4.1. Principle of Operation
Ultrasonic sensors are devices deployed to convert electrical energy into mechanical energy. Ultrasonic waves are longitudinal waves which move as a series of compressions and rarefactions across the direction of wave propagation through the medium [37]. In addition to distance measurement, they are also utilised in ultrasonic material testing to detect; air bubbles, cracks, and other defects in products, detection of object and position, ultrasonic mouse, etc [37].
Ultrasonic sound waves are mechanical vibrations that display all of the same features as audible sound waves, only they operate at higher frequencies. Audible sound wave frequencies range between 20 Hz to 20 kHz. In contrast ultrasonic waves range from 20 kHz to 800 MHz, Generally, ultrasonic waves that are used for the testing of materials range from around 0.5 MHz to 20 MHz [38]. Ultrasonic waves are transferred via vibrating particles; therefore, ultrasonic waves require a transmission medium whether it is solid, liquid, or gas along which to propagate [3].
The velocity of sound is not constant, but, it alters in dissimilar media and also in the same medium at different temperature. For instance, it is estimated to be roughly around 331.9272 meters per second at 0°C in air medium; however, it increased to around 344.4240 meters per second at 20°C in the same air medium, or an increase of around 0.6248 meters per second for every centigrade degree rise in temperature [39]. Sound
Ultrasonic sensors emit short, high-frequency sound pulses at regular intervals. These propagate in the air at the velocity of sound. If they strike an object, then they are reflected back as echo signals to the sensor, which itself computes the distance to the target based on the time-span between emitting the signal and receiving the echo.
The purpose of this experiment is to measure the speed of sound in air and to determine the effects of frequency on the speed of sound.
P=P_1 +C_p*(V-V_0 ) [9] where P and P1 are the measured and atmospheric pressures in psia, Cp is the calibration constant in psia/volts, V is the transducer voltage, and V0 is the offset voltage. RESULTS AND DISCUSSION To convert the measured voltages to pressures, we first determined the calibration constants of transducers 2 and 3 for each of the trials ranging from 6 to 14 psig. To do this, we calculated the measured shock wave velocity for each trial by dividing the distance between transducers 2 and 3 (0.548 m) by the measured time difference between the peak measured voltages. Next, assuming T = 70° F and γ = 1.4 (for air), we calculated the speed of sound and Mach number using equations 2 and 3.
Detects different physical characteristics of pressure waves: • Pitch: perception of the frequency of sound waves (umber of wavelengths that pass a fixed point in a unit of time) • Loudness: the perception of the intensity of sound (the pressure exerted by sound
A sound wave is a disturbance that repeats regularly in space and time and that transmits energy from one place to another with no transfer of matter. In Activity 2 on page 8 we had to model sound waves using an instrument. In our class we used a flute as the example and when the person blew into it, sound waves were produced. As they blew and changed the volume and pitch the sound waves changed. A sound wave is created when something vibrates. When something vibrates, longitudinal waves are created which we can hear. A longitudinal wave is a wave that transfers energy through compressions and rarefactions in the material that the wave travels which are all parts of a sound wave. In Activity 2 it states in some parts of the wave, the air molecules
Ultrasound relies on high frequency sounds to image the body and diagnose patients. Ultrasounds are therefore longitudinal waves which cause particles to oscillate back and forth and produce a series of compressions and rarefactions
Sound is usually something that people usually take as something simple. However, sound can be a very complicated topic. Sound is a wave of vibration (called a longitudinal wave) caused by a release of energy.
Sound waves are nothing more than an energy transfer through a medium be it through a liquid, solid, or a gas. Sound pressure or intensity is measured on logarithmic scale in decibels dB which increases on an order of magnitude. For instance a quiet conversation would be around 30 dB and whereas the human pain threshold would be just over 100 dB. While the pitch or frequency of the sound is measured in hertz or Hz, the higher the hertz the higher the pitch of the sound and vice versa (Hildebrand, 2004).
Sound is a wave, and a wave can be remembered as a medium, carrying energy from one point to another. The sound wave has a resemblance of a slinky in its nature, for many reasons. The disturbance goes from one place to another, carried by the medium. Typically, the medium will carry energy through the air, although it could be any substance like water and steel. There is an original source of the wave; anything from someone’s vibrating vocal chords, or a tuning fork. Then, the sound is transported through the medium through particle-to-particle interaction. If the sound wave is moving through the
These averages we determined from the trials can be compared to the accepted speed of sound (344.2 m/s in this specific temperature), and we determine the relative error percentages:
Diagnostic medical sonography is a profession where sonographers direct high-frequency sound waves into a patient’s body through the use of specific equipment to diagnose or monitor a patient’s medical condition. As described by the Bureau of Labor Statistics, this examination is referred to as an ultrasound, sonogram, or echocardiogram. The high-frequency sound waves emitted from the handheld device, called a transducer, bounce back creating an echo and therefore produce an image that can be viewed on the sonographers computer screen. This image provides the sonographer and physician with an internal image of the patient’s body that will be used in the diagnosis. The most familiar use of ultrasound is used in monitoring pregnancies
According to Gill (2012,p. 11) the equation for Acoustic impedance is Z=ρc, where (Z=Acoustic impedance, ρ =density of medium and c =velocity of beam). From this equation is understood that acoustic
The sound waves are produced by a random oscillating crystal, and are inaudible to humans. A instrument called a
Ultrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves. It is a high pitch frequency that cannot be heard by the human ear. In ultra sound the following happens: High frequency sound pulses (1-5megahertz) are transmitted from the ultrasound machine into your body using a probe. The sound wave will travel into your body until it hits an object such as soft tissue and bone. When the sound wave hits these objects some of the wave will be reflected back to the probe. While some waves may carry on further till they hit another object and then reflected back. The probe picks up these reflected sound waves and relays them to the machine. The distance and time from the probe,
Among the methods used for cell disruption, sonication (ultrasonics) is one of the most widely used cell disruption technique at laboratory scale. Ultrasound technology has been applied to various fields (Wang et al. 1997). On one hand it is hardly suitable for the industrial purpose, but on the other hand, it requires neither sophisticated devices nor extensive technical training at laboratory (Feliu et al. 1998).