1,720,991 research outputs found
Robust Nonlinear Feedback Linearizing Control for Power Systems to Enhance Transient Stability
Full text linkStability is an important issue for the secure operation of power systems as an unsecured system faces a lot of unusual operating conditions and due to these unusual operating conditions, power systems can undergo blackouts which cause a
huge losses. In addition, the demand on power systems is increasing consistently
for which the recent trend is to operate the system near to the extreme conditions.
The changing characteristics of power systems continue to provide new challenges
to the system designers and operators. To mitigate the constraints related to power
system stability, the design and implementation of high-performance controllers are
crucial which is the key focus of this dissertation.
The first contribution of this work is to design a nonlinear excitation controller to
enhance transient stability. To clearly identify the necessity of new controllers, analyses
have been performed to determine the limitations of existing linear controllers.
In this thesis, the feedback linearization technique which transforms a nonlinear system
into a fully (exactly) or partially linear system based on the selection of output
function, is proposed. The proposed feedback linearizing is mainly based on the
partial feedback linearization technique which transforms the power system into a
partially linearized system and is novel in power system applications. The proposed
control scheme offers several benefits as compared to the feedback linearization that
transforms a power system into a fully linear one.
To implement a control algorithm in an accurate and effective manner, it is essential
to express the control law in terms of all measured variables. The control law
obtained through feedback linearization is in terms of the states of the power system
and some assumptions must be satisfied to express the state variables in terms of
measured variables. To validate the accuracy of these assumptions, it is essential
to design an effective observer which is capable to estimate the states of power systems under different changing conditions. The second and other unique contribution
of this dissertation is to design a novel nonlinear state observer for power systems
based on the feedback linearization technique and the observed states are used as
the feedback variables for feedback linearizing controllers. In this contribution, both
the full and partial feedback linearization are considered to provide a deep insight
regarding the proposed scheme. The comparisons between the performances of the controller with observed states and measured variables feedbacks are presented with
a view to look at the suitability of the assumptions.
The other significant contribution of this research is to design a robust nonlinear
controller for power systems to improve the performance by considering the mismatch
between the original system model and the considered mathematical model.
This part of the dissertation considers the uncertainty within the power system
model where the uncertainties are bounded in such a way that the proposed controller
can guarantee the stability and enhance the performance for all possible
perturbations within the given upper bounds on the modeling error of nonlinear
power systems. The effectiveness of the proposed controller is tested on small and
large power systems.
The current trend is the inclusion of renewable energy sources into the distribution
network to get some technical and economical benefits from the existing
systems. Since the integration of photovoltaic systems is increasing, this dissertation
proposes the design of a novel controller based on partial feedback linearization
to ensure the dynamic stability under changing conditions of the system.
The final contribution of this dissertation is to develop the relationship between
the amount of generation that can be integrated into the distribution networks and
the voltage variation which is a prominent issue for distribution networks. To develop
this relationship, the worst-case scenario of the distribution network is considered
and based on the formulation, some effective solutions have been recommended.
Finally, a partial feedback linearizing controller is designed for a distributed static
compensator (DSTATCOM) to maintain the voltage stability through reactive power
compensation
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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