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.

Computation of Unsteady Viscous Marine-Propulsor Blade Flows—Part 2: Parametric Study

1999 ◽  
Vol 121 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Eric G. Paterson ◽  
Fred Stern
Keyword(s):  
Boundary Layer ◽  
Frequency Response ◽  
High Frequency ◽  
Stokes Equations ◽  
Low Frequency ◽  
Driving Mechanism ◽  
Massachusetts Institute Of Technology ◽  
Flapping Foil ◽  
Displacement Thickness ◽  
Institute Of Technology

In this two-part paper, time-accurate solutions of the Reynolds-averaged Navier-Stokes equations are presented, which address through model problems, the response of turbulent propeller-blade boundary layers and wakes to external-flow traveling waves. In Part 1, the Massachusetts Institute of Technology flapping-foil experiment was simulated and the results validated through comparisons with data. The response was shown to be significantly more complex than classical unsteady boundary layer and unsteady lifting flows thus motivating further study. In Part 2, the effects of frequency, waveform, and foil geometry are investigated. The results demonstrate that uniquely different response occurs for low and high frequency. High-frequency response agrees with behavior seen in the flapping-foil experiment, whereas low-frequency response displays a temporal behavior which more closely agrees with classical inviscid-flow theories. Study of waveform and geometry show that, for high frequency, the driving mechanism of the response is a viscous-inviscid interaction created by a near-wake peak in the displacement thickness which, in turn, is directly related to unsteady lift and the oscillatory wake sheet. Pressure waves radiate upstream and downstream of the displacement thickness peak for high frequency flows. Secondary effects, which are primarily due to geometry, include gust deformation due to steady-unsteady interaction and trailing-edge counter-rotating vortices which create a two-layered amplitude and phase-angle profile across the boundary layer.

Application of ABRS to the Hearing-Aid Selection Process

1986 ◽  
Vol 29 (1) ◽  
pp. 120-128 ◽  
Author(s):  
Kathryn A. Beauchaine ◽  
Michael P. Gorga ◽  
Jan K. Reiland ◽  
Lori L. Larson
Keyword(s):  
Frequency Response ◽  
Preliminary Data ◽  
High Frequency ◽  
Selection Process ◽  
Hearing Aid ◽  
Low Frequency ◽  
Evaluation Process ◽  
Acoustic Reflex ◽  
Technical Factors ◽  
Functional Gain

This paper describes preliminary data on the use of click-evoked ABRs in the hearing aid selection process. Four normal-hearing and 4 hearing-impaired subjects were tested with a hearing aid set at three different frequency response settings. Estimates of gain were calculated using shifts in Wave V thresholds, shifts in Wave V latency-level functions, acoustic-reflex measurements, coupler gain measurements, and measurements of functional gain. Results suggest that the click-evoked ABR does not distinguish between differing amounts of low-frequency gain, although reasonable estimates of high-frequency gain appear possible. Also discussed are technical factors that must be considered when using the ABR in the hearing aid evaluation process.

High-Frequency Dynamic Model of a Pre-Loaded Circular Dielectric Electro-Active Polymer Actuator

2013 ◽  
Author(s):  
Micah Hodgins ◽  
Gianluca Rizzello ◽  
Alex York ◽  
Stefan Seelecke
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
High Frequency ◽  
Natural Frequencies ◽  
Mechanical Coupling ◽  
Polymer Actuator ◽  
Validation Tests ◽  
Future Work ◽  
Force Displacement ◽  
Good Agreement

In this work a high-frequency dynamic model of a pre-loaded circular DEAP actuator is developed and experimentally validated. The model is capable of predicting both the static and dynamic response of the actuator. The static response is modeled based on a free energy approach and consists of an Ogden term representing the elastic energy, and a electrical term representing the electrical-mechanical coupling [1]. The addition of viscoelastic elements (spring-dashpot configurations) enables the model to capture the dynamic response. The Ogden coefficients were first identified through a quasi-static force-displacement test of the actuator. A series of validation tests of the actuator at various pre-loads and voltage frequencies showed the model to be in good agreement with the experiments. The model is shown to accurately predict the actuators observed natural frequencies as the pre-deflection and the stiffness of the spring were changed. Future work will include additions to the model to account for relaxation and creep inherent in DEAP material.

