Learning 3D Navigation Protocols on Touch Interfaces with Cooperative Multi-Agent Reinforcement Learning

Using touch devices to navigate in virtual 3D environments such as computer assisted design (CAD) models or geographical information systems (GIS) is inherently difficult for humans, as the 3D operations have to be performed by the user on a 2D touch surface. This ill-posed problem is classically solved with a fixed and handcrafted interaction protocol, which must be learned by the user. We propose to automatically learn a new interaction protocol allowing to map a 2D user input to 3D actions in virtual environments using reinforcement learning (RL). A fundamental problem of RL methods is the vast amount of interactions often required, which are difficult to come by when humans are involved. To overcome this limitation, we make use of two collaborative agents. The first agent models the human by learning to perform the 2D finger trajectories. The second agent acts as the interaction protocol, interpreting and translating to 3D operations the 2D finger trajectories from the first agent. We restrict the learned 2D trajectories to be similar to a training set of collected human gestures by first performing state representation learning, prior to reinforcement learning. This state representation learning is addressed by projecting the gestures into a latent space learned by a variational auto encoder (VAE).Comment: 17 pages, 8 figures. Accepted at The European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases 2019 (ECMLPKDD 2019

Wave Profile for Breakdown Waves with a Large Current Behind the Wave Front

For analytical solution of breakdown waves with a large current behind the wave front, we employ a one-dimensional, steady-state, three-component (electrons, ions, and neutral particles) fluid model. This project involves breakdown waves propagating in the opposite direction of the electric field force on electrons, anti-force waves (return stroke in lightning); and the electron gas partial pressure is considered to provide the driving force for the propagation of the wave. The basic set of equations consists of the equation of conservation of mass flux, equation of conservation of momentum, equation of conservation of energy, plus Poisson’s equation. The waves are considered to have a shock front. In this study, we examine the possibility and validity of large currents measured and reported by few investigators. Existence of a relationship between wave speed and peak current values is investigated as well. Existence of a large current behind the wave front alters the equation of conservation of energy and Poisson’s equation, as well as the shock boundary condition on electron temperature. Considering a current behind the shock front, we have made appropriate modifications in our set of electron fluid dynamical equations. Using the modified set of equations and the shock condition on electron temperature, we have been able to integrate the set of electron fluid dynamical equations for current bearing anti-force waves. For a range of wave speeds and with the largest current possible for a specific wave speed, we present the wave profile for electric field, electron velocity, and the ionization rate within the dynamical transition region of the wave for anti-force waves

Consistency of parity-violating pion-nucleon couplings extracted from measurements in 18F and 133Cs

The recent measurement of the nuclear anapole moment of 133Cs has been interpreted to yield a value of the weak pion-nucleon coupling H_pi^1 which contradicts the upper limit from the 18F experiments. We argue that because of the sensitivity of the anapole moment to H_rho^0 in the odd proton nucleus 133Cs, there is a combination of weak meson-nucleon couplings which satisfies both experiments and which is (barely) in agreement with theory. In addition, the anapole moment measurement in 205Tl gives a constraint which is inconsistent with the value from 133Cs, calling into question the theory of nuclear anapole moments. We argue that measurements of directional asymmetry in n+p-->d+gamma and in the photo-disintegration of the deuteron by circularly polarized photons, combined with results from pp scattering, would determine H_pi^1 and several other weak meson-nucleon couplings in a model-independent way.Comment: 9 pages, RevTeX, 1 figure, eps, submitted to Phys. Rev.

Critical Points in the Linear Sigma Model with Quarks

We employ a simple effective model to study the chiral dynamics of two flavors of quarks at finite temperature and density. In particular, we determine the phase diagram in the plane of temperature and baryon chemical potential as a function of the pion mass. An interesting phase structure occurs which results in zero, one or two critical points depending on the value of the vacuum pion mass.Comment: 16 pages plus 5 figure