196,092 research outputs found
Terminal settling velocity measurements of volcanic ash during the 2002-2003 Etna eruption by an X-band microwave rain gauge disdrometer
No full texthis is the first report in the scientific literature of direct measurement of the terminal settling velocity of volcanic particles during an eruption. Field measurements using a continuous wave X-band disdrometer were carried out at Mt. Etna on 18 and 19 December 2002, when the explosive activity produced a 4 km high volcanic plume. These data allow the estimation of the intensity of the fallout and the measurement of the terminal settling velocities of the volcanic particles in real-time. The main results are: ( 1) the tested instrument detected coherent falling volcanic particles from 0.2 to 1 mm diameter; ( 2) measured terminal settling velocities were in agreement with both experimental and theoretical methods; ( 3) however, the measured velocities were clustered around few discrete values, rather than a range of velocities as would be expected if the particles were falling simultaneously and discretely. This new methodology has many new applications for local hazard mitigation and improved understanding of fallout processes
Multi sensor Evolution Analysis (MEA): Land use and land cover analysis applied to (A)ATSR time series.
No full textThe problem of (better) exploiting long-term satellite image databases is not yet resolved. Meanwhile the continuous growth of satellite data is generating an unprecedented increase in data types and volume. All this makes unrealistic to proceed with the current,
mainly manual, image processing. Therefore the upcoming challenge is to find new methods permitting in near real-time to store and access large data volumes and to simplify or even automate the extraction of meaningful information for application domains, such
as Land Use / Land Cover Change (LU/LCC) mapping. In the framework of the ESA Support by Pre-classification to Specific Applications (SPA) project a fully automatic LU/LCC application (initially named (A)ATSR Land Classification System (ALCS)) known
as Multi sensor Evolution Analysis (MEA) system, has been implemented and tested. MEA data store is built using 15 years of ATSR2-AATSR data (C1P 4713,C1P 5016)
Effect of CH4 addition on excess electron mobility in liquid Kr
No full textThe mobility μ of excess electrons has been measured in liquid mixtures of Kr and CH4 as a function of the electric field up to E~104 V/cm and of the CH4 concentration x up to x~10%, at a temperature T~125 K, fairly close to the normal boiling point of Kr (Tb~120 K) [Nucl. Instrum. Methods Phys. Res. A 430, 277 (1997)]. We present here new data extending the previous set in the low E region. At small E, μ appears to be quite independent of x. CH4 impurities prove to be less efficient in enhancing momentum transfer than liquified rare gas impurities Kr and Xe in liquid Ar. The dependence of μ on E at higher strengths is complicated. On the one hand, the addition of CH4 extends the range of E in which μ is field independent, by efficiently thermalizing the electrons. On the other hand, at the highest field, the presence of the impurities accomplishes a large increase of the electron drift velocity with respect to the pure liquid (up to a factor of 7 for the highest x). Moreover, at intermediate values of E, where electrons are epithermal, there appears to be a crossover between two different behaviors of μ as a function of E. The electric field strength at the crossover, E*, is well correlated with x. The behavior of μ can be rationalized in terms of a gas-kinetic model proposed to explain its concentration dependence in the liquified rare gas mixtures Ar-Kr and Ar-Xe. This analysis suggests that the observed crossover is related to the excitation of the first vibrational level of CH4
Land Classification System (LCS) - A system architecture for geospatial information processing for multi-temporal analysis
No full textAnalisi multispettrale ed iperspettrale di immagine Landsat TM e ETM + ChrisProba e Modis per l'individuazione e la classificazione di parametri chimici del suolo ad uso agricolo.
