417 research outputs found

    End-to-end adaptation scheme for ubiquitous remote experimentation

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    Remote experimentation is an effective e-learning paradigm for supporting hands-on education using laboratory equipment at distance. The current trend is to enable remote experimentation in mobile and ubiquitous learning. In such a context, the remote experimentation software should enable effective telemonitoring and teleoperation, no matter the kind of device used to access the equipment. It should also be sufficiently lenient so as to handle the rapidly evolving wireless and mobile communication environment. While the current Internet bandwidth allows remote experimentation to work flawlessly on fixed connections such as LANs, mobile users suffer from both the versatile nature of wireless communications and the limitation of the mobile devices. These conditions impose that the remote experimentation software should integrate adaptation features. For effective ubiquitous remote experimentation, it should ideally be guaranteed that the information representing the state of the remote equipment is rendered (to the end user) at the same pace at which it has been acquired, yet possibly at the cost of a somewhat minimal time delay between the acquisition and rendering phases. In this respect, an end-to-end adaptation scheme is proposed that explicitly handles the inherent variability of the connection and the versatility of the mobile devices considered in ubiquitous remote experimentation. Instead of relying on a stochastic approach, the proposed adaptation scheme relies on a deterministic mass-balance equivalence model. The effectiveness of the proposed adaptation scheme is demonstrated in critical conditions corresponding to remote experimentation carried out using a PDA over a Bluetooth lin

    Motivic Weight Complexes for Arithmetic Varieties

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    We associate weight complexes of (homological) motives, and hence Euler characteristics in the Grothendieck group of motives, to arithmetic varieties and Deligne-Mumford stacks; this extends the results in the paper "Descent, Motives and K-theory" in volume 478 of Crelle, where a similar result was proved for varieties over a field of characteristic zero. We use K_0-motives with rational coefficients, rather than Chow motives, because we cannot appeal to resolution of singularities, but rather must use de Jong's results. In addition, for varieties over a field we prove a general result on contravariance of weight complexes, in particular showing that any morphism of finite tor-dimension between varieties induces a morphism of weight complexes.Comment: 52 pages. Proofs in section 56 have been clarified and a new section on Chow motives has been adde

    Use of 13C-NMR in structural elucidation of polysaccharides: case of locust bean gum

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    Locust bean gum (LBG) galactomannans are polysaccharides consisting of a β-(1→4) D-mannopyranosyl backbone substituted to varying degrees in α-(1→6) with single D-galactopyranosyl residues. This basic structure is the same for all galactomannans (Fig. 2). However, when locust bean gum is extracted at different temperatures, the generated fractions exhibit different properties in aqueous solution (viscosity, viscoelasticity, gel formation, thermohydrolysis resistance, etc.). This means that there are differences within the fine structure of the polymers (although the basic structure is the same). Analysis of [13C]-NMR spectra of galactomannans, in combination with other techniques, can provide capital information about fine structural elucidation of the polymers. The method specifies the distribution of lateral galactosyls along the main chain of mannans. Two fractions extracted from locust bean gum at 25 and 80 °C (respectively GM25 and GM80) were comparatively studied by [13C]-NMR. Mannosyls/Galactosyls (M/G) ratios can be determined by considering the intensities of C-1 mannose and galactose signals in [13C]-NMR spectra. This method provides results relatively close to those obtained by GC-MS analysis. Spectra also showed that resonance from C4 of D-mannose residues were split, in evident dependence upon the nearest-neighbor probabilities (“diad frequencies”) of D-galactosyl groups along the mannan chains (Fig. 2). Diad frequencies were obtained by integrating C4(Man) peak areas. F11, F21/F12 and F22 gave respectively the di-, mono- or non-substituted mannose pairs proportions. High percentages of F11 and F22 therefore indicate a more non-homogeneous distribution of lateral galactosyls along the polysaccharide backbone as observed for GM80. The percentages of total lateral substituents obtained by C4(Man) peak analysis [F11 + (F21 or F12)/2] were fairly well correlated with M/G ratios. Splitting of the C-6 substituted D-mannose resonance provides, therefore the basis for determining the next-nearest-neighbor probabilities (triad frequencies) (Fig. 2). However, the spectrum is often not sufficiently resolved to accurately quantify and interpret the results

    Maîtrise des risques dans les Très Petites Entreprises (TPE) : proposition d'un outil de diagnostic des vulnérabilités fondé sur le concept de cycle de vie

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    Au regard de son poids économique et social, la Très Petite Entreprise (TPE) devrait faire l'objet de toutes les attentions (qu'elles émanent des acteurs de la vie politique, sociale, économique...) dans le but de comprendre et de diminuer sa mortalité. Pourtant dans les faits, en France et en 2010, près de 97% des entreprises défaillantes sont des Très Petites Entreprises (TPE). Ce constat trouve son origine dans l'incapacité (ou la non volonté) individuelle et collective à définir précisément les caractéristiques de ce type d'organisations, empêchant ainsi une identification pertinente de leurs attentes et de leurs besoins

    Impact d'un fractionnement soustractif sur la relation structure-fonction de la gomme de caroube

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    Le choix d'une température de fractionnement de la gomme de caroube va conditionner les caractéristiques des fractions obtenues et par conséquent les potentialité d'applications de ces dernières

    Challenges in Remote Laboratory Sustainability

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    Remote experimentation facilities have been accessible from the Internet for more than a decade. However, sustainability of such services is not adequately ensured in many academic institutions. The major challenge lies in moving from a single research setup available occasionally to a professional remote laboratory infrastructure with many setups accessible worldwide and 24/7. Not only are the technical aspects demanding but also the usability of the solutions and the support of the customers are to be considered. On the technical side the solution should be robust to students and external malicious attack. It should be fully autonomous and capable of self-diagnosing. In case of problems it should be able to set itself back to a known stable state and report problem to the administrator. On the educational side, the learning environment should be reworked to consider the drawback inherent to the distance to make the student interaction with the distant system as close as possible as the actual work on the real equipment and enable collaborative work

    From online experiments to smart devices

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    Online experiments have been available for more than a decade. The integration of online experiments into collaborative environments is more recent. The wealth of client applications/environments, the versatility of possible interaction protocols/technologies and the needs for more autonomous actions impel the evolution of online experiments to the smart device concept. This paper reviews the evolution of an electrical drive experiment and presents the requirements for turning online experiments into smart devices

    The Smart Wind Turbine

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    Remote experimentation is at the core of Science Technology Engineering and Mathematics education supported by e-learning. The development and integration of remote labo- ratories in online learning activities is hindered by the inherited supporting infrastructure’s architecture and implementation. In this paper we present a remote experiment (The Smart Wind Tur- bine) built following the Smart Device Paradigm and integrated in an Inquiry Learning Space: the rich open educational resource defined in the EU project Go-Lab. Graasp- an educational social media platform, is the authoring and hosting tool. The Golabz platform is the dissemination medium among teachers and students

    Contextual Spaces with Functional Skins as OpenSocial Extension

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    Portability, flexibility and extensibility are essential features of social media platforms. When such Web platforms are able to take user's context into account, they provide better user experience and enhance the effectiveness of users' actions. In this paper, we discuss an extension to OpenSocial standard, namely contextual space, that shapes the framework, in which people carry out online activities. The proposed contextual space extension defines how a set of OpenSocial widgets are aggregated as a Web environment for a given purpose and with a given functional skin as a user interface. Additionally it allows to create contextualized widgets. In this paper we discuss the proposed extension in details and provide the examples of its use based on real life scenarios. Finally, we detail an implementation scheme
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