神光Ⅲ原型单端驱动黑腔等离子体聚心时间研究

在神光Ⅲ原型装置上,利用8束激光单端驱动半腔靶实验研究了黑腔等离子体聚心时间.通过改变腔底结构建立了4种黑腔辐射源,比较了等离子体径向的聚心时间与黑腔辐射温度的变化关系.径向聚心时间和辐射温度分别由X射线分幅相机和软X射线能谱仪给出.研究发现,4种辐射源的等离子体径向聚心时间与辐射温度之间存在正比关系,聚心时间随辐射温度升高而延后.     

台湾东北部地形共振对M2内潮演化影响的数值模拟研究

<正>压潮流、突变海底地形和稳定层结结构是内潮生成的主要因素。台湾东北部海域地形结构多变,正压潮流较强,形成复杂的内潮场。本文通过ROMS(Regional Ocean Modeling System)模式,研究了台湾东北部海域两源区共振条件下内潮的生成、传播和耗散混合过程。结果表明:在台湾东北部海域,Mien-Hua海底峡谷与I-lan海脊是M2内潮重要的生成源区,源区之间的距离与M2内潮水平波长相当,满足共振条件并增强了内潮的生成和耗散。本文通过敏感性试验,探讨模式水平分辨率与不同季节的层化对源区共振过程的影响,数值实验表明,高分辨率的数值模式可以更好地刻画小尺度的地形结构,对复杂地形条件下内潮生成和传播过程的数值模拟十分必要;不同季节的海水层化结构在本质上不改变两源区间的共振关系,但层化强弱对内潮能量的生成具有一定程度的影响。     

线性偏振光激发的错位表面等离子体激元纳米结构聚焦

利用扫描近场光学显微镜观测并分析了两种表面等离子体激元纳米结构对表面等离子体激元(SPP)的激发和聚焦现象. 用线偏振光照射有半个周期相位差的环状沟槽结构与有半个周期位相差的环状狭缝结构,得到了单点的SPP聚焦. 有限时域差分法的模拟结果验证了实验中观测的现象. 这两种相位错位的表面等离子体激元纳米结构,突破了由于干涉导致的线偏振光不能得到单个聚焦点的限制. 与采用径向偏振光激发而得到单个聚焦点的方法相比,线偏振光不需要聚焦,也不需要将光束中心对准纳米结构的几何中心即可得到单点聚焦.     

微量生物碳酸盐ICP-OES元素分析中的仪器优化

为优化电感耦合等离子体发射光谱仪（ICP-OES）测试微量生物碳酸盐中元素含量的工作条件,在Thermo—Fisher公司生产的iCAP6300 Radial型ICP—OES上,对1050组仪器条件、32种不同组成的标准溶液、36个谱线对和两种仪器校正工作曲线进行了测试;借助开源科学计算软件Scilab数据插值和可视化...     

传统Spar平台和型组合共振运动响应研究

研究传统Spar平台在长周期规则波浪下的和型组合共振现象.考虑垂荡与纵摇运动的相互影响以及瞬时波面对于纵摇运动的参数激励作用,建立平台两自由度耦合运动方程.采用多尺度法导出了当波浪频率接近垂荡与纵摇固有频率之和时方程的一阶摄动解.针对一座实际Spar平台,通过求解幅值分岔方程,得到平台在不同波高下的运动响应并进行了数值模拟.计算结果发现,当波浪幅值超过某一极限值时,平台出现较大幅值的垂荡与纵摇亚谐共振运动.研究结果揭示了Spar平台出现和型组合共振的条件和组合共振时的动力特性.     

