Optimization Of Acoustic Source Strength In The Problems Of Active Noise Control

Optimization of Acoustic Source Strength in the Problems of Active Noise Control PDF
Author: Josip Lončarić
Publisher:
ISBN:
Size: 13.69 MB
Format: PDF, ePub, Docs
Category : Noise control
Languages : en
Pages : 44
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We consider a problem of eliminating the unwanted time-harmonic noise on a predetermined region of interest. The desired objective is achieved by active means, i.e., by introducing additional sources of sound called control sources, that generate the appropriate annihilating acoustic signal (anti-sound). A general solution for the control sources has been obtained previously in both continuous and discrete formulation of the problem. In the current paper, we focus on optimizing the overall absolute acoustic source strength of the control sources. Mathematically, this amounts to the minimization of multi-variable complex-valued functions in the sense of L1 with conical constraints, which are only 'marginally' convex. The corresponding numerical optimization problem appears very challenging even for the most sophisticated state-of-the-art methodologies, and even when the dimension of the grid is small, and the waves are long. Our central result is that the global L1-optimal solution can, in fact, be obtained without solving the numerical optimization problem. This solution is given by a special layer of monopole sources on the perimeter of the protected region. We provide a rigorous proof of the global L1 minimality for both continuous and discrete optimization problems in the one-dimensional case. We also provide numerical evidence that corroborates our result in the two-dimensional case, when the protected domain is a cylinder. Even though we cannot fully justify it, we believe that the same result holds in the general case, i.e., for multi-dimensional settings and domains of arbitrary shape. We formulate it as a conjecture at the end of the paper.

Computational Science And Its Applications Iccsa 2003

Computational Science and Its Applications   ICCSA 2003 PDF
Author: Vipin Kumar
Publisher: Springer
ISBN: 3540448438
Size: 23.21 MB
Format: PDF
Category : Computers
Languages : en
Pages : 926
View: 5974

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The three-volume set, LNCS 2667, LNCS 2668, and LNCS 2669, constitutes the refereed proceedings of the International Conference on Computational Science and Its Applications, ICCSA 2003, held in Montreal, Canada, in May 2003.The three volumes present more than 300 papers and span the whole range of computational science from foundational issues in computer science and mathematics to advanced applications in virtually all sciences making use of computational techniques. The proceedings give a unique account of recent results in computational science.

Quadratic Optimization In The Problems Of Active Control Of Sound

Quadratic Optimization in the Problems of Active Control of Sound PDF
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723749193
Size: 80.93 MB
Format: PDF, ePub, Mobi
Category : Science
Languages : en
Pages : 32
View: 2700

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We analyze the problem of suppressing the unwanted component of a time-harmonic acoustic field (noise) on a predetermined region of interest. The suppression is rendered by active means, i.e., by introducing the additional acoustic sources called controls that generate the appropriate anti-sound. Previously, we have obtained general solutions for active controls in both continuous and discrete formulations of the problem. We have also obtained optimal solutions that minimize the overall absolute acoustic source strength of active control sources. These optimal solutions happen to be particular layers of monopoles on the perimeter of the protected region. Mathematically, minimization of acoustic source strength is equivalent to minimization in the sense of L(sub 1). By contrast. in the current paper we formulate and study optimization problems that involve quadratic functions of merit. Specifically, we minimize the L(sub 2) norm of the control sources, and we consider both the unconstrained and constrained minimization. The unconstrained L(sub 2) minimization is certainly the easiest problem to address numerically. On the other hand, the constrained approach allows one to analyze sophisticated geometries. In a special case, we call compare our finite-difference optimal solutions to the continuous optimal solutions obtained previously using a semi-analytic technique. We also show that the optima obtained in the sense of L(sub 2) differ drastically from those obtained in the sense of L(sub 1).Loncaric, J. and Tsynkov, S. V. and Bushnell, Dennis M. (Technical Monitor)Langley Research CenterNOISE SPECTRA; ACOUSTIC FREQUENCIES; NOISE REDUCTION; OPTIMIZATION; ACTIVE CONTROL; MATHEMATICAL MODELS; NUMERICAL ANALYSIS; MONOPOLES; SOUND FIELDS; SOUND GENERATORS

Modeling And Simulation Techniques In Structural Engineering

Modeling and Simulation Techniques in Structural Engineering PDF
Author: Samui, Pijush
Publisher: IGI Global
ISBN: 152250589X
Size: 31.36 MB
Format: PDF, ePub, Mobi
Category : Technology & Engineering
Languages : en
Pages : 524
View: 7376

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The development of new and effective analytical and numerical models is essential to understanding the performance of a variety of structures. As computational methods continue to advance, so too do their applications in structural performance modeling and analysis. Modeling and Simulation Techniques in Structural Engineering presents emerging research on computational techniques and applications within the field of structural engineering. This timely publication features practical applications as well as new research insights and is ideally designed for use by engineers, IT professionals, researchers, and graduate-level students.

Numerical Analysis And Applied Mathematics

Numerical Analysis and Applied Mathematics PDF
Author: International Conference on Numerical Analysis and Applied Mathematics
Publisher: American Institute of Physics
ISBN:
Size: 66.37 MB
Format: PDF, Kindle
Category : Computers
Languages : en
Pages : 787
View: 6319

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This volume contains peer-reviewed papers presented at the International Conference on Numerical Analysis and Applied Mathematics 2007, ICNAAM-2007. This conference brought together leading scientists of the international Numerical and Applied Mathematics community. More than 350 papers were submitted to be considered for presentation at ICNAAM-2007. From these submissions, 189 papers were selected after an international peer review by at least two independent reviewers.

Mathematical Reviews

Mathematical Reviews PDF
Author:
Publisher:
ISBN:
Size: 16.61 MB
Format: PDF, ePub, Docs
Category : Mathematics
Languages : en
Pages :
View: 247

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Acoustic Array Systems

Acoustic Array Systems PDF
Author: Mingsian R. Bai
Publisher: John Wiley & Sons
ISBN: 0470828374
Size: 57.11 MB
Format: PDF, Mobi
Category : Science
Languages : en
Pages : 536
View: 5866

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Presents a unified framework of far-field and near-field array techniques for noise source identification and sound field visualization, from theory to application. Acoustic Array Systems: Theory, Implementation, and Application provides an overview of microphone array technology with applications in noise source identification and sound field visualization. In the comprehensive treatment of microphone arrays, the topics covered include an introduction to the theory, far-field and near-field array signal processing algorithms, practical implementations, and common applications: vehicles, computing and communications equipment, compressors, fans, and household appliances, and hands-free speech. The author concludes with other emerging techniques and innovative algorithms. Encompasses theoretical background, implementation considerations and application know-how Shows how to tackle broader problems in signal processing, control, and transudcers Covers both farfield and nearfield techniques in a balanced way Introduces innovative algorithms including equivalent source imaging (NESI) and high-resolution nearfield arrays Selected code examples available for download for readers to practice on their own Presentation slides available for instructor use A valuable resource for Postgraduates and researchers in acoustics, noise control engineering, audio engineering, and signal processing.