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Las imágenes Synthetic Aperture Radar (SAR) del sensor Sentinel-1 complementan las posibilidades actuales que brindan los sensores remotos de información multiespectral, siendo principalmente útiles en áreas de alta nubosidad. Este estudio presenta la descripción de la dinámica espaciotemporal de un sistema de humedales tropicales denominado Ciénaga Colombia durante el periodo 2014-2021 a través de imágenes del sensor SAR Sentinel-1. Los datos se procesaron en Google Earth Engine (GEE) y se emplearon gráficos de cajas y bigotes para analizar la dispersión multitemporal de la retrodispersión del SAR. La lámina de agua superficial del sistema de humedales se calculó mediante los métodos de Umbrales y el Surface Water Index Extraction Model (SWIM), y se exploró su posible relación con la precipitación media anual y el El Niño Osciliación del Sur (ENOS). Los resultados indican la media del tamaño de la lámina de agua superficial de 109,96 ha en el 2015 y de 334,79 ha en el 2017. Los valores calculados para el 2017 con el SWIM y el método de umbrales distan casi en el doble para el mínimo de retrodispersión —384 ha y 657 ha, respectivamente—, aunque para esa temporalidad hubo ausencia de datos SAR. La consistencia de los resultados obtenidos a través de datos SAR se validó con valores del Normalized Difference Water Index (NDWI) provenientes de imágenes Sentinel 2-1C, y muestran coherencia en lo calculado. Finalmente, desde este estudio se reconoce la necesidad de profundizar en diferentes análisis para identificar los cambios en el sistema de humedales producto de las intervenciones directas sobre la red de drenaje en el que se encuentra.

Este artículo presenta los resultados del análisis polarimétrico, a través de una imagen de radar de apertura sintética (SAR) con cuatro polarizaciones utilizando la herramienta SAR polarimetry target analysis, realizado a las coberturas de la tierra obtenidas con la metodología Corine Land Cover y verificándolas con imágenes de sensores pasivos en un área de la sabana de Bogotá, como resultado del quehacer investigativo del Núcleo de Investigaciones en Datos Espaciales (NIDE)[1] y su semillero, Grupo de Investigaciones en Percepción Remota y Sistemas de Información Geográfica GEIPER[2], de la Universidad Distrital Francisco José de Caldas. Debido a las condiciones climáticas colombianas, que no permiten obtener datos de manera frecuente a partir de sensores pasivos para la generación y actualización de cartografía básica y temática, este grupo de investigación se ha visto en la necesidad de analizar y evaluar la utilización de fuentes de datos de sensores activos, como los radares, para garantizar la consecución de información necesaria para el monitoreo territorial, como los mapas de uso y cobertura de la tierra. Dentro de este contexto, las imágenes de radar de apertura sintética han venido siendo utilizadas por muchas instituciones internacionales y, con mucha menos asiduidad, por las nacionales, aplicando habitualmente una sola polarización, lo que genera mayor dedicación en los trabajos de campo y pos edición. Es precisamente la posibilidad actual de poder trabajar con cuatro polarizaciones lo que direccionó al equipo de trabajo a realizar un análisis de este tipo de imágenes adoptando uno de los sistemas de clasificación más utilizado en el país, el Corine Land Cover. Para ello, se escogen referentes teóricos polarimétricos y módulos de software comercial, como SAR polarimetry target analysis (SPTA) de Catalyst, una marca de PCI Geomatics. [1] https://comunidad.udistrital.edu.co/nide/ [2] https://comunidad.udistrital.edu.co/nide/semillero-geiper-percepcion-remota/

Since measurements such as meters (m), kilometers (km) or gallons (gal) of any object, substance or matter; man has sought systems that guarantee the accuracy of what he sells, buys, uses or consumes in his activities. The Colombian Air Force (FAC) is no exception; at the Colombian Air Force Non-Commissioned Officers School (ESUFA) there is a storage tank for Motor Fuel Oil (ACPM) that is used for the operation of the electric generator that supplies electric power to the ANTPS-70 radar. The measurement of ACPM consumption in gallons is done by hand. The operators use a gauging rod, which is inserted into the tank and, depending on how long it is wetted, allows them to estimate the number of gallons of fuel in the tank and use this data to estimate the number of gallons used. This procedure is carried out in each of the AN/TPS-70 type radars of the FAC military units. In the present investigation, a digital system for measuring the gallons of ACPM in the tanks was developed. The volume of the tank is established with the tank manufacturer's data. With an ultrasound sensor HC-SR04, which works by emitting an ultrasonic sound by one of its transducers, and waiting for the sound to bounce off the surface of the ACPM, the echo is captured by the second transducer. Thus, the height of the fuel (ACPM) inside the tank is obtained and a comparison table of height & volume is made, the Arduino UNO board is programmed and with this relationship the amount of gallons of ACPM contained in the tank is measured, which are transmitted wirelessly by a NRF24L01 module to the receiver where the amount of gallons is displayed on an LCD.

