Search results for "Sensing"
showing 10 items of 1698 documents
Performances of neural networks for deriving LAI estimates from existing CYCLOPES and MODIS products
2008
International audience; This paper evaluates the performances of a neural network approach to estimate LAI from CYCLOPES and MODIS nadir normalized reflectance and LAI products. A data base was generated from these products over the BELMANIP sites during the 2001-2003 period. Data were aggregated at 3 km x 3 km, resampled at 1/16 days temporal frequency and filtered to reject outliers. VEGETATION and MODIS reflectances show very consistent values in the red, near infrared and short wave infrared bands. Neural networks were trained over part of this data base for each of the 6 MODIS biome classes to retrieve both MODIS and CYCLOPES LAI products. Results show very good performances of neural …
An integrated modelling and remote sensing approach for hydrological study in arid and semi-arid regions: the SUDMED Program
2008
International audience; Recent efforts have been concentrated in the development of models to understand and predict the impact of environmental changes on hydrological cycle and water resources in arid and semi-arid regions. In this context, remote sensing data have been widely used to initialize, to force, or to control the simulations of these models. However, for several reasons, including the difficulty in establishing relationships between observational and model variables, the potential offered by satellite data has not been fully used. As a matter of fact, a few hydrological studies that use remote sensing data emanating from different sources (sensors, platforms) have been performe…
Experimental and theoretical studies on electropolymerization of polar amino acids on platinum electrode
2017
International audience; The anodic oxidation of polar amino acids (L-serine, L-threonine, L-asparagine, and L-glutamine) in aqueous electrolyte on smooth platinum electrode was carried out by cyclic voltammetry coupled to electrochemical quartz crystal microbalance (EQCM). pH (zwitterion, acidic and alkaline) effects on their electrochemical behavior were examined. The maximum current values are measured for zwitterion species. In addition, the current increases with increasing of concentration and scan rate, and decreases with increasing pH. The resulting passivation was studied by spectroscopic analysis such as attenuated total reflection FT infrared spectroscopy (ATR-FTIR), X-ray photoel…
Quantification of land-atmosphere exchanges of water, energy and carbon dioxide in space and time over the heterogeneous Barrax site
2008
International audience; To advance our understanding of land-atmosphere exchanges of water, energy and carbon dioxide (CO2) in space and time over heterogeneous land surfaces, two intensive field campaigns were carried out at the Barrax agricultural test site in Spain during 12-21 July 2004 (SPARC 2004) and 8-14 July 2005 (SEN2FLEX 2005) involving multiple field, satellite and airborne instruments for characterizing the state of the atmosphere, the vegetation and the soil from the visible to the microwave range of the spectrum. Part of the experimental area is a core site of area 25 km2, within which numerous crops are grown, on both irrigated and dry land, alongside fields of bare soil. Th…
PV-Alert: Fog Computing based Architecture for Safeguarding Vulnerable Road Users
2018
High volumes of pedestrians, cyclists and other vulnerable road users (VRUs) have much higher casualty rates per mile; not surprising given their lack of protection from an accident. In order to alleviate the problem, sensing capabilities of smartphones can be used to detect, warn and safeguard these road users. In this research we propose an infrastructure-less fog-based architecture named PV-Alert (Pedestrian-Vehicle Alert) where fog nodes process delay sensitive data obtained from smartphones for alerting pedestrians and drivers before sending the data to the cloud for further analysis. Fog computing is considered in developing the architecture since it is an emerging paradigm that has p…
Remote and proximal sensing for precision agriculture and viticulture". Special issue
2021
International audience; Special Issue InformationDear Colleagues,Remote and proximal sensing are the two most common techniques concerning the acquisition of information about an object or any phenomenon without physical contact with the object. Remote sensing is widely tied to the use of satellite, airborne or UAV platforms using multi- or hyperspectral imagery. In terms of proximal sensing, the sensor is close to the object and is installed on platforms ranging from handheld, fixed installations, or robotics and tractor-embedded sensors. The types of sensors range from simple RGB or grey-level-cameras to multispectral and hyperspectral high resoluted imaging systems or even thermographic …
Multitemporal Unmixing of Medium-Spatial-Resolution Satellite Images: A Case Study Using MERIS Images for Land-Cover Mapping
2011
Data from current medium-spatial-resolution imaging spectroradiometers are used for land-cover mapping and land-cover change detection at regional to global scales. However, few landscapes are homogeneous at these scales, and this creates the so-called mixed-pixel problem. In this context, this study explores the use of the linear spectral mixture model to extract subpixel land-cover composition from medium-spatial-resolution data. In particular, a time series of MEdium Resolution Imaging Spectrometer (MERIS) full-resolution (FR; pixel size of 300 m) images acquired over The Netherlands is used to illustrate this study. The Netherlands was selected because of the following: 1) the fragmenta…
Lichtaktivierte Sensoren zur empfindlichen Amindetektion
2017
Unsere neue, einfache und akkurate colorimetrische Methode basiert auf Diarylethenen (DAEs) zur schnellen Detektion einer grosen Vielfalt primarer und sekundarer Amine. Die Sensoren bestehen aus aldehyd- oder ketonsubstituierten Diarylethenen, die selektiv ausgehend vom geschlossenen Isomer eine amininduzierte Entfarbungsreaktion eingehen. Somit konnen diese Sensoren zum gewunschten Zeitpunkt durch Lichteinstrahlung aktiviert werden und erlauben eine Empfindlichkeit der Amindetektion bis hinab zu 10−6 m in Losung. Zusatzlich ermoglicht die Immobilisierung auf Papier den Nachweis biogener Amine wie Cadaverin in der Gasphase oberhalb eines Grenzwerts von 12 ppbv innerhalb von 30 Sekunden.
Light-Activated Sensitive Probes for Amine Detection
2017
Our new, simple, and accurate colorimetric method is based on diarylethenes (DAEs) for the rapid detection of a wide range of primary and secondary amines. The probes consist of aldehyde- or ketone-substituted diarylethenes, which undergo an amine-induced decoloration reaction, selectively to give the ring-closed isomer. Thus, these probes can be activated at the desired moment by light irradiation, with a sensitivity that allows the detection of amines at concentrations as low as 10exp−6 M in solution. In addition, the practical immobilization of DAEs on paper makes it possible to detect biogenic amines, such as cadaverine, in the gas phase above a threshold of 12 ppbv within 30 seconds. P…
Telerilevamento e GIS per la valutazione e il monitoraggio delle isole di calore in ambiente urbano
2017
The techniques of spatial analysis and Remote Sensing represent an useful tool for the knowledge and the study of the Urban Heat Island phenomenon (English acronym UHI). In this study, among the different causes that lead to the generation of the event, those regarding physical features of the surface and the presence of different land use/cover such as: the high cover of urban areas and the lack of green areas have been examined. The Remote Sensing techniques allow to create maps of the land use/cover, then, in order to estimate the different in temperature due to the distance to the vegetation, the temperature of the bodies already tested have been compared with a thermal map. In detail t…