1,720,961 research outputs found
Dynamic State Estimation for Improving Observation and Resiliency of Interconnected Power Systems
No full textThis article investigates a particle filter (PF)-based fully-decentralised dynamic state estimation (DSE) method for interconnected multi-machine power systems. The PF-based observer is developed to dynamically estimate the states of the 7th-order dynamic model of synchronous machines that are either inaccessible and/or highly noisy. It is assumed that the proposed PF-based robust decentralized observer for a particular synchronous generating unit relies on typical output measurements available from phasor measurement units (PMUs) installed at its terminal. The performance of the presented observer is investigated using the benchmark model of the IEEE 68-bus system considering a detailed sub-transient representative model of synchronous machines with different excitation and control systems. The presented estimation framework works successfully and accurately under various transient events, such as load perturbation, faults, and changes in network topology, while accounting for different errors and sampling rates in measurements. The accuracy and robustness of the presented dynamic estimator in the case of Gaussian and non-Gaussian noisy measurements are verified. The paper also develops an approach-based PF to detect bad data and introduces a new metric based on the computation Cramer-Rao Low bound (CRLB) for evaluating the dynamic estimation performance. The introduced PF-based DSE improves the system resiliency by providing the system operator with the monitoring and observation capability of the system in a real-time manner to perform the proper corrective and protective actions in case of any events. The comparative study with other sophisticated dynamic state estimators confirms the brilliance, robustness, and superiority of the presented PF-based dynamic state estimation for multi-machine systems, and its practical and implementation feasibility
Flatness-based control in successive loops for mechatronic motion transmission systems
No full textMechatronic systems with nonlinear dynamics are met in motion transmission applications for vehicles and robots. In this article, the control problem for the nonlinear dynamics of mechatronic motion transmission systems is solved with the use of a flatness-based control approach which is implemented in successive loops. The state-space model of these systems is separated into a series of subsystems, which are connected between them in cascading loops. Each one of these subsystems can be viewed independently as a differentially flat system, and control about it can be performed with inversion of its dynamics as in the case of input–output linearized flat systems. In this chain of i = 1, 2, … ,N subsystems, the state variables of the subsequent (i+1)-th subsystem become virtual control inputs for the preceding i-th subsystem and so on. In turn, exogenous control inputs are applied to the last subsystem and are computed by tracing backwards the virtual control inputs of the preceding N − 1 subsystems. The whole control method is implemented in successive loops, and its global stability properties are also proven through Lyapunov stability analysis. The validity of the control method is confirmed in the following two case studies: (a) control of a permanent magnet linear synchronous motor (PMLSM)-actuated vehicle's clutch and (ii) control of a multi-Degrees of Freedom (multi-DOF) flexible joint robot.(a) Gerasimos Rigatos has been partially supported by grant ref. 301022 “Nonlinear optimal and flatness-based control methods for complex dynamical systems” of the Unit of Industrial Automation, Industrial Systems Institute, Greece. (b) Pierluigi Siano and Mohammed AL-Numay acknowledge financial support from the Researchers Supporting Project (number RSP2023R150), King Saud University, Riyadh, Saudi Arabia
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
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
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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