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A comparison on static and fatigue behaviour between traditional and SLM AISI 316L
Danilo D’Andrea,Andrea Gatto,Eugenio Guglielmino,Giacomo Risitano,Dario Santonocito 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3
Additive manufacturing (AM) is a novel production process, that allows the creation of lightweight and customizable devices. Such capacity requires a high grade of reliability under the action of service loads, especially under fatigue loads. One of the high-performance steels adopted for selective laser melting (SLM) is the AISI 316L. However, SLM is severally affected by laser beam power and scanning velocity. Mechanical properties must be investigated to provide reliability of final products, but this requires a huge amount of time. On the other hand, energy methods, such as the Risitano’s thermographic method and the novel static thermographic method, by performing stepwise fatigue tests and static tensile tests, can assess the material’s performance by monitoring the energy release. In this work, failure analysis has been performed, showing the differences between the traditional and AM manufacturing process, giving an insight to understand and improve the quality of the AM production process.
Automated brainstem segmentation detects differential involvement in atypical parkinsonian syndromes
Martina Bocchetta,Juan Eugenio Iglesias,Viorica Chelban,Edwin Jabbari,Ruth Lamb,Lucy L. Russell,Caroline V. Greaves,Mollie Neason,David M. Cash,David L. Thomas,Jason D. Warren,John Woodside,Henry Houl 대한파킨슨병및이상운동질환학회 2020 Journal Of Movement Disorders Vol.13 No.1
Brainstem segmentation has been useful in identifying potential imaging biomarkers for diagnosis and progression in atypical parkinsonian syndromes (APS). However, the majority of work has been performed using manual segmentation, which is time consuming for large cohorts.
The SAMI Galaxy Survey: Mass as the Driver of the Kinematic Morphology-Density Relation in Clusters
Brough, Sarah,van de Sande, Jesse,Owers, Matt S.,d’Eugenio, Francesco,Sharp, Rob,Cortese, Luca,Scott, Nicholas,Croom, Scott M.,Bassett, Rob,Bekki, Kenji,Bland-Hawthorn, Joss,Bryant, Julia J.,Davies, R American Astronomical Society 2017 The Astrophysical journal Vol.844 No.1
<P>We examine the kinematic morphology of early-type galaxies (ETGs) in eight galaxy clusters in the Sydney-AAO Multi-object Integral-field spectrograph Galaxy Survey. The clusters cover a mass range of 14.2 < log(M-200/M-circle dot) < 15.2 and we measure spatially resolved stellar kinematics for 315 member galaxies with stellar masses 10.0 < log(M-*/M-circle dot) <= 11.7 within 1 R-200 of the cluster centers. We calculate the spin parameter, lambda(R), and use this to classify the kinematic morphology of the galaxies as fast or slow rotators (SRs). The total fraction of SRs in the ETG population is F-SR = 0.14 +/- 0.02 and does not depend on host cluster mass. Across the eight clusters, the fraction of SRs increases with increasing local overdensity. We also find that the slow-rotator fraction increases at small clustercentric radii (R-cl < 0.3 R-200), and note that there is also an increase in the slow-rotator fraction at R-cl similar to 0.6 R-200. The SRs at these larger radii reside in the cluster substructure. We find that the strongest increase in the slow-rotator fraction occurs with increasing stellar mass. After accounting for the strong correlation with stellar mass, we find no significant relationship between spin parameter and local overdensity in the cluster environment. We conclude that the primary driver for the kinematic morphology-density relationship in galaxy clusters is the changing distribution of galaxy stellar mass with the local environment. The presence of SRs in the substructure suggests that the cluster kinematic morphology-density relationship is a result of mass segregation of slow-rotating galaxies forming in groups that later merge with clusters and sink to the cluster center via dynamical friction.</P>
THE SAMI GALAXY SURVEY: REVISITING GALAXY CLASSIFICATION THROUGH HIGH-ORDER STELLAR KINEMATICS
Sande, Jesse van de,Bland-Hawthorn, Joss,Fogarty, Lisa M. R.,Cortese, Luca,d’Eugenio, Francesco,Croom, Scott M.,Scott, Nicholas,Allen, James T.,Brough, Sarah,Bryant, Julia J.,Cecil, Gerald,Colless, Ma American Astronomical Society 2017 The Astrophysical journal Vol.835 No.1
