scholarly journals Continuous Sensing of Water Temperature in a Reservoir with Grid Inversion Method Based on Acoustic Tomography System

2021 ◽  
Vol 13 (13) ◽  
pp. 2633
Author(s):  
Haocai Huang ◽  
Shijie Xu ◽  
Xinyi Xie ◽  
Yong Guo ◽  
Luwen Meng ◽  
...  
Keyword(s):  
Water Temperature ◽  
Grid Method ◽  
Small Scale ◽  
Acoustic Tomography ◽  
Inversion Method ◽  
Sound Waves ◽  
Water Parameters ◽  
Tomography System ◽  
Vertical Slice ◽  
Over Time

The continuous sensing of water parameters is of great importance to the study of dynamic processes in the ocean, coastal areas, and inland waters. Conventional fixed-point and ship-based observing systems cannot provide sufficient sampling of rapidly varying processes, especially for small-scale phenomena. Acoustic tomography can achieve the sensing of water parameter variations over time by continuously using sound wave propagation information. A multi-station acoustic tomography experiment was carried out in a reservoir with three sound stations for water temperature observation. Specifically, multi-path propagation sound waves were identified with ray tracing using high-precision topography data obtained with ship-mounted ADCP. A new grid inverse method is proposed in this paper for water temperature profiling along a vertical slice. The progression of water temperature variation in three vertical slices between acoustic stations was mapped by solving an inverse problem. The reliability and adaptability of the grid method developed in this research are verified by comparison with layer-averaged water temperature results. The grid method can be further developed for the 3D mapping of water parameters over time, especially in small-scale water areas, where sufficient multi-path propagation sound waves can be obtained.

scholarly journals Short-Range Water Temperature Profiling in a Lake with Coastal Acoustic Tomography

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4498
Author(s):  
Haocai Huang ◽  
Yong Guo ◽  
Guangming Li ◽  
Kaneko Arata ◽  
Xinyi Xie ◽  
...  
Keyword(s):  
Water Temperature ◽  
Short Range ◽  
Moving Average ◽  
Time Windows ◽  
Innovative Technology ◽  
Acoustic Tomography ◽  
Transmission Experiment ◽  
Regularized Inversion ◽  
Vertical Slice ◽  
Tomography Method

Coastal acoustic tomography (CAT), as an innovative technology, can perform water temperature measurements both in horizontal and vertical slices. Investigations on vertical slice observations are significantly fewer in number than horizontal observations due to difficulties in multi-path arrival peak identification. In this study, a two-station sound transmission experiment is carried out in Thousand-Island Lake, Hangzhou, China, to acquire acoustic data for water temperature profiling. Time windows, determined by range-independent ray simulation, are used to identify multi-path arrival peaks and obtain corresponding sound wave travel times. Special attention is paid to travel time correction, whose errors are caused by position drifting by more than 2 m of moored stations. The sound speed and temperature profiling are divided into four layers and are calculated by regularized inversion. Results show a good consistency with conductivity–temperature–depth (CTD) measurements. The root mean square error (RMSE) of water temperature is 0.3494, 0.6838, 1.0236 and 1.0985 °C for layer 1, 2, 3 and 4, respectively. The fluctuations of measurement are further smoothed by the moving average, which decreases the RMSE of water temperature to 0.2858, 0.4742, 0.7719 and 0.9945 °C, respectively. This study illustrates the feasibility and high accuracy of the coastal acoustic tomography method in short-range water temperature measurement. Furthermore, 3D water temperature field profiling can be performed with combined analyzing in horizontal and vertical slices.

scholarly journals PEMETAAN SUHU LAUT DI PERAIRAN TELUK BALIKPAPAN MENGGUNAKAN TEKNOLOGI AKUSTIK TOMOGRAFI PANTAI

2019 ◽  
Vol 11 (1) ◽  
pp. 25-36
Author(s):  
Teguh Arif Pianto ◽  
Henry M. Manik ◽  
Indra Jaya
Keyword(s):  
Travel Time ◽  
Seawater Temperature ◽  
Temperature Data ◽  
Acoustic Tomography ◽  
Inversion Method ◽  
Time Data ◽  
Sea Temperature ◽  
Tomography System ◽  
Wide Range ◽  
Temperature Depth

