In 2025, ARNES continued the intensive development and upgrade of its high-performance computing (HPC) infrastructure, further strengthening the capabilities of the national environment for advanced computing. The ARNES computing cluster, in operation since 2009, represents one of the key processing resources for the Slovenian research and education community. With a total computing power of approximately 2.3 petaFLOPS, it is the second most powerful supercomputer in Slovenia and the only one accessible both to beginners and to more advanced users.
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Author: ARNES
High Performance Computing has become a key enabler of innovation in modern engineering. At the Faculty of Mechanical Engineering, University of Ljubljana, the HPCFS infrastructure provides researchers and students with the computational power necessary for advanced simulations, modelling, and data analysis. This paper presents the motivation for using HPC in engineering, an overview of the HPCFS system, and the planned 2025 upgrade. The selected projects demonstrate how HPC supports complex analyses ranging from plasma simulations to AI-driven modelling.
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Authors: Pavel Tomšič, Leon Kos, Matjaž Šubelj, University of Ljubljana
The Gray–Scott School 2025 – Revolutions offered an intensive introduction to modern high-performance computing, with a focus on optimization, profiling, and software engineering across CPE and GPE architectures. The Slovenian satellite school, hosted at the Faculty of Engineering and on the VEGA supercomputer, provided hands-on exercises and discussions based on the Gray–Scott reaction–diffusion model — a pedagogical system well suited for parallelization. Participants explored advanced programming in C++, Rust, Fortran, and Python, applying concepts such as vectorization, cache blocking, GPE offloading, and numerical precision. The event exemplified the active role of Slovenian HPC infrastructure and SLING in European HPC education and open science.
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Author: Luka Leskovec, University of Ljubljana
In recent years, AI has become a driving force of technological progress, transforming the way we create, communicate, and design digital content. Originally known primarily as a tool for generating text, AI algorithms are now expanding into images, videos, and 3D models. AI is reshaping 3D modeling into a faster, more accessible, and more automated process. What was once the exclusive domain of experienced designers using software such as Blender, Maya, or ZBrush is now accessible to those without a technical background. Just a few lines of description are enough for AI to generate a preliminary 3D model. These models form the foundation of modern product development, video games, animations, architectural visualizations, and medical diagnostics. The core idea behind using AI for 3D modeling is simple: The user provides a concept, and the AI turns it into a three-dimensional object. Rather than using complex polygon-by-polygon modeling, one can now use a text description, a sketch, or a reference image. Machine learning algorithms, often powered by deep neural networks, then generate a mesh or voxel-based representation that designers can refine as needed.
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Authors: Domen Verber, Jani Dugonik; University of Maribor
Artificial Intelligence (AI) is becoming an indispensable tool in healthcare, improving diagnostics, treatment planning, and patient outcomes. As AI systems handle sensitive health data and make critical decisions, ethical considerations, including patient privacy, data security, and the transparency of AI decision-making processes, are paramount. The CLASSICA project (Horizon Europe Programme) is at the forefront of integrating AI with medical technology to tackle colorectal cancer, the third most common type of cancer worldwide. CLASSICA transforms a research prototype into a vital tool for surgeons, utilising tissue fluorescence dynamics to effectively distinguish between cancerous and non-cancerous tissues. The technology leverages the differential fluorescence intensity of tissues when exposed to indocyanine green (ICG), a fluorescent dye, and excited by near-infrared (NIR) light. This method captures and analyses the intensity curves from video frames, allowing for real-time AI-based classification of tissues during colorectal cancer surgery.
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Authors: Samo Eržen, Jernej Cucek, Jan Rojc; Arctur
The ARNES data center will integrate the capabilities of the new Slovenian supercomputer, the Slovenian Artificial Intelligence Factory (SLAIF), permanent storage of research data, and infrastructure to support open science. This strategic investment will establish a central Slovenian hub for open science and supercomputing.
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Author: ARNES
In recent years, generative artificial intelligence has transformed the way texts are created. Tools like ChatGPT can now write essays, school papers, advertisements, and even articles like this one in just a few clicks. These tools can mimic different writing styles, draw on massive amounts of data, and sound increasingly "human." However, the rapid development of this technology also raises an important question: Who is the real author of the text we’re reading? In an era when a convincing essay or article can be generated in seconds, the need to verify content authenticity is growing.This has led to the development of detectors, which are tools designed to determine whether a text was written by a human or by AI. Most of these detectors measure perplexity. Large language models produce text that is smooth and orderly, following a kind of statistical logic. In contrast, human writing is often imperfect, riddled with errors, stylistic quirks, and even contradictions.
