An experimental study on microscopic characteristics of gas-bearing sediments under different gas reservoir pressures

Gas-bearing sediments are widely distributed in five continents all over the world. Most of the gases exist in the soil skeleton in the form of discrete large bubbles. The existence of gas-phase may increase or decrease the strength of the soil skeleton. So far, bubbles’ structural morphology and evolution characteristics in soil skeleton lack research, and the influence of different gas reservoir pressures on bubbles are still unclear. The micro characteristics of bubbles in the same sediment sample were studied using an industrial CT scanning test system to solve these problems. Using the image processing software, the micro variation characteristics of gas-bearing sediments in gas reservoir pressure change are obtained. The results show that the number and volume of bubbles in different equivalent radius ranges will change regularly under different gas reservoir pressure. With the increase of gas reservoir pressure, the number and volume of tiny bubbles decrease. In contrast, the number and volume of large bubbles increase, and the gas content in different positions increases and occupies a dominant position, driving the reduction of pore water and soil skeleton movement.     

Characteristics and origins of middle Miocene mounds and channels in the northern South China Sea

Numerous elongated mounds and channels were found at the top of the middle Miocene strata using 2D/3D seismic data in the Liwan Sag of Zhujiang River Mouth Basin(ZRMB) and the Beijiao Sag of Qiongdongnan Basin(QDNB). They occur at intervals and are rarely revealed by drilling wells in the deepwater areas. Origins of the mounds and channels are controversial and poorly understood. Based on an integrated analysis of the seismic attribute, palaeotectonics and palaeogeography, and drilling well enco...     

Storm surge induced flux through multiple tidal passes of Lake Pontchartrain estuary during Hurricanes Gustav and Ike

In September 2008, Hurricanes Gustav and Ike generated major storm surges which impacted the Lake Pontchartrain estuary in Louisiana. This paper presents analyses of in situ measurements acquired during these storm events. The main data used in the analyses were from three bottom mounted moorings equipped with conductivity, temperature, and depth sensors, acoustic Doppler current profilers (ADCPs), and a semi-permanent laterally mounted horizontal acoustic Doppler profiler (ADP). These moorings were deployed in the three major tidal channels that connect Lake Pontchartrain with the coastal ocean. A process similar to tidal straining was observed: the vertical shear of the horizontal velocity was negligible during the inundation stage, but a shear of 0.8 m/s over a less than 5 m water column was recorded during the receding stage, 2–3 times the normal tidal oscillations. The surge reached its peak in the Industrial Canal 1.4–2.1 h before those in the other two channels. The inward flux of water lasted for a shorter time period than that of the outward flux. The inward flux was also observed to have much smaller magnitude than the outward flux (∼960–1200 vs. 2100–3100 million m³). The imbalance was believed to have been caused by the additional water into Lake Pontchartrain through some small rivers and inundation over the land plus rainfall from the hurricanes. The flux through the Industrial Canal was 8–12%, while the flux through the other two tidal passes ranged between 17% and 70% of the total, but mostly split roughly half-half of the remaining (∼88–92% of the total).     

Compact and tunable mid-infrared source based on a 2 μm dual-wavelength KTiOPO4 intracavity optical parametric oscillator

Using a double resonant KTiOPO₄ (KTP) intracavity optical parametric oscillator operating at degenerated point of 2 μm, we demonstrate a unique mid-infrared source based on difference frequency generation in GaSe crystal. The output tuning range is 8.42-19.52 μm, and a peak power of 834 W for type-I phase matching scheme and 730 W for type-II phase matching scheme are achieved. Experimental results show that this oscillator is a good alternative to the generator of a compact and tabletop mid-infrared radiation with a widely tunable range.     