Introducción. Los sensores remotos ofrecen la capacidad de observar un objeto sin estar en contacto con el mismo, son utilizados en aplicaciones para la agricultura y tienen un gran potencial de desarrollo para el cultivo del banano (Musa AAA). Durante las últimas décadas las investigaciones en sensores remotos y agricultura se han incrementado gracias a la disponibilidad de imágenes satelitales de alta resolución y al uso de vehículos aéreos no tripulados que generan información base para las investigaciones. Objetivo. Realizar una revisión general sobre las aplicaciones del uso de sensores remotos para el cultivo del banano en tres aspectos específicos: determinación del área de cultivo, estimación de su productividad y en el diagnóstico de enfermedades. Desarrollo. Las áreas de plantaciones comerciales de banano son de fácil detección visual o por medio clasificaciones de imágenes, como con las imágenes del radar de abertura sintética (SAR), que pueden alcanzar presiones superiores al 95 %. Esto debido a la alta retrodispersión de las hojas grandes de la planta. No obstante, los estudios realizados en cuanto a productividad son escasos para el cultivo de banano y se han limitado al uso de índices de vegetación, con resultados bajos en sus correlaciones. En cuanto la identificación de enfermedades, se ha trabajado en las principales que afectan la producción con niveles de correlación superiores al 90 % para algunas enfermedades. Conclusión. La presente revisión evidencia que las plantaciones bananeras pueden ser delimitadas mediante el uso de sensores remotos y, de igual forma, estos permiten la identificación de las principales enfermedades en el cultivo. Sin embargo, los resultados obtenidos para determinar productividad son escasos y con poca precisión.

La interpolación espacial de las observaciones puntuales provenientes de estaciones meteorológicas es una manera recurrente de estimar la precipitación en un determinado sitio. Sin embargo, a medida que se incrementa la distancia al sitio puntual de medición estas estimaciones suelen diferir fuertemente en la cantidad de agua que realmente precipita. Los sensores remotos ópticos a bordo de satélites permiten incrementar la extensión espacial con una adecuada resolución temporal, sin embargo, presentan una baja resolución espacial. Los radares meteorológicos terrestres, por su parte, presentan mayor resolución espacial y temporal, aunque trabajos previos han demostrado un importante desfasaje entre los valores de precipitación estimados y los registrados en pluviómetros. Dada la limitada información puntual de precipitación y su variable distribución en el territorio, la identificación de campos de precipitación (es decir, el área donde efectivamente ocurre el evento precipitante) mediante los radares puede ser una importante alternativa para incrementar la precisión de las estimaciones basadas en interpolaciones convencionales. El objetivo de este trabajo fue delimitar los campos de precipitación a partir de la utilización de la red de radares meteorológicos del INTA con el fin de complementar las estimaciones de lluvia en grandes extensiones del territorio basadas en interpolaciones de datos puntuales. Para ello se consideró un período de análisis que incluyó los meses de octubre y noviembre de 2016 y un total de 8784 imágenes. Se realizó la interpolación espacial de los registros pluviométricos diarios medidos en estaciones meteorológicas y se utilizaron los radares meteorológicos para reconocer la distribución espacial de los eventos de precipitación, calculándose un umbral de detección de precipitación de 3,125 mm. Se delimitaron campos de precipitación y se generó el producto de “Interpolación Espacial utilizando Radar (IER)” a escala diaria y mensual. Se observó que solo en el 55% del área estudiada efectivamente acontecieron eventos de precipitación diaria, por lo que las interpolaciones espaciales convencionales generan una sobreestimación en el área de ocurrencia de este evento. Esto generaría una sobreestimación promedio del agua precipitada en el área de estudio de 91,1 mm y 35,2 mm para los meses de octubre y noviembre respectivamente, lo que podría afectar seriamente la toma de decisiones relacionadas con este recurso. El radar resultó ser una herramienta práctica y complementaria para la delimitación de aquellas zonas en las que se produjo el evento de precipitación y que resultan sobreestimadas por el registro discontinuo en las interpolaciones espaciales, aun más en zonas alejadas de las estaciones meteorológicas.

