Bore reconstruction of tubular ducts from its acoustic input impedance curve

Author(s):  
W. Kausel
Acta Acustica ◽  
2021 ◽  
Vol 5 ◽  
pp. 53
Author(s):  
Frédéric Ablitzer

The paper presents a method to obtain the modal expansion of the measured input impedance of a brass instrument. The method operates as a peak-picking procedure, which makes it particularly intuitive for users who are not experts in modal analysis. To bypass the limitation of usual peak-picking approaches, which are valid only for well separated resonances, the present method is based on a semi-local optimization problem. It consists in adjusting the frequency and damping of one mode at a time while taking into account the presence of all other modes in the basis. The practical application of the method involves four elementary actions, which can be chained in different ways to progressively approximate a measured input impedance. This procedure is illustrated through the approximation of the input impedance of a bass trombone. The supervised nature of the method allows the user to favour modes that have a physical meaning, i.e. that can be associated with a resonance peak. A single spurious mode can however be deliberately introduced to approximate the input impedance curve beyond the last visible peak. The method applies directly to the frequency-domain data provided by an impedance sensor and does not require any preprocessing. Nevertheless, it is fairly robust to noisy data. Since the method allows a reconstruction of the input impedance using either complex modes or real modes, results obtained with each approximation are critically compared.


2014 ◽  
Vol 8 (1) ◽  
pp. 279-284
Author(s):  
Qinghua Cao ◽  
Dingfang CaoChen ◽  
Quanguo Lu ◽  
Jianwu LuYan ◽  
Gang Tang ◽  
...  

This paper aims to designed a prototype for achieving the full magnetostriction of Galfenol, Lamination struction of transducer is designed and the radiation impedance is expressed in mechanical terms, a simplified onedimensional modeling of SPICE magnetostrictive transducer is established, the electrical input impedance is simulated as the function of frequency and experimentally adjusting the values is to match an existing impedance curve. a good fit between model and measurement is shown by measured and simulated electrical input impedances for the device.


2016 ◽  
Vol 5 (6) ◽  
pp. 158-162
Author(s):  
Kazuma Endo ◽  
Takayuki Sasamori ◽  
Teruo Tobana ◽  
Yoji Isota

Author(s):  
Milad Zamani ◽  
Yasser Rezaeiyan ◽  
Hai Au Huynh ◽  
Margherita Ronchini ◽  
Hooman Farkhani ◽  
...  

2021 ◽  
Vol 11 (10) ◽  
pp. 4631
Author(s):  
Yu Chen ◽  
Xiaoqing Ji ◽  
Zhongyong Zhao

The accurate establishment of the equivalent circuit model of the synchronous machine windings’ broadband characteristics is the basis for the study of high-frequency machine problems, such as winding fault diagnosis and electromagnetic interference prediction. Therefore, this paper proposes a modeling method for synchronous machine winding based on broadband characteristics. Firstly, the single-phase high-frequency lumped parameter circuit model of synchronous machine winding is introduced, then the broadband characteristics of the port are analyzed by using the state space model, and then the equivalent circuit parameters are identified by using an optimization algorithm combined with the measured broadband impedance characteristics of port. Finally, experimental verification and comparison experiments are carried out on a 5-kW synchronous machine. The experimental results show that the proposed modeling method identifies the impedance curve of the circuit parameters with a high degree of agreement with the measured impedance curve, which indicates that the modeling method is feasible. In addition, the comparative experimental results show that, compared with the engineering exploratory calculation method, the proposed parameter identification method has stronger adaptability to the measured data and a certain robustness. Compared with the black box model, the parameters of the proposed model have a certain physical meaning, and the agreement with the actual impedance characteristic curve is higher than that of the black box model.


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