Offenburg University of Applied Sciences
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Pre- and post-pyrolysis treatments in biochar-based fertilization
No full textBiochar is produced by pyrolysis of biomass and applied to soil for carbon sequestration. Its application further aims to improve crop yield in agriculture and to reduce nutrient leaching and soil-borne nitrous oxide (N2O) emissions. Still, little is known if these co-benefits attributed to high, but uneconomic biochar application rates can be observed when using biochar as biochar-based fertilizer (BBF), a combination of biochar and fertilizer in one product, resulting in low biochar application rates to soil of ~1-5 t ha-1 season-1. In this thesis, BBF production methods applied before (pre-) or after (post-) pyrolysis were elucidated on their effects on the pyrolysis process, biochar properties and agricultural performance. An underlying aim of this work was to investigate the extent to which wood ash as pyrolysis additive can increase biochar yields and how BBF production methods, mainly granulation and liquid fertilizer-enrichment, affect agronomic performance of low biochar application rates to soil.
Biomass was amended with wood ash before pyrolysis, aiming to recycle ash-derived nutrients and to increase dry and ash-free biochar yield. Ash amendment was most effective to elevate biochar yield when applied to woody biomass while negative effects were observed for gramineous biomass. Results from pilot-plant scale were confirmed by pyrolysis on industrial scale, which has the potential to reduce biochar production costs.
Wood ash and pyrolysis feedstocks like marine biomass can be enriched with chlorine, potentially leading to biochar contamination with polychlorinated aromatic hydrocarbons (PCB+PCDD/F), a largely unexplored topic in biochar production. In pyrolysis experiments performed in this thesis, the use of chlorine-rich feedstock did not increase PCB+PCDD/F contamination of biochar above limit values set in the European Biochar Certificate, enabling biochar producers to use chlorine enriched additives and biomass in the future.
Impacts of different post-pyrolysis treatments on crop growth, nutrient leaching and soil-borne N2O emissions were studied in greenhouse experiments. Biochar, liquid enriched with fertilizer and applied concentrated in the root-zone at low dosage (~1 t ha-1), increased yields of white cabbage by up to 21% compared to fertilized soil without a biochar amendment. The underlying mechanisms remained unclear; a better nutrient supply might have occurred due to BBF application directly below seedlings.
A further focus was on the preparation of granulated BBF. It was hypothesized that the close contact of fertilizer and biochar after granulation reduces the nutrient release rate from BBF leading to decreased nutrient leaching and soil-borne N2O emissions. Granulated BBF reduced nutrient leaching by up to 35% in sandy loam, similar to non-granulated biochar. Still, higher crop yields compared to non-amended soil were only observed with non-granulated biochar co-applied with fertilizer, which was associated with immobilization of macronutrients in granulated BBF. In silt loam, granulated BBF increased nitrogen leaching by 32% compared to non-amended soil, highlighting that BBF application strategies need to be adapted to soil types. Soil borne N2O emissions were not reduced with a low biochar application rate resulting from granulated BBF amendment (~1 t ha-1). However, reductions could occur after repeated use over several years.
Lastly, acidification of biochar was studied as a tool to reduce nitrate (NO3-) leaching from soil. Citric acid treated and NO3--enriched biochar reduced NO3- leaching more effectively than non-acidified biochar in a greenhouse experiment with sandy loam. Still, unintended side-effects of citric-acid treatment, like decreased macronutrient uptake in spinach and an increase in soil pH, potentially due to decarboxylation of citrate, make this method unsuitable for BBF application. Further, nitric acid was used for acidification to systematically study sorption mechanisms of NO3- to biochar at soil relevant pH (pH 5 and pH 7) by avoiding interference with competing anions, such as citrate. Previous research reported increased NO3- sorption at higher biochar production temperature and at decreased in equilibration pH, which was confirmed by the experiments in this thesis, but so far, sorption mechanisms remained unclear. The experiments in this thesis indicated that NO3- sorption at soil relevant pH is dominated by sorption to protonated, condensed aromatic structures of biochar. Nitric-acid enriched BBF amended to LUFA standard soils reduced NO3- leaching by up to 20% in soil with pH below 6 while leaching from soil with neutral pH was only marginally affected compared to non-amended soil.
The most consistent effect of using low biochar application rates applied as BBF in this thesis was an averaged 42 ± 16% reduction in nitrogen leaching from sandy soil, which likely enabled BBF-induced increases in crop yields by 14 ± 12% following leaching events across different experiments. In absence of leaching, crop yields were changed by +5 ± 9% across all greenhouse experiments, here, significant differences to non-treated soil could only be rarely observed.
