V. Bruyere , C. Touvrey , P. Namy 
 SIMTEC, Grenoble, France
 CEA DAM, Is-sur-Tille, France
The formation of porosities in spot laser welding depends on complex thermo-hydraulic phenomena. To understand and control these mechanisms, the COMSOL Multiphysics® software is used to model both the interaction and cooling stages of an isolated impact made with a Nd:YAG pulsed laser. The model is based on the Phase Field method in order to apprehend the evolution of the liquid-gas interface ...
Energy Exchange During Electron Emission from Carbon Nanotubes: Considerations on Tip Cooling Effect and Destruction of the Emitter
M. Dionne, S. Coulombe, and J. Meunier
Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada
Murphy and Good general theory for electron emission from metal surfaces was used to predict the field-emission capabilities of ideal arrays of vertically aligned carbon nanotubes (VACNT). The Nottingham effect was taken into account in order to explain experimental observation of a localized cooling of the VACNT tips during field emission and the total destruction of very short emitters at ...
F. Ferrero, M. Kluge, R. Zeps, T. Spoormaker
BAM Federal Institute for Materials Research and Testing, Berlin, Germany
Chairman PlasticsEurope Fluoropolymers TFE Safety Task Force, Du Pont De Nemours, Dordrecht, The Netherlands
The self-ignition of tetrafluoroethylene (TFE) caused by contact with hot surfaces has been analyzed with the help of simulations performed with COMSOL Multiphysics®. The current study focuses on large-scale heated reactors for the industrial production of polytetrafluoroethylene (PTFE) from TFE at high pressures. Simulations of the self-heating and consequent self-ignition of TFE in a 100-dm3 ...
M. A. Shah , F. Iqbal , B. L. Lee ,
 Korea University of Technology and Education, Cheonan, Chungcheong, South Korea
A dual axis MEMS seismometer targeted for building monitoring system has been simulated for a full scale of ±5g acceleration. The design uses the capacitive effect for vibration sensing. This comb drive capacitive MEMS seismometer consists of 8 springs with two proof masses. The device is very low cross axis sensitive (almost negligible cross axis error). The cross axis sensitivity of x-axis is ...
A Time Dependent Dielectric Breakdown (TDDB) Model for Field Accelerated Low-K Breakdown Due To Copper Ions
R. Achanta, J. Plawsky, and W. Gill
Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
We have simulated the copper ion concentration and internal electric field profiles in a dielectric material by solving the transient continuity/Poisson equations using COMSOL Multiphysics. We have shown that failure of dielectrics can be modeled if we assume that failure in Cu/SiO2/Si devices occurs due to a pile-up of copper ions at the cathode and the subsequent increase in electric field ...
N. Kleinknecht, and S. A. Halvorsen
In many metallurgical processes metals are (heated and) stirred by an oscillating external magnetic field. The magnetic field induces electric currents in the metal and the currents interact with the magnetic field to create a force, the Lorentz force. For high frequencies induction only takes place in an electromagnetic boundary layer due to the skin effect and the force is confined within this ...
3D Multiphysics Modeling of Bulk High-Temperature Superconductors for Use as Trapped Field Magnets - new
M. Ainslie, J. Zou, D. Hu, D. Cardwell
Department of Engineering, University of Cambridge, Cambridge, UK
The authors are currently investigating the use of bulk high temperature superconductors as trapped field magnets (TFMs) in order to increase the electrical and magnetic loading of an axial gap, trapped flux-type superconducting electric machine. In electric machines, the use of superconducting materials can lead to increases in efficiency, as well as power density, which results in reductions ...
P. Zilio , W. Raja , A. Alabastri , R. Proietti Zaccaria 
 Istituto Italiano di Tecnologia, Italy
 Istituto Italiano di Tecnologia, Italy
 Rice University, USA
The formation of space charge clouds is a well known problem that affects thermionic emitters in regimes of high current emission. Although some analytical models have been presented, suitable for 1D geometries, the modeling of the problem in complex 3D structures remains a challenge due to the mutual coupling between electron trajectories and field they produce. Here we propose a model able to ...
N. H. Elabbasi, M. J. Hancock, S. B. Brown
Veryst Engineering, LLC., Needham, MA, USA
Wear is a complex phenomenon relevant to many problems involving frictional contact, such as mechanical brakes, seals, metal forming, and orthopedic implants. The rate of wear depends on the properties of the contacting materials and operating conditions. One widely used model of wear is Archard’s law, which relates the rate of material removal due to wear to the contact pressure, sliding ...
Numerical Modeling of Sampling Airborne Radioactive Particles Methods from the Stacks of Nuclear Facilities in Compliance with ISO 2889 - new
Sogin Spa, Rome, Italy
The main objective of this study is to verify the compliance of an ongoing nuclear facilities stack design with the ISO 2889 requirements, during normal and off-normal conditions. In particular, with the numerical simulations, they have been identify well-mixed sample locations along the chimney and the compliance with the International Standard requirements as result of stack flow rate and ...