482 research outputs found
Quantifying fusion born ion populations in magnetically confined plasmas using ion cyclotron emission
Ion cyclotron emission (ICE) offers unique promise as a diagnostic of the
fusion born alpha-particle population in magnetically confined plasmas.
Pioneering observations from JET and TFTR found that ICE intensity
scales approximately linearly with the measured neutron flux from fusion
reactions, and with the inferred concentration, , of fusion-born
alpha-particles confined within the plasma. We present fully nonlinear
self-consistent kinetic simulations that reproduce this scaling for the first
time. This resolves a longstanding question in the physics of fusion
alpha-particle confinement and stability in MCF plasmas. It confirms the
magnetoacoustic cyclotron instability (MCI) as the likely emission mechanism
and greatly strengthens the basis for diagnostic exploitation of ICE in future
burning plasmas
La Traza Oculta de la Plaza de Toros de la Real Maestranza de CaballerÃa de Sevilla. Sobre la GeometrÃa de su Planta
Perhaps one of the most showy characteristics of the Bullring of the Real Maestranza de Caballeria of Seville is the singularity of its geometric layout, the irregularity of its arena. An unusual form to which no convincing justification has been found. There are no documents that explain it in the archives of the Corporation and there is no doubt about the solvency and dexterity of the major teachers, military engineers and architects who built it over a hundred and twenty years. Now, we think we have found an explanation for this irregular geometry. A reasoning based on the history of it construction, also in the observation of the historical and new planimetry, and especially in the knowledge that has provided us with the building of the works of reform and conservation carried out In it during these last years.Quizás una de las caracterÃsticas más llamativas de la Plaza de la Real Maestranza de CaballerÃa de Sevilla sea la singularidad de su traza, la irregularidad de su ruedo. Una forma insólita a la que no se ha encontrado justificación convincente. No existen documentos que la expliquen en los archivos de la Corporación y tampoco puede dudarse de la solvencia y destreza de los maestros mayores, ingenieros militares y arquitectos que a lo largo de ciento veinte años la levantaron. Ahora, creemos haber encontrado una explicación a esa geometrÃa irregular. Un razonamiento basado en la historia de su construcción, también en la observación tanto de la planimetrÃa histórica conservada como de los nuevos levantamientos, y sobre todo en el conocimiento que nos han proporcionado del edificio las obras de reforma y conservación llevadas a cabo en ella durante estos últimos años
cloud property retrieval using synergistic AATSR and MERIS observations
A newly developed daytime cloud property retrieval algorithm FAME-C (Freie
Universität Berlin AATSR MERIS Cloud) is presented. Synergistic observations
from AATSR and MERIS, both mounted on the polar orbiting satellite ENVISAT,
are used for cloud screening. For cloudy pixels two main steps are carried out
in a sequential form. First, a micro-physical cloud property retrieval is
performed using an AATSR near-infrared and visible channel. Cloud phase, cloud
optical thickness, and effective radius are retrieved, and subsequently cloud
water path is computed. Second, two independent cloud top height products are
retrieved. For cloud top temperature AATSR brightness temperatures are used,
while for cloud top pressure the MERIS oxygen-A absorption channel is used.
Results from the micro-physical retrieval serve as input for the two cloud top
height retrievals. Introduced are the AATSR and MERIS forward models and
auxiliary data needed in FAME-C. Also, the optimal estimation method with
uncertainty estimates, which also provides for uncertainty estimated of the
retrieved property on a pixel-basis, is presented. Within the frame of the ESA
Climate Change Initiative project first global cloud property retrievals have
been conducted for the years 2007–2009. For this time period verification
efforts are presented comparing FAME-C cloud micro-physical properties to
MODIS-TERRA derived cloud micro-physical properties for four selected regions
on the globe. The results show reasonable accuracies between the cloud micro-
physical retrievals. Biases are generally smallest for marine stratocumulus
clouds; −0.28, 0.41μm and −0.18 g m−2 for cloud optical thickness, effective
radius and cloud water path, respectively. This is also true for the root mean
square error. Also, both cloud top height products are compared to cloud top
heights derived from ground-based cloud radars located at several ARM sites.
