743 research outputs found
Combinatorial Tools for Regge Calculus
In this short note we briefly review some recent mathematical results
relevant to the classical Regge Calculus evolution problem.Comment: 5 pages, LaTeX, no figures. To appear on the Proceedings of the 12th
Italian Conference on General Relativity and Gravitational Physic
The Use of HepRep in GLAST
HepRep is a generic, hierarchical format for description of graphics
representables that can be augmented by physics information and relational
properties. It was developed for high energy physics event display applications
and is especially suited to client/server or component frameworks. The GLAST
experiment, an international effort led by NASA for a gamma-ray telescope to
launch in 2006, chose HepRep to provide a flexible, extensible and maintainable
framework for their event display without tying their users to any one graphics
application. To support HepRep in their GUADI infrastructure, GLAST developed a
HepRep filler and builder architecture. The architecture hides the details of
XML and CORBA in a set of base and helper classes allowing physics experts to
focus on what data they want to represent. GLAST has two GAUDI services:
HepRepSvc, which registers HepRep fillers in a global registry and allows the
HepRep to be exported to XML, and CorbaSvc, which allows the HepRep to be
published through a CORBA interface and which allows the client application to
feed commands back to GAUDI (such as start next event, or run some GAUDI
algorithm). GLAST's HepRep solution gives users a choice of client
applications, WIRED (written in Java) or FRED (written in C++ and Ruby), and
leaves them free to move to any future HepRep-compliant event display.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 9 pages pdf, 15 figures. PSN THLT00
Distributed interpolatory algorithms for set membership estimation
This work addresses the distributed estimation problem in a set membership
framework. The agents of a network collect measurements which are affected by
bounded errors, thus implying that the unknown parameters to be estimated
belong to a suitable feasible set. Two distributed algorithms are considered,
based on projections of the estimate of each agent onto its local feasible set.
The main contribution of the paper is to show that such algorithms are
asymptotic interpolatory estimators, i.e. they converge to an element of the
global feasible set, under the assumption that the feasible set associated to
each measurement is convex. The proposed techniques are demonstrated on a
distributed linear regression estimation problem
A Distributed Asynchronous Method of Multipliers for Constrained Nonconvex Optimization
This paper presents a fully asynchronous and distributed approach for
tackling optimization problems in which both the objective function and the
constraints may be nonconvex. In the considered network setting each node is
active upon triggering of a local timer and has access only to a portion of the
objective function and to a subset of the constraints. In the proposed
technique, based on the method of multipliers, each node performs, when it
wakes up, either a descent step on a local augmented Lagrangian or an ascent
step on the local multiplier vector. Nodes realize when to switch from the
descent step to the ascent one through an asynchronous distributed logic-AND,
which detects when all the nodes have reached a predefined tolerance in the
minimization of the augmented Lagrangian. It is shown that the resulting
distributed algorithm is equivalent to a block coordinate descent for the
minimization of the global augmented Lagrangian. This allows one to extend the
properties of the centralized method of multipliers to the considered
distributed framework. Two application examples are presented to validate the
proposed approach: a distributed source localization problem and the parameter
estimation of a neural network.Comment: arXiv admin note: substantial text overlap with arXiv:1803.0648
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