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Solving an industrially relevant quantum chemistry problem on quantum hardware
No full textQuantum chemical calculations are among the most promising applications for quantum computing. Implementations of dedicated quantum algorithms on available quantum hardware were so far, however, mostly limited to comparatively simple systems without strong correlations. As such, they can also be addressed by classically efficient single-reference methods. Here we calculate the lowest energy eigenvalue of active space Hamiltonians of industrially relevant and strongly correlated metal chelates on trapped ion quantum hardware, and integrate the results into a typical industrial quantum chemical workflow to arrive at chemically meaningful properties. We are able to achieve chemical accuracy by training a variational quantum algorithm on quantum hardware, followed by a classical diagonalization in the subspace of states measured as outputs of the quantum circuit. This approach is particularly measurement-efficient, requiring 600 single-shot measurements per cost function evaluation on a ten qubit system, and allows for efficient post-processing to handle erroneous runs
A contribution to mitigate NOₓ and H₂O emissions for a hydrogen-powered hypersonic vehicle
No full textHypersonic transport fueled with liquid hydrogen (LH2-HST) is currently considered as long-term future technology of civil aviation to fly with speeds greater than Mach 5 at stratospheric altitudes of 25–38 km. In this paper, we present a comprehensive methodology to assess the emission mitigation potential (via NOx and H2O) of future LH2-HST through operational measures, considering realistic constraints such as the sonic boom carpet as well as tolerable g-forces acting on the passengers while flying with hypersonic speeds. Both NOx- and H2O-optimal 4D-trajectories are identified by a brute-force algorithm that varies the initial cruise altitude from 30 to 36 km. As case study, the Mach 8 passenger aircraft STRATOFLY-MR3, which was conceptually developed in the framework of the H2020 STRATOFLY project, is operated on a single route from Brussels (BRU) to Sydney (MYA). The findings are highlighted as relative changes regarding MR3's design flight altitude set at 32 km, respectively, 105 000 ft. As scientific contribution, 3D emission inventories are calculated and made publicly available for a world fleet of MR3 aircraft operated along the BRU-MYA route on both NOx- and H2O-optimal mission profiles in the year 2075
Dealing with regression models’ endogeneity by means of an adjusted estimator for the Gaussian copula approach
No full textEndogeneity in regression models is a key marketing research concern. The Gaussian copula approach offers an instrumental variable (IV)-free technique to mitigate endogeneity bias in regression models. Previous research revealed substantial finite sample bias when applying this method to regression models with an intercept. This is particularly problematic as models in marketing studies almost always require an intercept. To resolve this limitation, our research determines the bias’s sources, making several methodological advances in the process. First, we show that the cumulative distribution function estimation’s quality strongly affects the Gaussian copula approach’s performance. Second, we use this insight to develop an adjusted estimator that improves the Gaussian copula approach’s finite sample performance in regression models with (and without) an intercept. Third, as a broader contribution, we extend the framework for copula estimation to models with multiple endogenous variables on continuous scales and exogenous variables on discrete and continuous scales, and non-linearities such as interaction terms. Fourth, simulation studies confirm that the new adjusted estimator outperforms the established ones. Further simulations also underscore that our extended framework allows researchers to validly deal with multiple endogenous and exogenous regressors, and the interactions between them. Fifth, we demonstrate the adjusted estimator and the general framework’s systematic application, using an empirical marketing example with real-world data. These contributions enable researchers in marketing and other disciplines to effectively address endogeneity problems in their models by using the improved Gaussian copula approach
3D micromechanical interaction of thin-film retained austenite and lath martensite by computational plasticity