一类信号恢复问题的投影迭代硬阈值算法

本文给出了基于L₀模求解该问题的非凸模型,借助于稀疏正则化方法来克服问题的不适定性。该模型利用紧小波框架对信号进行稀疏逼近,并利用L₀模度量稀疏性。提出了求解该模型的投影迭代硬阈值算法,并证明了算法的全局收敛性。该算法每一步都有闭式解,计算过程简洁高效。数值实验表明,方法在重建信号的视觉质量和量化指标方面均优于所对比的pFISTA方法。     

苯酰胺类化合物防污活性基团的初步探索

开发绿色环保防污剂是海洋船舶防污涂料研究的重要方向,查明防污活性化合物分子结构中的防污活性基团,是设计开发新型防污剂的关键。本文合成了三种结构相似的苯酰胺类化合物HNOB、DOLPA和DHNOB,通过FTIR,1H NMR,13C NMR测试表征三种化合物的分子结构,利用典型污损生物硅藻和贻贝作为目标生物,测试其对硅藻和贻贝附着的影响,并将分子结构与防污活性进行对比,初步探讨影响防污性能的活性基团。硅藻和贻贝附着实验均表明,HNOB的防污性能较好,半数抑制浓度远低于DOLPA和DHNOB。通过结构对比分析发现,极性和非极性结构的协同作用比单一的极性基团或非极性长碳链基团能更好地赋予苯酰胺类物质良好的防污性能。该研究初步探讨了苯酰胺类化合物的构效关系,有助于新型防污活性化合物的设计开发和结构优化,并对探究该类化合物防除污损生物附着的机理和快速筛选有潜力的防污化合物具有重要意义。     

某核电厂附近海域生态环境特征及潜在致灾生物研究

为了了解某核电厂周边海域的生态环境状况,筛选潜在威胁核电厂冷源安全的致灾生物,分析影响致灾生物时空分布的主要环境因素,本研究于2018年进行了4个季节的生态调查。结果表明,研究海域浮游植物密度秋季最高,春季优势种为东海原甲藻(Prorocentrumdonghaiense),其他季节优势种为中肋骨条藻(Skeletonema costatum)等硅藻。浮游动物密度夏季最高,以桡足类为主,春、夏季优势种还包括球型侧腕水母(Pleurobrachiaglobosa)和薮枝螅水母(Obeliasp.)。底栖动物的密度和生物量在秋季最高,优势种主要为豆形短眼蟹(Xenophthalmus pinnotheroides)、长吻沙蚕(Glycera chirori)和丝异须虫(Heteromastusfiliforms)。浮游植物、浮游动物和底栖动物群落均在夏季最为稳定,群落多样性水平和物种丰度较高,且分布较为均匀。浮游植物群落的细胞丰度与悬浮物和磷酸盐的浓度正相关性最高。浮游动物的密度受温度和盐度的影响较大。底栖动物的群落分布主要受悬浮物和无机营养盐的浓度影响。本研究共筛选出17种威胁该核电厂冷...     

Vertical characteristics revealed by biweekly and synoptic variability of upper sea temperature in the northern South China Sea

On the basis of the analysis of the sea temperature data that are observed from the three automatic temperature line acquisition sysem mooring buoys deployed in the central South China Sea (SCS) during South China Sea monsoon experiment, vertical features of biweekly and synoptic variability are discussed. There are five vertical modes, that is, subsurface temperature variability is in phase with,out of phase with, leads to, lags the surface temperature variability, and at depths within the subsurface layer the upper and lower temperature variations are out of phase. The formation of these vertical modes is related to the property of low-level atmospheric forcing and to the background in atmosphere and ocean. Wind stress curl is the main driving factor in forming Modes 1 and 3, and wind stresses in forming Modes 2 and 4.     

真鲷仔稚鱼微粒饲料中DHA与EPA最佳比例的研究

制备4种n-3HUFA含量相同,DHA和EPA含量比[m(DHA)：m(EPA)]分别为1．70：1,2．00：1,2．30：1和2．60：1的微粒饲料,探讨DHA与EPA的配比对真鲷(Pagrus major)仔稚鱼生长、存活和体内相关成分的影响。30d的养殖试验结果表明．m(DHA)：m(EPA)≥2．30：1的2种微粒饲料与m(DHA)：m(EPA)≤2．00：1的2种微粒饲料相比,真鲷仔稚鱼的生长速度和成活率,前者明显优于后者。该比例即m(DHA)：m(EPA)≥2.30：1应是真鲷微粒饲料中DHA与EPA的最佳配比。养殖试验结束后,对仔稚鱼体内相关成分的分析结果表明,仔稚鱼体内DHA的含量随微粒饲料中DHA含量的增加而增大。