émet. Le principe de détection proposé par notre collaboration consiste dans l'utilisation d'un observatoire spatial, JEM-EUSO. Son objectif est d'observer un très grand volume d'atmosphère afin d'enregistrer un nombre significatif des événements ultra-violet de fluorescence initiés par les RCUHEs.Le démonstrateur EUSO-Ballon a été développé par la collaboration JEM-EUSO dans le but de démontrer les technologies et méthodes utilisées par le futur instrument spatial. Le 25 août 2014, EUSO-Ballon a été lâché depuis la base de ballons stratosphériques de Timmins (Ontario, Canada) par la division ballon du CNES. L'instrument a fonctionné pendant toute une nuit astronomique, observant depuis 38km d'altitude la lumière UV provenant de divers types de sols et de centaines de gerbes atmosphériques simulées. Ces dernières ont été produites par des flashers et un laser embarqués dans un hélicoptère volant sous EUSO-Ballon pendant deux heures. Ces résultats ont été rendus possibles par la restitution de l'attitude de l'instrument effectuée à l'IRAP, c'est-à-dire une analyse exhaustive des données du vol des différents appareils de mesure d'attitude de la nacelle du ballon.Une caractérisation précise de chaque sous-système était aussi indispensable à l'exploitation des données du vol. Le système optique innovant, composé de deux grandes lentilles de Fresnel, a été intégré et entièrement testé à l'IRAP. Face au large système réfractif de l'instrument, une nouvelle méthodologie de test a été développée. Les performances de l'optique, efficacité et spot focal, ont ainsi été mesurées et se sont révélées étonnamment différentes des prédictions des modèles numériques. Ces mesures sont utilisées pour l’analyse des données du premier vol et pour mieux comprendre le comportement de ces toutes nouvelles optiques, éléments clés dans la conception de l'instrument JEM-EUSO.

A century ago Cosmic Rays were discovered by Victor Hess during one of the very first scientific balloon flights. Ever since, Cosmic Ray physics and stratospheric balloons have shared a common history - either through genuine discoveries or by using balloon platforms as technology test beds for new satellite missions. This thesis, carried out within the JEM-EUSO collaboration, is about such a pathfinder balloon mission. Our ultimate science goal is the study of Ultra-High Energy Cosmic Rays (UHECR), the most energetic particles known in the Universe. Having macroscopic energies of over 10^20 eV, UHECRs are of yet unknown cosmic origin and are extremely rare. They penetrate our atmosphere at a rate of about one event per km2 and century, producing energetic atmospheric air showers, detectable through the ultraviolet fluorescence light they emit. The technique that our collaboration proposes for their detection consists of a spaceborne observatory, JEM-EUSO. Its objective is to monitor a very large volume of the Earth's nighttime atmosphere from above, recording a significant sample of ultraviolet light tracks initiated by UHECRs. In order to demonstrate the technologies and methods featured in the future space instrument, the EUSO-Balloon pathfinder has been developed by the JEM-EUSO collaboration. On August 25, 2014, EUSO-Balloon was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. From a float altitude of 38 km, the instrument operated during the entire astronomical night, observing UV-light from a variety of groundcovers and from hundreds of simulated air showers, produced by flashers and a laser during a two-hour helicopter under-flight. These results have been made possible by the restitution of the instruments attitude carried out at IRAP, i.e. an exhaustive analysis of the flight data from various attitude sensors on board of the balloon gondola. Also, a precise understanding of the Fresnel optics was required to analyze the data of the first EUSO-balloon flight. The all new optical system, integrated and tested at IRAP, has been characterized during two measurement campaigns. To test this large refractive system, a new test method has been developed. The optics performance, i.e. the efficiency and point spread function, came as something of a surprise, since none of the numerical models had predicted the observed behavior. These measurements are used in the analysis of the flight data and for the deep understanding of these brand-new Fresnel optics, key element in the design of the JEM-EUSO instrument.; Les rayons cosmiques ont été découverts il y a un siècle par Victor Hess à bord d'un vol scientifique en ballon. La physique des rayons cosmiques et les ballons stratosphériques ont partagé depuis lors une histoire commune, que ce soit pour d'authentiques découvertes ou en utilisant les ballons comme plateformes de test technologique pour de nouvelles missions satellites. Cette thèse, développée au sein de la collaboration JEM-EUSO, traite d'un démonstrateur en ballon stratosphérique. Notre but scientifique final est l'étude des Rayons Cosmiques de Ultra-Haute Energie (RCUHE), les particules les plus énergétiques connues dans l'Univers. Les RCUHES ont des énergies macroscopiques de plus de 10^20eV mais étant extrêmement rares, leurs origines sont encore inconnues. Ces derniers pénètrent notre atmosphère à une fréquence de un par km2 par siècle, produisant une gerbe atmosphérique géante, détectable notamment par la lumière de fluorescence ultraviolette qu'elle émet. Le principe de détection proposé par notre collaboration consiste dans l'utilisation d'un observatoire spatial, JEM-EUSO. Son objectif est d'observer un très grand volume d'atmosphère afin d'enregistrer un nombre significatif des événements ultra-violet de fluorescence initiés par les RCUHEs. Le démonstrateur EUSO-Ballon a été développé par la collaboration JEM-EUSO dans le but de démontrer les technologies et méthodes utilisées par le futur instrument spatial. Le 25 août 2014, EUSO-Ballon a été lâché depuis la base de ballons stratosphériques de Timmins (Ontario, Canada) par la division ballon du CNES. L'instrument a fonctionné pendant toute une nuit astronomique, observant depuis 38km d'altitude la lumière UV provenant de divers types de sols et de centaines de gerbes atmosphériques simulées. Ces dernières ont été produites par des flashers et un laser embarqués dans un hélicoptère volant sous EUSO-Ballon pendant deux heures. Ces résultats ont été rendus possibles par la restitution de l'attitude de l'instrument effectuée à l'IRAP, c'est-à-dire une analyse exhaustive des données du vol des différents appareils de mesure d'attitude de la nacelle du ballon. Une caractérisation précise de chaque sous-système était aussi indispensable à l'exploitation des données du vol. Le système optique innovant, composé de deux grandes lentilles de Fresnel, a été intégré et entièrement testé à l'IRAP. Face au large système réfractif de l'instrument, une nouvelle méthodologie de test a été développée. Les performances de l'optique, efficacité et spot focal, ont ainsi été mesurées et se sont révélées étonnamment différentes des prédictions des modèles numériques. Ces mesures sont utilisées pour l'analyse des données du premier vol et pour mieux comprendre le comportement de ces toutes nouvelles optiques, éléments clés dans la conception de l'instrument JEM-EUSO.