Current radars must meet the technological demands of today's world, which is why the modernization, replacement or design of any of its parts is a strategic step. The antenna unit does not escape this reality. In it, it is usual to find several blocks amoung which are the power dividers, especially in radars that use antenna array and in particular air exploration radar such as P18 and P12 use an unequal Wilkinson power divider at the center frequency of 160 MHz of the Very High Frequency (VHF) band with a power ratio at the ourput ports of 60%-40%. The calculation of the components is carried out in Mathcad and the lumped circuit is simulated in AWR Microwave Office. From the results, Return Loss (RL) of -45.18 dB, isolation between the output ports of -49dB and power ratio at the output of s31=-2.21dB and s21=-3.98 dB in ports 3 and 2 respectively.

Radar detection in environments with high spatial and temporal variability is an issue of great importance. Many efforts are devoted to the development of adaptive techniques that allow robust operation for all possible scenarios. Among the most widely used techniques in this context are those that changes the detection threshold adaptively in order to maintain a constant false alarm rate (CFAR). New CFAR detectors appear frequently, so it is useful the permanent update of the state-of-art in this topic. Therefore, this article presents the theoretical framework required by CFAR techniques, as well as a literature review in this matter. Furthermore, the application of non-coherent integration to CFAR detection is included as a distinctive element. Emphasis is made on three different scenarios: homogeneous clutter, multiple interfering targets and transitions in the clutter level. This review will be useful for researchers requiring a brief view of CFAR detection.

This paper deals with the design of two identical 1 × 4 patch antenna arrays for a linear frequency modulated (LFM) continuous wave (CW) synthetic aperture radar (SAR) prototype. The theoretical design is carried out by using the empirical equations available in the literature, while the design optimization is performed by numerical methods using two commercial full wave simulators. Once the antennas are built they are experimentally characterized and incorporated into a radar prototype implemented at the Ecuadorian Space Institute. The radar is tested in a probing polygon and the horizontal resolution is estimated. A measured azimuthal resolution value very close to the theoretical one is achieved

This paper describes the Butler Matrix’s state of the art in switched beam Smart antennas, as a result of the bibliographical revision of scientific articles, indexed journals, dissertations and books related to the subject. It describes the main advances and developments in its architecture, constituent components, successful implementations, problems and modern challenges from its invention, until the first decade of the 21st century. The document concludes with the awareness of the importance of the matrix, its validity and its relevance in the development of communications systems and radar.

A ¨RADAR¨ system, from the English Acronym ¨Radio Detention and Ranging¨. Better known as ¨Radio Detection and Location¨ RDL. It is a system for detecting and positioning objects through shipping and reflection of electromagnetic waves in terms of the time of issue and the return of the waves and their speed (calculated by the Doppler effect of the electromagnetic signal received). Meanwhile, an autonomous unmanned vehicle, also known as Unmanned Aerial Vehicle, UAV, which is defined as an aircraft which does not carry a human operator, and uses aerodynamic forces to provide airlift by itself. Therefore, it can fly autonomously or it can be operated by remote control. This article focuses on the review of experiences where these two technologies are integrated, particularly UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar). This is done in order to support research concerning the combination thereof to be applied in georeferencing humanitarian missions or military missions that require monitoring of airspace.

This paper proposes a radar-based sensing system that estimates the coordinates for shorelines based on image-processing techniques. The proposed system provides shore estimations without appreciable loss of resolution and avoids the costs associated with bathymetries and/or satellite images. The system is comprised of a commercial radar, a GPS, and a heading sensor, which communicates to a central node that georeferences the radar measurements and runs the image-processing algorithms. A dedicated FPGA-based unit is implemented to interface with the radar internal signaling to extract and deliver the radar information. In the central node, a novel mathematical model is proposed for georefencing radar measurements to WSG-84 coordinates. A seam-carving-like algorithm is applied over the estimated coordinates to create a shoreline based on a probability heat map. The system performance is validated using official geographical information, showing that a continuous shoreline can be generated with a CEP of up to 6 m without incurring elevated costs.