No full textSviluppo di un metodo di misura dei nutrienti chimici del suolo basato sull'utilizzo di analisi multispettrali ed iperspettrali da aereo e da satellite. lo scopo finale è di valutare il contenuto di ossidi di azoto, potassio, ferro e fosforo
Tecnologie innovative per l?analisi di variabili climatiche: attivita di ricerca per lo sviluppo di metodologie di analisi di dati pluvio-disdrometrici ed elaborazione di immagini telerilevate da satelliti meteorologici e di uso generale per analizzare e modellizzare le dinamiche climatologiche ed ambientali di medio e vasto raggio
No full textQuesto rapporto tecnico è generato quale documento conclusivo del progetto RIADE (Ricerca Integrata per l’Applicazione di tecnologie e processi innovativi per la lotta alla Desertificazione). In particolare, il presente rapporto sarà articolato in tre parti fondamentali. La prima, introduttiva, servirà per definire gli eventi analizzati nel presente rapporto, selezionati in base all’analisi condotta sui dati pluvio-disdrometrici, e per definire i satelliti utilizzati per l’analisi. La seconda parte illustra le tecniche satellitari utilizzate per l’analisi. Infine si mostreranno i risultati ottenuti. I dati Pludix sono infatti in grado di fornire i dati locali come descrittori degli eventi di precipitazione ed una accurata analisi climatologica degli eventi di precipitazione, ma con lo strumento non si e’ in grado di elaborare una analisi ad un’estensione spaziale maggiore (per la comprensione della scala spaziale degli eventi osservati) ed una analisi delle caratteristiche in nube degli eventi in studio, cioè della genesi degli eventi di precipitazione considerati. Tale analisi che utilizza strumenti satellitari si e’ pertanto resa necessaria per:
• avere una conferma della distinzione effettuata a terra (con Pludix) tra eventi stratiformi e convettivi;
• comprendere l’estensione spaziale relativa a ogni singolo evento e caratterizzarlo microfisicamente.
Infine si mostreranno i modelli di evoluzione di precipitazione più “tipici” per questa zona per il periodo analizzato e si riferiranno questi modelli a modelli concettuali di sistemi meteorologici a scala non locale. Si selezioneranno, fra i modelli concettuali comunemente utilizzati, quelli che, in base alla analisi di dati satellitari, si sono rivelati come più frequenti, relativamente alla area in studio. In tal modo si comprenderà quali sono, in prevalenza, le cause che generano le maggiori precipitazioni al di sopra dell’area in studio
Multitemporal data management and exploitation infrastructure
No full textThe development of new technologies and tools for as-much-as-possible automatic multi-temporal data analysis has been a goal for most of the institutions that aim at promoting the use of satellite data in different application domains. In the framework of the Support by Pre-classification to specific Applications Project, started in 2008, the European Space Agency has requested the development of a specific platform, named Multi-sensor Evolution Analysis (MEA), with the scope of demonstrating that long term satellite datasets coming from different sensors can be accessed and exploited in almost real time (few seconds) from a web application as user interface. The MEA system has been implemented based on 15 years of global (A)ATSR data (1 km resolution), together with 5 years of regional AVNIR-2 data (10 m resolution), with the final aim of permitting on-the-fly Land Use / Land Cover Change analysis. Moreover, a modified version of MEA has been set-up to permit the multi-temporal analysis of pollution maps coming from satellite observations and ground measurements, demonstrating the generality of the pursued approach. The present work aims at introducing the basis of the MEA system, describing the two implementations for land cover and pollution multi-temporal analysis, including external validation activities being performed for the first application by third parties
The multi-sensor land classification system (LCS): automatic multitemporal land use classification system for multi-resolution data.
No full textProviding land use/land cover change maps through the use of satellite imagery is very challenging and demanding in terms of
human interaction, mainly because of limited process automation. One main cause is that most of land use/land cover change
applications require multi-temporal acquisitions over the same area, that introduces the need for accurate pre-processing of the
dataset, in both geo-referencing and radiometry. Moreover, single multi-spectral images can be hundred of megabytes in size and
therefore image time series are even more difficult to be handled and processed in real time. The approach here proposed foresees
the use of a robust land cover classification system named SOIL MAPPER® to reduce input data size by assigning a semantic
meaning (in the land cover domain) to each pixel of a single image. Land cover transitions and land use maps can be expressed as
evolutions of land cover classes (features) on temporal domain. This permits to define ‘trajectories’ in the features – time space, that
define specific transition or periodic behaviour. The target system, named Land Classification System, provides fully automatic and
real time land use/land cover change analysis and includes fundamental sub-systems for accurate radiometric calibration, accurate
geo-referencing (with geolocation within the pixel size) and accurate remapping onto an Earth fixed grid. The characteristics of the
selected pre-classification system and Earth fixed grid allow general application across different sensors. Land Classification System
has been prototyped over 15 years of global (A)ATSR data and foresees integration of over 3 years of regional ALOS-AVNIR-2
data
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
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