17,539 research outputs found
The Dreaming Variational Autoencoder for Reinforcement Learning Environments
Reinforcement learning has shown great potential in generalizing over raw
sensory data using only a single neural network for value optimization. There
are several challenges in the current state-of-the-art reinforcement learning
algorithms that prevent them from converging towards the global optima. It is
likely that the solution to these problems lies in short- and long-term
planning, exploration and memory management for reinforcement learning
algorithms. Games are often used to benchmark reinforcement learning algorithms
as they provide a flexible, reproducible, and easy to control environment.
Regardless, few games feature a state-space where results in exploration,
memory, and planning are easily perceived. This paper presents The Dreaming
Variational Autoencoder (DVAE), a neural network based generative modeling
architecture for exploration in environments with sparse feedback. We further
present Deep Maze, a novel and flexible maze engine that challenges DVAE in
partial and fully-observable state-spaces, long-horizon tasks, and
deterministic and stochastic problems. We show initial findings and encourage
further work in reinforcement learning driven by generative exploration.Comment: Best Student Paper Award, Proceedings of the 38th SGAI International
Conference on Artificial Intelligence, Cambridge, UK, 2018, Artificial
Intelligence XXXV, 201
The Effects of Electrical Degradation on the Microstructure of Metal Oxide Varistor
In this paper, the findings from systematic experiments with the purpose to determine the degradation effect of single and multiple current pulses on the microstructure of the Metal Oxide (MO) varistor are described. Six distribution class varistors from one manufacturer were used in these experiments. The first part of the paper describes the electrical condition after application of single and multiple lightning current pulses. The results (before and after each elevated current impulse test) of 1mA AC reference voltage and residual voltage are presented in this section. We have also investigated a new technique called ‘Return Voltage Measurement’ for monitoring of the degradation in MO varistors. This is described in detail. The second part deals with the microstructure observations of MO varistors. The results of microstructural examination of impulse current on MO varsitors are examined in detail. This section also explains the relationship between the microstructural changes and electrical degradation of MO varistors
Temperature dependence of surface reconstructions of Au on Pd(110)
Surface reconstructions of Au film on Pd(110) substrate are studied using a
local Einstein approximation to quasiharmonic theory with the Sutton-Chen
interatomic potential. Temperature dependent surface free energies for
different coverages and surface structures are calculated. Experimentally
observed transformations from to and
structures can be explained in the framework of this model. Also conditions for
Stranski-Krastanov growth mode are found to comply with experiments. The domain
of validity of the model neglecting mixing entropy is analyzed.Comment: 7 pages, REVTeX two-column format, 3 postscript figures available on
request from [email protected] To appear in Phys. Rev. Letter
Evolution of the Pairwise Peculiar Velocity Distribution Function in Lagrangian Perturbation Theory
The statistical distribution of the radial pairwise peculiar velocity of
galaxies is known to have an exponential form as implied by observations and
explicitly shown in N-body simulations. Here we calculate its statistical
distribution function using the Zel'dovich approximation assuming that the
primordial density fluctuations are Gaussian distributed. We show that the
exponential distribution is realized as a transient phenomena on megaparsec
scales in the standard cold-dark-matter model.Comment: 19 pages, 8 Postscript figures, AAS LaTe
Josephson Coupling through a Quantum Dot
We derive, via fourth order perturbation theory, an expression for the
Josephson current through a gated interacting quantum dot. We analyze our
expression for two different models of the superconductor-dot-superconductor
(SDS) system. When the matrix elements connecting dot and leads are featureless
constants, we compute the Josephson coupling J_c as a function of the gate
voltage and Coulomb interaction. In the diffusive dot limit, we compute the
probability distribution P(J_c) of Josephson couplings. In both cases, pi
junction behavior (J_c < 0) is possible, and is not simply dependent on the
parity of the dot occupancy.Comment: 9 pages; 3 encapsulated PostScript figure
Iron redox systematics of martian magmas.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月18日(金) 国立国語研究所 2階講
Investigation of Diagnostic Techniques for Metal Oxide Surge Arresters
Gapless metal oxide surge arresters(MOSA)have been available in the market for many years since they were first introduced in the 1970's. The aim of this study is to investigate some reliable diagnostic techniques to assess the condition of a metal oxide surge arrester when subjected to severe lightning strikes in the field. A number of non-destructive and destructive diagnostic techniques for Metal Oxide Surge Arrester (MOSA) are discussed in this paper. The non-destructive techniques include the standard 1 mA reference voltage, lightning impulse discharge residual voltage and a number of modern diagnostics based on polarization methods: Return voltage and polarization/depolarization current measurements. In order to observe, analyze and correctly explain the degradation phenomena, a number of destructive techniques based on microstructure observation are also conducted. The techniques include optical microscopy, scanning electron microscopy, X-Ray diffraction and energy dispersive spectrometry. The single and multi-pulse currents of 8r20 s wave shape were used to artificially degrade the MOSA. The before and after diagnostic results of the non-destructive and destructive techniques are presented and interpreted to understand the aging mechanism in MOSA. The importance of modern non-destructive electrical diagnostics based on polarization methods is validated by test results and is highlighted in detail in this paper. Finally the correlation of the results of different diagnostic techniques with each other and with the results of standard techniques is discussed
Iron Redox Systematics of Martian Magmas
Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite [1]. Morris et al. [1] propose that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks [2,3]. Magnetite stability in terrestrial magmas is well understood, as are the stability of FeO and Fe2O3 in terrestrial magmas [4,5]. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas we have undertaken an experimental study with two emphases. First we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition. Second, we determine the FeO and Fe2O3 contents of the same shergottite bulk composition at 1 bar and variable fO2 at 1250 C, and at variable pressure. These two goals will help define not only magnetite stability, but pyroxene-melt equilibria that are also dependent upon fO2
Edge wetting of an Ising three-dimensional system
The effect of edge on wetting and layering transitions of a three-dimensional
spin-1/2 Ising model is investigated, in the presence of longitudinal and
surface magnetic fields, using mean field (MF) theory and Monte Carlo (MC)
simulations. For T=0, the ground state phase diagram shows that there exist
only three allowed transitions, namely: surface and bulk transition, surface
transition and bulk transition. However, there exist a surface intra-layering
temperature , above which the surface and the intra-layering surface
transitions occur. While the bulk layering and intra-layering transitions
appear above an other finite temperature . These
surface and bulk intra-layering transitions are not seen in the perfect
surfaces case.
Numerical values of and , computed by Monte Carlo
method are found to be smaller than those obtained using mean field theory.
However, the results predicted by the two methods become similar, and are
exactly those given by the ground state phase diagram, for very low
temperatures. On the other hand, the behavior of the local magnetizations as a
function of the external magnetic field, shows that the transitions are of the
first order type. and decrease when increasing the
system size and/or the surface magnetic field. In particular,
reaches the wetting temperature for sufficiently large system sizes.Comment: 11 Pages latex, 12 Figures P
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