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Publications (10 of 25) Show all publications
Bruneel, T., Crucerescu, S., Löwe, W., Ericsson, M., Perez-Palacin, D. & Nordqvist, J. (2026). A modular multi-agent pipeline framework for large-scale code translation. Future Generation Computer Systems, 184, Article ID 108599.
Open this publication in new window or tab >>A modular multi-agent pipeline framework for large-scale code translation
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2026 (English)In: Future Generation Computer Systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 184, article id 108599Article in journal (Refereed) Published
Abstract [en]

This publication presents an established engineering-driven framework for pipelining large language model (LLM) agents for automatic code translation. The framework is applied in a long-term ongoing industrial project with Danfoss Power Solutions aimed at translating five million lines of Delphi to C#. To manage this scale, the source codebase is divided into translatable chunks, which are processed independently through an agentic LLM pipeline, with subsequently the reassembly of the translated code chunks in the target language. Due to the inherent stochasticity of LLMs, the framework incorporates processing and validation functions to ensure consistency and correctness. As an extended version of our short paper (Bruneel et al., 2025), this paper provides a significantly more comprehensive architectural blueprint. Specifically, we present an indepth background & related work section, formalise the chunking and reassembly strategies, detail the internal mechanics of agent stages, and introduce sequential agent orchestration alongside the dynamic LLM pipeline architecture. Furthermore, we report early empirical observations regarding the pipeline's computational overhead, validation dynamics, and translation quality, noting a practical impact of an initial 10x acceleration over estimated manual translation efforts. Ultimately, we share these expanded insights to inform future development and application in similar large-scale translation tasks.

Place, publisher, year, edition, pages
Elsevier, 2026
Keywords
code translation, large language models, mlops, llmops, llm pipeline, pipeline orchestration
National Category
Software Engineering Computer Sciences
Identifiers
urn:nbn:se:lnu:diva-148289 (URN)10.1016/j.future.2026.108599 (DOI)001790510700001 ()2-s2.0-105039308191 (Scopus ID)
Available from: 2026-07-02 Created: 2026-07-02 Last updated: 2026-08-17Bibliographically approved
Björnberg, D., Nordqvist, J., Ericsson, M., Lindeberg, J., Löwe, W. & Fransson, J. (2026). Gradient Tree Boosting for Regression Transfer. Transactions on Machine Learning Research, Article ID 7551.
Open this publication in new window or tab >>Gradient Tree Boosting for Regression Transfer
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2026 (English)In: Transactions on Machine Learning Research, article id 7551Article in journal (Refereed) Published
Abstract [en]

Many real-world modeling problems are hindered by limited data availability. In such cases, transfer learning leverages related source domains to improve predictions in a target domain of interest. We extend the classical gradient tree boosting paradigm to a regression transfer algorithm by modeling the weak learner as a sum of two regression trees. The trees are fitted on source data and target data, respectively, and jointly optimized for the target data. We derive optimal coefficients for the model update under the least-squares, the least-absolute-deviation, and the Huber loss functions. We benchmark our approach against boosting-based regression transfer methods in twelve transfer scenarios. The results indicate that our approach constitutes a competitive alternative within the realm of boosting-based regression transfer. Moreover, we provide a theoretical justification as well as empirical validation that our approach is robust under larger domain shifts.

National Category
Mathematical sciences
Identifiers
urn:nbn:se:lnu:diva-149112 (URN)
Available from: 2026-08-17 Created: 2026-08-17 Last updated: 2026-08-18Bibliographically approved
Jabeen, R., Ericsson, M., Nordqvist, J. & Wingkvist, A. (2026). Graph Embeddings for Software Architecture Recovery. Nordic Machine Intelligence, 6(4), 20-36
Open this publication in new window or tab >>Graph Embeddings for Software Architecture Recovery
2026 (English)In: Nordic Machine Intelligence, E-ISSN 2703-9196, Vol. 6, no 4, p. 20-36Article in journal (Refereed) Published
Abstract [en]

A software system's source code is organized into files, but the way those files group into architectural modules is often undocumented or has drifted from the original design. Software architecture recovery (SAR) reconstructs this module view to help developers understand and maintain large systems.

