In ultrasonic medical imaging, spatial compounding of images is a technique where ultrasonic beam is steered to examine patient tissues in multiple angles. In the conventional ultrasonic diagnostic imaging, the steering of the ultrasonic beam is achieved electronically using the phased array transducer elements. In this paper, a spatial compounding approach is presented where the ultrasonic pro...

The deployment of a wireless sensor network to monitor subjects’ locations and relative distances during psychological experiments is discussed. As its primary function, an overhead array of ultrasound sensors automatically tracks a parent, child and stranger over a 4.45 m×4.23 m observation area. The array of ultrasonic-equipped motes can resolve two point targets separated by at least 73 cm. ...

The sound reproduction in air by using a parametric acoustic array [1] has been reported for a few decades. Two inaudible ultrasonic frequencies are produced from the parametric array. Due to the nonlinearity of air, it is possible to produce an audible frequency with its frequency equal to the difference in the two ultrasonic frequencies. However, there is not much work done in controlling the...

The phenomenon known as mechanical crosstalk from the point of view of its physical nature and the causes of its generation are analyzed. It is also analyzed how it may affect the performance of ultrasonic matrix arrays. This phenomenon occurs primarily in matrix arrays and it is magnified by certain factors causing serious problems in the performance of this type of transducers. This work incl...

Partial discharge (PD) in electrical equipment is one of the major causes of electrical insulation failures. Fast and accurate positioning of PD sources allows timely elimination of insulation faults. In order to improve the accuracy of PD detection, this paper mainly studies the direction of arrival (DOA) estimation of PD ultrasonic signals based on a step-by-step over-complete dictionary. The...

The subsurface defect in the wheel tread caused from Rolling Stock Fatigue (RCF) has become more danger in high speed railway. The conventional UT and phased array UT have deficiency to find the subsurface defect from the tread surface because of limitation of ultrasonic near field. In this paper, the subsurface defect is studied by simulation and experimental results with ultrasonic technique....

We report on the development of transducers for ultrasonic flaw detection which can be permanently mounted at critical locations on structures. We will show that MEMS capacitive diaphragm transducers can be bonded to metal or plexiglas test speciments without damage and that ultrasonic energy can be efficiently coupled into the transducer. It will be demonstrated that transducer arrays can be o...

High contrast and resolution in phased array ultrasonic images are of importance for accurate evaluation. The spread of the ultrasonic beam is one cause of the images being unsharp. One technique for reducing the influence of the beam spread, and thereby improving the image quality, is by deconvolving the data with the point spread function of the ultrasonic beam. By assuming that the material ...

For inquiry of application of ultrasonic method [UT] possibilities at composite materials inspection specimens based on the carbon fibres that correspond to structure aircraft elements were designed and made. Applied specimens were made of different composite materials with various numbers of layers and various thicknesses. For simulation of delaminating in different layers of tested structure ...