Study of the damage evolution of the concrete under freeze-thaw cycles using traditional and non-traditional techniques

Some experiments have been performed to investigate the cyclic freeze-thaw deterioration of concrete, using traditional and non-traditional techniques. Two concrete mixes, with different pore structure, were tested in order to compare the behavior of a freeze-thaw resistant concrete from one that is not. One of the concretes was air entrained, high content of cement and low w/c ratio, and the other one was a lower cement content and higher w/c ratio, without air-entraining agent. Concrete specimens were studied under cyclic freeze-thaw conditions according to UNE-CENT/TS 12390-9 test, using 3% NaCl solution as freezing medium (CDF test: Capillary Suction, De-icing agent and Freeze-thaw Test). The temperature and relative humidity were measured during the cycles inside the specimens using embedded sensors placed at different heights from the surface in contact with the de-icing agent solution. Strain gauges were used to measure the strain variations at the surface of the specimens. Also, measurements of ultrasonic pulse velocity through the concrete specimens were taken before, during, and after the freeze-thaw cycles. According to the CDF test, the failure of the non-air-entraining agent concrete was observed before 28 freeze-thaw cycles; contrariwise, the scaling of the air-entraining agent concrete was only 0.10 kg/m 2 after 28 cycles, versus 3.23 kg/m 2 in the deteriorated concrete, after 28 cycles. Similar behavior was observed on the strain measurements. The residual strain in the deteriorated concrete after 28 cycles was 1150 ���m versus 65 ���m, in the air-entraining agent concrete. By means of monitoring the changes of ultrasonic pulse velocity during the freeze-thaw cycles, the deterioration of the tested specimens were assessed

Strict and non-strict independent and-parallelism in logic programs: Correctness, efficiency, and compile-time conditions.

This paper presents some fundamental properties of independent and-parallelism and extends its applicability by enlarging the class of goals eligible for parallel execution. A simple model of (independent) and-parallel execution is proposed and issues of correctness and efficiency discussed in the light of this model. Two conditions, "strict" and "non-strict" independence, are defined and then proved sufficient to ensure correctness and ef��ciency of parallel execution: if goals which meet these conditions are executed in parallel the solutions obtained are the same as those produced by standard sequential execution. Also, in absence of failure, the parallel proof procedure does not gen��rate any additional work (with respect to standard SLD-resolution) while the actual execution time is reduced. Finally, in case of failure of any of the goals no slow down will occur. For strict independence the results are shown to hold independently of whether the parallel goals execute in the same environment or in sep��rate environments. In addition, a formal basis is given for the automatic compile-time generation of independent and-parallelism: compile-time conditions to efficiently check goal independence at run-time are proposed and proved sufficient. Also, rules are given for constructing simpler conditions if information regarding the binding context of the goals to be executed in parallel is available to the compiler.

Advances in the Simultaneous Multiple Surface optical design method for imaging and non-imaging applications

