81,241 research outputs found
Lunar Atmospheric Contamination Due to an Apollo Landing
Lunar atmospheric contamination due to Apollo landin
Theoretical and experimental investigation on modulation-inducing retrodirective optical systems /miros/ monthly progress report, 20 dec. 1964 - 20 jan. 1965
Modulation inducing retrodirecting optical system - diode mount for gallium arsenide lasers, and generation of alkaline line by stimulated Raman emissio
Development of modified vibration test criteria for qualifying space vehicle components
The results of the evaluation of two response prediction methods relating to the prediction of structural responses of stiffened shell structures with or without attached components, and subjected to broadband acoustic excitations are presented. The methods under evaluation were the constant mass attenuation method and the impedance ratio method. Example problems were used to illustrate the application procedures of these two methods and to compare their predicted results with the experimentally measured data. It is found that more realistic estimates of the structural response can be obtained by the impedance ratio method
Development of modified vibration test criteria for qualifying space vehicle components
Simplified methods are described to estimate the test criteria of primary structures at component attachment points subjected to broadband random acoustic excitations. The current method utilizes a constant smeared component mass attenuation factor across the frequency range of interest. The developed method indicates that the attenuation factor is based on a frequency dependent ratio of the mechanical impedances of both the component and primary structures. The procedures used to predict the structural responses are considered as the present state-of-the-art and provide satisfactory prediction results. Example problems are used to illustrate the application procedures of the two methods and to compare the significant difference. It was found that the lower test criteria obtained by the impedance ratio method is due to the results of considering the effects of component/primary structure interaction
Global Entanglement for Multipartite Quantum States
Based on the residual entanglement [9] (Phys. Rev. A \textbf{71}, 044301
(2005)), we present the global entanglement for a multipartite quantum state.
The measure is shown to be also obtained by the bipartite partitions of the
multipartite state. The distinct characteristic of the global entanglement is
that it consists of the sum of different entanglement contributions. The
measure can provide sufficient and necessary condition of fully separability
for pure states and be conveniently extended to mixed states by minimizing the
convex hull. To test the sufficiency of the measure for mixed states, we
evaluate the global entanglement of bound entangled states. The properties of
the measure discussed finally show the global entanglement is an entanglement
monotone.Comment: 6 page
Coupling of Nonlocal Potentials to Electromagnetic Fields
Nonlocal Hamiltonians are used widely in first-principles quantum
calculations; the nonlocality stems from eliminating undesired degrees of
freedom, e.g. core electrons. To date, attempts to couple nonlocal systems to
external electromagnetic (EM) fields have been heuristic or limited to weak or
long wavelength fields. Using Feynman path integrals, we derive an exact,
closed-form coupling of arbitrary EM fields to nonlocal systems. Our results
justify and clarify the couplings used to date and are essential for systematic
computation of linear and especially nonlinear response.Comment: 1 figure, 1 tabl
Density and flux distributions of neutral gases in the lunar atmosphere
Neon, argon, and helium density and flux distributions in lunar atmospher
A Two-Step Etching Method to Fabricate Nanopores in Silicon
A cost effectively method to fabricate nanopores in silicon by only using the
conventional wet-etching technique is developed in this research. The main
concept of the proposed method is a two-step etching process, including a
premier double-sided wet etching and a succeeding track-etching. A special
fixture is designed to hold the pre-etched silicon wafer inside it such that
the track-etching can be effectively carried out. An electrochemical system is
employed to detect and record the ion diffusion current once the pre-etched
cavities are etched into a through nanopore. Experimental results indicate that
the proposed method can cost effectively fabricate nanopores in silicon.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
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