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[Fred Hartman Award for John P. Lopez]
No full textThe Fred Hartman Award for Excellence in Sportswriting to John P. Lopez, of the Houston Chronicle to be presented at Austin, Texas on March, 22, 2993. This document is the award template that is to be printed on the plaque and be awarded to Lopez
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
Technologies and Algorithms for autonomous guidance on RPAS
No full textThe research project consists in the analysis, design and prototyping of systems for autonomous guidance of RPAS.
After a first analysis of the state of the art, available sensor technologies have been surveyed and a proper architecture of an embedded platform has been identified and designed, that aims to perform autonomous guidance of RPAS by using techniques of sense and avoid
Modelling, simulation and experimental validation of the behaviour of a piezoelectric cantilever beam in Energy Harvesting and non-destructive diagnostic fields
Get PDFL'inquinamento ambientale è, al giorno d'oggi, uno dei più grandi problemi mondiali da risolvere ed è strettamente collegato ad altre importanti problematiche, quali, ad esempio, l'aumento del numero di pazienti affetti da malattie ad esso correlate. Malgrado ciò, la percentuale di impiego di fonti di energia notoriamente inquinanti è ancora molto elevata rispetto alla percentuale riservata alle energie 'pulite' e rinnovabili, il che ha indotto i ricercatori a condurre numerosi studi sulle energie alternative. L'obiettivo di questi studi si concilia bene con la filosofia di una scienza che studia la conversione dell'energia sprecata nell'ambiente in forme di energia diverse e più utili: questa scienza si chiama Energy Harvesting (EH). E' possibile recuperare energia da fonti ambientali naturali quali il sole, il vento e le vibrazioni naturali. L'energia prodotta da alcune di queste fonti alternative può essere convertita in energia elettrica attraverso processi non inquinanti che utilizzano opportuni dispositivi, chiamati energy harvester; essi funzionano da veri e propri generatori quando sono sottoposti all'effetto delle vibrazioni.
Il processo di conversione dell'energia ambientale in energia elettrica comporta spesso l'utilizzo di smart materials quali, ad esempio, i materiali piezoelettrici. Questi materiali hanno la proprietà di sviluppare cariche elettriche nel momento in cui sono sottoposti a sollecitazioni meccaniche (effetto piezoelettrico diretto): le cariche prodotte possono essere immagazzinate e conservate utilizzando un circuito elettrico. Una vasta gamma di dispositivi realizzati con materiali piezoelettrici è stata sviluppata nel campo dell'EH. In particolare, stanno suscitando notevole interesse i trasduttori piezoelettrici sollecitati da vibrazioni naturali, come quelle indotte dalla pioggia o dal vento.
La presente tesi ha lo scopo di fornire un contributo alla produzione di energia pulita ed 'economica', utilizzando piccoli dispositivi piezoelettrici: sollecitando gli harvester piezoelettrici con opportune vibrazioni naturali è possibile alimentare dispositivi a bassa potenza.
L'obiettivo principale della tesi è quello di capire come possa reagire un cantilever beam piezoelettrico sotto l'effetto di opportune vibrazioni, quali, ad esempio, quelle indotte dal passaggio di un fluido (aria o acqua), o da un movimento meccanico quale quello provocato dal passaggio di un vagone ferroviario sulle rotaie. L'analisi vibrazionale è stata effettuata utilizzando sia un opportuno apparato sperimentale che un ambiente di simulazione, al fine di validare le simulazioni con i dati sperimentali. Tale validazione conferisce affidabilità al processo di simulazione che può quindi essere esteso per analizzare situazioni non facilmente riproducibili in laboratorio. Inoltre, l'ambiente di simulazione offre la possibilità di ottimizzare i vari elementi costitutivi (forme, spessori e materiali costituenti) dei cantilever beam, permettendo così la progettazione di un cantilever beam piezoelettrico 'ottimale', specifico per la situazione considerata. Il potenziale elettrico sviluppato da tali dispositivi può essere conservato e riutilizzato, secondo i principi dell'EH. Inoltre, i dispositivi così progettati possono essere utilizzati anche come sensori nel campo della diagnostica non distruttiva.
