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Atmospheric boundary layers (ABLs) exhibit transient processes on various time scales that range from a few days down to seconds, with a scale separation of the large-scale forcing and the small-scale turbulent response. One of the standing challenges in modeling and simulation of ABLs is a physically based representation of complex multiscale boundary layer dynamics. In this study, an idealized time-dependent ABL, the so-called Ekman–Stokes boundary layer (ESBL), is considered as a simple model for the near-surface flow in the mid latitudes and polar regions. The ESBL is driven by a prescribed temporal modulation of the bulk–surface velocity difference. A stochastic one-dimensional turbulence (ODT) model is applied to the ESBL as standalone tool that aims to resolve all relevant scales of the flow along a representative vertical coordinate. It is demonstrated by comparison with reference data that ODT is able to capture relevant features of the time-dependent boundary layer flow. The model predicts a parametric enhancement of the bulk–surface coupling in the event of a boundary layer resonance when the flow is forced with the local Coriolis frequency. The latter reproduces leading order effects of the critical latitudes. The model results suggest that the bulk flow decouples from the surface for high forcing frequencies due to a relative increase in detached residual turbulence.

Poster presented at the 86. Annual Meeting of DPG and DPG-Frühjahrstagung (DPG Spring Meeting) of the Matter and Cosmos Section (SMuK) - Dresden, Germany - 20.03. - 24.03.2023

Joint predictive modeling of hydrodynamics and electrokinetics is a standing numerical challenge but crucial for various applications in electrochemistry and power engineering. The present lack in modeling of electrohydrodynamic (EHD) turbulent flows lies in the treatment of small-scale processes and scale interactions. To overcome these limitations, a stochastic one-dimensional turbulence (ODT) model is utilized. The model aims to resolve all scales of the flow, but only on a notional line-of-sight, modeling turbulent advection by a stochastically sampled sequence of eddy events that punctuate deterministic molecular diffusive advancement. In this study, two canonical flow configurations are investigated that address different coupling strategies and flow physics. First, EHD effects in a variable-density vertical pipe flow of an ideal gas with an inner concentric electrode are investigated with a one-way coupled model formulation. Electric fields are generated by means of a corona discharge and the corresponding effect of a fixed ionic charge density field. Second, in order to reduce physical complexity, EHD effects the turbulent boundary layers in plane Couette flow of an isothermal univalent ionic liquid are investigated with a fully coupled model formulation. Both application cases demonstrate that ODT has predictive capabilities due to multiscale resolution of transport processes. Present results suggest that more expensive fully than one-way coupling of electrokinetics is crucial when charge relaxation times are significantly larger than the mean advection time scale.

Turbulent mixing is an omnipresent phenomenon that permanently affects our everyday life. Mixing processes also plays an important role in many industrial applications. The full resolution of all relevant flow scales often poses a major challenge to the numerical simulation and requires a modeling of the small-scale effects. In transported Probability Density Function (PDF) methods, the simplified modeling of the molecular mixing is a known weak point. At this place, the Hierarchical Parcel-Swapping (HiPS) model developed by A.R. Kerstein [J. Stat. Phys. 153, 142-161 (2013)] represents a computationally efficient and novel turbulent mixing model. HiPS simulates the effects of turbulence on time-evolving, diffusive scalar fields. The interpretation of the diffusive scalar fields or a state space as a binary tree structure is an alternative approach compared to existing mixing models. The characteristic feature of HiPS is that every level of the tree corresponds to a specific length and time scale, which is based on turbulence inertial range scaling. The state variables only reside at the base of the tree and are understood as fluid parcels. The effects of turbulent advection are represented by stochastic swaps of sub-trees at rates determined by turbulent time scales associated with the sub-trees. The mixing of adjacent fluid parcels is done at rates consistent with the prevailing diffusion time scales. In this work, a standalone HiPS model formulation for the simulation of passive scalar mixing is detailed first. The generated scalar power spectra with forced turbulence shows the known scaling law of Kolmogorov turbulence. Furthermore, results for the PDF of the passive scalar, mean square displacement and scalar dissipation rate are shown and reveal a reasonable agreement with experimental findings. The described possibility to account for variable Schmidt number effects is an important next development step for the HiPS formulation. This enables the incorporation of differential diffusion, which represents an immense advantage compared to the established mixing models. Using a binary structure allows HiPS to satisfy a large number of criteria for a good mixing model. Considering the reduced order and associated computational efficiency, HiPS is an attractive mixing model, which can contribute to an improved representation of the molecular mixing in transported PDF methods.

