Analyzers and Signal Generators

Herlufsen, H.; Gade, Svend; Zaveri, Harry K.

doi:10.1002/9780470209707.ch40

Cited by 7 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This spatial resolution (0.2 m) yields an aliasing frequency of ≈850 Hz, which is sufficient for the range of the FE simulations. This high frequency limit is calculated based on the Nyquist theorem for sampling signals [28].…”

Section: Plane Wave Expansion From Finite Element Datamentioning

confidence: 99%

Low Frequency Interactive Auralization Based on a Plane Wave Expansion

2017

View full text Add to dashboard Cite

This paper addresses the problem of interactive auralization of enclosures based on a finite superposition of plane waves. For this, room acoustic simulations are performed using the Finite Element (FE) method. From the FE solution, a virtual microphone array is created and an inverse method is implemented to estimate the complex amplitudes of the plane waves. The effects of Tikhonov regularization are also considered in the formulation of the inverse problem, which leads to a more efficient solution in terms of the energy used to reconstruct the acoustic field. Based on this sound field representation, translation and rotation operators are derived enabling the listener to move within the enclosure and listen to the changes in the acoustic field. An implementation of an auralization system based on the proposed methodology is presented. The results suggest that the plane wave expansion is a suitable approach to synthesize sound fields. Its advantage lies in the possibility that it offers to implement several sound reproduction techniques for auralization applications. Furthermore, features such as translation and rotation of the acoustic field make it convenient for interactive acoustic renderings.

show abstract

Section: Plane Wave Expansion From Finite Element Datamentioning

confidence: 99%

Low Frequency Interactive Auralization Based on a Plane Wave Expansion

2017

View full text Add to dashboard Cite

show abstract

“…Frequency analysis using FFT is the most commonly used method for constant bandwidth analysis [41]. The FFT algorithm in Matlab calculates the discrete Fourier transform (DFT) described in [42].…”

Section: Spectral Analysis With Fftmentioning

confidence: 99%

Time Series-, Time-Frequency- and Spectral Analyses of Sensor Measurements in an Offshore Wave Energy Converter Based on Linear Generator Technology

Strömstedt¹,

Savin²,

Svensson³

et al. 2013

EPE

View full text Add to dashboard Cite

Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is a sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.

show abstract

Introduction

2020

Engineering Acoustics

View full text Add to dashboard Cite

Analyzers and Signal Generators

Cited by 7 publications

References 0 publications

Low Frequency Interactive Auralization Based on a Plane Wave Expansion

Low Frequency Interactive Auralization Based on a Plane Wave Expansion

Time Series-, Time-Frequency- and Spectral Analyses of Sensor Measurements in an Offshore Wave Energy Converter Based on Linear Generator Technology

Introduction

Contact Info

Product

Resources

About