Validación a largo plazo de datos de nivel 3 de tierra de SMOS con medidas de ELBARA-II en la Valencia Anchor Station

Revista oficial de la Asociación Española de Teledetección[EN] The Soil Moisture and Ocean Salinity (SMOS) mission was launched on 2nd November 2009 with the objective of providing global estimations of soil moisture and sea salinity. The main activity of the Valencia Anchor Station (VAS) is currently to assist in a long-term validation of SMOS land products. This study focus on a level 3 SMOS data validation with in situ measurements carried out in the period 2010-2012 over the VAS. ELBARA-II radiometer is placed in the VAS area, observing a vineyard field considered as representative of a major proportion of an area of 50×50 km, enough to cover a SMOS footprint. Brightness temperatures (TB) acquired by ELBARA-II have been compared to those observed by SMOS at the same dates and time. They were also used for the L-MEB model inversion to retrieve soil moisture (SM), which later on have been compared to those provided by SMOS as level 3 data. A good correlation between both TB datasets was found, improving year by year, mainly due to the decrease of precipitations in the analyzed period and the mitigation of radio frequency interferences at L-band. The larger homogeneity of the radiometer footprint as compared to SMOS explains the higher variability of its TB. Periods of more intense precipitation (spring and autumn) also presented higher SM, which corroborates the consistency of SM retrieved from ELBARA-II’s observations. However, the results show that SMOS level 3 data underestimate SM as compared to ELBARA-II’s, probably due to the influence of the small soil fraction which is not cultivated in vineyards. SMOS estimations in descending orbit (6 pm) had better quality (higher correlation, lower RMSE and bias) than the ones in ascending orbit (6 am, when there is a higher soil moisture). Guardar / Salir Siguiente >[ES] La misión de SMOS (Soil Moisture and Ocean Salinity) se lanzó el 2 de Noviembre de 2009 con el objetivo de proporcionar datos de humedad del suelo y salinidad del mar. La principal actividad de la conocida como Valencia Anchor Station(VAS) es asistir en la validación a largo plazo de productos de suelo de SMOS. El presente estudio se centra en una validación de datos de nivel 3 de SMOS en la VAS con medidas in situ tomadas en el periodo 2010-2012. El radiómetro ELBARA-II está situado dentro de los confines de la VAS, observando un campo de viñedos que se con-sidera representativo de una gran proporción de un área de 50×50 km, suficiente para cubrir un footprint de SMOS. Las temperaturas de brillo (TB) adquiridas por ELBARA-II se compararon con las observadas por SMOS en las mismas fechas y horas. También se utilizó la inversión del modelo L-MEB con el fin de obtener humedades de suelo (SM) que, posteriormente, se compararon con datos de nivel 3 de SMOS. Se ha encontrado una buena correlación entre ambas series de TB, con mejoras año tras año, achacable fundamentalmente a la disminución de precipitaciones en el perio-do objeto de estudio y a la mitigación de las interferencias por radiofrecuencia en banda L. La mayor homogeneidad del footprintdel radiómetro ELBARA-II frente al de SMOS explica la mayor variabilidad de sus TB. Los periodos de preci-pitación más intensa (primavera y otoño) también son de mayor SM, lo que corrobora la consistencia de los resultados de SM simulados a través de las observaciones del radiómetro. Sin embargo, se debe resaltar una subestimación por parte de SMOS de los valores de SM respecto a los obtenidos por ELBARA-II, presumiblemente debido a la influencia que la pequeña fracción de suelo no destinado al cultivo de la vid tiene sobre SMOS. Las estimaciones por parte de SMOS en órbita descendente (6 p.m.) resultaron de mayor calidad (mayor correlación y menores RMSE y bias) que en órbita ascendente (6 a.m., momento de mayor humedad de suelo).This work is carried out within the framework of the project MIDAS-7/UVEG Productos y Aplicaciones Avanzados de SMOS y Futuras Misiones (Parte UVEG) from the Spanish Research Programme on Space, Spanish Ministry for Economy and Competitiveness.Fernandez-Moran, R.; Wigneron, JP.; López-Baeza, E.; Miernecki, M.; Salgado-Hernanz, P.; Coll, M.; Kerr, YH.... (2015). Towards a long-term dataset of ELBARA-II measurements assisting SMOS level-3 land product and algorithm validation at the Valencia Anchor Station. Revista de Teledetección. (43):55-62. doi:10.4995/raet.2015.2297.SWORD55624

