水文重力效应改正中一维地下水模拟算法的对比

基于一维地下水渗透方程详细推导其有限差分解算过程,引入不同于显式差分的隐式差分和中心差分格式,对比分析不同差分格式对地下水模拟结果及其相应地下水重力效应的影响,并对其中的层间参数取值和非线性方程的线性化问题进行探讨。结果表明,在日本Isawa扇形地区超导台站,不同层间参数加权公式能够引起最大约0.15 μGal的重力效应差异,影响在1.9%以内;不同差分格式和线性化方法组合形式能够引起最大约0.12 μGal的重力效应差异,影响在1.5%以内。     

Seismogenic Structures of the 2006 ML4.0 Dangan Island Earthquake Offshore Hong Kong

The northern margin of the South China Sea, as a typical extensional continental margin, has relatively strong intraplate seismicity. Compared with the active zones of Nanao Island, Yangjiang, and Heyuan, seismicity in the Pearl River Estuary is relatively low. However, a ML4.0 earthquake in 2006 occurred near Dangan Island(DI) offshore Hong Kong, and this site was adjacent to the source of the historical M5.8 earthquake in 1874. To reveal the seismogenic mechanism of intraplate earthquakes in DI, we systematically analyzed the structural characteristics in the source area of the 2006 DI earthquake using integrated 24-channel seismic profiles, onshore–offshore wide-angle seismic tomography, and natural earthquake parameters. We ascertained the locations of NW-and NE-trending faults in the DI sea and found that the NE-trending DI fault mainly dipped southeast at a high angle and cut through the crust with an obvious low-velocity anomaly. The NW-trending fault dipped southwest with a similar high angle. The 2006 DI earthquake was adjacent to the intersection of the NE-and NW-trending faults, which suggested that the intersection of the two faults with different strikes could provide a favorable condition for the generation and triggering of intraplate earthquakes. Crustal velocity model showed that the high-velocity anomaly was imaged in the west of DI, but a distinct entity with low-velocity anomaly in the upper crust and high-velocity anomaly in the lower crust was found in the south of DI. Both the 1874 and 2006 DI earthquakes occurred along the edge of the distinct entity. Two vertical cross-sections nearly perpendicular to the strikes of the intersecting faults revealed good spatial correlations between the 2006 DI earthquake and the low to high speed transition in the distinct entity. This result indicated that the transitional zone might be a weakly structural body that can store strain energy and release it as a brittle failure, resulting in an earthquake-prone area.     

Spatial Variations of b-Values in the Coastal Area of Guangdong

We used earthquake catalogs recorded by Guangdong Seismological Network from 2008 to 2014 to resolve the spatial variations of b-values in the coastal area of Guangdong, particularly in three key research areas(Yangjiang, Heyuan, and offshore Nanao Island) with strong seismicity. Our results revealed that b-values exhibited significant spatial variations, and zones with low b-values could indicate the most likely seismogenic area of large earthquakes. We observed three clear low b-value patches in the offshore Nanao Island. We found a distinct high b-value peak at the depth of 11 km and two minimum peaks at about 14 and 7–8 km in the Yangjiang area. The overall b-values generally decrease with depth in the Heyuan area. The spatial variations of b-values reflect tectonic anomalies; that is, the ‘low-high-low' distribution of b-values in the offshore Nanao Island and the Yangjiang area may indicate the anomaly of the crustal structure with a weak layer. The b-values of reservoir-induced seismicity are obviously lower than that induced by tectonism. This finding indicates that the reservoir area is generally at high stress state under the condition of high pore pressure. We inferred that large earthquakes might be prone to occur at 10–12 km depth in the offshore Nanao Island, at 12–15 km depth in the Yangjiang area, and at the lower part of the seismic activity zone in the Heyuan area. Moreover, the upstream area of the Xinfengjiang reservoir is the most likely area of future large earthquakes in the Heyuan area.     

海岸破波带内悬沙空间分布试验研究和解析表达式

关于海岸破波带内悬沙浓度水平和垂向分布的研究对于计算海岸输沙率和地形演变具有重要意义。本研究进行了规则波、波群和不规则波三种波浪情况破波带内悬沙浓度的水平和垂向分布的试验测量。试验在大尺度波浪水槽进行,接近实际海岸波况尺度。给出了破波带内多断面悬沙垂向分布的细致测量结果,并以此为基础给出了预报实际海岸破波带内悬沙浓度水平和垂向分布解析表达式,讨论了形成这些分布的物理原因和不同波况、不同破波带区域对分布的影响。     

SWAN模型对实验室小尺度浅水波浪模拟研究

基于浅水斜坡地形的物理模型试验数据,考察SWAN模型对实验室小尺度浅水波浪的模拟效果,进而检验其浅水项的模拟精度。模拟中采用直接输入初始测点的实测海浪谱进行造波,重点考察浅水中三波相互作用和变浅破碎两个源项,对不同工况下,SWAN模式在水深条件变化下的有效波高、谱平均周期、海浪谱演化的模拟能力进行研究。研究表明:模拟的有效波高较符合实测波浪的增长和衰减,但谱平均周期计算值明显偏小;海浪谱的能量转移机制同实测有较大区别,频谱模拟结果出现高频高估、低频低估现象。对两个源项进行对比分析得出三波相互作用对海浪谱的能量转换影响远大于变浅破碎耗散。想要提高近岸区谱平均周期和海浪谱的模拟精度则SWAN模型中三波非线性项的计算精确度仍需更多研究和改进。     

