Conical transducer

A NIST (National Institute for Standards and Technology, USA) conical transducer developed (Proctor 1982) has been known as a reference sensor of flat response. Because the sensor consists of a conical element of 1.5 mm truncated-end in diameter bonded to a brass cylinder as illustrated in Fig. 3.7. Comparing with the frequency spectrum in the bonded case in Fig. 3.6, it should have fairly weak peak frequencies in the low frequency range from 100 kHz to 1 MHz and could be of low sensitivity. 

Proctor TM (1982) Some details on the NBS conical transducer. J. Acoustic Emission 1(3) 173-178... 

There are many papers dealing with a solution of this problem. For many years a NIST (National Institute for Standards and Technology) conical transducer developed by Proctor [1982, 1986] out of a Standard Reference Material (SRM) and mass-backed (600 gr.) was used as a reference for AE measurements. Several new approaches have explored other transducer materials out of polyvinylidene fluoride (PVDF) or copolymers (Hamstad 1994 Hamstad and Fortunko 1005 Bar-Cohen et al. 1996 Hamstad 1997) as well as embedded sensors (Glaser et al. 1998). 

Nanosensors for electrochemical detection have been made for years using more traditional fabrication methods, e.g., pulled platinum strings and carbon fibers. Carbon fibers can be purchased with diameters in the low /am range. These can subsequently be etched in an Ar beam until conically shaped tips are produced with tip diameters between 100 and 500 nm [61]. Similarly, a platinum wire can be heated and pulled in order to create tips of similar diameters. Thick film electrodes made by screen printing [62] have also been shown to find application as transducer in microchaimel systems [63]. 

This system represents the ultimate approach to 3D sonographic acquisition. 2D arrays are matrix with a large number of elements arranged in rows and columns that are able, in principle, to have unrestricted scanning in 3D. A volumetric image is produced without moving the transducer such an array generates pyramidal or conical ultrasound pulse... 

Dogan A, Uchino K, Newnham RE (1997) Composite piezoelectric transducer with truncated conical endcaps Cymbal . IEEE Trans UFFC 44 597-605 Elissalde C, Cross LE (1995) Dynamic characteristics of Rainbow ceramics. J Am Ceram Soc 78 2233-2236... 

The CPT device is a probe with a conical tip as shown in Fig. 5. The cone t5 ically has either a 10 cm or 15 cm projected area and a 60° apex angle. A 13.3 cm long friction sleeve is located behind the tip. The disassembled cone, pictured in Fig. 6, shows the tip and friction sleeve separately. The white ring located between the tip and friction sleeve in Fig. 5 is a porous stone which must be saturated prior to the test. A pressure transducer mounted within the probe measures pore water pressure during cone advance and may also be used to monitor excess pore water pressure dissipation when the cone is not advancing in order to estimate soil hydraulic conductivity. 

Historical Seismometer, Fig. 20 Different pendulum settings used for earthquake recording. It is possible to establish a seismograph classification according to the mechanical constitution of the transducer (i) conical or bifilar pendulum, (2) rigid pendulum, (5) Zdllner pendulum, (4) vertical pendulum, (5) torsion pendulum, (6) inverted pendulum, (7) fiexure pendulum, (S) vertical oscillator, (9) vertical rotational oscillator (From Batiio 2004)... 

In most experimental techniques, ultrasonic vibrations are intrcxluced into the liquid from a solid. This is possible either by direct contact of the liquid with the ultrasonic transducer or indirectly by means of a coupling member, the so-called ultrasonic horn. The use of horns avoids the contact of the liquid that is being irradiated with the transducer. If necessary, the intensity can be increase over small volumes by characteristic geometrical forms of the horn. Usually cylindrical, conical, catenoidal or exponential horns are u (5). In the latter case the vibration ami itude increases along the bar inversely with the cone diameter. The dimensions of ultrasonic horns... 

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