Estimation of the Stability of Acoustic Reciprocal Transmission in Long-Range Propagation at the Central Equatorial Pacific

Wang, Yong; Hachiya, Hiroyuki; Nakamura, Toshiaki; Nakano, Iwao

doi:10.1143/jjap.41.3525

Cited by 14 publications

(9 citation statements)

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“…In a previous study of ocean acoustic tomography, simultaneous transmission using multiple M-sequence codes from five transceivers was employed to perform precise measurements of ocean currents. [6][7][8][9][10][11][12][13][14] In this case, the overlapped signals with different M-sequence codes were rarely observed.…”

Section: Introductionmentioning

confidence: 91%

Development of Ultrasonic Multiple Access Method Based on M-Sequence Code

Wang

Siginouchi

Hashimoto

et al. 2007

jjap

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Sonar systems are currently used in automobiles or mobile robots. When multiple active sonar systems operate in a small area, ultrasonic interference is a serious problem. In this paper, we propose an ultrasonic multiple access method (UMAM), in order to realize aerial active sonar systems that can operate in an interference environment. From experimental results, the proposed UMAM was shown to be useful for a highly precise measurement in such an interference environment.

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Section: Introductionmentioning

confidence: 91%

Development of Ultrasonic Multiple Access Method Based on M-Sequence Code

Wang

Siginouchi

Hashimoto

et al. 2007

jjap

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“…By the OAT method, the spatial profiles of temperature and current in the area enclosed by transceivers are determined by calculating the reciprocal sound propagation between the transceivers. Therefore, an adequate numerical method for determining sound propagation 4) and accurate determination of arrival time from the received signals [5][6][7][8] are required to obtain sufficient resolution. A data assimilation technique was used for data analysis using the ocean dynamical model to explain ocean phenomena observed by OAT in accordance with physical processes.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Tidal Effect on Reciprocal Sound Propagation in Central Pacific Ocean

Ogasawara¹,

Nakamura²,

Fujimori

et al. 2008

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Long-range-traveling sound in the ocean includes information on ocean phenomena such as changes in temperature, tide, internal wave, and vortex as travel time differences or sound pressure attenuations. In this study, time series of travel time differences between two moorings for an ocean acoustic tomography experiment in the equatorial central Pacific Ocean promoted by JAMSTEC in 2000 were compared with the calculated elevation of sea level predicted from eight major tidal constituents using the tidal model GOTIC2. While diurnal and semidiurnal tidal effects were confirmed from the water temperature changes located near the sound sources, differences in the reciprocal travel time also fluctuated in accordance with the tidal effects. Although the precision of the moorings position detection and travel time tracking from the received signals need to be improved, this analysis is the first step to reveal the dynamics of energy circulation in the sea.

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“…OAT can determine the spatial profiles of currents and temperatures in the observed area by calculating reciprocal sound speeds between the sound source and the receiver. Thus, theoretical sound ray simulations 2) and accurate methods to calculate arrival time [3][4][5][6][7][8] are needed to obtain exact arrival times. OAT experiments extending over a long period of time were periodically performed by the Japan Agency for Marine-Earth Science and Technology (JAM-STEC) in the central equatorial Pacific from 1998 to 2000.…”

Section: Introductionmentioning

confidence: 99%

“…OAT experiments extending over a long period of time were periodically performed by the Japan Agency for Marine-Earth Science and Technology (JAM-STEC) in the central equatorial Pacific from 1998 to 2000. [3][4][5][6][7][8][9][10][11][12][13][14] The main purposes of these experiments were to determine relations between water temperature and El Nin ˜o and southern oscillation (ENSO), and to observe the meridian circulation between the tropical and subtropical ocean.…”

Section: Introductionmentioning

confidence: 99%

Fluctuation of Long-Distance Sound Propagation in the Central Pacific

Ogasawara

Nakamura

Hachiya

et al. 2006

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An effective Hamiltonian for a two-level system (TLS) which could model the interaction between a tunneling proton and the conduction electrons of a metal is investigated in a comparative way. In the conventional first-order Born approximation with plane waves, and for small-distance displacement of the tunneling particle, a simple correlation between the atomic motion and angular momentum change of the scattering electron is deduced. For such a displacement, and within a distorted wave Born approximation for initial and final states, the change in the scattering amplitude is expressed via bounded trigonometric functions of the corresponding difference of scattering phase shifts. The numerical value of this amplitude change is analyzed in the framework of a self-consistent screening description for an impurity embedding in a paramagnetic electron gas. The coupling thus obtained of the tunneling proton to a homogeneous electron gas is too weak to be in the range required for realization of the two-channel Kondo effect.

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Estimation of the Stability of Acoustic Reciprocal Transmission in Long-Range Propagation at the Central Equatorial Pacific

Cited by 14 publications

References 1 publication

Development of Ultrasonic Multiple Access Method Based on M-Sequence Code

Development of Ultrasonic Multiple Access Method Based on M-Sequence Code

Analysis of Tidal Effect on Reciprocal Sound Propagation in Central Pacific Ocean

Fluctuation of Long-Distance Sound Propagation in the Central Pacific

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