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Relationship between nonlinear creep and cracking of concrete under uniaxial compression
No full textIBETO
Quenching spin diffusion in transferred Overhauser studies and detection of octupolar order in gaseous xenon-131
No full textA review with 38 refs. on the detn. of mol. conformation and spin diffusion in small mols. Exchange transferred NOE nuclear Overhauser effect is summarized. [on SciFinder (R)]LRM
Ultrafast Relaxation Dynamics of Osmium-Polypyridine Complexes in Solution
No full textWe present steady-state absorption and emission spectroscopy and femtosecond broadband photoluminescence up-conversion spectroscopy studies of the electronic relaxation of Os(dmbp)(3) (Os1) and Os(bpy)(2)(dpp) (Os2) in ethanol, where dmbp is 4,4'-dimethyl-2,2'-biypridine, bpy is 2,2'-biypridine, and dpp is 2,3-dipyridyl pyrazine. In both cases, the steady-state phosphorescence is due to the lowest (MLCT)-M-3 state, whose quantum yield we estimate to be <= 5.0 x 10(-3). For Os1, the steady-state phosphorescence lifetime is 25 ns. In both complexes, the photoluminescence excitation spectra map the absorption spectrum, pointing to an excitation wavelength-independent quantum yield. The ultrafast studies revealed a short-lived (<= 100 fs) fluorescence, which stems from the lowest singlet metal-to-ligand-charge-transfer ((MLCT)-M-1) state and decays by intersystem crossing to the manifold of (MLCT)-M-3 states. In addition, Os1 exhibits a 50 ps lived emission from an intermediate triplet state at an energy similar to 2000 cm(-1) above that of the long-lived (25 ns) phosphorescence. In Os2, the (MLCT)-M-1-(MLCT)-M-3 intersystem crossing is faster than that in Os1, and no emission from triplet states is observed other than the lowest one. These observations are attributed to a higher density of states or a smaller energy spacing between them compared with Os1. They highlight the importance of the energetics on the rate of intersystem crossing.LS
A theory for the streamwise turbulent fluctuations in high Reynolds number pipe flow
No full textA new theory for the streamwise turbulent fluctuations in fully developed pipe flow is proposed. The theory extends the similarities between the mean flow and the streamwise turbulence fluctuations, as observed in experimental high Reynolds number data, to also include the theoretical derivation. Connecting the derivation of the fluctuations to that of the mean velocity at finite Reynolds number as introduced by Wosnik, Castillo & George (J. Fluid Mech., vol. 421, 2000, pp. 115-145) can explain the logarithmic behaviour as well as the coefficient of the logarithm. The slope of the logarithm, for the fluctuations, depends on the increase of the fluctuations with Reynolds number, which is shown to agree very well with the experimental data. A mesolayer, similar to that introduced by Wosnik et al., exists for the fluctuations for 300 > y(+) > 800, which coincides with the mesolayer for the mean velocities. In the mesolayer, the flow is still affected by viscosity, which shows up as a decrease in the fluctuations.EFLUMNational Licence
A modular multiple frequency inductive link to wirelessly power multiple miniaturized implants
No full textA modular multiple frequency coils inductive link system to wirelessly provide power for at least a medical implant at an output of a receiving coil, whereby the receiving coil is configured to be implanted in an organism. The modular multiple frequency coils inductive link comprises a transmitter coil configured to input power from a power supply and induce a first magnetic field at a resonating carrier frequency. The modular multiple frequency coils inductive link further comprises a shifting resonator comprising at least an active integrated circuit, a first coil configured to receive the first induced magnetic field from the transmitter coil by induction at the resonating carrier frequency and convert it to an electrical current, and a second coil configured to transmit the electrical current to the receiving coil by inducing a second magnetic field at a determined frequency different from the resonating carrier frequency, the active integrated circuit connected with both the first coil and the second coil and being configured to receive the power induced at the resonating carrier frequency though the first coil and to use it to drive remaining power reduced due to a power dissipation of the active integrated circuit at the determined frequency though the second coil. The receiving coil is configured to receive the power induced by the second coil at the determined frequency and make it available at the output of the receiving coil.AVP-R-TTOAlternative title(s) : (fr) Liaison à induction multifréquence modulaire pour alimenter sans fil de multiples implants miniaturisé
Energy and orientation independence of the channel branching in Ne* + ND3 chemi-ionisation
No full textCollisions of excited neon atoms with ammonia molecules can lead to two reaction processes, dissociative ionisation and Penning ionisation. Both processes result in the ionisation of the ammonia molecule and redistribution of the electronic energy into the internal ammonia ion rovibrational modes. We performed energy dependent, crossed-beam stereodynamics studies of the branching ratio between the two ionisation processes. It was found that the branching ratio is totally and completely insensitive to both the neon orientation and the collision energy across the range we sampled, 370–520 cm1. The total lack of stereodynamics can be explained by the structure of the ammonia and that its orientation, which we do not attempt to control, is the critical factor in the reaction outcome.SCI-SB-A
