Tanks are typically used for the storage of oil by the petrochemical industry, and the storage quality is largely determined by the safety of the equipment. Recently, Electromagnetic Acoustic Transducer (EMAT) technology has been the focus of many non-destructive examinations, as EMATs can generate elastic waves without contact, thereby making it easy to carry out the process of detection. The Shear Horizontal (SH)-guided waves that are generated by an EMAT are modeled in a plate made of ferromagnetic material, and this is of particular interest regarding the testing of welded structures. This paper provides an EMAT-sensor design that can be used to find cracks in the welds of a tank whereby the need for people to climb onto the tank is removed; furthermore, regarding cases where the amplitude signal of the SH-wave EMATs is too low, a simulation is used in this paper to propose a method that improves the transduction efficiency.
Snoring is one of the representative phenomena of the sleep disorder and detection of snoring is quite important for improving quality of daily human life. The purpose of this research is to define the noises of the ordinary sleep situation and to find its characteristics as a preliminary research of snoring detection. Differently from previous snoring researches, we use a built-in sound recording system of Smartphone for practical use in ordinary sleep condition, and recording was carried out in a general private bedroom. Especially, we designed the experimental protocol, including the various noises could be frequently occurred during sleep such as cough, music, talking, alarm, door open/close, fan, radio and footstep to make closer to the actual sleep circumstance. The sound data set was recorded during actual sleep from 10 normal subjects. Totally 44 snoring data set and 75-noise dataset is acquired and analyzed.
Abstract. The causes of faults of induction motors are largely categorized into bearing fault, which causes a mechanical fault, and stator fault and rotor fault, which cause an electrical fault. A stator fault among these faults, which causes an electrical fault, occurs due to the breakdown of insulation, meaning the stator is directly connected with the power supply, and the direct connection is a direct cause of a major accident. For this reason, many studies are being performed to detect the faults. This paper explained the effects of a negative sequence on phase angle change by analyzing the effects of the existing negative sequence on the d-q transform of Park's vector approach. This paper suggested a new algorithm that identifies the causes of stator faults with the use of the change in the duty ratio of the half-period frequency of the frequency when a phase angle change occurs at that moment.
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