Electromagnetic characterization of soil-litter media – Application to the simulation of the microwave emissivity of the ground surface in forests

In order to improve our knowledge of the emitted signal of forests at L-band (1.4 GHz) we focused this study on permittivity measurements of heterogenic natural media such as soil or litter consisting of plant debris and organic matter. This study was done in the context of the upcoming SMOS (Soil Moisture and Ocean Salinity) satellite mission that will attempt to map surface soil moisture from L-band (1.4 GHz) passive microwave measurements. In the field of passive microwaves, very little information exists about the behaviour of the L-band signal of forests especially when litter is included in the soil-vegetation system. To date very few analyses have investigated the dielectric behaviour of the litter layer and its influence on the microwave emission of forests is generally neglected. © 2008 EDP Sciences

The hydrogen and helium lines of the symbiotic binary Z And during its brightening at the end of 2002

High resolution observations in the region of the lines Halpha, He II 4686 and Hgamma of the spectrum of the symbiotic binary Z And were performed during its small-amplitude brightening at the end of 2002. The profiles of the hydrogen lines were double-peaked. These profiles give a reason to suppose that the lines can be emitted mainly by an optically thin accretion disc. The Halpha line is strongly contaminated by the emission of the envelope, therefore for consideration of accretion disc properties we use the Hgamma line. The Halpha line had broad wings which are supposed to be determined mostly from radiation damping but high velocity stellar wind from the compact object in the system can also contribute to their appearance. The Hgamma line had a broad emission component which is assumed to be emitted mainly from the inner part of the accretion disc. The line He II 4686 had a broad emission component too, but it is supposed to appear in a region of a high velocity stellar wind. The outer radius of the accretion disc can be calculated from the shift between the peaks. Assuming, that the orbit inclination can ranges from 47$^\circ$ to 76$^\circ$, we estimate the outer radius as 20 - 50 R_sun. The behaviour of the observed lines can be considered in the framework of the model proposed for interpretation of the line spectrum during the major 2000 - 2002 brightening of this binary.Comment: 19 pages, 5 figures. Accepted for publication in Astronomy Report

Illumination in symbiotic binary stars: Non-LTE photoionization models. II. Wind case

We describe a non-LTE photoionization code to calculate the wind structure and emergent spectrum of a red giant wind illuminated by the hot component of a symbiotic binary system. We consider spherically symmetric winds with several different velocity and temperature laws and derive predicted line fluxes as a function of the red giant mass loss rate, \mdot. Our models generally match observations of the symbiotic stars EG And and AG Peg for \mdot about 10^{-8} \msunyr to 10^{-7} \msunyr. The optically thick cross- section of the red giant wind as viewed from the hot component is a crucial parameter in these models. Winds with cross-sections of 2--3 red giant radii reproduce the observed fluxes, because the wind density is then high, about 10^9 cm^{-3}. Our models favor winds with acceleration regions that either lie far from the red giant photosphere or extend for 2--3 red giant radii.Comment: 51 pages, LaTeX including three tables, requires 15 Encapsulated Postscript figures, to appear in Ap

The research of automobile electric control bus technology based on CAN/LIN mixed protocol

传统汽车电气控制系统中采用的点对点通信方式，对于电子化程度越来越高的汽车而言，将使其线束十分复杂，不仅增加了电气系统成本，而且会因为节点繁多使系统运行可靠性降低。总线网络能够大量减少控制线数，提高可靠性，因此，采用总线控制成为汽车电气控制系统技术发展的必然趋势。如何在汽车上建立基于总线技术的汽车电气控制系统问题自然成为汽车电子领域广受关注的研究热点。西门子公司已经利用PLC完成CAN总线控制系统，由于其具有抗干扰性强、线路简化、传输速率高、系统可任意扩展等优点，正受到国内外高度重视，但其成本高，很多国内汽车生产厂家不能接受。在这种情形下，福州源光亚明电器有限公司（沈阳中顺汽车供应商）委托厦门大...The traditional automobile electrical control system used in peer-to-peer communications, the freetly increased electronic level of automobiel makes the wiring harness more complicated by which not only increases costs, but also lower the reliability of system because of the various nodes. Bus network can decrease the number of the control lines and increase the reliability greatly. Therefore, the...学位：工学硕士院系专业：物理与机电工程学院机电工程系_测试计量技术及仪器学号：2005130175

Criticality of Low-Energy Protons in Single-Event Effects Testing of Highly-Scaled Technologies

