33,030 research outputs found
The scatter of mechanical values of carbon fiber composites and its causes
The scatter of experimental data obtained in an investigation of the parameters of structural components was investigated. Strength parameters which are determined by the resin or the adhesion between fiber and resin were included. The statistical characteristics of the mechanical parameters of carbon fiber composites, and the possibilities which exist to reduce this scatter were emphasized. It is found that quality control tests of fiber and resin are important for such a reduction
Thermal detector model for cryogenic composite detectors for the dark matter experiments CRESST and EURECA
The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers)
and the EURECA (European Underground Rare Event Calorimeter Array) experiments
are direct dark matter search experiments where cryogenic detectors are used to
detect spin-independent, coherent WIMP (Weakly Interacting Massive
Particle)-nucleon scattering events by means of the recoil energy. The
cryogenic detectors use a massive single crystal as absorber which is equipped
with a TES (transition edge sensor) for signal read-out. They are operated at
mK-temperatures. In order to enable a mass production of these detectors, as
needed for the EURECA experiment, a so-called composite detector design (CDD)
that allows decoupling of the TES fabrication from the optimization procedure
of the absorber single-crystal was developed and studied. To further
investigate, understand and optimize the performance of composite detectors a
detailed thermal detector model which takes into account the CDD has been
developed.Comment: To appear in Journal of Physics: Conference Series; Proceedings of
Neutrino 2008, Christchurch, New Zealan
Depletion potentials near geometrically structured substrates
Using the recently developed so-called White Bear version of Rosenfeld's
Fundamental Measure Theory we calculate the depletion potentials between a
hard-sphere colloidal particle in a solvent of small hard spheres and simple
models of geometrically structured substrates: a right-angled wedge or edge. In
the wedge geometry, there is a strong attraction beyond the corresponding one
near a planar wall that significantly influences the structure of colloidal
suspensions in wedges. In accordance with an experimental study, for the edge
geometry we find a free energy barrier of the order of several which
repels a big colloidal particle from the edge.Comment: 7 pages, 7 figure
Binary hard-sphere fluids near a hard wall
By using the Rosenfeld density functional we determine the number density
profiles of both components of binary hard-sphere fluids close to a planar hard
wall as well as the corresponding excess coverage and surface tension. The
comparison with published simulation data demonstrates that the Rosenfeld
functional, both its original version and sophistications thereof, is superior
to previous approaches and exhibits the same excellent accuracy as known from
studies of the corresponding one-component system
Light environment - A. Visible light. B. Ultraviolet light
Visible and ultraviolet light environment as related to human performance and safety during space mission
The dynamics of Machiavellian intelligence
The "Machiavellian intelligence" hypothesis (or the "social brain"
hypothesis) posits that large brains and distinctive cognitive abilities of
humans have evolved via intense social competition in which social competitors
developed increasingly sophisticated "Machiavellian" strategies as a means to
achieve higher social and reproductive success. Here we build a mathematical
model aiming to explore this hypothesis. In the model, genes control brains
which invent and learn strategies (memes) which are used by males to gain
advantage in competition for mates. We show that the dynamics of intelligence
has three distinct phases. During the dormant phase only newly invented memes
are present in the population. During the cognitive explosion phase the
population's meme count and the learning ability, cerebral capacity
(controlling the number of different memes that the brain can learn and use),
and Machiavellian fitness of individuals increase in a runaway fashion. During
the saturation phase natural selection resulting from the costs of having large
brains checks further increases in cognitive abilities. Overall, our results
suggest that the mechanisms underlying the "Machiavellian intelligence"
hypothesis can indeed result in the evolution of significant cognitive
abilities on the time scale of 10 to 20 thousand generations. We show that
cerebral capacity evolves faster and to a larger degree than learning ability.
Our model suggests that there may be a tendency toward a reduction in cognitive
abilities (driven by the costs of having a large brain) as the reproductive
advantage of having a large brain decreases and the exposure to memes increases
in modern societies.Comment: A revised version has been published by PNA
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