We study SAR from file-level static dependency graphs by learning file embeddings in a self-supervised manner and clustering them into modules. Using node2vec as a baseline, we train graph autoencoders via link reconstruction and compare dependency-based representations (a graph attention encoder, with and without personalized PageRank diffusion) against heterogeneous ones that also incorporate the project's folder structure. We evaluate eleven open-source Java, C, and C++ systems against ground-truth architectures using complementary alignment and modularity metrics. Recovery from a dependency structure alone is useful but limited, bounded more by how much structural context is available to the model than by the choice of encoder. Folder organization helps where dependency cohesion is weak, but heterogeneous methods often gain alignment by drifting from pure dependency modularity, a trade-off between structural cohesion and the developer-intended decomposition. No single method wins on every system and metric — node2vec and the diffusion model are comparable on dependencies alone, while folder-aware methods are worth their added complexity mainly when cohesion is weak. All representations scale well and are practical to run and tune, so representation learning is not the bottleneck for adoption.

Place, publisher, year, edition, pages
University of Oslo Library, 2026
Keywords
Graph autoencoders, Graph attention networks, Software architectures
National Category
Software Engineering Computer Sciences
Identifiers
urn:nbn:se:lnu:diva-148830 (URN)10.5617/nmi.13153 (DOI)
Funder
Knowledge Foundation
Available from: 2026-07-24 Created: 2026-07-24 Last updated: 2026-08-18Bibliographically approved
Björnberg, D., Ericsson, M., Lindeberg, J., Löwe, W., Nordqvist, J., Wallerman, J. & Fransson, J. (2026). Improving national forest attribute maps of Sweden with machine learning. Science of Remote Sensing, 13, Article ID 100395.
Open this publication in new window or tab >>Improving national forest attribute maps of Sweden with machine learning
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2026 (English)In: Science of Remote Sensing, ISSN 2666-0172, Vol. 13, article id 100395Article in journal (Refereed) Published
Abstract [en]

Remote sensing techniques are widely used for mapping and monitoring forest attributes, providing valuable information on forest cover, biomass, and overall forest health. In recent years, national airborne laser scanning (ALS) campaigns have been conducted in several countries to map forest resources. When combining ALS with field inventory data, these datasets enable the development of nationwide models for prediction of forest attributes. In this study, we explore the potential of machine learning (ML) to enhance existing modeling approaches for nationwide forest attribute mapping in Sweden. We achieve this by relating ALS data from the most recent ALS campaign of Sweden with field data from the Swedish National Forest Inventory (NFI). By aggregating laser metrics from surveyed areas (NFI plots), as well as over surrounding areas to the plots, we investigate (1) if ML approaches can outperform existing linear regression baseline models and (2) if further enhancements of the predictive capacity can be achieved by including surrounding, spatially correlated ALS data. To this end, we used extreme gradient boosting (XGBoost), as well as a convolutional neural network (CNN), specialized to handle tabular data and spatially correlated data, respectively. The models were evaluated on five forest variables: basal-area weighted mean tree height, basal-area weighted mean stem diameter, basal area, stem volume, and above-ground biomass. All models were evaluated on several nested datasets to assess the robustness, showcasing consistent results across datasets. We achieved significant improvements in prediction accuracy across all investigated forest variables. Furthermore, incorporating surrounding information to the modeling rendered further improvements for diameter, basal area, and biomass predictions. The approaches tested and developed here thus form a promising basis for flexible modeling approaches that can be transferred globally for large-scale forest monitoring and management.

Place, publisher, year, edition, pages
Elsevier, 2026
Keywords
Airborne laser scanning, Forest variable estimation, Forest mapping, Forest monitoring, Remote sensing
National Category
Forest Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-145305 (URN)10.1016/j.srs.2026.100395 (DOI)001690318200001 ()
Funder
Knowledge FoundationVinnovaSwedish Energy AgencyEU, Horizon Europe, 773324Swedish Research Council FormasEU, Horizon 2020
Available from: 2026-02-27 Created: 2026-02-27 Last updated: 2026-03-09Bibliographically approved
Hönel, S. & Nordqvist, J. (2025). From Lab to Factory: Pitfalls and Guidelines for Self-/Unsupervised Defect Detection on Low-Quality Industrial Images. In: Inês Dutra; Mykola Pechenizkiy; Paulo Cortez; Sepideh Pashami; Alípio M. Jorge; Carlos Soares; Pedro H. Abreu, João Gama (Ed.), Machine Learning and Knowledge Discovery in Databases. Applied Data Science Track: European Conference, ECML PKDD 2025, Porto, Portugal, September 15-19, 2025, Proceedings, Part IX. Paper presented at European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD) 2025 (pp. 511-527). Springer Nature
Open this publication in new window or tab >>From Lab to Factory: Pitfalls and Guidelines for Self-/Unsupervised Defect Detection on Low-Quality Industrial Images
2025 (English)In: Machine Learning and Knowledge Discovery in Databases. Applied Data Science Track: European Conference, ECML PKDD 2025, Porto, Portugal, September 15-19, 2025, Proceedings, Part IX / [ed] Inês Dutra; Mykola Pechenizkiy; Paulo Cortez; Sepideh Pashami; Alípio M. Jorge; Carlos Soares; Pedro H. Abreu, João Gama, Springer Nature , 2025, p. 511-527Conference paper, Published paper (Refereed)
Abstract [en]

