JabRef references
Matching entries: 0
settings...
Balázs I, Fodor A and Magyar A (2019), "Aggregation of heterogeneous flexibility resources providing services for system operators and the market participants", Hungarian Journal of Industrial Chemistry. Vol. 47(1), pp. 65-70. De Gruyter Open.
Abstract: Power systems characterized by large, centralized generation sources and the typical flow of energy from the transmission grid to the distribution grid towards consumers are evolving. The increasing penetration of intermittent and distributed renewable energy generation is forcing system operators to increase the volume of balancing capabilities and procure flexibility services at the distribution grid level that must be supported by the aggregation of small-scale resources connected at the distribution grid. This paper suggests an aggregator framework that provides services for both operators of transmission and distribution systems while optimizes its portfolio to perform on wholesale energy trading markets too. Overlaying phases of multi-period optimization runs are proposed that incorporate stochastic renewable energy generation as well as load forecasts and, moreover, the continuously changing business context while enabling cooperation between optimization phases throughout the business process.
BibTeX:
@article{Balazs2019,
  author = {István Balázs and Attila Fodor and Attila Magyar},
  title = {Aggregation of heterogeneous flexibility resources providing services for system operators and the market participants},
  journal = {Hungarian Journal of Industrial Chemistry},
  publisher = {De Gruyter Open},
  year = {2019},
  volume = {47},
  number = {1},
  pages = {65--70},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/Gm5bMSeHbiw46Gr/download},
  doi = {10.33927/hjic-2019-10}
}
Greber M and Fodor A (2019), "Simulation of a balanced low-voltage electrical grid using a simplified network model", Hungarian Journal of Industrial Chemistry. Vol. 47(1), pp. 49-56. De Gruyter Open.
Abstract: A simulation method for low-voltage balanced distribution networks is proposed in this article. The novel method of node
powers is based on the general calculation technique of node voltages. By researching only balanced networks, single-
phase equivalents of the three-phase system are applicable. For the description of power lines, various parameters and
matrices are available. In this work a simplified model is applied by using a purely resistive one. The active power results
are solved through an iterative process. A main accomplishment is that the number of iterations needed is independent of
the size of the network, and the process rapidly converges. Validation of the method is performed on the IEEE European
Low-Voltage Test Feeder network. The simulation results confirm the achievements described in this paper.
BibTeX:
@article{Greber2019,
  author = {Márton Greber and Attila Fodor},
  title = {Simulation of a balanced low-voltage electrical grid using a simplified network model},
  journal = {Hungarian Journal of Industrial Chemistry},
  publisher = {De Gruyter Open},
  year = {2019},
  volume = {47},
  number = {1},
  pages = {49--56},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/2piqs8QbYz4T3KY/download},
  doi = {10.33927/hjic-2019-08}
}
Pózna AI, Fodor A and Hangos K (2019), "Non-technical loss diagnosis in electrical networks with a radial layout", Hungarian Journal of Industrial Chemistry. Vol. 47(1), pp. 3-9. De Gruyter Open.
Abstract: A network-oriented non-technical loss detection and localization methodology is presented in this paper. The basic idea
behind the proposed methodology is the deviation of the measured voltages from their nominal values. The operation of
the algorithm was investigated by simulation experiments using an (IEEE) European Low Voltage Test Feeder benchmark
network. The simulation results show that the proposed method is able to detect and localize multiple occurrences of non-
technical losses caused by fraudulent meters.
BibTeX:
@article{Pozna2019,
  author = {Anna I. Pózna and Attila Fodor and Katalin Hangos},
  title = {Non-technical loss diagnosis in electrical networks with a radial layout},
  journal = {Hungarian Journal of Industrial Chemistry},
  publisher = {De Gruyter Open},
  year = {2019},
  volume = {47},
  number = {1},
  pages = {3--9},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/N7iZ8KPzzg24J48/download},
  doi = {10.33927/hjic-2019-02}
}
Pózna AI, Fodor A and Hangos K (2019), "Model-based fault detection and isolation of non-technical losses in electrical networks", Mathematical and Computer Modelling of Dynamical Systems. Vol. 25(4), pp. 397-428. Taylor and Francis, IF: 0.862 (2018).
Abstract: A model-based diagnostic method is proposed for detecting and isolating non-technical losses (illegal loads) in low voltage electrical grids of one transformer area. The proposed method uses a simple static linear model of the network and it is based on analysing the differences between the measured and model-predicted voltages. As a preliminary off-line step of the diagnosis, a powerful electrical decomposition method is proposed, which breaks down the overall network to subsystems with one feeder layout enabling to make the computation efficient. The uncertainty in the model parameters together with the measurement uncertainties are also taken into account to make the approach applicable in real-world cases. The proposed method is able to detect and localize multiple illegal loads, and the amount of the illegal consumption can also be estimated. The operation and the diagnostic capabilities of the method are illustrated on a case study using the IEEE 2015 European Low Voltage Test Feeder.
BibTeX:
@article{Pozna2019a,
  author = {Anna I Pózna and Attila Fodor and Katalin Hangos},
  title = {Model-based fault detection and isolation of non-technical losses in electrical networks},
  journal = {Mathematical and Computer Modelling of Dynamical Systems},
  publisher = {Taylor and Francis, IF: 0.862 (2018)},
  year = {2019},
  volume = {25},
  number = {4},
  pages = {397--428},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/zZWBbMjSatSxZTE/download},
  doi = {10.1080/13873954.2019.1655066}
}
Pózna AI, Hangos KM and Magyar A (2019), "Temperature dependent parameter estimation of electrical vehicle batteries", Energies. Vol. 12(19), pp. 3755. MDPI IF: 2.707 (2018).
Abstract: 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-step
method is used that includes a parameter estimation step of the key parameters at different
temperatures followed by a static optimization step that determines the temperature coefficients of the
corresponding parameters. It was found that the temperature dependent parameter characteristics
can be reliably estimated from charging profiles only. The proposed method can be used as a
computationally effective way of determining the key battery parameters at a given temperature from
their actual estimated values and from their previously determined static temperature dependence.
The proposed parameter estimation method was verified by simulation experiments on a more
complex battery model that also describes the detailed dynamic thermal behavior of the battery.
BibTeX:
@article{Pozna2019b,
  author = {Anna I. Pózna and Katalin M. Hangos and Attila Magyar},
  title = {Temperature dependent parameter estimation of electrical vehicle batteries},
  journal = {Energies},
  publisher = {MDPI IF: 2.707 (2018)},
  year = {2019},
  volume = {12},
  number = {19},
  pages = {3755},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/dkRJtHkkBr4QZBJ/download},
  doi = {10.3390/en12193755}
}
Bálint R, Fodor A, Szalkai I, Szalkai Z and Magyar A (2019), "Modeling and calculation of the global solar irradiance on slopes", Hungarian Journal of Industrial Chemistry. Vol. 47(1), pp. 57-63. De Gruyter Open.
Abstract: The first step with regard to a simple model of a Photovoltaic Power Plant is developed in this paper based on astronomical and engineering principles. A solar irradiance model is presented in this paper that can be used to forecast the solar energy a surface on Earth is exposed to. The obtained model is verified against engineering expectations. The developed model can serve as a basis for forecasting the power of solar energy.
BibTeX:
@article{Rol2019,
  author = {Roland Bálint and Attila Fodor and István Szalkai and Zsófia Szalkai and Attila Magyar},
  title = {Modeling and calculation of the global solar irradiance on slopes},
  journal = {Hungarian Journal of Industrial Chemistry},
  publisher = {De Gruyter Open},
  year = {2019},
  volume = {47},
  number = {1},
  pages = {57--63},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/iMwmKco2KFzXtBj/download},
  doi = {10.33927/hjic-2019-09}
}
Bálint R, Fodor A and Magyar A (2019), "Model-based power generation estimation of solar panels using weather forecast for microgrid application", Acta Polytechnica Hungarica. Vol. 16(7), pp. 149-165. IF: 1.286 (2018).
Abstract: An electrical power production estimation model has been proposed in this paper
for PV panels. The model uses weather forecast data of a time interval (e.q. one day ahead)
as input and gives an estimation to electricity generation for the same time interval. The
proposed method takes into account the thermal effects taking place in a solar panel as
well as the temperature dependent nature of the solar panel efficiency. The results of this
paper could be utilized by transmission system operator, distribution system operator,
virtual power plant and microgrid operators. The precise mathematical model of the
renewable energy resources, which the function of the weather forecast is necessary for the
very large scale integration to the electrical transmission system.
BibTeX:
@article{Rol2019a,
  author = {Roland Bálint and Attila Fodor and Attila Magyar},
  title = {Model-based power generation estimation of solar panels using weather forecast for microgrid application},
  journal = {Acta Polytechnica Hungarica},
  publisher = {IF: 1.286 (2018)},
  year = {2019},
  volume = {16},
  number = {7},
  pages = {149--165},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/YHi8QXiKdN2i953/download},
  doi = {10.12700/APH.16.7.2019.7.9}
}
Bálint R, Fodor A, Hangos KM and Magyar A (2018), "Cost-optimal model predictive scheduling of freezers", Control Engineering Practice. Vol. 80, pp. 61-69. Elsevier, IF: 3.232.
Abstract: 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.

BibTeX:
@article{Balint2018,
  author = {Bálint, Roland and Fodor, Attila and Hangos, Katalin M and Magyar, Attila},
  title = {Cost-optimal model predictive scheduling of freezers},
  journal = {Control Engineering Practice},
  publisher = {Elsevier, IF: 3.232},
  year = {2018},
  volume = {80},
  pages = {61--69},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/DK53C5spfefCfEX/download},
  doi = {10.1016/j.conengprac.2018.08.009}
}
Magyar A (2018), "Generalized mass action realizations of temperature dependent chemical reaction networks", Reaction Kinetics, Mechanisms and Catalysis. , pp. 1-14. Springer, IF: 1.428.
Abstract: Generalized mass action systems are general descriptors in the sense that they are able to capture the structure and dynamic properties of chemical reaction networks even in intracellular environments. It has been shown that several results of chemical reaction network (CRN) theory carry over to the case of generalized mass action kinetics. It is known, however, that the most important properties of CRNs, including their deficiency, reversibility and balancing, are realization-dependent. Using model transformations a method is proposed for embedding the temperature dependent CRN models extended with energy balance into the class of generalized CRNs with positive real exponents. The embedding increases the state variables by two new ones with a nonlinear algebraic equation between them. Applying the tools for finding realizations of CRNs obeying the mass action law for this generalized case, realizations with prescribed properties (weak reversibility, zero deficiency) were searched in a simple case. It was found in this case that the minimum deficiency is 3, and no reversible realizations exists.
BibTeX:
@article{magyar2018generalized,
  author = {Magyar, Attila},
  title = {Generalized mass action realizations of temperature dependent chemical reaction networks},
  journal = {Reaction Kinetics, Mechanisms and Catalysis},
  publisher = {Springer, IF: 1.428},
  year = {2018},
  pages = {1--14},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/2E32fZGaKKtK92k/download},
  doi = {10.1007/s11144-018-1500-3}
}
Pózna AI, Fodor A, Gerzson M and Hangos KM (2018), "Colored Petri net model of electrical networks for diagnostic purposes", IFAC-PapersOnLine. Vol. 51(2), pp. 260-265. Elsevier.
Abstract: A simple and effective colored Petri net (CPN) model is proposed in this paper for a special type of electrical networks that describe local transformer areas, in order to detect and localize illegal loads that may be present.

The model is decomposed to characteristic structural elements called feeders with one or two sources the computation of which can be performed independently and in parallel. The CPN model allows to handle the interval-type uncertainties in the model in a transparent and effective way.

BibTeX:
@article{Pozna2018,
  author = {Pózna, A I and Fodor, A and Gerzson, M and Hangos, K M},
  title = {Colored Petri net model of electrical networks for diagnostic purposes},
  journal = {IFAC-PapersOnLine},
  publisher = {Elsevier},
  year = {2018},
  volume = {51},
  number = {2},
  pages = {260--265},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/696HeAaKTnRDmj4},
  doi = {10.1016/j.ifacol.2018.03.045}
}
Pózna AI, Hangos KM and Magyar A (2018), "Design of experiments for battery aging estimation", IFAC-PapersOnLine. Vol. 51(28), pp. 386-391. Elsevier.
Abstract: Li-ion batteries are widely used in EV applications and are imposed to several aging effects during their lifetime. Since battery health cannot be measured directly, information about its health can be obtained by iteratively re-estimating the parameters of the model describing its dynamical behavior.

