In this study, we have evaluated the ability of ultrasonic sensors to produce guidance signals for greenhouse application robots. First, one high-quality ultrasonic sensor was selected and some basic experiments were carried out. Experimental results showed that with predetermined internal parameters, the accuracy of the selected sensor was good for distances between 15 and 215 cm and angles be...

In this work, the degradation of Basic Red 29 (BR29), an azo dye, was investigated using a high-frequency ultrasonic reactor (300 kHz). The influence of several parameters such as initial substrate concentration (5–200 mg L−1) , pH (3–10.1), ultrasonic power (20–80 W), and nature of the dissolved gas (Ar, air, and N2) on the degradation of BR29 was assessed. Additionally, the impact of natural ...

Feature extraction and selection are the most important techniques for ultrasonic flaw signal classification. In this study, empirical mode decomposition (EMD) is first used to obtain the intrinsic mode functions (IMFs) of original ultrasonic signals. Such IMFs and traditional time as well as frequency domain based statistical parameters are extracted as the initial features of flaw signal. Aft...

The amplitude of an ultrasonic signal generated by electromagnetic acoustic transducers (EMATs) is typically low when compared to those generated by contacting transducers, which restricts the application of EMATs in the fields of nondestructive testing and nondestructive evaluation. The transmission process of a surface wave EMAT is studied, based on a previously established 3-D model, with th...

This paper proposes a simultaneous tuning method for PID controllers and dead-zone compensators based on particle swarm optimization. By the proposed algorithm, PID gains and dead-zone parameters are tuned online to minimize the error between the control output and the reference input. However, since ultrasonic motors intrinsically have a varying dead-zone in the control input associated with a...

A viscous mechanism for the absorption of ultrasonic energy in tissue is considered. It is shown that the viscous forces acting between a suitably chosen distribution of suspended particles or structure lements and a suspending liquid can account for the experimentally observed linear elations between acoustic absorption coefficient and ultrasonic frequency. The frequency band over which linear...

This paper presents a study about the amplitude of ultrasonic echoes and a simple model is proposed to predict the shape and amplitude of echoes received from different materials in environments composed of walls and corners. Using this model is possible to distinguish between walls and corners, in a single circular scan of a single ultrasonic transducer pair. The parameters of the model have b...

BACKGROUND The aim of this study was to compare reliability in handling and function of resterilised and single-use disposable ultrasonic scissors. METHODS In a prospective randomized study, the surgeon blindly tested new and resterilised ultrasonic scissors. The parameters were force of activation, cutting effect, coagulation effect, error messages and disturbing generator noise. RESULTS 5...

This paper presents a ultrasonic flaw signal classification system by using wavelet transform and support vector machine (SVM). A digital flaw detector is first used to acquire the signals of defective carbon fiber reinforced polymer (CFRP) specimen with void, delamination and debonding. After that, the time domain based ultrasonic signals can be processed by discrete wavelet transform (DWT), a...

Launch vehicles use ablative nozzle liners to function under very high thermal and erosive environments. In solid motor nozzle throats, graphite or carbon phenolic materials are used because of their high heat of ablation and erosion resistance. Ultrasonic testing is implemented as the primary NDT technique for throat insert liners by almost replacing radiography testing. Though introduced for ...