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Transaktive Betriebsführung vernetzter Wärme- und Kältesysteme an Produktionsstandorten
Get PDFDurch die forcierte Dekarbonisierung finden sich energieintensive Unternehmen mit hohen thermischen Energiebedarfen in einem Spannungsfeld ökonomischer und ökologischer Ziele wieder. Dabei erhöhen die erforderlichen Transformationsmaßnahmen die Komplexität industrieller Wärme- und Kältesysteme und folglich die Anzahl möglicher Betriebszustände. Hieraus resultieren Herausforderungen bei der Entwicklung energieoptimierter Betriebsführungskonzepte, welche gleichzeitig die Anforderungen an Skalierbarkeit und Adaptivität erfüllen. In elektrischen Energiesystemen wird diesen Herausforderungen zunehmend mit transaktiven Konzepten auf Basis lokaler Energiemärkte begegnet. Die vorliegende Arbeit transferiert diesen Ansatz durch die holistische Entwicklung eines auktionsbasierten Multiagentensystems auf die vernetzten, thermischen Energiesysteme eines Produktionsstandorts anhand folgender Forschungsclusterstruktur.
Forschungscluster 1 beschreibt die statische und dynamische Interaktion von Betriebsführungsmodul und Agentenumgebung. Forschungscluster 2 modelliert ein Multiagentensystem auf Basis lokaler Energiemärkte für die gekoppelten thermischen Netze eines Produktionsstandorts. Ein Energiemarkt besteht aus einem Marktagenten, der den algorithmischen Handel von Kurz- und Langfristkontrakten mit unterschiedlichen Handelsvorlaufzeiten ermöglicht, sowie einer beliebigen Anzahl an Handelsagenten. Die Handelsagenten repräsentieren technische Systeme wie thermische Wandler, Verbraucher, Speicher oder netzverknüpfende Elemente wie Wärmepumpen und -übertrager. Zur virtuellen Abbildung des Energiesystems durch ein dynamisches Simulationsmodell wird in Forschungscluster 3 eine objektorientierte Modellbibliothek unter Herleitung eines konsistenten Basisdatenmodells entwickelt. Gleiches gilt für äquivalente Automationsbibliotheken in Forschungscluster 4. Alle Modelle werden in unabhängigen Open-Source-Lösungen implementiert.
Schließlich wird das Betriebsführungskonzept anhand des thermischen Energiesystems der ETA-Fabrik der Technischen Universität Darmstadt validiert. Die simulative Anwendung erfolgt für sechs Agentensystemkonfigurationen und verschiedene Jahreszeiten. Hierbei reduzieren sich die Energiekosten unter Beibehaltung der Versorgungssicherheit für die performanteste Agentensystemkonfiguration um 21,5 % gegenüber einem regelbasierten Referenzkonzept. Im Anschluss wird diese Konfiguration zur Funktionalitätsdemonstration erfolgreich auf das Realsystem transferiert. Die Ergebnisse der virtuellen und realen Anwendung bestätigen die Potenziale lokaler Energiemärkte zur Implementierung eines skalierbaren und adaptiven Automationsansatzes, der die effiziente Ressourcenallokation unter Gewährleistung der Versorgungssicherheit in industriellen, thermischen Energiesystemen ermöglicht
Breitbandige Laserkühlung relativistischer Ionenstrahlen: Erste Experimente und Weiterentwicklung des UV-Lasers
Get PDFDie 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
Liquid Fuel Atomization and Evaporation in Complex Geometries Using High-Fidelity Multi-Scale Simulation Methods
Get PDFModern combustion systems used in applications like automotive, ship and aerospace engines are increasingly focused on advanced technologies that may enable to reduce pollutant emissions and incorporate carbon neutral fuels. In such systems mainly fired with liquid fuel, the process of liquid injection is essentially realized under non-isothermal conditions making the whole liquid injection a very complex phenomenon featuring a wide range of length and time scales. Thereby, complex interaction processes take especially place between flow dynamics, atomization, evaporation, turbulent mixing and combustion, which critically influence fuel-air mixture formation and pollutant generation. Understanding these processes is vital not only for advancing nozzle design, but also for optimizing fuel-air mixing, and improving combustion efficiency. High fidelity numerical simulation techniques are able to support such a challenge.