Se presenta en el siguiente trabajo la caracterización de los parámetros de funcionamiento de un motor a vapor a efectos de conocer la capacidad de producción de potencia y torque, para ser acoplado a la línea de vapor generado en el sistema Fresnel Lineal montado en San Carlos, Salta. Los ensayos fueron realizados en la planta piloto de la Facultad de Ingeniería (FI) de la Universidad Nacional de Salta (UNSa), donde se empleó una caldera-generador de vapor. Se ensayó el motor desde el arranque hasta régimen nominal, pasando por diversos escalones de r.p.m. y se tomaron medidas de presiones mínimas y máximas, temperatura de vapor de admisión y ambiente, régimen de r.p.m. y caudal de vapor. Las curvas de potencia y torque presentadas concuerdan con la literatura correspondiente a las maquinas térmicas., Characterizing operating parameters of a steam engine, in order to determinate its capacity of power and couple generating to be coupled to steam line source generated by the Fresnel Linear System mounted in San Carlos, Salta is showed. The tests were conducted in the Faculty of Engineering (FI) of the National University of Salta (UNSa), where we used a boiler – steam generator plant. The engine was tested from startup to nominal regime, trough different steps of rotational speeds and measures of minimum and maximum pressure, inlet steam temperature and environment, regime of speeds and steam flow were took. Power and couple curves presented are consistent with the relevant literature to thermal machines., Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES)

This paper focuses on unresolved or poorly documented issues pertaining to Fresnel's scalar diffraction theory and its modifications. In Sec. 2 it is pointed out that all thermal sources used in practice are finite in size and errors can result from insufficient coherence of the optical field. A quarter-wave criterion is applied to show how such errors can be avoided by placing the source at a large distance from the aperture plane, and it is found that in many cases it may be necessary to use collimated light as on the source side of a Fraunhofer experiment. If these precautions are not taken the theory of partial coherence may have to be used for the computations. In Sec. 3 it is recalled that for near-zone computations the Kirchhoff or Rayleigh-Sommerfeld integrals are applicable, but fail to correctly describe the energy flux across the aperture plane because they are not continuously differentiable with respect to the assumed geometrical field on the source side. This is remedied by formulating an improved theory in which the field on either side of a semi-reflecting screen is expressed as the superposition of mutually incoherent components which propagate in the opposite directions of the incident and reflected light. These components are defined as linear combinations of the Rayleigh-Sommerfeld integrals, so that they are rigorous solutions of the wave equation as well as continuously differentiable in the aperture plane. Algorithms for using the new theory for computing the diffraction patterns of circular apertures and slits at arbitrary distances z from either side of the aperture (down to z = ± 0.0003 λ) are presented, and numerical examples of the results are given. These results show that the incident geometrical field is modulated by diffraction before it reaches the aperture plane while the reflected field is spilled into the dark space. At distances from the aperture which are large compared to the wavelength λ these field expressions are reduced to the usual ones specified by Fresnel's theory. In the specific case of a diffracting half plane the numerical results obtained were practically the same as those given by Sommerfeld's rigorous theory. The modified theory developed in this paper is based on the explicit assumption that the scalar theory of light cannot explain plolarization effects. This premise is justified in Sec. 4, where it is shown that previous attempts to do so have produced dubious results.

To develop concentrating photovoltaic systems for building integration applications, two optical devices are proposed. The concentrators are based in stationary linear Fresnel lenses and secondary CPC. The moving focal area is ten times smaller than the Fresnel lens aperture. Concentrator characteristics are studied in detail: shadowing effect, placement of the focal area and optical concentration efficiency. The main contribution of this paper is the three-dimensional optical analysis of the non-imaging concentrating systems. In terms of solar radiation, photovoltaic moving modules placed in the focal area of stationary concentrators are compared with simply fixed photovoltaic modules. In favourable weather locations, the beam radiation incident on the concentrating modules would be a large percentage, more than 50%, of the global radiation received by the fixed photovoltaic devices.

A unique Fresnel prototype is currently running in France. It is composed of a 1000 m 2 solar field, a thermocline thermal storage and an Organic Rankine Cycle (ORC). This CSP plant is perfectly suited to test the three main parts of a solar power plant (ie. solar field, storage and turbine). More than two years of experience is achieved and the paper aims at presenting some results about this operating period. It shows that this kind of technology is very versatile. Automation experiences along with thermocline behavior are discussed. Electricity production using the storage capacity is also presented. This experimental tool will be upgraded with water chilled production and desalination. The perspective is the optimization of the whole system for MW scale installations.