The optimal design of experiments is investigated in this paper. The proposed method applies families of input signals (PRBS current and constant current-constant voltage (CC-CV) signals) to the batteries to estimate the key aging factors. Simulation experiments have been used to analyze the statistical properties of the estimators as a function of the design parameters of the input signal families.

The results show that the CC-CV charging-discharging cycle has the possibility to gain the most information out of the battery model parameter estimation.

BibTeX:
@article{Pozna2018a,
  author = {Pózna, Anna I and Hangos, Katalin M and Magyar, Attila},
  title = {Design of experiments for battery aging estimation},
  journal = {IFAC-PapersOnLine},
  publisher = {Elsevier},
  year = {2018},
  volume = {51},
  number = {28},
  pages = {386--391},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/LXoBeqHqqgCD2PE/download},
  doi = {10.1016/j.ifacol.2018.11.733}
}
Szederkenyi G, Magyar A and Hangos KM (2018), "Analysis and control of polynomial dynamic models with biological applications" Academic Press.
Abstract: Analysis and Control of Polynomial Dynamic Models with Biological Applications synthesizes three mathematical background areas (graphs, matrices and optimization) to solve problems in the biological sciences (in particular, dynamic analysis and controller design of QP and polynomial systems arising from predator-prey and biochemical models). The book puts a significant emphasis on applications, focusing on quasi-polynomial (QP, or generalized Lotka-Volterra) and kinetic systems (also called biochemical reaction networks or simply CRNs) since they are universal descriptors for smooth nonlinear systems and can represent all important dynamical phenomena that are present in biological (and also in general) dynamical systems.
BibTeX:
@book{Szederkenyi2018,
  author = {Szederkenyi, Gabor and Magyar, Attila and Hangos, Katalin M},
  title = {Analysis and control of polynomial dynamic models with biological applications},
  publisher = {Academic Press},
  year = {2018},
  url = {https://www.elsevier.com/books/analysis-and-control-of-polynomial-dynamic-models-with-biological-applications/szederkenyi/978-0-12-815495-3}
}
Szücs V, Fodor A, Göllei A and Görbe P (2018), "Examination of nonlinear distortion of IT power supplies in low voltage grid from the current quality point of view", Acta Physica Polonica, A.. Vol. 134(1) Polish Academy of Sciences IF: 0.545.
Abstract: This work is devoted to investigating the current nonlinear distortion of IT devices linear and switching
mode power supplies. A new developed software package is shown suitable for separate varying degrees load of
functional parts of personal computers. Based on the collected voltage and current harmonic analysis serious
distortion is stated in current time functions in automatic power factor compensating devices, too. Enormous
distortions are observed in simple structure power supplies low power consumption consumer electronic devices.
The consequences and effects of this behavior is described, and possible solutions are adumbrated in detailed
conclusion with integration of domestic size complex energetic systems consisting of renewable energy sources,
battery storage and single and three phase current inverter parts, especially in development of direct current bus
systems in computer system applications.
BibTeX:
@article{Szuecs2018,
  author = {Szücs, V and Fodor, A and Göllei, A and Görbe, P},
  title = {Examination of nonlinear distortion of IT power supplies in low voltage grid from the current quality point of view},
  journal = {Acta Physica Polonica, A.},
  publisher = {Polish Academy of Sciences IF: 0.545},
  year = {2018},
  volume = {134},
  number = {1},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/pkt5HBC7HBf9dCk/download},
  doi = {10.12693/APhysPolA.134.307}
}
Bálint R, Hangos KM and Magyar A (2017), "Optimal scheduling of a household refrigerator using adaptive model predictive technique", In Power Electronics (Ee), 2017 International Symposium on. , pp. 1-6.
Abstract: 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 day-ahead 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.
BibTeX:
@inproceedings{Balint2017,
  author = {Bálint, Roland and Hangos, Katalin M and Magyar, Attila},
  title = {Optimal scheduling of a household refrigerator using adaptive model predictive technique},
  booktitle = {Power Electronics (Ee), 2017 International Symposium on},
  year = {2017},
  pages = {1--6},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/kPysd5JaAckPojQ/download},
  doi = {10.1109/PEE.2017.8171690}
}
Bálint R, Magyar A and Hangos KM (2017), "Cost-optimal model predictive scheduling of home appliances", IFAC-PapersOnLine. Vol. 50(1), pp. 3344-3349. Elsevier.
Abstract: A novel heuristic model-based optimal scheduling algorithm is proposed in this paper to operate heating and cooling type home appliances connected to smart grids where the price of the electrical energy is known in advance and temperature constraints are present. The properties and the use of the proposed algorithm are shown using a simple refrigerator model. The accuracy and the computational properties of the proposed method are compared to the schedule generated by the MPT toolbox. The algorithm works well with a relatively short prediction horizon using a fraction of the computing time needed for the MPT-based method. The robustness of the algorithm is also investigated with respect to the load of the refrigerator. It is shown that the designed schedule with an empty refrigerator is always suitable, yet not optimal, for any loaded case.
BibTeX:
@article{Balint2017a,
  author = {Bálint, Roland and Magyar, Attila and Hangos, Katalin M},
  title = {Cost-optimal model predictive scheduling of home appliances},
  journal = {IFAC-PapersOnLine},
  publisher = {Elsevier},
  year = {2017},
  volume = {50},
  number = {1},
  pages = {3344--3349},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/LzcxBGWRFDTcYzo/download}
}
Göllei A (2017), "Dielectric characteristics of ionic liquids and usage in advanced energy storage cells", In Progress and Developments in Ionic Liquids. InTech.
Abstract: Before the application of ionic liquids, it is important to know their fundamental phys-
ical and chemical properties. Practical experience has shown that it is important to look
at these materials in the behaviour of the function frequency and temperature. To
understand obtained information understanding the molecular-physic bases is needed.
Research and application of ionic liquids have attracted an increasing attention in the
areas of nuclear industry, oil and gas industry, petrochemical industry, chemical and
electrochemical industry. The number of studies dealing with the question is proliferat-
ing which opens up new horizons in the field of chemical operations in microwave field
with ionic liquids (organic chemical synthesis, catalytic operations, etc.). As a result of
the relatively high destroying temperature of ionic liquids, a wider temperature range of
operations can be done and it offers environmental friendly solution in the replacement
of the toxic solvents with generally low evaporating temperatures. The area of applica-
tion is becoming more widespread as electrolyte of novel battery cells. Being aware of
the physical and chemical properties of ionic liquids is necessary in order to apply them.
The main goal of this research was to test the dielectric properties, viscosity and temper-
ature dependence of the electrical conductivity. Based on our results, we can claim that
significant temperature dependence of the three properties can be shown in the case of
ionic liquids. These findings are crucial for the usability of applications, planning and
preparing of production and optimization processes. The significance and importance of
these results become even more obvious if we consider the fact that these energy storage
cells are exposed to large temperature differences. The present study discusses the
sample materials, their usage possibilities and the results of the research from the
previous work of the author. In the case of ionic liquids, it is important to know their
behaviour in electric field. In lot of cases, there is no fundamental difference between the
static and dynamic behaviours. Static state (like in accumulators) is similar to the
dynamic. Ionic liquids are well characterized and grouped with their dielectric behav-
iour. First of all a short summarizing of basics of the electrical permittivity and then a
modelling procedure will be shown modelling lots of parameters using dielectric char-
acteristic of material. At the end the practical usage and application will be shown by
using ionic liquids as the electrolyte of batteries.
BibTeX:
@incollection{Goellei2017,
  author = {Göllei, Attila},
  title = {Dielectric characteristics of ionic liquids and usage in advanced energy storage cells},
  booktitle = {Progress and Developments in Ionic Liquids},
  publisher = {InTech},
  year = {2017},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/wYH9et6Mj6ofetD/download},
  doi = {10.5772/66948}
}
Koók L, Nemestóthy N, Bakonyi P, Göllei A, Rózsenberszki T, Takács P, Salekovics A, Kumar G and Bélafi-Bakó K (2017), "On the efficiency of dual-chamber biocatalytic electrochemical cells applying membrane separators prepared with imidazolium-type ionic liquids containing [NTf2]- and [PF6]- anions", Chemical Engineering Journal., IF: 6.735, 2017. Vol. 324, pp. 296-302. Elsevier, IF: 6.735.
Abstract: In this study, the dependency of energy recovery on separator characteristics applied in microbial fuel cells (MFCs) was sought by testing an emerging class of membranes (supported ionic liquid membranes (SILMs), prepared with [hmim][PF6] and [bmim][NTf2] ionic liquids) comparatively with well-known proton exchange (Nafion N115) and microfiltration (PVDF) counterparts. Crucial membrane features such as O2 and substrate (acetate as the sole carbon source) crossovers were assessed and as a result, mass transfer as well as diffusivity coefficients of these compounds (kO, kA, DO, DA, respectively) were determined. The experiments showed that SILM-operated MFCs could work in a reliable way and among them, the [bmim][NTf2]-based one produced higher specific energy yield (YS = 9.78 kJ g−1CODin m−2) than the Nafion-MFC (YS = 8.25 kJ g−1CODin m−2) used as an important reference. This outcome was found to be associated with the membrane-cross oxygen shuttle properties of the membranes (kO = 1.25 cm s−1 and 1.31 cm s−1, respectively). As for the two SILMs, significant differences in terms of the energy yield, mass transfer and diffusion coefficients were noted, however, it has appeared from cell polarization measurements that the internal resistances of the SILM-MFCs were nearly the same. The evaluation of the SILM-operated MFCs’ power production was complemented by measuring the dielectric traits of ionic liquids that can be related with the ion conductivity of these materials. It turned out that the [hmim][PF6] IL had an order of magnitude lower ionic conductivity.
BibTeX:
@article{Kook2017,
  author = {Koók, L and Nemestóthy, N and Bakonyi, P and Göllei, Attila and Rózsenberszki, T and Takács, P and Salekovics, A and Kumar, G and Bélafi-Bakó, K},
  title = {On the efficiency of dual-chamber biocatalytic electrochemical cells applying membrane separators prepared with imidazolium-type ionic liquids containing [NTf2]- and [PF6]- anions},
  journal = {Chemical Engineering Journal},
  publisher = {Elsevier, IF: 6.735},
  year = {2017},
  volume = {324},
  pages = {296--302},
  url = {https://www.sciencedirect.com/science/article/pii/S1385894717307611},
  doi = {10.1016/j.cej.2017.05.022}
}
Neukirchner L, Görbe P and Magyar A (2017), "Voltage unbalance reduction in the domestic distribution area using asymmetric inverters", Journal of Cleaner Production. Vol. 142, pp. 1710-1720. Elsevier, IF: 5.651.
Abstract: Voltage unbalance is a major yet often overlooked power quality problem in low voltage residential feeders due to the random location and rating of single-phase renewable sources and uneven distribution of household loads. This paper proposes a new indicator of voltage deviation that may serve as a basis of analysis and compensation methods in this dimension of power quality. The paper proposes three main results. First of all a novel voltage norm capable of jointly indicating unbalance and under-voltage in a single value, afterwards a three phase unbalance reduction controller structure is given. As the third main result, the proposed controller structure is integrated with an optimization based control algorithm that uses asynchronous parallel pattern search as its engine. The suggested structure and the underlying three phase power grid model has been implemented in a dynamical simulation environment and tested against engineering expectations.

The simulation based experiments served as a proof of concept for the proposed complex control structure. The experiments included performance and robustness analysis, both of them concluded that the proposed control and inverter structure is promising.

The proposed three phase inverter structure together with the control algorithm connected with a renewable source (photovoltaic panel or wind turbine) is capable of an asymmetric power injection or rerouting the energy flow to the grid so that the voltage unbalance decrease. This is also important from the environmental point of view since the achieved power loss reduction can easily be translated to CO2 emission reduction and carbon footprint - these indicators has also been calculated.

