Papers by Friedrich von Haeseler
Chapter 3. Automaticity
De Gruyter eBooks, Nov 20, 2002
Chapter 5. Algebraic properties
De Gruyter eBooks, Nov 20, 2002
Chapter 4. Automaticity II
De Gruyter eBooks, Jan 20, 2002
Chapter 1. Preliminaries
De Gruyter eBooks, Jan 20, 2002
Chapter 5. Algebraic properties
Chapter 2. Expanding endomorphisms and substitutions
Automatic Sequences, 2002
IFAC-PapersOnLine, 2015
Enhanced conductivity method is adopted to incorporate PCM convective effect into 1-D thermal res... more Enhanced conductivity method is adopted to incorporate PCM convective effect into 1-D thermal resistance model. • An improved thermal resistance model, offering a good compromise between accuracy and simplicity, is developed. • Neglecting PCM convective effect or radiative heat transfer in numerical simulation may result in significant errors. • A sensitivity analysis suggests that the optimal PCM melting temperature is about 5 °C higher than ambient.
Mathematical 3D modelling and sensitivity analysis of multipolar radiofrequency ablation in the spine
Mathematical biosciences, Feb 1, 2017
Radiofrequency ablation is a valuable tool in the treatment of many diseases, especially cancer. ... more Radiofrequency ablation is a valuable tool in the treatment of many diseases, especially cancer. However, controlled heating up to apoptosis of the desired target tissue in complex situations, e.g. in the spine, is challenging and requires experienced interventionalists. For such challenging situations a mathematical model of radiofrequency ablation allows to understand, improve and optimise the outcome of the medical therapy. The main contribution of this work is the derivation of a tailored, yet expandable mathematical model, for the simulation, analysis, planning and control of radiofrequency ablation in complex situations. The dynamic model consists of partial differential equations that describe the potential and temperature distribution during intervention. To account for multipolar operation, time-dependent boundary conditions are introduced. Spatially distributed parameters, like tissue conductivity and blood perfusion, allow to describe the complex 3D environment representing diverse involved tissue types in the spine. To identify the key parameters affecting the prediction quality of the model, the influence of the parameters on the temperature distribution is investigated via a sensitivity analysis. Simulations underpin the quality of the derived model and the analysis approach. The proposed modelling and analysis schemes set the basis for intervention planning, state- and parameter estimation, and control.
Effects of noisy biological data on picard iteration-based parameter estimation for a glutamate excitotoxicity pathway
IFAC-PapersOnLine, 2018
Biological signal transduction models allow to explain and analyze biological causeeffect relatio... more Biological signal transduction models allow to explain and analyze biological causeeffect relationships and to establish and test new hypotheses about biological pathways. Yet their predictive capability crucially depends on the parameters involved. These parameters are usually determined from experimental data. However, due to the appearing nonlinearities, the resulting inverse problem is often ill-posed and difficult to solve. We outline how parameters can be estimated based on Picard iterations. In case of linear parameter dependence and good measurements of the involved entities, the method allows to retrieve good parameter estimates for medium size problems. The proposed method is applied to an IL-6-dependent Jak-STAT3 signalling pathway model. As shown it it is well suited for data generated by life cell imaging where accurate time series are available.
Nonlinear Power Control of an Internal Combustion Engine Without Throttle Actuator
IEEE Transactions on Control Systems and Technology, Jul 1, 2021
A system consisting of an internal combustion engine (ICE) directly coupled to an electric machin... more A system consisting of an internal combustion engine (ICE) directly coupled to an electric machine for power generation as in range extenders is considered in this brief. The engine power is mostly controlled by acting on the throttle. A second control loop regulates the air-to-fuel ratio by measuring the exhaust oxygen and acting on the fuel-mass flow, whereas the electric machine is usually considered only for the energy conversion. In this brief, the influence of the throttle and the generator speed on the power control is studied. Moreover, a control strategy is proposed that, by acting on the generator, allows the power control without the need of a throttle actuator. The baseline system was compared with the proposed control strategy. The power control leads to a nonlinear control system that is dealt with via feedback linearization. The control strategy was designed and tested in an experimental prototype. The results validate the proposed control structure that ensures a high fuel conversion efficiency within a wide power range and foregoes the throttle actuator. The highest possible fuel conversion efficiency difference in the operation range is 10%.
Nonlinear Power Control of an Internal Combustion Engine Without Throttle Actuator
IEEE Transactions on Control Systems Technology
A system consisting of an internal combustion engine (ICE) directly coupled to an electric machin... more A system consisting of an internal combustion engine (ICE) directly coupled to an electric machine for power generation as in range extenders is considered in this brief. The engine power is mostly controlled by acting on the throttle. A second control loop regulates the air-to-fuel ratio by measuring the exhaust oxygen and acting on the fuel-mass flow, whereas the electric machine is usually considered only for the energy conversion. In this brief, the influence of the throttle and the generator speed on the power control is studied. Moreover, a control strategy is proposed that, by acting on the generator, allows the power control without the need of a throttle actuator. The baseline system was compared with the proposed control strategy. The power control leads to a nonlinear control system that is dealt with via feedback linearization. The control strategy was designed and tested in an experimental prototype. The results validate the proposed control structure that ensures a high fuel conversion efficiency within a wide power range and foregoes the throttle actuator. The highest possible fuel conversion efficiency difference in the operation range is 10%.
On Algebraic Structure of Neighborhoods of Cellular Automata: Horse Power Problem
Fundamenta Informaticae, Aug 1, 2007
... Maurice Margenstern LITA, EA 3097, UFR MIM, University of Metz Île du Saulcy, 57045 Metz, Fra... more ... Maurice Margenstern LITA, EA 3097, UFR MIM, University of Metz Île du Saulcy, 57045 Metz, France ... Particularly we discussed the horse power problem whether the motion of a horse (knight) fills the infinite chess board or Z2 that is, an algebraic problem whether a subset of ...
Effects of noisy biological data on picard iteration-based parameter estimation for a glutamate excitotoxicity pathway
IFAC-PapersOnLine, 2018
Biological signal transduction models allow to explain and analyze biological causeeffect relatio... more Biological signal transduction models allow to explain and analyze biological causeeffect relationships and to establish and test new hypotheses about biological pathways. Yet their predictive capability crucially depends on the parameters involved. These parameters are usually determined from experimental data. However, due to the appearing nonlinearities, the resulting inverse problem is often ill-posed and difficult to solve. We outline how parameters can be estimated based on Picard iterations. In case of linear parameter dependence and good measurements of the involved entities, the method allows to retrieve good parameter estimates for medium size problems. The proposed method is applied to an IL-6-dependent Jak-STAT3 signalling pathway model. As shown it it is well suited for data generated by life cell imaging where accurate time series are available.
IFAC-PapersOnLine, 2018
Mathematical models of biochemical reaction networks are widespread used to shade light and under... more Mathematical models of biochemical reaction networks are widespread used to shade light and understand biological process. The validation and parametert estimation of such models is an important task to ensure the quality of the model. Many parameter estimation strategies for biochemical reaction networks exist by now. This work focuses on the use of an Picard iteration based parameter estimation approach for ODE-based dynamical models, which inherently exploits the model structure. In the frame of this work the influence of measurement errors and noise on the resulting parameter estimation is examined.
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Papers by Friedrich von Haeseler