Katalin Hangos | University of Pannonia (original) (raw)

Papers by Katalin Hangos

Cornell University - arXiv, Jul 5, 2011

A unified framework is proposed in this paper for parameter estimation using convex optimization ... more A unified framework is proposed in this paper for parameter estimation using convex optimization and experiment design applying convex maximization for Pauli channels, that can be extended to generalized Pauli channels, too. In the case of known channel directions, an affine parametrization of the Choi matrix turns the LS parameter estimation into a convex optimization problem also for the generalized Pauli channels. A simple iterative algorithm for estimating the channel directions is also given for qubit Pauli channels. The experiment design was performed by maximizing the trace of the Fisher information matrix of the output quantum system to find optimal input state and measurement POVM for the channel estimation. For the known channel direction case it was found that the optimal input state should be pure and the optimal measurement POVM is extremal. It was also shown that both the input state and the POVM elements in the optimal configuration should be parallel to the channel directions in the qubit Pauli channel case. The proposed methods and algorithms are illustrated by simple numerical examples.

2017 International Symposium on Power Electronics (Ee), 2017

A heuristic and adaptive model predictive control algorithm is presented in this work which opera... more A heuristic and adaptive model predictive control algorithm is presented in this work which operates domestic refrigerators connected to an electrical grid operating in a dayahead market (DAM) and temperature constraints also have to be met by the refrigerator temperatures. The problem has been solved using the model predictive framework using a simple refrigerator model. This paper is a continuation of a previous work that has been extended so that the optimal scheduler algorithm adapts its steps to the actual estimated interior heat capacity of the refrigerator (which depends on the food quantity, food temperature, etc. in the interior). It is shown that the proposed adaptive MPC based scheduling algorithm gives a better performance (with respect to price) as opposed to the scheduling algorithm having no precise knowledge of the actual load of the refrigerator. Moreover, due to the adaptive behavior it was possible to decrease the running time of the optimal scheduler algorithm compared to the non-adaptive version.

Energies, 2022

Fast charging is an attractive way of charging batteries; however, it may result in an undesired ... more Fast charging is an attractive way of charging batteries; however, it may result in an undesired degradation of battery performance and lifetime because of the increase in battery temperature during fast charge. In this paper we propose a simple optimized fuzzy controller that is responsible for the regulation of the charging current of a battery charging system. The basis of the method is a simple dynamic equivalent circuit type model of the Li-ion battery that takes into account the temperature dependency of the model parameters, too. Since there is a tradeoff between the charging speed determined by the value of the charging current and the increase in temperature of the battery, the proposed fuzzy controller is applied for controlling the charging current as a function of the temperature. The controller is optimized using a genetic algorithm to ensure a jointly minimal charging time and battery temperature increase during the charging. The control method is adaptive in the sense...

Energies, 2019

Parameter estimation of electrical vehicle batteries in the presence of temperature effect is add... more Parameter estimation of electrical vehicle batteries in the presence of temperature effect is addressed in this work. A simple parametric temperature dependent battery model is used for this purpose where the temperature dependence is described by static relationships. A two-stepmethod is used that includes a parameter estimation step of the key parameters at differenttemperatures followed by a static optimization step that determines the temperature coefficients of thecorresponding parameters. It was found that the temperature dependent parameter characteristicscan be reliably estimated from charging profiles only. The proposed method can be used as acomputationally effective way of determining the key battery parameters at a given temperature fromtheir actual estimated values and from their previously determined static temperature dependence.The proposed parameter estimation method was verified by simulation experiments on a morecomplex battery model that also describes the detail...

Transportation Research Part D: Transport and Environment, 2018

In this work a control system is developed and analyzed for the suppression of moving jamwaves an... more In this work a control system is developed and analyzed for the suppression of moving jamwaves and the reduction of pollutant concentrations near motorways. The system is based on the second-order macroscopic freeway traffic model METANET, joined by an emission dispersion model, introduced in a previous work of the authors. For the control tasks dedicated controllers are designed, both using the nonlinear model predictive control method. The control objectives require a distinction in the utilized control measures, thus different controllers are designed and used in predefined control modes. The first mode of the controller is responsible for keeping pollutant concentrations below prescribed limits under stable conditions. The second mode of the controller is working in case of a shockwave threat, aiming for traffic stabilization. Between the control modes switching is based on an appropriate rule set that satisfies the stability of the controlled system. The hybrid controller structure is realized by a finite automata. A complex case study is presented for the evaluation of the suggested controller. 1 Segment lengths Li, i = 1, ..., Ns may be chosen arbitrarily as long as the numerical stability condition of Courant et al. (1928) is satisfied for given sampling time T , i.e. v free T L i < 1, i = 1, ..., Ns. The free flow speed v free is equal to the highest velocity that a particle (i.e. a vehicle) in the flow may carry.

