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Streaks to Rings to Vortex Grids: Generic Patterns in Transient Convective Spin Up of an Evaporating Fluid

Physical Review Letters 2010年第4期105卷 044504-044504页

作者： J.-Q. Zhong M. D. Patterson J. S. Wettlaufer Department of Geology & Geophysics Yale University New Haven Connecticut 06520-8109 USA Faculty of Engineering & Design University of Bath Bath BA2 7AY United Kingdom Department of Physics Yale University New Haven Connecticut 06520-8109 USA Program in Applied Mathematics Yale University New Haven Connecticut 06520-8109 USA

We observe the transient formation of a ringed pattern state during spin up of an evaporating fluid on a time scale of order a few Ekman spin up times. The ringed state is probed using infrared thermometry and particle image velocimetry and it is demonstrated to be a consequence of the transient balance between Coriolis and viscous forces which dominate inertia, each of which are extracted from the measured velocity field. The breakdown of the ringed state is quantified in terms of the antiphasing of these force components which drives a Kelvin-Helmholtz instability and we show that the resulting vortex grid spacing scales with the ring wavelength. This is the fundamental route to quasi-two-dimensional turbulent vortex flow and thus may have implications in astrophysics and geophysics wherein rotating convection is ubiquitous.

关键词： Vortex flow

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Galactic transient sources with the Cherenkov Telescope Array Observatory

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Monthly Notices of the Royal Astronomical Society 2025年第1期540卷 205–238页