No full textTo exploit the full potential of advanced high-strength steels (AHSS), a more in-depth understanding of the complex micromechanical interaction of thin-film retained austenite (RA) and lath martensite is indispensable. Inspired by the medium-Mn steel microstructure, a three-dimensional micromechanical modeling approach is therefore proposed in the present work, embedding the thin RA films explicitly into the hierarchical lath martensite structure. This enables systematic studies of the effect of RA film thickness and volume fraction on the local stresses and strains as well as their partitioning within the microstructure. The investigations reveal that with shrinking RA volume fraction, both stress and especially strain heterogeneity in the thin-film RA intensifies. In the martensite blocks, stress and strain heterogeneity also intensifies, although stresses are generally more heterogeneously, and strains much more homogeneously, distributed than in RA. The results underline the key role of RA with thin-film morphology for further optimizing AHSS microstructures
Development of novel microaerogel particles from pea protein and their application as ingredient for low-saturated fat cocoa spreads
No full textPea protein aqueous dispersions at 18% (w/w) were subjected to thermal gelation at the isoelectric pH, followed by water-to-ethanol solvent exchange and supercritical-CO2 drying. The obtained particles presented a size in the range of 10–50 μm and showed internal surface area (142 m2/g), density (0.28 g/cm3) and porosity (79%) values typical of aerogels. Their SEM microstructure revealed a peculiar hierarchical structure of aggregated dried microgels. The obtained particles were thus defined pea protein microaerogel particles. One g of microaerogel particles were able to structure 1.7 g of oil, turning it in a viscoelastic material. Based on this, the microaerogel particles were used in the preparation of cocoa spreads containing sunflower oil solely as lipid phase. The spreads containing up to 2% (w/w) microaerogel particles showed rheological moduli and spreadability behaviour comparable to those of commercial spreads, along with high physical stability (oil holding capacity >96%). Despite the similar physical properties, the saturated fatty acid content of the developed spreads was up to 57% lower than that of commercial spreads. Obtained results highlight the possibility to obtain microaerogel particles from plant proteins and demonstrate their applicability as oil structuring ingredients, suitable for the design of spreads with physical properties similar to those of market products but with a healthier lipidic profile
Effective nudging in product design - a case study in the window construction industry
No full textThe growing complexity of product design poses a challenge for team management. Nudging, a targeted behavioral influence method, offers a potential tool to address this matter. This study explores how nudges can aid product developers in decision-making. A field study in the innovation management department in the home appliances industry identified effective nudges and their degree of contribution. A workshop format introduced managers to nudge design and use. Findings showed positive impacts of nudges, notably improving transparency, collaboration, and team awareness, proving to be a promising tool for managing complex innovation processes in practical application
Erosion threshold of cohesive sediments in the German Wadden Sea: temporal variability and comparison of in-situ and laboratory experiments
No full textA newly developed in-situ setup of the Closed Gust Erosion Microcosm System (C-GEMS) was utilized for erosion experiments in a tidal mudflat in the mouth of the Elbe in the German Wadden Sea to investigate the temporal variability of the erosion threshold τc of cohesive sediments. In addition, erosion experiments with extracted sediment cores from the same site were conducted in the field and in the laboratory with the identical device to analyze the influence of sample extraction and transport on the derived erosion threshold. A total of 21 erosion experiments were carried out in four measuring campaigns between April and September 2024. The erosion thresholds derived from the in-situ experiments exhibit considerable temporal variability across campaigns, with values of τc = 0.1–0.27 N/m2, while repeated experiments within the individual campaigns demonstrate a high degree of reproducibility. Accompanying analyses of surface sediment particle size distribution and bulk density revealed that mud concentration (clay and silt) varied with wind conditions and the associated hydrodynamic load prior to the measurement campaigns. The observed temporal variability in τc is reasonably well captured by a mathematical model based on mud concentration and particle size, suggesting that τc can be plausibly estimated from these parameters. For campaigns with a cohesive surface sediment layer, erosion thresholds derived in the ex-situ experiments are consistently lower than those obtained in the in-situ experiments. This is attributed to the disturbance of the surface sediments due to mechanical extraction and liquefaction during transport. The findings offer insights into the transport dynamics of cohesive sediments and help guide decisions on whether future erosion experiments should be conducted in situ, despite the significant effort involved, or whether extracted sediment cores are a suitable alternative