PAZ is a satellite with a highly flexible X band SAR as primary instrument. The radar is capable of generating high quality SAR images with sizes ranging from 5 km to 200 km and resolutions from 30 m for products with high coverage to values around 1m or even in the order of several cm in the case of very high resolution products. This paper describes the validation activities and the expected quality performances based on the tests performed on-ground.

En el presente trabajo se presenta una historia de la tecnología radar desde una perspectiva socio-técnica. Para ello se analizan los casos de desarrollo simultáneo durante la década de 1930 y hasta finales de la II Guerra Mundial en Alemania, Estados Unidos, Japón, la ex URSS y el Reino Unido. Se recurre al concepto de co-creación a fin de explicar cómo la tecnología y la sociedad se modelaron mutuamente y generaron diversos estilos tecnológicos vinculados al radar. El artículo, basado en fuentes secundarias, realiza un aporte sobre la historia de una tecnología sobre la cual existe escaso material en castellano.

Biomass is a very important forest resource in Andalusia. “Forest Biomass in Andalusia” web tool, developed by the Andalusian Government, provides information about the location and biomass stock for the main pine forest species. It is important to mention that information needs to be regularly, quickly, effectively and inexpensively updated. These requirements could be covered with the help of Earth Observation technologies. In this project, radar images have been acquired from ALOS-PALSAR sensor from different years (2008 and 2010) over two pilot areas located in Huelva. The aim of the study has been to develop a methodology to estimate wood volumes based on the statistic correlation between radar signal and wood volume, variable extracted of forest management plans contemporary to images. As result, correlations of 0.8 and 0.7 have been obtained for pine and eucalyptus respectively. Forest biomass has been calculated using species-specific allometric equations. Three key sources of information have been used: a sample of plots distributed homogeneously, an accurate digital terrain model and a current forest map. Furthermore, the study of the variability of estimated volumes between these dates has been carried out. Methodologies obtained could be extrapolated to the whole region.

Spatially explicit maps of wildlife habitat relationships have proven to be valuable tools for conservation and management applications including evaluating how and which species may be impacted by large scale climate change, ongoing fragmentation of habitat, and local land-use practices. Studies have turned to remote sensing datasets as a way to characterize vegetation for the examination of habitat selection and for mapping realized relationships across the landscape. Potentially one of the more difficult habitat types to try to characterize with remote sensing are the vertically and horizontally complex forest systems. Characterizing this complexity is needed to explore which aspects may represent driving and/or limiting factors for wildlife species. Active remote sensing data from lidar and radar sensors has thus caught the attention of the forest wildlife research and management community in its potential to represent three dimensional habitat features. The purpose of this review was to examine the applications of active remote sensing for characterizing forest in wildlife habitat studies through a keyword search within Web of Science. We present commonly used active remote sensing metrics and methods, discuss recent advances in characterizing aspects of forest habitat, and provide suggestions for future research in the area of new remote sensing data/techniques that could benefit forest wildlife studies that are currently not represented or may be underutilized within the wildlife literature. We also highlight the potential value in data fusion of active and passive sensor data for representing multiple dimensions and scales of forest habitat. While the use of remote sensing has increased in recent years within wildlife habitat studies, continued communication between the remote sensing, forest management, and wildlife communities is vital to ensure appropriate data sources and methods are understood and utilized, and so that creators of mapping products may better realize the needs of secondary users.

La cizalladura del viento a poca altura ha sido la causa de numerosos incidentes y accidentes de aviación. Este trabajo aborda el desarrollo de un método para el pronóstico a muy corto plazo de ocurrencia de cizalladura del viento a poca altura provocada por microcorrientes descendentes en el AeropuertoInternacional “José Martí” de La Habana. Utilizando el software Vesta Proceso para el análisis del radar meteorológico de Casablanca, así como de los anemómetros instalados en dicho aeropuerto, se identificaron los patrones de radioecos asociados con microcorrientes descendentes que producen rachas de viento por encima de 30 nudos. Para ello se analizaron las imágenes de radar meteorológico teniendo en cuenta la intensidad de los ecos en dBZ, la altura que alcanzan y la morfología de los mismos, así como la cercanía al aeropuerto y movimiento de las nubes cumulonimbo que pueden representar un peligro para este y las operaciones de tráfico aéreo. Se estableció un procedimiento para emitir alertas y alarmas de microcorrientes descendentes para el aeropuerto

