Ingenieurwissenschaften

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Loss Characterisation of Additively Manufactured Windings for Aerospace Propulsion Motors
(New York, N.Y. : IEEE, 2026) Habte Tesfamikael, Hadish; Ahmadi Darmani, Mostafa; Murataliyev, Mukhammed; J.M. Hague, Richard; Gerada, Chris; Degano, Michele
This study presents an electrical loss characterisation of laser powder bed fusion (LPBF) additively manufactured copper windings for aerospace propulsion motors (APMs). Limited manufacturing flexibility in conventional processes restricts the realisation of optimised three-dimensional conductor geometries, whereas metal additive manufacturing (AM) can relax these constraints; however, the electrical performance of AM windings must be demonstrated to be comparable to that of conventionally manufactured windings before AM-enabled benefits can be exploited. 2D finite-element analysis (FEA) is employed to evaluate the influence of temperature and current excitation on AC copper losses, while 3D FEA is used to quantify end winding impact and to decompose the dominant AC loss components. Experimental measurements on an LPBF edgewise coil mounted on a stator and benchmarked against a commercially manufactured edgewise coil validate the modelling approach and demonstrate comparable loss behaviour for the investigated geometry. The results indicate the suitability of AM for rapid prototyping and tailored winding manufacture; however, application-ready deployment still requires insulation and thermal/dielectric qualification. In the present prototype, interlayer insulation is provided using Kapton tape as a laboratory solution.
Performance Analysis of High Power Density Propulsion Motors Under Various PWM Strategies
(New York, NY : IEEE, 2025-10) Habte Tesfamikael, Hadish; Ahmadi Darmani, Mostafa; Murataliyev, Mukhammed; Wang, Meiqi; Gerada, Chris; Degano, Michele
Compared to conventional three-phase machines, multi-three-phase machines are more susceptible to the adverse effects of voltage pulses introduced by pulse-width modulation (PWM) techniques. This increased sensitivity leads to higher current harmonics, resulting in increased machine losses, current distortion, and mechanical vibration. This paper presents a comprehensive investigation into the high-frequency harmonic losses induced by PWM in a voltage-fed electric machine. A circuit-level simulation framework is performed to evaluate the voltage excitation and the resulting current responses of the motor-inverter system under various PWM strategies. The analysis incorporates field-oriented control (FOC) with the synchronous frame PI current controller, ensuring consistent computational effort and control fidelity across all modulation schemes. To maintain a balanced trade-off between simulation accuracy and computational efficiency, the study combines finite element analysis (FEA) for machine loss estimation with a circuit-based approach for predicting PWM-induced current ripple. An in-depth electromagnetic loss breakdown is carried out to pinpoint the dominant sources of high-frequency losses. Two well established PWM techniques, known for their distinct current distortion profiles, are evaluated across a range of switching frequencies, machine operating speeds, and modulation indices. The analysis emphasizes their impact on current waveform quality and high-frequency loss behavior in the context of aerospace propulsion systems.
Comparing Load-Forecasts of Residential Heatpumps with Transformer and XGB on Field Data
(Graz : Technische Universität Graz, 2026-02-11) Lüdecke, Marcel; Justi, Timon; Meinert, Michel; Engel, Bernd
Accurate device-level forecasting of residential heat pump power consumption is a key enabler for advanced Prosumer energy management, yet forecasting performance is often limited by user-driven variability and incomplete measurement data. This work examines day-ahead forecasting of individual air-source heat pumps at 15-minute resolution using a large field dataset from 308 devices, combining lagged load, weather, and calendar features. A globally trained XGB model, locally trained XGB and Transformer models, and benchmark methods (linear regression and 24 h persistence) are comparatively evaluated with respect to R2, normalized RMSE, and a peak error metric. Results reveal pronounced performance heterogeneity across devices, with the global XGB model achieving R2 > 0.8 and nRMSE < 0.05 for series with regular daily peaks, but negative R2 and large peak errors for highly irregular time series. Transformers do not consistently outperform XGB and tend to overfit to noisy data despite considerable model capacity and training effort. Feature ablation experiments identify lagged load values as the dominant predictors and indicate that temperature and periodic features alone yield poor forecasts. Generalization analyses show that models trained on time series with consistent patterns transfer reasonably well to unseen, regular time series, whereas models calibrated on irregular time series generalize poorly and are sometimes inferior to persistence, highlighting the central role of the intrinsic load structure in forecastability. The findings underscore that, in the studied setting, robust, computationally efficient tree-based ensembles remain competitive with deep learning methods.
