15,646 research outputs found
EFD-P(13)60 ITER-Like Current Ramps in JET with ILW: Experiments, Modelling and Consequences for ITER
No full textSince the ITER-like wall in JET (JET-ILW) came into operation, dedicated ITER-like plasma current (Ip) ramp-up (RU) and ramp-down (RD) experiments have been performed and matched to similar discharges with the carbon wall (JET-C). The experiments show that access to H-mode early in the Ip RU phase and maintaining H-mode in the Ip RD as long as possible are instrumental to achieve low internal plasma inductance (li) and to minimize flux consumption. The measured H-mode power threshold during Ip RU is similar to that obtained during flat top, and lower than in JET-C. In JET-ILW, at a given current rise rate similar variations in li (0.70.9) are obtained as in JET-C. In most discharges no strong W accumulation is observed. However, in some low density cases during the early phase of the Ip RU (ne/neGw ~ 0.2) strong core radiation due to W influx led to hollow electron temperature (Te) profiles. In JET-ILW Zeff is significantly lower than in JET C. W significantly disturbs the discharge evolution when the W concentration approaches 104; this threshold is confirmed by predictive transport modelling using the CRONOS code. Similar modelling for the ITER Ip RU showed a comparable critical W concentration, however with opposite effect: in ITER a too high Wconcentration leads to a very peaked Te profile and too high li. Ip RD experiments in JET-ILW confirm the result of JET-C that sustained H-mode and elongation reduction are both instrumental in controlling li.Preprint of Paper to be submitted for publication in Nuclear Fusio
Measurement of the multi-jet cross-sections with the ATLAS detector at the LHC
No full textInclusive multi-jet production is studied using the ATLAS detector for proton-proton collisions
with a center-of-mass energy of 7 TeV at the Large Hadron Collider at CERN.
The data sample corresponds to an integrated luminosity of 2.4~pb, using the first proton-proton data collected by the ATLAS detector in 2010.
Results on multi-jet cross sections are presented and compared to both
leading-order plus parton-shower Monte Carlo predictions and next-to-leading-order QCD calculations
Degradation modes and tool wear mechanisms in finish and rough machining of Ti17 Titanium alloy under high-pressure water jet assistance
No full textThis article presents the results of an experimental study on the Ti17 titanium alloy, which was carried out to analyze tool wear and the degradation mechanisms of an uncoated tungsten carbide tool insert. Two machining conditions, roughing and finishing, have been studied under different lubrication conditions. The experimental procedure included measurement of the cutting forces and the surface roughness. Different techniques have been used to explain the tool wear mechanisms. Distribution maps of the elemental composition of the titanium alloy and the tool inserts have been created using Energy Dispersive X-ray Spectroscopy (EDS). An area of material deposition on the tool rake face, characterized by a high titanium concentration has been observed. The width of this area and the concentration of titanium, decrease when increasing water jet pressure. The study shows that wear mechanisms, with and without high-pressure water jet assistance (HPWJA) are not the same. For example, for the roughing condition using conventional lubrication, the temperature in the cutting area becomes very high, this causes plastic deformation of the cutting edge which results in its rapid collapse. By contrast, this problem disappears when machining with HPWJA. In addition, the evolution of flank wear (VB) is stabilized with high-pressure lubrication. In this case, the most critical degradation mode is due to notch wear (VBn) leading to the sudden rupture of the cutting edge.Région Pays de la Loir
A Parametric Study of Vane and Air-jet Vortex Generators
No full textAn experimental parametric sturdy of vane and air-jet vortex generators in a turbulent boundary
layer has been carried out. Experiments were carried out in two facilities, one with a free-stream
velocity of 20 m/s and a boundary layer thickness (6) of 41.5 mm, and one in a high speed facility
at free-stream Mach numbers of between 0.45 and 0.75 and a boundary layer thickness of 20 mm.
Cross-stream data were measured at a number of downstream locations using a miniature five-hole
pressure probe, such that local cross-stream velocity vectors could be derived. Streamwise
vorticity was calculated using the velocity vector data.