Control Engineering Practice, 2018

A cost-optimal model predictive scheduling algorithm is presented that operates in a day-ahead ma... more A cost-optimal model predictive scheduling algorithm is presented that operates in a day-ahead market. The underlying optimizer is a heuristic branch and bound algorithm that finds the constrained optimal scheduling of a freezer with respect to hourly changing energy price. The method is also able to iteratively re-estimate the heat capacity of the freezer. Simulation experiments were performed on a freezer model identified from measurement data. Results show that the proposed algorithm successfully decreased the cost of operation, however the computational complexity increases when the price is growing. The proposed method can be generalized for home appliances of different kind.

Journal of Mathematical Chemistry, 2016

In this paper we show that the model form of a wide class of kinetic systems with rational terms ... more In this paper we show that the model form of a wide class of kinetic systems with rational terms in the reaction rates is invariant under a positive linear diagonal transformation. Thus, the concept of linear conjugacy defined originally for mass action systems is extended to rational biochemical models. The generalized Kirchhoff matrix and the kinetic weighting matrix of the linearly conjugate models are given as functions of the computed transformation parameters. It is shown through the illustrative examples that the dense realization of a linearly conjugate rational model may contain more reactions than that of a dynamically equivalent one due to the additional degrees of freedom introduced by the linear transformation. The proposed matrix-based representation is suitable for the computational search of preferred graph structures corresponding to linearly conjugate realizations of rational kinetic models.

IFAC-PapersOnLine, 2016

This work applies the LQ control framework to the class of quasi-polynomial and Lotka-Volterra sy... more This work applies the LQ control framework to the class of quasi-polynomial and Lotka-Volterra systems through the linearized version of their nonlinear system model. The primary aim is to globally stabilize the original system with a suboptimal LQ state feedback by means of a well-known entropy-like Lyapunov function that is related to the diagonal stability of linear systems. This aim can only be reached in the case when the quasi-monomial composition matrix is invertible. In the rank-deficient case only the local stabilization of the system is possible with an LQ controller that is designed using the locally linearized model of the closed-loop system model.

Electric Power Components and Systems, 2014

ABSTRACT —A multiple-input–multiple-output linear-quadratic servo controller is proposed for a sy... more ABSTRACT —A multiple-input–multiple-output linear-quadratic servo controller is proposed for a synchronous generator operating in a nuclear power plant that keeps the active power at the desired level and performs reactive power reference tracking using the reactive power demand from a central dispatch center. The controller design was based on the locally linearized version of a previous non-linear dynamical model of the synchronous electrical generator [1, 2], the parameters of which have been identified using measured data from Paks Nuclear Power Plant (Hungary). The method can easily be applied to any industrial power plant generator connected to the electrical grid after estimating its parameters. The proposed observer-based multiple-input–multiple-output state feedback controller is a linear-quadratic servo controller with very good reference tracking and disturbance rejection properties, which were confirmed by simulation experiments.

Transportation Research Part C: Emerging Technologies, 2015

In this paper a novel simple dynamic model is suggested for the dispersion of motorway traffic em... more In this paper a novel simple dynamic model is suggested for the dispersion of motorway traffic emissions. The motivation for the research is to develop a model with low computational demand so that it can serve as a basis for a model based controller that is able to keep pollutant concentrations under legislation limits. The dispersion process is characterized as a distributed parameter system (DPS) in which the law of mass conservation holds. The elements of the mathematical model (the assumptions of the initial value problem) are specified using topological considerations, and the boundary conditions originate from the macroscopic traffic emission framework developed by the authors earlier. The developed engineering model, with applying the Gaussian plume model, is transformed to a discrete time nonlinear concentrated parameter state-space model form using lumping and finite difference approximations. For the suggested model a verification and numerical stability analysis is carried out. A sensitivity analysis of the existing motorway control measures (i.e. ramp metering, variable speed limits) is performed to justify the choice of a future control structure.

