A new primitive ray‐tracing (PRT) model to compute forward and inverse acoustic propagation in a two‐dimensional, range‐dependent, sound‐speed field

2004 ◽  
Vol 116 (4) ◽  
pp. 2550-2550
Author(s):  
Sergey V. Vinogradov ◽  
Jerald W. Caruthers ◽  
Hans E. Ngodock ◽  
Natalia A. Sidorovskaia
Keyword(s):  
Ray Tracing ◽  
Sound Speed ◽  
Acoustic Propagation ◽  
Two Dimensional ◽  
Dimensional Range

An Efficient Coupled-Mode Formulation for Acoustic Propagation in Inhomogeneous Waveguides

2016 ◽  
Vol 24 (01) ◽  
pp. 1550019
Author(s):  
Chunmei Yang ◽  
Wenyu Luo ◽  
Renhe Zhang ◽  
Liangang Lyu ◽  
Fangli Qiao
Keyword(s):  
Water Column ◽  
Sound Speed ◽  
Sound Propagation ◽  
Acoustic Propagation ◽  
Two Dimensional ◽  
Speed Profile ◽  
Benchmark Problem ◽  
Sound Speed Profile ◽  
Coupled Mode ◽  
Sloping Bottom

The direct-global-matrix coupled-mode model (DGMCM) for sound propagation in range-dependent waveguides was recently developed by Luo et al. [A numerically stable coupled-mode formulation for acoustic propagation in range-dependent waveguides, Sci. China G: Phys. Mech. Astron. 55 (2012) 572–588]. A brief review of the formulation and characteristics of this model is given. This paper extends this model to deal with realistic problems involving an inhomogeneous water column and a penetrable sloping bottom. To this end, the normal mode model KRAKEN is adopted to provide local modal solutions and their associated coupling matrices. As a result, the extended DGMCM model is capable of providing full two-way solutions to two-dimensional (2D) realistic problems with a depth- and range-dependent sound speed profile as well as a penetrable sloping bottom. To validate this model, it is first applied to a benchmark problem of sound propagation in a plane-parallel waveguide with a depth- and range-dependent sound speed profile, and then it is applied to a problem involving both an inhomogeneous water column and a sloping bottom. Comparisons with the analytical solution proposed by DeSanto and with the numerical model COUPLE are also provided, which show that the extended DGMCM model is accurate and efficient and hence can serve as a benchmark for realistic problems of sound propagation in an inhomogeneous waveguide.

DEPENDENCE OF THE AXIAL WAVE ON RANGE AND SOUND-SPEED PROFILE PROPERTIES IN A RANGE-INDEPENDENT OCEAN

2005 ◽  
Vol 13 (02) ◽  
pp. 259-278 ◽  
Author(s):  
NATALIE S. GRIGORIEVA ◽  
GREGORY M. FRIDMAN
Keyword(s):  
Numerical Simulation ◽  
Sound Speed ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Speed Profile ◽  
Wave Fields ◽  
Sound Speed Profile ◽  
Average Profile ◽  
Ducted Propagation ◽  
Dimensional Range

For ducted propagation in a waveguide when the source and receiver are placed closely to the depth of the waveguide axis, there exist cusped caustics repeatedly along the axis. In neighborhoods of these cusped caustics, the interference of the wave fields that correspond to near-axial rays occurs. This results in the formation of a coherent structure (the axial wave) that propagates along the waveguide axis like a wave. In this paper the integral representation of the axial wave obtained before for an arbitrary waveguide in a two-dimensional range-independent medium is generalized to a three-dimensional range-independent medium. Through numerical simulation, the dependencies of the axial wave on range, sound-speed profile properties, and geometry of the experiment are studied for two sound-speed profiles: the average profile from the AET experiment and the Munk canonical profile. The sound source frequency is taken equal to 75 Hz; the propagation range is up to 3250 km. The strong difference between shapes of the axial wave for the average profile from the AET experiment and the Munk canonical profile is shown for all the examined models.

