Procesamiento de señales de radar en presencia de clutter dinámico

El radar es un sistema de sensado remoto que utiliza técnicas de procesamiento estadístico de señales para obtener información de la señal recibida. Los radares convencionales son sistemas activos que operan transmitiendo energía en forma de ondas electromagnéticas y recibiendo las señales reflejadas por el entorno y el objeto iluminado. Una de las dificultades a tener en cuenta en los sistemas de radar es que la señal de interés suele encontrarse obscurecida por las reflexiones producidas por el ambiente, fenómeno al que se denomina {\it clutter}. Generalmente, y dependiendo de la aplicación, el clutter es considerado una fuente de interferencia y perturbaciones cuyos efectos se deben eliminar o reducir. Por lo tanto, en vista de su naturaleza aleatoria, es importante el desarrollo de métodos estadísticos de procesamiento de señales para poder detectar objetivos y estimar sus propiedades en situaciones de clutter intenso y dinámico. Para obtener algoritmos eficientes, es fundamental utilizar modelos realistas de las señales recibidas por el radar. Estos modelos deben enfatizar las diferencias entre el objeto de interés y el clutter. De esta forma, los métodos de procesamiento de señal son usados para separar el objetivo del clutter y reducir el efecto degradante de este último. En esta tesis se aborda el problema de detección en presencia de clutter dinámico para aplicaciones de radar. En especial se desarrollan modelos que contemplan las variaciones del escenario y utilizan la historia del clutter para mejorar su caracterización en el instante actual y las predicciones a tiempo futuro. La primera alternativa considera el clutter como una serie temporal que presenta heteroscedasticidad condicional autorregresiva generalizada, utilizando los denominados procesos GARCH. Este tipo de procesos poseen la característica de ser impulsivos, pero presentan la desventaja de que no cuentan con una expresión explícita para su función densidad de probabilidad. Por este motivo, se analizan alternativas para estimar sus parámetros y determinar la calidad de la estimación. Asimismo, se adaptan los test de hipótesis usuales para deducir un esquema de detección basado en el modelo GARCH. Con el fin de incorporar información de múltiples pulsos en los instantes de decisión, se extiende el modelo anterior combinando un proceso GARCH en dos dimensiones (GARCH-2D) con un proceso autorregresivo (AR) y se deriva el detector correspondiente para este modelo de clutter. La parte GARCH-2D del modelo preserva la propiedad impulsiva de los procesos GARCH y la AR en las innovaciones permite modelar la correlación pulso a pulso que existe en los datos. En ambos casos se deducen expresiones para las probabilidades de falsa alarma y, dada su complejidad matemática, la probabilidad de detección se evalúa por medio de simulaciones numéricas. Además, se analiza la sensibilidad del desempeño de los detectores ante errores en la estimación de sus parámetros. A pesar de que no resultan de tasa de falsa alarma constante, muestran un comportamiento robusto en situaciones prácticas. Por último, el desempeño de los detectores propuestos es comparado con algoritmos de detección existentes en la literatura utilizando mediciones reales de clutter marítimo. Los resultados muestran que presentan un mejor desempeño respecto de los demás detectores, es decir, una probabilidad de detección mayor para una tasa de falsa alarma menor, independientemente de la relación señal a clutter. Finalmente se estudia el problema de estimación secuencial de los parámetros de los procesos GARCH. Si bien de los análisis de sensibilidad se concluye que en los detectores porpuestos no es necesaria una actualización frecuente de los mismos, su estimación es la etapa de mayor costo computacional en los esquemas de detección propuestos. Siguiendo el enfoque de estimación Bayesiano se deduce un estimador lineal de mínimo error cuadrático medio para la varianza condicional de los procesos GARCH, que es el parámetro del cual depende el estadístico de los detectores desarrollados. La deducción del algoritmo es análoga a la del filtro de Kalman, pero en este caso las matrices del sistema son aleatorias.Facultad de Ingenierí

