1,720,971 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Contrôle tolérant aux défauts basé observateurs par intervalle pour systèmes LPV commutés
No full textSwitched systems have drawn considerable attention from researchers due to their ability to model a variety of practical systems. The synthesis of observers for this class of systems has gained increasing interest over the past few decades since the estimation plays a fundamental role in determining the current system states, including measured and unmeasured variables, which is crucial for fault diagnosis and control. However, the conventional observer synthesis technique may struggle to cope with the uncertainties, resulting in reduced estimation accuracy and reliability. Moreover, in practical engineering applications, it is inevitable to encounter unknown inputs and faults due to unpredictable external disturbances, measurement noise, and potential actuator faults. Such factors may cause system performance degradation, instability, or even catastrophic failures. It is, therefore essential to enhance the system safety and reliability by developing well-designed algorithms that can effectively estimate and compensate for faults affecting the performance. The objective of this research is to provide some contributions to the state-of-the-art in the field of robust state estimation and fault-tolerant control (FTC) for a class of switched systems by addressing the aforementioned problems. The present research mainly focuses on addressing the challenge of robust state bounding estimation using interval observer techniques for uncertain switched systems subject to unknown but bounded exogenous disturbances and/or measurement noise. Based on the cooperativity system theory, the methodology presents novel interval observer structures that provide notable improvement, particularly in enhancing the robustness and accuracy of state estimation under uncertain conditions. In contrast to conventional observers may struggle to deal with uncertainties, the proposed observer can effectively cope with the problems by offering guaranteed lower and upper bounds of state estimations. In addition to robust state estimation, the thesis also focuses on the synthesis of active fault-tolerant control (AFTC) strategies designed to preserve system stability and ensure desired performance levels, even in the presence of faults. The approach employs a co-design methodology, which integrates the design of observers and controllers into a cohesive framework. This integrated design approach considers the bi-directional interaction between the estimation process and control actions, leading to the optimized overall system performance and enhanced resilience to faults.Sufficient conditions for proving the existence of the interval observers and controllers are formulated in terms of Linear Matrix Inequalities (LMIs) constraints. These conditions are derived through a combination of Lyapunov theory and Input-to-State-Stability (ISS) under the Average-Dwell Time (ADT) concept. Finally, to validate the efficacy of the proposed interval observer structures and the synthesized control laws, an application to the vehicle lateral dynamics model is presented, using MATLAB Simulink. The simulations validate the robustness of the interval observer structures and fault-tolerant control strategies, showing that the proposed approach can effectively maintain vehicle stability and control even in challenging and unpredictable environments. The results highlight the ability of the interval observers to accurately bound state estimates despite uncertainties, while the synthesized control laws successfully ensure system stability and performance even in the occurrence of faults.Les systèmes à commutation attirent de plus en plus l'attention dans le domaine scientifique grâce à leur capacité à représenter des phénomènes complexes issus de diverses applications en ingénierie. L'estimation d'état joue un rôle clé dans ces systèmes, notamment pour le diagnostic de pannes et le contrôle. Toutefois, les méthodes classiques d'observateurs peinent à traiter efficacement les incertitudes, limitant ainsi la précision et la fiabilité des résultats. Dans les applications industrielles, les perturbations externes, le bruit de mesure ou les défaillances d'actionneurs engendrent fréquemment des entrées inconnues ou des défauts. Ces aléas peuvent dégrader les performances, provoquer une instabilité, voire conduire à des dysfonctionnements critiques. Il devient donc primordial de développer des solutions algorithmiques robustes pour estimer et compenser ces anomalies, améliorant ainsi la sûreté de fonctionnement. L'un des axes principaux de cette étude concerne l'estimation d'état robuste par intervalles, une approche novatrice permettant de borner les états malgré des perturbations bornées ou un bruit de mesure. Fondée sur la théorie des systèmes coopératifs, la méthodologie proposée garantit des bornes inférieures et supérieures aux estimations, offrant une robustesse accrue face aux incertitudes par rapport aux observateurs conventionnels. Parallèlement, des stratégies de commande active tolérante aux défauts (AFTC) sont développées pour maintenir la stabilité et les performances du système, même en présence de défauts. Une approche de co-conception intègre observateurs et contrôleurs dans un cadre unifié, tenant compte des interactions entre estimation et commande. Cette synergie optimise la résilience globale et les performances. Les conditions d'existence des observateurs par intervalles et des contrôleurs sont exprimées via des inégalités matricielles linéaires (LMIs), dérivées de la théorie de Lyapunov et de la stabilité entrée-état (ISS) sous contraintes de temps de commutation moyen (ADT). Enfin, les applications à la dynamique latérale d'un véhicule, simulée sous MATLAB/Simulink, valide l'efficacité des solutions proposées. Les résultats démontrent que les observateurs par intervalles maintiennent des estimations précises malgré les incertitudes, tandis que les lois de commande AFTC préservent la stabilité et les performances, même dans des scénarios dégradés. Ces contributions renforcent la fiabilité des systèmes complexes soumis à des environnements imprévisibles
