1,720,986 research outputs found
Giovannibriglia/Bearing-fault-detection-and-recognition-from-supply-currents-with-decision-trees: Zenodo
No full textThis is the repository of the paper titled "Bearing fault detection and recognition from supply currents with decision trees"; authors: Giovanni Briglia, Fabio Immovilli, Marco Cocconcelli and Marco Lippi
Arc Linear Motors for Direct Drive Robots: Galileo Sphere
No full textThis paper presents the design of an arc linear motor for a new type of robot, named Galileo Sphere, based on direct drive technology for pick and place operations. Pick and place robots require high dynamics and position accuracy and repeatability. A classical implementation is based on rotating electric machines with reduction gearboxes and kinematic mechanisms that convert the rotating motion to linear where necessary.The direct drive technology reduce mechanical losses, backlash, MTBF and a number of components. This technology also achieves higher dynamic and accuracy.The robot has a polar-like configuration with 5 degree of freedom.A dynamical simulator was used to assess motors, that satisfies a typical pick and place trajectory with the different payload. The proposed solution resulted feasible, even at high working frequencies and with payloads up to 4 kg. The precisionand repeatability remained high, within 100 micron.The working is a spherical sector with 1870 mm maximum diameter, and 450mm vertical reach
A test bench for accelerated thermal ageing of III–V concentration solar cells using forward bias injection
No full textPower production from solar photovoltaic systems is constantly increasing. In the last few years concentration photovoltaic (CPV) system using III-V multijunction cells appeared on the market, promising doubled efficiencies compared to traditional silicon PV solar panels. For CPV systems to be competitive on the market, they must be reliable to assure long-term operation. This paper presents the design and construction of a test bench for thermal cycling characterization of dense array receivers employing III-V multijunction cells mounted on a microchannel heat sink. Instead of a climatic chamber, the proposed test bench employs forward bias injection (FBI) to heat the cells, in order to better mimic on-field operating conditions. The experimental results of the accelerated ageing test are coherent with preliminary on-field trials, with a good agreement on the fault mechanism
Test Setup for Multistress Characterization of Insulation Degradation Mechanisms in Electric Drives
No full textIn this paper a special test setup able to assess lifespan models of electrical motor insulation system under various stress conditions is proposed. The test bed will allow characterizing insulation degradation mechanisms under variable ambient and power supply parameters, from simple models, such as twisted pairs, up to coil form and complete machine operated at rated load
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
Currents and Vibrations in Asynchronous Motor with Externally Induced Vibration
No full textThis paper presents an experimental investigation ofthe airgap variation model for vibration and current harmonicsrelationship in induction motors. To this aim, an external vibrationsource was employed, together with ball bearing alterationsin order to decrease stiffness. The direction of the externalvibration is radial with respect to the axis of the electricmachine under test. To maximize the effect of externally inducedvibrations, the frequency chosen was near the flexural resonanceof the rotor, determined by FEM analysis.During tests both currents and vibration of the machine wereacquired. The test rig allowed to vary speed, vibration level andbearing stiffness. An electromagnetic brake provided a variableoutput load for the electric machine. The focus of the paper isthe review of fault models used in literature. Radial effects areusually visible only in case of large failures that result in air-gapvariations, as the experiments confirme
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
Review of Design Solutions for Internal Permanent Magnet Machines Cogging Torque Reduction
No full textInternal permanent magnet synchronous machinesare spreading in industrial production.They feature high torque density and extended speed rangethat are key issues in many fields of applications, however theircogging torque is typically quite high.Many methods and design guidelines for cogging torquereduction exist in literature and this paper compares them. Forthis purpose, the different design guidelines are applied to acommon reference machine in order to assess their effectiveness.Computer Finite Element Analysis (FEA) are carried out for eachcase in order to compare the cogging torque reduction capabilityof the different techniques. The side effects of these techniques,such as back-emf and rated torque profile distortions, willbe taken into account. The paper contribution is to comparethe various cogging torque reduction techniques and magneticgeometries on a common reference machine to identify the mosteffective ones
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