Environmental Engineering Reference
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Ultrasonic
pulser
transducer
Ultrasonic
receiver
Pultrude spar
Ultrasonic pulser control
FIGURE 6.9
Ultrasonic.pulser.control.
In.this.approach,.a.reference.intensity.(Iref).at.a.given.reference.pressure.
(Pref).is.divided.by.the.luminescence.intensity.(Ip).at.some.test.condition.(P).
over.the.region.of.interest..The.coeficients.A.and.B.are.intensity.ratio.(Iref/
Ip),.lifetime.(τ),.and.are.then.correlated.with.the.output.of.the.CCD,.provid-
ing. a. convenient. tool. for. the. generation. of. a. spatially. continuous. pressure.
map,.allowing.the.entire.test.surface.to.be.sampled.simultaneously..Current.
CCD.cameras.have.a.million.unequaled.spatial.resolutions..The.output.of.the.
CCD.array.can.be.visually.represented.as.a.two-dimensional.image,.with.the.
luminescence.corresponding.to.a.gray.or.false-color.scale..It.is.more.dificult.
to.use.the.luminescent.light.in.the.water.
Immersion. transducers. are. speciically. designed. to. transmit. ultrasound.
waves.in.a.situation.where.the.test.part.is.partially.or.wholly.immersed.in.
the.water..Typically,.immersion.transducers.are.used.inside.the.water.tank.in.
scanning.applications. 30 .Ultrasonic.pulser.controls.work.automatically.if.the.
pulser.transducer.and.ultrasonic.receiver.are.maintained.at.one.frame.and.
drive.from.one.motor.
In.Figure 6.9,.pos..1.represents.the.controlled.ultrasonic.pulser.transducer.
(for.example,.model.5900.PR.Panametrics.Inc.,.Waltham,.MA)..Pos..1.trans-
ducers.are.used.for.transmitting,.and.pos..2.for.receiving.the.ultrasound.lon-
gitudinal.waves..Pos..3.represents.a.polymer.coating..The.sound.generated.
with.the.frequency.range.from.20.to.250.kHz.and.a.velocity.of.ultrasound.
propagation.c.could.be.determined.as:
.
c.=.λ/T.or.c.=.λf..
(6.36)
where:
λ.is.the.wavelength.of.one.cycle.ultrasound.waves.propagation,.m;
T.is.a.period.of.complete.cycle,.sec;
f.is.the.frequency.of.longitudinal.wave.propagation,.1/sec.
Our.concept.for.experimental.pressure.determination.based.on.empirical.
correlation.is:
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