Weather radar signal processing

En el año 2011 se lanzó el Sistema Nacional de Radares Meteorológicos (SINARAME), el que es operado por el Servicio Meteorológico Nacional, con el objetivo de desplegar una red de radares meteorológicos. En este contexto se encomendó a la empresa INVAP, la fabricación y puesta en funcionamiento de una red de radares de última generación. Hasta el momento se instalaron siete nuevos radares en distintos puntos del país y se proyecta que se sumen al menos tres a los existentes.Las variables meteorólogicas se obtienen a partir de los momentos espectrales de la señal que mide el radar, resultado de las reflexiones de la señal transmitida en el fenómeno atmosférico. Dicha señal suele estar contaminada por interferencia, lo que degradada la estimación de las variables. El objetivo general del presente proyecto consiste en el procesamiento estadístico de las señales de radar meteorológico, en pos de mitigar el efecto degradante de la inteferencia y mejorar la calidad de los observables en los que los meteorólogos basan su trabajo. En especial se desean mitigar los efectos del clutter terrestre y de la interferencia producida por las redes WLAN/RLAN que operan en la banda C.Se trabajará en el modelado de las señales propias del radar, utilizando modelos estadísticos que ajusten a las mediciones del radar. Se desarrollarán métodos de estimación de los momentos espectrales. Se propondrán técnicas de filtrado adaptivo, de modo de eliminar las señales interferentes o bien reducir su efecto sobre la señal deseada. Los objetivos serán contemplados tanto en el modo de operación estándar del radar como en el modo staggered. En todos los casos se verificará el funcionamiento de los métodos propuestos por medio de simulaciones y luego se evaluarán sus desempeños empleando datos reales. Finalmente, se migrarán los algoritmos a procesamiento paralelo con GPU para su empleo en tiempo real.El presente proyecto persigue el desarrollo y la utilización de conocimientos en el campo del medio ambiente. Es importante destacar que el objetivo final subyacente consiste en arribar a pronósticos certeros para emitir alertas tempranas y llevar a cabo planes de contingencia en localidades proclives a sufrir catástrofes naturales o bien frente a fenómenos climáticos que afectan las actividades económicas del país, tales como la agricultura. Se espera contribuir para mejorar el desempeño de la etapa de procesamiento de los radares meteorológicos nacionales.In the year 2011 the Argentinian National Wheather Radar System (SINARAME) was created, it is operated by National Weather Service, with the aim of deploying a network of weather radars. In this context, the manufacturing and starting up of a latest generation weather radars network was delegated to the INVAP company. Until now seven new radars were installed in different locations of the country and at least three radars more will be installed. Weather variables are obtained from the spectral moments of the signal acquired by the weather radar, which results from the backscattering of the transmitted electromagnetic waves by atmospheric phenomenon. The radar received signal often is contaminated by interference, which degrades the weather variables estimation. The general objective of the project is the statistical processing of weather radar signals, in order to mitigate the interference effect and to improve the quality of the variables that the meteorologists uses to make weather forecasts. Specifically, are wanted to mitigate the effects of the ground clutter and of the interference due to WLAN/RLAN that operates at C band. We will model the weather radar signals by means of statistical models that fit the radar measurements. Throughout the the project, we will model the weather radar signals by means of statistical models that fit the radar measurements. We will develop spectral moments estimation methods. We will propose adaptive techniques to filter the interferences and to reduces their effect on the desired signal. We will consider the standard mode operation radar and also the staggered operation mode. In all cases we will verify the proposed methods operation by means of numerical simulations and we will evaluate their performance using radar measurements. Finally, we will implement the algorithms in a specialized software to process the data in parallel in a graphics processing unit (GPU), intended to serve real-time applications. This project attempts to use the knowledge in the field of the environment. It is important to note that the underlying objective consist in getting accurate short term forecasts to issue early warnings and carry out contingency plans in cities prone to natural catastrophes or for extreme climatic phenomena that affect the economic activities of the country, such as agriculture. It is expected to improve the performance of the signal processing stage of national weather radars

Advanced driver assistance system based on computer vision using detection, recognition and tracking of road signs

