Urban flood vulnerability assessment in a densely urbanized city using multi-factor analysis and machine learning algorithms

Theoretical and Applied Climatology - Flood is considered as the most devastating natural hazards that cause the death of many lives worldwide. The present study aimed to predict flood...     

Shear behaviour of subgrade soil with reference to varying initial shear stress and plasticity index

Acta Geotechnica - The influence of stress anisotropy (K) (i.e. the ratio between effective horizontal and vertical stresses) on the shear behaviour of soils has received significant attention in...     

Local stress analysis in granular materials at a mesoscale

The purpose of this paper is to contribute to the change of scale techniques developed for granular materials. The proposed approach consists in considering an intermediate scale between the macroscales and microscales, called the mesoscale, using the classical homogenization scheme. In this approach, the mesoscale for 2D granular materials was defined at the level of local volumes, called mesodomains, which are local closed structures composed of particles in contact. In this paper, we focused on defining a local stress field at this scale. Two different methods are proposed, both based on the equivalent continuum mean stress but using different approximations of the mean stress tensor for each mesodomain. The two proposed methods were then compared to each other. Analyses performed on the stress field at the mesoscale show that this local field is heterogeneous and, in particular, that its heterogeneity is significantly structured at this scale. The distribution of the local mean stress (first invariant of the local stress tensor) is uniform in any mesodomain, whereas the distribution of the stress deviator (second invariant of the deviatoric part of the local stress tensor) is significantly dependent on the elongation direction and on the elongation degree of the mesodomains. The local stress ratio (ratio of the stress deviator to the mean stress) is higher within the mesodomains that are elongated in the global compression direction than that within the ones elongated in the global extension direction. Copyright © 2011 John Wiley & Sons, Ltd.     

Cold deep water in the South China Sea

Two deep channels that cut through the Luzon Strait facilitate deep (>2000 m) water exchange between the western Pacific Ocean and the South China Sea. Our observations rule out the northern channel as a major exchange conduit. Rather, the southern channel funnels deep water from the western Pacific to the South China Sea at the rate of 1.06 ± 0.44 Sv (1 Sv = 10⁶ m³s⁻¹). The residence time estimated from the observed inflow from the southern channel, about 30 to 71 years, is comparable to previous estimates. The observation-based estimate of upwelling velocity at 2000 m depth is (1.10 ± 0.33) × 10⁻⁶ ms⁻¹, which is of the same order as Ekman pumping plus upwelling induced by the geostrophic current. Historical hydrographic observations suggest that the deep inflow is primarily a mixture of the Circumpolar Deep Water and Pacific Subarctic Intermediate Water. The cold inflow through the southern channel offsets about 40% of the net surface heat gain over the South China Sea. Balancing vertical advection with vertical diffusion, the estimated mean vertical eddy diffusivity of heat is about 1.21 × 10⁻³ m²s⁻¹. The cold water inflow from the southern channel maintains the shallow thermocline, which in turn could breed internal wave activities in the South China Sea.     

Nearshore scavenging phenomenon elucidated by <Superscript>234</Superscript>th/<Superscript>238</Superscript>u disequilibrium in the coastal waters off Western Taiwan

Dissolved and particulate ²³⁴Th activities in surface seawater were determined at 27 stations along the coastline of western Taiwan during 19–23 November 2004. Contrasting scavenging settings were observed between the northern and southern regimes of the nearshore water off western Taiwan, separated by the Cho-Shui River. The northern regime is characterized by a large quantity of suspended load contributed by northward transport of a suspension plume from the Cho-Shui River, while the southern regime, low in suspended load and high in chlorophyll concentration, is a system controlled by biological activity. A scavenging model that takes account of the physical transport was used to estimate the ²³⁴Th budget in order to estimate the scavenging and removal rates from the nearshore water. The scavenging and removal rates ranged from 21 to 127 dpm m⁻³d⁻¹ and from 36 to 525 dpm m⁻³d⁻¹, for dissolved and particulate ²³⁴Th, respectively. The removal fluxes of particulate organic carbon (POC) and particulate organic nitrogen (PON) were estimated by multiplying the particulate ²³⁴Th removal flux to the organic carbon/²³⁴Th and nitrogen/²³⁴Th ratios in suspended particles, which ranged from 4.5 to 275.2 mmol-C m⁻²d⁻¹ and from 1.3 to 50.1 mmol-N m⁻²d⁻¹, respectively. These fluxes resulted in residence times of 1∼20 days for the POC in the surface water of nearshore water off western Taiwan.     

Tyrosinase, a new innate humoral immune parameter in large yellow croaker （Pseudosciaena crocea R）

We evaluated the immune response to infection with a pathogen in large yellow croaker(Pseudosciaena crocea Richardson).The fish were given an intraperitoneal(i.p.) injection of Vibrio parahaemolyticus or sterile sea water(control).We collected blood sera from the fish 0.17,1,2,4,8,12,or 16 d after injection(dpi).We measured tyrosinase activity and the concentrations of lysozyme,NOS,and antibodies.Serum tyrosinase activity was significantly higher at 0.17 and 4 dpi than in the control group,and peaked at 8 d...     

Geological evolution,regional perspectives and hydrocarbon potential of the northwest Phu Khanh Basin,offshore Central Vietnam

Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest–southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion, triggered by right-lateral wrenching near the Palaeogene–Neogene boundary. Following the onset of this inversion regional uplift and volcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north, leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence and siliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area.     

城市生活固体废弃物处置规划和场地选址方向探讨

城市生活固体废弃物已成为重要环境污染问题之一,地质环境工作应为废弃物的填埋选址,防治污染提供服务。北京地质环境部门受北京市主管部门委托开展了全市生活固体废弃物填埋场地适宜性区划,卫生填埋场地环境地质影响评价,其成果已为市规划、环境行政部门所利用。     

利用InSAR获取2020年新疆于田Mw6.3地震同震形变场与断层滑动分布反演

本文基于InSAR技术,利用欧空局Sentinel-1A/B升降轨SAR数据,提取了2020年6月26日新疆于田Mw6.3地震的同震形变场.利用升、降轨同震形变场约束,分别采用MPSO算法和Bayesian方法反演此次地震发震断层均匀滑动的几何参数,并进行对比.然后采用SDM方法获得发震断层非均匀滑动分布,并分析了同震...