Systems & Control Letters, 2015

In the literature, there exist strong results on the qualitative dynamical properties of chemical... more In the literature, there exist strong results on the qualitative dynamical properties of chemical reaction networks (also called kinetic systems) governed by the mass action law and having zero deficiency. However, it is known that different network structures with different deficiencies may correspond to the same kinetic differential equations. In this paper, an optimization-based approach is presented for the computation of deficiency zero reaction network structures that are linearly conjugate to a given kinetic dynamics. Through establishing an equivalent condition for zero deficiency, the problem is traced back to the solution of an appropriately constructed mixed integer linear programming problem. Furthermore, it is shown that weakly reversible deficiency zero realizations can be determined in polynomial time using standard linear programming. Two examples are given for the illustration of the proposed methods.

Quantum Probability and Infinite Dimensional Analysis, 2007

In the paper the Bayesian and the least squares methods of quantum state tomography are compared ... more In the paper the Bayesian and the least squares methods of quantum state tomography are compared for a single qubit. The quality of the estimates are compared by computer simulation when the true state is either mixed or pure. The fidelity and the Hilbert-Schmidt distance are used to quantify the error. It was found that in the regime of low measurement number the Bayesian method outperforms the least squares estimation. Both methods are quite sensitive to the degree of mixedness of the state to be estimated, that is, their performance can be quite bad near pure states.

Computer Intensive Methods in Control and Signal Processing, 1997

Various types of control problems related to distributed control system structure design, such as... more Various types of control problems related to distributed control system structure design, such as the analysis of structural controllability and observability, analysis of disturbance rejectivity, analysis of structural stability, design of distributed SISO (single input single output) controller system structures, and the design of distributed MIMO (multiple input multiple output) controller system structures, are described in the paper as algorithmic problems. Their equivalent graph theoretic problems and their algorithmic properties are also analysed.

Model Reduction and Coarse-Graining Approaches for Multiscale Phenomena

Fault detection and diagnosis in large-scale process systems is of great practical importance and... more Fault detection and diagnosis in large-scale process systems is of great practical importance and present various challenging research problems at the same time. One of them is the computational complexity of the algorithms that causes an exponential growth of the computational resources (time and memory) with increasing system sizes [21]. One remedy of this problem is to decompose the system model and effectively focus on its relevant sub-model when doing the fault detection, isolation and loss prevention. Multi-scale modelling is an emerging interdisciplinary field that offers a systematic way of constructing, analyzing and solving dynamic models of large-scale complex systems [22]. The aim of this paper is to propose a model reduction approach based on multi-scale modelling of process systems for diagnostic purposes. Because lumped or concentrated parameter process models are the most important and widespread class of process models for control and diagnostic applications, therefore we also restrict ourselves to this case.

A dinamikus folyamatrendszerek modellezése és irányítása területén folytattunk kutatást a folyama... more A dinamikus folyamatrendszerek modellezése és irányítása területén folytattunk kutatást a folyamatmérnöki, valamint a rendszer- és irányításelméleti módszereket integrálva. 1. Számítógéppel segített folyamatmodellezés A folyamatmodellek osztályán bevezettük a minimális modell fogalmát, és eljárásokat javasoltunk minimális modellek felállítására modellredukcióval, illetve inkrementális modellépítéssel. A komplex folyamatrendszerek dinamikus modellezésére használatos többléptékű (multi-scale) modellekre kidolgoztunk egy diagnosztikai cél-vezérelt modellezési módszert és egy ezen alapuló intelligens diagnosztikai rendszert. Kidolgoztuk a többléptékű modellek skálatérképen alapuló egyszerűsítésének módszerét. 2. Nemlineáris folyamatrendszerek analízise és irányítása A kvázipolinom modellekkel leírható folyamatrendszerek esetén lineáris mátrix egyenlőtlenségekkel leírható feltételeket adtunk a stabilitásra, és kvadratikus hamiltoni struktúrák létezésére. Módszert adtunk statikus kvázipol...

