Search results for "feature"
showing 10 items of 4091 documents
Unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes
2008
[i] We report the first measurements of volcanic gases with an unmanned aerial vehicle (UAV). The data were collected at La Fossa crater, Vulcano, Italy, during April 2007, with a helicopter UAV of 3 kg payload, carrying an ultraviolet spectrometer for remotely sensing the SO 2 flux (8.5 Mg d- 1 ), and an infrared spectrometer, and electrochemical sensor assembly for measuring the plume CO 2 /SO 2 ratio; by multiplying these data we compute a CO 2 flux of 170 Mg d -1 . Given the deeper exsolution of carbon dioxide from magma, and its lower solubility in hydro-thermal systems, relative to SO 2 , the ability to remotely measure CO 2 fluxes is significant, with promise to provide more profound…
Gas hazard assessment at the Monticchio crater lakes of Mt. Vulture, a volcano in Southern Italy
2009
Geochemical investigations have shown that there is a considerable inflow of gas into both crater lakes of Monticchio, Southern Italy. These lakes are located in two maars that formed 140 000 years ago during Mt. Vulture volcanos last eruptive activity. Isotopic analyses suggest that CO2 and helium are of magmatic origin; the latter displays 3 He ⁄ 4 He isotope ratios similar to those measured in olivines of the maar ejecta. In spite of the fact that the amount of dissolved gases in the water is less than that found in Lake Nyos (Cameroon), both the results obtained and the historical reports studied indicate that these crater lakes could be highly hazardous sites, even though they are loca…
First multi-GAS based characterisation of the Boiling Lake volcanic gas (Dominica, Lesser Antilles)
2013
We used a Multi-component Gas Analyser System (Multi-GAS) to measure, for the very first time, the composition (H2O, CO2, H2S, SO2) of the volcanic gas plume issuing from the Boiling Lake, a vigorously degassing, hot (T ~ 80-90°C) volcanic lake in Dominica, West Indies. The Multi-GAS captured in-plume concentrations of H2O, CO2 and H2S were well above those typical of ambient atmosphere, while no volcanic SO2 was detected (<0.05 ppm). These were used to derive the Boiling Lake plume characteristic ratios of CO2/H2S (5.2±0.4) and H2O/CO2 (31.4±6). Assuming that other volcanic gas species (e.g., HCl, CO, H2, N2, etc.) are absent in the plume, we recalculated a (air-free) composition fo…
. New ground-based lidar enables volcanic CO2 flux measurements
2015
AbstractThere have been substantial advances in the ability to monitor the activity of hazardous volcanoes in recent decades. However, obtaining early warning of eruptions remains challenging, because the patterns and consequences of volcanic unrests are both complex and nonlinear. Measuring volcanic gases has long been a key aspect of volcano monitoring since these mobile fluids should reach the surface long before the magma. There has been considerable progress in methods for remote and in-situ gas sensing, but measuring the flux of volcanic CO2—the most reliable gas precursor to an eruption—has remained a challenge. Here we report on the first direct quantitative measurements of the volc…
Immersive Virtual Reality in Experiential Learning : A Value Co-creation and Co-destruction Approach
2023
Immersive Virtual Reality (later VR) has its potential in enabling learning experiences. Several studies adopt experiential learning as a key concept to understand the outcomes of VR. This study consists of two parts – the first part conducts a systematic literature review on VR experiential learning and suggests seven main dimensions for the concept identified by the existing literature: engagement, sociability, contextual information, physical sensation, interactivity, cognitions, and presence. The second part adopts a value co-creation and co-destruction approach to empirically test the construction underlying VR experiential learning. The findings indicate 33 value co-creation and 19 va…
Cueva de El Toro (Antequera, Malaga-Spain): a Neolithic stockbreeding community in the Andalusian region, between the 6th and 3th millennia BC
2004
The occupation evidence shown by the cave El Toro, is that of a unique stockbreeding community in the Andalusian region. The calibrated dates for this occupation period go from the second quarter of the sixth millennium up to the second millennium BP. There is also evidence of occasional occupation throughout later millennia up to the Hispano-Muslim period. The nature of thisoccupation is determined by the close link between the cave and the community which occupied it, both continuously and periodically. Throughout the occupation levels, the community's skillful control of technical processesand its remarkable knowledge on how to transform local primary resources, have shown that this comm…
Recognition of briefly presented familiar and unfamiliar faces
2009
Early processing stages in the perception of familiar and unfamiliar faces were studied in four experiments by varying the type of available facial information in a four alternative forced choice recognition task. Both reaction time and recognition accuracy served as dependent measures. The observed data revealed an asymmetry in processing familiar and unfamiliar faces. A markedly weak inversion effect and strong blurring effect suggest a limited usage of spatial relations within early processing stages of unfamiliar faces. Recognition performance for whole familiar faces did not deteriorate due to blurring or the presentation of isolated internal features, suggesting a low level of represe…
Stability of Embankments Resting on Foundation Soils with A Weak Layer
2021
The presence of weak layers in geotechnical systems, including soil or rock masses, both natural and man-made, is more frequent than is normally believed. Weak layers can affect both failure mechanisms, in drained and in undrained conditions, as well as in static and seismic conditions, and the safety factor. In the present study, conducted numerically using the finite-element method (FEM) Plaxis 2D code, the influence of a horizontal thin weak layer on stress and strain distribution, on failure mechanisms and on the overall stability of an embankment was evaluated. The results obtained prove that when the weak layer is located at a significant depth from the foundation plane, the failure m…
Metaforas modes emuāros
2017
Lai gan metaforas pētījumi ir piesaistījuši daudzu zinātnieku uzmanību, metaforu lietojums modes emuāros nav daudz pētīts. Emuārs kā žanrs parādījās 2000.gadu sākumā un kopš tā laika ir izveidojušies dažādi emuāra veidi. Empīriskie dati ir ekscerpēti no modes emuāra The Blonde Salad. Pētījums ir izstrādāts, lai atbildētu uz pētījuma jautājumu - kāda metaforu funkcija dominē emuārā The Blonde Salad. Pētījuma mērķis ir noteikt avota domēnus, kas metaforiski raksturo modi izvēlētajā modes emuārā. Teorētiskā pētījuma daļa ir balstīta uz teorijām par metaforām, to funkcijām un iedalījumu tādu zinātnieku kā Lakofs, Džonsons, Gibs, Knovles, Mūns un Kovecses skatījumā. Empīŗiskais pētījums ir veikt…
Comparison of feature importance measures as explanations for classification models
2021
AbstractExplainable artificial intelligence is an emerging research direction helping the user or developer of machine learning models understand why models behave the way they do. The most popular explanation technique is feature importance. However, there are several different approaches how feature importances are being measured, most notably global and local. In this study we compare different feature importance measures using both linear (logistic regression with L1 penalization) and non-linear (random forest) methods and local interpretable model-agnostic explanations on top of them. These methods are applied to two datasets from the medical domain, the openly available breast cancer …