1,200 research outputs found
Modular Planar Antenna at X-band for satellite communications
An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 [1] and ITU-R S.465-5 [2] for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarizatio
Portable low profile antenna at X-band
An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 and ITU-R S.465-5 for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band with a VSWR of 1.4:1. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarization
Greenhouse Crop Identification from Multi-Temporal Multi-Sensor Satellite Imagery Using Object-Based Approach: A Case Study from Almería (Spain)
A workflow headed up to identify crops growing under plastic-covered greenhouses (PCG) and based on multi-temporal and multi-sensor satellite data is developed in this article. This workflow is made up of four steps: (i) data pre-processing, (ii) PCG segmentation, (iii) binary preclassification between greenhouses and non-greenhouses, and (iv) classification of horticultural crops under greenhouses regarding two agronomic seasons (autumn and spring). The segmentation stage was carried out by applying a multi-resolution segmentation algorithm on the pre-processed WorldView-2 data. The free access AssesSeg command line tool was used to determine the more suitable multi-resolution algorithm parameters. Two decision tree models mainly based on the Plastic Greenhouse Index were developed to perform greenhouse/non-greenhouse binary classification from Landsat 8 and Sentinel-2A time series, attaining overall accuracies of 92.65% and 93.97%, respectively. With regards to the classification of crops under PCG, pepper in autumn, and melon and watermelon in spring provided the best results (Fβ around 84% and 95%, respectively).
Data from the Sentinel-2A time series showed slightly better accuracies than those from Landsat 8
Improving georeferencing accuracy of Very High Resolution satellite imagery using freely available ancillary data at global coverage
While impressive direct geolocation accuracies better than 5.0 m CE90 (90% of circular error) can be achieved from the last DigitalGlobe’s Very High Resolution (VHR) satellites (i.e. GeoEye-1 and WorldView-1/2/3/4), it is insufficient for many precise geodetic applications. For these sensors,
the best horizontal geopositioning accuracies (around 0.55 m CE90) can be attained by using third-order 3D rational functions with vendor’s rational polynomial coefficients data refined by a zero-order polynomial adjustment obtained from a small number of very accurate ground control points (GCPs). However, these high-quality GCPs are not always available. In this work, two different approaches for improving the initial direct geolocation accuracy of VHR satellite imagery are proposed. Both of them are based on the extraction of three-dimensional GCPs from freely available ancillary data at global coverage such as multi-temporal information of Google Earth and the Shuttle Radar Topography Mission 30 m digital elevation model. The application of these approaches on WorldView-2 and GeoEye-1 stereo pairs over two different study sites proved to improve the horizontal direct geolocation accuracy values around of 75%
Classification of urban areas from GeoEye-1 imagery through texture features based on Histograms of Equivalent Patterns
A family of 26 non-parametric texture descriptors based on Histograms of Equivalent Patterns (HEP) has been tested, many of them for the first time in remote sensing applications, to improve urban classification through object-based image analysis of GeoEye-1 imagery. These HEP descriptors have been compared to the widely known texture measures derived from the gray-level co-occurrence matrix (GLCM). All the five finally selected HEP descriptors (Local Binary Patterns, Improved Local Binary Patterns, Binary Gradient Contours and two different combinations of Completed Local Binary Patterns) performed faster in terms of execution time and yielded significantly better accuracy figures than GLCM features. Moreover, the HEP texture descriptors provided additional information to the basic spectral features from the GeoEye-1's bands (R, G, B, NIR, PAN) significantly improving overall accuracy values by around 3%. Conversely, and in statistic terms, strategies involving GLCM texture derivatives did not improve the classification accuracy achieved from only the spectral information. Lastly, both approaches (HEP and GLCM) showed similar behavior with regard to the training set size applied
Mean Sombor index
A Special Volume on Chemical Graph Theory in Memory of Nenad TrinajsticWe introduce a degree–based variable topological index inspired on the power (or generalized) mean. We name this new index as the mean Sombor index: SOα(G) = P uv∈E(G) [(d α u + d α v ) /2]1/α. Here, uv denotes the edge of the graph G connecting the vertices u and v, du is the degree of the vertex u, and α ∈ R\{0}. We also consider the limit cases mSOα→0(G) and
SOα→±∞(G). Indeed, for given values of α, the mean Sombor index is related to well-known opological indices such as the inverse sum indeg index, the reciprocal Randic index, the first Zagreb index, the Stolarsky–Puebla index and several ´Sombor indices. Moreover, through a quantitative structure property relationship (QSPR) analysis we show that mSOα(G) correlates well with several physicochemical properties of octane isomers. Some mathematical properties of the mean Sombor index as well as bounds and new relationships with known topological indices are also discussed.J.A.M.-B. acknowledges financial support from CONACyT (Grant No. A1-S-22706) and BUAP (Grant No. 100405811VIEP2021) .E.D.M. and J.M.R. were supported by a grant from Agencia Estatal de Investigación (PID 2019-106433GBI00 / AEI / 10.13039 / 501100011033), Spain. J.M.R. was supported by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M23), and in the context of the VPRICIT (Regional Programme of Research and Technological Innovation)
Severa complicación neurológica tras vertebroplastia percutánea