In the low speed study, vortex generator parameters were as follows:
" Vane vortex generators: thin rectangular vanes with a vane aspect ratio of unity (2h/c = 1),
free-stream velocity 20 m/s, incidence (cc = 10', 15', 18', 20'), height-to-boundary- layer-
thickness-ratio (h/8 0.554,0.916,1.27,1.639), and strearnwise distance from the vortex
generator (x/6 = 3.855,12.048,19.277,26.506).
" Air-jet vortex generators: circular jet nozzles, free-stream velocity = 20 m/s, jet nozzle pitch
and skew angles (cc, P= 30', 45', 60'), hole diameter-to-boundary-layer-thickness-ratio (D/5 =
0.098,0.193,0.289), jet-to-free-stream-velocity ratio (VR = 0.7,1.0,1.3,1.6,2.0), and
strearnwise distance from the vortex generator (x/8 = 3.855,12.048,19.277,26.506).
In the high-speed study, the vortex generator parameters were as follows:
Vane vortex generators: thin rectangular vanes with an aspect ratio of unity, incidence ((X
1505 20'), he i ght-to- boundary- I ayer-th i ckne s s-rati o (h/8 = 0.75), strearnwise distance from the
vortex generator (x/6 = 8.755 16.25,23.75), and free-stream Mach numbers of 0.45,0.6 and
0.75.
Air-jet vortex generators: jet pitch ((x = 30', 45'), jet skew angle (P = 30', 45', 60'), hole
diameter-to-boundary-layer-thickness-ratio (D/8 = 0.15,0.3), j et-to- free- strearn-ve loc ity ratio
(VR = 1.6), and strearnwise distance from the vortex generator (x/6 = 8.75,16.25,23.75,
31.25), and free-stream Mach numbers of 0.50,0.6 and 0.75.
Streamwise vorticity data from the experiment was used to generate prediction techniques that
would allow the vorticity profiles, downstream of vane or air-jet vortex generators, to be predicted.
Both techniques are based on the approximation of the experimental cross-stream vorticity data to
Gaussian distributions of vorticity through the vortex centre. The techniques, which are
empirically derived, are simple equations that give the peak vorticity and vortex radius based on
the vortex generator parameters. Use of these descriptors allows the assembly of the Gaussian
vorticity equation.
Both techniques are compared with the experimental data set and were seen to produce peak
vorticity results to within 12% and 20% (for the vanes and air-jets respectively), 15% for the
radius of the vortex, and 15% and 20% in vortex circulation (for the vanes and air-jets
respectively). The two simple prediction techniques allow good prediction of the vortex structure
at extremely low computational effort
fastmachinelearning/l1-jet-id: v0.1.0
No full text<h2>What's Changed</h2>
<ul>
<li>Add <code>environment.yml</code> by @jmduarte in https://github.com/fastmachinelearning/l1-jet-id/pull/1</li>
<li>Configurable accum_t by @jmduarte in https://github.com/fastmachinelearning/l1-jet-id/pull/2</li>
</ul>
<h2>New Contributors</h2>
<ul>
<li>@jmduarte made their first contribution in https://github.com/fastmachinelearning/l1-jet-id/pull/1</li>
</ul>
<p><strong>Full Changelog</strong>: https://github.com/fastmachinelearning/l1-jet-id/commits/v0.1.0</p>
EFD-C(13)02/03 Characterization of Local Heat Fluxes around ICRF Antennas on JET
No full textWhen using Ion Cyclotron Range of Frequency (ICRF) heating, enhanced power deposition on Plasma-Facing Components (PFCs) close to the antennas can occur. Experiments have recently been carried out on JET with the new ITER-Like-Wall (ILW) to characterize the heat fluxes on the protection of the JET ICRF antennas, using Infra-Red (IR) thermography measurement. The measured heat flux patterns along the poloidal limiters surrounding powered antennas were compared to predictions from a simple RF sheath rectification model. The RF electric field, parallel to the static magnetic field in front of the antenna, was evaluated using the TOPICA code, integrating a 3D flattened model of the JET A2 antennas. The poloidal density variation in front of the limiters was obtained from the mapping of the Li-beam or edge reflectometry measurements using the flux surface geometry provided by EFIT equilibrium reconstruction. In many cases, this simple model can well explain the position of the maximum heat flux on the different protection limiters and the heat-flux magnitude, confirming that the parallel RF electric field and the electron plasma density in front of the antenna are the main driving parameters for ICRF-induced local heat fluxes.Preprint of Paper to be submitted for publication in Proceedings of the 20th Topical Conference on Radio Frequency Power in Plasmas, Sorrento, Italy. 25th June 2013 - 28th June 201