Passive scalars in turbulent channel flows are investigated as canonical problem for heat and mass transfer in turbulent boundary-layer flows. The one-dimensional turbulence model is used to numerically investigate the Schmidt and Reynolds number dependence of the scalar transfer to a wall due to fluctuating wall-normal transport. First, the model is calibrated for low-order velocity statistics. After that, we keep the model parameters fixed and investigate low-order passive scalar statistics for a relevant Schmidt and Reynolds number range. We show that the model consistently predicts the boundary layer structure and the scaling regimes, for which it is close to asymptotic one-dimensional theory., 8 pages, 5 figures, preprint

Noise prediction requires the resolution of relevant acoustic sources on all scales of a turbulent flow. High-resolution direct numerical and large-eddy simulation would be ideal but both are usually too costly despite developments in high performance computing. Lower-order modeling approaches are therefore of general interest. A crucial but standing problem for accurate predictive modeling is the estimation of missing noise from the modeled scales. In this paper we address this problem by presenting a novel lower-order framework that couples the one-dimensional turbulence model to the Ffowcs-Williams and Hawkings approach for prediction of the far-field noise of a subsonic turbulent round jet., 4 pages, 3 figures

The Rayleigh number $Ra$ dependence of the Nusselt number $Nu$ in turbulent Rayleigh--B\'enard convection is numerically investigated for a moderate and low Prandtl number, $Pr=0.7$ and $0.021$, respectively. Here we specifically address the case of a Boussinesq fluid in a planar configuration with smooth horizontal walls and notionally infinite aspect ratio. Numerical simulations up to $Ra=10^{16}$ for $Pr=0.7$ and up to $Ra=8\times10^{13}$ for $Pr=0.021$ are made feasible on state-of-the-art workstations by utilising the stochastic one-dimensional turbulence (ODT) model. The ODT model parameters were estimated once for two combinations $(Pr,Ra)$ in the classical regime and kept fixed afterwards in order to address the predictive capabilities of the model. The ODT results presented exhibit various effective Nusselt number scalings $Nu\propto Ra^b$. The exponent changes from $b\approx1/3$ to $b\approx1/2$ when the $Ra$ number increases beyond the critical value $Ra_*\simeq6\times10^{14}$ ($Pr=0.7$) and $Ra_*\simeq6\times10^{11}$ ($Pr=0.021$), respectively. This is consistent with the literature. Furthermore, our results suggest that the transition to the ultimate regime is correlated with a relative enhancement of the temperature-velocity cross-correlations in the bulk of the fluid as hypothesised by Kraichnan, R. H., Phys. Fluids, 5, 1374 (1962)., Comment: Preprint

The evolution of reptiles, birds, and mammals was associated with the origin of unique integumentary structures. Studies on lizards, chicken, and humans have suggested that the evolution of major structural proteins of the outermost, cornified layers of the epidermis was driven by the diversification of a gene cluster called Epidermal Differentiation Complex (EDC). Turtles have evolved unique defense mechanisms that depend on mechanically resilient modifications of the epidermis. To investigate whether the evolution of the integument in these reptiles was associated with specific adaptations of the sequences and expression patterns of EDC-related genes, we utilized newly available genome sequences to determine the epidermal differentiation gene complement of turtles. The EDC of the western painted turtle (Chrysemys picta bellii) comprises more than 100 genes, including at least 48 genes that encode proteins referred to as beta-keratins or corneous beta-proteins. Several EDC proteins have evolved cysteine/proline contents beyond 50% of total amino acid residues. Comparative genomics suggests that distinct subfamilies of EDC genes have been expanded and partly translocated to loci outside of the EDC in turtles. Gene expression analysis in the European pond turtle (Emys orbicularis) showed that EDC genes are differentially expressed in the skin of the various body sites and that a subset of beta-keratin genes within the EDC as well as those located outside of the EDC are expressed predominantly in the shell. Our findings give strong support to the hypothesis that the evolutionary innovation of the turtle shell involved specific molecular adaptations of epidermal differentiation.