Classical imaging optics has been developed over centuries in many areas, such as its paraxial imaging theory and practical design methods like multi-parametric optimization techniques. Although these imaging optical design methods can provide elegant solutions to many traditional optical problems, there are more and more new design problems, like solar concentrator, illumination system, ultra-compact camera, etc., that require maximum energy transfer efficiency, or ultra-compact optical structure. These problems do not have simple solutions from classical imaging design methods, because not only paraxial rays, but also non-paraxial rays should be well considered in the design process. Non-imaging optics is a newly developed optical discipline, which does not aim to form images, but to maximize energy transfer efficiency. One important concept developed from non-imaging optics is the ���edge-ray principle���, which states that the energy flow contained in a bundle of rays will be transferred to the target, if all its edge rays are transferred to the target. Based on that concept, many CPC solar concentrators have been developed with efficiency close to the thermodynamic limit. When more than one bundle of edge-rays needs to be considered in the design, one way to obtain solutions is to use SMS method. SMS stands for Simultaneous Multiple Surface, which means several optical surfaces are constructed simultaneously. The SMS method was developed as a design method in Non-imaging optics during the 90s. The method can be considered as an extension to the Cartesian Oval calculation. In the traditional Cartesian Oval calculation, one optical surface is built to transform an input wave-front to an out-put wave-front. The SMS method however, is dedicated to solve more than 1 wave-fronts transformation problem. In the beginning, only 2 input wave-fronts and 2 output wave-fronts transformation problem was considered in the SMS design process for rotational optical systems or free-form optical systems. Usually ���SMS 2D��� method stands for the SMS procedure developed for rotational optical system, and ���SMS 3D��� method for the procedure for free-form optical system. Although the SMS method was originally employed in non-imaging optical system designs, it has been found during this thesis that with the improved capability to design more surfaces and control more input and output wave-fronts, the SMS method can also be applied to imaging system designs and possesses great advantage over traditional design methods. In this thesis, one of the main goals to achieve is to further develop the existing SMS-2D method to design with more surfaces and improve the stability of the SMS-2D and SMS-3D algorithms, so that further optimization process can be combined with SMS algorithms. The benefits of SMS plus optimization strategy over traditional optimization strategy will be explained in details for both rotational and free-form imaging optical system designs. Another main goal is to develop novel design concepts and methods suitable for challenging non-imaging applications, e.g. solar concentrator and solar tracker. This thesis comprises 9 chapters and can be grouped into two parts: the first part (chapter 2-5) contains research works in the imaging field, and the second part (chapter 6-8) contains works in the non-imaging field. In the first chapter, an introduction to basic imaging and non-imaging design concepts and theories is given. Chapter 2 presents a basic SMS-2D imaging design procedure using meridian rays. In this chapter, we will set the imaging design problem from the SMS point of view, and try to solve the problem numerically. The stability of this SMS-2D design procedure will also be discussed. The design concepts and procedures developed in this chapter lay the path for further improvement. Chapter 3 presents two improved SMS 3 surfaces��� design procedures using meridian rays (SMS-3M) and skew rays (SMS-1M2S) respectively. The major improvement has been made to the central segments selections, so that the whole SMS procedures become more stable compared to procedures described in Chapter 2. Since these two algorithms represent two types of phase space sampling, their image forming capabilities are compared in a simple objective design. Chapter 4 deals with an ultra-compact SWIR camera design with the SMS-3M method. The difficulties in this wide band camera design is how to maintain high image quality meanwhile reduce the overall system length. This interesting camera design provides a playground for the classical design method and SMS design methods. We will show designs and optical performance from both classical design method and the SMS design method. Tolerance study is also given as the end of the chapter. Chapter 5 develops a two-stage SMS-3D based optimization strategy for a 2 freeform mirrors imaging system. In the first optimization phase, the SMS-3D method is integrated into the optimization process to construct the two mirrors in an accurate way, drastically reducing the unknown parameters to only few system configuration parameters. In the second optimization phase, previous optimized mirrors are parameterized into Qbfs type polynomials and set up in code V. Code V optimization results demonstrates the effectiveness of this design strategy in this 2-mirror system design. Chapter 6 shows an etendue-squeezing condenser optics, which were prepared for the 2010 IODC illumination contest. This interesting design employs many non-imaging techniques such as the SMS method, etendue-squeezing tessellation, and groove surface design. This device has theoretical efficiency limit as high as 91.9%. Chapter 7 presents a freeform mirror-type solar concentrator with uniform irradiance on the solar cell. Traditional parabolic mirror concentrator has many drawbacks like hot-pot irradiance on the center of the cell, insufficient use of active cell area due to its rotational irradiance pattern and small acceptance angle. In order to conquer these limitations, a novel irradiance homogenization concept is developed, which lead to a free-form mirror design. Simulation results show that the free-form mirror reflector has rectangular irradiance pattern, uniform irradiance distribution and large acceptance angle, which confirm the viability of the design concept. Chapter 8 presents a novel beam-steering array optics design strategy. The goal of the design is to track large angle parallel rays by only moving optical arrays laterally, and convert it to small angle parallel output rays. The design concept is developed as an extended SMS method. Potential applications of this beam-steering device are: skylights to provide steerable natural illumination, building integrated CPV systems, and steerable LED illumination. Conclusion and future lines of work are given in Chapter 9. Resumen La ��ptica de formaci��n de imagen cl��sica se ha ido desarrollando durante siglos, dando lugar tanto a la teor��a de ��ptica paraxial y los m��todos de dise��o pr��cticos como a t��cnicas de optimizaci��n multiparam��tricas. Aunque estos m��todos de dise��o ��ptico para formaci��n de imagen puede aportar soluciones elegantes a muchos problemas convencionales, siguen apareciendo nuevos