La difracción es el fenómeno que ocurre cuando las ondas se propagan y se encuentran con un obstáculo. Se trata de un aspecto fundamental en Óptica, ya que todos los sistemas ópticos están afectados por la difracción, produciendo en general dos efectos desfavorables. Por un lado produce un ensanchamiento de los haces a lo largo de su propagación. Por otro lado, limita el tamaño mínimo posible del haz al ser enfocado. A lo largo de los años, ha habido multitud de intentos de mejorar o reducir estos inconvenientes tanto en la difracción de campo lejano como también en la de campo cercano. En este artículo nos centraremos en el estudio de los límites impuestos por la difracción de campo lejano, y especialmente en el segundo problema que explicábamos antes: cómo mejorar el poder resolutivo o de una manera más general, la respuesta tridimensional de un sistema, ya que nosotros estamos especialmente interesados en sistemas ópticos como formadores de imagen. En segundo lugar mostraremos el uso de los moduladores espaciales de luz basados en cristal líquido (LC-SLM) para crear filtros de transmisión y/o fase no uniforme y también la generación de elementos ópticos difractivos orientados a formación de imagen. Mostraremos resultados experimentales que cubren un amplio abanico de posibilidades ofrecidas por el uso conjunto de los filtros mencionados y de los dispositivos LC-SLM.

This paper describes design of daylight collectors using multiple Fresnel lenses, each facing the sun for a particular period of time in a day. The influence of solar movement on flat Fresnel lens was studied. The influence of groove density of the lens was also determined by which the suitable Fresnel lens was selected. Passive and profiled north-facing and south-facing collectors with multi-lens system have been designed based on the solar altitude and azimuth angle of a geographical location. Performance of the north- and south-facing collector at different times of a day with an acrylic dome indicated better efficiency and uniformity of lighting throughout the day time for the proposed profiled Fresnel collectors. � The Chartered Institution of Building Services Engineers 2014.

SPIE OPTO, 2017, San Francisco, California, United States, Giichi Shibuya, Shohei Yamano, Hiroyuki Yoshida, and Masanori Ozaki "Active liquid-crystal deflector and lens with Fresnel structure", Proc. SPIE 10125, Emerging Liquid Crystal Technologies XII, 101250V (15 February 2017). DOI: https://doi.org/10.1117/12.2261113, A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of ±1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about ±4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

Fresnel mirror in thermodynamic solar power plant technology is an efficient power resource in many potential countries. The key challenge is cost effectiveness of the product and its settling. The importance of using this tech- nology redounded in writing this paper to propose a methodology in order to design this system considering its complexities. Because of the dependency of the product with process of production and installation of this solar plant, a simultaneous design methodology is required. Moreover, a concept of movable factory, from one solar farm site to another one, is also discussed which is iden- tified as a proper solution for such project with reusability.

Bu çalışmada, Sınır Kırınım Dalgası Teorisi(SKDT) yaklaşımı kullanılarak yutucu kesik silindirin kenarından kırınan üniform alanların hesabı yapılmıştır. İlk olarak silindirik dalga gelişi için vektör potansiyeli ifadesi yeniden elde edilmiştir. Elde edilen vektör potansiyeli ifadesi, gözlem noktasındaki toplam skaler elektrik/manyetik alan dağılımının hesaplanmasında kullanılmıştır. Helmholtz-Kirchoff integrali formunda kullanılan alan ifadesi Stokes teoremi ile kırınan alan ve geometrik optik alanın toplamı formuna dönüştürülmüştür. Elde edilen kırınan alan ifadesi üniform olmayan formda sonuç vermektedir. Üniform olmayan alan ifadesi fresnel fonksiyonu yardımıyla üniform hale getirilmiştir. Böylece yutucu kesik silindirin kenarından kırınan uniform alan ifadesi SKDT yaklaşımı ile ilk kez hesaplanmıştır. Son olarak toplam saçılan alan ifadesi kırınan ve geometrik optik alanların toplamı şeklinde hesaplanmıştır. Elde edilen üniform ve üniform olmayan kırınan alan ifadeleri ile toplam saçılan alan ifadesi sayısal olarak değerlendirilmiş ve davranışları incelenmiştir. In this paper the uniform diffracted fields from an opaque cylinder cut surface are studied with the theory of the boundary diffraction wave(BDW). For an incoming cylindrical wave, first the vector potential is refound. The new generated vector potential is used in the calculation of the scalar electric/magnetic field, for the observation point. The field expression is taken in Helmholtz-Kirchoff integral form. By applying the Stokes theorem, the field expression can be written as the sum of the diffracted wave field and the geometrical optic field. The obtained diffracted wave field expression results in a non-uniform structure. The non-uniform field expression is converted to uniform structure by using the fresnel function. In this work the diffracted wave field from the edge of an opaque cut cylinder is calculated with the boundary diffraction wave theory for the first time. Total scattered field is calculated as the sum of the diffracted and the geometrical optic wave fields in this work. Finally the uniform and non-uniform diffracted wave fields and the total scattered field are examined numerically.

X-ray microscopy has emerged as a powerful and versatile imaging technique in many fields of science over the last years, offering insights in opaque media at high spatial resolution. A major challenge remains the fabrication of suitable X-ray lenses, e.g., Fresnel zone plates or compound refractive lenses. In an alternative approach of a lensless imaging scheme the sample is illuminated by a coherent X-ray beam. The sample information is then reconstructed from the recorded diffraction signal by numerical iterative algorithms. Within this thesis the basics of lensless holographic imaging with X-Ray waveguides are summarised and extended to the concept of waveguide-based X-ray interferometry. The specific instrumentation required for the conceptual experiments of waveguide-based holographic imaging is explained and illustrated by the obtained results. Based on the results of these conceptual experiments a dedicated synchrotron endstation for waveguide-based holographic imaging was designed and built. The specifications and properties of the Kirkpatrick-Baez focussing mirrors and other mechanical and optical components are described in detail, along with the instrument control system and various available detectors. First commissioning results prove the imaging abilities of the presented endstation.