The SON-9A radar was designed and built in the sixties at the non-existent Soviet Union and it was widely used in Vietnam’s War, however its technology is still employed for researching purposes. These systems could work fine under four frequencies from 2,700 up to 2,800 MHz with a frequency of repetition (PRF) of 1,707 Hz. The Group of Radar of the Telecommunications and Telematics Department, Cujae is carrying out the setting up and installation of an experimental radar using theSON-9A antenna. That is done in order to profit the tracking method of angular coordinates of this radar based on conical scanning and to can also effectuate polarimetric measurements of the echoes coming from the targets. The first step towards this modernization is to get a whole characterization of the antenna’s radiation pattern since it is only count on one bibliography and it’s in Russian language. It is needed to explain from a strictly technical point of view how the pattern behaves. To achieve this, the system has been modeled using the "CST Microwave Studio 2009" tool, which hasled to a fairly accurate idea of the device’s operation principle.

A utilização de imagens de radar é fonte alternativa de informações para subsidiar o monitoramento da região amazônica, visto que as imagens ópticas têm limitações de imageamento em zonas tropicais face a ocorrência de nuvens. Por conseguinte este trabalho teve como objetivo analisar a capacidade das imagens-radar de banda X multitemporais e polarizadas obtidas pelo satélite COSMO-SkyMed (COnstellation of small Satellites for Mediterranean basin Observation), no modo intensidade, isoladamente e agregados às informações texturais, na caracterização temática de uso e cobertura da terra no município de Humaitá/AM. A metodologia empregada consistiu da: análise das imagens duais obtidas em duas aquisições subsequentes, de forma a explorar a potencialidade do conjunto de dados na forma quad-pol intensidade; extração dos atributos texturais a partir da matriz de coocorrência (Gray Level Co-occurrence Matrix) e posterior classificação contextual; avaliação estatística de desempenho temático das imagens intensidade e texturais, isoladas e em grupos polarizados. Dentre os vários resultados alcançados, foi verificado que o grupo formado somente pelas imagens intensidade apresentou o melhor desempenho, comparado àqueles contendo os atributos texturais. Nesta separabilidade, estavam envolvidas as classes de floresta, floresta aluvial, reflorestamento, savana, pasto e queimada, obtendo-se 66% de acurácia total e valor Kappa de 0,55. Os resultados mostraram que as imagens de banda X do COSMO-SkyMed, modo StripMap (Ping-Pong), multipolarizadas, têm potencial moderado para a caracterização e monitoramento da dinâmica de uso e cobertura da terra na Amazônia brasileira.

In this paper is presented pulse compression technique in radar, focusing on Linear Frequency Modulation (LFM). Matched Filter characteristics are the elements considered for pulse compression, algebraic operations are derived to avoid the signal phase effect received by detection capacity. A hardware system for pulse compression in language description hardware is implemented. The product obtained is a first step in radar techniques to improve resolution capacity.

Taking The present article deals with the topic of windowing techniques for sidelobe reduction inlinearly frequency modulated (LFM) pulses compressed by an adapted filter. Main characteristics ofwindow´s techniques are presented; focusing on those that improves the window´s performance. Designsare simulated in a Graphic User Interface in MatLab and Simulink to conform it on FPGA. Simulationof carried out softwares allows the selection of the best choice as the case of interest.

Many researchers have shown the potential of Synthetic Aperture Radar (SAR) images for agricultural applications, particularly for monitoring regions with limitations in terms of acquiring cloud free optical images. Recently, Brazil and Germany began a feasibility study on the construction of an orbital L-band SAR sensor referred to as MAPSAR (Multi-Application Purpose SAR). This sensor provides L-band images in three spatial resolutions and polarimetric, interferometric and stereoscopic capabilities. Thus, studies are needed to evaluate the potential of future MAPSAR images. The objective of this study was to evaluate multipolarized MAPSAR images simulated by the airborne SAR-R99B sensor to distinguish coffee, cotton and pasture fields in Brazil. Discrimination among crops was evaluated through graphical and cluster analysis of mean backscatter values, considering single, dual and triple polarizations. Planting row direction of coffee influenced the backscatter and was divided into two classes: parallel and perpendicular to the sensor look direction. Single polarizations had poor ability to discriminate the crops. The overall accuracies were less than 59 %, but the understanding of the microwave interaction with the crops could be explored. Combinations of two polarizations could differentiate various fields of crops, highlighting the combination VV-HV that reached 78 % overall accuracy. The use of three polarizations resulted in 85.4 % overall accuracy, indicating that the classes pasture and parallel coffee were fully discriminated from the other classes. These results confirmed the potential of multipolarized MAPSAR images to distinguish the studied crops and showed considerable improvement in the accuracy of the results when the number of polarizations was increased.