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Authors: Jani Dugonik, Domen Verber; University of Maribor
Technological innovations with flashy names often receive a lot of media attention, but they often amount to nothing more than passing trends. Interest in artificial intelligence, however, will not fade so easily. The rise of generative models—including today's popular large language models, such as Claude and ChatGPT; image models, such as DeepAI and DALL·E; and lesser-known or proprietary industrial and development-specific models—has firmly placed AI at the core of modern society's developmental, technological, administrative, user interface, and artistic and creative foundations.
To ensure our researchers and technology developers have access to powerful enough tools to meet the increasingly demanding technological and skill-related challenges brought about by the rise of artificial intelligence, numerous AI factories are being established across the shared European research space. One such AI factory is being developed in Slovenia. The project will include support mechanisms to guide and assist users, as well as educational activities. At its core is the development of a new supercomputer specifically designed for AI tasks.
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Authors: Jan Jona Javoršek, Florian Klauser; Jožef Stefan Institute
ChatGPT has become a valuable tool in software development, capable of generating code quickly and providing useful insights. However, directly copying large code snippets into a project without review can introduce unintended bugs, often leading to time-consuming debugging. In some cases, manually writing code from scratch may be more efficient.
Despite these challenges, there are several scenarios where ChatGPT adds significant value to coding workflows. Below are some practical examples, focusing on Python, though the same concepts can be applied to other programming languages. The goal is not just to solve problems but to demonstrate how to use ChatGPT effectively as a development assistant.
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Author: Mark Baltič; Arctur
This year's Arnes Hackathon 2025 has once again shown that open science and supercomputing are key tools to tackle the challenges of modern society. Under the slogan “Fly into the future with open science and supercomputing”, more than a hundred participants from all over Slovenia took part in finding innovative solutions to the challenges set by the HackathON. The Hackathon took place in two rounds with a clear focus on sustainable development, the use of digital twins, and HPC technologies.
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Author: ARNES
The past year has seen the continued rapid advancement of large language models, yet training them has become increasingly complex. Even companies with vast financial and computational resources are encountering significant limitations that slow progress in enhancing these models’ capabilities.
One notable example is OpenAI’s development of its new Orion model, which has faced several challenges. While Orion has shown some improvements in language tasks, its overall progress—particularly in programming—has been modest compared to the leap from GPT-3 to GPT-4. Testing has revealed that the model struggles to handle coding tasks as efficiently as its predecessor, raising serious concerns within the development team.
The whole article is available here (in Slovene language only).
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Author: Jenz Perš; University of Ljubljana
Artificial Intelligence (AI) has made rapid progress in recent years, especially in the field of generative and large language models (LLMs). Its growing capabilities are making it increasingly important across various industries, including engineering. To integrate AI into mechanical engineering more effectively, they explored how and where its potential can be best utilized. This study presents a methodology that incorporates AI into computer-aided design (CAD), enabling a simple and efficient conversion of text descriptions into parametric 3D models written in the STEP format.
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Authors: Luka Samsa, Nikola Vukašinović, Miha Brojan; University of Ljubljana
To overcome the many problems of compiling software on supercomputers, a few solutions are emerging. The first are package managers like EasyBuild, Spack, Conda, Nix or GuixHPC. At the same time, European projects have been funded over the last few years to help with this problem. It is also worth mentioning containers, which provide users with an isolated environment in which to run their software.
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Author: Alja Prah; Jožef Stefan Institute
Optimization problems are everywhere in today's world. From minimizing costs to maximizing efficiency, the goal is often to find the most effective solution for a given task. These challenges typically involve identifying the maximum and minimum values—such as reducing fuel costs for a transportation company. One of the most powerful and valuable methods for tackling these problems is the use of genetic algorithms, a technique inspired by Darwin's theory of evolution.
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Author: Nejc Hočevar; Arctur
Containers in high-performance computing (HPC) offer a flexible and efficient alternative to traditional modular software. Containers permit researchers and engineers to package applications and their dependencies into a single file, thereby ensuring portability, reproducibility and consistent performance across different computing environments.
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Author: Barbara Krašovec; Jožef Stefan Institute
The work by UL focuses on the optimization of ray-tracing techniques, commonly used in simulation of nuclear fusion phenomena, especially estimation of radiation on plasma facing surfaces, signal calculation of diagnostic systems to arrive at synthetic diagnostic signal.
