scholarly journals Response of Van Der Pol’s Oscillator to Random Excitation

1959 ◽  
Vol 26 (3) ◽  
pp. 345-348
Author(s):  
T. K. Caughey
Keyword(s):  
Spectral Density ◽  
Natural Frequency ◽  
Narrow Band ◽  
Random Excitation ◽  
Square Root ◽  
Mean Square ◽  
Root Mean Square Amplitude ◽  
Periodic Term ◽  
Noise Term ◽  
Band Noise

Abstract This paper considers the response of Van der Pol’s oscillator to random excitation. It is shown that the output of the oscillator consists of a periodic term, plus a narrow band noise term centered at the natural frequency of the oscillator. The root-mean-square amplitude of this noise term is shown to be proportional to the square root of the spectral density of the excitation, and inversely proportional to the amplitude of self-oscillation.

Mean-Square Response of a Second-Order System to Nonstationary, Random Excitation

1970 ◽  
Vol 37 (3) ◽  
pp. 612-616 ◽  
Author(s):  
L. L. Bucciarelli ◽  
C. Kuo
Keyword(s):  
Narrow Band ◽  
Random Excitation ◽  
Second Order ◽  
Envelope Function ◽  
Order System ◽  
Mean Square ◽  
Forcing Function ◽  
Mean Square Response ◽  
Noise Function ◽  
The Mean

The mean-square response of a lightly damped, second-order system to a type of non-stationary random excitation is determined. The forcing function on the system is taken in the form of a product of a well-defined, slowly varying envelope function and a noise function. The latter is assumed to be white or correlated as a narrow band process. Taking advantage of the slow variation of the envelope function and the small damping of the system, relatively simple integrals are obtained which approximate the mean-square response. Upper bounds on the mean-square response are also obtained.

scholarly journals Susceptibility to Residual Inhibition Is Associated With Hearing Loss and Tinnitus Chronicity

2021 ◽  
Vol 25 ◽  
pp. 233121652098630
Author(s):  
S. Hu ◽  
L. Anschuetz ◽  
D. A. Hall ◽  
M. Caversaccio ◽  
W. Wimmer
Keyword(s):  
Hearing Loss ◽  
Narrow Band ◽  
Acoustic Stimulation ◽  
Normal Hearing ◽  
Short Term ◽  
Factors Associated ◽  
Band Noise ◽  
Comparator Group ◽  
Residual Inhibition ◽  
Subject Comparison

Residual inhibition, that is, the temporary suppression of tinnitus loudness after acoustic stimulation, is a frequently observed phenomenon that may have prognostic value for clinical applications. However, it is unclear in which subjects residual inhibition is more likely and how stable the effect of inhibition is over multiple repetitions. The primary aim of this work was to evaluate the effect of hearing loss and tinnitus chronicity on residual inhibition susceptibility. The secondary aim was to investigate the short-term repeatability of residual inhibition. Residual inhibition was assessed in 74 tinnitus subjects with 60-second narrow-band noise stimuli in 10 consecutive trials. The subjects were assigned to groups according to their depth of suppression (substantial residual inhibition vs. comparator group). In addition, a categorization in normal hearing and hearing loss groups, related to the degree of hearing loss at the frequency corresponding to the tinnitus pitch, was made. Logistic regression was used to identify factors associated with susceptibility to residual inhibition. Repeatability of residual inhibition was assessed using mixed-effects ordinal regression including poststimulus time and repetitions as factors. Tinnitus chronicity was not associated with residual inhibition for subjects with hearing loss, while a statistically significant negative association between tinnitus chronicity and residual inhibition susceptibility was observed in normal hearing subjects (odds ratio: 0.63; p = .0076). Moreover, repeated states of suppression can be stably induced, reinforcing the use of residual inhibition for within-subject comparison studies.

scholarly journals IndoorPlant: A Model for Intelligent Services in Indoor Agriculture Based on Context Histories

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1631
Author(s):  
Bruno Guilherme Martini ◽  
Gilson Augusto Helfer ◽  
Jorge Luis Victória Barbosa ◽  
Regina Célia Espinosa Modolo ◽  
Marcio Rosa da Silva ◽  
...  
Keyword(s):  
Technology Acceptance ◽  
Mean Square Error ◽  
Ease Of Use ◽  
Coefficient Of Determination ◽  
Square Root ◽  
Mean Square ◽  
Use Context ◽  
The Mean ◽  
Acceptance Model ◽  
The Internet Of Things

The application of ubiquitous computing has increased in recent years, especially due to the development of technologies such as mobile computing, more accurate sensors, and specific protocols for the Internet of Things (IoT). One of the trends in this area of research is the use of context awareness. In agriculture, the context involves the environment, for example, the conditions found inside a greenhouse. Recently, a series of studies have proposed the use of sensors to monitor production and/or the use of cameras to obtain information about cultivation, providing data, reminders, and alerts to farmers. This article proposes a computational model for indoor agriculture called IndoorPlant. The model uses the analysis of context histories to provide intelligent generic services, such as predicting productivity, indicating problems that cultivation may suffer, and giving suggestions for improvements in greenhouse parameters. IndoorPlant was tested in three scenarios of the daily life of farmers with hydroponic production data that were obtained during seven months of cultivation of radicchio, lettuce, and arugula. Finally, the article presents the results obtained through intelligent services that use context histories. The scenarios used services to recommend improvements in cultivation, profiles and, finally, prediction of the cultivation time of radicchio, lettuce, and arugula using the partial least squares (PLS) regression technique. The prediction results were relevant since the following values were obtained: 0.96 (R2, coefficient of determination), 1.06 (RMSEC, square root of the mean square error of calibration), and 1.94 (RMSECV, square root of the mean square error of cross validation) for radicchio; 0.95 (R2), 1.37 (RMSEC), and 3.31 (RMSECV) for lettuce; 0.93 (R2), 1.10 (RMSEC), and 1.89 (RMSECV) for arugula. Eight farmers with different functions on the farm filled out a survey based on the technology acceptance model (TAM). The results showed 92% acceptance regarding utility and 98% acceptance for ease of use.

