4,812 research outputs found
[Acoustic Levitation Methods and Apparatus]
Methods are described for acoustically levitating objects within chambers of spherical and cylindrical shape. The wavelengths for chambers of particular dimensions are given, for generating standing wave patterns of any of a variety of modes within the chambers. For a spherical chamber the lowest resonant mode is excited by applying a wavelength of 3.02R, where R is the chamber radius. The two lowest pure radial modes for that chamber, are excited by applying wavelengths of 1.40R and 0.814R. For a cylindrical chamber of radius R, the lowest mode is at a wavelength of 3.41R, and the lowest pure radial modes are at wavelengths of 1.64R and 0.896R
Acoustic particle separation
A method is described which uses acoustic energy to separate particles of different sizes, densities, or the like. The method includes applying acoustic energy resonant to a chamber containing a liquid of gaseous medium to set up a standing wave pattern that includes a force potential well wherein particles within the well are urged towards the center, or position of minimum force potential. A group of particles to be separated is placed in the chamber, while a non-acoustic force such as gravity is applied, so that the particles separate with the larger or denser particles moving away from the center of the well to a position near its edge and progressively smaller lighter particles moving progressively closer to the center of the well. Particles are removed from different positions within the well, so that particles are separated according to the positions they occupy in the well
Simulating the Thermal Behavior an Earth-Stationed Satellite Terminal
Lumped parameter modeling using finite differencing, form the basis for a C language simulation of a thermal system. The study of the earth-stationed satellite terminal includes an introduction to the system, derivation of the governing equation, development of a simulation, and a comparison of the results to empirical data.
The analysis is undertaken with emphasis on the worst-case thermal environment, and with determination of the cooling loads and transient response as primary goals. Comparing the predicted cooling loads to empirical data, and previous analyses, indicates an accurate simulation has been constructed. The computer models are offered as an alternative method in thermal design and analysis of electronic systems typical to the earth-stationed satellite terminal
The role of interference in metacognitive monitoring
Recent advancements in neuropsychology have initiated theoretical advancements in cognitive psychology, particularly concerning the constructs of interference and metacognition. These constructs share similar cognitive functioning and this study investigated the relationship between them. It was expected that students with higher monitoring ability would demonstrate lower susceptibility to interference. Students from undergraduate Educational Psychology classes were administered three tests: two measures of interference, and one measure of metacognitive monitoring ability. Variables from the Wisconsin Card Sort Test (WCST) and the Stroop Color and Word Test (SCWT) measured susceptibility to interference. A monitoring task applied to a math aptitude test was used to measure monitoring ability. Pearson-product correlations showed no relationship among the interference measures and monitoring ability. Furthermore, there was no relationship among the interference component: scores and monitoring ability. The results of this study are also inconsistent with previous research concerning monitoring and math score prediction. Results showed no difference between the monitoring and non-monitoring groups in ability to predict math scores
Jacobi multipliers, non-local symmetries and nonlinear oscillators
Constants of motion, Lagrangians and Hamiltonians admitted by a family of
relevant nonlinear oscillators are derived using a geometric formalism. The
theory of the Jacobi last multiplier allows us to find Lagrangian descriptions
and constants of the motion. An application of the jet bundle formulation of
symmetries of differential equations is presented in the second part of the
paper. After a short review of the general formalism, the particular case of
non-local symmetries is studied in detail by making use of an extended
formalism. The theory is related to some results previously obtained by
Krasil'shchi, Vinogradov and coworkers. Finally the existence of non-local
symmetries for such two nonlinear oscillators is proved.Comment: 20 page
From Lagrangian to Quantum Mechanics with Symmetries
We present an old and regretfully forgotten method by Jacobi which allows one
to find many Lagrangians of simple classical models and also of nonconservative
systems. We underline that the knowledge of Lie symmetries generates Jacobi
last multipliers and each of the latter yields a Lagrangian. Then it is shown
that Noether's theorem can identify among those Lagrangians the physical
Lagrangian(s) that will successfully lead to quantization. The preservation of
the Noether symmetries as Lie symmetries of the corresponding Schr\"odinger
equation is the key that takes classical mechanics into quantum mechanics.
Some examples are presented.Comment: To appear in: Proceedings of Symmetries in Science XV, Journal of
Physics: Conference Series, (2012
Calculating the Volume of Water Droplets on Topographically-Modified, Micro-Grooved Aluminum Surfaces
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