What is Ultrasonic

Ultrasonic Sound
The term "ultrasonic" applied to sound refers to anything above the frequencies of audible sound, and nominally includes anything over 20,000 Hz. Frequencies used for medical diagnostic ultrasound scans extend to 10 MHz and beyond.
Sounds in the range 20-100kHz are commonly used for communication and navigation by bats, dolphins, and some other species. Much higher frequencies, in the range 1-20 MHz, are used for medical ultrasound. Such sounds are produced by ultrasonic transducers. A wide variety of medical diagnostic applications use both the echo time and the Doppler shift of the reflected sounds to measure the distance to internal organs and structures and the speed of movement of those structures. Typical is the echocardiogram, in which a moving image of the heart's action is produced in video form with false colors to indicate the speed and direction of blood flow and heart valve movements. Ultrasound imaging near the surface of the body is capable of resolutions less than a millimeter. The resolution decreases with the depth of penetration since lower frequencies must be used (the attenuation of the waves in tissue goes up with increasing frequency.) The use of longer wavelengths implies lower resolution since the maximum resolution of any imaging process is proportional to the wavelength of the imaging wave.

Neutron Imaging

The field of neutron imaging has a broad scope of applications and has played a pivotal role in visualizing and quantifying hydrogenous masses in metallic matrices. The field continues to expand into new applications with the installation of new neutron imaging facilities, the investigation of new imaging techniques and developments in neutron detector technology. Some of the main topics to be discussed are:

• new neutron imaging facilities
• detector development
• phase, stroboscopic, and other novel imaging techniques
• imaging for the hydrogen economy
• industrial imaging applications
• tomography and image reconstruction/analysis methods
• security applications
• fast neutron radiography
• miscellaneous

Eddy-Current Inspection

In order to monitor on-line blade steel quality, MPI has developed high-speed, on-line process control eddy current capabilities to determine three major parameters: hardness, percentage of retained austenite, and impact (toughness) in its manufacturing lines.
New sensor development
Since commercial probes introduce a number of engineering problems, chief among them proximity effects and lift-off measurement errors, a special purpose sensor was developed to overcome these difficulties. A newly constructed encircling coil on a carbide former was found to be insensitive to small random motions of the steel blade due to the relative uniform field within the cross section. In addition, side effect and lift-off measurement errors were virtually eliminated, therefore enabling high-speed, on-line testing. Based on the industrial requirement of monitoring the ambient temperature, a thermocouple was also embedded in the coil former with a protective sheath.
Generic dynamic eddy current testing system
The system interface developed by MPI is completely automated. It is comprised of two eddy current sensors with integrated thermocouples. The thermocouples are directly connected to a standard data acquisition board that is connected to the PC via a serial interface. For the custom-built sensors, shielded cables are utilized to connect to impedance analyzers that in turn are connected to the PC via a fast GPIB interface. Within the PC an appropriate Graphical User Interface (GUI) will allow the operator to determine the impedance calibrated retained austenite value in conjunction with the coil temperature. In addition to the on-line display of the RA and temperature, a software algorithm stores the recorded information for further off-line data processing and statistical analysis.