TIB Open Publishing
Not a member yet
1994 research outputs found
Sort by
LABKAG at LLMs4OL 2025 Tasks A and C: Context-Rich Prompting for Ontology Construction
Full text linkThis paper presents LABKAG\u27s submission to the LLMs4OL 2025 Challenge, focusing on ontology construction from domain-specific text using large language models (LLMs). Our core methodology prioritizes prompt design over fine-tuning or external knowledge, demonstrating its effectiveness in generating structured knowledge. For Task A (Text2Onto: extracting ontological terms and types), we utilized a locally deployed Qwen3-8B model, while for Task C (Taxonomy Discovery: identifying taxonomic hierarchies), we evaluated the performance of GPT-4o-mini and Gemini 2.5 Pro. Our experiments consistently show that incorporating in-domain examples and providing richer context within prompts significantly enhances performance. These results confirm that well-engineered prompts enable LLMs to effectively extract entities and their hierarchical relationships, offering a lightweight, adaptable, and generalizable approach to structured knowledge extraction
SEMA at LLMs4OL 2025 Task C: Prompt-Decoupled Fine-Tuning on MatOnto with LLaMA
Full text linkThis paper presents our submission to Task C (Relation Extraction) of the LLMs4OL 2025 Challenge, which investigates the ability of Large Language Models (LLMs) to identify semantic and taxonomic relations between ontology types. Focusing on the MatOnto subtask—selected for its manageable size—we explore the performance of open-source models under resource constraints. We fine-tune LLaMA 3.1–8B using LoRA adapters and evaluate various strategies including contrastive negative sampling, prompt inversion, and system prompt variation. Inspired by recent findings on prompt sensitivity, we adopt a cross-template setup where the model is trained with one prompt format and tested with another semantically equivalent variant. Our experiments suggest that prompt-decoupling can improve generalization and mitigate overfitting to specific phrasings. While our results are modest, they offer insights into the challenges of adapting LLMs to structured relation extraction tasks and highlight practical considerations for tuning under constrained resources
3D-Shape Measurement of Parabolic Trough Mirror Panels:: First Results of the SFERA-III Round Robin
Full text linkThe 3D-shape round-robin initiative aims to compare the main geometric parameters of 3D shape measurements for parabolic-trough mirror panels, assessed using equipment developed and employed by each participating institution: ENEA, F-ISE, DLR, NREL, and SNL. Except ENEA equipment, all the other are based on deflectometry, also call fringe-reflection method. The round-robin is based on circulating 6 trough mirror panels (3 inner and 3 outer) of RP3 dimensions, with a focal length of 1710 mm, between participating laboratories; a simple and rugged supporting fixture together with precise instruction on how to use it have been provided to make the comparison more reliable. ENEA wrote a custom evaluation software for comparing the results. We observe a reasonable agreement among the mean values of the deviations of height and slopes from the ideal parabola: standard deviation better than 0.1 mm, 0.5 mrad and 0.3 mrad for z, slopeX and slopeY, respectively. The agreement is improved when a software realignment procedure for setting the height values on the support points to the expected ideal values is applied. The absolute difference between pairs of evaluators is sometimes greater than the declared experimental uncertainty; investigation into these deviations is still ongoing
Active Thermal Insulation – A Possible Option to reduce Thermal Inertia of Cavity Receivers
Full text linkAn Active Thermal Insulation (ATI) is proposed as suitable option to reduce the transient response of high-temperature cavity-type solar receivers. It consists of a straight tubes bundle, embedded in the insulating material, covering the entire receiver length through which the heat transfer fluid (HTF) is fed prior being injected into the cavity. The implications of adding the ATI to the reference absorbing gas solar receiver were evaluated through a series of 3D CFD simulations campaigns. Two key parameters on the ATI design (i.e., tubes number and radial tubes bundle radial position with respect to the cavity axis) were evaluated assuming the receiver operating at both design conditions (nominal incoming concentrated solar radiation) and part-load (reduced incoming input power). For all the CFD simulations performed, an HTF inlet temperature of 700 °C was assumed with a case-dependent mass flow rate tuned to reach 1’200 °C as HTF outflow temperature. The simulations campaign allowed to observe that a HTF pre-heating, between 4% and 6% with respect to the HTF inlet temperature within the ATI, was achieved for all the cases considered. However, despite this, for some cases the receiver efficiency remained unchanged. The ATI resulted to be beneficial on the receiver efficiency if it is operated at full-load and almost irrelevant in the case of part-load
