Electric Field Strengths

The electric field strength, denoted by E, is a vector quantity directed from negative charge regions to positive charge regions. Its module is expressed in volt per metre (V.m ). It is clearly defined by the vector equation as follows  

19 The effect of (a) DOP and (b) Ti02 on the breakdown field strength. Reprinted from [Nguyen et al. (2009)]. 

Based on the above experimental results, the elastic energy of the synthetic elastomer with different contents of DOP and Ti02 is calculated according to Eq. (6.2) and is shown in Table 6.2 (the electric held applied to the synthetic elastomer with the contents of the hllers of DOP 80 PHR and Ti02 40 PHR is 16MV/m because the breakdown held strength of this synthetic elastomer is only 16.6MV/m). 

Based on the results in Table 6.2, it is shown that the synthetic elastomer with the contents of 80 PHR DOP and 30 PHR Ti02 has a better radial 

In the effort of finding a new DE, the synthetic elastomer is proposed. Its improved performance characterized with dielectric constant, elastic modulus and stress relaxation can be proved with the highest energy density among the materials tested. Under the comprehensive comparisons with the materials commercially available, its possibility as means of actuation is validated. Additionally, the synthetic elastomer properties can be adjusted based on the different contents of the fillers added to the synthetic elastomer. Different additives can be added to this material to create new DE which can be adapted to our requirements. Future research activity may focus on the development of a new composite synthetic elastomer-filler that can accommodate more requirements of our applications. 

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This perturbation method is claimed to be more efficient than the fluctuating dipole method, at least for certain water models [Alper and Levy 1989], but it is important to ensure that the polarisation (P) is linear in the electric field strength to avoid problems with dielectric saturation. 

The dielectric constant (permittivity) tabulated is the relative dielectric constant, which is the ratio of the actual electric displacement to the electric field strength when an external field is applied to the substance, which is the ratio of the actual dielectric constant to the dielectric constant of a vacuum. The table gives the static dielectric constant e, measured in static fields or at relatively low frequencies where no relaxation effects occur. 

The magnitude of the induced dipole moment depends on the electric field strength in accord with the relationship = nT, where ]1 is the induced dipole moment, F is the electric field strength, and the constant a is caHed the polarizabHity of the molecule. The polarizabHity is related to the dielectric constant of the substance. Group-contribution methods (2) can be used to estimate the polarizabHity from knowledge of the number of each type of bond within the molecule, eg, the polarizabHity of an unsaturated bond is greater than that of a saturated bond. 

When corona occurs, current starts to flow in the secondary circuit and some dust particles are precipitated. As potential is increased, current flow and electric field strength increase until, with increasing potential, a spark jumps the gap between the discharge wire and the collecting surface. If this "sparkover" is permitted to occur excessively, destmction of the precipitator s internal parts can result. Precipitator efficiency increases with increase in potential and current flow the maximum efficiency is achieved at a potential just short of heavy sparking. 

An interesting development of the PHB technique leads to four-dimensional data storage. By variation of an electric field appHed to the sample the spectral profile of the absorption holes can specifically be altered. This adds two more dimensions to the geometrically two-dimensional matrix frequency of laser light and electrical field strength (174). 

Electromagnetic interference (EMI) testing has become more prevalent for materials that either emit or are affected by EMI. Shielding efficiency (SE) of materials is deterrnined by measuring electric field strength between a transmitter and receiver with or without the presence of the material under test. Several researchers have suggested a correlation between volume resistivity and SE values (300,301). 

At electric-field strengths greater than flux is proportional to AP up to the critical pressure P where E becomes E (Fig. 12). 

The heating effect is the limiting factor for all electrophoretic separations. When heat is dissipated rapidly, as in capillary electrophoresis, rapid, high resolution separations are possible. For electrophoretic separations the higher the separating driving force, ie, the electric field strength, the better the resolution. This means that if a way to separate faster can be found, it should also be a more effective separation. This is the opposite of most other separation techniques. 

FIG. 22-29 Qualitative effects of Reynolds number and applied-electric-field strength on the filtration permeate flux J. Dashed lines indicate large particles (radial migration dominates) solid lines, small particles (particle diffusion dominates). 

While several factors determine ESP collection efficiency, ESP size is most important. Size determines treatment time, the longer a particle spends in the ESP, the greater its chance of being collected. Maximizing electric field strength will maximize ESP collection efficiency. Collection efficiency is also affected to some extent by dust resistivity, gas temperature, chemical composition (of the dust and the gas), and particle size distribution. 

Strommen, R. and Roland, A., Corrosion Surveillance of Submarine Pipelines by Electric Field Strength Monitoring , Materials Performance, 20 No. 10, 47 (1981)... 

For large thermal energies of the electrons (kT predominates in the denominator), the distribution is maxwellian for large electric field strengths, we obtain the Margenau distribution29 (assuming, for simplicity, constant mean-free path) ... 

Perturbation or chemical relaxation techniques cause an equilibrium to be upset by a sudden change in an external variable such as temperature, pressure, or electric field strength. One then measures the readjustment of the equilibrium concentrations. The time resolution may be as short as 10 10 s, although 10 6 s is the limit more commonly attainable. The method requires no mixing, which is why its time resolution is so good. On the other hand, it is applicable only to equilibria that are properly poised under the conditions used. 

Chemical relaxation techniques were conceived and implemented by M. Eigen, who received the 1967 Nobel Prize in Chemistry for his work. In a relaxation measurement, one perturbs a previously established chemical equilibrium by a sudden change in a physical variable, such as temperature, pressure, or electric field strength. The experiment is carried out so that the time for the change to be applied is much shorter than that for the chemical reaction to shift to its new equilibrium position. That is to say, the alteration in the physical variable changes the equilibrium constant of the reaction. The concentrations then adjust to their values under the new condition of temperature, pressure, or electric field strength. 

No. This happens for only one Uwr value for which the electric field strength E vanishes (Fig. 4.48). 

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