Complex acoustic intensity of normal modes in Pekeris waveguide and its application

Yun, Yu; Jun-Ying, Hui; Zhao, Anbang; Guo-Cang, Sun; Chao, Teng

doi:10.7498/aps.57.5742

Cited by 16 publications

(2 citation statements)

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“…The band at 888 cm -1 is assigned to vibration of W-O b -W connecting with co-cornor bridge oxygen, and the band at 803 cm -1 comes from vibration of W-O c -W connecting with co-side bridge oxygen.The peaks corresponding to the MCM-41(in Fig. 7a) are at 1234,1079,959,805 cm -1 [14]. The broad band around 3449cm -1 may be attributed to surface silanols and adsorbed water molecules, while deformational vibration of adsorbed molecules cause the adsorption bands at 1630 cm -1 .…”

Section: Ftir Spectroscopymentioning

confidence: 95%

Alkylation of p-Cresol with Isobutylene Catalyzed by Heteropoly Acid Supported on MCM-41 Catalyst

Liu

Deng

2011

AMR

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The phosphorus tungsten(PW) heteropoly acids were immobilized on the mesoporous molecular sieves(MCM-41) by wet impregnation. The prepared catalysts were characterized by X-ray powder diffraction, TG and DTA,FTIR. The alkylation of p-cresol with isobutylene was carried out over the PW /MCM-41 catalysts. The influences of various reaction parameters such as reaction temperature, time, PW loading, and catalysts amount on the conversion of p-cresol and the products selectivity were also investigated. Under the optimized reaction conditions of 90 °C,PW loading of 10%, catalyst amount of 1.5%, p-cresol conversion was found to be 93.89% with product rate to 2-tert-butyl-p-cresol 51.29%, 2,6-di-tert-butyl-p-cresol 42.48% and tert-butyl-p-tolyl ether 0.12%, responding to selectivity of 2, 6-di-tert-butyl-p-cresol 45.24%.

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Section: Ftir Spectroscopymentioning

confidence: 95%

Alkylation of p-Cresol with Isobutylene Catalyzed by Heteropoly Acid Supported on MCM-41 Catalyst

Liu

Deng

2011

AMR

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“…The characteristics of the low-frequency acoustic vector field in Pekeris waveguide were analyzed based on the normal modes theory of a point source in layered media [5], especially the interference structure of vertical acoustic intensity flux was concerned, and the method which can tell the source's specified depth by comparing with a critical depth was proposed, however, the critical depth is not suitable enough to tell whether the target is a surface ship or a submarine. Therefore the researches were extended, and an ideal critical depth was achieved by analyzing horizontal complex cross acoustic intensity between two transducers deployed vertically [6], and the phase angle spatial distribution of complex acoustic intensity was discussed, but only the Pekeris waveguide was analyzed. The straightforward interference structures of the line spectrum acoustic field [7], which are the physical basis for further radial velocity estimation, were achieved by adopting two kinds of spatial temporal transformations, which are the pressure cross-spectrum reactive component of two sensors deployed vertically and the vertical complex acoustic intensity active component of a single vector sensor.…”

Section: Introductionmentioning

confidence: 99%

Pressure and velocity cross-spectrum of normal modes in low-frequency acoustic vector field of shallow water and its application

Ling

Jiang

2015

J. of Syst. Eng. Electron.

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The pressure and horizontal particle velocity combined descriptions in the very low frequency acoustic field of shallow water integrated with the concept of effective depth of Pekeris waveguide is proposed, especially the active component of the pressure and horizontal particle velocity cross-spectrum, also called horizontal complex cross acoustic intensity, when only two normal modes are trapped in the waveguide. Both the approximate theoretic analysis and the numerical results show that the sign of the horizontal complex cross acoustic intensity active component is independent of the range when vertically deployed receiving dual sensors are placed in appropriate depths, the sum of which is equal to the waveguide effective depth, so it can be used to tell whether the sound source is near the surface or underwater; while the range rate is expected to be measured by utilizing the sign distribution characteristic of the reactive component. The further robustness analysis of the depth classification algorithm shows that the existence of shear waves in semi infinite basement and the change of acoustic velocity profiles have few effects on the application of this method, and the seabed attenuation will limit the detection range, but the algorithm still has a good robustness in the valid detection range.

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Depth classification of underwater targets based on complex acoustic intensity of normal modes

Yang

Yin

Yun

et al. 2016

J. Ocean Univ. China

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In order to solve the problem of depth classification of the underwater target in a very low frequency acoustic field, the active component of cross spectra of particle pressure and horizontal velocity (ACCSPPHV) is adopted to distinguish the surface vessel and the underwater target. According to the effective depth of a Pekeris waveguide, the placing depth forecasting equations of passive vertical double vector hydrophones are proposed. Numerical examples show that when the sum of depths of two hydrophones is the effective depth, the sign distribution of ACCSPPHV has nothing to do with horizontal distance; in addition, the sum of the first critical surface and the second critical surface is equal to the effective depth. By setting the first critical surface less than the difference between the effective water depth and the actual water depth, that is, the second critical surface is greater than the actual depth, the three positive and negative regions of the whole ocean volume are equivalent to two positive and negative regions and therefore the depth classification of the underwater target is obtained. Besides, when the 20 m water depth is taken as the first critical surface in the simulation of underwater targets (40 Hz, 50 Hz, and 60 Hz respectively), the effectiveness of the algorithm and the correctness of relevant conclusions are verified, and the analysis of the corresponding forecasting performance is conducted.

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Complex acoustic intensity of normal modes in Pekeris waveguide and its application

Cited by 16 publications

References 0 publications

Alkylation of p-Cresol with Isobutylene Catalyzed by Heteropoly Acid Supported on MCM-41 Catalyst

Alkylation of p-Cresol with Isobutylene Catalyzed by Heteropoly Acid Supported on MCM-41 Catalyst

Pressure and velocity cross-spectrum of normal modes in low-frequency acoustic vector field of shallow water and its application

Depth classification of underwater targets based on complex acoustic intensity of normal modes

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