The conserved INO80 chromatin remodeling complex is involved in regulation of DNA damage repair, replication and transcription. It is commonly recruited to the transcription start region and contributes to the establishment of promoter-proximal nucleosomes. We find a substantial influence of INO80 on nucleosome dynamics and gene expression during stress induced transcription. Transcription induced by osmotic stress leads to genome-wide remodeling of promoter proximal nucleosomes. INO80 function is required for timely return of evicted nucleosomes to the 5΄ end of induced genes. Reduced INO80 function in Arp8-deficient cells leads to correlated prolonged transcription and nucleosome eviction. INO80 and the related complex SWR1 regulate incorporation of the H2A.Z isoform at promoter proximal nucleosomes. However, H2A.Z seems not to influence osmotic stress induced gene regulation. Furthermore, we show that high rates of transcription promote INO80 recruitment to promoter regions, suggesting a connection between active transcription and promoter proximal nucleosome remodeling. In addition, we find that absence of INO80 enhances bidirectional promoter activity at highly induced genes and expression of a number of stress induced transcripts. We suggest that INO80 has a direct repressive role via promoter proximal nucleosome remodeling to limit high levels of transcription in yeast.

In turbulence research and flow applications, turbulence models like RaNS (Reynolds averaged Navier-Stokes) models and LES (Large Eddy Simulation) are used. Both models filter the governing flow equations. Thus a scale separation approach is introduced for modeling purposes with the large scales simulated using a numerical scheme while smaller scales are assumed to be less important and might be modeled more or less easily. Unfortunately small scales are frequently of big importance, e.g. in reactive flows, wall bounded flows, or flows with significant Prandtl or Schmidt number effects. Recent alternatives to these standard models are the class of models based on the one-dimensional turbulence (ODT) idea, like ODTLES. The ability of ODT to capture highly turbulent flows (recently up to $Re_\tau = 6\times 10^5$) allows ODTLES to realize 3D resolutions basically independent of the turbulent intensity. In two papers we provide a formal theory and application of an innovative modeling strategy for highly turbulent flows in domains of moderate complexity: In part I (see Glawe et al. (2015)) a new general filtering approach, called XLES (extended LES), is introduced. Contrary to LES, XLES is based on 2D filtering of the governing equations, whereby additional small scale terms are interpreted numerically. In this work a new ansatz for the ODTLES model is introduced as one special approach in the XLES family of models by incorporating the ODT model into XLES. The ODT model introduces microstructures not captured by the XLES filtered equations. To illustrate the ODTLES model capabilities, turbulent channel and duct flows up to friction Reynolds number $Re_\tau = 10000$ are studied.

Direct numerical simulation (DNS), mostly used in fundamental turbulence research, is limited to low turbulent intensities due the current and future computer resources. Standard turbulence models, like RaNS (Reynolds averaged Navier-Stokes) and LES (Large Eddy Simulation), are applied to flows in engineering, but they miss small scale effects, which are frequently of importance, see e.g. the whole area of reactive flows, flows with apparent Prandtl or Schmidt number effects, or even wall bounded flows. A recent alternative to these standard approaches is the one-dimensional turbulence (ODT) model, which is limited to 1D sub-domains. In two papers we will provide a generalized filter strategy, called XLES (extended LES), including a formal theory (part I) and one special approach in the XLES family of models, called ODTLES (in part II (see Glawe et al. (2015))). ODTLES uses an ODT sub-grid model to describe all turbulent scales not represented by XLES, which leaves the larger scales to be simulated in 3D. This allows a turbulence modeling approach with a 3D resolution mainly independent of the turbulent intensity. Thus ODTLES is able to compute highly turbulent flows in domains of moderate complexity affordably and including the full range of turbulent and diffusive scales. The convergence of XLES to DNS is shown and the unconventional XLES advection approach is investigated in basic numerical tests. In part II, highly turbulent channel and duct flow results are discussed and show the future potential of XLES and ODTLES.

Systeme zur optischen Messung sind oft kompliziert und Anwendungsfehler daher nicht selten. Eine neue Software soll den Nutzer durch den Überprüfungs- und Messprozess und die anschließende Auswertung führen, um Fehler zu verhindern.

