1,721,021 research outputs found
A Meta-Heuristic Optimization Procedure for the Identification of the Nonlinear Model Parameters of Hydraulic Dampers Based on Experimental Dataset of Real Working Conditions
Full text linkHydralic dampers are widely implemented in railway vehicle suspension stages, especially in high-speed passenger trains. They are designed to be mounted in different positions to improve comfort, stability, and safety performances. Numerical simulations are often used to assist the design and optimization of these components. Unfortunately, hydraulic dampers are highly nonlinear due to the complex fluid dynamic phenomena taking place inside the chambers and through the by-pass orifices. This requires accurate damper models to be developed to estimate the influence of the nonlinearities of such components during the dynamic performances of the whole vehicle. This work aims at presenting a new parametric damper model based on a nonlinear lumped element approach. Moreover, a new model tuning procedure will be introduced. Differently from the typical sinusoidal characterization cycles, this routine is based on experimental tests of real working conditions. The set of optimal model parameters will be found through a metaheuristic iterative approach able to minimize the differences between numerical and experimental damper forces. The performances of the optimal model will be compared with the ones of the most common Maxwell model generally implemented in railway multibody software programs
Innovative passive yaw damper to increase the stability and curve-taking performance of high-speed railway vehicles
Full text linkYaw dampers are implemented on high-speed trains to reduce their tendency towards unstable movement (hunting) while running at high-speed. Although they have a positive influence on the vehicle's stability, these devices impose a steering resistance action on the bogies while negotiating tight curves at low speed, and so standard passive devices must be designed taking conflicting objective functions into account. This paper presents an innovative yaw damper able to overcome this trade-off by introducing a passive solution able to modify this component's working behaviour during different vehicle operating conditions. To quantify the efficacy of this solution, numerical models of innovative and standard dampers were developed and validated by means of experimental tests. Then, they were co-simulated with a multibody model of a real test case vehicle running under different operating conditions
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
L'assorbimento della vit. B12 (test di Schilling) in pazienti con M. di Crohn resecati e non, sotto terapia medica (prednisolone e/o salazopirina) di mantenimento (TMM)
No full textLyme disease seroprevalence in a region of central Italy.
No full textThe present study reports the seroprevalence of IgG antibodies to B. burgdorferi by testing sera from volunteer blood donors in Latium, a region of Central Italy. All samples were tested by ELISA and the positive samples were assayed by Western blotting as a confirmatory test. A positivity rate of 4.3% was recorded by ELISA, while after the confirmatory test by Western blotting the positivity rate decreased to 1.5%. The presence of significant antibody titers to B. burgdorferi in the sera of healthy subjects shows that further investigations are necessary to clarify the real prevalence of Lyme disease in our region
Osservazione di un caso di Lupus Eritematoso Sistemico iperacuto trattato con terapia immunosoppressiva e plasma exchange. Riv. Emoter. Immunoemat, 34:95, 1987.
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