232 research outputs found

    Principes alternatifs pour la détection de masse ultime via la dynamique non linéaire de capteurs résonants M/NEMS

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    Resonant M/NEMS mass sensors are widely used in biological environment for measuring the mass of biomolecules due to their high accuracy combined with a reduced size. Usually, the detection and the quantification are based on the frequency shift induced by an added mass. However, this shift becomes very small and difficult to distinguish from the noise of measurement as the considered masses are tiny. It is theoretically possible to increase further one or several orders of magnitude in resolution with these frequency methods by further reducing size and/or by increasing the signal-to-noise ratio, that is to say by operating more importantly the resonators. But in these conditions, the nanoresonators have a strongly nonlinear behavior, a source of instability and noise mix of low and high frequencies likely to degrade the reliability and the accuracy of measurements. Therefore, the thesis’s objective is to define alternative principles of detection based on exploiting the nonlinear phenomena, such as the hysteretic behavior and the bifurcations of frequency-response curves. To this end, a reduced model of resonant micro/nano-beam with electrostatic actuation is considered. The numerical results show that the sudden jumps in amplitude close to bifurcation points allow the detection of very small masses. Unlike the frequency detection, the smaller the added mass, the larger the increase of the jump, which makes this technique particularly interesting. In addition, the detection threshold can be adjusted with the value of the operating frequency. However, a mechanism of reinitialization is mandatory to make the detection possible again after a jump in amplitude. In order to automate the reinitialization and allow the detection in real-time, a completely innovative concept of mass detection by the frequency sweep of the hysteretic cycles is proposed to detect, quantify and locate the added mass on the resonant beam. An array of several resonant beams is also considered and constitutes a first step toward the implementation of arrays of thousands of sensors. Efficient architectures are proposed for this purpose and the numerical models are adapted accordingly. On symmetric configurations, exploiting the bifurcations of symmetry-breaking type allows here again to improve the mass detection.Les capteurs résonants de type M/NEMS sont largement utilisés dans l’environnement biologique pour la mesure de masse de biomolécules en raison de leur grande précision combinée à une taille réduite. Classiquement, la détection et la quantification se basent sur le décalage fréquentiel induit par la masse ajoutée. Toutefois, ce décalage devient très faible et difficile à distinguer du bruit de mesure lorsque les masses considérées sont très petites. Il est théoriquement possible de gagner encore un ou plusieurs ordres de grandeur en résolution avec ces méthodes fréquentielles en diminuant encore les tailles et/ou en augmentant le rapport signal sur bruit, c’est-à-dire en actionnant de manière plus importante les résonateurs. Mais, dans ces conditions, les nanorésonateurs ont un comportement très fortement non-linéaire, source d’instabilités et de mixage de bruit basses et hautes fréquences susceptibles de dégrader la fiabilité et la précision des mesures. C’est pourquoi cette thèse a pour objectif de définir des principes de détection alternatifs basés sur l’exploitation des phénomènes non-linéaires, tels que les comportements hystérétiques et les bifurcations des courbes de réponse en fréquence. Pour cela, un modèle réduit de micro/nano-poutre résonante avec actionnement électrostatique est considéré. Les résultats numériques montrent que les brusques sauts d’amplitude à proximité des points de bifurcation permettent la détection de masses très faibles. Contrairement à la détection fréquentielle, ces sauts sont d’autant plus grands que la masse additionnelle est petite, ce qui rend cette technique particulièrement intéressante. De plus, le seuil de détection peut être ajusté avec la valeur de la fréquence de fonctionnement. Un mécanisme de réinitialisation est toutefois indispensable pour rendre la détection à nouveau possible après un saut d’amplitude. Afin d’automatiser la réinitialisation et ainsi permettre la détection en temps réel, un concept totalement innovant de détection de masse par balayage en fréquence des cycles d’hystérésis est proposé, qui permet de détecter, quantifier et localiser la masse ajoutée sur la poutre résonante. La mise en réseau de plusieurs poutres résonantes est également traitée et constitue un premier pas vers la mise en oeuvre de réseaux de milliers de capteurs. Pour cela, des architectures efficaces sont proposées et les modèles numériques sont adaptés en conséquence. Sur des configurations symétriques, l’exploitation des bifurcations de type brisure de symétrie permet là-encore d’améliorer la détection de masse

    Barriers Affecting the Acceptance of Tourism Apps Among Tourists

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    The development of technology applications has brought many benefits to users. However, users face certain risks when adopting new technology applications. This leads to barriers affecting the acceptance of new technology applications. The study was carried out to identify the barriers affecting the acceptance of tourism apps by tourists. Research data were collected by the method of quota sampling, with a sample size of 222 tourists who have visited and experienced tourism services at famous destinations in Vietnam. Qualitative research methods and quantitative research methods are both applied to test the research hypotheses. The structural equation modeling (SEM) has demonstrated that insecurity and discomfort positively affect tourists’ perceived risk of tourism apps. Also, insecurity, discomfort, and perceived risk negatively affect tourists’ acceptance of travel apps

    Alternative mass sensing techniques based on nonlinear phenomena in M/NEMS resonators

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    International audienceThis paper investigates alternative mass sensing techniques that take advantage of multi-stability and bifurcations observed in the nonlinear regime. A finite-degree-of-freedom reduced-order model of an electrostatically-actuated microbeam with small added mass is considered. Strategies are proposed for robust real-time detection, quantification and localization of the added mass

    What Do WEIRD and Non-WEIRD Conversational Agent Users Want and Perceive? Towards Transparent, Trustworthy, Democratized Agents

