China
Africa
Explore chapters and articles related to this topic
Electrical Properties of Polymer/Ceramic Composites
Published in Noureddine Ramdani, Polymer and Ceramic Composite Materials, 2019
Dielectric properties in polymers are due to electronic, ionic, molecular, and interfacial polarization. These properties are associated with the physical and chemical structure of the polymers. Dielectric spectroscopy is a non-invasive, very sensitive technique to investigate complex systems and is frequently used to study relaxation processes and conductivity. In dielectric experiments, when an AC voltage is applied to a polymer, it produces an alternating electric polarization.
Microwave Emission of the Ocean
Published in Victor Raizer, Advances in Passive Microwave Remote Sensing of Oceans, 2017
In the electrodynamic sense, the ocean mixing environment can be represented by a composite medium with changing dielectric and physical parameters. In this case, microwave radiometry is able to provide diagnostics of turbulent features located at a thin (<1 m) subsurface layer. The technique is based on the method of microwave impedance spectroscopy. Impedance spectroscopy (also called dielectric spectroscopy) is widely used in electrical engineering and antenna technology for measuring parameters of composition dielectric materials as a function of electromagnetic frequency (Kremer and Schönhals 2003; Barsoukov and Macdonald 2005).
Distinguished identification of halal and non-halal animal-fat gelatin by using microwave dielectric sensing system
Published in Cogent Engineering, 2019
Animal fat is a solid form of lipid materials, which is gained from animals (Doppernberg et al., 2010). Chemically, it is composed of triglyceride, which is also known as triacylglycerol (TAG); a chemical composite consists of one molecule of glycerol and three fatty acids (Lim et al., 2011). Most animal fats are some combination of saturated fatty acids, monosaturated fatty acids and polyunsaturated linoleic acid and linolenic acid (Mariod, Bushra, Abdel-Wahab, & Ain, 2011a). In most cases, animal fats such as lard and tallow have roughly 40–60% saturated fat and remain solid at room temperature (Pensioen et al., 2010). Dielectric spectroscopy measures the electric and dielectric properties of a substance as a function of the frequency domain. It occurs due to the interaction of an external electric field with electrical dipole moment and the charges of the medium (Stanley, 2010). It is vital as it provides bunches of information about the atomic and molecular motions besides the relaxation processes. It offers certain advantages over some conventional techniques used to study the electrokinetic properties of colloidal particles. Microwave is sort of electromagnetic wave within a frequency range of 300 MHz to 300 GHz. By referring Equation (1), the frequency f is connected to a corresponding wavelength by the velocity of light c (Yarmand et al., 2011).
Dielectric spectroscopic sensing of fine liquid droplets in an airstream
Published in International Journal of Fluid Power, 2018
Safal Kshetri, Brian L. Steward, Stuart J. Birrell
Dielectric spectroscopy has potential as a sensing technology for detecting liquid droplets in compressed air. Dielectric spectroscopy is the measurement of dielectric properties of a material at multiple frequencies. The dielectric properties of a material explain the electrical interaction between the material and an electric field. Normally, this interaction depends on the frequency of the applied field and can be described best using relative complex permittivity, . The real part denotes the dielectric constant of the material and is a measure of the ability of the material to store electrical energy. The imaginary part, , denotes the dielectric loss factor and is associated with the loss of energy in a material relative to the applied external electrical field. This relative complex permittivity of the material can be measured as a function of frequency using dielectric spectroscopy (Von Hippel 1954). Dielectric spectroscopy has been used for comparing different petroleum fractions(Tjomsland et al. 1996, Folgero 1998), sensing moisture dynamics in oil-impregnated pressboard (Sheiretov and Zahn 1995) and monitoring moisture content and insulation degradation in oil transformers (Koch and Feser 2004).
Bioethanol fuel quality assessment using dielectric spectroscopy
Published in Biofuels, 2021
Azar Khodabakhshikoulaei, Hassan Sadrnia, Mohammad Tabasizadeh, Barat Ghobadian, Vijaya Raghavan
Meanwhile, several models have been used successfully to predict the flash point and octane number of bioethanol blends. However, in these models, bioethanol was considered an additive. One fast, non-destructive, and less time-consuming method for analyzing the relevant properties is dielectric spectroscopy. In the literature, a few studies can be found on using dielectric properties to assess the quality of fuels and biofuels. Campos et al. measured the dielectric constant and loss factor of a pure liquid mixture during acid-catalyzed transesterification using an open-ended coaxial probe method at a frequency range of 300 MHz–13 GHz. The results indicated that using a catalyst had a significant impact on dielectric properties at higher alcohol content [12]. Guan et al. could well predict the RON and MON of clean gasoline using a combination of dielectric properties and partial least squares multivariate calibration approaches [13]. Zarein et al. used several algorithms to model and optimize fish biodiesel features through dielectric permittivity. They found that a dielectric constant of 3.72 and a loss factor of 0.89 at the highest frequency produced the optimal fatty acid methyl esters (FAME) content and flash point [14]. Alvarez et al. used temperature, solvent composition, and solid–liquid ratio as variables to model the complex permittivity of solid grape pomace and ethanol–water solvent. Compared to the experimental results, the predicted model showed the dielectric properties of this multiphase media multiplied with an average deviation of 8.1% and 24.8% for the dielectric constant and the loss factor, respectively [15]. However, no published work explains the relationship between dielectric properties and the physical features of bioethanol.