基于小型三维阵列的瞬态声源快速被动定位方法

重物在落水和着底过程中都会产生瞬态声信号,这类信号可被运用于浅水区域水下目标定位。 针对浅水区域目标定位的问题,提出了一种基于小型立体五元基阵的瞬态声源快速被动定位算法。 在分析重物落水信号特征的基础上,选取合适的广义互相关加权函数求得传声器之间的声程差,运用快速最小二乘搜索算法进行声源定位。 结果表明:运用 5 传声器阵列可以同时兼顾定位精度和鲁棒性,且满足实时性要求,该方法可运用于浅水区域瞬态声源定位等领域。     

一种高Q值单频水声信号放大提取电路的设计

针对水声信号所处环境复杂、背景噪声源多的特点,提出了一种基于JFET的超低噪音放大电路,该电路选用两片低噪音的场效应管2SK170作为第一级放大器件,经过CR高通滤波连接到同相放大电路,整体电路增益可达70dB;为进一步提升接收信号信噪比,结合双T滤波器特点优化设计出一种高Q值选频电路;通过Multisim14仿真表明,设计的电路在1 Hz处的电压噪声密度仅为2.4 nV/Hz^0.5,滤波器Q值可达25.6,结合实际电路测试结果表明,设计的电路能够满足水声测量要求。     

Experimental Study on Sloshing Characteristics in the Elastic Tank Based on Morlet Wavelet Transform

Hydroelastic effect of sloshing is studied through an experimental investigation. Different excitation frequencies are considered with low-fill-depth and large amplitude. Morlet wavelet transform is introduced to analyze the free surface elevations and sloshing pressures. It focuses on variations and distributions of the wavelet energy in elastic tanks. The evolutions of theoretical and experimental wavelet spectra are discussed and the corresponding Fourier spectrums are compared. Afterwards, average values of the wavelet spectra are extracted to do a quantitative study at various points. From the wavelet analysis, sloshing energies are mainly distributed around the external excitation frequency and expanded to high frequencies under violent condition. In resonance, experimental wavelet energy of the elevation in elastic tanks is obviously less than that in the rigid one; for sloshing pressures, the elastic wavelet energy close to the rigid one and conspicuous impulse is observed. It recommends engineers to concern the primary natural frequency and impulsive peak pressures.     

Global Statistical Assessment and Cross-Calibration with Jason-2 for Reprocessed HY-2 A Altimeter Data

HY-2 A (Haiyang-2 A) satellite was launched on August 16, 2011 and radar altimeter is one of its main payloads. We reprocessed two years of HY-2 A altimeter sensor geophysical dataset records (SGDR) data. This paper presents the main results in terms of reprocessed HY-2 A altimeter data quality: verification of data availability and validity, monitoring several relevant altimeter parameters, and assessment of the HY-2 A altimeter system performances. A cross-calibration analysis of reprocessed HY-2 A altimeter data with Jason-2 was conducted. The reprocessed HY-2 A altimeter data show good quality and have a low level of noise with respect to Jason-2. The same geophysical correction methods were used to calculate the sea surface height (SSH) for the two missions. The mean standard deviations of the crossover differences for HY-2 A and Jason-2 are 5.24 cm and 5.34 cm, respectively. The mean standard deviation of the crossover differences between HY-2 A and Jason-2 is 5.37 cm. These show that HY-2 A can provide SSH measurements at almost the same level of accuracy as Jason-2. The relative SSH bias between HY-2 A and Jason-2 due to the Ultra Stable Oscillator (USO) drift is obviously observed, and it can affect the calculation of mean sea level and should be further studied and corrected.     

一个重构的153年热带太平洋次表层上卷海温资料

次表层上卷海温对改进ENSO(厄尔尼诺-南方涛动,El Ni o-Southern Oscillation)模拟水平及ENSO年代际变化均具有重要作用。利用一个中等复杂程度耦合模式(intermediate coupled model,简称ICM)和Nudging(张弛逼近)同化方法,重构了1856—2008年间热带太平洋地区的次表层上卷海温。统计检验表明,重构的次表层上卷海温与近50年的3种分析资料间具有较高的相关性和较小的均方根误差。此外,通过此重构的次表层上卷海温资料重新驱动ICM模式,模拟得到的海表温度距平(sea surface temperature anomaly,简称SSTA)可以真实地反映出ENSO的年际和年代际变化,表明此重构的次表层上卷海温资料可用于气候研究,特别是用于ENSO的大尺度低频变化或年代际气候变化研究。     

Dissolved inorganic carbon (DIC) and its carbon isotopic composition in sediment pore waters from the Shenhu area,northern South China Sea

