Mechanical properties of calcareous silts in a hydraulic fill island-reef

Abstract

The mechanical characteristics of calcareous silt interlayers play an important role in the stability of island-reef foundations. Direct shear and consolidation tests were performed to study the relationship between the mechanical properties and the physical parameters of calcareous silt. Based on the consolidation test results and analysis of the settling examples, different calculation methods for soil settling were compared. The results show the following. (1) The relationship between the cohesion and water content of calcareous silt can be represented by an M-shaped curve. The water contents corresponding to the two peaks of the M-type curve increase with increasing dry density. (2) When the dry density is less than 1.33?g/cm³, increasing the density significantly improves the internal friction angle of calcareous silts. When the dry density of the calcareous silt is greater than 1.33?g/cm³, the internal friction angle is affected by both the dry density and the water content. (3) The shear strength decreases when the water content exceeds the optimum level. (4) The compressive modulus of calcareous silt is larger than that of terrigenous silt. Specifically, it decreases with decreasing dry density and increasing water content. (5) The stepwise loading method should be used to estimate the soil settling before fill engineering construction.     

A System for Fast Cartographic Sounding Selection

Soundings on nautical charts provide information about the shape of the ocean bottom between chart depth curves. A single chart may have thousands of soundings posted on it. This article describes a system for automatic cartographic sounding selection. In this system, a new algorithm for automated selecting soundings is developed. The algorithm is employed in such a way that it can guarantee (a) fast and accurate selecting sounding, (b) processing the circular depth curves, (c) solving the overplotting problems between depth curves and soundings, and (d) keeping selected soundings “prettier.” The system was intensively tested using real data sets, and its superiority has been revealed by the testing results.     

Improving performances of ITO/GaP contact on AlGaInP light-emitting diodes

In this paper AlGaInP light emitting diodes with different types of electrodes: Au/Zn/Au-ITO Au/Ti-ITO Au/Ge/Ni-ITO and Au-ITO are fabricated. The photoelectricity properties of those LEDs are studied. The results show that the Au/Zn/Au electrode greatly improves the performance of LEDs compared with the other electrodes. Because the Au/Zn/Au electrode not only forms a good Ohmic contact with indium tin oxide (ITO), but also reduces the specific contact resistances between ITO and GaP, which are 1.273×10^-6 Ω · cm² and 1.743×10^-3 Ω ·cm² between Au/Zn/Au-ITO and ITO-GaP respectively. Furthermore, the textured Zn/Au-ITO/Zn electrode is designed to improve the performances of LEDs, reduce the forward-voltage of the LED from 1.93 to 1.88 V, and increase the luminous intensity of the LEDs from 126 to 134 mcd when driven at 20 mA.     

Formation of saddle dolomites in Upper Cambrian carbonates, western Tarim Basin (northwest China): Implications for fault-related fluid flow

The saddle dolomites occur more intensely in cores closely to fault than that in cores far away from the fault in Upper Cambrian carbonate of western Tarim basin, suggesting that formation of the saddle dolomites is likely related to fault-controlled fluid flow. They partially fill in fractures and vugs of replacement dolomite. The saddle dolomites exhibit complex internal textures, commonly consisting of core and cortex. In comparison with the matrix dolomites, the saddle dolomites show lower Sr-content and ⁸⁷Sr/⁸⁶Sr ratios, higher Fe- and Mn-content, and more negative δ¹⁸O values. Combined with high Th (100–130 °C) of primary fluid inclusions, it is suggested that the saddle dolomites precipitated from hydrothermal fluid derived from the deep evaporite-bearing Middle Cambrian strata, and the magnesium source may be due to dissolution of host dolomite during hydrothermal fluid migration. Fault activity resulted in petrographic and geochemical difference of the core and cortex of the saddle dolomites. The cores precipitated from the formation water mixed by deep brines at the early stage of fault activity, and the cortexes precipitated from the deep fluid with higher temperatures through the Middle Cambrian later. In summary, the formation of the saddle dolomites implies a hydrothermal fluid event related to fault activity, which also resulted in high porosity in Upper Cambrian carbonate in western Tarim Basin.     

