Search results for " parameter"
showing 10 items of 13688 documents
On asymmetric periodic solutions in relay feedback systems
2021
Abstract Asymmetric self-excited periodic motions or periodic solutions which are produced by relay feedback systems that have symmetric characteristics are studied in the paper. Two different mechanisms of producing an asymmetric oscillation by a system with symmetric properties are noted and analyzed by the locus of a perturbed relay system (LPRS) method. Bifurcation between the ability to excite symmetric and asymmetric oscillation with variation of system parameters is analyzed. An algorithm of finding asymmetric solutions is proposed.
Space‐vector state dynamic model of SynRM considering self‐ and cross‐saturation and related parameter identification
2020
This study proposes a state formulation of the space-vector dynamic model of the Synchronous Reluctance Motor (SynRM) considering both saturation and cross-saturation effects. The proposed model adopts the stator currents as state variables and has been theoretically developed in both the rotor and stator reference frames. The proposed magnetic model is based on a flux versus current approach and relies on the knowledge of 11 parameters. Starting from the definition of a suitable co-energy variation function, new flux versus current functions have been initially developed, based on the hyperbolic functions and, consequently, the static and dynamic inductance versus current functions have be…
Influence of the MgO barrier thickness on the lifetime characteristics of magnetic tunnelling junctions for sensors
2016
Magnetic tunnelling junctions increasingly enter the market for magnetic sensor applications. Thus, technological parameters such as the lifetime characteristics become more and more important. Here, an analysis of the lifetime characteristics of magnetic tunnelling junctions using the Weibull statistical distribution for CoFeB/MgO/CoFeB junctions is presented. The Weibull distribution is governed by two parameters, the characteristic lifetime η of the population and the shape parameter β, which gives information about the presence of an infant mortality. The suitability of the Weibull distribution is demonstrated for the description of dielectric breakdown processes in MgO-based tunnelling…
Study of a sample of faint Be stars in the exofield of CoRoT
2013
International audience; Context. Be stars are probably the most rapid rotators among stars in the main sequence (MS) and, as such, are excellent candidates to study the incidence of the rotation on the characteristics of their non-radial pulsations, as well as on their internal structure. Pulsations are also thought to be possible mechanisms that help the mass ejection needed to build up the circumstellar disks of Be stars.Aims. The purpose of this paper is to identify a number of faint Be stars observed with the CoRoT satellite and to determine their fundamental parameters, which will enable us to study their pulsation properties as a function of the location in the HR diagram and to searc…
LAI, FAPAR and FCOVER ground-truth map creation from FASat-C satellite imagery and in-situ measurements in Chimbarongo, Chile, for satellite products…
2016
[EN] In remote sensing, validation exercises are essential to ensure the quality of the products originated from satellite Earth observations. To assess the measurement uncertainty derived from satellite products, several ground field data from different ecosystems must be available for use. In the same order of importance, it is necessary to define data sampling and up-scaling methodologies to allow a suitable comparison between the ground data and the pixel size of the product. This paper shows the applied methodology used in the FP7 ImagineS project (Implementing Multi-scale Agricultural Indicators Exploiting Sentinels) to validate 10-days global LAI, FAPAR and vegetation cover products …
Modelling and Analysis of Flow Rate and Pressure Head in Pipelines
2019
Currently, various approaches with several utilities are proposed to identify damage in the pipeline. The pipeline system is modeled in the form of a distributed parameter system, such that the state space related to the distributed parameter system contains infinite dimension. In this paper, a novel technique is proposed to analyze and model the flow in the pipeline. Important theorems are proposed for testing the observability as well as controllability of the proposed model.
HF radar for wind waves measurements in the Malta-Sicily Channel
2018
Abstract The CALYPSO HF radar network is a permanent and fully operational observing system currently composed of four CODAR SeaSonde stations. The system is providing real-time hourly maps of sea surface currents and waves data in the Malta-Sicily Channel. The present work aims to compare significant wave height measurements by HF Radar to wave data from numerical models and satellite altimeter. This is the first time that this set of wave data are analysed since the four HF radars were installed between 2012 and 2015. Results suggest that CODAR HF Radar wave data are a reliable source of wave information even in the case of extreme events, providing an avenue to improve and complete the o…
ERA5-Land: A state-of-the-art global reanalysis dataset for land applications
2021
Framed within the Copernicus Climate Change Service (C3S) of the European Commission, the European Centre for Medium-Range Weather Forecasts (ECMWF) is producing an enhanced global dataset for the land component of the fifth generation of European ReAnalysis (ERA5), hereafter referred to as ERA5-Land. Once completed, the period covered will span from 1950 to the present, with continuous updates to support land monitoring applications. ERA5-Land describes the evolution of the water and energy cycles over land in a consistent manner over the production period, which, among others, could be used to analyse trends and anomalies. This is achieved through global high-resolution numerical integrat…
The 2009 Edition of the GEISA Spectroscopic Database
2011
The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10-6 to 35,877.031cm-1.The successful performances of the new …
PHYSICS-based retrieval of scattering albedo and vegetation optical depth using multi-sensor data integration
2017
Vegetation optical depth and scattering albedo are crucial parameters within the widely used τ-ω model for passive microwave remote sensing of vegetation and soil. A multi-sensor data integration approach using ICESat lidar vegetation heights and SMAP radar as well as radiometer data enables a direct retrieval of the two parameters on a physics-derived basis. The crucial step within the retrieval methodology is the calculus of the vegetation scattering coefficient KS, where one exact and three approximated solutions are provided. It is shown that, when using the assumption of a randomly oriented volume, the backscatter measurements of the radar provide a sufficient first order estimate and …