BibTeX:
@article{Neukirchner2017,
  author = {Neukirchner, L and Görbe, P and Magyar, A},
  title = {Voltage unbalance reduction in the domestic distribution area using asymmetric inverters},
  journal = {Journal of Cleaner Production},
  publisher = {Elsevier, IF: 5.651},
  year = {2017},
  volume = {142},
  pages = {1710--1720},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/jx9AxQ9NZA5Ao2y/download},
  doi = {10.1016/j.jclepro.2016.11.119}
}
Pózna AI, Magyar A and Hangos KM (2017), "Model identification and parameter estimation of lithium ion batteries for diagnostic purposes", In Power Electronics (Ee), 2017 International Symposium on., Oct, 2017. , pp. 1-6. IEEE.
Abstract: A parameter estimation study is reported here to estimate the temperature-dependent internal resistance of a lithium ion battery that is connected to the state of its health. A simple equivalent electrical circuit model was used for this purpose that is nonlinear both in its variables and in its parameters. Parameter sensitivity analysis showed that under conditions of constant charging/discharging current there is a linear dependency between some model parameters.
BibTeX:
@inproceedings{Pozna2017,
  author = {Pózna, Anna I and Magyar, Attila and Hangos, Katalin M},
  title = {Model identification and parameter estimation of lithium ion batteries for diagnostic purposes},
  booktitle = {Power Electronics (Ee), 2017 International Symposium on},
  publisher = {IEEE},
  year = {2017},
  pages = {1--6},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/3xaEZQNxr8orrHW/download},
  doi = {10.1109/PEE.2017.8171673}
}
Bálint R and Magyar A (2016), "Refrigerator optimal scheduling to minimise the cost of operation", Hungarian Journal of Industry and Chemistry. Vol. 44(2), pp. 99-104. De Gruyter Open.
Abstract: The cost optimal scheduling of a household refrigerator is presented in this work. The fundamental approach is the model predictive control methodology applied to the piecewise affine model of the refrigerator.

The optimisation could not be solved using off-the-shelf tools, e.g. Multi-Parametric Toolbox, so a binary treebased optimal scheduling algorithm has been developed for this problem.

BibTeX:
@article{Balint2016,
  author = {Bálint, Roland and Magyar, Attila},
  title = {Refrigerator optimal scheduling to minimise the cost of operation},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2016},
  volume = {44},
  number = {2},
  pages = {99--104},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/DQzM5f64Rsrj743/download},
  doi = {10.1515/hjic-2016-0012}
}
Göllei A, Görbe P and Magyar A (2016), "Measurement based modeling and simulation of hydrogen generation cell in complex domestic renewable energy systems", Journal of Cleaner Production., IF: 5.715, 2016. Vol. 111, pp. 17-24. Elsevier.
Abstract: A measurement based model of hydrogen generating cell for simulation of complex energy system is described in this paper. The model parameter estimation has been performed based on measurement data obtained during the detailed examination of a demonstration cell. A series of experiments has been carried out on a HHO (Oxyhydrogen) gas producing dry cell in order to find its optimal electrochemical, (e.g. electrolyte concentration, current value, etc.) and geometric (distance between the plates) parameters. The novel element is the current and concentration dependent Matlab Simulink model of the hydrogen generation cell. Hydrogen generation enables the long range storage of spare electric energy collected but not consumed or injected into the low voltage grid. The generated hydrogen can be consumed by vehicles for transportation purposes or it can be applied in fuel cells generating direct electrical energy for energy-deficient low voltage network situations. The potentially occurring energetic situations were simulated in a complex energetic system model. The simulations showed that the presented hydrogen generating cell model met the engineering expectations.
BibTeX:
@article{Goellei2016,
  author = {Göllei, Attila and Görbe, P and Magyar, Attila},
  title = {Measurement based modeling and simulation of hydrogen generation cell in complex domestic renewable energy systems},
  journal = {Journal of Cleaner Production},
  publisher = {Elsevier},
  year = {2016},
  volume = {111},
  pages = {17--24},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/CxwkW2dmT6pXTRE/download},
  doi = {10.1016/j.jclepro.2015.06.025}
}
Lipták G, Magyar A and Hangos KM (2016), "LQ control of Lotka-Volterra systems based on their locally linearized dynamics", IFAC-PapersOnLine. Vol. 49(10), pp. 241-245. Elsevier.
Abstract: 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.
BibTeX:
@article{Liptak2016,
  author = {Lipták, G and Magyar, Attila and Hangos, Katalin M},
  title = {LQ control of Lotka-Volterra systems based on their locally linearized dynamics},
  journal = {IFAC-PapersOnLine},
  publisher = {Elsevier},
  year = {2016},
  volume = {49},
  number = {10},
  pages = {241--245},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/fF5rRns45poi4BJ/download},
  doi = {10.1016/j.ifacol.2016.07.536}
}
Neukirchner L, Göllei A, Görbe P and Magyar A (2016), "Voltage unbalance reduction of a local transformer area with domestic asymmetrical inverter and optimal control design", Int. J. of Thermal & Environmental Engineering. Vol. 12(2), pp. 129-134.
Abstract: The three-phase unbalance problem can introduce additional losses in distribution networks due to both negative and zero sequence components, which leads to inefficient power consumption and increased CO 2 emission of low voltage transformer area, moreover it causes safety possible malfunction of energy transportation networks. The aim of this paper is to introduce a new voltage unbalance indicator and a control algorithm that compensates source voltage unbalances. To examine the available measures of voltage asymmetry and make a comparison from the transient behaviours point of view. Analytical and simulation, results are presented to illustrate the effectiveness of the new techniques.
BibTeX:
@article{Neukirchner2016,
  author = {Neukirchner, L and Göllei, Attila and Görbe, P and Magyar, A},
  title = {Voltage unbalance reduction of a local transformer area with domestic asymmetrical inverter and optimal control design},
  journal = {Int. J. of Thermal & Environmental Engineering},
  year = {2016},
  volume = {12},
  number = {2},
  pages = {129--134},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/coYSwWDads7oLzR/download},
  doi = {10.5383/ijtee.12.02.009}
}
Sőrés M and Fodor A (2016), "Simulation of electrical grid with OMNET++ open source discrete event system simulator", Hungarian Journal of Industry and Chemistry. Vol. 44(2), pp. 85-91. De Gruyter Open.
Abstract: The simulation of electrical networks is very important before development and servicing of electrical networks and grids can occur. There are software that can simulate the behaviour of electrical grids under different operating conditions, but these simulation environments cannot be used in a single cloud-based project, because they are not GNU-licensed software products. In this paper, an integrated framework was proposed that models and simulates communication networks. The design and operation of the simulation environment are investigated and a model of electrical components is proposed. After simulation, the simulation results were compared to manual computed results.
BibTeX:
@article{Sores2016,
  author = {Sőrés, M and Fodor, A},
  title = {Simulation of electrical grid with OMNET++ open source discrete event system simulator},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2016},
  volume = {44},
  number = {2},
  pages = {85--91},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/MXiY55zoieMtmRP/download},
  doi = {10.1515/hjic-2016-0010}
}
Tar S and Fodor A (2016), "Cloud-based application for Smart Grid simulation", Hungarian Journal of Industry and Chemistry. Vol. 44(2), pp. 81-83. De Gruyter Open.
Abstract: This study provides an overview of the content of an R&D project for increasing the efficiency of smart grids to analyse the energy market, consumption, generation, and renewable energy usage. The new energy participants, for example decentralized generation, dynamic consumption, and weather-dependent power plants, are facing challenges. This project offers solutions to these challenges: modelling of distribution networks, forecasts of renewable energy sources distributed generation (RES-DG), micro-grid management and responses to demand in new, complex solutions. A hardware device is being developed for smart grids and security modules to enhance IT security.
BibTeX:
@article{Tar2016,
  author = {Tar, Szabolcs and Fodor, Attila},
  title = {Cloud-based application for Smart Grid simulation},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2016},
  volume = {44},
  number = {2},
  pages = {81--83},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/CKxBQcneJ7wTaZN/download},
  doi = {10.1515/hjic-2016-0009}
}
Fodor A (2015), "Model analysis, parameter estimation and control of a synchronous generator= Egy ipari szinkrongenerátor paramétereinek a becslése és szabályozása". Thesis at: Ph. D. Thesis, University of Pannonia,.
Abstract: Global warming caused by greenhouse gases and the constantly growing use of elec tricity of the industry is forcing power plants operator’s engineers to achieve the higher efficiency of the power plants. In many cases, increasing the efficiency can be achieved by modernization of the control system, as it is done in the MVM Paks Nuclear Power Plant. The dissertation deals with the synchronous generator used in nuclear power plants, thermal power plants and hydropower plants, presents the design of an advanced controller for its power control together with the necessary preliminary steps. The basis of the design is the state-space model of the synchronous generator. Simple but effective model analysis methods were proposed for model verification and for preliminary parameter selection in parameter estimation of the synchronous generator. Based on the result of the sensitivity analysis, it is possible to define 4 groups of parameters. Based on this results 9 parameters were selected to parameter estimation. A parameter estimation method using passive industrial measurement was also proposed for a synchronous generator that uses passive measurement of power changing transients. The quality of the parameter estimation was characterized using the quality, the fit and the dependence of the error function on the parameters. The confidence region was also estimated from the level sets of the error function. Based on the model and the parameter estimation a servo version of a Linear Quadratic Regulator (LQR) has been proposed for control of the industrial synchronous generator operating in MVM Paks NPP. The proposed LQ-servo controller was verified by simulation using step changes in active power. Based on the simulation the developed LQ-servo controller provides better control than the existing
PID controllers in MVM Paks NPP.
BibTeX:
@phdthesis{Fodor2015,
  author = {Fodor, Attila},
  title = {Model analysis, parameter estimation and control of a synchronous generator= Egy ipari szinkrongenerátor paramétereinek a becslése és szabályozása},
  school = {Ph. D. Thesis, University of Pannonia,},
  year = {2015},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/fEs7jxK86QNXoNg/download}
}
Hangos K, Magyar A and Szederkényi Gá (2015), "Entropy-inspired Lyapunov functions and linear first integrals for positive polynomial systems", Mathematical Modelling of Natural Phenomena., IF: 0.82, 2015. Vol. 10(3), pp. 105-123. EDP Sciences.
Abstract: 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.
BibTeX:
@article{Hangos2015,
  author = {Hangos, KM and Magyar, Attila and Szederkényi, Gábor},
  title = {Entropy-inspired Lyapunov functions and linear first integrals for positive polynomial systems},
  journal = {Mathematical Modelling of Natural Phenomena},
  publisher = {EDP Sciences},
  year = {2015},
  volume = {10},
  number = {3},
  pages = {105--123},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/D3XTHjx52F5anEf/download},
  doi = {10.1051/mmnp/201510309}
}
Magyar A and Hangos KM (2015), "Globally stabilizing state feedback control design for Lotka-Volterra systems based on underlying linear dynamics", IFAC-PapersOnLine. Vol. 48(11), pp. 1000-1005. Elsevier.
Abstract: Using translated X-factorable phase space transformations and nonlinear variable transformations a dynamically similar linear ODE model is associated to the Lotka-Volterra system models with a positive equilibrium point. This enables to use a linear full state feedback controller to stabilize the system in controllable cases, that leaves the open loop equilibrium point unchanged. The linear state feedback controller design problem in the general case has also been formulated to ensure the compartmental property of the closed loop system from which the existence of a diagonal Lyapunov function follows. Further extension has been obtained by using the time re-parametrization transformation defined for quasi-polynomial models.
