Pseudoscience | EPFL Graph Search

thumb|redresse|Dans le domaine de la pseudoscience :Instrument du début du conçu par Franciszek Rychnowski afin de mesurer les radiations d'une « énergie cosmique ». La pseudoscience ou pseudo-science (du grec ancien ψευδής, et du latin scientia, ) est une discipline qui est présentée sous des apparences scientifiques, mais qui n'en a pas la démarche, ni la reconnaissance. Elle se situe en opposition à la science. Le terme de « pseudoscience » est souvent utilisé pour dénoncer la tromperie autour de certaines connaissances, c'est-à-dire ceux qui utilisent, sciemment ou non, des termes et des démarches qui semblent scientifiques ou logiques dans le but de s'attribuer le crédit que la science possède. Ils utilisent parfois un langage et des axiomes scientifiques, mais ne respectent pas les critères de la méthode scientifique, tels les principes fondamentaux de réfutabilité, de non-contradiction et de reproductibilité. La pseudoscience se rapproche de la para-science () dont le t

Biomechanical Ambulatory Assessment of 3D Knee Angle Using Novel Inertial Sensor-Based Technique

Kamiar Aminian, Lai Kuan Tham

Three-dimensional (3D) knee angle measurement is one of the key measures in human gait analysis. Inertial sensor capable of measuring joint motion under unconstrained conditions is a practical tool for clinical evaluation and rehabilitation. An inertial measurement unit (IMU) consisting of accelerometer and gyroscope allows orientation measurement in 3D with an additional sensor (i.e., magnetometer). However, ferromagnetic interference negatively affects the performance of magnetometer and thus reduces measurement accuracy. In this study, a technique based on nonlinear autoregressive neural network with exogenous inputs (NARX) is presented to measure 3D segmental orientation during gait without the use of magnetometer. With IMUs attached to the thigh and shank, 3D knee angles in long-distance treadmill walking were computed and validated against an optical motion analysis system as the gold standard. Pseudo-integrator (PI) was also compared to the reference system for benchmarking. The learning capability of NARX was further assessed with the comparison of complementary filter (CF) to the reference system. The proposed NARX model was shown to outperform PI with biases between -3.5 degrees and -0.2 degrees, and root mean square errors between 4.5 degrees and 2.5 degrees. Results demonstrated the capability of NARX in providing accurate estimates of 3D knee joint angle while avoiding interference as encountered in systems incorporating magnetometer, suggesting that NARX is feasible to computing long-term ambulatory measurements of body segment orientation and 3D joint angles.

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2021

Numerical simulation of a sailing boat

Matteo Lombardi

In this work, various aspects concerning the numerical simulation of a sailing boat are investigated. The attention is focused on simulation of the free-surface, the fluid-structure interaction (FSI) between wind and sails, and the dynamics of the whole boat. Some preliminary work on shape optimization is also presented. Free-surface simulations are carried out both on classical academic benchmark problems and for the prediction of the wave pattern around racing yachts. The comparison with experimental results and numerical data obtained with other CFD codes has proven the validity of the proposed set-up. In this framework, the Level Set method has been implemented and validated as a possible solution to the problem of interface diffusion arising in planing conditions with the standard Volume of Fluid approach. The FSI problem governing the interaction between wind and sails is solved via a strongly coupled segregated approach based on the standard Dirichlet-Neumann coupling. The structural solution is based on a MITC4 finite-element shell code. The fluid and structural meshes are non-conforming and the exchange of information at the interface is obtained via radial basis functions (RBF) interpolation. The fluid mesh motion is accomplished either through the mapping generated using the radial basis functions or via a method based on the inverse distance weighting (IDW) interpolations. The attention is paid to the methodological aspects of this complex problem and to the analysis of the numerical results. The fluid-structure interaction simulations of one and two sail configurations, with different trimmings, are presented; both steady and transient simulations are performed. The results obtained are very encouraging and show the potential of the proposed model. The dynamic motion of the Series 60 hull and the Alinghi’s AC 32 monohull complete of bulb, keel and sails have also been investigated. For the latter in particular, the free sink, trim and roll case has proven to be particularly interesting, with the boat rolling considerably on the side due to the aerodynamic loads exerted by the wind on the sails. Here, the whole boat has been considered as a rigid body but the integration of the FSI module for the sails into the full boat dynamic system is already under development. Finally, a preliminary analysis of shape optimization techniques applied to sailing boat elements have been investigated: in particular the attention has been focused on the drag minimization of (pseudo) bulb geometries under the constraint of fixed volume/fixed righting moment. The shape parametrization have been achieved either using directly the surface element nodes or via the Free Form Deformation (FFD) technique while the optimization algorithm has been based either on the solution of the adjoint Navier-Stokes equations or via pseudo finite-difference algorithms. The algorithm and developments mentioned have been implemented in a common open-source framework, the library OpenFOAM®.

EPFL2012

Kinetic model basis of ozone/light-based advanced oxidation processes: a pseudoempirical approach

Eva Maria Rodriguez Franco

Most works on AOP technologies aimed at removing contaminants from water have focused on the influence of experimental variables on the overall removal rate of specific target contaminants. Few studies have been devoted to proposing detailed kinetic models of these processes. Photocatalytic ozonation is a highly complex process, where commonly the number of unknown parameters, reactions, intermediates generated, etc. impedes the proposal of a detailed rigorous reaction mechanism. In this work, a pseudoempirical model based on experimental data and the typical reactions occurring during photocatalytic oxidation and ozonation of a model compound (primidone) has been proposed and discussed. Total organic carbon was selected as a surrogate parameter to simulate the process. The experimental system consisted of an ozonation tank where water was pumped to and recirculated through a tubular photoreactor equipped with 6 high power UVA LEDs. The photoreactor was characterized by non-ideal flow analysis and chemical actinometry. The model was implemented in Simulink (R) and solved to minimize differences between the model and experimental data. Simple processes such as ozonation, photolytic ozonation and photocatalytic oxidation were acceptably modelled and used to simulate the photocatalytic ozonation process.

2020

Numerical simulation of a sailing boat

Matteo Lombardi

EPFL2012