14,933 research outputs found

    Variable sweep aircraft Patent

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    Development and characteristics of variable sweep wing control system for supersonic aircraf

    Effects of Enamel Paint on the Behavior and Survival of the Periodical Cicada, \u3ci\u3eMagicicada Septendecim\u3c/i\u3e (Homoptera) and the Lesser Migratory Grasshopper, \u3ci\u3eMelanoplus Sanguinipes (Orthoptera).

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    We present information compiled from several studies on the effects of methods for marking individual arthropods on their longevity and behavior. Results from our own research on effects of enamel paint marking on two in- sect species, the periodical cicada, Magicicada septendecim, and the lesser migratory grasshopper, Melanoplus sanguinipes, are also presented. Neither species showed any adverse survivorship or behavioral effects from marking

    Dipolar Bose gases: Many-body versus mean-field description

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    We characterize zero-temperature dipolar Bose gases under external spherical confinement as a function of the dipole strength using the essentially exact many-body diffusion Monte Carlo (DMC) technique. We show that the DMC energies are reproduced accurately within a mean-field framework if the variation of the s-wave scattering length with the dipole strength is accounted for properly. Our calculations suggest stability diagrams and collapse mechanisms of dipolar Bose gases that differ significantly from those previously proposed in the literature

    The maximum density droplet to lower density droplet transition in quantum dots

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    We show that, Landau level mixing in two-dimensional quantum dot wave functions can be taken into account very effectively by multiplying the exact lowest Landau level wave functions by a Jastrow factor which is optimized by variance minimization. The comparison between exact diagonalization and fixed phase diffusion Monte Carlo results suggests that the phase of the many-body wave functions are not affected much by Landau level mixing. We apply these wave functions to study the transition from the maximum density droplet state (incipient integer quantum Hall state with angular momentum L=N(N-1)/2) to lower density droplet states (L>N(N-1)/2).Comment: 8 pages, 5 figures, accepted for publication in Phys. Rev.

    The Trapped Polarized Fermi Gas at Unitarity

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    We consider population-imbalanced two-component Fermi gases under external harmonic confinement interacting through short-range two-body potentials with diverging s-wave scattering length. Using the fixed-node diffusion Monte Carlo method, the energies of the "normal state" are determined as functions of the population-imbalance and the number of particles. The energies of the trapped system follow, to a good approximation, a universal curve even for fairly small systems. A simple parameterization of the universal curve is presented and related to the equation of state of the bulk system.Comment: 4 pages, 2 tables, 2 figure

    Metamaterial lens of specifiable frequency-dependent focus and adjustable aperture for electron cyclotron emission in the DIII-D tokamak

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    Electron Cyclotron Emission (ECE) of different frequencies originates at different locations in non-uniformly magnetized plasmas. For simultaneous observation of multiple ECE frequencies from the outside edge of a toroidal plasma confinement device (e.g. a tokamak), the focal length of the collecting optics should increase with the frequency to maximize the resolution on a line of sight along the magnetic field gradient. Here we present the design and numerical study of a zoned metamaterial lens with such characteristics, for possible deployment with the 83-130 GHz ECE radiometer in the DIII-D tokamak. The lens consists of a concentric array of miniaturized element phase-shifters. These were reverse-engineered starting from the desired Gaussian beam waist locations and further optimized to account for diffraction and finite-aperture effects that tend to displace the waist. At the same time we imposed high and uniform transmittance, averaged over all phase-shifters. The focal length is shown to increase from 1.37 m to 1.97 m over the frequency range of interest, as desired for low-field DIII-D discharges (B = -1.57 T). Retracting the lens to receded positions rigidly moves the waists accordingly, resulting in a good match -within a fraction of the Rayleigh length- of the EC-emitting layer positions at higher fields (up to B = -2.00 T). Further, it is shown how varying the lens aperture might move the waists "non-rigidly" to better match the non-rigid movement of the EC-emitting layers with the magnetic field. The numerical method presented is very general and can be used to engineer any dependence of the focal length on the frequency, including zero or minimal chromatic aberration.Comment: 18 pages, 9 figures, http://link.springer.com/article/10.1007%2Fs10762-013-9987-

    Two-dimensional molecular para-hydrogen and ortho-deuterium at zero temperature

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    We study molecular para-hydrogen (p-H2{\rm H_{2}}) and ortho-deuterium (o-D2{\rm D_{2}}) in two dimensions and in the limit of zero temperature by means of the diffusion Monte Carlo method. We report energetic and structural properties of both systems like the total and kinetic energy per particle, radial pair distribution function, and Lindemann's ratio in the low pressure regime. By comparing the total energy per particle as a function of the density in liquid and solid p-H2{\rm H_{2}}, we show that molecular para-hydrogen, and also ortho-deuterium, remain solid at zero temperature. Interestingly, we assess the quality of three different symmetrized trial wave functions, based on the Nosanow-Jastrow model, in the p-H2{\rm H_{2}} solid film at the variational level. In particular, we analyze a new type of symmetrized trial wave function which has been used very recently to describe solid 4^{4}He and found that also characterizes hydrogen satisfactorily. With this wave function, we show that the one-body density matrix ϱ1(r)\varrho_{1} (r) of solid p-H2{\rm H_{2}} possesses off-diagonal long range order, with a condensate fraction that increases sizably in the negative pressure regime.Comment: 11 pages, 9 figure

    The calibration of photographic and spectroscopic films: Reciprocity failure and thermal responses of IIaO film at liquid nitrogen temperatures

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    Reciprocity failure was examined for IIaO spectroscopic film. The results indicate reciprocity failure occurs at three distinct minimum points in time; 15 min, 30 min and 90 min. The results are unique because theory suggests only one minimum reciprocity failure point should occur. When incubating 70mm IIaO film for 15 and 30 min at temperatures of 30, 40, 50, and 60 C and then placing in a liquid nitrogen bath at a temperature of -190 C the film demonstrated an increase of the optical density when developed at a warm-up time of 30 min. Longer warm-up periods of 1, 2 and 3 hrs yield a decrease in optical density of the darker wedge patterns; whereas, shorter warm-up times yield an overall increase in the optical densities

    An evaluation of helicopter noise and vibration ride qualities criteria

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    Two methods of quantifying helicopter ride quality; absorbed power for vibration only and the NASA ride comfort model for both noise and vibration are discussed. Noise and vibration measurements were obtained on five operational US Army helicopters. The data were converted to both absorbed power and DISC's (discomfort units used in the NASA model) for specific helicopter flight conditions. Both models indicate considerable variation in ride quality between the five helicopters and between flight conditions within each helicopter

    Eye-CU: Sleep Pose Classification for Healthcare using Multimodal Multiview Data

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    Manual analysis of body poses of bed-ridden patients requires staff to continuously track and record patient poses. Two limitations in the dissemination of pose-related therapies are scarce human resources and unreliable automated systems. This work addresses these issues by introducing a new method and a new system for robust automated classification of sleep poses in an Intensive Care Unit (ICU) environment. The new method, coupled-constrained Least-Squares (cc-LS), uses multimodal and multiview (MM) data and finds the set of modality trust values that minimizes the difference between expected and estimated labels. The new system, Eye-CU, is an affordable multi-sensor modular system for unobtrusive data collection and analysis in healthcare. Experimental results indicate that the performance of cc-LS matches the performance of existing methods in ideal scenarios. This method outperforms the latest techniques in challenging scenarios by 13% for those with poor illumination and by 70% for those with both poor illumination and occlusions. Results also show that a reduced Eye-CU configuration can classify poses without pressure information with only a slight drop in its performance.Comment: Ten-page manuscript including references and ten figure
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