25,481 research outputs found
Comparing policy gradient and value function based reinforcement learning methods in simulated electrical power trade
In electrical power engineering, reinforcement learning algorithms can be used to model the strategies of electricity market participants. However, traditional value function based reinforcement learning algorithms suffer from convergence issues when used with value function approximators. Function approximation is required in this domain to capture the characteristics of the complex and continuous multivariate problem space. The contribution of this paper is the comparison of policy gradient reinforcement learning methods, using artificial neural networks for policy function approximation, with traditional value function based methods in simulations of electricity trade. The methods are compared using an AC optimal power flow based power exchange auction market model and a reference electric power system model
Color Transparency at COMPASS - Feasibility Study
We examine the potential of the COMPASS experiment at CERN to study color
transparency via exclusive vector meson production in hard muon-nucleus
scattering. It is demonstrated that COMPASS has high sensitivity to test this
important prediction of perturbative QCD.Comment: Expanded version of the talk presented at the Workshop on "Nucleon
Structure and Meson Spectroscopy", Dubna, Russia, 10-11 October 200
Development of electrical test procedures for qualification of spacecraft against EID. Volume 2: Review and specification of test procedures
A combined experimental and analytical program to develop system electrical test procedures for the qualification of spacecraft against damage produced by space-electron-induced discharges (EID) occurring on spacecraft dielectric outer surfaces is described. A review and critical evaluation of possible approaches to qualify spacecraft against space electron-induced discharges (EID) is presented. A variety of possible schemes to simulate EID electromagnetic effects produced in spacecraft was studied. These techniques form the principal element of a provisional, recommended set of test procedures for the EID qualification spacecraft. Significant gaps in our knowledge about EID which impact the final specification of an electrical test to qualify spacecraft against EID are also identified
Control and structural optimization for maneuvering large spacecraft
Presented here are the results of an advanced control design as well as a discussion of the requirements for automating both the structures and control design efforts for maneuvering a large spacecraft. The advanced control application addresses a general three dimensional slewing problem, and is applied to a large geostationary platform. The platform consists of two flexible antennas attached to the ends of a flexible truss. The control strategy involves an open-loop rigid body control profile which is derived from a nonlinear optimal control problem and provides the main control effort. A perturbation feedback control reduces the response due to the flexibility of the structure. Results are shown which demonstrate the usefulness of the approach. Software issues are considered for developing an integrated structures and control design environment
Boosting the Standard Model Higgs Signal with the Template Overlap Method
We show that the Template Overlap Method can improve the signal to background
ratio of boosted events produced in association with a
leptonically decaying . We introduce several improvements on the previous
formulations of the template method. Varying three-particle template subcones
increases the rejection power against the backgrounds, while sequential
template generation ensures an efficient coverage in template phase space. We
integrate b-tagging information into the template overlap framework and
introduce a new template based observable, the template stretch. Our analysis
takes into account the contamination from the charm daughters of top decays in
events, and includes nearly-realistic effects of pileup and
underlying events. We show that the Template Overlap Method displays very low
sensitivity to pileup, hence providing a self-contained alternative to other
methods of pile up subtraction. The developments described in this work are
quite general, and may apply to other searches for massive boosted objects.Comment: 28 pages, 35 figures; references added, minor revisions, to appear in
JHE
Reinforcement Learning for UAV Attitude Control
Autopilot systems are typically composed of an "inner loop" providing
stability and control, while an "outer loop" is responsible for mission-level
objectives, e.g. way-point navigation. Autopilot systems for UAVs are
predominately implemented using Proportional, Integral Derivative (PID) control
systems, which have demonstrated exceptional performance in stable
environments. However more sophisticated control is required to operate in
unpredictable, and harsh environments. Intelligent flight control systems is an
active area of research addressing limitations of PID control most recently
through the use of reinforcement learning (RL) which has had success in other
