---
_id: '27426'
abstract:
- lang: eng
  text: "Regularization is used in many different areas of optimization when solutions\r\nare
    sought which not only minimize a given function, but also possess a certain\r\ndegree
    of regularity. Popular applications are image denoising, sparse\r\nregression
    and machine learning. Since the choice of the regularization\r\nparameter is crucial
    but often difficult, path-following methods are used to\r\napproximate the entire
    regularization path, i.e., the set of all possible\r\nsolutions for all regularization
    parameters. Due to their nature, the\r\ndevelopment of these methods requires
    structural results about the\r\nregularization path. The goal of this article
    is to derive these results for\r\nthe case of a smooth objective function which
    is penalized by a piecewise\r\ndifferentiable regularization term. We do this
    by treating regularization as a\r\nmultiobjective optimization problem. Our results
    suggest that even in this\r\ngeneral case, the regularization path is piecewise
    smooth. Moreover, our theory\r\nallows for a classification of the nonsmooth features
    that occur in between\r\nsmooth parts. This is demonstrated in two applications,
    namely support-vector\r\nmachines and exact penalty methods."
author:
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Katharina
  full_name: Bieker, Katharina
  id: '32829'
  last_name: Bieker
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Gebken B, Bieker K, Peitz S. On the structure of regularization paths for piecewise
    differentiable regularization terms. <i>Journal of Global Optimization</i>. 2023;85(3):709-741.
    doi:<a href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>
  apa: Gebken, B., Bieker, K., &#38; Peitz, S. (2023). On the structure of regularization
    paths for piecewise differentiable regularization terms. <i>Journal of Global
    Optimization</i>, <i>85</i>(3), 709–741. <a href="https://doi.org/10.1007/s10898-022-01223-2">https://doi.org/10.1007/s10898-022-01223-2</a>
  bibtex: '@article{Gebken_Bieker_Peitz_2023, title={On the structure of regularization
    paths for piecewise differentiable regularization terms}, volume={85}, DOI={<a
    href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>},
    number={3}, journal={Journal of Global Optimization}, author={Gebken, Bennet and
    Bieker, Katharina and Peitz, Sebastian}, year={2023}, pages={709–741} }'
  chicago: 'Gebken, Bennet, Katharina Bieker, and Sebastian Peitz. “On the Structure
    of Regularization Paths for Piecewise Differentiable Regularization Terms.” <i>Journal
    of Global Optimization</i> 85, no. 3 (2023): 709–41. <a href="https://doi.org/10.1007/s10898-022-01223-2">https://doi.org/10.1007/s10898-022-01223-2</a>.'
  ieee: 'B. Gebken, K. Bieker, and S. Peitz, “On the structure of regularization paths
    for piecewise differentiable regularization terms,” <i>Journal of Global Optimization</i>,
    vol. 85, no. 3, pp. 709–741, 2023, doi: <a href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>.'
  mla: Gebken, Bennet, et al. “On the Structure of Regularization Paths for Piecewise
    Differentiable Regularization Terms.” <i>Journal of Global Optimization</i>, vol.
    85, no. 3, 2023, pp. 709–41, doi:<a href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>.
  short: B. Gebken, K. Bieker, S. Peitz, Journal of Global Optimization 85 (2023)
    709–741.
date_created: 2021-11-15T09:24:59Z
date_updated: 2023-03-11T17:16:33Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/s10898-022-01223-2
intvolume: '        85'
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s10898-022-01223-2.pdf
oa: '1'
page: 709-741
publication: Journal of Global Optimization
status: public
title: On the structure of regularization paths for piecewise differentiable regularization
  terms
type: journal_article
user_id: '47427'
volume: 85
year: '2023'
...
---
_id: '30125'
abstract:
- lang: eng
  text: We present an approach for guaranteed constraint satisfaction by means of
    data-based optimal control, where the model is unknown and has to be obtained
    from measurement data. To this end, we utilize the Koopman framework and an eDMD-based
    bilinear surrogate modeling approach for control systems to show an error bound
    on predicted observables, i.e., functions of the state. This result is then applied
    to the constraints of the optimal control problem to show that satisfaction of
    tightened constraints in the purely data-based surrogate model implies constraint
    satisfaction for the original system.
author:
- first_name: Manuel
  full_name: Schaller, Manuel
  last_name: Schaller
- first_name: Karl
  full_name: Worthmann, Karl
  last_name: Worthmann
- first_name: Friedrich
  full_name: Philipp, Friedrich
  last_name: Philipp
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Feliks
  full_name: Nüske, Feliks
  id: '81513'
  last_name: Nüske
  orcid: 0000-0003-2444-7889
citation:
  ama: 'Schaller M, Worthmann K, Philipp F, Peitz S, Nüske F. Towards reliable data-based
    optimal and predictive control using extended DMD. In: <i>IFAC-PapersOnLine</i>.
    Vol 56. ; 2023:169-174. doi:<a href="https://doi.org/10.1016/j.ifacol.2023.02.029">10.1016/j.ifacol.2023.02.029</a>'
  apa: Schaller, M., Worthmann, K., Philipp, F., Peitz, S., &#38; Nüske, F. (2023).
    Towards reliable data-based optimal and predictive control using extended DMD.
    <i>IFAC-PapersOnLine</i>, <i>56</i>(1), 169–174. <a href="https://doi.org/10.1016/j.ifacol.2023.02.029">https://doi.org/10.1016/j.ifacol.2023.02.029</a>
  bibtex: '@inproceedings{Schaller_Worthmann_Philipp_Peitz_Nüske_2023, title={Towards
    reliable data-based optimal and predictive control using extended DMD}, volume={56},
    DOI={<a href="https://doi.org/10.1016/j.ifacol.2023.02.029">10.1016/j.ifacol.2023.02.029</a>},
    number={1}, booktitle={IFAC-PapersOnLine}, author={Schaller, Manuel and Worthmann,
    Karl and Philipp, Friedrich and Peitz, Sebastian and Nüske, Feliks}, year={2023},
    pages={169–174} }'
  chicago: Schaller, Manuel, Karl Worthmann, Friedrich Philipp, Sebastian Peitz, and
    Feliks Nüske. “Towards Reliable Data-Based Optimal and Predictive Control Using
    Extended DMD.” In <i>IFAC-PapersOnLine</i>, 56:169–74, 2023. <a href="https://doi.org/10.1016/j.ifacol.2023.02.029">https://doi.org/10.1016/j.ifacol.2023.02.029</a>.
  ieee: 'M. Schaller, K. Worthmann, F. Philipp, S. Peitz, and F. Nüske, “Towards reliable
    data-based optimal and predictive control using extended DMD,” in <i>IFAC-PapersOnLine</i>,
    2023, vol. 56, no. 1, pp. 169–174, doi: <a href="https://doi.org/10.1016/j.ifacol.2023.02.029">10.1016/j.ifacol.2023.02.029</a>.'
  mla: Schaller, Manuel, et al. “Towards Reliable Data-Based Optimal and Predictive
    Control Using Extended DMD.” <i>IFAC-PapersOnLine</i>, vol. 56, no. 1, 2023, pp.
    169–74, doi:<a href="https://doi.org/10.1016/j.ifacol.2023.02.029">10.1016/j.ifacol.2023.02.029</a>.
  short: 'M. Schaller, K. Worthmann, F. Philipp, S. Peitz, F. Nüske, in: IFAC-PapersOnLine,
    2023, pp. 169–174.'
conference:
  name: 12th IFAC Symposium on Nonlinear Control Systems (NOLCOS)
date_created: 2022-02-25T17:14:58Z
date_updated: 2023-03-17T15:55:33Z
department:
- _id: '655'
doi: 10.1016/j.ifacol.2023.02.029
external_id:
  arxiv:
  - '2202.09084'
intvolume: '        56'
issue: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.sciencedirect.com/science/article/pii/S2405896323002173/pdf?md5=164ee9a0343a1bd0e0b9ac4187e44b77&pid=1-s2.0-S2405896323002173-main.pdf
oa: '1'
page: 169-174
publication: IFAC-PapersOnLine
publication_status: published
status: public
title: Towards reliable data-based optimal and predictive control using extended DMD
type: conference
user_id: '47427'
volume: 56
year: '2023'
...
---
_id: '46579'
abstract:
- lang: eng
  text: "The Koopman operator has become an essential tool for data-driven analysis,
    prediction and control of complex systems, the main reason being the enormous
    potential of identifying linear function space representations of nonlinear\r\ndynamics
    from measurements. Until now, the situation where for large-scale systems, we
    (i) only have access to partial observations (i.e., measurements, as is very common
    for experimental data) or (ii) deliberately perform coarse\r\ngraining (for efficiency
    reasons) has not been treated to its full extent. In this paper, we address the
    pitfall associated with this situation, that the classical EDMD algorithm does
    not automatically provide a Koopman operator approximation for the underlying
    system if we do not carefully select the number of observables. Moreover, we show
    that symmetries in the system dynamics can be carried over to the Koopman operator,
    which allows us to massively increase the model efficiency. We also briefly draw
    a connection to domain decomposition techniques for partial differential equations
    and present numerical evidence using the Kuramoto--Sivashinsky equation."
author:
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Hans
  full_name: Harder, Hans
  id: '98879'
  last_name: Harder
- first_name: Feliks
  full_name: Nüske, Feliks
  last_name: Nüske
- first_name: Friedrich
  full_name: Philipp, Friedrich
  last_name: Philipp
- first_name: Manuel
  full_name: Schaller, Manuel
  last_name: Schaller
- first_name: Karl
  full_name: Worthmann, Karl
  last_name: Worthmann
citation:
  ama: Peitz S, Harder H, Nüske F, Philipp F, Schaller M, Worthmann K. Partial observations,
    coarse graining and equivariance in Koopman  operator theory for large-scale dynamical
    systems. <i>arXiv:230715325</i>. Published online 2023.
  apa: Peitz, S., Harder, H., Nüske, F., Philipp, F., Schaller, M., &#38; Worthmann,
    K. (2023). Partial observations, coarse graining and equivariance in Koopman 
    operator theory for large-scale dynamical systems. In <i>arXiv:2307.15325</i>.
  bibtex: '@article{Peitz_Harder_Nüske_Philipp_Schaller_Worthmann_2023, title={Partial
    observations, coarse graining and equivariance in Koopman  operator theory for
    large-scale dynamical systems}, journal={arXiv:2307.15325}, author={Peitz, Sebastian
    and Harder, Hans and Nüske, Feliks and Philipp, Friedrich and Schaller, Manuel
    and Worthmann, Karl}, year={2023} }'
  chicago: Peitz, Sebastian, Hans Harder, Feliks Nüske, Friedrich Philipp, Manuel
    Schaller, and Karl Worthmann. “Partial Observations, Coarse Graining and Equivariance
    in Koopman  Operator Theory for Large-Scale Dynamical Systems.” <i>ArXiv:2307.15325</i>,
    2023.
  ieee: S. Peitz, H. Harder, F. Nüske, F. Philipp, M. Schaller, and K. Worthmann,
    “Partial observations, coarse graining and equivariance in Koopman  operator theory
    for large-scale dynamical systems,” <i>arXiv:2307.15325</i>. 2023.
  mla: Peitz, Sebastian, et al. “Partial Observations, Coarse Graining and Equivariance
    in Koopman  Operator Theory for Large-Scale Dynamical Systems.” <i>ArXiv:2307.15325</i>,
    2023.
  short: S. Peitz, H. Harder, F. Nüske, F. Philipp, M. Schaller, K. Worthmann, ArXiv:2307.15325
    (2023).
date_created: 2023-08-21T05:52:24Z
date_updated: 2023-08-21T05:53:35Z
department:
- _id: '655'
external_id:
  arxiv:
  - '2307.15325'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/pdf/2307.15325
oa: '1'
publication: arXiv:2307.15325
status: public
title: Partial observations, coarse graining and equivariance in Koopman  operator
  theory for large-scale dynamical systems
type: preprint
user_id: '47427'
year: '2023'
...