作者： Abe, K Abe, S Abhir, J Abhishek, A Acero, F Acharyya, A Adam, R Aguasca-Cabot, A Agudo, I Aguirre-Santaella, A Alfaro, J Alfaro, R Alvarez-Crespo, N Alves Batista, R Amans, J-P Amato, E Ambrosi, G Ambrosino, F Angüner, E O Antonelli, L A Aramo, C Arcaro, C Arnesen, T T H Asano, K Ascasibar, Y Aschersleben, J Ashkar, H Augusto Stuani, L Baack, D Backes, M Balazs, C Balbo, M Baquero Larriva, A Barbosa Martins, V Barres de Almeida, U Barrio, J A Barrios-Jiménez, L Batković, I Batzofin, R Baxter, J Becerra González, J Becker Tjus, J Belmont, R Benbow, W Bernete, J Bernlöhr, K Berti, A Bertucci, B Beshley, V Bhattacharjee, P Bhattacharyya, S Bigongiari, C Bissaldi, E Blanch, O Blazek, J Bocchino, F Boisson, C Bolmont, J Bonnoli, G Bonollo, A Bordas, P Bosnjak, Z Bottacini, E Böttcher, M Bradascio, F Bronzini, E Brown, A M Brunelli, G Bulgarelli, A Burelli, I Burger-Scheidlin, C Burmistrov, L Burton, M Buscemi, M Cailleux, J Campoy-Ordaz, A Cantlay, B K Capasso, G Caproni, A Capuzzo-Dolcetta, R Caraveo, P Caroff, S Carosi, A Carosi, R Carquin, E Carrasco, M-S Cascone, E Cassol, F Castaldini, L Castrejon, N Castro-Tirado, A J Cerasole, D Ceribella, G Cerruti, M Chadwick, P M Chaty, S Chen, A W Chernyakova, M Chiavassa, A Chudoba, J Chytka, L Cicciari, G M Cifuentes, A Coimbra Araujo, C H Colapietro, M Conforti, V Contreras, J L Cortina, J Costa, A Costantini, H Cotter, G Cristofari, P Cuevas, O Curtis-Ginsberg, Z D’Aì, A D’Amico, G D’Ammando, F Dai, S Dazzi, F de Bony de Lavergne, M De Caprio, V De Cesare, G De Frondat Laadim, F de Gouveia Dal Pino, E M De Lotto, B De Lucia, M de Martino, D de Menezes, R de Naurois, M de Ona Wilhelmi, E de Souza, V del Peral, L del Valle, M V Delgado, C Dell’aiera, M Della Valle, M della Volpe, D Depaoli, D Devin, J Di Girolamo, T Di Piano, A Di Pierro, F Di Tria, R Di Venere, L Diebold, S Dignam, C Dima, R Dinesh, A Djuvsland, J Dominik, R M Dominis Prester, D Donini, A Dorner, D Dörner, J Doro, M Dubos, C Ducci, L Dwarkadas, V V Ebr, J Eckner, C Egberts, K Einecke, S Elsässer, D Emery Department of Physics Tokai University 4-1-1 Kita-Kaname Hiratsuka Kanagawa 259-1292 Japan Institute for Cosmic Ray Research University of Tokyo 5-1-5 Kashiwa-no-ha Kashiwa Chiba 277-8582 Japan ETH Zürich Institute for Particle Physics and Astrophysics Otto-Stern-Weg 5 CH-8093 Zürich Switzerland INFN and Università degli Studi di Siena Dipartimento di Scienze Fisiche della Terra e dell’Ambiente (DSFTA) Sezione di Fisica Via Roma 56 I-53100 Siena Italy Université Paris-Saclay Université Paris Cité CEA CNRS AIM F-91191 Gif-sur-Yvette Cedex France FSLAC IRL 2009 CNRS/IAC E-38205 La Laguna Tenerife Spain University of Alabama Tuscaloosa Department of Physics and Astronomy Gallalee Hall Box 870324 Tuscaloosa AL 35487-0324 USA Université Côte d’Azur Observatoire de la Côte d’Azur CNRS Laboratoire Lagrange UF 06304 Nice France Laboratoire Leprince-Ringuet CNRS/IN2P3 École Polytechnique Institut Polytechnique de Paris F-91120 Palaiseau France Departament de Física Quàntica i Astrofísica Institut de Ciències del Cosmos Universitat de Barcelona IEEC-UB Martí i Franquès 1 E-08028 Barcelona Spain Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n E-18008 Granada Spain Institute for Computational Cosmology and Department of Physics Durham University South Road Durham DH1 3LE UK Pontificia Universidad Católica de Chile Av. Libertador Bernardo O’Higgins 340 8331150 Santiago Chile Universidad Nacional Autónoma de México Delegación Coyoacán 04510 Ciudad de México Mexico IPARCOS-UCM Instituto de Física de Partículas y del Cosmos and EMFTEL Department Universidad Complutense de Madrid E-28040 Madrid Spain Instituto de Física Teórica UAM/CSIC and Departamento de Física Teórica Universidad Autónoma de Madrid c/ Nicolás Cabrera 13-15 Campus de Cantoblanco UAM E-28049 Madrid Spain LUTH GEPI and LERMA Observatoire de Paris Université PSL Université Paris Cité CNRS 5 place Jules Janssen F-92190 Meudon France INAF – Osservatorio

A wide variety of Galactic sources show transient emission at soft and hard X-ray energies: low- and high-mass X-ray binaries containing compact objects, isolated neutron stars exhibiting extreme variability as magnetars as well as pulsar-wind nebulae. Although most of them can show emission up to MeV and/or GeV energies, many have not yet been detected in the TeV domain by Imaging Atmospheric Cherenkov Telescopes. In this paper, we explore the feasibility of detecting new Galactic transients with the Cherenkov Telescope Array Observatory (CTAO) and the prospects for studying them with Target of Opportunity observations. We show that CTAO will likely detect new sources in the TeV regime, such as the massive microquasars in the Cygnus region, low-mass X-ray binaries with low-viewing angle, flaring emission from the Crab pulsar-wind nebula or other novae explosions, among others. Since some of these sources could also exhibit emission at larger time-scales, we additionally test their detectability at longer exposures. We finally discuss the multiwavelength synergies with other instruments and large astronomical facilities.

