1,720,955 research outputs found
Efficient Computational Approaches and Their Convergence Analysis for Integro-differential Equations with Small Parameters and Fractional Derivatives
No full textIntegro-differential equations (IDEs) combining both differential and integral terms emerge in diverse fields of science and engineering, for conceptualizing systems that depend on past values of the function. For instance in physics, IDEs depict the conduct of materials possessing memory, like viscoelastic substances. In the field of ecology, these equations find utility in depicting population dynamics, wherein the integral component captures the impact of previous populations on the present state. In the domain of finance, they find application in modeling option valuation and risk management, accounting for the historical trajectory of underlying assets. So, IDEs can be used to model economic systems where past decisions or events can influence the current behavior and this feature of IDEs attracted many researchers to attain insights into a broad array of complex phenomena spanning diverse scientific domains. It is really intricate to find the analytical solutions of the IDEs. So, several ideas are proposed in literature basically consisting of the numerical as well as semi-analytical approaches which are used for finding the solutions to the IDEs. Some of the techniques involves the Adomian decomposition method, homotopy perturbation method, variational iteration method, reproducing kernel method, which are meshfree in nature. Also, there are many numerical techniques such as the finite difference method, finite element method, spectral/collocation method, that are employed to approximate the solution of IDEs. As already mentioned, finding the solutions to IDEs are complicated, but it is even more difficult to obtain the solutions of singular IDEs, where the solution has singularities at some point of the domain. These type of situations often cannot be dealt with the conventional numerical methods, so specially tailored methods are used to deal with such model problems. Researchers have gained insights in solving the regular IDEs but very less contributions are made for analyzing the IDEs with singularities. This thesis intends to develop the higher order numerical methods and semi-analytical methods for finding the solutions of IDEs involving small parameters and fractional derivatives. Also, the convergence analysis/error estimates of all the proposed schemes for various kinds of model problems are broadly discussed. Some numerical simulations are carried out so as to give a pictorial description of how the solution behaves and thereby drawing a validation to the theoretical prospects. Since, we have dealt with two types of IDEs, this thesis is partitioned in two categories, wherein the first five chapters are devoted to find the numerical solutions of singularly perturbed IDEs where the solution undergoes vital changes as the parameter approaches zero. The next three chapters are dedicated to find the approximate/numerical solutions of fractional order IDEs. This dissertation is comprised of a total of ten chapters, of which Chapter 1 deals with the basic ideas of the singularly perturbed differential equations and fractional calculus, inclusive of the important definitions, properties, and the motive of working out various model equations of IDEs. Chapter 2 describes the numerical schemes and their convergence analysis for studying a singularly perturbed Volterra integro differential equation (SPVIDE) using the conventional upwind scheme with the trapezoidal rule for the integral term. The accuracy is further improved by using a post-processing scheme which is validated with a few examples and comparison results. The idea used for the first order SPVIDE is further extended to a second order SPVIDE wherein the kernel is taken to be of the nonlinear type and a hybrid scheme is used for obtaining direct second order convergence. The numerical approach used in Chapter 1 is extended to solve IVP and BVP cases of the singularly perturbed Fredholm integro differential equation (SPFIDE) and singularly perturbed Volterra-Fredholm integro differential equation (SPV-FIDE) in Chapter 3 and Chapter 4 respectively. The system of SPVIDEs is considered in Chapter 5, where the problem is solved using a first order convergent scheme. The numerical approximation is done using the backward Euler method for the differential operator and rectangular rule for the integral operator and with a proper error analysis of the concerned scheme. Further, the scheme is subjected to post-processing technique, thereby giving better accuracy. In Chapter 6, the numerical solution of the singularly perturbed partial differential equation with a Volterra integral is proposed. Firstly, the problem is solved by forming a difference scheme that consists of the implicit-Euler method for the time derivative, an upwind scheme for the spatial derivative, and a left rectangular rule for the integral part that gives a first ordere-uniform convergence. The order of accuracy is then enhanced by successfully applying the Richardson extrapolation technique. Secondly, a direct second order convergent difference scheme is employed, comprising of the Crank-Nicolson scheme in the temporal direction, a hybrid scheme in the spatial direction, and a composite trapezoidal rule in the integral part. Finally, the performance of the numerical schemes is tested by a few examples. The next three chapters of the thesis study the model problems related to fractional IDEs. Chapter 7 focuses on different semi-analytical methods to solve a time fractional partial IDEs (PIDEs). The Adomian decomposition method, the homotopy perturbation method, and the modified homotopy perturbation method are applied to solve the model equation. A brief convergence analysis is carried out for all the proposed techniques and numerical experiments are done to show the efficiency of the suggested methods. In the next chapter, Chapter 8, investigates the fractional order Fredholm-Volterra IDE using both semi-analytical and numerical methods. The semi-analytical approximations are done using the Chebyshev and Bernstein polynomials in the ADM and the numerical scheme is developed using the L1 scheme for the fractional order derivative in combination with appropriate quadrature rules for the integral parts. Some comparisons with the existing results show that the proposed methods are highly productive and reliable. Chapter 9 aims to develop an efficient scheme for a fractional IDE involving a weakly singular kernel. The weakly singular Volterra integral is approached with the production integration rule, and the Caputo order derivative is approximated using the L1 scheme. First order accuracy of this method has been demonstrated. Additionally, the Richardson extrapolation strategy is effectively used to boost the accuracy. Finally, the model problem is also investigated using another scheme wherein, the integral part is discretized using the product trapezoidal rule and fractional derivative is discretized using the L1 scheme which gives better convergence rate in comparison to scheme I. Numerical tests are done to demonstrate the efficacy of the proposed methodologies. Finally, Chapter 10 presents the concluding statements derived from the diverse outcomes discussed in this thesis, along with a handful of potential future avenues for further exploration based on the current research
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
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
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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