Concept

Jet airliner

Publications associées (27)

Heating D ions to optimal D-T fusion energies in JET-ILW

In JET-ILW, beam-target reactions contribute to a large fraction of the fusion power generated in Deuterium – Tritium (D-T) plasmas, with core ion temperatures of 10-12keV and large neutral-beam injection (NBI) power. Previous modelling done in preparation for the recent D-T campaigns in JET have shown that injecting D beam ions with energies of ~120keV in T-rich plasmas produces larger 14MeV fusion yield than in 50:50 D:T plasmas, but such scenario had never been tested in past D-T experiments. In addition

IOP Publishing Ltd2026

Vertical measurements of aerosols in the high Arctic during the winter-spring transition using a tethered balloon

Aerosol number size distributions, along with thermodynamic and dynamic parameters, were measured from the surface to 600 m using a tethered balloon, the Helikite. The field measurements were carried out at Villum Research Station in Northern Greenland from 23rd March to 2nd May 2024. During the transition from winter to spring, three types of atmospheric regimes were identified: (1) a background regime with a profile of uniformly distributed aerosols, represented by low particle number concentrations as we

2025

Ghost Noise for Regularizing Deep Neural Networks

Batch Normalization (BN) is widely used to stabilize the optimization process and improve the test performance of deep neural networks. The regularization effect of BN depends on the batch size and explicitly using smaller batch sizes with Batch Normalization, a method known as Ghost Batch Normalization (GBN), has been found to improve generalization in many settings. We investigate the effectiveness of GBN by disentangling the induced ``Ghost Noise'' from normalization and quantitatively analyzing the dist

Association for the Advancement of Artificial Intelligence2024

Plunging Circular Jets: Experimental Characterization of Dynamic Pressures Near the Stagnation Zone

Spillways are a requirement for dams' safety, mainly preventing dam over-topping in ood cases. A common spillway solution involves plunging jets which dissipate a considerable energy ow in the plunge pool. Dissipation has to occur in a controlled manner to avoid endangering dam's foundations and the river valley slopes. Indeed, a scouring process in the downstream riverbed will inevitably develop until an equilibrium is reached, or else, a pre-excavated or concrete lined plunge pool has to be provided. The

2021

Hydraulic performance of stepped spillway aerators and related downstream flow features

Roller compacted concrete gravity dams are built since several decades. In combination with such dams, stepped spillways are very often used as efficient flood release structures. More recently stepped spillways are also excavated into rock along the abutments of embankment dams. Over the last years, the specific design discharge over stepped spillways has increased significantly. Specific discharge higher than 30m3/sm for skimming flow regime are not rare anymore. For such high specific discharges risk of

EPFL-LCH2016

JET experiments with tritium and deuterium-tritium mixtures

Henri Weisen, Javier García Hernández

Extensive preparations are now underway for an experiment in the Joint European Torus QET) using tritium and deuterium tritium mixtures. The goals of this experiment are described as well as the progress that has been made in developing plasma operational ...

Elsevier Science Sa2016

ELM frequency feedback control on JET

Jonathan Graves

This paper describes the first development and implementation of a closed loop edge localized mode (ELM) frequency controller using gas injection as the actuator. The controller has been extensively used in recent experiments on JET and it has proved to wo ...

IOP Publishing Ltd2015

Absolute and convective instabilities of heated coaxial jet flow

Gioele Mariano Nicolò Balestra

This study investigates the inviscid, linear spatio-temporal stability of heated, compressible, and incompressible coaxial jet flows. The influence of the temperature ratio and the velocity ratio between the core jet and the bypass stream on the transition ...

Amer Inst Physics2015

Influence of air entrainment on rock scour development and block stability in plunge pools

Rock scour occurring near dam foundations due to high-velocity jets of spillways impinging into the plunge pool is a major concern regarding dam safety. Scour in fractured rock resulting from high-velocity jet impact is a complex phenomenon, which involves the three phases: water, air and rock. Since 1998, the Laboratory of Hydraulic Constructions (LCH) of the Ecole Polytechnique Fédérale de Lausanne (EPFL) is conducting research in order to better understand the physical processes that contribute to rock s

EPFL - LCH2014

The Scientific Case for a JET D-T Experiment

Henri Weisen

After the first high power D-T experiment in JET in 1997 (DTE1), when JET was equipped with Carbon PFC's, a proposed second high power (up to similar to 40MW) D-T campaign (DTE2) in the current Be/W vessel will address essential operational, technical, dia ...

