Remotely operated gripper provides vertical control rod movement

Remote actuation of a gripper shaft affects vertical engagement between a drive shaft and control rod. A secondary function of the gripper is to provide remote indication of positive completion of the gripping or ungripping operation

Hypersonic airframe structures: Technology needs and flight test requirements

Hypersonic vehicles, that may be produced by the year 2000, were identified. Candidate thermal/structural concepts that merit consideration for these vehicles were described. The current status of analytical methods, materials, manufacturing techniques, and conceptual developments pertaining to these concepts were reviewed. Guidelines establishing meaningful technology goals were defined and twenty-eight specific technology needs were identified. The extent to which these technology needs can be satisfied, using existing capabilities and facilities without the benefit of a hypersonic research aircraft, was assessed. The role that a research aircraft can fill in advancing this technology was discussed and a flight test program was outlined. Research aircraft thermal/structural design philosophy was also discussed. Programs, integrating technology advancements with the projected vehicle needs, were presented. Program options were provided to reflect various scheduling and cost possibilities

Thermally stable electrolytes for rechargeable lithium batteries, phase 2

During the second year of research under NASA SBIR Contract NAS7-967, Covalent Associates and NASA contract monitors at the Jet Propulsion Laboratory agreed to perform an evaluation of the three best electrolytes developed during Phase 2. Due to the extensive period of time required to collect meaningful cycling data, we realized the study would extend well beyond the original formal end of the Phase 2 program (August 31, 1988). The substitution of this effort in lieu of an earlier proposed 20-cell final deliverable is formally documented in Modification No. 1 of Contract NAS7-967 as task 7. This Addendum contains the results of the cycling studies performed at Covalent Associates. In addition, sealed ampoules of each of these three electrolytes were delivered to the Jet Propulsion Laboratory Electrochemical Power Group. Their concurrent evaluation in a different test vehicle has also been recently concluded and their results are also summarized herein

Charm production in deep inelastic and diffractive scattering

We consider the production of charm by real and virtual photons. Special attention is paid to diffractive charm production, which provides information on the gluonic content of the Pomeron. Our calculations are based on the gluon distributions of the CKMT-model, which is shown to lead to agreement with the data on open charm production in deep inelastic scattering. We compare predictions for diffractive charm production of different models for the distribution of gluons in the Pomeron. Experiments at HERA should be able to discriminate between them. Predictions for beauty production in diffractive and non-diffractive interactions of photons are also given.Comment: 14 pages REVTEX and 24 figures include

Density Functional Theory screening of gas-treatment strategies for stabilization of high energy-density lithium metal anodes

To explore the potential of molecular gas treatment of freshly cut lithium foils in non-electrolyte based passivation of high energy-density Li anodes, density functional theory (DFT) has been used to study the decomposition of molecular gases on metallic lithium surfaces. By combining DFT geometry optimization and Molecular Dynamics, the effects of atmospheric (N2, O2, CO2) and hazardous (F2, SO2) gas decomposition on Li(bcc) (100), (110), and (111) surfaces on relative surface energies, work functions, and emerging electronic and elastic properties are investigated. The simulations suggest that exposure to different molecular gases can be used to induce and control reconstructions of the metal Li surface and substantial changes (up to over 1 eV) in the work function of the passivated system. Contrary to the other considered gases, which form metallic adlayers, SO2 treatment emerges as the most effective in creating an insulating passivation layer for dosages <= 1 mono-layer. The substantial Li->adsorbate charge transfer and adlayer relaxation produce marked elastic stiffening of the interface, with the smallest change shown by nitrogen-treated adlayers

Phonon-affected steady-state transport through molecular quantum dots

We consider transport through a vibrating molecular quantum dot contacted to macroscopic leads acting as charge reservoirs. In the equilibrium and nonequilibrium regime, we study the formation of a polaron-like transient state at the quantum dot for all ratios of the dot-lead coupling to the energy of the local phonon mode. We show that the polaronic renormalization of the dot-lead coupling is a possible mechanism for negative differential conductance. Moreover, the effective dot level follows one of the lead chemical potentials to enhance resonant transport, causing novel features in the inelastic tunneling signal. In the linear response regime, we investigate the impact of the electron-phonon interaction on the thermoelectrical properties of the quantum dot device.Comment: 11 pages, 7 figures, FQMT11 Proceeding

A para-differential renormalization technique for nonlinear dispersive equations

For \alpha \in (1,2) we prove that the initial-value problem \partial_t u+D^\alpha\partial_x u+\partial_x(u^2/2)=0 on \mathbb{R}_x\times\mathbb{R}_t; u(0)=\phi, is globally well-posed in the space of real-valued L^2-functions. We use a frequency dependent renormalization method to control the strong low-high frequency interactions.Comment: 42 pages, no figure

Resonance Production on Nuclei at High Energies: Nuclear-Medium Effects and Space-Time Picture

The influence of nuclear matter on the properties of coherently produced resonances is discussed. It is shown that, in general, the mass distribution of resonance decay products has a two-component structure corresponding to decay outside and inside the nucleus. The first (narrow) component of the amplitude has a Breit-Wigner form determined by the vacuum values of mass and width of the resonance. The second (broad) component corresponds to interactions of the resonance with the nuclear medium. It can be also described by a Breit-Wigner shape with parameters depending e.g. on the nuclear density and on the cross section of the resonance-nucleon interaction. The resonance production is examined both at intermediate energies, where interactions with the nucleus can be considered as a series of successive local rescatterings, and at high energies, $E>E_{crit}$, where a change of interaction picture occurs. This change of mechanisms of the interactions with the nucleus is typical for the description within the Regge theory approach and is connected with the nonlocal nature of the reggeon interaction.Comment: 22 pages LaTeX, 1 Postscript file containing 7 figures; addition in beginning of Ch. 2; Nucl. Phys. A, to be publishe