Doppler effect is the difference in frequency between the wave transmitted or wave that leaves a source and the wave received or wave that reach the receiver due to the relative motion of source and receiver, while sound reflection is the reflection of the sound when it hits the surface of an object. These two, the Doppler effect and sound reflection, are some of the concepts that the SODAR instrument used.
SODAR is an acronym for Sound Detection and Ranging which is an instrument that used sound waves to investigate the lower atmosphere. It is generally used as a wind profiler which measures the wind speed, the wind direction, and the vertical wind speed at various heights above the ground. It is also called acoustic echo sounders (AES), echo sounder, and acoustic radar.
SODAR produces sound waves directly above the atmosphere at different angles. As the sound wave travels, the sound wave attenuates by the temperature and humidity in the atmosphere. When the sound
wave hit wind turbulence in the atmosphere, the sound wave is reflected. The reflected sound wave, which now has different intensity and frequency, goes back to SODAR.
The received sound wave is then compared to the transmitted sound wave and the following were acquired:
- Time delay or the time the sound wave travels
- Intensity difference or the difference in amplitude of the wave
- Doppler shift or the difference in wave frequency
Turbulent strength is acquired using the intensity difference, height using the time delay and sound speed, wind speed using the Doppler shift or the frequency difference, and wind direction using the sound
wave received in different angles.
SODAR used remote sensing for air observation. It is a much smaller instrument compared to meteorological towers, so it is easy to install and collect data. Although it is smaller, it shows a very good correlation both in wind speed and wind direction to the meteorological towers. It is now used in many applications such as:
- .Meteorological Monitoring
- Wind Power Generation
- Airport Low Altitude Wind Monitoring
- Wind Resource Assessment and Measurement
- Meteorological Research
Piezo Source is the leading supplier to the lower atmosphere meteorology industry. Our speakers are used as both transmitters and receivers in SODAR instruments including echo sounders and acoustic
Boundary Layer (Atmospheric) And Air Pollution: Observational Techniques
Detection and Ranging (SODAR) Wind Profiler Instrument Handbook
Comparison of Second Wind Triton Data with Meteorological Tower Measurements
Medical Device Applications
Due to the properties of piezoelectric materials, it is used on different medical applications. In diagnostic medical equipment, it’s been used magnetic resonance elastography (MRE) which is a noninvasive imaging technology that uses magnetic field and sound waves to produce a detailed images of organs and tissues composition in the body. It operates the same as magnetic resonance imaging (MRI)
but with the combination of sound waves. A pad is placed on the skin which will send sound wave to the body and receive it after it travels through the body. The speed of the sound waves shows the stiff tissues
because sound waves travel faster on stiffer tissues. It is been used for liver diseases and tumors of different body parts.
Piezoelectric materials are also used to monitor many bodily signals. Since it converts mechanical energy into electrical signal, it is used on pressure changes within the body such as blood pressure, intraocular pressure, and cranial pressure. Aside from this two, the following are piezoelectric materials
application on medical devices:
- Ultrasound scanners
- Ultrasonic surgery instruments
- Ultrasonic dental scalers
- Energy harvesting
- Cochlear implants
Piezo Source provides products that provide the basis for the audio systems in MRI/MRE systems where the non-ferrous/nonmagnetic mature of the piezoelectric speakers provides zero interference with
Imaging Tumour Stiffness Could Help Enhance Treatment for Breast and Pancreatic Cancer
Piezoelectric Materials for Medical Applications https://www.intechopen.com/chapters/61340
When two waves have the same frequency and phase and interacted, they will combine and producea stronger wave which process is called constructive interference. Since sound is a wave, this process can also be applied to speakers. The produced sound wave due to constructive interference has a higher amplitude and intensity than the former two waves. And when two sounds are out of phase, they will cancel each other producing lesser waves which process is called destructive interference. The produced sound wave due to destructive interference have lower amplitude and intensity. Constructive and destructive interference is the main principles that LRAD used for creating a directional very loud sound.
LRAD or Long-Range Acoustic Device is a device that American Technology Corporation developed as a substitute and discourages in use of lethal force in US military ships. It is also called an acoustic hailing device (AHD) and sound canon.
LRAD uses piezoelectric transducers to produce sound in a speaker. Many piezoelectric speakers are then aligned in an array and connected to an electrical power source. The power source applies electrical current to the transducers which will then each create sound waves. Identical sound waves, having the same phase and frequency, are then produced in the array of transducers. Due to constructive interference, the sound wave produced has a higher amplitude that helps LRAD have powerful sounds.
Applications of piezoelectric materials on automotive technology are actuators, fuel injectors, sensors, and variety of safety systems on automobiles, aircrafts, trains, and ships. An actuator converts electrical signal into mechanical movement which is the most important property of the piezoelectric materials. It is used on adjusting mirrors, lenses and other automotive parts. It is maintenance-free and durable that can be operated many times.
Piezoelectric materials are important for power generation in automobiles since significant amount of energy is wasted in automobile motion. Although it only produces small amount of electrical energy, it is
sufficient enough to power sensors and other small, low-energy consumption gadget. An example of this are benders made of PZT which attached to the tire. The PZT benders then supply electrical energy to tire-pressure sensors that operate periodically.
Piezo Source is utilized in different applications for automotive technology. It is compact, simple and highly reliable as it provides a promising solution.
Piezoelectric Automotive Devices https://www.americanpiezo.com/markets/automotive.html
Application of Piezoelectric Technology in Automotive Systems