150 research outputs found

    IXPE Mission System Concept and Development Status

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    The Goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mi SMEX), is to expand understanding of high-energy astrophysical processes and sources, in support of NASAs first science objective in Astrophysics: Discover how the universe works. IXPE, an international collaboration, will conduct X-ray imaging polarimetry for multiple categories of cosmic X-ray sources such as neutron stars, stellar-mass black holes, supernova remnants and active galactic nuclei. The Observatory uses a single science operational mode capturing the X-ray data from the targets. The IXPE Observatory consists of spacecraft and payload modules built up in parallel to form the Observatory during system integration and test. The payload includes three X-ray telescopes each consisting of a polarization-sensitive, gas pixel X-ray detector, paired with its corresponding grazing incidence mirror module assembly (MMA). A deployable boom provides the correct separation (focal length) between the detector units (DU) and MMAs. These payload elements are supported by the IXPE spacecraft which is derived from the BCP-small spacecraft architecture. This paper summarizes the IXPE mission science objectives, updates the Observatory implementation concept including the payload and spacecraft ts and summarizes the mission status since last years conference

    JPSS-1/NOAA-20 VIIRS Early On-Orbit Geometric Performance

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    The first NOAA/NASA Join Polar Satellite System (JPSS-1) satellite was successfully launched on November 18, 2017,becoming NOAA-20. Instruments on-board the NOAA-20 satellite include the Visible Infrared Imaging RadiometerSuite (VIIRS). This instrument is the second build of VIIRS, with the first flight instrument on-board NASA/NOAASuomi National Polar-orbiting Partnership (SNPP) satellite operating since October 2011. The purpose of these VIIRSinstruments is to continue the long-term measurements of biogeophysical variables for multiple applications includingweather forecasting, rapid response and climate research. The geometric performance of VIIRS is essential to retrievingaccurate biogeophysical variables. This paper describes the early on-orbit geometric performance of the JPSS-1/NOAA-20 VIIRS. It first discusses the on-orbit orbit and attitude performance, a key input needed for accurate geolocation. Itthen discusses the on-orbit geometric characterization and calibration of VIIRS and an initial assessment of thegeometric accuracy. It follows with a discussion of an improvement in the instrument geometric model that correctssmall geometrical artifacts that appear in the along-scan direction. Finally, this paper discusses on-orbit measurements ofthe focal length and the impact of this on the scan-to-scan underlap/overlap

