École Polytechnique Fédérale de Lausanne
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Fibre distribution and orientation in composite UHPFRC-reinforced concrete structural members - determination and effect on mechanical properties
No full textMC
Optimisation of Strain Hardening Cementitious Composites - deformability versus matrix density
No full textMC
Sampling Moments and Reconstructing Signals of Finite Rate of Innovation: Shannon Meets Strang-Fix
No full textConsider the problem of sampling signals which are not bandlimited, but still have a finite number of degrees of freedom per unit of time, such as, for example, nonuniform splines or piecewise polynomials, and call the number of degrees of freedom per unit of time the rate of innovation. Classical sampling theory does not enable a perfect reconstruction of such signals since they are not bandlimited. Recently, it was shown that, by using an adequate sampling kernel and a sampling rate greater or equal to the rate of innovation, it is possible to reconstruct such signals uniquely . These sampling schemes, however, use kernels with infinite support, and this leads to complex and potentially unstable reconstruction algorithms. In this paper, we show that many signals with a finite rate of innovation can be sampled and perfectly reconstructed using physically realizable kernels of compact support and a local reconstruction algorithm. The class of kernels that we can use is very rich and includes functions satisfying Strang–Fix conditions, exponential splines and functions with rational Fourier transform. This last class of kernels is quite general and includes, for instance, any linear electric circuit. We, thus, show with an example how to estimate a signal of finite rate of innovation at the output of an RC circuit. The case of noisy measurements is also analyzed, and we present a novel algorithm that reduces the effect of noise by oversampling.LCAVCIBLI
Web Text Retrieval with a P2P Query-Driven Index
No full textIn this paper, we present a query-driven indexing/retrieval strategy for efficient full text retrieval from large document collections distributed within a structured P2P network. Our indexing strategy is based on two important properties: (1) the generated distributed index stores posting lists for carefully chosen indexing term combinations, and (2) the posting lists containing too many document references are truncated to a bounded number of their top-ranked elements. These two properties guarantee acceptable storage and bandwidth requirements, essentially because the number of indexing term combinations remains scalable and the transmitted posting lists never exceed a constant size. However, as the number of generated term combinations can still become quite large, we also use term statistics extracted from available query logs to index only such combinations that are frequently present in user queries. Thus, by avoiding the generation of superfluous indexing term combinations, we achieve an additional substantial reduction in bandwidth and storage consumption. As a result, the generated distributed index corresponds to a constantly evolving query-driven indexing structure that efficiently follows current information needs of the users. More precisely, our theoretical analysis and experimental results indicate that, at the price of a marginal loss in retrieval quality for rare queries, the generated index size and network traffic remain manageable even for web-size document collections. Furthermore, our experiments show that at the same time the achieved retrieval quality is fully comparable to the one obtained with a state-of-the-art centralized query engine.LSI
Ultra high performance fiber reinforced concrete for rehabilitation
No full textMCSedited by Swedish Cement and concrete Research Institute (CBI) RILEM PRO 43 : International RILEM TC 193-RLS Workshop on Bonded Concrete Overlay
Haloalkane Dehalogenase LinB is responsible for β- and δ-hexachlorocyclohexane transoformation in sphingobium indicum B90A
No full textIncubation of resting cells of Sphingobium indicum B90A, Sphingobium japonicum UT26, and Sphingobium francense Sp+ showed that they were able to transform ß- and -hexachlorocyclohexane (ß- and -HCH, respectively), the most recalcitrant hexachlorocyclohexane isomers, to pentachlorocyclohexanols, but only resting cells of strain B90A could further transform the pentachlorocyclohexanol intermediates to the corresponding tetrachlorocyclohexanediols. Moreover, experiments with resting cells of Escherichia coli expressing the LinB proteins of strains B90A, UT26, and Sp+ indicated that LinB was responsible for these transformations. Purified LinB proteins from all three strains also effected the formation of the respective pentachlorocyclohexanols. Although the three LinB enzymes differ only marginally with respect to amino acid sequence, they showed interesting differences with respect to substrate specificity. When LinB from strain B90A was incubated with ß- and -HCH, the pentachlorocyclohexanol products were further transformed and eventually disappeared from the incubation mixtures. In contrast, the LinB proteins from strains UT26 and Sp+ could not catalyze transformation of the pentachlorocyclohexanols, and these products accumulated in the incubation mixture. A mutant of strain Sp+ lacking linA and linB did not degrade any of the HCH isomers, including ß-HCH, and complementation of this mutant by linB from strain B90A restored the ability to degrade ß- and -HCH.LB
Clustering protein environments for function prediction: finding PROSITE motifs in 3D