Duisburg, Essen, Univ., Diss., 2014

Large-scale software systems need to be accurately planned and designed. This includes the determination of requirements, the definition of specifications, and the development of models conforming to specifications. These models are expressed in modeling languages like process algebras, the Unified Modeling Language (UML), or variants of state diagrams (e.g. UML state machines or Harel's statecharts). Such modeling languages are usually underspecified, since they only express certain aspects of the system to be designed, leaving out implementation details. The process of refining such abstract descriptions in a stepwise fashion, until finally the concrete, executable implementation is reached, is called (model-driven) top-down development. Finding bugs as early as possible in this process often saves considerable development costs. This thesis considers methods for proven-to-be-correct top-down development, with specification conformance being guaranteed at all levels of abstraction, either by applying model checking techniques or by employing pre-defined refinement patterns that are already proven to be sound. In order to apply formal proof methods, models on all levels of abstraction, e.g. presented as process algebra terms or state diagrams, need to be given a precise semantics in some semantic domain, usually based on (extensions of) labeled transition systems. We call semantic domains that support underspecification refinement settings. One of the contributions of this thesis is a new kind of comparison of a dozen such settings proposed in the literature with respect to their expressible sets of implementations. This comparison is done by providing transformations that not only establish the implementation-based expressiveness hierarchy of the most commonly used refinement settings, but can also be employed to convert models between the settings, thus enabling tool reuse. Some kinds of abstract models require a setting as semantic domain that not only features resolvable nondetermism expressing underspecification, but also persistent nondeterminism that is not to be resolved in refinements, as characterized by bisimulation equivalence on labeled transition systems. We show that such a setting is needed for process algebras if they specify concurrent systems, because concurrency may introduce resolvable nondeterminism which is resolved by the scheduler of the operating system, and the choice operator, which is common to process algebras, may correspond to persistent nondeterminism. This is the first work in the literature making this observation. A simple process algebra of this kind is given an operational semantics, using the refinement setting of mu-automata, as well as a sound and complete axiomatic semantics. Sometimes state diagrams, such as UML state machines or Harel's statecharts, also require a refinement setting with both kinds of nondeterminism, because (i) they are underspecified and (ii) the underlying action language may contain operators exhibiting persistent nondeterministic behavior. This thesis is the first publication presenting a state diagram semantics with both kinds of nondeterminism. In this context, existing refinement settings like mu-automata lead to unnecessarily complex semantic models. Therefore, we develop a new and in this context more succinct refinement setting, called nu-automata, and give a semantic mapping for a simple state diagram variant, as well as a general transformation that can be applied when extending existing semantics by persistent nondeterminism. Thus, we make state diagrams accessible to persistent nondeterminism. Support for both kinds of nondeterminism, however, does not necessarily imply the practical feasibility of top-down development in state diagrams. In existing state diagram variants, expressing resolvable nondeterminism is only possible to a certain degree, because the notations for underspecification (i) often have no precise semantics, and (ii) are not expressive enough to reflect the requirements of the top-down development process, such as starting with interface definitions and subsequent parallel development of mostly independent modules. Therefore, we develop a new variant of state diagrams that allows more explicit and more expressive modeling of underspecification than existing variants. This variant is given a semantics in a newly developed semantic setting that distinguishes between input and output events. A set of refinement patterns is then provided that enables proven-to-be-correct stepwise refinement without the need to re-check correctness after each refinement step. Consequently, we deliver the formal foundations for the development of a state-diagram-based design tool that ensures correctness at all stages of the development process. Große Softwaresysteme bedürfen sorgfältiger Planung und Entwicklung, einschließlich einer Anforderungsanalyse, dem Aufstellen von Spezifikationen und der Entwicklung von Modellen, die die Spezifikation einhalten. Solche Modelle werden in Modellierungssprachen wie Prozessalgebren, der