problemas de dise��o ��ptico, concentradores solares, sistemas de iluminaci��n, c��maras ultracompactas, etc. que requieren m��xima transferencia de energ��a o dimensiones ultracompactas. Este tipo de problemas no se pueden resolver f��cilmente con m��todos cl��sicos de dise��o porque durante el proceso de dise��o no solamente se deben considerar los rayos paraxiales sino tambi��n los rayos no paraxiales. La ��ptica anid��lica o no formadora de imagen es una disciplina que ha evolucionado en gran medida recientemente. Su objetivo no es formar imagen, es maximazar la eficiencia de transferencia de energ��a. Un concepto importante de la ��ptica anid��lica son los ���rayos marginales���, que se pueden utilizar para el dise��o de sistemas ya que si todos los rayos marginales llegan a nuestra ��rea del receptor, todos los rayos interiores tambi��n llegar��n al receptor. Haciendo uso de este principio, se han dise��ado muchos concentradores solares que funcionan cerca del l��mite te��rico que marca la termodin��mica. Cuando consideramos m��s de un haz de rayos marginales en nuestro dise��o, una posible soluci��n es usar el m��todo SMS (Simultaneous Multiple Surface), el cu��l dise��a simult��neamente varias superficies ��pticas. El SMS naci�� como un m��todo de dise��o para ��ptica anid��lica durante los a��os 90. El m��todo puede ser considerado como una extensi��n del c��lculo del ��valo cartesiano. En el m��todo del ��valo cartesiano convencional, se calcula una superficie para transformar un frente de onda entrante a otro frente de onda saliente. El m��todo SMS permite transformar varios frentes de onda de entrada en frentes de onda de salida. Inicialmente, s��lo era posible transformar dos frentes de onda con dos superficies con simetr��a de rotaci��n y sin simetr��a de rotaci��n, pero esta limitaci��n ha sido superada recientemente. Nos referimos a ���SMS 2D��� como el m��todo orientado a construir superficies con simetr��a de rotaci��n y llamamos ���SMS 3D��� al m��todo para construir superficies sin simetr��a de rotaci��n o free-form. Aunque el m��todo originalmente fue aplicado en el dise��o de sistemas anid��licos, se ha observado que gracias a su capacidad para dise��ar m��s superficies y controlar m��s frentes de onda de entrada y de salida, el SMS tambi��n es posible aplicarlo a sistemas de formaci��n de imagen proporcionando una gran ventaja sobre los m��todos de dise��o tradicionales. Uno de los principales objetivos de la presente tesis es extender el m��todo SMS-2D para permitir el dise��o de sistemas con mayor n��mero de superficies y mejorar la estabilidad de los algoritmos del SMS-2D y SMS-3D, haciendo posible combinar la optimizaci��n con los algoritmos. Los beneficios de combinar SMS y optimizaci��n comparado con el proceso de optimizaci��n tradicional se explican en detalle para sistemas con simetr��a de rotaci��n y sin simetr��a de rotaci��n. Otro objetivo importante de la tesis es el desarrollo de nuevos conceptos de dise��o y nuevos m��todos en el ��rea de la concentraci��n solar fotovoltaica. La tesis est�� estructurada en 9 cap��tulos que est��n agrupados en dos partes: la primera de ellas (cap��tulos 2-5) se centra en la ��ptica formadora de imagen mientras que en la segunda parte (cap��tulos 6-8) se presenta el trabajo del ��rea de la ��ptica anid��lica. El primer cap��tulo consta de una breve introducci��n de los conceptos b��sicos de la ��ptica anid��lica y la ��ptica en formaci��n de imagen. El cap��tulo 2 describe un proceso de dise��o SMS-2D sencillo basado en los rayos meridianos. En este cap��tulo se presenta el problema de dise��ar un sistema formador de imagen desde el punto de vista del SMS y se intenta obtener una soluci��n de manera num��rica. La estabilidad de este proceso se analiza con detalle. Los conceptos de dise��o y los algoritmos desarrollados en este cap��tulo sientan la base sobre la cual se realizar��n mejoras. El cap��tulo 3 presenta dos procedimientos para el dise��o de un sistema con 3 superficies SMS, el primero basado en rayos meridianos (SMS-3M) y el segundo basado en rayos oblicuos (SMS-1M2S). La mejora m��s destacable recae en la selecci��n de los segmentos centrales, que hacen m��s estable todo el proceso de dise��o comparado con el presentado en el cap��tulo 2. Estos dos algoritmos representan dos tipos de muestreo del espacio de fases, su capacidad para formar imagen se compara dise��ando un objetivo simple con cada uno de ellos. En el cap��tulo 4 se presenta un dise��o ultra-compacto de una c��mara SWIR dise��ada usando el m��todo SMS-3M. La dificultad del dise��o de esta c��mara de espectro ancho radica en mantener una alta calidad de imagen y al mismo tiempo reducir dr��sticamente sus dimensiones. Esta c��mara es muy interesante para comparar el m��todo de dise��o cl��sico y el m��todo de SMS. En este cap��tulo se presentan ambos dise��os y se analizan sus caracter��sticas ��pticas. En el cap��tulo 5 se describe la estrategia de optimizaci��n basada en el m��todo SMS-3D. El m��todo SMS-3D calcula las superficies ��pticas de manera precisa, dejando s��lo unos pocos par��metros libres para decidir la configuraci��n del sistema. Modificando el valor de estos par��metros se genera cada vez mediante SMS-3D un sistema completo diferente. La optimizaci��n se lleva a cabo variando los mencionados par��metros y analizando el sistema generado. Los resultados muestran que esta estrategia de dise��o es muy eficaz y eficiente para un sistema formado por dos espejos. En el cap��tulo 6 se describe un sistema de compresi��n de la Etendue, que fue presentado en el concurso de iluminaci��n del IODC en 2010. Este interesante dise��o hace uso de t��cnicas propias de la ��ptica anid��lica, como el m��todo SMS, el teselado de las lentes y el dise��o mediante grooves. Este dispositivo tiene un l��mite te��rica en la eficiencia del 91.9%. El cap��tulo 7 presenta un concentrador solar basado en un espejo free-form con irradiancia uniforme sobre la c��lula. Los concentradores parab��licos tienen numerosas desventajas como los puntos calientes en la zona central de la c��lula, uso no eficiente del ��rea de la c��lula al ser ��sta cuadrada y adem��s tienen ��ngulos de aceptancia de reducido. Para poder superar estas limitaciones se propone un novedoso concepto de homogeneizaci��n de la irrandancia que se materializa en un dise��o con espejo free-form. El an��lisis mediante simulaci��n demuestra que la irradiancia es homog��nea en una regi��n rectangular y con mayor ��ngulo de aceptancia, lo que confirma la viabilidad del concepto de dise��o. En el cap��tulo 8 se presenta un novedoso concepto para el dise��o de sistemas afocales din��micos. El objetivo del dise��o es realizar un sistema cuyo haz de rayos de entrada pueda llegar con ��ngulos entre ��45�� mientras que el haz de rayos a la salida sea siempre perpendicular al sistema, variando ��nicamente la posici��n de los elementos ��pticos lateralmente. Las aplicaciones potenciales de este dispositivo son varias: tragaluces que proporcionan iluminaci��n natural, sistemas de concentraci��n fotovoltaica integrados en los edificios o iluminaci��n direccionable con LEDs. Finalmente, el ��ltimo cap��tulo contiene las conclusiones y las l��neas de investigaci��n futura.

