Electric transducers

Flow meters have traditionally been classified as either electrical or mechanical depending on the nature of the output signal, power requirements, or both. However, improvement in electrical transducer technology has blurred the distinction between these categories. Many flow meters previously classified as mechanical are now used with electrical transducers. Some common examples are the electrical shaft encoders on positive displacement meters, the electrical (strain) sensing of differential pressure, and the ultrasonic sensing of weir or flume levels. 

Figure 1. Implantation of electrons in polytetrafluoroethylene films to form electric transducer of high stability and sensitivity.

Since optical techniques could not be used to study events occurring within the opaque layers of liquid expls, a new method needed to be employed. A device called an electric transducer (a converter of electrical energy from one system to another, such as a transformer) was used by Travis in... 

Electrical Transducer Studies of Initiation of Liquid Explosives. See Vol 4, p D339-R,... 

Electrical transducer studies of initiation of liq expls 4 D339... 

It is interesting to consider hardness as an example of how mechanical tests for rubber have, or have not developed. Firstly, despite the very imprecise relationship with modulus and the lack of any fundamental significance, hardness measurements have continued to be used and even now new ones are being introduced. The far more sensible method of measuring force to produce a given deformation, which would also allow stress relaxation to be conveniently measured, has not been adopted. However, the instrumentation has been updated so that the old measure can be made with electrical transducers and fed directly to a computer. On the other hand, perhaps the fact that hardness is a non-destructive method that can be applied to virtually any product is justification that it should thrive. 

Optoelectronic—Pertaining to a device that responds to optical power, emits or modifies optical radiation, or utilizes optical radiation for its internal operation. Any device that functions as an electncal-to-optical or oplical-to-electrical transducer. 

Table III is a summary presentation of the CCD image sensor products of various companies in Japan, while Figure 8 shows the change in numbers of elements for photo-electric transducers. In the background of this change there was a great improvement in the clarity of pictures in home video systems (the photo-sensor for surface recognition of course was not developed exclusively for these measurements but was adapted from the general type).

Figure 8 Change in number of elements for photo-electric transducers...

Among the various techniques of measurement one may be indicated as the most versatile the immersion technique (see Hartmann and Jarzynski, 1974 Hartmann, 1980). In this method acoustic waves are generated and received by two piezo-electric transducers, one acting as transmitter, the other as receiver the transducer material is... 

Tension Control Roil These type rolls provide the important function of material tension control. There is a proportional relationship between winding tension and lay-on-roll forces (eliminating areas were bumps, valleys, unwanted stretch, etc. develop). There are various tension control techniques available. The proper selection involves decisions on how to produce the tension, how to sense the tension, and how to control the tension. For instance, if the material has a very low tension requirement and if exact control is required, then perhaps, using a magnetic particle brake with an electrical transducer roll with appropriate electronic control is best. However, if the material is on large diameter rolls and moves at slow speed, then a roll follower system can be used effectively. 

The principles of UVP, or its special variant CVP, in which we are now interested, and ESA have been introduced in sec. 4.3e. Under discussion is now how the measurements are carried out in practice. As a consequence of the relatively complicated experiments. Involving wave generation (acoustic or electric), transducers, response analysis, etc., measurements are mostly done with commercial apparatus, including a lot of electronics and software. Some of these apparatus allow for additional options, such as measuring the particle size distribution, conductivity or titrating the sample to change the surface charge. 

A more detailed study of the sequence of transition to the onset of spouting has been reported by Volpicelli and Raso (Vl), who carried out instantaneous pressure measurements with an electric transducer near the base of the bed at varying gas flow rates in a tw o-dimensional column. They also recorded the development of the internal spout and the particle trajectories with a motion-picture camera. The average pressure, together with records of instantaneous pressures published by these workers, are reproduced in Fig. 6. Their results broadly confirm the mechanism already described (Figures 4 and 5), and provide the following additional information ... 

In thermomechanical analysis (TMA) the deformation of the sample under stress is monitored against time or temperature while the temperature increases or decreases proportionally to time. Changes are detected by mechanical, optical, or electrical transducers. The stress may be a compression, penetration, tension, flexure, or torsion. Generally the instruments are also able to measure the sample dimensions, a technique called thermodilatometry. The stress F/A) expressed in N/m or Pa may be a normal tensile stress cr, a tangential shearing stress x, or a pressure change Ap the force applied is F and A is the area. 

Many questions pertaining to membrane processes in general and ligand/membrane receptor interactions in particular can be addressed by a novel model membrane system, i.e., polymer-supported or polymer-tethered lipid bilayers [12,14], The basic structural unit for this sensor platform is the tethered lipid bilayer membrane [16] displayed in Fig. 2D. The essential architectural elements of this supramolecular assembly include the solid support, e.g., an optical or electrical transducer (device), the polymeric tether system which provides the partial covalent and, hence, very stable attachment of the whole membrane to the substrate surface, and the fluid lipid bilayer, functionalized if needed by embedded proteins. 

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