Energy Utilization Factor of Solar Tower Systems
Full text linkThe solar tower system is one of the most promising concentrated solar power technologies that can address climate change issues by meeting energy demand sustainably while mitigating carbon emissions. The mirrors of the solar tower require a large share of the investment cost and occupy 4-8 times the ground compared to the mirror surface area. The share of the plant area cost may become significantly high for regions where the land is not cheap, especially in developing countries. In this study, a parameter named Energy Utilization Factor is introduced to quantify the utilization of the ground area in terms of available solar radiation energy. The variation of the Energy Utilization Factor is studied for a range of design variables without considering any specific dimensions for the heliostat and the receiver. The annual Energy Utilization Factor is seen to have a maximum value within 15 %, indicating the solar tower system is only capable of using one-seventh of the available solar resource on the ground. The maximum achievable Energy Utilization Factor is seen to increase with the tower height, but reduces with latitude. For a given heliostat field, the Energy Utilization Factor is seen to have a direct relationship with the amount of mirror area employed per unit ground area
Inverse Heat Transfer Analysis for Estimating Heat Flux in Solar Tower Receivers
Full text linkSolar power tower plants are utilized to harness solar radiation for large-scale electricity generation. The concentrated solar radiation is absorbed by the central receiver to heat a transfer fluid, which is typically a mixture of 60% sodium nitrate (NaNO₃) and 40% potassium nitrate (KNO₃) to temperatures up to 565°C. Extreme conditions, including high temperatures and variable heat flux, are experienced by these central receivers, necessitating precise thermal measurements to optimize energy production and maintain efficiency. In this paper, an in-house code based on an inverse analysis technique is developed to determine the absorbed heat flux on the surface of the concentrated solar power (CSP) receiver tube, using surface temperature measurements as input. It is found that a single temperature measurement from the frontal part of the tube (0 ≤ θ < 90°) is sufficient for the estimation of the absorbed flux within an acceptable deviation. Additionally, noise is incorporated into the input temperature data to evaluate the reliability of the code under fluctuating conditions typical of real-world applications. The effectiveness of the code in this scenario is demonstrated, reinforcing its potential for practical applications
TES Model for Hybrid Energy System Analysis
Full text linkLong-duration energy storage (LDES) is essential for efficiently harnessing renewable energy. While electrochemical energy storage technologies have been increasingly deployed, they often face challenges due to high costs and limited mineral resources. Thermal Energy Storage (TES) offers a promising, cost-effective, and location-independent solution for LDES by storing energy as heat in inexpensive materials. A dynamic TES simulation tool within Flownex was developed to predict the TES outlet temperature for varying inlet conditions within a typical combined heat and power (CHP) system. The application of the dynamic TES model was demonstrated by successfully simulating the transient behaviour of a gas turbine cogeneration system for a 950°C gas turbine inlet temperature and ~18h TES energy storage duration. The model was used to evaluate the economic viability of a TES gas turbine cogeneration system compared to a lithium-ion (Li-ion) battery system for delivering the same output. An economic comparison over a 30-year project lifespan highlights the advantages of TES for LDES
Modeling of an High-Concentration Solar Reactor for Dry Methane Reforming