---
_id: '23428'
abstract:
- lang: eng
  text: "The Koopman operator has become an essential tool for data-driven approximation
    of dynamical (control) systems in recent years, e.g., via extended dynamic mode
    decomposition. Despite its popularity, convergence results and, in particular,
    error bounds are still quite scarce. In this paper, we derive probabilistic bounds
    for the approximation error and the prediction error depending on the number of
    training data points; for both ordinary and stochastic differential equations.
    Moreover, we extend our analysis to nonlinear control-affine systems using either
    ergodic trajectories or i.i.d.\r\nsamples. Here, we exploit the linearity of the
    Koopman generator to obtain a bilinear system and, thus, circumvent the curse
    of dimensionality since we do not autonomize the system by augmenting the state
    by the control inputs. To the\r\nbest of our knowledge, this is the first finite-data
    error analysis in the stochastic and/or control setting. Finally, we demonstrate
    the effectiveness of the proposed approach by comparing it with state-of-the-art
    techniques showing its superiority whenever state and control are coupled."
article_number: '14'
author:
- first_name: Feliks
  full_name: Nüske, Feliks
  id: '81513'
  last_name: Nüske
  orcid: 0000-0003-2444-7889
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Friedrich
  full_name: Philipp, Friedrich
  last_name: Philipp
- first_name: Manuel
  full_name: Schaller, Manuel
  last_name: Schaller
- first_name: Karl
  full_name: Worthmann, Karl
  last_name: Worthmann
citation:
  ama: Nüske F, Peitz S, Philipp F, Schaller M, Worthmann K. Finite-data error bounds
    for Koopman-based prediction and control. <i>Journal of Nonlinear Science</i>.
    2023;33. doi:<a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>
  apa: Nüske, F., Peitz, S., Philipp, F., Schaller, M., &#38; Worthmann, K. (2023).
    Finite-data error bounds for Koopman-based prediction and control. <i>Journal
    of Nonlinear Science</i>, <i>33</i>, Article 14. <a href="https://doi.org/10.1007/s00332-022-09862-1">https://doi.org/10.1007/s00332-022-09862-1</a>
  bibtex: '@article{Nüske_Peitz_Philipp_Schaller_Worthmann_2023, title={Finite-data
    error bounds for Koopman-based prediction and control}, volume={33}, DOI={<a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>},
    number={14}, journal={Journal of Nonlinear Science}, author={Nüske, Feliks and
    Peitz, Sebastian and Philipp, Friedrich and Schaller, Manuel and Worthmann, Karl},
    year={2023} }'
  chicago: Nüske, Feliks, Sebastian Peitz, Friedrich Philipp, Manuel Schaller, and
    Karl Worthmann. “Finite-Data Error Bounds for Koopman-Based Prediction and Control.”
    <i>Journal of Nonlinear Science</i> 33 (2023). <a href="https://doi.org/10.1007/s00332-022-09862-1">https://doi.org/10.1007/s00332-022-09862-1</a>.
  ieee: 'F. Nüske, S. Peitz, F. Philipp, M. Schaller, and K. Worthmann, “Finite-data
    error bounds for Koopman-based prediction and control,” <i>Journal of Nonlinear
    Science</i>, vol. 33, Art. no. 14, 2023, doi: <a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>.'
  mla: Nüske, Feliks, et al. “Finite-Data Error Bounds for Koopman-Based Prediction
    and Control.” <i>Journal of Nonlinear Science</i>, vol. 33, 14, 2023, doi:<a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>.
  short: F. Nüske, S. Peitz, F. Philipp, M. Schaller, K. Worthmann, Journal of Nonlinear
    Science 33 (2023).
date_created: 2021-08-17T12:25:09Z
date_updated: 2023-08-24T07:50:12Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/s00332-022-09862-1
intvolume: '        33'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s00332-022-09862-1.pdf
oa: '1'
publication: Journal of Nonlinear Science
publication_status: published
status: public
title: Finite-data error bounds for Koopman-based prediction and control
type: journal_article
user_id: '47427'
volume: 33
year: '2023'
...
---
_id: '21600'
abstract:
- lang: eng
  text: Many problems in science and engineering require an efficient numerical approximation
    of integrals or solutions to differential equations. For systems with rapidly
    changing dynamics, an equidistant discretization is often inadvisable as it results
    in prohibitively large errors or computational effort. To this end, adaptive schemes,
    such as solvers based on Runge–Kutta pairs, have been developed which adapt the
    step size based on local error estimations at each step. While the classical schemes
    apply very generally and are highly efficient on regular systems, they can behave
    suboptimally when an inefficient step rejection mechanism is triggered by structurally
    complex systems such as chaotic systems. To overcome these issues, we propose
    a method to tailor numerical schemes to the problem class at hand. This is achieved
    by combining simple, classical quadrature rules or ODE solvers with data-driven
    time-stepping controllers. Compared with learning solution operators to ODEs directly,
    it generalizes better to unseen initial data as our approach employs classical
    numerical schemes as base methods. At the same time it can make use of identified
    structures of a problem class and, therefore, outperforms state-of-the-art adaptive
    schemes. Several examples demonstrate superior efficiency. Source code is available
    at https://github.com/lueckem/quadrature-ML.
author:
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
- first_name: Eyke
  full_name: Hüllermeier, Eyke
  id: '48129'
  last_name: Hüllermeier
- first_name: Marvin
  full_name: Lücke, Marvin
  last_name: Lücke
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Karlson
  full_name: Pfannschmidt, Karlson
  id: '13472'
  last_name: Pfannschmidt
  orcid: 0000-0001-9407-7903
citation:
  ama: Dellnitz M, Hüllermeier E, Lücke M, et al. Efficient time stepping for numerical
    integration using reinforcement  learning. <i>SIAM Journal on Scientific Computing</i>.
    2023;45(2):A579-A595. doi:<a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>
  apa: Dellnitz, M., Hüllermeier, E., Lücke, M., Ober-Blöbaum, S., Offen, C., Peitz,
    S., &#38; Pfannschmidt, K. (2023). Efficient time stepping for numerical integration
    using reinforcement  learning. <i>SIAM Journal on Scientific Computing</i>, <i>45</i>(2),
    A579–A595. <a href="https://doi.org/10.1137/21M1412682">https://doi.org/10.1137/21M1412682</a>
  bibtex: '@article{Dellnitz_Hüllermeier_Lücke_Ober-Blöbaum_Offen_Peitz_Pfannschmidt_2023,
    title={Efficient time stepping for numerical integration using reinforcement 
    learning}, volume={45}, DOI={<a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>},
    number={2}, journal={SIAM Journal on Scientific Computing}, author={Dellnitz,
    Michael and Hüllermeier, Eyke and Lücke, Marvin and Ober-Blöbaum, Sina and Offen,
    Christian and Peitz, Sebastian and Pfannschmidt, Karlson}, year={2023}, pages={A579–A595}
    }'
  chicago: 'Dellnitz, Michael, Eyke Hüllermeier, Marvin Lücke, Sina Ober-Blöbaum,
    Christian Offen, Sebastian Peitz, and Karlson Pfannschmidt. “Efficient Time Stepping
    for Numerical Integration Using Reinforcement  Learning.” <i>SIAM Journal on Scientific
    Computing</i> 45, no. 2 (2023): A579–95. <a href="https://doi.org/10.1137/21M1412682">https://doi.org/10.1137/21M1412682</a>.'
  ieee: 'M. Dellnitz <i>et al.</i>, “Efficient time stepping for numerical integration
    using reinforcement  learning,” <i>SIAM Journal on Scientific Computing</i>, vol.
    45, no. 2, pp. A579–A595, 2023, doi: <a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>.'
  mla: Dellnitz, Michael, et al. “Efficient Time Stepping for Numerical Integration
    Using Reinforcement  Learning.” <i>SIAM Journal on Scientific Computing</i>, vol.
    45, no. 2, 2023, pp. A579–95, doi:<a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>.
  short: M. Dellnitz, E. Hüllermeier, M. Lücke, S. Ober-Blöbaum, C. Offen, S. Peitz,
    K. Pfannschmidt, SIAM Journal on Scientific Computing 45 (2023) A579–A595.
date_created: 2021-04-09T07:59:19Z
date_updated: 2023-08-25T09:24:50Z
ddc:
- '510'
department:
- _id: '101'
- _id: '636'
- _id: '355'
- _id: '655'
doi: 10.1137/21M1412682
external_id:
  arxiv:
  - arXiv:2104.03562
has_accepted_license: '1'
intvolume: '        45'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://epubs.siam.org/doi/reader/10.1137/21M1412682
page: A579-A595
publication: SIAM Journal on Scientific Computing
publication_status: published
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/lueckem/quadrature-ML
status: public
title: Efficient time stepping for numerical integration using reinforcement  learning
type: journal_article
user_id: '47427'
volume: 45
year: '2023'
...
