海浪谱型对最大波高估算的影响研究

无论是对于各种涉海水工建筑物的设计还是对于它们的防护而言,最大波高的预测都是非常重要的工作。目前常用的海浪预报模式多以相位平均模型为主,其能直接给出的计算结果是海浪谱,因此基于海浪谱给出合理的最大波高估算具有重要的意义。前人对波陡、谱宽等参数对最大波高公式的影响都有了较为清楚的认知,然而相关研究大多围绕单峰谱开展,尚没有考虑包括双峰谱在内的海浪谱型最大波高公式的影响。本文首先探讨了海浪谱对最大波高的影响特性,进而提出了海浪谱谱型的参数化定义,最后给出了考虑谱型因子的最大波高公式。     

枯季长江口南汇东滩潮间带盐沼湿地冲淤变化对大型底栖动物功能群的影响

盐沼湿地的冲淤变化是影响大型底栖动物功能群组成及其分布特征的一个重要因素。本文选择长江口南汇东滩作为研究区域,设置固定样地,分别于2015年11月和2016年2月,进行了大型底栖动物和沉积物理化因子的季节性取样分析,并在期间内每月进行滩面冲淤变化的观测,分析了枯季长江口南汇东滩潮间带盐沼湿地冲淤变化对大型底栖动物功能群的影响及作用机理。调研期间共采集到大型底栖动物37种,从功能群组成来看,以杂食者居多,共25种;植食者次之,共7种;肉食者最少,仅为5种。3种食性功能群的物种数、密度和生物量的时空变化特征有所不同。调研期间,3个功能群物种数都略有下降;植食者密度显著增加（P<0.01）,而肉食者、杂食者密度变化不显著（P>0.05）;3个功能群的生物量变化均不显著（P>0.05）。植食者密度和生物量在样地间都存在极显著差异（P<0.01）;肉食者和杂食者仅密度在2016年2月的调研中存在样地间的显著差异（P<0.05）。不同样地月际冲淤变化特征有所不同,但总体均呈淤涨态势。多数环境因子存在显著的空间差异（P<0.05）,仅不同深度的沉积物中值粒径在样地间无显著差异（P>0.05）。滩面冲淤变化对沉积物理化指标的变化具有主导作用。通过非线性回归分析筛选出的与各功能群物种数、密度、生物量变化具有显著相关性（P<0.05）的环境因子组合存在差异。其中,对植食者密度、生物量的变化和肉食者物种数的变化有显著影响的环境因子组合中都包含绝对冲淤变化量。滩面冲淤变化除对大型底栖动物产生直接影响外,还会通过改变沉积物理化因子特征,间接对大型底栖动物产生影响。对于3种食性功能群来说,产生影响作用的主要生境因子存在明显差异。虽然各食性功能群的物种数均有下降,但相对另外两种功能群而言,沉积物中的营养环境还是更利于杂食者的生存,因此杂食者在竞争过程中更具优势。未来相关研究需要在多因子系统监测的基础上,结合洪季的观测结果,进行综合分析。     

单环刺螠engrailed和hedgehog基因在体壁中的表达特征

本文采用Masson染色技术,确定了单环刺螠体壁的组织排列特征,由外向内依次为假复层柱状上皮、外环肌层、中纵肌层、内环肌层,各组织之间由发达的结缔组织连接。采用原位杂交和免疫组织化学技术,确定单环刺螠engrailed和hedgehog基因的mRNA及蛋白均定位于体壁的结缔组织中,尤以外环肌层两侧的结缔组织中阳性信号更明显。探讨了两个基因在单环刺螠体壁功能维持中的潜在作用。     

基于高分一号卫星影像的珊瑚岛礁分类方法

在国内外学者对珊瑚岛礁分类体系的研究的基础上,提出了一种适用范围较广的分类体系,利用高分一号多光谱卫星数据,对西沙群岛华光礁和盘石屿进行了最小距离、马氏距离、最大似然、神经网络、支持向量机等基于像元的监督分类和使用面向对象分类,并对分类结果进行精度评估。两次实验结果表明,支持向量机和面向对象分类方法精度较高,且面向对象分类方法具有更好的目视效果,在一定程度上能满足当前珊瑚岛礁信息提取的需要。     

The ARIEL Instrument Control Unit design

In this paper we present the electromagnetic modeling and beam pattern measurements of a 16-elements ultra wideband sparse random test array for the low frequency instrument of the Square Kilometer Array telescope. We discuss the importance of a small array test platform for the development of technologies and techniques towards the final telescope, highlighting the most relevant aspects of its design. We also describe the electromagnetic simulations and modeling work as well as the embedded-element and array pattern measurements using an Unmanned Aerial Vehicle system. The latter are helpful both for the validation of the models and the design as well as for the future instrumental calibration of the telescope thanks to the stable, accurate and strong radio frequency signal transmitted by the UAV. At this stage of the design, these measurements have shown a general agreement between experimental results and numerical data and have revealed the localized effect of un-calibrated cable lengths in the inner side-lobes of the array pattern.     