BibTeX:
@article{Magyar2015,
  author = {Magyar, Attila and Hangos, Katalin M},
  title = {Globally stabilizing state feedback control design for Lotka-Volterra systems based on underlying linear dynamics},
  journal = {IFAC-PapersOnLine},
  publisher = {Elsevier},
  year = {2015},
  volume = {48},
  number = {11},
  pages = {1000--1005},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/XZYPLE3CG9Ld87Q/download},
  doi = {10.1016/j.ifacol.2015.09.323}
}
Neukirchner L, Göllei A, Görbe P and Magyar A (2015), "Carbon footprint reduction via voltage asymmetry compensation of three-phase low voltage grid utilizing small domestic power plants", CHEMICAL ENGINEERING. Vol. 45
Abstract: The three-phase unbalance problem can introduce additional losses in distribution networks due to both negative and zero sequence components, which leads to inefficient power consumption and increased CO2 emission of low voltage transformer area, moreover it causes safety possible malfunction of energy transportation networks. The aim of this paper is to examine two new analytical approaches to the voltage asymmetry phenomena and the following power losses and based on this definitions novel control algorithms are suggested and examined in simulation environment. To perform the analysis a power distribution systemtextquoterights Matlab/Simulink model will be created with a domestic size complex energetic system with a power storage module and with renewable sources in a household environment. Based on the novel compensation control algorithm we calculate the possible CO2 emission reduction and carbon footprint.
BibTeX:
@article{Neukirchner2015,
  author = {Neukirchner, L and Göllei, Attila and Görbe, P and Magyar, A},
  title = {Carbon footprint reduction via voltage asymmetry compensation of three-phase low voltage grid utilizing small domestic power plants},
  journal = {CHEMICAL ENGINEERING},
  year = {2015},
  volume = {45},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/7Je7oCjBpMJiX3a/download},
  doi = {10.3303/CET1545048}
}
Neukirchner L, Görbe P and Magyar A (2015), "Examination of different voltage asymmetry norms under transient behavior of three-phase low voltage power systems containing small domestic power plants", In PowerTech, 2015 IEEE Eindhoven. , pp. 1-6. IEEE.
Abstract: The three-phase unbalance problem is a familiar issue. It can introduce additional power losses in distribution networks due to both negative and zero sequence components. It could also limit the loading capability of distribution transformers, well below their nominal ratings. There are many voltage unbalance definitions for three-phase three-wire systems. This paper proposes new indicators of the unbalance power that allows a different tool for analysis of inefficiencies caused by nonlinear loads. The aim of this paper is to examine the available measures of voltage asymmetry and make a comparison from the transient behaviours point of view. As a next step, a compensation algorithm is to be developed which is based on a loss function derived from the results of the present analysis.
BibTeX:
@incollection{Neukirchner2015a,
  author = {Neukirchner, L and Görbe, P and Magyar, Attila},
  title = {Examination of different voltage asymmetry norms under transient behavior of three-phase low voltage power systems containing small domestic power plants},
  booktitle = {PowerTech, 2015 IEEE Eindhoven},
  publisher = {IEEE},
  year = {2015},
  pages = {1--6},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/TnetzB2sgxJ5oc5/download},
  doi = {10.1109/PTC.2015.7232383}
}
Fodor A, Bálint R, Magyar A and Szederkényi G (2014), "Stability and parameter sensitivity analysis of an induction motor", Hungarian Journal of Industry and Chemistry. Vol. 42(2), pp. 109-113. De Gruyter Open.
Abstract: A simple dynamical model of an induction motor is derived and analyzed in this paper based on engineering principles that describe the mechanical phenomena together with the electrical model. The used state space model consists of nonlinear state equations. The model has been verified under the usual controlled operating conditions when the speed is controlled. The effect of load on the controlled induction motor has been analyzed by simulation. The sensitivity analysis of the induction motor has been applied to determine the model parameters to be estimated.
BibTeX:
@article{Fodor2014,
  author = {Fodor, Attila and Bálint, Roland and Magyar, Attila and Szederkényi, G},
  title = {Stability and parameter sensitivity analysis of an induction motor},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2014},
  volume = {42},
  number = {2},
  pages = {109--113},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/6jo9r8K3ncPbBe8/download}
}
Fodor A, Magyar A and Hangos KM (2014), "Multiple-input--multiple-output Linear-Quadratic control of the energy production of a synchronous generator in a nuclear power plant", Electric Power Components and Systems. Vol. 42(15), pp. 1673-1682. Taylor & Francis.
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 Anderson, P., and Fouad, A., Power-Systems-Control and Stability, Ames, IA: The IOWA State University Press, Chap. 4, 1977. [Google Scholar], 2 Fodor, A., Magyar, A., and Hangos, K.M., Control-oriented modeling of the energy-production of a synchronous generator in a nuclear power plant, Energy, . 39, pp. 135–145, 2012.[Crossref], [Web of Science ®], , [Google Scholar]], 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.
BibTeX:
@article{Fodor2014a,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {Multiple-input--multiple-output Linear-Quadratic control of the energy production of a synchronous generator in a nuclear power plant},
  journal = {Electric Power Components and Systems},
  publisher = {Taylor & Francis},
  year = {2014},
  volume = {42},
  number = {15},
  pages = {1673--1682},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/QdB6qSxiqf4o5KB/download},
  doi = {10.1080/15325008.2014.950359}
}
Göllei A, Görbe P and Magyar A (2014), "Examination, modelling and simulation of hydrogen generation cell for complex renewable energy system", Chemical Engineering Transactions. Vol. 39, pp. 409-414.
Abstract: Nowadays, the growing need for energy from renewable sources and growing revulsion towards fossil and nuclear fuels turns sustainable and green energy in the foreground. Producing (electrical) energy from renewable sources hardly means difficulties but the storage of the energy not consumed immediately is a great engineering challenge. In the present paper a complex model has been developed by investigating renewable energy sources, converting currently unnecessary energy to Hydrogen for storage purposes and feeding the main grid. A measurement based model of a Hydrogen generating cell developed for simulation of complex energetic system is presented in this paper. The parameter estimation of the static model has been performed based on measurement data collected during the detailed examination of a demonstration cell. Series of experiments has been carried out on a HHO gas producing dry cell in order to find out if there are optimal electrolyte concentration, current value, or geometric parameter (distance between plates) values for this equipment. During the measurement KOH electrolyte solution was used while different signals has been measured, for example cell voltage, gas production value. As a result of the experiments, a cell operating in an optimal way has been developed. The novel element of this work is the temperature and concentration dependent Matlab Simulink model of the hydrogen generation cell. Using this model, a dynamic simulator of a complex domestic power plant using renewable energy source and H2 generation cell become available. Hydrogen generation enables the long range storage of spare electric energy collected but not consumed or injected into the low voltage grid. The generated Hydrogen can be consumed by vehicles for transportation purposes or it can be applied in fuel cells generating direct electrical energy for energy-deficient low voltage network situations. Energetic situations potentially occurring in practice have been simulated in the complex model. Several hours of simulations showed that the presented H2 generating cell model performed well. Producing H2 from excess energy is not a brand new invention. This is the alternative way to store and convert renewable energy for further utilization. The produced Hydrogen can be used to store, to use in power cell to convert back to electric energy or to use in Hydrogen propulsion vehicles. Among the numerous realized H2 producing applications the most important class is when the energy consumption and the quantity of produced H2 is controlled. When the power consumption and generation are continuous (and not necessarily deterministic) function of time, the H2 production depends solely on the excess energy of the grid.
BibTeX:
@article{Goellei2014,
  author = {Göllei, A and Görbe, P and Magyar, A},
  title = {Examination, modelling and simulation of hydrogen generation cell for complex renewable energy system},
  journal = {Chemical Engineering Transactions},
  year = {2014},
  volume = {39},
  pages = {409--414},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/W9qFyzatfBHMmjZ/download},
  doi = {10.3303/CET1439069}
}
Göllei A, Görbe P, Magyar A and Neukirchner L (2014), "Measurement-based modelling and simulation of a hydrogen generating dry cell for complex domestic renewable energy systems", Hungarian Journal of Industry and Chemistry. Vol. 42(2), pp. 85-89. De Gruyter Open.
Abstract: Nowadays, the growing need for energy from renewable sources and growing revulsion towards fossil and nuclear fuels puts sustainable and green energy in the limelight. Producing (electrical) energy in domestic power plants from renewable sources (mainly solar and wind) hardly results in difficulties, but the storage of energy not consumed immediately is a great engineering challenge. In the present paper a complex model has been developed by investigating renewable energy sources, the surplus energy not actually consumed and stored in electrical vehicle (EV) batteries, the conversion to hydrogen for storage purposes and how the main grid is fed. A measurement-based model of a hydrogen generating cell developed for the simulation of complex energetic systems. The parameter estimation of the static model was based on the collected measurement data coming from the detailed examination of a built demonstration cell. The novel element of this work is the Matlab Simulink model for the hydrogen generation cell. Using this model, a dynamic simulator of a complex domestic power plant is made available using renewable energy sources and hydrogen generation cells. Hydrogen generation enables the lossless long-term storage of surplus electric energy collected, but not consumed or injected into the low voltage grid. The generated hydrogen can be consumed for transportation purposes in suitable vehicles or it can be applied in fuel cells generating direct electrical energy for energy-deficient low voltage network situations. Energetic situations potentially occurring in practice were simulated in our complex model. Simulations showed that the presented model is suitable for domestic scale low voltage complex energetic systems.
BibTeX:
@article{Goellei2014a,
  author = {Göllei, Attila and Görbe, P and Magyar, Attila and Neukirchner, L},
  title = {Measurement-based modelling and simulation of a hydrogen generating dry cell for complex domestic renewable energy systems},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2014},
  volume = {42},
  number = {2},
  pages = {85--89},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/rtmGNGkaZoAMaTD/download}
}
Görbe P, Fodor A, Magyar A and Hangos KM (2014), "Experimental study of the nonlinear distortion caused by domestic power plants", Applied Thermal Engineering., IF: 2.739, 2014. Vol. 70(2), pp. 1288-1293. Elsevier.
Abstract: An experimental study is presented in this work, where the distortion effect of a 4 kW photovoltaic domestic power plant, located in Hungary, has been examined. The power plant is connected to a low voltage grid by using a standard grid synchronized inverter. Based on the measured voltage and current signals we examined the frequency domain behavior of the power plant, and the effect of the power plant on the power quality, mainly the total harmonic distortion. The measurement database shows that the synchronous power injection of the photovoltaic domestic power plant has serious effect on the voltage distortion of the low voltage grid, and this effect highly depends on the actual generated power.