---
_id: '46784'
article_number: '5616'
author:
- first_name: Oliver
  full_name: Wallscheid, Oliver
  id: '11291'
  last_name: Wallscheid
  orcid: https://orcid.org/0000-0001-9362-8777
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Jan
  full_name: Stenner, Jan
  id: '65520'
  last_name: Stenner
- first_name: Daniel
  full_name: Weber, Daniel
  id: '24041'
  last_name: Weber
  orcid: 0000-0003-3367-5998
- first_name: Septimus
  full_name: Boshoff, Septimus
  last_name: Boshoff
- first_name: Marvin
  full_name: Meyer, Marvin
  last_name: Meyer
- first_name: Vikas
  full_name: Chidananda, Vikas
  last_name: Chidananda
- first_name: Oliver
  full_name: Schweins, Oliver
  last_name: Schweins
citation:
  ama: Wallscheid O, Peitz S, Stenner J, et al. ElectricGrid.jl - A Julia-based modeling
    and simulationtool for power electronics-driven electric energy grids. <i>Journal
    of Open Source Software</i>. 2023;8(89). doi:<a href="https://doi.org/10.21105/joss.05616">10.21105/joss.05616</a>
  apa: Wallscheid, O., Peitz, S., Stenner, J., Weber, D., Boshoff, S., Meyer, M.,
    Chidananda, V., &#38; Schweins, O. (2023). ElectricGrid.jl - A Julia-based modeling
    and simulationtool for power electronics-driven electric energy grids. <i>Journal
    of Open Source Software</i>, <i>8</i>(89), Article 5616. <a href="https://doi.org/10.21105/joss.05616">https://doi.org/10.21105/joss.05616</a>
  bibtex: '@article{Wallscheid_Peitz_Stenner_Weber_Boshoff_Meyer_Chidananda_Schweins_2023,
    title={ElectricGrid.jl - A Julia-based modeling and simulationtool for power electronics-driven
    electric energy grids}, volume={8}, DOI={<a href="https://doi.org/10.21105/joss.05616">10.21105/joss.05616</a>},
    number={895616}, journal={Journal of Open Source Software}, publisher={The Open
    Journal}, author={Wallscheid, Oliver and Peitz, Sebastian and Stenner, Jan and
    Weber, Daniel and Boshoff, Septimus and Meyer, Marvin and Chidananda, Vikas and
    Schweins, Oliver}, year={2023} }'
  chicago: Wallscheid, Oliver, Sebastian Peitz, Jan Stenner, Daniel Weber, Septimus
    Boshoff, Marvin Meyer, Vikas Chidananda, and Oliver Schweins. “ElectricGrid.Jl
    - A Julia-Based Modeling and Simulationtool for Power Electronics-Driven Electric
    Energy Grids.” <i>Journal of Open Source Software</i> 8, no. 89 (2023). <a href="https://doi.org/10.21105/joss.05616">https://doi.org/10.21105/joss.05616</a>.
  ieee: 'O. Wallscheid <i>et al.</i>, “ElectricGrid.jl - A Julia-based modeling and
    simulationtool for power electronics-driven electric energy grids,” <i>Journal
    of Open Source Software</i>, vol. 8, no. 89, Art. no. 5616, 2023, doi: <a href="https://doi.org/10.21105/joss.05616">10.21105/joss.05616</a>.'
  mla: Wallscheid, Oliver, et al. “ElectricGrid.Jl - A Julia-Based Modeling and Simulationtool
    for Power Electronics-Driven Electric Energy Grids.” <i>Journal of Open Source
    Software</i>, vol. 8, no. 89, 5616, The Open Journal, 2023, doi:<a href="https://doi.org/10.21105/joss.05616">10.21105/joss.05616</a>.
  short: O. Wallscheid, S. Peitz, J. Stenner, D. Weber, S. Boshoff, M. Meyer, V. Chidananda,
    O. Schweins, Journal of Open Source Software 8 (2023).
date_created: 2023-09-04T11:05:03Z
date_updated: 2023-09-04T11:06:06Z
department:
- _id: '655'
- _id: '52'
doi: 10.21105/joss.05616
intvolume: '         8'
issue: '89'
keyword:
- General Earth and Planetary Sciences
- General Environmental Science
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://joss.theoj.org/papers/10.21105/joss.05616
oa: '1'
publication: Journal of Open Source Software
publication_identifier:
  issn:
  - 2475-9066
publication_status: published
publisher: The Open Journal
status: public
title: ElectricGrid.jl - A Julia-based modeling and simulationtool for power electronics-driven
  electric energy grids
type: journal_article
user_id: '47427'
volume: 8
year: '2023'
...
---
_id: '46813'
abstract:
- lang: eng
  text: Modelling of dynamic systems plays an important role in many engineering disciplines.
    Two different approaches are physical modelling and data‐driven modelling, both
    of which have their respective advantages and disadvantages. By combining these
    two approaches, hybrid models can be created in which the respective disadvantages
    are mitigated, with discrepancy models being a particular subclass. Here, the
    basic system behaviour is described physically, that is, in the form of differential
    equations. Inaccuracies resulting from insufficient modelling or numerics lead
    to a discrepancy between the measurements and the model, which can be compensated
    by a data‐driven error correction term. Since discrepancy methods still require
    a large amount of measurement data, this paper investigates the extent to which
    a single discrepancy model can be trained for a physical model with additional
    parameter dependencies without the need for retraining. As an example, a damped
    electromagnetic oscillating circuit is used. The physical model is realised by
    a differential equation describing the electric current, considering only inductance
    and capacitance; dissipation due to resistance is neglected. This creates a discrepancy
    between measurement and model, which is corrected by a data‐driven model. In the
    experiments, the inductance and the capacity are varied. It is found that the
    same data‐driven model can only be used if additional parametric dependencies
    in the data‐driven term are considered as well.
author:
- first_name: Meike Claudia
  full_name: Wohlleben, Meike Claudia
  id: '43991'
  last_name: Wohlleben
  orcid: 0009-0009-9767-7168
- first_name: Lars
  full_name: Muth, Lars
  id: '77313'
  last_name: Muth
  orcid: 0000-0002-2938-5616
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: 'Wohlleben MC, Muth L, Peitz S, Sextro W. Transferability of a discrepancy
    model for the dynamics of electromagnetic oscillating circuits. In: <i>Proceedings
    in Applied Mathematics and Mechanics</i>. Wiley; 2023. doi:<a href="https://doi.org/10.1002/pamm.202300039">10.1002/pamm.202300039</a>'
  apa: Wohlleben, M. C., Muth, L., Peitz, S., &#38; Sextro, W. (2023). Transferability
    of a discrepancy model for the dynamics of electromagnetic oscillating circuits.
    <i>Proceedings in Applied Mathematics and Mechanics</i>. <a href="https://doi.org/10.1002/pamm.202300039">https://doi.org/10.1002/pamm.202300039</a>
  bibtex: '@inproceedings{Wohlleben_Muth_Peitz_Sextro_2023, title={Transferability
    of a discrepancy model for the dynamics of electromagnetic oscillating circuits},
    DOI={<a href="https://doi.org/10.1002/pamm.202300039">10.1002/pamm.202300039</a>},
    booktitle={Proceedings in Applied Mathematics and Mechanics}, publisher={Wiley},
    author={Wohlleben, Meike Claudia and Muth, Lars and Peitz, Sebastian and Sextro,
    Walter}, year={2023} }'
  chicago: Wohlleben, Meike Claudia, Lars Muth, Sebastian Peitz, and Walter Sextro.
    “Transferability of a Discrepancy Model for the Dynamics of Electromagnetic Oscillating
    Circuits.” In <i>Proceedings in Applied Mathematics and Mechanics</i>. Wiley,
    2023. <a href="https://doi.org/10.1002/pamm.202300039">https://doi.org/10.1002/pamm.202300039</a>.
  ieee: 'M. C. Wohlleben, L. Muth, S. Peitz, and W. Sextro, “Transferability of a
    discrepancy model for the dynamics of electromagnetic oscillating circuits,” 2023,
    doi: <a href="https://doi.org/10.1002/pamm.202300039">10.1002/pamm.202300039</a>.'
  mla: Wohlleben, Meike Claudia, et al. “Transferability of a Discrepancy Model for
    the Dynamics of Electromagnetic Oscillating Circuits.” <i>Proceedings in Applied
    Mathematics and Mechanics</i>, Wiley, 2023, doi:<a href="https://doi.org/10.1002/pamm.202300039">10.1002/pamm.202300039</a>.
  short: 'M.C. Wohlleben, L. Muth, S. Peitz, W. Sextro, in: Proceedings in Applied
    Mathematics and Mechanics, Wiley, 2023.'
date_created: 2023-09-06T05:18:05Z
date_updated: 2023-09-21T14:47:20Z
department:
- _id: '655'
- _id: '151'
doi: 10.1002/pamm.202300039
keyword:
- Electrical and Electronic Engineering
- Atomic and Molecular Physics
- and Optics
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://onlinelibrary.wiley.com/doi/epdf/10.1002/pamm.202300039
oa: '1'
publication: Proceedings in Applied Mathematics and Mechanics
publication_identifier:
  issn:
  - 1617-7061
  - 1617-7061
publication_status: published
publisher: Wiley
quality_controlled: '1'
status: public
title: Transferability of a discrepancy model for the dynamics of electromagnetic
  oscillating circuits
type: conference
user_id: '77313'
year: '2023'
...
---
_id: '16296'
abstract:
- lang: eng
  text: "Multiobjective optimization plays an increasingly important role in modern\r\napplications,
    where several objectives are often of equal importance. The task\r\nin multiobjective
    optimization and multiobjective optimal control is therefore\r\nto compute the
    set of optimal compromises (the Pareto set) between the\r\nconflicting objectives.
    Since the Pareto set generally consists of an infinite\r\nnumber of solutions,
    the computational effort can quickly become challenging\r\nwhich is particularly
    problematic when the objectives are costly to evaluate as\r\nis the case for models
    governed by partial differential equations (PDEs). To\r\ndecrease the numerical
    effort to an affordable amount, surrogate models can be\r\nused to replace the
    expensive PDE evaluations. Existing multiobjective\r\noptimization methods using
    model reduction are limited either to low parameter\r\ndimensions or to few (ideally
    two) objectives. In this article, we present a\r\ncombination of the reduced basis
    model reduction method with a continuation\r\napproach using inexact gradients.
    The resulting approach can handle an\r\narbitrary number of objectives while yielding
    a significant reduction in\r\ncomputing time."
author:
- first_name: Stefan
  full_name: Banholzer, Stefan
  last_name: Banholzer
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: https://orcid.org/0000-0002-3389-793X
- first_name: Stefan
  full_name: Volkwein, Stefan
  last_name: Volkwein
citation:
  ama: 'Banholzer S, Gebken B, Dellnitz M, Peitz S, Volkwein S. ROM-Based Multiobjective
    Optimization of Elliptic PDEs via Numerical Continuation. In: Michael H, Roland
    H, Christian K, Michael U, Stefan U, eds. <i>Non-Smooth and Complementarity-Based
    Distributed Parameter Systems</i>. Springer; 2022:43-76. doi:<a href="https://doi.org/10.1007/978-3-030-79393-7_3">10.1007/978-3-030-79393-7_3</a>'
  apa: Banholzer, S., Gebken, B., Dellnitz, M., Peitz, S., &#38; Volkwein, S. (2022).
    ROM-Based Multiobjective Optimization of Elliptic PDEs via Numerical Continuation.
    In H. Michael, H. Roland, K. Christian, U. Michael, &#38; U. Stefan (Eds.), <i>Non-Smooth
    and Complementarity-Based Distributed Parameter Systems</i> (pp. 43–76). Springer.
