Search results for "Atom"
showing 10 items of 31559 documents
Energy-based fluid–structure model of the vocal folds
2020
AbstractLumped elements models of vocal folds are relevant research tools that can enhance the understanding of the pathophysiology of many voice disorders. In this paper, we use the port-Hamiltonian framework to obtain an energy-based model for the fluid–structure interactions between the vocal folds and the airflow in the glottis. The vocal fold behavior is represented by a three-mass model and the airflow is described as a fluid with irrotational flow. The proposed approach allows to go beyond the usual quasi-steady one-dimensional flow assumption in lumped mass models. The simulation results show that the proposed energy-based model successfully reproduces the oscillations of the vocal …
Assembly Assistance System with Decision Trees and Ensemble Learning
2021
This paper presents different prediction methods based on decision tree and ensemble learning to suggest possible next assembly steps. The predictor is designed to be a component of a sensor-based assembly assistance system whose goal is to provide support via adaptive instructions, considering the assembly progress and, in the future, the estimation of user emotions during training. The assembly assistance station supports inexperienced manufacturing workers, but it can be useful in assisting experienced workers, too. The proposed predictors are evaluated on the data collected in experiments involving both trainees and manufacturing workers, as well as on a mixed dataset, and are compared …
A port-Hamiltonian Fluid-Structure Interaction Model for the Vocal folds ⁎ ⁎This work was supported by CONICYT-PFCHA/2017-21170472, and AC3E CONICYT-…
2018
Abstract Fluid-structure interaction models are of special interest for studying the energy transfer between the moving fluid and the mechanical structure in contact. The vocal folds are an example of a fluid-structure system, where the mechanical structure is usually modeled as a mass-spring-damper system. In particular, the estimation of the collision forces of the vocal folds is of high interest in the diagnosis of phonotraumatic voice pathologies. In this context, the port-Hamiltonian modeling framework focuses on the energy flux in the model and the interacting forces. In this paper, we develop a port-Hamiltonian fluid-structure interaction model based on the interconnection methodolog…
Using infrared thermography in order to compare laser and hybrid (laser plus MIG) welding processes
2009
International audience; In order to deepen the understanding of the differences between laser and laser-arc hybrid welding, comparisons were undertaken using thermography. The experiments were carried out for a T assembly of aluminium alloy plates. Modelling, based on the finite element method approach, was realized using IR temperature measurements and seam geometry. For a value of the power supply, depicted as a surface source in the hybrid case, agreement was found between simulated and measured temperatures. The arc power supply efficiency value is similar to the usually used value.
Comparison of electropolishing behaviours of TSC, ALM and cast 316L stainless steel in H 3 PO 4 /H 2 SO 4
2017
Abstract In recent decades, new manufacturing processes have been developed such as Thermal Spray Coating (TSC) and Additive Layer Manufacturing (ALM), which reduce or avoid machining of parts with complex geometries. This study aims to develop an Electropolishing (EP) process for TSC and ALM 316L Stainless Steel (SS). EP is an anodic dissolution process currently used in industry to reduce surface roughness and obtain a bright and smooth finish. The EP mechanism was studied, in a mixture of H3PO4 and H2SO4, for TSC, ALM and “cast” SS in order to determine the best conditions (time, temperature, potential). Special attention was paid to surface characterization by combining several techniqu…
The use of exploratory experimental designs combined with thermal numerical modelling to obtain a predictive tool for hybrid laser/MIG welding and co…
2011
Abstract While hybrid laser welding and coating processes involve a large number of physical phenomena, it is currently impossible to predict, for a given set of influencing factors, the shape of the molten zone and the history of temperature fields inside the parts. This remains true for complex processes, such as the hybrid laser/MIG welding process, which consists in combining a laser beam with a MIG torch. The gains obtained result essentially from the synergy of the associated processes: the stability of the process, the quality of the seam realized, and the productivity are increased. This article shows how, by means of a reduced number of experiments (8), it is possible to predict th…
The numerical simulation of heat transfer during a hybrid laser–MIG welding using equivalent heat source approach
2014
International audience; The present study is dedicated to the numerical simulation of an industrial case of hybrid laser-MIG welding of high thickness duplex steel UR2507Cu with Y-shaped chamfer geometry. It consists in simulation of heat transfer phenomena using heat equivalent source approach and implementing in finite element software COMSOL Multiphysics. A numerical exploratory designs method is used to identify the heat sources parameters in order to obtain a minimal required difference between the numerical results and the experiment which are the shape of the welded zone and the temperature evolution in different locations. The obtained results were found in good correspondence with …
Through-transmission laser welding of polymers – temperature field modeling and infrared investigation
2007
The purpose of the present study is to estimate the weldability of a polymeric material couple according to their thermal and optical properties. A first model based on Mie theory and Monte Carlo method describes the laser beam behavior in semi-transparent media and makes it possible to approximate the laser power distribution at the interface of the two materials. A second model based on finite element method permits the temperature field estimation into both parts to be welded. The results are validated by infrared thermography.
Improved Active Disturbance Rejection Control for Trajectory Tracking Control of Lower Limb Robotic Rehabilitation Exoskeleton.
2020
Neurological disorders such as cerebral paralysis, spinal cord injuries[acronym](SCI), and strokes, result in the impairment of motor control and induce functional difficulties to human beings like walking, standing, etc. Physical injuries due to accidents and muscular weaknesses caused by aging [english]affectsaffect people and can cause them to lose their ability to perform daily routine functions. In order to help people recover or improve their dysfunctional activities and quality of life after accidents or strokes, assistive devices like exoskeletons and orthoses are developed. Control strategies for control of exoskeletons are developed with the desired intention of improving the qual…
Diode laser welding of ABS: Experiments and process modeling
2009
International audience; The laser beam weldability of acrylonitrile/butadiene/styrene (ABS) plates is determined by combining both experimental and theoretical aspects. In modeling the process, an optical model is used to determine how the laser beam is attenuated by the first material and to obtain the laser beam profile at the interface. Using this information as the input data to a thermal model, the evolution of the temperature field within the two components can be estimated. The thermal model is based on the first principles of heat transfer and utilizes the temperature variation laws of material properties. Corroborating the numerical results with the experimental results, some impor…