Collaborating Ray Tracing and AI Model for AUV-Assisted 3-D Underwater Sound-Speed Inversion

2021 ◽  
pp. 1-19
Author(s):  
Wei Huang ◽  
Mingliu Liu ◽  
Deshi Li ◽  
Feng Yin ◽  
Haole Chen ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Sound Speed ◽  
Underwater Sound

scholarly journals Encoding Two-Dimensional Range Top-k Queries

Algorithmica ◽  
2021 ◽  
Author(s):  
Seungbum Jo ◽  
Rahul Lingala ◽  
Srinivasa Rao Satti
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Upper Bound ◽  
Total Order ◽  
Two Dimensional ◽  
Information Theoretic ◽  
Cartesian Tree ◽  
Dimensional Range

AbstractWe consider the problem of encoding two-dimensional arrays, whose elements come from a total order, for answering $${\text{Top-}}{k}$$ Top- k queries. The aim is to obtain encodings that use space close to the information-theoretic lower bound, which can be constructed efficiently. For an $$m \times n$$ m × n array, with $$m \le n$$ m ≤ n , we first propose an encoding for answering 1-sided $${\textsf {Top}}{\text {-}}k{}$$ Top - k queries, whose query range is restricted to $$[1 \dots m][1 \dots a]$$ [ 1 ⋯ m ] [ 1 ⋯ a ] , for $$1 \le a \le n$$ 1 ≤ a ≤ n . Next, we propose an encoding for answering for the general (4-sided) $${\textsf {Top}}{\text {-}}k{}$$ Top - k queries that takes $$(m\lg {{(k+1)n \atopwithdelims ()n}}+2nm(m-1)+o(n))$$ ( m lg ( k + 1 ) n n + 2 n m ( m - 1 ) + o ( n ) ) bits, which generalizes the joint Cartesian tree of Golin et al. [TCS 2016]. Compared with trivial $$O(nm\lg {n})$$ O ( n m lg n ) -bit encoding, our encoding takes less space when $$m = o(\lg {n})$$ m = o ( lg n ) . In addition to the upper bound results for the encodings, we also give lower bounds on encodings for answering 1 and 4-sided $${\textsf {Top}}{\text {-}}k{}$$ Top - k queries, which show that our upper bound results are almost optimal.

Methods to Accelerate Ray Tracing in the Monte Carlo Method for Surface-to-Surface Radiation Transport

2006 ◽  
Vol 128 (9) ◽  
pp. 945-952 ◽  
Author(s):  
Sandip Mazumder
Keyword(s):  
Monte Carlo ◽  
Ray Tracing ◽  
Radiation Transport ◽  
Three Dimensional ◽  
Intersection Point ◽  
Surface Radiation ◽  
Computational Domain ◽  
Two Dimensional ◽  
Spatial Partitioning ◽  
The Monte Carlo Method

Two different algorithms to accelerate ray tracing in surface-to-surface radiation Monte Carlo calculations are investigated. The first algorithm is the well-known binary spatial partitioning (BSP) algorithm, which recursively bisects the computational domain into a set of hierarchically linked boxes that are then made use of to narrow down the number of ray-surface intersection calculations. The second algorithm is the volume-by-volume advancement (VVA) algorithm. This algorithm is new and employs the volumetric mesh to advance the ray through the computational domain until a legitimate intersection point is found. The algorithms are tested for two classical problems, namely an open box, and a box in a box, in both two-dimensional (2D) and three-dimensional (3D) geometries with various mesh sizes. Both algorithms are found to result in orders of magnitude gains in computational efficiency over direct calculations that do not employ any acceleration strategy. For three-dimensional geometries, the VVA algorithm is found to be clearly superior to BSP, particularly for cases with obstructions within the computational domain. For two-dimensional geometries, the VVA algorithm is found to be superior to the BSP algorithm only when obstructions are present and are densely packed.

scholarly journals The reliability and validity of upper quadrant posture and two-dimensional range of motion measurement tools

2008 ◽  
Vol 64 (3) ◽  
Author(s):  
S. Van Niekerk ◽  
Q. Louw
Keyword(s):  
Reliability And Validity ◽  
Two Dimensional ◽  
Research Projects ◽  
Validity And Reliability ◽  
Research Setting ◽  
Motion Measurement ◽  
Measurement Tools ◽  
Specific Project ◽  
Posture Measurement ◽  
Dimensional Range

