Papers by Keyword: Standing Wave

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Authors: Da Yu Huang
Abstract: Absorption coefficient is an important parameter of the absorption function of the absorption material. Traditional measurement methods of absorption coefficient are standing wave tube and reverberation which have some shortcomings. In this paper, phase of the sound pressure measured by two equal distance microphones placed in the front of the absorption material is delayed in order to attain the absorption coefficient. At the last, an experiment for one absorption material is carried out, the experiment results compare with the results of the other methods above mentioned that denotes that the theory is correct and practicable. Key words: absorption material standing wave reverberation time delaying
1156
Authors: Cong Yun Zhu, Jian Ru Shi, Shu Feng Yang
Abstract: Absorption coefficient is an important parameter of the absorption function of the absorption material. Traditional measurement methods of absorption coefficient are standing wave tube and reverberation which have some shortcomings. In this paper, phase of the sound pressure measured by two equal distance microphones placed in the front of the absorption material is delayed in order to attain the absorption coefficient. At the last, an experiment for one absorption material is carried out, the experiment results compare with the results of the other methods above mentioned that denotes that the theory is correct and practicable.
1350
Authors: Xiao Hua Qian, Meng Hong Shen
Abstract: Linear ultrasonic motors have been of significant research interests for its excellent characteristics, but it’s hindered by complicated structure. The purpose of this paper is to design and manufacture a prototype by utilizing ANSYS software based on the analysis of mechanism. The vibrator of linear motor is composed of a three teeth rectangular medal block, two group of PZT elements which is adhered on the surface of metal block and slider. It is found that the result of FEA analysis is consistent with experiment result.
140
Authors: Wei Shan Chen, Ying Xiang Liu, Jun Kao Liu, Sheng Jun Shi
Abstract: To obtain large mechanical output power, a ring type standing wave ultrasonic motor using cantilever type bending transducer is proposed. There is a cantilever on one side of the ring, and four PZT ceramics are set on each end surface of the cantilever. The bending mode of ring is excited by the bending vibration of cantilever transducer. Thus, linear simple harmonic motions are achieved at the particles on the teeth. The working principle of proposed motor is analyzed. The ring and transducer are designed with FEM. The bending vibration modals of transducer and ring are degenerated, and the motion trajectories of nodes on the teeth are analyzed. The analysis results indicate that a standing wave is excited in the ring by the bending vibration of transducer, and the proposed motor has potential good output characteristics. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed motor.
293
Authors: Jun Kao Liu, Tao Xie, Wei Shan Chen, Chang Hua Jia
Abstract: A new type standing wave ultrasonic motor is proposed in this study. In this design, three longitudinal vibration transducers are clamped on the inner side of a ring with driving teeth by screws. Bending standing wave can be generated in the ring by the longitudinal vibrations of the transducers. Thus, oblique linear simple harmonic vibrations are formed on the teeth, which can drive the rotor by frictional force. The structure and working principle of the proposed design are introduced. The motor is designed and analyzed by using FEM method. A standing wave is gained after the degeneration between the bending vibration of the ring and the longitudinal vibration of the transducer. The test results of the prototype motor verify the feasibility of the proposed design.
661
Authors: Le Yi Wang
Abstract: This paper presents a frequency multiplication technique using travelling wave. The proposed technique improves conversion efficiency, cancels byproduct harmonics, and achieves wide bandwidth. citive pressure sensor by means of frequency shifts from its nominal operation frequency. It takes advantage of standing-wave formation and loss cancellation in a distributed structure to generate high amplitude signals resulting in high harmonic power. Wide bandwidth operation and odd harmonic cancellation around the center frequency are the inherent properties of this frequency multiplier.
128
Authors: Tomohiro Inada, Hirotaka Ojima, Li Bo Zhou, Teppei Onuki, Jun Shimizu
Abstract: Based on the acoustic levitation phenomenon, we have proposed and developed an acoustic levitation/trap system to control the movements of free abrasives for the finishing of inner surfaces. Described in this paper are the theoretical analysis of levitation force generated in a standing wave field, and experimental results of levitation and trap. A simulation is first performed to determine the wave amplitude and frequency required to levitate the actual abrasives. Based on those results, we developed a system which consists of a sound transducer (speaker), a reflector (an aluminium plate), an amplifier and a function generator, and successfully not only levitated but also trapped actual abrasives in a cylindrical tube. It is found that the relation between the size, density of the abrasives and the power of the acoustic field (wave amplitude and frequency) fairly agreed with the theoretical prediction. Also, the kinetics of levitated abrasives including their positions and movements are precisely controllable by varying the wave frequency and switching from one node position to another.
326
Authors: Pattanan Meethom, Kheamrutai Thamaphat, Pichet Limsuwan, Orrawan Rewthong
Abstract: An optical method to determine a speed of sound (or ultrasound) in water was described in this work. The measuring system composes of ultrasonic transducer, glass water bath, He-Ne laser source, lens, and screen. An ultrasound fog generator used for producing an ultrasound with a frequency f of 1.74 MHz was immersed in DI water. It was fixed at one side of water bath. When the sound wave travels in water along the length of water bath, a standing wave is obtained from the interference of the incidence wave and the wave reflected from the opposite side of water bath. The node and antinode of the standing wave act as an opaque and transparent medium. As a He-Ne laser beam with a wavelength of 632.8 nm travelled to a convex lens with a focal length of 5 cm and diverged through the sound field, an enlarged standing wave pattern was shown on a white screen. The wavelength of sound wave λ was obtained using geometry (similar triangle). Therefore, the speed of ultrasound in water was calculated by v = fλ. In this work, the water temperature was varied in a range of 15 - 39 °C. The results showed that the speed of sound increased with increasing the water temperature. The percentage error was below 2.8. This proposed method can be used for demonstrating physics principles such as waves and optics for high school students and undergraduates.
75
Authors: Hong Xiang Wang, Jing Hu, Yuan Yuan Ma, Qing He
Abstract: This paper presents a vibrator of linear standing wave ultrasonic driving. The driving vibrator works with in-plane bending vibration modes and the vibrator structure which contacts with the guide on both sides is long ring and increases driving force . Based on mode analysis, the working principle of long ring vibrator is analyzed. The vibrator of linear standing wave ultrasonic driving is developed, which has been tested and analyzed. The experimental results further verify the correctness of the theory analysis.
1099
Authors: Yan Chao, Li Qun Wu
Abstract: Nowadays solar energy receives more and more attention for its clear, non-pollutant and renewable characteristics. Although the production cost of electricity by solar cell is much higher than those by fossil fuels currently, solar cell has partly substituted traditional energy and be used in some fields. Silicon wafer surface texture act an important role in solar cell, which can trap the incident lights and influence the photoelectric conversion. In this paper, a new method using ultrasonic standing wave is present based on the previous researches. The acid molecules are droved to distribute regularly in terms of the standing wave. Then regular morphology can be textured on the surface of mc-Si by the acid molecules etching with silicon. SEM experiment illustrate the present method can texture regular morphology on the surface of multi-crystalline silicon (mc-Si) , also the antireflection of 9.4% is much lower than that of traditional acid etching.
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