617 research outputs found
Leveraging video annotations in video-based e-learning
The e-learning community has been producing and using video content for a
long time, and in the last years, the advent of MOOCs greatly relied on video
recordings of teacher courses. Video annotations are information pieces that
can be anchored in the temporality of the video so as to sustain various
processes ranging from active reading to rich media editing. In this position
paper we study how video annotations can be used in an e-learning context -
especially MOOCs - from the triple point of view of pedagogical processes,
current technical platforms functionalities, and current challenges. Our
analysis is that there is still plenty of room for leveraging video annotations
in MOOCs beyond simple active reading, namely live annotation, performance
annotation and annotation for assignment; and that new developments are needed
to accompany this evolution.Comment: 7th International Conference on Computer Supported Education (CSEDU),
Barcelone : Spain (2014
The Impact of Interface Quality on Trust in Web Retailers
Web retailing is expected to grow at aggressive rates in future years. One of the most important factors that is slowing down this growth is the lack of trust of potential customers. So, as transactions through the internet develop and mature, success will largely be dependent on gaining and0501ntaining this trust. It has been suggested that the quality of the user interface of the Web site is a determinant of the initial establishment of trust. In this article, we describe a study where 66 subjects were asked to perform some predefined book purchasing task in a series of sites with varying interface quality. We found a strong relationship between interface quality and trust. We also found some components of user interface quality to be more important than others and discuss the implications for Web site design. Le manque de confiance constitue une des barrières les plus importantes à l'adoption et au développement du commerce électronique. Centré sur le commerce électronique de détail, ce travail présente un modèle permettant d'analyser le développement de la confiance du consommateur en fonction des caractéristiques de ce dernier - sa propension - et de la perception qu'il a de certaines caractéristiques du commerçant, soit l'intégrité, l'habilité et la bienveillance de ce dernier. L'utilisabilité de l'interface graphique a été retenue comme étant le facteur-clé en ce qui concerne la perception de ces caractéristiques. Le rôle de chacune des dimensions composant l'utilisabilité a donc été étudié et mis en évidence relativement à la confiance développée par le consommateur.User interface, laboratory experiment, trust, usability, electronic retailing, web design, Interface utilisateur, expérimentation en laboratoire, confiance, b2c, commerce électronique (détail), design de site web
Instrumental genesis through interdisciplinary collaboration -- reflections on the emergence of a visualisation framework for video annotation data
Instrumental genesis through interdisciplinary collaboration-reflections on
the emergence of a visualisation framework for video annotation data XML This
paper presents, discusses and reflects on the development of a visualization
framework for the analysis of the temporal dynamics of audiovisual
expressivity. The main focus lies on the instrumental genesis process (Rabardel
1995; Longchamp 2012)-a concept trying to express and analyze the co-evolution
of instruments and the practices they make possible-underlying this
development. It is described through the collaboration and communication
processes between computer science scholars and humanities scholars in finding
new ways of visualizing complex datasets for exploration and presentation in
the realm of film-studies research. It draws on the outcome and concrete usage
of the visualizations in publications and presentations of a research group,
the AdAproject, that investigates the audiovisual rhetorics of affect in
audiovisual media on the financial crisis (2007-). These film analyses are
based on theoretical assumptions on the process of film-viewing, the relation
of the viewer's perception and the temporally unfolding audiovisual images, and
a methodical approach that draws on 'steps' in the research process such as
segmentation, description and qualification, called eMAEX (Kappelhoff et al.
