1,720,963 research outputs found
SISTEMA DI PROPULSIONE PER VELIVOLO E METODO DI CONTROLLO DEL SISTEMA DI PROPULSIONE PER VELIVOLO
Full text linkBrevetto per invenzione industriale intitolato "Sistema di propulsione per velivolo e metodo di controllo di sistema di propulsione per velivolo". Titolari: Politecnico di Torino, Torino; Alenia Aermacchi S.P.A., Venegono Superiore (VA). Inventori: Ronchetto Davide, Chiesa Sergio, Ragusa Carlo Stefano, Armando Eric Giacomo, Farfaglia Salvatore
Design methodologies and prototyping of a starter-geenrator for an unmanned aerial vehicle (UAV) for civil applications
No full textDuring the recent years the development and use of uninhabited aircraft, in the form of UAVs (Unmanned Aerial Vehicle) has progressed quickly. An uninhabited aircraft is defined as the general term for UAV (Uninhabited Aerial Vehicle, Unmanned Aerial Vehicle), ROA (Remotely Operated Aircraft), and RPV (Remotely Piloted Vehicle), [1]. UAVs are to be understood as uninhabited and reusable motorized aerial vehicles [2], which are remotely controlled, semi-autonomous, autonomous, or have a combination of these capabilities, and that can carry various types of payloads, making them capable of performing specific tasks within the earth's atmosphere, or beyond, for a duration that is related to their missions. A cruise missile or an intelligent bomb can't be considered an UAV, as, according to the above definition, it must be reusable. Despite its huge potential in several applications, the utilization of such a technology was mainly reserved, in the past years, to the military field [3]. Nowadays, because of their remarkable potential, they're becoming more and more attractive also for some civil applicatio
New investigations in magnetic refrigeration device, AMR cycle and refrigerant bed performance evaluation
No full textSymmetric Short-Circuit Model of Synchronous Machines based on Flux and Loss Maps
No full textThe peak current during a short-circuit is a crucial performance index for Permanent Magnet Synchronous Motors (PMSMs). This indicator is even more critical for propulsion applications since the Active Short-Circuit (ASC) is one of the most common reaction strategies triggered when a system failure is detected, both for terrestrial and aerospace systems. Because of the non-linear behaviors of high-performance PMSMs and the trend towards rare-earth free Permanent Magnets (PMs) for traction applications, the peak current during ASC must be accurately evaluated, avoiding excessive oversizing but still guaranteeing the health of the PMs after the fault. In this paper, a fast and accurate model to compute the instantaneous current and torque during ASC is presented. The proposal relies on flux and loss maps, directly accounting for saturation and cross-saturation phenomena and also the iron and AC loss, typically neglected in the existing models. The proposed methodology is exploited to assess the performance of a double three-phase PMSM designed for aerospace applications. The two AC loss components, namely iron loss and loss related to skin and proximity effect in the winding, are considered and the effect of each of them is highlighted. Then, the proposed maps elaboration is compared with the dynamic model in Simulink/SimScape and against dedicated Finite Element Analysis (FEA) simulations
Hybrid sensorless control of Axial Flux Permanent Magnet motor drives, including zero speed
No full textHybrid sensorless control of axial flux permanent magnet motor drives, including zero speed
Full text linkSensorless control of an axial flux permanent magnet motor drive is proposed and tested. The motor is not purposely designed for sensorless control and shows a very small inherent saliency. This significantly affects the saliency-based position estimation in the low speed region. Other non-idealities, such as the non-sinusoidal back-EMF waveforms and possible misalignment between stator and rotor make the control more challenging. A robust sensorless control scheme is proposed, able to deal with these non-idealities with a rather simple implementation. The position estimation is based on a closed loop hybrid observer of the permanent magnet flux linkage. Experimental results report torque and speed sensorless control
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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