scholarly journals Recent Developments of Noise Attenuation Using Acoustic Barriers for a Specific Edge Geometry

Computation ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 129
Author(s):  
Mihai Bugaru ◽  
Ovidiu Vasile ◽  
Marian Neagoe
Keyword(s):  
Prediction Method ◽  
Diffraction Theory ◽  
New Method ◽  
Noise Attenuation ◽  
Atmospheric Absorption ◽  
Edge Geometry ◽  
Recent Developments ◽  
Noise Barrier ◽  
Specific Geometry ◽  
Meteorological Effect

The aim of this research is to provide a better prediction for noise attenuation using thin rigid barriers. In particular, the paper presents an analysis on four methods of computing the noise attenuation using acoustic barriers: Maekawa-Tatge formulation, Kurze and Anderson algorithm, Menounou formulation, and the general prediction method (GPM-ISO 9613). Accordingly, to improve the GPM, the prediction computation of noise attenuation was optimized for an acoustic barrier by considering new effects, such as attenuation due to geometrical divergence, ground absorption-reflections, and atmospheric absorption. The new method, modified GPM (MGPM), was tested for the optimization of an y-shape edge geometry of the noise barrier and a closed agreement with the experimental data was found in the published literature. The specific y-shape edge geometry of the noise barrier contributes to the attenuation due to the diffraction phenomena. This aspect is based on the Kirchhoff diffraction theory that contains the Huygens-Fresnel theory, which is applied to a semi-infinite acoustic barrier. The new method MGPM of predicting the noise attenuation using acoustic barriers takes into consideration the next phenomena: The effect of the relative position of the receiver, the effect of the proximity of the source or receiver to the midplane of the barrier, the effect of the proximity of the receiver to the shadow boundary, the effect of ground absorption-reflections, the effect of atmospheric absorption, and the meteorological effect due to downwind. The conclusion of the paper reveals the optimization of the method for computing the noise attenuation using acoustic barriers, including the necessary corrections for ISO-9613 and the Sound PLAN software, as well as the optimization on a case study of a specific geometry of the edge barrier.

scholarly journals Weight Analysis of Influence Factors and Potential Evaluation Method for Chemical Combination Flooding

2018 ◽  
Vol 53 ◽  
pp. 01022
Author(s):  
LIU Zhaoxia ◽  
WANG Qiang ◽  
MA Desheng ◽  
Gaoming ◽  
LIU Wanlu
Keyword(s):  
Evaluation Method ◽  
Influence Factor ◽  
Comprehensive Evaluation ◽  
Influence Factors ◽  
Prediction Method ◽  
Weight Coefficient ◽  
New Method ◽  
Chemical Flooding ◽  
Evaluation Score ◽  
Chemical Combination

In this paper, the weight coefficient of influencing factors for chemical combination flooding is determined by using grey correlation theory. A calculation method for comprehensive evaluation score of chemical combination flooding is established. The influence factor grading and weight grading are combined in this method. By collecting and analysing chemical combination flooding field tests, a prediction method for chemical combination flooding is established by the exponential regression. It reflects the relationship between EOR of the chemical combination flooding and the comprehensive evaluation score. The new method is applied in 6 different reservoirs to evaluate the effect of chemical flooding. The new method determines the weight coefficient of influence factors for chemical combination flooding. It can quickly predict EOR factor of chemical flooding to provide a basis for chemical flooding planning in the field.

Real-Time Prediction Method for Performance Degradation Trend Based on Reliability Experimental Data

2013 ◽  
Vol 321-324 ◽  
pp. 757-761 ◽  
Author(s):  
Chen Liang Song ◽  
Zhen Liu ◽  
Bin Long ◽  
Cheng Lin Yang
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Field Data ◽  
Prediction Method ◽  
Field Method ◽  
Performance Degradation ◽  
New Method ◽  
Time Prediction ◽  
Prediction Result ◽  
The Relationship

According to the real-time prediction for performance degradation trend, the commonly used method is just based on field data. But this methods prediction result will not be so much ideal when the fitting of degradation trend of field data is not good. To solve the problem, the paper introduces a new method which is not only based on field method but also based on reliability experimental data coming from the history experiment. We use the relationship between the field data and reliability experimental data to get the result of the two kinds of data respectively and then get the weights according to the two prediction results. Finally, the final real-time prediction result for performance degradation tendency can obtain by allocating the weights to the two prediction results.