Residential Photovoltaic Generation Forecast via Long Short-Term Memory and Transformer
(Graz : Technische Universität Graz, 2026) Lüdecke, Marcel; Oppermann, Elias; Meinert, Michel; Engel, Bernd
Accurate short-term photovoltaic (PV) power forecasting is increasingly important for maximizing on-site self-consumption and ensuring reliable grid integration as decentralized PV deployment grows. This paper presents a systematic comparison of Long Short-Term Memory (LSTM) and Transformer-based architectures for deterministic short-term PV power forecasting using exclusively publicly available data from multiple climatic regions. The dataset combines multi-year 15-minute PV power measurements from nine plants with corresponding meteorological variables, and it is followed by a unified preprocessing pipeline that includes outlier treatment, interpolation, feature scaling, and correlation-based feature selection. Several feature subsets and input window lengths are evaluated, and Bayesian hyperparameter optimization is employed to refine model configurations for both architectures. The results indicate that using all meteorological variables except cloud coverage with a 2-day input window yields the best performance. Under this configuration, the Transformer model outperforms the LSTM model, achieving on average test errors of MSE = 0.0038 and MAE = 0.0265, compared to 0.0055 and 0.0343 for the LSTM, respectively. An analysis of time-resolved residuals shows that both models exhibit the largest errors around noon, while the Transformer provides a consistently narrower error distribution over the diurnal cycle. These findings highlight the advantages of attention-based sequence modeling for PV applications and offer practical guidance on feature design, input horizon selection, and hyperparameter ranges for future data-driven PV forecasting studies.
Netzzustandsüberwachung in Smart Grids: Analyse des Datenverbrauchs intelligenter Messsysteme
(Graz : Technische Universität Graz, 2026) Niehs, Eike; Essers, Julien; Engel, Bernd
Netzzustandsüberwachung in elektrischen Verteilnetzen erfolgt in Deutschland zukünftig auf Grundlage von Momentanwerten aus Ortsnetzstationen und von intelligenten Messsystemen an den Netzanschlusspunkten. Zur Übermittlung der Netzzustandsdaten intelligenter Messsysteme wird der Tarifanwendungsfall 10 der Technischen Richtlinie TR03109 des Bundesamtes für Sicherheit in der Informationstechnik umgesetzt. In diesem Zusammenhang untersuchen wir die Frage, welches Datenaufkommen bei Variation des Messintervalls und der Anzahl verschiedener Messwerte zu erwarten ist. Unser Testaufbau umfasst dabei ein vollwertiges intelligentes Messsystem, sowie die notwendigen Softwaresysteme zu dessen Betrieb. Die Ergebnisse zeigen, dass bei allgemein vorgesehener minütlicher Messwertübermittlung ein Datenvolumen von 1,5 GB bis 10,8 GB erreicht wird.
