35,768 research outputs found
Coolant passage heat transfer with rotation
In current and advanced gas turbine engines, increased speeds, pressures and temperatures are used to reduce specific fuel consumption and increase thrust/weight ratios. Hence, the turbine airfoils are subjected to increased heat loads escalating the cooling requirements to satisfy life goals. The efficient use of cooling air requires that the details of local geometry and flow conditions be adequately modeled to predict local heat loads and the corresponding heat transfer coefficients. The objective of this program is to develop a heat transfer and pressure drop data base, computational fluid dynamic techniques and correlations for multi-pass rotating coolant passages with and without flow turbulators. The experimental effort is focused on the simulation of configurations and conditions expected in the blades of advanced aircraft high pressure turbines. With the use of this data base, the effects of Coriolis and buoyancy forces on the coolant side flow can be included in the design of turbine blades
Quantum radiation reaction force on a one-dimensional cavity with two relativistic moving mirrors
We consider a real massless scalar field inside a cavity with two moving
mirrors in a two-dimensional spacetime, satisfying Dirichlet boundary condition
at the instantaneous position of the boundaries, for arbitrary and relativistic
laws of motion. Considering vacuum as the initial field state, we obtain
formulas for the exact value of the energy density of the field and the quantum
force acting on the boundaries, which extend results found in previous papers.
For the particular cases of a cavity with just one moving boundary,
non-relativistic velocities, or in the limit of infinity length of the cavity
(a single mirror), our results coincide with those found in the literature.Comment: 6 pages 9 figure
Age-Associated Hyper-Methylated Regions in the Human Brain Overlap with Bivalent Chromatin Domains
PMCID: PMC3454416This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Effects of rotation on coolant passage heat transfer. Volume 1: Coolant passages with smooth walls
An experimental program was conducted to investigate heat transfer and pressure loss characteristics of rotating multipass passages, for configurations and dimensions typical of modern turbine blades. The immediate objective was the generation of a data base of heat transfer and pressure loss data required to develop heat transfer correlations and to assess computational fluid dynamic techniques for rotating coolant passages. Experiments were conducted in a smooth wall large scale heat transfer model
Optical Signatures of Spin-Orbit Interaction Effects in a Parabolic Quantum Dot
We demonstrate here that the dipole-allowed optical absorption spectrum of a
parabolic quantum dot subjected to an external magnetic field reflects the
inter-electron interaction effects when the spin-orbit interaction is also
taken into account. We have investigated the energy spectra and the
dipole-allowed transition energies for up to four interacting electrons
parabolically confined, and have uncovered several novel features in those
spectra that are solely due to the SO interaction.Comment: 4 pages, 3 figure
Exploring complex networks by walking on them
We carry out a comparative study on the problem for a walker searching on
several typical complex networks. The search efficiency is evaluated for
various strategies. Having no knowledge of the global properties of the
underlying networks and the optimal path between any two given nodes, it is
found that the best search strategy is the self-avoid random walk. The
preferentially self-avoid random walk does not help in improving the search
efficiency further. In return, topological information of the underlying
networks may be drawn by comparing the results of the different search
strategies.Comment: 5 pages, 5 figure
Current Switch by Coherent Trapping of Electrons in Quantum Dots
We propose a new transport mechanism through tunnel-coupled quantum dots
based on the coherent population trapping effect. Coupling to an excited level
by the coherent radiation of two microwaves can lead to an extremely narrow
current antiresonance. The effect can be used to determine interdot dephasing
rates and is a mechanism for a very sensitive, optically controlled current
switch.Comment: to appear in Phys. Rev. Let
Is there a “pandemic effect” on individuals' willingness to take genetic tests?
In this cross-sectional, semi-longitudinal and quasi-experimental study, our goal was to determine the effect of data storage conditions on willingness to take a genetic test. We compared individuals’ preferences regarding how they want to store health data collected from genetic tests through two survey experiments fielded in Switzerland in March 2020 and January 2022. We tested for differences whether genetic data are presented as private goods or public goods. Results confirm our initial research expectation: more control over storage increases willingness, so does framing genetic data as private good. However, they also show that the willingness to take a genetic test has noticeably increased between 2020 and 2022. Our results point toward a “pandemic effect” which would have increased willingness take a genetic test, nevertheless, more data are needed to understand this putative effect
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