Re-evaluating the relationship between load transfer characterisation values for rigid aircraft pavement construction joints

Rigid aircraft pavement load transfer is typically characterised by load transfer efficiency via deflection (LTEδ), or free-edge stress transferred (LT). LTEδ is relatively easily calculated from falling weight deflectometer field measurements and is routinely assessed for existing slabs. In contrast, LT is commonly used as an input for thickness design. However, LT is difficult to measure in the field. Consequently, understanding the relationship between LTEδ and LT can improve rigid aircraft pavement design and evaluation strategies. Although relationships exist for load transfer characterisation values, they are built on generalised assumptions for free-edge deflection and stress. This study re-evaluated the relationships between typical load transfer values for three different construction joint types using finite element methods. It was determined that the relationship between LT and LTEδ is largely dependent on construction joint type. Furthermore, predictive models for different construction joints were developed to relate LTEδ to LT. The findings from this research can be used to better relate load transfer field measurements, to thickness design assumptions, for rigid aircraft pavements

Bewertungsmodell für Leistungsfähigkeits-, Resilienzfähigkeits- und Nachhaltigkeitsfaktoren produzierender Unternehmen

Neben der Leistungssteigerung ist die Erhöhung der Resilienz und Nachhaltigkeit (LRN) eine zentrale Größe im industriellen Umfeld. Optimierungsmaßnahmen werden in produzierenden Unternehmen meist ökonomischen Faktoren zugeschrieben, ohne eine resiliente, ökologisch und sozial nachhaltige Systemgestaltung zu berücksichtigen. Das Aufkommen von Nachhaltigkeitsgesetzgebungen sowie jüngste Krisen zeigen, dass ökonomische Zielsetzungen allein nicht mehr ausreichen, um wettbewerbsfähig zu bleiben. Forschungsprojekte, Expertiseinterviews und die Analyse des Standes der Wissenschaft verdeutlichen, dass vor allem die hohe Abstraktheit, thematische Komplexität und fehlende Ansätze zur systematischen Bewertung des LRN-Ist-Zustands für die schleppende Umsetzung verantwortlich sind. Ziel der Dissertation ist es, relevante LRN-Faktoren zu analysieren, zu operationalisieren und mittels einer eigens entwickelten, praxistauglichen Methodik bewertbar zu machen. Über den bewerteten Ist-Zustand, den definierten Soll-Zustand und den Maßnahmenbedarf sollen Unternehmen Zielgrößen ableiten, Optimierungsstrategien definieren und konkrete Investitionen in organisatorische, prozessuale und nachhaltige Entwicklungen tätigen, um Wertschöpfung und Wettbewerbsfähigkeit sicherzustellen. Die Dissertation folgt der Design Science Methodik, angereichert um weitere Forschungsmethoden. Eine systematische Literaturrecherche identifizierte ca. 400 relevante Publikationen. Aus 59 Bewertungsmodellen wurden 36 qualitative und quantitative Bewertungsattribute abgeleitet. Für produzierende Unternehmen wurden eine Anwendungs- und Bewertungsmethodik sowie die notwendigen Werkzeuge entwickelt. Das Ergebnis ist ein Bewertungsmodell, das den Ist-Zustand der LRN-Betrachtungs-größen anhand von 36 Attributen in zehn Dimensionen erfasst und den Maßnahmenbedarf ausgibt. Die Entwicklungsschritte werden durch zwei Praxisanwendungen, Befragungen mit Fachpersonen und eine Bewertungsanalyse mit 24 Anwendenden de-monstriert und evaluiert. Die Ergebnisse zeigen wissenschaftlich, dass die Nutzung operationaler Attribute und deren quantitative Messung zu einer objektiven Bewertung führt. Praxisorientiert ermöglicht das Vorgehen eine eindeutige Bestimmung von Ist- und Soll-Zuständen sowie die Priorisierung von Maßnahmen als Grundlage für die Planung zukünftiger Optimierungsprojekte.In addition to improving performance, increasing resilience and sustainability (PRS) is a key factor in the industrial environment. For manufacturing companies, optimisation measures are usually driven by economic factors without considering a resilient, ecologically and socially sustainable system design. The emergence of sustainability legislation and recent crises show that economic goals alone are no longer sufficient for remaining competitive. Research projects, expert interviews with industry representatives, and the analysis of the state of the art reveal that the high abstraction level, thematic complexity of PRS related areas, and lack of systematic evaluation approaches are mainly responsible for the slow implementation. Therefore, the aim of this dissertation is to analyse and operationalise the PRS factors at the level of industrial companies and to make them assessable in manufacturing companies using a specially developed, practice-oriented methodology. The evaluated actual state, the defined target state and the resulting need for action for the three variables should help companies to derive target values, to define optimisation strategies and finally to make concrete investments in organisational, sustainable development in order to maintain added value and competitiveness in the future. This dissertation follows the design science research approach, which has been selectively enriched with further research methods. A comprehensive systematic literature review was conducted to identify approximately 400 relevant publications. A total of 36 qualitative and quantitative assessment attributes of the PRS model were derived from 59 analysed assessment models. An application and evaluation methodology and the necessary tools were developed for use in manufacturing companies. The result is an assessment model that uses 36 assessment attributes within ten dimensions to capture the PRS current state and identify the need for action. The devel-opment steps are demonstrated and evaluated by two practical applications, expert surveys, and a user evaluation analysis with 24 participants. Scientifically, the practical applications show that using operational assessment attributes and quantitatively measuring their characteristics leads to an objective PRS assessment. Application-oriented, a clearly defined procedure in applying the model en-ables a prioritization of requirements as a basis for efficient planning of future optimisation projects