Non-proportional plastic deformation at the micron scale: Single crystal Cu cantilever beams subjected to orthogonal bending
No full textExperiments involving abrupt non-collinear changes in the direction of loading in the plastic range have been performed on micron-scale, single crystal Cu cantilever beams to provide the first data of its kind on non-proportional loading. The data is used to assess whether existing strain gradient plasticity (SGP) theories are capable of reproducing complex deformation histories representative of micron-scale metal forming processes, for which non-proportional loading is common. The data is also used to explore an issue that has arisen in efforts to develop SGP that is sufficiently accurate for engineering applications and yet not overly complex. Specifically, using a combination of experimentation and computation, the paper examines the differences in predictions made by two classes of theories presently in the mainstream, termed “incremental” and “non-incremental”, when non-proportional plastic loading occurs at the micron scale. Orthogonal bend experiments are performed on Cu single crystal cantilever beams with square cross-sections that are symmetrically oriented with respect to the vertical and horizonal bending axes. In Stage 1, the force applied to the end of the cantilever is vertical, producing bending in the vertical plane. Abruptly, in Stage 2, a horizontal force is applied with either the vertical force held constant (force control) or the vertical end-displacement of the beam held constant (displacement control). Three cantilever sizes, with widths of the square cross-section of 2, 5 and 20 microns, have been tested. The strength elevation for cantilever widths decreasing from 20 to 2 microns is about a factor of three as compared to what would be expected based on conventional plasticity theory. The incremental and non-incremental SGP theories both capture the full non-proportional loading history, including the size effect. However, they differ in their predictions of behavior in the early portion of Stage 2, due to the abrupt change in the loading path. This difference will be assessed with the aid of experimental test data
Debottlenecking a 2-phase multi-enzymatic cascade by an enzyme membrane reactor – Modelling and experimental validation
No full textBiotechnological processes have a high potential to make industrial processes more sustainable. However, biotechnological processes often have low product concentrations and production rates. This is where process intensification can help to make these processes competitive. Using the example of the multi-enzymatic synthesis of natural cinnamyl cinnamate, it is shown how an existing multi-enzymatic process can be intensified by using an enzyme membrane reactor. The individual enzymatic reactions are first characterised in laboratory scale and then combined in a mini plant. In addition, a process model of the mini plant is developed. It is shown that the use of an enzyme membrane reactor can increase the production rate of the multi-enzymatic process by a factor of 10 compared to a previously investigated set-up
Car dependence and car ownership among carsharing users and the mitigating effect of having multiple carsharing memberships: a moderated mediation analysis
No full textAs business-to-consumer carsharing continues to expand on a global scale, it is probable that a growing number of carsharing users will become enrolled in multiple carsharing services concurrently, particularly in major cities. However, extant literature offers scant insight into whether and to what extent enrollment in multiple services shapes the perception of carsharing as a substitute for car ownership. In addressing this gap, this paper aims to examine how having multiple carsharing memberships affects the relationship between carsharing users’ perceived car dependence, their perception of the suitability of carsharing to meet their car travel needs, and, consequently, their car ownership. To this end, a moderated mediation analysis was conducted with a sample of 788 carsharing users (including 362 individuals with multiple memberships) in the inner city of Hamburg, Germany. The findings suggest that heightened car dependence diminishes the perception of carsharing as a substitute for car ownership, thereby increasing the odds of car ownership. However, having multiple carsharing memberships was found to mitigate this effect. While surveyed carsharing users with more than one membership reported higher levels of car dependence compared to users with only one membership, they were more inclined to perceive carsharing as a viable alternative to car ownership. The moderating influence of multiple carsharing memberships was particularly pronounced among carsharing users with relatively high levels of car dependence, while among carsharing users with relatively low levels of car dependence, having multiple memberships did not lead to significantly more positive perceptions of carsharing or significantly lower car ownership