Based on the experimental results, suggestions on how to operate the photovoltaic domestic power plant are formulated that enable its energy-efficient operation with minimal distortion effect.

BibTeX:
@article{Goerbe2014,
  author = {Görbe, Peter and Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {Experimental study of the nonlinear distortion caused by domestic power plants},
  journal = {Applied Thermal Engineering},
  publisher = {Elsevier},
  year = {2014},
  volume = {70},
  number = {2},
  pages = {1288--1293},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/TCyzgkwYNk2wpid/download},
  doi = {10.1016/j.applthermaleng.2014.05.072}
}
Neukirchner L and Magyar A (2014), "Quasi-polynomial representation-based control of mechanical systems", Hungarian Journal of Industry and Chemistry. Vol. 42(2), pp. 91-95. De Gruyter Open.
Abstract: A simple kinematic model of a differential steering mobile robot is investigated using a nonlinear technique based on the quasi-polynomial representation of the dynamical model. Dynamical systems can be embedded in the generalized Lotka-Volterrs (or quasi-polynomial) form under mild conditions. Quasi-polynomial systems are good candidates for a general nonlinear system representation, since their global stability analysis is equivalent to the feasibility of a linear matrix inequality. The stabilizing quasi-polynomial state feedback controller design problem is equivalent to the feasibility of a bilinear matrix inequality. The classical stabilizing state feedback problem for quasi-polynomial systems was extended with the ability of tracking time-dependent reference signals. It is shown that the stabilizing quasi-polynomial controller design is equivalent to a bilinear matrix inequality. The results are applied to the model of the differential steering mobile robot. The goal reaching quasi-polynomial controller is shown to be a special kind of proportional state feedback.
BibTeX:
@article{Neukirchner2014,
  author = {Neukirchner, L and Magyar, A},
  title = {Quasi-polynomial representation-based control of mechanical systems},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2014},
  volume = {42},
  number = {2},
  pages = {91--95},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/wNYRBxtDnjMFRNs/download}
}
Göllei A and Magyar A (2013), "Ionic liquids in advanced energy storage cells", Hungarian Journal of Industry and Chemistry. Vol. 41(1), pp. 11-15. De Gruyter Open.
Abstract: The interest in the research and application of ionic liquids has been increased worldwide, especially in petrochemical industry, nuclear industry, oil and gas industry, chemical, and electro-chemical industry. In the field of chemical operations in microwave field with ionic liquids (organic chemical synthesis, catalytic operations, etc.) new horizons opened that were supported by the dramatically increasing number of studies dealing with this question and their impact. Due to the high durability of ionic liquids as a function of temperature, a wider temperature range of operations can be accessed. In addition, it offers environmental friendly solution in the replacement of the toxic solvents with generally low volatility. The area of application extends to electrolytes of novel battery cells. The important prerequisite for application of ionic liquids is the knowledge of their physical and chemical properties. Our aim was to test the dielectric properties, viscosity, and temperature dependence of the electrical conductivity. Considering our measurements, it can be declared that the aforementioned properties show significant temperature dependence in the case of ionic liquids. This knowledge is important for the usability, design and execution of production and related optimization processes. It is particularly important that energy storage cells can be exposed to large temperature fluctuations. This study discusses the sample materials, the usage possibilities of the sample materials and the obtained results.
BibTeX:
@article{Goellei2013,
  author = {Göllei, Attila and Magyar, Attila},
  title = {Ionic liquids in advanced energy storage cells},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2013},
  volume = {41},
  number = {1},
  pages = {11--15},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/WNsGWrFYkymdpct/download}
}
Görbe P, Magyara A, Fodora A and Hangos KM (2013), "Effect of domestic power plants to the low voltage transformer areas from the nonlinear distortion point of view", Chemical Engineering. Vol. 35
Abstract: A case study is presented in this work, where a 4 kW photovoltaic domestic power plant, located in Hungary, has been examined. Based on the measured voltage and current signals we examined the frequency domain behaviour of the power plant and the effect to the power quality, mainly the total harmonic distortion, of the low voltage transformer area. Evaluation of the measurement database suggests that this type of synchronous power injection has serious effect on the voltage distortion of the low voltage grid, and this effect highly depends on the ratio of the injected power magnitude related to the nominal power of the inverter part. The available hardware structure enables us not only to eliminate this phenomenon but also to improve the existing quality of the low voltage grid. It needs only a modified control structure that can be implemented in the inverter control device. It causes power loss reduction in the low voltage grid. This reduction helps lowering the power loss in the phase conductor, and more radically in the neutral conductor of the transportation line. In the case of electric power production from fossil sources, it lowers the greenhouse gas emission, to lower the environmental and social- welfare effects of the climate change.
BibTeX:
@article{Goerbe2013,
  author = {Görbe, P and Magyara, Attila and Fodora, Attila and Hangos, Katalin M},
  title = {Effect of domestic power plants to the low voltage transformer areas from the nonlinear distortion point of view},
  journal = {Chemical Engineering},
  year = {2013},
  volume = {35},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/oy8ZcMKLnwkJaSG/download},
  doi = {10.3303/CET1335217}
}
Görbe P (2013), "Áram minőség optimalizálása kisfeszültségű nemlineáris torzított hálózatokban megújuló energiaforrások komplex integrációjával". Thesis at: Ph. D. Thesis, University of Pannonia,.
Abstract: The Fukushima nuclear accident, the observed effects of global warming and the significantly increasing price of fossil fuels steers the economic-, political- and scientific leaders towards the exploitation of renewable energy sources. There are still serious technical difficulties in balancing the energy production and consumption in a convenient way. The intelligent coordination and control of energy production and consumption and the construction of fast and high capacity storage facilities is a very actual scientific challenge. The dissertation presents a general temperature-dependent model for a family of batteries developed for electrical vehicle (EV) use. In addition to the model’s derivation, the methodology and instruments developed to accurately measure the temperature-dependent parameters are also presented together with a Matlab Simulink block for a temperature-dependent battery. This information is very important for simulating the behavior of an EV in real-life weather and temperature conditions and for simulating the quick charging process, which are key issues for spreading of EV-s. Besides this, the dissertation describes a low-voltage grid composed of small, domestic power plants fueled by clean and renewable energy sources and augmented with electric vehicle batteries as power storage devices. I propose that this grid could utilize a complex multifunctional control unit capable of optimizing the working point and charging current of the system, while also implementing an active power factor correction, lowering existent harmonic distortion and controlling the voltage level in the low-voltage power lines. The complex controller structure pro- posed in this thesis work contains the following novel components: an upper harmonic controller which (together with the connection voltage controller) minimizes the amplitudes of the 3rd, 5th, 7th, 9th, and 11th high-order components in the output voltage; and a connection voltage controller which controls the energy flow between the low-voltage network, its renewable energy sources and the electrical vehicle batteries. Unlike other similar approaches, the harmonic controller proposed in this thesis work does not rely on a measured current signal but rather optimizes the voltage shape, the latter of which depends on the nonlinear distortion of the whole low-voltage transformer area and determines additional power losses. I analyzed the proposed controller via simulations in a Matlab environment and as a result, achieved substantial improvements in the output voltage, current waveform and energy flow of the system’s low-voltage conditions. My calculations show that the implementation could achieve substantial reductions in CO2 emissions for an average household. The robustness of the method against nonlinear loads and fluctuations in overloaded and overproduced cases was also tested.
BibTeX:
@phdthesis{Goerbe2013a,
  author = {Görbe, Peter},
  title = {Áram minőség optimalizálása kisfeszültségű nemlineáris torzított hálózatokban megújuló energiaforrások komplex integrációjával},
  school = {Ph. D. Thesis, University of Pannonia,},
  year = {2013},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/KKqyCRMjP7pifR2/download}
}
Magyar A and Fodor A (2013), "Quasi-polynomial control of a synchronous generator", Hungarian Journal of Industry and Chemistry. Vol. 41(1), pp. 51-57. De Gruyter Open.
Abstract: A simple dynamic model of permanent magnet synchronous generator, that is used for electrical energy generation is investigated in this work using a nonlinear technique based on the quasi-polynomial representation of the dynamical model. It is well known that dynamical systems with smooth nonlinearities can be embedded in a quasi-polynomial model. Quasipolynomial systems are good candidates for a general nonlinear system representation since their global stability analysis is equivalent to the feasibility of a LMI. Moreover, the stabilizing quasi-polynomial state feedback controller design problem is equivalent to the feasibility of a bilinear matrix inequality. The classical stabilizing state feedback problem for quasipolynomial systems has been extended in this work with the ability of tracking time-dependent reference signals. It is shown, that the stabilizing quasi-polynomial servo controller design is equivalent to a bilinear matrix inequality. The results are applied to the model of a synchronous generator.
BibTeX:
@article{Magyar2013,
  author = {Magyar, Attila and Fodor, Attila},
  title = {Quasi-polynomial control of a synchronous generator},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2013},
  volume = {41},
  number = {1},
  pages = {51--57},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/EoCotgmSFLTcy4d/download}
}
Magyar A and Hangos KM (2013), "Control Lyapunov function based feedback design for quasi-polynomial systems", IFAC Proceedings Volumes. Vol. 46(23), pp. 128-133. Elsevier.
Abstract: The aim of this work is to present an entropy-like Lyapunov function based dynamic feedback design technique for quasi-polynomial and Lotka-Volterra systems. It is shown, that the dynamic feedback design problem is equivalent to the feasibility of a bilinear matrix inequality. The problem is also formulated as a control Lyapunov function based feedback design when the Lyapunov function parameters are given, the solution of this problem can be obtained by solving a linear matrix inequality. The developed method is illustrated on a simple numerical example.
BibTeX:
@article{Magyar2013a,
  author = {Magyar, Attila and Hangos, Katalin M},
  title = {Control Lyapunov function based feedback design for quasi-polynomial systems},
  journal = {IFAC Proceedings Volumes},
  publisher = {Elsevier},
  year = {2013},
  volume = {46},
  number = {23},
  pages = {128--133},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/nFzsaLP2iceeSdj/download},
  doi = {10.3182/20130904-3-FR-2041.00108}
}
Magyar A, Hangos KM and Szederkényi G (2013), "Stabilizing dynamic feedback design of quasi-polynomial systems using their underlying reduced linear dynamics", In Decision and Control (CDC), 2013 IEEE 52nd Annual Conference on. , pp. 636-641.
Abstract: Based on the underlying dynamically similar linear system of a quasi-polynomial (QP) system [7], a dynamic feedback controller for single input QP systems is proposed in this work that can locally stabilize the closed-loop system using a pre-defined quadratic control Lyapunov function. Since the parameter matrix of the dynamically similar reduced linear dynamics depends linearly on the feedback gain parameters, the controller can be designed by solving LMIs. Conditions for extending the controller design for obtaining a globally stable closed-loop system are also investigated.
BibTeX:
@inproceedings{Magyar2013b,
  author = {Magyar, Attila and Hangos, Katalin M and Szederkényi, G},
  title = {Stabilizing dynamic feedback design of quasi-polynomial systems using their underlying reduced linear dynamics},
  booktitle = {Decision and Control (CDC), 2013 IEEE 52nd Annual Conference on},
  year = {2013},
  pages = {636--641},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/gJSRkooAsaz93pP/download},
  doi = {10.1109/CDC.2013.6759953}
}
Fodor A, Magyar A and Hangos KM (2012), "Control-oriented modeling of the energy-production of a synchronous generator in a nuclear power plant", Energy., IF: 3.651, 2012. Vol. 39(1), pp. 135-145. Elsevier.
Abstract: Nuclear Power Plant (Hungary) is developed in this paper based on first engineering principles that is able to describe the time-varying active and reactive power output of the generator. These generators are required to take part in the reactive power support of the power grid following the demand of a central dispatch center, and also contribute to the frequency control of the grid. The developed model has been verified under the usual controlled operating conditions when the frequency and the active power are controlled.

Static and dynamic sensitivity analysis has been applied to determine the model parameters to be estimated. The model parameters have been estimated applying the asynchronous parallel pattern search method using real measured data from the nuclear power plant. The confidence regions in the parameter space have been analyzed by investigating the geometry of the estimation error function.

The developed model can serve as a basis for controlling the optimal energy production of the generator using both the active and reactive power components.

