16,811 research outputs found
In vitro 14 C-glycine incorporation into protein of denervated rat muscle, effect of nandrolonedecanoate
Safe Controller Optimization for Quadrotors with Gaussian Processes
One of the most fundamental problems when designing controllers for dynamic
systems is the tuning of the controller parameters. Typically, a model of the
system is used to obtain an initial controller, but ultimately the controller
parameters must be tuned manually on the real system to achieve the best
performance. To avoid this manual tuning step, methods from machine learning,
such as Bayesian optimization, have been used. However, as these methods
evaluate different controller parameters on the real system, safety-critical
system failures may happen. In this paper, we overcome this problem by
applying, for the first time, a recently developed safe optimization algorithm,
SafeOpt, to the problem of automatic controller parameter tuning. Given an
initial, low-performance controller, SafeOpt automatically optimizes the
parameters of a control law while guaranteeing safety. It models the underlying
performance measure as a Gaussian process and only explores new controller
parameters whose performance lies above a safe performance threshold with high
probability. Experimental results on a quadrotor vehicle indicate that the
proposed method enables fast, automatic, and safe optimization of controller
parameters without human intervention.Comment: IEEE International Conference on Robotics and Automation, 2016. 6
pages, 4 figures. A video of the experiments can be found at
http://tiny.cc/icra16_video . A Python implementation of the algorithm is
available at https://github.com/befelix/SafeOp
Recommended from our members
On the boundary-layer structure of high-Prandtl-number horizontal convection
A Small Cosmological Constant and Backreaction of Non-Finetuned Parameters
We include the backreaction on the warped geometry induced by non-finetuned
parameters in a two domain-wall set-up to obtain an exponentially small
Cosmological Constant . The mechanism to suppress the Cosmological
Constant involves one classical fine-tuning as compared to an infinity of
finetunings at the quantum level in standard D=4 field theory.Comment: 13 pages, minor corrections and references adde
Peak wind speed anemometers /maxometer/ Final report, 26 Mar. 1969 - 25 May 1970
Fabrication and testing of peak wind speed recording devic
Spontaneous centralization of control in a network of company ownerships
We introduce a model for the adaptive evolution of a network of company
ownerships. In a recent work it has been shown that the empirical global
network of corporate control is marked by a central, tightly connected "core"
made of a small number of large companies which control a significant part of
the global economy. Here we show how a simple, adaptive "rich get richer"
dynamics can account for this characteristic, which incorporates the increased
buying power of more influential companies, and in turn results in even higher
control. We conclude that this kind of centralized structure can emerge without
it being an explicit goal of these companies, or as a result of a
well-organized strategy.Comment: 5 Pages, 7 figure
Fairness Behind a Veil of Ignorance: A Welfare Analysis for Automated Decision Making
We draw attention to an important, yet largely overlooked aspect of
evaluating fairness for automated decision making systems---namely risk and
welfare considerations. Our proposed family of measures corresponds to the
long-established formulations of cardinal social welfare in economics, and is
justified by the Rawlsian conception of fairness behind a veil of ignorance.
The convex formulation of our welfare-based measures of fairness allows us to
integrate them as a constraint into any convex loss minimization pipeline. Our
empirical analysis reveals interesting trade-offs between our proposal and (a)
prediction accuracy, (b) group discrimination, and (c) Dwork et al.'s notion of
individual fairness. Furthermore and perhaps most importantly, our work
provides both heuristic justification and empirical evidence suggesting that a
lower-bound on our measures often leads to bounded inequality in algorithmic
outcomes; hence presenting the first computationally feasible mechanism for
bounding individual-level inequality.Comment: Conference: Thirty-second Conference on Neural Information Processing
Systems (NIPS 2018
A Moral Framework for Understanding of Fair ML through Economic Models of Equality of Opportunity
We map the recently proposed notions of algorithmic fairness to economic
models of Equality of opportunity (EOP)---an extensively studied ideal of
fairness in political philosophy. We formally show that through our conceptual
mapping, many existing definition of algorithmic fairness, such as predictive
value parity and equality of odds, can be interpreted as special cases of EOP.
In this respect, our work serves as a unifying moral framework for
understanding existing notions of algorithmic fairness. Most importantly, this
framework allows us to explicitly spell out the moral assumptions underlying
each notion of fairness, and interpret recent fairness impossibility results in
a new light. Last but not least and inspired by luck egalitarian models of EOP,
we propose a new family of measures for algorithmic fairness. We illustrate our
proposal empirically and show that employing a measure of algorithmic
(un)fairness when its underlying moral assumptions are not satisfied, can have
devastating consequences for the disadvantaged group's welfare
Electrodynamic Structure of an Outer Gap Accelerator: Location of the Gap and the Gamma-ray Emission from the Crab Pulsar
We investigate a stationary pair production cascade in the outer
magnetosphere of a spinning neutron star. The charge depletion due to global
flows of charged particles, causes a large electric field along the magnetic
field lines. Migratory electrons and/or positrons are accelerated by this field
to radiate curvature gamma-rays, some of which collide with the X-rays to
materialize as pairs in the gap. The replenished charges partially screen the
electric field, which is self-consistently solved together with the
distribution functions of particles and gamma-rays. If no current is injected
at neither of the boundaries of the accelerator, the gap is located around the
conventional null surface, where the local Goldreich-Julian charge density
vanishes. However, we first find that the gap position shifts outwards (or
inwards) when particles are injected at the inner (or outer) boundary. Applying
the theory to the Crab pulsar, we demonstrate that the pulsed TeV flux does not
exceed the observational upper limit for moderate infrared photon density and
that the gap should be located near to or outside of the conventional null
surface so that the observed spectrum of pulsed GeV fluxes may be emitted via a
curvature process. Some implications of the existence of a solution for a super
Goldreich-Julian current are discussed.Comment: 17 pages, 12 figures, submitted to Ap
- …