Unified Modeling Language (UML) oder Varianten von Zustandsdiagrammen (z.B. UML state machines oder Harel's statecharts) ausgedrückt. Diese Modellierungssprachen sind üblicherweise unterspezifiziert, d.h. sie beschreiben nur bestimmte Aspekte des zu entwickelten Systems und lassen Implementationsdetails weg. Der Prozess, solche abstrakten Beschreibungen schrittweise zu verfeinern, bis schließlich die konkrete, ausführbare Implementation erreicht ist, wird (modellgetriebene) Top-Down-Entwicklung genannt. Es spart oft beachtliche Entwicklungskosten, wenn Programmierfehler so früh wie möglich in diesem Prozess gefunden werden. Die vorliegende Arbeit betrachtet Methoden für per-Konstruktion-korrekte Top-Down-Entwicklung, für die Spezifikationstreue auf allen Abstraktionsstufen gewährleistet ist, entweder durch die Anwendung von Modelchecking-Techniken oder durch die Verwendung von vordefinierten Verfeinerungsmustern, deren Korrektheit bereits bewiesen ist. Um formale Methoden anwenden zu können, muss den Modellen auf allen Abstraktionsstufen, ausgedrückt etwa in Prozessalgebren oder Zustandsdiagrammen, eine präzise Semantik gegeben werden. Solche Semantiken werden üblicherweise mittels (Erweiterungen von) Transitionssystemen ausgedrückt. Wir nennen solche semantischen Formalismen, die Unterspezifikation unterstützen, Verfeinerungsformalismen. Einer der Beiträge dieser Arbeit ist eine neue Art von Vergleich von einem Dutzend solcher Formalismen, in Hinblick auf ihre ausdrückbaren Mengen von Implementationen. Dieser Vergleich erfolgt durch die Angabe von Transformationen, die nicht nur die implementationsbasierte Ausdrucksstärkenhierarchie der meistbenutzten Verfeinerungsformalismen begründen, sondern auch dafür verwendet werden können, Modelle zwischen Formalismen zu konvertieren und damit die Wiederverwendung von Werkzeugen zu ermöglichen. Einige abstrakte Modelle benötigen einen semantischen Formalismus, der nicht nur auflösbaren Nichtdeterminismus für das Ausdrücken von Unterspezifikation, sondern auch persistenten Nichtdeterminismus enthält. Letzterer soll nicht in Verfeinerungen aufgelöst werden, wie es durch Bisimulationsäquivalenz auf Transitionssystemen charakterisiert wird. Wir zeigen, dass ein solches Modell für Prozessalgebren im Kontext nebenläufiger Systeme benötigt wird, weil Nebenläufigkeit auflösbaren Nichtdeterminismus einführen kann, der vom Scheduler des Betriebssystems aufgelöst wird, und der Choice-Operator, welcher in Prozessalgebren üblich ist, persistentem Nichtdeterminismus entsprechen kann. Dieses ist die erste publizierte Arbeit, die diese Beobachtung macht. Wir geben für eine einfache Prozessalgebra eine operationelle Semantik mittels mu-Automaten, sowie eine korrekte und vollständige axiomatische Semantik an. Auch Zustandsdiagramme wie UML state machines oder Harel's statecharts benötigen manchmal semantische Formalismen mit beiden Arten von Nichtdeterminismus, weil Zustandsdiagramme (i) unterspezifiziert sind und (ii) die zugrundeliegende Aktionssprache Operatoren enthalten kann, die persistent-nichtdeterministisches Verhalten zeigen. Die vorliegende Arbeit ist die erste, die eine Zustandsdiagramm-Semantik mit beiden Arten von Nichtdeterminismus vorstellt. In diesem Kontext würden existierende semantische Modelle wie mu-Automaten zu unnötig komplexen semantischen Modellen führen. Daher entwickeln wir einen neuen, in diesem Kontext bündigeren Verfeinerungsformalismus, nämlich nu-Automaten, und geben eine semantische Abbildung für eine einfache Zustandsdiagrammvariante, sowie eine allgemeine Transformation an, die auf existierende Semantiken, die um persistenten Nichtdeterminismus erweitert werden sollen, angewendet werden kann. Wir machen also Zustandsdiagramme im Allgemeinen für persistenten Nichtdeterminismus zugänglich. Die Unterstützung von beiden Arten von Nichtdeterminismus impliziert jedoch nicht notwendigerweise die praktische Umsetzbarkeit von Top-Down-Entwicklung in Zustandsdiagrammen. In existierenden Zustandsdiagrammvarianten ist das Ausdrücken von auflösbarem Nichtdeterminismus nur zu einem gewissen Grade möglich, weil die Notationen für Unterspezifikation (i) oft keine präzise Semantik haben, und (ii) nicht ausdrucksstark genug sind, um die Anforderungen des Top-down-Entwicklungsprozesses widerzuspiegeln, wie das Starten mit der Definition von Schnittstellen und nachfolgende parallele Entwicklung größtenteils unabhängiger Module. Daher entwickeln wir eine neue Zustandsdiagrammvariante, die expliziteres und ausdrucksstärkeres Modellieren von Unterspezifikation als existente Varianten unterstützt. Ihre Semantik wird in einem neu entwickelten semantischen Formalismus gegeben, der zwischen Eingabe- und Ausgabeereignissen unterscheidet. Eine Kollektion von gegebenen Verfeinerungsmustern erlaubt korrekt-bewiesene schrittweise Verfeinerung, ohne dass die Korrektheit nach jedem Verfeinerungsschritt erneut bewiesen werden muss. Wir liefern also die formale Basis für die Entwicklung eines zustandsdiagrammbasierten Entwicklungswerkzeugs, welches Korrektheit in allen Stadien des Entwicklungsprozesses sicherstellt.

