1,720,981 research outputs found
Method of Construction of Specialized Algorithms for Solving Differential Equations
Get PDFConsidered the problem of optimization of the process of constructing specialized algorithms for the given form nonlinear ordinary differential equations systems’ numerical solution. The problem is reduced to the determination and use of approximating representations of the numerical integration errors by the chosen basic metho
On Using GSSM in Power Systems Dynamics' Simulation
Get PDFA broad spectrum of aspects related to the feasibility, principles, and implementation of the generalized state-space model (GSSM) as a mathematical modeling technique for energy systems simulation has been considered. This paper reviews the use of GSSM to address the challenges of adequate modeling of dynamics of modern power systems’ dynamics, which are characterized by their hybrid nature, complex switching modes, and nonlinear interactions. The versatility of GSSM is analyzed in comparison to traditional approaches, particularly its capability to integrate continuous and discrete system dynamics into a unified advanced framework. Additionally, the model's ability to capture both linear and nonlinear regimes, its compatibility with contemporary computational tools, and its application across various power systems are discussed in detail. The fundamentals, analytical and numerical considerations of differential-algebraic equations (DAEs) are also examined. The effectiveness of GSSM is demonstrated through a case study involving simulation of a power supply control device dynamics. Computer modeling experiments highlight the advantages of GSSM over traditional methods in terms of accuracy, computational efficiency, and scalability. At the same time, they identify areas where further advancements and improvements are necessary.On Using GSSM in Power Systems Dynamics' SimulationpublishedVersio
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
On the Choice of Numerical Methods for Solving Dynamic Equations for Control Systems with Embedded Calculating Tools
Get PDFApproaches to choice of optimum method as for accuracy and amount of computation at the integration step that makes it possible to range numerical implementation methods for different levels of acceptable error based on evaluation of optimality criterion. Key words: choice of numerical method, solving dynamic equations, algorithms for embedded calculating tools.publishedVersion© A. Verlan, V. Fedorchuk, 201
Specifics of the autonomous energy power unit dynamic processes’ modeling
No full textSignificant features of modern autonomous power units, along with increasing complexity of structures and modes and increasing requirements for quality of operation, are the heterogeneity of their composition, the presence of links with distributed parameters, changing parameters during operation, the presence of computer components control, monitoring and diagnostics. A characteristic feature of controlled autonomous power units is the diversity of elements that are part of them. This, in turn, usually creates inhomogeneity in the mathematical description of the system. Physical heterogeneity is caused by the presence of elements that are different in physical essence (mechanical, electrical, optical, magnetic and electromagnetic, etc.). Functional heterogeneity is manifested in the presence of different purpose signals (control, measuring, duplicating, aux-iliary, etc.). Thus, modern autonomous power units belong to the class of complex inhomogeneous dynamic systems.These features cause the emergence of new requirements for methods and tools for mathematical modeling of dynamic processes in autonomous power units, in particular the need to move from common in practice autonomous study of individual components, to a comprehensive study of the system as a whole using macro-models, model building according to experimental data, in-creasing the adequacy of mathematical models by rationally taking into account the distribution of parameters of the relevant links, the possibility of rapid changes in the composition of computer models, taking into account physical and functional heterogeneity.The article considers the methods of construction of mathematical models of dynamic processes in modern autonomous power units and in their control systems, diagnostics and testing on the basis of expansion of forms of mathematical descriptions with involvement of integral operators and Volterra equatio
DIGITAL CORRECTION FILTER IN PROBLEMS OF RECOVERY OF INPUT SIGNALS AND OBSERVING SYSTEMS’ DATA IN ENERGY OBJECTS
Get PDFThe task of signal recovery is one of the most important for auto-mated diagnostics and control systems of an energy object. When solving the inverse problems of recovering signals, images and other types of data, spectral distortions and losses occur (in some cases, very significant ones). They are primarily stipulated due to ill-posedness of these problems, which is the result of loss of information about the original signal due to strong (and even complete) suppression in the observed signal of a part of spectral components, which become indis-tinguishable against the background of errors and noise [1]. Besides, additional spectral distortions may occur in the process of solving recovery problems, which depend on specific methods used and their parameters. A method for building a digital correcting filter for processing the results of solving incorrect inverse problems is proposed, which effectively improves the quality of the solution. The method is based on the use of a singular decomposition of the matrix (SVD) of a system of algebraic equations that approximates the integral operatorpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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