@article{SalamatOlzemElsbacheretal.2024, author = {Salamat, Babak and Olzem, Sebastian-Sven and Elsbacher, Gerhard and Tonello, Andrea M.}, title = {Global Multi-Phase Path Planning Through High-Level Reinforcement Learning}, volume = {3}, journal = {IEEE Open Journal of Control Systems}, publisher = {IEEE}, address = {Piscataway}, issn = {2694-085X}, doi = {https://doi.org/10.1109/OJCSYS.2024.3435080}, pages = {405 -- 415}, year = {2024}, abstract = {In this paper, we introduce the Global Multi-Phase Path Planning ( GMP3 ) algorithm in planner problems, which computes fast and feasible trajectories in environments with obstacles, considering physical and kinematic constraints. Our approach utilizes a Markov Decision Process (MDP) framework and high-level reinforcement learning techniques to ensure trajectory smoothness, continuity, and compliance with constraints. Through extensive simulations, we demonstrate the algorithm's effectiveness and efficiency across various scenarios. We highlight existing path planning challenges, particularly in integrating dynamic adaptability and computational efficiency. The results validate our method's convergence guarantees using Lyapunov's stability theorem and underscore its computational advantages.}, language = {en} } @article{SalamatBencicElsbacheretal.2023, author = {Salamat, Babak and Bencic, Daniel and Elsbacher, Gerhard and Seidel, Christian and Tonello, Andrea M.}, title = {Investigating Integral Reinforcement Learning to Achieve Asymptotic Stability in Underactuated Mechanical Systems}, volume = {9}, journal = {IEEE Robotics and Automation Letters}, number = {1}, publisher = {IEEE}, address = {New York}, issn = {2377-3766}, doi = {https://doi.org/10.1109/LRA.2023.3332556}, pages = {191 -- 198}, year = {2023}, language = {en} } @inproceedings{OlzemSalamatKienastetal.2023, author = {Olzem, Sebastian-Sven and Salamat, Babak and Kienast, Thomas and Drouven, Tim and Elsbacher, Gerhard}, title = {Aircraft Conceptualization and Analysis by Flight Simulation}, booktitle = {2023 IEEE Aerospace Conference}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-6654-9032-0}, doi = {https://doi.org/10.1109/AERO55745.2023.10115814}, year = {2023}, language = {en} } @unpublished{MuellerSchmittBottetal.2026, author = {M{\"u}ller, Simon Nikolaus and Schmitt, David and Bott, Christoph and Akbar, Shariq and Bayer, Peter and Schrag, Tobias}, title = {Operating thermal source networks - How supply temperature and ground exchange shape performance}, titleParent = {SSRN}, publisher = {Elsevier}, address = {Amsterdam}, doi = {http://dx.doi.org/10.2139/ssrn.6034530}, year = {2026}, language = {en} } @inproceedings{FrankeSlowikBurgeretal.2021, author = {Franke, Florian and Slowik, Thomas and Burger, Uli and H{\"u}hne, Christian}, title = {Numerical Investigation of Drone Strikes with Various Aircraft Targets}, pages = {AIAA 2022-2603}, booktitle = {AIAA SciTech 2022 Forum: January 3-7, 2022, San Diego, virtual}, publisher = {AIAA}, address = {Reston}, isbn = {978-1-62410-631-6}, doi = {https://doi.org/10.2514/6.2022-2603}, year = {2021}, language = {en} } @unpublished{SalamatMatternOlzemetal.2025, author = {Salamat, Babak and Mattern, Dominik and Olzem, Sebastian-Sven and Elsbacher, Gerhard and Seidel, Christian and Tonello, Andrea M.}, title = {GMP3: Learning-Driven, Bellman-Guided Trajectory Planning for UAVs in Real-Time on SE(3)}, publisher = {arXiv}, address = {Ithaca}, doi = {https://doi.org/10.48550/arXiv.2509.21264}, year = {2025}, abstract = {We propose GMP3, a multiphase global path planning framework that generates dynamically feasible three-dimensional trajectories for unmanned aerial vehicles (UAVs) operating in cluttered environments. The framework extends traditional path planning from Euclidean position spaces to the Lie group SE(3), allowing joint learning of translational motion and rotational dynamics. A modified Bellman-based operator is introduced to support reinforcement learning (RL) policy updates while leveraging prior trajectory information for improved convergence. GMP3 is designed as a distributed framework in which agents influence each other and share policy information along the trajectory: each agent refines its assigned segment and shares with its neighbors via a consensus-based scheme, enabling cooperative policy updates and convergence toward a path shaped globally even under kinematic constraints. We also propose DroneManager, a modular ground control software that interfaces the planner with real UAV platforms via the MAVLink protocol, supporting real-time deployment and feedback. Simulation studies and indoor flight experiments validate the effectiveness of the proposed method in constrained 3D environments, demonstrating reliable obstacle avoidance and smooth, feasible trajectories across both position and orientation. The open-source implementation is available at https://github.com/Domattee/DroneManager.