2,107 research outputs found
An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor
Parallel heat flux calculations at the JET divertor have been based on the assumption that
all incoming heat is due to the projection of the heat flux parallel to the magnetic line, q ,
plus a constant background. This simplification led to inconsistencies during the analysis of
a series of dedicated tungsten melting experiments performed in 2013, for which infrared
(IR) thermography surface measurements could not be recreated through simulations unless
the parallel heat flux was reduced by 80% for L-mode and 60% for H-mode. We give an
explanation for these differences using a new IR inverse analysis code, a set of geometrical
corrections, and most importantly an additional term for the divertor heat flux accounting for
non-parallel effects such as cross-field transport, recycled neutrals or charge exchange. This
component has been evaluated comparing four different geometries with impinging angles
varying from 2 to 90°. Its magnitude corresponds to 1.2%–1.9% of q , but because it is not
affected by the magnetic projection, it accounts for up to 20%–30% of the tile surface heat
flux. The geometrical corrections imply a further reduction of 24% of the measured heat
flux. In addition, the application of the new inverse code increases the accuracy of the tile
heat flux calculation, eliminating any previous discrepancy. The parallel heat flux computed
with this new model is actually much lower than previously deduced by inverse analysis of IR temperatures—40% for L-mode and 50% for H-mode—while being independent of
the geometry on which it is measured. This main result confirms the validity of the optical
projection as long as a non-constant and non-parallel component is considered. For a given
total heating power, the model predicts over 10% reduction of the maximum tile surface
heat flux compared to strict optical modelling, as well as a 30% reduced sensitivity to
manufacturing and assembling tolerances. These conclusions, along with the improvement in
the predictability of the divertor thermal behaviour, are critical for JET future DT operations,
and are also directly applicable to the design of the ITER divertor monoblocks.EURATOM 63305
On the Excitation and Formation of Circumstellar Fullerenes
We compare and analyze the Spitzer mid-infrared spectrum of three
fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds;
Tc1, SMP SMC16, and SMP LMC56. The three planetary nebulae share many
spectroscopic similarities. The strongest circumstellar emission bands
correspond to the infrared active vibrational modes of the fullerene species
C60 and little or no emission is present from Polycyclic Aromatic Hydrocarbons
(PAHs). The strength of the fullerene bands in the three planetary nebulae is
very similar, while the ratio of the [NeIII]15.5um/[NeII]12.8um fine structure
lines, an indicator of the strength of the radiation field, is markedly
different. This raises questions about their excitation mechanism and we
compare the fullerene emission to fluorescent and thermal models. In addition,
the spectra show other interesting and common features, most notably in the
6-9um region, where a broad plateau with substructure dominates the emission.
These features have previously been associated with mixtures of
aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this
band, which is likely related to the fullerene formation mechanism, and compare
it with modeled Hydrogenated Amorphous Carbon that present emission in this
region.Comment: 13 pages, 2 tables, 7 figures, Accepted for publication in Ap
Magnetic nanoparticles with bulk-like properties
The magnetic behavior of nanoparticles synthesized either by
high-temperature decomposition of an organic iron precursor or low-temperature
co-precipitation in aqueous conditions, is compared. Transmission electron
microscopy, X-ray absorption spectroscopy, X-ray magnetic circular dichroism
and magnetization measurements show that nanoparticles synthesized by thermal
decomposition display high crystal quality and bulk-like magnetic and
electronic properties, while nanoparticles synthesized by co-precipitation show
much poorer crystallinity and particle-like phenomenology, including reduced
magnetization, high closure fields and shifted hysteresis loops. The key role
of the crystal quality is thus suggested since particle-like behavior for
particles larger than about 5 nm is only observed when they are structurally
defective. These conclusions are supported by Monte Carlo simulations. It is
also shown that thermal decomposition is capable of producing nanoparticles
that, after further stabilization in physiological conditions, are suitable for
biomedical applications such as magnetic resonance imaging or bio-distribution
studies.Comment: Review article. 20 pages, 7 figures. Invited contribution to 55th MMM
Conference 2010 (Atlanta), Session HG-01. To be published in J. Appl. Phy
¿Existe relacion entre los parametros de composicion corporal y el riesgo de infección peritoneal (IP) en dialisis peritoneal (DP)?: estudio longitudinal
Resumen de comunicación ora
Addressing potential sources of variation in several non-destructive techniques for measuring firmness in apples
Measurements of firmness have traditionally been carried out according to the Magness Taylor (MT) procedure; using a texture analyser or penetrometer in reference texture tests. Non-destructive tests like the acoustic impulse response of acoustic firmness sensors (AFSs), a low-mass impact firmness sensor Sinclair International (SIQ-FT) and impact test (Lateral Impact – UPM) have also been used to measure texture and firmness. The objectives of this study were to evaluate the influence of different sources of variation in these three non-destructive tests and to evaluate their respective capabilities of discriminating between fruit maturity at two different harvest dates, turgidity before and after dehydration treatment and ripening after different storage periods. According to our results, fruit studied an unexpected AFS trend with turgidity. Contact measurements (Lateral Impact – UPM and SIQ-FT) appeared highly sensitive to changes in turgidity, but were less able to follow changes in ripening caused by storage period. Contact measurements were suitable for detecting differences between fruits from different harvest dates and showed higher correlation coefficients with reference texture tests than acoustic measurements. The Lateral Impact – UPM test proved better at separating fruits according to turgidity than the SIQ-FT instrumen
Sensors for product characterization and quality of specialty crops—A review
This review covers developments in non-invasive techniques for quality analysis and inspection of specialty
crops, mainly fresh fruits and vegetables, over the past decade up to the year 2010. Presented and
discussed in this review are advanced sensing technologies including computer vision, spectroscopy,
X-rays, magnetic resonance, mechanical contact, chemical sensing, wireless sensor networks and radiofrequency
identification sensors. The current status of different sensing systems is described in the
context of commercial application. The review also discusses future research needs and potentials of
these sensing technologies. Emphases are placed on those technologies that have been proven effective
or have shown great potential for agro-food applications. Despite significant progress in the development
of non-invasive techniques for quality assessment of fruits and vegetables, the pace for adoption of these
technologies by the specialty crop industry has been slow
El cerezo en España: situación e innovación tecnológica
En el presente artÃculo se expone una visión global de la producción de cereza en España, indicando las principales zonas de producción que siguen siendo Aragón y Extremadura. Las exportaciones suponen el 30% de la producción media nacional (110.000 t), siendo los principales destinos Reino Unido y Alemania. La mano de obra representa alrededor del 59% del coste total de producción. El calibre del fruto es el principal factor de calidad determinante del precio. La gama varietal disponible con variedades ya contrastadas es amplia y abarca desde la segunda semana de mayo con las variedades ‘Royal Tioga’ y ‘Nimba’, hasta principios de julio con ‘Stacatto’. Con respecto a los portainjertos Adara es el más plantado en la actualidad en sustitución de SL–64. Nuevas selecciones de las series ‘Corette®’ (Michigan State University, USA) y ‘GiSelA’ (CDB®, Alemania) se encuentran en fase de evaluación. En cuanto a sistemas de formación el vaso español constituye la referencia aunque el KGB es cada vez más utilizado, completado con sistemas planos o 2D.Creative Commons Attribution-NonCommercial-NoDerivs 3.0 SpainvariedadPublishe
- …