Active galactic nuclei: what’s in a name?

Active galactic nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different “flavours” in the literature that now comprise a complex and confusing AGN “zoo”. It is increasingly clear that these classifications are only partially related to intrinsic differences between AGN and primarily reflect variations in a relatively small number of astrophysical parameters as well the method by which each class of AGN is selected. Taken together, observations in different electromagnetic bands as well as variations over time provide complementary windows on the physics of different sub-structures in the AGN. In this review, we present an overview of AGN multi-wavelength properties with the aim of painting their “big picture” through observations in each electromagnetic band from radio to \(\gamma \)-rays as well as AGN variability. We address what we can learn from each observational method, the impact of selection effects, the physics behind the emission at each wavelength, and the potential for future studies. To conclude, we use these observations to piece together the basic architecture of AGN, discuss our current understanding of unification models, and highlight some open questions that present opportunities for future observational and theoretical progress.     

模糊ISODATA法在矿物包裹体成分研究中的应用

矿物包裹体是在成岩成矿过程中保留下来的原始物质,对其成分进行研究,可以提供诸如成岩成矿的物化条件、矿床成因、成岩演化等多方面的信息。就具体矿床而言,成矿物质常常具多源性,矿床的形成往往是各种因素共同作用的产物,其成因具有模糊性。如产于火山岩体或岩浆岩体附近的层控矿床,既具有沉积层控的特点,又受到火山活动或岩浆活动的影响,二者没有一个明确的成因界线。对此模糊现象,运用模糊ＩＳＯＤＡＴＡ法来讨论不同矿床矿物包裹体成分特点,以此探讨矿床的成因类型。     

东海污损生物群落研究Ⅲ.群落结构

计算东海29 个试验点污损生物群落之间的相似系数,并进行聚类分析。根据分析结果,东海污损生物群落可分为4 个类型: 河口群落、近岸群落、内湾群落和远岸群落     

The April 1996 Irpinia seismic sequence: Evidence for fault interaction

The analysis of the Irpinia earthquake of 3 April 1996 (ML = 4.9), based on strong motion and short period local data, shows that it was a normal faulting event located within the epicentral area of the MS 6.9, 1980, earthquake. It was located at 40.67° N and 15.42° E at a depth of 8 km. The local magnitude (4.9) has been computed from the VBB stations of the MedNet network. The moment magnitude is Mw = 5.1 and the seismic moment estimated from the ground acceleration spectra is 5.0 1023 dyne cm. Spectral analysis of the strong motion recordings yields a Brune stress drop of 111 bars and a corner frequency of 1 Hz. The source radius associated to these values of seismic moment and stress drop is 1.3 km. The focal mechanism has two nodal planes having strike 297°, dip 74°, rake 290° and strike 64°, dip 25° and rake 220°, respectively. A fault plane solution with strike 295° ± 5°, dip 70° ± 5°, and rake 280° ± 10° is consistent with the S-wave polarization computed from the strong motion data recorded at Rionero in Vulture. We discuss the geometry and the dimensions of the fault which ruptured during the 1996 mainshock, its location and the aftershock distribution with respect to the rupture history of the 1980 Irpinia earthquake. The distribution of seismicity and the fault geometry of the 1996 earthquake suggest that the region between the two faults that ruptured during the first subevents of the 1980 event cannot be considered as a strong barrier (high strength zone), as it might be thought looking at the source model and at the sequence of historical earthquakes revealed by paleoseismological investigations.     

Badlands as a hot spot of petrogenic contribution to riverine particulate organic carbon to the Gulf of Lion (NW Mediterranean Sea)

Determining the riverine carbon fluxes to oceans is critical for an improved understanding of C budgets and biogeochemical cycles (C, O) over a broad range of spatial and time scales. Among the particulate organic carbon (POC) involved in these fluxes, those yielded by sedimentary rocks (petrogenic POC: pPOC) remain somewhat uncertain as to their source on continental surfaces. Based on time series from long‐term observatories, we refine the POC and sediments flux of the Rhône River, one of the major tributaries to the Mediterranean Sea. Radiocarbon measurements on a set of riverine samples and forward modelling were used to (i) determine a modelled pPOC content and pPOC/POC ratio for each sample set, (ii) assess pPOC flux delivered to the NW Mediterranean Sea, and (iii) estimate the badlands contribution from the Durance catchment to both the pPOC and to sediment discharges. The weighted pPOC flux contributes up to 26% of the POC flux (145 Gg yr^‐1) discharged into the Mediterranean Sea, whereas the weighted pPOC content reaches 0.31 wt%. Despite their low contributive surface area (0.2%), badlands provide, respectively, 12, 3.5 and 14% of the pPOC, POC and sediment fluxes to the Rhône River. Consequently, such rocks can be considered as a major source of pPOC and sediments for the NW Mediterranean Sea and potentially for oceans. We suggest that river‐dominated ocean margins, such as the Rhône River, with badlands in their catchment could export a significant amount of pPOC to the oceans. Copyright © 2018 John Wiley & Sons, Ltd.