Hybrid Contribution of JPEG200 Video Files for Professional Production Centers Reliability and Non-Reliability Transmission File Based in Image Quality Needed

ATM, SDH or satellite have been used in the last century as the contribution network of Broadcasters. However the attractive price of IP networks is changing the infrastructure of these networks in the last decade. Nowadays, IP networks are widely used, but their characteristics do not offer the level of performance required to carry high quality video under certain circumstances. Data transmission is always subject to errors on line. In the case of streaming, correction is attempted at destination, while on transfer of files, retransmissions of information are conducted and a reliable copy of the file is obtained. In the latter case, reception time is penalized because of the low priority this type of traffic on the networks usually has. While in streaming, image quality is adapted to line speed, and line errors result in a decrease of quality at destination, in the file copy the difference between coding speed vs line speed and errors in transmission are reflected in an increase of transmission time. The way news or audiovisual programs are transferred from a remote office to the production centre depends on the time window and the type of line available; in many cases, it must be done in real time (streaming), with the resulting image degradation. The main purpose of this work is the workflow optimization and the image quality maximization, for that reason a transmission model for multimedia files adapted to JPEG2000, is described based on the combination of advantages of file transmission and those of streaming transmission, putting aside the disadvantages that these models have. The method is based on two patents and consists of the safe transfer of the headers and data considered to be vital for reproduction. Aside, the rest of the data is sent by streaming, being able to carry out recuperation operations and error concealment. Using this model, image quality is maximized according to the time window. In this paper, we will first give a briefest overview of the broadcasters requirements and the solutions with IP networks. We will then focus on a different solution for video file transfer. We will take the example of a broadcast center with mobile units (unidirectional video link) and regional headends (bidirectional link), and we will also present a video file transfer file method that satisfies the broadcaster requirements.

