558 research outputs found
QCD strings and the thermodynamics of the metastable phase of QCD at large
The thermodyanmics of a metastable hadronic phase of QCD at large are
related to properties of an effective QCD string. In particular, it is shown
that in the large limit and near the maximum hadronic temperature, ,
the energy density and pressure of the metastable phase scale as (for ) and (for ) where is the effective
number of transverse dimensions of the string theory. It is shown, however,
that for the thermodynamic quantities of interest the limits and
do not commute. The prospect of extracting via
lattice simulations of the metastable hadronic phase at moderately large
is discussed.Comment: After this paper was published, the author became aware of an
important early paper by Charles Thorn on the subject of the QCD phase
transition at large N_c and its relation to the Hagedorn spectrum. Given the
pioneering nature of Thorn's paper, and the fact that it is not as widely
known as it should be, it is important to cite it in the present work. This
updated version cites Thorn's wor
Near-bed hydrodynamics and turbulence below a large-scale plunging breaking wave over a mobile barred bed profile
Funded by The research presented in this paper is part of the SINBAD project. Grant Number: STW (12058) and EPSRC (EP/J00507X/1, EP/J005541/1)Peer reviewedPublisher PDFPublisher PD
Multidisciplinary Study of Pulse Detonation Engines
Research at the Explosion Dynamics Laboratories at Caltech over the past three years under
an ONR contract has examined many issues critical to Pulse Detonation Engine (PDE) development.
These include: fundamental and applied studies of detonation initiation; detonation cell width
measurements to characterize fuels, including JP10; visualization of the reaction zone structure of
propagating detonations; direct measurements and analytical modeling of impulse from a detonation
tube, including the effects of partial fill and exit geometry; studies of detonation diffraction; and the
structural response of tubes to detonation loading, including fracture and failure. Each of these
aspects of our program is discussed and key results are presented
Nickel-cadium batteries for Apollo telescope mount
The operational testing and evaluation program is presented which was conducted on 20-ampere-hour nickel-cadmium (Ni-Cd) batteries for use on the Apollo telescope mount (ATM). The test program was initiated in 1967 to determine if the batteries could meet ATM mission requirements and to determine operating characteristics and methods. The ATM system power and charging power for the Ni-Cd secondary batteries is provided by a solar array during the 58-minute daylight portion of the orbit; during the 36-minute night portion of the orbit, the Ni-Cd secondary batteries will supply ATM system power. The test results reflect battery operating characteristics and parameters relative to simulated ATM orbital test conditions. Maximum voltage, charge requirements, capacity, temperature, and cyclic characteristics are presented
Analysis of overfitting in the regularized Cox model
The Cox proportional hazards model is ubiquitous in the analysis of
time-to-event data. However, when the data dimension p is comparable to the
sample size , maximum likelihood estimates for its regression parameters are
known to be biased or break down entirely due to overfitting. This prompted the
introduction of the so-called regularized Cox model. In this paper we use the
replica method from statistical physics to investigate the relationship between
the true and inferred regression parameters in regularized multivariate Cox
regression with L2 regularization, in the regime where both p and N are large
but with p/N ~ O(1). We thereby generalize a recent study from maximum
likelihood to maximum a posteriori inference. We also establish a relationship
between the optimal regularization parameter and p/N, allowing for
straightforward overfitting corrections in time-to-event analysis
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