    El urban sprawl : un modelo de urbanización insostenible

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    Tesi en modalitat de compendi de publicacions, amb diferents articles retallats per drets de l'editor.(English) he present thesis consists in a PhD thesis by compendium of publications. The general objective of the thesis is the analysis of the phenomenon of the Urban Sprawl, on a planetary scale, starting from the hypothesis that it is an unsustainable process. For the development, specific objectives were set that include the evolution of the research through a selection of 20 papers. The objectives are: a) Analyzing the Urban Sprawl urbanization model, by reviewing the specialized literature; b) Studying the genesis and evolution c) Quantify the Urban Sprawl from databases of local, regional and global, raising the question: is the Sprawl a phenomenon of planetary scope? d) Verify the hypothesis that in Europe, despite having a relatively dense metropolitan structure, there is a pronounced process of Urban Sprawl in the peripheries of large cities e) Define the “city” in the Sprawl era, defining urban and metropolitan systems based on morphological, economic and functional criteria f) Develop a methodology for the analysis of the internal structure of metropolises, capable of contrasting the degree of monocentrism and polycentrism of urban and metropolitan systems and verify the hypothesis that a higher degree of polycentrism reduces the degree of Sprawl (+ Polycentrism =-Sprawl) g) Apply this methodology to the analysis of specific cases, such as the Spanish urban system h) Apply the above methodology to analyze the efficiency in land consumption of the metropolitan systems of Madrid and Barcelona, Los Angeles and Chicago i) Analyze the process of urbanization through the land impacted by urbanization on a global scale, through images of night lights, delimiting metropolitan and megalopolitan areas and defining the different landscapes of human settlements j) Assess suitability of nighttime images to identify urban areas (in relation to rural settlements), and especially the Urban Sprawl, as well as, quantify the retrospective (and prospective) dynamics of the urbanization process (with special attention to China) k) Evaluate the climatic behavior of dispersed and low-density fabrics in comparison to the rest of urban and rural fabrics and uses; l) Study the daytime and nighttime Urban Heat Island (UHI), its spatial distribution and climatic performance of the different types of land covers; m) Study the urban factors that increase the adaptation of cities to global warming, specifically, urban parks as islands of cold in the context of the UHI n) Analyze the effects of heat waves on health, as well as the effect of urban greenery. The thesis, on the one hand, confirms the hypothesis of the unsustainability of the Urban Sprawl, since it implies a high consumption of land, in addition to generating unsustainable mobility. In the same way, it implies a fragmented and dispersed urbanization model, higher energy consumption and promotes social segregation. On the other hand, from the perspective of adaptation to climate change, the Urban Sprawl undoubtedly has a better performance, mainly due to the quality and quantity of green areas present in this type of urban fabric (absent in the central and dense city) and its proximity to those rural or forest areas, which are spaces that produce fresh air. The great challenge of spatial and urban planning is to stop this process of urban expansion without compromising the quality of life, comfort and human health. In this sense, it is necessary to proceed with a radical regeneration of the inherited urban fabrics. The compact city model cannot simply be considered the paradigm of sustainability. It must learn from the green spaces per inhabitant present in the Sprawl. Therefore, it can be concluded that green compactness is the new paradigm of 21st century cities.(Español) La tesis consiste en una tesis por compendio de publicaciones y el objetivo central es el análisis del fenómeno de la dispersión de la urbanización llamado Urban Sprawl a escala planetaria, partiendo de la hipótesis de que se trata de un proceso insostenible. Para el desarrollo de la misma se plantearon objetivos específicos que han sido desarrollados a través de artículos. Estos objetivos son: a) analizar el modelo del Urban Sprawl, mediante la revisión de la literatura especializada b) estudiar su génesis y evolución c) cuantificar el Urban Sprawl a partir de bases de datos de alcance local, regional y mundial, planteando la interrogante ¿es el Sprawl un fenómeno de alcance planetario? d) verificar la hipótesis de que en Europa, a pesar de tener una estructura metropolitana relativamente densa, existe un acusado proceso de Urban Sprawl en las periferias de las grandes ciudades e) delimitar la “ciudad” en la era del Sprawl, definiendo los sistemas urbanos y metropolitanos a partir de criterios morfológicos, económicos y funcionales f) desarrollar una metodología para el análisis de la estructura interna de las metrópolis, capaz de contrastar el grado de monocentrismo y policentrismo de los sistemas urbanos y metropolitanos y verificar la hipótesis de que un mayor grado de policentrismo atenúa el grado de Sprawl (+ Policentrismo = - Sprawl) g) aplicar dicha metodología al análisis de casos concretos, como es el sistema urbano español h) aplicar la anterior metodología para analizar la eficiencia en el consumo de suelo de los sistemas metropolitanos de Madrid y Barcelona, Los Ángeles y Chicago i) Analizar el proceso de urbanización a través del suelo impactado por la urbanización a escala mundial, por medio de imágenes de luces nocturnas, delimitando áreas metropolitanas y megalopolitanas a escala mundial y definiendo en las mismas los diferentes paisajes de los asentamientos humanos j) evaluar la capacidad de las luces nocturnas para identificar las áreas urbanas y muy especialmente el Urban Sprawl, así como cuantificar la dinámica retrospectiva (y prospectiva) del proceso de urbanización (con especial atención a China); k) evaluar el comportamiento climático de los tejidos dispersos y de baja densidad en comparación al resto de tejidos y usos urbanos y rurales; l) Estudiar la Isla de Calor Urbana (UHI) diurna y nocturna, su distribución espacial y comportamiento climático de los diferentes tipos de cubiertas de suelo; m) estudiar los factores urbanísticos que incrementan la adaptación de las ciudades al calentamiento global, específicamente, los parques urbanos como islas de frío en el contexto de la UHI; y n) analizar los efectos que tienen las olas de calor en la salud, así como el efecto del verde urbano. La tesis, por un lado, confirma la hipótesis de la insostenibilidad del Urban Sprawl, dado que implica un alto consumo de suelo, además de generar una movilidad insostenible. Del mismo modo, implica un modelo de urbanización fragmentado y disperso, un mayor consumo energético y promueve la segregación social. Por otro lado, desde la perspectiva de la adaptación al cambio climático, el Urban Sprawl tiene sin duda un mejor comportamiento, principalmente por la calidad y cantidad de espacio verde presente en este tipo de tejido urbano (ausente en la ciudad central y densa) y su proximidad a aquellas zonas rurales o forestales, que son espacios que producen aire fresco. El gran desafío de la planificación territorial y urbana es detener este proceso de expansión urbana sin comprometer la calidad de vida, el confort y la salud humana. En este sentido, es necesario proceder a una reforma radical de los tejidos urbanos heredados. El modelo de ciudad compacta no puede ser considerado simplemente el paradigma de la sostenibilidad. Debe aprender de la mayor cantidad de espacios verdes por habitante presente en el Sprawl. Por tanto, concluir que la compacidad verde es el nuevo paradigma de las ciudades del siglo XXI.Postprint (published version

