One of the great challenges in the processing of materials using Equal Channel Angular Pressing (ECAP) is the high forming forces required to produce large shear deformation in the material. Researchers show that the friction forces between the die and the sample constitute a great part of the total forming forces. Recently, ultrasonic vibrations are successfully implemented into the ECAP proce...

In ultrasonic tube hydroforming, the tube is hydro formed while the ultrasonic vibration is applied to the die. Prior studies provide experimental proof that ultrasonic tube hydroforming reduces corner radius, improves lubrication and uniform thickness. Use of ultrasonic vibration can decrease friction at the tube-die interface. Few attempts have been made to analyze the wire drawing while the ...

This paper reviews recent developments of micro ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, four ultrasonic motors recently developed at Penn State University are introduced; windmill, PZT tube, metal tube, and shear-type motors. Driving principles and motor characteristics are described in comparison with the conventional ultrasonic mo...

We have constructed an atomic force microscope enabling one to image the topography of a sample, and to monitor simultaneously ultrasonic surface vibrations in the MHz range. For detection of the distribution of the ultrasonic vibration amplitude, a part of the position-sensing light beam reflected from the cantilever is directed to an external knife-edge detector. Acoustic images taken on the ...

Micro-forming is a miniaturization technology with great potential for high productivity. Some technical challenges, however, need to be addressed before micro-forming becomes a commercially viable manufacturing process. These challenges include severe tribological conditions, difficulty in achieving desired tolerances, and short tool-life due to inability of available die materials to withstan...

BACKGROUND A diastolic coronary flow murmur has been reported for patients with coronary stenoses, yet is rarely appreciated during routine auscultation. We hypothesized that an ultrasonic Doppler method can detect the epicardial vibrations associated with this murmur. Ultrasonic Doppler vibrometry is a pulsed wave echocardiography phase demodulation technique designed for detecting vibrations....

In this paper, a new non-contact ultrasonic abrasive finishing mechanism is designed and fabricated. This mechanism combines the function of ultrasonic vibrations and the magnetic abrasive finishing (MAF) process. A permanent magnet which is mounted on a horn has been used as the processing tool. This polishing tool is vibrated at an ultrasonic frequency with piezo-electric actuators. Ultrasoni...

The effects of ultrasonic treatment (UST) on the solidification microstructure of a 35CrMo steel cast ingot were investigated. To avoid the erosion of a high-temperature melt, a T-shaped ultrasonic waveguide unit was used to introduce ultrasonic vibrations into a 35CrMo steel die casting melt. The experimental results show that the microstructure of the ingot was refined by ultrasonic treatment...

Mobile devices can be protected by a variety of information flow control systems. These systems can prevent Trojans from leaking secrets over network connections. As mobile devices become more secure, attackers will begin to use unconventional methods for exfiltrating data. We propose two sound-based covert channels, ultrasonic and isolated sound. Speakers on mobile devices can produce frequenc...