关键词： binaries: general stars: magnetars novae cataclysmic variables pulsars: general gamma-rays: general

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Numerical validation of scaling laws for stratified turbulence

arXiv

引用

arXiv 2024年

作者： Garaud, Pascale Chini, Gregory P. Cope, Laura Shah, Kasturi Caulfield, Colm-Cille P. Department of Applied Mathematics and Theoretical Physics University of Cambridge CambridgeCB3 0WA United Kingdom Department of Applied Mathematics Baskin School of Engineering University of California Santa Cruz Santa CruzCA95064 United States Program in Integrated Applied Mathematics Department of Mechanical Engineering University of New Hampshire DurhamNH03824 United States School of Mathematics University of Leeds LeedsLS2 9JT United Kingdom Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology CambridgeMA02139 United States Institute for Energy and Environmental Flows University of Cambridge CambridgeCB3 0EZ United Kingdom

Recent theoretical progress using multiscale asymptotic analysis has revealed various possible regimes of stratified turbulence. Notably, buoyancy transport can either be dominated by advection or diffusion, depending on the effective Péclet number of the flow. Two types of asymptotic models have been proposed, which yield measurably different predictions for the characteristic vertical velocity and length scale of the turbulent eddies in both diffusive and non-diffusive regimes. The first, termed a ‘single-scale model’, is designed to describe flow structures having large horizontal and small vertical scales, while the second, termed a ‘multiscale model’, additionally incorporates flow features with small horizontal scales, and reduces to the single-scale model in their absence. By comparing predicted vertical velocity scaling laws with direct numerical simulation data, we show that the multiscale model correctly captures the properties of strongly stratified turbulence within regions dominated by small-scale isotropic motions, whose volume fraction decreases as the stratification increases. Meanwhile its single-scale reduction accurately describes the more orderly, layer-like, quiescent flow outside those regions. Copyright © 2024, The Authors. All rights reserved.

关键词： Asymptotic analysis

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Changes in electroencephalography complexity of acute Ischemic stroke: A fuzzy approximate entropy analysis

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AIP Conference Proceedings 2020年第1期2314卷

作者： Osmalina Nur Rahma Alfian Pramudita Putra Angga Bagus Prasetyo Riries Rulaningtyas Sastra Kusuma Wijaya 1Biomedical Engineering Study Program Department of Physics Faculty of Science and Technology Airlangga University Indonesia 2Department of Physics Faculty of Mathematics & Natural Science University of Indonesia Indonesia

Stroke is one of the leading causes of death in the world. The previous study had shown that EEG (Electroencephalogram) was a promising tool to detect stroke since it is non-invasive and cheap. So, the EEG analysis method needs to be more explored to give an accurate prognosis assessment. Previously, complexity analysis, such as Fuzzy Approximate Entropy (fApEn), had been successfully differentiated between control and patients with Alzheimer's Disease. Thus, this study used fApEn to analyse the changes of electroencephalography complexity in Acute Ischemic Stroke (AIS) during hyperventilation and photic stimulation, which are a general protocol to investigate the abnormality in EEG. Photic stimulation conducted using white light that flashed with frequency 5Hz, 10Hz, and 15Hz consecutively for three minutes and then continued by hyperventilation for three minutes, approximately. This study compared the fApEn value from healthy subjects with AIS patients. The result showed that patient with AIS tended to conduct the lower and higher fApEn value compared to the healthy subject. The lower value of fApEn occurred because of the presence of the slow-waves on the EEG, while the higher fApEn indicated the epileptiform activity during the recording. The increment of the slow-waves and the presence of epileptiform activity could be considered as the characteristic of stroke even though its appearance is uncertain. However, complexity analysis of EEG could be useful in differentiating the healthy subject and patient with stroke or classifying the severity level of the stroke to improve stroke management.

