1,720,953 research outputs found
Nonlinear tuning of microresonators for dynamic range enhancement
No full textThis paper investigates the development of a novel framework and its implementation for the nonlinear
tuning of nano/microresonators. Using geometrically exact mechanical formulations, a nonlinear model is
obtained that governs the transverse and longitudinal dynamics of multilayer microbeams, and also takes
into account rotary inertia effects. The partial differential equations of motion are discretized,
according to the Galerkin method, after being reformulated into a mixed form. A zeroth-order shift
as well as a hardening effect are observed in the frequency response of the beam. These results are
confirmed by a higher order perturbation analysis using the method of multiple scales. An inverse
problem is then proposed for the continuation of the critical amplitude at which the transition
to nonlinear response characteristics occurs. Path following techniques are employed to explore the
dependence on the system parameters, as well as on the geometry of bilayer microbeams, of the magnitude
of the dynamic range in nano/microresonators
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
On the application of numerical continuation to large-scale dynamical systems
Full text linkThe system approach in dealing with large groups of components with nonlinear interactions has received constantly growing attention in recent years in wide variety of applications from system biology to the size evolution of aerosol particles. These systems exhibit complex behaviors that are not predictable unless the entire system as well as their interactions are taken into account. The complexity of these high-dimensional problems is exacerbated when parameter space of interest is also sizable. The focus of this dissertation is addressing several physical and engineering problems within the context of large-scale dynamical systems through the development as well as implementation of novel computational algorithms based on numerical path-following techniques. For all systems investigated in this study, a suitable boundary value problem is formulated and the numerical continuation method is used for covering the parameter space using the software-package coco.
In this dissertation, we first briefly consider the reachability problem in power system networks in which the uncertainties in the loads require robust design of system parameters to ensure safe operation of the network under undesired perturbation in the system. This analysis is based on an existing matlab-code which utilizes a so-called numerical shooting method for the parametric analysis of power systems. A wrapper is developed to make the custom-designed systems in this code compatible with the asynchronous collocation toolbox in coco.
The asynchronous collocation toolbox developed in this dissertation extends the capability of common implementation of collocation methods for differential equations by reducing the number of mesh points required specifically for problems with slow-fast dynamics. This class of dynamical systems appears in many large-scale physical systems in which changes of states are governed by different time scales.
The transient growth of aerosol particles in a humid environment is then investigated in order to explore the effect of some system parameters, such as the initial size distribution and the rate of temperature decay, on the formation of cloud droplets. For a fixed fraction of droplet forming particles in a rising parcel, a suitably formulated boundary value problem is used along with numerical continuation to obtain the solutions in the parameter space of interest. Results obtained from the proposed numerical scheme are compared with the estimated fractions from available criteria in the literature to show the estimation error due to a phenomenon known as kinetic limitation.
In the second part of this dissertation, our objective is to identify and, where possible, resolve singularities that may arise in the discretization of spatiotemporal boundary-value problems governing the steady-state behavior of nonlinear beam structures. Of particular interest is the formulation of nondegenerate continuation problems of a geometrically-nonlinear model of a slender beam, subject to a uniform harmonic excitation, that may be analyzed numerically in order to explore the parameter-dependence of the excitation response. Several methods for breaking both the spatial and temporal equivariance are proposed. We then use these findings to suitably discretize the mixed formulation of the governing equations of a beam in the longitudinal and transverse directions where inertia effects are taken into account. The numerical results corresponding to the free vibrations are compared to a perturbation analysis obtained using the multiple-scales method to show the validity of the numerical scheme. The developed numerical technique is then employed to investigate the geometry as well as parameter dependence of the range of the linear regime in the beam's forced response.
Finally, the convergence associated with the collocation scheme is investigated in order to rigorously analyze the capabilities of this method. The dissertation ends with a discussion of further development of asynchronous discretization scheme as well as several physical questions to be addressed.Item withdrawn by Laura Spradlin ([email protected]) on 2014-09-04T13:11:34Z
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University of Illinois Theses & Dissertations (ID: 1)
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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
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