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.

SEA Subsystem Property Identification by Periodic FEM Approach

2011 ◽  
Vol 94-96 ◽  
pp. 1979-1982
Author(s):  
Jie Gao ◽  
Ke An Chen
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Periodic Structures ◽  
Low Frequency ◽  
Engineering Method ◽  
Complex Structures ◽  
High Frequency Range ◽  
Frequency Range ◽  
Remarkable Improvement ◽  
Property Identification

A study on SEA properties of periodically stiffened structure was accomplished based on the periodic theory. With application of certain software, a simulation was performed on a common periodically stiffened fuselage structure. The results indicate such modeling approach reflects relatively accurate property of subsystem in mid and high frequency range, while a remarkable improvement could also be expected in low frequency range, especially for complex structures. Such approach was approved as one reliable engineering method for solving dynamic response of periodic structures.

Nonlinear Dynamic Behaviour of the Intervertebral Disc

2013 ◽  
Author(s):  
Giacomo Marini ◽  
Gerd Huber ◽  
Stephen J. Ferguson
Keyword(s):  
Dynamic Response ◽  
Intervertebral Disc ◽  
High Frequency ◽  
Nonlinear Dynamic ◽  
Mechanical Response ◽  
Numerical Models ◽  
Low Frequency ◽  
Upper Body ◽  
Highly Nonlinear ◽  
Flexion Extension

The intervertebral disc, like many collagen-based tissues, has a mechanical response which is highly nonlinear (1). This characteristic is due to both the arrangement and composition of the tissue constituents of the disc (2). Over the past decades several studies have reported the nonlinear response of the disc for different loading scenarios. In particular, past studies were focused on the quasi-static and low frequency (< 10Hz) response to pure and combined cyclic loading, such as axial compression, shear, flexion/extension moment (3–6). The information provided by these studies has been applied in several fields, from the validation of numerical models to the development of disc prostheses. However, such loading conditions are only partially representative of the in-situ load that the intervertebral disc normally experiences. High frequency dynamics stimuli, such as that experienced while driving a car on a rough surface or driving heavy industrial machinery, are also important. It is well known that long-term exposure to vibrational loading is detrimental to normal disc metabolism (7,8). Despite its relevance only a few studies have investigated the dynamic response of the disc to high frequency vibration (9,10) with sometimes different outcomes. In particular, no study has shown an asymmetric, nonlinear dynamic behavior of the system, even though it is evident in quasi-static testing — the well-known tension / compression asymmetry. This aspect is somehow neglected when building rigid body models of the upper body for impact simulation where a Kelvin-Voigt model with linear stiffness is normally used. The aim of this experimental study was therefore to investigate the nonlinear dynamic response of the intervertebral disc to high frequency loadings, taking different pre-loads and displacement amplitude into account.

scholarly journals Evolutionary Mechanism of Frangibility in Social Consensus System Based on Negative Emotions Spread

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yao-feng Zhang ◽  
Hong-ye Duan ◽  
Zhi-lin Geng
Keyword(s):  
High Frequency ◽  
Negative Emotions ◽  
Low Frequency ◽  
Opinion Leaders ◽  
Group Polarization ◽  
Social Consensus ◽  
Evolutionary Mechanism ◽  
The Social ◽  
Simulation Results ◽  
Better Than

To study the social consensus system under the spread of negative emotions, the nonlinear emergence model of frangibility of social consensus system is established based on Multiagent method, and effects of emotions spread frequency, opinion leaders, and shielding behavior of government on the frangibility of social consensus system are revealed. The simulation results show that the low-frequency negative emotions spread is better than the high-frequency one for reducing the frangibility of social consensus system. Low-frequency negative emotions spread will lead to the group polarization, while high frequency will lead to the collapse of system. The joining of opinion leaders who are with negative emotions can promote the frangibility of social consensus system, and collapse speed of social consensus system tends to increase with the influence of opinion leaders. Shielding behavior of government cannot effectively block the spread of negative emotions. On the contrary, it will enhance the frangibility of social consensus system.

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