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Finite-Time Distributed Identification for Nonlinear Interconnected Systems

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IEEE/CAA Journal of Automatica Sinica 2022年第7期9卷 1188-1199页

作者： Farzaneh Tatari Hamidreza Modares Christos Panayiotou marios polycarpou Mechanical Engineering Department Michigan State UniversityEast LansingMI 48824 USA KIOS Research and Innovation Center of Excellence and the Department of Electrical and Computer Engineering University of CyprusNicosia 1678Cyprus IEEE

In this paper,a novel finite-time distributed identification method is introduced for nonlinear interconnected systems.A distributed concurrent learning-based discontinuous gradient descent update law is presented to learn uncertain interconnected subsystems’*** concurrent learning approach continually minimizes the identification error for a batch of previously recorded data collected from each subsystem as well as its neighboring *** state information of neighboring interconnected subsystems is acquired through direct *** overall update laws for all subsystems form coupled continuous-time gradient flow dynamics for which finite-time Lyapunov stability analysis is *** a byproduct of this Lyapunov analysis,easy-to-check rank conditions on data stored in the distributed memories of subsystems are obtained,under which finite-time stability of the distributed identifier is *** rank conditions replace the restrictive persistence of excitation(PE)conditions which are hard and even impossible to achieve and verify for interconnected ***,simulation results verify the effectiveness of the presented distributed method in comparison with the other methods.

关键词： Distributed concurrent learning finite-time identification nonlinear interconnected systems unknown dynamics

Passive Attack Detection for a Class of Stealthy Intermittent Integrity Attacks

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IEEE/CAA Journal of Automatica Sinica 2023年第4期10卷 898-915页

作者： Kangkang Zhang Christodoulos Keliris Thomas Parisini Bin Jiang marios M.polycarpou Department of Electrical and Electronic Engineering Imperial College LondonLondon SW72AZUKand also with the KIOS Research and Innovation Center of ExcellenceUniversity of CyprusNicosia 1678Cyprus KIOS Research and Innovation Center of Excellence and the Department of Electrical and Computer Engineering University of CyprusNicosia 1678Cyprus Department of Electrical and Electronic Engineering Imperial College LondonLondon SW72AZUK Department of Engineering and Architecture University of TriesteTrieste 34127Italy KIOS Research and Innovation Center of Excellence University of CyprusNicosia 1678Cyprus College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper proposes a passive methodology for detecting a class of stealthy intermittent integrity attacks in cyberphysical systems subject to process disturbances and measurement noise.A stealthy intermittent integrity attack strategy is first proposed by modifying a zero-dynamics attack *** stealthiness of the generated attacks is rigorously investigated under the condition that the adversary does not know precisely the system state *** order to help detect such attacks,a backward-in-time detection residual is proposed based on an equivalent quantity of the system state change,due to the attack,at a time prior to the attack occurrence time.A key characteristic of this residual is that its magnitude increases every time a new attack *** estimate this unknown residual,an optimal fixed-point smoother is proposed by minimizing a piece-wise linear quadratic cost function with a set of specifically designed weighting *** smoother design guarantees robustness with respect to process disturbances and measurement noise,and is also able to maintain sensitivity as time progresses to intermittent integrity attack by resetting the covariance matrix based on the weighting *** adaptive threshold is designed based on the estimated backward-in-time residual,and the attack detectability analysis is rigorously investigated to characterize quantitatively the class of attacks that can be detected by the proposed ***,a simulation example is used to demonstrate the effectiveness of the developed methodology.

关键词： Backward-in-time equivalent quantity fixed-point smoother intermittent integrity attacks

Scalable Distributed Sensor Fault Diagnosis for Smart Buildings

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IEEE/CAA Journal of Automatica Sinica 2020年第3期7卷 638-655页

作者： Panayiotis M.Papadopoulos Vasso Reppa marios M.polycarpou Christos G.Panayiotou IEEE KIOS Research and Innovation Center of Excellence Department of Electrical and Computer EngineeringUniversity of CyprusNicosia 1678Cyprus Department of Maritime and Transport Technology Delft University of TechnologyDelft2628 CDThe Netherlands

