A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment

A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies

Superluminal Propagation and Acausality of Nonlinear Massive Gravity

Massive gravity is an old idea: trading geometry for mass. Much effort has been expended on establishing a healthy model, culminating in the current ghost-free version. We summarize here our recent findings -- that it is still untenable -- because it is locally acausal: CTC solutions can be constructed in a small neighborhood of any event.Comment: Contribution to Conference in Honour of the 90th Birthday of Freeman Dyson -- To Appear in Proceeding. v2: Explicit CTC example, and other improvements, adde

Local flow management/profile descent algorithm. Fuel-efficient, time-controlled profiles for the NASA TSRV airplane

The Local Flow Management/Profile Descent (LFM/PD) algorithm designed for the NASA Transport System Research Vehicle program is described. The algorithm provides fuel-efficient altitude and airspeed profiles consistent with ATC restrictions in a time-based metering environment over a fixed ground track. The model design constraints include accommodation of both published profile descent procedures and unpublished profile descents, incorporation of fuel efficiency as a flight profile criterion, operation within the performance capabilities of the Boeing 737-100 airplane with JT8D-7 engines, and conformity to standard air traffic navigation and control procedures. Holding and path stretching capabilities are included for long delay situations

An investigation of TNAV equipped aircraft in a simulated en route metering environment

This document presents the results of an effort to estimate how often a TNAV (Time Navigation) equipped aircraft could be given a TNAV clearance in the En Route Metering (ERM) system as a function of the percentage of arriving traffic which is TNAV equipped. A fast-time simulation of Denver Stapleton international arrival traffic in the Denver Air Route Traffic Control Center route structure, including en route metering operations, was used to develop data on estimated conflicts, clearance communications and fuel usage for traffic mixes of 25, 50, 75 and 100% TNAV equipped. This study supports an overall effort by NASA to assess the benefits and required technology for using TNAV-equipped aircraft in the ERM environment

Prohibiting Good Faith Reports Under the Uniform Mediation Act: Keeping the Adjudication Camel out of the Mediation Tent

This symposium article examines a narrow slice of the Uniform Mediation Act - the prohibition on mediator communication to judges about a party\u27s good faith participation or problem behavior in mediation

Ghosts in asymmetric brane gravity and the decoupled stealth limit

We study the spectrum of gravitational perturbations around a vacuum de Sitter brane in a 5D asymmetric braneworld model, with induced curvature on the brane. This generalises the stealth acceleration model proposed by Charmousis, Gregory and Padilla (CGP) which realises the Cardassian cosmology in which power law cosmic acceleration can be driven by ordinary matter. Whenever the bulk has infinite volume we find that there is always a perturbative ghost propagating on the de Sitter brane, in contrast to the Minkowski brane case analysed by CGP. We discuss the implication of this ghost for the stealth acceleration model, and identify a limiting case where the ghost decouples as the de Sitter curvature vanishes.Comment: 21 page

Superconducting and normal-state interlayer-exchange-coupling in La0.67_{0.67}Sr0.33_{0.33}MnO3{3}-YBa2_{2}Cu3_{3}O7−La_{7}-La_{0.67}SrSr_{0.33}MnO MnO{3}$ epitaxial trilayers

The issue of interlayer exchange coupling in magnetic multilayers with superconducting (SC) spacer is addressed in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) - YBa$_{2}$Cu$_{3}$O$_{7}$ (YBCO) - La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) epitaxial trilayers through resistivity, ac-susceptibility and magnetization measurements. The ferromagnetic (FM) LSMO layers possessing in-plane magnetization suppress the critical temperature (T$_{c})$ of the c-axis oriented YBCO thin film spacer. The superconducting order, however, survives even in very thin layers (thickness d$_{Y} \sim$ 50 {\AA}, $\sim$ 4 unit cells) at T $<$ 25 K. A predominantly antiferromagnetic (AF) exchange coupling between the moments of the LSMO layers at fields $<$ 200 Oe is seen in the normal as well as the superconducting states of the YBCO spacer. The exchange energy J$_{1}$ ($\sim$ 0.08 erg/cm$^{2}$ at 150 K for d$_{Y}$ = 75 {\AA}) grows on cooling down to T$_{c}$, followed by truncation of this growth on entering the superconducting state. The coupling energy J$_{1}$ at a fixed temperature drops exponentially with the thickness of the YBCO layer. The temperature and d$_{Y}$ dependencies of this primarily non-oscillatory J$_{1}$ are consistent with the coupling theories for systems in which transport is controlled by tunneling. The truncation of the monotonic T dependence of J$_{1}$ below T$_{c}$ suggests inhibition of single electron tunneling across the CuO$_{2}$ planes as the in-plane gap parameter acquires a non-zero value.Comment: Accepted for publication in Phys. Rev.

Brans-Dicke DGP Brane Cosmology

We consider a five dimensional DGP-brane scenario endowed with a non-minimally coupled scalar field within the context of Brans-Dicke theory. This theory predicts that the mass appearing in the gravitational potential is modified by the addition of the mass of the effective intrinsic curvature on the brane. We also derive the effective four dimensional field equations on a 3+1 dimensional brane where the fifth dimension is assumed to have an orbifold symmetry. Finally, we discuss the cosmological implications of this setup, predicting an accelerated expanding universe with a value of the Brans-Dicke parameter $\omega$ consistent with values resulting from the solar system observations.Comment: 12 pages, 1 figure, to appear in JCA