Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"contact models"”.
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Discrete Element Method (DEM) Contact Models Applied to Pavement Simulation
… introduction and comparison between various contact models. This paper will give a detail exploration on the contact models that can be potentially used in DEM pavement simulation; in the analysis, it includes both a theoretical part, simulation results and computational time cost, which can …
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Validation of Radiocarpal Joint Contact Models Based On Images from a Clinical MRI Scanner
… One such means is MRI-based modeling for joint contact analysis of in vivo functional loading. The purpose of this study was to validate models generated from a clinical MR scanner for future in vivo joint contact analyses. Models were tested using 3 cadaver forearm specimens and compared with …
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Planning, Sensing, and Control for Contact-rich Robotic Manipulation with Quasi-static Contact Models
… our palms, arms, body and legs to make and break contact with the manipuland whenever and wherever necessary. In contrast, the vast majority of robotic manipulators are artificially divided into a small end effector that makes all the interactions, and a hefty arm that needs to always remain …
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Inference and learning for rigid-body models of manipulation
… frictional interactions. We begin by deriving a contact-implicit system identification formulation for articulated rigid-bodies. Assuming we have a physical model of the system, the objective is to derive system parameters and contact forces for articulated rigid-bodies without enumerating and …
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Effects of nanoscale film thickness on apparent stiffness of and cell-mediated strains in polymers
… multiaxial loading conditions. The Hertzian contact models developed for linear elastic materials of semi-infinite thickness fail to accurately predict the elastic modulus E for these compliant materials. This makes it necessary to understand the evolution of stress and strain fields of these …
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Simulating Complex Multi-Degree-Of-Freedom Systems and Muscle-Like Actuators
… and developing robotic systems based on these models are complicated and computationally intensive tasks. In order to reduce the amount of time needed to develop such models, computational tools are required which intelligently determine parameters of the physical system. Towards this goal …
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Modelling and optimization of green pellets classification on roller screens using the discrete element method
… validation by comparison with industrial data of contact models that reproduce with verisimilitude the movement of these solids. According to the results, the JKR model was the one that best fitted the interactions of low resistance moist pellets among themselves and rolls surface. Exploratory …
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Advances in grasping and vehicle contact identification : analysis, design and testing of robust methods for underwater robot manipulation
… Institution. To enable the exploitation of contact with the environment to help stabilize the vehicle, Part II develops a technique which identifies the contact state of a planar vehicle interacting with a fixed environment. Knowing the vehicle geometry and velocity we identify kinematically …
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Application of Koopman Operator Theory to Legged Locomotion
… from complicated robot systems and harsh contact dynamics have long impeded the effectiveness of optimal control strategies for legged robots. In this work, we present a linearized simple walking model using Koopman Operator Theory, and its usage in Linear Model Predictive Control (L-MPC). …
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The vibration of rolling discs
… due to rotation of the disc and the effect of contact on the disc which in the first instance is modelled as a simple pinning constraint. Further in depth analysis is described for a more realistic model of the rolling contact including the effect of the contact stiffness and the creepage …
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Food Safe Alternatives to Methyl Bromide in Country Ham Production
… volatile efficacy, but was effective in direct contact assays. However, as garlic juice was aged and diluted, efficacy was reduced even after treatments with antioxidants, metal chelators, and pH neutralization. In total, garlic juice acted as a short term repellent and showed efficacy in …
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An Investigation into the Impact of Random Spacing Errors on Static Transmission Error and Root Stresses of Spur Gear Pairs
… are simulated by using two existing gear contact models to demonstrate their accuracy and describe the empirical trends physically. A methodology is proposed at the end to relate increases in root stresses to the spacing error magnitudes directly. Closed-form expressions resulting from …
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A nonlinear interface formulation for frictional contact
<p>Finite element simulations of contact problems often involve modeling the interaction of multiple bodies across a non-confirming interface. Non-Confirming Meshes (NCM) are typically associated with large sliding or adaptive refinement on one side of the interface to capture localized nonlinear …
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The Dynamics of Rigid Bodies on Moving Deformable Support Media
… G. W. Housner in 1963, a number of alternative models have been proposed for its mathematical simulation. Although, with very few exceptions, the previous models in the literature make the simplified assumption that this motion is planar, this is usually not true since a body will probably not …
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Multi-scale scratching in chemical-mechanical polishing
… or eliminated. This thesis presents scratching models by analytical contact mechanics, finite element analysis, and statistical methods. First, scratching due to hard, abrasive particles was modeled and expressions for the maximum and minimum scratch width and depth were determined. Second, …
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Modelling and Analysis of Close Contact Ultrasonic Power Transfer Systems with Metal Barriers
… on metal barriers by developing appropriate models that characterize the system behaviour and predict the output characteristics for various mechanical configurations. In this thesis, UPT systems are characterized from a structural perspective rather than by the conventional wave theory …
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Astronaut-centric analysis of a jetpack with integrated control-moment gyroscopes for enhanced extravehicular activity performance
… The combined astronaut dynamics and controls models formed a full simulation that was integrated into a Virtual Reality (VR) environment at JSC to offer a platform for two human evaluations comparing the proposed and current control systems. Although computational analyses demonstrated …
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Sensitivity Analysis and Optimization of Multibody Systems
… method is developed for multibody dynamic models that employ Maggi's formulation. An adjoint variable method is developed for explicit and implicit first order Maggi's formulations, second order Maggi's formulation, and first and second order penalty formulations. The resulting …
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Study of micro-sized particle deposition using DEM, CFD-DEM and SPH approach
… granular particles using two history dependent contact models. The simulation results are presented using porosity, coordination number, RDF and force distribution. It was observed that the particles with Gaussian distribution always have the lowest packing density while the mono-sized particles …
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State of the Art Roller Rig for Precise Evaluation of Wheel-Rail Contact Mechanics and Dynamics
… single-wheel roller rig for studying contact mechanics and dynamics in railroad applications. The use of indoor-based simulation tools has become a mainstay in vehicle testing for the automotive and railroad industries. In contrast to field-testing, roller rigs offer a controlled …
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