sj-tif-1-jet-10.1177_15266028231208638 – Supplemental material for Incidence of Distal Radial Artery Occlusion and its Influencing Factors After Cardiovascular Intervention Via the Distal Transradial Access
No full textSupplemental material, sj-tif-1-jet-10.1177_15266028231208638 for Incidence of Distal Radial Artery Occlusion and its Influencing Factors After Cardiovascular Intervention Via the Distal Transradial Access by Tao Chen, Lamei Li, Anni Yang, Hui Huang, Ganwei Shi, Feng Li, Wenhua Li, Wei Lu, Lingxia Xu, Li Li and Gaojun Cai in Journal of Endovascular Therapy</p
sj-tif-2-jet-10.1177_15266028231208638 – Supplemental material for Incidence of Distal Radial Artery Occlusion and its Influencing Factors After Cardiovascular Intervention Via the Distal Transradial Access
No full textSupplemental material, sj-tif-2-jet-10.1177_15266028231208638 for Incidence of Distal Radial Artery Occlusion and its Influencing Factors After Cardiovascular Intervention Via the Distal Transradial Access by Tao Chen, Lamei Li, Anni Yang, Hui Huang, Ganwei Shi, Feng Li, Wenhua Li, Wei Lu, Lingxia Xu, Li Li and Gaojun Cai in Journal of Endovascular Therapy</p
Parametric study of dust acoustic wave destabilization in the JET scrape-off layer
No full textPublisher Copyright: © 2024 Author(s).Sudden inflows of W particulate are routinely observed in correlation with plasma instabilities in JET-ITER-Like-Wall experimental campaigns. Dust acoustic wave destabilization by micrometer-size tungsten dust released in such events is simulated here using realistic parameters describing the JET scrape-off layer. Such low-frequency waves may serve as a monitorable signal for dust detection in the scrape-off layer on a pulse-by-pulse basis.Peer reviewe
Numerical and experimental investigation of a confined plunging liquid jet system
No full textIn a confined plunging liquid jet (CPLJ) system, a liquid jet is allowed to fall in a partially submerged narrow downcomer tube. Liquid jet impingement at gas-liquid interface leads to entrainment of gas, which is dispersed down the downcomer tube in to outer pool in form of bubbles. This simple phenomenon of gas entrainment bears great industrial significance. It facilitates an efficient gas liquid contacting device, which can be used for waste water aeration and lake destratification etc. In present work, a confined plunging liquid jet system was experimentally and numerically analyzed. On experimental front, a laboratory scale CPLJ setup was developed. Impact of change in jet height, water flow rate and nozzle diameter on, bubble plume size and surrounding flow field was investigated through high speed camera photography and Particle Image Velocimetry. Image processing programs were developed in MATLAB for extracting plume boundaries in high speed camera images. Experimental results showed that, bubble plume width and flow field is only weakly dependent on jet height. With increase in water flow rate, bubble plume size and air lifted water velocity increases. Increase in nozzle diameter, at constant water flow rate and jet height, decreases both the plume size and upward water velocity. On numerical front, a 3D Euler-Euler two-fluid CFD simulation of bubble plume dispersion was performed for the test case of 7 mm nozzle diameter, 100 mm jet length and 12.5 LPM water flow rate. Grid generation was done in GAMBIT while CFD software ANSYS CFX 12.1 was used for CFD simulations. Air phase was modelled as a polydispersed fluid with eight size bins. In CFD modelling, interfacial drag, lift, wall lubrication and turbulent dispersion forces were incorporated through appropriate correlations. Numerical and experimental results were found to be in agreement with each other. CFD results showed that at least 85% of the inlet air breaks thorough the downcomer tube in to outer water tan
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