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Synthesis of colloidal platinum nanoparticles using pulse laser ablation method

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AIP Conference Proceedings 2018年第1期2014卷

作者： Oki Dimas Prasetya Ali Khumaeni 1Magister Program of Physics Department of Physics Faculty of Science and Mathematics Diponegoro University Indonesia 2Department of Physics Faculty of Science and Mathematics Diponegoro University Jl. Prof. Soedharto SH Tembalang Semarang 50275 Indonesia

High-purity platinum nanoparticles (PtNPs) has been successfully synthesized in a pure water by using laser ablation method utilizing low-power neodymium yttrium aluminium garnet (Nd:YAG) laser at fundamental wavelength. Experimentally, pulse laser beam (Nd:YAG laser, 1064 nm, 7 ns, 30 mJ) was directed and focused onto a high-purity platinum sheet (99.9%), which was placed into a pure liquid of deionized water, to produce PtNPs colloid. The morphology, size distribution and optical properties of the Pt nanoparticles (PtNPs) were observed by scanning electron microscope (SEM) and UV-vis spectrometer. The average diameter of Pt NPs prepared in 10 Hz and 15 Hz ranges around 8 nm and 9 nm, respectively. Dark-yellow color colloid containing high-purity PtPs was successfully produced.

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Steady Rayleigh-BénardRayleigh-Bénard convection between stress-free boundaries

arXiv

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arXiv 2020年

作者： Wen, Baole Goluskin, David LeDuc, Matthew Chini, Gregory P. Doering, Charles R. Department of Mathematics University of Michigan Ann ArborMI48109-1043 United States Department of Mathematics & Statistics University of Victoria VictoriaBCV8P 5C2 Canada Department of Physics University of Michigan Ann ArborMI48109-1040 United States Program in Integrated Applied Mathematics University of New Hampshire DurhamNH03824 United States Department of Mechanical Engineering University of New Hampshire DurhamNH03824 United States Center for the Study of Complex Systems University of Michigan Ann ArborMI48109-1042 United States

Steady two-dimensional Rayleigh-Bénard convection between stress-free isothermal boundaries is studied via numerical computations. We explore properties of steady convective rolls with aspect ratios π/5 ⩽ Γ ⩽ 4π, where Γ is the width-to-height ratio for a pair of counter-rotating rolls, over eight orders of magnitude in the Rayleigh number, 103 ⩽ Ra ⩽ 1011, and four orders of magnitude in the Prandtl number, 10−2 ⩽ Pr ⩽ 102. At large Ra where steady rolls are dynamically unstable, the computed rolls display Ra → ∞ asymptotic scaling. In this regime, the Nusselt number Nu that measures heat transport scales as Ra1/3 uniformly in Pr. The prefactor of this scaling depends on Γ and is largest at Γ ≈ 1.9. The Reynolds number Re for large-Ra rolls scales as Pr−1Ra2/3 with a prefactor that is largest at Γ ≈ 4.5. All of these large-Ra features agree quantitatively with the semi-analytical asymptotic solutions constructed by Chini & Cox (2009). Convergence of Nu and Re to their asymptotic scalings occurs more slowly when Pr is larger and when Γ is smaller. Copyright © 2020, The Authors. All rights reserved.

关键词： Prandtl number

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Synthesis of silver nanoparticles using laser ablation method utilizing Nd:YAG laser

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AIP Conference Proceedings 2019年第1期2202卷

作者： Mohammad Zamakhsari Alhamid Beny S. Hadi Ali Khumaeni 1Master Program of Physics Department of Physics Faculty of Science and Mathematics Diponegoro University Tembalang Semarang 50275 Indonesia 2Department of Physics Faculty of Science and Mathematics Diponegoro University Jl. Prof. Soedharto SH Tembalang Semarang 50275 Indonesia

