Optimal configuration and combination of piezoelectric transducer and inductor for synchronized-switch-damping-on-an-inductor technique

2016 ◽  
Vol 28 (7) ◽  
pp. 888-906
Author(s):  
Junjiro Onoda ◽  
Shigeru Shimose ◽  
Kenji Minesugi
Keyword(s):  
Energy Dissipation ◽  
Piezoelectric Transducer ◽  
Energy Dissipation Rate ◽  
Free Vibrations ◽  
Piezoelectric Transducers ◽  
Optimal Configuration ◽  
Electric Voltage ◽  
Cross Sectional ◽  
Patch Type ◽  
Parallel Connections

This article describes the optimal configuration and combination of piezoelectric transducers and inductors for the synchronized-switch-damping-on-an-inductor technique. The technique suppresses structural vibrations by inverting the polarity of the electric voltage in a piezoelectric transducer using a switched inductive shunt circuit at each displacement extremum. The energy dissipation rate of synchronized switch damping on an inductor depends on the impedances of the transducer and the inductor in the circuit, especially the resistive component, in this inversion. For this study, mathematical models of the equivalent resistances of transducers and inductors for this inversion phenomenon were formulated based on experiments with various transducers and inductors. Using these models, the optimal ratio of the thickness–area of patch-type piezoelectric transducers and that of the length–cross-sectional area of the lead of the inductors were analytically obtained. The optimization of series–parallel connections of multiple transducers and inductors was also shown to be equivalent to this one. The optimal mass budget allocation for the transducers and inductors was also formulated. Two examples of optimization, involving an increase in energy dissipation rates by a factor of 4, were presented. The examples showed that the time taken to suppress free vibrations in a clamped beam was reduced to half through the optimization.

STUDY OF PULSE MODE OF PIEZOELECTRIC TRANSDUCER FOR ECHOSCOPE

2019 ◽  
pp. 50-57
Author(s):  
V. S. Konovalova ◽  
R. S. Konovalov ◽  
S. I. Konovalov
Keyword(s):  
Piezoelectric Transducer ◽  
Soft Tissues ◽  
Active Element ◽  
Pulse Mode ◽  
Piezoelectric Transducers ◽  
Electric Signal ◽  
Stationary Mode ◽  
Piezoceramic Plate ◽  
Electric Voltage ◽  
Broadband Pulse

The piezoelectric transducer of the echoscope intended for research of soft tissues of the person is considered. The active element of the transducer is a damped piezoceramic plate. As an exciting electric signal, an electric voltage pulse with a different number of half‑cycles at the natural frequency of the plate is selected. The pulse mode of the radiator operation is investigated. The amplitudes and durations of the probing acoustic signal are estimated depending on the duration of the exciting pulse. The dynamics of changes in the durations and amplitudes of the radiated acoustic pulses is studied. For various degrees of damping of the plate, the number of half‑cycles contained in the exciting signal, from which the emitter operates in a stationary mode, is determined. The obtained results can be used in the field of design and development of technology for manufacturing of broadband pulse piezoelectric transducers of ultrasonic medical echoscopes.

Energy dissipation rate in a baffled vessel with pitched blade turbine impeller

1991 ◽  
Vol 56 (9) ◽  
pp. 1856-1867 ◽  
Author(s):  
Zdzisław Jaworski ◽  
Ivan Fořt
Keyword(s):  
Energy Dissipation ◽  
Cross Sections ◽  
Mechanical Energy ◽  
Vessel Diameter ◽  
Energy Dissipation Rate ◽  
Mean Velocity ◽  
Agitated Vessel ◽  
Radial Profiles ◽  
Pitched Blade Turbine ◽  
Turbine Impeller