scholarly journals Target detection against narrow band noise backgrounds

1999 ◽  
Vol 39 (13) ◽  
pp. 2191-2203 ◽  
Author(s):  
Mark W. Cannon ◽  
Greg J. Reese ◽  
Steven C. Fullenkamp
Keyword(s):  
Target Detection ◽  
Narrow Band ◽  
Narrow Band Noise ◽  
Band Noise

Calculation of Nonlinear Systems Under Narrow Band Excitation Using Equivalent Linearization and Path Continuation

2021 ◽  
Author(s):  
Alwin Förster ◽  
Lars Panning-von Scheidt
Keyword(s):  
Nonlinear Systems ◽  
Narrow Band ◽  
Gaussian White Noise ◽  
Random Excitation ◽  
Mean Value ◽  
Equivalent Linearization ◽  
Efficient Procedure ◽  
Stochastic Excitations ◽  
Wide Range ◽  
The One

Abstract Turbomachines experience a wide range of different types of excitation during operation. On the structural mechanics side, periodic or even harmonic excitations are usually assumed. For this type of excitation there are a variety of methods, both for linear and nonlinear systems. Stochastic excitation, whether in the form of Gaussian white noise or narrow band excitation, is rarely considered. As in the deterministic case, the calculations of the vibrational behavior due to stochastic excitations are even more complicated by nonlinearities, which can either be unintentionally present in the system or can be used intentionally for vibration mitigation. Regardless the origin of the nonlinearity, there are some methods in the literature, which are suitable for the calculation of the vibration response of nonlinear systems under random excitation. In this paper, the method of equivalent linearization is used to determine a linear equivalent system, whose response can be calculated instead of the one of the nonlinear system. The method is applied to different multi-degree of freedom nonlinear systems that experience narrow band random excitation, including an academic turbine blade model. In order to identify multiple and possibly ambiguous solutions, an efficient procedure is shown to integrate the mentioned method into a path continuation scheme. With this approach, it is possible to track jump phenomena or the influence of parameter variations even in case of narrow band excitation. The results of the performed calculations are the stochastic moments, i.e. mean value and variance.

Search for narrow-band-noise modulations of the infrared transmission of blue bronze

2002 ◽  
Vol 12 (9) ◽  
pp. 85-86
Author(s):  
R. C. Rai ◽  
V. A. Bondarenko ◽  
J. W. Brill
Keyword(s):  
Absorption Coefficient ◽  
Narrow Band ◽  
Diode Lasers ◽  
Infrared Transmission ◽  
Narrow Band Noise ◽  
Band Noise ◽  
Tunable Diode Lasers ◽  
Upper Limits ◽  
Blue Bronze

We have searched for narrow-band-noise (NBN) modulations of the infrared transmission in blue bronze, using tunable diode lasers. No modulations were observed, giving an upper limits for NBN changes in the absorption coefficient of $\Delta \alpha_{NBN} < 0.3 $ / cm ($\approx \alpha/2000$). The implication of these results on proposed CDW properties and NBN mechanisms are discussed.

Lateralization of Narrow-Band Noise by Blind and Sighted Listeners

Perception ◽  
10.1068/p3338 ◽  
2002 ◽  
Vol 31 (7) ◽  
pp. 855-873 ◽  
Author(s):  
Helen J Simon ◽  
Pierre L Divenyi ◽  
Al Lotze
Keyword(s):  
Narrow Band ◽  
Lateral Displacement ◽  
Spatial Hearing ◽  
Binaural Hearing ◽  
Center Frequency ◽  
Intensity Difference ◽  
Sensation Level ◽  
Individual Subject ◽  
Narrow Band Noise ◽  
Band Noise

The effects of varying interaural time delay (ITD) and interaural intensity difference (IID) were measured in normal-hearing sighted and congenitally blind subjects as a function of eleven frequencies and at sound pressure levels of 70 and 90 dB, and at a sensation level of 25 dB (sensation level refers to the pressure level of the sound above its threshold for the individual subject). Using an ‘acoustic’ pointing paradigm, the subject varied the IID of a 500 Hz narrow-band (100 Hz) noise (the ‘pointer’) to coincide with the apparent lateral position of a ‘target’ ITD stimulus. ITDs of 0, ±200, and ±400 μs were obtained through total waveform delays of narrow-band noise, including envelope and fine structure. For both groups, the results of this experiment confirm the traditional view of binaural hearing for like stimuli: non-zero ITDs produce little perceived lateral displacement away from 0 IID at frequencies above 1250 Hz. To the extent that greater magnitude of lateralization for a given ITD, presentation level, and center frequency can be equated with superior localization abilities, blind listeners appear at least comparable and even somewhat better than sighted subjects, especially when attending to signals in the periphery. The present findings suggest that blind listeners are fully able to utilize the cues for spatial hearing, and that vision is not a mandatory prerequisite for the calibration of human spatial hearing.

Sign in / Sign up

Export Citation Format

Share Document