Hybrid LQG-Neural Controller for Inverted Pendulum System

The paper presents a hybrid system controller, incorporating a neural and an LQG controller. The neural controller has been optimized by genetic algorithms directly on the inverted pendulum system. The failure free optimization process stipulated a relatively small region of the asymptotic stability of the neural controller, which is concentrated around the regulation point. The presented hybrid controller combines benefits of a genetically optimized neural controller and an LQG controller in a single system controller. High quality of the regulation process is achieved through utilization of the neural controller, while stability of the system during transient processes and a wide range of operation are assured through application of the LQG controller. The hybrid controller has been validated by applying it to a simulation model of an inherently unstable system of inverted pendulum

Jupiter's magnetopause, bow shock, and 10-hour modulated magnetosheath: Voyagers 1 and 2

Fine scale magnetic field data from the Voyager 1 and 2 magnetopause and bow shock crossings at Jupiter were analyzed. Explicit models of the dawnside magnetopause and bow shock in Jupiter's orbital plane employ an axisymmetric parabola and hyperbola, respectively, and are determined separately for the encounters. A new phenomenon was discovered in the magnetosheath. It is manifested as (5 or) 10 hour quasi-periodic modulation of the direction of the magnetic field in the outbound magnetosheath, predominantly in the northward (N) and southward (S) directions. It was seen to occur during both encounters and appears most evident in Voyager 2 outbound observations, probably due to the extreme tailward extent of the Voyager 2 trajectory through the magnetosheath. The durations of the N to and from S transitions range from tens of minutes to approximately 3 hours. The directional variation of the field during these transitions is fairly well restricted to a plane parallel to the local model magnetopause location. These signatures may be due to magnetosheath field line draping modulated by the large scale motion of the magnetospheric plasma disk

Solar Energetic Particle Events in the 23rd Solar Cycle: Interplanetary Magnetic Field Configuration and Statistical Relationship with Flares and CMEs

We study the influence of the large-scale interplanetary magnetic field configuration on the solar energetic particles (SEPs) as detected at different satellites near Earth and on the correlation of their peak intensities with the parent solar activity. We selected SEP events associated with X and M-class flares at western longitudes, in order to ensure good magnetic connection to Earth. These events were classified into two categories according to the global interplanetary magnetic field (IMF) configuration present during the SEP propagation to 1AU: standard solar wind or interplanetary coronal mass ejections (ICMEs). Our analysis shows that around 20% of all particle events are detected when the spacecraft is immersed in an ICME. The correlation of the peak particle intensity with the projected speed of the SEP-associated coronal mass ejection is similar in the two IMF categories of proton and electron events, $\approx 0.6$. The SEP events within ICMEs show stronger correlation between the peak proton intensity and the soft X-ray flux of the associated solar flare, with correlation coefficient $r=\,$0.67$\pm$0.13, compared to the SEP events propagating in the standard solar wind, $r=\,$0.36$\pm$0.13. The difference is more pronounced for near-relativistic electrons. The main reason for the different correlation behavior seems to be the larger spread of the flare longitude in the SEP sample detected in the solar wind as compared to SEP events within ICMEs. We discuss to which extent observational bias, different physical processes (particle injection, transport, etc.), and the IMF configuration can influence the relationship between SEPs and coronal activity.Comment: http://adsabs.harvard.edu.ezproxy.obspm.fr/abs/2013SoPh..282..579

Improved Templates for Photometric Redshifts of Submm Sources

There is growing evidence that some star-forming galaxies at z>1 are characterized by high efficiencies and specific star formation rates. In the local universe, these traits are shared by ``active'' Blue Compact Dwarf galaxies (BCDs) with compact and dense star-forming regions. The Spectral Energy Distributions (SEDs) of these BCDs are dominated by young massive star clusters, embedded in a cocoon of dust. In this Letter, we incorporate these BCD SEDs as templates for two samples of high-redshift galaxy populations selected at submm wavelengths. Because of the severe absorption of the optical light, the featureless mid-infrared spectrum, and the relatively flat radio continuum, the dusty star-cluster SEDs are good approximations to most of the submm sources in our samples. In most cases, the active BCD SEDs fit the observed photometric points better than the ``standard'' templates, M 82 and Arp 220, and predict photometric redshifts significantly closer to the spectroscopic ones. Our results strongly suggest that the embedded dusty star clusters in BCD galaxies are superior to other local templates such as M 82 and Arp 220 in fitting distant submm starburst galaxies.Comment: Accepted by ApJL: 4 pages, 2 figures, 2 table

