A study of the interior ballistic equations

Summary A system of non-linear differential equations, typical of the interior ballistics equations for orthodox guns, is studied. Characteristics of the mathematical pressure curves are obtained for the entire spectrums of the ballistic parameter, burning exponent, and geometric parameter (characteristic of the form function). The mathematical solutions are found to distinguish sharply between regressive and progressive burning geometries, and a constant pressure solution is obtained (a piezometric efficiency of one) for what is defined as the ideally progressive geometry. The approximate validity of isothermal solutions, established by Clemmow for a linear burning law, is extended to the general case.The work on this paper was sponsored by the Office of Ordnance Research, U. S. Army, Contract DA-36-034 ORD-2733 RD.     

Phase space tweezers for tailoring cavity fields by quantum Zeno dynamics

We discuss an implementation of quantum Zeno dynamics in a cavity quantum electrodynamics experiment. By performing repeated unitary operations on atoms coupled to the field, we restrict the field evolution in chosen subspaces of the total Hilbert space. This procedure leads to promising methods for tailoring nonclassical states. We propose to realize "tweezers" picking a coherent field at a point in phase space and moving it towards an arbitrary final position without affecting other nonoverlapping coherent components. These effects could be observed with a state-of-the-art apparatus.     

The detection of increments and decrements is not facilitated by abrupt onsets or offsets

Two experiments measured thresholds for the detection of increments and decrements in the intensity of a quasi-continuous broadband-noise (experiment 1) or increments in a 477-Hz pure-tone pedestal (experiment 2). A variety of onset and offset ramps for the intensity change were tested, from instantaneous onsets or offsets to ramps lasting several tens of milliseconds. For increments and decrements with equal duration, the characteristics of the ramps had little effect on performance. Abrupt rise times, which are associated with strong transient responses in auditory neurons, did not facilitate detection in comparison to much slower rise times. The temporal window model of temporal resolution provided a good account of the data when the decision statistic was the maximum magnitude of the change in the output of the window produced by the increment or decrement, but provided a poor account of the data when the decision statistic was the maximum rate of change in the output of the window over time. Overall the results suggest that, in the absence of cues in the audio-frequency domain, rapid changes in envelope contribute little to near-threshold increment or decrement detection.     

Elliptic flow measurements from STAR

In these proceedings some of the highlights of the elliptic flow measurements from STAR at $\sqrt {s_{NN} } = 130$ and 200 GeV for Au + Au collisions are presented.