Enhanced hardness and fracture toughness in diboride superlattice films: Ab initio and experimental study

Superlattice architecture presents a promising strategy for the simultaneous enhancement of hardness and toughness in hard ceramic films. Here, we demonstrate the success of this approach in transition metal diboride films—materials whose inherent brittleness typically limits their applications. We combined Density Functional Theory (DFT)-based calculations and direct current magnetron sputtering to investigate the mechanical properties as a function of the bilayer period (Λ). Theoretical calculations for ZrB₂/TaB₂ cells (Λ = 1.4–8.2 nm) reveal a stabilizing effect with decreasing Λ and a significant increase in stiffness, peaking at Λ = 2.7 nm. Experimentally, ZrB₂.₆/TaB₁.₄ superlattice films deposited with Λ = 1.8–31.5 nm exhibit a structural transition characterized by the crystallization of disordered TaB₂₋y layers. This transition is accompanied by a remarkable increase in hardness from H = 34.1 ± 1.9 to 47.2 ± 2.3 GPa as Λ decreases to 3.4 nm. The hardening exceeds the estimations of Koehler's strengthening, suggesting multiple contributing effects: chemical bonding, boron diffusion at interfaces, Hall-Petch behavior, and compressive residual stress. At the same time, the fracture toughness increases to KIC = 4.6 ± 0.3 MPa·m¹/² at Λ = 1.8 nm, attributed to coherent stresses at the ZrB₂₊ₓ/TaB₂₋y interfaces. This research demonstrates the effectiveness of superlattice architectures in diboride films and highlights the crucial role of nanostructure and stoichiometry

The Role of Snowmelt on the Recharge Dynamics of a Vadose Alpine Karst

In Alpine karst aquifers, snowmelt plays a crucial role in groundwater recharge, yet the processes governing water flow through the soil and epikarst into the vadose zone and to the phreatic zone remain poorly understood. This study aims at shedding some light on paths and mechanisms for infiltration, flow, and accumulation of snowmelt in comparison to rainwater in karstic systems. In particular, we present results for the upper vadose zone of the Hochschwab karst massif (Eastern Alps, Austria), a crucial water source for the capital of Vienna. We combined geophysical and hydrological methods to distinguish different infiltration processes. Data were collected at a cave (1896 m above sea level) over 3 weeks in March and April 2024, during which 12 infiltration events were observed—nine through diurnal cycles of snowmelt and three mixed with effective rain. Additionally, dry and wet conditions in the following summer were monitored to provide a seasonal comparison of infiltration dynamics. Monitoring included cave drip water at a V-notch weir (discharge, electrical conductivity, and temperature), soil moisture measurements at depths of 5–30 cm, and electrical resistivity tomography (ERT), utilising 96 electrodes between the cave ceiling and the surface. Measurements at the weir in the cave indicate higher flow rates during heavy precipitation than during snowmelt, while the ERT images show the highest saturation during snowmelt, especially in the bedrock. Hence, results show that snowmelt primarily leads to diffuse recharge, with an overall increase in the saturation of the epikarst and rock, while rain events demonstrate a quick recharge pattern. These findings emphasise the importance of snowmelt as a diffuse recharge source contributing to water storage and underline that the integration of multiple sensors is crucial for understanding the variability of recharge processes in Alpine karst systems under different meteorological conditions

