scholarly journals Static Regime Imaging of Locations of Certain 3D Electromagnetic Imperfections from a Boundary Perturbation Formula

2014 ◽  
Vol 32 (4) ◽  
pp. 412-441
Author(s):  
Séraphin M. Mefire
Keyword(s):  
Boundary Perturbation ◽  
Perturbation Formula ◽  
Static Regime

scholarly journals On the Tidal Prism: The Roles of Basin Extension, Bottom Friction and Inlet Cross-Section

2021 ◽  
Vol 9 (1) ◽  
pp. 88
Author(s):  
Marco Petti ◽  
Sara Pascolo ◽  
Silvia Bosa ◽  
Nadia Busetto
Keyword(s):  
Cross Section ◽  
Bottom Friction ◽  
Static Method ◽  
Tidal Prism ◽  
Empirical Relationships ◽  
Cross Sectional ◽  
Asymptotic Regime ◽  
Static Regime ◽  
The One ◽  
Basin Area

The prism of the Lignano tidal inlet was approximately constant over the last forty years, although the section width has halved. This has led to questions concerning the factors that most influence the tidal prism, and on the applicability of the well-known A–P relationship. A conceptual scheme of the sea–channel–lagoon system has been used to perform a sensitivity analysis of different parameters that characterize both the basin and the inlet cross-section. A 2D hydrodynamic model has been applied to evaluate the prism and compare it to the one derived by a static method, which is the basis of the analytical derivation of the A–P linkage. Three regimes have been found in the prism variability as a function of the basin extension: a linear static regime between prism and basin area; an asymptotic regime in which the prism depends only on the basin bottom friction; and an intermediate one. In addition, the roles of the inlet and channel sizes on the prism value have been investigated. The results, compared to the empirical relationships between the prism and the inlet cross-section, show that a variation in the cross-sectional area does not always corresponds to a change in tidal prism.

On the Application of the Lu-Gre Model to Simulate Joint Friction in Multi-Body Systems

2011 ◽  
Author(s):  
Kedar Gajanan Kale ◽  
Rajiv Rampalli
Keyword(s):  
Friction Model ◽  
Lugre Model ◽  
Friction Forces ◽  
Joint Friction ◽  
Modeling Techniques ◽  
Static Regime ◽  
Increasing Demand ◽  
Automotive Suspension ◽  
Multi Body

Advances in the application of multi-body simulation technology to real world problems have led to an ever increasing demand for higher fidelity modeling techniques. Of these, accurate modeling of friction is of strategic interest in applications such as control system design, automotive suspension analysis, robotics etc. Joints (sometimes referred to as constraints) play an important role in defining the dynamics of a multi-body system. Hence, it is imperative to accurately account for friction forces arising at these joints due to the underlying interface dynamics. In this paper, we discuss the application of LuGre, a dynamic friction model to simulate joint friction. We choose the LuGre model due to its ability to capture important effects such as the Stribeck effect and the Dahl effect. The native 1-d LuGre model is extended to formulate friction computations for non-trivial joint geometries and dynamics in 2 and 3 dimensions. It is also extended to work in the quasi-static regime. Specific applications to revolute, cylindrical and spherical joints in multi-body systems are discussed. Finally, an engineering case study on the effects of joint friction in automotive suspension analysis is presented.

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.

The EPR Zero-Field Splitting D and its Pressure and Temperature Dependence for Trigonal Mn2+ Centers in [Zn(H2O)6](BF4)2:Mn2+ Crystal

2006 ◽  
Vol 61 (5-6) ◽  
pp. 289-292 ◽  
Author(s):  
Hong-Gang Liu ◽  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng ◽  
Lv He
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Coupling Mechanism ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Thermal Expansion Coefficients ◽  
Perturbation Formula ◽  
Expansion Coefficients

