1,721,031 research outputs found
Analisi computazionale dell’aeroacustica di un pneumatico in rotolamento
Full text linkIl traffico stradale è una delle maggiori fonti di inquinamento acustico della società moderna. Conseguentemente, lo sviluppo dei nuovi veicoli è soggetta a direttive sempre più stringenti in termini di emissione rumorosa. Le maggiori sorgenti di rumore dei comuni veicoli stradali sono il rumore del motore, quello della trasmissione, il rumore aerodinamico e quello dell’interazione pneumatico-strada. Quest’ultimo diventa dominante tra i 50 e 100 km/h, velocità tipiche dei tratti urbani ed extra-urbani. Il rumore derivante dall’interazione pneumatico-strada è la combinazione di vibrazioni strutturali e fenomeni aeroacustici che generano e amplificano/riducono il suono emesso dal pneumatico. L’analisi numerica presentata in questa tesi ha lo scopo di investigare i meccanismi di generazione del rumore aeroacustico del pneumatico e allo stesso tempo fornire uno strumento di sviluppo di coperture a basso impatto acustico.
Il presente lavoro è diviso in due parti, l’analisi dell’aerodinamica stazionaria e l’analisi aeroacustica del pneumatico in rotolamento. Nella prima, lo studio della soluzione numerica delle Navier-Stokes mediate ha consentito di evidenziare i fenomeni aerodinamici, come separazioni o flussi a getto, che possono originare emissione acustica. Nella seconda parte tali aspetti sono stati analizzati con maggiore dettaglio per mezzo delle analogie aeroacustiche, definendo la reale capacità di predizione dello strumento numerico e fornendo suggerimenti per lo sviluppo di pneumatici più silenziosi.Road traffic is one of the major source of noise in modern society. Consequently, the development of new vehicles is subject to increasingly stringent guidelines in terms of noise emissions. The main noise sources of common road vehicles are the engine, the transmission, the aerodynamic and the tire-road interaction. The latter becomes dominant between 50 and 100 mph, speeds typical of urban and extra-urban roads. The noise that arises from tire-road is the combination of structural vibration and aeroacoustics phenomena that create and amplification/reduction of the sound emitted from the tire. The aim of the numerical analysis presented in this thesis is to investigate the aeroacoustic noise generation mechanisms of the tire and at the same time provide a tool to develop low noise tire.
The present work is divided into two parts, the analysis of the steady aerodynamics and the aeroacoustic of the rolling tire. In the first part, the study of the Navier-Stokes numerical solution made it possible to highlight the aerodynamic phenomena, such as separations or jet streams, which can cause noise. In the second part these aspects have been analyzed in greater detail by means of aeroacoustic analogies, defining the capacity of the numerical tool to provide suggestions for the development of quieter tires
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
Evaluation of a conventionally defined vulnerability of buildings based on surveyed damage data
No full textAutophagy in trimethyltin-induced neurodegeneration
Full text linkAutophagy is a degradative process playing an important role in removing misfolded or aggregated proteins, clearing damaged organelles, such as mitochondria and endoplasmic reticulum, as well as eliminating intracellular pathogens. The autophagic process is important for balancing sources of energy at critical developmental stages and in response to nutrient stress. Recently, autophagy has been involved in the pathophysiology of neurodegenerative diseases although its beneficial (pro-survival) or detrimental (pro-death) role remains controversial. In the present review, we discuss the role of autophagy following intoxication with trimethyltin (TMT), an organotin compound that induces severe hippocampal neurodegeneration associated with astrocyte and microglia activation. TMT is considered a useful tool to study the molecular mechanisms occurring in human neurodegenerative diseases such as Alzheimer’s disease and temporal lobe epilepsy. This is also relevant in the field of environmental safety, since organotin compounds are used as heat stabilizers in polyvinyl chloride polymers, industrial and agricultural biocides, and as industrial chemical catalysts
Role of the protease-activated receptor 1 in regulating the function of glial cells within central and peripheral nervous system
Full text linkProtease-activated receptor 1 (PAR1) is a cell surface receptor, which belongs to a family of G protein-coupled receptors and signals in response to multiple extracellular proteases. PAR1 is widely distributed in mammalian cells and tissues, including human glial cells. Within this context, PAR1 may participate to various activities promoted by glial cells. In fact, glia does not represent merely a glue in the nervous system but affects significantly various neuronal functions and activities being also significantly involved in the pathophysiology of various nervous system disorders. In this review, we summarize the current understanding of PAR1 expression and functions within glial cells both in the central and peripheral nervous system
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
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