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RISS 인기검색어
- 검색키워드
- 저자 : Ali Loghmani (검색결과 2 건)
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Active structural acoustic control of a smart cylindrical shell using a virtual microphone
Loghmani, Ali,Danesh, Mohammad,Kwak, Moon K,Keshmiri, Mehdi Institute of Physics Publishing 2016 Smart materials & structures Vol.25 No.4
<P>This paper investigates the active structural acoustic control of sound radiated from a smart cylindrical shell. The cylinder is equipped with piezoelectric sensors and actuators to estimate and control the sound pressure that radiates from the smart shell. This estimated pressure is referred to as a virtual microphone, and it can be used in control systems instead of actual microphones to attenuate noise due to structural vibrations. To this end, the dynamic model for the smart cylinder is derived using the extended Hamilton’s principle, the Sanders shell theory and the assumed mode method. The simplified Kirchhoff–Helmholtz integral estimates the far-field sound pressure radiating from the baffled cylindrical shell. A modified higher harmonic controller that can cope with a harmonic disturbance is designed and experimentally evaluated. The experimental tests were carried out on a baffled cylindrical aluminum shell in an anechoic chamber. The frequency response for the theoretical virtual microphone and the experimental actual microphone are in good agreement with each other, and the results show the effectiveness of the designed virtual microphone and controller in attenuating the radiated sound.</P>
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Ali Rezaei,Ali Loghmani,Sayyed Mahdi Hejazi,Aminollah Mohammadi 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12
In recent years, there has been a growing interest in the application of ultrasonic cleaning techniques to textiles. However, the impact of textile properties on the cleaning performance has not been studied yet. This paper addresses this gap by systematically investigating the influence of different factors including fabric type, dirt type, and ultrasonic frequency, on the cleaning efficacy of textiles. To this end, four distinct fabric types, characterized by variations in texture, fiber material, and area density, were selected for experimentation. Additionally, two distinct dirt types, derived from chocolate milk and a carbon black-paraffin mixture, were introduced to assess their specific effects on ultrasonic cleaning. To analyze the impact of ultrasonic frequency, two transducers operating at frequencies of 19.5 Hz and 32.5 Hz were designed and fabricated. The quality of cleaning on the fabric samples, stained with the aforementioned dirt types, was evaluated using a full factorial experimental design. Measurement of washing quality was carried out employing a spectrophotometer. The findings of this investigation reveal that an increase in frequency is associated with a reduction in cleaning performance. Furthermore, the type of fabric texture directly influences the extent to which dirt stains are removed from the fabric. The choice of fiber material plays a crucial role in determining the textile's hydrophilic or hydrophobic characteristics, which, in turn, significantly impacts the bonding between textile yarn and various types of dirt. Consequently, the overall cleaning efficiency of the textile is affected by these interrelated factors.
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