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 Effects of Diameter and Cross sectional Partitioning on Active Noise Control in Round Ducts written by Jeremy Michael Slagley and published by . This book was released on 2006 with total page 86 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 the 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. To test those suppositions, a commercially-available ANC system was used to reduce random noise in round ducts having five different diameters. Results showed that insertion loss (IL) ranged from 5 to 30 dB in frequencies ranging from 40--1000 Hz, and varied inversely with size as expected. The same tests were conducted on a rectangular duct with one cross-sectional dimension fixed and one varied at seven different sizes. Results showed similar IL from 5 to 30 dB that varied inversely with size. If smaller diameters have broader frequency ranges that can be controlled with ANC, perhaps one could extend the frequency range for a large cross-section by partitioning it into smaller cross-sections. This hypothesis was tested by two methods of cross-sectional partitioning. Partitioning was achieved in one design by inserting a smaller duct inside a large duct. In a second design, a cross-shaped partition was inserted inside the large duct. ANC IL results were 1.7 to 2 dB better for the large duct partitioned by a smaller inner duct than the large duct alone (p=0.0146 for low frequency and p=0.0333 for high frequency). ANC insertion loss was 5.8 dB better for the large duct partitioned by a cross-shaped splitter at high frequencies than the large duct alone (p=0.0003). However, the cross-shaped partition system was 5.6 dB less effective at low frequencies than the large duct ANC IL alone (p
Download or read book Part II Effects of Cross Sectional Partitioning on Active Noise Control in Round Ducts written by and published by . This book was released on 2006 with total page 37 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 the 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. If smaller diameters have broader frequency ranges that can be controlled with ANC, perhaps one could extend the frequency range for a large cross-section by partitioning it into smaller cross- sections. This hypothesis was tested by two methods of cross-sectional partitioning. Partitioning was achieved in one design by inserting a smaller duct inside a large duct. In a second design, a cross-shaped partition was inserted inside the large duct. ANC IL results were 1.7 to 2 dB better for the large duct partitioned by a smaller inner duct than the large duct alone (p=0.0146 for low frequency and p=0.0333 for high frequency). ANC insertion loss was 5.8 dB better for the large duct partitioned by a cross-shaped splitter at high frequencies than the large duct alone (p=0.0003). However, the cross-shaped partition system was 5.6 dB less effective at low frequencies than the large duct ANC IL alone (p
Download or read book Total Exposure Health written by Kirk A. Phillips and published by CRC Press. This book was released on 2020-05-15 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of the concept of "Total Exposure Health" and presents details on subject areas which make up the framework. It provides in-depth coverage of the science and technology supporting exposure and risk assessment. This includes advances in toxicology and the "-omics" as well as new techniques for exposure assessment. The book concludes with a discussion on bioethics implications, including ethical considerations related to genetic testing. Discusses advances in exposure monitoring Presents a systems biology approach to human exposures Examines how overall well-being translates to worker productivity Considers the link between work-related risk factors and health conditions Covers the study of genomics in precision medicine and exposure science Explores bioethics in genomic studies Aimed at the exposure professionals (industrial hygienists, toxicologists, public health, environmental engineers), geneticists, molecular biologists, engineers and managers in the health and safety industry as well as professionals in the public administration field.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book E Source Technology Atlas Series Commercial space cooling and air handling written by and published by . This book was released on 1997 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Acoustics written by Malcolm J. Crocker and published by John Wiley & Sons. This book was released on 1998-03-09 with total page 1494 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustical engineers, researchers, architects, and designers need a comprehensive, single-volume reference that provides quick and convenient access to important information, answers and questions on a broad spectrum of topics, and helps solve the toughest problems in acoustical design and engineering. The Handbook of Acoustics meets that need. It offers concise coverage of the science and engineering of acoustics and vibration. In more than 100 clearly written chapters, experts from around the world share their knowledge and expertise in topics ranging from basic aerodynamics and jet noise to acoustical signal processing, and from the interaction of fluid motion and sound to infrasound, ultrasonics, and quantum acoustics. Topics covered include: * General linear acoustics * Nonlinear acoustics and cavitation * Aeroacoustics and atmospheric sound * Mechanical vibrations and shock * Statistical methods in acoustics * Architectural acoustics * Physiological acoustics * Underwater sound * Ultrasonics, quantum acoustics, and physical aspects of sound * Noise: its effects and control * Acoustical signal processing * Psychological acoustics * Speech communication * Music and musical acoustics * Acoustical measurements and instrumentation * Transducers The Handbook of Acoustics belongs on the reference shelf of every engineer, architect, research scientist, or designer with a professional interest in the propagation, control, transmission, and effects of sound.