Heimspeicher nach dem Solarspitzengesetz 2025: Bewertung des techno-ökonomischen Potenzials der MiSpeL-Festlegung
(Graz : Technische Universität Graz, 2026) Wagner, Henrik; Schlüpmann, Jan; Engel, Bernd; Weyer, Hartmut
Stationäre Batteriespeichersysteme kleiner 30 kWh, sogenannte Heimspeicher, dominieren gegenwärtig die installierte Batteriespeicherleistung (13,2 GW von 16,4 GW) und Batteriespeicherkapazität (19,6 GWh von 24,5 GWh) in Deutschland. Die bislang übliche Einfachnutzung der Heimspeicher zur Eigenverbrauchserhöhung schöpft ihr techno-ökonomisches Potenzial nicht vollständig aus. Um diese ungenutzten Potenziale durch eine gezielte Marktaktivierung zu erschließen, wurden mit dem Solarspitzengesetz 2025 neue rechtliche Rahmenbedingungen geschaffen. Die Rahmenbedingungen sollen durch eine ergänzende Festlegung (MiSpeL) der Bundesnetzagentur, die Ende 2025 im Entwurf zur Konsultation gestellt wurde, auch in der Praxis nutzbar gemacht werden. Dieser Beitrag bewertet das techno-ökonomische Potenzial der profitoptimierten Mehrfachnutzung (Revenue- oder Value-Stacking) von Heimspeichern als konkrete Ausprägungsform dieser Marktaktivierung vor dem Hintergrund der genannten Neuregelungen. Mithilfe eines mathematischen Optimierungsmodells werden die in § 19 EEG definierten Optionen – Ausschließlichkeits-, Abgrenzungs- und Pauschaloption – hinsichtlich ihres Ertragspotenzials in einer Mehrfachnutzung der Anwendungen Eigenverbrauchserhöhung, Intraday-Handel und Primärregelleistung untersucht. Die Simulationsergebnisse auf Basis historischer Marktdaten der Jahre 2023 und 2024 zeigen, dass alle untersuchten EEG-Optionen in einer Mehrfachnutzung den ökonomischen Ertrag für Prosumer gegenüber der reinen Einfachnutzung steigern. Den signifikantesten Mehrwert für Heimspeicher bietet die Pauschaloption (§ 19 Abs. 3c EEG). Zwar führt die Anwendung von Pauschalen zu rechnerischen Abweichungen bei der förderfähigen Netzeinspeisung, jedoch werden die daraus resultierenden Erlösminderungen durch andere Kostenvorteile überkompensiert. Maßgeblich sind hierbei das vorteilhafte Verhältnis von saldierungsfähiger Netzeinspeisung zu abgabenbelastetem Netzbezug sowie das vereinfachte Messkonzept bzw. der Entfall eines zusätzlichen Zählers im Vergleich zur exakten Erfassung. Die Abgrenzungsoption (§ 19 Abs. 3b EEG) ermöglicht zwar eine präzise messtechnische Erfassung und weitreichende Abgabenbefreiung, bleibt jedoch aufgrund der höheren Messkosten ökonomisch hinter der Pauschaloption zurück. Auch die Ausschließlichkeitsoption (§ 19 Abs. 3a EEG) ermöglicht trotz technischer Einschränkungen deutliche Ertragssteigerungen gegenüber der Einfachnutzung bei Teilnahme am Intraday-Handel. Die Ergebnisse belegen, dass die neuen rechtlichen Rahmenbedingungen wirksame Anreize für die Marktintegration von Heimspeichern setzen und somit die Bereitstellung von Flexibilitäten für ein klimaneutrales Energiesystem fördern.
Tagungsband zum 9ten BIH-Treffen
(Hannover : Technische Informationsbibliothek, 2026-03-03) Steinkuhl, Anika; Gadischke, Cedric; Glenn, Nathalie; Bender, Tom; Albes, Jonah; Thanh Le-Vu, Vivien; Meckmann, Frank Felix; Lengert, Kay; Lengert, Kay
Vom 27. bis zum 29. August fand die neunte Fachtagung für wissenschaftliche Beschäftigte und Nachwuchskräfte an Bauingenieur-Institutionen der Hochschulen (kurz: BIH-Treffen) bei uns an der Hochschule für angewandte Wissenschaften in Kiel statt. Das BIH-Treffen bietet eine hervorragende Möglichkeit zu fachlichem und persönlichem Austausch unter den wissenschaftlichen Mitarbeitenden der HAWs. In diesem Rahmen werden Fachbeiträge zu aktuellen Forschungsthemen, Anwendungen aus Labor und Praxis und innovative Ausbildungsmethoden präsentiert. Das BIH-Treffen wurde bereits im Jahr 2016 von der Hochschule Ruhr West in Mülheim an der Ruhr ins Leben gerufen. Die ersten Treffen fanden in Mülheim an der Ruhr (2016), Gießen (2017) und Köln (2018) statt. Das vierte Treffen wurde in Dresden (2019) ausgerichtet, gefolgt von Veranstaltungen in Frankfurt am Main (2021), Bielefeld (2022), Berlin (2023) und Mainz (2024).
