This report introduces an approach to recognize hand gestures by utilizing the Doppler effect of ultrasonic soundwaves. I use a microphone array as the receivers and two speakers as the transmitters to generate ultrasonic soundwaves. Gestures are characterized through the Doppler frequency shift they generate in reflections of the soundwaves. I then apply the artificial neural network algorithm...

The acoustical cross-talk in row-column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed in the frequency-wavenumber domain. The sources of cross-talk are identified and predicted theoretically. The ne...

This paper raises the design of an ultrasonic array for obstacle detection based on Phased Array (PA) techniques, which steers the acoustic beam through the environment by electronics rather than mechanical means. The transmission of every element in the array has been encoded, according to Code Division for Multiple Access (CDMA), which allows multiple beams to be transmitted simultaneously. A...

Ultrasonic measurements of elastic moduli of composite materials have traditionally been made on either small specimens cut from a iar ger component or by using a scanning technique with the specimen immersed in a water bath. A phase-insensitive array has been developed for rapid nondestructive measurement of in-plane elastic moduli. The array characteristics allow for determinat ion of energy ...

A methodology is presented for health monitoring and subsequent inspection of critical structures. Algorithms have been developed to detect and approximately locate damaged regions by analyzing signals recorded from a permanently mounted, sparse array of transducers. Followup inspections of suspected flaw locations are performed using a dual transducer ultrasonic approach where a permanently mo...

A layer-by-layer deposition method for producing dual-layer ultrasonic transducers from piezoelectric copolymers has been developed. The method uses a combination of customized and standard processing to obtain 2D array transducers with electrical connection of the individual elements routed directly to the rear of the substrate. A numerical model was implemented to study basic parameters effec...

The feeder pipe in the pressurized heavy water reactor (PHWR) is exposed to a possible leakage during operation. Because of the geometrical complexity of the pipe and its inaccessibility due to a high radiation environment, it is difficult to examine the defect by the conventional ultrasonic method. The guided ultrasonic inspection was chosen for the inspection of the pipe. The torsional mode h...

This paper proposes the use of ultrasonic microscale subarrayed MIMO RADARs to estimate the position of breast cancer nodes. The transmit and receive antenna arrays are divided into subarrays. In order to increase the signal diversity each subarray is assigned a different waveform from an orthogonal set. High-frequency ultrasonic transducers are used since a breast is considered to be a superfi...

The increasing use in the industries of composite materials implies finding a suitable way for testing and evaluating them. Non-destructive testing by ultrasounds is an appropriate method to detect defects in this type of materials, however, because of their structure it is required to find the most applicable and accurate process for detecting flaws and anomalies in them. For conventional ultr...

Ultrasonic imaging systems usually require an array of ultrasonic transducers for data acquisition on a wide area on top of an object under investigation. The goal of an imaging algorithm is the use of reflected ultrasound data to form a recognizable image. Conventional algorithms like SAFT are based on an inverse Huygens' principle and need therefore a dense measurement grid. This requires a b...