Los accidentes de tráfico son un grave problema socioeconómico. Obviamente el coste humano es imposible de evaluar y el económico supone un continuo e ingente gasto de dinero por parte de los gobiernos. Se han propuesto diferentes soluciones para paliar los efectos de los accidentes, una de las cuales, los Sistemas Avanzados de Ayuda a la Conducción, son el marco en el que se encuadra el presente trabajo. Estos sistemas, como su nombre indica, asisten al conductor ofreciéndole información del entorno o actuando en determinadas circunstancias para la salvaguarda de los ocupantes del vehículo, o para facilitar la conducción. El sistema que se propone en esta tesis es una plataforma multipropósito original en su concepción, cuyo fin más inmediato es reconocer las señales de tráfico de prohibición, peligro, ceda el paso, obligación e indicación. La información obtenida de ese reconocimiento se integra dentro de un módulo de aviso al conductor. Lo que se pretende es que el conductor conozca en todo momento si está contraviniendo alguna norma de circulación derivada de una velocidad o maniobra inadecuada para el tipo de señal que se ha reconocido. Dado que este sistema está embarcado en un vehículo, deberá cumplir dos requisitos de especial importancia: funcionar en tiempo real y tanto en entorno urbano como en autopista. El primero cobra especial relevancia si se piensa en que la seguridad de los ocupantes del vehículo y de los peatones puede depender de los avisos que permitan al conductor anticiparse a un peligro. La segunda, que es una aportación original, garantiza que el sistema funcionará en vías donde la velocidad es mayor y por tanto también la probabilidad y gravedad de un posible accidente. El sistema, como se decía anteriormente, sirve al desarrollo de otras aplicaciones, como es el caso del inventariado automático de señales de tráfico, tan en auge actualmente. ______________________________________________Road traffic accidents are a serious socio-economic problem, where the cost of human life is impossible to evaluate, and cause massive and continuous government spending. Different solutions have been proposed to reduce the effects of accidents, one of which, Advanced Driver Assistance Systems, forms part of the framework which encompasses the current investigation work presented in this thesis. These systems, as their name suggest, assist the driver by providing vital information on the traffic environment or by acting under speciffic circumstances to safeguard the occupants of the vehicle, or to facilitate driving. A multitask driver assistance platform is originally presented as part of the research work of this thesis, among other tasks, it has been designed to recognize road signs in both urban and non-urban environments. The road signs that have been considered are: prohibition, danger, yield, obligation and indication. The information obtained from the road sign recognition process forms part of a complete module that advises drivers on traffic circulation requirements. The primary objective of this work has been to increase driver awareness, at all times, on the legal limitations which have established for road safety. The two areas which have been considered in this thesis are the velocity of the vehicle and the velocity of the vehicle corresponding to incorrect driving manoeuvres both of which are controlled using the information contained within road signs. The assistance platform which has been designed forms an integral part of the vehicle, thus it must satisfy two important requirements: first, provide the driver with real time information from road signs and secondly, to operate in both urban and non-urban environments. Real time information is important for the safety of drivers, passengers, and pedestrians where the information provided warns the driver well in advance of any danger so that the appropriate manoeuvres can be made to correct the speed of the vehicle. One important aspect of the work presented here is that the system has also been designed for non-urban environments, such as: national roads, toll roads and motorways where there is a higher probability of more serious and fatal accidents occurring due to the increased speed. There is a wide range of possible applications for road sign recognition systems, another area of interest which has motivated the work carried out for this thesis has been an automatic road sign inventory system. From the beginning of research in automatic road sign detection applications, many di®erent stages have been proposed, such as: signal detection, road sign recognition, and road sign tracking. The work presented in this thesis provides an in depth analysis of each of these three stages and this has allowed a more robust and complete system to be designed. In this thesis an exhaustive review is presented on color spaces and their characteristic color components which are best suited to the task of searching for road signs within an image. The technique of template matching using patterns with road signs has been optimized in this research, also included is an analysis of the most adequate models required to effciently detect each type of road sign. As part of the development of the recognition stage of the system, the two currently most important tools used in object recognition have been studied, these are: template matching and neural networks (NN). A comparative analysis of both of these techniques has been performed, where emphasis has been placed on image preprocessing to optimize the results. The final stage of this system addresses the problem of road sign tracking. The method proposed is a model based on the movement of the camera within the vehicle with respect to the road sign which is taken as the reference point. All the different stages of the system, which have been developed, form part of an experimental platform used on-board a test vehicle. To investigate the viability of this system the experimental trials have been carried out under real conditions. This methodology has been used for each stage, and the results presented corroborate the advantages and effectiveness of a multitask driver assistance platform