Complex estimation of mechanical properties of SLM-printed gyroid AlSi10Mg structures – experimental and FE analysis
(Durham, NC : Research Square, 2025-12) UI Hassan, Shaheer; Hussain Shah, Mazahir; Parma, Slavomir; Stefan, Jan; Pesek, Ludek; Chomat , Miroslav
Gyroid triply periodic minimal surfaces (TPMS) structures are vastly considered for thermal applications as they provide better surface to volume ratio and ensure mechanical properties. Its properties are significantly influenced by cell size, printing process, printing direction and volume fraction. To ensure the mechanical strength of the design, accurate stress measurements need to be done. TPMS structures do not behave the same as conventional structures or lattice structures due to their continuous curvature and nonlinearity. To evaluate accurate properties of TPMS structures, complex finite element approaches are needed. This study introduces complex finite element methods to evaluate accurate properties of the TPMS structures. Gyroid structures were also 3d-printed and tested to validate the simulation results. These structures were printed with varying printing direction and varying volume fractions using the selective laser melting (SLM) process. Surface roughness of the samples was recorded before and after post-processing. Tensile and compression tests were performed to investigate the impact of varying volume fraction and printing direction on mechanical behavior. Important finding of this paper is the precise and experimentally validated finite element method that could evaluate accurate mechanical properties of TPMS structures. Based on experimental data, predictive equations are designed which could predict the properties of the gyroid structure for any volume fraction.
Calculations for Functional Safety : Quantities, Formulas and Methods
(Hannover : Technische Informationsbibliothek, 2025-11-29) Brunnengräber, Thomas
Whereas in the past, functional safety hardly played a role in many industries, and in the others was essentially ensured by detailed design rules, driven by (negative) experiences, today the trend is moving away from fixed design rules to quantitative requirements and evidence. This undoubtedly promotes innovation and competition, but it also carries the risk of unsafe systems entering the market. The practice of the author as an assessor for functional safety shows again and again, that even experienced safety engineers find it difficult to perform correct calculations. This is often caused by a lack of understanding of the different variables, but just as often it is also due to a lack of knowledge about the calculation tools and methods used (especially FTA tools), coupled with an unjustifiably high level of trust in them. This introduction is primarily intended for prospective and experienced safety engineers, but also to mathematicians or computer scientists, who are entrusted with the development of calculation tools. Reference is occasionally made to standards, however, knowledge of these standards is not presumed. First, the parameters availability, reliability, failure density, failure rate, distribution functions, and MTTF, along with their mathematical foundations and dependencies, are presented in detail, and their practical significance is explained with examples. Then, it is shown how these parameters can also be calculated for complex systems using fault trees and Markov models.
Berechnungen zur Funktionalen Sicherheit : Größen, Formeln und Methoden
(Hannover : Technische Informationsbibliothek, 2025-11-29) Brunnengräber, Thomas
Während in der Vergangenheit die funktionale Sicherheit in vielen Branchen kaum eine Rolle spielte, und in den übrigen im Wesentlichen durch detaillierte Design-Regeln gewährleistet war, getrieben durch (negative) Erfahrungen, geht heute der Trend weg von festen Design-Regeln hin zu quantitativen Forderungen und Nachweisen. Dies fördert zweifellos die Innovation und den Wettbewerb, birgt jedoch das Risiko, dass unsichere Systeme auf den Markt kommen. Die Praxis des Autors als Gutachter für funktionale Sicherheit zeigt immer wieder, dass es selbst erfahrenen Sicherheitsingenieuren schwer fällt, korrekte Berechnungen anzustellen. Oft ist dafür mangelndes Verständnis der unterschiedlichen Größen ursächlich, genauso oft aber auch mangelnde Kenntnisse über die verwendeten Berechnungswerkzeuge und -methoden (insbesondere FTA-Tools), gepaart mit ungerechtfertigt großem Vertrauen in selbige. Diese Einführung richtet sich in erster Linie an angehende und erfahrende Sicherheitsingenieure, aber auch an Mathematiker oder Informatiker, welche mit der Entwicklung von Berechnungswerkzeugen betraut sind. Es wird gelegentlich Bezug auf Normen genommen, jedoch wird die Kenntnis dieser Normen nicht vorausgesetzt. Es werden zunächst die Größen Verfügbarkeit, Zuverlässigkeit, Ausfalldichte, Ausfallrate, Verteilungsfunktionen und MTTF und deren mathematische Grundlagen und Abhängigkeiten ausführlich dargestellt und deren praktische Bedeutung mit Beispielen erläutert. Dann wird gezeigt, wie diese Größen auch für komplexe Systeme mittels Fehlerbäumen und Markov-Modellen berechnet werden können.
