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Etude d'une antenne octaédrique pour la localisation de sources sonores compétitives
No full textL'environnement industriel ou urbain peut être composé de nombreuses sources nuisibles compétitives. Les stratégies optimales pour réduire le bruit nécessitent en amont une connaissance la plus précise possible des caractéristiques acoustiques et physiques de ces sources. Ce document propose une méthode pour localiser et estimer la puissance acoustique de plusieurs sources de bruit simultanément. Par opposition aux méthodes les plus classiques impliquant des microphones directifs ou des systèmes d'antennerie dit à formation de voie pour lesquels les performances dépendent fortement de la qualité et/ou du nombre de microphones utilisés (généralement important), nous utiliserons des microphones omnidirectionnels en nombre limité. Basé sur les intercorrélations entre microphones, le traitement combinatoire proposé est illustré par des simulations et une expérience en salle anéchoïque dans lesquelles une antenne tridimensionnelle doit localiser et comparer l'énergie de haut-parleurs aléatoirement distribués dans l'espace. Dans cette étude les sources sont considérées monopolaires, large bande, immobiles, stationnaires et décorellées deux à deux.LEM
Antiangiogenic and Anticancer Properties of Bifunctional Ruthenium(II)-p-Cymene Complexes: Influence of Pendant Perfluorous Chains
No full textTwo bifunctional ruthenium(II)-p-cymene complexes with perfluorinated side chains, attached via pyridine ligands, have been evaluated in a series of in vitro and in vivo assays. Their effects on human endothelial (ECRF24 and HUVEC) cells, noncancerous human embryonic kidney (HEK-293) cells, and various human tumor cells were investigated. The complex with the shorter chain, 1, inhibits the proliferation of the tumor cell lines and ECRF24, whereas 2 selectively inhibits ECRF24 and HUVEC proliferation. Neither inhibits the migration of ECRF24 cells whereas both compounds inhibit sprout formation in HUVEC cells. Using three preclinical models, i.e., vasculature formation in the chorioallantoic membrane (CAM) of the chicken embryo, human A2780 ovarian carcinoma tumors xenografted on the CAM, and human LS174T colorectal adenocarcinoma tumors grown in athymic mice, the angiostatic and anticancer activities of these two complexes were studied. Overall, 1 inhibited tumor growth predominantly through an anticancer effect whereas 2 inhibited tumor growth predominately via an antiangiogenic mechanism.LCO
Comparison of the conformation and orientation of alamethicin and melittin in lipid membranes
No full textThe secondary structure of alamethicin in lipid membranes below and above the lipid phase transition temp. Tt is detd. by Raman spectroscopy and CD measurements. In both cases structural data are obtained by fitting the exptl. spectra by a superposition of the spectra of 15 ref. proteins of known 3-dimensional structure. According to the Raman expts., in a lipid bilayer above Tt, alamethicin is helical from residue 1 to 12, whereas below Tt the helix extends from residue 1 to 16. The remaining C-terminal part is nonhelical up to the end residue 20 both above and below Tt. A considerably lower helix content is derived from CD, namely, 38% and 46% above and below Tt, resp., in agreement with several reported values for CD in the literature. It is shown that the commonly used set of CD spectra of water-sol. ref. proteins is unsuitable to describe the CD spectra of alamethicin correctly. Therefore, the secondary structure of alamethicin as derived from CD measurement is, at the present state of anal., unreliable. In contrast to the case of alamethicin, the CD spectra of melittin in lipid membranes are correctly described by the ref. protein spectra. The helix content of melittin is detd. thereby to be 72% in lipid membranes above Tt and 75% below Tt. The data are in accord with a structure where the hydrophobic part of melittin adopts a bent helix as detd. recently by Raman spectroscopy. The orientation order parameters of the helical parts of alamethicin and of melittin in a lipid membrane are deduced from the difference between a corresponding CD spectrum of a polypeptide in planar