A Unified Framework for Trend Uncertainty Assessment in Climate Data Record: Application to the Analysis of the Global Mean Sea Level Measured by Satellite Altimetry

Estimating trends from Climate Data Records (CDRs) of Essential Climate Variables (ECVs) is necessary to detect persistent changes in Earth’s climate and geophysical processes and states. Accurately describing trend uncertainty is also essential to determining the significance of observed changes and attributing drivers. However, despite the importance of uncertainty, no established trend assessment approach properly accounts for all known sources of trend uncertainty. Most approaches either neglect part of known measurement uncertainty, such as measurement system instability, or ignore the influence of natural climate variability on trend estimation. Such neglect can result in over-confidence in trend estimates. With the intent of providing the most realistic uncertainty intervals for climate data record time series data, this study discusses problems and limitations of current approaches. It emphasizes the need to account for the combined influence of measurement uncertainties (i.e., stability of the observational system) and natural climate variability on trend uncertainty. This study proposes a novel trend-uncertainty assessment approach unifying available measurement uncertainty information with empirical modelling of natural climate variability within the same trend-estimation framework. As a proof of concept, the proposed approach is applied to the analysis of trends in a Global Mean Sea Level (GMSL) time-series. This GMSL application demonstrates that combining available measurement uncertainty assessment with variance modelling is expected to lead to more realistic uncertainty evaluations in sea-level trends. This unified approach is potentially applicable to virtually any CDR and could enhance the reliability of climate change analysis through an improved trend uncertainty assessment in climate studies

Cumulative-Time Signal Temporal Logic

Signal Temporal Logic (STL) is a widely adopted specification language for Cyber-Physical Systems that can be used to express critical temporal requirements, such as system safety and response time. STL’s expressivity, however, is not sufficient to capture the cumulative duration during which a property holds within an interval of time. To overcome this limitation, we introduce Cumulative-Time Signal Temporal Logic (CT-STL) which operates over discrete-time signals and extends STL with a new cumulative-time operator. This operator compares the sum of all time steps for which its nested formula is true with a threshold. We present both a qualitative and a quantitative (robustness) semantics for CT-STL and prove the soundness and completeness of the robustness semantics. We also provide an efficient online monitoring algorithm for both semantics. We demonstrate the utility of CT-STL via two case studies: specifying and monitoring cumulative temporal requirements for a microgrid and an artificial pancreas

Effects of Isolated and Installed Turbofan Engine Nozzle Flows on Nozzle Pressure Coefficients for Various Thrust Ratings