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    A majority of researchers who develop design guidelines have WEIRD, adult perspectives. This means we may not have technology developed appropriately for people from non-WEIRD countries and children. We present five design recommendations to empower designers to consider diverse users' desires and perceptions of agents. For one, designers should consider the degree of task-orientation of agents appropriate to end-users' cultural perspectives. For another, designers should consider how competence, predictability, and integrity in agent-persona affects end-users' trust of agents. We developed recommendations following our study, which analyzed children and parents from WEIRD and non-WEIRD countries' perspectives on agents as they create them. We found different subsets of participants' perceptions differed. For instance, non-WEIRD and child perspectives emphasized agent artificiality, whereas WEIRD and parent perspectives emphasized human-likeness. Children also consistently felt agents were warmer and more human-like than parents did. Finally, participants generally trusted technology, including agents, more than people.Comment: 24 pages, 13 figures, submitted to CHI 2023, for associated appendix: https://gist.github.com/jessvb/fa1d4c75910106d730d194ffd4d725d

    International experience in organization of teaching practice in teacher training and some recommendations

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    Given the strict guideline and significant innovation from the Laos Government, there are certain limitations in teacher training in Laos. This paper focuses on selected internationally published works on training teaching skills for prospective teachers (pre-service teachers) with document analysis method on articles and books of authors outside Laos. Subsequently, some recommendations to help innovate the pre-service teacher training process in Laos would be proposed in order to contribute to the development of teachers’ pedagogical competencies. It is suggested that the time allowance for pedagogical practice in high schools with the guidance of expert teachers, possibly through lesson planning and micro-teaching be increased. It is also necessary to pay more attention to equip teacher trainees with skills in using information technology and software in teaching (in particular pre-service mathematics teachers)

    BISMUTH FILM ELECTRODE FOR STRIPPING VOLTAMMETRIC DETERMINATION OF BLOOD LEAD AND PRELIMINARY ASSESSMENT OF BLOOD LEAD LEVEL IN THE RESIDENTS AT CANH DUONG VILLAGE, THUA THIEN HUE PROVINCE

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    Joint Research on Environmental Science and Technology for the Eart

    BISMUTH FILM ELECTRODE FOR MEASUREMENT OF TRACE LEAD BY ADSORPTIVE STRIPPING VOLTAMMETRY WITH CALCEIN BLUE

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    Joint Research on Environmental Science and Technology for the Eart

    CLASSIFICATION AND ZONING OF WATER QUALITY FOR MAIN RIVERS IN BINH TRI THIEN REGION (CENTRAL VIETNAM) BASED ON WATER QUALITY INDEX

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    Joint Research on Environmental Science and Technology for the Eart

    Aplicação da habilidade de metacognição em métodos de solução de problemas para estudantes do ensino médio

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    Currently, policy makers around the world are trying to reform the educational system in general and Mathematics education in particular to create a fundamental change in the content, curriculum and students’ methods of learning Mathematics. Innovative efforts in Mathematics education focus on helping students develop the core competencies of the 21st century to create more educational and career choices for students in the future. Metacognition or thinking about thinking refers to an individual's ability to control his or her thinking processes, especially the perception of choosing and using problem-solving strategies. To find solutions to the problems mentioned, a number of studies have focused on understanding the role of metacognition in problem solving activities in the teaching process of Mathematics. In this study we will explore some metacognitive models in Mathematics education, therefor, we research “Application of metacognition skill to methods problem solution for secondary school students”.Actualmente, los responsables políticos de todo el mundo están tratando de reformar el sistema educativo en general y la educación matemática en particular para crear un cambio fundamental en el contenido, el plan de estudios y los métodos de aprendizaje de las matemáticas por parte de los estudiantes. Los esfuerzos innovadores en la educación matemática se centran en ayudar a los estudiantes a desarrollar las competencias básicas del siglo XXI para crear más opciones educativas y profesionales para los estudiantes en el futuro. La metacognición o pensamiento sobre el pensamiento se refiere a la capacidad de un individuo para controlar sus procesos de pensamiento, especialmente la percepción de elegir y utilizar estrategias de resolución de problemas. Para encontrar soluciones a los problemas mencionados, una serie de estudios se han centrado en comprender el papel de la metacognición en las actividades de resolución de problemas en el proceso de enseñanza de las matemáticas. En este estudio exploraremos algunos modelos metacognitivos en la educación matemática, para ello investigamos “Aplicación de la habilidad metacognitiva a métodos de solución de problemas para estudiantes de secundaria”.Atualmente, os formuladores de políticas em todo o mundo estão tentando reformar o sistema educacional em geral e a educação matemática em particular para criar uma mudança fundamental no conteúdo, no currículo e nos métodos de aprendizagem de matemática dos estudantes. Esforços inovadores na educação em Matemática concentram-se em ajudar os estudantes a desenvolver as competências centrais do século 21 para criar mais opções educacionais e de carreira para os estudantes no futuro. Metacognição ou pensar em pensar refere-se à capacidade de um indivíduo de controlar seus processos de pensamento, especialmente a percepção de escolher e usar estratégias de resolução de problemas. Para encontrar soluções para os problemas mencionados, vários estudos se concentraram na compreensão do papel da metacognição nas atividades de resolução de problemas no processo de ensino de Matemática. Neste estudo vamos explorar alguns modelos metacognitivos na educação matemática, por isso, pesquisamos “Aplicação da habilidade de metacognição em métodos de solução de problemas para estudantes do ensino médio”

    IMPACT OF SEA LEVEL RISE ON COASTAL RESOURCE IN VIETNAM

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    Joint Research on Environmental Science and Technology for the Eart
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