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Breitbandige Laserkühlung relativistischer Ionenstrahlen: Erste Experimente und Weiterentwicklung des UV-Lasers
No full textDie Kühlung von Ionenstrahlen in Beschleunigerringen auf geringe relative Impulsverteilungen ist essentiell für präzise Experimente, insbesondere in der Spektroskopie und bei Kollisionsexperimenten. Etablierte Methoden wie die Elektronen- und die stochastische Kühlung stoßen bei hochrelativistischen, intensiven Ionenstrahlen aufgrund der stark verlängerten Kühlzeiten an ihre Grenzen. Eine Alternative bietet die Laserkühlung gebündelter Ionenstrahlen, die als einzige Kühlmethode am Schwerionensynchrotron SIS100 der FAIR-Beschleunigeranlage geplant ist. Laserkühlung von Ionenstrahlen wurde bereits an mehreren Anlagen demonstriert, etwa 2012 an relativistischen C³⁺-Ionenstrahlen mit einem schmalbandigen UV-Dauerstrichlaser am Experimentierspeicherring ESR des GSI Helmholtzzentrums für Schwerionenforschung.
Zur Kühlung mehrerer Ionengeschwindigkeitsklassen und zur Verringerung interner Aufheizprozesse wie des Intrabeam Scatterings ist bei schmalbandigen Dauerstrichlasern eine ständige Verstimmung der Laserfrequenz notwendig. Alternativ ermöglicht die für Kurzpulslaser typische große Frequenzbreite eine simultane Adressierung mehrerer Geschwindigkeitsklassen, wodurch breitbandige Laserkühlung realisiert werden kann. Dieses Prinzip wurde 2021 erstmals an hochenergetischen gebündelten C³⁺-Ionenstrahlen am ESR demonstriert. Zur Adressierung der Ionen wurde ein leistungsstarkes Lasersystem mit flexiblen Pulsdauern zwischen 50 ps und 735 ps und hohen Repetitionsraten von 1 MHz bis 10 MHz verwendet. Während gepulste Lasersysteme durch ihre breite Laserkraft mehrere Geschwindigkeitsklassen adressieren können, bleibt die finale Strahltemperatur höher als bei Dauerstrichlasern. Am SIS100 ist eine Kombination aus Dauerstrich- und zwei Kurzpulslasern mit unterschiedlichen Frequenzbreiten geplant, um die Vorteile aller Systeme zu vereinen.
Diese Arbeit beschäftigt sich mit der weiterführenden Analyse des Strahlexperiments zur breitbandigen Laserkühlung von gebündelten C³⁺-Ionenstrahlen. Der Fokus liegt auf der Auswirkung unterschiedlicher Frequenzbreiten des Pulslasers auf kontinuierliche Ionenstrahlen und der erstmaligen Demonstration der Laserkühlung gebündelter C³⁺-Ionenstrahlen mit kurzen Laserpulsdauern von 285 ps und 166 ps bei einer hohen Repetitionsrate von über 9 MHz. Zudem wird die Weiterentwicklung des gepulsten Lasersystems beschrieben, das hohe Durchschnittsleistungen und große Frequenzverstimmungen bietet, um den Anforderungen hochrelativistischer Ionenspezies am SIS100 gerecht zu werden. Durchschnittsleistungen von 5,3 W bei 257,25 nm und ein Verstimmbereich von 3,39 THz im UV-Bereich werden demonstriert, wobei eine Regelung mit aktiver Rückkopplung zur Optimierung der kritischen Phasenanpassung eingesetzt wird
The Circular Bioeconomy as a Regional Concept: Assessing the Regional Potential of Innovative Residue-Based Bioeconomic Technologies and their Prospective Life Cycle Environmental Impacts
No full textThe bioeconomy (BE) concept has gained considerable political interest in the past two decades and is promoted as an alternative to the current fossil-based economy with the aim of increasing sustainability. BE can be understood as a broad concept, including all sectors and systems that produce biological resources or use them to produce food, feed, bio-based products, bioenergy and services. It aims to ensure food and resource security, reduce dependence on fossil fuels, strengthen competitiveness, economic growth and job creation, while protecting the climate. However, there are increasing doubts as to whether the growing demand for biomass can be met sustainably. The expansion of cultivated land, intensification of primary production and increased biomass competition are associated with ecological and social risks. These include GHG emissions and biodiversity losses due to land use change, the eutrophication of fresh water and acidification of soils and increases in food prices. The circular bioeconomy (CBE) concept has been developed as a reaction to these problems and aims at an efficient and sustainable valorization of bio-resources. CBE is regarded as a concept that varies from region to region, especially when the focus is on the use of bio-residues, which are mostly traded on regional markets. Although the concept aims to improve sustainability, the actual sustainability benefits of CBE implementations have not been conclusively proven. Accordingly, to avoid unanticipated negative side-effects of large-scale CBE implementations, a thorough ex-ante assessment and planning of the CBE transition process under consideration of regional conditions is necessary.
