Development of DONET2 &amp;#x2014; Off Kii chanel observatory network

Kawaguchi, Katsuyoshi; Araki, Eiichiro; Kogure, Y.; Takahashi, Narumi; Katayama, Takeshi; Hishiki, K.; Fujiwara, Noriyuki; Iida, N.; Kaneda, Yasufumi

doi:10.1109/ut.2013.6519844

Cited by 13 publications

(7 citation statements)

References 3 publications

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“…Among these synthetic gauges, 24 are aligned with the positions of actual deployed gauges in observation networks such as NOWPHAS (Nationwide Ocean Wave information network for Ports and Harbors) or DONET2 (Dense Oceanfloor Network system for Earthquakes and Tsunamis); see, for example, Nagai (1998) and Kawaguchi et al. (2013) for detailed information on these gauge networks. The remaining 47 gauges are placed at randomly selected grid points.…”

Section: Verification With Procedures Demonstrationmentioning

confidence: 99%

Sequential Bayesian Update to Detect the Most Likely Tsunami Scenario Using Observational Wave Sequences

et al. 2022

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This study presents a method for the detection of the most likely tsunami scenario among a set of possible scenarios using an observational wave sequence based on a sequential Bayesian update scheme. The proposed method consists of two phases: an offline preliminary learning phase and an online real‐time detection update phase. The innovation of this study is that proper orthogonal decomposition (POD) and Bayesian update are used together with an established tsunami simulation technique. In the offline reinforcement learning process, a series of tsunami simulations are carried out based on geophysically feasible scenarios, and the spatial modes of wave data calculated at predefined synthetic gauge locations are extracted through the application of POD. When a real tsunami event occurs and observational ocean data are obtained, the online process can then be performed as follows: using the stored spatial modes along with their component coefficients, pseudocoefficients are repeatedly estimated from the obtained wave data and used to sequentially update the most likely tsunami scenario according to the posterior probability through Bayesian update. A verification analysis is carried out to illustrate the procedure of the proposed method, and a validation analysis is conducted to demonstrate both the capabilities and applicability of the process with reasonable accuracy. A comprehensive discussion details the characteristic features of the proposed method in terms of the real‐time prediction of tsunami hazards and risks.

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Section: Verification With Procedures Demonstrationmentioning

confidence: 99%

Sequential Bayesian Update to Detect the Most Likely Tsunami Scenario Using Observational Wave Sequences

et al. 2022

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“…Due to the merit feature of shunt fault tolerance, CC mode observatories are widely adopted at scenarios requiring uninterrupted observation even with fault presence [5]. Existing CC observatories systems, including the Hawaii Undersea Geo-Observatory (HUGO) [6], the Hawaii-2 Observatory (H2O) [7,8], ALOHA Cabled Observatory (ACO) [9], the Development of Dense Ocean-floor Network System for Earthquakes and Tsunamis (DONET) [10,11], DONET2 [12,13], the Marine Cable Hosted Observatory (MACHO) [14], the Japan Trench Earthquake and Tsunami Monitoring Network Project (S-net Project) [15][16][17], etc., are all powered by CC mode and mainly used for long term observation around unstable geology seismic areas.…”

Section: Introductionmentioning

confidence: 99%

“…The underwater CC power system consists of multi-serial connection nodes that each tap a certain quantity of power from the constant current cable [18]. Considering stability problems due to parasitic parameters under long submarine cables, using a shunt regulator or similar principle to draw the required power is mainly used worldwide [19], such as HUGO, H2O, ACO, NONET, MACHO, DONET2 [6][7][8][9][10][11][12][13][14][15][16][17], etc. Figure 1a shows a typical CC/CV converter that comprises a shunt regulator and a DC/DC module [20].…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable Power Converter for Constant Current Underwater Observatory

et al. 2020

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A constant current (CC) underwater observatory employing the shunt method to provide constant voltage (CV) power for external loads is favored in occasions where shunt-fault tolerance is required. However, low efficiency of CC to CV conversion with the shunt method limits its application, especially in scenarios of varying loads. In this paper, a highly reliable and stable CC/CV converter with better efficiency is introduced based on the proposed novel active soft bypass (ASB) technology and the proposed novel priority-based power management strategy (PPMS). The ASB technology is a method that employs switches and a special control sequence which greatly depresses the large voltage transient presenting on the input side when trying hard bypass redundant modules, and the PPMS makes the system easy to monitor and ensures the absolute reliability of ASB technology. The theoretical study of this novel reconfigurable CC/CV converter and validation experiments on a prototype are carried out, with results showing great improvement in the performance. In addition, the proposed reconfigurable power converter is applied to a coastal observatory in the East China Sea.

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“…Kasahara et al [26] proposed a versatile ecomonitoring network which delivered 175-W power for scientific instruments via a cabled underwater system. Kawaguchi et al [27,28] proposed a power distribution control system used in a dense ocean-floor network detection system for earthquakes and tsunamis in Japan. This system received 500-W constant direct current power supplied by the terminal equipment and distributed 45-W secondary power output to a measurement instrument as needed.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the maximum and minimum values of GS1 V and in V are obtained at the same time. In (27),…”

mentioning

confidence: 99%

Design and Analysis of an Equivalent Load Power-Stability Control Circuit for Cabled Underwater Information Networks

2020

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Cabled underwater information networks (CUINs) have evolved over the last decade to provide abundant power and broad bandwidth communication to enable marine science. To ensure reliable operation of the CUINs, the stability of the remote power supply system, a key component of underwater power facilities, is essential. To avoid instability and collapse of the power system caused by rapid changes in load, we propose an equivalent load power-stability control circuit suited for an underwater constant current power supply system. This circuit can change its own working state according to the size of the load and play a role in power compensation. In order to prove the feasibility of the converter design, the working state of the circuit under different load values was analyzed and the performance of circuit was verified through simulation and experiments. The results show that when the load resistance changes within a large range (including when the load has an open circuit or short circuit fault), the equivalent load is basically unchanged or changed within a very small range for the constant current source, causing the constant current source to maintain stable output voltage and output power. Thus, the influence of the branch line cable on the trunk line cable is reduced, and the reliability of the underwater constant current power supply system is improved. Furthermore, the equivalent load power-stability control circuit would facilitate live equipment replacement and maintenance for CUINs. INDEX TERMS Cabled underwater information networks (CUINs), remote constant current power supply system, stability, equivalent load power-stability control.

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Development of DONET2 — Off Kii chanel observatory network

Cited by 13 publications

References 3 publications

Sequential Bayesian Update to Detect the Most Likely Tsunami Scenario Using Observational Wave Sequences

Sequential Bayesian Update to Detect the Most Likely Tsunami Scenario Using Observational Wave Sequences

Reconfigurable Power Converter for Constant Current Underwater Observatory

Design and Analysis of an Equivalent Load Power-Stability Control Circuit for Cabled Underwater Information Networks

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