Celebrating One Year of QUEENS as Open-Source Software

[sbrandstaeter]

🎉 Celebrating One Year of QUEENS as Open-Source Software

On 20 December 2024, QUEENS officially went open source – today we’re celebrating one year of the project being out in the open! 🥂

QUEENS (Quantification of Uncertain Effects in Engineering Systems) is our open-source Python framework for solver-independent analyses of large-scale computational models. Over the past year, it has grown thanks to the work of maintainers, contributors, students, collaborators, and users all over the world. Thank you for being part of it. 💚

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Highlights at a glance

Here are some of the things that happened in our first open-source year:

• 🧑‍💻 New contributors joined the project and opened issues, PRs and discussions.
• 📄 QUEENS paper on arXiv and submitted for publication.
• 🌐 New website: https://www.queens-py.org/
• 🧠 New methods and major refactors of the codebase (naming scheme, src layout, data & dependency management…).
• 🧭 Usability improvement including documentation and maintainability
• 🎤 Talks & tutorials at UNCECOMP, ESB, ICCB, UKACM & GACM Autumn School and more.

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What we built this year

✨ New methods, usability & maintainability

Since the start of 2025 we’ve implemented several new methods in QUEENS and made foundational improvements to the codebase:

• New methods

  • Multilevel Monte Carlo @janniskoeckeritz
  • Control variates @janniskoeckeritz
  • Reinforcement learning–based approaches @danielwolff1

• Usability & maintainability

  • Introduced a coherent naming standard (05/25) @maxdinkel
  • Restructured simulation data management (05/25) @sbrandstaeter
  • Simplified dependency management (06/25) @gilrrei
  • Moved the codebase to a src layout (06/25) @gilrrei
  • Discontinued the input-file workflow (08/25) @maxdinkel
  • Removed the need for dedicated driver objects in schedulers @gilrrei
  • Major documentation rework (design, testing, content) @leahaeusel @gilrrei
  • Added tested tutorials @BishrMaradni @gilrrei @sbrandstaeter @reginabuehler
  • Testing with the latest 4C version and improved subprocess logging
  • Continued cluster testing on GitHub
  • Introduced type hints and lazy imports @leahaeusel @maxdinkel
  • Improved results handling
  • Started working towards a clear frontend/backend separation Untangling the backend QUEENS dependencies #244

Many of these changes aren’t visible from the outside, but they make the project more robust, maintainable and pleasant to contribute to.

🤝 Community milestones

Beyond code and features, the community around QUEENS has grown a lot this year:

• 120 pull requests from 11 different commit authors
• 21 developer meetings, which we now run publicly
• Public community meetings and a survey on infrastructure improvements
• Improved communication with clearer, central announcement channels
• An “introduce yourself” section to welcome new faces
• The QUEENS design rework as a true community effort

A special thank-you to everyone who contributed code, ideas, issues, reviews and feedback. We’re excited to see the list of contributors grow in the coming years.

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Publications, talks & events

📑 Papers using or presenting QUEENS

QUEENS has been used in and featured by several papers and preprints on UQ, inverse analysis and biomechanical simulations.

👉 For an up-to-date list of publications, please see the Publications on our website.
Please cite QUEENS if it helps your research – it really supports the project. 🙌

🎤 Selected presentations & talks

A few highlights from a long list of talks involving QUEENS:

• S. Brandstaeter – “Navigating Biological Variability in Biomechanical Models: Insights from Uncertainty Quantification and Global Sensitivity Analysis.” Gut Motility Workshop, 17–27 Feb. 2025, Auckland, New Zealand.
• L. Häusel, J. Nitzler, L. Köglmeier, and W. Wall – “Inverse Insights through Multiphysics: Learning from Coupled Fields.” UNCECOMP 2025, 17 June 2025, Rhodes, Greece.
• S. Brandstaeter, B. Maradni, and A. Popp – “Probabilistic Virtual Sensing with Gaussian Processes and Physics-Based Models.” UNCECOMP 2025, 18 June 2025, Rhodes, Greece.
• M. Dinkel and W. Wall – “Towards Higher Information Gain from Bayesian Calibration in Real-World Engineering Applications.” UNCECOMP 2025, 18 June 2025, Rhodes, Greece.
• G. Robalo Rei, J. Nitzler, M. Dinkel, C. Schmidt, and W. Wall – “A Black Box Variational Inference Scheme for Bayesian Inference with Demanding Physics-Based Forward Models.” UNCECOMP 2025, 18 June 2025, Rhodes, Greece.
• W. Wall, M. Dinkel, L. Häusel, J. Nitzler, and G. Robalo Rei – “Advanced Methods for Uncertainty Quantification, Inverse Analysis and Digital Twinning for Complex and Multi-Physics Problems.” UNCECOMP 2025, 18 June 2025, Rhodes, Greece.
• M. Henke, S. Brandstaeter, A. Gizzi, and C. J. Cyron – “Coupled Electromechanical Simulations of the Human Stomach.” 30th Congress of the European Society of Biomechanics (ESB 2025 Congress), 6–9 July 2025, Zürich, Switzerland.
• S. Brandstaeter and M. Henke – “Multi-Query Analysis of Electromechanical Stomach Models Enhances Understanding of Biophysical Function.” XI International Conference on Computational Bioengineering (ICCB 2025), 8–10 Sept. 2025, Rome, Italy.
• S. Brandstaeter – “UQ, GSA and QUEENS: Possible GI Applications.” International Workshop on Gastrointestine Biomechanics & Motility, 11 Sept. 2025, Rome, Italy.

🧑‍🏫 Workshops & events

QUEENS was part of various events, including:

• UNCECOMP 2025 – talks and demos on UQ and inverse analysis
• 3rd German Workshop on Next-Generation Software Development in Computational Mechanics (GWNGSDCM) – Freising
• UKACM & GACM Autumn School 2025 – online hands-on sessions on 4C & QUEENS
• The QUEENS Open-Source Party 2025 in Munich 🎈

These events helped us connect with users, gather feedback, and spread the word about solver-independent UQ and inverse analysis workflows.

Thanks to all co-authors, co-organizers, and participants who made these possible!

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🖥️ Website & design

In 2025 we also gave QUEENS a visual refresh:

• A major design makeover for the project.
• Migration and redesign of the QUEENS website:
  👉 https://www.queens-py.org/

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🙏 Thank you, Barbara

This year also marks a change in the maintainer team: Barbara (@bwirthl) decided to step down from her QUEENS maintainer role.

Barbara, thank you for your many contributions. Your work has shaped the project in important ways, and we’re very grateful for your time and energy. 💐

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🚀 What’s next

In year two of QUEENS as an open-source project, we’re aiming to:

• Further structure the frontend/backend separation.
• Advance our work-in progress methods: Covariance Matrix Adaptation Evolution Strategy (CMA-ES) and Shapley values
• Add more tutorials and example workflows, especially for new users.
• Improve developer experience with clearer contribution guidelines, better CI and more tests.
• Continue collaborating through workshops, schools and joint projects.

If you have ideas or feature requests, please let us know!

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🤝 Get involved

If you’d like to join us:

• ⭐ Star the repo: https://github.com/queens-py/queens
• 📦 Install QUEENS and try the tutorials – see the documentation on https://www.queens-py.org/
• 🐛 Report issues or request features via GitHub Issues
• 🧑‍💻 Contribute via pull requests
• 📑 Cite QUEENS if you use it in your research

Thank you for an amazing first year of open source – and here’s to many more years (and lots more uncertainty) ahead. 🥂

Acknowledgement: Thanks to @reginabuehler for turning our look back into a polished announcement.