In den letzten Jahrzehnten hat die Entwicklung von Turbofan-Triebwerken zu einer substanziellen Reduktion von Betriebskosten, spezifischem Treibstoffverbrauch und Lärmemissionen geführt. Für weiter Verbesserungen ist es notwendig, die aerodynamischen Phänomene, die mit modernen Triebwerken mit niedrigem Fandruckverhältnis (Fan Pressure Ratio, FPR) und ultra hohem Nebenstromverhältnis (Ultra High Bypass Ratio, UHBR) verbunden sind, besser zu verstehen. Diese Arbeit befasst sich mit den Auswirkungen der Strömungsunterdrückung infolge der Wechselwirkungen zwischen dem Triebwerksabgasstrom und der Luftfahrzeugzelle, die den statischen Druck am Düsenauslass erhöhen und damit zu einer Reduktion des Düsendruckverhältnisses, des -massenstroms und des Schubs führen.Um zwischen Effekten der Außenumströmung der Gondel und dem aerodynamischen Einfluss des Flügels zu unterscheiden, wurde eine umfassende Strömungssimulationskampagne durchgeführt. Siemens Simcenter STAR-CCM+ wurde zur Erstellung der Simulationen verwendet. Die Simulationen wurden mit der Infrastruktur von Austrian Scientific Computing (ASC) durchgeführt.Die Reynoldsgemittelten Navier-Stokes-Gleichungen (RANS) wurden unter Verwendung des Spalart-Allmaras-Turbulenzmodells gelöst. Eine Gitterkonvergenzstudie wurde sowohl für die isolierte Konfiguration (nur Triebwerk) als auch für die installierte Konfiguration (Triebwerk mit Pylon am Flügel) durchgeführt, wobei ein Kompromiss zwischen numerischer Genauigkeit und Rechenaufwand gefunden wurde.Der im Rahmen der Studie eingesetzte Triebwerksimulator (Turbofan Propulsion Simulator, TPS) verwendete ein Aktuatorscheibenmodell für die Schuberzeugung durch den Fan und den Triebwerkskern. Der Triebwerkssimulator ist im Gegensatz zu den sogenannten Durchflussgondeln (Through Flow Nacelles, TFN), in der Lage, Schub zu erzeugen. Für die Flügel-Rumpfkombination wurde das Common Research Model (CRM) der NASA verwendet. Flügel, Rumpf, Pylon und Triebwerk wurden in voller Größe modelliert. Ein 0-D-Gasdynamikmodell wurde verwendet, um die wichtigsten geometrischen Parameter des Triebwerks wie Fan-Fläche, effektive Kern- und Fandüseneinlass- und -auslassflächen sowie die thermophysikalischen Größen an diesen Stationen zu berechnen, die als Randbedingungen in den Simulationen dienen. Das Triebwerk wurde für ein Fandruckverhältnis von 1,3 und einen geeigneten Mantelstrom-Nettoschub eines modernen Langstrecken-Großraumflugzeug ausgelegt, indem der Fandurchmesser auf 3,7 Meter eingestellt wurde.Die paramterischen Triebwerksgeometrien für Kern, Fandüse, Gondel und Pylon wurden mit Hilfe der Class Shape Transformation (CST)-Kurven gebildet, um die grundlegenden Hauptabmessungen steuern zu können. Die Geometrien wurden mit MATLAB und CATIA erstellt.In der Simulationkampagne wurde das Triebwerk unter verschiedenen Flugbedingungen betrieben. Die Flugmachzahl würde im Bereich zwischen 0,4 und 0,8, der Anstellwinkel zwischen -6 Grad und +8 Grad und das Fandruckverhältnis von 1,0 bis 1,35 sowohl in der isolierten als auch in der installierten Konfiguration variiert. Die Simulationsergebnisse wurden extrahiert und die Installationseffekte durch den Vergleich des Fandüsenauslassdruckkoeffizienten, des modifizierten Auslasskoeffizienten und der Düsendruckverhältnisse analysiert. Die Wirkung der Außenumströmung der Gondel sowie der Flügelumströmung wurden durch die Untersuchung der isolierten als auch der installierten Konfigurationen herausgearbeitet, sodass ein umfassendes Bild der Strömungsunterdrückung an der Fandüse gewonnen werden konnte.Over the last decades, turbofan engine development has led to substantial reductions in operating cost, specific fuel consumption and noise emissions. Understanding aerodynamic phenomena that are related to modern low Fan Pressure Ratio, Ultra High Bypass Ratio engines that affect performance is necessary for further improvements.This work focuses on engine flow suppression effects due to mutual interaction between the engine exhaust stream and the airframe, which increases the static pressure in the nozzle exit areas, leading to a reduction of the nozzle pressure ratio, nozzle mass flow, and ultimately thrust.In order to distinguish between the contributions of the nacelle external flow effects and those created by the aerodynamic presence of the wing, an exhaustive CFD-simulation campaign was devised. The Siemens Simcenter STAR-CCM+ platform was used to setup the simulation and the computational results presented have been achieved using the Austrian Scientific Computing (ASC) infrastructure.Reynolds Averaged Navier-Stokes equations (RANS) were solved using the Spalart-Allmaras turbulence model. A mesh convergence study was performed for the isolated (engine alone), as well as the installed (engine with pylon on wing) configuration and a compromise was made between accuracy and numerical expense.The turbofan propulsion simulator (TPS) employed in the study used an actuator disc model for thrust production by the fan and the core, which is in contrast to Through Flow Nacelles (TFN) which do not generate any thrust. For the Wing and Fuselage combination, NASA's Common Research Model (CRM) was employed. The wing, fuselage, pylon and engine were modeled at aircraft full scale.A 0-D gas dynamics model was used to calculated the main geometric engine parameters like fan area, effective core and fan nozzle inlet and exit areas, as well as the thermophysical properties used as boundary conditions. The engine was sized for an FPR of 1,3 and an appropriate net thrust for a modern wide-body long range aircraft was obtained by adjusting the fan diameter to 3.7m.The engine geometries for the core and the fan nozzle, the nacelle, and the pylon were generated using Class Shape Transformation (CST) curves to allow basic control of the main aeroshape dimensions. Geometries were generated using MATLAB and CATIA.In the simulation program, the engine was run under different flight conditions, varying the cruise flight Mach number between 0.4 and 0.8, the angle of attack from -6 degrees to +8 degrees, and the fan pressure ratio between 1.0 and 1.35 both in the isolated and installed configuration. Simulation results were extracted and the installation effects were discussed by means of the fan nozzle exit pressure coefficient, the modified discharge coefficient and the nozzle pressure ratios. Nacelle external flow effects and wing aerodynamic effects were outlined by investigating both the isolated and the installed configurations and a comprehensive picture of fan nozzle flow suppression was drawn