    <a href="https://doi.org/10.1007/978-3-030-79393-7_3">https://doi.org/10.1007/978-3-030-79393-7_3</a>
  bibtex: '@inbook{Banholzer_Gebken_Dellnitz_Peitz_Volkwein_2022, place={Cham}, title={ROM-Based
    Multiobjective Optimization of Elliptic PDEs via Numerical Continuation}, DOI={<a
    href="https://doi.org/10.1007/978-3-030-79393-7_3">10.1007/978-3-030-79393-7_3</a>},
    booktitle={Non-Smooth and Complementarity-Based Distributed Parameter Systems},
    publisher={Springer}, author={Banholzer, Stefan and Gebken, Bennet and Dellnitz,
    Michael and Peitz, Sebastian and Volkwein, Stefan}, editor={Michael, Hintermüller
    and Roland, Herzog and Christian, Kanzow and Michael, Ulbrich and Stefan, Ulbrich},
    year={2022}, pages={43–76} }'
  chicago: 'Banholzer, Stefan, Bennet Gebken, Michael Dellnitz, Sebastian Peitz, and
    Stefan Volkwein. “ROM-Based Multiobjective Optimization of Elliptic PDEs via Numerical
    Continuation.” In <i>Non-Smooth and Complementarity-Based Distributed Parameter
    Systems</i>, edited by Hintermüller Michael, Herzog Roland, Kanzow Christian,
    Ulbrich Michael, and Ulbrich Stefan, 43–76. Cham: Springer, 2022. <a href="https://doi.org/10.1007/978-3-030-79393-7_3">https://doi.org/10.1007/978-3-030-79393-7_3</a>.'
  ieee: 'S. Banholzer, B. Gebken, M. Dellnitz, S. Peitz, and S. Volkwein, “ROM-Based
    Multiobjective Optimization of Elliptic PDEs via Numerical Continuation,” in <i>Non-Smooth
    and Complementarity-Based Distributed Parameter Systems</i>, H. Michael, H. Roland,
    K. Christian, U. Michael, and U. Stefan, Eds. Cham: Springer, 2022, pp. 43–76.'
  mla: Banholzer, Stefan, et al. “ROM-Based Multiobjective Optimization of Elliptic
    PDEs via Numerical Continuation.” <i>Non-Smooth and Complementarity-Based Distributed
    Parameter Systems</i>, edited by Hintermüller Michael et al., Springer, 2022,
    pp. 43–76, doi:<a href="https://doi.org/10.1007/978-3-030-79393-7_3">10.1007/978-3-030-79393-7_3</a>.
  short: 'S. Banholzer, B. Gebken, M. Dellnitz, S. Peitz, S. Volkwein, in: H. Michael,
    H. Roland, K. Christian, U. Michael, U. Stefan (Eds.), Non-Smooth and Complementarity-Based
    Distributed Parameter Systems, Springer, Cham, 2022, pp. 43–76.'
date_created: 2020-03-13T12:45:31Z
date_updated: 2022-03-14T13:04:51Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/978-3-030-79393-7_3
editor:
- first_name: Hintermüller
  full_name: Michael, Hintermüller
  last_name: Michael
- first_name: Herzog
  full_name: Roland, Herzog
  last_name: Roland
- first_name: Kanzow
  full_name: Christian, Kanzow
  last_name: Christian
- first_name: Ulbrich
  full_name: Michael, Ulbrich
  last_name: Michael
- first_name: Ulbrich
  full_name: Stefan, Ulbrich
  last_name: Stefan
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/pdf/1906.09075.pdf
oa: '1'
page: 43-76
place: Cham
publication: Non-Smooth and Complementarity-Based Distributed Parameter Systems
publication_identifier:
  isbn:
  - 978-3-030-79392-0
publisher: Springer
status: public
title: ROM-Based Multiobjective Optimization of Elliptic PDEs via Numerical Continuation
type: book_chapter
user_id: '47427'
year: '2022'
...
---
_id: '30294'
abstract:
- lang: eng
  text: With the ever increasing capabilities of sensors and controllers, autonomous
    driving is quickly becoming a reality. This disruptive change in the automotive
    industry poses major challenges for manufacturers as well as suppliers as entirely
    new design and testing strategies have to be developed to remain competitive.
    Most importantly, the complexity of autonomously driving vehicles in a complex,
    uncertain, and safety-critical environment requires new testing procedures to
    cover the almost infinite range of potential scenarios.
author:
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
- first_name: Sebastian
  full_name: Bannenberg, Sebastian
  last_name: Bannenberg
citation:
  ama: 'Peitz S, Dellnitz M, Bannenberg S. Efficient Virtual Design and Testing of
    Autonomous Vehicles. In: Bock HG, Küfer K-H, Maas P, Milde A, Schulz V, eds. <i>German
    Success Stories in Industrial Mathematics</i>. Vol 35. Mathematics in Industry.
    Springer International Publishing; 2022. doi:<a href="https://doi.org/10.1007/978-3-030-81455-7_23">10.1007/978-3-030-81455-7_23</a>'
  apa: Peitz, S., Dellnitz, M., &#38; Bannenberg, S. (2022). Efficient Virtual Design
    and Testing of Autonomous Vehicles. In H. G. Bock, K.-H. Küfer, P. Maas, A. Milde,
    &#38; V. Schulz (Eds.), <i>German Success Stories in Industrial Mathematics</i>
    (Vol. 35). Springer International Publishing. <a href="https://doi.org/10.1007/978-3-030-81455-7_23">https://doi.org/10.1007/978-3-030-81455-7_23</a>
  bibtex: '@inbook{Peitz_Dellnitz_Bannenberg_2022, place={Cham}, series={Mathematics
    in Industry}, title={Efficient Virtual Design and Testing of Autonomous Vehicles},
    volume={35}, DOI={<a href="https://doi.org/10.1007/978-3-030-81455-7_23">10.1007/978-3-030-81455-7_23</a>},
    booktitle={German Success Stories in Industrial Mathematics}, publisher={Springer
    International Publishing}, author={Peitz, Sebastian and Dellnitz, Michael and
    Bannenberg, Sebastian}, editor={Bock, H. G. and Küfer, K.-H. and Maas, P. and
    Milde, A. and Schulz, V.}, year={2022}, collection={Mathematics in Industry} }'
  chicago: 'Peitz, Sebastian, Michael Dellnitz, and Sebastian Bannenberg. “Efficient
    Virtual Design and Testing of Autonomous Vehicles.” In <i>German Success Stories
    in Industrial Mathematics</i>, edited by H. G. Bock, K.-H. Küfer, P. Maas, A.
    Milde, and V. Schulz, Vol. 35. Mathematics in Industry. Cham: Springer International
    Publishing, 2022. <a href="https://doi.org/10.1007/978-3-030-81455-7_23">https://doi.org/10.1007/978-3-030-81455-7_23</a>.'
  ieee: 'S. Peitz, M. Dellnitz, and S. Bannenberg, “Efficient Virtual Design and Testing
    of Autonomous Vehicles,” in <i>German Success Stories in Industrial Mathematics</i>,
    vol. 35, H. G. Bock, K.-H. Küfer, P. Maas, A. Milde, and V. Schulz, Eds. Cham:
    Springer International Publishing, 2022.'
  mla: Peitz, Sebastian, et al. “Efficient Virtual Design and Testing of Autonomous
    Vehicles.” <i>German Success Stories in Industrial Mathematics</i>, edited by
    H. G. Bock et al., vol. 35, Springer International Publishing, 2022, doi:<a href="https://doi.org/10.1007/978-3-030-81455-7_23">10.1007/978-3-030-81455-7_23</a>.
  short: 'S. Peitz, M. Dellnitz, S. Bannenberg, in: H.G. Bock, K.-H. Küfer, P. Maas,
    A. Milde, V. Schulz (Eds.), German Success Stories in Industrial Mathematics,
    Springer International Publishing, Cham, 2022.'
date_created: 2022-03-14T07:32:41Z
date_updated: 2022-03-14T07:42:01Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/978-3-030-81455-7_23
editor:
- first_name: H. G.
  full_name: Bock, H. G.
  last_name: Bock
- first_name: K.-H.
  full_name: Küfer, K.-H.
  last_name: Küfer
- first_name: P.
  full_name: Maas, P.
  last_name: Maas
- first_name: A.
  full_name: Milde, A.
  last_name: Milde
- first_name: V.
  full_name: Schulz, V.
  last_name: Schulz
intvolume: '        35'
language:
- iso: eng
place: Cham
publication: German Success Stories in Industrial Mathematics
publication_identifier:
  isbn:
  - '9783030814540'
  - '9783030814557'
  issn:
  - 1612-3956
  - 2198-3283
publication_status: published
publisher: Springer International Publishing
series_title: Mathematics in Industry
status: public
title: Efficient Virtual Design and Testing of Autonomous Vehicles
type: book_chapter
user_id: '47427'
volume: 35
year: '2022'
...
---
_id: '29673'
abstract:
- lang: eng
  text: Koopman operator theory has been successfully applied to problems from various
    research areas such as fluid dynamics, molecular dynamics, climate science, engineering,
    and biology. Applications include detecting metastable or coherent sets, coarse-graining,
    system identification, and control. There is an intricate connection between dynamical
    systems driven by stochastic differential equations and quantum mechanics. In
    this paper, we compare the ground-state transformation and Nelson's stochastic
    mechanics and demonstrate how data-driven methods developed for the approximation
    of the Koopman operator can be used to analyze quantum physics problems. Moreover,
    we exploit the relationship between Schrödinger operators and stochastic control
    problems to show that modern data-driven methods for stochastic control can be
    used to solve the stationary or imaginary-time Schrödinger equation. Our findings
    open up a new avenue towards solving Schrödinger's equation using recently developed
    tools from data science.
author:
- first_name: Stefan
  full_name: Klus, Stefan
  last_name: Klus
- first_name: Feliks
  full_name: Nüske, Feliks
  id: '81513'
  last_name: Nüske
  orcid: 0000-0003-2444-7889
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: 'Klus S, Nüske F, Peitz S. Koopman analysis of quantum systems. <i>Journal
    of Physics A: Mathematical and Theoretical</i>. 2022;55(31):314002. doi:<a href="https://doi.org/10.1088/1751-8121/ac7d22">10.1088/1751-8121/ac7d22</a>'
  apa: 'Klus, S., Nüske, F., &#38; Peitz, S. (2022). Koopman analysis of quantum systems.
    <i>Journal of Physics A: Mathematical and Theoretical</i>, <i>55</i>(31), 314002.