This thesis presents a novel integrated assessment approach to support the planning and assessment of CBE implementation at regional level. It combines methodological guidelines for (1) the selection of CBE technologies for a region based on a comprehensive assessment of their regional potential for a successful sustainable implementation with (2) a regionalized, prospective and consequential life cycle assessment (LCA) of the selected CBE technologies. Under the umbrella of the integrated assessment approach, this thesis proposes novel methods and methodological advancements. The development of the methods and their partial application to case studies are outlined in three publications. The first publication develops from a comprehensive catalog of success criteria for CBE implementation and the discussion of the region-specificity of these criteria a matching approach for CBE technologies and regions. The multi-criteria structured approach enables the selection of CBE technologies, based on their potential for successful and sustainable implementation in a specific region. The second publication presents a novel method to quantify the overall bio-residue potential of a region, which is (a) comprehensive in terms of the bio-residue categories and source sectors covered, (b) applicable at the regional level, (c) suitable to quantify industrial bio-residues, and (d) based on openly available, regularly updated, consistently categorized statistical data. This publication also demonstrates the application of the developed method to three study regions: the Federal Republic of Germany (GER), the Frankfurt Rhine-Main metropolitan region (FRM) and the city of Frankfurt/Main (Ffm). In the third publication, a regionalized, prospective, consequential LCA is carried out for a case study on insect rearing on a feed substrate based on apple pomace. Along this case study, methodological advancements are proposed. These include guidance on how to integrate regional conditions related to the valorized by-product into consequential LCA and how to model the diversion of the by-product from its current utilization pathway. Furthermore, suggestions are made for streamlining an existing scheme for upscaling innovative technologies to an industrial scale for consideration in prospective LCA.
The discussion of the region-specificity of CBE success criteria shows that the majority of criteria are region-specific. Furthermore, the quantification of bio-residue potentials in GER, FRM and Ffm demonstrates significant differences between the study regions considering their characteristics as bio-residue suppliers. Differences occur in terms of the relevance of source sectors and residue categories, in the spatial densities of residue generation and the temporal trends of its annual generation. Accordingly, this thesis supports the notion of CBE as a highly regional concept and underscores the importance of reflecting regional conditions in effective CBE transition planning. The case study on bio-residue potentials further illustrates that the quantification of industrial bio-residues, which is often regarded as being possible to a limited extent for reasons of confidentiality, is feasible with a top-down approach based on waste factors, even at a high spatial resolution. However, the high spatial resolution is accompanied by uncertainties caused by data gaps and a high level of aggregation of the residue categories and source sectors. The analysis also shows that urban industrial bio-residues have meaningful potential due to their considerable spatial density. Finally, the LCA case study on insect rearing shows that the analyzed process chain still needs to be optimized to achieve a reduction of environmental impacts in most categories. Only regarding land use and eutrophication of fresh water, the replacement of soybean meal with black soldier fly larvae is advantageous. However, the identification of further optimization potential regarding an optimized composition of the feed substrate and the feeding rate shows that the upscaling underestimates the potential for environmental impact reduction in industrial implementation. Overall, the results indicate that this CBE technology has the potential to reduce environmental impacts in the long term. The LCA results also show that diverting a by-product from its current utilization pathway to a new one can contribute significantly to environmental impacts. It should therefore be considered in LCA models, as suggested in our methodological framework.