}, language = {en} } @inproceedings{ReumSchmittSummetal.2024, author = {Reum, Tobias and Schmitt, David and Summ, Thorsten and Schrag, Tobias}, title = {Energetic Potential of Parallel Operation of Two Heat Sources in a Dual-Source Heat Pump}, booktitle = {International Sustainable Energy Conference - Proceedings}, editor = {Fink, Christian and Brunner, Christoph}, publisher = {TIB Open Publishing}, address = {Hannover}, issn = {2976-2030}, doi = {https://doi.org/10.52825/isec.v1i.1158}, year = {2024}, abstract = {Dual-source heat pumps can mitigate disadvantages of single source heat pumps: They have fewer geological requirements compared to ground-source heat pumps while having higher efficiencies compared to air-source heat pumps. Parallel operation of two heat sources can also make electric heaters for peak loads obsolete, leading to economic benefits in the operational costs. Parallel operation has not been analysed thoroughly at different evaporation temperature gradients. To address this gap in research, four possible interconnections of two heat sources were analysed using a refrigerant cycle simulation, two with similar and two with separate evaporation pressures. The energetic potential of each interconnection is evaluated and compared to single source operation with an air-source and a ground-source heat pump. The results showed that only the interconnections with separate evaporation pressure allowed significant reduction in evaporation power from the ground source. As expected, the efficiency - compared to single air-source operation - increased for all parallel interconnections but decreased compared to ground-source operation. Efficient peak load coverage with small ground-source collectors therefore requires a more complex interconnection of completely split evaporator branches at different evaporation pressures. While the efficiency and heating power compared to single ground-source operation decreased slightly (by 4\% and 6\%, respectively), the power load on the GSHX and ASHX reduced to about 54\% and 66\% compared to the corresponding single-source operation, respectively. This allows high efficiency at reduced GSHX size and ASHX noise emission. Additionally, this interconnection also allows increased flexibility for improved heat source management.}, language = {en} } @inproceedings{MuellerStrobelFaigletal.2024, author = {M{\"u}ller, Simon Nikolaus and Strobel, Rainer and Faigl, Markus and Schrag, Tobias}, title = {Analysis of Industrial 5GDHC System in Ingolstadt}, booktitle = {International Sustainable Energy Conference - Proceedings}, subtitle = {A Step Towards CO2-Neutral Industry}, editor = {Fink, Christian and Brunner, Christoph}, publisher = {TIB Open Publishing}, address = {Hannover}, issn = {2976-2030}, doi = {https://doi.org/10.52825/isec.v1i.1152}, year = {2024}, abstract = {This study comprehensively examines the technical manifestation and planning process for a shared thermal energy network at a 75-hectare industrial area in Ingolstadt. Unlike traditional systems, this (5GDHC) network showcases a smart integration of energy flows across 70 buildings with a yearly heating demand of around 17 GWh and a yearly cooling demand of around 35 GWh. The network spans over 9,100 meters of piping with diameters up to 800 mm. With thermal power from various sources including 1.8 MW waste heat from a data centre and potential for 10 MW from the Danube River, the system epitomizes a dynamic balance of heating and cooling demands. The paper itself examines the planning process of the system and encompasses topics such as defining energy requirements and load profiles, assessing potential energy sources and sinks for enhanced system efficiency, and analysing pipe and network design. Through this investigation, the study provides valuable insights towards a methodology to facilitate the successful implementation of future industrial 5GDHC systems, furthering the cause of sustainable energy.}, language = {en} } @article{BornschleglKreitleinBregullaetal.2015, author = {Bornschlegl, Martin and Kreitlein, Sven and Bregulla, Markus and Franke, J{\"o}rg}, title = {A method for forecasting the running costs of manufacturing technologies in automotive production during the early planning phase}, volume = {2015}, journal = {Procedia CIRP}, number = {26}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2212-8271}, doi = {https://doi.org/10.1016/j.procir.2014.07.103}, pages = {412 -- 417}, year = {2015}, abstract = {The running costs of production sites are a decisive factor in the overheads of automotive production. Because of this, it is important for many operators to decrease those costs in a sustainable way. Therefore, they try to reduce both the energy consumption costs of production systems, as well as their maintenance costs. However, most parts of the running costs are already determined during the very early phases of the product creation process. The approach in this paper shows how the decision for a specific manufacturing technology influences the factory costs. It is necessary to determine the life-cycle costs with regard to the manufacturing technology. Therefore, deep knowledge about the process itself and the support processes is required. This paper shows how cost relevant parameters can be identified and introduces a method to determine the prospective costs for maintenance and energy consumption in advance.