    <a href="https://doi.org/10.1088/1751-8121/ac7d22">https://doi.org/10.1088/1751-8121/ac7d22</a>'
  bibtex: '@article{Klus_Nüske_Peitz_2022, title={Koopman analysis of quantum systems},
    volume={55}, DOI={<a href="https://doi.org/10.1088/1751-8121/ac7d22">10.1088/1751-8121/ac7d22</a>},
    number={31}, journal={Journal of Physics A: Mathematical and Theoretical}, publisher={IOP
    Publishing Ltd.}, author={Klus, Stefan and Nüske, Feliks and Peitz, Sebastian},
    year={2022}, pages={314002} }'
  chicago: 'Klus, Stefan, Feliks Nüske, and Sebastian Peitz. “Koopman Analysis of
    Quantum Systems.” <i>Journal of Physics A: Mathematical and Theoretical</i> 55,
    no. 31 (2022): 314002. <a href="https://doi.org/10.1088/1751-8121/ac7d22">https://doi.org/10.1088/1751-8121/ac7d22</a>.'
  ieee: 'S. Klus, F. Nüske, and S. Peitz, “Koopman analysis of quantum systems,” <i>Journal
    of Physics A: Mathematical and Theoretical</i>, vol. 55, no. 31, p. 314002, 2022,
    doi: <a href="https://doi.org/10.1088/1751-8121/ac7d22">10.1088/1751-8121/ac7d22</a>.'
  mla: 'Klus, Stefan, et al. “Koopman Analysis of Quantum Systems.” <i>Journal of
    Physics A: Mathematical and Theoretical</i>, vol. 55, no. 31, IOP Publishing Ltd.,
    2022, p. 314002, doi:<a href="https://doi.org/10.1088/1751-8121/ac7d22">10.1088/1751-8121/ac7d22</a>.'
  short: 'S. Klus, F. Nüske, S. Peitz, Journal of Physics A: Mathematical and Theoretical
    55 (2022) 314002.'
date_created: 2022-01-31T09:49:40Z
date_updated: 2022-07-18T14:26:41Z
department:
- _id: '655'
- _id: '101'
doi: 10.1088/1751-8121/ac7d22
external_id:
  arxiv:
  - '2201.12062'
intvolume: '        55'
issue: '31'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://iopscience.iop.org/article/10.1088/1751-8121/ac7d22/pdf
oa: '1'
page: '314002'
publication: 'Journal of Physics A: Mathematical and Theoretical'
publication_status: published
publisher: IOP Publishing Ltd.
status: public
title: Koopman analysis of quantum systems
type: journal_article
user_id: '47427'
volume: 55
year: '2022'
...
---
_id: '33150'
abstract:
- lang: eng
  text: In this article, we build on previous work to present an optimization algorithm
    for nonlinearly constrained multi-objective optimization problems. The algorithm
    combines a surrogate-assisted derivative-free trust-region approach with the filter
    method known from single-objective optimization. Instead of the true objective
    and constraint functions, so-called fully linear models are employed and we show
    how to deal with the gradient inexactness in the composite step setting, adapted
    from single-objective optimization as well. Under standard assumptions, we prove
    convergence of a subset of iterates to a quasi-stationary point and if constraint
    qualifications hold, then the limit point is also a KKT-point of the multi-objective
    problem.
author:
- first_name: Manuel Bastian
  full_name: Berkemeier, Manuel Bastian
  id: '51701'
  last_name: Berkemeier
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Berkemeier MB, Peitz S. Multi-Objective Trust-Region Filter Method for Nonlinear
    Constraints using Inexact Gradients. <i>arXiv:220812094</i>. Published online
    2022.
  apa: Berkemeier, M. B., &#38; Peitz, S. (2022). Multi-Objective Trust-Region Filter
    Method for Nonlinear Constraints using Inexact Gradients. In <i>arXiv:2208.12094</i>.
  bibtex: '@article{Berkemeier_Peitz_2022, title={Multi-Objective Trust-Region Filter
    Method for Nonlinear Constraints using Inexact Gradients}, journal={arXiv:2208.12094},
    author={Berkemeier, Manuel Bastian and Peitz, Sebastian}, year={2022} }'
  chicago: Berkemeier, Manuel Bastian, and Sebastian Peitz. “Multi-Objective Trust-Region
    Filter Method for Nonlinear Constraints Using Inexact Gradients.” <i>ArXiv:2208.12094</i>,
    2022.
  ieee: M. B. Berkemeier and S. Peitz, “Multi-Objective Trust-Region Filter Method
    for Nonlinear Constraints using Inexact Gradients,” <i>arXiv:2208.12094</i>. 2022.
  mla: Berkemeier, Manuel Bastian, and Sebastian Peitz. “Multi-Objective Trust-Region
    Filter Method for Nonlinear Constraints Using Inexact Gradients.” <i>ArXiv:2208.12094</i>,
    2022.
  short: M.B. Berkemeier, S. Peitz, ArXiv:2208.12094 (2022).
date_created: 2022-08-26T06:08:06Z
date_updated: 2022-08-26T06:12:10Z
department:
- _id: '101'
- _id: '655'
external_id:
  arxiv:
  - '2208.12094'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/pdf/2208.12094
oa: '1'
publication: arXiv:2208.12094
status: public
title: Multi-Objective Trust-Region Filter Method for Nonlinear Constraints using
  Inexact Gradients
type: preprint
user_id: '47427'
year: '2022'
...
---
_id: '20731'
abstract:
- lang: eng
  text: We present a novel algorithm that allows us to gain detailed insight into
    the effects of sparsity in linear and nonlinear optimization, which is of great
    importance in many scientific areas such as image and signal processing, medical
    imaging, compressed sensing, and machine learning (e.g., for the training of neural
    networks). Sparsity is an important feature to ensure robustness against noisy
    data, but also to find models that are interpretable and easy to analyze due to
    the small number of relevant terms. It is common practice to enforce sparsity
    by adding the ℓ1-norm as a weighted penalty term. In order to gain a better understanding
    and to allow for an informed model selection, we directly solve the corresponding
    multiobjective optimization problem (MOP) that arises when we minimize the main
    objective and the ℓ1-norm simultaneously. As this MOP is in general non-convex
    for nonlinear objectives, the weighting method will fail to provide all optimal
    compromises. To avoid this issue, we present a continuation method which is specifically
    tailored to MOPs with two objective functions one of which is the ℓ1-norm. Our
    method can be seen as a generalization of well-known homotopy methods for linear
    regression problems to the nonlinear case. Several numerical examples - including
    neural network training - demonstrate our theoretical findings and the additional
    insight that can be gained by this multiobjective approach.
article_type: original
author:
- first_name: Katharina
  full_name: Bieker, Katharina
  id: '32829'
  last_name: Bieker
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Bieker K, Gebken B, Peitz S. On the Treatment of Optimization Problems with
    L1 Penalty Terms via Multiobjective Continuation. <i>IEEE Transactions on Pattern
    Analysis and Machine Intelligence</i>. 2022;44(11):7797-7808. doi:<a href="https://doi.org/10.1109/TPAMI.2021.3114962">10.1109/TPAMI.2021.3114962</a>
  apa: Bieker, K., Gebken, B., &#38; Peitz, S. (2022). On the Treatment of Optimization
    Problems with L1 Penalty Terms via Multiobjective Continuation. <i>IEEE Transactions
    on Pattern Analysis and Machine Intelligence</i>, <i>44</i>(11), 7797–7808. <a
    href="https://doi.org/10.1109/TPAMI.2021.3114962">https://doi.org/10.1109/TPAMI.2021.3114962</a>
  bibtex: '@article{Bieker_Gebken_Peitz_2022, title={On the Treatment of Optimization
    Problems with L1 Penalty Terms via Multiobjective Continuation}, volume={44},
    DOI={<a href="https://doi.org/10.1109/TPAMI.2021.3114962">10.1109/TPAMI.2021.3114962</a>},
    number={11}, journal={IEEE Transactions on Pattern Analysis and Machine Intelligence},
    publisher={IEEE}, author={Bieker, Katharina and Gebken, Bennet and Peitz, Sebastian},
    year={2022}, pages={7797–7808} }'
  chicago: 'Bieker, Katharina, Bennet Gebken, and Sebastian Peitz. “On the Treatment
    of Optimization Problems with L1 Penalty Terms via Multiobjective Continuation.”
    <i>IEEE Transactions on Pattern Analysis and Machine Intelligence</i> 44, no.
    11 (2022): 7797–7808. <a href="https://doi.org/10.1109/TPAMI.2021.3114962">https://doi.org/10.1109/TPAMI.2021.3114962</a>.'
  ieee: 'K. Bieker, B. Gebken, and S. Peitz, “On the Treatment of Optimization Problems
    with L1 Penalty Terms via Multiobjective Continuation,” <i>IEEE Transactions on
    Pattern Analysis and Machine Intelligence</i>, vol. 44, no. 11, pp. 7797–7808,
    2022, doi: <a href="https://doi.org/10.1109/TPAMI.2021.3114962">10.1109/TPAMI.2021.3114962</a>.'
  mla: Bieker, Katharina, et al. “On the Treatment of Optimization Problems with L1
    Penalty Terms via Multiobjective Continuation.” <i>IEEE Transactions on Pattern
    Analysis and Machine Intelligence</i>, vol. 44, no. 11, IEEE, 2022, pp. 7797–808,
    doi:<a href="https://doi.org/10.1109/TPAMI.2021.3114962">10.1109/TPAMI.2021.3114962</a>.
  short: K. Bieker, B. Gebken, S. Peitz, IEEE Transactions on Pattern Analysis and
    Machine Intelligence 44 (2022) 7797–7808.
date_created: 2020-12-15T07:46:36Z
date_updated: 2022-10-21T12:27:16Z
ddc:
- '510'
department:
- _id: '101'
- _id: '530'
- _id: '655'
doi: 10.1109/TPAMI.2021.3114962
file:
- access_level: closed
  content_type: application/pdf
  creator: speitz
  date_created: 2021-09-25T11:59:15Z
  date_updated: 2021-09-25T11:59:15Z
  file_id: '25040'
  file_name: On_the_Treatment_of_Optimization_Problems_with_L1_Penalty_Terms_via_Multiobjective_Continuation.pdf
  file_size: 7990831
  relation: main_file
  success: 1
file_date_updated: 2021-09-25T11:59:15Z
has_accepted_license: '1'
intvolume: '        44'
issue: '11'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9547772
oa: '1'
page: 7797-7808
publication: IEEE Transactions on Pattern Analysis and Machine Intelligence
publication_status: epub_ahead
publisher: IEEE
status: public
title: On the Treatment of Optimization Problems with L1 Penalty Terms via Multiobjective
  Continuation
type: journal_article
user_id: '47427'
volume: 44
year: '2022'
...
---
_id: '29727'
author:
- first_name: Meike Claudia
  full_name: Wohlleben, Meike Claudia
  id: '43991'
  last_name: Wohlleben
- first_name: Amelie
  full_name: Bender, Amelie
  id: '54290'
  last_name: Bender
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Walter
  full_name: Sextro, Walter
  id: '21220'
  last_name: Sextro
citation:
  ama: 'Wohlleben MC, Bender A, Peitz S, Sextro W. Development of a Hybrid Modeling
    Methodology for Oscillating Systems with Friction. In: <i>Machine Learning, Optimization,
    and Data Science</i>. Springer International Publishing; 2022. doi:<a href="https://doi.org/10.1007/978-3-030-95470-3_8">10.1007/978-3-030-95470-3_8</a>'
  apa: Wohlleben, M. C., Bender, A., Peitz, S., &#38; Sextro, W. (2022). Development
    of a Hybrid Modeling Methodology for Oscillating Systems with Friction. In <i>Machine
    Learning, Optimization, and Data Science</i>. Springer International Publishing.
