6,132 research outputs found
Evaluation of the thermal and hydraulic performances of a very thin sintered copper flat heat pipe for 3D microsystem packages
The reported research work presents numerical studies validated by
experimental results of a flat micro heat pipe with sintered copper wick
structure. The objectives of this project are to produce and demonstrate the
efficiency of the passive cooling technology (heat pipe) integrated in a very
thin electronic substrate that is a part of a multifunctional 3-D electronic
package. The enhanced technology is dedicated to the thermal management of high
dissipative microsystems having heat densities of more than 10W/cm2. Future
applications are envisaged in the avionics sector. In this research 2D
numerical hydraulic model has been developed to investigate the performance of
a very thin flat micro heat pipe with sintered copper wick structure, using
water as a refrigerant. Finite difference method has been used to develop the
model. The model has been used to determine the mass transfer and fluid flow in
order to evaluate the limits of heat transport capacity as functions of the
dimensions of the wick and the vapour space and for various copper spheres
radii. The results are presented in terms of liquid and vapour pressures within
the heat pipe. The simulated results are validated by experiments and proved
that the method can be further used to predict thermal performance of the heat
pipe and to optimise its design.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Design and fabrication of a radiative actively cooled honeycomb sandwich structural panel for a hypersonic aircraft
The panel assembly consisted of an external thermal protection system (metallic heat shields and insulation blankets) and an aluminum honeycomb structure. The structure was cooled to temperature 442K (300 F) by circulating a 60/40 mass solution of ethylene glycol and water through dee shaped coolant tubes nested in the honeycomb and adhesively bonded to the outer skin. Rene'41 heat shields were designed to sustain 5000 cycles of a uniform pressure of + or - 6.89kPa (+ or - 1.0 psi) and aerodynamic heating conditions equivalent to 136 kW sq m (12 Btu sq ft sec) to a 422K (300 F) surface temperature. High temperature flexible insulation blankets were encased in stainless steel foil to protect them from moisture and other potential contaminates. The aluminum actively cooled honeycomb sandwich structural panel was designed to sustain 5000 cycles of cyclic in-plane loading of + or - 210 kN/m (+ or - 1200 lbf/in.) combined with a uniform panel pressure of + or - 6.89 kPa (?1.0 psi)
Supersonic flutter of a thermally stressed flat panel with uniform edge loads
Supersonic flutter of thermally stressed flat panel with uniform edge load
Scaling in Gravitational Clustering, 2D and 3D Dynamics
Perturbation Theory (PT) applied to a cosmological density field with
Gaussian initial fluctuations suggests a specific hierarchy for the correlation
functions when the variance is small. In particular quantitative predictions
have been made for the moments and the shape of the one-point probability
distribution function (PDF) of the top-hat smoothed density. In this paper we
perform a series of systematic checks of these predictions against N-body
computations both in 2D and 3D with a wide range of featureless power spectra.
In agreement with previous studies, we found that the reconstructed PDF-s work
remarkably well down to very low probabilities, even when the variance
approaches unity. Our results for 2D reproduce the features for the 3D
dynamics. In particular we found that the PT predictions are more accurate for
spectra with less power on small scales. The nonlinear regime has been explored
with various tools, PDF-s, moments and Void Probability Function (VPF). These
studies have been done with unprecedented dynamical range, especially for the
2D case, allowing in particular more robust determinations of the asymptotic
behaviour of the VPF. We have also introduced a new method to determine the
moments based on the factorial moments. Results using this method and taking
into account the finite volume effects are presented.Comment: 13 pages, Latex file, 9 Postscript Figure
The First-Order Theory of Binary Overlap-Free Words is Decidable
We show that the first-order logical theory of the binary overlap-free words
(and, more generally, the -free words for rational , ), is decidable. As a consequence, many results previously
obtained about this class through tedious case- based proofs can now be proved
"automatically", using a decision procedure
A dataset of continuous affect annotations and physiological signals for emotion analysis
From a computational viewpoint, emotions continue to be intriguingly hard to
understand. In research, direct, real-time inspection in realistic settings is
not possible. Discrete, indirect, post-hoc recordings are therefore the norm.
As a result, proper emotion assessment remains a problematic issue. The
Continuously Annotated Signals of Emotion (CASE) dataset provides a solution as
it focusses on real-time continuous annotation of emotions, as experienced by
the participants, while watching various videos. For this purpose, a novel,
intuitive joystick-based annotation interface was developed, that allowed for
simultaneous reporting of valence and arousal, that are instead often annotated
independently. In parallel, eight high quality, synchronized physiological
recordings (1000 Hz, 16-bit ADC) were made of ECG, BVP, EMG (3x), GSR (or EDA),
respiration and skin temperature. The dataset consists of the physiological and
annotation data from 30 participants, 15 male and 15 female, who watched
several validated video-stimuli. The validity of the emotion induction, as
exemplified by the annotation and physiological data, is also presented.Comment: Dataset available at:
https://rmc.dlr.de/download/CASE_dataset/CASE_dataset.zi
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