The detection and localization of quality-related problems in industrially mass-produced products has historically relied on manual inspection, which is costly and error-prone. Machine learning has the potential to replace manual handling. As such, the desire is to facilitate an unsupervised (or self-supervised) approach, as it is often impossible to specify all conceivable defects ahead of time. A plethora of prior works have demonstrated the aptitude of common reconstruction-, embedding-, and synthesis-based methods in laboratory settings. However, in practice, we observe that most methods do not handle low data quality well or exude low robustness in unfavorable, but typical real-world settings. For practitioners it may be very difficult to identify the actual underlying problem when such methods underperform. Worse, often-reported metrics (e.g., AUROC) are rarely suitable in practice and may give misleading results. In our setting, we attempt to identify subtle anomalies on the surface of blasted forged metal parts, using rather low-quality RGB imagery only, which is a common industrial setting. We specifically evaluate two types of state-of-the-art models that allow us to identify and improve quality issues in production data, without having to obtain new data. Our contribution is to provide guardrails for practitioners that allow them to identify problems related to, e.g., (lack of) robustness or invariance, in either the chosen model or the data reliably in similar scenarios. Furthermore, we exemplify common pitfalls in and shortcomings of likelihood-based approaches and outline a framework for proper empirical risk estimation that is more suitable for real-world scenarios.

Place, publisher, year, edition, pages
Springer Nature, 2025
Series
Lecture Notes in Artificial Intelligence, ISSN 2945-9133, E-ISSN 2945-9141 ; 16021
Keywords
Unsupervised Anomaly Detection, Anomaly Localization, Normalizing Flows, Industrial Visual Inspection, Low-Quality Imagery, Robust Evaluation, Out-of-Distribution Detection, Computer Vision in Manufacturing
National Category
Artificial Intelligence Probability Theory and Statistics Computer graphics and computer vision
Research subject
Computer and Information Sciences Computer Science, Computer Science
Identifiers
urn:nbn:se:lnu:diva-142227 (URN)10.1007/978-3-032-06118-8_30 (DOI)2-s2.0-105019192533 (Scopus ID)9783032061188 (ISBN)
Conference
European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD) 2025
Projects
In-line visual inspection using unsupervised learning
Available from: 2025-10-29 Created: 2025-10-29 Last updated: 2025-11-03Bibliographically approved
Jabeen, R., Ericsson, M., Nordqvist, J. & Wingkvist, A. (2025). Graph Convolutional Networks for Mapping Source Code Entities to Architectural Modules. In: 2025 IEEE 22nd International Conference on Software Architecture Companion (ICSA-C): . Paper presented at 22nd IEEE International Conference on Software Architecture (ICSA 2025), Odense, Denmark, March 31 - April 4, 2025 (pp. 472-481). IEEE
Open this publication in new window or tab >>Graph Convolutional Networks for Mapping Source Code Entities to Architectural Modules
2025 (English)In: 2025 IEEE 22nd International Conference on Software Architecture Companion (ICSA-C), IEEE, 2025, p. 472-481Conference paper, Published paper (Other academic)
Abstract [en]

Mapping source code entities manually to architectural modules is labor-intensive and time-consuming. Automating this process can help adopt static architecture compliance checking techniques like reflection modeling. We propose a graph-based semi-supervised learning approach to automate this mapping. Our method leverages syntactic and semantic dependencies extracted from compiled software artifacts and formulates the problem as a node classification task on a graph. We investigated Graph Convolutional Network (GCN) variants: (1) a homogeneous graph approach that treats all dependencies uniformly and (2) a heterogeneous graph approach that maintains distinct dependency types, utilizing a Relational Graph Convolutional Network (RGCN). The proposed method was evaluated on eight open-source Java systems and benchmarked against the state-of-the-art Naive Bayes classifier. Results demonstrate that the RGCNN variant outperforms the baseline, offering improved accuracy for mapping source code entities to architectural modules.