    <a href="https://doi.org/10.1007/978-3-030-95470-3_8">https://doi.org/10.1007/978-3-030-95470-3_8</a>
  bibtex: '@inbook{Wohlleben_Bender_Peitz_Sextro_2022, place={Cham}, title={Development
    of a Hybrid Modeling Methodology for Oscillating Systems with Friction}, DOI={<a
    href="https://doi.org/10.1007/978-3-030-95470-3_8">10.1007/978-3-030-95470-3_8</a>},
    booktitle={Machine Learning, Optimization, and Data Science}, publisher={Springer
    International Publishing}, author={Wohlleben, Meike Claudia and Bender, Amelie
    and Peitz, Sebastian and Sextro, Walter}, year={2022} }'
  chicago: 'Wohlleben, Meike Claudia, Amelie Bender, Sebastian Peitz, and Walter Sextro.
    “Development of a Hybrid Modeling Methodology for Oscillating Systems with Friction.”
    In <i>Machine Learning, Optimization, and Data Science</i>. Cham: Springer International
    Publishing, 2022. <a href="https://doi.org/10.1007/978-3-030-95470-3_8">https://doi.org/10.1007/978-3-030-95470-3_8</a>.'
  ieee: 'M. C. Wohlleben, A. Bender, S. Peitz, and W. Sextro, “Development of a Hybrid
    Modeling Methodology for Oscillating Systems with Friction,” in <i>Machine Learning,
    Optimization, and Data Science</i>, Cham: Springer International Publishing, 2022.'
  mla: Wohlleben, Meike Claudia, et al. “Development of a Hybrid Modeling Methodology
    for Oscillating Systems with Friction.” <i>Machine Learning, Optimization, and
    Data Science</i>, Springer International Publishing, 2022, doi:<a href="https://doi.org/10.1007/978-3-030-95470-3_8">10.1007/978-3-030-95470-3_8</a>.
  short: 'M.C. Wohlleben, A. Bender, S. Peitz, W. Sextro, in: Machine Learning, Optimization,
    and Data Science, Springer International Publishing, Cham, 2022.'
date_created: 2022-02-03T10:30:23Z
date_updated: 2023-04-26T12:10:58Z
department:
- _id: '151'
- _id: '655'
doi: 10.1007/978-3-030-95470-3_8
language:
- iso: eng
main_file_link:
- url: https://link.springer.com/content/pdf/10.1007%2F978-3-030-95470-3_8.pdf
place: Cham
publication: Machine Learning, Optimization, and Data Science
publication_identifier:
  isbn:
  - '9783030954697'
  - '9783030954703'
  issn:
  - 0302-9743
  - 1611-3349
publication_status: published
publisher: Springer International Publishing
quality_controlled: '1'
status: public
title: Development of a Hybrid Modeling Methodology for Oscillating Systems with Friction
type: book_chapter
user_id: '43991'
year: '2022'
...
---
_id: '21337'
abstract:
- lang: eng
  text: "We present a flexible trust region descend algorithm for unconstrained and\r\nconvexly
    constrained multiobjective optimization problems. It is targeted at\r\nheterogeneous
    and expensive problems, i.e., problems that have at least one\r\nobjective function
    that is computationally expensive. The method is\r\nderivative-free in the sense
    that neither need derivative information be\r\navailable for the expensive objectives
    nor are gradients approximated using\r\nrepeated function evaluations as is the
    case in finite-difference methods.\r\nInstead, a multiobjective trust region approach
    is used that works similarly to\r\nits well-known scalar pendants. Local surrogate
    models constructed from\r\nevaluation data of the true objective functions are
    employed to compute\r\npossible descent directions. In contrast to existing multiobjective
    trust\r\nregion algorithms, these surrogates are not polynomial but carefully\r\nconstructed
    radial basis function networks. This has the important advantage\r\nthat the number
    of data points scales linearly with the parameter space\r\ndimension. The local
    models qualify as fully linear and the corresponding\r\ngeneral scalar framework
    is adapted for problems with multiple objectives.\r\nConvergence to Pareto critical
    points is proven and numerical examples\r\nillustrate our findings."
article_number: '31'
author:
- first_name: Manuel Bastian
  full_name: Berkemeier, Manuel Bastian
  id: '51701'
  last_name: Berkemeier
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Berkemeier MB, Peitz S. Derivative-Free Multiobjective Trust Region Descent
    Method Using Radial  Basis Function Surrogate Models. <i>Mathematical and Computational
    Applications</i>. 2021;26(2). doi:<a href="https://doi.org/10.3390/mca26020031">10.3390/mca26020031</a>
  apa: Berkemeier, M. B., &#38; Peitz, S. (2021). Derivative-Free Multiobjective Trust
    Region Descent Method Using Radial  Basis Function Surrogate Models. <i>Mathematical
    and Computational Applications</i>, <i>26</i>(2). <a href="https://doi.org/10.3390/mca26020031">https://doi.org/10.3390/mca26020031</a>
  bibtex: '@article{Berkemeier_Peitz_2021, title={Derivative-Free Multiobjective Trust
    Region Descent Method Using Radial  Basis Function Surrogate Models}, volume={26},
    DOI={<a href="https://doi.org/10.3390/mca26020031">10.3390/mca26020031</a>}, number={231},
    journal={Mathematical and Computational Applications}, author={Berkemeier, Manuel
    Bastian and Peitz, Sebastian}, year={2021} }'
  chicago: Berkemeier, Manuel Bastian, and Sebastian Peitz. “Derivative-Free Multiobjective
    Trust Region Descent Method Using Radial  Basis Function Surrogate Models.” <i>Mathematical
    and Computational Applications</i> 26, no. 2 (2021). <a href="https://doi.org/10.3390/mca26020031">https://doi.org/10.3390/mca26020031</a>.
  ieee: M. B. Berkemeier and S. Peitz, “Derivative-Free Multiobjective Trust Region
    Descent Method Using Radial  Basis Function Surrogate Models,” <i>Mathematical
    and Computational Applications</i>, vol. 26, no. 2, 2021.
  mla: Berkemeier, Manuel Bastian, and Sebastian Peitz. “Derivative-Free Multiobjective
    Trust Region Descent Method Using Radial  Basis Function Surrogate Models.” <i>Mathematical
    and Computational Applications</i>, vol. 26, no. 2, 31, 2021, doi:<a href="https://doi.org/10.3390/mca26020031">10.3390/mca26020031</a>.
  short: M.B. Berkemeier, S. Peitz, Mathematical and Computational Applications 26
    (2021).
date_created: 2021-03-01T10:46:48Z
date_updated: 2022-01-06T06:54:55Z
department:
- _id: '101'
- _id: '655'
doi: 10.3390/mca26020031
intvolume: '        26'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.mdpi.com/2297-8747/26/2/31/pdf
oa: '1'
publication: Mathematical and Computational Applications
publication_identifier:
  eissn:
  - 2297-8747
publication_status: published
status: public
title: Derivative-Free Multiobjective Trust Region Descent Method Using Radial  Basis
  Function Surrogate Models
type: journal_article
user_id: '47427'
volume: 26
year: '2021'
...
---
_id: '16867'
abstract:
- lang: eng
  text: "In this article, we present an efficient descent method for locally Lipschitz\r\ncontinuous
    multiobjective optimization problems (MOPs). The method is realized\r\nby combining
    a theoretical result regarding the computation of descent\r\ndirections for nonsmooth
    MOPs with a practical method to approximate the\r\nsubdifferentials of the objective
    functions. We show convergence to points\r\nwhich satisfy a necessary condition
    for Pareto optimality. Using a set of test\r\nproblems, we compare our method
    to the multiobjective proximal bundle method by\r\nM\\\"akel\\\"a. The results
    indicate that our method is competitive while being\r\neasier to implement. While
    the number of objective function evaluations is\r\nlarger, the overall number
    of subgradient evaluations is lower. Finally, we\r\nshow that our method can be
    combined with a subdivision algorithm to compute\r\nentire Pareto sets of nonsmooth
    MOPs."
author:
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Gebken B, Peitz S. An efficient descent method for locally Lipschitz multiobjective
    optimization problems. <i>Journal of Optimization Theory and Applications</i>.
    2021;188:696-723. doi:<a href="https://doi.org/10.1007/s10957-020-01803-w">10.1007/s10957-020-01803-w</a>
  apa: Gebken, B., &#38; Peitz, S. (2021). An efficient descent method for locally
    Lipschitz multiobjective optimization problems. <i>Journal of Optimization Theory
    and Applications</i>, <i>188</i>, 696–723. <a href="https://doi.org/10.1007/s10957-020-01803-w">https://doi.org/10.1007/s10957-020-01803-w</a>
  bibtex: '@article{Gebken_Peitz_2021, title={An efficient descent method for locally
    Lipschitz multiobjective optimization problems}, volume={188}, DOI={<a href="https://doi.org/10.1007/s10957-020-01803-w">10.1007/s10957-020-01803-w</a>},
    journal={Journal of Optimization Theory and Applications}, author={Gebken, Bennet
    and Peitz, Sebastian}, year={2021}, pages={696–723} }'
  chicago: 'Gebken, Bennet, and Sebastian Peitz. “An Efficient Descent Method for
    Locally Lipschitz Multiobjective Optimization Problems.” <i>Journal of Optimization
    Theory and Applications</i> 188 (2021): 696–723. <a href="https://doi.org/10.1007/s10957-020-01803-w">https://doi.org/10.1007/s10957-020-01803-w</a>.'
  ieee: B. Gebken and S. Peitz, “An efficient descent method for locally Lipschitz
    multiobjective optimization problems,” <i>Journal of Optimization Theory and Applications</i>,
    vol. 188, pp. 696–723, 2021.
  mla: Gebken, Bennet, and Sebastian Peitz. “An Efficient Descent Method for Locally
    Lipschitz Multiobjective Optimization Problems.” <i>Journal of Optimization Theory
    and Applications</i>, vol. 188, 2021, pp. 696–723, doi:<a href="https://doi.org/10.1007/s10957-020-01803-w">10.1007/s10957-020-01803-w</a>.
  short: B. Gebken, S. Peitz, Journal of Optimization Theory and Applications 188
    (2021) 696–723.
date_created: 2020-04-27T09:11:22Z
date_updated: 2022-01-06T06:52:57Z
department:
- _id: '101'
doi: 10.1007/s10957-020-01803-w
intvolume: '       188'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s10957-020-01803-w.pdf
oa: '1'
page: 696-723
publication: Journal of Optimization Theory and Applications
publication_status: published
status: public
title: An efficient descent method for locally Lipschitz multiobjective optimization
  problems
type: journal_article
user_id: '47427'
volume: 188
year: '2021'
...