Geo-Data for Mapping Scenic Beauty: Exploring the Potential of Remote Sensing and Social Media
No full textScenic beauty is an important contributing factor to peoples' well-being. Modelling scenic beauty has been made possible at large scales with the availability of open-source remote sensing products. At the same time, the metadata available through social media, including tags and descriptions, offer a novel modelling alternative with a personalised view from the ground. This is especially relevant to policy applications. Using a crowdsourced landscape aesthetics dataset called ScenicOrNot as ground truth, we develop and test models to predict scenic beauty based on remotely sensed indicators and image metadata from social media (Flickr). Initial results show that both model types generate strong predictions of scenic beauty and model accuracy is maximised when the two are combined. Our research shows that both a top-view measurement using remote sensing and a social media-based measurement from the ground can be used to model landscape aesthetics in support of sustainable policy goalsECE
Structural Design from Reclaimed Material Sauvabelin – The Never-Ending Story
No full textThis thesis is developed as part of the final year project that must be completed to obtain the MCs degree in Civil Engineering at EPFL. It follows up the pre-study project carried out during the last semester of the course. The environmental crisis that our society is currently facing is no longer a surprise to anyone. While a shift of mindsets can slowly be observed in many fields of activity, the construction sector remains one of the most energy-intensive sectors that consumes enormous quantities of materials resulting in an important amount of waste and relative emissions. The shift of paradigm from an oil-based economy toward a material economy will progressively enforce the daily use of reclaimed materials within our infrastructures. Designing from reclaimed materials, however, reverse the usual design process and not only requires new tools but also requires new regulations. The project is developed around the concept of reuse and aims to assess the potential to reuse in the timber construction domain. The first part of this report is dedicated to the assessment of the potential and limitations of such strategy while the second part is centred around the development of a fictitious case study. The case study aims to propose a feasible design for the new lookout tower of Sauvabelin considering that its load bearing structure could be built from reclaimed elements of the existing tower. The project is intended to be used as a banner to reuse by demonstrating the early-stage feasibility and benefit of implementing a reuse strategy. It is further hoped that the project can be used as a discussion tool to initiate reflection on the future of the Sauvabelin Tower. The project therefore brings together structural, architectural, and environmental considerations that need to be balanced out to obtain a sustainable design. The project involves the use of the decision support tool Phoenix 3D, developed at the Structural Xploration Lab in Fribourg, which provides the assignment of an available stock and new elements to member positions of truss structures. A parametric design of the load bearing system is implemented in the Rhinoceros 3D – Grasshopper environment to be able to perform some optimization regarding its environmental impact and other quantities assessed through Phoenix 3D. The project proves the feasibility of the pursued strategy and show that a load bearing structure with similar height can be constructed only from the reclaimed elements of the current Sauvabelin Tower. It was, furthermore, assessed that the environmental impact of the load bearing structure can theoretically be reduced of about 45% in implementing a reuse strategy. The retained design and final look of the tower are finally presented in the last part of this report.SGCIBOI
A feedback approach to the steady-state performance of fractionally spaced blind adaptive equalizers
No full textThis paper proposes a new approach to the analysis of the steady-state performance of constant modulus algorithms (CMA), which are among the most popular adaptive schemes for blind equalization. A major feature of the proposed feedback approach is that it bypasses the need for working directly with the weight error covariance matrix. In so doing, approximate expressions for the steady-state mean-square error of several CM algorithms are derived, including CMA2-2, CMA1-2, normalized CMA, and a new normalized CMA variant with less bias. A comparison among the various algorithms is also performed, along with several simulation results. The conclusions confirm the superior performance of CMA2-2.AS
Brain micro-vasculature imaging: An unsupervised deep learning algorithm for segmenting mouse brain volume probed by high-resolution phase-contrast X-ray tomography
No full textHigh-throughput synchrotron-based tomographic microscopy at third generation light sources allows to probe cm-sized samples at micrometer-resolution. In this work, we present an approach to image a full mouse brain. With Indian-ink as a contrast agent, it was possible to obtain 3D distribution of microvessels while a computational framework automatically extracted the morphological and geometrical embedding of the putative vascular systems. Results demonstrate the potentiality of the proposed methodology to visualize and quantify in 3D details of the brain tissue with an image quality and resolution previously unachievable.CIB