Resonance ultrasonic spectroscopy

The discrepancy between the first determination of the elastic constants and the following ones is not surprising, due to the very indirect way utilised in [33]. The difference between the Brillouin spectroscopy results on the one hand and those obtained with resonance ultrasonic spectroscopy on the other one is mostly due to the difference in C33. Although the authors claim that the most precise measurements of elastic moduli are obtained using ultrasonic techniques, the samples should have a... 

As stated above, US secondary responses are obtained under speoific conditions such as resonance, are derived from primary responses suoh as impedanoe or are a fraction of the overall primary response e.g. absorption, refleotion). Measurements made under resonanoe conditions are the basis for resonance ultrasonic spectroscopy (RUS), also known as high-resolution ultrasonic spectroscopy — the latter name was given by the leading manufacturer of RUS instruments. The importanoe of this teohnique warrants disoussion of its basic principles below. 

Aerospace struetwes made of composite. As part of the evaluation of the developed ultrasonic spectroscopy system the NSC software was tested on ultrasonic resonance spectra from composite panel samples. Spectra were collected with four different types of damages, and from flawless samples. The damages included a small cut in one of the carbon fiber... 

Fokker Bond Tester. An ultrasonic inspection technique commonly used for aircraft structures is based on ultrasonic spectroscopy [2]. Commercially available instruments (bond testers) used for this test operate on the principle of mechanical resonance in a multi-layer structure. A piezoelectric probe shown in Figure 3b, excited by a variable frequency sine signal is placed on the surface of the inspected structure. A frequency spectrum in the range of some tens of kHz to several MHz is acquired by the instrument, see Figure 3a. 

We have presented a neural network based spectrum classifier (NSC) aimed at ultrasonic resonance spectroscopy. The ultrasonic spectroscopy and the NSC has been evaluated in many industrial applications, such as concrete inspection, testing of aerospace composite structures, ball bearings, and aircraft multi-layer structures. The latter application has been presented in some detail. 

Sensitivity Enhancement by the use of Acoustic Resonators in cw Ultrasonic Spectroscopy. 

Other relevant studies on physical properties of emulsions are those of McClements et al. (1993), Dickinson and Pawlowsky (1996), Dickinson et al. (1996), and Demetriades et al. (1997). The application of nuclear magnetic resonance (NMR) technique (Simoneau et al., 1993) and ultrasonic spectroscopy (Demetriades et al., 1996) to study the stability of emulsions were discussed. The rheological behavior of salad dressings and mayonnaises that are emulsions will be discussed in Chapter 5. 

Fig. 7.3 The resonance behavior of three different microcapsule formulations obtained by ultrasonic spectroscopy. The ultrasound attenuation (y-axis, given relative to the maximum) is measured over a driving frequency from 1 to 20 MHz (x-axis). Each capsule population has the same mean diameter of about 5 pm, but the shell thickness dif fers significantly (45, 105 and 236 nm). Tailoring the geometry of the USCA tunes the resonance properties. For example, increasing the...

Af/f is small whenever rq,2 is close to one. Conversely, since the QCM only works well when the normalized frequency shift Af/ff is small, it makes sense to assume 1. Equation 39 shows that quartz crystals are acoustic re-flectometers. The results of QCM measurements can therefore be easily compared to data obtained with other forms of ultrasonic reflectometry [57,58]. It is well known from optical techniques such as elUpsometry [59] or surface plasmon resonance (SPR) spectroscopy [60] that a film thickness can be inferred from a measurement of the reflectivity. The same applies to acoustics. 

Recently, Kinney etal. [2004] used the technique of resonant ultrasound spectroscopy (RUS) tomeasure the elastic constants (Qj) of human dentin from both wet and dry samples. As (%) and Ac (%) calculated from these data are included in both Table 47.5 and Figure 47.4. Their data showed that the samples exhibited transverse isotropic symmetry. However, the Qj for dry dentin implied even higher symmetry. Indeed, the result of using the average value for Q i and Cu = 36.6 GPa and the value for C44 = 14.7 GPa for dry dentin in the calculations suggests that dry human dentin is very nearly elastically isotropic. This isotropic-lifce behavior of the dry dentin may have clinical significance. There is independent experimental evidence to support this calculation of isotropy based on the ultrasonic data. Small angle x-ray diffraction... 

It is not possible to discuss all the methods available for characterizing foods critically and systematically in a single volume. Methods pertaining to interfaces (food emulsions, foams, and dispersions), fluorescence, ultrasonics, nuclear magnetic resonance, electron spin resonance, Fourier-transform infrared and near infrared spectroscopy, small-angle neutron scattering, dielectrics, microscopy, rheology, sensors, antibodies, flavor and aroma analysis are included. 

Reversible attachment of nanostructures at molecular printboards was exemplified by the adsorption and desorption of CD-functionalized nanoparticles onto and from stimuli-responsive pre-adsorbed ferrocenyl-dendrimers at a CD SAM (Fig. 13.7).65 Electrochemical oxidation of the ferrocenyl endgroups was employed to induce desorption of the nanostructure from the CD SAM. An in situ adsorption and desorption of ferrocenyl dendrimers and CD-functionalized Au nanoparticles (d 3 nm) onto and from the molecular printboard was observed by a combination of surface plasmon resonance spectroscopy (SPR) and electrochemistry. Similar behavior was observed when larger CD-functionalized silica nanoparticles (d 60 nm) were desorbed from the surface with the aid of ultrasonication. 

Ultrasonic Sciences (www. ultrasonic-scientific. com) Attenuation and velocity spectroscopy-resonance Materials characterization No Yes... 

Many other methods have been employed to study CTC in biological systems, such as calorimetry, mixed fusion analysis, solubility and partition methods, ultrasonic methods, spectropolarimetry, reflective infrared spectroscopy, Raman spectroscopy, flash photolysis spectroscopy, nuclear quadrupole resonance spectroscopy, and magnetic susceptibility methods, to name several of a very long list. X-ray photoelectron spectroscopy (XPS) has also been used to elucidate some EDA interactions in electrically active macromolecules. XPS is useful for detecting the redistribution of charges in complexes of such compounds, (e.g., in the presence of phosphate acceptors, the nature of the semiconductive environment of S, O, and N bridges in macromolecules is affected profoundly [111]. 

Part II of the book deals with lesser known aspects of US for the analytical chemists such as its use as an energy source for detection purposes. Thus, ultrasound-based detection techniques viz. US spectrometry in its various modes including ultrasound attenuation, ultrasonic velocity, resonant ultrasound, laser-generated, ultrasound reflection and acoustic wave impedance spectroscopies) are dealt with in Chapter 9. Finally, Chapter 10 is devoted to seleoted applioations of US spectrometry — mostly non-analytical applications from whioh, however, analytical chemists can derive new, interesting analytical uses for ultrasound-based deteotion techniques. 

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