Comparing linear and non linear wind flow models

Assessing wind conditions on complex terrain has become a hard task as terrain complexity increases. That is why there is a need to extrapolate in a reliable manner some wind parameters that determine wind farms viability such as annual average wind speed at all hub heights as well as turbulence intensities. The development of these tasks began in the early 90��s with the widely used linear model WAsP and WAsP Engineering especially designed for simple terrain with remarkable results on them but not so good on complex orographies. Simultaneously non-linearized Navier Stokes solvers have been rapidly developed in the last decade through CFD (Computational Fluid Dynamics) codes allowing simulating atmospheric boundary layer flows over steep complex terrain more accurately reducing uncertainties. This paper describes the features of these models by validating them through meteorological masts installed in a highly complex terrain. The study compares the results of the mentioned models in terms of wind speed and turbulence intensity.

Differences between innovative and non-innovative microenterprises: internal factors

This exploratory study presents a comparison between two samples of microenterprises. One sample is formed by companies involved in product innovation during the current economic crisis and the other is formed by companies not involved in product innovation during the same period. The comparison analyzes which internal factors, supported by the literature as the influential factors of small business innovation, are significant when explaining the main differences between innovative microenterprise and non-innovative ones. The results suggest that the factors related to the organization and activity of the company are the factors which explain the differences between these two types of firms, rather than those factors related to micro-entrepreneurs own profile.

1H HR MAS NMR metabolomic and non-destructive 2D NMR relaxometry to assess internal quality in apples.

NMR can be considered a multi-scale multidimensional technology in the sense that it provides both spatial insight at macroscopic (MRI) or microscopic level (relaxometry), together with chemical characterization (HR-MAS). In this study 296 apples (from 4 cultivars) were MRI screened (20 slices per fruit) among which 7 fruits were used for metabolomic study by 1H HR MAS in order to assess various chemical shifts: malic acid, sucrose, glucose, fructose and ethanol. On the first season, tissue samples were taken from the sound and affected apples (near the core, centre and outer part of the mesocarp) belonging to sound and affected locations, while on the second season, tissue samples were focused on the comparison between sound and affected tissue. Beside, MRI and 2D non-destructive relaxometry (on whole fruits, and localized tissue) where performed on 72 and 12 apples respectively in order to compare features at macroscopic (tissue) and microscopic (subcellular) level. HR MAS shows higher content of ?-glucose, ?-glucose, malic acid and aromatic compounds in watercore affected tissues from both seasons, while sound tissue reflects higher sucrose. Microscopic (subcellular) degradation of tissue varies according to disorder development and is in good accordance with macroscopic characterization with MRI.