The Shenhu area is one of the most favorable places for the occurrence of gas hydrates in the northern continental slope of the South China Sea. Pore water samples were collected in two piston cores (SH-A and SH-B) from this area, and the concentrations of sulfate and dissolved inorganic carbon (DIC) and its carbon isotopic composition were measured. The data revealed large DIC variations and very negative δ ¹³C-DIC values. Two reaction zones, 0–3 mbsf and below 3 mbsf, are identified in the sediment system. At site SH-A, the upper zone (0–3 mbsf) shows relatively constant sulfate and DIC concentrations and δ ¹³C-DIC values, possibly due to bioturbation and fluid advection. The lower zone (below 3 mbsf) displays good linear gradients for sulfate and DIC concentrations, and δ ¹³C-DIC values. At site SH-B, both zones show linear gradients, but the decreasing gradients for δ ¹³C-DIC and SO₄ ²⁻ in the lower zone below 3 mbsf are greater than those from the upper zone, 0–3 mbsf. The calculated sulfate-methane interface (SMI) depths of the two cores are 10.0 m and 11.1 m, respectively. The depth profiles of both DIC and δ ¹³C-DIC showed similar characteristics as those in other gas hydrate locations in the world oceans, such as the Blake Ridge. Overall, our results indicate an anaerobic methane oxidation (AMO) process in the sediments with large methane flux from depth in the studied area, which might be linked to the formation of gas hydrates in this area.     

主检测深线系统误差的探测与实现

针对海道测量中测深成果系统误差的评价问题,介绍了一种利用主、检测深线测深数据探测系统误差的方法,以实现测深中系统误差的科学评估。     

Heterogeneous Gravity Data Fusion and Gravimetric Quasigeoid Computation in the Coastal Area of China

ABSTRACT

Different types of gravity observations are available over coastal areas. The main challenge for coastal geoid determination is the proper fusion of heterogeneous gravity data including land, shipborne, airborne, and altimetry-derived gravity data. This paper describes the gravity data fusion and the computation of the gravimetric quasigeoid in the coastal area of mainland China. An iterative procedure of the weighted least-squares prediction based on rectangular harmonic functions is used for merging the land, altimetric, shipborne, and airborne gravity data. Applying the analytical continuation method in Molodensky's theoretic frame, the merged gravity data are then used to determine the gravimetric quasigeoid model by using the generalized Stokes' integral in a remove-compute-restore fashion. The gravimetric quasigeoid model is compared with the height anomalies determined at 662 GPS leveling points over the coastal region of mainland China, where both the geodetic height and the normal height are known. The standard deviations of the differences in the coastal provinces range from 1.8 to 4.4 cm. For the entire computation area, the mean and standard deviation of the differences are 27.9 and 3.9 cm, respectively.     

长江口及其邻近陆架区夏季网采浮游植物及其影响因素

2009年6、8月长江口及其邻近陆架区的网采样品中检出浮游植物9门395种(含223种硅藻与125种甲藻)。浮游植物丰度8月(3 077.15×104 cells/m3)显著高于6月(107.80×104 cells/m3)。随长江冲淡水势力增强,位于长江口的丰度高值区8月较6月更偏外侧。种类丰富度8月高于6月,但多样性和均匀度指数略低于6月。6月尖刺伪菱形藻和三角角藻占绝对优势,8月优势种主要有尖刺伪菱形藻、笔尖形根管藻和铁氏束毛藻。骨条藻虽非优势种,但在长江冲淡水区丰度较高。相似性分析和多维尺度分析表明,浮游植物群落组成时空差异显著。典范对应分析表明,温度和盐度是分别影响6、8月群落分布的首要因子。根据水动力和化学参数,该区浮游植物群落分布与环流变化和水团消长密切相关。     

我国海洋水下文化遗产保护现状与管理探讨

海洋水下文化遗产是不可再生的文化资源,在全球海洋开发的浪潮中,做好海洋水下文化遗产的调查和保护是迫切和急需的。文章概述世界上传统海洋大国对海洋水下文化遗产保护和管理的经验,分析我国海洋水下文化遗产保护和管理存在的问题,并提出相关对策:查清海洋水下文化遗产的分布、数量和特征等信息,了解海洋水下文化遗产分布区的地质地貌环境、水动力环境和保存环境条件,建立海洋水下文化遗产档案馆和数据库系统;完善与海洋水下文化遗产保护相关的法规、政策和标准规范等,提升执法效率,做好海洋水下文化遗产保护和海洋开发利用的协调工作;建立海洋水下文化遗产保护示范区,传承和弘扬蓝色文明,实现海洋水下文化遗产的社会利用和可持续保护。