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THE SPACE OF FINITE-ENERGY METRICS OVER A DEGENERATION OF COMPLEX MANIFOLDS
Get PDFGiven a degeneration of projective complex manifolds X ← D∗ with meromorphic singularities, and a relatively ample line bundle L on X, we study spaces of plurisubharmonic metrics on L, with particular focus on (relative) finite-energy conditions. We endow the space ϵ 1(L) of relatively maximal, relative finite-energy metrics with a d1-type distance given by the Lelong number at zero of the collection of fiberwise Darvas d1-distances. We show that this metric structure is complete and geodesic. Seeing X and L as schemes XK, LK over the discretely-valued field K = C((t)) of complex Laurent series, we show that the space ϵ1(Lan K ) of non-Archimedean finite-energy metrics over Lan K embeds isometrically and geodesically into ϵ 1(L), and characterize its image. This generalizes previous work of Berman-Boucksom-Jonsson, treating the trivially-valued case
Comparing Anomaly Detection and Classification Algorithms: A Case Study in Two Domains
No full textUtilizing large data sets in practical scenarios usually requires identifying, annotating and classifying rare events or anomalies. Although several methods exists, there are two classes of algorithms: anomaly detection algorithms and classification algorithms. Both types of algorithms have different characteristics and in this paper, we set out to compare them on two cases. We use data from a neurointensive care unit and from microwave radio transmissions. We apply Isolation Forest and Random Forest algorithms to find events in the data that occur with a frequency of ca. 1%. The results show that classification algorithms (Random Forest) perform better and can achieve up to 100% accuracy, while the anomaly detection algorithms (Isolation Forest) can achieve only 73% at best. Based on the results, we conclude that it is better to invest in annotating data \ue1 priori and use classification algorithms, despite the lower costs of using the anomaly detection algorithms
Interaction of water with supplementary cementitious materials: Hydration mechanism, microstructure and moisture transport
No full textSupplementary cementitious materials (SCMs) offer a sustainable solution to reduce carbon emissions from the production of cement and concrete. This dissertation explores the impact of SCMs and the related additives on the hydration process of cementitious materials, which can affect their microstructure and transport properties. Water is involved in the whole life of the cementitious materials thereby determining the hydration, microstructure and durability. Advanced techniques were employed in this study to investigate the impact of additives on the hydration of C3S, examining microstructure refinement by SCMs and its relationship to transport processes, and assessing changes in water dynamics. A device was designed to continuously monitor the effect of SCMs on early hydration, and it was subsequently updated to monitor the hardening process of concrete containing SCMs.Results show that the dissolution theory fails to explain anomalous hydration of tricalcium silicate at high water to solid ratio. A new hypothesis in this study proposes that calcium silicate hydrate (C-S-H) primarily nucleates within the near-surface region, and this hypothesis bridges the gap between dissolution and protective layer theories. The designed device performs well in monitoring water interaction with SCMs. The evolution of electrical conductivity in hydrating pastes closely relates to chemical reaction processes and can be classified into four stages. The growth rate of the formation factor indicates the reactivity of different binders. Blending SCMs refines the pore structure, decreases pore connectivity and results in a higher formation factor. SCMs affect the pore structure of, the phase assemblage and water dynamics. The mesoscale pore structure in pastes with SCMs can be well indicated by water vapour desorption isotherms, but ion effects on water vapour equilibrium pressure must be considered when calculating pore size distribution. A novel approach works well in evaluating the hydration degree of SCMs by use of water vapour sorption and thermodynamic modelling. Thermoporometry and broadband dielectric spectroscopy effectively characterise moisture distribution and dynamics in hcps, respectively. SCMs have limited effects on the dynamics of structural water, primarily influencing water dynamic in small gel pores and interfacial polarization. The first drying process decreases the volume of unfrozen water (< ~2.4 nm) under various levels of relative humidity. Gel pores coarsen significantly during the drying between 75 % and 50 %. Change of microstructure alters the transport of moisture and chloride in hcp. The decrease in both moisture transport coefficient and chloride migration coefficient induced by SCMs is notably more significant in hcp with a higher water to binder ratio. The modified moisture transport in blended systems is primarily due to pore structure refinement, specifically the reduction in pore connectivity. Both the formation factor and porosity of small pores determine the moisture transport properties of hcp, with the formation factor being more significant at high RH and the porosity of small pores being more significant at low RH. The effect of SCMs on chloride is also due to the decrease in pore. A simplified model based on the formation factor of hcp can be used to estimate the chloride migration coefficient for the blended pastes and mortars.The upgraded device provides a reliable non-destructive monitoring of concrete performance. Formation factor and ultrasonic pulse velocity are reliable indices for concrete strength; however, formation factor exhibits the optimal performance. This study provides insights into the mechanism of how water interacts with cementitious materials and a new non-destructive monitoring method to promote the application of SCMs in sustainable concretes
Optimizing Jastrow factors for the transcorrelated method
Get PDFWe investigate the optimization of flexible tailored real-space Jastrow factors for use in the transcorrelated (TC) method in combination with highly accurate quantum chemistry methods, such as initiator full configuration interaction quantum Monte Carlo (FCIQMC). Jastrow factors obtained by minimizing the variance of the TC reference energy are found to yield better, more consistent results than those obtained by minimizing the variational energy. We compute all-electron atomization energies for the challenging first-row molecules C2, CN, N2, and O2 and find that the TC method yields chemically accurate results using only the cc-pVTZ basis set, roughly matching the accuracy of non-TC calculations with the much larger cc-pV5Z basis set. We also investigate an approximation in which pure three-body excitations are neglected from the TC-FCIQMC dynamics, saving storage and computational costs, and show that it affects relative energies negligibly. Our results demonstrate that the combination of tailored real-space Jastrow factors with the multi-configurational TC-FCIQMC method provides a route to obtaining chemical accuracy using modest basis sets, obviating the need for basis-set extrapolation and composite techniques
