Transducer measurement

Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0% (complete absorption). All methods of detection, whether the human eye or a modern photoelectric transducer, measure the transmittance of electromagnetic radiation. 

P. G. Dargie, S. T. Hughes. A thick-film capacitive differential pressure transducer. Measurement Science and Technology, 5, 1994, pp. 1216-1220. 

Velocity transducers are electro-mechanical sensors designed to monitor casing, or relative, vibration. Unlike displacement probes, velocity transducers measure the rate of displacement rather than the distance of movement. Velocity is normally expressed in terms of inches per second (ips) peak, which is perhaps the best method of expressing the energy caused by machine vibration. Figure 43.22 is a schematic diagram of a velocity measurement device. 

Three basic types of transducers that can be used for monitoring the mechanical condition of plant machinery displacement probes (measures movement), velocity transducers (measures energy due to velocity), and accelerometers (measures force due to acceleration). Each has specific applications in a monitoring program, while each also has limitations. 

Velocity transducers are an electro-mechanical sensor designed to monitor casing or relative vibration. Unlike the displacement probe, velocity transducers measure the rate of displacement not actual movement. Velocity data is... 

Capacitance probes A capacitometer, used as a transducer, measures the gap capacitance between a plate whose area is small compared to the wave and a grounded conducting surface across which the liquid film flows (Nakanishi et al., 1979). 

An acoustic wave detector, typically a piezoelectric transducer, measures the volume change (see Section HI). This detector is sensitive to the magnitude and the temporal profile of the acoustic wave. As we will see, the amplitude of the wave provides valuable enthalpic information about reactive intermediates, and the temporal profile can reveal the dynamics of these intermediates. 

Thus, it would appear that overpressures experienced in the air from LNG RPTs for spills less than about 30 are not particularly large unless one is very close to the spill site. Overpressures in the water are much larger, as shown in Table X from transducer measurements about 0.7 m from the surface. In fact, in one instance, the overpressure in the water exceeded the critical pressure of the LNG this would not have been expected from the superheated liquid model. 

The dilatometer stem is coaxially enclosed in an open-ended stainless-steel sheath which serves as one plate of a capacitor in a manner similar to the sheath used in the high-pressure porosimeter. When connected to the capacitance bridge of the porosimeter, the filling apparatus, using its own low-pressure transducer, measures the intruded volume and continuously plots the data on an X-Y recorder up to 24 psia. 

If measurements of the shock velocity in water are available at various distances from the charge, one can compute shock pressures at these distances. This approach can be used close to the charge where direct transducer measurements present formidable problems. An exptl arrangement for measuring shock velocity is shown in Fig 16 (Ref 1). Measurements thus obtained are compared with theoretical predictions in Fig 17 (closed circles). Also shown are direct pressure measurements (open circles). 

C, activity coeff. -differential pressure transducer, measured range 20-40°C, Wright et al. 

Amperometric transducers measure the current (flux of electrons) caused by oxidation or reduction of the species of interest when a voltage is applied between the working and the reference electrode. Often, oxygen serves as electron acceptor but interferences have encouraged development of new methods to avoid this, e.g. controlled oxygen supply and the application of mediators, such as ferrocene, e.g. [169]. Other determinations focus on the... 

Potentiometric transducers measure the potential between the sensing element and a reference element. Thus, in contrast to amperometric transducers, practically no mass transport occurs the response depends on the development of the thermodynamic equilibrium. pH changes often correlate with the measured substance because many enzymatic reactions consume or produce protons. 

For primer performance testing, primers are sealed in an air-tight test apparatus and initiated by dropping an 8 or 16 oz steel ball onto the primary explosive. Pressure transducers measure the output (Fig. 1.18c). 

Enzyme sensors can measure analytes that are the substrates of enzymatic reactions. Thermometric sensors can measure the heat produced by the enzyme reaction [31], while optical or electrochemical transducers measure a product produced or cofactor consumed in the reaction. For example, several urea sensors are based on the hydrolysis of urea by urease producing ammonia, which can be detected by an ammonium ion-selective ISE or ISFET [48] or a conductometric device [49]. Amperometric enzyme sensors are based on the measurement of an electroactive product or cofactor [50] an example is the glucose oxidase-based sensor for glucose, the most commercially successful biosensor. Enzymes are incorporated in amperometric sensors in functionalised monolayers [51], entrapped in polymers [52], carbon pastes [53] or zeolites [54]. Other catalytic biological systems such as micro-organisms, abzymes, organelles and tissue slices have also been combined with electrochemical transducers. 

The deflection of the beam was monitored using an inductive displacement gauge (Mahr Pupitron) with a sensitivity of 0.06mmA7. The transducer measured the deflection at the bottom side of the beam, directly under the loading nose main axis. No extra correction for indentation was necessary. 

Potentiometric transducers measure the potential under conditions of constant current. This device can be used to determine the analytical quantity of interest, generally the concentration of a certain analyte. The potential that develops in the electrochemical cell is the result of the free-energy change that would occur if the chemical phenomena were to proceed until the equilibrium condition is satisfied. For electrochemical cells containing an anode and a cathode, the potential difference between the cathode electrode potential and the anode electrode potential is the potential of the electrochemical cell. If the reaction is conducted under standard-state conditions, then this equation allows the calculation of the standard cell potential. When the reaction conditions are not standard state, however, one must use the Nernst equation to determine the cell potential. Physical phenomena that do not involve explicit redox reactions, but whose initial conditions have a non-zero free energy, also will generate a potential. An example of this would be ion-concentration gradients across a semi-permeable membrane this can also be a potentiometric phenomenon and is the basis of measurements that use ion-selective electrodes (ISEs). 

The potential change is proportional to the logarithm of the penicillin concentration. Solid state fluoride or iodide selective electrodes have been employed for the biosensing of glucose or amino acids. These transducers measure the decreasing activity of iodide or fluoride (upon their reaction with the peroxide product). 

Shock-focusing obstacles are placed at different locations downstream from the transition exit 0 mm (1), 51 mm (II), 102 mm (III), and 152 mm (IV). Velocity is measured 407 mm downstream of the transition exit (estimated from pressure transducer measurements at the halfway point between the last two pressure transducers). 

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