Offenburg University of Applied Sciences
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Habituation does not change running economy in advanced footwear technology
No full textPurpose: This study aimed to compare running economy across habituated and nonhabituated advanced footwear technology (AFT) in trained long-distance runners.
Methods: A total of 16 participants completed up to six 5-minute trials in 1 to 3 pairs of their own habituated shoes and 3 different and standardized AFTs at individual marathon pace. We measured oxygen uptake and carbon dioxide production and expressed running economy as oxygen uptake (in milliliters oxygen per kilogram per minute), oxygen cost of transport (oxygen per kilogram per minute), energetic cost (in watts per kilogram), and energetic cost of transport (in joules per kilogram per kilometer). We used linear mixed-effect models to evaluate differences. Relative shoe weight and shoe mileage (distance worn during running) were covariates.
Results: Forty-eight standardized and 29 individual AFT conditions were measured (mileage 117.0 [128.8] km, range 0–522 km; 25 habituated 135.7 [129.2] km, range 20–522 km; 4 nonhabituated 0 [0] km, range 0–0 km). Rating of perceived exertion, blood [La], and respiratory exchange ratio ranged from 9 to 15, 1.11 to 4.54 mmol/L, and 0.76 to 1.01. There was no effect for habituation on energetic cost of transport (thabituation = −.232, P = .409, b = −0.006; 95% CI, −0.058 to 0.046) or other running economy metrics. Neither shoe weight nor shoe mileage had an effect.
Conclusions: Our results suggest that habituation to AFTs does not result in greater benefits in the use of AFTs. This means that implementation in training may not be needed, even if we cannot rule out any other possible benefits of habituation at this stage, such as adaptation of the musculoskeletal system
Prediction of PV Power Production with Neural ODEs on the base of Weather data
Get PDFPredicting energy production from photovoltaics (PV) is crucial for efficient energy management. In order to apply different operating strategies, it is necessary to predict the expected amounts of PV energy. The operating strategies are typically optimized with regard to economic or technical goals or a combination of both. Within this work, we show a possibility to predict PV power production using local weather data and Neural Ordinary Differential Equations (NODE). Based on the measured values from the PV system and an associated weather station, the NODE is trained and validated with regard to PV production. The measurement data are collected from the PV system of the former Campus North of Offenburg University of Applied Sciences
Individualized Technique Feedback for Instant Technique Improvements and Knee Abduction Moment Reductions – A New Approach for ‘Sidestepping’ ACL Injuries?
No full textBackground
Sidestep cutting technique is highly individual and has been shown to influence knee joint loading. However, studies assessing whether individualized technique feedback improves technique and ACL injury-relevant knee joint loads instantly in a sport-specific task are lacking.
Purpose
To determine the instant effects of individualized augmented technique feedback and instructions on technique and the peak external knee abduction moment (pKAM) in a handball-specific sidestep cut. Additionally, to determine the effects of technique modifications on the resultant ground reaction force and its frontal plane moment arm to the knee joint center.
Study Design
Controlled laboratory cohort study
Methods
Three-dimensional biomechanics of 48 adolescent female handball players were recorded during a handball-specific sidestep cut. Following baseline cuts to each side, leg-specific visual and verbal technique feedback on foot strike angle, knee valgus motion, or vertical impact velocity using a hierarchically organized structure accounting for the variables’ association with performance was provided. Subsequently, sidestep cuts were performed again while verbal instructions were provided to guide technique modifications. Combined effects of feedback and instructions on technique and pKAM as well as on the resultant ground reaction force and its frontal plane moment arm to the knee joint center were assessed.
Results
On average, each targeted technique variable improved following feedback and instructions, leading to instant reductions in pKAM of 13.4% to 17.1%. High inter-individual differences in response to feedback-instruction combinations were observed. These differences were evident in both the adherence to instructions and the impact on pKAM and its components.
Conclusion
Most players were able to instantly adapt their technique and decrease ACL injury-relevant knee joint loads through individualized augmented technique feedback, thereby potentially reducing the risk of injury. More research is needed to assess the retention of these adaptations and move towards on-field technique assessments using low-cost equipment.
