4 edition of **Periodic time-domain nonlocal nonreflecting boundary conditions for duct acoustics** found in the catalog.

Periodic time-domain nonlocal nonreflecting boundary conditions for duct acoustics

- 171 Want to read
- 31 Currently reading

Published
**1996** by National Aeronautics and Space Administration, Langley Research Center, National Technical Information Service, distributor in Hampton, Va, [Springfield, Va .

Written in English

- Boundary conditions,
- Domains,
- Euler equations of motion,
- Numerical analysis

**Edition Notes**

Other titles | Periodic time domain nonlocal nonreflecting boundary conditions for duct acoustics. |

Statement | Willie R. Watson and William E. Zorumski. |

Series | NASA technical memorandum -- 110230. |

Contributions | Zorumski, William E., Langley Research Center. |

The Physical Object | |
---|---|

Format | Microform |

Pagination | 1 v. |

ID Numbers | |

Open Library | OL17565426M |

OCLC/WorldCa | 39535732 |

Introduction High-Reynolds’ number turbulent flows contain a broad range of scales of length and time. The largest length scales are related to the problem geometry and associated boundary conditions, whereas it is principally at the smallest length scales that energy is dissipated by molecular viscosity. The different wave fields are then combined using the superposition principle. Also periodic structures can be studied using these strategies. As is the case for 2D structural dynamics, singularities can be present in corner points of the problem domain where discontinuities exist in normal directions or in boundary conditions. This book gives a comprehensive treatment of the fundamental necessary and sufficient conditions for optimality for finite-dimensional, deterministic, optimal control problems. The emphasis is on the geometric aspects of the theory and on illustrating how these methods can be used to solve optimal control problems.

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These boundary conditions are referred to as periodic nonreflecting time-domain boundary conditions. In the following section the physical duct acoustics problem, which is infinite in ex-tent, is described and the initial boundary value problem is formulated.

In section 3, the time-domain computational boundary-condition operators are presented. Periodic time-domain nonlocal nonreflecting boundary conditions for duct acoustics (OCoLC) Material Type: Government publication, National government publication: Document Type: Book: All Authors / Contributors: Willie R Watson; William E Zorumski; Langley Research Center.

Get this from a library. Periodic time-domain nonlocal nonreflecting boundary conditions for duct acoustics. [Willie R Watson; W E Zorumski; Langley Research Center,; United States. National Aeronautics and Space Administration,]. In order to examine the performance of the exact boundary condition, we implement several local boundary conditions at the exit plane and compare the solutions for various values of the parameter commonly used local conditions are () φ(x,t)=0 and () ∂ φ ∂ t −λ 2 p=0.

These conditions will be referred to as BC1 and BC2 in the remainder of the by: SCATTERING PROBLEMS WITH EXACT NONREFLECTING BOUNDARY CONDITIONS LI-LIAN WANG1, BO WANG2 AND XIAODAN ZHAO1 Abstract. This paper is concerned with fast and accurate computation of exterior wave equations truncated via exact circular or spherical nonreﬂecting boundary conditions (NRBCs, which are known to be nonlocal in both time and space).

Time-Domain Implementation of Nonreflecting Boundary-Conditions for the Nonlinear Euler Equations Article in Applied Mathematical Modelling 31(10) October with 23 Reads.

A review of time domain impedance boundary conditions C. Richter Rolls-Royce Deutschland LTD & Co. KG, Eschen Dahlewi tz, Blankenfelde-Mahlow, Germany [email protected] Proceedings of the Acoustics Nantes Conference AprilNantes, France The evaluation of non-reflecting boundary conditions for duct acoustic computation Article in Journal of Sound and Vibration (3) February with 31 Reads How we measure 'reads'.

An exact nonreflecting boundary condition is derived for solutions of the time dependent wave equation in three space dimensions. It holds on a spherical artificial Cited by: This paper reports the development of a time-accurate method for prediction of acoustics in lined ducts.

The multi-dimensional Euler equations are dim Cited by: 9. Math. Study doi: /jms.v1n Vol. 1, No. 1, pp. March On L2-Stability Analysis of Time-Domain Acoustic Scattering Problems with Exact Nonreﬂecting Boundary Conditions Bo Wang1, Li-Lian Wang2,∗ 1 College of Mathematics and Computer Science, Hunan Normal University, Changsha, HunanChinaCited by: 7.

