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Zhou D.F.,South China Sea Marine Engineering Surveying Center | Zhou D.F.,Key Laboratory of Technology and Application for Safeguarding of Marine Rights and Interests | Wang Y.F.,Digital Signal
Applied Mechanics and Materials | Year: 2014

In this paper, a fast and high-efficiency carrier frequency offsets (CFO) estimation algorithm is proposed. This new algorithm exploits the intrinsic structure information of OFDM signals and the unimodality of the cost function for CFO estimation. It reduces the computational complexity by using the golden section method in searching for the extremum of the cost function. The performance of the proposed algorithm is investigated with numerical simulations. The results show that the new algorithm has much lower complexity than Tureli's MUSIC-like approach while achieves same performance in both additive white Gaussian noise (AWGN) and multipath fading channels. © (2014) Trans Tech Publications, Switzerland.

Hong-Bo Z.,CAS South China Sea Institute of Oceanology | Pin Y.,CAS South China Sea Institute of Oceanology | Wang Y.-L.,CAS South China Sea Institute of Oceanology | Xing Y.-Q.,South China Sea Marine Engineering Surveying Center
Marine Georesources and Geotechnology | Year: 2016

Many researchers have focused on the characteristics of tectonic evolution in the Reed area of the southern South China Sea, but there has been little research focusing on deep-water sedimentary characteristics. Seismic data acquired in the Reed area have been processed and analyzed; representative deep-water sedimentary patterns, such as sediment waves, deep-water channels, slumping, and sliding mass, can be clearly distinguished from these seismic profiles. Combining this data with the geological setting and seafloor topography of the research area, it can be concluded that deep-water channels, slumping, and sliding depositions which have developed on the continental slope of the northeast Reed basin were formed by gravity flow, and the sediment waves which occur in the west and northwest Reed basin have been generated by deep-water bottom current. © 2016, Copyright © Taylor & Francis Group, LLC.

Bai Y.,Tianjin University | Wang X.,Tianjin University | Cao Y.,Tianjin University | Cao Y.,South China Sea Marine Engineering Surveying Center
Science China Technological Sciences | Year: 2013

The incipient motion of bedload is due to the interaction between the flow and sediment. It is stochastically correlated with the flow structure, the sediment gradation and the arrangement of grains on the bed surface. The random position of the sediment on bed can be represented by a hiding factor or an exposure degree. Based on the numerical simulation of the disturbed flow in the interstice of grains, the influence of the two-way exposure degree (the vertical exposure degree and the longitudinal exposure degree) on the coarse grain incipient motion was investigated in this work. Results show that the exposure degree varies with the position of the sediment on the bed, which influences the flow structure around the particle and the incipient motion. In this paper, the major research achievements on this phenomenon include: Firstly, a mathematical model is established for the rolling-pattern incipient motion of the coarse grain under a critical state of moment balance. The influence of the partial disturbed flow is considered. Secondly, the two-way relative-exposure-degree probability distribution functions are developed to reflect the influence of the disturbed flow and the random arrangement of sediments. Thirdly, a formula to calculate the incipient velocity is presented based on the above results, which considers the impact of the two-way exposure degree of sediment particles. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.

Zheng H.-B.,CAS South China Sea Institute of Oceanology | Zheng H.-B.,Chinese Academy of Sciences | Yan P.,CAS South China Sea Institute of Oceanology | Chen J.,South China Sea Marine Engineering Surveying Center | Wang Y.-L.,CAS South China Sea Institute of Oceanology
Applied Ocean Research | Year: 2013

Sub-bottom profile data can be used not only for the interpretation of the seabed strata structure and formation, but also for seabed sediments classification using inversion method. In the present paper, sub-bottom profile data from a survey line located on the continental slope of the northern South China Sea were processed. The data collected were used to calculate seabed reflection coefficient and attenuation rolloff, while sediment acoustic characteristics parameters, including porosity and permeability, were defined based on the Biot model that calculates wave propagation in sediment-fluid mixtures. Finally, the mean grain sizes and corresponding sediment classification were quantitatively estimated. By comparing the inversion result with sediment description of gravity piston cores which were acquired near the survey line, we found that the results from inversion method accord with the particle size analysis of sediment cores. However, the inversion method is only suitable for the soft seabed sediments such as mud or sand. The petrous sediment in the survey is classified by Gardner formula and we concluded the petrous seabed sediments are carbonate crusts which are generated from leaky gas hydrate. © 2012 Elsevier Ltd.

Yuan D.,Chinese Academy of Sciences | Yuan D.,CAS Qingdao Institute of Oceanology | Li Y.,Chinese Academy of Sciences | Li Y.,CAS Qingdao Institute of Oceanology | And 13 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2010

Satellite images and in situ hydrography and nutrient observations are used to study the three-dimensional structure of a penetrating front off the Changjiang mouth in the East China Sea. The satellite images of MODIS/Terra on October 16, 2006 show anomalously high concentrations of chlorophyll and total suspended sediments extending offshore from the mean coastal front off the Chiangjiang mouth. However, the sea-surface temperature image of the same satellite shows no signature of this extension at all. The in situ hydrography measured during the same time as the satellite images discloses that the surface layer of the front is occupied by low-salinity waters from the nearshore area, which suggests a cross-shelf jet covering a distance of about 50. km. A counter intrusion underneath the surface offshore jet is indicated by an increase of the subsurface temperature and salinity during the offshore excursion of the front, which leads to a significant temperature inversion at the head of the front. The vertical temperature and salinity distribution shows propensity of double diffusive processes, which may contribute to the ensuing evolution of the front. The nutrient distribution of the front is consistent with the cross-shelf jet derived from the hydrographic data, with surface and bottom intensified concentrations and minimum mid-depth concentrations, suggesting that the primary transport of the surface nutrients is in the horizontal cross-shelf direction. The potential dynamics of the frontal intrusion is discussed in light of wind forcing and frontal instability. The intrusion is found to be very important to cross-shelf and cross-front exchanges in the East China Sea. © 2010 Elsevier Ltd.

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