14,642 research outputs found
New advances in H∞ control and filtering for nonlinear systems
The main objective of this special issue is to
summarise recent advances in H∞ control and filtering
for nonlinear systems, including time-delay, hybrid and
stochastic systems. The published papers provide new
ideas and approaches, clearly indicating the advances
made in problem statements, methodologies or applications
with respect to the existing results. The special
issue also includes papers focusing on advanced and
non-traditional methods and presenting considerable
novelties in theoretical background or experimental
setup. Some papers present applications to newly
emerging fields, such as network-based control and
estimation
Mathematical control of complex systems
Copyright © 2013 ZidongWang et al.This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Solving the Simplest Theory of Quantum Gravity
We solve what is quite likely the simplest model of quantum gravity, the
worldsheet theory of an infinitely long, free bosonic string in Minkowski
space. Contrary to naive expectations, this theory is non-trivial. We
illustrate this by constructing its exact factorizable S-matrix. Despite its
simplicity, the theory exhibits many of the salient features expected from more
mature quantum gravity models, including the absence of local off-shell
observables, a minimal length, a maximum achievable (Hagedorn) temperature, as
well as (integrable relatives of) black holes. All these properties follow from
the exact S-matrix. We show that the complete finite volume spectrum can be
reconstructed analytically from this S-matrix with the help of the
thermodynamic Bethe Ansatz. We argue that considered as a UV complete
relativistic two-dimensional quantum field theory the model exhibits a new type
of renormalization group flow behavior, "asymptotic fragility". Asymptotically
fragile flows do not originate from a UV fixed point.Comment: 32+4 pages, 1 figure, v2: typos fixed, published versio
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