That is why, in the present work, a novel multiscale approach is developed which saves computational costs and is able to capture correctly the whole spray formation and dispersion while including the in-nozzle flow, the liquid fuel atomization and the phase change throughout the spray regions. The suggested approach consists in a seamless coupling of the Volume of Fluid (VOF) method and the Lagrangian Particle Tracking (LPT) within a high-fidelity framework based on Large Eddy Simulation (LES) techniques. Adaptive Mesh Refinement (AMR) is incorporated into the simulation setting to dynamically enhance the resolution of the liquid-gas interface, effectively lowering computational costs while ensuring accuracy. The coupling algorithm is implemented into the open source CFD code OpenFOAM.
First, the model is developed and validated to deal with isothermal applications of liquid jet injection, and then applied to three practical configurations, namely the liquid jet injection in cross-flow (LJICF), the spray atomization from a pressure swirl atomizer, and the spray atomization with co-flow effects from a spray burner. The results successfully reproduce the key atomization processes, including the in-nozzle flow, the jet penetration, the breakup and the droplet dispersion, while highlighting the significant influence of turbulent co-flow on the spray cone angle, sheet thickness, breakup length and droplet distribution.
Encouraged by these impressive achievements, the approach could be then extended by consistently integrating the phase change into the overall modeling. This makes it possible to investigate practical configurations under non-isothermal conditions. Two cases are selected for this purpose. The first allows to analyze and quantify the influence of evaporation on the entire spray evolution in LJICF. The second brings to the fore the effects of different crossflow temperatures on atomization, evaporation, spray dispersion, interaction between turbulence and evaporation, as well as on turbulent mixing in LJICF. Overall, the extended methodology effectively captures the influence of phase change on spray dynamics in the near-nozzle region, including instabilities, breakup through appropriate breakup diagram, and penetration length of the liquid jet. In addition, it allows to quantify the influence of crossflow temperature on evaporation rates, droplet sizes, turbulence-evaporation interaction thanks to a targeted evaporation Damköhler number, and turbulent mixing through specific selected measures in the dilute spray region far from the nozzle. Comparisons with experimentally available data demonstrate the predictive accuracy and reliability of the developed approaches. In summary, these accomplishments ensure significant progress both in the development of the methodology and in the analysis of the phenomena. The established method provides a solid basis for future extensions, including combustion and other complex processes
Crystal structure of dilithium (nitridolithiate/manganate(I)), Li₂[(Li₁₋ₓMnₓ)N], x = 0.73
Get PDFLi₂.₂₇Mn₀.₇₃N, hexagonal, P6/mmm (No. 191), a = 3.7263(4) Å, c = 3.8281(4) Å, V= 46.0 ų, Z= 1, Rgt(F) = 0.025, wR(F²) = 0.063, Τ = 293 Κ
High‐speed drive‐by monitoring: field testing with an intercity express train (ICE)
Get PDFThe structural condition of bridges in Germany is often affected by aging and increased traffic loads. However, retrofitting or renewing all bridges is not always feasible due to limited resources. Indirect or drive‐by monitoring of bridges with sensors on passing vehicles has been explored as a cost‐effective and scalable alternative to direct monitoring. In this study, we propose a novel High‐Speed Monitoring (HSM) method for determining natural frequencies, based on accelerometers mounted on train axles, developed for speeds under normal operating conditions. In combination with Bayesian optimisation, a resonance curve can be generated using only a few bridge passages, from which the dominant bending natural frequency of a bridge can be determined with an accuracy comparable to direct monitoring. Measurements on an ICE‐TD passaging bridges travelling at high speeds of up to 200 km/h have shown that the natural frequencies can be determined with the same accuracy as direct measurements. Thus, in this study we were able to show that the method is not only accurate, cost‐effective and scalable, but can also be applied at high speeds without affecting operations
Structure of the Dispase Autolysis-inducing Protein from Streptomyces mobaraensis and Glutamine Cross-linking Sites for Transglutaminase
Get PDFTransglutaminase from Streptomyces mobaraensis (MTG) is an important enzyme for cross-linking and modifying proteins. An intrinsic substrate of MTG is the dispase autolysis-inducing protein (DAIP). The amino acid sequence of DAIP contains 5 potential glutamines and 10 lysines for MTG-mediated cross-linking. The aim of the study was to determine the structure and glutamine cross-linking sites of the first physiological MTG substrate. A production procedure was established in Escherichia coli BL21 (DE3) to obtain high yields of recombinant DAIP. DAIP variants were prepared by replacing four of five glutamines for asparagines in various combinations via site-directed mutagenesis. Incorporation of biotin cadaverine revealed a preference of MTG for the DAIP glutamines in the order of Gln-39 ≫ Gln-298 > Gln-345 ∼ Gln-65 ≫ Gln-144. In the structure of DAIP the preferred glutamines do cluster at the top of the seven-bladed β-propeller. This suggests a targeted cross-linking of DAIP by MTG that may occur after self-assembly in the bacterial cell wall. Based on our biochemical and structural data of the first physiological MTG substrate, we further provide novel insight into determinants of MTG-mediated modification, specificity, and efficiency