The EPR zero-field splitting D (= b02 ) and its pressure and temperature dependence for trigonal Mn2+ centers in low and room temperature phases in [Zn(H2O)6](BF4)2 :Mn2+ crystal are studied by a high-order perturbation formula based on the dominant spin-orbit coupling mechanism. From the studies, the local trigonal distortion angles, the local angular compressibilities and the local angular thermal expansion coefficients for Mn2+ centers in both phases of the [Zn(H2O)6](BF4)2 crystal are estimated. The results are discussed

Hysteresis in thermal expansion of the quasi 1-dimensional conductor TaS3: Coupling of the underlying and the electronic crystals

2002 ◽  
Vol 12 (9) ◽  
pp. 287-287
Author(s):  
V. Ya. Pokrovskii ◽  
A. V. Golovnya ◽  
P. M. Shadrin
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
Charge Density ◽  
Hysteresis Loop ◽  
Charge Density Waves ◽  
Small Sample ◽  
Temperature Hysteresis ◽  
Static Regime ◽  
Peierls Transition ◽  
Sample Elongation

An interferometer-based setup for measurements of length of needle-like samples is developed, and thermal expansion of o-TaS3 crystals is studied. Below the Peierls transition the temperature hysteresis of length L is observed, the width of the hysteresis loop $\delta L/L$ being up to $5\times 10^{-5}$. Curiously, $L(T)$ changes so that it is in front of its equilibrium value. The hysteresis loop couples with that of conductivity. With lowering T the charge-density waves' (CDW) elastic modulus grows and at 100 K becomes comparable with that of the lattice Yl. The results justify the assumption about the strain dependence of the CDW wave vector and clarify the nature of the anomalies of Yl which occur on the CDW depinning. In particular, Yl, is expected to show a strong drop in the static regime, if measured at sufficiently small sample elongation $(\delta L/L < 10^{ -5}) $.

Finite difference analysis of Rayleigh wave transmission past an upward step change

1984 ◽  
Vol 74 (3) ◽  
pp. 893-911
Author(s):  
Masahiko Fuyuki ◽  
Masayoshi Nakano
Keyword(s):  
Finite Difference ◽  
Difference Scheme ◽  
Perturbation Method ◽  
Rayleigh Wave ◽  
Finite Difference Scheme ◽  
Step Change ◽  
Boundary Perturbation ◽  
Difference Analysis ◽  
Transmission Coefficients ◽  
Boundary Perturbation Method

Abstract Transmission coefficients of the Rayleigh wave past an upward step change are obtained by the finite difference scheme. In the region of large height of a step relative to a wavelength h/λ, individual phases of the transmitted wave are investigated and the dominant wave in each phase is clarified. For smaller values of h/λ, we examine to what extent the contribution of the diffracted wave due to a step change accounts for the discrepancy between the finite difference results and the prediction of the theory of Mal and Knopoff. In order to explain the transmission coefficients with h/λ close to zero, a boundary-perturbation method is extended to the second order.

scholarly journals Destabilization of Immersed Dense Granular Material Submitted to Localized Fluidization: An Experimental and Numerical Study

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Aboubacar Sidiki Dramé ◽  
Li Wang ◽  
Yanping Zhang
Keyword(s):  
Granular Material ◽  
Granular Medium ◽  
Experimental Approach ◽  
Solid Phase ◽  
Numerical Study ◽  
Lighting System ◽  
Led Lighting ◽  
Hydrogel Beads ◽  
Static Regime ◽  
As Solid Phase

An alternative experimental approach and a numerical analysis for the study of destabilization by localized fluidization of an immersed dense granular material are presented. To visualize the evolutions of the internal structure of the granular medium, the hydrogel beads, composed of about 99% of water and having substantially the same refraction indexes, are used as solid phase. A LED lighting system is used in place of a laser lighting system. As a result, the optical access restriction of porous structure is removed. A real economic alternative for the experimental study of fluid-grain coupling during destabilization by localized fluidization of a granular material is created. The experimental phenomenology presented in the literature is verified: the system passes successively through three different stationary regimes: static regime, fluidized cavity regime, and fluidized chimney regime. Some restrictions of using hydrogel beads as particles in the study of liquid-solid interaction are also discussed.

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