}, language = {en} } @inproceedings{BornschleglDrechselKreitleinetal.2013, author = {Bornschlegl, Martin and Drechsel, Michael and Kreitlein, Sven and Bregulla, Markus and Franke, J{\"o}rg}, title = {A new Approach to increasing Energy Efficiency by utilizing Cyber-Physical Energy Systems}, booktitle = {Proceedings of the Eleventh International Workshop on Intelligent Solutions in Embedded Systems}, editor = {Kucera, Markus and Waas, Thomas}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-3-00-042899-9}, url = {https://ieeexplore.ieee.org/document/6664947}, year = {2013}, language = {en} } @article{JamesKillingerMutangaetal.2025, author = {James, Stuart Daniel and Killinger, Markus and Mutanga, Chiedza Ngonidzashe and Pirard, Romain and Einax, Mario and Huber, Matthias and Bader, Tobias}, title = {The hybrid renewable energy community approach (HyRECA): Synergising electricity access with bush encroachment mitigation in rural Southern Africa}, volume = {2026}, pages = {100136}, journal = {Renewable and Sustainable Energy Transition}, number = {9}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2667-095X}, doi = {https://doi.org/10.1016/j.rset.2025.100136}, year = {2025}, abstract = {Rural electrification and bush encroachment in Southern Africa have long been studied separately. Research shows that hybrid renewable energy systems (HRES) offer viable solutions for off-grid communities, and bush encroachment mitigation is widely recognised as an ecological priority. Using Jamataka, Botswana, as a case study, this study integrates both, asking under which conditions encroacher bush-based HRES are economically viable, which electricity access levels local populations can afford, and whether biomass utilisation contributes to mitigation. Findings indicate strong potential for bush-based HRES in off-grid areas, but competitiveness declines where low-cost grid electricity is available. Economic viability is examined through levelised cost of electricity (LCOE) across alternative HRES configurations. HOMER Pro® simulations indicate PV/biomass/battery systems are most cost-effective off-grid, achieving 100 \% renewable fractions, near zero CO₂ emissions, and LCOE of 0.246 \$/kWh. In grid-connected contexts without feed-in, PV/diesel/grid combinations dominate (LCOE 0.117 \$/kWh) due to low tariffs, but with higher emissions. A novel affordability analysis using household willingness to pay and the World Bank Multi-Tier Framework indicates that all households reach at least Tier 3 electricity access under grid-connected systems and >70 \% off-grid, supporting household-use of medium-power appliances. Sustainable biomass extraction clears ∼12 ha annually (∼120 t) in Jamataka, aiding bush encroachment mitigation. Upscaling indicates potential to electrify 1.35 million people in >900 bush-encroached villages across Botswana, Namibia, and South Africa, using <1 \% of encroached land - highlighting significant untapped potential. Future research should validate findings through geospatial modelling with high-resolution biomass data and spatially sensitive biomass cost models for region-wide planning.}, language = {en} } @unpublished{JamesKillingerMutangaetal.2025, author = {James, Stuart Daniel and Killinger, Markus and Mutanga, Chiedza Ngonidzashe and Pirard, Romain and Einax, Mario and Huber, Matthias and Bader, Tobias}, title = {The Hybrid Renewable Energy Community Approach (HyRECA): Synergising energy access, economic development, and ecosystem restoration in rural Southern Africa}, titleParent = {SSRN}, publisher = {Elsevier}, address = {Amsterdam}, doi = {https://dx.doi.org/10.2139/ssrn.5294413}, year = {2025}, language = {en} } @inproceedings{SanchezMoralesMembarthGaulletal.2019, author = {S{\´a}nchez Morales, Eduardo and Membarth, Richard and Gaull, Andreas and Slusallek, Philipp and Dirndorfer, Tobias and Kammenhuber, Alexander and Lauer, Christoph and Botsch, Michael}, title = {Parallel Multi-Hypothesis Algorithm for Criticality Estimation in Traffic and Collision Avoidance}, booktitle = {2019 IEEE Intelligent Vehicles Symposium (IV)}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-0560-4}, doi = {https://doi.org/10.1109/IVS.2019.8814015}, pages = {2164 -- 2171}, year = {2019}, language = {en} } @unpublished{SanchezMoralesMembarthGaulletal.2020, author = {S{\´a}nchez Morales, Eduardo and Membarth, Richard and Gaull, Andreas and Slusallek, Philipp and Dirndorfer, Tobias and Kammenhuber, Alexander and Lauer, Christoph and Botsch, Michael}, title = {Parallel Multi-Hypothesis Algorithm for Criticality Estimation in Traffic and Collision Avoidance}, publisher = {arXiv}, address = {Ithaca}, doi = {https://doi.org/10.48550/arXiv.2005.06773}, year = {2020}, language = {en} } @article{RufinoJuniorRivaSanseverinoGalloetal.2024, author = {Rufino J{\´u}nior, Carlos Ant{\^o}nio and Riva Sanseverino, Eleonora and Gallo, Pierluigi and Koch, Daniel and Diel, Sergej and Walter, Gero and Trilla, Llu{\´i}s and Ferreira, Victor Jos{\´e} and Benveniste, Gabriela and Kotak, Yash and Eichman, Joshua and Schweiger, Hans-Georg and Zanin, Hudson}, title = {Towards to Battery Digital Passport: Reviewing Regulations and Standards for Second-Life Batteries}, volume = {10}, pages = {115}, journal = {Batteries}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {2313-0105}, doi = {https://doi.org/10.3390/batteries10040115}, year = {2024}, abstract = {Greenhouse gas emissions from transportation harm the environment. In response to these environmental concerns, numerous countries encourage the adoption of electric vehicles (EVs) as a more environmentally friendly option than traditional gasoline-powered vehicles. Advances in battery technology have made batteries an alternative solution for energy storage in stationary applications and for electric mobility. Reduced lithium-ion batteries (LIBs) production costs due to economies of scale, electrode material and cell design developments, and manufacturing process improvements have driven this success. This trend is expected to increase the number of LIBs on the market that may be discarded in the environment at the end of their useful life if more sustainable alternatives are not technologically mature. This coming environmental concern can be mitigated by collecting wasted EV batteries, reconfiguring them, and reusing them for applications with less stringent weight, performance, and size requirements. This method would extend battery life and reduce environmental effects. The present work investigates the main regulatory structures of the second-life battery industry that require rules, technical standards, and laws. To achieve this objective, a systematic review was carried out following a strict protocol that includes identifying relevant studies, extracting data and information, evaluating, and summarizing information. This paper explains the primary rules and technical standards governing the second-life battery business. The findings highlight the need for universities, research institutions, and government agencies to evaluate the second-life battery industry objectively. This would enable the creation of new technological regulations and laws for this burgeoning industry.}, language = {en} } @unpublished{RufinoJuniorRivaSanseverinoGalloetal.2023, author = {Rufino J{\´u}nior, Carlos Ant{\^o}nio and Riva Sanseverino, Eleonora and Gallo, Pierluigi and Amaral, Murilo Machado and Koch, Daniel and Kotak, Yash and Diel, Sergej and Walter, Gero and Schweiger, Hans-Georg and Zanin, Hudson}, title = {A Comprehensive Review of EV Lithium-Ion Battery Degradation}, publisher = {Preprints}, address = {Basel}, doi = {https://doi.org/10.20944/preprints202306.0228.v2}, year = {2023}, abstract = {Lithium-ion batteries with improved energy densities have made understanding the Solid Electrolyte Interphase (SEI) generation mechanisms that cause mechanical, thermal, and chemical failures more complicated. SEI processes reduce battery capacity and power. Thus, a review of this area's understanding is important. It is essential to know how batteries degrade in EVs to estimate battery lifespan as it goes, predict, and minimize losses, and determine the ideal time for a replacement. Lithium-ion batteries used in EVs mainly suffer two types of degradation: calendar degradation and cycling degradation. Despite the existence of several existing works in the literature, several aspects of battery degradation remain unclear or have not been analyzed in detail. This work presents a systematic review of existing works in the literature. The results of the present investigation provide insight into the complex relationships among various factors affecting battery degradation mechanisms. Specifically, this systematic review examined the effects of time, side reactions, temperature fluctuations, high charge/discharge rates, depth of discharge, mechanical stress, thermal stress, and the voltage relationship on battery performance and longevity. The results revealed that these factors interact in complex ways to influence the degradation