scholarly journals Magnetospheric boundary perturbations on MHD and kinetic scales

2015 ◽  
Vol 120 (1) ◽  
pp. 113-137 ◽  
Author(s):  
S-H Chen ◽  
G Le ◽  
M-C Fok
Keyword(s):  
Magnetospheric Boundary ◽  
Boundary Perturbations

A REFORMULATED BOUNDARY PERTURBATION THEORY IN ELECTROMAGNETISM AND ITS APPLICATION TO A SPHERE

1967 ◽  
Vol 45 (5) ◽  
pp. 1729-1743 ◽  
Author(s):  
M. L. Burrows
Keyword(s):  
Electromagnetic Field ◽  
Perturbation Theory ◽  
Classical Method ◽  
Experimental Results ◽  
Boundary Perturbation ◽  
Conducting Sphere ◽  
Classical Formulation ◽  
Classical Class ◽  
New Formulation ◽  
Boundary Perturbations

The classical method of solving electromagnetic field problems involving boundary perturbations is reformulated in a way that is both more general and simpler. The new formulation makes it easier to apply the theory to the class of boundaries amenable to the classical formulation, and shows that it can also be applied to other boundary shapes. As an example, the perfectly conducting sphere with surface perturbations has been treated, using the methods appropriate only for boundaries in the classical class and also using those applicable to the larger class. Some experimental results which appear to support the theory are reported.

Evolvement law of a macroscopic traffic model accounting for density-dependent relaxation time

2017 ◽  
Vol 31 (31) ◽  
pp. 1750291 ◽  
Author(s):  
Yu-Qing Wang ◽  
Xing-Jian Chu ◽  
Chao-Fan Zhou ◽  
Bin Jia ◽  
Sen Lin ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Traffic Flow ◽  
Flow Model ◽  
Initial Density ◽  
Traffic Model ◽  
Traffic Flow Model ◽  
Density Dependent ◽  
Macroscopic Traffic Flow ◽  
Boundary Perturbations ◽  
Initial Density Distribution

In this paper, a modified macroscopic traffic flow model is presented. The term of the density-dependent relaxation time is introduced here. The relation between the relaxation time and the density in traffic flow is presented quantitatively. Besides, a factor R depicting varied properties of traffic flow in different traffic states is also introduced in the formulation of the model. Furthermore, the evolvement law of traffic flow with distinctly initial density distribution and boundary perturbations is emphasized.

Boundary Perturbations due to the Presence of Small Cracks

2015 ◽  
Author(s):  
Habib Ammari ◽  
Elie Bretin ◽  
Josselin Garnier ◽  
Hyeonbae Kang ◽  
Hyundae Lee ◽  
...  
Keyword(s):  
Asymptotic Formula ◽  
Neumann Boundary ◽  
Representation Formula ◽  
Fundamental Solutions ◽  
Energy Functional ◽  
Finite Hilbert Transform ◽  
Time Harmonic ◽  
Elastic Potential Energy ◽  
Potential Energy Functional ◽  
Boundary Perturbations

This chapter considers the perturbations of the displacement (or traction) vector that are due to the presence of a small crack with homogeneous Neumann boundary conditions in an elastic medium. It derives an asymptotic formula for the boundary perturbations of the displacement as the length of the crack tends to zero. Using analytical results for the finite Hilbert transform, the chapter derives an asymptotic expansion of the effect of a small Neumann crack on the boundary values of the solution. It also derives the topological derivative of the elastic potential energy functional and proves a useful representation formula for the Kelvin matrix of the fundamental solutions of Lamé system. Finally, it gives an asymptotic formula for the effect of a small linear crack in the time-harmonic regime.

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