On Variants of the Frequency Power Law for the Electromagnetic Characterization of Hydraulic Concrete

2011 ◽  
Vol 60 (11) ◽  
pp. 3658-3668 ◽  
Author(s):  
Amine Ihamouten ◽  
Khaled Chahine ◽  
Vincent Baltazart ◽  
Géraldine Villain ◽  
Xavier Derobert
Keyword(s):  
Power Law ◽  
Hydraulic Concrete ◽  
Frequency Power

Thermorheological Characterization of Elastoviscoplastic Carbopol Ultrez 20 Gel

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
M. A. Hassan ◽  
Manabendra Pathak ◽  
Mohd. Kaleem Khan
Keyword(s):  
Experimental Investigation ◽  
Yield Stress ◽  
Elastic Properties ◽  
Viscous Dissipation ◽  
Power Law ◽  
Effect Of Temperature ◽  
Rheological Parameters ◽  
Frequency Range ◽  
Power Law Index

The temperature and concentration play an important role on rheological parameters of the gel. In this work, an experimental investigation of thermorheological properties of aqueous gel Carbopol Ultrez 20 for various concentrations and temperatures has been presented. Both controlled stress ramps and controlled stress oscillatory sweeps were performed for obtaining the rheological data to find out the effect of temperature and concentration. The hysteresis or thixotropic seemed to have negligible effect. Yield stress, consistency factor, and power law index were found to vary with temperature as well as concentration. With gel concentration, the elastic effect was found to increase whereas viscous dissipation effect was found to decrease. Further, the change in elastic properties was insignificant with temperature in higher frequency range of oscillatory stress sweeps.

Invariants of Chaotic Attractor in a Nonlinearly Damped System

1998 ◽  
Vol 65 (4) ◽  
pp. 875-879 ◽  
Author(s):  
B. Ravindra ◽  
P. Hagedorn
Keyword(s):  
Power Law ◽  
Chaotic Attractor ◽  
Correlation Dimension ◽  
Ml Estimation ◽  
State Space Reconstruction ◽  
Damped System ◽  
Building Models ◽  
Prediction And Control ◽  
And Control

The characterization of a chaotic attractor in a driven, Duffing-Holmes oscillator with power-law damping is considered. State space reconstruction of the time series of the attractor is carried out to investigate its structure. The invariants associated with the attractor such as correlation dimension and entropy are computed. Also the maximum-likelihood (ML) estimation of dimension and entropy are carried out. The use of obtained invariants in building models for prediction and control using power-law dampers is discussed.

A volume integral approach for the modelling and design of HTS coils

2019 ◽  
Vol 38 (4) ◽  
pp. 1133-1140 ◽  
Author(s):  
Yazid Statra ◽  
Hocine Menana ◽  
Lamia Belguerras ◽  
Bruno Douine
Keyword(s):  
Power Law ◽  
Strong Dependence ◽  
Superconducting Devices ◽  
Electromagnetic Properties ◽  
Integral Approach ◽  
Volume Integral ◽  
Content Type ◽  
High Level ◽  
Modelling Approach

Purpose The purpose of this paper is to develop a rapid and realistic modelling approach for the design and characterization of high temperature superconducting (HTS) coils and windings carrying DC currents. Indeed, the strong dependence of the electromagnetic properties of such materials on the magnetic field makes the design and characterization of HTS systems a delicate operation where local quantities have to be evaluated. Design/methodology/approach A volume integral modelling approach has been developed taking into account the electric nonlinearity of the HTS material which is represented by power law. The variations of the characteristic quantities of the HTS (critical current density and power law exponent) with the magnetic flux density are also taken into account by using Kim’s law. The volume integral modelling allows to model only the active parts of the system and thus to overcome the difficulties linked to the multiscale dimensions. Findings The model has been tested in a case study in which simulation results were compared to measurements and to finite element analysis. A good agreement was found which validates the model as a rapid and efficient tool for HTS coils and windings design and modelling. Practical implications HTS coils are important elements of emerging superconducting devices which require a high level of reliability, such as generators or motors. The proposed approach is interesting to speed up the design and optimization procedures of such systems. Originality/value Advanced structures of the basic elements have been used in the volume integral modelling, which results in a considerable gain in computation time and in memory-space saving while keeping a high level of precision and realism of the modelling, which has been verified experimentally.

scholarly journals Analysis of the geomagnetic activity of the <i>D<sub>st</sub></i> index and self-affine fractals using wavelet transforms

