28,295 research outputs found
Development of an optimized intumescent coating
Intumescent coatings for small diameter air launched missiles were studied. An aerodynamically smooth, moderately flexible coating, with excellent thermal efficiency was developed
Development of thermal stratification and destratification scaling concepts. Volume 1: Definition of thermal stratification scaling parameters and experimental investigations
The dimensionless parameters associated with the thermal stratification and pressure history of a heated container of liquid and its vapor were examined. The Modified Grashof number, the Fourier number, and an Interface number were parameterized using a single test liquid, Freon 113. Cylindrical test tanks with spherical dome end caps were built. Blanket heaters covered the tanks and thermocouples monitored the temperatures of the liquid, the ullage, the tank walls, and the foam insulation encapsulating the tank. A centrifuge was used for the 6 inch tank to preserve the same scaling parameter values between it and the larger tanks. Tests were conducted over a range of Gr* values and the degree of scaling was checked by comparing the dimensionless pressures and temperatures for each scaled pair of tests. Results indicate that the bulk liquid temperature, the surface temperature of the liquid, and the tank pressure can be scaled with the three dimensionless parameters. Some deviation was, however, found in the detailed temperature profiles between the scaled pairs of tests
A characterization of quasi-rational polygons
The aim of this paper is to study quasi-rational polygons related to the
outer billiard. We compare different notions introduced, and make a synthesis
of those.Comment: 15 pages, 9 figure
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What does the future hold for utility electricity efficiency programs?
This study develops projections of future spending and savings from electricity efficiency programs funded by electric utility customers in the United States through 2030 based on three scenarios. Our analysis relies on detailed bottom-up modeling of current state energy efficiency policies, demand-side management and integrated resource plans, and regulatory decisions. The three scenarios represent a range of potential outcomes given the policy environment at the time of the study and uncertainties in the broader economic and state policy environment in each state. We project spending to increase to 11.1 billion in 2030 and remains relatively flat in the low case ($6.8 billion in 2030). Our analysis suggests that electricity efficiency programs funded by utility customers will continue to impact load growth significantly at least through 2030, as savings as a percent of retail sales are forecast at 0.7 percent in the medium scenario and 0.98 percent in the high scenario
Integrating EEG and MEG signals to improve motor imagery classification in brain-computer interfaces
We propose a fusion approach that combines features from simultaneously
recorded electroencephalographic (EEG) and magnetoencephalographic (MEG)
signals to improve classification performances in motor imagery-based
brain-computer interfaces (BCIs). We applied our approach to a group of 15
healthy subjects and found a significant classification performance enhancement
as compared to standard single-modality approaches in the alpha and beta bands.
Taken together, our findings demonstrate the advantage of considering
multimodal approaches as complementary tools for improving the impact of
non-invasive BCIs
Numerical simulation of exciton dynamics in Cu2O at ultra low temperatures within a potential trap
We have studied theoretically the relaxation behaviour of excitons in cuprous
oxide (Cu2O) at ultra low temperatures when excitons are confined within a
potential trap by solving numerically the Boltzmann equation. As relaxation
processes, we have included in this paper deformation potential phonon
scattering, radiative and non-radiative decay and Auger decay. The relaxation
kinetics has been analysed for temperatures in the range between 0.3K and 5K.
Under the action of deformation potential phonon scattering only, we find for
temperatures above 0.5K that the excitons reach local equilibrium with the
lattice i.e. that the effective local temperature is coming down to bath
temperature, while below 0.5K a non-thermal energy distribution remains.
Interestingly, for all temperatures the global spatial distribution of excitons
does not reach the equilibrium distribution, but stays at a much higher
effective temperature. If we include further a finite lifetime of the excitons
and the two-particle Auger decay, we find that both the local and the global
effective temperature are not coming down to bath temperature. In the first
case we find a Bose-Einstein condensation (BEC) to occur for all temperatures
in the investigated range. Comparing our results with the thermal equilibrium
case, we find that BEC occurs for a significantly higher number of excitons in
the trap. This effect could be related to the higher global temperature, which
requires an increased number of excitons within the trap to observe the BEC. In
case of Auger decay, we do not find at any temperature a BEC due to the heating
of the exciton gas
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