Stability analysis and design of time-domain acoustic impedance boundary conditions for lined duct with mean flow Xin Liu State Key Laboratory of Turbulence and Complex Systems, College of Engineering, Peking University, BeijingChina Xun Huanga).

More generally, the frequency of a periodic waveform is the inverse of its period; F = 1/P or in this example, = / If you would like to hear what this Hz waveform sounds like, click on the graph with your mouse or pointer.

In addition to the frequency of a sound, we can describe its amplitude. In general, small variations in. N2 - Finite Difference Time Domain room acoustics modelling provides accurate emulation of sound propagation within enclosed structures.

Inclusion of frequency-dependent boundary Periodic time-domain nonlocal nonreflecting boundary conditions for duct acoustics book in such models facilitates emulation of realistic sound wave interaction with absorbing surface materials.

The finite‐difference time‐domain (FDTD) recurrence expressions are formulated, and the numerical algorithm developed for underwater acoustic scattering applications, based upon the basic motion equation and the equation of continuity. The boundary condition implementation for both soft and rigid surfaces, and the absorbing boundary conditions on the truncating surface are by: T.

Qiu and F.-J. Sayas, The Costabel-Stephan system of boundary integral equations in the time domain, Math. Comp. 85 (), – ––––, New mapping properties of the time domain electric field integral equation, ESAIM: M2AN, March/m2an/ F.-J.

Sayas, Energy estimates for Galerkin semidiscretizations of time domain boundary integral equations, by: 8. In the case of rigid walls of simple geometry, the wave equation is used, and after the applicable boundary conditions are applied, the solutions for the natural (eigen) frequencies for the modes (standing waves) are found.

See Chapters 4 andand Chapter 6. () Nonreflecting boundary conditions for the Euler equations in a discontinuous Galerkin discretization.

AIAA Scitech Forum. () Investigation of a Local Correlation-based Transition Model in a Newton-Krylov by: To my knowledge you have to receive a signal in the time domain and then take the fft to get the frequency domain out of a signal you are receiving. (Like you have stated) Maybe reducing the sampling rate of your receiver or trying different types of filtering will help you get the speed you want.

Distributed acoustic sensing has been traditionally implemented using optical reflectometry. Here we describe an alternative to the common interrogation approaches.

According to the new method the frequency of the source is varied sinusoidally with time. For a sufficiently high scan frequency there is a position along the fiber, z0, for which the roundtrip time is half the scan period.

Full text of "New trends in turbulence = Turbulence nouveaux aspects: Les Houches, Session LXXIV, 31 July - 1 September " See other formats. A time-domain reflectometer (TDR) is an electronic instrument used to determine the characteristics of electrical lines by observing reflected waveforms.

It can be used to characterize and locate faults in metallic cables (for example, twisted pair wire or coaxial cable).

It can also be used to locate discontinuities in a connector, printed circuit board, or any other electrical path. Full text of "Second Computational Aeroacoustics (CAA) Workshop on Benchmark Problems" See other formats. A novel BOTDA technique for distributed sensing of the Brillouin frequency in optical fibers with cm-order spatial resolution is proposed.

The technique is based upon a simple modulation scheme, requiring only a single long pump pulse for acoustic excitation, and no subsequent interrogating pulse. Instead, the desired spatial mapping of the Brillouin response is extracted by taking the.

DeepDyve is the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. IEICE TRANS. COMMUN., VOL.E89–B, NO.5 MAY LETTER Channel Estimation for OFDM-Based WLANs in the Presence of Wiener Phase Noise and Residual Frequency Oﬀset Yong-Hwa KIM †, Jong-Ho LEE, Nonmembers, and Seong-Cheol KIM†a), Member SUMMARY In orthogonal frequency-division multiplexing (OFDM)- based wireless local area networks (WLANs), phase noise (PHN)and.

dimensional CEM solver using the finite difference time-domain technique. The origin of the CATR co-ordinate system was located at the vertex of the parabolic reflector with the QZ simulations being computed across a transverse plane at z = f where f was the focal length.

IEEE SIGNAL PROCESSING LETTERS, VOL. 11, NO. 6, JUNE On the Use of Phase and Energy for Musical Onset Detection in the Complex Domain Juan P. Bello, Chris Duxbury, Mike Davies, and Mark Sandler, Senior Member, IEEE Abstract—We present a study on the combined use of energy and phase information for the detection of onsets in musical sig-Cited by: S2L2 TELE Experiment 3 2 2.

