Optimized Driver Placement for Array-Driven Flat-Panel Loudspeakers

2017 ◽  
Vol 42 (1) ◽  
pp. 93-104 ◽  
Author(s):  
David A. Anderson ◽  
Michael C. Heilemann ◽  
Mark F. Bocko
Keyword(s):  
Frequency Band ◽  
Mode Coupling ◽  
Dynamic Force ◽  
Two Dimensional ◽  
Flat Panel ◽  
Piezoelectric Patch ◽  
Optimal Force ◽  
Network Method ◽  
Point Forces ◽  
Bending Modes

Abstract The recently demonstrated ‘modal crossover network’ method for flat panel loudspeaker tuning employs an array of force drivers to selectively excite one or more panel bending modes from a spectrum of panel bending modes. A regularly spaced grid of drivers is a logical configuration for a two-dimensional driver array, and although this can be effective for exciting multiple panel modes it will not necessarily exhibit strong coupling to all of the modes within a given band of frequencies. In this paper a method is described to find optimal force driver array layouts to enable control of all the panel bending modes within a given frequency band. The optimization is carried out both for dynamic force actuators, treated as point forces, and for piezoelectric patch actuators. The optimized array layouts achieve similar maximum mode coupling efficiencies in comparison with regularly spaced driver arrays; however, in the optimized arrays all of the modes within a specified frequency band may be independently addressed, which is important for achieving a desired loudspeaker frequency response. Experiments on flat panel loudspeakers with optimized force actuator array layouts show that each of the panel modes within a selected frequency band may be addressed independently and that the inter-modal crosstalk is typically −30 dB or less with non-ideal drivers.

Parameter Sensitivity Analysis of Piezoelectrically-Actuated Flexural/Torsional Vibrating Beams

2020 ◽  
Author(s):  
Roya Salehzadeh ◽  
Nicholas Candelino ◽  
Mohammad Javad Khodaei ◽  
Amin Mehrvarz ◽  
Nader Jalili
Keyword(s):  
Sensitivity Analysis ◽  
Equations Of Motion ◽  
Parameter Sensitivity ◽  
Point Mass ◽  
Parameter Sensitivity Analysis ◽  
Piezoelectric Patch ◽  
Frequency Domain Methods ◽  
Sensitivity Curves ◽  
Vibrating Beams ◽  
Bending Modes

Abstract A numerical parameter sensitivity analysis is performed on the bending and torsional vibrations of a flexural-torsional vibrating beam gyroscope model. The gyroscope analyzed in this work is comprised of a rotating cantilever beam with a point-mass attached to its free end and a piezoelectric actuator fixed to a portion of its length. The governing equations of motion are derived using extended Hamilton’s principle and the steady-state magnitude response of the system is obtained through frequency domain methods. A sensitivity analysis is then carried out for the parameters including rotational speed of the base, the length of the beam, the location of the piezoelectric patch, and the location of the added point mass along the beam’s length. It is observed that, in the region surrounding specific configurations, small variations in the rotation rate, beam length and the location of the piezoelectric patch will result in significant changes to the amplitudes of the coupled vibrations and produce peaks in the sensitivity curves. Further, the amplitude of vibration tends to increase as the location of the added point-mass is moved closer to the free end. Generally, the bending modes are more sensitive to all of these parameter variations than are the torsional modes.

scholarly journals Mode coupling and resonance instabilities in quasi-two-dimensional dust clusters in complex plasmas

2014 ◽  
Vol 90 (3) ◽  
Author(s):  
Ke Qiao ◽  
Jie Kong ◽  
Jorge Carmona-Reyes ◽  
Lorin S. Matthews ◽  
Truell W. Hyde
Keyword(s):  
Mode Coupling ◽  
Two Dimensional ◽  
Complex Plasmas