FAME-C mostly shows an underestimation of cloud top heights when compared to
radar observations, which is partly attributed to the difficulty of accurate
cloud property retrievals for optically thin clouds and multi-layer clouds.
The bias is smallest, −0.9 km, for AATSR derived cloud top heights for single-
layer clouds
Exploiting the sensitivity of two satellite cloud height retrievals to cloud vertical distribution
This work presents a study on the sensitivity of two satellite cloud height
retrievals to cloud vertical distribution. The difference in sensitivity is
exploited by relating the difference in the retrieved cloud heights to cloud
vertical extent. The two cloud height retrievals, performed within the Freie
Universität Berlin AATSR MERIS Cloud (FAME-C) algorithm, are based on
independent measurements and different retrieval techniques. First, cloud top
temperature (CTT) is retrieved from Advanced Along Track Scanning Radiometer
(AATSR) measurements in the thermal infrared. Second, cloud top pressure (CTP)
is retrieved from Medium Resolution Imaging Spectrometer (MERIS) measurements
in the oxygen-A absorption band. Both CTT and CTP are converted to cloud top
height (CTH) using atmospheric profiles from a numerical weather prediction
model. A sensitivity study using radiative transfer simulations in the near-
infrared and thermal infrared were performed to demonstrate the larger impact
of the assumed cloud vertical extinction profile on MERIS than on AATSR top-
of-atmosphere measurements. The difference in retrieved CTH (ΔCTH) from AATSR
and MERIS are related to cloud vertical extent (CVE) as observed by ground-
based lidar and radar at three ARM sites. To increase the impact of the cloud
vertical extinction profile on the MERIS-CTP retrievals, single-layer and
geometrically thin clouds are assumed in the forward model. The results of the
comparison to the ground-based observations were separated into single-layer
and multi-layer cloud cases. Analogous to previous findings, the MERIS-CTP
retrievals appear to be close to pressure levels in the middle of the cloud.
Assuming a linear relationship, the ΔCTH multiplied by 2.5 gives an estimate
on the CVE for single-layer clouds. The relationship is weaker for multi-layer
clouds. Due to large variations of cloud vertical extinction profiles
occurring in nature, a quantitative estimate of the cloud vertical extent is
accompanied with large uncertainties. Yet, estimates of the CVE can contribute
to the characterization of a cloudy scene. To demonstrate the plausibility of
the approach, an estimate of the CVE was applied to a case study. In light of
the follow-up mission Sentinel-3 with AATSR and MERIS like instruments, Sea
and Land Surface Temperature Radiometer (SLSTR) and (Ocean and Land Colour
Instrument) OLCI, respectively, for which the FAME-C algorithm can be easily
adapted, a more accurate estimate of the CVE can be expected. OLCI will have
three channels in the oxygen-A absorption band, thus providing more pieces of
information on the cloud vertical extinction profile
Like-charge attraction through hydrodynamic interaction
We demonstrate that the attractive interaction measured between like-charged
colloidal spheres near a wall can be accounted for by a nonequilibrium
hydrodynamic effect. We present both analytical results and Brownian dynamics
simulations which quantitatively capture the one-wall experiments of Larsen and
Grier (Nature 385, p. 230, 1997).Comment: 10 pages, 4 figure
Anomalous interactions in confined charge-stabilized colloid
Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are
supposed to repel each other. Consequently, experimental evidence for anomalous
long-ranged like-charged attractions induced by geometric confinement inspired
a burst of activity. This has largely subsided because of nagging doubts
regarding the experiments' reliability and interpretation. We describe a new
class of thermodynamically self-consistent colloidal interaction measurements
that confirm the appearance of pairwise attractions among colloidal spheres
confined by one or two bounding walls. In addition to supporting previous
claims for this as-yet unexplained effect, these measurements also cast new
light on its mechanism.Comment: 8 pages, 5 figures, RevTeX4. Conference proceedings for CODEF-04,
Colloidal Dispersions in External Fields, March 29 - April 1, 200
On the nature of long-range contributions to pair interactions between charged colloids in two dimensions
We perform a detailed analysis of solutions of the inverse problem applied to
experimentally measured two-dimensional radial distribution functions for
highly charged latex dispersions. The experiments are carried out at high
colloidal densities and under low-salt conditions. At the highest studied
densities, the extracted effective pair potentials contain long-range
attractive part. At the same time, we find that for the best distribution
functions available the range of stability of the solutions is limited by the
nearest neighbour distance between the colloidal particles. Moreover, the
measured pair distribution functions can be explained by purely repulsive pair
potentials contained in the stable part of the solution.Comment: 6 pages, 5 figure
3D printed scaled setup for smoke transport analysis in a subterranean passenger platform
In this work, the study of smoke fire transportation inside of a subway passenger platform is presented. The study includes a set of numerical simulations to observe the behavior of the smoke inside the platform. Two smoke transport simulations using the FDS program are also included. Subsequently, the development of a 3D - 1:100 scale model is described and it was used to perform an experimental observation of the phenomenon. The model was built by using a 3D printer which allowed to include more architectural details of the real scenario. The inclusion of these details allowed to observe qualitative similarity between the results of the simulation and the experimental work. Although there are clear differences between what could happen in a real scenario and what was observed in the scale model, it was identified that the model is an important complement to the simulations. In addition to the simulations, the use of this type of 3D models allows the observation of the phenomenon by different specialists such as firefighters, policeman, medical personnel, etc., in the same place and its intention is to provide a more interactive tool to the observation group, increasing the time devoted to the development of contingency actions and reducing the costs associated with the logistics of a real simulacrum. The model allows to better identify the strengths, opportunities, weaknesses and threats of the contingency procedures developed by the safety and hygiene groups and to make their corresponding adjustments if necessary.Peer Reviewe
Application of non-linear techniques for daily weather data reconstruction and downscaling coarse climate data for local predictions
Downscaling techniques aim at resolving the scale discrepancy between climate change scenarios and the resolution demanded for impact assessments. Requirements for downscaled climate, to be useful for end users, include reliable representation of precipitation intensities, temporal and spatial variability, and physical parameters consistency. This report summarizes the results of the proof of concept phase in the development and testing of a novel data reconstruction method and a downscaling algorithm based on the multiplicative random cascade disaggregation method using rainfall signals at different spatial and temporal resolutions. The Wavelet Transformed-based Multi-Resolution Analysis (WT-MRA) was used for reconstructing the historical daily rainfall data needed as input for the downscaling methodology, using satellite-derived proxy data. Comparisons with presently used software showed that in all the cases; that is, the reconstructed, generated daily or downscaled daily data, the products developed outperformed the control test by either generating more accurate outcomes or by demanding significantly less parameterizing data
El impacto del contexto social sobre la personalidad resistente en deportistas universitarios de México.
Los objetivos de este estudio fueron identificar los factores de contexto social que más influyen sobre la personalidad resistente (PR), y además encontrar los factores del contexto social que mejor se relacionan con el control del compromiso y desafÃo de la personalidad resistente. Participo un grupo de 174 deportistas universitarios de 16 diferentes deportes, que compitieron en la Universiada Nacional 2017, en Monterrey, Nuevo León (México). Los instrumentos que se utilizaron fueron dos: el cuestionario sobre Percepción de Factores relacionados con la Excelencia en el Deporte (PFED) y el cuestionario de Personalidad Resistente en Deportistas Centroamericanos y del Caribe (PRDCC). La metodologÃa que se utilizó fue un diseño transversal, correlacional causal, de tipo no experimental. Los resultados mostraron que el factor del contexto social de mayor influencia sobre la personalidad resistente total son la naturaleza del entrenamiento (β = 3.21; p< .01) y las caracterÃsticas del entrenamiento (β = 3.80; p< .01) , además de que ambas predicen los factores de control (β = 3.83, β = 3.81; p< .01) y compromiso (β = 3.89, β = 3.67; p< .01). En las correlaciones se encontró que la naturaleza del entrenamiento tiene una relación con el desafÃo r= .415 ** con el compromiso con un valor de r= .323 ** y el control con las caracterÃsticas del entrenamiento con un valor de r=288 ** y la naturaleza del entrenamiento de manera global correlaciono con la PR total con un valor de r= 382 **.Por lo tanto, se concluye que el entrenador, los gestores administrativos y el equipo multidisciplinario impactan el desarrollo deportivo y promueven el compromiso y el gusto por los desafÃos
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