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 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 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 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 Fundamentals of Signals and Systems Using MATLAB written by Edward W. Kamen and published by Macmillan College. This book was released on 1997 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text presents an accessible yet comprehensive analytical treatment of signals and systems, and also incorporates a strong emphasis on solving problems and exploring concepts using MATLAB

Download or read book Noise Control written by Colin Hansen and published by CRC Press. This book was released on 2005-10-19 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: An excellent learning tool for students and practitioners, this guide to noise control will enable readers to use their knowledge to solve a wide range of industrial noise control problems. Working from basic scientific principles, the author shows how an understanding of sound can be applied to real-world settings, working through several examples in detail and covering good practice in noise control for both new and existing facilities.

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.

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 Noise and Vibration Control written by Leo Leroy Beranek and published by McGraw-Hill Companies. This book was released on 1971 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ventilation for Control of the Work Environment written by William A. Burgess and published by John Wiley & Sons. This book was released on 2004-07-12 with total page 575 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Ventilation Control of the Work Environment incorporates changes in the field of industrial hygiene since the first edition was published in 1982. Integrating feedback from students and professionals, the new edition includes problems sets for each chapter and updated information on the modeling of exhaust ventilation systems, and thus assures the continuation of the book's role as the primary industry textbook. This revised text includes a large amount of material on HVAC systems, and has been updated to reflect the changes in the Ventilation Manual published by ACGIH. It uses both English and metric units, and each chapter concludes with a problem set.

Download or read book NASA SP written by and published by . This book was released on 1993 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acoustic Absorbers and Diffusers written by Trevor J. Cox and published by CRC Press. This book was released on 2009-01-26 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: Absorbers and diffusers are two of the main design tools for altering the acoustic conditions of rooms, semi-enclosed spaces and the outdoor environment. Their correct use is important for delivering high quality acoustics. Unique and authoritative, this book decribes how to effectively measure, model, design and apply diffusers and absorbers. It is a resource for new and experienced acousticians, seeking an understanding of the evolution, characteristics and application of modern diffusers. Absorption is a more established technology and so the book blends traditional designs with modern developments. The book covers practical and theoretical aspects of absorbers and diffusers and is well illustrated with examples of installations and case studies. This new edition brings Acoustic Absorbers and Diffusers up-to-date with current research, practice and standards. New developments in measurement, materials, theory and practice since the first edition (published in 2004) are included. The sections on absorbers are extended to include more about noise control.

Download or read book Foundations of Engineering Acoustics written by Frank J. Fahy and published by Elsevier. This book was released on 2000-09-12 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Foundations of Engineering Acoustics takes the reader on a journey from a qualitative introduction to the physical nature of sound, explained in terms of common experience, to mathematical models and analytical results which underlie the techniques applied by the engineering industry to improve the acoustic performance of their products. The book is distinguished by extensive descriptions and explanations of audio-frequency acoustic phenomena and their relevance to engineering, supported by a wealth of diagrams, and by a guide for teachers of tried and tested class demonstrations and laboratory-based experiments. Foundations of Engineering Acoustics is a textbook suitable for both senior undergraduate and postgraduate courses in mechanical, aerospace, marine, and possibly electrical and civil engineering schools at universities. It will be a valuable reference for academic teachers and researchers and will also assist Industrial Acoustic Group staff and Consultants. Comprehensive and up-to-date: broad coverage, many illustrations, questions, elaborated answers, references and a bibliography Introductory chapter on the importance of sound in technology and the role of the engineering acoustician Deals with the fundamental concepts, principles, theories and forms of mathematical representation, rather than methodology Frequent reference to practical applications and contemporary technology Emphasizes qualitative, physical introductions to each principal as an entrée to mathematical analysis for the less theoretically oriented readers and courses Provides a 'cook book' of demonstrations and laboratory-based experiments for teachers Useful for discussing acoustical problems with non-expert clients/managers because the descriptive sections are couched in largely non-technical language and any jargon is explained Draws on the vast pedagogic experience of the writer

Download or read book A Practical Guide to Noise and Vibration Control for HVAC Systems written by Mark E. Schaffer and published by . This book was released on 1993-01-01 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 Aeronautical Engineering written by and published by . This book was released on 1993 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).

Download or read book Acoustics written by Allan D. Pierce and published by Springer. This book was released on 2019-06-22 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt: This corrected version of the landmark 1981 textbook introduces the physical principles and theoretical basis of acoustics with deep mathematical rigor, concentrating on concepts and points of view that have proven useful in applications such as noise control, underwater sound, architectural acoustics, audio engineering, nondestructive testing, remote sensing, and medical ultrasonics. Since its publication, this text has been used as part of numerous acoustics-related courses across the world, and continues to be used widely today. During its writing, the book was fine-tuned according to insights gleaned from a broad range of classroom settings. Its careful design supports students in their pursuit of a firm foundation while allowing flexibility in course structure. The book can easily be used in single-term or full-year graduate courses and includes problems and answers. This rigorous and essential text is a must-have for any practicing or aspiring acoustician.