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A real time empirical mode decomposition (EMD) algorithm based ultrasonic imaging system has been developed for non-destructive testing (NDT) applications. It is difficult to implement the EMD based signal processing algorithm in real time because it is totally a data-driven process which comprises numerous sifting operations. In this paper, the EMD algorithm has been implemented in the visual software environment. The EMD implementation encompasses two types of interpolation methods: piecewise linear interpolation (PLI) and cubic spline interpolation (CSI). The cubic spline tridiagonal matrix has been solved by using the Thomas algorithm for real time processing. The total time complexity functions for both the implemented PLI and CSI based EMD methods have been computed. For the signal filtering, the partial reconstruction algorithm has been adopted. The baseline correction and noise filtering applications have been presented using an EMD based visual software. The real time practicability and the efficiency of this method have been validated through ultrasonic NDT experimentation for improvement in the time domain resolution of the ultrasonic A-scan raw data. The practical results show that in the noisy environment, it is possible to enhance the signal-to-noise ratio for the visualization and identification of ultrasonic pulse-echo signals in real time.

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This paper provides design and development details of the generation of bipolar High Voltage (HV) square wave pulses for the excitation of low frequency ultrasonic transducers. Such a circuit is required for the purpose of ultrasonic inspection of components, particularly where high energy is required to insonify the attenuative medium, such as concrete. A HV (±350 V) square wave pulse has been generated by an ultrafast complementary Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) pair, which is driven by high speed MOSFET drivers. The generated bipolar square wave pulse has been utilized to energize a 108 kHz ultrasonic transducer to operate in the pulse-echo mode for the evaluation of a concrete test block. The receiver amplifier filters the received low-amplitude echo signals, which are reflected back from a discontinuity, and amplifies further for signal to noise ratio enhancement. The pulser board designed has been tested and evaluated for its functionality to measure ultrasonic velocity in the highly attenuative concrete medium up to a depth of 1 m. The measured value of acoustic velocity was compared with the value obtained from the commercially available ultrasonic pulse velocity instrument, and the values obtained are within ±5%.

The novel matrix-based real-time ultrasonic imaging using an ultrasonic camera for immersion application has been proposed in this paper. The proposed ultrasonic camera provides real-time images of mechanical components and the image size is equal to the field of view of the developed matrix-based transducer assembly. For the matrix-based ultrasonic imaging, the addressing-based analog multiplexing scheme has been proposed in such a way that all channels of the specific row are selected simultaneously such as the transducer excitation, data acquisition, data processing and transferring operations are performed concurrently. Similarly, the same operations are performed for remaining all rows sequentially. The developed ultrasonic camera further supports dynamic on-line reconfiguration of the analog front-end hardware, real-time hardware/software-based data processing and data transfer operation. For the experimentation, the entire matrix-based (5 × 5) ultrasonic imaging system for immersion applications has been designed, developed and evaluated in the laboratory. Here we present the performance evaluation of the developed matrix-based ultrasonic camera system by acquiring the real-time images of the water-immersed mechanical objects.

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A water-immersible two-channel high-voltage (HV) spike pulser has been designed, developed, and mounted inside the IP 67 (Ingress Protection 67) grade enclosure, and it is suitable for the ultrasonic Pipe Inspection and Gauging (PIG) system utilized in the petrochemical industry. Such a critical and strategic application requires a portable, miniaturized, and water-immersible water-tight pulser module, which resides inside the pipe carrying water or liquid petrochemicals. The developed spike pulser printed circuit board (PCB) generates a HV negative spike pulse up to −300 V and 100 ns half-amplitude pulse width, required for the energization of ultrasonic immersion transducers of 5–10 MHz frequency. The water-immersible pulser is mounted inside the water-tight IP 67 grade enclosure, and it is operated through an external DC power supply/lithium batteries. The evaluation of the module was carried out using a two-channel water-immersible HV spike pulser, in-house developed preamplifier, and inspection head supported by four sets of spring-loaded Teflon balls for centering, and the inspection head carries two ultrasonic immersion transducers placed 180° apart and a sample SS pipe with a length of 400 mm, Inner Diameter of 200 mm, and Wall Thickness of 9 mm. The two-channel pulser module was evaluated in water to measure the dimensions of the sample SS pipe. This two-channel water-immersible novel spike pulser has dedicated circuitry, and each channel is a standalone PCB and it operates through external LV and HV DC supplies. The module can be scaled up to 256 channels for dimension measurement and flaw detection of long length pipes. In the absence of any literature available on the water-immersible pulser for PIG systems, the present two-channel pulser module has been designed and developed, and the module was evaluated by gauging of the SS pipe from inside. This paper provides the details of the water-immersible HV spike pulser module suitable for the gauging of metallic pipes.