Enhanced fault characterization by using a conventional OTDR and DSP techniques

To plan a rapid response and minimize operational costs, passive optical network operators require to automatically detect and identify faults that may occur in the optical distribution network. In this work, we present DSP-Enhanced OTDR, a novel methodology for remote fault analysis based on conventional optical time-domain reflectometry complemented with reference traces and DSP-based techniques. We first obtain the optimal decision thresholds to detect deviations in the noisy OTDR measurement. In order to quantify and characterize the fault, the detection stage is followed by one of estimation where its return loss and insertion loss are determined. We experimentally demonstrate that this approach allows to detect and characterize faults with an accuracy higher than that found in conventional OTDR trace analysis. In our experiments, we achieved detection sensitivities higher than 0.2 dB in a 1:16 split-ratio PON, and higher than 1 dB in a 1:64 split-ratio PON, achieving estimation errors that can be as low as 0.01 dB. We also verified how the optical network terminal's reflectivity can improve the detection capabilities.Fil: Fernández, Manuel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Bulus Rossini, Laureano Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Pascual, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Costanzo Caso, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; Argentin

Selection of rail improvement projects using the Analytic Network Process

Trabajo presentado al XI International Symposium on the AHP celebrado en Nápoles (Italia) del 15 al 18 de Junio de 2011.In this artiele the applieation of the Analytie Network Process (ANP) to establish priorities arnong the portfolio of rail infrastructure rnaintenance, rehabilitation and improvernent projects in the area of Valencia (Spain) is presented. The problem is complex because of the large number and variety of projects to be considered and the great number of criteria that must be taken into account in the decision analysis process. The present work is a continuation of a previons research hased on the AHP model. The present study analyzes the different priority values of a particular group of projects obtained in ANP and AHP as well as changes in the weigbts of the criteria and the possibility of eliminating minor criteria from the model for the sake of simplicity.Peer Reviewe

Testing a Recent DEMATEL-Based Proposal to Simplify the Use of ANP

[EN] The Analytic Network Process (ANP) is a well-known multi-criteria decision method that allows the relationships between its elements to be incorporated into the model. The large number of questions to be answered is one of the main drawbacks of the method, since it is time consuming for decision makers and experts who participate in the decision process. A recent DEMATEL-based ANP proposal can significantly reduce the number and the complexity of questions. This proposal was simply exposed and lacked an experimental test with real cases. The fundamental objective of this work is to answer the question: Does it work? In this work, this new proposal is applied to 45 ANP cases published in the literature. Variants to the verified proposal have also been identified. The results obtained show that the values of the priorities and the ranks obtained with this new proposal are very similar to the results obtained with the ANP, reducing the number of questions required by 42% on average. Additionally, in this work you can find the compilation of the 45 ANP weighted supermatrices to use in your investigations.Schulze-González, E.; Pastor-Ferrando, J.; Aragonés-Beltrán, P. (2021). Testing a Recent DEMATEL-Based Proposal to Simplify the Use of ANP. Mathematics. 9(14):1-23. https://doi.org/10.3390/math9141605S12391

Selection of maintenance, renewal and improvement projects in rail lines using the analytic network process

