École Polytechnique Fédérale de Lausanne
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Pavillon du Camping Sierre-Ouest, Sierre, 1959-1960. 2. WengerTag – 05.10.2024
No full textPublié à l’occasion du deuxième « WengerTag » du 5 octobre 2024 organisé par la Fondation Heidi + Peter Wenger et les Archives de la construction moderne – EPFL, cette publication présente le pavillon d’accueil du camping Sierre-Ouest (1959), commandé aux architectes par l’entrepreneur A. Bärfuss. Elle réunit des reproductions de plans originaux et des photographies d’archives.
Images : Archives de la construction moderne – EPFL, Fonds WENGER 0183
Editée par Lisa Virgillito.Published on the occasion of the second “WengerTag” on October 5, 2024, organized by the Heidi + Peter Wenger Foundation and the Archives de la construction moderne – EPFL, this publication presents the reception pavilion of the Sierre-Ouest campsite (1959), commissioned from the architects by entrepreneur A. Bärfuss. It brings together reproductions of original plans and archival photographs.
Images: Archives de la construction moderne – EPFL, Fonds WENGER 0183
Edited by Lisa Virgillito.GR-ACM(Lausanne ; Brigue : Archives de la construction moderne – EPFL ; Heidi + Peter Wenger Stiftung, 2024).(Lausanne ; Brigue : Archives de la construction moderne – EPFL ; Heidi + Peter Wenger Stiftung, 2024)
Data-Driven Markovian Project Portfolio Tracking
No full textWe propose a finite-state Markov chain framework for tracking and forecasting the status of project portfolios. This approach enables forecasts of portfolio composition over time and the computation of long-run distributions of project outcomes. It supports strategic planning by identifying project success rates, average durations, and the balance of resource allocation between active and idle projects. From a managerial perspective, the model facilitates early detection of portfolio-level risks and provides a data-driven basis for adjusting resource deployment or re-prioritizing projects. We show that forecasts remain robust under moderate errors in model identification, enhancing the method’s practical applicability in environments with noisy or incomplete data. This work lays the foundation for a scalable, organization-wide mechanism to improve visibility into project dynamics and support evidence-based decision-making.OE
UHPFRC intervention reduces environmental and economic costs in bridge management
No full textConventional infrastructure management typically involves replacing bridges at the end of their intended service duration or when significant structural deficiencies arise, resulting in high costs and environmental impacts. Novel structural-strengthening methods using ultra-high-performance fiber-reinforced cementitious composite (UHPFRC) have allowed the preservation of hundreds of bridges. Their service duration has been extended, and the performance has been improved to achieve the same performance as a new structure. Examining the Swiss federal network (3,903 bridges), it is found that interventions with the UHPFRC method are feasible on more than 99.7% of structures, demonstrating that the structural intervention could be systematically applied to road bridge networks. Systematically applying the UHPFRC strategy would lead to savings of up to 7.7 MtCO2,eq, and 18.5 billion CHF over the next 80 years compared to current mainstream engineering practice. This study underscores the large potential of UHPFRC-method interventions for sustainable and cost-effective infrastructure management.SXLGIS-G
Impact of Industrial Waste Heat Recovery on Heat and Electricity Marginal Costs in an Energy Community
No full textSector coupling is seen as one of the keys to improve energy efficiency within urban centers. In this perspective, residential energy system coupled with industrial waste heat recovery via district heating network is a promising solution. However, it also implies the coordination between systems design since a decision taken in one subsystem directly affects the decision-making of other subsystems. The aim of this paper is to demonstrate the sector coupling within an energy community containing an industrial site. The problem is formulated as a renewable energy hub with investment and operation decisions. Each building is modeled individually and the Dantzig-Wolfe decomposition is applied to optimize the district-scale problem. The industrial site is modeled as a heat source with fixed capacity and temperature. The marginal cost analysis demonstrates the spillover effect of waste heat availability on the profitability of PV panels, therefore engendering a self-consumption competition.SCI-STI-F
A colloidal approach for the synthesis of catalytically active solid–liquid–solid nanoparticles
No full textNanoreactors can synthesize highly tunable nanomaterials beyond the reach of conventional methods. Liquid metals (LMs) have emerged as an interesting reaction medium for materials synthesis. However, the limited understanding of their chemistry at the nanoscale has so far hindered the broader exploration of LMs in the synthesis of nanomaterials. Here we advance the chemistry of LM nanoparticles (NPs) and demonstrate the use of these NPs as nanoreactors to access well-defined, compositionally tunable multimetallic NPs. We propose a colloidal approach to synthesize solid–liquid–solid core–shell–shell NPs in which a solid metal core (silver, gold, copper or palladium) is embedded into a liquid gallium NP surrounded by its native oxide skin. Using state-of-the-art characterization, we observe the dissolution and recrystallization of the solid metal core within the liquid gallium NP during the synthesis. We leverage this understanding to access unprecedented multimetallic NPs, exemplified by Ag–Au nanodimers within a liquid gallium shell. Finally, we show that solid–liquid–solid NPs are promising electrocatalysts with improved structural stability over the solid core only. (Figure presented.)LNC