Place, publisher, year, edition, pages
IEEE, 2025
Keywords
Graph convolution network, software architecture
National Category
Computer Sciences
Research subject
Computer Science, Software Technology
Identifiers
urn:nbn:se:lnu:diva-138079 (URN)10.1109/ICSA-C65153.2025.00071 (DOI)2-s2.0-105007946654 (Scopus ID)
Conference
22nd IEEE International Conference on Software Architecture (ICSA 2025), Odense, Denmark, March 31 - April 4, 2025
Available from: 2025-04-16 Created: 2025-04-16 Last updated: 2026-01-05Bibliographically approved
Pelgrom, N., Hangelbäck, J., Ericsson, M., Nordqvist, J. & Grahn, H. (2025). Hallucinations and Training-Data Bias: Results from Two Number Transcription Experiments Using GPT Models. In: Computational Science and Computational Intelligence (CSCI 2024): . Paper presented at International Conference on Computational Science and Computational Intelligence (pp. 59-69). Springer Science+Business Media B.V., 2501
Open this publication in new window or tab >>Hallucinations and Training-Data Bias: Results from Two Number Transcription Experiments Using GPT Models
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2025 (English)In: Computational Science and Computational Intelligence (CSCI 2024), Springer Science+Business Media B.V., 2025, Vol. 2501, p. 59-69Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents two experiments testing the capabilities of the models GPT-4-vision-preview and GPT-4o, to transcribe images of randomly generated number-strings. We noticed a tendency for longer number strings to be read inaccurately while transcribing invoices using the models, so we created an experiment with images with minimal noise to see what amount of digits these models are able to transcribe with full accuracy. We further tested weather the mistakes that occur in transcribing longer strings are reoccurring when the images are re-tested. We analyzed the character of the mistakes made, and weather any digits are over represented among the ones involved in mistakes. We found, among more results described in the paper, that the models are 100% accurate up to 75 digits per image, that the same mistakes are reoccurring when the same image is rerun, and that hallucinations are only 23% of all mistakes made by the models.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2025
Series
Communications in Computer and Information Science ; 2501
Keywords
Generative AI, Large Language Model, LLM Hallucinations, OCR
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:lnu:diva-142938 (URN)10.1007/978-3-031-90341-0_5 (DOI)2-s2.0-105006767018 (Scopus ID)9783031903403 (ISBN)
Conference
International Conference on Computational Science and Computational Intelligence
Available from: 2025-12-23 Created: 2025-12-23 Last updated: 2026-01-08Bibliographically approved
Bruneel, T., Löwe, W., Ericsson, M., Perez-Palacin, D. & Nordqvist, J. (2025). Optimising Pixel-Wise Time-Series Analysis of Vegetation Indices Imagery via Key-Pixel Selection. In: Proceedings of Swedish AI Society Workshop 2025 (SAIS 2025): . Paper presented at Swedish AI Society Workshop 2025 (SAIS 2025) (pp. 26-38). CEUR-WS, 4037
Open this publication in new window or tab >>Optimising Pixel-Wise Time-Series Analysis of Vegetation Indices Imagery via Key-Pixel Selection
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2025 (English)In: Proceedings of Swedish AI Society Workshop 2025 (SAIS 2025), CEUR-WS , 2025, Vol. 4037, p. 26-38Conference paper, Published paper (Refereed)
Abstract [en]

Pixel-wise time-series analysis of satellite-derived vegetation indices is often complex and computationally demanding, as the pixel-wise application of the analysis scales with the number of pixels to be processed. In this study, we use Gaussian Process Regression (GPR) pixel-wise to fill temporal gaps in Normalized Difference Vegetation Index (NDVI) data. Rather than applying GPR across all pixels and trying to optimise the performance of GPR directly, we introduce an algorithm to select key pixels for GPR applications. By selectively applying GPR to a subset of pixels and image reconstruction of the remaining unselected pixels, we achieve substantial speedups (2.5-5.5×) with minimal loss in NDVI estimation accuracy (0.5-2.5%). This trade-off with pixel selection enables more scalable and efficient pixel-wise processing of large-scale imagery, with strong applicability in the field of remote sensing.