BibTeX:
@article{Fodor2012,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {Control-oriented modeling of the energy-production of a synchronous generator in a nuclear power plant},
  journal = {Energy},
  publisher = {Elsevier},
  year = {2012},
  volume = {39},
  number = {1},
  pages = {135--145},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/qinCetJxFSxfbGj/download},
  doi = {10.1016/j.energy.2012.01.054}
}
Fodor A, Magyar A and Hangos KM (2012), "MIMO LQ control of the energy production of a synchronous generator in a nuclear power plant", Chem. Eng. Trans. Vol. 29, pp. 361-366.
Abstract: A multiple-input multiple-output (MIMO) LQ servo controller was proposed for an industrial size synchronous generator that keeps the active power at the desired level and performs reactive power reference tracking using the reactive power demand from the central dispatch center. The controller design was based on the locally linearized version of a previous dynamical model of the synchronous electrical generator (Anderson and Fouad, 1977, Fodor et al., 2012) the parameters of which have been identified using measured data from Paks Nuclear Power Plant, Hungary.
BibTeX:
@article{Fodor2012a,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {MIMO LQ control of the energy production of a synchronous generator in a nuclear power plant},
  journal = {Chem. Eng. Trans},
  year = {2012},
  volume = {29},
  pages = {361--366},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/4TEkoY3G9AtpYWt},
  doi = {10.3303/CET1229061}
}
Göllei A, Görbe P and Magyar A (2012), "Modeling and optimization of electrical vehicle batteries in complex clean energy systems", Journal of Cleaner Production., IF: 3.398, 2012. Vol. 34, pp. 138-145. Elsevier.
Abstract: The paper presents a general temperature-dependent model for a family of batteries developed for electrical vehicle (EV) use. In addition to the model’s derivation, the methodology and instruments developed to accurately measure the temperature-dependent parameters are also presented together with a Matlab/Simulink block for a temperature-dependent battery. This information is very important for simulating the behavior of an EV in real-life weather and temperature conditions and for simulating the quick charging process, which are key issues for spreading EVs. The battery model has been verified in a complex energetic structure consisting of a harmonic controller that minimizes the amplitudes of the 3rd, 5th, 7th, 9th, and 11th higher order components of the output voltage and that of the connection voltage controller, which controls the energy flow between the low voltage network and the renewable energy source, thereby reducing the power loss of the whole low voltage transformer area and reducing the CO2 emission of the average household.
BibTeX:
@article{Goellei2012,
  author = {Göllei, Attila and Görbe, P and Magyar, Attila},
  title = {Modeling and optimization of electrical vehicle batteries in complex clean energy systems},
  journal = {Journal of Cleaner Production},
  publisher = {Elsevier},
  year = {2012},
  volume = {34},
  pages = {138--145},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/LYfRDrP7ga2SnZT/download},
  doi = {10.1016/j.jclepro.2011.12.013}
}
Görbe P, Magyar A and Hangos KM (2012), "Reduction of power losses with smart grids fueled with renewable sources and applying EV batteries", Journal of Cleaner Production., IF: 3.398, 2012. Vol. 34, pp. 125-137. Elsevier.
Abstract: This paper describes a low-voltage grid composed of small, domestic power plants fueled by clean and renewable energy sources and augmented with electric vehicle batteries as power storage devices. We propose that this grid could utilize a complex multifunctional control unit capable of optimizing the working point and charging current of the system, while also implementing active power factor correction, lowering extant harmonic distortion and controlling the voltage level in the low-voltage power lines. The complex controller structure proposed in this paper contains the following novel components: an upper harmonic controller which (together with the connection voltage controller) minimizes the amplitudes of the 3rd, 5th, 7th, 9th, and 11th high order components in the output voltage; and a connection voltage controller which controls the energy flow between the low-voltage network, its renewable energy sources and the electrical vehicle batteries. Unlike other similar approaches, the harmonic controller proposed in this paper does not rely on a measured current signal but rather optimizes the voltage shape, the latter of which depends on the nonlinear distortion of the whole low-voltage transformer area and determines additional power losses. We analyzed the proposed controller via simulations in a Matlab environment and as a result, achieved substantial improvements to the output voltage, current waveform and energy flow of the system’s low-voltage conditions. Our calculations show that the implementation of substantial reductions in CO2 emissions could be achieved for an average household. The robustness of the method against nonlinear loads and fluctuations in overloads and overproductions was also tested.
BibTeX:
@article{Goerbe2012,
  author = {Görbe, P and Magyar, Attila and Hangos, Katalin M},
  title = {Reduction of power losses with smart grids fueled with renewable sources and applying EV batteries},
  journal = {Journal of Cleaner Production},
  publisher = {Elsevier},
  year = {2012},
  volume = {34},
  pages = {125--137},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/Pz72QTdedSXN8kX/download},
  doi = {10.1016/j.jclepro.2011.12.021}
}
Göllei A (2011), "Veszteséges közeggel töltött mikrohullámú tápvonalak energetikai és hőmérsékleti viszonyainak vizsgálata és gyakorlati alkalmazásai". Thesis at: Ph. D. Thesis, University of Pannonia,.
Abstract: This dissertation investigate theoretical and practial procedures to develop a model for simulating microwave transmission lines and determining the dielectric properties of different materials. Special emphasis is placed on ionic liquids and the development of an energy efficient drying procedure for agricultural seeds. A closed model was developed to calculate different temperature dependent energy, impedance and dielecric parameters in microwave waveguide filled with lossy materials. This model was verified by three different sample materials. A computer controlled dielectrometer unit was designed and developed. The unit is suitable for measuring the temperature dependent dielectric properties of solid and liquid materials within a wide range. Moreover, this equipment is suitable for measuring well conductive liquid materials such as ionic liquids that are important novel environmently friendly solvents. One of the main industrial applications of microwave energy is the dielectric drying of agricultural seeds. Before starting a drying procedure, it is very important to know the dielectric parameters of the materials which are to be treated. The parameters of combined drying influences end product quality. The combined drying procedure (convective and microwave process) is very energy efficient. A novel procedure to determine the degree of efficiency of the drying procedure is developed. Finally, the thesis presents the measurement results demonstrating the lower energy consumption of the developed drying procedure.
BibTeX:
@phdthesis{Goellei2011,
  author = {Göllei, Attila},
  title = {Veszteséges közeggel töltött mikrohullámú tápvonalak energetikai és hőmérsékleti viszonyainak vizsgálata és gyakorlati alkalmazásai},
  school = {Ph. D. Thesis, University of Pannonia,},
  year = {2011},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/pKxAEQKmaaj9MRC/download}
}
Görbe P, Magyar A and Hangos KM (2011), "Low voltage grid optimization with power injection of renewable sources and EV batteries", Chemical Engineering Transactions. Vol. 25, pp. 893-898.
Abstract: The increase of renewable power sources in today’s energy production systems results in high non-deterministic fluctuations in energy distribution network. At the same time, the use of nonlinear switching power supplies is more and more widespread nowadays, that creates serious nonlinear distortion in the line. In addition, the insufficient energy storage capacity commonly available in public energy distribution networks makes it very difficult to operate it an efficient and balanced way. Therefore, a novel control method for combining small domestic power plants using renewable energy and electric vehicle battery chargers where the battery can be used as temporal energy storage is proposed in this paper. The method is not only capable of optimizing the working point of the plant, but also implements active power factor (PF) correction and lowers the extant harmonic distortion in the line. In addition, the proposed control method allows one to create systems that can absorb the peaks of power production, or can feed power back into the grid in fluctuating energy production. The novel element is the voltage level controller which independently optimizes the effective value of the voltage at the connection point. This controls the energy flow direction between the grid, the renewable power source and the EV batteries. The system is able to communicate with an external controller through a Smart Grid Interface to be an element of a larger grid control scheme as an executer part. The proposed controller has been verified by simulation in Matlab environment, and as a result, substantial improvement of the output voltage and current effective value and waveform could be achieved. Robustness of the method against nonlinear loads has also been tested.
BibTeX:
@article{Goerbe2011,
  author = {Görbe, P and Magyar, Attila and Hangos, Katalin M},
  title = {Low voltage grid optimization with power injection of renewable sources and EV batteries},
  journal = {Chemical Engineering Transactions},
  year = {2011},
  volume = {25},
  pages = {893--898},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/CLTMr2erqkZTRdo/download},
  doi = {10.3303/CET1125149}
}
Hatos P, Fodor A and Magyar A (2011), "Parameter sensitivity analysis of an induction motor", Hungarian Journal of Industry and Chemistry. Vol. 39(1), pp. 157-161. De Gruyter Open.
Abstract: A simple dynamic model of an induction motor is presented in this paper based on engineering principles that describe the mechanical phenomena together with the electrical model. The investigated state space model consists of nonlinear state equations and linear output equations. The model has been verified under the usual controlled operating conditions when the speed is controlled. The effect of load on the controlled induction motor has been analyzed by simulation. The sensitivity analysis of the induction motor and the bridge of the inverter have been applied to determine the model parameters to be estimated.
BibTeX:
@article{Hatos2011,
  author = {Hatos, P and Fodor, A and Magyar, A},
  title = {Parameter sensitivity analysis of an induction motor},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2011},
  volume = {39},
  number = {1},
  pages = {157--161},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/MnKbiRJNyYGR9XZ/download}
}
Cserjési P, Göllei A, Bélafi-Bakó K and Gubicza L (2011), "Dielectric properties of ionic liquids proposed to be used in batteries", In Ionic Liquids-Classes and Properties. InTech.
Abstract: Ionic liquids (ILs) opened new technological possibilities (Marsh, 2004) at the end of the 1990s for many application fields (Mutelet & Jaubert, 2006) due to their special physical and chemical properties (Welton, 1999). They have several advantages compared to commercial organic solvents (Mutelet & Jaubert, 2006), or electrolyte liquids (Plechkova & Seddon, 2008) since they are liquid over a wide temperature range, easy to recycle, noncombustible (Matsumoto, 2005), non-flammable (Saruwatari, 2010), display wide electrochemical windows (Giroud, 2008), high inherent conductivities (Stracke, 2009), have negligible vapor pressure (Endres, 2008), high thermal (Wasserschied & Welton, 2007) and electrochemical stability (Arnold, 2004), tuneable physicochemical properties (Koel, 2008) and lack of reactivity in various electrochemical or industrial applications (Seddon, 2003). Therefore ILs have been intensively studied recently as novel, much safer electrolyte materials (Sakaebe, 2007) for electrochemical devices (Ohno 2005) and energy storing devices, such as Li batteries for cellular phones (Xu, 2006), batteries for vehicles, fuel cells, supercapacitors (Sato, 2004), solar cells (Stathatos, 2005.), etc. In order to decide whether an IL could be successfully used as electrolyte it is necessary to first gain enough information about the electrochemical properties, hence the dielectric behaviour of the selected liquid. However, several methods have already been published about determination of the dielectric properties of ILs – generally characterized by the dielectric constant (Wakai, 2005) and by the dielectric loss factor (Bright & Baker, 2006; Wakai, 2006), so far no measuring method was introduced. This can be explained by the fact that the dielectric properties of ionic liquids cannot be measured by classical methods due to their high conductivity (Krossing, 2006). In this chapter we intend to describe a novel method and a self-designed microwave dielectrometric apparatus built to measure the (e’) and (e”) values and the electrical conductivity (G) of several ionic liquids, which might be used as electrolyte in batteries, at 2.45 GHz and at different temperatures. Furthermore the connections between the structure of the investigated ionic liquids and the dielectric characteristics will be determined.
BibTeX:
@incollection{Petra2011,
  author = {Cserjési, Petra and Göllei, A and Bélafi-Bakó, K and Gubicza, L},
  title = {Dielectric properties of ionic liquids proposed to be used in batteries},
  booktitle = {Ionic Liquids-Classes and Properties},
  publisher = {InTech},
  year = {2011},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/tFDPpcYJcJKZkkY/download},
  doi = {10.5772/23428}
}
Balló G and Hangos KM (2010), "Parameter estimation of quantum processes using convex optimization", arXiv preprint arXiv:1004.5209.