O presente trabalho tem como objetivo analisar o potencial de imagens SAR polarimétricas do sensor TerraSAR-X, no modo StripMap, para mapear o uso e cobertura da terra na região sudoeste da Amazônia brasileira. No procedimento metodológico imagens de amplitude nas polarizações A HH e A VV, A derivada da matriz de covariância, bem como da entropia A Entropia derivada da decomposição de alvos por auto-valores fizeram parte, de forma individual ou combinada, do conjunto de dados investigados. Na classificação das imagens foram empregados dois classificadores: um baseado nas funções estatísticas de máxima verossimilhança (MAXVER); e outro, o método contextual (Context). Os resultados temáticos dessas classificações foram avaliados através da matriz de confusão e pelo índice Kappa. De forma sintetizada pode-se afirmar que as componentes A e A Entropia, têm significativa contribuição no procedimento classificatório, sobretudo pelo método Context, cujo desempenho alcançou com 78% de exatidão global e índice Kappa de 0,70.The objective of this work was to analyze the potential use of SAR polarimetric images from the TerraSAR-X sensor system, at StripMap mode, to map land use and land cover in SW Brazilian Amazon. Amplitude images at polarizations A HH, A VV, A, derived from the co-variance matrix, as well as the entropy A Entropia, derived from the decomposition of targets by eigenvalues, are parts of the datasets investigated individually or in combined form. Two classifiers were used: the first is based on statistical functions of maximum likelihood (MAXVER), and the second is the contextual method (Context). The thematic results from these classifications were evaluated by a confusion matrix and by the Kappa index. Summarizing we can state that the components A and A Entropia, gave a significant contribution to the image classification procedure, considering specially the Context method, whose performance reached 78% of Global Accuracy and a Kappa index of 0.70.

This study comes from four years (2006–2009) of monitoring on two sites during the prenuptial migration. On each site, a monitoring of 24 hours per each 10–day period from the second 10–day period of January (J2), though February (F1–F3) and March (M1–M3), up to the first 10–day period of April (A1). Monitoring was carried out by RADAR (FURUNO FAR2127), associated with nocturnal bioacoustics recordings, and visual censuses on the same areas. The monitoring effort was considerable: visual counts carried out represent 282 counts–sites (n = 262,030 ducks counted), bioacoustics detected 9,573 calls during 814 hours of nocturnal recording and RADAR recorded 67,368 echoes on a set of 2,128 hours of monitoring. Visual counts showed a decline in the number of birds from late January/early February. Two patterns were observed with the nocturnal recordings with a maximum or a minimum of the value of bioacoustics index on F2 and F3, depending on the years. RADAR, the most relevant method for tracking of bird movements at a population level, identified two different abundance peaks using variables ‘flight altitude > 400 m’ and ‘flight direction towards north–east/south–east’, considered as characteritics of the prenuptial migration. The first peak was detected during F1 on Site 1 only in 2007 (once every four years) and during F2 on Site 2 only in 2006 (once every four years). A second peak with a higher number of echoes was recorded on M1 (Site 1) and on M2 (Site 2). Although all methods may suffer from different biases, the combination of two new technologies complementary to visual counts provided reliable and updated data for waterfowl migration in the Mediterranean area.

Este artículo habla de la experiencia de Thomas Kuhn como físico: su educación en la disciplina, su servicio como experto durante la Segunda Guerra Mundial, y su investigación doctoral. Estudiamos un lapso de tiempo que va de 1940 a 1951. El objetivo en última instancia es ofrecer base empírica para valorar una afirmación como la de Mara Beller (1999), que dice que la descripción kuhniana de la ciencia normal está parcialmente basada en circunstancias y experiencias personales, no sólo en los datos históricos o en la evidencia disponible de la sociología de la ciencia. En este artículo se establece que dicha tesis es plausible.

