scholarly journals Pengaruh dari Direct Field Component pada Ruang Akustik dengan menggunakan SEA Model

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Al Munawir ◽  
Herri Darsan ◽  
Murhaban Murhaban
Keyword(s):  
Field Component ◽  
Model Comparison ◽  
Energy Analysis ◽  
Complex Structure ◽  
Sound Field ◽  
Coupling Loss ◽  
Model Assumption ◽  
Reflection Measurement ◽  
Acoustic Space ◽  
Good Agreement

Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. This study investigates the application of the corrected SEA model in a non-reverberant acoustic space where the direct  field component from the sound source dominates  the total  sound  field rather than  a diffuse field in a reverberant space which the  classical SEA model assumption is based on. A corrected SEA model is proposed where the direct field component in the energy is removed and the power injected in the subsystem considers only the remaining power after the loss at first reflection.  Measurement is conducted a box divided into two rooms separated by a partition with an opening where the condition of reverberant and non-reverberant can conveniently be controlled. In the case of a non-reverberant space where acoustic material was installed inside the wall of the experimental box, the signals are corrected by eliminating the direct field component in the measured impulse response. Using the corrected SEA model, comparison of the coupling loss factor (CLF) with the theory shows good agreement.

The Effect of Direct Field Component on a Statistical Energy Analysis (SEA) Model

2013 ◽  
Vol 471 ◽  
pp. 279-284 ◽  
Author(s):  
Azma Putra ◽  
Al Munawir ◽  
W.M.F.W. Mohamad ◽  
J.I. Mohammad
Keyword(s):  
Field Component ◽  
Energy Analysis ◽  
Complex Structure ◽  
Sound Field ◽  
Injection Technique ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Model Assumption ◽  
Power Injection ◽  
Acoustic Space

Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. The structure is divided into subsystems where the energy in each of the subsystem is assumed to be reverberant. This study investigates the application of SEA model in a 'damped' acoustic space where the direct field component from the sound source dominates the total sound field rather than a diffuse field in a reverberant space which the SEA model assumption is based on. A measurement was conducted in a scaled room divided into two acoustic spaces separated by a partition with an opening. Absorbent materials were installed on the room walls and the power injection technique was implemented to obtain the coupling loss factor (CLF) of the system. It is found that correction of the direct field component from the subsystem energy improves the prediction of the CLF of the system.

scholarly journals An Energy Model for the Calculation of Room Acoustic Parameters in Rectangular Rooms with Absorbent Ceilings

2021 ◽  
Vol 11 (14) ◽  
pp. 6607
Author(s):  
Erling Nilsson ◽  
Emma Arvidsson
Keyword(s):  
Model Comparison ◽  
Field Model ◽  
Energy Analysis ◽  
Sound Field ◽  
Acoustical Parameters ◽  
Acoustic Parameters ◽  
Reverberation Chamber ◽  
Additional Information ◽  
Classroom Configuration ◽  
Speech Clarity

The most common acoustical treatment of public rooms, such as schools, offices, and healthcare premises, is a suspended absorbent ceiling. The non-uniform distribution of the absorbent material, as well as the influence of sound-scattering objects such as furniture or other interior equipment, has to be taken into account when calculating room acoustic parameters. This requires additional information than what is already inherent in the statistical absorption coefficients and equivalent absorption areas provided by the reverberation chamber method ISO 354. Furthermore, the classical diffuse field assumption cannot be expected to be valid in these types of rooms. The non-isotropic sound field has to be considered. In this paper, a statistical energy analysis (SEA) model is derived. The sound field is subdivided into a grazing and non-grazing part where the grazing part refers to waves propagating almost parallel to the suspended ceiling. For estimation of all the inherent parameters in the model, the surface impedance of the suspended ceiling has to be known. A method for estimating the scattering and absorbing effects of furniture and objects is suggested in this paper. The room acoustical parameters reverberation time , speech clarity , and sound strength were calculated with the model and compared with calculations according to the classical diffuse field model. Comparison with measurements were performed for a classroom configuration. With regard to all cases, the new model agrees better with measurements than the classical one.

Statistical energy analysis parameter estimation for different structural junctions of rectangular plates

2016 ◽  
Vol 230 (15) ◽  
pp. 2603-2610 ◽  
Author(s):  
Maruti B Mandale ◽  
P Bangaru Babu ◽  
SM Sawant
Keyword(s):  
Loss Factor ◽  
Energy Analysis ◽  
Rectangular Plates ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Drawing Board ◽  
Board Stage ◽  
Good Agreement ◽  
Coupling Loss Factor ◽  
Loss Factors

In industries, the use of appropriate junctions between components is of paramount interest. Coupling loss factor is one of the important parameters in statistical energy analysis for vibroacoustic analysis of complicated structures in drawing board stage. The values of coupling loss factor were calculated and compared for different junctions. The screwed and bolted junctions were examined for thin rectangular plates of same size. The energy level difference method was used to find coupling loss factors because of its simplicity. These experimentally found coupling loss factors were later compared with analytical solutions. It is noticed that the analytical results are in good agreement with experimental results. It is also observed that coupling loss factor for bolted junction are relatively high than that for screwed junction.

High Amplitude Sound Propagation at Low Frequencies in a Flow Duct Lined With Resonators: A Time Domain Solution

1988 ◽  
Vol 110 (4) ◽  
pp. 545-551 ◽  
Author(s):  
A. Cummings ◽  
I.-J. Chang
Keyword(s):  
Time Domain ◽  
Internal Combustion Engines ◽  
Sound Propagation ◽  
Sound Field ◽  
High Amplitude ◽  
Combustion Engines ◽  
Low Frequencies ◽  
The Time Domain ◽  
Flow Duct ◽  
Good Agreement

A quasi one-dimensional analysis of sound transmission in a flow duct lined with an array of nonlinear resonators is described. The solution to the equations describing the sound field and the hydrodynamic flow in the neighborhood of the resonator orifices is performed numerically in the time domain, with the object of properly accounting for the nonlinear interaction between the acoustic field and the resonators. Experimental data are compared to numerical computations in the time domain and generally very good agreement is noted. The method described here may readily be extended for use in the design of exhaust mufflers for internal combustion engines.