---
_id: '16295'
abstract:
- lang: eng
  text: It is a challenging task to identify the objectives on which a certain decision
    was based, in particular if several, potentially conflicting criteria are equally
    important and a continuous set of optimal compromise decisions exists. This task
    can be understood as the inverse problem of multiobjective optimization, where
    the goal is to find the objective function vector of a given Pareto set. To this
    end, we present a method to construct the objective function vector of an unconstrained
    multiobjective optimization problem (MOP) such that the Pareto critical set contains
    a given set of data points with prescribed KKT multipliers. If such an MOP can
    not be found, then the method instead produces an MOP whose Pareto critical set
    is at least close to the data points. The key idea is to consider the objective
    function vector in the multiobjective KKT conditions as variable and then search
    for the objectives that minimize the Euclidean norm of the resulting system of
    equations. By expressing the objectives in a finite-dimensional basis, we transform
    this problem into a homogeneous, linear system of equations that can be solved
    efficiently. Potential applications of this approach include the identification
    of objectives (both from clean and noisy data) and the construction of surrogate
    models for expensive MOPs.
author:
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: https://orcid.org/0000-0002-3389-793X
citation:
  ama: 'Gebken B, Peitz S. Inverse multiobjective optimization: Inferring decision
    criteria from data. <i>Journal of Global Optimization</i>. 2021;80:3-29. doi:<a
    href="https://doi.org/10.1007/s10898-020-00983-z">10.1007/s10898-020-00983-z</a>'
  apa: 'Gebken, B., &#38; Peitz, S. (2021). Inverse multiobjective optimization: Inferring
    decision criteria from data. <i>Journal of Global Optimization</i>, <i>80</i>,
    3–29. <a href="https://doi.org/10.1007/s10898-020-00983-z">https://doi.org/10.1007/s10898-020-00983-z</a>'
  bibtex: '@article{Gebken_Peitz_2021, title={Inverse multiobjective optimization:
    Inferring decision criteria from data}, volume={80}, DOI={<a href="https://doi.org/10.1007/s10898-020-00983-z">10.1007/s10898-020-00983-z</a>},
    journal={Journal of Global Optimization}, publisher={Springer}, author={Gebken,
    Bennet and Peitz, Sebastian}, year={2021}, pages={3–29} }'
  chicago: 'Gebken, Bennet, and Sebastian Peitz. “Inverse Multiobjective Optimization:
    Inferring Decision Criteria from Data.” <i>Journal of Global Optimization</i>
    80 (2021): 3–29. <a href="https://doi.org/10.1007/s10898-020-00983-z">https://doi.org/10.1007/s10898-020-00983-z</a>.'
  ieee: 'B. Gebken and S. Peitz, “Inverse multiobjective optimization: Inferring decision
    criteria from data,” <i>Journal of Global Optimization</i>, vol. 80, pp. 3–29,
    2021.'
  mla: 'Gebken, Bennet, and Sebastian Peitz. “Inverse Multiobjective Optimization:
    Inferring Decision Criteria from Data.” <i>Journal of Global Optimization</i>,
    vol. 80, Springer, 2021, pp. 3–29, doi:<a href="https://doi.org/10.1007/s10898-020-00983-z">10.1007/s10898-020-00983-z</a>.'
  short: B. Gebken, S. Peitz, Journal of Global Optimization 80 (2021) 3–29.
date_created: 2020-03-13T12:45:05Z
date_updated: 2022-01-06T06:52:48Z
department:
- _id: '101'
doi: 10.1007/s10898-020-00983-z
intvolume: '        80'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s10898-020-00983-z.pdf
oa: '1'
page: 3-29
publication: Journal of Global Optimization
publisher: Springer
status: public
title: 'Inverse multiobjective optimization: Inferring decision criteria from data'
type: journal_article
user_id: '47427'
volume: 80
year: '2021'
...
---
_id: '16294'
abstract:
- lang: eng
  text: "Model predictive control is a prominent approach to construct a feedback\r\ncontrol
    loop for dynamical systems. Due to real-time constraints, the major\r\nchallenge
    in MPC is to solve model-based optimal control problems in a very\r\nshort amount
    of time. For linear-quadratic problems, Bemporad et al. have\r\nproposed an explicit
    formulation where the underlying optimization problems are\r\nsolved a priori
    in an offline phase. In this article, we present an extension\r\nof this concept
    in two significant ways. We consider nonlinear problems and -\r\nmore importantly
    - problems with multiple conflicting objective functions. In\r\nthe offline phase,
    we build a library of Pareto optimal solutions from which we\r\nthen obtain a
    valid compromise solution in the online phase according to a\r\ndecision maker's
    preference. Since the standard multi-parametric programming\r\napproach is no
    longer valid in this situation, we instead use interpolation\r\nbetween different
    entries of the library. To reduce the number of problems that\r\nhave to be solved
    in the offline phase, we exploit symmetries in the dynamical\r\nsystem and the
    corresponding multiobjective optimal control problem. The\r\nresults are verified
    using two different examples from autonomous driving."
author:
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: https://orcid.org/0000-0002-3389-793X
citation:
  ama: Ober-Blöbaum S, Peitz S. Explicit multiobjective model predictive control for
    nonlinear systems  with symmetries. <i>International Journal of Robust and Nonlinear
    Control</i>. 2021;31(2):380-403. doi:<a href="https://doi.org/10.1002/rnc.5281">10.1002/rnc.5281</a>
  apa: Ober-Blöbaum, S., &#38; Peitz, S. (2021). Explicit multiobjective model predictive
    control for nonlinear systems  with symmetries. <i>International Journal of Robust
    and Nonlinear Control</i>, <i>31(2)</i>, 380–403. <a href="https://doi.org/10.1002/rnc.5281">https://doi.org/10.1002/rnc.5281</a>
  bibtex: '@article{Ober-Blöbaum_Peitz_2021, title={Explicit multiobjective model
    predictive control for nonlinear systems  with symmetries}, volume={31(2)}, DOI={<a
    href="https://doi.org/10.1002/rnc.5281">10.1002/rnc.5281</a>}, journal={International
    Journal of Robust and Nonlinear Control}, author={Ober-Blöbaum, Sina and Peitz,
    Sebastian}, year={2021}, pages={380–403} }'
  chicago: 'Ober-Blöbaum, Sina, and Sebastian Peitz. “Explicit Multiobjective Model
    Predictive Control for Nonlinear Systems  with Symmetries.” <i>International Journal
    of Robust and Nonlinear Control</i> 31(2) (2021): 380–403. <a href="https://doi.org/10.1002/rnc.5281">https://doi.org/10.1002/rnc.5281</a>.'
  ieee: 'S. Ober-Blöbaum and S. Peitz, “Explicit multiobjective model predictive control
    for nonlinear systems  with symmetries,” <i>International Journal of Robust and
    Nonlinear Control</i>, vol. 31(2), pp. 380–403, 2021, doi: <a href="https://doi.org/10.1002/rnc.5281">10.1002/rnc.5281</a>.'
  mla: Ober-Blöbaum, Sina, and Sebastian Peitz. “Explicit Multiobjective Model Predictive
    Control for Nonlinear Systems  with Symmetries.” <i>International Journal of Robust
    and Nonlinear Control</i>, vol. 31(2), 2021, pp. 380–403, doi:<a href="https://doi.org/10.1002/rnc.5281">10.1002/rnc.5281</a>.
  short: S. Ober-Blöbaum, S. Peitz, International Journal of Robust and Nonlinear
    Control 31(2) (2021) 380–403.
date_created: 2020-03-13T12:44:36Z
date_updated: 2022-01-24T13:27:50Z
department:
- _id: '101'
doi: 10.1002/rnc.5281
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://onlinelibrary.wiley.com/doi/epdf/10.1002/rnc.5281
oa: '1'
page: 380-403
project:
- _id: '52'
  name: Computing Resources Provided by the Paderborn Center for Parallel Computing
publication: International Journal of Robust and Nonlinear Control
status: public
title: Explicit multiobjective model predictive control for nonlinear systems  with
  symmetries
type: journal_article
user_id: '15694'
volume: 31(2)
year: '2021'
...
---
_id: '17411'
abstract:
- lang: eng
  text: Many dynamical systems possess symmetries, e.g. rotational and translational
    invariances of mechanical systems. These can be beneficially exploited in the
    design of numerical optimal control methods. We present a model predictive control
    scheme which is based on a library of precomputed motion primitives. The primitives
    are equivalence classes w.r.t. the symmetry of the optimal control problems. Trim
    primitives as relative equilibria w.r.t. this symmetry, play a crucial role in
    the algorithm. The approach is illustrated using an academic mobile robot example.
author:
- first_name: Kathrin
  full_name: Flaßkamp, Kathrin
  last_name: Flaßkamp
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  last_name: Ober-Blöbaum
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: 'Flaßkamp K, Ober-Blöbaum S, Peitz S. Symmetry in Optimal Control: A Multiobjective
    Model Predictive Control Approach. In: Junge O, Schütze O, Froyland G, Ober-Blöbaum
    S, Padberg-Gehle K, eds. <i>Advances in Dynamics, Optimization and Computation</i>.
    Cham: Springer; 2020. doi:<a href="https://doi.org/10.1007/978-3-030-51264-4_9">10.1007/978-3-030-51264-4_9</a>'
  apa: 'Flaßkamp, K., Ober-Blöbaum, S., &#38; Peitz, S. (2020). Symmetry in Optimal
    Control: A Multiobjective Model Predictive Control Approach. In O. Junge, O. Schütze,
    G. Froyland, S. Ober-Blöbaum, &#38; K. Padberg-Gehle (Eds.), <i>Advances in Dynamics,
    Optimization and Computation</i>. Cham: Springer. <a href="https://doi.org/10.1007/978-3-030-51264-4_9">https://doi.org/10.1007/978-3-030-51264-4_9</a>'
  bibtex: '@inbook{Flaßkamp_Ober-Blöbaum_Peitz_2020, place={Cham}, title={Symmetry
    in Optimal Control: A Multiobjective Model Predictive Control Approach}, DOI={<a
    href="https://doi.org/10.1007/978-3-030-51264-4_9">10.1007/978-3-030-51264-4_9</a>},
    booktitle={Advances in Dynamics, Optimization and Computation}, publisher={Springer},
    author={Flaßkamp, Kathrin and Ober-Blöbaum, Sina and Peitz, Sebastian}, editor={Junge,
    Oliver and Schütze, Oliver and Froyland, Gary and Ober-Blöbaum, Sina and Padberg-Gehle,
    KathrinEditors}, year={2020} }'
  chicago: 'Flaßkamp, Kathrin, Sina Ober-Blöbaum, and Sebastian Peitz. “Symmetry in
    Optimal Control: A Multiobjective Model Predictive Control Approach.” In <i>Advances
    in Dynamics, Optimization and Computation</i>, edited by Oliver Junge, Oliver
    Schütze, Gary Froyland, Sina Ober-Blöbaum, and Kathrin Padberg-Gehle. Cham: Springer,
    2020. <a href="https://doi.org/10.1007/978-3-030-51264-4_9">https://doi.org/10.1007/978-3-030-51264-4_9</a>.'
  ieee: 'K. Flaßkamp, S. Ober-Blöbaum, and S. Peitz, “Symmetry in Optimal Control:
    A Multiobjective Model Predictive Control Approach,” in <i>Advances in Dynamics,
    Optimization and Computation</i>, O. Junge, O. Schütze, G. Froyland, S. Ober-Blöbaum,
    and K. Padberg-Gehle, Eds. Cham: Springer, 2020.'
  mla: 'Flaßkamp, Kathrin, et al. “Symmetry in Optimal Control: A Multiobjective Model
    Predictive Control Approach.” <i>Advances in Dynamics, Optimization and Computation</i>,
    edited by Oliver Junge et al., Springer, 2020, doi:<a href="https://doi.org/10.1007/978-3-030-51264-4_9">10.1007/978-3-030-51264-4_9</a>.'
  short: 'K. Flaßkamp, S. Ober-Blöbaum, S. Peitz, in: O. Junge, O. Schütze, G. Froyland,
    S. Ober-Blöbaum, K. Padberg-Gehle (Eds.), Advances in Dynamics, Optimization and
    Computation, Springer, Cham, 2020.'
date_created: 2020-07-27T09:50:19Z
date_updated: 2022-01-06T06:53:11Z
department:
- _id: '101'
doi: 10.1007/978-3-030-51264-4_9
editor:
- first_name: Oliver
  full_name: Junge, Oliver
  last_name: Junge
- first_name: Oliver
  full_name: Schütze, Oliver
  last_name: Schütze
- first_name: Gary
  full_name: Froyland, Gary
  last_name: Froyland
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  last_name: Ober-Blöbaum
- first_name: Kathrin
  full_name: Padberg-Gehle, Kathrin
  last_name: Padberg-Gehle
language:
- iso: eng
place: Cham
publication: Advances in Dynamics, Optimization and Computation
publication_identifier:
  isbn:
  - '9783030512637'
  - '9783030512644'
  issn:
  - 2198-4182
  - 2198-4190
publication_status: published
publisher: Springer
status: public
title: 'Symmetry in Optimal Control: A Multiobjective Model Predictive Control Approach'
type: book_chapter
user_id: '47427'
year: '2020'
...
