476 research outputs found
Performance of a micro-engineered ultrasonic particle manipulator
No full textAn ultrasonic microfluidic particle manipulator has been modeled and its experimentally measured separation performance has been compared with the modeled results for 1 µm latex particles, and yeast particles in water
Dynamics of inertial disk particles in turbulent channel flow
No full textA suspension of oblate spheroidal (disk-like) particles in turbulent channel flow has been investigated with focus on the translational and rotational particle statistics. The effects of particle aspect ratio and inertia have been explored. The disk-like particles exhibited a significant preferential orientation in the plane of the mean shear. The influence of the particle shape on the orientation and rotation diminished as translational inertia increased from Stokes number 1 to 30. Isotropization of both orientation and rotation could be observed in the core region of the channel. Keywords: oblate spheroids, preferential orientation, shape effects, inertia effects
Inertial effects on non-spherical particle rotation on turbulent channel flow
No full textWe investigated the rotation of non-spherical particles (rod-like and disk-like) in turbulent channel flow with focus on inertial effects. A direct numerical simulation (DNS) with an Eulerian-Lagrangian approach was performed. A wide range of particle aspect ratios, λ, ranging from 0.01 to 50 were considered for Stokes numbers St equal to 1 and 30. In the particle reference frame, statistical results reveal the importance of shape effect on the particle rotation. The rods (λ > 1) are spinning (rotation about their symmetry axis) more than tumbling (rotation about other axes) whereas disks (λ < 1) behave oppositely. With increasing particle inertia, i.e. higher St, the preferential tumbling of the disks and the spinning of the rods are reduced. We ascribe these observations to the varying degree of alignment of the particle symmetry axis with the fluid vorticity vector
RR Lyrae stars in the GCVS observed by the Qatar Exoplanet Survey
No full textThis publication was made possible by NPRP grant # X-019-1-006 from the Qatar National Research Fund (a member of Qatar Foundation). AAF is grateful to DGAPA-UNAM for grant number IN104612.We used the light curve archive of the Qatar Exoplanet Survey to investigate the RR Lyrae variable stars listed in the GCVS. Of 588variables studied, we reclassified 14 as eclipsing binaries, one as an RS CVn type variable, one as an irregular variable, four as classical Cepheids, and one as a type II Cepheid, while also improving their periods. We also report new RR Lyrae sub-type classifications for 65variables and improve on the GCVS period estimates for 135 RR Lyrae variables. There are seven double-mode RR Lyrae stars in the sample for which we measured their fundamental and first overtone periods. Finally,we detected the Blazhko effect in 38 of the RR Lyrae stars for the first time and we successfully measured the Blazhko period for 26 of them.Peer reviewe
A comparison of rosseland-mean opacities from op and opal
No full textMonochromatic opacities from the Opacity Project (OP) have been augmented by hitherto missing inner-shell contributions. OP Rosseland-mean opacities, κR, are compared with results from OPAL for the six elements H, He, C, O, S and Fe. The OPAL data are obtained from the project's website. Agreement for H is close everywhere except for the region of log(T) 6 and log(R) −1 (R=ρ/T36 where ρ is mass density in g cm3 and T6= 106×T with T in K). In that region κR(OPAL) is larger than κR(OP) by up to 13 per cent. The differences are caused by different equations of state (EOS). In the region concerned, OP has the H ground state undergoing dissolution, leading to a small H-neutral ionization fraction, while OPAL has larger values for that fraction. A similar difference occurs for He at log(R) −1 and log(T) 6.4, where OP has the He+ ground state undergoing dissolution. The OPAL website does not provide single-element Rosseland means for elements other than H and He. Comparisons between OP and OPAL are made for mixtures with X= 0.9, Z= 0.1 and Z containing pure C, O or S. There are some differences: at the lower temperatures, say log(T) ≤ 5.5, owing to differences in atomic data, with the OP R-matrix data probably being the more accurate; and at higher temperatures mainly owing to differences in level populations resulting from the use of different EOS theories. In the original OP work, R-matrix data for iron were supplemented by data obtained using the configuration-interaction (CI) code superstructure. The experiment is made of replacing much of the original iron data with new data from the CI code autostructure. Inclusion of intercombination lines gives an increase in κR of up to 18 per cent. The OPAL website does not allow for Z containing pure iron. Comparisons are made for an iron-rich mixture, X= 0.9, Z= 0.1 and Z containing C and Fe with C:Fe = 2:1 by number fraction. There are some differences between OP and OPAL for that case: the OP 'Z-bump' in κR is shifted to slightly higher temperatures, compared with OPAL. Overall, there is good agreement between OP and OPAL Rosseland-mean opacities for the six elements, but there are some differences. Recent work has shown that helioseismology measurements give a very accurate value for the depth of the solar convective zone, RCZ, and that, taking account of recent revisions in abundances, solar models give agreement with that value only if opacities at RCZ are about 20 per cent larger than OPAL values. For the six-element mix at RCZ we obtain κR(OP) to be larger than κR(OPAL) by 5 per cent
Author Correction: Rapid increase in the risk of heat-related mortality.
