Ultrasonic device

Projection radiography is widely used for pipe inspection and corrosion monitoring. Film digitisation allows a direct access to the local density variations by computer software. Following to a calibration step an interactive estimation of local wall thickness change based on the obtained density variation is possible. The theoretical model is discussed, the limitations of the application range are shown and examples of the practical use are given. The accuracy of this method is compared to results from wall thickness measurements with ultrasonic devices. 

Thermospray nebulizers are somewhat expensive but can be used on-line to a liquid chromatographic column. About 10% of sample solution is transferred to the plasma flame. The overall performance of the thermospray device compares well with pneumatic and ultrasonic sprays. When used with microbore liquid chromatographic columns, which produce only about 100 pl/min of eluant, the need for spray and desolvation chambers is reduced, and detection sensitivities similar to those of the ultrasonic devices can be attained both are some 20 times better than the sensitivities routinely found in pneumatic nebulizers. 

Even without a rapid gas flow, the droplets produced are very small, at about 1-pm diameter or less, and they are produced at a rate of about 10 per second, similar to the rate of production of droplets in an ultrasonic device. 

Nebulizers are used to introduce analyte solutions as an aerosol spray into a mass spectrometer. For use with plasma torches, it is necessary to produce a fine spray and to remove as much solvent as possible before the aerosol reaches the flame of the torch. Various designs of nebulizer are available, but most work on the principle of interacting gas and liquid streams or the use of ultrasonic devices to cause droplet formation. For nebulization applications in thermospray, APCI, and electrospray, see Chapters 8 and 11. 

ULTRASONE Ultrasonic atomizer Ultrasonic bonding Ultrasonic devices Ultrasonic fusing Ultrasonic generators Ultrasonic instruments... 

Nickel is being used ia magnetostrictive transducers ia some ultrasonic devices, eg, solderiag irons and ultrasonic cleaners, because of its moderate magnetostriction and availabiUty. This market, however, is dominated by piezoelectric transducers of lead zirconate—titanate (PZT) (see Ultrasonics). 

Density Gauges These are used to measure the density or suspended solids content of the feed and underflow streams. Gamma radiation devices are the most commonly used for automatic control, but ultrasonic devices are effective in the lower range of slurry density. Marcy pulp density scales are an effective manually operated device. A solids mass flow indication is usually obtained by combining a density gauge output with the output from a flowmeter. 

Romdhane M, Gourdon C, Casamatta G (1995) Local investigation of some ultrasonic devices by means of a thermal sensor. Ultrasonics 33 221-227... 

The basis for the present-day generation of ultrasound was established as far back as 1880 with the discovery of the piezoelectric effect by the Curies [1-3]. Most modern ultrasonic devices rely on transducers (energy converters) which are composed of piezoelectric material. Such materials respond to the application of an electrical potential across opposite faces with a small change in dimension. This is the inverse of the piezoelectric effect and will be dealt with in detail later (Chapter 7). If the potential is alternated at high frequencies the crystal converts the electrical energy to mechanical... 

One recent medical application is for the destruction of blood dots where a miniaturised ultrasonic device (1 MHz) is attached to the end of a catheter so that it can be... 

The polymer should be dissolved at room temperature [28]. Magnetic stirring devices or laboratory shakers are recommended to aid dissolution. Excessive temperature or ultrasonic devices may cause the polymer to degrade. Polystyrene solutions prepared with solvents such as THF are very stable, as long as MW < 500,000 g mol 1. However, it is a good practice to analyze polymer solutions within 24 hr of their preparation [28]. 

Semisolid samples such as muscle and liver tissues can be homogenized by blending with water or an appropriate aqueous solution such as a buffer in a mechanical or an ultrasonic device to expose the residue to the extraction solvent. Fatty tissue samples are sometimes subjected to heating at 40 or 60 C until fat becomes liquid, prior to extraction of the analytes with hexane (433) or acetonitrile (434), respectively. An alternative pretreatment approach is the enzymatic digestion of the tissue by means of proteolytic enzymes such as subtilisin A (429, 435-437). 

Apparently the dispersive ability of ultrasonic devices is not limited to liquids, but has found application in the dispersion of dust. Modified Hartmann whistles operating between 10 and 15 kHz have been used to enhance the... 

As equivalent to the Mackensen air blower, ultrasonic devices can be used, specifically those manufactured by Rio Grande and Branson (Fig. 4.4.18). With a suitably chosen nozzle delivering the abrasive material and with the device scaled on Mohs standard hardness blocks, small surfaces can be tested by the point abrasion method using ultrasonic impact abrasion technique. The possibility of employing a fine-grained abrasive for this purpose allows substantial miniaturization of measurement, as compared with Mackensen s method. 