Amer Inst Physics2014

Air concentrations in plunge pools due to aerated plunging high-velocity jets and dynamic pressures in underlying fissures

High-velocity plunging water jets, such as those formed by spillways of high-head dams, cause scour on the rock foundations. The scour process is the result of complex physical phenomena concerning the three media involved, namely, water, rock and air. Air is entrained in the jet during the travel through the air and at the impinging point into the plunge pool. The air bubbles flow in the plunge pool influence energy dissipation and dynamic pressures. The bubbles may also enter rock fissures, where they wil

TPI2013

Scour formation due to simultaneous circular impinging jet and wall jet

Anton Schleiss

Experiments involving both a circular wall jet and an impinging jet were conducted, as occurring at irrigation control structures or at dams with combined crest and low-level spillways. The effects of the non-dimensional parameters on the scour hole dimensions have been investigated. It was found that the effect of the expansion ratio of the channel width to the jet diameter is negligible for values larger than 22.5 and 35, depending on the experimental conditions. The scour depth decreases with increasing

Taylor & Francis Ltd2012

Deflector-jets affected by pre-aerated approach flow

Jets generated at chute ends move a potential scour zone away from the dam, and dissipate flow energy to reduce the scour. Usually, so-called flip buckets or ski jumps are provided to generate jets, yet they are rarely issued by deflectors. The application of a theoretical mass point parabola is limited to predict the jet features, because effects related to the take-off angle and the disintegration process affect the jet air transport and trajectories. This research discusses the effect of pre-aeration of

Taylor & Francis Ltd2012

Dynamic Pressures around a Confined Block Impacted by Plunging Aerated High-Velocity Jets

Anton Schleiss, Erik Bollaert

The impingement of high-velocity water jets on unlined plunge pools causes scour on the rock foundations. The scour process is the result of complex physical phenomena that happen consecutively. Turbulence and dynamic pressures play a major role, especially in the jet development during air travel, in the diffusion process in the pool, in the pressure fluctuations in the water-rock interface and in the pressure propagation inside rock fissures. Air entrainment significantly influences the whole process. Air

2012

Influence of a circular jet arrangement in a rectangular tank on flow and suspended sediment release

Jolanda Maria Isabella Jenzer Althaus

With the objective of high sediment release out of a rectangular tank the performance of a circular jet arrangement has been investigated. Therefore, experiments with four jets arranged in a horizontal circle placed in water with quasi homogeneous sediment concentration were conducted. The induced circulation was analysed by measuring the flow field. The influence of the flow circulation on suspension and on sediment release through the water intake was studied and discussed. The offbottom clearance of the

2011

Experimental study on Scour due to simultaneous wall and impinging circular jet

Anton Schleiss

In this study the scour mechanism and the effect of some of the important parameters such as jet velocities, impinging jet distance from the upstream wall and tailwater depth on the longitudinal scour profile due to 3d simoultaneous wall and impinging jet are investigated experimentally. Experiments were conducted in a channel 10 m long, 1 m height and 0.57 m width. For generating jet flow, two pipes with 1 cm inside diameter and 2 m long were used. Uniform sediment with median size of 1.05 mm was used as t

2011

Fine Sediment release from a reservoir by controlled hydrodynamic mixing

Anton Schleiss, Giovanni De Cesare, Jolanda Maria Isabella Jenzer Althaus

Reservoir sedimentation is worldwide a problem and requires a sustainable solution. The idea of maintaining sediment in suspension by a jet induced artificial turbulence and releasing it through the water intake was tested in laboratory experiments. Therefore, two jet configurations and the influence of their geometrical parameters and the jet discharge on the sediment release were investigated: (i) a circular jet configuration with four jets arranged in a circle on a horizontal plane and (ii) a linear jet

2011

Helical core tokamak MHD equilibrium states

Olivier Sauter, Basil Duval, Stefano Coda, Jonathan Graves, Wilfred Anthony Cooper, Holger Reimerdes, Benoît Labit, Antoine Pochelon, Jonathan Rossel, Mattia Albergante

Bifurcated magnetohydrodynamic tokamak equilibrium states with axisymmetric or helical core structure are computed. When a peaked pressure profile is chosen, the helical core structures appear like the {em snakes} that are observed in the JET tokamak. They ...

Caroline Wilkinson2011

Dynamic response of a rock block in a plunge pool due to asymmetrical impact of a high-velocity jet

Anton Schleiss, Erik Bollaert, Matteo Paolo Elia Antonio Federspiel

Flood release structures of high-head dams generate high-velocity plunging jets. These may scour the downstream rocky riverbed and even damage the dam foundation. Assessment of the scour evolution is essential to ensure the safety of the dam and appurtenant structures, as well as to guarantee the stability of its abutments.In the framework of a research project, near-prototype scaled experimental installation generating high-velocity jet impact in a plunge pool has been equipped with an artificial rock bloc

2011

Response of an embedded block impacted by high-velocity jets

Matteo Paolo Elia Antonio Federspiel

The safety of dams is very often endangered by the formation of scour near the foundation as a result of high-velocity jet impact. These jets issue from appurtenant structures such as spillways and may impact in the immediate vicinity of the dam toe. The process of rock scour is very complex and full physical understanding of the water-air-rock interaction is still lacking. With his PhD research Dr. Matteo Federspiel filled up a gap towards a better scientific understanding of the scouring process. For the

EPFL - LCH2011

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Publications associées (27)

Air concentrations in plunge pools due to aerated plunging high-velocity jets and dynamic pressures in underlying fissures

TPI2013