<P>Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h(3) (similar to skewness) and h(4) (similar to kurtosis) in galaxies to their cosmological assembly history. Here, we assess these results by measuring the stellar kinematics on a sample of 315 galaxies, without a morphological selection, using two-dimensional integral field data from the SAMI Galaxy Survey. Proxies for the spin parameter (lambda(Re)) and ellipticity (epsilon(e)) are used to separate fast and slow rotators; there exists a good correspondence to regular and non-regular rotators, respectively, as also seen in earlier studies. We confirm that regular rotators show a strong h(3) versus V/sigma s anti-correlation, whereas quasi-regular and non-regular rotators show a more vertical relation in h(3) and V/sigma. Motivated by recent cosmological simulations, we develop an alternative approach to kinematically classify galaxies from their individual h(3) versus V/sigma signatures. Within the SAMI Galaxy Survey, we identify five classes of high-order stellar kinematic signatures using Gaussian mixture models. Class 1 corresponds to slow rotators, whereas Classes 2-5 correspond to fast rotators. We find that galaxies with similar lambda(Re)-epsilon(e) -values can show distinctly different h(3)-V/sigma signatures. Class 5 objects are previously unidentified fast rotators that show a weak h(3) versus V/sigma anti-correlation. From simulations, these objects are predicted to be disk-less galaxies formed by gas-poor mergers. From morphological examination, however, there is evidence for large stellar disks. Instead, Class 5 objects are more likely disturbed galaxies, have counter-rotating bulges, or bars in edge-on galaxies. Finally, we interpret the strong anti-correlation in h(3) versus V/sigma as evidence for disks in most fast rotators, suggesting a dearth of gas-poor mergers among fast rotators.</P>
The SAMI Galaxy Survey: global stellar populations on the size–mass plane
Scott, Nicholas,Brough, S.,Croom, Scott M.,Davies, Roger L.,van de Sande, Jesse,Allen, J. T.,Bland-Hawthorn, Joss,Bryant, Julia J.,Cortese, Luca,D'Eugenio, Francesco,Federrath, Christoph,Ferreras, Ign Oxford University Press 2017 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.472 No.3
The SAMI Galaxy Survey: revising the fraction of slow rotators in IFS galaxy surveys
van de Sande, Jesse,Bland-Hawthorn, Joss,Brough, Sarah,Croom, Scott M.,Cortese, Luca,Foster, Caroline,Scott, Nicholas,Bryant, Julia J.,d'Eugenio, Francesco,Tonini, Chiara,Goodwin, Michael,Konstantopou Oxford University Press 2017 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.472 No.2
<P>The fraction of galaxies supported by internal rotation compared to galaxies stabilized by internal pressure provides a strong constraint on galaxy formation models. In integral field spectroscopy surveys, this fraction is biased because survey instruments typically only trace the inner parts of the most massive galaxies. We present aperture corrections for the two most widely used stellar kinematic quantities V/sigma and lambda(R) (spin parameter proxy). Our demonstration involves integral field data from the SAMI (Sydney-AAO Multi-object Integral-field spectrograph) Galaxy Survey and the ATLAS(3D) survey. We find a tight relation for both V/sigma and lambda(R) when measured in different apertures that can be used as a linear transformation as a function of radius, i.e. a first-order aperture correction. In degraded seeing, however, the aperture corrections are more significant as the steeper inner profile is more strongly affected by the point spread function than the outskirts. We find that V/sigma and lambda(R) radial growth curves are well approximated by second-order polynomials. By only fitting the inner profile (0.5R(e)), we successfully recover the profile out to one R-e if a constraint between the linear and quadratic parameter in the fit is applied. However, the aperture corrections for V/sigma and lambda(R) derived by extrapolating the profiles perform as well as applying a first-order correction. With our aperture-corrected lambda(R) measurements, we find that the fraction of slow rotating galaxies increases with stellar mass. For galaxies with log M-*/M-circle dot > 11, the fraction of slow rotators is 35.9 +/- 4.3 per cent, but is underestimated if galaxies without coverage beyond one R-e are not included in the sample (24.2 +/- 5.3 per cent). With measurements out to the largest aperture radius, the slow rotator fraction is similar as compared to using aperture-corrected values (38.3 +/- 4.4 per cent). Thus, aperture effects can significantly bias stellar kinematic integral field spectrograph studies, but this bias can now be removed with the method outlined here.</P>