The energy efficient engine project

The Energy Efficient Engine Project is directed at providing, by 1984, the advanced technologies which could be used for a generation of fuel conservative turbofan engines. The project is conducted through contracts with the General Electric Company and Pratt and Whitney Aircraft. The scope of the entire project and the current status of these efforts are summarized. A description of the preliminary designs of the fully developed engines is included and the potential benefits of these advanced engines, as well as highlights of some of the component technology efforts conducted to date, are discussed

Eta-mesic nuclei

In this contribution we report on theoretical studies of $\eta$ nuclear quasi-bound states in few- and many-body systems performed recently by the Jerusalem-Prague Collaboration [1-5]. Underlying energy-dependent $\eta N$ interactions are derived from coupled-channel models that incorporate the $N^*(1535)$ resonance. The role of self-consistent treatment of the strong energy dependence of subthreshold $\eta N$ amplitudes is discussed. Quite large downward energy shift together with rapid decrease of the $\eta N$ amplitudes below threshold result in relatively small binding energies and widths of the calculated $\eta$ nuclear bound states. We argue that the subthreshold behavior of $\eta N$ scattering amplitudes is crucial to conclude whether $\eta$ nuclear states exist, in which nuclei the $\eta$ meson could be bound and if the corresponding widths are small enough to allow detection of these $\eta$ nuclear states in experiment.Comment: 7 pages, 5 figures; presented at HADRON2017, Sept. 25-29, 2017, Salamanca (Spain); prepared for Proceedings of Scienc

Can Light Echoes Account for the Slow Decay of Type IIn Supernovae?

The spectra of type IIn supernovae indicate the presence of apre-existing slow, dense circumstellar wind (CSW). If the CSW extends sufficiently far from the progenitor star, then dust formation should occur in the wind. The light from the supernova explosion will scatter off this dust and produce a light echo. Continuum emission seen after the peak will have contributions from both this echo as well as from the shock of the ejecta colliding with the CSW, with a fundamental question of which source dominates the continuum. We calculate the brightness of the light echo as a function of time for a range of dust shell geometries, and use our calculations to fit to the light curves of SN 1988Z and SN 1997ab, the two slowest declining IIn supernovae on record. We find that the light curves of both objects can be reproduced by the echo model. However, their rate of decay from peak, color at peak and their observed peak absolute magnitudes when considered together are inconsistent with the echo model. Furthermore, when the observed values of M$_{B}$ are corrected for the effects of dust scattering, the values obtained imply that these supernovae have unrealistically high luminosities. We conclude that light echoes cannot properly account for the slow decline seen in some IIn's, and that the shock interaction is likely to dominate the continuum emission.Comment: 15 pages, 9 figure

Physics issues in simulations with dynamical overlap fermions

We discuss the impact of various improvements on simulations of dynamical overlap fermions using the Hybrid Monte Carlo algorithm. We focus on the usage of fat links and multiple pseudo-fermion fields.Comment: 14 pages, 10 figure

Dynamics of Transport and Energy Systems. History of Development and a Scenario for the Future

This report analyzes the historical development of transport systems from canals to railroads, from horse-driven carriages to automobiles, and more recently to air transportation and new forms of high-speed ground transportation. The historically observed heterogeneity in the timing, duration, and adoption intensity of the diffusion of individual transport technologies is then used to sketch a scenario of energy demand, and resulting carbon emissions from the passenger transport sector. In this scenario, automobile and air transport in the industrialized countries approaches saturation in the next two to three decades. For developing countries, however, the scenario suggests that despite their high growth potential, they may not necessarily mimic the high adoption intensity of individual transport modes prevailing in the industrialized countries. Combined with a continuation of historical rates of efficiency improvements, transportation energy demand and resulting carbon emissions could level off after the year 2000. Carbon emissions could be reduced significantly thereafter through the penetration of electric- and hydrogen-powered vehicles in the industrialized countries. Such a scenario illustrates a possible future pathway contrasting conventional wisdom and giving some indication of the direction and time scale of technology and transport policy actions required to reconcile growing mobility with global environmental concerns

Fluctuations and the QCD phase diagram

In this contribution the role of quantum fluctuations for the QCD phase diagram is discussed. This concerns in particular the importance of the matter back-reaction to the gluonic sector. The impact of these fluctuations on the location of the confinement/deconfinement and the chiral transition lines as well as their interrelation are investigated. Consequences of our findings for the size of a possible quarkyonic phase and location of a critical endpoint in the phase diagram are drawn.Comment: 7 pages, 3 figures, to appear in Physics of Atomic Nucle