Synchronization of extended systems from internal coherence

A condition for the synchronizability of a pair of PDE systems, coupled through a finite set of variables, is commonly the existence of internal synchronization or internal coherence in each system separately. The condition was previously illustrated in a forced-dissipative system, and is here extended to Hamiltonian systems, using an example from particle physics. Full synchronization is precluded by Liouville's theorem. A form of synchronization weaker than "measure synchronization" is manifest as the positional coincidence of coherent oscillations ("breathers" or "oscillons") in a pair of coupled scalar field models in an expanding universe with a nonlinear potential, and does not occur with a variant of the model that does not exhibit oscillons.Comment: version accepted for publication in PRE (paragraph beginning at the bottom of pg. 5 has been rewritten to suggest unifying principle for synchronizability, applying to both forced-dissipative and Hamiltonian systems; other minor changes

A Noisy Monte Carlo Algorithm

We propose a Monte Carlo algorithm to promote Kennedy and Kuti's linear accept/reject algorithm which accommodates unbiased stochastic estimates of the probability to an exact one. This is achieved by adopting the Metropolis accept/reject steps for both the dynamical and noise configurations. We test it on the five state model and obtain desirable results even for the case with large noise. We also discuss its application to lattice QCD with stochastically estimated fermion determinants.Comment: 10 pages, 1 tabl

Synchronicity in predictive modelling: a new view of data assimilation

International audienceThe problem of data assimilation can be viewed as one of synchronizing two dynamical systems, one representing "truth" and the other representing "model", with a unidirectional flow of information between the two. Synchronization of truth and model defines a general view of data assimilation, as machine perception, that is reminiscent of the Jung-Pauli notion of synchronicity between matter and mind. The dynamical systems paradigm of the synchronization of a pair of loosely coupled chaotic systems is expected to be useful because quasi-2D geophysical fluid models have been shown to synchronize when only medium-scale modes are coupled. The synchronization approach is equivalent to standard approaches based on least-squares optimization, including Kalman filtering, except in highly non-linear regions of state space where observational noise links regimes with qualitatively different dynamics. The synchronization approach is used to calculate covariance inflation factors from parameters describing the bimodality of a one-dimensional system. The factors agree in overall magnitude with those used in operational practice on an ad hoc basis. The calculation is robust against the introduction of stochastic model error arising from unresolved scales

Influence of moisture and thermal cycling on delamination flaws in transparent armor materials: Thermoplastic polyurethane bonded glass-polycarbonate laminates

Transparent armor laminates (TALs), manufactured from layers of soda-lime-silica float glass, thermoplastic polyurethane, and polycarbonate, are known to suffer unpredictable delamination in ambient-condition service, interfering with their transparency and reducing operational lifespan. The nature of the mechanisms leading to delamination are not well known, and believed to be driven by exposure to moisture, thermal cycling, and stresses induced by differing thermal expansion of the layers. Herein, small-scale coupons of TAL laminates were hygrothermally aged for a variety of durations and moisture exposure geometries, then thermally cycled to investigate the onset of delamination. As duration of aging was increased, the mode of failure changed from cohesive void formation at high temperature (85 °C), to interfacial crack during less-extreme thermal cycling (0 °C to 70 °C). The progression indicated that the barrier to nucleating delaminations reduced with progressing moisture exposure, leading to less-selective initiation and increasingly contiguous growth of the delaminations. In this study, for the first time, delaminations were successfully and consistently produced in glass-polycarbonate laminates, the delamination failure mode was correlated with the degree of moisture exposure, and both a theoretical basis to guide further studies and a methodology to assess the delamination resistance of current and future transparent armor designs are suggested

Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions

New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics, and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high (n=6-10) principal quantum numbers affects some helium-like line ratios from low-lying (n=2) transitions.Comment: 5 pages, 6 figures, accepted by ApJ Letter

