2,743 research outputs found
Detecting Topology Variations in Dynamical Networks
This paper considers the problem of detecting topology variations in
dynamical networks. We consider a network whose behavior can be represented via
a linear dynamical system. The problem of interest is then that of finding
conditions under which it is possible to detect node or link disconnections
from prior knowledge of the nominal network behavior and on-line measurements.
The considered approach makes use of analysis tools from switching systems
theory. A number of results are presented along with examples
B-decay anomalies in Pati-Salam SU(4)
Attempts to incorporate in a coherent picture the -decay anomalies
presumably observed in and semi-leptonic
decays have to face the absence of signals in other related experiments, both
at low and at high energies. By extending and making more precise the content
of Ref. [1], we describe one such attempt based on the Pati-Salam SU(4) group,
that unifies colour and the - charge, in the context of a new strongly
interacting sector, equally responsible for producing a pseudo-Goldstone Higgs
boson.Comment: 24 pages, 3 figure
Switching Control for Parameter Identifiability of Uncertain Systems
This paper considers the problem of identifying the parameters of an
uncertain linear system by means of feedback control. The problem is approached
by considering time-varying controllers. It is shown that even when the
uncertainty set is not finite, parameter identifiability can be generically
ensured by switching among a finite number of linear time-invariant
controllers. The results are shown to have several implications, ranging from
fault detection and isolation to adaptive and supervisory control. Practical
aspects of the problem are also discussed in details
Cosmological Production of Dark Nuclei
We study the formation of Dark Matter nuclei in scenarios where DM particles
are baryons of a new confining gauge force. The dark nucleosynthesis is
analogous to the formation of light elements in the SM and requires as a first
step the formation of dark deuterium. We compute this process from first
principles, using the formalism of pion-less effective theory for
nucleon-nucleon interactions. This controlled effective field theory expansion
allows us to systematically compute the cross sections for generic SM
representations under the assumption of shallow bound states. In the context of
vector-like confinement models we find that, for nucleon masses in the TeV
range, baryonic DM made of electro-weak constituents can form a significant
fraction of dark deuterium and a much smaller fraction of dark tritium.
Formation of dark nuclei can also lead to monochromatic photon lines in
indirect detection. Models with singlets do not undergo nucleosynthesis unless
a dark photon is added to the theory.Comment: 26 pages, 4 figures. v2) improved discussion on indirect detection,
refs adde
On Resilient Control of Nonlinear Systems under Denial-of-Service
We analyze and design a control strategy for nonlinear systems under
Denial-of-Service attacks. Based on an ISS-Lyapunov function analysis, we
provide a characterization of the maximal percentage of time during which
feedback information can be lost without resulting in the instability of the
system. Motivated by the presence of a digital channel we consider event-based
controllers for which a minimal inter-sampling time is explicitly
characterized.Comment: 7 pages, 1 figur
Resilient Control under Denial-of-Service
We investigate resilient control strategies for linear systems under
Denial-of-Service (DoS) attacks. By DoS attacks we mean interruptions of
communication on measurement (sensor-to-controller) and/or control
(controller-to-actuator) channels carried out by an intelligent adversary. We
characterize the duration of these interruptions under which stability of the
closed-loop system is preserved. The resilient nature of the control descends
from its ability to adapt the sampling rate to the occurrence of the DoS.Comment: 10 pages, abridged version submitte
Self-triggered Coordination over a Shared Network under Denial-of-Service
The issue of security has become ever more prevalent in the analysis and
design of cyber-physical systems. In this paper, we analyze a consensus network
in the presence of Denial-of-Service (DoS) attacks, namely attacks that prevent
communication among the network agents. By introducing a notion of
Persistency-of-Communication (PoC), we provide a characterization of DoS
frequency and duration such that consensus is not destroyed. An example is
given to substantiate the analysis
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