2,675 research outputs found
Highlights from TeV Extragalactic Sources
The number of discovered TeV sources populating the extragalactic sky in 2017
is nearly 70, mostly blazars located up to a redshift ~1. Ten years ago, in
2007, less than 20 TeV emitters were known, up to a maximum redshift of 0.2.
This is a major achievement of current generation of Cherenkov telescopes
operating in synergy with optical, X-ray, and GeV gamma-ray telescopes. A
review of selected results from the extragalactic TeV sky is presented, with
particular emphasis on recently detected distant sources.Comment: 12 pages, invited review talk at the conference: Moriond 2017 (VHE
Phenomena in the Universe). New version with a minor correction and one
reference update
Regularized Jacobi iteration for decentralized convex optimization with separable constraints
We consider multi-agent, convex optimization programs subject to separable
constraints, where the constraint function of each agent involves only its
local decision vector, while the decision vectors of all agents are coupled via
a common objective function. We focus on a regularized variant of the so called
Jacobi algorithm for decentralized computation in such problems. We first
consider the case where the objective function is quadratic, and provide a
fixed-point theoretic analysis showing that the algorithm converges to a
minimizer of the centralized problem. Moreover, we quantify the potential
benefits of such an iterative scheme by comparing it against a scaled projected
gradient algorithm. We then consider the general case and show that all limit
points of the proposed iteration are optimal solutions of the centralized
problem. The efficacy of the proposed algorithm is illustrated by applying it
to the problem of optimal charging of electric vehicles, where, as opposed to
earlier approaches, we show convergence to an optimal charging scheme for a
finite, possibly large, number of vehicles
Sampling-based optimal kinodynamic planning with motion primitives
This paper proposes a novel sampling-based motion planner, which integrates
in RRT* (Rapidly exploring Random Tree star) a database of pre-computed motion
primitives to alleviate its computational load and allow for motion planning in
a dynamic or partially known environment. The database is built by considering
a set of initial and final state pairs in some grid space, and determining for
each pair an optimal trajectory that is compatible with the system dynamics and
constraints, while minimizing a cost. Nodes are progressively added to the tree
{of feasible trajectories in the RRT* by extracting at random a sample in the
gridded state space and selecting the best obstacle-free motion primitive in
the database that joins it to an existing node. The tree is rewired if some
nodes can be reached from the new sampled state through an obstacle-free motion
primitive with lower cost. The computationally more intensive part of motion
planning is thus moved to the preliminary offline phase of the database
construction at the price of some performance degradation due to gridding. Grid
resolution can be tuned so as to compromise between (sub)optimality and size of
the database. The planner is shown to be asymptotically optimal as the grid
resolution goes to zero and the number of sampled states grows to infinity
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