Nonlinear Hydrodynamic Forces on Flexible Structures: A Combined-Force Model

2004 ◽  
Vol 126 (1) ◽  
pp. 78-83 ◽  
Author(s):  
Iftekhar Anam ◽  
Jose M. Roesset
Keyword(s):  
Flexible Structures ◽  
Nonlinear Problems ◽  
Nonlinear Effects ◽  
Diffraction Theory ◽  
Computational Effort ◽  
New Method ◽  
Force Model ◽  
Order Difference ◽  
The Individual ◽  
Better Than

A new combined-force method is suggested to approximate the second-order difference frequency forces from diffraction theory (Φ2 theory) with less computational effort. The new method is formulated by combining two limiting cases of the Φ2 theory; i.e., Newman’s approximation and the slender Φ2 theory. Numerical results show that the new method reproduces the individual nonlinear effects of the Φ2 theory better than the existing approximations. Results of this work also show the limitations of Morison’s equation as the slender-body counterpart of the diffraction theory for nonlinear problems.

Prediction of the Effect of Impeller Trimming on the Hydraulic Performance of Low Specific-Speed Centrifugal Pumps

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
D. G. J. Detert Oude Weme ◽  
M. S. van der Schoot ◽  
N. P. Kruyt ◽  
E. J. J. van der Zijden
Keyword(s):  
Flow Field ◽  
Prediction Method ◽  
Hydraulic Performance ◽  
New Method ◽  
Prediction Methods ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pump Head ◽  
Low Specific Speed ◽  
Specific Speed

The effect of trimming of radial impellers on the hydraulic performance of low specific-speed centrifugal pumps is studied. Prediction methods from literature, together with a new prediction method that is based on the simplified description of the flow field in the impeller, are used to quantify the effect of trimming on the hydraulic performance. The predictions by these methods are compared to measured effects of trimming on the hydraulic performance for an extensive set of pumps for flow rates in the range of 80% to 110% of the best efficiency point. Of the considered methods, the new prediction method is more accurate (even for a large impeller trim of 12%) than the considered methods from literature. The new method generally overestimates the reduction in the pump head after trimming, and hence results less often in impeller trims that are too large when the method is used to determine the amount of trimming that is necessary in order to attain a specified head.

A new method for robust feature extraction of otolith growth marks using fingerprint recognition methods

2005 ◽  
Vol 56 (5) ◽  
pp. 791 ◽  
Author(s):  
M. Palmer ◽  
A. Álvarez ◽  
J. Tomás ◽  
B. Morales-Nin
Keyword(s):  
Image Analysis ◽  
Feature Extraction ◽  
Age Determination ◽  
Fingerprint Recognition ◽  
New Method ◽  
Otolith Growth ◽  
Contour Analysis ◽  
Recent Developments ◽  
Robust Feature Extraction ◽  
Essential Knowledge

Individual and population age structures constitute essential knowledge for proper management of commercial fisheries. Despite the important advances made in age determination using otolith growth structures, there is still a need to improve both precision and accuracy. The problem of increasing precision in age estimations has been addressed via increasing automation in the identification of growth marks. However, approaches based on otolith size, weight, perimeter, and related measurements (including contour analysis) have moderate success in age prediction. Likewise, early attempts of image analysis have reported poor results, both in cases of 1D (grey-intensity profiles) or 2D images. Recent developments in image analysis have broken this trend, and fully automatic techniques could be an alternative for routine ageing in the near future. Here, we propose a new method for 2D feature extraction that provides robust numerical descriptors of the growth structures of otoliths.

