3,825 research outputs found
Subsonic stability and control derivatives for an unpowered, remotely piloted 3/8-scale F-15 airplane model obtained from flight test
In response to the interest in airplane configuration characteristics at high angles of attack, an unpowered remotely piloted 3/8-scale F-15 airplane model was flight tested. The subsonic stability and control characteristics of this airplane model over an angle of attack range of -20 to 53 deg are documented. The remotely piloted technique for obtaining flight test data was found to provide adequate stability and control derivatives. The remotely piloted technique provided an opportunity to test the aircraft mathematical model in an angle of attack regime not previously examined in flight test. The variation of most of the derivative estimates with angle of attack was found to be consistent, particularly when the data were supplemented by uncertainty levels
Applicability of the control configured design approach to advanced earth orbital transportation systems
The applicability of the control configured design approach (CCV) to advanced earth orbital transportation systems was studied. The baseline system investigated was fully reusable vertical take-off/horizontal landing single-stage-to-orbit vehicle and had mission requirements similar to the space shuttle orbiter. Technical analyses were made to determine aerodynamic, flight control and subsystem design characteristics. Figures of merit were assessed on vehicle dry weight and orbital payload. The results indicated that the major parameters for CCV designs are hypersonic trim, aft center of gravity, and control surface heating. Optimized CCV designs can be controllable and provide substantial payload gains over conventional non-CCV design vertical take-off vehicles
Critical Workforce Skills for Bachelor-Level Geoscientists: An Analysis of Geoscience Job Advertisements
Understanding the skills bachelor-level geoscientists need to enter the workforce is critical to their success. The goal of this study was to identify the workforce skills that are most requested from a broad range of geoscience employers. We collected 3668 job advertisements for bachelor-level geoscientists and used a case-insensitive, code-matching function in Matlab to determine the skills geoscience employers seek. Written communication (67%), field skills (63%), planning (53%), and driving (51%) were most frequently requested. Field skills and data collection were frequently found together in the ads. Written communication skills were common regardless of occupation. Quantitative skills were requested less frequently (23%) but were usually mentioned several times in the ads that did request them, signaling their importance for certain jobs. Some geoscience-specific skills were rarely found, such as temporal understanding (5%) and systems thinking (0%). We also subdivided field skills into individual tasks and ranked them by employer demand. Site assessments and evaluations, unspecified field tasks, and monitoring were the most frequently requested field skills. This study presents the geoscience community with a picture of the skills sought by employers of bachelor-level geoscientists and provides departments and programs with data they can use to assess their curricula for workforce preparation
Interface-engineered hole doping in Sr2IrO4/LaNiO3 heterostructure
The relativistic Mott insulator Sr2IrO4 driven by large spin-orbit
interaction is known for the Jeff = 1/2 antiferromagnetic state which closely
resembles the electronic structure of parent compounds of superconducting
cuprates. Here, we report the realization of hole-doped Sr2IrO4 by means of
interfacial charge transfer in Sr2IrO4/LaNiO3 heterostructures. X-ray
photoelectron spectroscopy on Ir 4f edge along with the X-ray absorption
spectroscopy at Ni L2 edge confirmed that 5d electrons from Ir sites are
transferred onto Ni sites, leading to markedly electronic reconstruction at the
interface. Although the Sr2IrO4/LaNiO3 heterostructure remains non-metallic, we
reveal that the transport behavior is no longer described by the Mott variable
range hopping mode, but by the Efros-Shklovskii model. These findings highlight
a powerful utility of interfaces to realize emerging electronic states of the
Ruddlesden-Popper phases of Ir-based oxides.Comment: 9 pages including 3 figures and reference
Critical workforce skills for bachelor-level geoscientists: An analysis of geoscience job advertisements
Understanding the skills bachelor-level geoscientists need to enter the workforce is critical to their success. The goal of this study was to identify the workforce skills that are most requested from a broad range of geoscience employers. We collected 3668 job advertisements for bachelor-level geoscientists and used a case-insensitive, code-matching function in Matlab to determine the skills geoscience employers seek. Written communication (67%), field skills (63%), planning (53%), and driving (51%) were most frequently requested. Field skills and data collection were frequently found together in the ads. Written communication skills were common regardless of occupation. Quantitative skills were requested less frequently (23%) but were usually mentioned several times in the ads that did request them, signaling their importance for certain jobs. Some geoscience-specific skills were rarely found, such as temporal understanding (5%) and systems thinking (0%). We also subdivided field skills into individual tasks and ranked them by employer demand. Site assessments and evaluations, unspecified field tasks, and monitoring were the most frequently requested field skills. This study presents the geoscience community with a picture of the skills sought by employers of bachelor-level geoscientists and provides departments and programs with data they can use to assess their curricula for workforce preparation
Observation of a multimode plasma response and its relationship to density pumpout and edge-localized mode suppression
Density pumpout and edge-localized mode (ELM) suppression by applied n=2 magnetic fields in low-collisionality DIII-D plasmas are shown to be correlated with the magnitude of the plasma response driven on the high-field side (HFS) of the magnetic axis but not the low-field side (LFS) midplane. These distinct responses are a direct measurement of a multimodal magnetic plasma response, with each structure preferentially excited by a different n=2 applied spectrum and preferentially detected on the LFS or HFS. Ideal and resistive magneto-hydrodynamic (MHD) calculations find that the LFS measurement is primarily sensitive to the excitation of stable kink modes, while the HFS measurement is primarily sensitive to resonant currents (whether fully shielding or partially penetrated). The resonant currents are themselves strongly modified by kink excitation, with the optimal applied field pitch for pumpout and ELM suppression significantly differing from equilibrium field alignment.This material is based upon work supported by the U.S.
Department of Energy, Office of Science, Office of Fusion
Energy Sciences, using the DIII-D National Fusion Facility,
a DOE Office of Science user facility, under Awards No. DE-FC02-04ER54698, No. DE-AC02-09CH11466,
No. DE-FG02-04ER54761, No. DE-AC05-06OR23100,
No. DE-SC0001961, and No. DE-AC05-00OR22725.
S. R. H. was supported by AINSE and ANSTO
Coherent Control of Isotope Separation in HD+ Photodissociation by Strong Fields
The photodissociation of the HD+ molecular ion in intense short- pulsed
linearly polarized laser fields is studied using a time- dependent wave-packet
approach where molecular rotation is fully included. We show that applying a
coherent superposition of the fundamental radiation with its second harmonic
can lead to asymmetries in the fragment angular distributions, with significant
differences between the hydrogen and deuterium distributions in the long
wavelength domain where the permanent dipole is most efficient. This effect is
used to induce an appreciable isotope separation.Comment: Physical Review Letters, 1995 (in press). 4 pages in revtex format, 3
uuencoded figures. Full postcript version available at:
http://chemphys.weizmann.ac.il/~charron/prl.ps or
ftp://scipion.ppm.u-psud.fr/coherent.control/prl.p
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