Tin/Tin Oxide Nanostructures: Formation, Application, and Atomic and Electronic Structure Peculiarities
(Basel : MDPI, 2023-08-22) Liu, Poting; Sivakov, Vladimir
For a very long period, tin was considered one of the most important metals for humans due to its easy access in nature and abundance of sources. In the past, tin was mainly used to make various utensils and weapons. Today, nanostructured tin and especially its oxide materials have been found to possess many characteristic physical and chemical properties that allow their use as functional materials in various fields such as energy storage, photocatalytic process, gas sensors, and solar cells. This review discusses current methods for the synthesis of Sn/SnO2 composite materials in form of powder or thin film, as well as the application of the most advanced characterization tools based on large-scale synchrotron radiation facilities to study their chemical composition and electronic features. In addition, the applications of Sn/SnO2 composites in various fields are presented in detail.
Peculiarities in thermal transport of nanostructured silicon arrays with different morphology
([London] : Springer Nature, 2025-08-26) Sivakov, Vladimir; Liu, Poting; Chepela, Lesia; Lishchuk, Pavlo; Nkenfack, Isibert Marcel; Mandrolko, Viktor; Chaynes, Hadrien; Kuzmich, Andrey; Borovyi, Mykola; Lacroix, David; Isaiev, Mykola
This study explores the thermal conductivity of nanostructured porous silicon with different morphology produced by metal-assisted chemical etching of silicon wafers with different dopants, doping levels and crystallographic orientation. The wide range of morphological structures observed in the samples strongly depends on the initial wafer characteristics, a factor that cannot be neglected. While previous studies have demonstrated the qualitative capabilities of photoacoustic and Raman spectroscopy in characterizing nanostructured silicon, our work highlights the quantitative discrepancies that can arise when combining these techniques to investigate thermal properties. The differences in the results obtained using these methods can be attributed to the distinct nature of the information they provide: photoacoustic spectroscopy probes the effective thermal conductivity over larger areas, whereas Raman spectroscopy offers localized measurements. Furthermore, our Monte Carlo simulations provide insights into the morphological features of porous silicon that influence the interpretation of experimental data. This study underscores the importance of a comprehensive approach, combining both experimental and theoretical methods, to accurately assess the thermal transport properties of nanostructured materials.
Peculiarities in XPS spectra of Sn/SiO2 layers as an effect of surface charge
(Amsterdam [u.a.] : Elsevier, 2024-05-04) Liu, Poting; Freiberg, Katharina; Grinter, David C.; Sivakov, Vladimir
X-ray photoelectron spectroscopy based on synchrotron radiation was used to investigate the composition of the observed SnO2-x/Sn:SiO2-x thin layer grown by organometallic chemical vapour deposition on single-crystalline silicon wafer with additional argon ions etching treatment. Due to the formation of a thermodynamic anomaly during in situ layer growth, an efficient oxygen exchange between silicon and tin oxide phases occurs. The present study addresses the effect of localized surface charging and its influence on the obtained XPS core level spectra. We found that due to the high electrical conductivity of metallic tin and the direct coupling of tin particles to the silicon wafer, the XPS Sn 3d5/2 core level spectrum is not affected by the surface charge compared to the highly charged dielectric silicon oxide matrix, as observed for the XPS O 1 s and Si 2p core level spectra. Our results show that the core level spectra of Si 2p and O 1 s are shifted up to 3 eV due to the presence of uncompensated positive charge on the surface of the silica matrix. These results provide insight into the influence of surface charge effects on the analysis of conductor/insulator composite materials and contribute to the application of Sn-based materials in various application concepts related to energy and surface functionalization.