Se considera que el radar es un buen instrumento de medida, aunque sus aplicaciones en actividad física y deporte son escasas. El presente estudio trata de validar un protocolo de medición basado en el radar comparándolo con un criterio de referencia utilizado habitualmente (fotogrametría), en este caso aplicado a la velocidad en el golpeo en fútbol. Para ello, cuatro jugadores de fútbol experimentados participaron de forma voluntaria en el estudio, realizando un total de 100 golpeos de balón. La velocidad de los mismos fue medida a través del radar Stalker PRO® y el protocolo de medición fue validado mediante un sistema de fotogrametría con el software Kinescan/IBV® 2001. Para cuantificar la relación entre los dos métodos de medición empleados se aplicó el coeficiente de correlación de Pearson (Rxy = 0,998; p

Um dos fatores que influencia diretamente no desempenho de sistemas mecanizados é a velocidade de deslocamento pela sua importância no planejamento e na execução das operações agrícolas. O objetivo deste trabalho foi avaliar a acurácia de quatro sensores de velocidade, em condições de superfície asfáltica, solo com cobertura vegetal, aclives e declives, acelerações e desacelerações, submetidos a velocidades representativas para aplicações agrícolas. Foram ensaiados dois modelos comerciais de sensores de radar, um sensor de GPS e um sensor óptico. Foram identificadas diferenças significativas para as situações de solo com cobertura vegetal, acelerações e desacelerações. Para a superfície asfáltica, em situação de velocidade constante, os sensores avaliados não apresentaram desempenho com diferença significativa. Os sensores tipo radar demonstraram ser influenciados pela superfície com cobertura vegetal. Na superfície asfáltica, sob condições de aceleração e desaceleração, o sensor de GPS apresentou retardo nos valores de velocidade quando comparado com os demais.One of the factors that influence directly the performance of mechanized systems is the forward speed that is important on planning and managing agricultural operations. The objective of this work was to evaluate the accuracy of four speed sensors, on paved road, vegetated surface, hills, increasing and reducing representative speeds for agricultural applications. Two commercial radars, a GPS sensor and an optical sensor were tested. For the paved road surface, under constant speed, no significant differences were observed on the performance. Radars were influenced by the vegetated surface. On paved road and under acceleration and deceleration the GPS sensor presented delay on its speed values when compared with the other sensors.

En un ambiente FOXPLUS fue confeccionado un sistema automatizado para el procesamiento y observación de ecos de aves detectados por radar sobre las provincias habaneras (Cuba) durante el período migracional. Para obtener el articulo completo pueden contactar al Editor de la Revista Ecosistemas y Recursos Agropecuarios en el siguiente correo electrónico era@ujat.mx y se les enviará sin algún costo.

RESUMEN En edificios históricos son conocidos los efectos nocivos de la presencia de humedad en muros, que deteriora detalles de ornamentación, conjuntamente con los componentes de la mampostería que conforma su propia estructura. Es el caso de la Iglesia Nuestra Señora de la Viña (Salta, Argentina), edificio del s. XIX que presentaba manifestaciones patológicas características de las producidas por la presencia de humedad ascendente. Las tareas de recuperación de las superficies exteriores fueron realizadas una vez que el sistema instalado (por electrólisis) deshumidificó los muros. La elevada inversión realizada requiere de un control periódico de la eficacia del sistema. En este trabajo se presentan los fundamentos y los resultados obtenidos con el empleo de georradar como recurso no destructivo para controlar el sistema de deshumidifación, cuya principal ventaja es la de poder detectar en forma precoz a lo largo del tiempo alguna falla en el sistema, evitando en forma indefinida la aparición de nuevas manifestaciones patológicas por humedad ascendente. Palabras clave: patología; mampostería; humedad; radar. ABSTRACT In historical buildings the harmful effects in masonry due to moisture are well known, as it affects ornamentation and the components of the masonry which is also the building’s structure. That is the case of the church Nuestra Señora de la Viña (Salta, Argenti na), a XIX cent. building which presented typical pathological symptoms caused by rising damp. An electro physical system was installed in order to dehumidificate the masonry and external surfaces were subsequently recovered. This high investment requires a periodical control of the system’s efficiency. This article presents the foundations of and the results obtained by using an impulse radar as a non-destructive resource to control the dehumidification system. Its main advantage is the early detecting of a failure in the system and so avoiding new pathological symptoms caused by rising damp. Keywords: Pathology masonry; moisture; radar.

