Phase angle 402 INDEX

Moreover, rotational rheometers can be used in dynamic oscillatory mode, frequency sweep, to assess the elastic G module as well as the viscous G" module and the correlated phase angle 6, as a function of the frequency co. G and G" allow to study the viscoelastic behaviour of HA macromolecules. Fig. (15) shows the frequency sweep curves (G, G", and tg(5) vs. the frequency co) for an HA sample (Mw=1350 kDa, polydispersity index D=1.6, concentration c = 2%) at 20 °C. 

The ratio of the loss index to its relative permittivity, the tangent of its loss angle, 5 or the cotangent of its phase angle, 0. 

Abstract. We present a historical review of polarimetric observations of planetary atmospheres, comets, atmosphereless solar system bodies, and terrestrial materials. We highlight the study of physical and optical parameters of planetary atmospheres. Polarimetric observations of the atmospheres of Venus, Mars, Jupiter and Saturn have made it possible to determine the real part of the refractive index and the cumulative size distribution function for the constituent cloud layers. We describe a simple and reliable method of quantifying absorptive cloud layers of the giant planets and predict the vertical stracture of aerosol layers of planetaiy atmospheres based on the analysis of observational spectropolarimetric data of contours of molecular absorption bands at the center of the planetaiy disk. The method is effective only when experimental data exist in a broad interval of phase angles. Using this method we can determine aerosol sizes in the atmospheres of Uranus and Neptune. 

Figure 9.5 Example of typical powder x-ray diffractogram measured for an ordered mesoporous silica. The diffraction pattern shows reflections at low 2 theta angles indexed to the cubic laid space group (3D cubic MCM-48 phase). The diffractogram is recorded at low angles with a conventional laboratory instrument.

Complex impedance data can also be given as modulus and phase. Phase has been used as an index of nutrition. This is true only in comparison between vectors with the same modulus. For instance, short vectors with a small phase angle are associated with edema, whereas long vectors with an increased phase angle indicate dehydration. The prediction error of fat mass is too high for clinical use (standard error of the estimate in the order of 3-4 L for TBW and 3-4 kg for the fat-free mass) (Sun et al. 2003). 

ASTM D150 Standard Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation includes the determination of relative permittivity, dissipation factor, loss index, power factor, phase angle, and loss angle through specimens of solid electrical insulating materials when the standards used are lumped impedances. The frequency range that can be covered extends from less than 1 Hz to several hundred megahertz. 

An index is the ratio between two measurements made under different conditions but on the same sample volume. The index can be calculated from measurement results with respect to the results from a gold standard or be based, for instance, upon the same parameter measured at different energies or frequencies. Indexes can also be made by a mathematical operation on the combination of measurement results and other parameters such as, for example, height or weight of the measured person. Actually the phase angle (p = arctan(B/G) is an index. 

As with the dynamic mechanical relaxations, it is also possible to check the dielectric behavior of the sample. In this case the thermal analysis is carried out measuring the dielectric constant, dissipation factor, loss index, and phase angle as a function of temperature and frequency. In order to see a dielectric effect, a dipole must be connected with the molecular motion. In this way dielectric relaxation may be more specific than DMA. A combination of DMA, dielectric measurements, and DSC is often needed for a detailed interpretation of the properties of the materials. ... 

---