    CIRA annual report FY 2014/2015

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    Reporting period July 1, 2014-March 31, 2015

    Faculty Publications and Creative Works 2003

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    Faculty Publications & Creative Works is an annual compendium of scholarly and creative activities of University of New Mexico faculty during the noted calendar year. It serves to illustrate the robust and active intellectual pursuits conducted by the faculty in support of teaching and research at UNM

    Spacelab Science Results Study

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    Beginning with OSTA-1 in November 1981 and ending with Neurolab in March 1998, a total of 36 Shuttle missions carried various Spacelab components such as the Spacelab module, pallet, instrument pointing system, or mission peculiar experiment support structure. The experiments carried out during these flights included astrophysics, solar physics, plasma physics, atmospheric science, Earth observations, and a wide range of microgravity experiments in life sciences, biotechnology, materials science, and fluid physics which includes combustion and critical point phenomena. In all, some 764 experiments were conducted by investigators from the U.S., Europe, and Japan. The purpose of this Spacelab Science Results Study is to document the contributions made in each of the major research areas by giving a brief synopsis of the more significant experiments and an extensive list of the publications that were produced. We have also endeavored to show how these results impacted the existing body of knowledge, where they have spawned new fields, and if appropriate, where the knowledge they produced has been applied

    Half a century of satellite remote sensing of sea-surface temperature

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    Sea-surface temperature (SST) was one of the first ocean variables to be studied from earth observation satellites. Pioneering images from infrared scanning radiometers revealed the complexity of the surface temperature fields, but these were derived from radiance measurements at orbital heights and included the effects of the intervening atmosphere. Corrections for the effects of the atmosphere to make quantitative estimates of the SST became possible when radiometers with multiple infrared channels were deployed in 1979. At the same time, imaging microwave radiometers with SST capabilities were also flown. Since then, SST has been derived from infrared and microwave radiometers on polar orbiting satellites and from infrared radiometers on geostationary spacecraft. As the performances of satellite radiometers and SST retrieval algorithms improved, accurate, global, high resolution, frequently sampled SST fields became fundamental to many research and operational activities. Here we provide an overview of the physics of the derivation of SST and the history of the development of satellite instruments over half a century. As demonstrated accuracies increased, they stimulated scientific research into the oceans, the coupled ocean-atmosphere system and the climate. We provide brief overviews of the development of some applications, including the feasibility of generating Climate Data Records. We summarize the important role of the Group for High Resolution SST (GHRSST) in providing a forum for scientists and operational practitioners to discuss problems and results, and to help coordinate activities world-wide, including alignment of data formatting and protocols and research. The challenges of burgeoning data volumes, data distribution and analysis have benefited from simultaneous progress in computing power, high capacity storage, and communications over the Internet, so we summarize the development and current capabilities of data archives. We conclude with an outlook of developments anticipated in the next decade or so

    Long-Term Durability of Rooftop Grid-Connected Solar Photovoltaic Systems

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    Compared to their initial performance, solar photovoltaic (PV) arrays show long-term performance degradation, resulting in lower like-for-like efficiencies and performance ratios. The long-term durability of polycrystalline silicon (p-Si) solar PV modules in three roof-top grid-connected arrays has been examined. Electrical output, ambient temperature, cell temperature, solar irradiance, solar irradiation, and wind speed data were collected at hourly intervals from 2017 to 2021 from three 50 kWp PV installations in Northern Ireland. The results show the extent to which higher PV temperatures associated with more intense solar radiation decrease efficiency, fill factor and maximum power output for PV arrays in a temperate climate. Long-term durability trends for grid-connected roof-top solar photovoltaic systems can be obscured by diurnal and seasonal changes in environmental conditions. To reduce the influence of variable conditions, performance ratios (PRcorr) were “corrected” using the measured annual average cell temperature (Tcell_avg). Introduction of this temperature-correction reduced the seasonal variation of the performance ratio. Using temperature-corrected performance ratios, long-term (in this case those seen after fiveyears operation) performance degradation trends become evident with high confidence after six months for one PV array and within three years for the two other arrays. If lower statistical confidence in trends is acceptable, long-term degradation rates can be identified within one year of operation for all PV arrays examined. These results have the important implication that relatively short-duration outdoor PV performance monitoring may be reliably used to estimate long-term degradation and/or to calibrate normally-conducted accelerated testing

    CIRA annual report FY 2017/2018

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    Reporting period April 1, 2017-March 31, 2018
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