1,953 research outputs found
Inverse Optimal Planning for Air Traffic Control
We envision a system that concisely describes the rules of air traffic
control, assists human operators and supports dense autonomous air traffic
around commercial airports. We develop a method to learn the rules of air
traffic control from real data as a cost function via maximum entropy inverse
reinforcement learning. This cost function is used as a penalty for a
search-based motion planning method that discretizes both the control and the
state space. We illustrate the methodology by showing that our approach can
learn to imitate the airport arrival routes and separation rules of dense
commercial air traffic. The resulting trajectories are shown to be safe,
feasible, and efficient
Investigating hybrids of evolution and learning for real-parameter optimization
In recent years, more and more advanced techniques have been developed in the field
of hybridizing of evolution and learning, this means that more applications with these techniques
can benefit from this progress. One example of these advanced techniques is the
Learnable Evolution Model (LEM), which adopts learning as a guide for the general evolutionary
search. Despite this trend and the progress in LEM, there are still many ideas and
attempts which deserve further investigations and tests. For this purpose, this thesis has
developed a number of new algorithms attempting to combine more learning algorithms
with evolution in different ways. With these developments, we expect to understand the
effects and relations between evolution and learning, and also achieve better performances
in solving complex problems.
The machine learning algorithms combined into the standard Genetic Algorithm (GA)
are the supervised learning method k-nearest-neighbors (KNN), the Entropy-Based Discretization
(ED) method, and the decision tree learning algorithm ID3. We test these algorithms
on various real-parameter function optimization problems, especially the functions
in the special session on CEC 2005 real-parameter function optimization. Additionally, a
medical cancer chemotherapy treatment problem is solved in this thesis by some of our
hybrid algorithms.
The performances of these algorithms are compared with standard genetic algorithms
and other well-known contemporary evolution and learning hybrid algorithms. Some of
them are the CovarianceMatrix Adaptation Evolution Strategies (CMAES), and variants of
the Estimation of Distribution Algorithms (EDA).
Some important results have been derived from our experiments on these developed algorithms.
Among them, we found that even some very simple learning methods hybridized
properly with evolution procedure can provide significant performance improvement; and
when more complex learning algorithms are incorporated with evolution, the resulting algorithms
are very promising and compete very well against the state of the art hybrid algorithms
both in well-defined real-parameter function optimization problems and a practical
evaluation-expensive problem
Deterministic Policy Optimization by Combining Pathwise and Score Function Estimators for Discrete Action Spaces
Policy optimization methods have shown great promise in solving complex
reinforcement and imitation learning tasks. While model-free methods are
broadly applicable, they often require many samples to optimize complex
policies. Model-based methods greatly improve sample-efficiency but at the cost
of poor generalization, requiring a carefully handcrafted model of the system
dynamics for each task. Recently, hybrid methods have been successful in
trading off applicability for improved sample-complexity. However, these have
been limited to continuous action spaces. In this work, we present a new hybrid
method based on an approximation of the dynamics as an expectation over the
next state under the current policy. This relaxation allows us to derive a
novel hybrid policy gradient estimator, combining score function and pathwise
derivative estimators, that is applicable to discrete action spaces. We show
significant gains in sample complexity, ranging between and ,
when learning parameterized policies on Cart Pole, Acrobot, Mountain Car and
Hand Mass. Our method is applicable to both discrete and continuous action
spaces, when competing pathwise methods are limited to the latter.Comment: In AAAI 2018 proceeding
Optimal Aerodynamic Design of a Transonic Centrifugal Turbine Stage for Organic Rankine Cycle Applications
This paper presents the results of the application of a shape-optimization technique to the design of the stator and the rotor of a centrifugal turbine conceived for Organic Rankine Cycle (ORC) applications. Centrifugal turbines have the potential to compete with axial or radial-inflow turbines in a relevant range of applications, and are now receiving scientific as well as industrial recognition. However, the non-conventional character of the centrifugal turbine layout, combined with the typical effects induced by the use of organic fluids, leads to challenging design difficulties. For this reason, the design of optimal blades for centrifugal ORC turbines demands the application of high-fidelity computational tools. In this work, the optimal aerodynamic design is achieved by applying a non-intrusive, gradient-free, CFD-based method implemented in the in-house software FORMA (Fluid-dynamic Opti-mizeR for turboMachinery Aerofoils), specifically developed for the shape optimization of turbomachinery profiles. FORMA was applied to optimize the shape of the stator and the rotor of a transonic centrifugal turbine stage, which exhibits a significant radial effect, high aerodynamic loading, and severe non-ideal gas effects. The optimization of the single blade rows allows improving considerably the stage performance, with respect to a baseline geometric configuration constructed with classical aerodynamic methods. Furthermore, time-resolved simulations of the coupled stator-rotor configuration shows that the optimization allows to reduce considerably the unsteady stator-rotor interaction and, thus, the aerodynamic forcing acting on the blades
Towards Recommendations for Value Sensitive Sustainable Consumption
Excessive consumption can strain natural resources, harm the environment, and widen societal gaps. While adopting a more sustainable lifestyle means making significant changes and potentially compromising personal desires, balancing sustainability with personal values poses a complex challenge. This article delves into designing recommender systems using neural networks and genetic algorithms, aiming to assist consumers in shopping sustainably without disregarding their individual preferences. We approach the search for good recommendations as a problem involving multiple objectives, representing diverse sustainability goals and personal values. While using a synthetic historical dataset based on real-world sources, our evaluations reveal substantial environmental benefits without demanding drastic personal sacrifices, even if consumers accept only a fraction of the recommendations
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