Abstract: A convex optimization based method is proposed for quantum process tomography, in the case of known channel model structure, but unknown channel parameters. The main idea is to select an affine parametrization of the Choi matrix as a set of optimization variables, and formulate a semidefinite programming problem with a least squares objective function. Possible convex relations between the optimization variables are also taken into account to improve the estimation. Simulation case studies show, that the proposed method can significantly increase the accuracy of the parameter estimation, if the channel model structure is known. Beside the convex part, the determination of the channel parameters from the optimization variables is a nonconvex step in general. In the case of Pauli channels however, the method reduces to a purely convex optimization problem, allowing to obtain a globally optimal solution.
BibTeX:
@article{Ballo2010,
  author = {Balló, G and Hangos, Katalin M},
  title = {Parameter estimation of quantum processes using convex optimization},
  journal = {arXiv preprint arXiv:1004.5209},
  year = {2010},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/zz53HCcKiCW8cnY/download}
}
Fodor A, Magyar A and Hangos K (2010), "Parameter sensitivity analysis of an industrial synchronous generator", In 11th International PhD Workshop on Systems and Control, Hluboka nad Vltavou, Czech Republic, ISBN. , pp. 978-615.
Abstract: Abstract— A previously developed simple dynamic model of an industrial size synchronous generator operating in a nuclear power plant is analyzed in this paper. The constructed state-space model consists of a nonlinear state equation and a bi-linear output equation. It has been shown that the model is locally asymptotically stable with parameters obtained from the literature for a similar generator.
The effect of load disturbances on the partially controlled generator has been analyzed by simulation using a PI controller. It has been found that the controlled system is stable and can follow the set-point changes in the effective power well. The sensitivity of the model for its parameters has also been investigated and parameter groups have been defined according to the system’s degree of sensitivity to them. This groups form the different candidates of parameters for a subsequent parameter estimation.
BibTeX:
@inproceedings{Fodor2010,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin},
  title = {Parameter sensitivity analysis of an industrial synchronous generator},
  booktitle = {11th International PhD Workshop on Systems and Control, Hluboka nad Vltavou, Czech Republic, ISBN},
  year = {2010},
  pages = {978--615},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/y2y2tYGEowsX6W7/download}
}
Fodor A, Magyar A and Hangos KM (2010), "Parameter sensitivity analysis of a synchronous generator", Hungarian Journal of Industry and Chemistry. Vol. 38(1) De Gruyter Open.
Abstract: A previously developed simple dynamic model of an industrial size synchronous generator is analyzed in this paper. The constructed state-space model consists of a nonlinear state equation and a bilinear output equation. It has been shown that the model is locally asymptotically stable with parameters obtained from the literature for a similar generator. The effect of load disturbances on the partially controlled generator has been analyzed by simulation using a PI controller. It has been found that the controlled system is stable and can follow the set-point changes in the effective power well. The sensitivity of the model for its parameters has also been investigated and parameter groups have been identified according to the system’s degree of sensitivity to them. This groups form the different candidates of parameters for subsequent parameter estimation. The ways of applying the developed methods to other generators used in the automotive industry are also outlined.
BibTeX:
@article{Fodor2010a,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {Parameter sensitivity analysis of a synchronous generator},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2010},
  volume = {38},
  number = {1},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/yC5JQT5Q6m2qgHd/download}
}
Fodor A, Magyar A and Hangos KM (2010), "Dynamic modeling and model analysis of a large industrial synchronous generator", In Applied Electronics (AE), 2010 International Conference on. , pp. 1-6.
Abstract: A simple dynamic model of an industrial size synchronous generator operating in a nuclear power plant is developed in this paper based on first engineering principles. The constructed state-space model consists of a nonlinear state equation and a bi-linear output equation. It has been shown that the model is locally asymptotically stable with parameters obtained from the literature for a similar generator. The effect of load disturbances on the partially controlled generator has been analyzed by simulation using a traditional PI controller. It has been found that the controlled system is stable and can follow the set-point changes in the effective power well. The disturbance rejection of the controller is also satisfactory.
BibTeX:
@inproceedings{Fodor2010b,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {Dynamic modeling and model analysis of a large industrial synchronous generator},
  booktitle = {Applied Electronics (AE), 2010 International Conference on},
  year = {2010},
  pages = {1--6},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/poN8fgtST3imTiH/download}
}
Görbe P, Magyar A and Hangos KM (2010), "Power conditioning with electric car battery charging from renewable sources", Hungarian Journal of Industry and Chemistry. Vol. 38(1) De Gruyter Open.
Abstract: A control method for electric car battery charging combined with small domestic power plants using renewable energy is described in this paper. This method is not only capable of optimizing the working point and charging current of the system but also implements robust energy flow control to balance the convenient process variables.The proposed controller has been investigated by simulation in Matlab environment, and as a result, succesful combination of a grid synchronised inverter and a electric car battery charger robust operation could be achieved in changing operational modes.
BibTeX:
@article{Goerbe2010,
  author = {Görbe, P and Magyar, Attila and Hangos, Katalin M},
  title = {Power conditioning with electric car battery charging from renewable sources},
  journal = {Hungarian Journal of Industry and Chemistry},
  publisher = {De Gruyter Open},
  year = {2010},
  volume = {38},
  number = {1},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/fMf6TNN355YD7xe/download}
}
Görbe P, Magyar A and Hangos KM (2010), "THD reduction with grid synchronized inverter’s power injection of renewable sources", In Power Electronics Electrical Drives Automation and Motion (SPEEDAM), 2010 International Symposium on. , pp. 1381-1386.
Abstract: A control method for small domestic power plants using renewable energy is described in this paper. This method is not only capable of optimizing the working point of the plant but also implements active power factor correction and lowers the extant harmonic distortion in the line. The novel element in the proposed complex controller structure is the upper harmonic controller that minimizes the amplitudes of the 3rd, 5th 7th, 9th, and the 11th upper harmonic component in the output voltage. The proposed controller has been investigated by simulation in Matlab environment, and as a result, substantial improvement of the output voltage and current waveform could be achieved. Robustness of the method against nonlinear loads has also been tested.
BibTeX:
@inproceedings{Goerbe2010a,
  author = {Görbe, P and Magyar, Attila and Hangos, Katalin M},
  title = {THD reduction with grid synchronized inverter’s power injection of renewable sources},
  booktitle = {Power Electronics Electrical Drives Automation and Motion (SPEEDAM), 2010 International Symposium on},
  year = {2010},
  pages = {1381--1386},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/RpCPPKT3MFXCmp6/download},
  doi = {10.1109/SPEEDAM.2010.5545079}
}
Gollei A, Magyar A and Gerzson M (2010), "Investigating energetic and impedance relations of microwave transmission line filled with dielectric material", PIERS Online. Vol. 6(5), pp. 420-424. PIERS Online.
Abstract: During microwave treatment, microwave energy is transferred to a material sample placed in an applicator of given geometric parameters. As a result of the energy transfer, the sample absorbs energy from the microwave field depending on its dielectric properties. The degree of energy absorption is directly proportional to the dielectric loss and proportional to the square root of the dielectric constant. The temperature of the sample continuously increases due to the energy transfer and the dielectric properties of the sample also change with the rising temperature. Although the microwave energy supply is constant, time and temperature dependent energy impedance and dielectric relations are developed. A part of them is measurable, but the other part of them can not be directly measured, they can only be computed from the previously measured ones. In a closed model which contains the parameters of the sample and the waveguide, the continuously changing parameters can be determined in relation of the temperature. These parameters are as follows: Attenuation of the transmission line, temporal change of the sample temperature, dielectric properties of the sample, loss factor of the sample, penetration depth, impedance of the transmission line, standing wave ratio reflection factor. The above parameters can be modeled as a function of the sample’s temperature or as a function of time.
BibTeX:
@article{Gollei2010,
  author = {Gollei, Attila and Magyar, Andras and Gerzson, M},
  title = {Investigating energetic and impedance relations of microwave transmission line filled with dielectric material},
  journal = {PIERS Online},
  publisher = {PIERS Online},
  year = {2010},
  volume = {6},
  number = {5},
  pages = {420--424},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/K8AgBdGgaj7scww/download},
  doi = {10.2529/PIERS091216050152}
}
Fodor A, Magyar A and Hangos KM (2009), "Dynamic modeling and analysis of a synchronous generator in a nuclear power plant", In 10th International PhD Workshop on Systems and Control, Hluboka nad Vltavou, Czech Republic,. , pp. 978-80.
Abstract: A simple dynamic model of an industrial size synchronous generator operating in a nuclear power plant is developed in this paper based on first engineering principles. The constructed state-space model consists of an LTI state equation and a bi-linear output equation. It has been shown that the model is asymptotically stable with parameters obtained from the literature for a similar generator but it is very close to the stability boundary.
The effect of load disturbances on the partially controlled generator has been analyzed by simulation using a traditional PI controller. It has been found that the controlled system is stable and can follow the set-point changes in the effective power well. The disturbance rejection of the controller is also satisfactory.
BibTeX:
@inproceedings{Fodor2009,
  author = {Fodor, Attila and Magyar, Attila and Hangos, Katalin M},
  title = {Dynamic modeling and analysis of a synchronous generator in a nuclear power plant},
  booktitle = {10th International PhD Workshop on Systems and Control, Hluboka nad Vltavou, Czech Republic,},
  year = {2009},
  pages = {978--80},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/WpFmRG39EJAeZ5K/download}
}
Göllei A, Vass A, Magyar A and Pallai E (2009), "Apparatus and method for investigation of energy consumption of microwave assisted drying systems", Review of Scientific Instruments., IF: 1.521, 2009. Vol. 80(10), pp. 104706. AIP.
Abstract: Convective, hot air drying by itself is relatively efficient for removing water from the surface environment of agricultural seed products. However, moving internal moisture to the surface needs rather a long time, as a rule. The major research aim of the authors was to decrease the processing time and processing costs, to improve the quality of the dried product, and to increase drying efficiency. For this reason their research activities focused on the development of a special drying apparatus and a method suitable for measuring of energy conditions in a hybrid (microwave and convective) dryer. Experimental investigations were made with moistened wheat as model material. Experiments were carried out in microwave, convective and hybrid drying systems. The microwave drying alone was more efficient than the convective method. The lowest energy consumption and shortest drying time were obtained by the use of a hybrid method in which the waste energy of magnetron was utilized and the temperature was controlled. In this way, it was possible to keep the temperature of the dried product at a constant and safe value and to considerably decrease the energy consumption.
BibTeX:
@article{Goellei2009,
  author = {Göllei, Attila and Vass, A and Magyar, Attila and Pallai, Elisabeth},
  title = {Apparatus and method for investigation of energy consumption of microwave assisted drying systems},
  journal = {Review of Scientific Instruments},
  publisher = {AIP},
  year = {2009},
  volume = {80},
  number = {10},
  pages = {104706},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/DEFYkJtxmyjKKkF/download},
  doi = {10.1063/1.3250870}
}
Görbe P, Magyar A and Hangos KM (2009), "Line conditioning with grid synchronized inverter's power injection of renewable sources in nonlinear distorted mains", In Proc. 10th International PhD Workshop on Systems and Control. , pp. 978-980.
BibTeX:
@inproceedings{Goerbe2009,
  author = {Görbe, P and Magyar, Attila and Hangos, Katalin M},
  title = {Line conditioning with grid synchronized inverter's power injection of renewable sources in nonlinear distorted mains},
  booktitle = {Proc. 10th International PhD Workshop on Systems and Control},
  year = {2009},
  pages = {978--980},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/y3gPcwWXxEMXdwx/download}
}
Magyar A, Szederkényi G and Hangos KM (2008), "Globally stabilizing feedback control of process systems in generalized Lotka--Volterra form", Journal of Process control., IF: 1.606, 2008. Vol. 18(1), pp. 80-91. Elsevier.
Abstract: In the present paper a globally stabilizing feedback controller design method is proposed for process systems when the feedback structure is also assumed to be in a quasi-polynomial form. It is shown that such feedback structure can always be achieved for process systems.

