École Polytechnique Fédérale de Lausanne
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Ertüchtigung von Stahlbetonbrücken mit UHFB – Erfahrungen aus 400+ Anwendungen = [Renewal of reinforced concrete bridges by means of UHPFRC - Experiences from 400+ applications]
No full textRenewal of reinforced concrete bridges by means of UHPFRC – Experiences from 400+ applications. Ultra-High-Performance Fiber-Reinforced Cementitious composite UHPFRC is a novel building material that is characterized by high mechanical strength and durability. UHPFRC is used in Switzerland for 20 years to rehabilitate and strengthen existing reinforced concrete bridges. This article first appraises more than 400 UHPFRC applications. The findings from numerous applications when casting UHPFRC on bridge deck slabs are prepared in such a way that they can be adopted ready for use by the interested reader. Finally, a recently completed example of a 65-year-old reinforced concrete bridge strengthened with UHPFRC shows how the basic concepts and the great potential of the UHPFRC technology can be transferred into practice, while preserving resources and building culture values.GIS-GEText in German & summary in Englis
Boosting Resource-Constrained Federated Learning Systems with Guessed Updates
No full textFederated learning (FL) enables a set of client devices to collaboratively train a model without sharing raw data. This process, though, operates under the constrained computation and communication resources of edge devices. These constraints combined with systems heterogeneity force some participating clients to perform fewer local updates than expected by the server, thus slowing down convergence. Exhaustive tuning of hyperparameters in FL, furthermore, can be resource-intensive, without which the convergence is adversely affected. In this work, we propose GEL, the guess and learn algorithm. GEL enables constrained edge devices to perform additional learning through guessed updates on top of gradient-based steps. These guesses are gradientless, i.e., participating clients leverage them for free. Our generic guessing algorithm (i) can be flexibly combined with several state-of-the-art algorithms including FedProx + GeL, FedNova, FedYogi or ScaleFL; and (ii) achieves significantly improved performance when the learning rates are not best tuned. We conduct extensive experiments and show that GEL can boost empirical convergence by up to 40% in resourceconstrained networks while relieving the need for exhaustive learning rate tuning.SAC
Data-Driven LPV Control for Harmonic Disturbance Rejection in a Hybrid Isolation Platform
No full textA novel approach for linear parameter-varying (LPV) controller synthesis for adaptive rejection of frequency-varying sinusoidal disturbances is proposed. Only the frequency response data of a linear time-invariant (LTI) multiple-input-multiple-output (MIMO) system are used to design the LPV controller that stabilizes the system for arbitrarily fast variation of the disturbance frequencies. Global stability is achieved thanks to the specific structure of the LPV controller and the use of integral quadratic constraints (IQCs) to represent the frequency variations. The LPV controller is designed by convex optimization in the frequency domain. A hybrid microvibration damping platform (MIVIDA) for space applications is considered for experimental validation of the proposed method. An LPV controller for rejection of unknown frequency-varying sinusoidal disturbances is designed and implemented on the real system. Experimental results demonstrate the effectiveness of the proposed approach in asymptotically rejecting disturbances and ensuring closed-loop stability against arbitrarily fast variations in disturbance frequencies.SCI-STI-A
Svtudy of charmonium production via the decay to p p at √s=13 TeV
No full textCharmonium production cross-section in protonpvroton collisions is measured at the centre-of-mass energy root s = 13 TeV using decays to pp final state. The study is performed using a data sample corresponding to an integrated luminosity of 2.2 fb(-1) collected in 2018 with the LHCb detector. The production cross-section of the h(c) meson is measured in a rapidity range of 2.0 < y < 4.0 and in a transverse momentum range of 5.0 < p(T) < 20.0GeV/c, which is extended compared with previous LHCb analyses. The differential cross-section is measured in bins of pT and, for the first time, of y. Upper limits, at 90% and 95% confidence levels, on the h(c)(2S) and h(c)(1P) prompt production cross-sections are determined for the first time.LPHE-OSPH-SBLPHE-RMLPHE-L
Monocrystalline Gold Metasurface to Control Anisotropic Second‐Harmonic Generation (Advanced Optical Materials 13/2025)
No full textNA
Nonuniform Chiralization of Metal-Organic Frameworks Using Imine Chemistry
No full textHomochiral metal-organic frameworks (MOFs) are exceptional media for heterogeneous enantiodifferentiation processes. Modifying available achiral structure-bearing MOF scaffolds is a preferred method to extend this class of materials. Reported postsynthetic covalent chiralizations generally lead to uniform, site-specific modifications. The use of chemically versatile modifying agents, like aldehydes, may instead result in the statistical formation of chemically nonuniform anchored products. In addition, the use of such modifying agents gives rise to spatial nonuniformities in the radial direction, due to prohibited diffusion through the MOF bulk. The advantageous grain structure formation plus molecular nonuniformity greatly increase the complexity of such systems. The use of such modifying agents, therefore, necessitates a broader holistic characterization. The present work explores the adaptation of imine chemistry for postsynthetic chiralization. A chiral aldehyde and a chiral ketone are probed on two amine-functionalized MOF substrates-MIL-125 NH2 and UiO-66 NH2. The UiO-66 NH2 modified with the natural product-derived (R)-2,2-dimethyl-1,3-dioxolane-4-carboxaldehyde ((R)-1 aldehyde) is found to have the best performance in terms of reactivity and MOF stability. A comprehensive toolbox of methods was demonstrated to robustly characterize the obtained material. This includes high-resolution accurate mass electrospray ionization mass spectrometry (HRAM-ESI-MS) to reveal the competing reactions that yield a set of oligomer-rich structures. In silico modeling correctly predicts the localization of the modification. The modification is found to be covalent and chiral and mainly proceeds through imine formation, resulting in a surface enantioselector display formation. Restricted diffusion lengths in the solid phase infer good retention of resolving power in ascending van Deemter regimes in chromatography. Meeting this criterion makes the yielding material a promising potential stationary phase candidate for performant chromatographic enantioseparations.LSMOISIC-MSEAPCIME-G