La modellizzazione, la simulazione, l'ottimizzazione e la validazione sperimentale del comportamento dei cantilever beam piezoelettrici sono state realizzate in svariati casi di studio, la cui descrizione propone il dispositivo utilizzato in situazioni diverse, aventi un crescente grado di difficoltà. Per ogni caso di studio è stata descritto un adeguato modello matematico. Sono state fornite anche opportune informazioni in merito alla struttura delle matrici costitutive di ogni materiale piezoelettrico considerato.
Tutte le simulazioni presentate nella tesi sono stati realizzate utilizzando COMSOL Multiphysics, un software che utilizza il metodo agli elementi finiti (FEM) per risolvere modelli matematici. Il FEM è uno dei metodi numerici più utilizzati per calcolare soluzioni approssimate di problemi descritti matematicamente da equazioni alle derivate parziali (PDE). E' spesso utilizzato per ‘semplificare’ problemi reali che coinvolgono interazioni di non semplici fenomeni fisici, realizzate utilizzando oggetti aventi geometrie e condizioni al contorno di non semplice analisi.
La presente tesi si conclude con lo studio di fattibilità di un'applicazione reale, in cui un sistema autoalimentato, basato su un dispositivo piezoelettrico, può continuamente monitorare lo stato di salute della boccola di una carrozza ferroviaria, e quindi contribuire alla sicurezza dei passeggeri ferroviari.Environmental pollution is one of the biggest world problems nowadays and is closely connected to other important problems. The percentage of employment of polluting sources of energy is still high compared with that referred to clean ones. In recent years, several studies into alternative energies have been developed. The aim of renewable energies fits well with the philosophy of a science that studies the conversion of energy wasted in the environment into different and more useful forms: this science is called Energy Harvesting (EH). It is possible to harvest energy capturing it from environmental sources such as solar, thermal, wind-kinetic energy and natural vibrations. The energy produced by some of these alternative sources of energy, such as wind and vibrational energy, is converted into electrical energy through non-polluting processes and are used directly by energy harvesters devices that work as generators under the effect of vibrations.
The conversion process of environmental energy into electrical power often involves smart materials such as piezoelectric materials, which develop electrical charge when subject to mechanical stress (direct piezoelectric effect): this charge can be stored by means of an electrical circuit. A wide range of devices made of piezoelectric materials has been developed in the EH field, for various large and small-scale applications. Great interest has been directed to piezoelectric transducers stressed by natural vibrations, such as those induced by rain or wind.
This dissertation is aimed at contributing to the production of clean and inexpensive energy, using small piezoelectric devices stressed by natural vibrations and useful to provide energy to low-power devices.
The objective is to understand how a piezoelectric cantilever beam reacts under the effect of vibrations that could be induced by a flowing fluid, such as air or water, or by mechanical movement, such as that of a train on the rails. The vibrational analysis was carried out both using experimental apparatus and in a simulation environment, in order to validate the simulations with experimental data. This validation lends reliability to the simulation process that can be extended to analyse situations not easily testable in the laboratory. Furthermore, the simulation environment offers the opportunity of looking for the optimization of several constitutive elements of cantilever beams, such as their shapes, thicknesses and materials they are made of, so allowing the design of an ‘optimal’ cantilever beam, specific for the situation considered. The electrical potential developed by such devices can be stored and reused following the principles of EH. Moreover, these so designed devices can be used as sensors in the field of Non-destructive testing.
The modelling, simulation, optimization and experimental validation of the behaviour of the piezoelectric cantilever beam are carried out with some different case studies, describing the harvester device in situations with an increasing degree of difficulty. An appropriate mathematical model was described for each case study. Useful information is provided about the structure of the constitutive matrices of each piezoelectric material considered.
All the simulations presented in the dissertation were realised using Comsol Multiphysics, software that uses the Finite Element Method (FEM) to solve mathematical models. The FEM is one of the most popular numerical methods used to calculate approximated solutions for problems described mathematically by Partial Differential Equations (PDEs). It is often used to ‘simplify’ real-world problems that involve complicated physics, geometry and boundary conditions.
Finally, this dissertation presents a feasibility study for a real application, in which a self-powered system based on a piezoelectric device can constantly monitor the state of health of the axle-box of a railway carriage and hence contribute to the safety of rail passengers
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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