Level of Evidence:
Level
The impact of fresh and used ankle taping on lower extremity biomechanics during sports specific movements
No full textThis study aimed to investigate the effects of ankle taping on lower extremity joint biomechanics. Kinetic and kinematic data were collected from 25 participants using 3D motion capturing and force platforms without shoes for running (RUN), drop jumping (DJ), and 180° change of direction (COD), in tape applied fresh (TF) and tape after sports-specific use (TU) conditions compared to a barefoot (BF) baseline. Taping conditions decreased peak ankle excursions and moments for the frontal and sagittal planes for some of the sports-specific movements. However, TF did not significantly alter the knee and hip moments in the frontal and sagittal planes. Reducing ankle excursion likely offers some protection to extreme joint ranges. To reduce restrictions imposed by fresh taping on the sagittal plane ankle ROM, applying ankle taping already during the pre-match warm-up might be useful
Harnessing Generative AI for Sustainable Innovation: A Comparative Study of Prompting Techniques and Integration with Nature-Inspired Principles
No full textAmidst growing environmental challenges and the imperative for sustainable solutions, this study explores how generative artificial intelligence (AI) can drive innovation in process engineering. It investigates the effectiveness of different prompting techniques and their integration with nature-inspired principles (NIP) in fostering sustainable innovation. The study employs a comparative methodology to assess the effectiveness of two distinct prompting techniques: basic and AI-automated prompting. It also examines the influence of integrating NIP derived from various natural ecosystems on the generated solutions. Experiments were conducted using a generative AI model and analysing the output, focusing on the number of unique and overlapping ideas. Furthermore, the quality of AI-generated solution concepts was evaluated using four parameters, such as feasibility, novelty, usefulness, and sustainability, each rated on a scale of 0 to 2. Three case studies within the process engineering domain were used, each representing a different problem-solving scenario. The results showed that the integration of NIP, particularly through the “one by one” strategy in AI-automated prompting, significantly increased the number of unique ideas compared to basic prompting, demonstrating its effectiveness in enhancing idea diversity and quality. Concepts generated through this approach also scored higher in novelty and sustainability, aligning with sustainable innovation goals. These findings have practical implications for developing innovative and sustainable engineering solutions, particularly in the early phases of design, offering insights into effective strategies for leveraging AI in eco-innovation
Influence of operating conditions on the aging of large-format lithium iron phosphate battery cells: From laboratory conditions to a home storage system
No full textThe installed energy capacity of renewable energy generation systems is increasing globally due to the implementation of decarbonization policies. Due to the unpredictable nature of renewable energy sources, there is frequently a mismatch between load demand and energy supply. Stationary energy storage systems act as a buffer that stores excessive energy to balance future energy shortcomings. For residential applications, battery energy storage systems (BESS) are an attractive solution to realize the self-sufficiency of a household equipped with photovoltaics. Despite the decrease in prices, battery costs are still the most significant part of the investment cost of battery energy storage systems. Therefore, estimating battery lifetime and developing operation strategies to hinder aging is essential for improving the feasibility of BESS.
Lithium iron phosphate (LFP) lithium-ion batteries are widely used for residential BESS because of their low cost, long life, and safety. Despite extensive research in the laboratory of small-capacity cells, there are few full-scale field investigations on the lifetime and aging characteristics of commercial BESS equipped with LFP cells. This Ph.D. thesis investigates the realistic aging behavior of a residential-scale BESS equipped with large-format (180 Ah) LFP cells. We aim to create and implement a method to investigate the practical aging on cell, stack, and system levels. The experimental data is also processed by degradation modes analysis to identify the underlying mechanisms of capacity loss.
Each cell underwent primarily detailed electrical characterization, which consists of measuring characteristic charge/discharge curves and internal resistances at different current rates and temperatures. After electrical characterization, exemplary cells were opened in an inert atmosphere glove-box for structural investigation, consisting of size and weight measurements of cell components. The morphology and chemical composition of electrode samples from opened cells were investigated with light microscopy (LM) and scanning electron microscopy (SEM). The results of the detailed initial characterization of single cells were used to create a complete and self-consistent parameter set for each cell. The initial dataset was also used to compare periodical performance test results with the initial aging state of single cells throughout aging experiments.
The realistic aging experiment was carried out by investigating for 1000 days the changes in aging indicators of two commercial, residential scale BESS integrated into a microgrid. The battery stacks of both systems were built with LFP cells from the same batch of detailed characterization cells but installed with different (serial and parallel) configurations. Thus, we could investigate the effect of stack architecture on aging comparatively. At the end of the measurements, it was observed that no stack architecture is superior to another despite different operating voltages and current levels. In parallel, two LFP cells (identical to the battery stack cells) were tested at constant ambient temperature (20 °C) with continuous complete charge/discharge cycles at a constant current higher than the maximum current exhibited by BESS cells. Regarding capacity retention by equivalent full cycles, both cells outperformed BESS stacks. The comparative cell, stack, and system-level aging investigations indicate that good thermal management can provide a better lifetime even under harsher operating conditions.
