Logarithmically discretized model of bounce averaged gyrokinetics and its implications on tokamak turbulence

2018 ◽  
Vol 25 (10) ◽  
pp. 102306 ◽  
Author(s):  
Shaokang Xu ◽  
P. Morel ◽  
Ö. D. Gürcan
Keyword(s):  
Discretized Model

Initial Investigations Into the Dynamics of Cutting Brushes for Sweeping

2002 ◽  
Vol 124 (4) ◽  
pp. 675-681 ◽  
Author(s):  
G. M. Peel ◽  
G. A. Parker
Keyword(s):  
Steady State ◽  
Centrifugal Force ◽  
Transient Effects ◽  
Test Rig ◽  
Low Speeds ◽  
Discretized Model

Cutting brushes are used at relatively low speeds by various municipal vehicles and in particular road sweeping units. As the name suggests such brushes are designed to “cut” through debris, especially compacted sand or similar matter. The main deflection plane of a bristle (or tine) is along the mount radius, making the tines very stiff in the direction of rotation, hence the cutting action when the brush is rotated. Exploring the literature shows that very little is known, or understood, about the operation of brushes for mechanical sweeping. In this paper a pseudo-static discretized model is developed to investigate the deformations and forces acting on brushes during ideal operation of a horizontal brush on a flat plane. Due to the numerous different sweeper brushes on the market, one common configuration is used as the basis of the model and the paper will detail only the characteristics of this brush. The brush to be investigated is a “cutting brush,” introduced above, where the tines can only deflect along the mount radius. Having developed a model it is used to predict the forces and torques generated within a horizontally rotating brush. The influence of centrifugal force is analyzed although transient effects are neglected and steady state conditions assumed. The predictions of the model are compared to practical results taken from a test rig and the validity of the model is discussed. Agreement between the model and the practical results will be shown to be good, considering the complexities and practical realities involved in analyzing any system which is friction dependent.

scholarly journals An Improved Method to an Impulsive and Delayed Discretized Model

2016 ◽  
Vol 07 (01) ◽  
pp. 108-123
Author(s):  
Yujing Liu ◽  
Lijun Zhang ◽  
Shujing Gao
Keyword(s):  
Improved Method ◽  
Discretized Model

Two Efficient Time-Marching Explicit Procedures Considering Spatially/Temporally-Defined Adaptive Time-Integrators

2021 ◽  
pp. 2150051
Author(s):  
Delfim Soares
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Results ◽  
Spatial Discretization ◽  
Adaptive Procedure ◽  
Excellent Performance ◽  
Time Integrators ◽  
Time Marching ◽  
Adaptive Time ◽  
Discretization Technique ◽  
Discretized Model

In this paper, two explicit time-marching techniques are discussed for the solution of hyperbolic models, which are based on adaptively computed parameters. In both these techniques, time integrators are locally and automatically evaluated, taking into account the properties of the spatially/temporally discretized model and the evolution of the computed responses. Thus, very versatile solution techniques are enabled, which allows computing highly accurate responses. Here, the so-called adaptive [Formula: see text] method is formulated based on the elements of the adopted spatial discretization (elemental formulation), whereas the so-called adaptive [Formula: see text] method is formulated based on the degrees of freedom of the discretized model (nodal formulation). In this context, each adaptive procedure can be better applied according to the specific features of the focused spatial discretization technique. At the end of the paper, numerical results are presented, illustrating the excellent performance of the discussed adaptive formulations.

Confinement and Suppression of Structural Vibrations

2001 ◽  
Vol 123 (4) ◽  
pp. 496-501 ◽  
Author(s):  
Slim Choura ◽  
Ahmet S. Yigit
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Vibrational Energy ◽  
Flexible Structures ◽  
Element Model ◽  
Structural Vibrations ◽  
Feedback Strategy ◽  
Feedback Scheme ◽  
Vibratory Motion ◽  
Discretized Model

A feedback strategy, aiming at confining and suppressing simultaneously the vibratory motion in flexible structures, is proposed. It is assumed that the structure consists of parts that are sensitive to vibration. The proposed strategy makes use of control inputs whose number is less than or equal to that of the dimension of the discretized model. The design objective is to devise a feedback scheme that leads to transferring the vibrational energy from the sensitive parts to the remaining parts of the structure. In order to keep away from the build-up of transferred energy in the nonsensitive parts, the feedback scheme considers, along with the confinement, the suppression of vibration in both the sensitive and nonsensitive parts. The proposed strategy also accounts for the presence of persistent excitations. A finite element model of a cantilever beam is used to show the viability of the proposed strategy.

A NEW DISCRETIZED MODEL IN NONLINEAR KINETIC THEORY—THE SEMICONTINUOUS BOLTZMANN EQUATION

1991 ◽  
Vol 01 (01) ◽  
pp. 113-123 ◽  
Author(s):  
N. BELLOMO ◽  
E. LONGO
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Boltzmann Equation ◽  
Kinetic Theory ◽  
Continuous Dependence ◽  
Modeling And Analysis ◽  
Collision Invariants ◽  
The Mathematical Model ◽  
Nonlinear Kinetic ◽  
Discretized Model

This paper deals with the mathematical modeling and analysis of a new model of the Boltzmann equation with a finite number of velocity moduli, but with a continuous dependence on the velocity directions. The mathematical model is derived in the first part of the paper. Then the analysis of the equilibrium Maxwellian state is dealt with in the second part of the paper with the purpose of showing that the space of collision invariants is the correct one.

scholarly journals Control of 2D Flexible Structures by Confinement of Vibrations and Regulation of Their Energy Flow

2009 ◽  
Vol 16 (2) ◽  
pp. 213-228 ◽  
Author(s):  
Fakhreddine Landolsi ◽  
Slim Choura ◽  
Ali H. Nayfeh
Keyword(s):  
Energy Flow ◽  
Vibrational Energy ◽  
Flexible Structures ◽  
Control Design ◽  
Control Law ◽  
Control Parameters ◽  
Feedback Strategy ◽  
Model Simulations ◽  
Suppression Process ◽  
Discretized Model

In this paper, we investigate the control of 2D flexible structures by vibration confinement and the regulation of their energy flow along prespecified spatial paths. A discretized-model-based feedback strategy, aiming at confining and suppressing simultaneously the vibration, is proposed. It is assumed that the structure consists of parts that are sensitive to vibrations. The control design introduces a new pseudo-modal matrix derived from the computed eigenvectors of the discretized model. Simulations are presented to show the efficacy of the proposed control law. A parametric study is carried out to examine the effects of the different control parameters on the simultaneous confinement and suppression of vibrations. In addition, we conducted a set of simulations to investigate the flow control of vibrational energy during the confinement-suppression process. We found that the energy flow can be regulated via a set of control parameters for different confinement configurations.

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