In light of the results of this thesis, which substantiate the regional nature of the CBE concept and show that the environmental performance of CBE implementations is not advantageous in any case, it is concluded that the planning of the CBE transition must be thoroughly accompanied by an integrated assessment, as proposed in this thesis, to guide the transition process in a sustainable direction
Automated material flow characterization of WEEE in sorting plants using deep learning and regression models on RGB data
No full textWaste from electrical and electronic equipment (WEEE) is a rapidly growing waste stream. Notably, electronic equipment contains valuable and critical raw materials. State of the art in WEEE recycling uses a combination of automated comminution and separation processes. To optimize these processes, analyzing material flow composition is essential, which today is performed by labor- and cost-intensive manual sampling and sorting. Automated analysis can be achieved through sensor-based material flow characterization (SBMC). However, this method has not yet successfully been applied for shredded WEEE. In a pilot-scale sorting plant, we developed a three-step SBMC method for shredded WEEE, based on cheap and widespread RGB cameras. Novel features of this approach are the combination of deep learning for material type identification, regression models for predicting individual particle masses, and aggregating the masses towards a material flow composition. First, YOLO v11 object detection performed best in identifying ferrous-metals, non-ferrous metals, printed circuit boards and plastics, reaching an [email protected] of 0.990. Next, geometry and color features were extracted for a total of 70 particle features. These data were used to train 11 types of regression models for particle mass prediction. K-nearest neighbors regression achieved a mean relative error of below 5 , calculating the material shares in the waste stream from predicted particle masses. Finally, the combined approach of YOLO and k-NN regression was used on a validation dataset, achieving 4.94. Our method can be applied in WEEE sorting plants to monitor and control processes or to analyze experiments
Wind turbine blade recycling for greener and sustainable wind energy
No full textThe rapid expansion of wind farms has led to a growing challenge: the escalating accumulation of decommissioned wind turbine blades in landfills. Addressing this issue through innovative recycling and reuse strategies is pivotal to advancing a circular economy within the wind energy sector
Phenomenological Prediction of the Band Diagram of Organic–Organic and Inorganic–Organic Heterointerfaces
No full textHerein, a phenomenological rule is presented for the estimation of electronic contact properties of organic–organic and inorganic–organic hetero interfaces, which is deduced from a large number of experimentally studied heterojunctions. The data for the present study are summarized from in situ step‐by‐step interface experiments using photoelectron spectroscopy. Organic and inorganic (oxide) materials are investigated which are used for the manufacturing of organic based optoelectronic devices in the InnovationLab Heidelberg. It is shown that the measured values of the interface dipole as well as of the band bending linearly depend on the work function difference between substrate and adsorbate. The data suggest that the investigated materials as technologically applied films contain a prototypical concentration of electron states at the interface and in the bulk, the charge of which is adjusted to reach thermodynamic equilibrium at a contact. As a consequence, a generally applicable empirical formula to predict the energetic band alignment due to dipole formation and the contact potential distribution due to band bending can be deduced, which is given by just the work function differences between the pristine layers. This result suggests that band bending as well as interface dipole formation are both attained by redistribution of electronic charge via integer charge transfer processes
Analyzing Gaze During Driving: Should Eye Tracking Be Used to Design Automotive Lighting Functions?
