Search results for " sensing"
showing 10 items of 1517 documents
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…
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…
CAROLS: A New Airborne L-Band Radiometer for Ocean Surface and Land Observations
2011
The "Cooperative Airborne Radiometer for Ocean and Land Studies" (CAROLS) L-Band radiometer was designed and built as a copy of the EMIRAD II radiometer constructed by the Technical University of Denmark team. It is a fully polarimetric and direct sampling correlation radiometer. It is installed on board a dedicated French ATR42 research aircraft, in conjunction with other airborne instruments (C-Band scatterometer--STORM, the GOLD-RTR GPS system, the infrared CIMEL radiometer and a visible wavelength camera). Following initial laboratory qualifications, three airborne campaigns involving 21 flights were carried out over South West France, the Valencia site and the Bay of Biscay (Atlantic O…
Biofilm Related to Animal Health, Zoonosis and Food Transmitted Diseases: Alternative Targets for Antimicrobial Strategy?
2012
The biofilm is a complex community of microbial cells that are associated with a surface and enclosed in a self-produced biopolymer matrix. Such structured community is a response of bacteria to a signal system named quorum sensing (QS) constituted by inter-cell communication through the production of small molecules called autoinducers (AIs) that trigger a cascade of events in gene expression. When the concentration of the AIs molecules reach a certain threshold, the bacterial population acts as a single organism, collectively expressing virulence or biofilm forming genes. Gram-positive bacteria use modified oligopeptides as QS effectors molecules.
Characterization of Food Packaging Films with Blackcurrant Fruit Waste as a Source of Antioxidant and Color Sensing Intelligent Material
2021
Chitosan and pectin films were enriched with blackcurrant pomace powder (10 and 20% (w/w)), as bio-based material, to minimize food production losses and to increase the functional properties of produced films aimed at food coatings and wrappers. Water vapor permeability of active films increased up to 25%, moisture content for 27% in pectin-based ones, but water solubility was not significantly modified. Mechanical properties (tensile strength, elongation at break and Young’s modulus) were mainly decreased due to the residual insoluble particles present in blackcurrant waste. FTIR analysis showed no significant changes between the film samples. The degradation temperatures, determined by D…
Ecology and extent of freshwater browning - What we know and what should be studied next in the context of global change
2022
Water browning or brownification refers to increasing water color, often related to increasing dissolved organic matter (DOM) and carbon (DOC) content in freshwaters. Browning has been recognized as a significant physicochemical phenomenon altering boreal lakes, but our understanding of its ecological consequences in different freshwater habitats and regions is limited. Here, we review the consequences of browning on different freshwater habitats, food webs and aquatic-terrestrial habitat coupling. We examine global trends of browning and DOM/DOC, and the use of remote sensing as a tool to investigate browning from local to global scales. Studies have focused on lakes and rivers while seldo…
Telerilevamento di aree archeologiche mediante dati iperspettrali MIVIS
2004
The aim of this study is to examine the relationship between physical parameters and the spatial distribution of buried archaeological structures, using data acquired by the airborne hyperspectral sensor MIVIS in the visible, near infrared and thermal infrared wavelengths. The study areas are the territories of Halaesa, an important city in the Hellenistic-Roman period, and the Punic city of Mozia in Sicily. The influence of buried structures on thermal-radiative behaviour has been investigated using three parameters: Normalized Difference Vegetation Index (NDVI), thermal inertia, and Thermal Balanced Gradient. These techniques are shown to be particularly effective in identifying surface p…
Spectral calibration of hyperspectral imagery using atmospheric absorption features
2006
One of the initial steps in the preprocessing of remote sensing data is the atmospheric correction of the at-sensor radiance images, i.e., radiances recorded at the sensor aperture. Apart from the accuracy in the estimation of the concentrations of the main atmospheric species, the retrieved surface reflectance is also influenced by the spectral calibration of the sensor, especially in those wavelengths mostly affected by gaseous absorptions. In particular, errors in the surface reflectance appear when a systematic shift in the nominal channel positions occurs. A method to assess the spectral calibration of hyperspectral imaging spectrometers from the acquired imagery is presented in this p…
Coupling two radar backscattering models to assess soil roughness and surface water content at farm scale
2013
Remote sensing techniques are useful for agro-hydrological monitoring at the farm scale because the availability of spatially and temporally distributed data improves agricultural models for irrigation and crop yield optimization under water scarcity conditions. This research focuses on the surface water content retrieval using active microwave data. Two semi-empirical models were chosen as these showed the best performances in simulating cross and co-polarized backscatter. Thus, these models were coupled to obtain reliable assessments of both soil water content and soil roughness. The use of the coupled model enables one to avoid using roughness measured in situ. Remote sensing images and …
Estimating Tree Health Decline Caused by Ips typographus L. from UAS RGB Images Using a Deep One-Stage Object Detection Neural Network
2022
Various biotic and abiotic stresses are causing decline in forest health globally. Presently, one of the major biotic stress agents in Europe is the European spruce bark beetle (Ips typographus L.) which is increasingly causing widespread tree mortality in northern latitudes as a consequence of the warming climate. Remote sensing using unoccupied aerial systems (UAS) together with evolving machine learning techniques provide a powerful tool for fast-response monitoring of forest health. The aim of this study was to investigate the performance of a deep one-stage object detection neural network in the detection of damage by I. typographus in Norway spruce trees using UAS RGB images. A Scaled…