En la actividad científica y de investigación es necesario en muchos casos ubicar estaciones de medida y toma de datos en diferentes lugares, habitualmente alejados de los centros de investigación, donde se realiza el estudio y análisis y correlación de dichas medidas y datos. Si las instalaciones científicas de toma de datos se encuentran en entornos alejados de las zonas habitadas, como pueden ser entornos naturales, de montaña o zonas rurales, no es posible el uso de las redes públicas de telecomunicaciones para acceso a la información desde los centros de investigación. Una solución a este problema es la instalación de radioenlaces entre las estaciones científicas de media y los centros de investigación. Este trabajo fin máster estudia, calcula e implementa un radioenlace de larga distancia entre la estación de medidas sismológicas y el observatorio de medidas de ondas electromagnéticas de baja frecuencia ubicados en la Sierra de los Filabres (Almería) y la Universidad de Almería, así como los sistemas y reglas de enrutamiento para el tráfico transparente de diferentes redes de datos.

Glavna svrha ove disertacije je u boljem razumijevanju oscilatornosti funkcija. Za postizanje tog cilja koristimo fraktalnu dimenziju, koju primjenjujemo na nekim od uobiˇcajenih objekata od interesa u tom podruˇcju. Objekti koje istraˇzujemo su chirp-like funkcije, Besselove funkcije, Fresnelovi oscilatorni integrali i neke generalizacije. Prvo, s pozicije fraktalne geometrije prouˇcavamo oscilatornost jedne klase realnih C1 funkcija x = x(t) u blizini t = ∞. Fraktalna oscilatornost rjeˇsenja diferencijalnih jednad ˇzbi drugog reda u blizini beskonaˇcnosti mjeri se oscilatornim i faznim dimenzijama, koje su definirane kao box dimenzija grafa X(τ ) = x( 1/τ ) u blizini τ = 0, odnosno trajektorije (x, x˙ ) u R2, pod pretpostavkom da je (x, x˙ ) spirala koja konvergira prema ishodiˇstu. Box dimenzija ravninske krivulje mjeri akumulaciju krivulje u blizini toˇcke, ˇsto je od osobitog interesa za nerektifikabilne krivulje. Koriste´ci formule za box dimenziju klase nerektifikabilnih spirala izračunata je fazna dimenzija klase oscilatornih funkcija koju uvodimo u ovoj disertaciji. Također, proucavali smo i slucaj rektibikabilnih spirala. Određena klasa spirala koju nazivamo valovitim spiralama, a koja konvergira prema ishodištu, ali s rastu´com funkcijom radijusa na nekim dijelovima, otkrivena je prilikom naseg istrazivanja faznih portreta. Nadalje, istrazujemo faznu dimenziju jedne klase neautonomnih diferencijalnih jednad zbi drugog reda s oscilatornim rjesenjima, a koja ukljuˇcuju i Besselovu jednadzbu. Dokazali smo da je fazna dimenzija Besselovih funkcija jednaka 4/3 , i da im je pripadaju´ca trajektorija valovita spirala, koja pokazuje zanimljivo ponasanje. Takoder, izracunata je i fazna dimenzija odredene generalizacije Besselove jednadzbe. Ponovo, s pozicije fraktalne geometrije istrazujemo i jednu drugu klasu neautonomnih diferencijalnih jednadzbi drugog reda i odgovarajuce sustave u ravnini i prostoru. Koristeci faznu dimenziju rjesenja jednadzbe drugog reda, odredujemo box dimenziju spiralne trajektorije odgovaraju´ceg sustava u prostoru, koja lezi na Lipschitzovim ili H¨olderovim plohama. Fazna dimenzija jednadzbe drugog reda povezana je i sa asimptotikom pridruzenog Poincareovog preslikavanja. Na kraju, odredili smo novi asimptotski razvoj generaliziranih Fresnelovih integrala.

The present paper studies the heat loss of a linear absorber with a trapezoidal cavity and a set of pipes used for a linear Fresnel reflecting solar concentrator. The study includes the measurements on a 1.4 m long prototype installed in a laboratory, and its thermal simulation in steady-state using EnergyPlus software. Results of the measured vertical temperature variation inside the cavity, the surface interior and exterior wall and window temperatures, the global heat loss at steady-state and the heat loss coefficients, are presented for six different temperatures of the pipes. Measurements revealed a stable thermal gradient in the upper portion of the cavity and a convective zone below it. Around 91% of the heat transferred to outdoors occurs at the bottom transparent window, for a pipe temperature of 200 °C. The heat loss coefficient per area of absorbing pipes ranged from 3.39 W/m2K to 6.35 W/m2K (for 110 °C < Tpipe < 285 °C), and it increased with the increase of Tpipe. Simpler and less time-consuming available free software originally designed for heat transfer in buildings was tested to be a possible replacement of the highly complex CFD software commonly used to simulate the steady-state heat loss of the absorber. The experimental and predicted data sets were found to be in good agreement. © 2011 Elsevier Ltd. Fil: Flores Larsen, Silvana Elinor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina Fil: Altamirano, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina Fil: Hernández, Alejandro Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina

KRAMER GmbH, a German supplier for cold room construction, insulation technology and shopfitting with more than 80 years of company experience, and INDUSTRIAL SOLAR GmbH (ISG), a supplier of high-quality solar process heat systems for industrial applications, and the FRAUNHOFER INSTITUTE FOR SOLAR ENERGY SYSTEMS (ISE) are currently developing a standard solar driven cold room for industrial cooling applications. Within the recent EU co-funded project SOLERA, ISE and ISG had gathered experience in the successful operation of the solar cooling technology. Main components of the SOLERA demonstration system are a linear Fresnel collector providing the driving heat at temperatures up to 200 °C for two cascading ammonia water absorption chillers, which produce cold temperatures down to -12 °C, as well as ice storages for peak shifting. In the current project AgroKuhl, which is co-funded by the German Federal Ministry of Education and Research, a consortium of five partners, among them the company KRAMER GmbH and ISE, constructed a cold room, that will now be driven by a similar solar cooling system. Further technical details, operation experience and measurement data from the SOLERA demonstration system in 2011 as well as a description of the new system will be presented in the paper.

