Use of frequency power law to link the results of two EM testing methods for the characterization of humid concretes

2011 ◽  
Author(s):  
Geraldine Villain ◽  
Amine Ihamouten ◽  
Xavier Derobert
Keyword(s):  
Power Law ◽  
Testing Methods ◽  
Frequency Power

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.

scholarly journals An Automated Aerosol Collection and Extraction System to Characterize Electronic Cigarette Aerosols

2021 ◽  
Vol 9 ◽  
Author(s):  
Yeongkwon Son ◽  
Andrey Khlystov
Keyword(s):  
Electronic Cigarette ◽  
Extraction System ◽  
Cigarette Use ◽  
Testing Methods ◽  
Sampling System ◽  
Toxic Compounds ◽  
Use Patterns ◽  
Variable Power ◽  
Flow Control System

Electronic cigarette (e-cigarette) market increased by 122% during 2014–2020 and is expected to continue growing rapidly. Despite their popularity, e-cigarettes are known to emit dangerous levels of toxic compounds (e.g., carbonyls), but a lack of accurate and efficient testing methods is hindering the characterization of e-cigarette aerosols emitted by a wide variety of e-cigarette devices, e-liquids, and use patterns. The aim of this study is to fill this gap by developing an automated E-cigarette Aerosol Collection and Extraction System (E-ACES) consisting of a vaping machine and a collection/extraction system. The puffing system was designed to mimic e-cigarette use patterns (i.e., power output and puff topography) by means of a variable power-supply and a flow control system. The sampling system collects e-cigarette aerosols using a combination of glass wool and a continuously wetted denuder. After the collection stage, the system is automatically washed with absorbing and extracting liquids (e.g., methanol, an acetaldehyde-DNPH solution). The entire system is controlled by a computer. E-ACES performance was evaluated against conventional methods during measurements of nicotine and carbonyl emissions from a tank type e-cigarette. Nicotine levels measured using glass fiber filters and E-ACES were not significantly different: 201.2 ± 6.2 and 212.5 ± 17 μg/puff (p = 0.377), respectively. Differences in formaldehyde and acetaldehyde levels between filter-DNPH cartridges and the E-ACES were 14% (p = 0.057) and 13% (p = 0.380), respectively. The E-ACES showed reproducible nicotine and carbonyl testing results for the selected e-cigarette vaping conditions.

PREPARATION, MORPHOLOGY AND MECHANICAL PROPERTIES OF EPOXY NANOCOMPOSITES WITH ALUMINA FILLERS

2010 ◽  
Vol 24 (01n02) ◽  
pp. 136-147 ◽  
Author(s):  
SHEAU HOOI LIM ◽  
KAIYANG ZENG ◽  
CHAOBIN HE
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Thermomechanical Properties ◽  
Nano Particles ◽  
Testing Methods ◽  
Transmission Electron ◽  
Alumina Particles ◽  
Thermomechanical Testing ◽  
Platelet Shape

This paper presents recent studies on the processing and characterization of epoxy-alumina nanocomposites. Nano-sized alumina particles are incorporated into epoxy resin via solvent-assisted method, so that the particles are dispersed homogeneously in the epoxy matrix. The morphologies, mechanical and thermomechanical properties of the resulting nanocomposites are studied using transmission electron microscope (TEM), conventional tensile testing and thermomechanical testing methods. TEM results show that the alumina nano-particles with a higher specific surface area tend to agglomerate. Furthermore platelet shape particles shows a better dispersion homogeneity as well as better improvement in the mechanical properties of the composites compared to the rod shape particles.

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
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