multibilayer and that in lipid vesicles. The presented method for detg. helix order parameters is new and may be generally applicable to other membrane proteins. The orientation of the helical part of both polypeptides depends on the phys. state of the lipid bilayer at maximal membrane hydration and in the ordered, lipid state furthermore on the degree of membrane hydration. Under conditions where alamethicin and melittin are incorporated in an aggregated form in a fluid lipid membrane at maximal water content, the helical segments are oriented preferentially parallel to the membrane normal. Cooling such lipid membranes to a temp. below Tt changes the orientation of the helical part of alamethicin as well as melittin toward the membrane plane. On the contrary, in dried planar membranes at 2% water content, both polypeptide mols. are oriented with their helical parts parallel to the membrane normal, similar to the case of fluid lipid membranes. [on SciFinder (R)]LCPP
Determination of local refractive index variations in thin films by heterodyne interferometric scanning near-field optical microscopy
No full textWe report on a heterodyne interferometric scanning near-field optical microscope developed for characterizing, at the nanometric scale, refractive index variations in thin films. An optical lateral resolution of 80 nm (lambda/19) and a precision smaller than 10(-4) on the refractive index difference have been achieved. This setup is suitable for a wide set of thin films, ranging from periodic to heterogeneous samples, and turns out to be a very promising tool for determining the optical homogeneity of thin films developed for nanophotonics applications. (C) 2009 American Institute of Physics. [doi:10.1063/1.3226660]LOALPMA
Multi-hydrogenated compounds monitoring in optical fibre manufacturing process by photoacoustic spectroscopy
No full textSub-ppm hydrogen chloride (HCl) and water vapour (H2O) monitoring using photoacoustic spectroscopy in optical fibre manufacturing is reported. The development and performance of a sensor based on an acoustic resonant configuration is described, and on-site measurements are presented. Two DFB lasers emitting in the 1370 nm and 1740 nm range were used for the detection of H2O and HCl, respectively. A detection limit (defined for a SNR=3) of 60 ppb for HCl and 40 ppb for H2O was achieved. Contamination sources of the carrier gas used for the fibre preform manufacturing are identified and discussed. © Springer-Verlag 2006.THEVESCI-STI-LTEcole Polytechnique Federale de Lausanne (EPFL), Nanophotonics and Metrology Laboratory, 1015 Lausanne, Switzerland Compilation and indexing terms, Copyright 2008 Elsevier Inc. 064010143145 0946-2171 Hydrogen chloride (HCl) Carrier gases Acoustic resonant configuratio
Vin partout Un projet de vie pour Lavaux
No full textLe projet traite la surface viticole de la région de Lavaux, de Lutry à Saint Saphorin. Il vise à renforcer le caractère et surligner la qualité de ce paysage construit par l’homme. D’abord, une opération de suppression nettoie la zone viticole de tout immeuble d'habitation construit de manière aléatoire. Ensuite, le projet répartit la totalité des surfaces supprimées dans les bourgs existants. La vigne se libère de l’ombre du bâti, le paysage respire et la vie se réorganise en communauté. Inspirée par la maison vigneronne, le nouveau bâti se place en amont et en aval de la rue. Le rapport à l’espace public est donc différent pour les deux situations. La typologie se développe en hauteur; deux à trois étages d’habitation cherchent la vue vers les Alpes, le lac, le soleil et le ciel. Des espaces d’atelier ouvrent leurs portes au niveau de la route; les bourgs s’animent d’activités. Chaque maison dispose d’une cave, elle en contact avec la terre. La présence d’un noyau central permet l’ajout d’espaces de vie aux dimensions identiques en demi-niveaux. En se libérant de la contrainte dimensionnelle, le projet repose sa qualité spatiale sur le rapport entre le vide intérieur et le contexte extérieur. Le village d’Epesses est pris comme cas d’étude pour analyser plus en détail la qualité spatiale que le projet vise à offrir. Cette opération, accompagnée d’une flexibilité qui répond aux contraintes contextuelles, vise à densifier d’autres bourgs, ainsi que d’en créer des nouveaux.MANSLAB-COLASURLMIS3SAR-DCote: 2021.065Archive: MEM.1/1 A5 verticalGroupe de suivi: Blanc, Alexandre (dir. pédagogique) ; Kaufmann, Vincent (prof.) ; Nay, Nicole (maître EPFL) ; Ritz, Katia (expert)Professeur responsable de l'Enoncé: Kaufmann, Vincent (ENAC IA LASUR)Enoncé théorique de master: Vin et architecture