applications such as robotics. However previous work has focused primarily on
using RL at the mission-level controller. In this work, we investigate the
performance and accuracy of the inner control loop providing attitude control
when using intelligent flight control systems trained with the state-of-the-art
RL algorithms, Deep Deterministic Gradient Policy (DDGP), Trust Region Policy
Optimization (TRPO) and Proximal Policy Optimization (PPO). To investigate
these unknowns we first developed an open-source high-fidelity simulation
environment to train a flight controller attitude control of a quadrotor
through RL. We then use our environment to compare their performance to that of
a PID controller to identify if using RL is appropriate in high-precision,
time-critical flight control.Comment: 13 pages, 9 figure
Measurement of Neutrino-Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor
The elastic scattering cross-section was measured with
a CsI(Tl) scintillating crystal array having a total mass of 187kg. The
detector was exposed to an average reactor flux of
at the Kuo-Sheng Nuclear Power
Station. The experimental design, conceptual merits, detector hardware, data
analysis and background understanding of the experiment are presented. Using
29882/7369 kg-days of Reactor ON/OFF data, the Standard Model(SM) electroweak
interaction was probed at the squared 4-momentum transfer range of . The ratio of experimental to SM cross-sections
of was measured. Constraints on
the electroweak parameters were placed, corresponding to a weak
mixing angle measurement of \s2tw = 0.251 \pm 0.031({\it stat}) \pm
0.024({\it sys}) . Destructive interference in the SM \nuebar -e process was
verified. Bounds on anomalous neutrino electromagnetic properties were placed:
neutrino magnetic moment at \mu_{\nuebar}< 2.2 \times 10^{-10} \mu_{\rm B}
and the neutrino charge radius at -2.1 \times 10^{-32} ~{\rm cm^{2}} <
\nuchrad < 3.3 \times 10^{-32} ~{\rm cm^{2}}, both at 90% confidence level.Comment: 18 Figures, 7 Tables; published version as V2 with minor revision
from V
Adaptive Robust Optimization with Dynamic Uncertainty Sets for Multi-Period Economic Dispatch under Significant Wind
The exceptional benefits of wind power as an environmentally responsible
renewable energy resource have led to an increasing penetration of wind energy
in today's power systems. This trend has started to reshape the paradigms of
power system operations, as dealing with uncertainty caused by the highly
intermittent and uncertain wind power becomes a significant issue. Motivated by
this, we present a new framework using adaptive robust optimization for the
economic dispatch of power systems with high level of wind penetration. In
particular, we propose an adaptive robust optimization model for multi-period
economic dispatch, and introduce the concept of dynamic uncertainty sets and
methods to construct such sets to model temporal and spatial correlations of
uncertainty. We also develop a simulation platform which combines the proposed
robust economic dispatch model with statistical prediction tools in a rolling
horizon framework. We have conducted extensive computational experiments on
this platform using real wind data. The results are promising and demonstrate
the benefits of our approach in terms of cost and reliability over existing
robust optimization models as well as recent look-ahead dispatch models.Comment: Accepted for publication at IEEE Transactions on Power System
Radiative Transfer Modeling of Lyman Alpha Emitters. II. New Effects in Galaxy Clustering
We study the clustering properties of z~5.7 Lyman-alpha emitters (LAEs) in a
cosmological reionization simulation with a full Lya radiative transfer
calculation. Lya radiative transfer substantially modifies the intrinsic Lya
emission properties, compared to observed ones, depending on the density and
velocity structure environment around the Lya emitting galaxy. This
environment-dependent Lya selection introduces new features in LAE clustering,
suppressing (enhancing) the line-of-sight (transverse) density fluctuations and
giving rise to scale-dependent galaxy bias. In real space, the contours of the
three-dimensional two-point correlation function of LAEs appear to be
prominently elongated along the line of sight on large scales, an effect that
is opposite to and much stronger than the linear redshift-space distortion
effect. The projected two-point correlation function is greatly enhanced in
amplitude by a factor of up to a few, compared to the case without the
environment dependent selection effect. The new features in LAE clustering can
be understood with a simple, physically motivated model, where Lya selection
depends on matter density, velocity, and their gradients. We discuss the
implications and consequences of the effects on galaxy clustering from Lya
selection in interpreting clustering measurements and in constraining cosmology
and reionization from LAEs.Comment: 31 pages, 26 figures, revised according to the referee's comments,
more discussions and tests, published in Ap
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