Measuring upper quadrant posture and movement is a challenge to researchers and clinicians. A  range of postural measurement tools is commonly used in the clinical setting and in research projects to evaluate postural align-ment, but information about the validity and reliability of these tools and thus as election of the optimal tool for a specific project is often uncertain. This reviewaims to make recommendations to clinicians and researchers regarding practical,valid and reliable tools to assess upper quadrant posture and range of motion.Electronic databases and key journals were searched. An adapted appraisal toolwas utilised to assess the methodology for each of the nine selected articles. Nine eligible articles reporting on thegoniometer, flexicurve and inclinometer were included. This review highlights the fact that a range of two-dimensional(2D) posture measurement tools are being used in clinical practice and research. Although the findings for the reliability and validity of the tools included in this review appear to be promising, strong recommendations are limited by the imprecision of the results. Thus, the primary issue hampering the recommendation for the most reliable and valid tool to use in the clinical or research setting is due to the limitations pertaining the analysis of the data, and the interpretation thereof.

scholarly journals A Spectral Method for Two-Dimensional Ocean Acoustic Propagation

2021 ◽  
Vol 9 (8) ◽  
pp. 892
Author(s):  
Xian Ma ◽  
Yongxian Wang ◽  
Xiaoqian Zhu ◽  
Wei Liu ◽  
Qiang Lan ◽  
...  
Keyword(s):  
Numerical Calculation ◽  
Spectral Method ◽  
Collocation Method ◽  
Approximation Error ◽  
Sound Field ◽  
Acoustic Propagation ◽  
Two Dimensional ◽  
Chebyshev Collocation Method ◽  
Chebyshev Collocation ◽  
Wide Range

The accurate calculation of the sound field is one of the most concerning issues in hydroacoustics. The one-dimensional spectral method has been used to correctly solve simplified underwater acoustic propagation models, but it is difficult to solve actual ocean acoustic fields using this model due to its application conditions and approximation error. Therefore, it is necessary to develop a direct solution method for the two-dimensional Helmholtz equation of ocean acoustic propagation without using simplified models. Here, two commonly used spectral methods, Chebyshev–Galerkin and Chebyshev–collocation, are used to correctly solve the two-dimensional Helmholtz model equation. Since Chebyshev–collocation does not require harsh boundary conditions for the equation, it is then used to solve ocean acoustic propagation. The numerical calculation results are compared with analytical solutions to verify the correctness of the method. Compared with the mature Kraken program, the Chebyshev–collocation method exhibits higher numerical calculation accuracy. Therefore, the Chebyshev–collocation method can be used to directly solve the representative two-dimensional ocean acoustic propagation equation. Because there are no model constraints, the Chebyshev–collocation method has a wide range of applications and provides results with high accuracy, which is of great significance in the calculation of realistic ocean sound fields.

Deep Person Detection in Two-Dimensional Range Data

2018 ◽  
Vol 3 (3) ◽  
pp. 2726-2733 ◽  
Author(s):  
Lucas Beyer ◽  
Alexander Hermans ◽  
Timm Linder ◽  
Kai O. Arras ◽  
Bastian Leibe
Keyword(s):  
Range Data ◽  
Two Dimensional ◽  
Person Detection ◽  
Dimensional Range

Flow-dependent modeling of acoustic propagation based on DG-FEM method

2021 ◽  
Author(s):  
Zichen Wang ◽  
Jian Xu ◽  
Xuefeng Zhang ◽  
Can Lu ◽  
Kangkang Jin ◽  
...  
Keyword(s):  
Sound Propagation ◽  
Transmission Loss ◽  
Acoustic Propagation ◽  
Water Area ◽  
Current Speed ◽  
Propagation Model ◽  
Propagation Loss ◽  
Two Dimensional ◽  
Underwater Sound ◽  
Ocean Environment

AbstractThis paper proposes a two-dimensional underwater sound propagation model using the Discontinuous Galerkin Finite Element Method (DG-FEM) to investigate the influence of current on sound propagation. The acoustic field is calculated by the convected wave equation with the current speed parameter. Based on the current speed data from an assimilation model, a two-dimensional coupled acoustic propagation model in the Fram Strait water area is established to observe the variability in propagation loss under different seasonal velocities in the real ocean environment. The transmission loss and signal time structure are examined. The results obtained in different source frequencies are also compared. It appears that the current velocity, time and range variation all have an effect on underwater sound propagation.

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