Témoignage IDEAS - Dr. Loïc Fumeaux
No full textL’initiative Design intégré, architecture et durabilité (IDEAS) propose depuis 10 ans un Mineur interdisciplinaire, l’organisation de séminaires doctoraux et la mise en réseau de doctorantes et doctorants des laboratoires affiliés. Retour sur l’évolution de ce programme en pleine expansion avec le témoignage de Dr. Loïc Fumeaux. Loïc Fumeaux Architecte, enseignant xy-ar.ch / EPFL-LAST, Lausanne EPFL PhD - IDEAS 2016LASTSXLBUILD-OLIPI
On the inefficiency of ride-sourcing services towards urban congestion
No full textThe advent of shared-economy and smartphones made on-demand transportation services possible, which created additional opportunities, but also more complexity to urban mobility. Companies that offer these services are called Transportation Network Companies (TNCs) due to their internet-based nature. Although ride-sourcing is the most notorious service TNCs provide, little is known about to what degree its operations can interfere in traffic conditions, while replacing other transportation modes, or when a large number of idle vehicles is cruising for passengers. We experimentally analyze the efficiency of TNCs using taxi trip data from a Chinese megacity and an agent-based simulation with a trip-based MFD model for determining the speed. We investigate the effect of expanding fleet sizes for TNCs, passengers’ inclination towards sharing rides, and strategies to alleviate urban congestion. We observe that, although a larger fleet size reduces waiting time, it also intensifies congestion, which, in turn, prolongs the total travel time. Such congestion effect is so significant that it is nearly insensitive to passengers’ willingness to share and flexible supply. Finally, parking management strategies can prevent idle vehicles from cruising without assigned passengers, mitigating the negative impacts of ride-sourcing over congestion, and improving the service quality.LUTSThis is an Open Access article under the terms of the Creative Commons Attribution Licens
Heritage, energy, economy: planned preventive conservation and thermal improvements to building envelopes at the Cité du Lignon satellite precinct, Geneva (1963-1971)
No full textBuilt between 1963 and 1971, the Lignon satellite precinct in Geneva (Georges Addor, Dominique Julliard, Louis Payot, Jacques Bolliger architects) is regarded as the most spectacular housing development in post-war Switzerland. The heritage protection agencies in the Geneva Canton have recognised the value of this emblematic scheme – urban, architectural, technical and social - with a conservation plan (plan de site) for the Lignon put in place in May 2009. This affords protection within the urban setting and seems adequately to meet the objective of conservation of the ensemble - the preservation of the architectural unity of the buildings, the planning design and the landscape quality of the exterior spaces - without having to resort to a listing in the Monuments Inventory, something which would impose major constraints on a precinct which blends social housing units with owner-occupied dwellings. For some it is an energy-guzzling black hole, for others an historical monument; either way the Lignon is under scrutiny. Given the rash of unauthorised modifications that have been made, and faced with new imperatives to reduce energy consumption whilst at the same time endorsing the conservation plan, a pilot project in the area of "preventive conservation" of the Lignon facades has been devised. For this, two Canton of Geneva agencies - the Heritage and Sites Bureau and the Energy Service, have teamed up with the Lignon Central Committee, the association representing building owners. The École Polytechnique Fédérale de Lausanne has been tasked with carrying out the research, which will look at economic, architectural and energy efficiency aspects of the site.TSA