No full textIn this work, an experiment was designed in which a defined route consisting of country roads, highways, and urban roads was driven by 20 subjects during the day and at night. The test vehicle was equipped with GPS and a camera, and the subject wore head-mounted eye-tracking glasses to record gaze. Gaze distributions for country roads, highways, urban roads, and specific urban roads were then calculated and compared. The day/night comparisons showed that the horizontal fixation distribution of the subjects was wider during the day than at night over the whole test distance. When the distributions were divided into urban roads, country roads, and motorways, the difference was also seen in each road environment. For the vertical distribution, no clear differences between day and night can be seen for country roads or urban roads. In the case of the highway, the vertical dispersion is significantly lower, so the gaze is more focused. On highways and urban roads there is a tendency for the gaze to be lowered. The differentiation between a residential road and a main road in the city made it clear that gaze behavior differs significantly depending on the urban area. For example, the residential road led to a broader gaze behavior, as the sides of the street were scanned much more often in order to detect potential hazards lurking between parked cars at an early stage. This paper highlights the contradictory results of eye-tracking research and shows that it is not advisable to define a holy grail of gaze distribution for all environments. Gaze is highly situational and context-dependent, and generalized gaze distributions should not be used to design lighting functions. The research highlights the importance of an adaptive light distribution that adapts to the traffic situation and the environment, always providing good visibility for the driver and allowing a natural gaze behavior
Auswertung einer Befragung der ULB Darmstadt unter Lehrkräften der Oberstufe aus der Region Südhessen
No full textDienstleistungs- und Zielgruppenorientierung spielen im Alltag wissenschaftlicher Bibliotheken mittlerweile eine entscheidende Rolle. Im Gegensatz zu Hochschulbibliotheken, bei denen sich die Zielgruppen relativ klar definieren lassen, ist das Umfeld der Nutzer:innen von Regional- und Landesbibliotheken sehr heterogen. Die ULB Darmstadt erfüllt hierbei eine klassische Doppelaufgabe: Als Hochschulbibliothek ist sie für die Medienversorgung aller Angehörigen der TU Darmstadt zuständig und in ihrer Funktion als Landesbibliothek zugleich auch Ansprechpartnerin für alle interessierten Nutzer:innen aus der Region Südhessen.
Nachdem bereits die Bedürfnisse der Bürger:innen durch eine Befragung erhoben wurde, zielt diese Befragung nun auf Lehrkräfte im Speziellen ab. Gemeinsam mit der Hochschule Darmstadt führte die ULB im Sommersemester 2024 ein Forschungsprojekt durch, um mittels Onlinebefragung die folgenden Frage zu beantworten: Wie kann die ULB trotz begrenzter Personalkapazitäten effektiv sicherstellen, dass die relevanten Inhalte ihrer Veranstaltungen im Bereich Informationskompetenz möglichst viele Schüler:innen in ihrem Zuständigkeitsbereich erreichen. Die Antworten hierauf sind in dieser ausführlichen Auswertung der Befragung zu finden
A model for scheduling the resource deployment in a multi-stage ramp-up production system.
No full textAutomated hierarchical object clustering for multi-image documentation: a comprehensive image analysis pipeline
No full textThis paper presents an automated comprehensive image analysis pipeline designed for the spatially separated detection and hierarchical clustering of objects within multiple images taken for different kinds of documentation. While the original application derives from German crime scene documentation, the presented concept describes the application for various fields and use cases containing hierarchical structures of objects. In civil engineering and construction documentation, the as-built documentation, and the automated evaluation of images of construction diaries or issue documentation are useful use cases, improving the way data from multiple images in construction documentation is analyzed and interpreted. The presented approach closes the gap in existing solutions relying on additional information like BIM-models or specific photogrammetry-usages to gather (building) object relations. The parts of the pipeline are Single Image Analysis, Image Comparison, and Evaluation of Image Comparison. The Single Image Analysis includes the methods Metadata Extraction, computer vision methods such as object detection and -segmentation, a QR code reader as well as an image-rating of probability of being an overview image. The Image Comparison is executed for all image pairs and allows for the comparison of different types of information between two images and calculates the affinity-score (based on probability) for matching information for every single one of the following single comparison-methods: Metadata Comparison, Feature Matching, Object Segmentation Comparison (also combined with Feature Matching) and QR Code Comparison. The Image Comparison is done by comparing all image pairs with all available methods or more intelligently by using smarter resource-saving approaches described in the paper. The Evaluation of Image Comparison sorts the detected objects in the images hierarchically based on the previous steps. Additionally, the images get sorted room-wise into clusters. As a proof of concept, a demonstrative application with the use case of crime scene documentation is introduced, and the results are discussed
