Non-white noise generation method for ASE noise simulation in systems with Raman amplification

2009 ◽  
Author(s):  
Nelson J. Muga ◽  
Meire C. Fugihara ◽  
Mario F. S. Ferreira ◽  
Armando Nolasco Pinto
Keyword(s):  
White Noise ◽  
Noise Generation ◽  
Raman Amplification ◽  
Noise Simulation

Finite length white noise generation with an immuno inspired algorithm

2017 ◽  
Vol 69 ◽  
pp. 189-200
Author(s):  
Mateus Giesbrecht ◽  
Celso Pascoli Bottura
Keyword(s):  
White Noise ◽  
Finite Length ◽  
Noise Generation

Numerical Method for Turbomachinery Tonal Noise Generation and Radiation Simulation Using CAA Approach

2008 ◽  
Author(s):  
Mikhail A. Nyukhtikov ◽  
Anton A. Rossikhin ◽  
Vasily V. Sgadlev ◽  
Igor A. Brailko
Keyword(s):  
Numerical Method ◽  
Three Dimensional ◽  
Noise Generation ◽  
Tonal Noise ◽  
3 Dimensional ◽  
Ducted Fan ◽  
Noise Simulation ◽  
Direct Numerical Solution ◽  
Rotor Stator Interaction ◽  
Field Radiation

The numerical method for 3D calculation of the turbomachinery tonal noise generation, propagation and radiation in the near and far fields taking account of the rotor-stator interaction is developed in CIAM. The method is based on the direct numerical solution of three-dimensional Euler equations for disturbances in time or in frequency domain using numerical methods of computational acoustics (CAA). For far-field radiation calculation the Ffowcs Williams method is used. The method is build into CIAM domestic aeroacoustic solver 3DAS (3 Dimensional Acoustics Solver). In this paper we present some examples of our method applications for calculation of rotor-stator interaction and propagation: • Ducted fan tonal noise simulation; • Ducted counter-rotated fan noise simulation; • Low pressure turbine tonal noise simulation.

A DSP-Based Design for Generating Limited White Noise Wave

2010 ◽  
Vol 34-35 ◽  
pp. 1228-1232
Author(s):  
Ming Ma ◽  
Run Jie Shen ◽  
Bing Fang ◽  
Ming Wei Sun ◽  
Wen He
Keyword(s):  
White Noise ◽  
Frequency Domain ◽  
Simulation Experiment ◽  
Amplitude Spectrum ◽  
Random Numbers ◽  
Zero Section ◽  
Signal Source ◽  
External Data ◽  
Noise Simulation ◽  
Data Memory

In this paper, based on the analysis of white noise generation, equably distributed pseudo-random numbers are generated by a method of mixed congruency. In the case that the pseudo-random numbers are taken as the phase spectrum and the amplitude spectrum is equally set, the waveform array of frequency-domain is made up. The array is transformed from frequency-domain to time-domain by the IFFT before stored into the external data memory. Based on the wave generating technology of DDS, the timer interruption of DSP2812 is installed to change the frequency for generating wave .Then the number is taken out from the external memory. The limited white noise is formed by the way of D/A and zero-section maintenance .This generator can be used as signal source in the noise simulation experiment.

scholarly journals Stick-Slip Analysis of a Drill String Subjected to Deterministic Excitation and Stochastic Excitation

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Hongyuan Qiu ◽  
Jianming Yang ◽  
Stephen Butt
Keyword(s):  
White Noise ◽  
Gaussian White Noise ◽  
Element Model ◽  
Random Excitation ◽  
Time Instant ◽  
Drill String ◽  
Stochastic Excitation ◽  
Stick Slip ◽  
Probabilistic Distribution ◽  
Noise Simulation

Using a finite element model, this paper investigates the torsional vibration of a drill string under combined deterministic excitation and random excitation. The random excitation is caused by the random friction coefficients between the drill bit and the bottom of the hole and assumed as white noise. Simulation shows that the responses under random excitation become random too, and the probabilistic distribution of the responses at each discretized time instant is obtained. The two points, entering and leaving the stick stage, are examined with special attention. The results indicate that the two points become random under random excitation, and the distributions are not normal even when the excitation is assumed as Gaussian white noise.

Numerical Investigation of the Low Pressure Compressor Tone Noise of a High Bypass Ratio Turbofan

2020 ◽  
Author(s):  
Anton Rossikhin ◽  
Sergey Pankov ◽  
Victor Mileshin
Keyword(s):  
Frequency Domain ◽  
Computational Method ◽  
Test Facility ◽  
Frequency Domain Method ◽  
Noise Generation ◽  
Operational Conditions ◽  
3 Dimensional ◽  
Noise Simulation ◽  
Bypass Ratio ◽  
Pressure Compressor

Abstract The presented work investigates the tone noise of three booster stages designed for a high bypass ratio turbofan. Calculations were performed at the approach operational conditions. The frequency domain numerical method of multistage turbomachines tone noise simulation, developed in CIAM (Central Institute of Aviation Motors) and implemented in 3DAS (3 Dimensional Acoustics Solver) in-house solver was used. The aim was to perform once again the validation of the computational method and to obtain better understanding of the mechanisms of tone noise generation in multistage turbomachines. The results of the investigation were compared with the experimental data obtained in the CIAM C-3A acoustic test facility. In general satisfactory correspondence between the numerical calculations and the experiment was observed. This can be treated as a significant argument for the validity of the frequency domain method of the multistage turbomachinery tone noise calculations.

Integrated Fractional white Noise as an Alternative to Multifractional Brownian Motion

2007 ◽  
Vol 44 (02) ◽  
pp. 393-408 ◽  
Author(s):  
Allan Sly
Keyword(s):  
Stochastic Process ◽  
Brownian Motion ◽  
White Noise ◽  
Gaussian Process ◽  
Discrete Data ◽  
Hölder Exponent ◽  
Scaling Properties ◽  
Multifractional Brownian Motion ◽  
Local Properties

Multifractional Brownian motion is a Gaussian process which has changing scaling properties generated by varying the local Hölder exponent. We show that multifractional Brownian motion is very sensitive to changes in the selected Hölder exponent and has extreme changes in magnitude. We suggest an alternative stochastic process, called integrated fractional white noise, which retains the important local properties but avoids the undesirable oscillations in magnitude. We also show how the Hölder exponent can be estimated locally from discrete data in this model.

Auditory Selective Attention in Cerebral-Palsied Individuals

1985 ◽  
Vol 16 (4) ◽  
pp. 260-266 ◽  
Author(s):  
Lee Ann Laraway
Keyword(s):  
Selective Attention ◽  
White Noise ◽  
Normal Subjects ◽  
Auditory Selective Attention ◽  
Normal Individuals ◽  
Significant Difference

The purpose of this study was to determine whether there is a statistically significant difference between the auditory selective attention abilities of normal and cerebral-palsied individuals. Twenty-three cerebral-palsied and 23 normal subjects between the ages of 5 and 21 were asked to repeat a series of 30 items consisting of from 2 to 4 digits in the presence of intermittent white noise. Results of the study indicate that cerebral-palsied individuals perform significantly poorer than normal individuals when the stimulus is accompanied by noise. Noise was not a significant factor in the performance of the normal subjects regardless of age.

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