Author: Martha J. WillisPublisher:
ISBN:
Category : Acoustic models
Languages : en
Pages :
Book Description
Army Outdoor Sound Propagation Model Development
Author: Martha J. WillisPublisher:
ISBN:
Category : Acoustic models
Languages : en
Pages :
Book Description
Attenuation of Outdoor Sound Propagation Levels by a Snow Cover
Author: Donald Gene AlbertPublisher:
ISBN:
Category : Absorption of sound
Languages : en
Pages : 104
Book Description
Scientific and Technical Aerospace Reports
Author: Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 652
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
An Outdoor Sound Propagation Model in Concert with Geographic Information System Software
Author: Nathan TiptonPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
As industrial technology advances, man-made noise has increasingly contributed to natural soundscapes. To predict how anthropogenic noise can affect natural environments, engineers build acoustic models over a given terrain; however, many current models are not compatible with common Geographic Information System (GIS) software and become outdated due to software version updates, or are written as proprietary packages unavailable to park management. The goal of this study was to create a true open source outdoor sound propagation model compatible with (but not dependent on) outside GIS software. The model was developed using algorithms from ISO 9613-2, an international standard for attenuation of sound during propagation outdoors. The standard accounts for uneven terrain, atmospheric absorption, screening, wind effects, and ground effects; however, the scope of this thesis is limited to the initial three attenuation factors. Geometric and atmospheric attenuation were directly translatable to a three-dimensional terrain. Additional software was developed in order to translate the two-dimensional screening algorithms for simple terrains to three-dimensional complex terrains. Given sound source inputs and locations over an input Digital Elevation Map, GIS compatible file types of spatially explicit sound pressure level predictions were produced by this model. The model was tested using simple simulated terrains of known ISO 9613-2 cases: one barrier and two barriers. Additionally, the model produced preliminary results using real terrain data and natural gas compressor noise as the sound source. Sound maps were displayed over satellite imagery of the sound pressure level data, and a correlation of visitor acceptability to the sound. The results produced by this work demonstrate a preliminary version of an open-source outdoor sound predictive tool with the capability of mapping visitor experience.
Evaluation of Simple Spherical Spreading Model for Near Vertical Acoustical Propagation
Author: John M. NoblePublisher:
ISBN:
Category : Absorption of sound
Languages : en
Pages : 108
Book Description
A comparison study was performed to evaluate the performance of a simple spherical spreading plus molecular absorption model to a more complex acoustic propagation model for near vertical propagation. The problem of near vertical propagation is important since several acoustic detection systems are being developed for the Army. The operational use of a simple acoustic propagation model in the battlefield will allow for fast computation time providing rapid evaluation of the advantage or disadvantage of using the acoustic detection system. However, simple propagation model, more complex models must be that incorporate many effects of the ground and atmosphere on the propagation of sound. This comparison will determine the limitations.
Outdoor Sound Propagation Modelling in Complex Environments: Recent Developments in the Parabolic Equation Method
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 17
Book Description
In complex environments the modelling of outdoor sound propagation implies to take into account the mixed influence of ground characteristics (topography, obstacles, impedance, etc.) and atmospheric conditions (refraction and turbulence). During the last decade significant progress has been made in the modelling of sound propagation over distances ranging from hundreds meters to kilometres, and the agreement between calculated and measured fields has been greatly improved. New developments appear in the parabolic-equation method. In this paper we present a method which evaluates the propagation of an acoustic wave above uneven terrains including realistic meteorological parameters. In our approach the effects of the topography are modelled using appropriate rotated co-ordinates systems in order to treat the non-flat ground as a succession of flat domains. We also examine the influence of scale resolution on numerical simulation of long range sound propagation through the turbulent atmosphere. Currently, we generate the turbulence using a Random Fourier Modes technique, such that the turbulent fluctuation at any point in the medium (either scalar or vectorial in nature) is calculated from the sum of a chosen number of modes. Our model of outdoors sound propagation is validated both with classical numerical benchmark cases and recent outdoor experiments.
Handbook of Environmental Fluid Dynamics, Volume Two
Author: Harindra Joseph FernandoPublisher: CRC Press
ISBN: 1466556013
Category : Science
Languages : en
Pages : 591
Book Description
With major implications for applied physics, engineering, and the natural and social sciences, the rapidly growing area of environmental fluid dynamics focuses on the interactions of human activities, environment, and fluid motion. A landmark for the field, the two-volume Handbook of Environmental Fluid Dynamics presents the basic principles, fundamental flow processes, modeling techniques, and measurement methods used in the study of environmental motions. It also offers critical discussions of environmental sustainability related to engineering. The handbook features 81 chapters written by 135 renowned researchers from around the world. Covering environmental, policy, biological, and chemical aspects, it tackles important cross-disciplinary topics such as sustainability, ecology, pollution, micrometeorology, and limnology. Volume Two: Systems, Pollution, Modeling, and Measurements explores the interactions between engineered structures and anthropogenic activities that affect natural flows, with particular emphasis on environmental pollution. The book covers the numerical methodologies that underpin research, predictive modeling, and cyber-infrastructure developments. It also addresses practical aspects of laboratory experiments and field observations that validate quantitative predictions and help identify new phenomena and processes. As communities face existential challenges posed by climate change, rapid urbanization, and scarcity of water and energy, the study of environmental fluid dynamics becomes increasingly relevant. This volume is a valuable resource for students, researchers, and policymakers working to better understand environmental motions and how they affect and are influenced by anthropogenic activities. See also Handbook of Environmental Fluid Dynamics, Two-Volume Set and Volume One: Overview and Fundamentals.
Attenuation of Outdoor Sound Propagation Levels by a Snow Cover
Author: Donald Gene AlbertPublisher:
ISBN:
Category : Absorption of sound
Languages : en
Pages : 104
Book Description
Development of a Multistream Acoustic Propagation Model Including Scattering by Turbulence
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 79
Book Description
The objective of the ARL research effort in acoustic propagation is to provide the Army with a multistream model for investigating acoustic detection systems operating in a variety of realistic battlefield conditions. The first step is to account for scattering from turbulent regions of the atmosphere with an explicit algorithm. The turbulent region is considered to be a collection of vortices with a distribution of characteristic sizes and velocities and random orientation and position. Each vortex (turbule) is characterized as a known (or assumed) velocity distribution in three dimensional space. The scattering from each turbule is determined by solving the fluid equations. The contribution to the sound pressure level at the detector location of all turbules is summed up accounting for the propagation characteristics of the atmospheric medium. The algorithms devised to model the above picture of the turbulent region are then used in existing (or appropriately modified) propagation models. Progress in incorporating turbulence scattering into the Past Field Program (PFP) acoustic propagation model is recounted in this report. (MM).
Author: Martin Almgren