Other Transducers. Ultrasound also has been used for the measurement of force, vibration, acceleration, interface location, position changes, differentiation between the composition of differing materials, grain size in metals, and evaluation of stress and strain and elasticity in materials. Sonic devices can used to detect gas leaks, and to count discrete parts by means of an interrupted sound beam. Frequently, an ultrasonic device can be applied where photoelectric derices are used. Particularly tn situations where light-sensitive materials are being processed (hence presence of light must be avoided), ultrasonic devices may be the detectors of choice. 

Chow et al. (2004) reported dynamic video images of the influence of ultrasonic cavitation on the sonocrystallization of ice at a microscopic level. The ultrasonic device was used in combination both with an optical... 

The RE process proceeds in three major types of equipment mixer-settler systems, column extractors, and centrifugal extractors. Countercurrent column extractors can be further subdivided into nonagitated nonproprietary columns and agitated proprietary extractors. Agitating the liquid-liquid system breaks up droplets and increases the interfacial area to improve the mass transfer and column efficiency. Various forms of energy input are used, e.g., rotation of propellers, impellers, and discs pulsation, vibration, and ultrasonic devices and centrifugal devices. 

The wet chemical methods are summarized in Table IV. Basically this approach centers on the water-soluble extract obtained from Alter substrates, impactor plates, or other collection surfaces. The extraction process has to be done with some care to ensure that all of the water-soluble material is removed. Standard extraction methods now involve the use of ultrasonic devices to maximize extraction efficiency. Once the extract is obtained, it can be subjected to a number of the methods listed in Table IV, such that a detailed elemental breakdown by inorganic and (water-soluble) organic carbon is accomplished. 

Using a solution-spray technique,124 an aqueous solution of HAuCU and titanium tetrachloride was atomised by an ultrasonic device to produce a mist without separation of the components this was then calcined, and the fine particles collected on a glass filter at the outlet. Samples of 1 wt.% Au/TiC>2 contained 4 nm particles when the spray reaction temperature was... 

Two different types of ultrasonic devices are used in laboratories ultrasonic bath and ultrasonic probe. However, as a result of inhomogeneity of ultrasonic energy distribution in the whole solution and a decrease in power with time, the repeatability and reproducibility of experimental conditions for ultrasonic baths is often unsatisfactory. With ultrasonic probes the energy is focused on a small sample area, which significantly improves cavitation efficiency and, thereby, extraction effectiveness [56]. 

Ultrasonic devices operating in the air are subject to minimal pressure, so they require minimal power to maintain the amplitude. 

Except in some special cases where the users themselves have designed and produced their own ultrasonic devices, US equipment for leaching consists of commercial ultrasonic baths or probes. 

Except for a few laboratory-made units and some devices marketed by other firms, most applications of ultrasonic nebulization (USNn) in atomic spectrometry have been developed with two commeroial devioes from CETAC Technologies viz. the U-5000AT+ and U-6000AT+). It should be noted that these two commercial ultrasonic devices were originally designed for ICP instruments but have been used with other types of detectors [20]. 

Laser ultrasonic transducers are truly non-contact devices which effectively avoid acoustic coupling problems (e.g. damping in the transducer and couplant reflection and transmission losses at the interface). Most laser ultrasonic devices have been used for excitation and detection of bulk elastic waves in point source or planar geometry, but also surface acoustic (Rayleigh or Brillouin) waves. Unlike the bulk wave regime, only one sample side is needed for excitation and detection when surface waves are used. This not only renders the measurements easier, but also avoids the need for an accurate knowledge and uniformity of the sample thickness. In addition, the excitation laser can be focused using cylindrical lenses in order to obtain an excitation line. 

It is often difficult to compare the sonochemical results reported from different laboratories (the reproducibility problem in sonochemistry). The sonochemical power irradiated into the reaction system can be different for different instruments. Several methods are available to estimate the amount of ultrasonic power entered into a sonochemical reaction, the most common being calorimetry. This experiment involves measurement of the initial rate of a temperature rise produced when a system is irradiated by power ultrasound. It has been shown that calorimetric methods combined with the Weissler reaction can be used to standardize the ultrasonic power of individual ultrasonic devices. ... 

This may be either a continuous process, used when the sample size is relatively large (1 ml or more), or a discrete process, used with samples of less than 20 /il. Continuous-flow systems are simpler to use and more precise, but they are less sensitive. They employ a nebulizer in association with a flame or gas plasma, and either a rotating electrode (Rotrode) or drip-feed to the electrode with the arc or spark. The pneumatic nebulizer has an efficiency of 5-10% and generates an inhomogeneous aerosol. Efiiciency can be improved by proper design of the nebulizer and spray chamber (N4), by use of heated nebulizer gas (R6) or ultrasonic devices (S23). The maximum improvement is a 5- to 10-fold increase in sensitivity. There is also an increase in the complexity and cost of the instrument which usually offsets these benefits. The effect... 

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