China
Africa
Explore chapters and articles related to this topic
Prediction of subgrade soil density using dielectric constant of soils
Published in Inge Hoff, Helge Mork, Rabbira Saba, Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields, Volume 1, 2021
Ahmed Abdelmawla, S.Sonny Kim*
The primary material property obtained from GPR surveys is the dielectric constant. The dielectric constant, also known as the relative permittivity, εr, of a homogeneous media relates the relative EM velocity in a material to the speed of light in free space, c (8).εr=c/v2
Introduction to Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
Electric displacement is the displacement of charge perpendicular to the direction of the field produced in an electric field per unit area. Permittivity is the ratio of electric displacement to electric field. Relative permittivity or dielectric constant of a material is its permittivity with respect to permittivity of free space. Displacement current is the rate of displacement of charge in an insulator (a material that does not allow current to flow through).
Components and Devices
Published in Katsuyuki Sakuma, Krzysztof Iniewski, Flexible, Wearable, and Stretchable Electronics, 2020
The key parameters to improve capacitor performance are the relative permittivity and thickness of the dielectric layer. Much research has been performed on dielectric materials for flexible capacitive devices, some of which was discussed previously. There has also been work on device architectures and processes to enable thin and uniform dielectric films. Capacitors fabricated on flexible substrates have been demonstrated in a number of applications. Graddage et al. [19] demonstrated a method to fabricate thin and uniform dielectric layers, which takes advantage of the coffee ring effect, wherein fluid flows to the edge of a feature during drying. This enabled dielectrics as thin as 70 nm to be fabricated, with a capacitance per unit area of 255 pF/mm2. An example structure of such a device is shown in Figure 3.4.
Effects of rotary triboelectrification technology on macerals separation for low-rank coal
Published in International Journal of Coal Preparation and Utilization, 2022
Xian Yushuai, Tao Youjun, Ma Fangyuan, Zhang Xuebin
The relative permittivity is an important parameter to represent the electrical property of dielectric medium or insulating material, and the numerical magnitude of relative permittivity attribute to the molecular dipole moment and surface polarity of materials, which stands for the ability of electrostatic energy storage in the electric field (He et al. 2017). The intensity of electric field was weakened when the dielectric medium filled in electrode plates, which attributes to the generation of induced charges in dielectric medium. The degree of weakened intensity of external electric field could be observed by the relative permittivity of dielectric medium, the increase of relative permittivity means the decline of external electric field. In the electrostatic separation, the decreased external electric field supplied the smaller electrostatic force, and the different deflection angles of particles emerged between the electrode plates. Finally, the separation of materials is realized.
Analysis of electro-osmotic flow by lattice Boltzmann simulation and Helmholtz-Smoluchowski formula
Published in Numerical Heat Transfer, Part B: Fundamentals, 2020
Shr-Chuan Yang, Tony Wen-Hann Sheu
The governing equation for electric potential is chosen to be a Poisson equation [18, 19, 20] where is the vacuum permittivity. It affects the propagation of electric fields. The dielectric properties of materials are generally expressed by the relative permittivity The relative permittivity defines the dielectric properties of a material relative to that of free-space. ρe given below represents the net charge where is the concentration of positive or negative ion, and z is Valence of ion. The Poisson equation relates the electricpotential according to resulting net charge. In Eq. (2), is known as the Faraday constant.