ABSTRAKSuhu laut dalam oseanografi merupakan faktor penting yang menunjukkan kualitas suatu perairan sehingga pemetaan secara spasial dan temporal perlu dilakukan. Salah satu teknologi yang potensial efektif untuk dapat digunakan dalam melakukan pemetaan suhu laut adalah dengan menggunakan teknologi akustik tomografi pantai Coastal Acoustic Tomography system (CATs). Penerapan teknologi akustik tomografi pantai di perairan teluk Balikpapan belum pernah dilakukan sebelumnya. Teknologi ini dapat menjangkau daerah yang luas dan dapat melakukan pemetaan suhu laut perlapisan kedalaman dengan resolusi temporal permenit. Tujuan dari penelitian ini adalah untuk merekonstruksi data akustik tomografi untuk mendapatkan nilai suhu laut dari data waktu tempuh yang diperoleh antar pasangan stasiun sehingga menjadi peta sebaran suhu laut di jejaring CATs. Penelitian dilakukan dengan menempatkan 4 stasiun akustik yang direkonstruksi melalui metode inversi dari waktu tempuh akustik yang diperoleh antar pasangan stasiun dan suhu rata-rata di lintasan terbentuk menggunakan formula Mackenzie. Hasil rekonstruksi suhu rata-rata pada lintasan jejaring CATs berkisar 28oC sampai 30oC. Uji validasi data suhu laut hasil pengukuran dengan metoda akustik tomografi pantai dengan alat ukur CTD (Conductivity Temperature Depth) diperoleh akurasi antara nilai suhu laut hasil pengukuran dengan data CTD mencapai 98%, nilai koefisien korelasi R=0,79. Kesimpulan penelitian didapati bahwa rekonstruksi data Akustik Tomografi telah berhasil mengakusisi data suhu laut dengan tingkat ketelitian pada pengukuran yang dilakukan di perairan Teluk Balikapapan mencapai lebih dari 97%. ABSTRACTSea temperature in oceanography is an important factor to figure out the quality of waters that the conducted mapping spatially and temporally. One of the potential technologies effectively can be carried out by mapping sea temperature is a coastal acoustic tomography system (CATs). This technology has never been implemented conducted in Balikpapan Bay before. The technology is able to reach out of a wide range of seawater area and to map sea temperature according to its depth layers.The purpose of this study is to reconstruct tomographic acoustic data to obtain ocean temperature values from travel time data that obtained between pair of stations, so it became a map of sea temperature distribution in CAT’s network. This research was taken by setting four reconstructed observational stations through inversion method of received acoustic travel time among paired stations. The average of temperatures in the formed tracks was analyzed by using Mackenzie formula.The results of reconstructing the seawater temperatures in the CATs tracking networks are in a range of 28oC – 30oC. Aalidation test of the seawater temperature data resulted from coastal acoustic tomography method by using a CTD (Conductivity Temperature Depth) generates the accuracies of the seawater temperature are more than 98% and a correlation coefficient R = 0.79. The finding of the study was the reconstruction of Acoustic Tomography data has succeeded in acquiring sea temperature data with a level of accuracy level of more than 97%.

scholarly journals Layer-Averaged Water Temperature Sensing in a Lake by Acoustic Tomography with a Focus on the Inversion Stratification Mechanism

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7448
Author(s):  
Shijie Xu ◽  
Zhao Xue ◽  
Xinyi Xie ◽  
Haocai Huang ◽  
Guangming Li
Keyword(s):  
Water Temperature ◽  
Fluid Dynamic ◽  
Field Measurements ◽  
Temperature Sensing ◽  
Acoustic Tomography ◽  
Inversion Method ◽  
Average Water Temperature ◽  
Travel Information ◽  
Average Water ◽  
Tomography Method

