12,408 research outputs found

    Uncertainties for Pre- and Post-Launch Radiometric Calibration of Imaging Spectrometers for Multi-Sensor Applications

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    An important aspect to using imaging spectrometer data is the radiometric characterization and calibration of the sensors and validation of their data products and doing so with error budgets with known traceability. The radiometric accuracy of a given sensor is important for demonstrating the expected quality of data from the sensor. Known traceability allows data from multiple sensors to be directly comparable as will become more important in the near future with the expected launches of multiple imaging spectrometers from multiple countries, agencies, and commercial entities. The current work describes the state of pre- and post-launch radiometric absolute and relative uncertainties and their role in harmonising on-orbit data. Examples of prelaunch uncertainties based on the calibration of EnMAP and the calibration planned for the CLARREO Pathfinder Mission are presented highlighting recent work in the area of detector-based approaches using tunable laser sources. Post-launch calibration approaches for Pathfinder, EnMAP, CHIME, and DESIS including traditional vicarious calibration methods and the challenges of working with commercial data are presented. The vicarious calibration discussion relies on the example of the recently-available RadCalNet data to describe typical methods and challenges that will be faced when harmonising data between imaging spectrometers as well as with multispectral sensors

    Cooling and recombination processes in cometary plasma

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    The ion electron plasma in comets is examined for cooling processes which result from its interactions with the neutral coma. A cometary coma model is formulated that is composed predominantly of H2O and its decomposition products where electrons are cooled in a variety of processes at rates varying with energy. It is shown that solar plasma plus accumulated cometary ions and electrons is affected very strongly as it flows into the coma. The electrons are rapidly cooled and all but some 10% of the ions undergo charge exchange. Photodissociation of H2O is assumed where ion electron recombination is the dominant loss process

    A 3-D Multilateration: A Precision Geodetic Measurement System

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    A system was designed with the capability of determining 1-cm accuracy station positions in three dimensions using pulsed laser earth satellite tracking stations coupled with strictly geometric data reduction. With this high accuracy, several crucial geodetic applications become possible, including earthquake hazards assessment, precision surveying, plate tectonics, and orbital determination

    Field-Tuning of the electron and hole populations in the ruthenate Bi_3Ru_3O_11

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    Experiments on the Hall coefficient R_H and heat capactity C reveal an unusual, compensated electronic ground state in the ruthenate Bi_3Ru_3O_11. At low temperature T, R_H decreases linearly with magnetic field |H| for fields larger than the field scale set by the Zeeman energy. The results suggest that the electron and hole populations are tuned by H in opposite directions via coupling of the spins to the field. As T is decreased below 5 K, the curve C(T)/T vs. T^2 shows an anomalous flattening consistent with a rapidly growing Sommerfeld parameter \gamma(T). We discuss shifts of the electron and hole chemical potentials by H to interpret the observed behavior of R_H.Comment: 5 pages, 6 figures, reference adde

    Pemahaman Tabib Etnis Tionghoa di Surabaya Mengenai Yīnyáng 泗水中医对阴阳之理解

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    Artikel ini bertujuan untuk mengetahui pemahaman tabib etnis Tionghoa di Surabaya mengenai yīnyáng dan cara penerapan konsep yīnyáng dalam profesi mereka.Teori yang menunjang terdiri atas teori keseimbangan yīnyáng merupakan dasar vitalitas kehidupan; keterkaitan konsep yīnyáng dengan keseimbangan bekerja, istirahat, dan bergerak. Artikel ini menggunakan metode penelitian kualitatif deskriptif dan teknik pengumpulan data dilakukan dengan cara wawancara semi terstruktur kepada masyarakat etnis Tionghoa Surabaya yang berprofesi sebagai tabib. Dari hasil penelitian diketahui bahwa para responden semuanya mengetahui konsep yīnyáng, sehingga semua responden menerapkan konsep keseimbangan yīnyáng dalam profesi mereka masing-masing
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