Feasibility of multiomics tumor profiling for guiding treatment of melanoma
No full textThere is limited evidence supporting the feasibility of using omics and functional technologies to inform treatment decisions. Here we present results from a cohort of 116 melanoma patients in the prospective, multicentric observational Tumor Profiler (TuPro) precision oncology project. Nine independent technologies, mostly at single-cell level, were used to analyze 126 patient samples, generating up to 500 Gb of data per sample (40,000 potential markers) within 4 weeks. Among established and experimental markers, the molecular tumor board selected 54 to inform its treatment recommendations. In 75% of cases, TuPro-based data were judged to be useful in informing recommendations. Patients received either standard of care (SOC) treatments or highly individualized, polybiomarker-driven treatments (beyond SOC). The objective response rate in difficult-to-treat palliative, beyond SOC patients (n = 37) was 38%, with a disease control rate of 54%. Progression-free survival of patients with TuPro-informed therapy decisions was 6.04 months, (95% confidence interval, 3.75–12.06) and 5.35 months (95% confidence interval, 2.89–12.06) in ≥third therapy lines. The proof-of-concept TuPro project demonstrated the feasibility and relevance of omics-based tumor profiling to support data-guided clinical decision-making. ClinicalTrials.gov identifier: NCT06463509.SDSC-G
Water Electrolysis Technologies: the Importance of New Cell Designs and Fundamental Modelling to Guide Industrial-scale Development
No full textLarge-scale, sustainable, low-cost production of hydrogen can reduce the negative effects of climate change by decarbonising energy infrastructure. Low-carbon hydrogen can be synthesised via water electrolysis. Today, however, this only constitutes a minor proportion of global hydrogen production, as fossil fuel-based processes are used predominantly with large amounts of carbon emissions. Low-temperature electrolysis (700 degrees C). In this review, the latest advancements in low-temperature water electrolysers are provided from the classical membrane-based designs to new potential designs such as membrane-less designs. The coverage of electrodes by gas bubbles can cause a drastic loss in their activity and, hence, the hydrogen production efficiency of the device. To alleviate this issue, aerophobic and aerophilic electrodes are being developed. Their advantageous properties are discussed. Furthermore, models of water electrolysers are reviewed to provide critical understanding of the different parameters affecting the electrochemical performance of these devices. Finally, an industrial perspective is given to discuss the challenges in large-scale Gigawatt-level deployment of these devices in coming decades to meet future green hydrogen demand.ISIC-DI
Combining passive and active ultrasonic stress wave monitoring for the characterization of the early-age properties of a UHPFRC beam
No full textThis article focuses on the characterization of the early-age properties of Ultra-High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC), which is becoming popular for designing lightweight and durable structures. Due to the large proportion of cement in the mix, the hardening of UHPFRC is significantly faster than conventional concrete. Therefore, the development of UHPFRC properties, such as the elastic modulus, is difficult to monitor as it happens while elements are within the formwork. For this reason, the hydration process of UHPFRC elements is not fully understood yet. A combined passive (or acoustic emission) and active ultrasonic stress wave monitoring approach has the potential to characterize structures made of cementitious materials over their entire service duration. Using a network of embedded ultrasonic transducers, monitoring can start only a few instants after casting. A UHPFRC beam with a T-shaped cross-section and a length of 4.2 m was constructed and instrumented with 24 transducers as well as 15 thermocouples. Monitoring results lead to the characterization of the development of the early-age UHPFRC properties on the structural-element scale while the specimen is within the formwork. The continuous monitoring approach enabled accurate estimations of the spatial and temporal evolution of the modulus of elasticity. Thanks to this novel combination of monitoring techniques, the early age properties of UHPFRC, which were measured at the material scale, are confirmed at the structural scale for the first time.IIC-GEGIS-G
Effect of Ion Irradiation on the Surface Electrical Conductivity of Cucrzr at High Frequencies
No full textThe ohmic losses in the Electron Cyclotron Heating system of the DEMO nuclear fusion reactor depend on the surface electrical conductivity of the material at the frequency of the mm-wave beams generated in the gyrotrons. To reduce the ohmic losses, many components will be made or coated with materials with high electrical conductivity, such as CuCrZr. In addition, in the Equatorial Port Plug these components will also have to withstand very high irradiation doses. The objective of this work was to study the effect of ion irradiation on the surface electrical conductivity of CuCrZr at frequencies between 140 and 170 GHz. The samples were irradiated with Cu ions at 1, 3 and 10 dpa, which did not entail any change in the surface roughness, and were measured using a Fabry-Perot resonator. In addition, SEM-EDX analysis was performed to chemically characterize the surface of the samples. The results show that the surface electrical conductivity is reduced by more than 40 % at 10 dpa, which would translate in a significant increase of the ohmic losses, rising the cooling needs of the components in the Electron Cyclotron Heating system.SPC-IISPC-TC