Apparatus transducers

Titanium IV) oxide, T1O2. See titanium dioxide. Dissolves in concentrated alkali hydroxides to give titanates. Mixed metal oxides, many of commercial importance, are formed by TiOj. CaTiOj is perovskite. BaTiOa, per-ovskite related structure, is piezoelectric and is used in transducers in ultrasonic apparatus and gramophone pickups and also as a polishing compound. Other mixed oxides have the il-menite structure (e.g. FeTiOj) and the spinel structure (e.g. MgjTiO ). 

The experimental activity was carried out on a cylindrical pressure vessel whose capacity is 50 litres and made from steel 3 mm thick. Fig. 2 shows the layout of the pressure vessel considered. The pressure vessel was connected to an oil hydraulics apparatus providing a cyclical pressure change of arbitrary amplitude and frequency (fig.3). Furthermore the vessel was equipped with a pressure transducer and some rosetta strain gauges to measure the stresses on the shell and heads. A layout of the rosetta strain gauges locations is shown in fig.4. 

A major advance in force measurement was the development by Tabor, Win-terton and Israelachvili of a surface force apparatus (SFA) involving crossed cylinders coated with molecularly smooth cleaved mica sheets [11, 28]. A current version of an apparatus is shown in Fig. VI-4 from Ref. 29. The separation between surfaces is measured interferometrically to a precision of 0.1 nm the surfaces are driven together with piezoelectric transducers. The combination of a stiff double-cantilever spring with one of a number of measuring leaf springs provides force resolution down to 10 dyn (10 N). Since its development, several groups have used the SFA to measure the retarded and unretarded dispersion forces, electrostatic repulsions in a variety of electrolytes, structural and solvation forces (see below), and numerous studies of polymeric and biological systems. 

Other, similar methods for measuring surface-surface interactions, which come under the generic heading of surface force apparatus, include the crossed-filament method. This utilizes a beam deflection technique similar to that now being used in some AFMs for the measurement of surface displacement [94]. Another technique for displacement measurement used in a similar SFA is that of a capacitance transducer. Both techniques suffer the criticism that separation is not measured at the point of interest, i.e., the gap between the two surfaces as measured in the FECO technique. 

A commercially available ultrasonic cleaner was used for the prqjaration of nickel powders from nickel salt in aqueous solution. This cleaner, Model 3210 (Branson Ultrasonic Corp., CT), is normally used as a cleaning apparatus, working at a frequency of 47 kHz with e power of 130 W that consists of a stainless-steel bath of 5.17 1 capacity and has an ultrasonic transducer attached to the bottom of the bath. A liquid solution temperature in the bath can be varied from room temperature to maximum of 80 °C. 

The core - flood apparatus is illustrated in Figure 1. The system consists of two positive displacement pumps with their respective metering controls which are connected through 1/8 inch stainless steel tubing to a cross joint and subsequently to the inlet end of a coreholder 35 cm. long and 4 cm. in diameter. Online filters of 7 im size were used to filter the polymer and brine solutions. A bypass line was used to inject a slug of surfactant solution. Two Validyne pressure transducers with appropriate capacity diaphragms are connected to the system. One of these measured differential pressure between the two pressure taps located about one centimeter from either end of the coreholder, and the other recorded the total pressure drop across the core and was directly connected to the inlet line. A two - channel linear strip chart recorder provided a continuous trace of the pressures. An automatic fraction collector was used to collect the effluent fluids. 

Apparatus. A constant rate displacement pump charged with mercury was used to displace the fluid of interest from steel cylinders to the core. A pressure transducer connected to the chart recorder provided the pressure history of each core flood. An automatic sampler with... 

Using the dilatometer technique, a small sample of powder (about 1 -2 grams) is heated at constant rate in the apparatus depicted schematically in Fig. 43. Dilatation of the sample is measured by a linear voltage transducer (LVDT) contraction of the sample indicates particle-particle surface flattening and defines the minimum softening point ox sintering temperature, Ts. In... 

The experimental design for the photoacoustic experiment is relatively simple. The apparatus is quite similar to that employed for nanosecond absorption spectroscopy with the major difference being that a piezoelectric transducer is used to monitor the acoustic waves rather than a photomultiplier tube to analyze the incident light. A representative schematic for PAC is shown in Fig. 2. 

The practising chemist has four types of laboratory ultrasonic apparatus which are commercially available. One of these, the whistle reactor, relies on mechanical generation of ultrasonic power whereas the other three - the bath, probe and cup-horn systems - are driven by electromechanical transducers. The construction of such systems is discussed below and a summary of their relative advantages (and disadvantages) in sonochemical usage are summarised in Tab. 7.1. 

Fig. 1.31 Scheme of Sieverts-type apparatus where T transducer, hydrogen cut-off valve, argon cut off valve, vacuum system cut-off valve, reactor cut-off valve, calibrated volume and its cut-off valve, V vent valve, R reactor... 

Calibration process consists of a few steps. At first we have to obtain advisable pressnre (usually about 10 atm) of argon in a calibrated volnme and atmospheric pressure in the rest of the system (reactor and connections). Then by opening calibrated volume cut-off valve and by pressnre rednction to the value the total volume of the system for the apparatus with the relative transducer can be calculated using the formula ... 

Figure 6. Diagram of our 1-atm ion mobility spectrometer (IMS) apparatus (a) stainless steel source gas dilution volume, (b) septum inlet, (c) needle valve, (d) Nj source gas supply, (e) source and drift gas exhaust, (f) flow meter, (g) pressure transducer, (h) insulated box, (i) drift tube, (j) ion source, (k) Bradbury-Nielson gate, (I) Faraday plate/MS aperture, (m) drift gas inlet, (n) universal joint, (o) electrostatic lens element, (p) quadrupole mass filter, (q) 6"-diffusion pump, (r) first vacuum envelope, (s) channeltron electron multiplier, (t) second vacuum envelope, (u) 3"-dif-fusion pump, (v) Nj drift gas, (w) leak valve, (x) on/off valves, (y) fused silica capillary, (z) 4-liter stainless steel dilution volume, (aa) Nj gas supply.

The displacement of the center part of the cover glass is continuously monitored by a displacement transducer. The actual measurements were performed using a modified thermo-mechanical system (TMS), a Perkin Elmer TMS-2 apparatus. 

Small pressure transducers with flush-mounted diaphragms are commercially available for the measurement of either steady or fluctuating pressures up to 100 MPa (about 15,000 Ibftin ). The metallic diaphragms are as small as 4.8 mm (%6 in) in diameter. The transducer is mounted on the apparatus containing the fluid whose pressure is to be measured so that the diaphragm is flush with the inner surface of the apparatus. Deflection of the diaphragm is measured by unbonded strain gauges and recorded electrically. 

Apparatus. A conventional static vacuum apparatus was used. Reactants were introduced into cylindrical borosilicate glass reaction vessels (250-ml. capacity) suspended in a furnace maintained at a temperature within 0.1°C. Pressure measurements were made by a transducer (Consolidated Electrodynamics) linked to a recorder (RE 511 Servo-scribe). 

The experimental apparatus employed was described elsewhere ( ). Briefly, surface pressures were determined continuously from surface tension measurements using a sand blasted platinum blade, suspended from a transducer-amplifier (Sandborn, model 311A). The transducer signal was fed to a X-Y recorder. Surface potential was measured with an electrometer (Kelthly, model 610B) using an air electrode coated with Ra and an Ag/AgCl electrode in the subsolution. 

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