Continuous sensing of water parameters is of great importance to fluid dynamic progress study in oceans, coastal areas and inland waters. The acoustic tomography technique can perform water temperature field measurements horizontally and vertically using sound wave travel information. The layer-averaged water temperature can also be measured with the acoustic tomography method. However, investigations focusing on the stratified mechanism, which consists of stratification form and its influence on inversion error, are seldom performed. In this study, an acoustic tomography experiment was carried out in a reservoir along two vertical slices to observe the layer-averaged water temperature. Specifically, multi-path sound travel information is identified through ray tracing using high-precision topography data obtained via a ship-mounted ADCP during the experiment. Vertical slices between sound stations are divided into different layers to study layer division inversion methods in different preset types. The inversion method is used to calculate the average water temperature and inversion temperature error of every layer. Different layer methods are studied with a comparison of results. The layer division principle studied in this paper can be used for layer-averaged water temperature sensing with multi-path sound transmission information.

scholarly journals Deep Learning Convolutional Neural Network Applying for the Arctic Acoustic Tomography Current Inversion Accuracy Improvement

2021 ◽  
Vol 9 (7) ◽  
pp. 755
Author(s):  
Kangkang Jin ◽  
Jian Xu ◽  
Zichen Wang ◽  
Can Lu ◽  
Long Fan ◽  
...  
Keyword(s):  
Neural Network ◽  
Deep Learning ◽  
Sea Ice ◽  
Convolutional Neural Network ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Small Scale ◽  
Acoustic Tomography ◽  
Arctic Sea ◽  
Current Inversion

Warm current has a strong impact on the melting of sea ice, so clarifying the current features plays a very important role in the Arctic sea ice coverage forecasting study field. Currently, Arctic acoustic tomography is the only feasible method for the large-range current measurement under the Arctic sea ice. Furthermore, affected by the high latitudes Coriolis force, small-scale variability greatly affects the accuracy of Arctic acoustic tomography. However, small-scale variability could not be measured by empirical parameters and resolved by Regularized Least Squares (RLS) in the inverse problem of Arctic acoustic tomography. In this paper, the convolutional neural network (CNN) is proposed to enhance the prediction accuracy in the Arctic, and especially, Gaussian noise is added to reflect the disturbance of the Arctic environment. First, we use the finite element method to build the background ocean model. Then, the deep learning CNN method constructs the non-linear mapping relationship between the acoustic data and the corresponding flow velocity. Finally, the simulation result shows that the deep learning convolutional neural network method being applied to Arctic acoustic tomography could achieve 45.87% accurate improvement than the common RLS method in the current inversion.

Optimum design of the ocean acoustic tomography system for the Sea of Japan

1994 ◽  
Vol 50 (3) ◽  
pp. 281-293 ◽  
Author(s):  
Arata Kaneko ◽  
Gang Yuan ◽  
Noriaki Gohda ◽  
Iwao Nakano
Keyword(s):  
Optimum Design ◽  
Sea Of Japan ◽  
Acoustic Tomography ◽  
The Sea Of Japan ◽  
Tomography System ◽  
Ocean Acoustic Tomography

scholarly journals Theology at Thresholds: Learning from a Practice ‘In Transition’

2017 ◽  
Vol 4 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Rachel Muers ◽  
Rhiannon Grant
Keyword(s):  
Decision Making ◽  
The Other ◽  
Small Scale ◽  
Theological Ethics ◽  
Reciprocal Influence ◽  
Core Practices ◽  
Recent Developments ◽  
Collective Process ◽  
The One ◽  
Over Time

Recent developments in contemporary theology and theological ethics have directed academic attention to the interrelationships of theological claims, on the one hand, and core community-forming practices, on the other. This article considers the value for theology of attending to practice at the boundaries, the margins, or, as we prefer to express it, the threshold of a community’s institutional or liturgical life. We argue that marginal or threshold practices can offer insights into processes of theological change – and into the mediation between, and reciprocal influence of, ‘church’ and ‘world’. Our discussion focuses on an example from contemporary British Quakerism. ‘Threshing meetings’ are occasions at which an issue can be ‘threshed out’ as part of a collective process of decision-making. Drawing on a 2015 small-scale study (using a survey and focus group) of British Quaker attitudes to and experiences of threshing meetings, set in the wider context of Quaker tradition, we interpret these meetings as a space for working through – in context and over time – tensions within Quaker theology, practice and self-understandings, particularly those that emerge within, and in relation to, core practices of Quaker decision-making.