Some relations between visual perception and non-linear photonic structures

The main objective of this work is to present a way to emulate some functions of the mammalian visual system and a model to analyze subjective sensations and visual illusions

Linear color correction for multiple illumination changes and non-overlapping cameras

Many image processing methods, such as techniques for people re-identification, assume photometric constancy between different images. This study addresses the correction of photometric variations based upon changes in background areas to correct foreground areas. The authors assume a multiple light source model where all light sources can have different colours and will change over time. In training mode, the authors learn per-location relations between foreground and background colour intensities. In correction mode, the authors apply a double linear correction model based on learned relations. This double linear correction includes a dynamic local illumination correction mapping as well as an inter-camera mapping. The authors evaluate their illumination correction by computing the similarity between two images based on the earth mover's distance. The authors compare the results to a representative auto-exposure algorithm found in the recent literature plus a colour correction one based on the inverse-intensity chromaticity. Especially in complex scenarios the authors��� method outperforms these state-of-the-art algorithms.

Comparison of linear and non-linear 2D+T registration methods for DE-MRI cardiac perfusion studies

A series of motion compensation algorithms is run on the challenge data including methods that optimize only a linear transformation, or a non-linear transformation, or both ��� first a linear and then a non-linear transformation. Methods that optimize a linear transformation run an initial segmentation of the area of interest around the left myocardium by means of an independent component analysis (ICA) (ICA-*). Methods that optimize non-linear transformations may run directly on the full images, or after linear registration. Non-linear motion compensation approaches applied include one method that only registers pairs of images in temporal succession (SERIAL), one method that registers all image to one common reference (AllToOne), one method that was designed to exploit quasi-periodicity in free breathing acquired image data and was adapted to also be usable to image data acquired with initial breath-hold (QUASI-P), a method that uses ICA to identify the motion and eliminate it (ICA-SP), and a method that relies on the estimation of a pseudo ground truth (PG) to guide the motion compensation.

Temperature of solar cells with regard to photoactive and non-photoactive light absorption in concentrator PV modules

A new method has recently been proposed by us for accurate measurement of the solar cell temperature in any operational regime, in particular, at a maximum power point (MPP) of the I-V curve (T-p-n(MPP)). For this, fast switching of a cell from MPP to open circuit (OC) regime is carried out and open circuit voltage V-oc is measured immediately (within about 1 millisecond), so that this value becomes to be an indicator of T-p-n(MPP). In the present work, we have considered a practical case, when a solar cell is heated not only by absorption of light incident upon its surface (called "photoactive" absorption of power), but also by heat transferred from structural elements surrounding the cell and heated by absorption of direct or diffused sunlight ("non-photoactive" absorption of power with respect to a solar cell). This process takes place in any concentrator module with non-ideal concentrators. Low overheating temperature of the p-n junction (or p-n junctions in a multijunction cell) is a cumulative parameter characterizing the quality of a solar module by the factor of heat removal effectiveness and, at the same time, by the factor of low "non-photoactive" losses.

Piezoelectric sensing and non-parametric statistical signal processing for health monitoring of hysteretic dampers used in seismic-resistant structures

The paper proposes a new application of non-parametric statistical processing of signals recorded from vibration tests for damage detection and evaluation on I-section steel segments. The steel segments investigated constitute the energy dissipating part of a new type of hysteretic damper that is used for passive control of buildings and civil engineering structures subjected to earthquake-type dynamic loadings. Two I-section steel segments with different levels of damage were instrumented with piezoceramic sensors and subjected to controlled white noise random vibrations. The signals recorded during the tests were processed using two non-parametric methods (the power spectral density method and the frequency response function method) that had never previously been applied to hysteretic dampers. The appropriateness of these methods for quantifying the level of damage on the I-shape steel segments is validated experimentally. Based on the results of the random vibrations, the paper proposes a new index that predicts the level of damage and the proximity of failure of the hysteretic damper