mechanisms of batteries. For example, high charge currents and deep discharges were found to accelerate degradation, while low temperatures and moderate discharge depths were shown to be beneficial for battery longevity. Additionally, the results showed that the relationship between cell voltage and State-of-Charge (SOC) plays a critical role in determining the rate of degradation. Overall, these findings have important implications for the design and operation of battery systems, as they highlight the need to carefully manage a range of factors to maximize battery performance and longevity. The result is an analysis of the main articles published in this field in recent years. This work aims to present new knowledge about fault detection, diagnosis, and management of lithium-ion batteries based on battery degradation concepts. The new knowledge is presented and discussed in a structured and comprehensive way.}, language = {en} } @article{HussenetherRufinoJuniorSelaibePiresetal.2026, author = {Hußenether, Thomas and Rufino J{\´u}nior, Carlos Ant{\^o}nio and Selaibe Pires, Tom{\´a}s and Mishra, Tarani and Nahar, Jinesh and Vaghani, Akash and Polzer, Richard and Diel, Sergej and Schweiger, Hans-Georg}, title = {Analysis of the Measurement Uncertainties in the Characterization Tests of Lithium-Ion Cells}, volume = {19}, pages = {825}, journal = {Energies}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en19030825}, year = {2026}, abstract = {The transition to renewable energy systems and electric mobility depends on the effectiveness, reliability, and durability of lithium-ion battery technology. Accurate modeling and control of battery systems are essential to ensure safety, efficiency, and cost-effectiveness in electric vehicles and grid storage. In engineering and materials science, battery models depend on physical parameters such as capacity, energy, state of charge (SOC), internal resistance, power, and self-discharge rate. These parameters are affected by measurement uncertainty. Despite the widespread use of lithium-ion cells, few studies quantify how measurement uncertainty propagates to derived battery parameters and affects predictive modeling. This study quantifies how uncertainty in voltage, current, and temperature measurements reduces the accuracy of derived parameters used for simulation and control. This work presents a comprehensive uncertainty analysis of 18650 format lithium-ion cells with nickel cobalt aluminum oxide (NCA), nickel manganese cobalt oxide (NMC), and lithium iron phosphate (LFP) cathodes. It applies the law of error propagation to quantify uncertainty in key battery parameters. The main result shows that small variations in voltage, current, and temperature measurements can produce measurable deviations in internal resistance and SOC. These findings challenge the common assumption that such uncertainties are negligible in practice. The results also highlight a risk for battery management systems that rely on these parameters for control and diagnostics. The results show that propagated uncertainty depends on chemistry because of differences in voltage profiles, kinetic limitations, and temperature sensitivity. This observation informs cell selection and testing for specific applications. Improved quantification and control of measurement uncertainty can improve model calibration and reduce lifetime and cost risks in battery systems. These results support more robust diagnostic strategies and more defensible warranty thresholds. This study shows that battery testing and modeling should report and propagate measurement uncertainty explicitly. This is important for data-driven and physics-informed models used in industry and research.}, language = {en} } @article{RufinoJuniorRivaSanseverinoGalloetal.2024, author = {Rufino J{\´u}nior, Carlos Ant{\^o}nio and Riva Sanseverino, Eleonora and Gallo, Pierluigi and Amaral, Murilo Machado and Koch, Daniel and Kotak, Yash and Diel, Sergej and Walter, Gero and Schweiger, Hans-Georg and Zanin, Hudson}, title = {Unraveling the Degradation Mechanisms of Lithium-Ion Batteries}, volume = {17}, pages = {3372}, journal = {Energies}, number = {14}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en17143372}, year = {2024}, abstract = {Lithium-Ion Batteries (LIBs) usually present several degradation processes, which include their complex Solid-Electrolyte Interphase (SEI) formation process, which can result in mechanical, thermal, and chemical failures. The SEI layer is a protective layer that forms on the anode surface. The SEI layer allows the movement of lithium ions while blocking electrons, which is necessary to prevent short circuits in the battery and ensure safe operation. However, the SEI formation mechanisms reduce battery capacity and power as they consume electrolyte species, resulting in irreversible material