实测海浪方向谱的统计特征

本文根据仪器阵列测量和“９５６”测波浮标获得的个例方向谱资料,分析了不同波场类型的实测方向谱形状;计算了海浪能量相对于方向和频率的实际分布;结合实测的风要素,探讨了由台风边缘大风和寒潮大风引起的风浪峰频组成波方向与风向的对应关系。     

实测海浪方向谱的统计特征

本文根据仪器阵列测量和“９５６”测波浮标获得的个例方向谱资料,分析了不同波场类型的实测方向谱形状;计算了海浪能量圩方向和频率的实际分布;结合实测的风要素,探讨了由台风边缘大风和寒潮大风引起的风浪峰频组成波方向与风向的对应关系。     

海浪方向谱的现场观测与分析

方向谱是海浪的基本性质之一。本文在国内首次采用测波仪阵列法在渤海采油平台上成功地观测到海浪方向谱，给出了当地随波浪成长而变化的方向谱表达式。观测前采用数模和模型试验方法，对阵列的布置型式、测波仪间距和平台等对观测结果的影响，以及现有各种方向谱分析方法的精度等进行了对比分析，为提高观测精度，保证方向谱分析的质量提供了依据。     

〈恩迪柯〉1156遥控测波仪

最近,我院首次从美国恩迪柯公司进口了一套1156遥控测波仪。货已到,待验收消化后即可正式投入使用。1156测波仪是原956测波仪的改进型,它以遥测浮标内的加速度计为传感器,是目前世界上最先进的测波系统之一。该系统使用甚为方便,不仅适用于测量近岸沿海波浪,也适用于远海测波,是当前交通、海洋、石油勘探和航海事业中一种较为理想的测波仪器。它的引进增加了我院现场测波研究工作的手段。 1156测波仪除了能如同956那样测取波浪的波高、波周期和波向外,如若配置一些部件,尚能进行风、气压、水温和气温等要素的测量。     

基于三种测波方法的实测数据对比分析

近海海洋工程波浪观测中较为广泛使用的测波方法主要包括压力式测波、声学测波和重力式测波等。三种观测方法各有优势,需根据历史资料、地理环境和任务目的设计合理的观测形式,可以选择一种或多种形式组合的形式,以达到最佳的观测效果。使用GPS测波浮标、AWAC声学海流/波浪测量仪和TWR-2050压力式波潮仪的实测资料进行了对比分析,结果显示,测波浮标与AWAC所测数据相关性较一致;TWR压力波潮仪与AWAC测量的波高趋势基本一致,但周期短、波高小的海域和时间段测量准确度较差。     

GPS测波技术分析与初步实验研究

测波浮标是一种方便可行的波浪测量方法,首先分析了单点GPS接收机测波浮标的测量原理,然后做了单点GPS接收机测速实验和单点GPS接收机模拟测波实验,并对这两个实验的数据进行了分析处理,最后提出了单点GPS接收机测波浮标的初步设计方案,为进一步推动这项测波技术的国产化打下了基础。     

声学测波仪在ZQA1—1型海洋站自动观测系统中的应用

在 ZQA1-1型海洋站自动观测系统中(简称系统),应用计算机软件配合声学测波仪进行波浪测量,提高了测波的可靠性。图1为系统中测波部分方框图。图中实线部分是声学测波仪电路框图,虚线部分为应系统测波要求而增加的。当开关 K 处于②的位置时,声学测波仪恢复原态,可以独立进行     

水下压力阵列的测波方法

本文介绍了ＨＤＬ—２１７６底压式测波仪的基本特性，给出了水下压力阵列进行波浪方向谱估计的数据计算方法。     

近海测波多传感器优化配置模拟与设计研究

研究了测波浮标中GPS传感器和加速度传感器共同作用下对近海测波的影响。介绍了测波浮标数据采集系统的基本框架和硬件设计;为提高测波浮标系统的测量精度,对多传感器进行了优化配置和信息的融合处理,并通过仿真验证了该设计性能的优越性。     

当前海洋波浪测量的技术特点和实测分析

全面地比较和总结了当前包括压力式测波、声学式测波、浮标式测波和遥测式测波在内的几种主要的海洋波浪测量方法的技术特点;对相应类型的典型代表型号的仪器主要技术指标进行了对比;对不同类型测量方法及其对应的仪器的具体适用环境给出了分析和建议。实际结合了ADCP,AWAC,Wave Duo测波浮球等几种海洋波浪测量仪器于2014年12月在江苏省南通市近海相近区域的同步实测数据,对这几种仪器的海洋波浪测量的响应和过程特征进行了对比和分析,这对相关的海洋波浪测量技术和对应的测波仪器设备特点也是一个很好的验证。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Evaluation of the Risk of Marine Slope Instability: A Pseudo-3D Approach for Application to Large Areas

This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried out by IFREMER on 19 cores extracted at different depths (from 27 m to 1300 m) (Cochonat, Bourillet, and Savoye, 1993; Mulder et al., 1994). Many scenarios were proposed in order to explain the cause of the Nice slope failure (Habib, 1994). In this article, two of those scenarios were tested. Simulation results are presented and discussed.