Analysis on Traffic Noise Attenuation by Using Sound Barrier

2014 ◽  
Vol 584-586 ◽  
pp. 776-779
Author(s):  
Xian Feng Huang ◽  
Chen Hui Zhu ◽  
Quan Shi
Keyword(s):  
Sound Source ◽  
Insertion Loss ◽  
Traffic Noise ◽  
Noise Attenuation ◽  
Noise Barriers ◽  
Sound Barrier ◽  
Noise Barrier ◽  
Significant Attenuation ◽  
Infinite Line ◽  
Insertion Losses

By applying noise insertion loss predicting model of the noise barriers, influencing factors on insertion loss of the sound barrier are investigated for achieving the significant attenuation effects. In term of the infinite line sound source and the finite length of the barriers, the sound insertion losses with varying parameters are calculated and compared. Finally, the meaningful results indicate that the economic and reasonable height and length of the noise barrier are gained to be beneficial for barrier design.

Applications of noise barriers with a slanted flat-tip jagged cantilever for noise attenuation on a construction site

2017 ◽  
Vol 24 (22) ◽  
pp. 5225-5232 ◽  
Author(s):  
Wang Zhaomeng ◽  
Lim Kian Meng ◽  
Prachee Priyadarshinee ◽  
Lee Heow Pueh
Keyword(s):  
Noise Pollution ◽  
Comfort Level ◽  
Destructive Interference ◽  
Noise Attenuation ◽  
Construction Site ◽  
Cross Sectional ◽  
Sound Fields ◽  
Noise Barrier ◽  
Sectional Profile ◽  
Level Of Living

Construction noise is one of the main sources of noise pollution in many cities, and degrades the comfort level of living spaces. It was previously reported that a noise barrier with a wide “cross-sectional profile” (e.g., T- or Y-shaped) could enhance the noise attenuation performance, and the jagged edge “longitudinal profile” on the top edge of the noise barrier could generate destructive interference sound fields behind the noise barrier, which could further reduce the noise levels. The present paper attempts to study the noise attenuation performances of jagged edge profiles applied on the edge of a cantilever, which was mounted at the top of a commercial passive noise barrier. In addition to the numerical simulations, the full-sized prototypes were also experimentally tested on a construction site with noise generated by a boring machine. Both numerical simulation and experimental results showed that this barrier with slanted flat-tip jagged cantilever would perform better than the traditional barrier having a Straight edge cantilever of same height, with a maximum additional attenuation of 5.0 dBA obtained experimentally. The barrier with a slanted flat-tip jagged cantilever could also extend the shadow zone behind the barrier to higher levels.

A New Reliability Prediction Method Based on Physics of Failure Method for Product Design and Manufacture

2012 ◽  
Vol 548 ◽  
pp. 521-526 ◽  
Author(s):  
Xing Hao Wang ◽  
Jiang Shao ◽  
Xiao Yu Liu
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Calculation ◽  
Computational Cost ◽  
Prediction Method ◽  
New Method ◽  
Reliability Prediction ◽  
Time To Failure ◽  
Physics Of Failure ◽  
First Order ◽  
Environment Stress

Different from the reliability prediction method on handbook, the reliability prediction method based on Physics of Failure (PoF) model takes failure mechanism as theoretical basis, and combines the design in-formation with the environment stress of the product to predict the time to failure. When the uncertain of the parameters is considered to predict the reliability, Monte-Carlo calculation method is always used here. How-ever, the Monte-Carlo method needs large computational cost, especially for large and complicated electronic systems. A new reliability prediction method which combines the first order reliability with the reliability pre-diction method based on PoF model was proposed. The new method utilized the first order method to calculate the position of design point and reliability index, thus Monte-Carlo calculation process was avoided. Example calculation results showed that the new method improves the prediction efficiency without decreasing the accuracy of reliability, thus it is feasible for reliability prediction of electronic product in engineering.

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