Full text linkDirect solar-powered reforming of methane has the potential to lower the CO2 footprint of reforming and to harvest solar energy with high-efficiency [1]. Combined with bio-sourced feedstock and recycled CO2 to perform dry methane reforming (DMR), this approach can highly decrease methane reforming environmental impact [2]. Using high solar concentration solar towers or parabolic dishes to provide the highly endothermal reaction heat required for DMR, it is possible to reach the temperatures of conventional reformers, ranging from 800°C up to 900°C. At this temperature, radiation losses are such that high solar concentrations approaching 1000x are required to reach high thermal efficiency, making heat flux management highly challenging. Previous work from Université de Sherbrooke experimentally shown the potential for such reactors to operate under high heat flux [3],[4]. The current work presents the modeling approach used to design these reactors and increase the heat flux within the absorption surface, while maintaining reasonable temperature drop within the reactor. Dimensional analysis if first assess that no diffusion limitation occurs within the reactor and the system can be simulated as a plug flow reactor with porous catalyst. Using DMR and RWGS kinetics from literature with 2D modeling in COMSOL Multiphysics, temperature and reaction rates along the reactor are evaluated showing consistency with experimental values. Parametrical analysis shows that optimal catalyst channels width appears to be equal or under 0.5 mm. Finally, it is demonstrated that optimal conversion occurs when around 1/3 of the catalytic bed is covered with metallic conductive fins. Over this value, increased conductivity gains are overpassed by the lowering of catalyst volume within the conduction chamber
CST4ALL - Support to the Activities of the Concentrated Solar Thermal Technology Area of the SET Plan
Full text linkThe Concentrated Solar Thermal Technologies (CST) sector has struggled with high-costs associated with Concentrated Solar Power (CSP) plants in Europe over the past decade. Moreover, CSP has largely been viewed only as a flexibility provider for electricity systems. To address these challenges, the CST4ALL project promotes a range of hybridization and cooperation initiatives at the intersection of CST and other renewable energy technologies, drawing on the work of various European Technology & Innovation Platforms (ETIPs). CST4ALL aligns closely with current EU priorities- such as Smart Sector Integration, Fit for 55, and Clean Energy Transition Partnership (CETP)-as well as national energy strategies. It seeks to offer solutions to pressing issues related to decarbonisation and energy security. The key outcome is a series of workshops engaging both industry and research and development (R&D) communities, fostering interaction among stakeholders at key technology interfaces with the CST sector. By analysing both industrial and R&D perspectives, CST4ALL aims to expand the network of active stakeholders in the CST Implementation Working Group (IWG) under the SET Plan and to raise awareness of CST’s potential role in sustainable energy mix. This paper outlines the project’s main activities to support the European Commission’s cross sector approach – encouraging public and private investment in R&D and establishing the political and regulatory framework needed to implement the new CST Implementation Plan (IP) from October 2022 to March 2024
Topcon Solar Modules: UV Degradation in Lab and Field Conditions
Full text linkThe UV degradation of TOPCon solar modules with different material compositions (BOM) was investigated and correlated in both field studies and accelerated aging laboratory tests. A UV treatment with 120 kWh/m² leads to significant power losses ranging from 1.3% to 13.7%, indicating a strong dependence on the specific material composition. Furthermore, it was found that additional degradation occurs beyond 120 kWh/m². Electroluminescence images (EL images) of laboratory UV-degraded modules show a characteristic checkerboard pattern indicative of UV-induced degradation (UVID). Additional degradation occurred during storage, which was partially reversible when the modules were re-irradiated.
After nine months in a ground-mounted system in Forst/Brandenburg, power losses of up to 2.4% were detected. Notably, this degradation was slightly lower than expected from UV-induced degradation tests (UVID) conducted in the laboratory. The EL images of field modules also displayed the characteristic checkerboard pattern, indicating that the UV degradation measured in the laboratory poses a real risk to the long-term stability of TOPCon modules in the field.
Due to the small number of modules examined, the statistical significance of the study is limited. Nevertheless, the results provide evidence of UV degradation of TOPCon modules under field conditions