118,128 research outputs found
Intermittency and regularity issues in 3D Navier-Stokes turbulence
No full textTwo related open problems in the theory of 3 D Navier-Stokes turbulence are discussed in this paper. The first is the phenomenon of intermittency in the dissipation field. Dissipation-range intermittency was first discovered experimentally by Batchelor and Townsend over fifty years ago. It is characterized by spatio-temporal binary behaviour in which long, quiescent periods in the velocity signal are interrupted by short, active ‘events’ during which there are violent fluctuations away from the average. The second and related problem is whether solutions of the 3 D Navier-Stokes equations develop finite time singularities during these events. This paper shows that Leray’s weak solutions of the three-dimensional incompressible Navier-Stokes equations can have a binary character in time. The time-axis is split into ‘good’ and ‘bad’ intervals: on the ‘good’ intervals solutions are bounded and regular, whereas singularities are still possible within the ‘bad’ intervals. An estimate for the width of the latter is very small and decreases with increasing Reynolds number. It also decreases relative to the lengths of the good intervals as the Reynolds number increases. Within these ‘bad’ intervals, lower bounds on the local energy dissipation rate and other quantities, such as || u (·, t )|| ∞ and ||∇ u (·, t )|| ∞ , are very large, resulting in strong dynamics at sub-Kolmogorov scales. Intersections of bad intervals for n ≧1 are related to the potentially singular set in time. It is also proved that the Navier-Stokes equations are conditionally regular provided, in a given ‘bad’ interval, the energy has a lower bound that is decaying exponentially in time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46170/1/205_2005_Article_382.pd
Stokes diagnostics of simulated solar magneto-convection
No full textWe present results of synthetic spectro-polarimetric diagnostics of radiative MHD simulations of solar surface convection with magnetic fields. Stokes profiles of Zeeman-sensitive lines of neutral iron in the visible and infrared spectral ranges emerging from the simulated atmosphere have been calculated in order to study their relation to the relevant physical quantities and compare with observational results. We have analyzed the dependence of the Stokes-I line strength and width as well as of the Stokes-V signal and asymmetries on the magnetic field strength. Furthermore, we have evaluated the correspondence between the actual velocities in the simulation with values determined from the Stokes-I (Doppler shift of the centre of gravity) and Stokes-V profiles (zero-crossing shift). We confirm that the line weakening in strong magnetic fields results from a higher temperature (at equal optical depth) in the magnetic flux concentrations. We also confirm that considerable Stokes-V asymmetries originate in the peripheral parts of strong magnetic flux concentrations, where the line of sight cuts through the magnetopause of the expanding flux concentration into the surrounding convective donwflow
Publication in BMC Research Notes: Shifts in soil and plant functional diversity along an altitudinal gradient in the French Alps
No full textAuthors: Stokes A., Angeles G., Barois I., Bounous M, Cruz-Maldonaldo N, Decaëns T, Freschet G., Gabriac Q, Hernandez D., Jimenez L., Ma J, Mao Z, Marin-Castro B, Merino-Martin L, Mohamed A, Reverchon F, Selli L., Sieron K., Weemstra M., Roumet
NAVIER–STOKES EQUATIONS ON THE β-PLANE
No full textMathematical analysis has been undertaken for the vorticity formulation of the two dimensional Navier–Stokes equation on the β-plane with periodic boundary conditions. This equation describes the flow of fluid near the equator of the Earth. The long time behaviour of the solution of this equation is investigated and we show that, given a sufficiently regular forcing, the solution of the equation is nearly zonal. We use this result to show that, for sufficiently large β, the global attractor of this system reduces to a point. Another result can be obtained if we assume that the forcing is time-independent and sufficiently smooth. If the forcing lies in some Gevrey space, the slow manifold of the Navier–Stokes equation on the β-plane can be approximated with O(εn/2) accuracy for arbitrary n = 0, 1, · · · , as well as with exponential accuracy
Integral representation of a solution to the Stokes-Darcy problem
No full textWith methods of potential theory we develop a representation of a solution of the coupled Stokes-Darcy model in a Lipschitz domain for boundary data in H-1/2
Interview of Frank G. Stokes by Brian Shoemaker
No full textThe media can be accessed at the links below.Audio Part 1: http://streaming.osu.edu/knowledgebank/byrd/oral_history/Capt_Francis_Stokes_1.mp3Audio Part 2: http://streaming.osu.edu/knowledgebank/byrd/oral_history/Capt_Francis_Stokes_2.mp3Capt Stokes became interested in Admiral Byrd after listening to the Admiral’s broadcasts during his expeditions. He graduated from the Naval Academy in 1953 and after his first tour of duty volunteered for Operation Deep Freeze. He was assigned to Little America in the fall of 1957 as the Communications Officer. He sailed from Seattle aboard the USS Atka via Christchurch to Little America at Kainan Bay. He gives good descriptions about life “On the Ice”. Mentions that Gus Shinn was their station pilot and that he spent the summer at Little America. Give a thorough accounting of the incident of Bert Crary falling into Kainan Bay when the ice front collapsed. Mentions “Little America College” and the regular lecture series that was involved. Little America was officially closed as a science base at the end of IGY (Dec 31, 1958), but Stokes was left behind with a close-out crew. He closed out the station on January 19, 1959 – he was the last to leave. He never had duty again in the Antarctic, but returned twice as a tourist in 1994 and 1995. The following is pertinent:
1. Listened to Admiral Byrd on radio as a young man.
2. While at Naval Academy wrote thesis on Admiral Byrd.
3. Volunteered for Deep Freeze after his first tour in fleet in 1957.
4. Was sent to Thule Greenland for survival school.
5. Was assigned as the Communications Officer to Antarctic Support Activities headed by Capt Pat Mayer.
6. He flew to Christchurch and boarded the USS Atka and headed for Kainan Bay.
7. He describes crashing two helicopters at Little America.
8. Slept in sleeping bag at first until previous winter crew left.
9. CDR Tommy Thompson was CO of Little America – Stokes boss.
10. Stokes was also Postal Officer requiring him to fly to Byrd Station and McMurdo.
11. Describes “Goober Beer”.
12. Discusses “All Hands” Club and fraternization with enlisted.
13. Discusses Antarctic Weather Central.
14. Describes the effect of sun-spots on communications.
15. States that there were four pilots assigned during the winter – they flew all winter.
16. He was duty officer when Bert Crary, the chief scientist in Antarctica, fell into Kainan Bay and was rescued by helicopter. He describes the incident in detail since he coordinated the rescue.
17. He discusses HAM Radio and its importance to morale.
18. Talks about the routine of steam-baths with others of the staff.
19. Frank and the scientists started “Little America College” which had lectures and movies every night.
20. He discusses the closing of Little America V. Stokes was the last man to leave.
21. Traveled to New Zealand on the USS Arneb
22. Returned to Ross Sea with Fuch and Hillary in 1994 as a tourist and again in 1995.
23. In 2001 Stokes joined a group from the Planetary Studies Foundation and Harper College to collect meteorites in Antarctica.Funded by a grant from the National Science Foundation
Mennine-Stokes Collection; no.07728
No full textSepia image of Henry B. Ailman and Henry M. Meridith posed standing in front of their bank, Meredith & Ailman Bankers. with two unidentified men. Poised at left side of photograph are two boys, and posed at right side of photograph stands an unidentified man in front of the C. G. Kidd____ Wholesaler in Cigars, Tobacco and Smokers ____ storefront. Image mounted on a gray matte board.Master file: image/tiff; 111,656 KB; Computer Hardware: Intel Pentium (R) 4 3.20 GHz/ 1.99 GB RAM manufactured by Dell; Operating system: Windows XP 2002; Creation software: Adobe Photoshop CS2 version 9.0.2; Scanner: flatbed reflective scanner Microtek 1000XL; Scanner software: Microtek SilverFast Ai 6.4.2r2b; Scanned by Jackie Becker on 2009-10-23
Māori in Engineering Podcast, Episode 9: Georgina Stokes: designing how we experience and understand spaces
No full textEpisode 19 of The Māori in Engineering podcast is now live!
A long time coming in getting episodes out, mō taku hē. So it was great to dust off the mic!
Awesome to catch up with Georgina Stokes (Ngāi Tahu) - someone who is an incredible thinker in the spatial design space and inspiration to those she lectures at Toi Rauwhārangi College of Creative Arts at Massey University kei Te Whanganui a Tara.
Georgina is an overall awesome wahine, pretty evident in the way she communicates so passionately with the work. Really interesting points of discussions was her mahi in whakapapa plotting to better how we experience spaces and the alignment in her studies and her Māoritanga
Available on all podcast platforms and the website https://lnkd.in/gPkURGxB
Listen on Spotify here: https://lnkd.in/gz3xkQyj
#MāoriinEngineerin
Large-time behavior of the weak solution to 3D Navier-Stokes equations
No full textThe weak solution to the Navier–Stokes equations in a bounded domain D ⊂ R[superscript 3] with a smooth boundary is proved to be unique provided that it satisfies an additional requirement. This solution exists for all t ≥ 0. In a bounded domain D the solution decays exponentially
fast as t → ∞if the force term decays at a suitable rat
Louis Stokes Interview, 17 December 2014
No full textThis interview was conducted as part of Cleveland State University\u27s 50th Anniversary Commemoration effort. Born and raised in Cleveland, Louis Stokes is most widely recognized as being the first African-American to be elected to Congress from Ohio. Stokes graduated from Central High School and was drafted into the army during WW2. Following his service in the military he attended Western Reserve University on his GI Bill and continued on to earn his law degree from Cleveland-Marshall Law School. After law school Stokes practiced law for a number of years with his brother Carl, who later made history when he was elected mayor of Cleveland, the first African-American to hold that office in a major US city, and the prominent defense lawyer Norman Minor. Of particular interest is Stokes\u27 description of Cleveland-Marshall, especially its dean, Wilson G. Stapleton, stories of his early years in the law profession, and his account the events leading to his election to Congress
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