NEXAFS spectral peculiarities in Sn:SiO2 composite layer
(Amsterdam [u.a.] : Elsevier, 2025-06-23) Sivakov, Vladimir; Liu, Poting; Freiberg, Katharina; Yadav, Shivani; Grinter, David C.; Makarova, Anna
Synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been used to investigate a novel Sn:SiO2 composite thin layer grown by organometallic chemical vapor deposition technique (CVD) on a single crystalline silicon wafer with additional treatment by argon ions. According to a previously reported thermodynamic anomaly, an efficient exchange of oxygen between the silicon and tin dioxide surfaces occurs during the growth of the metal oxide thin layer. The present study focuses on the visualization of the atomic and electronic structure of tin nanostructures localized in silica matrix. It is found that no significant chemical alterations are observed during argon ions treatment of the initial composite layer. The removal of atmospheric residues, which partially passivated defects in the highly defective SnO2-x top layer, did not significantly change the initial NEXAFS Sn M4,5 edge spectrum. Based on these results, we found that the main state in which tin nanoparticles localized in the amorphous silica matrix is the metallic state. In addition, based on the NEXAFS Si L2,3-edge studies, we found that silica is most associated with the stoichiometric structure of thermally deposited SiO2 layer with the presence of silicon suboxides. These results provide insights into the atomic and electronic structure of Sn:SiO2 composites and contribute to the possible implementation of such materials in various application concepts related to thermal energy storage and novel photonic devices.
Raman and fluorescence micro-spectroscopy applied for the monitoring of sunitinib-loaded porous silicon nanocontainers in cardiac cells
(Lausanne : Frontiers Media, 2022-08-09) Tolstik, Elen; Sivakov, Vladimir; Lorenz, Kristina; Gongalsky, Maxim Bronislavovich; Dierks, J.; Brand , T.; Pernecker , Moritz; Pervushin, Nikolay V.; Maksutova , D. E.; Gonchar, Kirill Aleksandrovich; Samsonova, J. V.; Kopeina, Gelina; Osminkina, Liubov A.
Nanomaterials are a central pillar in modern medicine. They are thought to optimize drug delivery, enhance therapeutic efficacy, and reduce side-effects. To foster this technology, analytical methods are needed to validate not only the localization and distribution of these nanomaterials, but also their compatibility with cells, drugs, and drug release. In the present work, we assessed nanoparticles based on porous silicon (pSiNPs) loaded with the clinically used tyrosine kinase inhibitor sunitinib for their effectiveness of drug delivery, release, and toxicity in colon cancer cells (HCT 116 cells) and cardiac myoblast cells (H9c2) using Raman micro-spectroscopy, high-resolution fluorescence microscopy, along with biological methods for toxicological effects. We produced pSiNPs with a size of about 100 nm by grinding mesoporous silicon layers. pSiNPs allowed an effective loading of sunitinib due to their high porosity. Photoluminescence properties of the nanoparticles within the visible spectrum allowed the visualization of their uptake in cardiac cells. Raman micro-spectroscopy allowed not only the detection of the uptake and distribution of pSiNPs within the cells via a characteristic silicon Raman band at about 518–520 cm−1, but also the localization of the drug based on its characteristic molecular fingerprints. Cytotoxicity studies by Western blot analyses of apoptotic marker proteins such as caspase-3, and the detection of apoptosis by subG1-positive cell fractions in HCT 116 and MTT analyses in H9c2 cells, suggest a sustained release of sunitinib from pSiNPs and delayed cytotoxicity of sunitinib in HCT 116 cells. The analyses in cardiac cells revealed that pSiNPs are well tolerated and that they may even protect from toxic effects in these cells to some extent. Analyses of the integrity of mitochondrial networks as an early indicator for apoptotic cellular effects seem to validate these observations. Our study suggests pSiNPs-based nanocontainers for efficient and safe drug delivery and Raman micro-spectroscopy as a reliable method for their detection and monitoring. Thus, the herein presented nanocontainers and analytical methods have the potential to allow an efficient advancement of nanoparticles for targeted and sustained intracellular drug release that is of need, e.g., in chronic diseases and for the prevention of cardiac toxicity.
Multi-Material Topology Optimization for IPM Machine with Efficient Rare-Earth PM Utilization
(New York, NY : IEEE, 2025-10-14) Mahmoud, Mohamed Reda; Ibrahim, Mohamed N.; Sergeant, Peter
This paper presents a multi-material topology optimization (TO) to efficiently utilize rare-earth permanent magnet (REPM) material and improve the machine performance. The proposed approach employs a density-based TO method to optimize the multi-material distribution inside the rotor domain. The TO algorithm optimally redistributes air, silicon-steel, and REPM. The objective function of the TO is to maximize the average torque of the IPM motor while constraining the material volume of both silicon-steel and REPM to below that utilized in the conventional design. The results demonstrate that multi-material TO is a highly effective strategy for developing a new generation of sustainable electric machines. The topology optimized configuration achieved an approximate 4% increase in torque density while reducing the amount of REPM used by 12.5%. Moreover, the amount of silicon steel required for the optimized rotor is 9% lower than the conventional design.