黄海温度锋及断面水温分布数值预报试验硏究

自Simpson和Hunter(1974)在对夏季爱尔兰海的研究中提出潮混合控制潮汐锋的概念以来,人们相继在许多强潮浅水区发现了潮汐锋现象,并做了大量的研究工作,对锋区的流场结构等特征,以及潮汐锋对周围环境的影响等有了更多的了解。在我国,赵保仁(1985)首先提出黄海存在潮汐锋现象,认为冷水团的温度锋可看作是底层的潮汐锋,并可利用近最大潮流流速计算层化参量来确定黄海潮汐锋(从而亦即温度锋)的位置,而且还可以根据已有调查资料和卫星图片揭示它的一些变化规律。他与合作者的一系列研究工作表明:黄海的潮混合及潮汐锋现象对黄海的温盐和水团分布、层化现象、强温跃层的分布变化、黄海的水平和垂直环流有重要影响和直接关系,进而可以推测黄海的潮混合及潮汐锋现象对黄海的物质输运、生态环境等有着重要的影响,因此研究黄海潮混合形成的温度锋和断面温度分布的数值预报方法是非常有必要的。 以往关于潮汐锋的数值研究大多数是诊断模式,用于求解潮汐锋形成以后锋区的环流结构等,而用数值方法模拟潮汐锋的形成和演化的工作却很少。在国外,只有王东平等(Wang et al.,1990)用二维模型,对垂直涡动扩散和粘性系数采用Munk-Anderson格式与湍流封闭格式嵌套的方法以反映边界层的作用,利用实测的大气强迫力和数值计算的潮流模拟了英国Celtic海的潮汐锋和海洋层化的变化问题,尚未涉及潮汐锋的形成过程。在国内,Bi和Zhao(1993)用一个二维数值模式对黄海34°N的潮汐锋进行了模拟,较好地模拟了从4月到8月潮汐锋的形成和演化过程。在此基础上,我们将进一步利用潮流分布及海面的热量和动量输入条件,以垂直均匀状态为初始条件,模拟黄海各主要断面的温度分布、温度锋和温跃层在增温期的形成和演化过程。     

总体最小二乘法在浮游植物色素吸收系数模型估算中的应用

采用常规最小二乘法(LS)和总体最小二乘法(TLS)对浮游植物色素吸收系数与叶绿素a浓度之间的关系进行了研究。利用2003-2012年6个航次243组实测数据,建立了LS和TLS模型,应用模型估算典型波段的色素吸收系数值,并对两种模型进行了验证。采用平均绝对百分误差和均方根误差两种方法进行模型效果评估,结果显示,两种评估方法均能很好地说明,在400～700 nm光谱范围内,TLS拟合结果优于LS拟合结果。总体最小二乘法在综合考虑了参数误差和测量误差的情况下,拟合结果精度更高,更符合实际情况,估算结果的准确性要优于常规最小二乘法。     

Spatio-temporal variability in sea surface temperatures for the Yellow Sea based on MODIS dataset

The spatio-temporal variabilities in sea surface temperature (SST) were analyzed using a time series of MODIS datasets for four separate regions in the Yellow Sea (YS) that were located along a north-south axis. The space variant temporal anomaly was further decomposed using an empirical orthogonal function (EOF) for estimating spatially distributed SST. The monthly SSTs showed similar temporal patterns in each region, which ranged from 2.4°C to 28.4°C in the study years 2011 to 2013, with seasonal cycles being stronger at the higher latitudes and weaker at the lower latitudes. Spatially, although there were no significant differences among the four regions (p < 0.05) in any year, the geographical distribution of SST was characterized by an obvious gradient whereby SST decreased along the north-south axis. The monthly thermal difference among regions was largest in winter since the SST in the southeast was mainly affected by the Yellow Sea Warm Currents. The EOF1 mode accounted for 56% of the total spatial variance and exhibited a warming signal during the study period. The EOF2 mode accounted for 8% of the total variance and indicated the warm current features in the YS. The EOF3 mode accounted for 6% of the total variance and indicated the topographical features. The methodology used in this study demonstrated the spatio-temporal variabilities in the YS.     