Jeder Mensch hat seine Geschichte. Hier kommen Handwerkerinnen und Handwerker aus den verschiedensten Gewerken zu Wort – original und ungeschminkt. Im Rahmen des Projektes »Handwerk erzählt« lud Rohnstock Biografien in 10 sächsischen und thüringischen Orten und Regionen Handwerkerinnen und Handwerker dazu ein, in Erzählsalons Erfahrungsgeschichten aus ihrem Berufsleben zu erzählen. Die Geschichten erzählen von den unterschiedlichen Wegen der Handwerker:innen ins Berufsleben, davon, wie sie Meister ihres Gewerkes wurden, von der Erfüllung, die sie in ihrem Beruf fanden, sowie von ihren Sorgen und Wünschen. An diesen Erfahrungen können die Leser nun teilhaben. Gerahmt werden die Geschichten von den starken Portraits des Fotografen André Kranert, der das Projekt mit der Kamera begleitete.:INHALT 08 - Marco Wanderwitz, Grußwort 10 - Hans Peter Wollseifer, Vorwort KUNSTHANDWERK - WIR GESTALTEN EURE WELT 14 - Manuela Fischer, Klöpplerin: Die Wiege des Spitzenklöppelns 19 - Sonja Belz, Klöpplerin: Ein Leben mit der Spitze 22 - Günter Jahn, Korbmacher: Ein Handwerk im Zeichen des immateriellen Kulturerbes 30 - Claus Hager, Porzellanmaler: Malen als Berufung 35 - Reni Matthias Tauscher, Töpferin: Eine Töpferstadt ohne Töpfer? 42 - Peter Tauscher, Töpfer: »Die Kunst ist mein Leben« MUSIKINSTRUMENTEBAU - WIR BRINGEN EUCH MUSIK 50 - Jacob Thierfelder, Geigenbauer: Der lange Weg zum Geigenbaumeister 58 - Frank Dittrich, Bassbauer: Vom Vogtland nach Shanghai und zurück 62 - Christoph Rühle, Orgelbauer: Die Töne meiner Arbeit 65 - Wolfgang Trobisch, Klavierbauer: Klavierbau gegen jede Widrigkeit LEBENSMITTELGEWERBE - WIR SORGEN FÜR GESCHMACK 74 - Robert Häußler, Fleischer: Den Meister macht die Zeit 80 - Carla Langer, Fleischerin: Eine Fleischermeisterin lernt nie aus 83 - Nora Seitz, Fleischerin: Wie die Teamchefin der Nationalmannschaft zum Fleisch kam 87 - Matthias Jung, Bäcker: »Du kannst kein Bäcker werden!« 90 - Peter Liebe, Bäcker: Uns Bäckern fällt immer etwas ein! 98 - Heiko Schmidt, Bäcker: Ein natürlicher Übergang 100 - Dieter Ullmann, Bäcker: Und plötzlich die eigene Bäckerei HOLZ -WIR GEBEN HOLZ EINE FORM 106 - Thomas Schalling, Drechsler: Von Großvaters Eierbecher zur Holzpyramide des Enkels 110 - Sebastian Schulz, Bau-und Möbeltischler, Restaurator im Tischlerhandwerk: Das Wunder der Frauenkirche 116 - Michael Metzeroth, Tischler: Traditionsbetrieb seit 1897