Sinuhé Martinez-Martinez

Brief paper: State and input observability for structured linear systems: A graph-theoretic approach

This paper deals with the state and input observability analysis for structured linear systems with unknown inputs. The proposed method is based on a graph-theoretic approach and assumes only the knowledge of the systems structure. Using a particular decomposition of the systems into two subsystems, we express, in simple graphic terms, necessary and sufficient conditions for the generic state and input observability. These conditions are easy to check because they are based on comparison of integers and on finding particular subgraphs in a digraph. Therefore, our approach is suited to study large-scale systems.

Graphic approach for the determination of the existence of sequences guaranteeing observability of switched linear systems

This paper deals with the design of sequences allowing the observability of the state of a switched linear system. The proposed method, based on a graph-theoretic approach, needs only the knowledge of the systems structure. The necessary and sufficient conditions for the existence of at least one switching sequence guaranteeing the observability of a switched structured system are provided. Such conditions are particularly intuitive and they can be implemented with classic algorithms of the graph theory.

LISA: A LINEAR STRUCTURED SYSTEM ANALYSIS PROGRAM

In this paper, the so-called software LISA is presented. LISA is a flexible and portable software, which has been developed to analyse structural properties of large scale linear and bilinear structured systems. More precisely, LISA contains programmed algorithms, which allow us to apply recent results in the analysis of structured systems.

Two neural network based strategies for the detection of a total instantaneous blockage of a sodium-cooled fast reactor

The total instantaneous blockage (TIB) of an assembly in the core of a sodium-cooled fast reactor (SFR) is investigated. Such incident could appear as an abnormal rise in temperature on the assemblies neighbouring the blockage. Its detection relies on a dataset of temperature measurements of the assemblies making up the core of the French Phenix Nuclear Reactor. The data are provided by the French Commission of Atomic and Alternatives Energies (CEA). Here, two strategies are proposed depending on whether the sensor measurement of the suspected assembly is reliable or not. The proposed methodology implements a time-lagged feed-forward neural (TLFFN) Network in order to predict the one-step-ahead temperature of a given assembly. The incident is declared if the difference between the predicted process and the actual one exceeds a threshold. In these simulated conditions, the method is efficient to detect small gradients as expected in reality.

Observability recovering for linear switched systems via sensor placement: a graphic approach

Abstract It is well known that the state observability of switched linear systems depends strongly on the switching sequence between the modes. In this work, the problem of recovering the observability of a class of switched linear systems via sensor placement is treated. The proposed method is based on an original graph representing switched systems and allowing to handle the problem of the sensor placement. Such graph-theoretic approach, needs only the knowledge of the systems structure. The calculations in order to find the number and location of the necessary sensors are given in terms of paths on a digraph and matchings on a bipartite graph which are particularly intuitive. Moreover, these results can be implemented with classic algorithms of the graph theory.

Control/fault diagnosis interactions analysis for structured bilinear systems

Abstract This work is dedicated to the study of control/fault diagnosis interactions for structured bilinear systems using a graph-theoretic approach. According to the fact that constant control inputs make possible the representation of a bilinear system by a linear one, some propositions provide the sufficient conditions for active-BFPRG (Bilinear Fundamental Problem of Residual Generation) in this particular case. These conditions are easy to check because they are based on the comparison of expressions and on finding paths in a digraph.

Early detection of an instantaneous total blockage accident in the core of a sodium-cooled fast reactor

The Total Instantaneous Blockage (TIB) of an assembly in the core of a Sodium-cooled Fast Reactor (SFR) is under study. The dataset is provided by the Atomic Energy and Alternative Energies Commission (CEA). Through the estimation of the temperatures on the top of each assembly of the SFRs core, an original strategy for the detection of a TIB is proposed and implemented to a hypothetical simulated incident. Since there is no knowledge of the systems model, it is considered as a blackbox and the estimation of temperatures is made by a Neural Network.

Communication sequence selection to preserve reachability/observability in networked control systems with communication constraints: a graphic approach

Abstract This paper proposes a graphical strategy for finding all communication sequences that ensure reachability and observability of a Networked Control system (NCS) in which a linear time invariant (LTI) plant communicates with a controller or a fault detection (FD) module over a shared medium. The medium supports a limited number of simultaneous connection between sensors and controller/FD module. The proposed method is based on a graph-theoretic approach and it needs only the knowledge of the systems structure.