Physics-based Modeling Approach Research Articles

Multiobjective Design Optimization of Coupled PM Synchronous Motor-Drive Using Physics-Based Modeling Approach

This paper deals with an optimal design of surface-mounted permanent magnet motor geometry for achieving minimum torque ripple, minimum RMS value of phase current, and minimum total harmonic distortion of phase currents, simultaneously. A classic multiobjective function is formed as a combination of these single objectives. A dynamic physics-based phase variable modeling approach is used to indirectly couple the motor geometry in the finite element domain to the drive circuit in a simulink environment. The physical behavior of motor is calculated by nonlinear transient FE analysis with motion. A fast hybrid genetic-particle swarm optimization process is developed for shape optimization of the motor. The results before and after optimization show the expected performance improvements while reducing magnet material and copper size.

On deriving incident auroral particle fluxes in the daytime using combined ground-based optical and radar measurements

[1] Particle energies and fluxes have predominantly been measured from instruments onboard satellites. In this study, we use daytime ground-based oxygen redline emission measurements, along with the ionospheric electron density, and electron temperature profiles measured from the incoherent scatter radar, and a physics-based modeling approach to derive the energy and flux of particles incident over Boston during the storm of 30 October 2003. We find that the characteristic energy and the associated flux vary between 0.07–5.7 keV and 0.5–130 mW m−2, respectively, during the intense magnetic disturbance that brought aurora to midlatitudes. Such an approach not only offers another method to estimate the incident particle energies and fluxes but also enhances our understanding on the channels of energy deposition in the upper atmospheric region, especially during magnetic disturbances, about which database is poor.

Physics-based modeling for fretting behavior of nominally flat rough surfaces

A physics-based modeling approach for fretting behavior of nominally flat rough contact is proposed. This approach employs physics-based models for partial slip of spherical contacts to formulate the contact forces at asperity tips. The individual asperity forces are added by a statistical method to obtain the fretting response of a flat rough contact. This approach suggests the plasticity index as an important parameter for studying the surface roughness effects on fretting. Fretting responses obtained by one of the models favorably compare with experimental results obtained from bolted steel lap joints. Tangential stiffness and energy loss per cycle obtained from the experiments and the model predictions deviate at higher preloads. This discrepancy is due to limitations of the modeling approach in accounting for plastic response to tangential loading.

Physics-based modeling for partial slip behavior of spherical contacts

A physics-based modeling approach for partial slip behavior of a spherical contact is proposed. In this approach, elastic and elastic–plastic normal preload and preload-dependent friction coefficient models are integrated into the Cattaneo–Mindlin partial slip solution. Partial slip responses to cyclic tangential loading (fretting loops) obtained by this approach are favorably compared with experiments and finite element results from the literature. In addition to load-deformation curves, tangential stiffness of the contact and energy dissipation per fretting cycle predictions of the models are also provided. Finally, the critical assumptions of elastically similar bodies, smooth contact surface and negligible adhesion, and limitations of this physics-based modeling approach are discussed.

Physics-based froth modelling: new developments and applications

This article describes the use of a flotation froth model based on foam physics. The model is briefly described by introducing the structure of froths and the equations that govern foam motion and liquid drainage. The methodology of combining the physical models for each phase into a complete description is reviewed. A boundary condition unique to froths, surface bursting, is detailed and its behaviour shown. The article does not dwell on the model itself, focussing instead on illustrating the utility of this physics-based froth modelling approach to optimising industrial flotation. This is illustrated with examples of improved understanding and operation. First, the liquid flow equations are solved explicitly, giving a clear interpretation of process variables and their importance on flotation behaviour. Second, an industrial example of the use of the model for improved air addition management is shown. This approach to froth modelling captures very closely the behaviour of flotation behaviour, and can be used for process optimisation. The most significant challenges that remain are discussed; most notably, understanding and incorporating the rates of bubble coalescence in the froth and bursting on the surface.

Comparison Between Experimental and Simulation Results for Ion Beam and Neutron Irradiations in Silicon Bipolar Junction Transistors

We report on an early-time inverse gain comparison between ion and neutron irradiated silicon bipolar junction transistors. We find ion irradiations to be an excellent simulator for fast-burst neutrons for early-time behavior and damage creation rates. In addition we report on an experimental to simulation comparison of transient gain annealing response. The simulations are from a physics based modeling approach that is being developed at Sandia National Laboratories as part of the Qualification Alternatives to the Sandia Pulsed Reactor (QASPR) Program. We find excellent agreement between simulation and experiment across a wide range of irradiation conditions.

A novel haptics-based interface and sculpting system for physics-based geometric design

Conventional geometric design techniques based on B-splines and NURBS often require tedious control-point manipulation and/or painstaking constraint specification via unnatural mouse-based computer interfaces. In this paper, we propose a novel and natural haptic interface and present a physics-based geometric modeling approach that facilitates interactive sculpting of spline-based virtual material. Using the PHANToM haptic device, modelers can feel the physically realistic presence of virtual spline objects and interactively deform virtual materials with force feedback throughout the design process. We develop various haptic sculpting tools to expedite the deformation of B-spline surfaces with haptic feedback and constraints. The most significant contribution of this paper is that point, normal, and curvature constraints can be specified interactively and modified naturally using forces. To achieve the real-time sculpting performance, we devise a novel dual representation for B-spline surfaces in both physical and mathematical space: the physics-based mass-spring model is mathematically constrained by the B-spline surface throughout the sculpting session. We envision that the integration of haptics with traditional computer-aided design makes it possible to realize all the potential offered by both haptic sculpting and physics-based modeling in CAD/CAM, virtual prototyping, human–computer interface, and medical training and simulation.