By exploiting the special structure of the controller design problem, the existent iterative linear matrix inequality (ILMI) algorithm of [Y.-Y. Cao, J. Lam, Y.-X. Sun, Static output feedback stabilization: an ILMI approach, Automatica 12 (1998) 1641–1645] is applied to solve the BMI feasibility problem underlying the design.

In addition, some partial results on placing the globally stable equilibrium point with respect to the positive orthant have also been proposed that is only possible in a fully actuated situation when the input variables are the intensive variables at the inlet. Furthermore, some preliminary results in selecting the structure of the QP-type feedback have also been presented.

BibTeX:
@article{Magyar2008,
  author = {Magyar, Attila and Szederkényi, G and Hangos, K M},
  title = {Globally stabilizing feedback control of process systems in generalized Lotka--Volterra form},
  journal = {Journal of Process control},
  publisher = {Elsevier},
  year = {2008},
  volume = {18},
  number = {1},
  pages = {80--91},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/MegCEdaNim9JHt3/download},
  doi = {10.1016/j.jprocont.2007.05.003}
}
Ruppert L, Magyar A and Hangos K (2008), "Compromising non-demolition and information gaining for qubit state estimation", In Quantum Probability and Related Topics. , pp. 212-224. World Scientific.
Abstract: An indirect measurement scheme is used in this paper, which allows us to to optimally select the elements of the measurement protocol according to a pre-defined weighting between the variance of the estimated state parameters and the ratio of the non-demolished copies of the system.
BibTeX:
@incollection{Ruppert2008,
  author = {Ruppert, L and Magyar, Attila and Hangos, KM},
  title = {Compromising non-demolition and information gaining for qubit state estimation},
  booktitle = {Quantum Probability and Related Topics},
  publisher = {World Scientific},
  year = {2008},
  pages = {212--224},
  doi = {10.1142/9789812835277_0017}
}
Ruppert L, Magyar A, Hangos K and Petz D (2008), "Towards optimal quantum state estimation of a qubit by using indirect measurements", Research Report of the Systems and Control Laboratory SCL-002/2008.. , pp. 24. MTA SZTAKI.
Abstract: The properties of the indirect measurement scheme is investigated in this report in the discrete time case. The simplest possible case is considered, where both the unknown and the measurement quantum systems are quantum bits. The measurements applied on the measurement qubit are the classical von Neumann measurements using the Pauli matrices as observables. The statistical properties of the estimate in terms of the variance of the ML estimator and the non-demolition probability are analytically calculated in a simple case when the measurements are applied in the x direction while the qubits interact in the y direction and the initial state of the measurement qubit is [0, 0, c]. A way of finding an optimal compromising measurement strategy between the asymptotic variance and the non-demolition probability is also proposed. The efficiency of the results have been compared with a classical ’standard’ state estimation procedure available in the literature. Although the classical one performs better by means of the variance, the indirect one gives a degree of freedom in the above mentioned trade-off problem. The estimation method has also been modified in a few ways to improve its
precision.
BibTeX:
@article{Ruppert2008a,
  author = {Ruppert, L and Magyar, Attila and Hangos, KM and Petz, D},
  title = {Towards optimal quantum state estimation of a qubit by using indirect measurements},
  journal = {Research Report of the Systems and Control Laboratory SCL-002/2008.},
  publisher = {MTA SZTAKI},
  year = {2008},
  pages = {24},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/nYoC8Y5F4TmNjSp/download}
}
Baier T, Petz D, Hangos KM and Magyar A (2007), "Comparison of some methods of quantum state estimation", In Quantum probability and infinite dimensional analysis. , pp. 64-78. World Scientific.
Abstract: 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.
BibTeX:
@incollection{Baier2007,
  author = {Baier, Th and Petz, D and Hangos, K M and Magyar, Attila},
  title = {Comparison of some methods of quantum state estimation},
  booktitle = {Quantum probability and infinite dimensional analysis},
  publisher = {World Scientific},
  year = {2007},
  pages = {64--78},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/HspPtgrPEgo6xmE/download},
  doi = {10.1142/9789812770271_0007}
}
Magyar A (2007), "State estimation and state feedback control in quasi-polynomial and quantum mechanical systems". Thesis at: Ph. D. Thesis, University of Pannonia, Systems and Control Laboratory.
Abstract: The goal of this dissertation is to apply system and control theory to two system classes originating from different fields of physics: process systems and quantum mechanical systems. Using the quasi-polynomial system representation it is possible to describe the dynamic behavior of general nonlinear process systems. It is shown in the work, that global stability analysis for such systems can be performed algorithmically, moreover, a globally stabilizing state feedback design method is given. Only a few authors tried to apply control theory in quantum mechanical fields. The aimed problem of the second part of the dissertation is quantum state estimation, where the state of a quantum system is to be determined from quantum measurement. The problem is solved in two different ways.
BibTeX:
@phdthesis{Magyar2007,
  author = {Magyar, Attila},
  title = {State estimation and state feedback control in quasi-polynomial and quantum mechanical systems},
  school = {Ph. D. Thesis, University of Pannonia, Systems and Control Laboratory},
  year = {2007},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/f8AgCssz89C6PdE/download}
}
Magyar A and Hangos K (2007), "Dynamics of quantum mechanical systems under weak measurement" MTA SZTAKI.
Abstract: The paper deals with the so-called weak measurement of quantum mechanical systems. As opposed to the classical (i.e. von Neumann) quantum measurement, in the weak measurement scheme a measuring quantum system is attached to the system of interest, and the von Neumann measurement is performed on the measurement system. This way, the state of the system of interest does not suffer a complete demolition as in the classical case, however, in the other hand, the possible information obtainable from the measurement is probably less. In quantum information theory, the widely used method for quantum state estimation is performed using several identical copies of the qubit (quantum bit) of interest. After applying a von Neumann measurement on the copies, they are useless. It would be interesting and useful, if the state od the system after a weak measurement could be used for further measurements, so the number of qubits used for state estimation could be decreased. To be able to do this, first of all the dynamical change of the system under the weak measurement scheme must be investigated.
BibTeX:
@article{Magyar2007a,
  author = {Magyar, Attila and Hangos, Katalin},
  title = {Dynamics of quantum mechanical systems under weak measurement},
  publisher = {MTA SZTAKI},
  year = {2007}
}
Magyar A, Szederkényi G and Hangos K (2007), "Control of mass action law based reaction networks" Slovak Univ. of Technology in Bratislava.
Abstract: The present paper addresses the controller structure selection and controller design for reaction networks given by their mass action law (MAL) description. Using this special form enables us to apply the results of classical reaction kinetics together with the tools of nonlinear control theory. It is shown that there exists a reaction network type feedback to a physically meaningfully opened system such, that the closed loop system is again in the class of MAL reaction networks. The manipulable inputs are then either the inlet concentrations or the inlet component mass flow rates. Moreover, it is possible to reach the very strong property of having zero deficiency with the proposed feedback structure. In the case of reversible reaction systems it implies the existence of a unique positive globally asymptotically stable equilibrium point. The problem and the method are demonstrated on a so called Michaelis Menten kinetics with substrate inhibition described by the mass action law mechanism.
BibTeX:
@article{Magyar2007b,
  author = {Magyar, Attila and Szederkényi, G and Hangos, Katalin},
  title = {Control of mass action law based reaction networks},
  publisher = {Slovak Univ. of Technology in Bratislava},
  year = {2007},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/g2mDZH9eZ6XNfQp/download}
}
Petz D, Hangos K and Magyar A (2007), "Point estimation of states of finite quantum systems", Journal of Physics A: Mathematical and Theoretical., IF: 1.680, 2007. Vol. 40(28), pp. 7955. IOP Publishing.
Abstract: The estimation of the density matrix of a k-level quantum system is studied when the parametrization is given by the real and imaginary part of the entries, and they are estimated by independent measurements. It is established that the properties of the estimation procedure depend very much on the invertibility of the true state. In particular, in the case of a pure state, the estimation should be constrained to ensure the positive definiteness of the estimate. An efficient constraining algorithm is proposed and it yields an asymptotically unbiased estimate. Moreover, several estimation schemes are compared for the unknown state of a qubit when one copy is measured at a time. It is shown that the average mean quadratic error matrix is the smallest if the applied observables are complementary. All the results are illustrated by computer simulations.
BibTeX:
@article{Petz2007,
  author = {Petz, D and Hangos, KM and Magyar, Attila},
  title = {Point estimation of states of finite quantum systems},
  journal = {Journal of Physics A: Mathematical and Theoretical},
  publisher = {IOP Publishing},
  year = {2007},
  volume = {40},
  number = {28},
  pages = {7955},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/oeYtppm5JbXXNFi/download},
  doi = {10.1088/1751-8113/40/28/S06}
}
Ruppert L and Magyar A (2006), "The effect of constraints on LS state estimators for a qubit" Akademie ved Ceské Republiky Ústav teorie informace a automatizace.
Abstract: The LS state estimation method has been chosen in this paper since constraints on the estimated states can easily be handled with it. The resulting convex constrained optimization problem can be solved by various available solvers. On the other hand, the simplicity of the estimator makes it a promising candidate to be generalized for two, or more qubits in the future. The effect of the constraint on the statistical properties of the state estimator is investigated here in the simplest case of a quantum bit (qubit) by analyzing the properties of an unconstrained- and a constrained LS estimator.
BibTeX:
@article{Ruppert2006,
  author = {Ruppert, L and Magyar, Attila},
  title = {The effect of constraints on LS state estimators for a qubit},
  publisher = {Akademie ved Ceské Republiky Ústav teorie informace a automatizace},
  year = {2006},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/LqsEjCMKcbNmwCs/download}
}
Szederkényi G, Magyar A and Hangos K (2006), "Quasi-polynomial and Lotka-Volterra representation in nonlinear systems and control theory", In Proceedings of the Workshop on System Identification and Control Systems, Advanced Vehicles and Vehicle Control Knowledge Center of BME, Budapest, Hungary. , pp. 147-163.
Abstract: Nonlinear input-affine systems in quasi-polynomial (QP) and Lotka-Volterra (LV) forms are investigated in this paper. It is shown that both the global stability analysis with an entropy-like Lyapunov function candidate and the local quadratic stability region determination can be performed by solving lin- ear matrix inequalities (LMIs). The invariance transformations preserving the form of the description are also described and their use for stability analysis is discussed. It is also shown that zero dynamics analysis can be performed by solving LMIs but the design of globally stabilizing feedback controllers leads to a bilinear matrix inequality (BMI) problem.
BibTeX:
@inproceedings{Szederkenyi2006,
  author = {Szederkényi, G and Magyar, Attila and Hangos, KM},
  title = {Quasi-polynomial and Lotka-Volterra representation in nonlinear systems and control theory},
  booktitle = {Proceedings of the Workshop on System Identification and Control Systems, Advanced Vehicles and Vehicle Control Knowledge Center of BME, Budapest, Hungary},
  year = {2006},
  pages = {147--163},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/XzrRqBQgYPbiQJi/download}
}
Magyar A, Szederkényi G and Hangos K (2005), "Quasi-polynomial system representation for the analysis and control of nonlinear systems", In Proceedings of the 16th IFAC World Congress. , pp. 1-6.
Abstract: The application of quasi-polynomial system representation for the analysis and control of a wide class of smooth nonlinear systems is proposed in this paper. The analysis part includes the global stability analysis of the open loop system and that of the zero dynamics. It is shown that the stabilizing controller design with monomial feedback structure leads to the feasibility of bilinear matrix inequalities. The methods are illustrated on simple examples.
BibTeX:
@inproceedings{Magyar2005,
  author = {Magyar, Attila and Szederkényi, G and Hangos, KM},
  title = {Quasi-polynomial system representation for the analysis and control of nonlinear systems},
  booktitle = {Proceedings of the 16th IFAC World Congress},
  year = {2005},
  pages = {1--6},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/XzrRqBQgYPbiQJi/download}
}
Szederkényi G, Hangos KM and Magyar A (2005), "On the time-reparametrization of quasi-polynomial systems", Physics Letters A., IF: 1.550, 2005. Vol. 334(4), pp. 288-294. Elsevier.
Abstract: In this Letter we show that an important type of time-reparametrization problem in quasi-polynomial systems is equivalent to the feasibility of a suitably constructed bilinear matrix inequality where the unknowns are the coefficients of the Lyapunov function and the exponents in the time-reparametrization transformation.
BibTeX:
@article{Szederkenyi2005,
  author = {Szederkényi, G and Hangos, Katalin M and Magyar, Attila},
  title = {On the time-reparametrization of quasi-polynomial systems},
  journal = {Physics Letters A},
  publisher = {Elsevier},
  year = {2005},
  volume = {334},
  number = {4},
  pages = {288--294},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/RzoR64gfCWweqLt/download},
  doi = {10.1016/j.physleta.2004.11.026}
}
Magyar A, Szederkényi G and Hangos K (2004), "Quadratic stability of process systems in generalized Lotka-Volterra form", IFAC Proceedings Volumes. Vol. 37(13), pp. 1217-1222. Elsevier.
Abstract: The global and local stability of process systems in generalized Lotka-Volterra form is studied in this paper using entropy-like and quadratic Lyapunov function candidates. The global stability check for LV models is performed by solving an LMI for a diagonal positive semi-definite matrix using singular perturbation technique. It is shown that a quadratic Lyapunov function can also be determined by solving linear matrix inequalities (LMIs). In addition, the quadratic stability neighborhood is convex in the space of the quasi-monomials and can be estimated by computing its corner points using LMIs. Furthermore, it is proved that quadratic stability with a diagonal weighting matrix enables to construct a dissipative-Hamiltonian description of the system. The developed methods are illustrated on the model of a continuously stirred tank reactor with a nonlinear reaction system.
BibTeX:
@article{Magyar2004,
  author = {Magyar, A and Szederkényi, G and Hangos, KM},
  title = {Quadratic stability of process systems in generalized Lotka-Volterra form},
  journal = {IFAC Proceedings Volumes},
  publisher = {Elsevier},
  year = {2004},
  volume = {37},
  number = {13},
  pages = {1217--1222},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/koyLkirKGp4C9is/download},
  doi = {10.1016/S1474-6670(17)31393-9}
}
Magyar A and Hangos K (2003), "Lotka-Volterra representation of process systems for stability analysis", Process Control. Vol. 3
BibTeX:
@article{Magyar2003,
  author = {Magyar, A and Hangos, KM},
  title = {Lotka-Volterra representation of process systems for stability analysis},
  journal = {Process Control},
  year = {2003},
  volume = {3},
  url = {https://ecloud.virt.uni-pannon.hu/index.php/s/knLtbt69S5YyEjk/download}
}
Created by JabRef on 03/10/2019.