482 research outputs found

    Quantifying fusion born ion populations in magnetically confined plasmas using ion cyclotron emission

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    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 PICEP_{ICE} scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, nα/nin_\alpha/n_i, 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 Caballería de Sevilla. Sobre la Geometría de su Planta

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    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 características más llamativas de la Plaza de la Real Maestranza de Caballería 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 geometría irregular. Un razonamiento basado en la historia de su construcción, también en la observación tanto de la planimetría 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

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    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

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    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

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    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

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    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

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    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

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    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

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    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.

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    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 desafío 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 metodología 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 características 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 desafío r= .415 ** con el compromiso con un valor de r= .323 ** y el control con las características 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 desafíos
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