A High Order, Lumped Parameter, Jet Dynamic Model for the Frequency Response of Laminar Proportional Amplifiers

1981 ◽  
Vol 103 (4) ◽  
pp. 317-323
Author(s):  
T. M. Drzewiecki
Keyword(s):  
Frequency Response ◽  
Dynamic Model ◽  
Low Frequency ◽  
Electrical Circuit ◽  
High Order ◽  
Step Response ◽  
Average Particle ◽  
Laplace Domain ◽  
Lumped Parameter ◽  
Good Agreement

This paper presents a high-order, lumped parameter, jet-dynamic model for laminar proportional amplifiers (LPA’s). The governing equations for the lumped-parameter representation of the flow regimes found in the input of an LPA are derived in the Laplace domain, and an equivalent electrical circuit is obtained. The input governs the overall response of the LPA and may be modeled in its simplest form by five reactive components. The transmission of the signal from input to output is delayed by a transport time (determined by observation of flow visualization of a step response) equal to twice the average particle transit time. A pressure difference is then developed at the splitter that is proportional to the loading and the vent conditions. This signal is acoustically fed back to the control region of the jet, augmenting jet deflection when in phase. The vent inductance is found to have a significant influence on the low-frequency gain. Resonant regions determined by this model correspond closely to edgetone eigenfrequencies reported in the literature. Experimental data have shown good agreement with theory for the amplitude frequency response of LPA’s and excellent agreement for the phase shift. An engineering guide developed for the bandpass characteristics of LPA’s indicates that operating bandwidths of up to 14 kHz can be expected for amplifiers with a nozzle width of 0.25 mm, and ultrasonic operation appears feasible with devices having nozzle widths as large as 0.1 mm.

A Dynamic Model of Electrostrictive Unimorph Actuators for Haptic Devices

2016 ◽  
Author(s):  
Tahzib Safwat ◽  
Ryan Tosto ◽  
Michael D. Grissom ◽  
Christopher D. Rahn
Keyword(s):  
Frequency Response ◽  
Dynamic Model ◽  
Time Domain ◽  
Haptic Feedback ◽  
High Strain ◽  
Piezoelectric Materials ◽  
Domain Model ◽  
Electroactive Polymer ◽  
Step Response ◽  
Compliant Actuators

Piezoelectric materials are commonly found in many devices, but their usage is limited by the low strain and high stiffness of the material. This prevents their use in “soft” applications, such as compliant actuators for haptic feedback devices and wearable technology. The actuation dynamics of a ferro-electric relaxor terpolymer, a type of soft and high strain electroactive polymer (EAP), are examined. This paper studies the unimorph actuator via a linearized time-domain model and experiments to validate the model include step response and frequency response of tip displacement.

Jitter Transmission Analysis and Experimental Research for Frame Structure in the Median and High Frequency Regions

2012 ◽  
Vol 271-272 ◽  
pp. 981-985
Author(s):  
You Yi Wang ◽  
Yang Zhao ◽  
Wen Lai Ma
Keyword(s):  
Dynamic Response ◽  
Frequency Response ◽  
Dynamic Model ◽  
Experimental Research ◽  
High Frequency ◽  
Low Frequency ◽  
Frame Structure ◽  
Wave Method ◽  
Simulation Results ◽  
Theoretical Results

Frame structure is widely used in practical projects. For jitter of the frame structure excited by median and high frequency disturbances, firstly, the dynamic model of thin plate substructure is built by wave method, and then the dynamic model of frame structure is established by combining wave method and substructure technique. At last, the accurate dynamic response was obtained. The simulation of dynamic characteristic is made, and simulation results are compared with FEM results. On this basis, modal experiment and frequency response experiment is done to verify theoretical results. In comparison to FEM, the results by wave method are accurate in low frequency regions, and the results are more accurate in the median and high frequency regions. The experiment proves wave method is correct and effective for jitter transmission analysis of frame structure in the median and high frequency regions.

A Comparison of Four Hearing Aid Measurement Systems

1977 ◽  
Vol 20 (4) ◽  
pp. 718-730
Author(s):  
Thomas H. Townsend ◽  
Daniel M. Schwartz
Keyword(s):  
Frequency Response ◽  
Hearing Aids ◽  
Second Harmonic ◽  
Hearing Aid ◽  
Harmonic Distortion ◽  
Low Frequency ◽  
Total Harmonic Distortion ◽  
Third Harmonic ◽  
Measurement Systems ◽  
Good Agreement

Measurements of hearing aid performance were made using four different electroacoustic systems. Nine hearing aids were evaluated three times in each of the four systems: a standard Bruel and Kjaer apparatus, a Fonix 5000, and both a Phonic Ear HC 1000 and HC 2000. Tests included frequency response and, when possible, total harmonic distortion, second harmonic distortion, and third harmonic distortion. Results were equivalent for frequency response and second harmonic distortion, whereas significant differences occurred for total harmonic distortion and third harmonic distortion at both the low and high frequencies. The degree to which the sum of second harmonic distortion and third harmonic distortion fails to equal the total harmonic distortion was also examined. In the low frequency region, second harmonic distortion plus third harmonic distortion yielded values considerably less than the total harmonic distortion, although good agreement was found in the midfrequencies.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals Impedance Spectroscopy of Lead-Free Ferroelectric Coatings

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 221
Author(s):  
Mariya Aleksandrova ◽  
Ivailo Pandiev
Keyword(s):  
Composite Coatings ◽  
Electrical Circuit ◽  
Ferroelectric Materials ◽  
Piezoelectric Transducers ◽  
Lead Free ◽  
Electrical Behavior ◽  
Oxide Composite ◽  
Before And After ◽  
Frequency Dependences ◽  
Good Agreement

This paper presents impedance measurements of ferroelectric structures involving lead-free oxide and polymer-oxide composite coatings for sensing and energy harvesting applications. Three different ferroelectric materials grown by conventional microfabrication technologies on solid or flexible substrates are investigated for their basic resonant characteristics. Equivalent electrical circuit models are applied to all cases to explain the electrical behavior of the structures, according to the materials type and thickness. The analytical results show good agreement with the experiments carried out on a basic types of excited thin-film piezoelectric transducers. Additionally, temperature and frequency dependences of the dielectric permittivity and losses are measured for the polymer-oxide composite device in relation with the surface morphology before and after introduction of the polymer to the functional film.

scholarly journals Understanding the low frequency response of carbon nanotube thermoacoustic projectors

2021 ◽  
Vol 498 ◽  
pp. 115940
Author(s):  
Prashant Kumar ◽  
Rammohan Sriramdas ◽  
Ali E. Aliev ◽  
John B. Blottman ◽  
Nathanael K. Mayo ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Frequency Response ◽  
Low Frequency
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