Fortschritte in der Kobalt Pincer Chemie

In dieser Arbeit wurde die Aktivität der aus der Literatur bekannten Komplexe [Co(PCPNMe-iPr)(NO)]PF6 und [Co(PCPNMe-iPr)(NO)H] hinsichtlich der Hydrosilylierung von Alkenen, der Isomerisierung von Allylbenzolen und der Hydrierung verschiedener funktioneller Gruppen untersucht. Es wurde festgestellt, dass der Hydridkomplex [Co(PCPNMe-iPr)(NO)H] katalytische Aktivität in der Hydrierung von Alkenen zeigt. Die Reaktion wurde optimiert und die Limitierungen des katalytischen Systems untersucht.Anschließend wurde ein PCPNEt-Ligand verwendet, um vier [Co(PCPNEt)]-Komplexe analog zu den [Co(PCPNMe)]-Verbindungen zu synthetisieren. Eine Kristallstruktur konnte vom paramagnetischen Komplex [Co(PCPNMe)Cl] erhalten werden, während die diamagnetischen Spezies mittels 1H-, 13C{1H}- und 31P{1H}-NMR- sowie IR-Spektroskopie charakterisiert wurden.Des Weiteren wurden zwei neue PCN-Liganden synthetisiert und mittels NMR-Spektroskopie charakterisiert. Komplexierungsreaktionen mit Co2(CO)8 wurden durchgeführt, und mögliche Produkte wurden auf Basis der aufgenommenen IR-Spektren sowie der vorhandenen Literatur diskutiert.In this work, the activity of literature-known complexes [Co(PCPNMe-iPr)(NO)]PF6 and [Co(PCPNMe-iPr)(NO)H] was investigated towards the hydrosilylation of alkenes, isomerization of allylbenzenes, and hydrogenation of various functional groups. It was discovered that the hydride complex [Co(PCPNMe-iPr)(NO)H] is active in the hydrogenation of alkenes. The reaction was optimized, and the substrate scope and limitations of the catalytic system were determined.Subsequently, a PCPNEt ligand was used to synthesize four [Co(PCPNEt)] complexes in analogy to the [Co(PCPNMe)] compounds. A crystal structure was obtained from the paramagnetic complex [Co(PCPNMe)Cl], whereas the diamagnetic species were characterized by 1H-, 13C{1H}- and 31P{1H}-NMR, and IR spectroscopy.Furthermore, two PCN ligands were synthesized and characterized by NMR spectroscopy. Complexation reactions with Co2(CO)8 were performed, yielding paramagnetic products, whose structural features were discussed based on the recorded IR spectra and literature data for complexation reactions of PCP ligands in a similar manner