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Author: Matic Brank; University of Ljubljana
In recent years, artificial intelligence (AI) has dramatically changed various industries, including tourism. The integration of advanced technologies such as high-performance computing (HPC) and machine learning has enabled tourism companies to improve user experience, optimize processes and adapt marketing strategies.
The tourism industry faces many challenges that can be addressed by advanced technologies. One of the main problems is processing the huge amounts of data generated by tourism providers such as hotels, airlines and travel agencies. Managing this data requires powerful systems that can analyze and predict customer behavior and optimize operational processes in real time. In addition, the tourism sector faces the need to improve the user experience at all customer touch points, from travel planning to post-service feedback. The key is for companies to understand customer preferences and behavior, which is no easy task in such a dynamic environment.
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Authors: Domen Verber, Jani Dugonik; University of Maribor
Many breakthroughs in speed and accuracy of single image super-resolution (SISR) have been achieved. One of the biggest challenges is how to recover finer texture details when super-resolution is applied at large upscaling factors. A typical solution to SISR involves using a convolutional neural network (CNN), however new approaches using a generative adversarial network (GAN) are now also popular. The behavior of optimization-based super-resolution methods is principally driven by the choice of the objective function. In this work, we present an evaluation of SRResNet and SRGAN. SRResNet is a deep residual network and SRGAN is a generative adversarial network for image super-resolution (SR). SRResNet is able to recover reasonable quality photo-realistic textures from heavily downsampled images. SRGAN is capable of inferring photo-realistic natural images with high upscaling factors. This is achieved using a perceptual loss function which consists of an adversarial loss and a content loss. The adversarial loss pushes the solution to the natural image manifold using a discriminator network that is trained to differentiate between the super-resolved images and original photo-realistic images. The content loss is motivated by perceptual similarity instead of similarity in pixel space.
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Author: Sebastien Strban; University of Ljubljana
Object counting is crucial in applications ranging from cell growth analysis, to crowd estimation in video surveillance systems, to product counting on production lines. Classical methods are not applicable in these cases because they require large annotated training sets and struggle in dense scenarios. On the other hand, the methods developed at the Visual Cognitive Systems Laboratory at the Faculty of Computer Science and Information Science, University of Ljubljana, develop accurate counting with just a few training examples and represent a methodological leap in computer vision.
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Authors: Matej Kristan; University of Ljubljana, Urša Vodopivec; ARNES
The digital transformation of organizations represents a necessary process for achieving competitiveness in both the economic and public sectors, thereby contributing to the development of the entire society. To encourage and accelerate this process, the European Commission has adopted two multi-annual work programs for the Digital Europe Program (DIGITAL) to support digital transformation and strengthen cybersecurity.
In the framework of the call for proposals for European Digital Innovation Hubs (EDIH), published by the European Commission in 2021, two Slovenian candidates were selected, the DIGI-SI consortium and SRC-EDIH, while 4PDIH obtained a Certificate of Excellence.
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Author: University of Maribor
Optimizing a container ship's hull for both calm water and added resistance in waves is a complex technical challenge. In calm water, the focus is on reducing resistance to enhance fuel efficiency and speed. This often involves streamlining the hull shape to minimize resistance. However, in wave conditions, additional factors like wave-induced motions, wave reflection and refraction come into play. This demands an iterative approach by employing CFD simulations and HPC resources to balance streamlined shapes for calm water efficiency hull geometry features that reduce added wave resistance.
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Author: Arctur
In the development of new medicinal compounds, research laboratories employ robotic equipment for high-throughput screening (HTS), which enables automated experimental in vitro biological evaluation of various compounds with a capacity of several hundred thousand compounds [1]. With the rapid advancement of computer science, this relatively expensive and complex process is complemented and being replaced by computational tools for molecular modelling. Similar to experiments conducted in vivo or in vitro, we can also refer to experiments conducted in silico, which literally means in silicon, essentially referring to computer simulation.
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Authors: Davor Sluga, Ratko Pilipović, Nejc Ilc; University of Ljubljana
We have recently upgraded our computing cluster at Arnes, and it is now much more powerful.
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Author: ARNES
The main result is 100 digitised units of cultural heritage and 30 5-star tourist products - AR app at the Russian Chapel, re-created world of sunken villages, exploring local stories with the help of a web app, e-Castles digital room, interpretation of 7 castles, Winegrowing and winemaking interpretation, etc.
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Athor: Arctur