Orbital remote sensing in the microwave electromagnetic region has been presented as an important tool for agriculture monitoring. The satellite systems in operation have almost all-weather capability and high spatial resolution, which are features appropriated for agriculture. However, for full exploration of these data, an understanding of the relationships between the characteristics of each system and agricultural targets is necessary. This paper describes the behavior of backscattering coefficient (sigma°) derived from calibrated data of Radarsat images from an agricultural area. It is shown that in a dispersion diagram of sigma° there are three main regions in which most of the fields can be classified. The first one is characterized by low backscattering values, with pastures and bare soils; the second one has intermediate backscattering coefficients and comprises well grown crops mainly; and a third one, with high backscattering coefficients, in which there are fields with strong structures causing a kind of double bounce effect. The results of this research indicate that the use of Radarsat images is optimized when a multitemporal analysis is done making the best use of the agricultural calendar and of the dynamics of different cultures.

Este estudo apresenta uma abordagem metodológica baseada em imagens de radar e nos critérios de tonalidade, tamanho e forma geométrica para identificar prováveis pistas de pouso não-homologadas na Amazônia. Os seguintes procedimentos foram conduzidos: georreferenciamento da imagem do sensor SAR-R99B do município paraense de Itaituba, adquirida na banda L, polarização HH e resolução espacial de três metros; subtração do ruído speckle com filtro mediana; classificação com a técnica não-supervisionada ISODATA; vetorização da classe indicativa dos alvos de interesse; e cálculo e seleção automática dos alvos de interesse por critérios de índice de circularidade e de tortuosidade. Foram identificados dez alvos, dos quais dois foram considerados como prováveis pistas de pouso pelos referidos índices.This study presents a methodological approach based on radar images and on gray level, size and geometric pattern to identify potential unofficial airplane strips in Amazonia. The following procedures were conducted: georeferencing of a L-band, HH polarization, 3-meter spatial resolution image obtained by the SAR-R99B system over the Itaituba municipality, State of Para; subtraction of speckle noise with a median filter; image classification with the ISODATA unsupervised technique; conversion of selected targets of interest into vector format; and calculation and automatic selection of targets of interest by the circularity and tortuosity indices. Among the 10 previously identified targets, two were considered as potential unofficial airplane strips by the above mentioned indices.

Using high-frequency radars, ocean surface currents were mapped every hour over an area of ≈5000 km2 in the inner Gulf of Tehuantepec (Mexico). The coastal circulation patterns (≈100 km offshore) were studied during spring, summer, and autumn 2006. The spring circulation was similar to the typical winter circulation, when the circulation is forced by outbursts of northerly winds (>8 m s–1) known locally as Tehuanos. Although Tehuano events are less common in spring than in winter, they are perfectly capable of modifying the sea surface by triggering cyclonic and anticyclonic eddies (≈50–200 km in diameter). Under moderate wind conditions, the ocean circulation showed a quasipermanent westward coastal current (≈50 cm s–1). Though the Tehuano winds were absent in summer, cyclonic eddies were observed and likely linked to the westward coastal current. Autumn was influenced by steady northerly winds with speeds of ≈12 m s–1 that remained over the region for almost 15 days. These conditions allowed us to study the competition between the wind-induced circulation and the more intense (≈100 cm s–1) westward coastal current during this period. The origin of this coastal current could be related to a warm coastal-trapped flow, composed of tropical low-salinity waters. The northwestward excursion of the observed coastal current is discussed, and the three-dimensional implications of surface current fields are studied by the Ekman theory and vorticity conservation.

En el presente trabajo se desarrolla un estudio sobre el comportamiento y carácter del estado de la superficie marina, que son generados por diferentes fenómenos meteorológicos de escala sinóptica y dan lugar a inundaciones costeras en el litoral de la Ciudad de La Habana. Con la información que se obtiene a través de la identificación de imágenes radáricas del patrón de radioecos característicos del oleaje, el cuál adopta la forma de un abanico desplegado, se determina­ron las magnitudes de las distancias radiales máximas y mínimas sobre el indicador de un radar meteorológico convencional. Así se logra establecer la relación entre las variables radáricas y el alcance de las inundaciones costeras por penetración del mar. Se diseñó una metodología observacional para el radar meteorológico de Casa Blanca y, por primera vez, se obtuvo un programa operacional para el pronóstico a muy corto plazo del alcance de las inundaciones costeras por penetración del mar en zonas del malecón habanero. Se sugiere el empleo de los radares meteorológicos convencionales como una herramienta útil para realizar la vigilancia, el diagnóstico y el pronóstico a muy corto plazo de inundaciones costeras por penetración del mar.