Contrôle tolérant aux défauts basé observateurs par intervalle pour systèmes LPV commutés
No full textLes systèmes à commutation attirent de plus en plus l'attention dans le domaine scientifique grâce à leur capacité à représenter des phénomènes complexes issus de diverses applications en ingénierie. L'estimation d'état joue un rôle clé dans ces systèmes, notamment pour le diagnostic de pannes et le contrôle. Toutefois, les méthodes classiques d'observateurs peinent à traiter efficacement les incertitudes, limitant ainsi la précision et la fiabilité des résultats. Dans les applications industrielles, les perturbations externes, le bruit de mesure ou les défaillances d'actionneurs engendrent fréquemment des entrées inconnues ou des défauts. Ces aléas peuvent dégrader les performances, provoquer une instabilité, voire conduire à des dysfonctionnements critiques. Il devient donc primordial de développer des solutions algorithmiques robustes pour estimer et compenser ces anomalies, améliorant ainsi la sûreté de fonctionnement. L'un des axes principaux de cette étude concerne l'estimation d'état robuste par intervalles, une approche novatrice permettant de borner les états malgré des perturbations bornées ou un bruit de mesure. Fondée sur la théorie des systèmes coopératifs, la méthodologie proposée garantit des bornes inférieures et supérieures aux estimations, offrant une robustesse accrue face aux incertitudes par rapport aux observateurs conventionnels. Parallèlement, des stratégies de commande active tolérante aux défauts (AFTC) sont développées pour maintenir la stabilité et les performances du système, même en présence de défauts. Une approche de co-conception intègre observateurs et contrôleurs dans un cadre unifié, tenant compte des interactions entre estimation et commande. Cette synergie optimise la résilience globale et les performances. Les conditions d'existence des observateurs par intervalles et des contrôleurs sont exprimées via des inégalités matricielles linéaires (LMIs), dérivées de la théorie de Lyapunov et de la stabilité entrée-état (ISS) sous contraintes de temps de commutation moyen (ADT). Enfin, les applications à la dynamique latérale d'un véhicule, simulée sous MATLAB/Simulink, valide l'efficacité des solutions proposées. Les résultats démontrent que les observateurs par intervalles maintiennent des estimations précises malgré les incertitudes, tandis que les lois de commande AFTC préservent la stabilité et les performances, même dans des scénarios dégradés. Ces contributions renforcent la fiabilité des systèmes complexes soumis à des environnements imprévisibles.Switched systems have drawn considerable attention from researchers due to their ability to model a variety of practical systems. The synthesis of observers for this class of systems has gained increasing interest over the past few decades since the estimation plays a fundamental role in determining the current system states, including measured and unmeasured variables, which is crucial for fault diagnosis and control. However, the conventional observer synthesis technique may struggle to cope with the uncertainties, resulting in reduced estimation accuracy and reliability. Moreover, in practical engineering applications, it is inevitable to encounter unknown inputs and faults due to unpredictable external disturbances, measurement noise, and potential actuator faults. Such factors may cause system performance degradation, instability, or even catastrophic failures. It is, therefore essential to enhance the system safety and reliability by developing well-designed algorithms that can effectively estimate and compensate for faults affecting the performance. The objective of this research is to provide some contributions to the state-of-the-art in the field of robust state estimation and fault-tolerant control (FTC) for a class of switched systems by addressing the aforementioned problems. The present research mainly focuses on addressing the challenge of robust state bounding estimation using interval observer techniques for uncertain switched systems subject to unknown but bounded exogenous disturbances and/or measurement noise. Based on the cooperativity system theory, the methodology presents novel interval observer structures that provide notable improvement, particularly in enhancing the robustness and accuracy of state estimation under uncertain conditions. In contrast to conventional observers may struggle to deal with uncertainties, the proposed observer can effectively cope with the problems by offering guaranteed lower and upper bounds of state estimations. In addition to robust state estimation, the thesis also focuses on the synthesis of active fault-tolerant control (AFTC) strategies designed to preserve system stability and ensure desired performance levels, even in the presence of faults. The approach employs a co-design methodology, which integrates the design of observers and controllers into a cohesive framework. This integrated design approach considers the bi-directional interaction between the estimation process and control actions, leading to the optimized overall system performance and enhanced resilience to faults.Sufficient conditions for proving the existence of the interval observers and controllers are formulated in terms of Linear Matrix Inequalities (LMIs) constraints. These conditions are derived through a combination of Lyapunov theory and Input-to-State-Stability (ISS) under the Average-Dwell Time (ADT) concept. Finally, to validate the efficacy of the proposed interval observer structures and the synthesized control laws, an application to the vehicle lateral dynamics model is presented, using MATLAB Simulink. The simulations validate the robustness of the interval observer structures and fault-tolerant control strategies, showing that the proposed approach can effectively maintain vehicle stability and control even in challenging and unpredictable environments. The results highlight the ability of the interval observers to accurately bound state estimates despite uncertainties, while the synthesized control laws successfully ensure system stability and performance even in the occurrence of faults
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Contrôle tolérant aux défauts basé observateurs par intervalle pour systèmes LPV commutés