---
_id: '10596'
abstract:
- lang: eng
  text: Multi-objective optimization is an active field of research that has many
    applications. Owing to its success and because decision-making processes are becoming
    more and more complex, there is a recent trend for incorporating many objectives
    into such problems. The challenge with such problems, however, is that the dimensions
    of the solution sets—the so-called Pareto sets and fronts—grow with the number
    of objectives. It is thus no longer possible to compute or to approximate the
    entire solution set of a given problem that contains many (e.g. more than three)
    objectives. On the other hand, the computation of single solutions (e.g. via scalarization
    methods) leads to unsatisfying results in many cases, even if user preferences
    are incorporated. In this article, the Pareto Explorer tool is presented—a global/local
    exploration tool for the treatment of many-objective optimization problems (MaOPs).
    In the first step, a solution of the problem is computed via a global search algorithm
    that ideally already includes user preferences. In the second step, a local search
    along the Pareto set/front of the given MaOP is performed in user specified directions.
    For this, several continuation-like procedures are proposed that can incorporate
    preferences defined in decision, objective, or in weight space. The applicability
    and usefulness of Pareto Explorer is demonstrated on benchmark problems as well
    as on an application from industrial laundry design.
article_type: original
author:
- first_name: Oliver
  full_name: Schütze, Oliver
  last_name: Schütze
- first_name: Oliver
  full_name: Cuate, Oliver
  last_name: Cuate
- first_name: Adanay
  full_name: Martín, Adanay
  last_name: Martín
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: https://orcid.org/0000-0002-3389-793X
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
citation:
  ama: 'Schütze O, Cuate O, Martín A, Peitz S, Dellnitz M. Pareto Explorer: a global/local
    exploration tool for many-objective optimization problems. <i>Engineering Optimization</i>.
    2020;52(5):832-855. doi:<a href="https://doi.org/10.1080/0305215x.2019.1617286">10.1080/0305215x.2019.1617286</a>'
  apa: 'Schütze, O., Cuate, O., Martín, A., Peitz, S., &#38; Dellnitz, M. (2020).
    Pareto Explorer: a global/local exploration tool for many-objective optimization
    problems. <i>Engineering Optimization</i>, <i>52</i>(5), 832–855. <a href="https://doi.org/10.1080/0305215x.2019.1617286">https://doi.org/10.1080/0305215x.2019.1617286</a>'
  bibtex: '@article{Schütze_Cuate_Martín_Peitz_Dellnitz_2020, title={Pareto Explorer:
    a global/local exploration tool for many-objective optimization problems}, volume={52},
    DOI={<a href="https://doi.org/10.1080/0305215x.2019.1617286">10.1080/0305215x.2019.1617286</a>},
    number={5}, journal={Engineering Optimization}, author={Schütze, Oliver and Cuate,
    Oliver and Martín, Adanay and Peitz, Sebastian and Dellnitz, Michael}, year={2020},
    pages={832–855} }'
  chicago: 'Schütze, Oliver, Oliver Cuate, Adanay Martín, Sebastian Peitz, and Michael
    Dellnitz. “Pareto Explorer: A Global/Local Exploration Tool for Many-Objective
    Optimization Problems.” <i>Engineering Optimization</i> 52, no. 5 (2020): 832–55.
    <a href="https://doi.org/10.1080/0305215x.2019.1617286">https://doi.org/10.1080/0305215x.2019.1617286</a>.'
  ieee: 'O. Schütze, O. Cuate, A. Martín, S. Peitz, and M. Dellnitz, “Pareto Explorer:
    a global/local exploration tool for many-objective optimization problems,” <i>Engineering
    Optimization</i>, vol. 52, no. 5, pp. 832–855, 2020.'
  mla: 'Schütze, Oliver, et al. “Pareto Explorer: A Global/Local Exploration Tool
    for Many-Objective Optimization Problems.” <i>Engineering Optimization</i>, vol.
    52, no. 5, 2020, pp. 832–55, doi:<a href="https://doi.org/10.1080/0305215x.2019.1617286">10.1080/0305215x.2019.1617286</a>.'
  short: O. Schütze, O. Cuate, A. Martín, S. Peitz, M. Dellnitz, Engineering Optimization
    52 (2020) 832–855.
date_created: 2019-07-10T08:14:39Z
date_updated: 2022-01-06T06:50:46Z
department:
- _id: '101'
doi: 10.1080/0305215x.2019.1617286
intvolume: '        52'
issue: '5'
language:
- iso: eng
page: 832-855
publication: Engineering Optimization
publication_identifier:
  issn:
  - 0305-215X
  - 1029-0273
publication_status: published
status: public
title: 'Pareto Explorer: a global/local exploration tool for many-objective optimization
  problems'
type: journal_article
user_id: '47427'
volume: 52
year: '2020'
...
---
_id: '16288'
abstract:
- lang: eng
  text: We derive a data-driven method for the approximation of the Koopman generator
    called gEDMD, which can be regarded as a straightforward extension of EDMD (extended
    dynamic mode decomposition). This approach is applicable to deterministic and
    stochastic dynamical systems. It can be used for computing eigenvalues, eigenfunctions,
    and modes of the generator and for system identification. In addition to learning
    the governing equations of deterministic systems, which then reduces to SINDy
    (sparse identification of nonlinear dynamics), it is possible to identify the
    drift and diffusion terms of stochastic differential equations from data. Moreover,
    we apply gEDMD to derive coarse-grained models of high-dimensional systems, and
    also to determine efficient model predictive control strategies. We highlight
    relationships with other methods and demonstrate the efficacy of the proposed
    methods using several guiding examples and prototypical molecular dynamics problems.
article_number: '132416'
author:
- first_name: Stefan
  full_name: Klus, Stefan
  last_name: Klus
- first_name: Feliks
  full_name: Nüske, Feliks
  id: '81513'
  last_name: Nüske
  orcid: 0000-0003-2444-7889
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: https://orcid.org/0000-0002-3389-793X
- first_name: Jan-Hendrik
  full_name: Niemann, Jan-Hendrik
  last_name: Niemann
- first_name: Cecilia
  full_name: Clementi, Cecilia
  last_name: Clementi
- first_name: Christof
  full_name: Schütte, Christof
  last_name: Schütte
citation:
  ama: 'Klus S, Nüske F, Peitz S, Niemann J-H, Clementi C, Schütte C. Data-driven
    approximation of the Koopman generator: Model reduction, system identification,
    and control. <i>Physica D: Nonlinear Phenomena</i>. 2020;406. doi:<a href="https://doi.org/10.1016/j.physd.2020.132416">10.1016/j.physd.2020.132416</a>'
  apa: 'Klus, S., Nüske, F., Peitz, S., Niemann, J.-H., Clementi, C., &#38; Schütte,
    C. (2020). Data-driven approximation of the Koopman generator: Model reduction,
    system identification, and control. <i>Physica D: Nonlinear Phenomena</i>, <i>406</i>.
    <a href="https://doi.org/10.1016/j.physd.2020.132416">https://doi.org/10.1016/j.physd.2020.132416</a>'
  bibtex: '@article{Klus_Nüske_Peitz_Niemann_Clementi_Schütte_2020, title={Data-driven
    approximation of the Koopman generator: Model reduction, system identification,
    and control}, volume={406}, DOI={<a href="https://doi.org/10.1016/j.physd.2020.132416">10.1016/j.physd.2020.132416</a>},
    number={132416}, journal={Physica D: Nonlinear Phenomena}, author={Klus, Stefan
    and Nüske, Feliks and Peitz, Sebastian and Niemann, Jan-Hendrik and Clementi,
    Cecilia and Schütte, Christof}, year={2020} }'
  chicago: 'Klus, Stefan, Feliks Nüske, Sebastian Peitz, Jan-Hendrik Niemann, Cecilia
    Clementi, and Christof Schütte. “Data-Driven Approximation of the Koopman Generator:
    Model Reduction, System Identification, and Control.” <i>Physica D: Nonlinear
    Phenomena</i> 406 (2020). <a href="https://doi.org/10.1016/j.physd.2020.132416">https://doi.org/10.1016/j.physd.2020.132416</a>.'
  ieee: 'S. Klus, F. Nüske, S. Peitz, J.-H. Niemann, C. Clementi, and C. Schütte,
    “Data-driven approximation of the Koopman generator: Model reduction, system identification,
    and control,” <i>Physica D: Nonlinear Phenomena</i>, vol. 406, 2020.'
  mla: 'Klus, Stefan, et al. “Data-Driven Approximation of the Koopman Generator:
    Model Reduction, System Identification, and Control.” <i>Physica D: Nonlinear
    Phenomena</i>, vol. 406, 132416, 2020, doi:<a href="https://doi.org/10.1016/j.physd.2020.132416">10.1016/j.physd.2020.132416</a>.'
  short: 'S. Klus, F. Nüske, S. Peitz, J.-H. Niemann, C. Clementi, C. Schütte, Physica
    D: Nonlinear Phenomena 406 (2020).'
date_created: 2020-03-13T12:35:40Z
date_updated: 2022-01-06T06:52:48Z
department:
- _id: '101'
doi: 10.1016/j.physd.2020.132416
intvolume: '       406'
language:
- iso: eng
publication: 'Physica D: Nonlinear Phenomena'
publication_identifier:
  issn:
  - 0167-2789
publication_status: published
status: public
title: 'Data-driven approximation of the Koopman generator: Model reduction, system
  identification, and control'
type: journal_article
user_id: '47427'
volume: 406
year: '2020'
...
