Human Factors of Flight-deck Automation: NASA/Industry Workshop

The scope of automation, the benefits of automation, and automation-induced problems were discussed at a workshop held to determine whether those functions previously performed manually on the flight deck of commercial aircraft should always be automated in view of various human factors. Issues which require research for resolution were identified. The research questions developed are presented

Effect of strain on the orbital and magnetic ordering of manganite thin films and their interface with an insulator

We study the effect of uniform uniaxial strain on the ground state electronic configuration of a thin film manganite. Our model Hamiltonian includes the double-exchange, the Jahn-Teller electron-lattice coupling, and the antiferromagnetic superexchange. The strain arises due to the lattice mismatch between an insulating substrate and a manganite which produces a tetragonal distortion. This is included in the model via a modification of the hopping amplitude and the introduction of an energy splitting between the Mn e_g levels. We analyze the bulk properties of half-doped manganites and the electronic reconstruction at the interface between a ferromagnetic and metallic manganite and the insulating substrate. The strain drives an orbital selection modifying the electronic properties and the magnetic ordering of manganites and their interfaces.Comment: 8 pages, 8 figure

Optimization of graded multilayer designs for astronomical x-ray telescopes

We developed a systematic method for optimizing the design of depth-graded multilayers for astronomical hard-x-ray and soft-γ-ray telescopes based on the instrument’s bandpass and the field of view. We apply these methods to the design of the conical-approximation Wolter I optics employed by the balloon-borne High Energy Focusing Telescope, using W/Si as the multilayer materials. In addition, we present optimized performance calculations of mirrors, using other material pairs that are capable of extending performance to photon energies above the W K-absorption edge (69.5 keV), including Pt/C, Ni/C, Cu/Si, and Mo/Si

Using aircraft measurements to determine the refractive index of Saharan dust during the DODO Experiments

Much uncertainty in the value of the imaginary part of the refractive index of mineral dust contributes to uncertainty in the radiative effect of mineral dust in the atmosphere. A synthesis of optical, chemical and physical in-situ aircraft measurements from the DODO experiments during February and August 2006 are used to calculate the refractive index mineral dust encountered over West Africa. Radiative transfer modeling and measurements of broadband shortwave irradiance at a range of altitudes are used to test and validate these calculations for a specific dust event on 23 August 2006 over Mauritania. Two techniques are used to determine the refractive index: firstly a method combining measurements of scattering, absorption, size distributions and Mie code simulations, and secondly a method using composition measured on filter samples to apportion the content of internally mixed quartz, calcite and iron oxide-clay aggregates, where the iron oxide is represented by either hematite or goethite and clay by either illite or kaolinite. The imaginary part of the refractive index at 550 nm (ni550) is found to range between 0.0001 i to 0.0046 i, and where filter samples are available, agreement between methods is found depending on mineral combination assumed. The refractive indices are also found to agree well with AERONET data where comparisons are possible. ni550 is found to vary with dust source, which is investigated with the NAME model for each case. The relationship between both size distribution and ni550 on the accumulation mode single scattering albedo at 550 nm (ω0550) are examined and size distribution is found to have no correlation to ω0550, while ni550 shows a strong linear relationship with ω0550. Radiative transfer modeling was performed with different models (Mie-derived refractive indices, but also filter sampling composition assuming both internal and external mixing). Our calculations indicate that Mie-derived values of ni550 and the externally mixed dust where the iron oxide-clay aggregate corresponds to the goethite-kaolinite combination result in the best agreement with irradiance measurements. The radiative effect of the dust is found to be very sensitive to the mineral combination (and hence refractive index) assumed, and to whether the dust is assumed to be internally or externally mixed

Laterally pumped GaAs/AlGaAs quantum wells as sources of broadband terahertz radiation

In this work we consider lateral current pumped GaAs/AlGaAs quantum wells as sources of incoherent terahertz radiation. The lateral field heats the electrons in a two-dimensional quantum layer and increases the population of higher subbands, hence also increasing the radiation power generated in spontaneous intersubband emission processes. Digitally graded quasi-parabolic and simple square quantum wells are considered, and the advantages of both types are discussed. Calculations at lattice temperatures of 77 K and 300 K, for electric fields up to 10 kV/cm, show that the optical output power of ~100−200 W/m2 may be achieved for the 7 THz source. The main peak of the spectrum, at 7 THz, of the quasi-parabolic quantum well exceeds the black body radiation at 300 K by approximately a factor of two and by two orders of magnitude at 77 K

A time series from the beach environment-II

This work is the second in a continuing series of time-series data reports to be published periodically as a result of field investigations in the beach-ocean-atmosphere system by Dr. Wyman Harrison and his associates. The first report was published as Technical Memorandum ERLTM-AOL 1 of ESSA\u27s Atlantic Oceanographic Laboratories. This series of reports will allow other researchers to test hypotheses or to experiment with analytical procedures without going through the expensive and somewhat arduous task of obtaining the data

A time series from the beach environment-II

This work is the second in a continuing series of time-series data reports to be published periodically as a result of field investigations in the beach-ocean-atmosphere system by Dr. Wyman Harrison and his associates. The first report was published as Technical Memorandum ERLTM-AOL 1 of ESSA\u27s Atlantic Oceanographic Laboratories. This series of reports will allow other researchers to test hypotheses or to experiment with analytical procedures without going through the expensive and somewhat arduous task of obtaining the data

Temperature-dependent resistivity of suspended graphene

In this paper we investigate the electron-phonon contribution to the resistivity of suspended single layer graphene. In-plane as well as flexural phonons are addressed in different temperature regimes. We focus on the intrinsic electron-phonon coupling due to the interaction of electrons with elastic deformations in the graphene membrane. The competition between screened deformation potential vs fictitious gauge field coupling is discussed, together with the role of tension in the suspended flake. In the absence of tension, flexural phonons dominate the phonon contribution to the resistivity at any temperature $T$ with a $T^{5/2}_{}$ and $T^{2}_{}$ dependence at low and high temperatures, respectively. Sample-specific tension suppresses the contribution due to flexural phonons, yielding a linear temperature dependence due to in-plane modes. We compare our results with recent experiments.Comment: 11 pages, 3 figure

The development of structural adhesive systems suitable for use with liquid oxygen Annual summary report, 1 Jul. 1964 - 30 Jun. 1965

Preparation and testing of adhesive polyurethanes, polycarbonates, and other highy halogenated polymers for liquid oxygen compatibilit