1,081 research outputs found
Quine, Ontology, and Physicalism
Quine's views on ontology and naturalism are well-known but rarely considered in tandem. According to my interpretation the connection between them is vital. I read Quine as a global epistemic structuralist. Quine thought we only ever know objects qua solutions to puzzles about significant intersections in observations. Objects are always accessed descriptively, via their roles in our best theory. Quine's Kant lectures contain an early version of epistemic structuralism with uncharacteristic remarks about the mental. Here Quine embraces mitigated anomalous monism, allowing introspection and the availability in principle of full physical descriptions of the perceptual states which get science off the ground. Later versions abandon these ideas. My epistemic-structural interpretation explains why. I argue first-personal introspective access to mental states is incompatible with global epistemic structuralism
Origin of the excitonic recombinations in hexagonal boron nitride by spatially resolved cathodoluminescence spectroscopy
The excitonic recombinations in hexagonal boron nitride (hBN) are
investigated with spatially resolved cathodoluminescence spectroscopy in the UV
range. Cathodoluminescence images of an individual hBN crystallite reveals that
the 215 nm free excitonic line is quite homogeneously emitted along the
crystallite whereas the 220 nm and 227 nm excitonic emissions are located in
specific regions of the crystallite. Transmission electron microscopy images
show that these regions contain a high density of crystalline defects. This
suggests that both the 220 nm and 227 nm emissions are produced by the
recombination of excitons bound to structural defects
Near-field BLEVE overpressure effects: The shock start model
International audienceThis paper presents the results of a small scale experimental study of BLEVE overpressure effects. Testing consisted of a sealed aluminum tube (0.6 L) filled with either water or propane, being heated by a flame until the internal pressure led to catastrophic failure and explosion. Three parameters were controlled during the experiments: the failing pressure, the weakened length on the tube and the fill level. BLEVEs were obtained with tests involving water and propane. Blast gages and optical techniques were used to characterize the shock wave escaping from the failing tube. The results obtained suggest that the lead shock was primarily generated by the vapor space. Overpressure results obtained were compared with the predictions of existing models and found to be in reasonable agreement except for overpressures measured vertically above the cylinder where the overpressures were highest. A prediction model based on only vapor space characteristics was developed. Images show that the shock was fully formed at some distance away from the vessel opening and this was due to the non-ideal opening of the vessel. The model developed was based on the characteristics of the shock when fully formed away from the tube. These characteristics were defined using a combination of imaging, pressure measurements, and predictions from shock tube theory
Evolution of CODYRUN from Thermal Simulation to Coupled Thermal and Daylight Simulation Software
AbstractCODYRUN is a multi-zone software integrating thermal building simulation, airflow, and pollutant transfer. Described in numerous publications, this software was originally used for the passive design of buildings, both for research and teaching purposes. In this context, the data treated were mainly concerned with volumes (zones), surfaces and thicknesses (walls and windows), materials, and systems, with the aim to determine temperatures, heat fluxes, energy consumed, air transfers, and so on.The question thus arose as to the integration of indoor lighting conditions into the simulation. Hence, previous data structures had to be amended to incorporate the spatial positioning of entities (walls, windows, and artificial lighting sources) through vertexes. A set of procedures was also developed for polygons as well as calculating natural and artificial lighting.The results of this new daylighting module were then compared with other results of simulation codes and experimental cases both in artificial and natural environments. Excellent agreements were obtained, such as the values for luminous efficiencies in a tropical and humid climate.A simulation exercise was conducted in a classroom located in Reunion Island (French overseas territory in the Indian Ocean), thus confirming the interest for thermal and daylighting designs in low-energy buildings
F2TE3: sistema de cerramiento transparente, ligero, de altas prestaciones energéticas que permite el diseño con formas libres
We propose a new lightweight, slim, high energy efficient, light-transmitting envelope system using VIP technology, providing for seamless, free-form designs for use in architectural projects. The research is based on envelope components already existing on the market, especially components implemented with aerogel insulation, as this is the most effective translucent thermal insulation there is today. This research revealed that no other insulation has all the features required of the proposed new envelope model. Even so, some systems, namely, VIP technology, monolithic aerogel used for insulation purposes, and polymethyl methacrylate (PMMA) barriers, do have properties that could be exploited to generate this envelope. Using these design elements, data from tests and independent studies, we have defined a new, variable geometry, envelope insulation system with excellent energy-saving levels.Se plantea un nuevo sistema de cerramiento monocasco ligero, de espesor mínimo, de alta eficiencia energética, mediante la utilización de tecnología tipo VIP 1, con un alto grado de transmisión de la luz, que permite el diseño con formas libres, para su utilización en proyectos arquitectónicos. La investigación se basa en el estudio de los elementos de cerramiento existentes en el mercado, en especial los implementados con aerogel como aislamiento térmico, ya que se trata del aislante transparente que mejores prestaciones ofrece actualmente, y determina que ninguno otro sistema de aislamiento cumple todas las prestaciones que se buscan con el nuevo sistema propuesto. Aún así, de ellos se pueden extraer cualidades para generarlo: la tecnología VIP, el aerogel monolítico como material aislante, y el Polimetilmetacrilato como material de encapsulado. Estos elementos de diseño nos han permitido definir, junto con ensayos realizados, y datos de estudios independientes, un nuevo sistema de cerramiento de formas libres que ofrece altas prestaciones energéticas
Sawtooth period pacing and locking by EC power control on TCV
Abstract #TP9.127 submitted for the DPP11 Meeting of The American Physical Society
Hydrodynamics at RHIC -- how well does it work, where and how does it break down?
I review the successes and limitations of the ideal fluid dynamic model in
describing hadron emission spectra from Au+Au collisions at the Relativistic
Heavy Ion Collider (RHIC).Comment: 8 pages, 4 figures. Invited talk presented at Strange Quark Matter
2004 (Cape Town, Sep. 15-20, 2004). Proceedings to appear in Journal of
Physics
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