84,262 research outputs found
DropIn: Making Reservoir Computing Neural Networks Robust to Missing Inputs by Dropout
The paper presents a novel, principled approach to train recurrent neural
networks from the Reservoir Computing family that are robust to missing part of
the input features at prediction time. By building on the ensembling properties
of Dropout regularization, we propose a methodology, named DropIn, which
efficiently trains a neural model as a committee machine of subnetworks, each
capable of predicting with a subset of the original input features. We discuss
the application of the DropIn methodology in the context of Reservoir Computing
models and targeting applications characterized by input sources that are
unreliable or prone to be disconnected, such as in pervasive wireless sensor
networks and ambient intelligence. We provide an experimental assessment using
real-world data from such application domains, showing how the Dropin
methodology allows to maintain predictive performances comparable to those of a
model without missing features, even when 20\%-50\% of the inputs are not
available
Competing coherent and dissipative dynamics close to quantum criticality
We investigate the competition of coherent and dissipative dynamics in
many-body systems at continuous quantum transitions. We consider dissipative
mechanisms that can be effectively described by Lindblad equations for the
density matrix of the system. The interplay between the critical coherent
dynamics and dissipation is addressed within a dynamic finite-size scaling
framework, which allows us to identify the regime where they develop a
nontrivial competition. We analyze protocols that start from critical many-body
ground states and put forward general dynamic scaling behaviors involving the
Hamiltonian parameters and the coupling associated with the dissipation. This
scaling scenario is supported by a numerical study of the dynamic behavior of a
one-dimensional lattice fermion gas undergoing a quantum Ising transition in
the presence of dissipative mechanisms such as local pumping, decaying, and
dephasing.Comment: 9 pages, 4 figure
Shape-from-intrinsic operator
Shape-from-X is an important class of problems in the fields of geometry
processing, computer graphics, and vision, attempting to recover the structure
of a shape from some observations. In this paper, we formulate the problem of
shape-from-operator (SfO), recovering an embedding of a mesh from intrinsic
differential operators defined on the mesh. Particularly interesting instances
of our SfO problem include synthesis of shape analogies, shape-from-Laplacian
reconstruction, and shape exaggeration. Numerically, we approach the SfO
problem by splitting it into two optimization sub-problems that are applied in
an alternating scheme: metric-from-operator (reconstruction of the discrete
metric from the intrinsic operator) and embedding-from-metric (finding a shape
embedding that would realize a given metric, a setting of the multidimensional
scaling problem)
Ratiometric control for differentiation of cell populations endowed with synthetic toggle switches
We consider the problem of regulating by means of external control inputs the
ratio of two cell populations. Specifically, we assume that these two cellular
populations are composed of cells belonging to the same strain which embeds
some bistable memory mechanism, e.g. a genetic toggle switch, allowing them to
switch role from one population to another in response to some inputs. We
present three control strategies to regulate the populations' ratio to
arbitrary desired values which take also into account realistic physical and
technological constraints occurring in experimental microfluidic platforms. The
designed controllers are then validated in-silico using stochastic agent-based
simulations.Comment: Accepted to CDC'201
PAMPC: Perception-Aware Model Predictive Control for Quadrotors
We present the first perception-aware model predictive control framework for
quadrotors that unifies control and planning with respect to action and
perception objectives. Our framework leverages numerical optimization to
compute trajectories that satisfy the system dynamics and require control
inputs within the limits of the platform. Simultaneously, it optimizes
perception objectives for robust and reliable sens- ing by maximizing the
visibility of a point of interest and minimizing its velocity in the image
plane. Considering both perception and action objectives for motion planning
and control is challenging due to the possible conflicts arising from their
respective requirements. For example, for a quadrotor to track a reference
trajectory, it needs to rotate to align its thrust with the direction of the
desired acceleration. However, the perception objective might require to
minimize such rotation to maximize the visibility of a point of interest. A
model-based optimization framework, able to consider both perception and action
objectives and couple them through the system dynamics, is therefore necessary.
Our perception-aware model predictive control framework works in a
receding-horizon fashion by iteratively solving a non-linear optimization
problem. It is capable of running in real-time, fully onboard our lightweight,
small-scale quadrotor using a low-power ARM computer, to- gether with a
visual-inertial odometry pipeline. We validate our approach in experiments
demonstrating (I) the contradiction between perception and action objectives,
and (II) improved behavior in extremely challenging lighting conditions
Aggressive Quadrotor Flight through Narrow Gaps with Onboard Sensing and Computing using Active Vision
We address one of the main challenges towards autonomous quadrotor flight in
complex environments, which is flight through narrow gaps. While previous works
relied on off-board localization systems or on accurate prior knowledge of the
gap position and orientation, we rely solely on onboard sensing and computing
and estimate the full state by fusing gap detection from a single onboard
camera with an IMU. This problem is challenging for two reasons: (i) the
quadrotor pose uncertainty with respect to the gap increases quadratically with
the distance from the gap; (ii) the quadrotor has to actively control its
orientation towards the gap to enable state estimation (i.e., active vision).
We solve this problem by generating a trajectory that considers geometric,
dynamic, and perception constraints: during the approach maneuver, the
quadrotor always faces the gap to allow state estimation, while respecting the
vehicle dynamics; during the traverse through the gap, the distance of the
quadrotor to the edges of the gap is maximized. Furthermore, we replan the
trajectory during its execution to cope with the varying uncertainty of the
state estimate. We successfully evaluate and demonstrate the proposed approach
in many real experiments. To the best of our knowledge, this is the first work
that addresses and achieves autonomous, aggressive flight through narrow gaps
using only onboard sensing and computing and without prior knowledge of the
pose of the gap
Generalized Riemann hypotheses: sufficient and equivalent criteria
This paper presents new sufficient and equivalent conditions for the
generalized version of the Riemann Hypothesis. The paper derives also
statements and remarks concerning zero-free regions, modified Hadamard-product
formulas and the behaviour of .Comment: Few changes. Accepted for publication in JP Journal of Algebra,
Number Theory and Application
Knowledge and the Importance of Being Right
Some philosophers have recently argued that whether a true belief amounts to knowledge in a specific circumstance depends on features of the subject’s practical situation that are unrelated to the truth of the subject’s belief, such as the costs for the subject of being wrong about whether the believed proposition is true. One of the best-known arguments used to support this view is that it best explains a number of paradigmatic cases, such as the well-known Bank Case, in which a difference in knowledge occurs in subjects differing exclusively with respect to their practical situation. I suggest an alternative explanation of such cases. My explanation has a disjunctive character: on the one hand, it accounts for cases in which the subject is aware of the costs of being wrong in a given situation in terms of the influence of psychological factors on her mechanisms of belief-formation and revision. On the other hand, it accounts for cases in which the subject is ignorant of the costs of being wrong in her situation by imposing a new condition on knowledge. This condition is that one knows that p only if one does not underestimate the importance of being right about whether p. I argue that my explanation has a number of advantages over other invariantist explanations: it accounts for all the relevant cases preserving the semantic significance of our ordinary intuitions, it is compatible with an intellectualist account of knowledge and it escapes several problems affecting competing views
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