The enormous energy use of the building sector and the requirements for indoor living quality that aim to improve occupants' productivity and health, prioritize Smart Buildings as an emerging technology. The Heating, Ventilation and Air-Conditioning(HVAC) system is considered one of the most critical and essential parts in buildings since it consumes the largest amount of energy and is responsible for humans comfort. Due to the intermittent operation of HVAC systems, faults are more likely to occur, possibly increasing eventually building's energy consumption and/or downgrading indoor living quality. The complexity and large scale nature of HVAC systems complicate the diagnosis of faults in a centralized framework. This paper presents a distributed intelligent fault diagnosis algorithm for detecting and isolating multiple sensor faults in large-scale HVAC *** the HVAC system as a network of interconnected subsystems allows the design of a set of distributed sensor fault diagnosis agents capable of isolating multiple sensor faults by applying a combinatorial decision logic and diagnostic reasoning. The performance of the proposed method is investigated with respect to robustness, fault detectability and scalability. Simulations are used to illustrate the effectiveness of the proposed method in the presence of multiple sensor faults applied to a 83-zone HVAC system and to evaluate the sensitivity of the method with respect to sensor noise variance.

关键词： Building automation fault diagnosis fault location smart homes

Actuator and sensor fault isolation in a class of nonlinear dynamical systems

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Journal of Automation and Intelligence 2024年第2期3卷 57-72页

作者： Hamed Tirandaz Christodoulos Keliris marios M.polycarpou KIOS Research Center for Intelligent Systems and Networks and the Department of Electrical and Computer EngineeringUniversity of CyprusNicosia 1678Cyprus

Fault isolation in dynamical systems is a challenging task due to modeling uncertainty and measurement noise,interactive effects of multiple faults and fault *** paper proposes a unified approach for isolation of multiple actuator or sensor faults in a class of nonlinear uncertain dynamical *** and sensor fault isolation are accomplished in two independent modules,that monitor the system and are able to isolate the potential faulty actuator(s)or sensor(s).For the sensor fault isolation(SFI)case,a module is designed which monitors the system and utilizes an adaptive isolation threshold on the output residuals computed via a nonlinear estimation scheme that allows the isolation of single/multiple faulty sensor(s).For the actuator fault isolation(AFI)case,a second module is designed,which utilizes a learning-based scheme for adaptive approximation of faulty actuator(s)and,based on a reasoning decision logic and suitably designed AFI thresholds,the faulty actuator(s)set can be *** effectiveness of the proposed fault isolation approach developed in this paper is demonstrated through a simulation example.

关键词： Actuator and sensor fault isolation Adaptive approximation Observer-based fault diagnosis Reasoning-based decision logic

Matrix pencil based robust control for feedforward systems with event-triggered communications and sensor/actuator faults

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Journal of Automation and Intelligence 2023年第3期2卷 139-145页

作者： Hefu Ye marios M.polycarpou Changyun Wen School of Electrical and Electronic Engineering Nanyang Technological UniversityNanyang Avenue639798Singapore Department of Electrical and Computer Engineering KIOS Center of ExcellenceUniversity of CyprusNicosia1678Cyprus

In this paper we address the issue of output-feedback robust control for a class of feedforward nonlinear *** different from the related literature,the feedback/input signals are corrupted by additive noises and can only be transmitted intermittently due to the consideration of event-triggered communications,which bring new challenges to the control *** the aid of matrix pencil based design procedures,regulating the output to near zero is globally solved by a non-conservative dynamic low-gain controller which requires only an a priori information on the upper-bound of the growth rate of *** analysis shows that the closed-loop system is input-to-state stable with respect to the sampled errors and additive *** particular,the observer and controller designs have a dual architecture with a single dynamic scaling parameter whose update law can be obtained by calculating the generalized eigenvalues of matrix pencils offline,which has an advantage in the sense of improving the system convergence rate.

关键词： Feedforward nonlinear systems Output-feedback Asynchronous event-triggered control Dynamic gain

A numerical study of prestressed high strength steel tubular members

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Frontiers of Structural and Civil Engineering 2020年第1期14卷 10-22页

作者： Michaela GKANTOU marios THEOFANOUS Charalampos BANIOTOPOULOS Department of Civil Engineering Liverpool John Moores UniversityLiverpool L33AFUK Department of Civil Engineering University of BirminghamBirmingham B152TTUK

The structural behavior of prestressed high strength steel(HSS)tubular members is investigated through the execution of advanced finite element *** models are developed and validated against published experimental data on HSS tubular members subjected to different levels of initial prestress and loaded either in tension or *** effect of the presence or absence of grouting on the strength and ductility of the members is also *** numerically replicate the structural response recorded in the tests,some key modeling features including the employed numerical solver,the adopted material models and the element types warrant careful *** developing of the finite element models,the numerically generated ultimate loads,the corresponding failure modes and the full load-deformation curves are compared to the experimental ones,indicating a successful *** anticipated,prestressing enhances the load-bearing capacity for the tensile members,whereas it is detrimental for the compressive ones.A series of parametric studies is performed to assess the influence of key factors on the structural response of prestressed HSS members and the obtained results are *** guidance for tensile and compressive prestressed tubular members is also provided.