El objetivo de este trabajo fue deducir analíticamente las funciones de reflectancia y transmitancia cuando existe generación de plasmones superficiales en sistemas ópticos estratificados. El sistema estudiado es conocido en la literatura como la configuración de Kretschmann[6], esta deducción analítica se realizó de por dos caminos diferentes, inicialmente de forma funcional [7] muy común en la literatura y posteriormente con ayuda de un formalismo matemático más sólido conocido como Método de Matriz de Transferencia MMT[21], este formalismo se utiliza en la solución de problemas en materia condensada en la presencia de sistemas periódicos o no periódicos como pozos o barreras de potencial, para encontrar la solución de la función de onda. Se aplica el MMT a un sistema óptico no periódico para deducir las funciones de reflectancia y transmitancia y luego compararlas con las obtenidas funcionalmente, como ganancia de este trabajo se realizó el montaje experimental objetivo que no estaba propuesto en el proyecto de trabajo de grado inicialmente, los datos experimentales fueron utilizados para validar el modelo teórico desarrollado de forma funcional y matricial, por último se concluyen los parámetros necesarios para la excitación de plasmones superficiales y el comportamiento de las funciones de reflectancia y transmitancia. Abstract. The aim of this work was to derive analytically the reflectance and transmittance functions when there is surface plasmon generation in optical laminates. The system studied is known in the literature as the Kretschmann configuration [6], this deduction is performed analytically in two different ways, initially functionally [7] very common in the literature and then using a stronger mathematical formalism known as transfer matrix method TMM [21], this formalism is used in solving problems in condensed matter systems in the presence of newspapers or newspapers as potential wells or barriers, to find the solution of the wave function. MMT is applied to an optical system nonperiodic functions to deduce the reflectance and transmittance and then compare them with those obtained functionally, as gain this work, the experimental objective was not proposed in the draft grade work initially, experimental data were used to validate the theoretical model developed in a functional matrix finally conclude the parameters necessary for the excitation of surface plasmons and the behavior of functions of reflectance and transmittance. Maestría

XXXIII Jornadas de Automática. 05/09/2012. Vigo Se ha desarrollado en este trabajo un conjunto de componentes de EcosimPro® para la simulación del captador tipo Fresnel de una planta solar situada en la Escuela Técnica Superior de Ingeniería de la Universidad de Sevilla. Se ha basado en un modelo de parámetros distribuidos, ajustando los parámetros del mismo con datos tomados del sistema real y comparando la respuesta del modelo con la temperatura de salida real del sistema. Ministerio de Eduación y Ciencia DPI2010-21589- C05-01

A greenhouse with Fresnel lenses in the south facing roof and a receiver for concentrated Photovoltaics with water cooling (CPVT system) will result in electrical and thermal energy output from the solar energy excess entering a greenhouse. The PV system converts about half of the direct radiation into heat and electricity. During periods with direct radiation this will significantly reduce the heat load on the greenhouse. For an optimal performance the roof elements must be asymmetric with a steep inclination at the north side (the exact angle of course depends on the latitude of the building site). The Fresnel lens structure is best oriented in upwards direction. In the current design, two lenses are placed in the inner space of a double glass. This prevents pollution and condensation on the lenses. By the upward facing of the lens structure, the focus quality is preserved over a much broader range of angles of incidence compared to a lens with downward facing structures. Each PMMA lens with a size of 1.20×1.52 m is composed of 12 ‘tiles’ for easy production. The focal distance of the lens is 1,875 m and the geometrical concentration factor is 50×. This means that in most cases the focus line is thinner than 3 cm. The performance of the lens with respect to the shape of the focal area and the position of the focal line has been analyzed with ray tracing techniques. From this analyses and by the development of a smart tracking system only two motors can bring the receivers in the required positions. One motor controls the distance between lens and receiver and the other controls the translocation of the receivers parallel to the lens. The second conclusion was that the positions of the focal line are within the bounds of the greenhouse construction for almost the whole year. Only in winter, in the early morning and at the end of the day, the focal line will be unreachable. The 480 m2 greenhouse, with the LCPVT system based on Static Fresnel lenses and a 40 m CPVT-module and a 200 m CT-module, is designed by Bode Project Engineering and constructed by Technokas in Bleiswijk the Netherlands.

Cataloged from PDF version of article. We present a digital integral imaging system. A Fresnel lenslet array pattern is written on a phase-only LCoS spatial light modulator device (SLM) to replace the regular analog lenslet array in a conventional integral imaging system. We theoretically analyze the capture part of the proposed system based on Fresnel wave propagation formulation. Because of pixelation and quantization of the lenslet array pattern, higher diffraction orders and multiple focal points emerge. Because of the multiple focal planes introduced by the discrete lenslets, multiple image planes are observed. The use of discrete lenslet arrays also causes some other artifacts on the recorded elemental images. The results reduce to those available in the literature when the effects introduced by the discrete nature of the lenslets are omitted. We performed simulations of the capture part. It is possible to obtain the elemental images with an acceptable visual quality. We also constructed an optical integral imaging system with both capture and display parts using the proposed discrete Fresnel lenslet array written on a SLM. Optical results when self-luminous objects, such as an LED array, are used indicate that the proposed system yields satisfactory results. © 2011 Optical Society of America