No full textBackground: Structural genomics initiatives are producing increasing numbers of three-dimensional (3D) structures for which there is little functional information. Structure-based annotation of molecular function is therefore becoming critical. We previously presented FEATURE, a method for describing microenvironments around functional sites in proteins. However, FEATURE uses supervised machine learning and so is limited to building models for sites of known importance and location. We hypothesized that there are a large number of sites in proteins that are associated with function that have not yet been recognized. Toward that end, we have developed a method for clustering protein microenvironments in order to evaluate the potential for discovering novel sites that have not been previously identified. Results: We have prototyped a computational method for rapid clustering of millions of microenvironments in order to discover residues whose surrounding environments are similar and which may therefore share a functional or structural role. We clustered nearly 2,000,000 environments from 9,600 protein chains and defined 4,550 clusters. As a preliminary validation, we asked whether known 3D environments associated with PROSITE motifs were "rediscovered". We found examples of clusters highly enriched for residues that share PROSITE sequence motifs. Conclusion: Our results demonstrate that we can cluster protein environments successfully using a simplified representation and K-means clustering algorithm. The rediscovery of known 3D motifs allows us to calibrate the size and intercluster distances that characterize useful clusters. This information will then allow us to find new clusters with similar characteristics that represent novel structural or functional sites.LSI
Rapport sur les méthodes de déménagement de bibliothèques en Suisse : Création d'un produit documentaire : deuxième semestre ID, Haute Ecole de Gestion de Genève.
Full text linkLa bibliothèque centrale de l'EPFL a mandaté les étudiants en information documentaire de la Haute Ecole de Gestion pour réaliser un panorama des méthodes de déménagements de bibliothèques en Suisse. Cette démarche s’inscrit dans le déménagement de ses collections dans le Rolex Learning Center, en février 2010. Toutefois, le rôle de ce travail était de s'intéresser principalement aux aspects pratiques d'un déménagement de bibliothèque, moins sur la planification de ce dernier. Etant donné qu'il existe peu de documentation spécifique sur ce sujet en Suisse, une enquête a été réalisée auprès de 108 bibliothèques, sélectionnées selon l'importance de leur envergure. En cas de déménagement au cours de ces 10 dernières années, un questionnaire à remplir leur a été fourni. Au final, ce sont les témoignages de 19 d'entre-elles qui ont été récoltés. L’objectif était de connaître les pratiques les plus courantes dans le cadre d'un déménagement de bibliothèque et d’en faire une synthèse dans un rapport. Dès lors, il a été possible de démontrer un certains nombre d'usages pratiques communs, tels que le type de support utilisé durant le transport des documents ou encore les rapports entretenus avec les professionnels du déménagement. De plus, des recommandations très utiles ont été émises par les bibliothèques. En outre, une recherche documentaire a été réalisée autour de ce sujet. Il en ressort une importante documentation au niveau international. Les articles jugés les plus révélateurs ont été sélectionnés, puis étudiés et synthétisés. Finalement, les éléments communs de l'enquête et de la recherche documentaire ont été mis en avant, afin de définir les usages plus couramment répandus. Plus qu'une étude théorique, ce travail présente toute une série de méthodes qui ont été appliquées dans des cas concrets. Nous pensons qu'un document de ce type pourra être utile à des bibliothèques suisses ou étrangères lors de leurs propres déménagements.VPA-SISBCréation d'un produit documentaire : deuxième semestre du Bachelor Information Documentation, Haute Ecole de Gestion de Genève
Electrolyte effects and stability of Zn/Li dual-ion batteries with water-in-salt electrolytes
No full textAqueous zinc-ion batteries have emerged as promising candidates for safe and cost-effective energy storage, yet their performance remains constrained by electrode stability and electrolyte composition. In this study, we investigate the electrochemical behavior of various electrode materials utilizing water-in-salt dual-ion electrolytes. Our findings highlight the critical influence of substrate materials on electrochemical stability, with titanium exhibiting superior anodic stability compared to, e.g., aluminum. Furthermore, we demonstrate the feasibility of LiFePO4 as a positive electrode, revealing a redox potential of 1.17 V vs. Zn2+/Zn in chloride-based electrolyte, which shifts positively with increasing lithium concentration. The observed potential variation with electrolyte composition underscores the need for optimized formulations to enhance the battery performance. Additionally, while LiMnPO4 offers a higher theoretical voltage, its cycling stability remains limited, suggesting that material modifications are necessary. Finally, we highlight the overlooked impact of electrolyte impurities on battery performance, emphasizing the importance of high-purity electrolyte components. These insights contribute to the development of more stable and efficient Zn-ion batteries, paving the way for their practical deployment in energy storage applications.LP