How do expert and non-expert drivers interact with cyclists at unsignalized intersections? Results from naturalistic data
No full textEducation, training and mobility, knowledge management: towards a common effort to ensure a future workforce in Europe and abroad
Get PDFContinuous and future-oriented education and training as well as knowledge management for young talents are required for the safe and reliable operation of nuclear reactors and nuclear facilities in Europe. A dedicated line of collaborative projects addresses the specific needs, such as lack of personnel (project ENEN+: “attract, retain and develop new nuclear talents beyond academic curricula”). State-of-the-art approaches and in-depth knowledge are provided when it comes to reactor physics (project GRE@T-PIONEeR: “graduate education alliance for teaching the physics and safety of nuclear reactors”) or nuclear radiochemistry (project A-CINCH: “augmented cooperation in education and training in nuclear and radiochemistry”). A highly skilled nuclear engineer must undergo experimental work to better observe theoretical principles at work. Following the ENEEP (European nuclear experimental educational platform) initiative, a network of research reactors and special laboratories is made available for performing such activities. Another issue found is that the results of Euratom-funded research activities are spread across multiple platforms and websites making it difficult to find relevant information within a reasonable timeframe. Such a situation requires the application of knowledge management actions. The PIKNUS project aims to define a concept of a knowledge management method and tool to improve the sharing and availability of Euratom research results. All projects successfully demonstrate that European collaboration could address certain needs to attract, develop and retain young talents in future-oriented nuclear fields
Investigation of the stent induced deformation on hemodynamic of internal carotid aneurysms by computational fluid dynamics
Get PDFApplication of the stent for treatment of the internal carotid artery (ICA) aneurysms has been extensively increased in recent decades. In the present work, stent-induced deformations of the parent vessel of ICA aneurysms are fully investigated. This study tries to visualize blood stream and calculated hemodynamic factors inside the four ICA aneurysms after deformations of parent vessel. For the simulation of the non-Newtonian blood stream, computational fluid dynamic is applied with one-way Fluid–Solid interaction (FSI) approach. Four ICA aneurysms with different ostium sizes and neck vessel angle are selected for this investigation. Wall shear stress on wall of aneurysm is analyzed in two angles of deformation due to application of the stent. Blood flow investigation shows that the deformation of the aneurysm limited blood entrance to the sac region and this decreases the blood velocity and consequently oscillatory shear index (OSI) on the sac wall. It is also observed that the stent-induced deformation is more effective on those cases with extraordinary OSI values on aneurysm wall
Sound and vibration influence overall ride comfort in a combustion passenger car under different driving scenarios
No full textA variety of factors, such as sound, vibration and seating system influence the perceived overall ride comfort in passenger cars. However, these influences are not constant across different driving scenarios. The purpose of this study is to identify how human experiences regarding sound and vibration varied in eight different driving scenarios. A user study was conducted with ten participants in a combustion passenger car. The results showed that dynamic discomfort was affected by induced body movement, annoying sounds and the discordance between sound and vibration. Tyre-road noise and wind noise dominated the perceived sound annoyance at lower and higher speed, respectively. The vibration annoyance was mostly judged by induced body movements. The conclusion was that the influences of sound and vibration on perceived ride comfort change in different driving scenarios, and thus, overall ride comfort should be evaluated in different ways depending on the chosen driving scenario
High-Q Trampoline Resonators from Strained Crystalline InGaP for Integrated Free-Space Optomechanics
Get PDFNanomechanical resonators realized from tensile-strained materials reach ultralow mechanical dissipation in the kHz to MHz frequency range. Tensile-strained crystalline materials that are compatible with epitaxial growth of heterostructures would thereby at the same time allow realizing monolithic free-space optomechanical devices, which benefit from stability, ultrasmall mode volumes, and scalability. In our work, we demonstrate nanomechanical string and trampoline resonators made from tensile-strained InGaP, which is a crystalline material that is epitaxially grown on an AlGaAs heterostructure. We characterize the mechanical properties of suspended InGaP nanostrings, such as anisotropic stress, yield strength, and intrinsic quality factor. We find that the latter degrades over time. We reach mechanical quality factors surpassing 107 at room temperature with a Q\ub7f product as high as 7
7 1011Hz with trampoline-shaped resonators. The trampoline is patterned with a photonic crystal to engineer its out-of-plane reflectivity, desired for efficient signal transduction of mechanical motion to light
Twist-angle dependent dehybridization of momentum-indirect excitons in MoSe2/MoS2 heterostructures
Get PDFThe moir\ue9 superlattice has emerged as a powerful way to tune excitonic properties in two-dimensional van der Waals structures. However, the current understanding of the influence of the twist angle for interlayer excitons (IXs) in heterostructures is mainly limited to momentum-direct K-K transitions. In this work, we use a judicious combination of spectroscopy and many-particle theory to investigate the influence of the twist angle on momentum-indirect IXs of a MoSe2/MoS2 heterostructure. Here, the energetically lowest state is a dark and strongly hybridized ΓK exciton. We show that increasing the twist angle from an aligned structure (0∘ or 60∘) gives rise to a large blue shift of the IX, which is a manifestation of the strong dehybridization of this state. Moreover, for small twist angle heterostructures, our photoluminescence measurements reveal contributions from two IX states, which our modelling attributes to transitions from different moir\ue9 minibands. Our finding contributes to a better fundamental understanding of the influence of the moir\ue9 pattern on the hybridization of momentum-dark IX states, which may be important for applications in moir\ue9-tronics including novel quantum technologies