Topology Optimization for Enhancing Electric Machine Performance: A Review
(New York, NY : IEEE, 2024-09-01) Mahmoud, Mohamed Reda; Ibrahim, Mohamed N.; Sergeant, Peter
Exploring the design space is essential in the pursuit of developing high-performance and power-dense electric machines. This article explores the transformative potential of topology optimization (TO) in enhancing the performance of electric machines. Conventional techniques for optimizing the design of electric machines use optimization algorithms to determine geometric variables within a predefined range. However, these methods are limited by manufacturing constraints and the designer's expertise in parameterization. On the other hand, topology optimization aims to enhance the performance of electric machines by manipulating the distribution of materials as a design factor. The enhancement is facilitated by additive manufacturing (AM), particularly via the manufacturing of intricate metal parts. In this paper, the main concepts of topology optimization in electric machines are reviewed. Firstly, the requirement for topology optimization is illustrated, and both the achievements and challenges of this technique over the traditional parametric optimization are described. Then, a description is given of different topology optimization methods that were reported in the literature. Finally, the development opportunities of this technology are shown in the electric machine design field.
Topology Optimization for a Magnetic Actuator Using Different Gradient-Based Solvers
(New York, NY : IEEE, 2025-01-13) Mahmoud, Mohamed Reda; Ibrahim, Mohamed N.; Sergeant, Peter
This paper presents a comparative study on the performance of density-based topology optimization using different gradient-based solvers. Three common solvers are employed: the method of moving asymptotes (MMA), interior point optimizer (IPOPT), and sparse nonlinear optimizer (SNOPT). The gradient solvers are compared regarding the convergence behaviour, computational time, and solution quality, i.e. maximizing the attractive force, when topology optimization is used to design a magnetic actuator as a case study. The results provide valuable insights into the strengths and limitations of MMA, IPOPT, and SNOPT in solving topology optimization and offering guidance for selecting the appropriate solvers. The results proved that SNOPT is suitable for largescale problems as it has fast convergence and low computation time compared to MMA and IPOPT solvers. Further, IPOPT is not suitable for large-scale problems due to high computation time and large amounts of intermediate materials, i.e. regions where the density function differs from 0 and 1. Moreover, the quality of the optimal solution is only slightly affected by the used solver.
Reducing AC Joule Losses in Hairpin Windings of Electric Machines: Strategies for Minimizing Losses Due to Radial and Tangential Flux
(New York, NY : IEEE, 2025-10-22) Bekele, Yitbarek; Korolova, Olga; Biebighäuser, Andreas; Akbar, Siddique; Ebrahimi, Amir; Ponick, Bernd
This paper presents a comprehensive analysis of conductor design strategies to reduce joule losses in hairpin windings of high-speed permanent magnet synchronous machines (PMSMs). With the increasing demand for high torque density, efficiency, and high-speed operation in electric vehicles and aircraft, minimizing these losses is crucial. Starting with a reference winding layout, various loss mechanisms due to radial and tangential flux components are investigated using finite element analysis (FEA) under both no-load and short-circuit conditions. Design variants including adjustments to conductor geometry, slot opening shapes, layer-specific conductor height tuning and segmented conductor designs with overhang twisting are explored. The findings are relevant for improving the performance and manufacturability of electric machines, with additive manufacturing offering new design opportunities for enhanced efficiency and lower losses.
The Evolution and Future of Composite Construction in Light Aircraft
(Hannover : Technische Informationsbibliothek, 2025) Wu, William
Within this study the historical development, current applications and future topics of light aircraft construction shall be analyzed. It describes the evolution of used materials and construction methods starting from traditional materials such as wood and aluminum to advanced composite materials. Furthermore, the different types of composite materials and construction methods are categorized, their advantages and disadvantages are discussed. The implementation in current aircraft models by leading manufacturers such as Diamond Aircraft, Cirrus, and Elixir is presented. Further, the challenges that likely arise with the adoption of advanced composites in general aviation are discussed and finally emerging trends and technologies that may be adapted in future aircraft construction are described.

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