Poling anisotropy

The two estimates, if plotted, look as shown in Fig. 6.4. This explains why fibre-reinforced composites like wood and GFRP are so stiff along the reinforced direction (the upper line of the figure) and yet so floppy at right angles to the direction of reinforcement (the lower line), that is, it explains their anisotropy. Anisotropy is sometimes what you want - as in the shaft of a squash racquet or a vaulting pole. Sometimes it is not, and then the layers of fibres can be laminated in a criss-cross way, as they are in the body shell of a Formula 1 racing car. 

Since the dipoles of chromophore molecules are randomly distributed in an inert organic matrix in amorphous PR materials, the material is centrosymmet-ric and no second-order optical nonlinearity can be observed. However, in the presence of a dc external field, the dipole molecules tend to be aligned along the direction of the field and the bulk properties become asymmetric. Under the assumption that the interaction between the molecular dipoles is negligible compared to the interaction between the dipoles and the external poling field (oriented gas model), the linear anisotropy induced by the external field along Z axis at weak poling field limit (pE/ksT <[Pg.276]

Both the amplitude and the direction of the total poling field are functions of position x. The dipole chromophore will align in response to the field Et(x), and a periodic refractive index modulation will be formed due to both molecular anisotropy and the Pockels effect [37], The contribution from molecular anisotropy is an important, sometimes even dominant, mechanism. 

The Degree Angular Scale Interferometer (DASI) is a very small interferometric array that operates at 26-36 GHz and the South Pole. After measuring the angular power spectrum of the anisotropy (Halverson et al., 2002) the instrument was converted into a polarization sensitive interferometer which detected the E mode polarization at 5.5a by looking at a small patch of sky for most of a year of integration time (Kovac et ah, 2002). The level agreed well with the solid predictions for adiabatic primordial perturbations. Since the measured quantity was the EE autocorrelation, the 5.5a corresponds to a 9% accuracy in the polarization amplitude. 

ACBAR is a bolometric camera array mounted on the VIPER 2 meter diameter telescope at the South Pole. It operates at several frequencies on both sides of the peak of the spectrum of the CMB, and thus can be used to make a sensitive test for the Sunyaev-Zeldovich effect. However, the data released to date are only at one frequency. ACBAR was able to measure the CMB angular power spectrum up to l > 2000 (Kuo et al., 2002), but the size of the surveyed regions was so small that ACBAR s l resolution was too limited to provide much information about tvk. ACBAR was able with its high observing frequency to show that the excess at l > 2000 seen by CBI (Mason et al., 2003) is not a primary CMB anisotropy. It could be due to point sources, or it could... 

In deriving Eq. (48) one ignores the anisotropy of the linear part of the dielectric constant and one assumes that Kleinman s symmetry is valid. Under these conditions, using group theory to reduce the number of non-vanishing tensor elements, the electro-optic tensor for poled polymers is given by... 

As the head track width decreases, remanent magnetization of the main pole tip is likely to occur because of stress-induced anisotropy and increased shape anisotropy in the normal direction to the ABS. The field from this remanent magnetization can... 

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