La vertebroplastia percutánea como tratamiento de las fracturas acuñamientos vertebrales osteoporóticos tras fracaso del tratamiento sintomático y ortopédico así como para el tratamiento de lesiones tumorales del caquis ha tomado un auge importante debido a los buenos resultados publicados y la baja tasa de complicaciones. Este hecho ha llevado a las casas comerciales a desarrollar productos específicos para esta técnica que simplifican su utilización y disminuyen en lo posible las dificultades técnicas del procedimiento así como sus complicaciones. A pesar de ello, en nuestra opinión es una técnica que requiere una alta demanda de entrenamiento y que puede dar lugar a graves complicaciones a pesar de que no existan prácticamente en la literatura complicaciones severas con la utilización de esta técnica. Presentamos un caso ocurrido en nuestra serie de una paraplejia completa no resuelta tras una vertebroplastia percutanea torácica para una fractura osteoporótica.The technique of percutaneous vertebroplasty for osteoporotic fractures and spine tumors was develop an important increase because there were a lot of publications with good results and low rate of complications. This fact was done a fast developing of instruments and new PMMA cements to simplify this technique and decreased the rate of complications. In our opinion the percutaneous vertebroplasty is a high demand technique and have a high potential of major neurological complications if it is not performed with use of appropriate safeguards, but the purpose of this article is not to condemn the technique because we have had a good results using it in this pathologies and the majority of publications have shown a high rate of excellent results
Formation of soy protein-based superabsorbent materials through optimization of a thermal processing
Superabsorbent materials are used in a wide range
of products (e.g. personal care, controlled-release
of nutrients in agriculture). The present study pretends the development of biodegradable materials
from a natural source, a soy protein isolate, which
eventually would help to diminish the environmental issues associated to the use of common synthetic materials. Moreover, the present work focuses
on the modulation of the water uptake exclusively
through the modification of the parameters of the
thermal processes carried out during the development of those materials. Firstly, the protein isolate
is blended with the plasticizer (glycerol) in a 1/1
ratio. Then, the homogeneous blend is injected
using different mould temperatures and, subsequently, the bioplastics obtained are submitted to
a dehydrothermal treatment (tdeshid) consisting on
the storage of the samples at 50 ºC for a certain
time (tdeshid). When the mould temperature is 70 ºC,
superabsorbent materials are always obtained at
tdeshid, shorter than 12 h. Conversely, viscoelastic properties increase as DHT treatment is longer,
reducing the swelling that takes place during water absorption, and resulting more compact matrices. Thus, the present study proves how thermal
processing modulation can solely determine the
superabsorbent ability of soy protein-based biodegradable materials.Los materiales superabsorbentes son aplicables
en campos tan diversos como productos de higiene
personal o liberación controlada de nutrientes en
agricultura. El presente estudio pretende el desarrollo de materiales biodegradables a partir de una
materia prima natural, un aislado de proteína de
soja, cuya aplicación supondría una disminución
en el uso de materiales sintéticos, repercutiendo
beneficiosamente en el medio ambiente; y la modulación de su capacidad de absorción de agua,
que se modificará exclusivamente variando las
condiciones de los procesos térmicos a los que son
sometidas durante su obtención. En primer lugar,
el aislado se mezcla con glicerina (plastificante)en
una proporción 1/1, para después inyectar la masa
homogénea utilizando diferentes temperaturas de
moldeo (Tmold). Posteriormente, son sometidas a un
tratamiento deshidrotérmico. o almacenamiento
a 50ºC, durante cierto periodo de tiempo (tdeshid).
Cuando la Tmold utilizada es 70ºC, se obtienen
siempre materiales superabsorbentes, cuando el
tdeshid seleccionado sea menos de 12h. Por otra
parte, las propiedades viscoelásticas aumentan con
la duración del tratamiento deshidrotérmico, provocando un menor hinchamiento durante la absorción de agua, resultando matrices menos porosas.
Así, el presente estudio permite comprobar cómo
modulando exclusivamente las condiciones de procesado pueden conseguirse capacidades superabsorbentes para materiales biodegradables basados
en soja.Ministerio de Economía y Competitividad de España-CTQ2015-71164-
Quantic Analysis of Formation of a Biomaterial of Latex, Retinol, and Chitosan for Biomedical Applications
The present work shows the quantum theoretical analysis and practical tests for the formation of a homogeneous mixture with Latex (Lx), Chitosan (Qn) and Retinol (Rl), which work as possible biomaterial for regeneration of epithelial tissue. Lx, Qn, and Rl compounds molecules were designed through Hyperchem to get the coefficient of electrostatic potential calculations. The amounts used to create the biomaterial are minimum depending on the quantities of molecules used in chemical design. A positive calculation was obtained for the reaction of these three compounds and the formation of the biomaterial in physical checking theory etc
Autonomic Management Architecture for Multi-HVAC Systems in Smart Buildings.
This article proposes a self-managing architecture for multi-HVAC systems in buildings, based on the “Autonomous Cycle of Data Analysis Tasks” concept. A multi-HVAC system can be plainly seen as a set of HVAC subsystems, made up of heat pumps, chillers, cooling towers or boilers, among others. Our approach is used for improving the energy consumption, as well as to maintain the indoor comfort, and maximize the equipment performance, by means of identifying and selecting of a possible multi-HVAC system operational mode. The multi-HVAC system operational modes are the different combinations of the HVAC subsystems. The proposed architecture relies on a set of data analysis tasks that exploit the data gathered from the system and the environment to autonomously manage the multi-HVAC system. Some of these tasks analyze the data to obtain the optimal operational mode in a given moment, while others control the active HVAC subsystems. The proposed model is based on standard standard HVAC mathematical models, that are adapted on the fly to the contextual data sensed from the environment. Finally, two case studies, one with heterogeneous and another with homogeneous HVAC equipment, show the generality of the proposed autonomous management architecture for multi-HVAC systems.post-print4413 K
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