This thesis highlighted the potential of wood ash as an additive in biomass pyrolysis and established a basic understanding on contamination of biochar with PCB+PCDD/F. Further, BBF application at low biochar application rate to soil has the potential to reduce nutrient leaching from soil while reductions in N2O emissions and increases in crop yields are uncertain, which needs to be further studied under field conditions
Multi-Stakeholder Contract Governance for Medical Data Access Using Distributed Ledgers
No full textAbstract—The secure and controlled access to medical data is a critical challenge in modern clinical research. Regulatory frameworks such as the GDPR and the EU AI Act impose strict requirements on data access, privacy, and transparency, making conventional data-sharing processes inefficient and administratively burdensome. Our proposed HyperAccess platform aims to digitise and streamline the contractual access management of medical data through Hyperledger Fabric, an enterprise-grade, permissioned blockchain framework. The project introduces a semi-automated access control system that minimizes administrative efforts while maximizing trust among stakeholders, including data holders, data owners, and data users. By employing exclusive channels on Hyperledger Fabric, only stakeholders involved in an agreement are part of the dedicated channel. This paper presents the design principles, technological framework, and potential impact of HyperAccess on multicentre clinical research, offering a scalable, privacypreserving, and practically validated solution through an initial prototypical implementation
Development of a Digital Twin for LIVARSA Efficiency Filter
No full textWith the increasing demand for energy efficiency and power quality in industrial and commercial electrical systems, innovative solutions are required to mitigate harmonic distortions and optimize power consumption. This thesis focuses on developing a digital twin for the LIVARSA Efficiency Filter, a transformer-based passive filter that enhances electrical efficiency by reducing harmonic distortions, improving power factor, and minimizing reactive power losses. The study integrates real-world experimental data with advanced simulation models using MATLAB Simulink and LTspice, ensuring accurate representation of the filter performance under diverse conditions. Comprehensive measurements and parameter extractions were conducted to model the transformer, including inductance, capacitance, leakage parameters, and coupling coefficients. The simulation results were validated against real world measurement data, demonstrating the effectiveness of the filter in achieving up to 6% energy savings. By bridging theoretical modelling with experimental validation, this research lays the foundation for integrating digital twin technology into industrial power quality solutions, ultimately contributing to sustainable and energy efficient electrical infrastructures
Die Entwicklung der Content-Erstellung auf Social-Media
No full textIm Rahmen der Bachelorarbeit wurden Experteninterviews durchgeführt, um die Forschungsfrage zu beantworten, welche Herausforderungen und Chancen sich aus dem Einsatz von KI bei der Content-Erstellung im Social-Media-Marketing ergeben. Ziel war es, herauszufinden wie KI-Tools genutzt werden und welchen Einfluss KI auf den Prozess der Content-Erstellung hat. Zunächst wurde mithilfe von Fachliteratur grundlegendes Wissen gesammelt, um tief in die Materie des Social-Media-Marketings, KI und Content-Erstellung einzutauchen. Auf Basis der Literaturgrundlage wurden Experteninterviews mit Agenturen aus Deutschland vorbereitet, welche KI im Contenterstellungsprozess einsetzen. Die Experteninterviews wurden qualitativ und halbstrukturiert durchgeführt, um differenzierte Antworten zu erhalten und flexibel Nachfragen stellen zu können. Die Antworten der Probanden unterscheiden sich in einigen Punkten, dennoch lassen sich einige Erkenntnisse ableiten. Der Einsatz von KI führt im Bereich der Content-Erstellung zu einer gesteigerten Effizienz, ermöglicht Hyperpersonalisierung und reduziert repetitive Aufgaben zunehmend. Dadurch kann man die gewonnene Zeit für kreative und zwischenmenschliche Aufgaben nutzen. Zu den Herausforderungen von KI zählen der Datenschutz, Rechtssicherheit und die Intransparenz der KI-Programme. Zudem zeigt die Arbeit, dass KI als wertvoller Sparringspartner dienen kann, der die Qualität der Arbeit im Agenturalltag bereichert. Je besser die KI mit internen Informationen trainiert wird, desto größer wird der Einfluss auf den Erstellungsprozess
Intelligente Elektroniksysteme für automatisierte Fahrzeuge und nachhaltige Mobilitätskonzepte
No full textIm Projekt AI4CSM bearbeitet die HSO schwerpunktmäßig das Teilvorhaben „Robustes Antriebssystem für gemeinsame, verknüpfte Mobilität“
Prosthetic limbs
No full textAlthough compensating for the loss of body parts through the use of biomechatronic systems presents a significant engineering challenge, well-designed prosthetic devices have immense potential for enhancing the quality of life of their users. This chapter provides an introduction, a review of recent technologies, and a deeper insight into prosthetic limbs. It also outlines the current demographic and societal situation and developments. Biomechanical fundamentals concerning musculoskeletal function, its modeling, and experimental studies are described to provide a solid basis for understanding manipulation and locomotion using prosthetic devices. A detailed discussion of general technical requirements outlines the challenges faced by prosthetic engineers and indicates their relation to the users’ perspectives. Upper- and lower-limb prosthetic systems are discussed in depth, which includes all biomechatronic subsystems, such as mechanical systems, actuators, sensors, controls, and user interfaces. Typical categories of amputations are introduced and the characteristics of passive, semiactive, and active/powered devices are discussed. Finally, approaches to systematically consider users’ needs and experiences in prosthetic engineering and visions of possible long-term developments are presented