loss. Furthermore, it is important to understand the degradation reactions of the LIBs used in Electric Vehicles (EVs), aiming to establish the battery lifespan, predict and minimise material losses, and establish an adequate time for replacement. Moreover, LIBs applied in EVs suffer from two main categories of degradation, which are, specifically, calendar degradation and cycling degradation. There are several studies about battery degradation available in the literature, including different degradation phenomena, but the degradation mechanisms of large-format LIBs have rarely been investigated. Therefore, this review aims to present a systematic review of the existing literature about LIB degradation, providing insight into the complex parameters that affect battery degradation mechanisms. Furthermore, this review has investigated the influence of time, C-rate, depth of discharge, working voltage window, thermal and mechanical stresses, and side reactions in the degradation of LIBs.}, language = {en} } @article{SalamatMatternOlzemetal.2026, author = {Salamat, Babak and Mattern, Dominik and Olzem, Sebastian-Sven and Elsbacher, Gerhard and Seidel, Christian and Tonello, Andrea M.}, title = {GMP3: Learning-Driven, Bellman-Guided Trajectory Planning for AAVs in Real-Time on SE(3)}, volume = {14}, journal = {IEEE Access}, publisher = {IEEE}, address = {New York}, issn = {2169-3536}, doi = {https://doi.org/10.1109/ACCESS.2026.3661193}, pages = {22720 -- 22733}, year = {2026}, abstract = {We propose GMP3, a multiphase global path planning framework that generates dynamically feasible three-dimensional trajectories for unmanned aerial vehicles (UAVs) operating in cluttered environments. The framework extends traditional path planning from Euclidean position spaces to the Lie group SE(3), allowing joint learning of translational motion and rotational dynamics. A modified Bellman-based operator is introduced to support reinforcement learning (RL) policy updates while leveraging prior trajectory information for improved convergence. GMP3 is designed as a distributed framework in which agents influence each other and share policy information along the trajectory: each agent refines its assigned segment and shares with its neighbors via a consensus-based scheme, enabling cooperative policy updates and convergence toward a path shaped globally even under kinematic constraints.We also propose DroneManager, a modular ground control software that interfaces the planner with real UAVs platforms via the Micro Air Vehicle Link (MAVLink) protocol, supporting real-time deployment and feedback. Simulation studies and indoor flight experiments validate the effectiveness of the proposed method in constrained 3D environments, demonstrating reliable obstacle avoidance and smooth, feasible trajectories across both position and orientation.}, language = {en} } @article{WalterDielRufinoJunioretal.2024, author = {Walter, Gero and Diel, Sergej and Rufino J{\´u}nior, Carlos Ant{\^o}nio and Schweiger, Hans-Georg and Valente de Bessa, Iury and Mallmann, Ma{\´i}ra and Kirsten Vidal de Oliveira, Aline and Odilio Dos Santos, Daniel and R{\"u}ther, Ricardo}, title = {Operating Behavior of a Photovoltaic-driven Electrolysis System}, volume = {15}, journal = {Revista Brasileira de Energia Solar}, number = {1}, publisher = {ABENS}, address = {S{\~a}o Paulo}, issn = {2526-2831}, doi = {https://doi.org/10.59627/rbens.2024v15i1.456}, pages = {82 -- 92}, year = {2024}, language = {en} } @article{NgetunyBaldaufZoerner2026, author = {Ngetuny, Joshua Kiplagat and Baldauf, Tobias and Z{\"o}rner, Wilfried}, title = {Evaluating Feedstock Pretreatment Methods to Unlock Co-Digestion in Small-Scale Biogas Systems: A Multi-Criteria Approach to System Integration and Decision Making}, volume = {19}, pages = {1303}, journal = {Energies}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en19051303}, year = {2026}, abstract = {Small-scale biogas plants in developing countries present a viable alternative to traditional polluting energy sources, particularly in rural and underserved communities. These systems typically rely on locally sourced livestock manure; however, inconsistent supply often results in underfeeding, reduced biogas production, and, in many cases, system abandonment. Co-digestion with crop residues presents a promising strategy to enhance feedstock availability and system resilience. However, the recalcitrant nature of lignocellulosic biomass and limited access to suitable pretreatment technologies have constrained its adoption. This paper evaluates feasible pretreatment methods for integrating crop residues, especially straw, into small-scale biogas systems. Using the Analytic Hierarchy Process (AHP), pretreatment methods are assessed based on five criteria: (i) technology simplicity, (ii) energy requirements, (iii) capital and