Silver nanoparticles (AgNPs) have attracted many researchers and scientist within the past decade due to their unique characteristics in physical, chemical, and biological properties compared to their macro scale. The AgNPs have been important subject of interest in applied science and material field and widely applied for various applications in the field of physics, chemistry, biology, environment, and medicine. The techniques usually used to synthesize silver nanoparticles are chemical, biological, and physical methods. However, chemical and biological methods still suffer from tedious sample pretreatment, contamination from additional agents during synthesis process, and quiet hazard and expensive. In this study, silver nanoparticles was synthesized using pulse laser ablation method. Experimentally, a high-purity silver plate (99, 95 %) was immersed in 25 ml pure aquades placed in a petri dish with a diameter 50 mm. A pulsed (Nd : YAG) laser (New Polaris II 1064 nm, max energy of 50 mJ, 7 ns) was focused on the gold sample target by a convex lens with a focal length of 30 mm. The laser repetition rate was 10 Hz, and the duration of laser bombardment was 13 hours. The results show that colloidal silver nanoparticles has yellowish colour. Furthermore, the produce silver nanoparticles have spherical shape with an averaged diameter size of tens nm. Detail results and discussion will be presented during presentation.

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Flagellum motion in 2-D: Work rate and efficiency of the non-sinusoidal approach

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AIP Conference Proceedings 2018年第1期1937卷

作者： Sparisoma Viridi Nuning Nuraini Monica Stephanie Ainur Rifqi Dina Christina Elsa Thania Erland Sihite 1Department of Physics Institut Teknologi Bandung Bandung 40132 Indonesia 2Department of Mathematics Institut Teknologi Bandung Bandung 40132 Indonesia 3Undergraduate Program Department of Mathematics Institut Teknologi Bandung Bandung 40132 Indonesia

Today microorganisms have been widely used to support human life. Some examples include foodstuffs (***), to help with medical needs, for mining purposes and more. On the other hand, the development of technology is also very big influence on human life. The combination of technology and health science will be very useful if we can develop it. One is the cancer treatment by utilizing the movement of the flagella to be made a nanorobot used as a carrier of cancer drugs. Movement of flagella that resembles the shape of the arc and straight line can be searched formulation and then applied to the manufacture of nanorobot tail. Then the nanorobot will carry a cancer drug that leads directly to the cancer cells. So hopefully with this nanorobot, can minimize the death of healthy cells around cancer cells. From the results of research and analysis of the movement of flagella, it can be concluded that the smaller the mass of the flagella, the greater the efficiency will be or will be more efficient. So, the energy needed nanorobot will be smaller. Model with non-sinusoidal approach (Brokaw, 1965) is discussed in this work and formulation to get the energy efficiency is proposed and analyzed. Unfortunately, there is a negative value in the formulation.

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Comparative analysis of median and Laplacian filter to detect edges of non-contrast cardiac CT image

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AIP Conference Proceedings 2022年第1期2391卷

作者： Nur Endah Sari Prawito Prajitno Djarwani Soeharso Soejoko 1Master Program of Science Department of Physics Faculty of Mathematics and Natural Science Universitas Indonesia Kampus UI Depok Jawa Barat Indonesia 2Department of Physics Faculty of Mathematics and Natural Science Universitas Indonesia Kampus UI Depok Jawa Barat Indonesia

The incidence of heart disease is increasing every year. One of the preventive actions is through early detection of the disease to take further action. Computer-Aided Diagnosis (CAD) helps doctors and cardiologists detect heart abnormalities seen in non-contrast cardiac CT images faster than manual detection. This study aims to detect the edges of non-contrast cardiac CT images. The method used is the Median and Laplacian filter algorithm using Matlab. The result shows that there is an automatic edge detection of non-contrast cardiac CT images. The conclusion obtained by the Laplacian filter with -8 kernel at its centre is clearer to detect edges of non-contrast cardiac CT images than the Median and Laplacian filters with -4 kernel at the centre. The study results are useful for medical image processing to facilitate the subsequent image analysis stage.

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Publisher's Note: “Reacting and non-reacting, three-dimensional shear layers with spanwise stretching” [Phys. Fluids 34, 123602 (2022)]

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physics of Fluids 2023年第1期35卷

作者： Jonathan L. Palafoutas William A. Sirignano 1Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08540 USA 2Department of Mechanical and Aerospace Engineering University of California Irvine Irvine California 92697 USA

This article was published online on 2 December 2022 with errors throughout the paper. All the derivative terms had the wrong denominator; the denominators were

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