The individual effects of temperature and load profile on aging were investigated via single-cell experiments in controlled ambient temperature. For this purpose, six test groups of single cells were tested to represent three realistic aging scenarios (continuous cycling, fully charged storage, and partially charged storage) at two different ambient temperatures (35 °C and 50 °C). All cells tested at 50 °C aged faster than those tested at 35 °C according to periodical performance diagnostics. Continuous cycling increased capacity loss among the cells tested at the same ambient temperature compared to fully or partially charged storage.
Single-cell experiment data was analyzed using degradation mode analysis algorithms. The results demonstrate that the loss of lithium inventory, attributed to the irreversible loss of lithium due to continuous growth of the solid electrolyte interface (SEI) layer, is the primary aging mode in all cases.Die installierte Energiekapazität erneuerbarer Energieerzeugungssysteme nimmt weltweit zu aufgrund der Umsetzung von Dekarbonisierungsmaßnahmen. Infolge der Unbeständigkeit der erneuerbaren Energiequellen kommt es häufig zu einem Ungleichgewicht zwischen Lastnachfrage und Energieangebot. Stationäre Energiespeichersysteme dienen als Puffer, um überschüssige Energie zu speichern und somit eventuelle Energiedefizite auszugleichen. Für private Anwendungen sind Batteriespeichersysteme (BESS) eine attraktive Lösung, um die Autarkie eines mit Photovoltaik ausgestatteten Haushalts zu erreichen. Trotz des Preisrückgangs machen die Batteriekosten jedoch immer noch den größten Teil der Investitionskosten für BESS aus. Daher sind die Abschätzung der Batterielebensdauer und die Entwicklung von Betriebsstrategien zur Verhinderung von Alterungsprozessen von entscheidender Bedeutung für die Verbesserung der Wirtschaftlichkeit von BESS.
Lithium-Eisenphosphat (LFP) Lithium-Ionen-Batterien werden aufgrund ihrer geringen Kosten, langen Lebensdauer und Sicherheit häufig für BESS in Privathaushalten verwendet. Während zahlreiche Forschungsarbeiten mit Zellen geringer Kapazität im Labor durchgeführt werden, gibt es nur wenige groß angelegte Untersuchungen zur Lebensdauer und den Alterungseigenschaften kommerzieller BESS mit LFP-Zellen. Diese Doktorarbeit untersucht das realitätsnahe Alterungsverhalten eines haushaltsüblichen BESS, das mit großformatigen (180 Ah) LFP-Zellen ausgestattet ist. Ziel ist es, eine Methode zu entwickeln und zu implementieren, mit der die Alterung auf Zell-, Stack- und Systemebene untersucht werden kann. Die experimentellen Daten werden außerdem im Hinblick auf Degradationsmodi analysiert, um die zugrundeliegenden Mechanismen des Kapazitätsverlustes zu identifizieren.
Jede Zelle wurde zunächst einer detaillierten elektrischen Charakterisierung unterzogen, die aus der Messung der charakteristischen Lade-/Entladekurven und der Innenwiderstände bei unterschiedlichen Stromstärken und Temperaturen bestand. Im Anschluss an die elektrische Charakterisierung wurden einige exemplarische Zellen in einer Glovebox unter Inertgasatmosphäre geöffnet, um ihre Struktur zu untersuchen, wobei Größe und Gewicht der Zellkomponenten gemessen wurden. Die Morphologie und die chemische Zusammensetzung von Elektrodenproben aus den geöffneten Zellen wurden mittels Lichtmikroskopie und Rasterelektronenmikroskopie untersucht. Die Ergebnisse der detaillierten initialen Charakterisierung der Einzelzellen wurden zur Erstellung eines vollständigen und konsistenten Parametersatzes für jede Zelle verwendet. Der Referenzdatensatz wurde außerdem für den Vergleich der Ergebnisse periodisch durchgeführter Performancetests mit dem anfänglichen Alterungszustand der Einzelzellen während der Alterungsexperimente verwendet.