全球三大洋海山钴结壳资源量估算

钴结壳具有Co、Ni、Cu和Mn及其他金属的潜在矿产资源和储存在结壳层中古环境信息的双重意义。与深海多金属结核和热液硫化物矿床相比,具有较高Co、Ni和Pt含量的海山钴结壳有可能成为商业勘探的潜在目标。为合理地估算出全球三大洋海山钴结壳资源量,基于我国西太平洋海山钴结壳拖网采样调查资料和对太平洋海山钴结壳资源分布规律和钴结壳矿区圈定参数指标的深入研究,按海山不同高度、不同洋壳年龄赋予不同结壳厚度,进而计算出全球三大洋海山钴结壳分布面积为3 039 452.14km2和干结壳资源量为(1 081.166 1~2 162.332 2)×108 t。太平洋海山钴结壳分布面积为2 123 087.12km2和干结壳资源量为(513.244~1 026.488)×108 t,大西洋海山钴结壳分布面积为512 509.74km2和干结壳资源量为(116.503 2~233.006 4)×108 t,印度洋海山钴结壳分布面积为403 855.28km2和干结壳资源量为(81.484 9~162.969 8)×108 t。三大洋海山钴结壳的Mn、Co、Ni和Cu金属量分别为(138.848 0~277.696 0)×108 t,(3.967 6~7.935 2)×108 t、(2.793 6~5.587 2)×108 t和(0.825 1~1.650 2)×108 t。根据钴结壳的Co含量、Co通量和厚度相关分析,所赋予的钴结壳厚度占理论推测厚度的6.10%~12.20%,这与Ku等得出"钴结壳生长时间约占其整个生命史4%"的认识非常相近。三大洋海山钴结壳实测厚度与赋值厚度对比分析表明,太平洋海山钴结壳赋值厚度平均值为1.87cm,实测厚度平均值为1.77cm,相对误差为5.35%,大西洋和印度洋相对误差分别为18.18%和23.23%。研究数据表明按海山高度和洋壳年龄所赋的钴结壳厚度基本合理,估算出的钴结壳资源量基本可靠。本文首次估算出三大洋海山钴结壳资源量,为整个海盆和三大洋海山钴结壳资源量估算提供了新方法。     

近60年来长江河口河势变化及其对水动力和盐水入侵的影响I.河势变化

河势是影响河口水动力和盐水入侵基本因子。本文利用20世纪50和70年代长江河口海图,数值化岸线和水深,结合2012年长江河口实测水深资料,分析长江河口自50年代以来的河势变化。长江河口为分汊河口,50年代仅为二级分汊,至70年代才形成三级分汊,四口入海的河势格局。70年代相比于50年代,北支淤浅严重,其上、中、下段容积变化分别为-64.13×106、-306.60×106和-639.27×106 m3,对应的变化率分别为-16.30%、-22.74%和-25.69%,均显著减小;南支的上、中、下段容积变化分别为-28.61×106、-35.69×106和126.43×106 m3,相应的变化率分别为-1.30%、-2.12%和4.36%;北港由于崇明浅滩和横沙浅滩的淤浅,下段容积明显减小,其上段和下段容积变化分别为109.21×106和-797.14×106 m3,对应的变化率分别为5.01%和-15.25%;南港上段由于河道淤浅容积减小,下段北由于铜沙浅滩被冲开形成北槽,导致水深变深、容积增加,其上段、下段北和下段南容积变化分别为-238.95×106、203.58×106和153.34×106 m3,对应的变化率分别为-8.96%、6.85%和3.26%。2012年相比于70年代,北支由于大量淤浅和围垦容积大幅减小,其上、中、下段容积变化分别为-199.06×106、-504.61×106和-654.12×106 m3,对应的变化率分别为-60.45%、-48.44%和-35.38%;南支的上、中、下段容积变化分别为92.34×106、193.01×106和-163.62×106 m3,相应的变化率分别为4.24%、11.73%和-5.40%;北港上段青草沙水库的围垦和下段横沙东滩的围垦造成面积和容积减小,其上段和下段容积变化分别为-154.64×106和-511.79×106 m3,对应的变化率分别为-6.75%和-11.55%;南港由于上段河道刷深而下段九段沙以及南汇边滩淤浅、围垦,导致其容积上段增加,下段减小,上段、下段北和下段南容积变化分别为136.39×106、-658.28×106和-1266.11×106 m3,对应的变化率分别为5.62%、-20.73%和-26.06%。     

松江鲈(Trachidermus fasciatus)泛素结合酶E2-D2基因的分子克隆及组织表达分析

泛素结合酶(UbcE2)是蛋白泛素化过程中所必需的酶,在泛素转移和底物的特异性识别方面发挥着重要的作用。本实验利用RACE技术克隆获得了全长为993bp的松江鲈泛素结合酶E2-D2基因cDNA序列(命名为TfUbcE2-D2),其开放阅读框为444bp,编码147个氨基酸。通过SMART预测得知,TfUbcE2-D2含有一个UBCc结构域。同源比对结果表明该基因与其他物种的同源性为92.31%。实时荧光定量PCR显示,TfUbcE2-D2广泛表达于松江鲈各组织,在肾脏中的相对表达量最高,其次为鳃。鳗弧菌(Vibrio anguillarum)刺激后,TfUbcE2-D2在血液、脾脏、肝脏和鳃中表达均上调,其中,脾脏和鳃中的表达量上调约40倍。由以上实验结果推测,TfUbcE2-D2可能参与松江鲈的先天免疫防御。