Application of discrete Fourier transform to electronic measurements

Liu, J.G.; Schönecker, Andreas; Fruhauf, U.; Keitel, U.; Gesemann, H.-J.

doi:10.1109/icics.1997.652188

Cited by 6 publications

(4 citation statements)

References 3 publications

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“…After the compensator parameters, g and T , are adjusted using (22), the process can be repeated until |G(jω)| falls within the desired level of tolerance. G(jω) can be determined in real time as shown in [18] by…”

Section: The Compensator Auto-tuning Proposalmentioning

confidence: 99%

Structural vibration control using an active resonator absorber: modeling and control implementation

Jalili¹,

Knowles²

2004

Smart Mater. Struct.

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A new dynamic vibration absorber referred to as an active resonator absorber (ARA) is proposed; we explore its practical implementation using piezoelectric ceramic (PZT) inertial actuators. The ARA is a passive absorber with an additional dynamic feedback compensator within the PZT actuator. Without any controller, it becomes a passive vibration absorber due to internal damping and elasticity properties of the piezoelectric materials; hence, it is inherently fail-safe. For active operation, the compensator parameters are designed such that a resonance condition is intentionally created within the absorber subsection to mimic the vibratory energy from the system of concern to which it is attached. The resonance condition can be created through the appropriate design of the compensator and implemented through adjusting the external electrical voltage applied to the PZT actuator. Although PZT materials inherently possess nonlinear characteristics (e.g., hysteresis), an equivalent linearized model is developed for the actuator subsystem. An experimental set-up is then constructed to validate the proposed linearized model and estimate the actuator parameters using a nonlinear least squares algorithm. Because the parameters of the PZT actuators (i.e. stiffness, damping, and effective mass) are approximate, the compensator designs based on these parameters would result in partial vibration suppression when utilized in real applications. An auto-tuning method is used to effectively tune the compensator parameters to improve the vibration suppression quality. The effectiveness and stability of the proposed auto-tuning scheme when implemented on a single-degree-of-freedom primary system are demonstrated.

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Section: The Compensator Auto-tuning Proposalmentioning

confidence: 99%

Structural vibration control using an active resonator absorber: modeling and control implementation

Jalili¹,

Knowles²

2004

Smart Mater. Struct.

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“…Several known methods for impedance calculation from voltage and current measurements have been studied [ Angrisani et al , 1996; Mahmud , 1989; Liu et al , 1997, 1999]. The Discrete Fourier Transform (DFT) method described by Liu et al [1997] was selected for this application. Otherwise, the current probe has not a constant response with the frequency; therefore the system calibration has been necessary.…”

Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

“…Circuit schemes of the earth models included in Table 1. Liu et al [1997] was selected for this application. Otherwise, the current probe has not a constant response with the frequency; therefore the system calibration has been necessary.…”

Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

“…It also processes the received digital data, providing as an output the impedance values as a function of the frequency. Several known methods for impedance calculation from voltage and current measurements have been studied [Angrisani et al, 1996;Mahmud, 1989;Liu et al, 1997Liu et al, , 1999. The Discrete Fourier Transform (DFT) method described by Figure 3.…”

Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

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Earth impedance model for through-the-earth communication applications with electrodes

et al. 2010

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[1] Through-the-earth (TTE) communications are relevant in applications such as caving, tunnel and cave rescue, mining, and subsurface radiolocation. The majority of the TTE communication systems use ground electrodes as load antenna. Wires, electrode contact, and earth impedances are the major contributors to the impedance observed by the transmitter. In this paper, state-of-art models found in the literature are reviewed, and an improved method to measure the earth impedance is presented. The paper also proposes an optimal circuit model for earth impedance between electrodes as a function of frequency, as a consequence of the particular conditions of the application. The model is validated with measurements for different soil conditions, showing a good agreement between empirical data and the simulation results.

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