1,720,956 research outputs found
Structural Design Evaluation of Integrated Rotor Hub and Shaft for a High-Speed Surface Mounted Radial Flux Permanent Magnet Synchronous Motor
No full textIncreasing the reliability and power density of a surface-mounted permanent magnet synchronous machine (SPMSM) is crucial due to the broader applications in the automotive and aerospace sectors. Concerns with such machines are that the overall rotating assembly experiences significant mechanical loads due to the rapid rotational speeds, making it exceptionally challenging to design the structural integrity of these components. This study's main objective is to offer a scientific justification for designing an integrated rotor hub and shaft through efficient Finite Element Modeling (FEM) and integration strategies to maximize the rotating assembly durability of a 150kW radial flux SPMSM spinning at 20,000 rpm. The optimization of integrated topology is evaluated based on a multiphysics platform, along with studies conducted on motor assembly eigen frequency. The integrated approach combining the shaft and rotor hub made of AISI 4340 solely saves 1.84kg, removing the necessity of standard components such as balancing end clamp plates, locknuts, and washers. Lower masses are proportional to lower centrifugal forces, reducing radial stress and promoting component/assembly stiffness
Rotor Durability Optimization by Means of Finite Element Multiphysics Analysis for High-Speed Surface Permanent Magnet Electric Machines
No full textTransport electrification is pushing the automotive and aerospace industries to enhance the power density of their powertrains further and further. One of the technologies currently pursued by some companies is high-speed electric motors. For instance, the new Model S Plaid motor by Tesla has a carbon-fiber wrapped IPM (Interior Permanent Magnet) rotor which can exceed 20,000rpm. The SPX88-120 made by Helix company shows a power density of about 18kW/kg at 50,000rpm. However, such high rotating speeds result is huge mechanical stresses in the entire rotating assembly, thus making the structural design of these parts extremely challenging. The primary goal of this paper is to provide a scientific rationale for the effective Finite Element Modeling (FEM) and integration strategies to maximize the rotating assembly durability of a 150kW radial flux SPMSM (surface-mounted permanent magnet synchronous motor) considered as a case-study. A non-linear simulation requires the input of a stress-strain curve and modified power law hardening study is conducted. The secondary goal of the paper is to analyze the thermal stress risers for multiphysics optimization of components. An analytical methodology to estimate the fatigue life for fully reverse cyclic loading is expressed. An extensive study on the eigen mode shape and frequency was performed to understand the dominant frequency of the system. A comparative performance study is conducted on shaft critical speeds, modal analysis, and stiffness interaction between components. Multiphysics optimization of topology is undertaken, the principal stresses in significant load-bearing components are reduced by 10 to 33%
Multiphysics Thermo-Structural Design of the Rotor in High-Speed Permanent Magnet Machines for Aerospace Propulsion Applications
No full textHigh temperatures, thermal and mechanical stresses, rotor imbalances in high-speed Surface Permanent Magnet Synchronous machines (SPMSM) often dictates the maximum power output of the machine. Hence, a trade-off should be made between the cooling design, and machine structure stiffness, and the power rating. This work discusses the modelling and design process of the high-speed machine rotor by means of thermo-structural and modal analyses to minimize the trade-offs between the structural and thermal designs. The study discusses the design and modeling of SPMSM machine rotor thermally and structurally to achieve the highest power output of the machine while targeting rotor weight reduction. The design of the rotor shows safe operating temperatures and stress levels at the machine rated speed and power output as a result of the minimized and well-distributed thermal and mechanical stresses. A power density of 7.1 kW/kg is achieved by designing the machine within safe operating limits without using excessive safety margins
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
