scholarly journals Scan and Paint: Theory and Practice of a Sound Field Visualization Method

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Daniel Fernández Comesaña ◽  
Steven Steltenpool ◽  
Graciano Carrillo Pousa ◽  
Hans-Elias de Bree ◽  
Keith R. Holland
Keyword(s):  
Particle Velocity ◽  
Sound Pressure ◽  
Sound Field ◽  
Theory And Practice ◽  
Acoustic Intensity ◽  
Practical Applications ◽  
Transfer Path ◽  
Sensor Position ◽  
Time Requirements ◽  
Visualization Techniques

Sound visualization techniques have played a key role in the development of acoustics throughout history. The development of measurement apparatus and techniques for displaying sound and vibration phenomena has provided excellent tools for building understanding about specific problems. Traditional methods, such as step-by-step measurements or simultaneous multichannel systems, have a strong tradeoff between time requirements, flexibility, and cost. However, if the sound field can be assumed time stationary, scanning methods allow us to assess variations across space with a single transducer, as long as the position of the sensor is known. The proposed technique, Scan and Paint, is based on the acquisition of sound pressure and particle velocity by manually moving a P-U probe (pressure-particle velocity sensors) across a sound field whilst filming the event with a camera. The sensor position is extracted by applying automatic color tracking to each frame of the recorded video. It is then possible to visualize sound variations across the space in terms of sound pressure, particle velocity, or acoustic intensity. In this paper, not only the theoretical foundations of the method, but also its practical applications are explored such as scanning transfer path analysis, source radiation characterization, operational deflection shapes, virtual phased arrays, material characterization, and acoustic intensity vector field mapping.

Development of Particle Velocity Transfer Path Analysis

2012 ◽  
Author(s):  
Akira Inoue ◽  
Yosuke Tanabe
Keyword(s):  
Path Analysis ◽  
Particle Velocity ◽  
Velocity Vector ◽  
Degrees Of Freedom ◽  
Sound Pressure ◽  
Simple Method ◽  
Transfer Path ◽  
Rank Ordering ◽  
Transfer Path Analysis ◽  
Velocity Transmission

The transfer path analysis (TPA) in terms of sound pressure has been implemented for decades in many application areas, such as car, train and construction machine. In this article, we propose a transfer path analysis where particle velocity is employed as the measure of TPA. Sound pressure is a scalar quantity, while particle velocity, which is the other fundamental quantity of sound, is a vector quantity. The phase differences among particle velocity vector components have to be generally considered. For TPA, not only the six degrees-of-freedom of each path motion, but also the three degrees-of-freedom of the particle velocity at the receiver location have to be considered together for an effective path rank ordering. We first propose the formulation of the particle velocity transfer path analysis where the same formulation of the standard sound pressure transfer path analysis is assumed to hold true for each direction of particle velocity. In order to verify the proposed particle velocity transfer path analysis, we carry out an experiment using a simple test box structure. As a result we have found that the error in the particle velocity vector synthesis is acceptably small, and is as small as the error in the standard sound pressure synthesis, which indicates that the same synthesis method can be employed. We then perform rank ordering of the particle velocity transmission paths. Here, a simple method of path rank ordering is applied. Lastly, we briefly discuss sound energy as a measure of TPA.

scholarly journals Sound field separation with sound pressure and particle velocity measurements

2012 ◽  
Vol 132 (6) ◽  
pp. 3818-3825 ◽  
Author(s):  
Efren Fernandez-Grande ◽  
Finn Jacobsen ◽  
Quentin Leclère
Keyword(s):  
Particle Velocity ◽  
Sound Pressure ◽  
Sound Field ◽  
Velocity Measurements ◽  
Field Separation

scholarly journals Time-Domain Sound Field Reproduction with Pressure and Particle Velocity Jointly Controlled

2021 ◽  
Vol 11 (22) ◽  
pp. 10880
Author(s):  
Xuanqi Hu ◽  
Jiale Wang ◽  
Wen Zhang ◽  
Lijun Zhang
Keyword(s):  
Computational Complexity ◽  
Particle Velocity ◽  
Time Domain ◽  
Sound Pressure ◽  
Filter Design ◽  
Sound Field ◽  
Eigenvalue Decomposition ◽  
Spatial Sound ◽  
Complexity Problem ◽  
Reproduction Method

Particle velocity has been introduced to improve the performance of spatial sound field reproduction systems with an irregular loudspeaker array setup. However, existing systems have only been developed in the frequency domain. In this work, we propose a time-domain sound field reproduction method with both sound pressure and particle velocity components jointly controlled. To solve the computational complexity problem associated with the multi-channel setup and the long-length filter design, we adopt the general eigenvalue decomposition-based approach and the conjugate gradient method. The performance of the proposed method is evaluated through numerical simulations with both a regular loudspeaker array layout and an irregular loudspeaker array layout in a room environment.