operational costs, (iv) effectiveness, and (v) environmental impact. The analysis identifies microbial pretreatment using the liquid fraction of digestate, combined with mechanical size reduction, as the most suitable approach for small-scale implementation, utilizing low-cost, simplified mechanical devices adaptable to various crop residues with minimal energy input. A conceptual design of a demonstration plant is proposed to validate this integrated pretreatment approach and assess its impact on biogas yield, system performance, and technology adoption. The design incorporates an on-site digestate separation unit to supply microbial inoculum and emphasizes simplicity and cost-effectiveness in material handling and energy use. Pilot trials are proposed to evaluate key performance indicators, including specific methane yield (LCH4/gVS added), volatile solids reduction (\%), and methane content increase (\%), ensuring evidence-based adoption and practical applicability of the design.}, language = {en} } @article{NgetunyBaldaufZoerner2025, author = {Ngetuny, Joshua Kiplagat and Baldauf, Tobias and Z{\"o}rner, Wilfried}, title = {Optimizing Feedstock Selection for Sustainable Small-Scale Biogas Systems Using the Analytic Hierarchy Process}, volume = {18}, pages = {1739}, journal = {Energies}, number = {7}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en18071739}, year = {2025}, abstract = {Small-scale biogas systems can play a pivotal role in sustainable energy provision, particularly in developing countries. However, their dependence on livestock manure as the only feedstock poses challenges to their adoption and long-term viability. This often leads to insufficient biogas production and plant abandonment. This study proposes co-digestion of livestock manure with other farm residues to enhance the technical sustainability of small-scale biogas systems by ensuring adequate and consistent biogas production throughout the plant's lifespan, minimizing the risks associated with reliance on a single feedstock. A novel feedstock selection approach is developed using the Analytic Hierarchy Process (AHP), a multicriteria decision-making method, to prioritize feedstocks based on adequacy, supply consistency, and logistical ease. AHP is chosen due to its capability to handle both quantitative and qualitative evaluation criteria. This approach is applied to the F{\`e}s-Mekn{\`e}s region of Morocco, which offers abundant livestock and crop residues alongside product utilization pathways. The prioritization and ranking of the potential feedstocks identified in the region reveals cattle manure as the top-ranked feedstock due to its consistent supply and ease of collection, followed by straw, valued for its storability and nutrient stability. Sheep, horse, and chicken manure ranked third, fourth, and fifth, respectively, while household food waste and fruit and vegetable residues, limited by seasonality and perishability, were ranked lower. Based on these findings, co-digestion of cattle manure and straw is proposed as a sustainable strategy for small-scale biogas plants in F{\`e}s-Mekn{\`e}s, addressing feedstock shortages, enhancing biogas production, and reducing plant abandonment. This approach strengthens technical sustainability and promotes the broader adoption of biogas technologies in developing countries.}, language = {en} } @article{AgricolaBaertlLandesbergeretal.2026, author = {Agricola, Barbara and B{\"a}rtl, Marko and Landesberger, Martin and Zhao, Huan and Palm, Frank and Kerschenlohr, Annegret and J{\"a}gle, Eric A.}, title = {The columnar to bimodal transition of Al-Cr-Mo-Sc-Zr alloys during laser powder bed fusion}, volume = {2026}, pages = {115770}, journal = {Materials \& Design}, number = {264}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0264-1275}, doi = {https://doi.org/10.1016/j.matdes.2026.115770}, year = {2026}, abstract = {Aluminium alloys processed via Powder Bed Fusion using a Laser Beam (PBF-LB) enable complex and lightweight components. Especially high-strength and heat-resistant Al alloys are in high demand for aerospace and motorsports applications, but the processability of these alloys remains critical due to hot-cracking along columnar grains. Therefore, the microstructural control of PBF-LB alloys is under increasing consideration. Al-Cr alloys have shown promising high-temperature properties and good processability in previous studies despite having a coarse and fully columnar grain structure. In this study, Al-Cr-Mo-Sc-Zr alloys with different compositions are subjected to phase analysis to understand the transition from fully columnar to bimodal grain structures. Synchrotron diffraction, electron dispersive spectroscopy, and atom probe tomography results have shown that three phases are present, irrespective of the alloys' composition: 𝛼-Al, Al45Cr7, and Al3(Sc,Zr). The introduction of Cr increases the lattice mismatch between 𝛼-Al and Al3(Sc,Zr) and is suspected to hinder grain refinement by Sc and Zr. Various thermodynamic simulations revealed the effect of grain refining elements (Sc+Zr) and Cr on the solidification path. The combination of simulation and experimental investigations led to three hypotheses on the columnar to bimodal transition in Al-Cr alloys. These results will help to further enable the microstructural control of PBF-LB processed alloys.