4 research outputs found
Structure Identifiability of an NDS with LFT Parametrized Subsystems
Requirements on subsystems have been made clear in this paper for a linear
time invariant (LTI) networked dynamic system (NDS), under which subsystem
interconnections can be estimated from external output measurements. In this
NDS, subsystems may have distinctive dynamics, and subsystem interconnections
are arbitrary. It is assumed that system matrices of each subsystem depend on
its (pseudo) first principle parameters (FPPs) through a linear fractional
transformation (LFT). It has been proven that if in each subsystem, the
transfer function matrix (TFM) from its internal inputs to its external outputs
is of full normal column rank (FNCR), while the TFM from its external inputs to
its internal outputs is of full normal row rank (FNRR), then the NDS is
structurally identifiable. Moreover, under some particular situations like
there are no direct information transmission from an internal input to an
internal output in each subsystem, a necessary and sufficient condition is
established for NDS structure identifiability. A matrix valued polynomial (MVP)
rank based equivalent condition is further derived, which depends affinely on
subsystem (pseudo) FPPs and can be independently verified for each subsystem.
From this condition, some necessary conditions are obtained for both subsystem
dynamics and its (pseudo) FPPs, using the Kronecker canonical form (KCF) of a
matrix pencil.Comment: 16 page
Global Structure Identifiability and Reconstructibility of an NDS with Descriptor Subsystems
This paper investigates requirements on a networked dynamic system (NDS) such
that its subsystem interactions can be solely determined from experiment data
or reconstructed from its overall model. The NDS is constituted from several
subsystems whose dynamics are described through a descriptor form. Except
regularity on each subsystem and the whole NDS, no other restrictions are put
on either subsystem dynamics or subsystem interactions. A matrix rank based
necessary and sufficient condition is derived for the global identifiability of
subsystem interactions, which leads to several conclusions about NDS structure
identifiability when there is some a priori information. This matrix also gives
an explicit description for the set of subsystem interactions that can not be
distinguished from experiment data only. In addition, under a well-posedness
assumption, a necessary and sufficient condition is obtained for the
reconstructibility of subsystem interactions from an NDS descriptor form model.
This condition can be verified with each subsystem separately and is therefore
attractive in the analysis and synthesis of a large-scale NDS. Simulation
results show that rather than increases monotonically with the distance of
subsystem interactions to the undifferentiable set, the magnitude of the
external output differences between two NDSs with distinct subsystem
interactions increases much more rapidly when one of them is close to be
unstable. In addition, directions of probing signals are also very important in
distinguishing external outputs of distinctive NDSs.These findings are expected
to be helpful in identification experiment designs, etc.Comment: 15 pages, 4 figure
Safety and Reliability - Safe Societies in a Changing World
The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management
- mathematical methods in reliability and safety
- risk assessment
- risk management
- system reliability
- uncertainty analysis
- digitalization and big data
- prognostics and system health management
- occupational safety
- accident and incident modeling
- maintenance modeling and applications
- simulation for safety and reliability analysis
- dynamic risk and barrier management
- organizational factors and safety culture
- human factors and human reliability
- resilience engineering
- structural reliability
- natural hazards
- security
- economic analysis in risk managemen