[EN] This paper addresses one of the most common problems that a railway infrastructure manager has to face: to prioritise a portfolio of maintenance, renewal and improvement (MR&I) projects in a railway network. This decision-making problem is complex due to the large number of MR&I projects in the portfolio and the different criteria to take into consideration, most of which are influenced and interrelated to each other. To address this problem, the use of the analytic network process (ANP) is proposed. The method is applied to a case study in which the Local Manager of the public company, who is responsible for the MR&I of Spanish Rail Lines, has to select the MR&I projects which have to be executed first. Based on the results, it becomes evident that, for this case study, the main factor of preference for a project is the location of application rather than the type of project. The main contributions of this work are: the deep analysis done to identify and weigh the decision criteria, how to assess the alternatives and provide a rigorous and systematic decision-making process, based on an exhaustive revision of the literature and expertiseThe translation of this paper was funded by the Universitat Politecnica de Valencia.Montesinos-Valera, J.; Aragonés-Beltrán, P.; Pastor-Ferrando, J. (2017). Selection of maintenance, renewal and improvement projects in rail lines using the analytic network process. Structure and Infrastructure Engineering. 13(11):1476-1496. https://doi.org/10.1080/15732479.2017.1294189S147614961311Abril, M., Barber, F., Ingolotti, L., Salido, M. A., Tormos, P., & Lova, A. (2008). An assessment of railway capacity. Transportation Research Part E: Logistics and Transportation Review, 44(5), 774-806. doi:10.1016/j.tre.2007.04.001Ahern, A., & Anandarajah, G. (2007). 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Late reproductive senescence in a rabbit line hyper selected for reproductive longevity, and its association with body reserves

The aim of the present study was to investigate differences in reproductive and body traits during successive parities between two genetic lines. The LP line was constituted by means of selection of animals having an extremely high number of parities (at least 25) and an average reproductive performance compared to the V line selected for litter size at weaning during 31 generations. The two lines were found to have an equal reproductive performance in the first three parities, but the LP line had higher reproductive performance from the fourth parturition onwards. The low reproductive performance after the third parity in the V line was suggested to be caused by constrained environmental conditions in the test station. A line by parity interaction was also observed for body weight, since body weight declined going from the third to the fourth parity in the LP line but not the V line. Thus, it was concluded that hyper selection for reproductive longevity and average prolificacy successfully delayed reproductive senescence, and that this newly founded line showed less environmental sensitivity, which might have been mediated by a higher body reserve

Nematicidal activity of essential oils and organic amendments from Asteraceae against root-knot nematodes

The essential oil of Chrysanthemum coronarium flowerheads showed strong nematicidal activity in vitro and in growthchamber experiments. Essential oil concentrations of 2, 4, 8 and 16 μL mL−1, significantly reduced hatch, J2 survival (determined by final value and area under curves of cumulative percentage hatch or mortality) and reproduction rate of Meloidogyne artiellia in vitro, with the lowest values occurring at 16 μL mL−1. In pot trials with chickpea cv. PV 61, essential oil concentrations of 10–40 μL per 500 cm3 soil, applied on sterile cotton pellets, also significantly reduced the nematode’s reproduction rate. The biological processes of mortality and hatching/reproduction were adequately described by the monomolecular and expanded negative exponential models, respectively. Effectiveness of soil amendment with either flowers, leaves, roots or seeds of C. coronarium, and flowers from several species of Asteraceae (Chrysanthemum segetum, Calendula maritima, Calendula officinalis and Calendula suffruticosa) at 5 g per 500 cm3 soil was tested for suppression of M. artiellia and growth of chickpea cv. PV 61 under growth-chamber conditions. In these tests, flowers of all five Asteraceae species and various parts of C. coronarium significantly reduced reproduction rates of M. artiellia, by 83·0–95·9%, with the minimum rates occurring in infected chickpea plants amended with flowers of C. officinalis and C. suffruticosa. The in vitro and in planta results suggest that the essential oil of C. coronarium and organic amendments from Asteraceae species may serve as nematicides.This research, part of a PhD study by P.P., was supported by grant SC98-022 and a fellowship from the Instituto Nacional de Tecnologías Agroalimentarias (INIA).Peer reviewe