PREPARATION P1. Sketch the phasor diagram and waveform of a DSB signal s(t) given by equation s(t) = A coswm t coswc t Based on the phasor diagram, try to sketch the envelope R(t) of s(t). Determine the expression of R(t).Are the. RTN in the time domain.

fC is a nontrivial function of the temperature and shows a sharp change near TCO. Such low-frequency noise components riding on the 1/f spectrum also appear when a dc bias is applied above a threshold current density ’Jth there is onset of nonlinear conductivity in the system.

We also ﬁnd that asT. METHODS OF NOISE SUPPRESSION FK DIP (or FAN) FILTERING. In this method the data are transformed into the FK domain either shot by shot (prestack) or by groups of traces (post-stack). Noise is separated from signal and identified in the FK domain.

An appropriate filter is designed, applied and the FK inverse transform is performed. Metrol. Meas. Syst., Vol. XVII (), No. 1, pp. corresponding to 1/f type of noise (Gaussian component) and RTS noise (non-Gaussian component).

The method proposed in this paper utilizes a standardised histogram estimated in the time domain and the Gram-Charlier series. The method identifies the presence of RTS noise but. Journal of Computational Physics Vol Number 2, June, Moshe Rosenfeld and Moshe Israeli and Micha Wolfshtfin A method for solving three-dimensional viscous incompressible flows over slender bodies Robert L.

Lee and Niel K. Madsen A mixed finite element formulation for Maxwell's equations in the time domain H. Chen and V. Patel and S. A Filippov system describing the effect of prey refuge use on a ratio-dependent predator–prey model, Xiaoyan Chen, Lihong Huang in J Math Anal+Appl China A periodic reaction–advection–diffusion model for a stream population, Xiao Yu, Xiao-Qiang Zhao in J Diff Eq Canada A reaction–advection–diffusion system modeling the.

A method for transforming received signals of a microphone array into driving signals of a loudspeaker array for sound field reproduction is needed to achieve real-time sound field transmission systems from the far-end to the near-end.

We recently proposed a transform method using planar or linear microphone and loudspeaker arrays in the spatio-temporal frequency domain, which is more Cited by: 2. This included optimizing the MBE growth conditions of a near-surface quantum wells with emission around nm and fabrication of arrays of various resonant antenna structures.

Pump-probe spectroscopy was used to investigate the coupling effects, and a toy model was used to extract the coupling parameters.

time domain measurements explained in References 1 and 2. Measurements: The heart of indoor radio measurements in the frequency domain is a network analyser which outputs a swept frequency signal and analyses the received signal.

The signal generated by the network analyser is used as the input to a 45dB transmitter RF amplifier. Notes on the boundaries of quadrature domains. NASA Astrophysics Data System (ADS) Verma, Kaushal. We highlight an intrinsic connection between classical quadrature do.

Periodic Time-Domain Nonlocal Nonreflecting Boundary Conditions for Duct Acoustics. NASA Technical Reports Server (NTRS) Watson, Willie R.; Zorumski, William E. Periodic time-domain boundary conditions are formulated for direct numerical simulation of acoustic waves in ducts without flow.

Well-developed frequency-domain boundary. The Pressure Acoustics, Boundary Mode Interface also shares these nodes, with one additional feature described in Boundary, Edge, Point, and Pair Nodes for the Pressure Acoustics, Boundary Mode Interface. For the Pressure Acoustics, Boundary Mode interface, apply the feature to boundaries instead of domains for 3D components.

Noise-domain reflectometry is a type of reflectometry where the reflectometer exploits existing data signals on wiring and does not have to generate any signals itself. Noise-domain reflectometry, like time-domain and spread-spectrum time domain reflectometers, is most often used in identifying the location of wire faults in electrical lines.

Time-domain reflectometers work by generating a.The shadow is formed behind the boundary. 58 Fundamentals of Audio and Acoustics 29 Phase angle Increasing (deg) 1 wavelength time T = 1/f f = 1/T = Tc where, T is the time in seconds, f is frequency in hertz, c is propagation speed in feet or meters.

Figure Together with so-called additional boundary conditions (ABC) nonlocal material parameters ε(ω, q) and μ(ω, q) introduced in [, ] can be used for solving the problem of plane-wave reflection and transmission in some MTM layers (at least at the frequencies up to the first Bragg resonance a = λ eff /) [ ].