247 research outputs found
Non regression testing for the JOREK code
Non Regression Testing (NRT) aims to check if software modifications result
in undesired behaviour. Suppose the behaviour of the application previously
known, this kind of test makes it possible to identify an eventual regression,
a bug. Improving and tuning a parallel code can be a time-consuming and
difficult task, especially whenever people from different scientific fields
interact closely. The JOREK code aims at investing Magnetohydrodynamic (MHD)
instabilities in a Tokamak plasma. This paper describes the NRT procedure that
has been tuned for this simulation code. Automation of the NRT is one keypoint
to keeping the code healthy in a source code repository.Comment: No. RR-8134 (2012
Extended Magnetic Dome Induced by Low Pressures in Superconducting FeSeS
We report muon spin rotation (SR) and magnetization measurements under
pressure on FeSeS with x
.Above GPa we find microscopic coexistence of
superconductivity with an extended dome of long range magnetic order that spans
a pressure range between previously reported separated magnetic phases. The
magnetism initially competes on an atomic scale with the coexisting
superconductivity leading to a local maximum and minimum of the superconducting
. The maximum of corresponds to the onset of
magnetism while the minimum coincides with the pressure of strongest
competition. A shift of the maximum of for a series of single
crystals with x up to 0.14 roughly extrapolates to a putative magnetic and
superconducting state at ambient pressure for x .Comment: 10 pages, 6 figures, including supplemental materia
Sustainable management of scab control through the integration of apple resistant cultivars in a low-fungicide input system
Evaluation of the sustainability of disease control strategies through experimental field studies is poorly documented. Plant genetic resistance to pathogens offers an interesting alternative to the use of pesticides, but pathogen populations are able to adapt, thus frequently resulting in the breakdown of the resistance. Partial resistance is considered to provide more durable resistance than major genes. However, partial resistance does not confer complete protection and its efficiency can also decrease. Developing appropriate strategies which integrate resistant cultivars into crop systems is therefore needed to increase the efficiency and durability of the resistance, whatever the kind of resistance. The aim of this study was to evaluate the relevance of the association of control methods in terms of increasing the efficiency and durability of two kinds of resistances: (i) partial resistance in the apple cultivar Reine des Reinettes and (ii) major resistance (Rvi6) in the apple cultivar Ariane, when planted in a region where the climatic conditions are very favourable to the disease. It was found that the removal of leaf litter in autumn together with spraying of fungicides in the case of moderate or high risks of scab infection resulted in a sustainable control of scab on Reine des Reinettes over a five-year period and delayed the breakdown of the major resistance Rvi6 of Ariane by virulent isolates
Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations
The interaction of static Resonant Magnetic Perturbations (RMPs) with
the plasma flows is modeled in toroidal geometry, using the non-linear
resistive MHD code JOREK, which includes the X-point and the
scrape-off-layer. Two-fluid diamagnetic effects, the neoclassical
poloidal friction and a source of toroidal rotation are introduced in
the model to describe realistic plasma flows. RMP penetration is studied
taking self-consistently into account the effects of these flows and the
radial electric field evolution. JET-like, MAST, and ITER parameters are
used in modeling. For JET-like parameters, three regimes of plasma
response are found depending on the plasma resistivity and the
diamagnetic rotation: at high resistivity and slow rotation, the islands
generated by the RMPs at the edge resonant surfaces rotate in the ion
diamagnetic direction and their size oscillates. At faster rotation, the
generated islands are static and are more screened by the plasma. An
intermediate regime with static islands which slightly oscillate is
found at lower resistivity. In ITER simulations, the RMPs generate
static islands, which forms an ergodic layer at the very edge (ψ
≥0.96) characterized by lobe structures near the X-point and results
in a small strike point splitting on the divertor targets. In MAST
Double Null Divertor geometry, lobes are also found near the X-point and
the 3D-deformation of the density and temperature profiles is observed
Experimental and numerical study of chemiluminescence characteristics in premixed counterflow flames of methane based fuel blends
Non-intrusive chemiluminescence measurements have been used as heat release rate and equivalence ratio indicators for gas turbine combustor active control. In the present study, measurements and modelling of OH*, CH(A)*, C 2 *, and CO 2 * chemiluminescence are used to examine chemiluminescence sensing of heat release rate and equivalence ratio in premixed counterflow methane – air flames with equivalence ratio from 0.6 to 1.3 and strain rate from 80 to 400 s -1 . Two spectrally resolved detecting optical systems were used to detect spatially-averaged (global) and spatially resolved (local) chemiluminescence characteristics in the reaction zone. A recently published reaction mechanism 1 for the chemiluminescence of the OH*, CH*, and C 2 * species is incorporated to GRI-Mech 3.0. The augmented mechanism is further validated against the experimental results of the present study and is used to predict the chemiluminescence characteristics of premixed counterflow methane – air flames. The mechanism includes OH* chemiluminescence formation paths from hydrogen reaction, which have not been evaluated before in premixed counterflow flames. The CHEMKIN based counterflow flame code, OPPDIF is employed to simulate the experiments. The calculated OH* and CH(A)* chemiluminescence agrees well with the experimental results measured by both optical methods. Both the experimental and numerical results demonstrate the ability of OH* and CH(A)* intensities to mark heat release rate in methane – air flames. Overall, CH* may be preferable for heat release rate sensing applications at elevated equivalence ratio and strain rate. For equivalence ratio sensing in methane combustion, the measured and simulated OH*/CH(A)* chemiluminescent intensity ratio is highly dependent on equivalence ratio and nearly independent of strain rate. Thus, this ratio can be used to monitor equivalence ratio. However, a non-monotonic behavior of the OH*/CH* ratio for very lean combustion (ER < 0.7) is observed, in agreement with previous studies. This behavior can be reproduced by the reaction mechanisms. The behavior of OH*/CH(A)* chemiluminescent intensity ratio for flames of methanepropane blends are also calculated with the detailed chemistry model. The addition of propane in methane modifies the behaviour of OH*/CH(A)* chemiluminescent intensity ratio dramatically. However, the numerical results suggest that the OH*/CH(A)* chemiluminescent intensity ratio is an indicator of equivalence ratio in lean methanepropane fuel blended flames
Analysis of test beam data taken with a prototype of TPC with resistive Micromegas for the T2K Near Detector upgrade
In this paper we describe the performance of a prototype of the High Angle
Time Projection Chambers (HA-TPCs) that are being produced for the Near
Detector (ND280) upgrade of the T2K experiment. The two HA-TPCs of ND280 will
be instrumented with eight Encapsulated Resistive Anode Micromegas (ERAM) on
each endplate, thus constituting in total 32 ERAMs. This innovative technique
allows the detection of the charge emitted by ionization electrons over several
pads, improving the determination of the track position. The TPC prototype has
been equipped with the first ERAM module produced for T2K and with the HA-TPC
readout electronics chain and it has been exposed to the DESY Test Beam in
order to measure spatial and dE/dx resolution. In this paper we characterize
the performances of the ERAM and, for the first time, we compare them with a
newly developed simulation of the detector response. Spatial resolution better
than 800 and dE/dx resolution better than 10% are observed for
all the incident angles and for all the drift distances of interest. All the
main features of the data are correctly reproduced by the simulation and these
performances fully fulfill the requirements for the HA-TPCs of T2K
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