No full textCorrection to: Nature Communicationshttps://doi.org/10.1038/s41467-023-40599-x, published online 24 August 2023 The original version of this Article omitted from the author list the 17th author, “Multi-Country Multi-City (MCC) collaborative research network”, which is the consortium providing the mortality data. A list of consortium authors and their affiliations are provided in the HTML version of this Correction. Part of the Author Contributions statement was incorrectly given and should have read ‘A.M.V.C., E.M.F., B.A., M.D.S.Z.S.C., Y.L.G., Y.G., Y.H., V.H., J.K., E.L., D.R., N.R., N.S., S.S., A.U., A.G. and the MCC were involved in resources and data curation.’ In addition, the primary affiliation ‘Climate Research Foundation (FIC), Madrid, Spain’ for Dominic Roye was missing
OCEANURB- the unseen spaces of Extended Urbanisation in the North Sea
No full textPosterHistory, Form & AestheticsOLD History of Architecture & Urban Plannin
Advancements in nonclassical gas dynamics
No full textShock waves can be formed in all states of matter, be it in the single- or multi-phase condition, when the substance is subjected to a rapid change of state, e.g., a sudden pressure variation. In the case of shock waves in vapors and gases, because of the fact that the developed theory is often based on the ideal-gas equation of state, it is commonly accepted that shock waves can be only of the compressive type, i.e., in the direction of flow, the gas experiences an abrupt increase of pressure whilst undergoing a supersonic-to-subsonic transition. Studies in the early 1940s and 1970s by Bethe, Zel’dovich and Thompson have shown however, that it is in principle possible, from a theoretical viewpoint, to deliberately create expansion shock waves, provided that the correct substance and initial states are chosen. The caloric property that is key in determining the nature of shock waves (and therefore the admissibility of expansion shock waves) is referred to as the fundamental derivative of gas dynamics and the implications of its value, namely when it is negative in so-called BZT fluids, have been studied extensively from a theoretical perspective. Experimental evidence of expansion shock waves in single-phase vapors is however unavailable. The motivation of this work stems from this lack of experimental evidence. The goal of the research project is to first identify BZT fluids. Once this is done, the aim is to develop, design, build and commission a setup which can be used to generate and study nonclassical expansion shock waves in molecularly complex BZT candidates. Finally, an unsteady nonclassical expansion shock wave is to be created and measured. The achievements of this project are: i) the identification of siloxane fluids as BZT candidates and ii) the building of a novel high-temperature flexible asymmetric shock tube with a fast-opening custom-designed valve. Cascading from this, new theory regarding nonclassical dense-gas dynamics has been developed which is very useful in the study of organic Rankine cycle turbogenerators which can benefit from the use of BZT fluids and their effects.Process and EnergyMechanical, Maritime and Materials Engineerin
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