}, language = {en} } @article{NgetunyHsaineMabroukietal.2025, author = {Ngetuny, Joshua Kiplagat and Hsaine, Jalal and Mabrouki, Abdelaalim and Rachidi, Fouad and El Asli, Abdelghani and Z{\"o}rner, Wilfried}, title = {Assessment of agricultural residues for small-scale biogas plants and adoption drivers: a case study of the F{\`e}s-Mekn{\`e}s region in Morocco}, volume = {15}, journal = {Biomass Conversion and Biorefinery}, number = {22}, publisher = {Springer}, address = {Berlin}, issn = {2190-6815}, doi = {https://doi.org/10.1007/s13399-024-06443-y}, pages = {29207 -- 29223}, year = {2025}, abstract = {Small-scale biogas systems hold promise as reliable renewable energy sources in developing nations; however, adequate and consistent supply of feedstock remains a challenge. Agricultural residue, due to their lack of competition with food crops for resources, is touted as a dependable feedstock choice. This article therefore examines agricultural residues as potential biogas plant feedstocks in the F{\`e}s-Mekn{\`e}s region of Morocco, using a structured farm survey to evaluate livestock types, crop varieties, and residue utilization. Additionally, the study explores the challenges and drivers influencing biogas technology adoption in Morocco. Findings indicate a predominance of small-scale farms with livestock (averaging 11 cattle, 45 sheep, and 20 chicken) and mainly subsistence crop production, making these farms suitable candidates for small-scale biogas plants. Key barriers to adoption include a lack of awareness about the technology, along with technical and financial constraints. However, raising awareness, establishing demonstration plants, and offering financial and non-financial incentives are identified as potential drivers of adoption. This research provides a foundation for implementing biogas technologies in the case study area and other developing nations, guiding researchers and governmental and non-governmental organizations in disseminating small-scale biogas systems as a reliable energy source and a method for converting agricultural residues into sustainable energy (biogas) and fertilizer. Graphical Abstract}, language = {en} } @article{VolpatodeSouzaPintoPereiraNeumeieretal.2025, author = {Volpato, Guilherme and de Souza Pinto Pereira, Adriano and Neumeier, Steffen and Hotza, Dachamir and G{\"o}ken, Mathias and Tetzlaff, Ulrich and Fredel, M{\´a}rcio Celso}, title = {Influence of a Standard Heat Treatment on the Microstructure and Properties of Inconel X-750 Produced by Laser Powder Bed Fusion}, volume = {27}, pages = {2500306}, journal = {Advanced Engineering Materials}, number = {24}, publisher = {Wiley}, address = {Weinheim}, issn = {1527-2648}, doi = {https://doi.org/10.1002/adem.202500306}, year = {2025}, abstract = {The production of nickel-base superalloys through powder bed fusion using a laser beam (PBF-LB) offers a promising method for reducing the cost of aeronautical components, especially those with complex geometries. However, when these materials are processed using PBF-LB, the standard heat treatments developed for conventional manufacturing routes do not consistently yield predictable microstructures or mechanical properties. Thus, this study analyzes how PBF-LB affects the microstructure and mechanical behavior of Inconel alloy X-750 when compared to a hot-rolled counterpart after undergoing a standard precipitation-hardening heat treatment (solution annealing, stabilization, and precipitation). Microstructure is examined using analytical electron microscopy and high-energy X-ray diffraction, while mechanical behavior is assessed through microhardness. Significant differences between both manufacturing routes are detected, so that PBF-LB processing led to an increase in grain size, anisotropy, fraction of low-angle grain boundaries, mean angle of misorientation, and dislocation density. Moreover, PBF-LB promoted the formation of γ′-Ni3(Al,Ti) and η-Ni3Ti phases during solution annealing and stabilization, respectively. Notably, the formation of γ′ contributes to an anomalous microhardness increase observed between these steps. These findings suggest that PBF-LB may inhibit recrystallization and facilitate precipitation during heat treatment, thereby affecting the performance of components produced using this technology.}, language = {en} }