Download or read book Active Noise Control in Ducts written by Rodney D. Hanze and published by . This book was released on 1991 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Noise Control Technique Application in Air Conditioning Ducts written by Aloysius Decruz and published by . This book was released on 2009 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Noise Control (ANC) is a technique for reducing noise by destructive interference of noise sound wave by out-of-phase secondary sound wave. In air conditioning installations, high frequency noises are effectively attenuated by porous-structured medium; but the low frequency noise produced by the fan needs a more sophisticated approach. An algorithm, 'Hardware-Tuned Feedback ANC (HTFA)', has been developed to implement the ANC technique for the noise reduction application in an air conditioning duct element, where Digital Signal Processing is used to sample noise and produce a complete anti-phase noise produced by the HTFA algorithm. Typical blade pass frequency in the vicinity of 100 Hz require sampling frequency of minimum twice that value. A 600 MHz fixed point Digital Signal Processor (DSP) from Texas Instrument, TMS320C6416DSK, is used to generate a secondary sound field by using an adaptive algorithm of Least Mean Square (LMS) principle for convergence. A duct section is used for the experiment and the effectiveness of low frequency attenuation by the secondary sound field is measured. Low and medium frequency tonal noises of octave bands 63 Hz - 1000 Hz were tested, low frequency below 250 Hz being the range of interest. Optimum frequency values for which ANC is more effective are determined. It was found that Active Noise Cancellation is effective at 63 Hz and 125 Hz. This is a simple, economic and effective method for noise cancellation compared to existing feed-forward software tuned method.

Download or read book A Study of Acoustic Feedback in Active Noise Control in Ducts written by Paul R. Enderle and published by . This book was released on 1990 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Practical Guide to Noise and Vibration Control for HVAC Systems written by Mark E. Schaffer and published by American Society of Heating Refrigerating and Air-Conditioning Engineers. This book was released on 2005 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: This major revision of the previously published 1991 version provides information for engineers, architects, contractors and other building industry professionals who have little or no experience with acoustical terms or concepts. Presents practical design guidelines to help minimize the possibility of excessive HVAC system noise and vibration in and around buildings, and by suggesting investigation methods to help solve existing noise and vibration problems. ASHRAE Research Project 526.

Download or read book The Active Noise Control of a One dimensional Duct written by Young-Su Lee and published by . This book was released on 1997 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Noise Control written by Kenneth Maurice Jackson and published by . This book was released on 2008 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Noise Control Primer written by Scott D. Snyder and published by Springer Science & Business Media. This book was released on 2012-09-25 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: By providing all the basic knowledge needed to assess how useful active noise control will be for a given problem, this book assists in the designing, setting up, and tuning of an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the text is short and descriptive, leaving all mathematical details and proofs concerning vibrations, signal processing and the like to more advanced texts or research monographs. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include basic acoustics, human perception and sound, sound intensity and related concepts, fundamentals of passive noise- control strategies, basics of digital systems and adaptive controllers, and active noise control systems.

Download or read book Active Noise Control in Ducts Using Adaptive Digital Filters written by Laurent Ludovic Jerome Billet and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fixed filter Designs for Active Noise Control in Ducts written by Prashant Girdharilal Mehta and published by . This book was released on 1996 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Models for Describing Active Noise Control in Ducts written by S. J. Elliott and published by . This book was released on 1984 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Part I Effects of Diameter on Active Noise Control in Rectangular and Round Ducts written by and published by . This book was released on 2006 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active noise control (ANC) is particularly useful in hard-walled ducts where plane waves propagate. Higher order mode waves are much more difficult to control. Basic acoustic principles dictate that tile cut-on frequency at which higher order modes will first begin to eclipse simple plane waves in a duct will be determined by the cross-sectional diameter of the duct. The lowest frequency for higher order modes will increase as duct diameter decreases. Therefore, the range of frequencies where plane waves dominate will be greater and effective control using ANC better as duct diameter decreases. The result is that somewhat higher frequencies can be controlled with ANC for smaller diameters. Below the first higher order mode cut-on frequency for the largest size studied, there should be little difference in ANC effectiveness between the duct sizes. To test those suppositions, a commercially-available ANC system was used to reduce random noise in rectangular and round ducts having different diameters. Results showed that insertion loss (IL) ranged from S to 30 dB in frequencies ranging from 40-1000 Hz, and varied inversely with size as expected. There was no difference in IL below 280 Hz (p=0.7751) between the different diameter ducts. There was a significant difference between duct diameters above 280 Hz (p

Download or read book Active Noise Control in Finite Length Ducts written by M. C. J. Trinder and published by . This book was released on 1985 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active Noise Control in Ducts written by Ian C. Shepherd and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The advantages of active noise control in ducts are well publicised and several laboratory systems are now yielding impressive results. Yet there are relatively few active attenuators employed in industry. This is partly due to some important limitations of active systems but also because potential suppliers and users have not recognised suitable applications. Several systems are described and the most influential performance factors are discussed, so that potential applications can be assessed to determine the performance which can be achieved and the hardware required.

Download or read book The Application of Adaptive Techniques to Duct Active Noise Control written by Mark Johnson and published by . This book was released on 1992 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On line Modeling Techniques for Active Noise Control in the Duct written by Yann-Guang Chyan and published by . This book was released on 1992 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Global Active Noise Control of a One dimensional Acoustic Duct Using a Feedback Controller written by Andrew James Hull and published by . This book was released on 1990 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Modal Concept for Active Noise Control in Circular Or Annular Ducts written by Ulf Tapken and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active control of sound propagation in ducts plays an important role in many technical applications e.g. the attenuation of noise in ventilating system or in the exhaust system of combustion engines. Today many control strategies exist for the simplest case, which is the noise control in the low frequency range in ducts the lateral dimensions of which are small compared to wavelength of sound. Up to the cut-on frequency of the first higher order mode a suppression of the propagating plane sound waves is possible in a broad frequency range. The situation is more difficult when the lateral duct dimensions become large compared to the wavelength as for example in the intake section of an aircraft engine With increasing rotor speed an increasing number of acoustical modes becomes present. This means. the system comprises all increasing number of degrees of freedom. As a consequence. control of the sound field is practicable just in a narrow frequency band or even limited to discrete frequencies.