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Civil Infrastructure controls the way people live by providing safe passage and shelter across the entire globe. Since safety leads the concern in infrastructure, it is essential to ensure that these structures have been adequately tested and analyzed periodically. Testing these structures can be extremely expensive when parts are required to be removed to capture the flaw, which is why nondestructive testing (NDT) continues to grow in demand since it can evaluate the structural component in-situ without causing any damage. Ultrasonic testing (UT) helps to adequately sustain and advance the safety in existing and future infrastructure across the globe. Continual advancement and use of UT methods for the application of condition assessment in the field of civil infrastructure can provide a cheaper alternative to other conventional practices. This report focuses on the UT methods of NDT and aims to provide an in-depth literature review of the different testing styles. Ultrasonic Pulse Velocity, Ultrasonic Pulse Echo, Semi-direct and Indirect testing, Time of flight Diffraction, Phased Array ultrasonic testing, are some of the NDT methods commonly used and discussed in the report. These techniques are routinely being applied to the condition assessment of concrete, steel, and timber structural members including the assessment of debonding between rebar cage and surrounding concrete in reinforced concrete structural members. With the techniques already established, the goals of the NDT industry are to make the techniques safer, cost effective, and modifying the systems to integrate a more accessible process.

Optical 3D imagers for gesture recognition, such as Microsoft Kinect, suffer from large size and high power consumption. Their performance depends on ambient illumination and they generally cannot operate in sunlight. These factors have prevented widespread adoption of gesture interfaces in energy- and volume-limited environments such as tablets and smartphones. Gesture recognition using sound is an attractive candidate to overcome these difficulties because of the potential for chip-scale solution size, low power consumption, and ambient light insensitivity.Our research focuses on building a 3D ultrasonic rangefinder system using batch-fabricated micromachined aluminum nitride (AlN) ultrasonic transducer arrays and custom CMOS electronics. The system uses pulse-echo time-of-flight to localize targets from their echoes. We use millimeter--wave ultrasound, which enables compact ultrasonic arrays which can measure range and direction to a target. The relatively slow speed of sound allows the use of low--speed, low-power readout electronics.In this dissertation, we will present the design methodology for a prototype ultrasonic rangefinder system. We will show how the choice of basic system specifications affects the mechanical transducer design and the interface circuit design. We will present a physics-based model of an ultrasound transducer which accurately predicts device operation. We will present measured results from an ultrasonic 3D gesture recognition system which uses an array of AlN MEMS transducers and custom readout electronics to localize targets over a ±45° field of view up to 1m away. The 0.18μm CMOS readout ASIC comprises 10 independent channels with separate high voltage transmitters, readout amplifiers, and ADCs. Power dissipation is 400μW at 30fps, and scales to 5μW/ch at 10fps.