1,721,177 research outputs found
Smart fault-tolerant air-data sensor for aircraft flow angles measurement
Full text linkThis paper deals with the development of a smart multi-hole probe for aircraft air data sensing. The system aims at the calculation of static and total pressures, the angle-of-attack and the angle-of-sideslip starting from the elaboration of the pressure measurements on holes. The probe is characterized by fault-tolerant capabilities with respect to the loss of pressure data, and it is developed as an embedded system including MEMS sensors and a control electronics for multiple reconstructions of flow measurements. The basic idea for the reconstruction algorithm is that, for typical aircraft envelopes, flow angles are small (<15° for both attack and sideslip), and the shape of the pressure field around the stagnation point of a hemispherical body is essentially independent from the flow angles. Thus, once characterised the flow at the aircraft installation for zero angles of attack and sideslip, the reconstruction can be performed by minimising the errors between the five pressure measurements on the probe tip and the predictions of a set of models imposing different locations of the stagnation point. The geometry f the probe is designed and validated by CFD simulations, with the basic objective of enabling the algorithm to reconstruct the flow angles even in case of a pressure data loss. The work describes the initial phases of the system development, from the conceptual phase, up to the manufacturing of a first prototype used for the wind tunnel tests
L’anemia nelle infezioni
No full textL'anemia è usualmente osservata nelle infezioni gravi, croniche, infiammatorie e neoplastiche. E' evidenziato il ruolo delle citochine nella patogenesi dell'anemia nelle malattie corniche
Multi-variable aircraft directional control with anti-skid differential brakes
Full text linkThe paper deals with the design of a fault-tolerant control system of the runway dynamics for small jet aircrafts, in which hydraulic differential brakes are used as a stand-by directional command, to be activated in case of electro-mechanical nose-wheel steering failure. The directional control system is composed of four nested feedback loops, respectively acting on the brake pressures, the wheels’ slip ratio, the aircraft heading and the ground path. The study, performed by integrating detailed models of hydraulic brakes and electro-mechanical nosewheel steering in a light jet aircraft simulator, aims at demonstrating that, in case of nose-wheel steering jamming, the redundant control architecture is capable to assure safe and satisfactory operations, but only if the differential brakes are activated with minimum fault detection latency. Simulation results allow highlighting and characterizing, at different runway conditions, the effects of jamming detection latency on the directional stability when the aircraft crosses severe lateral gusts
Fault-tolerant control system of the directional runway dynamics of small aircrafts with hydraulic differential brakes
No full textThe paper deals with the design of a fault-tolerant control
system of the runway dynamics for small jet aircrafts, in
which hydraulic differential brakes are used as a stand-by
directional command, to be activated in case of electromechanical
nose-wheel steering failure. The directional
control system is composed of four nested feedback loops,
respectively acting on the brake pressures, the wheels’ slip
ratio, the aircraft heading and the ground path. The study,
performed by integrating detailed models of hydraulic brakes
and electro-mechanical nose-wheel steering in a light jet
aircraft simulator, aims at demonstrating that, in case of
nose-wheel steering jamming, the redundant control
architecture is capable to assure safe and satisfactory
operations, but only if the differential brakes are activated
with minimum fault detection latency. Simulation results
allow highlighting and characterizing, at different runway
conditions, the effects of jamming detection latency on the
directional stability when the aircraft crosses severe lateral
gust
Fattori influenzanti il livello sierico di ferritina nei thalassemici major politrasfusi
No full text
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
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