Classical mappings of the symplectic model and their application to the theory of large-amplitude collective motion

We study the algebra Sp(n,R) of the symplectic model, in particular for the cases n=1,2,3, in a new way. Starting from the Poisson-bracket realization we derive a set of partial differential equations for the generators as functions of classical canonical variables. We obtain a solution to these equations that represents the classical limit of a boson mapping of the algebra. The relationship to the collective dynamics is formulated as a theorem that associates the mapping with an exact solution of the time-dependent Hartree approximation. This solution determines a decoupled classical symplectic manifold, thus satisfying the criteria that define an exactly solvable model in the theory of large amplitude collective motion. The models thus obtained also provide a test of methods for constructing an approximately decoupled manifold in fully realistic cases. We show that an algorithm developed in one of our earlier works reproduces the main results of the theorem.Comment: 23 pages, LaTeX using REVTeX 3.

Measuring collaborative emergent behavior in multi-agent reinforcement learning

Multi-agent reinforcement learning (RL) has important implications for the future of human-agent teaming. We show that improved performance with multi-agent RL is not a guarantee of the collaborative behavior thought to be important for solving multi-agent tasks. To address this, we present a novel approach for quantitatively assessing collaboration in continuous spatial tasks with multi-agent RL. Such a metric is useful for measuring collaboration between computational agents and may serve as a training signal for collaboration in future RL paradigms involving humans.Comment: 1st International Conference on Human Systems Engineering and Design, 6 pages, 2 figures, 1 tabl

The magnetoresistance tensor of La(0.8)Sr(0.2)MnO(3)

We measure the temperature dependence of the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in c-axis oriented epitaxial thin films of La(0.8)Sr(0.2)MnO(3), for different current directions relative to the crystal axes, and show that both AMR and PHE depend strongly on current orientation. We determine a magnetoresistance tensor, extracted to 4th order, which reflects the crystal symmetry and provides a comprehensive description of the data. We extend the applicability of the extracted tensor by determining the bi-axial magnetocrystalline anisotropy in our samples

The homotopy invariance of the string topology loop product and string bracket

Let M be a closed, oriented, n -manifold, and LM its free loop space. Chas and Sullivan defined a commutative algebra structure in the homology of LM, and a Lie algebra structure in its equivariant homology. These structures are known as the string topology loop product and string bracket, respectively. In this paper we prove that these structures are homotopy invariants in the following sense. Let f : M_1 \to M_2 be a homotopy equivalence of closed, oriented n -manifolds. Then the induced equivalence, Lf : LM_1 \to LM_2 induces a ring isomorphism in homology, and an isomorphism of Lie algebras in equivariant homology. The analogous statement also holds true for any generalized homology theory h_* that supports an orientation of the M_i 's.Comment: 21 pages, 2 figures final version published in Journal of Topolog

Photoproduction of Quarkonium in Proton-Proton and Nucleus-Nucleus Collisions

We discuss the photoproduction of $\Upsilon$ and $J/\psi$ at high energy $\bar{p}p$, $pp$ and heavy ion colliders. We predict large rates in $\bar{p}p$ interactions at the Fermilab Tevatron %and in heavy-ion interactions at the CERN LHC. These reactions can be and in $pp$ and heavy-ion interactions at the CERN LHC. The $J/\psi$ is also produced copiously at RHIC. These reactions can be used to study the gluon distribution in protons and heavy nuclei. We also show that the different CP symmetries of the initial states lead to large differences in the transverse momentum spectra of mesonsComment: 4 pgs. with 3 figure