2004 ◽  
Vol 11 (3) ◽  
pp. 303-312 ◽  
Author(s):  
H. L. Wei ◽  
S. A. Billings ◽  
M. Balikhin
Keyword(s):  
Brownian Motion ◽  
Geomagnetic Activity ◽  
Power Law ◽  
Wavelet Transforms ◽  
Effective Measure ◽  
Dst Index ◽  
Power Spectral ◽  
Power Law Exponent ◽  
Brownian Motion Model

Abstract. The geomagnetic activity of the Dst index is analyzed using wavelet transforms and it is shown that the Dst index possesses properties associated with self-affine fractals. For example, the power spectral density obeys a power-law dependence on frequency, and therefore the Dst index can be viewed as a self-affine fractal dynamic process. In fact, the behaviour of the Dst index, with a Hurst exponent H≈0.5 (power-law exponent β≈2) at high frequency, is similar to that of Brownian motion. Therefore, the dynamical invariants of the Dst index may be described by a potential Brownian motion model. Characterization of the geomagnetic activity has been studied by analysing the geomagnetic field using a wavelet covariance technique. The wavelet covariance exponent provides a direct effective measure of the strength of persistence of the Dst index. One of the advantages of wavelet analysis is that many inherent problems encountered in Fourier transform methods, such as windowing and detrending, are not necessary.

Improved description of shock wave evolution in media with frequency power law dependent attenuation

2001 ◽  
Vol 109 (5) ◽  
pp. 2263-2265 ◽  
Author(s):  
Kirk D. Wallace ◽  
Mark R. Holland ◽  
James G. Miller
Keyword(s):  
Shock Wave ◽  
Power Law ◽  
Wave Evolution ◽  
Frequency Power

Optimization and Characterization of Aluminum Induced Texture Using Radio Frequency Power

2020 ◽  
Vol 835 ◽  
pp. 359-366
Author(s):  
Hazim E. Elsorogy ◽  
Ahmed G. Soliman ◽  
Mai M. Elshahidy ◽  
Amr E. Abdelhakeem ◽  
Nour M. Elmahdy
Keyword(s):  
Optical Absorption ◽  
Radio Frequency ◽  
Glass Sheet ◽  
Rf Power ◽  
X Ray Diffraction ◽  
Corning Glass ◽  
Soft Surface ◽  
Frequency Power ◽  
Dipping Time

The purpose of this study aims to investigate the surface morphology and roughness of Aluminum induced glass texturing (AIT) substrate after different surface treatments. Aluminum layers were deposited in thickness 370 nm and 240 nm on corning glass sheet using Radio Frequency (RF) power. The effect of different concentrations of hydrofluoric acid (HF), 4%, 5% and 6% on morphology, optical absorption and surface roughness of glass was described. The dipping time of coated glass sheet in HF for 2 min and 5 min created very rough and soft surface, respectively. Optical absorption of AIT substrate after dipping in HF was measured. The optimum texturing process achieved by deposition of aluminum layer 240 nm of thickness and dipping the substrate in 5% HF. The AIT substrate was characterized by low angle X-ray diffraction (XRD), ultraviolet-visible spectrophotometer (UV-VIS), stylus profiler and scanning electron microscope (SEM).

Characterization of lubrication of asymmetric rollers including thermal effects

2015 ◽  
Vol 67 (3) ◽  
pp. 246-255
Author(s):  
Venkata Subrahmanyam Sajja ◽  
Dhaneshwar Prasad
Keyword(s):  
Power Law ◽  
Thermal Effects ◽  
Design Methodology ◽  
Hydrodynamic Lubrication ◽  
Flow Equation ◽  
Theoretical Problem ◽  
Governing Equations ◽  
Content Type ◽  
The Mean

Purpose – The purpose of this paper is to deal with the qualitative analysis of hydrodynamic lubrication of asymmetric rollers with non-Newtonian incompressible power law lubricants including Newtonian. Design/methodology/approach – The fluid flow governing equations such as equation of motion along with continuity and thermal equations are solved first analytically and investigated numerically by the Runge-Kutta Fehlberg method. Findings – As a result of this work, it is found that there is a significant change in temperature, pressure, load and traction with Newtonian and non-Newtonian fluids. Research limitations/implications – The authors considered incompressible hydrodynamic lubrication of two rigid asymmetric rollers, one of them is assumed to be adiabatic. The convection term of the heat flow equation is taken in its average form. Originality/value – It is a theoretical problem of two heavily loaded rigid cylindrical rollers with cavitations, where the consistency of the power law lubricant is assumed to vary with pressure and the mean film temperature. It has not appeared in the literature.

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