Comparison between imposed-periodicity and marching-in-time solutions of helicopter rotor blade steady-state response problem

1992 ◽  
Author(s):  
GRZEGORZ KAWIECKI ◽  
NITHIAM SIVANERI ◽  
TAD JANIK
Keyword(s):  
Steady State ◽  
Rotor Blade ◽  
Helicopter Rotor ◽  
Steady State Response ◽  
State Response ◽  
Helicopter Rotor Blade

A Case Study of the Unsteady Response of a Hingeless Helicopter Rotor Blade

2019 ◽  
Author(s):  
Pratik Sarker ◽  
Uttam K. Chakravarty
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Rotor Blade ◽  
Degrees Of Freedom ◽  
Forced Response ◽  
Helicopter Rotor ◽  
Mode Shapes ◽  
Response Analysis ◽  
Steady State Condition ◽  
Helicopter Rotor Blade

Abstract The helicopter is an essential means of transport for numerous tasks including carrying passengers and equipment, providing air medical services, firefighting, and other military and civil tasks. While in operation, the nature of the unsteady aerodynamic environment surrounding the rotor blades gives rise to a significant amount of vibration to the helicopter. In this study, the unsteady forced response of the Bo 105 hingeless helicopter rotor blade is investigated at the forward flight in terms of the coupled flapping, lead-lag, and torsional deformations. The mathematical model for the steady-state response of the rotor blade is modified to include the unsteady airfoil behavior by using the Theodorsen’s lift deficiency function for three degrees of freedom of motion. The nonlinear mathematical model is solved by the generalized method of lines in terms of the time-varying deflections of the rotor blade. The unsteady airloads are found to create larger deformations compared to that of the steady-state condition for a given advance ratio. The azimuth locations of the peak loadings also vary with different degrees of freedom. The first three natural frequencies and mode shapes of the rotor blade are presented. The model for the forced response analysis is validated by finite element results.

The Auditory Steady-State Response: Full-Term and Premature Neonates

2002 ◽  
Vol 13 (05) ◽  
pp. 260-269 ◽  
Author(s):  
Barbara Cone-Wesson ◽  
John Parker ◽  
Nina Swiderski ◽  
Field Rickards
Keyword(s):  
Steady State ◽  
Premature Infants ◽  
Modulation Frequency ◽  
Otoacoustic Emission ◽  
Full Term ◽  
Steady State Response ◽  
Pass Rates ◽  
Term Infants ◽  
State Response ◽  
Auditory Steady State Response

Two studies were aimed at developing the auditory steady-state response (ASSR) for universal newborn hearing screening. First, neonates who had passed auditory brainstem response, transient evoked otoacoustic emission, and distortion-product otoacoustic emission tests were also tested with ASSRs using modulated tones that varied in frequency and level. Pass rates were highest (> 90%) for amplitude-modulated tones presented at levels ≥ 69 dB SPL. The effect of modulation frequency on ASSR for 500- and 2000-Hz tones was evaluated in full-term and premature infants in the second study. Full-term infants had higher pass rates for 2000-Hz tones amplitude modulated at 74 to 106 Hz compared with pass rates for a 500-Hz tone modulated at 58 to 90 Hz. Premature infants had lower pass rates than full-term infants for both carrier frequencies. Systematic investigation of ASSR threshold and the effect of modulation frequency in neonates is needed to adapt the technique for screening.

scholarly journals Steady State Response of Linear Time Invariant Systems Modeledby Multibond Graphs

2021 ◽  
Vol 11 (4) ◽  
pp. 1717
Author(s):  
Gilberto Gonzalez Avalos ◽  
Noe Barrera Gallegos ◽  
Gerardo Ayala-Jaimes ◽  
Aaron Padilla Garcia
Keyword(s):  
Steady State ◽  
Linear Time ◽  
Direct Determination ◽  
The State ◽  
Steady State Response ◽  
State Variables ◽  
Linear Time Invariant ◽  
State Response ◽  
Time Invariant

The direct determination of the steady state response for linear time invariant (LTI) systems modeled by multibond graphs is presented. Firstly, a multiport junction structure of a multibond graph in an integral causality assignment (MBGI) to get the state space of the system is introduced. By assigning a derivative causality to the multiport storage elements, the multibond graph in a derivative causality (MBGD) is proposed. Based on this MBGD, a theorem to obtain the steady state response is presented. Two case studies to get the steady state of the state variables are applied. Both cases are modeled by multibond graphs, and the symbolic determination of the steady state is obtained. The simulation results using the 20-SIM software are numerically verified.

Decreased Gamma Auditory Steady-State Response Is Associated With Impaired Real-World Functioning in Unmedicated Patients at Clinical High Risk for Psychosis

2020 ◽  
pp. 155005942098270
Author(s):  
Sarah Ahmed ◽  
Jennifer R. Lepock ◽  
Romina Mizrahi ◽  
R. Michael Bagby ◽  
Cory J. Gerritsen ◽  
...  
Keyword(s):  
Steady State ◽  
High Risk ◽  
Functional Impairment ◽  
Real World ◽  
Steady State Response ◽  
Clinical High Risk ◽  
State Response ◽  
Auditory Steady State Response ◽  
Gamma Synchrony ◽  
40 Hz

Aim Deficits in synchronous, gamma-frequency neural oscillations may contribute to schizophrenia patients’ real-world functional impairment and can be measured electroencephalographically using the auditory steady-state response (ASSR). Gamma ASSR deficits have been reported in schizophrenia patients and individuals at clinical high risk (CHR) for developing psychosis. We hypothesized that, in CHR patients, gamma ASSR would correlate with real-world functioning, consistent with a role for gamma synchrony deficits in functional impairment. Methods A total of 35 CHR patients rated on Global Functioning: Social and Role scales had EEG recorded while listening to 1-ms, 93-dB clicks presented at 40 Hz in 500-ms trains, in response to which 40-Hz evoked power and intertrial phase-locking factor (PLF) were measured. Results In CHR patients, lower 40-Hz PLF correlated with lower social functioning. Conclusions Gamma synchrony deficits may be a biomarker of real-world impairment at early stages of the schizophrenia disease trajectory.

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