Frequency loss, high

Carsten, Bmce, High Frequency Losses in Switchmode Magnetics, High Frequency Power Conversion Conference, May 1986. 

Energy loss under low frequency conditions is often used as a key factor for evaluating elastomer compositions. In this respect, the rolling resistance and skidding properties are usually evaluated by tan delta (tan 8) at 60°C and 0°C, where the 60°C value correlates with low frequency loss and 0°C correlates with skid resistance (high frequency loss). 

At low frequencies the loss modulus is linear in frequency and the storage modulus is quadratic for both models. As the frequency exceeds the reciprocal of the relaxation time ii the Rouse model approaches a square root dependence on frequency. The Zimm model varies as the 2/3rd power in frequency. At high frequencies there is some experimental evidence that suggests the storage modulus reaches a plateau value. The loss modulus has a linear dependence on frequency with a slope controlled by the solvent viscosity. Hearst and Tschoegl32 have both illustrated how a parameter h can be introduced into a bead spring... 

Other substrates are being investigated for purposes such as obtaining reduced high frequency losses. The LaA103 material has been used (42) for frequencies of 10 GHz. Reasonable critical current densities are found, Jc 8 x 104 A/cm2 at 77 K. A bilayer structure of the film was found at the substrate surface the first layer had the c axis normal to the substrate and the second layer had the c axis in the plane. 

As a matter of fact, these properties are highly relevant for electrotechnical applications, in particular at high frequencies (losses are proportional to the product of loss factor and frequency). The extremely low loss factor of polyethylene has enabled the use of radar in the second world war. 

Solutions The reasons behind choosing solutions over other dosage forms are their favorable cost advantage, the simplicity of formulation development and production, and the high acceptance by patients [170], However, there are also a few drawbacks, such as rapid and extensive precorneal loss, high absorption via the conjunctiva and the nasolacrimal duct leading to systemic side effects, as well as the increased installation frequency resulting in low patient compliance. 

Of 75 adults with thalassemia major (age range 17-32 years) 50 had normal audiography (69). Of the other 25, 13 had a sensorineural deficit of 35 dB or less, with high frequency losses, and two had a deficit of 35-75 dB. There was no association between hearing loss and age, ferritin concentration, or therapeutic index. The authors concluded that their findings were not different from those in a healthy population of the same age and were not suggestive of an ototoxic effect of deferoxamine. 

Klnetlcally both anionically and radically prepared polymers conform to the following relationships, the rate of photo-oxidation being expressed as the rate of Increase of the high frequency loss (de Vdt). 

Stebbins characterized the thresholds for detection of sound over the range of frequencies normally detectable in the monkey and the effect of an ototoxic agent on these thresholds. This was done by training the monkey to keep its hand in contact with a sensor until it detected the onset of a tone and to break its contact upon detection of the tone. Intensity of the tone was then varied for each frequency tested to determine the intensity at which the monkey was unable to detect the tone. Stebbins was thus able to follow the development of hearing loss produced by an ototoxic antibiotic, from initial high-frequency loss to later low-frequency loss. These changes in hearing in the monkey were correlated with the pattern of receptor loss in the inner ear. 

The prospects for various applications depend, of course, on the materials properties of the superconductor. Many properties are important, including mechanical properties, interfacial interactions and contacts, high frequency loss, and so forth. Here we emphasize as an example the critical current density, which is one of the most vital properties for most applications. 

Another interesting result obtained for solutions of PIB in cyclohexane by Tanaka et al. (2,92) is shown in Fig. 3.4. The reduced storage modulus at infinite dilution is close to the prediction of the Rouse theory while the loss modulus is not. This result indicates the existence of an additional contribution to the intrinsic viscosity at high frequency which might be a frequency-independent high frequency limit [in contrast with the results for PMS (94,99) and for PIB in toluene (2,92)]. We will return to this subject in the following chapter. 

In the microwave region and at lower frequencies the high frequency approximation, used in this work for ice, becomes inapplicable. In particular, this approach does not describe a deep loss minimum e"(v), denoted in Fig. 26b by the dashed line. Such a behavior is typical for ice in a wide temperature range (Fig. 36), but has no analogy in the case of water, where the loss minimum of the g"(v) curve is not emphasized. On the contrary, curve e"(v) exhibits a shallow minimum in a much narrower frequency range (Fig. 37a). Moreover, in ice, only transverse vibration constitutes the loss minimum, while as depicted in Fig. 37c, in water all mechanisms, especially mechanisms a and d, contribute to the loss minimum. 

Forced-Oscillation Experiments. The dynamic moduli were measured as a function of frequency. At high strains (ca. 0.6), the Instron rheometer was used, whereas at lower strains (typically 0.16), the Bohlin VOR rheometer was used because of its greater sensitivity. Figure 6 shows the results obtained for the storage (G ) and loss (G") moduli for a 0.5-g dL" ... 

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