UNIVERSAL PRANDTL NUMBER IN TWO-DIMENSIONAL KRAICHNAN-BATCHELOR TURBULENCE

2008 ◽  
Vol 22 (20) ◽  
pp. 3421-3431
Author(s):  
MALAY K. NANDY
Keyword(s):  
Prandtl Number ◽  
Mode Coupling ◽  
Perturbation Expansion ◽  
Dynamic Scaling ◽  
Two Dimensional ◽  
Turbulent Prandtl Number ◽  
Energy Regime ◽  
Self Consistent ◽  
Prandtl Numbers

We evaluate the universal turbulent Prandtl numbers in the energy and enstrophy régimes of the Kraichnan-Batchelor spectra of two-dimensional turbulence using a self-consistent mode-coupling formulation coming from a renormalized perturbation expansion coupled with dynamic scaling ideas. The turbulent Prandtl number is found to be exactly unity in the (logarithmic) enstrophy régime, where the theory is infrared marginal. In the energy régime, the theory being finite, we extract singularities coming from both ultraviolet and infrared ends by means of Laurent expansions about these poles. This yields the turbulent Prandtl number σ ≈ 0.9 in the energy régime.

Development of a two-dimensional piezoelectric traveling-wave generator

2020 ◽  
pp. 1045389X2094394
Author(s):  
Yu-Min Lin ◽  
Yu-Hsiang Hsu ◽  
Wen-Chun Su ◽  
Yuan-Ting Kao ◽  
Chih-Kung Lee
Keyword(s):  
Traveling Waves ◽  
New Method ◽  
Two Dimensional ◽  
Resonant Frequencies ◽  
Specific Direction ◽  
Directional Movement ◽  
Bending Mode ◽  
Wave Generator ◽  
Bending Modes ◽  
Four Electrodes

In this article, we present a new method to control the direction of traveling waves in either an x-direction or y-direction on a two-dimensional square plate. The core structure was composed of a piezoelectric serial bimorph with four electrodes. Each electrode was spatially designed to activate one of the bending modes and which included the ability to reduce adjacent modes and minimize interference. Our new method differs from other reported methods in that the four electrodes were driven at designated resonant frequencies. In our wave generator, different driving amplitudes and phases were applied to induce the traveling waves to propagate in a specific direction. To design the directional movement and to better understand the pattern of induced traveling waves, an analytical solution was derived to assist in the design of the four driving electrodes. Using our newly developed analytical method, traveling waves can be controlled to travel in either the x-direction or y-direction using two different sets of electrodes, where each electrode can be driven at a specific but different bending mode. We found that both the voltage ratio and phase difference between the two driving electrodes are important factors for optimization.

IMPLEMENTATION OF NEURAL NETWORK METHOD TO INVESTIGATE DEFECT CENTERS IN SEMI-INSULATING MATERIALS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4449-4454 ◽  
Author(s):  
S. JANKOWSKI ◽  
M. WIERZBOWSKI ◽  
P. KAMINSKI ◽  
M. PAWLOWSKI
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Learning Process ◽  
Two Dimensional ◽  
Insulating Materials ◽  
Arrhenius Plots ◽  
Defect Centers ◽  
Dimensional Approximation ◽  
Network Method ◽  
Transient Spectroscopy

A neural network (NN) method has been proposed as a new algorithm for extraction of defect centers parameters in semi-insulating materials from experimental data obtained by photoinduced transient spectroscopy (PITS). The new algorithm is applied to investigate irradiation-induced defect centers in high resistive silicon. The folds on the PITS spectral surface formed due to the presence of defect levels are best fitted with a two-dimensional approximation function with implementation of the NN learning process. As a result, the Arrhenius plots for defect centers are obtained and the parameters of these centers are determined.

Phase Effect on Mode Coupling in Kelvin–Helmholtz Instability for Two-Dimensional Incompressible Fluid

2009 ◽  
Vol 52 (4) ◽  
pp. 694-696 ◽  
Author(s):  
Wang Li-Feng ◽  
Teng Ai-Ping ◽  
Ye Wen-Hua ◽  
Xue Chuang ◽  
Fan Zheng-Feng ◽  
...  
Keyword(s):  
Incompressible Fluid ◽  
Mode Coupling ◽  
Two Dimensional ◽  
Helmholtz Instability ◽  
Phase Effect
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