Download or read book Noise Control Engineering Journal written by and published by . This book was released on 1987 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Architectural Acoustics written by Madan Mehta and published by . This book was released on 1999 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by two educators and a practicing acoustical consultant, this reader-friendly book/reference coversall the important issues of architectural acoustics in a single volume --AND features a dual-level presentation that meets the needs of both those seeking depth and rigor, and those requiring a broad, practical perspective. Synthesizing acoustical theory with its practical applications, it provides exhaustivenarrative coverage of the subject (including advanced optional content and extensive mathematical appendixes) and extensivehigh-quality stand-alone illustrations -- for those who need to grasp concepts quickly without wading through long descriptions of complex acoustical phenomena. Explainscomplex acoustical phenomena and their practical details with relative ease. Providesover 500 stand-alone illustrations -- that, together with a cursory reading of the text, enable readers to grasp concepts quickly --without wading through long descriptions of complex acoustical phenomena. Containsa comprehensive list of important formulas in architectural acoustics.
Download or read book ASHRAE Handbook written by and published by . This book was released on 2003 with total page 898 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Noise Control Engineering written by and published by . This book was released on 1988 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Building Environment written by Vaughn Bradshaw and published by John Wiley & Sons. This book was released on 2010-09-29 with total page 593 pages. Available in PDF, EPUB and Kindle. Book excerpt: Get the updated guide to active and passive control systems for buildings. To capitalize on today's rapidly evolving, specialized technologies, architects, designers, builders, and contractors work together to plan the mechanical and electrical equipment that controls the indoor environment of a building. The Building Environment: Active and Passive Control Systems, Third Edition helps you take advantage of design innovations and construction strategies that maximize the comfort, safety, and energy efficiency of buildings. From active HVAC systems to passive methods, lighting to on-site power generation, this updated edition explains how to strategically plan for and incorporate effective, efficient systems in today's buildings. It covers the underlying thermal theories and thermodynamic principles and focuses on design that enhances the building environment and minimizes the impact on the world's environment. The Building Environment goes beyond the ABCs of HVAC and covers: On-site power generation, including wind turbines, solar photovoltaic cells, fuel cells, and more. Plumbing systems, fire protection, signal systems, conveying systems, and architectural acoustics. Procedures and/or formulas for performing heat loss, heat gain, and energy use calculations, determining the rate of heat flow, calculating solar energy utilization, doing load calculations, and more. Details on the latest building codes and standards references. New information on the sustainable design of building systems and energy efficiency, including new technologies. The latest thinking and data on a building's impact on the environment, indoor air quality, and "sick building syndrome." Design economics, including the payback period, life-cycle cost, comparative value analysis, and building commissioning. A practical on-the-job tool for architects, designers, builders, engineers, contractors, and other specialists, this Third Edition is also a great reference for architecture students who will lead tomorrow's design teams.
Download or read book 1995 ASHRAE Handbook written by American Society of Heating, Refrigerating and Air-Conditioning Engineers and published by . This book was released on 1995 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASHRAE Handbook 1981 Fundamentals written by American Society of Heating, Refrigerating and Air-Conditioning Engineers and published by . This book was released on 1981 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Engineering Noise Control written by David A. Bies and published by CRC Press. This book was released on 2017-12-01 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt: This classic and authoritative student textbook contains information that is not over simplified and can be used to solve the real world problems encountered by noise and vibration consultants as well as the more straightforward ones handled by engineers and occupational hygienists in industry. The book covers the fundamentals of acoustics, theoretical concepts and practical application of current noise control technology. It aims to be as comprehensive as possible while still covering important concepts in sufficient detail to engender a deep understanding of the foundations upon which noise control technology is built. Topics which are extensively developed or overhauled from the fourth edition include sound propagation outdoors, amplitude modulation, hearing protection, frequency analysis, muffling devices (including 4-pole analysis and self noise), sound transmission through partitions, finite element analysis, statistical energy analysis and transportation noise. For those who are already well versed in the art and science of noise control, the book will provide an extremely useful reference. A wide range of example problems that are linked to noise control practice are available on www.causalsystems.com for free download.