We report low-energy proton and low-energy alpha particle single-event effects (SEE) data on a 32 nm silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) latches and static random access memory (SRAM) that demonstrates the criticality of using low-energy protons for SEE testing of highly-scaled technologies. Low-energy protons produced a significantly higher fraction of multi-bit upsets relative to single-bit upsets when compared to similar alpha particle data. This difference highlights the importance of performing hardness assurance testing with protons that include energy distribution components below 2 megaelectron-volt. The importance of low-energy protons to system-level single-event performance is based on the technology under investigation as well as the target radiation environment

Unlocking data: Federated identity with LSDMA and dCache

X.509, the dominant identity system from grid computing, has proved unpopular for many user communities. More popular alternatives generally assume the user is interacting via their web-browser. Such alternatives allow a user to authenticate with many services with the same credentials (user-name and password). They also allow users from different organisations form collaborations quickly and simply. Scientists generally require that their custom analysis software has direct access to the data. Such direct access is not currently supported by alternatives to X.509, as they require the use of a web-browser. Various approaches to solve this issue are being investigated as part of the Large Scale Data Management and Analysis (LSDMA) project, a German funded national R&D project. These involve dynamic credential translation (creating an X.509 credential) to allow backwards compatibility in addition to direct SAML- and OpenID Connect-based authentication. We present a summary of the current state of art and the current status of the federated identity work funded by the LSDMA project along with the future road map

Raman-Scattering Wings of H alpha in Symbiotic Stars

Nussbaumer et al. (1989) proposed that broad H$\alpha$ wings can be formed through Raman scattering of Ly$\beta$ photons, and in this Letter we argue that the H$\alpha$ wings prevalently seen in symbiotic stars may be indeed formed in this way. Assuming a flat incident UV radiation around Ly$\beta$, we generate template wing profiles around H$\alpha$ that are formed through Raman scattering in a plane-parallel H~I region. We perform profile fitting analyses to show that the template wing profiles are in excellent agreement with the observed ones that are provided by van Winckel et al. (1993) and Ivison et al. (1994). The wing flux is determined by the scattering H~I column density and the incident Ly$\beta$ flux strength and profile. From our profile analysis it is proposed that the Raman scattering component may be identified with the neutral envelope with a column density ranging $10^{18-20} {\rm cm^{-2}}$ that surrounds the binary system. We briefly discuss alternative candidates for the wing formation mechanism and observational implications of Raman scattering in symbiotic stars and in other astronomical objects including planetary nebulae, post AGB stars and active galactic nuclei.Comment: 6 pages including 2 figures, to appear in the Astrophysical Journal Letter

Nonvolatile Field Effect Transistors Based on Protons and Si/SiO{Sub 2}Si Structures

Recently, the authors have demonstrated that annealing Si/SiO{sub 2}/Si structures in a hydrogen containing ambient introduces mobile H{sup +} ions into the buried SiO{sub 2} layer. Changes in the H{sup +} spatial distribution within the SiO{sub 2} layer were electrically monitored by current-voltage (I-V) measurements. The ability to directly probe reversible protonic motion in Si/SiO{sub 2}/Si structures makes this an exemplar system to explore the physics and chemistry of hydrogen in the technologically relevant Si/SiO{sub 2} structure. In this work, they illustrate that this effect can be used as the basis for a programmable nonvolatile field effect transistor (NVFET) memory that may compete with other Si-based memory devices. The power of this novel device is its simplicity; it is based upon standard Si/SiO{sub 2}/Si technology and forming gas annealing, a common treatment used in integrated circuit processing. They also briefly discuss the effects of radiation on its retention properties

The Continuing Slow Decline of AG Pegasi

We analyze optical and ultraviolet observations of the symbiotic binary AG Pegasi acquired during 1992-97. The bolometric luminosity of the hot component declined by a factor of 2-3 from 1980-1985 to 1997. Since 1992, the effective temperature of the hot component may have declined by 10%-20%, but this decline is comparable to the measurement errors. Optical observations of H-beta and He I emission show a clear illumination effect, where high energy photons from the hot component ionize the outer atmosphere of the red giant. Simple illumination models generally account for the magnitude of the optical and ultraviolet emission line fluxes. High ionization emission lines - [Ne V], [Mg V], and [Fe VII] - suggest mechanical heating in the outer portions of the photoionized red giant wind. This emission probably originates in a low density region $\sim$ 30-300 AU from the central binary.Comment: 17 pages, 7 pages, 5 tables; to be published in the Astronomical Journal, July 200