No full textSwitched systems have drawn considerable attention from researchers due to their ability to model a variety of practical systems. The synthesis of observers for this class of systems has gained increasing interest over the past few decades since the estimation plays a fundamental role in determining the current system states, including measured and unmeasured variables, which is crucial for fault diagnosis and control. However, the conventional observer synthesis technique may struggle to cope with the uncertainties, resulting in reduced estimation accuracy and reliability. Moreover, in practical engineering applications, it is inevitable to encounter unknown inputs and faults due to unpredictable external disturbances, measurement noise, and potential actuator faults. Such factors may cause system performance degradation, instability, or even catastrophic failures. It is, therefore essential to enhance the system safety and reliability by developing well-designed algorithms that can effectively estimate and compensate for faults affecting the performance. The objective of this research is to provide some contributions to the state-of-the-art in the field of robust state estimation and fault-tolerant control (FTC) for a class of switched systems by addressing the aforementioned problems. The present research mainly focuses on addressing the challenge of robust state bounding estimation using interval observer techniques for uncertain switched systems subject to unknown but bounded exogenous disturbances and/or measurement noise. Based on the cooperativity system theory, the methodology presents novel interval observer structures that provide notable improvement, particularly in enhancing the robustness and accuracy of state estimation under uncertain conditions. In contrast to conventional observers may struggle to deal with uncertainties, the proposed observer can effectively cope with the problems by offering guaranteed lower and upper bounds of state estimations. In addition to robust state estimation, the thesis also focuses on the synthesis of active fault-tolerant control (AFTC) strategies designed to preserve system stability and ensure desired performance levels, even in the presence of faults. The approach employs a co-design methodology, which integrates the design of observers and controllers into a cohesive framework. This integrated design approach considers the bi-directional interaction between the estimation process and control actions, leading to the optimized overall system performance and enhanced resilience to faults.Sufficient conditions for proving the existence of the interval observers and controllers are formulated in terms of Linear Matrix Inequalities (LMIs) constraints. These conditions are derived through a combination of Lyapunov theory and Input-to-State-Stability (ISS) under the Average-Dwell Time (ADT) concept. Finally, to validate the efficacy of the proposed interval observer structures and the synthesized control laws, an application to the vehicle lateral dynamics model is presented, using MATLAB Simulink. The simulations validate the robustness of the interval observer structures and fault-tolerant control strategies, showing that the proposed approach can effectively maintain vehicle stability and control even in challenging and unpredictable environments. The results highlight the ability of the interval observers to accurately bound state estimates despite uncertainties, while the synthesized control laws successfully ensure system stability and performance even in the occurrence of faults.Les systèmes à commutation attirent de plus en plus l'attention dans le domaine scientifique grâce à leur capacité à représenter des phénomènes complexes issus de diverses applications en ingénierie. L'estimation d'état joue un rôle clé dans ces systèmes, notamment pour le diagnostic de pannes et le contrôle. Toutefois, les méthodes classiques d'observateurs peinent à traiter efficacement les incertitudes, limitant ainsi la précision et la fiabilité des résultats. Dans les applications industrielles, les perturbations externes, le bruit de mesure ou les défaillances d'actionneurs engendrent fréquemment des entrées inconnues ou des défauts. Ces aléas peuvent dégrader les performances, provoquer une instabilité, voire conduire à des dysfonctionnements critiques. Il devient donc primordial de développer des solutions algorithmiques robustes pour estimer et compenser ces anomalies, améliorant ainsi la sûreté de fonctionnement. L'un des axes principaux de cette étude concerne l'estimation d'état robuste par intervalles, une approche novatrice permettant de borner les états malgré des perturbations bornées ou un bruit de mesure. Fondée sur la théorie des systèmes coopératifs, la méthodologie proposée garantit des bornes inférieures et supérieures aux estimations, offrant une robustesse accrue face aux incertitudes par rapport aux observateurs conventionnels. Parallèlement, des stratégies de commande active tolérante aux défauts (AFTC) sont développées pour maintenir la stabilité et les performances du système, même en présence de défauts. Une approche de co-conception intègre observateurs et contrôleurs dans un cadre unifié, tenant compte des interactions entre estimation et commande. Cette synergie optimise la résilience globale et les performances. Les conditions d'existence des observateurs par intervalles et des contrôleurs sont exprimées via des inégalités matricielles linéaires (LMIs), dérivées de la théorie de Lyapunov et de la stabilité entrée-état (ISS) sous contraintes de temps de commutation moyen (ADT). Enfin, les applications à la dynamique latérale d'un véhicule, simulée sous MATLAB/Simulink, valide l'efficacité des solutions proposées. Les résultats démontrent que les observateurs par intervalles maintiennent des estimations précises malgré les incertitudes, tandis que les lois de commande AFTC préservent la stabilité et les performances, même dans des scénarios dégradés. Ces contributions renforcent la fiabilité des systèmes complexes soumis à des environnements imprévisibles
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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