Diffusion equation modelling for energy flow analysis in reverberation chambers

2021 ◽  
Vol 263 (1) ◽  
pp. 5637-5642
Author(s):  
Ryan Hao ◽  
Ning Xiang
Keyword(s):  
Diffusion Equation ◽  
Energy Flow ◽  
Flow Analysis ◽  
Equation Model ◽  
Computationally Efficient ◽  
Reverberation Chamber ◽  
Sound Fields ◽  
Energy Flows ◽  
Standardized Measurement ◽  
Reverberation Chambers

Noise is a growing concern in the built environment. Sound absorbers are a viable option for noise treatment. However, the characterization of their absorption coefficient in standardized measurement chambers still show challenges for high accuracy as required in practice. In recent years, experimental analysis has shown that assumptions of diffuse sound fields made in well-known reverberation chambers are unfulfilled. Specifically, that sound intensities in chamber-based measurement methods are presumed to be isotropic or diffuse. Diffusion equation models have shown dramatic changes in energy flow in the presence of highly absorptive materials under test. This has been attributed to well-documented inconsistencies reported from reverberation chamber measurements across different laboratories. This work will demonstrate that the diffusion equation model is proving to be a computationally efficient and viable method for predicting sound energy flows, garnering an increasing amount of interest from the acoustical community.

Foundations and Applications of Computer Based Material Flow Networks for Environmental Management

2001 ◽  
pp. 379-396 ◽  
Author(s):  
Andreas Moller ◽  
Bernd Page ◽  
Arno Rolf ◽  
Volker Wohlgemuth
Keyword(s):  
Environmental Management ◽  
Material Flow ◽  
Energy Flow ◽  
Flow Analysis ◽  
Input Output ◽  
Flow Networks ◽  
Common Input ◽  
Energy Flow Analysis ◽  
Energy Flows ◽  
Definition Of

This chapter describes the foundations of Material Flow Networks for environmental management and gives an overview about their application fields. Material Flow Networks describe the flow of materials and energy within a defined system. The representation and evaluation of these material flows - especially when these flows have an impact on our environment and are caused by human business activities - has become one of the most important tasks of the so-called environmental management. The more familiar we become with the material and energy flows, the more we come to understand the relationship between human activities and our natural environment. The kind of techniques and tools required for material and energy flow analysis focuses on understanding the underlying material and energy transformations and the environmental impact of the resulting material and energy flows. Given the above, a possible definition of material and energy flow analysis is the process of collecting material and energy flow data and of computing derived values from the collection of data. The resulting material and energy flow model is a representation of the underlying system. The model must allow the user to evaluate different aspects of a system (see also, Schmidt, 1997): In input/output balances of companies, plants or production processes within the system refers to a site-specific view and a certain period of time, whereas in a life cycle assessment (LCA) a product or service is the item of interest, which usually is far beyond the temporal and spatial dimension of a common input/output balance. In fact, the same system is modelled in both cases, but interpreted with regard to different perspectives and boundaries.

scholarly journals Development of energy flow models to predict sound fields for sound absorbing structures in medium-to-high frequency ranges

2021 ◽  
Vol 13 (3) ◽  
pp. 168781402110046
Author(s):  
Tae-Gyoung Kim ◽  
Suk-Yoon Hong ◽  
Jee-Hun Song ◽  
Hyun-Wung Kwon
Keyword(s):  
Energy Density ◽  
Governing Equation ◽  
High Frequency ◽  
Energy Flow ◽  
Flow Analysis ◽  
Acoustic Energy ◽  
Acoustic Properties ◽  
Experimental Result ◽  
Sound Fields ◽  
Absorbing Materials

Energy flow analysis (EFA) model for the treatment of sound absorbing structures is developed to predict sound fields of engineering systems in medium-to-high frequency ranges. Thus far, EFA for acoustic models has been developed only for low damping media, such as air and water. A new energy flow governing equation is derived in this study by identifying a relationship between energy density gradient and intensity and acoustic energy dissipation for sound absorbing materials. With the developed EFA model, dispersive wave, and loss factors are identified using complex acoustic properties, and they are investigated to make ensure that they reflect the properties of sound absorbing materials. By solving the governing equation, acoustic energy density, and intensity distributions in sound absorbing materials are obtained, and noise analyses are performed for sound absorbing structures. They are compared with those obtained via a conventional method and experimental result for the verification, in which we confirmed that both results agreed well. Furthermore, various sound absorbing structures are analyzed using the developed EFA model to predict sound fields in medium-to-high frequency ranges. It is demonstrated that the developed EFA model is useful for medium-to-high frequency ranges.

scholarly journals Diffusion equation modeling for sound energy flow analysis in multi domain structures

2019 ◽  
Vol 145 (4) ◽  
pp. 2703-2717 ◽  
Author(s):  
Zühre Sü Gül ◽  
Erinç Odabaş ◽  
Ning Xiang ◽  
Mehmet Çalışkan
Keyword(s):  
Diffusion Equation ◽  
Energy Flow ◽  
Flow Analysis ◽  
Equation Modeling ◽  
Sound Energy ◽  
Energy Flow Analysis ◽  
Domain Structures

Energy flow analysis of straw-return agricultural modes in the Central Shaanxi Plain

2013 ◽  
Vol 20 (10) ◽  
pp. 1388-1393
Author(s):  
Bi JIANG ◽  
Fa-Qi WU ◽  
Xi-Hui WU ◽  
Ming LI ◽  
Xiao-Gang TONG
Keyword(s):  
Energy Flow ◽  
Flow Analysis ◽  
Energy Flow Analysis ◽  
Straw Return

Optimization-aided material and energy flow analysis for a low carbon industry

2017 ◽  
Vol 167 ◽  
pp. 1148-1154 ◽  
Author(s):  
Hendrik Lambrecht ◽  
Heidi Hottenroth ◽  
Tobias Schröer ◽  
Frank Schulenburg
Keyword(s):  
Energy Flow ◽  
Flow Analysis ◽  
Low Carbon ◽  
Energy Flow Analysis

Design and Construction of a Small Reverberation Chamber Applied to Absorption and Scattering Acoustic Measurements

2014 ◽  
Vol 1077 ◽  
pp. 197-202
Author(s):  
D. Hernandez ◽  
E.J. Liu ◽  
J.H. Huang ◽  
Y.C. Liu
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Sound Field ◽  
Acoustic Measurements ◽  
Acoustic Characteristics ◽  
Reverberation Chamber ◽  
Scattering Coefficients ◽  
Reverberation Chambers ◽  
The Cost ◽  
Design And Construction

Reverberation chambers are used to create a diffuse incidence sound field, where multiple types of acoustic measurements can be performed. The chambers tend to have a large volume in order to extent the reverberation time. However, this requirement may be conditioned by the cost and the infrastructure limitations. This paper presents the design and construction of a small-scaled reverberation chamber of 3 m3 for middle-high frequency acoustic measurements. On the design, the acoustic characteristics of chamber are confirmed via finite element computer simulation. As case studies, absorption and scattering coefficients of several materials and diffusors are measured. The reverberation times needed for the measurements were obtained by the impulse response integration method. The small reverberation chamber demonstrated to be a reliable tool for middle and high frequency acoustic measurements.

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