Place, publisher, year, edition, pages
CEUR-WS, 2025
Series
Ceur Workshop Proceedings
Keywords
Gaussian Process Regression, Key-Pixel Selection, NDVI, Performance Optimisation, Pixel-Wise Processing, Remote Sensing, Temporal Gap-Filling
National Category
Computer Sciences
Identifiers
urn:nbn:se:lnu:diva-142921 (URN)2-s2.0-105017600940 (Scopus ID)
Conference
Swedish AI Society Workshop 2025 (SAIS 2025)
Available from: 2025-12-23 Created: 2025-12-23 Last updated: 2026-01-08Bibliographically approved
Pelgrom, N., Ericsson, M., Hagelbäck, J., Nordqvist, J. & Grahn, H. (2025). Using ChatGPT as a Combined Invoice OCR and Key-Value Extractor. In: 2025 10th International Conference on Big Data Analytics (ICBDA) 2025: . Paper presented at 10th International Conference on Big Data Analytics (ICBDA), Singapore, 13 - 15 March, 2025. Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Using ChatGPT as a Combined Invoice OCR and Key-Value Extractor
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2025 (English)In: 2025 10th International Conference on Big Data Analytics (ICBDA) 2025, Institute of Electrical and Electronics Engineers (IEEE), 2025Conference paper, Published paper (Refereed)
Abstract [en]

This paper provides details and analysis of findings from three experiments on the capabilities of the OpenAI chatbot ChatGPT-4 with vision capabilities as a dual-purpose tool for Optical Character Recognition (OCR) and key-value data extraction tasks. Our results could be relevant to any task where one is interested in extracting key information from images with approximately equal complexity, and are scalable to be used for large datasets. We did the main experiments in the OpenAI user interface for the model, and a smaller experiment using the API. The experiment used a dataset comprising 1000 digital invoices alongside 1000 photographic images of real receipts, collected from a broad spectrum of market sectors within Sweden. The main experiment gave us a significant accuracy rate, achieving $\mathbf{9 9. 8 \%}$ in extracting critical financial information from the digital invoices. Similarly, when applied to the photographic images of receipts, it maintained a high accuracy level of $\mathbf{9 9. 5 \%}$. The smaller experiment gave us an accuracy of $\mathbf{9 4. 4 \%}$ These findings are particularly noteworthy not only because of the high accuracy levels but also due to the model's effectiveness in performing both OCR and key-value extraction tasks as a one-step process. This dual functionality underscores the model's potential as a highly efficient and reliable solution in automating financial data extraction and processing tasks.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2025
Keywords
Key-Value Extraction, Large Language Model, Optical Character Recognition
National Category
Computer Systems
Identifiers
urn:nbn:se:lnu:diva-145004 (URN)10.1109/ICBDA65366.2025.11211156 (DOI)2-s2.0-105023839703 (Scopus ID)9798331503932 (ISBN)
Conference
10th International Conference on Big Data Analytics (ICBDA), Singapore, 13 - 15 March, 2025
Available from: 2026-02-13 Created: 2026-02-13 Last updated: 2026-03-02Bibliographically approved
Björnberg, D., Ericsson, M., Lindeberg, J., Löwe, W. & Nordqvist, J. (2024). Image generation of log ends and patches of log ends with controlled properties using generative adversarial networks. Signal, Image and Video Processing, 18, 6481-6489
Open this publication in new window or tab >>Image generation of log ends and patches of log ends with controlled properties using generative adversarial networks
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2024 (English)In: Signal, Image and Video Processing, ISSN 1863-1703, E-ISSN 1863-1711, Vol. 18, p. 6481-6489Article in journal (Refereed) Published
Abstract [en]

The appearance of the log cross-section provides important information when assessing the quality of the log, where properties to consider include pith location and density of annual rings. This makes tasks like estimation of pith location and annual ring detection of great interest. However, creating labeled training data for these tasks can be time-consuming and subject to misjudgments. For this reason, we aim to create generated training data with controlled properties of pith location and amount of annual rings. We propose a two-step generator based on generative adversarial networks in which we can completely avoid manual labeling, not only when generating training data but also during training of the generator itself. This opens up the possibility to train the generator on other types of log end data without the need to manually label new training data. The same method is used to create two generated training datasets; one of entire log ends and one of patches of log ends. To evaluate how the generated data compares to real data, we train two deep learning models to perform estimation of pith location and ring counting, respectively. The models are trained separately on real and generated data and evaluated on real data only. The results show that the performance of both estimation of pith location and ring counting can be improved by replacing real training data with larger sets of generated training data.

Place, publisher, year, edition, pages
Springer, 2024
Keywords
Generative adversarial network, Image generation of log ends, Training data generation, Conditional GAN, CycleGAN
National Category
Computer Engineering Computer Sciences Computer graphics and computer vision
Research subject
Computer and Information Sciences Computer Science, Computer Science
Identifiers
urn:nbn:se:lnu:diva-131577 (URN)10.1007/s11760-024-03331-w (DOI)001249395800002 ()2-s2.0-85196276821 (Scopus ID)
Funder
Knowledge Foundation, 20190336
Available from: 2024-07-31 Created: 2024-07-31 Last updated: 2025-04-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0510-6782

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