Computation of a binary spatial light modulator (SLM) pattern that generates a desired light field is a challenging quantization problem for which several algorithms have been proposed, mainly for far-field or Fourier plane reconstructions. We study this problem assuming that the desired light field is synthesized within a volumetric region in the non-far-field range after free space propagation from the SLM plane. We use Fresnel and Rayleigh-Sommerfeld scalar diffraction theories for propagation of light. We show that, when the desired field is confined to a sufficiently narrow region of space, the ideal gray-level complex-valued SLM pattern generating it becomes sufficiently low pass (oversampled) so it can be successfully halftoned into a binary SLM pattern by solving two decoupled real-valued constrained halftoning problems. Our simulation results indicate that, when the synthesis region is considered, the binary SLM is indistinguishable from a lower resolution full complex gray-level SLM. In our approach, free space propagation related computations are done only once at the beginning, and the rest of the computation time is spent on carrying out standard image halftoning. (C) 2011 Optical Society of America

El comportamiento de la luz, como se conoce en la actualidad, es dual; esto quiere decir que la luz se comporta como onda y a la vez como partícula. Fue Einstein quien paró la discusión del comportamiento de la luz que duró por siglos. Newton fue el primero que encontró que la luz se comportaba como partícula, y que ésta seguía en línea recta hasta encontrar un obstáculo. Muchos científicos aceptaron y defendieron esta postura, pero hubo otros científicos, como Sir Young que observó que la luz se comportaba como onda mediante su famoso experimento de interferencia, el cual lleva su nombre. En el siglo XIX, los físicos teóricos defensores de la teoría corpuscular de la luz prepararon un concurso con el objetivo de encontrar una teoría que diera la estocada final a los que defendieran la teoría ondulatoria. Después de evaluar a los dos únicos concursantes, se realizó un solo arreglo experimental, dirigido por François Joan Domènec Arago, para demostrar la supuesta invalidez de la teoría de la difracción de Augustin- Jean Fresnel. Poisson, al revisar el trabajo presentado por Fresnel, encontró que la teoría implicaba un punto luminoso justo donde debería aparecer la generación de una sombra de un objeto pequeño, lo cual no era congruente para él. En este trabajo se muestra una variante en el diseño experimental que presentó Arago que hace de fácil reproducción la obtención del punto de Poisson.

XXXII Jornadas Nacionales de Automática Sevilla 2011 En este artículo se presenta el modelado matemático, así como algoritmos de control de un captador solar tipo Fresnel que pertenece planta de refrigeración solar situada en la Escuela Superior de Ingenieros de la Universidad de Sevilla. Se va a desarrollar un modelo de parámetros distribuidos, ajustando los parámetros del mismo con datos tomados del sistema real y comparando la respuesta del modelo con la salida del sistema. Por último, se implementará una estrategia de control clásica, un PID con un compensador de perturbaciones de tipo feedforward paralelo, cuyo desempeño será validado mediante simulación usando el modelo de parámetros distribuidos. Unión Europea DPI 2008-05818 Junta de Andalucía P07-TEP-02720

The usage of Fresnel diffraction as an approximation of the Kirchhoff formula offers a large variety of advantages concerning diverse calculations for camera systems. However, Fresnel approximations cannot be applied to arbitrary camera systems. For configurations with wide aperture, e.g., the usage of Fresnel approximation is not possible without accepting an unagreeable deviation. It is important to check in advance if a camera system allows such an approximation for the needed calculations. Assuming that focal length f and ground distance g are given quantities, investigations of the real and complex integrands lead to a formula from which the minimal F-number f # (respectively the maximum aperture radius r) is derived, so that Fresnel approximations can still be applied to a system. The analytical results are supported by numerical calculations and audited for three camera configurations outlined for remote sensing.

Il est possible de concevoir un enseignement de la physique qui incorpore l'histoire de la physique sur un mode qui n'est ni anecdotique, ni autonome et qui peut être décliné à différents niveaux de la formation, des élèves de lycée aux enseignants à l'université. L'introduction du manuscrit porte sur une mise en perspective de la démarche proposée avec des recherches antérieures. Le manuscrit est composé de quatre parties. Dans la partie I, après avoir rappelé les objectifs qui ont prévalu à la réalisation du cédérom « Histoire des idées sur la lumière - de l'Antiquité au début du XXe siècle », qui aborde la lumière à travers une approche historique, expérimentale et philosophique, je propose une utilisation de ce cédérom pour l'enseignement de la diffraction par une approche historique (la disparition des franges intérieures dans l'ombre d'un fil). Dans la partie II, je précise l'enjeu que constitue l'utilisation de la figure géométrique de Newton (1684), accompagnée des coordonnées polaires et des vecteurs, pour mettre à la portée d'un large public l'un des grands succès de la pensée scientifique : la détermination des trajectoires elliptiques des planètes (sans utilisation du calcul différentiel). Dans cette partie, je reviens également sur le modèle d'équant de Kepler, souvent assimilé à un échec, alors qu'il peut ouvrir la voie, dans le cadre de la formation des enseignants, à une discussion renouvelée des dynamiques aristotélicienne et newtonienne. La partie III est une analyse historique de "La Dynamique de l'électron" de Henri Poincaré. Après avoir rappelé le point de vue général de Poincaré sur les sciences et leur enseignement, et avoir situé son travail dans la lignée de Lorentz et des connaissances des géomètres, je reviens sur quatre clés que nous avons proposées (avec Jean-Pierre Provost) pour comprendre la logique du Mémoire : l'utilisation de transformations de Lorentz actives, le rôle de l'action et de son invariance, l'origine de la condition de groupe pour éliminer les dilatations (à travers les lettres à Lorentz de mai 1905) et le rôle des modèles d'électron comme théorème d'existence de la nouvelle dynamique. Dans la quatrième et dernière partie, je donne un historique des travaux de Planck et d'Einstein sur les quanta, afin de comparer leurs approches (étude des dépendances énergétique ou volumique de l'entropie du corps noir) et de les replacer dans une perspective moderne où la notion de mode quantique est la notion fondamentale. Je reviens ensuite sur deux questions naturelles que posent les quanta d'Einstein de mars 1905 pour des étudiants abordant la relativité et le quantique : leur vitesse (à laquelle répond le second postulat de la relativité) et leur indépendance (assujettie au retour à loi de Wien de 1896).