Plasma Energy Loss into Kaluza-Klein Modes

Recently, Barger {\em et al.} computed energy losses into Kaluza Klein modes from astrophysical plasmas in the approximation of zero density for the plasmas. We extend their work by considering the effects of finite density for two plasmon processes. Our results show that, for fixed temperature, the energy loss rate per cm$^3$ is constant up to some critical density and then falls exponentially. This is true for transverse and longitudinal plasmons in both the direct and crossed channels over a wide range of temperature and density. A difficulty in deriving the appropriate covariant interaction energy at finite density and temperature is addressed. We find that, for the cases considered by Barger {\em et al.}, the zero density approximation and the neglect of other plasmon processes is justified to better than an order of magnitude.Comment: 17 pages, LaTeX2e, 4 figures, 11 table

Properties of the a1 Meson from Lattice QCD

We determine the mass and decay constant of the $a_1$ meson using Monte Carlo simulation of lattice QCD. We find $M_{a_1} = 1250 \pm 80$ MeV and $f_{a_1} = 0.30 \pm 0.03 ~({\rm GeV})^2$, in good agreement with experiment.Comment: 9 page uu-encoded compressed postscript file. version appearing in Phys. Rev. Lett. 74 (1995) 459

Complex Action Support from Coincidences of Couplings

Our model \cite{ownmMPP}\cite{SIMPP} with complex action in a functional integral formulation with path integrals extending over all times, past and future, is reviewed. Several numerical relations between coupling constants are presented as supporting evidence. The new evidence is that some more unexplained coincidences are explained in our model: 1) The "scale problem" is solved because the Higgs field expectation value is predicted to be very small compared to say some fundamental scale, that might be the Planck scale. 2) The Higgs VEV need not, however, to be just zero, but rather is predicted to be so that the running top-Yukawa coupling just is about to be unity at this scale; in this way the (weak) scale easily becomes "exponentially small". Instead of the top-Yukawa we should rather say the highest flavour Yukawa coupling here. These predictions are only achieved by allowing the principle of minimization of the imaginary part of the action SI(history) to to a certain extent adjust some coupling constants in addition to the initial conditions. If Susy-partners are not found in LHC, it would strengthen the need for "solution" of the hierarchy or rather scale problem along the lines of the present article.Comment: only text. Some printing mistakes corrected and a couple of new subsections inserted and abstract stylistically changed a bi

First Results from Lattice Simulation of the PWMM

We present results of lattice simulations of the Plane Wave Matrix Model (PWMM). The PWMM is a theory of supersymmetric quantum mechanics that has a well-defined canonical ensemble. We simulate this theory by applying rational hybrid Monte Carlo techniques to a naive lattice action. We examine the strong coupling behaviour of the model focussing on the deconfinement transition.Comment: v3 20 pages, 8 figures, comment adde

A Study of the Nambu--Jona-Lasinio Model on the Lattice

We present our full analysis of the two flavor Nambu--Jona-Lasinio model with $SU(2) \times SU(2)$ chiral symmetry on the four--dimensional hypercubic lattice with naive and Wilson fermions. We find that this model is an excellent toy field theory to investigate issues related to lattice QCD. We use the large $N$ approximation to leading order in $1/N$ to obtain non perturbative analytical results over almost the whole parameter range. By using numerical simulations we estimate that the size of the $1/N$ corrections for most of the quantities we consider are small and in this way we strengthen the validity of the leading order large $N$ calculations. We obtain results regarding the approach to the continuum chiral limit, the effects of the zero momentum fermionic modes on finite lattices and the scalar and pseudoscalar spectrum. Note: The full ps file of this preprint is also available via anonymous ftp to ftp.scri.fsu.edu. To get the ps file, ftp to this address and use for username "anonymous" and for password your complete E-mail address. The file is in the directory pub/vranas (to go to that directory type: cd pub/vranas) and is called NJL_long.ps (to get it type: get NJL_long.ps)Comment: 35 pages, LaTex file. (Added section with title: "The zero pion mass line on a finite lattice at large $N$".