Cascade enzymatic synthesis of a statin side chain precursor – the role of reaction engineering in process optimization
Get PDFStatins are an important class of drugs used to lower blood cholesterol levels and are often used to combat cardiovascular disease. In view of the importance of safe and reliable supply and production of statins in modern medicine and the global need for sustainable processes, various biocatalytic strategies for their synthesis have been investigated. In this work, a novel biocatalytic route to a statin side chain precursor was investigated in a one-pot cascade reaction starting from the protected alcohol N-(3-hydroxypropyl)-2-phenylacetamide, which is oxidized to the corresponding aldehyde in the first reaction step, and then reacts with two equivalents of acetaldehyde to form the final product N-(2-((2S,4S,6S)-4,6-dihydroxytetrahydro-2H-pyran-2-yl)ethyl)-2-phenylacetamide (phenylacetamide-lactol). To study this complex reaction, an enzyme reaction engineering approach was used, i.e. the kinetics of all reactions occurring in the cascade (including side reactions) were determined. The obtained kinetic model together with the simulations gave an insight into the system and indicated the best reactor mode for the studied reaction, which was fed-batch with acetaldehyde feed to minimize its negative effect on the enzyme activity during the reaction. The mathematical model of the process was developed and used to simulate different scenarios and to find the reaction conditions (enzyme and coenzyme concentration, substrate feed concentration and flow rate) at which the highest yield of phenylacetamide-lactol (75%) can be obtained. In the end, our goal was to show that this novel cascade route is an interesting alternative for the synthesis of the statin side chain precursor and that is why we also calculated an initial estimate of the potential value addition
Need a Good Book about Privacy? Evaluating Dictionary-Based Corpus Query for Detecting the Topic of Privacy in Literary Texts
Get PDFThis paper evaluates the usefulness of querying Vasalou et al.’s Privacy
Dictionary (2011), a dictionary of 600+ words and phrases, in 131 canonical
English-language novels from the long 19th century. We evaluate the word
frequencies compared with a classification of the novels based on scholarly
attention to the topic of privacy in each particular text. We report evidence of
low- to low/medium strength of correlation between 3 of the 8 categories of
the Privacy Dictionary and this classification. As a final step, by identifying the
novels in our corpus which score highest in relative word frequency in these 3
categories, we suggest novels which have not yet received scholarly study on
the topic of privacy but which may be promising for such studies. The highest
scoring novel by our method, Maria Edgeworth’s Castle Rackrent (1800), seems
indeed to be highly concerned with the topic of privacy, which is discussed in
its author’s preface and opening pages
A Novel Approach for Identification and Linking of Short Quotations in Scholarly Texts and Literary Works
Get PDFWe present two approaches for the identification and linking of short quotations between scholarly works and literary works: ProQuo, a specialized pipeline, and ProQuoLM, a more general language model based approach. Our evaluation shows that both approaches outperform a strong baseline and the overall performance is on the same level. We compare the performance of ProQuoLM on texts with and without (page) reference information and find that reference information is not used. Based on our findings, we propose the following steps for future improvements: further analysis of the influence of a bigger context window for better handling of long distance references and the introduction of positional information of the literary work so that reference information can be utilized by ProQuoLM
InvBERT: Reconstructing Text from Contextualized Word Embeddings by inverting the BERT pipeline
Get PDFDigital Humanities and Computational Literary Studies apply automated methods to enable studies on large corpora which are not feasible by manual inspection alone. However, due to copyright restrictions, the availability of relevant digitized literary works is limited. Derived Text Formats (DTFs) have been proposed as a solution. Here, textual materials are transformed in such a way that copyright-critical features are removed, but that the use of certain analytical methods remains possible. Word embeddings produced by transformer-encoders are promising candidates for DTFs because they allow for state-of-the-art performance on analytical tasks. However, in this paper we demonstrate that under certain conditions the reconstruction of the original text from token representations becomes feasible. Our attempts to invert BERT suggest, that publishing the encoder together with the contextualized embeddings is critical, since it allows to generate data to train a decoder with a reconstruction accuracy sufficient to violate copyright laws