Il est possible de concevoir un enseignement de la physique qui incorpore l'histoire de la physique sur un mode qui n'est ni anecdotique, ni autonome et qui peut être décliné à différents niveaux de la formation, des élèves de lycée aux enseignants à l'université. L'introduction du manuscrit porte sur une mise en perspective de la démarche proposée avec des recherches antérieures. Le manuscrit est composé de quatre parties. Dans la partie I, après avoir rappelé les objectifs qui ont prévalu à la réalisation du cédérom « Histoire des idées sur la lumière - de l'Antiquité au début du XXe siècle », qui aborde la lumière à travers une approche historique, expérimentale et philosophique, je propose une utilisation de ce cédérom pour l'enseignement de la diffraction par une approche historique (la disparition des franges intérieures dans l'ombre d'un fil). Dans la partie II, je précise l'enjeu que constitue l'utilisation de la figure géométrique de Newton (1684), accompagnée des coordonnées polaires et des vecteurs, pour mettre à la portée d'un large public l'un des grands succès de la pensée scientifique : la détermination des trajectoires elliptiques des planètes (sans utilisation du calcul différentiel). Dans cette partie, je reviens également sur le modèle d'équant de Kepler, souvent assimilé à un échec, alors qu'il peut ouvrir la voie, dans le cadre de la formation des enseignants, à une discussion renouvelée des dynamiques aristotélicienne et newtonienne. La partie III est une analyse historique de "La Dynamique de l'électron" de Henri Poincaré. Après avoir rappelé le point de vue général de Poincaré sur les sciences et leur enseignement, et avoir situé son travail dans la lignée de Lorentz et des connaissances des géomètres, je reviens sur quatre clés que nous avons proposées (avec Jean-Pierre Provost) pour comprendre la logique du Mémoire : l'utilisation de transformations de Lorentz actives, le rôle de l'action et de son invariance, l'origine de la condition de groupe pour éliminer les dilatations (à travers les lettres à Lorentz de mai 1905) et le rôle des modèles d'électron comme théorème d'existence de la nouvelle dynamique. Dans la quatrième et dernière partie, je donne un historique des travaux de Planck et d'Einstein sur les quanta, afin de comparer leurs approches (étude des dépendances énergétique ou volumique de l'entropie du corps noir) et de les replacer dans une perspective moderne où la notion de mode quantique est la notion fondamentale. Je reviens ensuite sur deux questions naturelles que posent les quanta d'Einstein de mars 1905 pour des étudiants abordant la relativité et le quantique : leur vitesse (à laquelle répond le second postulat de la relativité) et leur indépendance (assujettie au retour à loi de Wien de 1896).

Οι ανανεώσιμες πηγές ενέργειας (ΑΠΕ), όπως η ηλιακή ενέργεια, μπορούν να προσφέρουν εναλλακτικούς τρόπους παραγωγής ενέργειας. Κάθε μορφή ΑΠΕ έχει τις δικές της ιδιομορφίες και μπορούν να εφαρμοστούν είτε σε μεγάλες εγκαταστάσεις παραγωγής ηλεκτρικής και θερμικής ενέργειας είτε σε μικρότερες μονάδες όπως στα κτίρια. Ενδιαφέρον παρουσιάζει η συνδυασμένη αξιοποίηση των παραπάνω ενεργειακών πηγών, ιδίως για την κάλυψη των ηλεκτρικών και θερμικών αναγκών των κτιρίων.Αντικείμενο αυτής της διπλωματικής εργασίας είναι η μελέτη συγκεντρωτικών συστημάτων χαμηλής συγκέντρωσης και των παραγόντων που επηρεάζουν την λειτουργία τους, με την χρήση τριών γεωμετρικών συγκεντρωτικών μέσων, τα οποία είναι: το σύστημα V-Trough, το σύστημα Fresnel γραμμικής εστίας και το κυλινδροπαραβολικό σύστημα γραμμικής εστίας, με χρήση συμβατικών φωτοβολταϊκών για την παραγωγή ηλεκτρικής ισχύος. Όμως, από το την προσπίπτουσα ηλιακή ακτινοβολία που συγκεντρώνεται στον απορροφητή, ένα μέρος μετατρέπεται σε ηλεκτρική ενέργεια, ενώ το υπόλοιπο μεταδίδεται στο περιβάλλον με την μορφή θερμότητας. Έτσι, περαιτέρω μελέτη έγινε με βάση την δημιουργία υβριδικού συγκεντρωτικού φωτοβολταϊκού/θερμικού συστήματος, ταυτόχρονης παραγωγής ηλεκτρικής και θερμικής ενέργειας χρησιμοποιώντας την βέλτιστη γεωμετρία, το οποίο θα μπορούσε να δώσει ικανοποιητικά ποσά θερμικής ενέργειας, χωρίς να ζημιώνεται η ηλεκτρική και το αντίστροφο, κάτι που θα καθιστούσε τα συστήματα αυτά ενεργειακώς και οικονομικώς πιο ανταγωνιστικά.Τα πειραματικά αποτελέσματα περιλαμβάνουν διαγράμματα ηλεκτρικών αποδοτικοτήτων των πειραματικών συστημάτων καθώς και των μεγεθών Pmax, Vpmax, Voc, Ιpmax, Ιsc, συναρτήσει της θερμοκρασίας λειτουργίας Tpv, κάτω από σταθερή ακτινοβολία G, θερμικών αποδόσεων, προφίλ κατανομών συγκεντρωτικής ακτινοβολίας καθώς και χαρακτηριστικές καμπύλες I-V για καθένα απ αυτά. The renewable energy sources (RES) like solar energy, can offer an alternative solution to power production. Each form of RES, has its own specifications and they can be applied in big installations of electric and thermal energy production or in smaller units as the buildings. This thesis investigates the performance of three different types of solar concentrating systems, which are: the V-Trough system, the linear Fresnel system and the Parabolic Trough system, with usage of common photovoltaics, instead of concentrating photovoltaics, for the electricity production.However, only a small part of the incoming solar radiation it is changed by an absorber into electric energy, while the rest is transmitted to the environment with the form of heat. Thus, further study has been done with base of the creation of a hybrid concentrating photovoltaic/thermal system, with simultaneous production of electric and thermal energy using the most optimal geometry. This could give satisfactory sums of thermal energy, without affecting the production of electric energy and vice versa, something that would render this systems economically more competitively.The experimental results include diagrams with the electric performance of the experimental systems as well as values of Pmax, Vpmax, Voc, Ipmax, Isc, associated with the operating temperature Tpv, under constant radiation G, thermal output, distribution profiles of the concentrating radiation as well as characteristic curves I-V for each one of them.