SNAP-tag2 for faster and brighter protein labeling
No full textSNAP-tag is a powerful tool for labeling proteins with synthetic fluorophores in bioimaging. However, its utility in live-cell applications can be constrained by its relatively slow labeling kinetics and the limited cell permeability of its substrates. Here, we introduce improved labeling substrates and an engineered SNAP-tag for faster labeling in vitro and in live cells. SNAP-tag2 presents a second-order rate constant with rhodamine substrates that approaches 107 s−1 M−1, a 100-fold improvement over the corresponding SNAP-tag–substrate pairs. When labeled with highly fluorogenic dyes, SNAP-tag2 also shows a fivefold increase in fluorescence brightness relative to currently used SNAP-tag. The increased labeling kinetics and brightness of SNAP-tag2 translate into greatly improved performance in various live-cell (super-resolution) imaging applications. (Figure presented.)LI
Minimizing Quasi-self-concordant Functions by Gradient Regularization of Newton Method
No full textWe study the composite convex optimization problems with a quasi-self-concordant smooth component. This problem class naturally interpolates between classic self-concordant functions and functions with Lipschitz continuous Hessian. Previously, the best complexity bounds for this problem class were associated with trust-region schemes and implementations of a ball optimization oracle. In this paper, we show that for minimizing quasi-self-concordant functions we can use instead the basic Newton method with gradient regularization. For unconstrained minimization, it only involves a simple matrix inversion operation (solving a linear system) at each step. We prove a fast global linear rate for this algorithm, matching the complexity bound of the trust-region scheme, while our method remains especially simple to implement. Then, we introduce the dual Newton method, and based on it, develop the corresponding accelerated Newton scheme for this problem class. This scheme further improves the complexity factor of the basic method, matching-up to logarithmic factors-the state-of-the-art rates of accelerated methods achieved within the framework of the ball optimization oracle. As a direct consequence of our results, we establish fast global linear rates of simple variants of the Newton method applied to several practical problems, including logistic regression, soft maximum, and matrix scaling, without requiring additional assumptions on strong or uniform convexity for the target objective.ML
Lausanne 1831
No full textDans ce volume, nous proposons une nouvelle perspective de l'histoire des villes et des territoires, à partir d'une analyse informatique à grande échelle des sources historiques. L'approche est basée sur l'extraction computationnelle des informations contenues dans une source historique faisant référence à une année spécifique. Les informations sont extraites, interprétées et visualisées à l'aide des dernières approches algorithmiques. Il ne s'agit pas simplement d'une reproduction des documents originaux, enrichie de commentaires critiques et de notes archivistiques, mais d'une nouvelle formule : la version numérique du document original accompagnée d'essais interprétatifs basés sur l'analyse quantitative et qualitative des résultats obtenus. Les défis sont multiples : fournir simultanément une version numérique et analogique des données transmises, créer de nouvelles méthodologies d'extraction adaptées à des questions historiques spécifiques, et représenter les connaissances possibles – mais pas les seules - que les méthodes computationnelles, enrichies de connaissances et d'interprétations historiques, peuvent produire. Les disciplines impliquées sont variées : de la géographie de l'information à la vision par ordinateur, en passant par l'apprentissage automatique, les statistiques, l'histoire, l'histoire urbaine et de l'image, et bien d'autres encore. Les auteurs réunissent des compétences diverses et les déploient avec de nouvelles méthodes et interprétations.DHI-GEDHLA
Jean-André Deluc's Traveling Barometer
No full textIn the second half of the 18th century, Jean-André Deluc painstakingly designed a portable barometer which could accurately determine the heights of mountains by measuring the weight of atmospheric air. While the principle behind the instrument was straightforward and had been used for more than a century, the novelty and success of Deluc's barometer depended on its ability of balancing various elements. Because of the shocks from travel and climbing, it was a great challenge to prevent air from mixing into the mercury reservoir. The reactive properties of mercury limited the elements with which it could come into contact. Occasional tumbles and falls posed a great risk to the glass container. Deluc's solution relied on coordinating how the elements and materials of the barometer reacted and moved in relation to each other. Most importantly, Deluc's barometer was not just designed for travel, but rather it was designed in response to Deluc's own travels and experiences in the Alps of the Haute-Savoie.LHS