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

Heuristic Algorithms for Waste Load Allocation in a River Basin

1989 ◽  
Vol 21 (8-9) ◽  
pp. 1057-1064 ◽  
Author(s):  
Vijay Joshi ◽  
Prasad Modak
Keyword(s):  
Dynamic Programming ◽  
Heuristic Algorithms ◽  
Water Quality Management ◽  
User Preferences ◽  
Theory And Practice ◽  
Waste Load Allocation ◽  
Practical Applications ◽  
Waste Load ◽  
On Line ◽  
The One

Waste load allocation for rivers has been a topic of growing interest. Dynamic programming based algorithms are particularly attractive in this context and are widely reported in the literature. Codes developed for dynamic programming are however complex, require substantial computer resources and importantly do not allow interactions of the user. Further, there is always resistance to utilizing mathematical programming based algorithms for practical applications. There has been therefore always a gap between theory and practice in systems analysis in water quality management. This paper presents various heuristic algorithms to bridge this gap with supporting comparisons with dynamic programming based algorithms. These heuristics make a good use of the insight gained in the system's behaviour through experience, a process akin to the one adopted by field personnel and therefore can readily be understood by a user familiar with the system. Also they allow user preferences in decision making via on-line interaction. Experience has shown that these heuristics are indeed well founded and compare very favourably with the sophisticated dynamic programming algorithms. Two examples have been included which demonstrate such a success of the heuristic algorithms.

The pragmatist influence on managerial ideas and practices

2018 ◽  
Author(s):  
Philippe Lorino
Keyword(s):  
Community Of Inquiry ◽  
Public Institutions ◽  
Theory And Practice ◽  
Direct Influence ◽  
Practical Applications ◽  
Corporate World ◽  
Quality Movement ◽  
Reflection In Action ◽  
Process Perspective ◽  
Exploratory Inquiry

A key idea of pragmatism is the inseparability of theory and practice, thought and action. Pragmatism is said to have had few contacts with the organizational world, and few direct practical applications, except in the domain of education. In particular, the pragmatist direct influence on the managerial world is often undervalued. However, pragmatist ideas have had a significant impact on managerial doctrines and can be traced in today’s debates amongst organization practitioners. This chapter studies three of those channels: Follett’s direct or indirect (for example through Chester Barnard’s work) influence on the corporate world as well as the management of public institutions; the stream of action research and reflection-in-action, in particular Donald Schön’s work; and the development of the quality movement as an anti-Taylorian revolution, deeply influenced by pragmatist thinkers (exploratory inquiry, community of inquiry, instrumental mediations, process perspective), more recently distorted into a Taylorian revival under the “lean management” label.

scholarly journals Research on the Manufacturing Quality of Co-Cured Hat-Stiffened Composite Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2747
Author(s):  
Xiangwen Ju ◽  
Jun Xiao ◽  
Dongli Wang ◽  
Cong Zhao ◽  
Xianfeng Wang
Keyword(s):  
Composite Structures ◽  
Sound Pressure ◽  
Integration Method ◽  
Complex Geometry ◽  
Sound Field ◽  
Thickness Measurement ◽  
Curing Process ◽  
The Finite Element Method ◽  
Manufacturing Quality

The stringer-stiffened structure is widely used due to its excellent mechanical properties. Improving the manufacturing quality of stringer-stiffened structure which have complex geometry is important to ensure the bearing capacity of aviation components. Herein, composite hat-stiffened composite structures were manufactured by different filling forms and bladders with various properties, the deformation of silicone rubber bladder in co-curing process was studied by using the finite element method. The thickness measurement at different positions of the hat-stiffened structure was performed to determine the best filling form and bladder property. Moreover, in view of the detection difficulties in R-zone of stringer, numerical simulation was performed to get the sound pressure and impulse response of at the R-zone of stringer by Rayleigh integration method, and an effective equipment which could stably detect the manufacturing quality of R-zone was designed to verify the correctness of sound field simulation and realize the detection of stringer. With the optimum filling form and bladder properties, hat-stiffened composites can be manufactured integrally with improved surface quality and geometric accuracy, based on co-curing process.

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