In this paper we present an approach to automatic generation of GUI for browsing of RDF data based on observation of existing forms and their adaptation to available RDF graphs. The objective of such an approach is the rapid prototyping of forms and their associated queries by exploiting the vast amount examples that is already available from the Web, and trying to automate those steps requiring human intervention (form template extraction, query specification) for customizing found examples to developer’s specific needs.

Date of Conference: 22-24 April 2010 As computer generated holograms becomes more common, the fast computation of holographic interference patterns in digital environment becomes a necessity. Since the computation time of holograms via Fresnel (or Rayleigh-Sommerfeld) diffraction models makes real time applications impossible, the holographic stereograms are developed to be a solution for this problem. Holographic stereograms divide the hologram plane into segments. In phase added stereograms the coordinates of 3D source points are used while calculating the diffraction field. And that enables to calculate the diffraction field with appropriate sized FFTs. Although the phase added stereograms are advantageous in terms of computation time, the quality of the reconstructed three dimensional images may not be satisfactory. The main reason is that the diffraction field of a given point source is approximated as a pure complex sinusuoid in each segment. To increase the reconstruction quality, we propose a method that uses variable sized segments, as opposed to previously developed holographic stereograms that use fixed sized segments. While approximating the diffraction field of a point source, higher frequency regions are covered with smaller segments and lower frequency regions with larger segments. As a result of this, we keep the total number of oscillations of pure sinusoidal waves constant in each segment. The simulations that we carried out for a point source show that we are able to obtain better quality reconstruction with our method. ©2010 IEEE.

El presente trabajo describe una solución de acceso inalámbrico a la Internet con tecnología WI-FI en varios puntos del cantón Chordeleg, tanto en su zona urbana como rural, desde un punto de vista práctico, abordando el estado del arte, conceptos teóricos y luego el diseño telemático de la solución técnica. Capítulo I se describe la tecnología WI-FI, sus diferentes estándares que existen en el mercado y sobre todo la seguridad en al ambiente inalámbrico que adopta WI-FI. Capítulo II se indica un análisis de cómo se encuentra la red interna de la I. Municipalidad de Chordeleg, para posteriormente brindar alternativas de mejorar, la red interna de esta institución. Capítulo III se muestra un análisis de la red externa de la I. Municipalidad de Chordeleg, contemplando desde los equipos que se van a utilizar (radios, antenas, software), su topología y como estos van a interactuar entre si para brindar un servicio optimo. Capitulo IV se presenta un enfoque simulado, con un programa llama Radio Mobile que nos permitirá afianzar el cálculo realizado en forma manual. Finalmente en los Capítulos V y Capítulo VI se describe brevemente las conclusiones y recomendaciones del Diseño, se muestra los anexos incluyendo los diferentes cálculos que se realiza en el presente trabajo. Magíster en Telemática Cuenca

En este trabajo se analizan los factores geométricos involucrados en el funcionamiento de un sistema de concentradores tipo Fresnel simplificado. Se determinan las coordenadas del haz de radiación solar directa reflejado sobre un espejo teniendo en cuenta el origen del rayo solar directo (la posición del Sol en el firmamento) y el ángulo β de rotación del espejo. Fil: Salazar, Germán Ariel. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cadena, Carlos Alberto. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentina

Se ha diseñado y construido un equipo que permite ajustar el punto óptimo de trabajo de un espejo de 50 metros de longitud, empleando detectores basados en seleniuros, cuando enfoca a un absorbedor con foco lineal. El espejo, forma parte de un conjunto mayor y que constituye un concentrador Fresnel, aunque los ajustes o correcciones de los mismos, se realizan en forma individual. El principio de funcionamiento es tal, que un equipo entrega una señal error que corrige el posible desacople entre cada espejo y el absorbedor común a todos ellos, ubicado en un plano focal rectangular a un distancia determinada sobre los mismos, y compuesto por caños de acero., It has been designed and built an equipment to adjust the optimum operating point of a mirror 40 or 50 meters long, using detectors based selenides, when focused on an absorber. Trough the concentrator device, this system should be able to take a great profit of direct sun radiation. The mirror is part of larger equipment and which is a Fresnel concentrator, though the adjustments or corrections thereof, are performed individually. The operating principle is such that a team that delivers an error signal corrects the possible delay between each mirror and the absorber common to them all, located in a rectangular focal plane a given distance on them, and pipes composed of zero . Automatization is a requirement in the correct use of Fresnel concentrators just as it is well described in the literature., Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES)