Differential temperature cryogenic liquid level sensing system Final report

Differential temperature cryogenic liquid level sensing system design and developmen

Substrate influence on the plasmonic response of clusters of spherical nanoparticles

The plasmonic response of nanoparticles is exploited in many subfields of science and engineering to enhance optical signals associated with probes of nanoscale and subnanoscale entities. We develop a numerical algorithm based on previous theoretical work that addresses the influence of a substrate on the plasmonic response of collections of nanoparticles of spherical shape. Our method is a real space approach within the quasi-static limit that can be applied to a wide range of structures. We illustrate the role of the substrate through numerical calculations that explore single nanospheres and nanosphere dimers fabricated from either a Drude model metal or from silver on dielectric substrates, and from dielectric spheres on silver substrates.Comment: 12 pages, 13 figure

Ancient Cosmic Dust from Triassic Halite

We describe the discovery of fossil micrometeorites in ancient Triassic rock salt; the first to be found in salt and the oldest complete micrometeorites found to date. We present an estimated flux rate of micrometeorites to Earth at this time

Modelling of Electroluminescence in Polymers Using a Bipolar Charge Transport Model

Electroluminescence (EL) in polymeric materials is thought to occur due to the energy dissipation process from the recombination of opposite polarity charge carriers. It is considered as an indication of storage and transport of charge carriers in cable insulation subject to electrical stresses and may indicate the change in charge movement due to aging or degradation processes. Under ac electric fields, the interaction of opposite polarity charge carriers at the interface of polymer/conductor is enhanced compared with dc conditions, and seems to contribute a lot to the electroluminescence rather than the charge behaviours in the bulk of polymers. The dynamics of charge carriers both at the interface of polymer/conductor and in the bulk of polymers is investigated through a simulation work using a bipolar charge transport model. Figure 1 compares experimental electroluminescence results with simulated data from the recombination of injected charge carriers. The paper will give more details on EL model and comparison under various waveforms and frequencies

Applications of acoustics in the measurement of coal slab thickness

The determination of the possibility of employing acoustic waves at ultrasonic frequencies for measurements of thicknesses of slabs of coal backed by shale is investigated. Fundamental information concerning the acoustical properties of coal, and the relationship between these properties and the structural and compositional parameters used to characterize coal samples was also sought. The testing device, which utilizes two matched transducers, is described

Ferromagnetic relaxation by magnon-induced currents

A theory for calculating spin wave relaxation times based on the magnon-electron interaction is developed. The theory incorporates a thin film geometry and is valid for a large range of magnon frequencies and wave vectors. For high conductivity metals such as permalloy, the wave vector dependent damping constant approaches values as high as 0.2, showing the large magnitude of the effect, and can dominate experimentally observed relaxation.Comment: 5 pages, 4 figure

Ellipsoidally Referenced Surveys: Issues and Solutions

One of the most significant issues in hydrography today is the use of the ellipsoid as a vertical reference for surveying measurements. High-accuracy GPS is used to vertically position hydrographic data collection platforms, relating bathymetric observations directly to the ellipsoid. Models are used to translate those observations to another datum. The use of high-accuracy vertical GPS and translation models to replace traditional tidal correctors is relatively new to the hydrographic community and, as such, requires some discussion. Even though individual components of the process are well understood in their particular field, it is their amalgamation and application to hydrography that requires explanation, clarification and evaluation.Many hydrographic organizations around the world are using Global Navigation Satellite Systems (GNSS) derived heights in their data collection and processing stream. The International Federation of Surveyors (FIG) has recognized the importance of these new developments and has established a new working group under Commission 4, tasked to developing best practices for Ellipsoidally Referenced Surveys (ERS). Over twenty groups from academia, industry and government who are engaged in some form of ERS have provided the working group with a summary of their practices and experiences. This paper outlines the issues related to ERS and summarizes the solutions being employed.Uno de los temas más significativos en la hidrografía actual es el uso del elipsoide como referencia vertical para las medidas hidrográficas. El GPS de alta precisión se utiliza para posicionar verticalmente las plataformas para la recogida de datos hidrográficos, relacionando las observaciones batimétricas directamente al elipsoide. Se utilizan modelos para traducir esas observaciones a otro plano de referencia. El uso de un GPS vertical de alta precisión y de modelos de traducción para sustituir a los correctores de mareas tradicionales es relativamente nuevo para la comunidad hidrográfica y, como tal, requiere una cierta discusión. Aunque se entienden bien las componentes individuales del proceso en su campo particular, lo que requiere una explicación, una aclaración y una evaluación es su amalgama y su aplicación a la hidrografía.Muchas organizaciones hidrográficas del mundo entero están utilizando en la recogida y el flujo de tratamiento de sus datos las alturas derivadas mediante los Sistemas Mundiales de Navegación por Satélite (GNSS). La Federación Internacional de Geodestas (FIG) ha reconocido la importancia de estos nuevos desarrollos y ha creado un nuevo grupo de trabajo en la Comisión 4, a la que se ha atribuido la tarea de desarrollar las mejores prácticas para los Levantamientos Referenciados Elipsoidalmente (ERS). Más de veinte grupos de la enseñanza, la industria y el gobierno, que están implicados en alguna forma de ERS, han proporcionado al grupo de trabajo un resumen de sus prácticas y experiencias. Este artículo destaca los temas relativos a los ERS y resume las soluciones que se están empleando.Une des questions les plus importantes en hydrographie aujourd‘hui est l‘utilisation de l‘ellipsoïde comme référence verticale pour le mesurage des levés. Le GPS à haute précision est utilisé pour positionner verticalement les plates formes de collecte des données hydrographiques, rapportant les observations bathymétriques directement à l‘ellipsoïde. Les modèles sont utilisés pour convertir ces observations dans un autre système. L‘utilisation du GPS vertical à haute précision et des modèles de conversion pour remplacer les correcteurs de marée traditionnels est relativement nouvelle pour la communauté hydrographique et, en tant que telle, nécessite une certaine discussion. Même si les composantes individuelles du processus sont bien comprises dans leur domaine spécifique, c‘est leur fusion et leur application à l‘hydrographie qui nécessite des explications, des éclaircissements et une évaluation.De nombreux organismes hydrographiques dans le monde utilisent les hauteurs dérivées des systè-mes globaux de navigation par satellite (GNSS) dans leur collecte et flux de traitement des données. La Fédération internationale des géomètres (FIG) a reconnu l‘importance de ces nouveaux dévelop-pements et a établi un nouveau groupe de travail dans le cadre de la Commission 4, chargé de déve-lopper de meilleures pratiques pour l‘ERS (Ellipsoidally Referenced Survey). Plus de vingt groupes du milieu universitaire, de l‘industrie et du gouvernement engagés dans une quelconque forme d‘ERS ont fourni au groupe de travail un résumé de leurs pratiques et expériences. Cet article passe en revue les questions liées à l‘ERS et résume les solutions mises en oeuvre