Mathematical Modelling of Natural Phenomena, 2015

Two partially overlapping classes of positive polynomial systems, chemical reaction networks with... more Two partially overlapping classes of positive polynomial systems, chemical reaction networks with mass action law (MAL-CRNs) and quasi-polynomial systems (QP systems) are considered. Both of them have an entropy-like Lyapunov function associated to them which are similar but not the same. Inspired by the work of Prof. Gorban [12] on the entropy-functionals for Markov chains, and using results on MAL-CRN and QP-systems theory we characterize MAL-CRNs and QP systems that enable both types of entropy-like Lyapunov functions. The starting point of the analysis is the class of linear weakly reversible MAL-CRNs that are mathematically equivalent to Markov chains with an equilibrium point where various entropy level set equivalent Lyapunov functions are available. We show that non-degenerate linear kinetic systems with a linear first integral (that corresponds to conservation) can be transformed to linear weakly reversible MAL-CRNs using linear diagonal transformation, and the coefficient matrix of this system is diagonally stable. This implies the existence of the weighted version of the various entropy level set equivalent Lyapunov functions for non-degenerate linear kinetic systems with a linear first integral. Using translated X-factorable phase space transformations and nonlinear variable transformations a dynamically similar linear ODE model is associated to the QP system models with a positive equilibrium point. The non-degenerate kinetic property together with the existence of positive equilibrium point form a sufficient condition of the existence of the weighted version of the various entropy level set equivalent Lyapunov functions in this case. Further extension has been obtained by using the time re-parametrization transformation defined for QP models.

Journal of Mathematical Chemistry, 2015

In this paper, a frequently used representation of mass-action type reaction networks is extended... more In this paper, a frequently used representation of mass-action type reaction networks is extended to a more general system class where the reaction rates are in rational function form. An algorithm is given to compute a possible reaction graph from the kinetic differential equations. However, this structure is generally non-unique, as it is illustrated through the phenomenon of dynamical equivalence, when different reaction network structures correspond to exactly the same dynamics. It is shown that under some technical assumptions, the so-called dense realization containing the maximal number of reactions, forms a superstructure in the sense that the reaction graph of any dynamically equivalent reaction network is the sub-graph of the dense realization. Additionally, optimization based methods are given to find dynamically equivalent realizations with preferred properties, such as dense-or sparse realizations. The introduced concepts are illustrated by examples.

IFAC Proceedings Volumes, 2002

A simple nonlinear controller for a low-power gas turbine based on direct passivation is proposed... more A simple nonlinear controller for a low-power gas turbine based on direct passivation is proposed in this paper. It uses a nonlinear state space model of the gas turbine in inputaffine form based on first engineering principles. It is found by standard nonlinear analysis that the developed model is reachable and observable in the whole application domain and stable in a small neighborhood of an operating point. Accordingly, the control aim is to guarantee the asymptotic stability of every operating points in the whole application domain and to provide suitable disturbance rejection. The proposed nonlinear controller is based on a prescribed quadratic Lyapunov-function and it is able to solve the protection of the gas turbine. The robustness of the closed-loop system with respect to the time-varying parameters is also investigated.

IFAC Proceedings Volumes, 2013

Component mass conservation gives a linear first integral to the dynamic reaction kinetic equatio... more Component mass conservation gives a linear first integral to the dynamic reaction kinetic equations and greatly influences the set of admissible reactions. Therefore, mass conservation can be related to the deficiency of the reaction network and thus to its dynamic properties. In particular, it is shown that a mass conserving CRN without isomers and with a full rank complex composition matrix has zero deficiency. The concepts and results are illustrated on the example of the original and the lumped version of Michaelis-Menten kinetics.

Nuclear Engineering and Design, 2007

A simple low dimensional nonlinear dynamic model of the primary circuit in a VVER-type nuclear po... more A simple low dimensional nonlinear dynamic model of the primary circuit in a VVER-type nuclear power plant is developed from first engineering principles that is able to capture the most important dynamics of the system in normal operating modes. The model includes the description of the main control loops in the system, too. The model has been verified and validated by using measured data from three VVER-440 units of Paks Nuclear Power Plant in Hungary, and a good fit has been obtained. This qualifies the model to be the basis for the integrated redesign of the primary control loops.