开孔率对明基床上开孔沉箱波浪反射系数影响的数值研究

开孔率是开孔沉箱波浪反射系数的重要影响因素,迄今为止关于开孔沉箱的物模试验研究成果(包括《防波堤设计与施工规范》)中,开孔率μ通常以线性关系反映在开孔沉箱波浪反射系数的计算关系式中,适用范围为0.2~0.4。但当μ0.2或μ0.4时,开孔率μ对波浪反射系数Kr的影响规律尚需进一步的研究探讨。现借助二维数值波浪水槽,在扩大了的开孔率取值范围内,模拟不规则波与可渗明基床上开孔沉箱的相互作用。结果表明:在0.2≤μ≤0.4的范围内,用线性关系描述开孔率μ对波浪反射系数Kr的影响是合适的;在μ0.4时,数模值和物模试验拟合的经验关系式的趋势是一致的;在μ0.2时,开孔沉箱反射系数K_r随开孔率μ的减小而增大,用物模试验拟合的经验关系式及《防波堤设计与施工规范》中计算公式的线性关系来描述开孔率μ对反射系数K_r的影响是不恰当的。研究成果对开孔沉箱消浪机理的深入认识和开孔沉箱结构的优化设计具有重要意义。     

无人机影像在测绘1∶500海岛地形图中的应用

通过介绍无人机航摄系统的优点,结合无人机航摄系统高效快捷、地面分辨率高、成本低等特点,对无人机影像采集、影像处理、制作成图的流程进行了归纳;通过虎平岛的实例,对无人机在海岛1∶500地形图测绘中的应用进行了全面的分析和精度比对,进而说明无人机影像可应用于海岛大比例尺地形图的制作。     

基于可靠性的海洋立管疲劳安全系数研究

综合考虑了立管疲劳安全系数取值的相关因素——立管的安全等级、设计寿命、检验周期、载荷和损伤计算方法等的不确定性,提出了基于可靠度的疲劳安全系数确定方法,筛选了用于计算波致疲劳和VIV(涡激振动)疲劳的随机变量,给出了立管波致疲劳与VIV疲劳安全系数的计算流程,并以某SCR(钢悬链线立管)为例进行了安全系数计算。结果表明,该方法的计算结果优于传统的安全系数确定方法,尤其适合于特殊工程方案或新颖设计的立管疲劳校核。     

基于SLAF-seq技术开发蓝圆鲹微卫星标记及跨物种扩增检测

采用基于高通量测序平台的SLAF-seq技术开发蓝圆鲹(Decapterus maruadsi)微卫星标记,从获得的1 450个四至六碱基重复微卫星位点中随机挑选93个位点进行引物合成和多态性检测,最终开发出31个多态性微卫星标记.群体遗传学检测结果表明,31个位点的等位基因数为4~29(均值13.48),观测杂合度(Ho)为0.281~0.875(均值0.650),期望杂合度(He)为0.557~0.958(均值0.838),多态信息含量值(PIC)为0.456~0.939(均值0.803),表明所开发的31个微卫星位点均具有较高的多态性.Hardy-Weinberg平衡检测表明,17个位点符合HWE("哈迪-温伯格"平衡),且各位点间不存在连锁不平衡现象.跨物种扩增结果显示,分别有27、20、20、18、9个微卫星标记在颌圆鲹(Decapterus macarellus)、长身圆鲹(Decapterus macrosoma)、无斑圆鲹(Decapterus kurroides)、竹荚鱼(Trachurus japonicus)及金带细鲹(Selaroides leptolepis)中具有较好的通用性.本研究开发的多态性长碱基重复微卫星标记可为蓝圆鲹渔业资源的科学管理和保护提供有力的遗传学评估手段,亦可为圆鲹属和鲹科鱼类系统进化研究提供新的分析手段.     

中西医结合治疗2型糖尿病30例总结

目的：观察二甲双胍联合养阴降浊汤治疗2型糖尿病的临床疗效。方法：将60例2型糖尿病患者随机分为治疗组和对照组各30例,治疗组采用二甲双胍联合养阴降浊汤治疗,对照组单用二甲双胍治疗。比较2组综合疗效及血糖血脂水平。结果：总有效率治疗组为86.7%,对照组为53.3%,组间比较,差异有统计学意义（P<0.05）;治疗组血糖血脂各项观察指标及对照组FPG治疗前后组内比较,差异均有统计学意义（P<0.05）;2组各项观察指标治疗后组间比较,差异均有统计学意义（P<0.05）。结论：二甲双胍联合养阴降浊汤能有效降低2型糖尿病患者的血糖,改善血脂,值得在临床上推广。