1,720,980 research outputs found
A novel method to improve the spatial resolution of microwave radiometer measurements using variable exponent Lebesgue space
No full textSpatial resolution enhancement of microwave radiometer measurements is addressed using a new method that is based on an Lp penalisation approach with a variable p exponent. The key idea is letting p to vary in the range 1.2 - 2 to take benefit of both Hilbert (i.e. p=2) and Banach (i.e. p=1.2) advantages. Results, obtained processing both simulated and actual Special Sensor Microwave Imager (SSM/I) measurements, demonstrate the benefits of the proposed approach in reconstructing abrupt discontinuities and smooth gradients with respect to approaches in Hilbert and Banach spaces
A resolution-enhanced product for the SMAP L-band radiometer
No full textThis study addresses the spatial resolution enhancement of synthetic microwave radiometer observations obtained by the Soil Moisture Active Passive (SMAP) L-Band Radiometer. An antenna pattern deconvolution method is used together with an iterative regularization scheme to reconstruct the brightness field at enhanced spatial resolution. Results obtained processing both synthetic and actual SMAP measurements show that sharper edges and coastlines can be reconstructed in a very effective way
A NEW ANTENNA PATTERN DECONVOLUTION METHOD TO ENHANCE THE SPATIAL RESOLUTION OF MULTI-CHANNEL MICROWAVE RADIOMETER MEASUREMENTS
No full textIn this study, a new antenna pattern deconvolution method to enhance the spatial resolution of multi-channel microwave radiometer (MWR) measurements is developed. This technique, based on a conventional gradient-like iterative method, utilizes the information contained in a high-frequency channel to enhance the spatial resolution of the lower-frequency channel in a data-fusion fashion. The physical idea consists of initializing the gradient-like inversion scheme using higher frequency details that are filtered out by the system measurement function. Experiments, performed on a dataset that includes both simulated and actual radiometer measurements, show that the proposed technique allows outperforming the conventional gradient method, while being very robust with respect to artifacts that could be induced by the higher frequency channel
An Enhanced Product for the Fsscat Microwave Radiometer
No full textIn this study, an enhanced spatial resolution product is proposed for the forthcoming L-band microwave radiometer operated on board of the FSSCat mission. The product is obtained reconstructing the brightness temperature on a finer spatial resolution grid using an antenna pattern deconvolution method. Simulated FSSCat noisy measurements are used to showcase the soundness of the proposed approach that results in remarkable reconstruction performance
On the Use of Preconditioners to Improve the Accuracy and Effectiveness of Iterative Methods to Enhance the Spatial Resolution of Radiometer Measurements
No full textIn this letter, a new approach is proposed to ameliorate the performance of iterative gradient-like regularization schemes aimed at enhancing the spatial resolution of microwave radiometer measurements in the Hilbert space. The approach consists of preconditioning the ill-conditioned discrete problem to let the iterative gradient-based inversion technique be more computer-time effective. Experiments undertaken on the simulated radiometer brightness profiles demonstrate the soundness of the proposed rationale that outperforms conventional gradient-like methods in terms of both computer-time effectiveness and accuracy in reconstructing spot-like discontinuities while resulting in larger fluctuations over the background
A Multichannel Data Fusion Method to Enhance the Spatial Resolution of Microwave Radiometer Measurements
No full textIn this study, a method to improve the reconstruction performance of antenna-pattern deconvolution based on the gradient iterative regularization scheme is proposed. The method exploits microwave measurements acquired by a multichannel radiometer to enhance their native spatial resolution. The proposed rationale consists of using the information carried on a high-frequency (finer spatial resolution) channel to ameliorate the spatial resolution of the lowest resolution radiometer channel. Experiments performed using both synthetic and real special sensor microwave/imager (SSM/I) radiometer data demonstrate that an enhanced spatial resolution 19.35-GHz channel can be obtained by ingesting in the algorithm information coming from 37.0-GHz channel. This multichannel spatial resolution method is also shown to outperform the conventional gradient-like regularization scheme in terms of both observation of smaller targets and reduction of ringings and fluctuations
Comparison of Accelerated Versions of the Iterative Gradient Method to Ameliorate the Spatial Resolution of Microwave Radiometer Products
Full text linkIn this study, the enhancement of the spatial resolution of microwave radiometer measurements is addressed by contrasting the accuracy of a gradient-like antenna pattern deconvolution method with its accelerated versions. The latter are methods that allow reaching a given accuracy with a reduced number of iterations. The analysis points out that accelerated methods result in improved performance when dealing with spot-like discontinuities; while they perform in a similar way to the canonical gradient method in case of large discontinuities. A key application of such techniques is the research on global warming and climate change, which has recently gained critical importance in many scientific fields, mainly due to the huge societal and economic impact of such topics over the entire planet. In this context, the availability of reliable long time series of remotely sensed Earth data is of paramount importance to identify and study climate trends. Such data can be obtained by large-scale sensors, with the obvious drawback of a poor spatial resolution that strongly limits their applicability in regional studies. Iterative gradient techniques allow obtaining super-resolution gridded passive microwave products that can be used in long time series of consistently calibrated brightness temperature maps in support of climate studies
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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