Mechanical energy dissipation was investigated in a cylindrical, flat bottomed vessel with four radial baffles and the pitched blade turbine impeller of varied size. This study was based upon the experimental data on the hydrodynamics of the turbulent flow of water in an agitated vessel. They were gained by means of the three-holes Pitot tube technique for three impeller-to-vessel diameter ratio d/D = 1/3, 1/4 and 1/5. The experimental results obtained for two levels below and two levels above the impeller were used in the present study. Radial profiles of the mean velocity components, static and total pressures were presented for one of the levels. Local contribution to the axial transport of the agitated charge and energy was presented. Using the assumption of the axial symmetry of the flow field the volumetric flow rates were determined for the four horizontal cross-sections. Regions of positive and negative values of the total pressure of the liquid were indicated. Energy dissipation rates in various regions of the agitated vessel were estimated in the range from 0.2 to 6.0 of the average value for the whole vessel. Hydraulic impeller efficiency amounting to about 68% was obtained. The mechanical energy transferred by the impellers is dissipated in the following ways: 54% in the space below the impeller, 32% in the impeller region, 14% in the remaining part of the agitated liquid.

scholarly journals Spectral characteristics of spring arctic mesosphere dynamics

1998 ◽  
Vol 16 (12) ◽  
pp. 1607-1618 ◽  
Author(s):  
C. M. Hall ◽  
A. H. Manson ◽  
C. E. Meek
Keyword(s):  
Energy Dissipation ◽  
Middle Atmosphere ◽  
Spectral Characteristics ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Spectral Signature ◽  
Upper Limits ◽  
Waves And Tides ◽  
Signal Fading ◽  
Mf Radar

Abstract. The spring of 1997 has represented a stable period of operation for the joint University of Tromsø / University of Saskatchewan MF radar, being between refurbishment and upgrades. We examine the horizontal winds from the February to June inclusive and also include estimates of energy dissipation rates derived from signal fading times and presented as upper limits on the turbulent energy dissipation rate, ε. Here we address the periodicity in the dynamics of the upper mesosphere for time scales from hours to one month. Thus, we are able to examine the changes in the spectral signature of the mesospheric dynamics during the transition from winter to summer states.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence; waves and tides).

The evolution of turbulent bursts: the b—ε model

1994 ◽  
Vol 5 (4) ◽  
pp. 537-557 ◽  
Author(s):  
M. Bertsch ◽  
R. Dal Passo ◽  
R. Kersner
Keyword(s):  
Partial Differential Equations ◽  
Energy Dissipation ◽  
Energy Density ◽  
Differential Equations ◽  
Dissipation Rate ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Self Similar ◽  
Similar Solutions ◽  
Semi Empirical

We study the semi-empirical b—ε model which describes the time evolution of turbulent spots in the case of equal diffusivity of the turbulent energy density b and the energy dissipation rate ε. We prove that the system of two partial differential equations possesses a solution, and that after some time this solution exhibits self-similar behaviour, provided that the system has self-similar solutions. The existence of such self-similar solutions depends upon the value of a parameter of the model.

scholarly journals NEW EVIDENCE OF DISCRETE SCALE INVARIANCE IN THE ENERGY DISSIPATION OF THREE-DIMENSIONAL TURBULENCE: CORRELATION APPROACH AND DIRECT SPECTRAL DETECTION

2003 ◽  
Vol 14 (04) ◽  
pp. 459-470 ◽  
Author(s):  
WEI-XING ZHOU ◽  
DIDIER SORNETTE ◽  
VLADILEN PISARENKO
Keyword(s):  
Energy Dissipation ◽  
Three Dimensional ◽  
Energy Dissipation Rate ◽  
Corrections To Scaling ◽  
Developed Turbulence ◽  
Pairwise Correlations ◽  
Spectral Detection ◽  
Simple Variant ◽  
High Reynolds ◽  
New Evidence

We extend the analysis of Ref. 16 showing statistically significant log-periodic corrections to scaling in the moments of the energy dissipation rate in experiments at high Reynolds number (≈ 2500) of three-dimensional fully developed turbulence. First, we develop a simple variant of the canonical averaging method using a rephasing scheme between different samples based on pairwise correlations that confirms Zhou and Sornette's previous results. The second analysis uses a simpler local spectral approach and then performs averages over many local spectra. This yields stronger evidence of the existence of underlying log-periodic undulations, with the detection of more than 20 harmonics of a fundamental logarithmic frequency f = 1.434 ± 0.007 corresponding to the preferred scaling ratio γ = 2.008 ± 0.006.

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