Data-model Comparison for the mid-Pliocene Warm Period

2021 ◽  
Author(s):  
Julia Tindall ◽  
Alan Haywood ◽  
Ulrich Salzmann ◽  
Aisling Dolan
Keyword(s):  
Data Model ◽  
Model Comparison ◽  
Surface Air Temperature ◽  
High Latitudes ◽  
Orbital Forcing ◽  
Local Site ◽  
Modern Analogue ◽  
Intercomparison Project ◽  
Global Mean ◽  
Good Agreement

<p>Modelling results from PlioMIP2 (the Pliocene Model Intercomparison Project Phase 2) focussing on MIS KM5c; ~3.205Ma, suggest that global mean surface air temperature was 1.7 – 5.2 °C higher than the preindustrial.  This warming was amplified at the poles and over land.  The results are in reasonable agreement with paleodata over the ocean.   </p><p>Over the land the situation is more complicated.  Model and data are in very good agreement at lower latitudes, however at high latitudes an initial data-model comparison shows much warmer mPWP temperatures from data than from models.   </p><p>Here we consider possible reasons for this data-model discord at high latitudes.  These include uncertainties in model boundary conditions (such as CO<sub>2 </sub>and orbital forcing), and whether there are local site-specific conditions which need to be accounted for.  We also show that the seasonal cycle in mPWP temperatures at these high latitude sites has no modern analogue.  This could lead to inaccuracies when comparing model derived mean annual temperatures with quantitative climatic estimates from palaeobotanical data using Nearest Living Relative methods.</p>

Estimation of coupling loss factors for rectangular plates with different materials and junctions

2019 ◽  
Vol 50 (9-11) ◽  
pp. 306-312
Author(s):  
Mandale Maruti Bhagwan ◽  
Bangarubabu Popuri
Keyword(s):  
Loss Factor ◽  
Energy Analysis ◽  
Acoustic Analysis ◽  
Composite Plates ◽  
Rectangular Plates ◽  
Coupling Loss ◽  
Tightening Torque ◽  
Essential Parameter ◽  
Coupling Loss Factor ◽  
Loss Factors

In statistical energy analysis, coupling loss factor is the essential parameter for vibro-acoustic analysis of complicated structures. The coupling loss factors have been estimated using energy-level difference method. The tightening torque applied at structural junction has been varied. Higher values of coupling loss factor have been observed for higher tightening torque on bolted junction. The coupling loss factors have been determined for various structural junctions of rectangular composite plates. The riveted and bolted junctions have been examined for composite plates in same plane and size. The coupling loss factors for bolted junction are relatively higher than that for riveted junction of composite plates. The values of coupling loss factors are found to increase with increasing tightening torque applied at structural junctions of composite plates. It is also noted that the experimental results of coupling loss factors for point junctions vary with changes in fiber orientations of composite plates. It is firmly believed that the various findings of the coupling loss factors in this article help for vibro-acoustic analysis of complicated structures.

Prediction of Transient Vibration Envelopes Using Statistical Energy Analysis Techniques

1990 ◽  
Vol 112 (1) ◽  
pp. 127-137 ◽  
Author(s):  
M. L. Lai ◽  
A. Soom
Keyword(s):  
Loss Factor ◽  
Energy Analysis ◽  
A Priori ◽  
Coupled Systems ◽  
Time Varying ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Transient Vibration ◽  
Coupled Plates ◽  
Coupling Loss Factor

The prediction, by the statistical energy analysis (SEA) method, of transient vibration envelopes for coupled systems is investigated. The relation between the time-varying energy transferred between two coupled subsystems and time-varying energies of the subsystems is studied numerically and experimentally. These studies indicate that time-varying energy transmitted between two subsystems is related to the subsystem energies by an apparent time-varying coupling loss factor. It is shown that the apparent coupling loss factor approaches the asymptotic (or steady-state) coupling loss factor as response energies and transferred energies are integrated over progressively larger times. Both the apparent time-varying coupling loss factor and the asymptotic coupling loss factor, determined experimentally, are used in energy balance equations to predict the time-varying vibration envelopes of a system of two point-coupled plates and the results are compared. Although overall response predictions are similar, considerable differences are noted in individual frequency bands. However, no general method for a priori determination of the apparent time-varying coupling loss factor is suggested.

Formulation of SEA parameters using mobility functions

1994 ◽  
Vol 346 (1681) ◽  
pp. 477-488 ◽  
Keyword(s):  
Dynamic Systems ◽  
Energy Analysis ◽  
Statistical Energy Analysis ◽  
Coupling Loss ◽  
Coupled Subsystems ◽  
Power Inputs ◽  
Complex Structural ◽  
General Mobility ◽  
Power And Energy ◽  
Loss Factors

Statistical energy analysis SEA formulates the dynamic response of a system in terms of power and energy variables. The SEA parameters include power inputs; damping loss factors; which control the power dissipated within the system; and coupling loss factors, which control the power transmitted between coupled subsystems. One of the great difficulties in using SEA is the calculation of these parameters. In this paper sea parameters are formulated using general mobility functions. Simplifications that result from averaging the parameters either over frequency or over an ensemble of dynamic systems are presented. These simplifications make it possible to apply SEA to very complex structural-acoustic systems.

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