2011-2016) to reconstruct these experiential figurations (Bakels et al. 2020a,
2020b). The main focus of this paper is the process of iterative development of
visualizations as interactive interfaces generated with the open-source
software Advene, that were an integral part of the research process. In this
regard, the timeline visualization is not only of interest for visual
argumentation in (digital) humanities publications, but also for the creation
of annotations as well as the exploration of this data. In the first part of
the paper we describe this interdisciplinary collaboration as instrumental
genesis on a general level-as an evolving and iterative process. In the second
part we focus on the specific challenge of designing a visualization framework
for the temporal dynamics of audiovisual aesthetics. Lastly we zoom out by
reflecting on experiences and insights that might be of interest for the wider
digital humanities community
Contributions to the geomagnetic secular variation from a reanalysis of core surface dynamics
We invert for motions at the surface of Earth's core under spatial and
temporal constraints that depart from the mathematical smoothings usually
employed to ensure spectral convergence of the flow solutions. Our spatial
constraints are derived from geodynamo simulations. The model is advected in
time using stochastic differential equations coherent with the occurrence of
geomagnetic jerks. Together with a Kalman filter, these spatial and temporal
constraints enable the estimation of core flows as a function of length and
time-scales. From synthetic experiments, we find it crucial to account for
subgrid errors to obtain an unbiased reconstruction. This is achieved through
an augmented state approach. We show that a significant contribution from
diffusion to the geomagnetic secular variation should be considered even on
short periods, because diffusion is dynamically related to the rapidly changing
flow below the core surface. Our method, applied to geophysical observations
over the period 1950-2015, gives access to reasonable solutions in terms of
misfit to the data. We highlight an important signature of diffusion in the
Eastern equatorial area, where the eccentric westward gyre reaches low
latitudes, in relation with important up/down-wellings. Our results also
confirm that the dipole decay, observed over the past decades, is primarily
driven by advection processes. Our method allows us to provide probability
densities for forecasts of the core flow and the secular variation.Comment: Geophysical Journal International publication; Earth core; Data
assimilation; Core flows inversion; 22 pages; 14 figure
Decision Support to Crowdsourcing for Annotation and Transcription of Ancient Documents: The RECITAL Workshop
In the 18th century in Paris, only two public theatres could officially
perform comedies: the Com{\'e}die-Fran{\c c}aise, and the
Com{\'e}die-Italienne. The latter was much less well known. By studying a
century of accounting registers, we aim to learn more about its successful
plays, its actors, musicians, set designers, and all the small trades necessary
for its operation, its administration, logistics and finances. To this end, we
employ a mass of untapped and unpublished resources, the 27,544 pages of 63
daily registers available at the Biblioth{\`e}que Nationale de France (BnF).
And we take a decidedly fresh look at emerging forms of creation and changes in
the entertainmenteconomy. We developed the crowdsourcing platform RECITAL to
collect and index the data from theregisters, following an emerging trend in
Digital Humanities. RECITAL is built upon the ScribeAPI framework and it offers
a fully-fledged web application to classify the pages, annotate with marks and
tags, transcribe the indexed marks and even to verify the previous transcripts.
We also describe a multi-level data model and to develop a series of monitoring
anddecision tools to support crowdsourced data management up to their
definitive form
Miniaturisation d'antennes en bande VHF pour applications spatiales