Circular economy from macro to micro: National impact, corporate strategies and digital engagement
No full textThis PhD thesis analyzes the effects of the circular economy (CE) on sustainable development (SD), environmental performance and corporate reputation. The research employs a multi-level approach, analyzing CE at macroeconomic, meso-economic, and microeconomic levels using both well-known indicators and novel data sources such as social media analytics. Chapter 1 evaluates the relationship between CE strategies—renewable energy, reuse and sharing, repair and remanufacturing, and recycling—and their effects on SD in 25 European countries from 2010 to 2019. Using principal component analysis (PCA) and panel data methodology, the study finds that CE strategies correlate with lower unemployment (social dimension), reduced greenhouse gas (GHG) emissions (environmental dimension), and higher GDP per capita (economic dimension). However, the effects vary: renewable energy and reuse/sharing significantly reduce environmental impact, while recycling has negligible effects, and repair activities unexpectedly increase emissions. Chapter 2 assesses CE relevance in German companies through LinkedIn data. The study tracks CErelated company profiles across Germany’s 16 federal states, revealing a 36.34% increase in CE-active firms within one year. The analysis highlights that industries such as environmental services, management consulting, and IT play a crucial role in CE adoption. However, a predominant focus on recycling emerges, despite its limited macroeconomic impact. Chapter 3 extends the LinkedIn analysis to CE professionals across Austria, Cyprus, Germany, and Greece. A dataset of 3,245 profiles provides insights into demographic characteristics, specializations, job positions, and employers. The findings show that men tend to use more keywords in their profiles, correlating with higher follower counts. Additionally, over 500 unique job titles related to CE are identified, with key employers including BASF (Germany) and the Circular Economy Alliance (Cyprus). Chapter 4 explores the microeconomic effects of CE strategies on corporate environmental performance and reputation. Based on a panel dataset of 67 multinational companies across 12 countries from 2015 to 2023, the results show that renewable energy adoption enhances both environmental performance (lower emissions, reduced energy consumption) and corporate reputation. In contrast, recycling improves energy efficiency but does not significantly impact emissions or reputation. The study also highlights the risks of sustainability policies that fail to yield tangible environmental benefits while strengthening corporate reputation, underscoring the potential for greenwashing. This thesis contributes to CE and business research by integrating macro-, meso-, and micro-level analyses. It provides empirical evidence that CE can drive sustainable development but emphasizes the need for a holistic approach beyond recycling. The research also offers practical implications for companies and policymakers, advocating for stricter sustainability regulations and more comprehensive CE strategies to maximize economic, environmental, and reputational benefits
Aufbau einer Additiven Fertigung von Edelstahl
No full textIn dieser Arbeit wird der Aufbau einer Additiven Fertigung von Edelstahl nach Anlehnung an die VDI-Richtlinie 3405 dargestellt. Die additive Fertigung bietet die Möglichkeit zur Bauteiloptimierung in Form von Gewichtsreduktion, Steifigkeitoptimerungen und der Herstellung von beweglichen Baugruppen ineinander. Die Aufgabenstellung der Abhandlung umfasst die Arbeitsabläufe für den Pre-, In-, und Postprozess unter Einbezug der Maschinenperipherie zu erstellen, die Teilautomatisierung der Stützstrukturen und die Umsetzung von Hilfskonstruktionen für die Maschinenperipherie. Die Ausgangssituation im Unternehmen wird betrachtet, ebenso das Fertigungsverfahren PBF-LB/M mit der dazugehörigen Prozesskette. In der Konzeption wird der Grund für die Vorschubeinrichtung der Metallbandsäge beschrieben, die Anforderungen und Methodiken für die Ausarbeiten der Arbeitspläne und der Teilautomatisierung der Stützstrukturen erläutert. Die Vorschubeinrichtung wird vollständig konstruiert, die Einzelteile werden gefertigt und die Baugruppe montiert. Die Arbeitsabläufe werden dargestellt und näher beschrieben. Die Teilautomatisierung der Stützstrukturen wird im Programm mit den Parametern umgesetzt und an den verschiedensten Bauteilen erprobt
Formbeständigkeit von Myzel-gebundenen Werkstoffen im 3D-Druck mit Ganoderma lucidum
No full textThe focus of the present work was the investigation of dimensional stability in 3D printing with mycelium-based materials. This material composite is made of wood fibers that are bound by mycelium growth. Hemp and coconut fibers were examined as materials for 3D-printing in order to evaluate their suitability for this purpose. In order for the material to be used for 3D-printing, binders and water must be added to make the ink extrudable. Different compositions of the printing paste were produced and the loss of shape after 3D-printing and after heat inactivation was compared. The results of the study showed that, compared to hemp fibers, coconut fibers effectively regulate moisture during cultivation. However, increased shrinkage was observed during heat inactivation due to the higher water content
Optimized Grasp Planning for Bin-Picking Robots with 2D and 3D Sensor Data
Get PDFBin-picking systems face challenges in fully emptying containers due to Collision risks in real-world scenarios. In this contribution, we present a grasp planning approach that combines 2D and 3D sensor data to ensure collision-free handling. The method is successfully tested on objects with eccentric centers of mass and is implemented directly on the robot’s control unit, eliminating the need for separate computing hardware