关键词： finite element prestressing tubular members grout high strength steel

Post-glass melting synthesis and photochromic properties of composite AgCl-AgPO_(3)glasses

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Journal of Materiomics 2023年第3期9卷 455-463页

作者： marios Adamidis Ioannis Konidakis Emmanuel Stratakis Institute of Electronic Structure and Laser(IESL) Foundation for Research and Technology-Hellas(FORTH)HeraklionCrete71110Greece Department of Materials Science and Technology University of CreteHeraklionCrete71003Greece

We herein present a simple,fast,low-temperature,post-glass melting fabrication protocol in which a photochromic silver cation based modified zone is incorporated within silver metaphosphate glass(AgPO_(3)).The selection of AgPO_(3)glass is mainly based on its relative“soft”nature(T_(g)=192℃)that enables the integration of silver cations from the surface deposited AgCl layer,while being transparent in most of the visible range,and therefore suitable for smart photochromic window *** suggested synthesis procedure permits the controlled formation of a silver cation modified layer within the host glass matrix,while the characteristics of the layer itself can be adjusted *** findings reveal a direct relationship between the developed composite AgCleAgPO_(3)glass photochromic response and the morphological features of the integrated layer,i.e.,thickness and *** importantly,the photochromic response time with various UV irradiation doses is also studied,where remarkable response times of several seconds are *** and efforts to further enhance the photochromic performance by utilizing the presence of silver nanoparticles within the glass matrix are also presented and discussed.

关键词： Silver chloride Silver metaphosphate glass Soft phosphate glass Post-glass melting incorporation Photochromic properties

Two-way coupling of unsaturated-saturated flow by integrating the SWAT and MODFLOW models with application in an irrigation district in arid region of West China

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Journal of Arid Land 2011年第3期3卷 164-173页

作者： Yi LUO marios SOPHOCLEOUS Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Kansas Geological Survey University of Kansas Lawrence Kansas 66047 USA

This paper presents the realization of two-way coupling of the unsaturated-saturated flow interactions of the SWAT2000 and MODFLOW96 models on the basis of the integrated surface/groundwater model SWATMOD99, and its application in Hetao Irrigation District （HID）, Inner Mongolia, China. Major revisions and enhancements were made to the SWAT2000 and MODFLOW models for simulating the detailed hydrologic budget and coupled unsaturated and saturated interactions, and irrigation canal hydrology for the HID. The simulation results of seasonal groundwater recharge to and evaporate from the shallow groundwater, and the annual water budget over the district are presented and discussed. The results implied the necessity of two-way coupling of the unsaturated-saturated interactions when groundwater is shallow, and the feasibility of making comprehensive use of the information coming from both the surface water and groundwater models to make a more physically-based assessment of the coupled interactions.

关键词： SWAT MODFLOW SWATMOD coupled unsaturated-saturated flow irrigation canals groundwater recharge groundwater evaporation

Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites

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npj Computational Materials 2023年第1期9卷 744-756页

作者： marios Zacharias George Volonakis Feliciano Giustino Jacky Even Univ Rennes INSA RennesCNRSInstitut FOTON-UMR 6082F-35000 RennesFrance Univ Rennes ENSCRINSA RennesCNRSISCR-UMR 6226F-35000 RennesFrance Oden Institute for Computational Engineering and Sciences The University of Texas at AustinAustinTX 78712USA Department of Physics The University of Texas at AustinAustinTX 78712USA

Anharmonicity and local disorder(polymorphism)are ubiquitous in perovskite physics,inducing various phenomena observed in scattering and spectroscopy *** of these phenomena still lack interpretation from first principles since,hitherto,no approach is available to account for anharmonicity and disorder in electron–phonon ***,relying on the special displacement method,we develop a unified treatment of both and demonstrate that electron–phonon coupling is strongly influenced when we employ polymorphous perovskite *** uncover that polymorphism in halide perovskites leads to vibrational dynamics far from the ideal noninteracting phonon picture and drives the gradual change in their band gap around phase transition *** also clarify that combined band gap corrections arising from disorder,spin-orbit coupling,exchange–correlation functionals of high accuracy,and electron–phonon coupling are all *** findings agree with experiments,suggesting that polymorphism is the key to address pending questions on perovskites’technological applications.

关键词： perovskite phonon harmonic