Geometrical modeling and analysis of low frequency acoustical scattering from cylindrically formed schools of swim bladder fish

2020 ◽  
Vol 148 (4) ◽  
pp. 2482-2482
Author(s):  
Luis Donoso ◽  
Christopher Feuillade
Keyword(s):  
Low Frequency ◽  
Swim Bladder ◽  
Modeling And Analysis ◽  
Geometrical Modeling

Modeling and Design of an Inertial Vibration Reflector

1997 ◽  
Vol 119 (1) ◽  
pp. 20-27
Author(s):  
R. G. Longoria ◽  
V. A. Narayanan
Keyword(s):  
Vibration Suppression ◽  
Active Vibration Control ◽  
Low Frequency ◽  
Dominant Frequency ◽  
Prototype System ◽  
Primary System ◽  
Transient Vibration ◽  
Modeling And Analysis ◽  
Reflector System ◽  
Oriented Parallel

This paper presents the modeling and analysis of a novel vibration suppression device. This reflector system exerts inertial forces, induced by tuned pendular motion, to control translational vibration of a primary system. Tuning of the reflector critically depends on the parameters of the pendula and on the rotational speed at which they are spun about an axis oriented parallel to the undesired motion. Consequently, one of its most appealing attributes is this devices’s ability to be tuned to, and thus actively track, the dominant frequency of disturbance forces. The paper describes how governing equations from an integrated physical model are developed using a bond graph approach and then used to derive relations applicable in design of an inertial reflector system. It is shown how the model supports component selection and tradeoff studies as well as simulation. Experimental results from testing of a laboratory realization of a prototype system are used to verify the design and to compare with simulation of a mathematical model. The results from the laboratory demonstrate the ability of the inertial reflector to control steady and transient vibration, and the favorable results suggest extended investigation for active vibration control situations. In particular, applications in low frequency vibration mitigation are promising.

scholarly journals Electromechanical coupling dynamic modeling and analysis of vertical electrodynamic shaker considering low frequency lateral vibration

2020 ◽  
Vol 12 (10) ◽  
pp. 168781402096385
Author(s):  
Shuguang Zuo ◽  
Zhaoyang Feng ◽  
Jian Pan ◽  
Xudong Wu
Keyword(s):  
Dynamic Model ◽  
Electromechanical Coupling ◽  
Low Frequency ◽  
Coupling Model ◽  
Vertical Position ◽  
Force Model ◽  
Lateral Vibration ◽  
Modeling And Analysis ◽  
Electrodynamic Shaker ◽  
Coupling Dynamic

For the problem of relatively severe lateral vibration found in the vertical electrodynamic shaker experiment, an electromechanical coupling dynamic model of the electrodynamic shaker considering low-frequency lateral vibration is proposed. The reason and mechanism of the lateral vibration is explained and analyzed through this model. To establish this model, an electromagnetic force model of overall conditions is firstly built by fitting force samples with neural network method. The force samples are obtained by orthogonal test of finite element simulation, in which five factors of the moving coil including current, vertical position, flipping eccentricity angle, radial translational eccentric direction and distance are considered. Secondly, a 7-dof dynamic model of the electrodynamic shaker is developed with the consideration of the lateral vibration of the moving system. To obtain the transfer function accurately, the stiffness and damping parameters are identified. Finally, an electromechanical dynamic model is established by coupling the force model and the 7-dof dynamic model, and it is verified by experiments. The coupling model proposed can be further used for the control and optimization of the electrodynamic shaker.

Modeling and Analysis of Ultra-Low Frequency Dynamics of Drag-Free Satellites

2019 ◽  
Vol 31 (2) ◽  
pp. 151-160 ◽  
Author(s):  
Jiaxing Zhou ◽  
Lei Liu ◽  
Zhigang Wang
Keyword(s):  
Low Frequency ◽  
Modeling And Analysis

Low frequency acoustical scattering from dynamic schools of swim bladder fish

2019 ◽  
Vol 145 (3) ◽  
pp. 1654-1654
Author(s):  
Luis Donoso ◽  
Christopher Feuillade
Keyword(s):  
Low Frequency ◽  
Swim Bladder

Minimum Time Trajectory Planning Along Specified Tool Path With Consideration of Cutting Force Constraint and Feed Drive Dynamics

Manufacturing ◽  
2002 ◽  
Author(s):  
Nejah Tounsi ◽  
Trevor E. Bailey ◽  
Mohamed A. Elbestawi
Keyword(s):  
Cutting Force ◽  
Feed Rate ◽  
Tool Path ◽  
End Milling ◽  
Low Frequency ◽  
Minimum Time ◽  
Force Model ◽  
Modeling And Analysis ◽  
Feed Drive ◽  
Drive Dynamics

This paper proposes an Optimized Feed Scheduling Strategy (OFSS). This strategy integrates the feed drive dynamics with the minimum-time trajectory planing to achieve the desired feed rate at the appropriate tool position along specified tool path. It optimizes the use of the feed drive capabilities and provides good tracking of the cutting geometry variations. The feed scheduling is applied to maintain near-constant cutting force magnitude. An integrated geometric and mechanistic force model is used to estimate the in-cut geometry and the cutting force. A methodology based on time series modeling and analysis is proposed to identify the low frequency feed drive dynamics. The resulting model is applied as an acceleration/deceleration processor (Acc/Dec) to relate the actual feed rate to the commanded feed rate specified in the G-Code file. The effectiveness of the OFSS is analyzed using ball end milling operations. Its performance in terms of productivity and machining safety is assessed based on comparison with other feed scheduling techniques where the trajectory planing does not consider the feed drive dynamics.

Mathematical Modeling and Analysis of a Very Low Frequency HV Test System

2014 ◽  
Vol 29 (11) ◽  
pp. 5784-5794 ◽  
Author(s):  
Stefan Eberharter ◽  
Wolfgang Kemmetmuller ◽  
Andreas Kugi
Keyword(s):  
Mathematical Modeling ◽  
Low Frequency ◽  
Test System ◽  
Modeling And Analysis ◽  
Very Low Frequency

Modeling and analysis of piezoelectric folded-beam isolator for attenuating micro-vibration in spacecraft

2018 ◽  
Vol 07 (01n02) ◽  
pp. 1850013 ◽  
Author(s):  
Yajun Luo ◽  
Yingqi Zhang ◽  
Xu Zhang ◽  
Xing Gao ◽  
Kun Jia ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Transfer Functions ◽  
Low Frequency ◽  
Relative Displacement ◽  
Fe Model ◽  
Feedback Controls ◽  
Isolation System ◽  
Modeling And Analysis ◽  
Mixed Responses ◽  
Micro Vibration

Design, modeling, and analysis of an intelligent flexible isolation system for attenuating low-frequency micro-vibration are presented. The isolator consists of a payload platform, a supporting platform and four folded-beams with surface-bonded macro-fiber composites (MFCs). To accurately analyze the system performance, a piezoelectric finite element (FE) model is built and validated by the modal analysis results derived from ANSYS. This paper presents an attempt to widen the low-frequency isolation range for the micro-vibration using a modal frequency shift approach. The transfer functions of the active isolation system with different feedback controls are derived based on an FE model, in which feedback signals can be absolute and relative accelerations, absolute and relative displacement, relative velocity, and mixed responses. According to the numerical results, the expected performance of low-frequency vibration isolation can be easily achieved, especially by a kind of mixed responses feedback method. The time-domain simulations also show that the proposed piezoelectric isolation system exhibits a good isolation performance, endowing them with great potential for the micro-vibration restrain in aerospace application.

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