Das realitätsnahe Alterungsexperiment wurde durchgeführt, indem über einen Zeitraum von 1000 Tagen die Veränderungen der Alterungsindikatoren zweier kommerzieller, haushaltsüblicher BESS untersucht wurden, die in ein Microgrid integriert waren. Die Batteriestacks beider Systeme bestanden aus LFP-Zellen aus derselben Charge von Zellen, die der beschriebenen detaillierten Charakterisierung unterzogen wurden. Allerdings wurden sie in unterschiedlichen Konfigurationen (seriell und parallel) aufgebaut. Durch diesen Vergleich konnten Auswirkungen der Systemarchitektur auf die Alterung untersucht werden. Trotz unterschiedlicher Betriebsspannungen und Stromstärken konnte jedoch am Ende der Messungen keine vorteilhafte Systemarchitektur festgestellt werden. Zusätzlich wurden zwei LFP-Zellen (identisch mit den Batteriestack-Zellen) bei konstanter Umgebungstemperatur (20 °C) mit kontinuierlichen vollständigen Lade-/Entladezyklen mit konstantem Strom getestet, der höher als der maximal auftretende Strom der BESS-Zellen war. Hinsichtlich des Kapazitätserhalts bezogen auf äquivalente Vollzyklen übertrafen beide Zellen die BESS-Stacks. Die vergleichenden Alterungsuntersuchungen auf Zell-, Stack- und Systemlevel zeigen, dass ein gutes Wärmemanagement auch unter härteren Betriebsbedingungen zu einer längeren Lebensdauer führen kann.
Die individuellen Auswirkungen von Temperatur und Lastprofil auf die Alterung wurden anhand von Einzelzellenversuchen bei kontrollierter Umgebungstemperatur untersucht. Zu diesem Zweck wurden sechs Testgruppen von Einzelzellen bei zwei verschiedenen Umgebungstemperaturen (35 °C und 50 °C) getestet, um drei realistische Alterungsszenarien zu repräsentieren (kontinuierliches Zyklieren, vollständig geladene Lagerung und teilweise geladene Lagerung). Alle bei 50 °C getesteten Zellen alterten schneller als die bei 35 °C getesteten Zellen, wie die periodische Leistungsdiagnose ergab. Bei gleichen Umgebungstemperaturen erhöhte kontinuierliches Zyklieren den Kapazitätsverlust im Vergleich zur Lagerung mit vollständiger oder teilweiser Ladung.
Die Daten aus den Einzelzellexperimenten wurden mithilfe von Algorithmen zur Analyse der Degradationsmodi analysiert. Die Ergebnisse zeigen, dass der Verlust an zyklierbaren Lithium-Ionen (LLI), der auf den irreversiblen Verlust von Lithium aufgrund des kontinuierlichen Wachstums der passiven Grenzschicht (SEI) zurückzuführen ist, in allen Fällen der wichtigste Alterungsmodus ist
CAD-gestützter Bau und FEM-Analyse eines funktionalen Fußes für das historische Capua-Bein
No full textDie vorliegende Bachelorarbeit befasst sich mit der Konstruktion und FEM-Analyse eines Fußes passend zum Stelzfuß von Capua mit der CAD-Software Autodesk. Der Stelzfuß von Capua ist eine ca. 2300 Jahre alte Beinprothese, welche 1884/1885 bei einer Ausgrabung im historischen Capua/Kampanien gefunden wurde.
Da diese Arbeit an einer bereits bestehenden Bachelorarbeit anknüpft, bedarf es einiger Vorarbeit, um mit der Konstruktion zu beginnen. Da in der Ausgrabung 1884/1885 keine Fußprothese gefunden wurde, müssen vergleichbare historische Daten herangezogen werden. Zudem müssen die anthropometrischen Daten der bereits bestehenden Rekonstruktion des Stelzfußes angepasst werden.
Zudem wird die Fertigung mittels additiver Fertigung und die dort vorhandenen Materialien hinsichtlich der Nutzung in der Medizin betrachtet. Wie auch die Eignung derer durch eine Belastungsanalyse.The present bachelor thesis deals with the construction and FEM analysis of a foot corresponding to the Capua stilts foot using the CAD software Autodesk. The Capua stilts foot is a leg prosthesis approximately 2300 years old, which was found during an excavation in historic Capua/Kampanien in 1884/1885.
Since this work builds on an existing bachelor thesis, some preliminary work is required to begin the construction. As no foot prosthesis was found in the excavation of 1884/1885, comparable historical data must be used. In addition, the anthropometric data of the already existing reconstruction of the stilts foot must be adjusted.
Furthermore, the production using additive manufacturing and the materials available there are considered for use in medicine. As is the suitability of these through a stress analysis