Le développement de l électronique embarquée et miniaturisée est pleinement d actualité de nos jours, dans les domaines tels que l armement, la médecine, et les télécommunications. La miniaturisation des antennes large-bande, opérationnelles sur plus d une décade, présentent un défi particulier. Ces travaux de thèse proposent de travailler sur la miniaturisation d une antenne spirale, afin d en réduire l encombrement, à savoir son diamètre, tout en conservant au mieux ses caractéristiques de rayonnement et polarisation intrinsèques. Cette recherche sera appliquée à la bande des Très hautes Fréquence (Very High Frequencies VHF), allant de 30MHz à 300MHz La géométrie inédite proposée consiste à associer à une antenne spirale un ensemble d anneaux résonnants, dont le diamètre n excède pas celui de la spirale, et permettant de diminuer la fréquence basse de fonctionnement. Pour un ensemble de cinq anneaux associé à la spirale, la réduction de la fréquence basse de fonctionnement est de plus de 30%. Pour deux antennes spirales de même fréquence basse de fonctionnement, l antenne miniaturisée a donc un diamètre réduit de 30%, soit une surface réduite de 50%. Les performances de l état de l art d après lesquelles les réductions sur le diamètre des antennes spirales n excèdent pas 15% sont donc dépassées. De plus, d après cet état de l art, les méthodes de réduction appliquées aux antennes large bande dégradent en général le gain et l axial ratio dans les bandes basses de fréquences de fonctionnement. La méthode proposée permet de conserver l efficacité de l antenne, voire de l augmenter, dans les fréquences proches de la fréquence basse de fonctionnement. Le rayonnement de l antenne spirale miniaturisée dans la bande passante de l antenne sans anneaux n est pour autant pas modifiée. Ces résultats très encourageant ont été confirmés par la mesure d antennes spirales miniaturisées, réalisées pour un diamètre de 8cm et de 1m : une réduction de 30% du diamètre sans dégradation du rayonnement a été observée. Les mesures ont par ailleurs donné lieu à l étude de la réalisation d une antenne en bande VHF, avec pour implication les problématiques de réalisation (masse, encombrement, résistance mécanique) et de mesure (isolation, effets parasites en VHF avec une longueur d onde de 4m).Miniaturizing electronic devices is a great challenge in crucial research domain such as defense, medicine, and telecommunications. Wideband antenna miniaturization operating on more than a decade is a particular issue. This thesis presents an original method for miniaturizing a spiral antenna, reducing its diameter while keeping its bandwidth, its radiating performances and its axial ratio characteristics. This method is applied to UHF spiral antenna (from 750MHz) and VHF antenna (from 75MHz). The new geometry adds stacked resonant rings to an Archimedean spiral antenna. Their diameter are the same, hence no rise of the antenna diameter. For a 5-ring spiral antenna, the lowest operating frequency reduction is higher than 30%. That is equivalent to a 30% reduction of the diameter for two antennas sharing the same lowest operating frequency, hence a 50% reduction of the area of the antenna. These reduction factors surpass the reduction factors of the state of art of 15%. Besides, according to the state of art, the miniaturizing techniques imply some degradation of the gain and axial ratio performances at the lowest operating frequencies. The new method improves on the other hand these characteristics at these frequencies. At higher frequencies, the rings do not interfere with the matching of neither the spiral antenna nor its radiation characteristics. These results were validated by fabricated antenna measurements. A 30% reduction of the diameter was obtained on a 5-ring-8cm-large antenna as well as on a 5-ring-1m-large antenna. No impairment was noticed on the radiation of the antennas, even at the lowest operating frequencies. The thesis also discusses the difficulties which came in addition for the fabrication (mass, size and mechanical resistance) and measurement (radiation interferences and measurement isolation the wavelength being 4m) of the VHF antenna.TOULOUSE-INP (315552154) / SudocSudocFranceF
Facile synthesis of high-surface area platinum-doped ceria for low temperature CO oxidation
International audienceUsing a simple slow decomposition method of nitrate precursors, high-surface area platinum-doped ceria with a crystallite size of 9 nm can be prepared. The catalytic performance of the compound can be tuned by changing the reduction temperature under hydrogen (300°C, 500°C and 700°C). The catalyst treated at 300°C shows the best catalytic performance, being active at room temperature. The materials were analysed using a combination of structural characterization methods (X-ray diffraction (XRD), nitrogen physisorption, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM)), surface sensitive methods (X-ray photoelectron spectroscopy (XPS), H 2-chemisorption and H 2-temperature-programmed reduction (TPR)) and X-ray absorption fluorescence spectroscopy (XAFS). HAADF-STEM and XAFS analysis suggests successful doping of platinum in the ceria lattice. After pretreatment at 300°C, the situation is slightly different. While no defined platinum nanoparticles can be identified on the surface, some platinum is in a reduced state (XPS, H 2-chemisorption)
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