Corrections to "coastal acoustic tomography system and its field application"

2002 ◽  
Vol 27 (3) ◽  
pp. 768-768
Author(s):  
H. Yamoaka ◽  
A. Kaneko ◽  
Jae-Hun Park ◽  
Hong Zheng ◽  
N. Gohda ◽  
...  
Keyword(s):  
Field Application ◽  
Acoustic Tomography ◽  
Tomography System

A physically motivated approach for filtering acoustic waves from the equations governing compressible stratified flow

2008 ◽  
Vol 601 ◽  
pp. 365-379 ◽  
Author(s):  
DALE R. DURRAN
Keyword(s):  
Acoustic Waves ◽  
Large Scale ◽  
Mass Conservation ◽  
Simple Expression ◽  
Reference State ◽  
Small Scale ◽  
Sound Waves ◽  
State Equations ◽  
Planetary Scale ◽  
Atmospheric Motions

An incompressibility approximation is formulated for isentropic motions in a compressible stratified fluid by defining a pseudo-density ρ* and enforcing mass conservation with respect to ρ* instead of the true density. Using this approach, sound waves will be eliminated from the governing equations provided ρ* is an explicit function of the space and time coordinates and of entropy. By construction, isentropic pressure perturbations have no influence on the pseudo-density.A simple expression for ρ* is available for perfect gases that allows the approximate mass conservation relation to be combined with the unapproximated momentum and thermodynamic equations to yield a closed system with attractive energy conservation properties. The influence of pressure on the pseudo-density, along with the explicit (x,t) dependence of ρ* is determined entirely by the hydrostatically balanced reference state.Scale analysis shows that the pseudo-incompressible approximation is applicable to motions for which ${\cal M})$2 ≪ min(1,${\cal R})$2, where ${\cal M})$ is the Mach number and ${\cal R}$ the Rossby number. This assumption is easy to satisfy for small-scale atmospheric motions in which the Earth's rotation may be neglected and is also satisfied for quasi-geostrophic synoptic-scale motions, but not planetary-scale waves. This scaling assumption can, however, be relaxed to allow the accurate representation of planetary-scale motions if the pressure in the time-evolving reference state is computed with sufficient accuracy that the large-scale components of the pseudo-incompressible pressure represent small corrections to the total pressure, in which case the full solution to both the pseudo-incompressible and reference-state equations has the potential to accurately model all non-acoustic atmospheric motions.

Experimental and Numerical Study of Water Distillation Performance of Small-Scale Direct Contact Membrane Distillation System

2017 ◽  
Author(s):  
Danielle Park ◽  
Elnaz Norouzi ◽  
Chanwoo Park
Keyword(s):  
Water Temperature ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Small Scale ◽  
Feed Water ◽  
Water Production ◽  
Water Distillation ◽  
Direct Contact Membrane Distillation ◽  
Feed Temperature ◽  
Feed Water Temperature

A small-scale Direct Contact Membrane Distillation (DCMD) system was built to investigate its water distillation performance for varying inlet temperatures and flow rates of feed and permeate streams, and salinity. A counterflow configuration between the feed and permeate streams was used to achieve an efficient heat exchange. A two-dimensional Computational Fluid Dynamics (CFD) model was developed and validated using the experimental results. The numerical results were compared with the experiments and found to be in good agreement. From this study, the most desirable conditions for distilled water production were found to be a higher feed water temperature, lower permeate temperature, higher flow rate and less salinity. The feed water temperature had a greater impact on the water production than the permeate water temperature. The numerical simulation showed that the water mass flux was maximum at the inlet of the feed stream where the feed temperature was the highest and rapidly decreased as the feed temperature decreased.

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