深水波中进动共振的数值模拟研究

进动(precession)共振是一种非线性共振相互作用,2016年才有学者对这一现象进行研究。采用非静压二维自由表面流模型模拟了深水条件下重力波的进动共振现象。通过边界造波的方法产生双色波,分析了触发进动共振的初始条件;探讨了进动共振在小振幅前提条件下发生的简化初始条件。数值模拟分析两组对称测点,对不同测点的波面、能量谱进行对比分析。数值结果表明:非静压二维自由表面流模型可以模拟进动共振现象,并且可以采用双色波作为条件来研究深水五波进动共振现象,进动共振需要一定的能量转化时间,进动共振发生的条件是三波组合的进动频率等于一个系统存在的非线性频率。     

海上浮式环形平台内域水体共振频域数值分析

海上浮式旅游平台作为新型海洋结构具有较好的发展前景。其中浮式环形平台结构的内域水体可作为浮式游艇港,但内域水体封闭性的增加也将引起类似月池共振的水体共振问题,影响码头泊稳条件。采用线性势流频域方法研究了平台吃水深度、结构运动响应和平台开口形状对内域水体共振响应特征的影响。结构吃水深度增加,水体共振频率向低频方向偏移,第0～2阶共振幅值随吃水深度增加而增加;结构运动引起水体共振频率向高频方向偏移,并且结构运动响应共振区间与第0～3阶水体共振频率范围重合,纵摇运动对内域水体共振模态分布影响较大,其他自由度影响较小。为抑制内域水体共振,提出在水面线处增设薄板和人工阻尼区域两种方案,结果表明：增设薄板可有效降低高频处水体共振,添加阻尼区域可在整个波浪频率范围内达到抑制水体共振的目的。     

非线性铰接浮体波能转换器的动力学特性研究

针对传统铰接浮体波能转换器捕获效率低、频带窄的瓶颈,提出一种新型高效波能捕获仿生非线性连接结构。该连接结构具有转动负刚度效应,可起到被动相位控制作用,提高系统的波能捕获效率。首先,基于海蛇脊柱骨结构的柔性约束机理,设计了一种高效波浪能捕获仿生连接结构,该结构由球窝结构、球头、翅状突出物和类肌肉柔性结构组成;其次,基于线性波浪理论和Cummins 方程,建立两模块非线性波能转换器的动力学模型,并采用谐波平衡法解析求解非线性控制方程;最后,开展了数值模拟研究,分析了规则波激励下该新型波能转换器的波能转换特性。结果表明：通过引入新型高效仿生连接结构,可有效降低系统的等效固有频率;当连接器的负刚度结构调整到合适参数时,系统的弹性力可以在纵摇相平面上形成一个椭圆势阱,其椭圆势阱的长轴接近铰接浮体系统相对纵摇运动的模态方向,由此驱动两个模块的相对纵摇运动趋于反相,起到被动相位控制的作用。     

低维半导体异质结中的量子相干红外发射机理理论研究

给出了一种在非粒子反转条件下量子阱和量子点激光器的红外发射机理. 此种红外发射是基于在同一作用区产生并作为红外场相干源的两种带间跃迁激光场的共振非线性混合. 这种频率下转换机理并不依赖于在半导体激活媒质中的长时相干假定条件,在室温和泵注入电流条件下仍然有效. 频率下转换的固有效率可以达到相当于每个可见光子产生一个红外光子的量子极限值. 根据红外发射的可参变特性,这种非粒子反转的方法尤其适用于长波红外工作范围.     

南海海啸在泰国湾海域的共振响应

马尼拉海沟具备引发地震海啸的条件,是南中国海主要的潜在海啸发生区。南中国海西南部泰国湾海域和纳土纳海域地形复杂、多独立的半封闭水域,海啸波极易在该区域形成水波共振,加剧其灾害影响。采用COMCOT海啸模型模拟了马尼拉海沟断裂带发生9.3级地震时引发海啸的长时间传播过程,并基于水波共振理论分析其在不同尺度下的共振特性。结果表明,海啸波在曼谷湾至邦加—勿里洞岛间引起了明显的纵向第一、二模态(3 360.0 min、1 440.0 min)水波共振,在泰国湾至邦加—勿里洞岛之间引起了明显的纵向第二、三、四模态(775.4 min、560.0 min、373.3 min)共振,而在泰国湾至印度尼西亚沿岸引起了明显的纵向第二、三、五、七模态(1 008.0 min、630.0 min、373.3 min、252.0 min)水波共振。此外,海啸波不仅在泰国湾引起了明显的纵向第一、三、四模态(560. 0 min、252. 0 min、179. 4 min)共振,还在其横向出现了明显的第一、二、三模态(480.0 min、252.0 min、179.4 min)共振。     

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.