scholarly journals Method for Establishing a Traveling Wave Sound Field with Adaptive Control in a Water-Filled Sound Tube

2021 ◽  
Vol 11 (13) ◽  
pp. 5785
Author(s):  
Yan Xiao ◽  
Xuesong Zhang
Keyword(s):  
Adaptive Control ◽  
Transfer Function ◽  
Wave Field ◽  
Transmission Coefficient ◽  
Sound Source ◽  
Traveling Wave ◽  
Control Method ◽  
Sound Field ◽  
Reflection And Transmission ◽  
Reflection And Transmission Coefficient

The transfer function method is a common method for establishing a traveling wave field in a sound tube to measure the reflection and transmission coefficient of underwater material. The voltage applied to the secondary sound source can be calculated in accordance with the transfer matrix between the sound sources and hydrophones, then a traveling wave field can be established in the sound tube. However, the transfer function must be remeasured when the measurement frequency needs to be changed. A checking procedure of the traveling wave field in the sound tube is essential before measuring underwater acoustic material. If it is not an accurate traveling wave field, the secondary sound source signal should be corrected until the traveling wave field meets the requirements. To address these problems, an adaptive control method for generating plane traveling waves is proposed. The phase difference of sound pressures measured using the two hydrophones between the secondary sound source and the sample is used as the objective function in the adaptive algorithm, and the amplitude and phase of the secondary sound source can be obtained using the adaptive control system in the frequency domain. When a traveling wave field is formed, the reflection and transmission coefficient of the sample can be measured at the same time. With this method, the procedure of testing the traveling wave field is omitted. If the state of the primary sound source changes, the signal form of the secondary sound source can be changed immediately. Therefore, the efficiency of material measurement is improved. Theoretically, this method can obtain the most matching signal form of the secondary sound source, such that the accuracy of this method is remarkably high. Simulation and experimental results in this paper show that the measurement accuracy is reliable within the frequency range of 100–2500 Hz.

Single Defect in Finite one Dimensional Photonic Crystals

2012 ◽  
Vol 614-615 ◽  
pp. 1629-1632
Author(s):  
Gang Xu ◽  
Yun Sun
Keyword(s):  
Photonic Crystals ◽  
Transmission Coefficient ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Defect Mode ◽  
Transmission Peak ◽  
Reflection And Transmission ◽  
One Dimensional ◽  
Single Defect ◽  
Reflection And Transmission Coefficient

Applying transfer matrix method, we get reflection and transmission coefficient of finite one dimensional photonic crystals. At the same time, we consider the position influence of single defect. We find the frequency of defect mode is same, but the height of transmission peak is not same when single defect is in different position of crystal. The transmission peak is maximum when the defect is in center of finite one dimensional photonic crystals.

Adaptive Control of Active Balancing Systems for Speed-Varying Rotors Using Feedforward Gain Adaptation Technique

1999 ◽  
Vol 123 (3) ◽  
pp. 346-352 ◽  
Author(s):  
Kwang-Keun Shin ◽  
Jun Ni
Keyword(s):  
Adaptive Control ◽  
Transfer Function ◽  
Control Method ◽  
Control Area ◽  
Positive Real ◽  
Single Plane ◽  
Active Balancing ◽  
Gain Adaptation ◽  
Jeffcott Rotor ◽  
Classical Technique

This paper presents a new adaptive control method for active balancing of speed-varying rotors. It is developed based on the feedforward gain adaptation problem, which is a classical technique in the continuous-time adaptive control area. The condition for using this technique is the need for strictly positive realness of the transfer function. In this research, the technique is re-examined and modified to be appropriate for the balancing problem. It is also shown that the rotor dynamics of single-plane balancing problem can easily be converted to a strictly positive real transfer function and that, consequently, the feedfoward gain adaptation technique can be applied. This paper demonstrates that the developed method can be applied to a simple Jeffcott rotor and can also be extended to the single-plane balancing problem of general flexible rotor. Simulation studies show that the new method works well as expected.

Sign in / Sign up

Export Citation Format

Share Document