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Estuarine environmental capacity is the foundation for coastal biological diversity and self-purification capacity. Hence, studies on the marine environmental capacity (MEC) are the foundation for the total discharge control and water quality improvement of land-based pollutants. In the article, A calibrated two-dimensional hydrodynamic model was used to study the environmental characteristics of Sanmen Bay. The model results were used to estimate the environmental capacity of the bay. Taking the pollution problem in Sanmen Bay as an example, the method of response factor, the sub-unit control method, and the phased control method were used to estimate the environmental capacity, pollutant amounts, and the pollutant reduction in the bay. The concentrations of COD, inorganic nitrogen, and acid salt in Sanmen Bay are spatially varied, with higher values occurring in the western part and in the inner bay. The half exchange time of the whole bay is about 23 days, and the exchange time of 95% water body is about 60 days. The evaluation of MEC can not only provide technical support for the offshore aquaculture industries but also provide a scientific basis for the total control of terrigenous pollutants in coastal cities in Southern Zhejiang Province.

Xiangshan Bay is a semi-enclosed bay in China, in which tidal flats have been substantially reclaimed to support the development of local economies and society over previous decades. The loss of tidal flats has led to changes of tides and locally suspended sediment in the bay. The effects of tidal flat reduction on locally suspended sediment dynamics was investigated using a numerical model forced by tidal data and calibrated by observed tidal elevation and currents. The model satisfactorily reproduces observed water levels, currents, and suspended sediment concentration in the estuary, and therefore is subsequently applied to analyze the impact of tidal flat reclamation on locally suspended sediment transport. After the loss of the tidal flats from 1963 to 2010, the suspended sediment concentrations (SSC) at the bottom boundary layer were reduced/increased in the outer bay/tidal flat areas due to weakened tidal currents. In the inner bay, the SSC values near the bottom level increased from 1963 to 2003 due to the narrowed bathymetry, and then decreased from 2003 to 2010 because of the reduced tidal prism. The model scenarios suggest that: (1) a reduction of tidal flat areas appears to be the main factor for enhancing the transport of sediments up-estuary, due to the increased Eulerian velocity and tidal pumping; (2) A reduction of tidal flat areas impacts on spatial and temporal SSC distribution: reducing the SSC values in the water areas due to the reduced current; and (3) a tidal flat reduction influences the net sediment fluxes: lessening the erosion and inducing higher/lower landward/seaward sediment transportation.

This paper studies the long-termed displacement of a tunnel boring machine (TBM) resting on soft clay during its unscheduled stoppage for 100 days. It is based on a real case of tunneling in a coastal city of Ningbo in China. The numerical prediction is carried out by using different soil models in the software PLAXIS, and the prediction is compared with on-site measurement of the displacement. Different factors are considered in the prediction, including soil creeping and the disturbance to the soft clay during the tunneling. The study indicates that the consideration of disturbance is essential to the accurate prediction. While advanced soil models including the soft soil model and soft soil creep model are not able to accurately predict the TBM displacement, the consideration of soil disturbance leads to a very good agreement with the measurement. The accurate prediction of ground settlements also justifies consideration of the disturbance in the study of tunneling. © 2018 Elsevier Ltd

Most vegetation indices (VIs) of remote sensing were designed based on the concept of soil-line, which represents a linear correlation between bare soil reflectance at the red and near-infrared (NIR) bands. Unfortunately, the soil-line can only suppress brightness variation, not color differences of bare soil. Consequently, soil variation has a considerable impact on vegetation indices, although significant efforts have been devoted to this issue. In this study, a new soil-line is established in a new feature space of the NIR band and a virtual band that combines the red and shortwave-infrared (SWIR) bands (0.74ρred+0.26ρswir). Then, plus versions of vegetation indices (VI+), i.e., normalized difference vegetation index plus (NDVI+), enhanced vegetation index plus (EVI+), soil-adjusted vegetation index plus (SAVI+), and modified soil-adjusted vegetation index plus (MSAVI+), are proposed based on the new soil-line, which replaces the red band with the red-SWIR band in the vegetation indices. Soil spectral data from several spectral libraries confirm that bare soil has much less variation for VI+ than the original VI. Simulation experiments show that VI+ correlates better with fractional vegetation coverage (FVC) and leaf area index (LAI) than original VI. Ground measured LAI data collected from BigFoot, VALERI, and other previous references also confirm that VI+ derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data correlates better with ground measured LAI than original VI. These data analyses suggest that replacing the red band with the red-SWIR band can reduce the sensitivity of VIs to soil background. We recommend employing the proposed NDVI+, EVI+, SAVI+, and MSAVI+ in applications of large area, sparse vegetation, or when soil color variation cannot be neglected, although sensitivity to soil moisture and clay content might cause slight side effects for the proposed VI+s.

Damutu Bay in eastern Zhejiang, China has abundant tidal flat resources for years of silt deposition in the wide open seas, making it an ideal place for mudflat reclamation. In this study we set up a two-dimensional hydrodynamic and sediment transport model based on Mike 21 FM to investigate changes in suspended sediment concentration (SSC) after reclaiming to 1 m and 3 m depth contours in the seas. The model results are compared temporally and spatially to field observations in December, 2011 and August, 2012 of water levels, current velocities, and SSC, and indicate a strong data-model agreement. This study shows the sensitivity of the system to changes in SSC and suggests that a large-scale tidal flat reclamation could reduce SSC by 15∼20% on average in Damutu seas which would influence physical and biological processes particularly in the intertidal areas around the bay.

Islands and coastal cities which have larger amounts of population and abundant marine resources, often bear the important responsibility of economic development. And environmental problems that coexist with it are occupied an important position of urban construction. What's more, high turbidity water caused by high sediment concentration has a great influence on coastal landscape and production. From this point of view, this article takes the representative turbid archipelago — Zhoushan as an example and a two-dimensional numerical model of suspended sediment is established. It is indicated that the suspended sediment concentration (SSC) decreases from west to east in Zhoushan archipelago sea area and SSC is closely related to flow direction and flow speed in the study area. Detailed research has been conducted about the influence that different coastal engineering may have on sediment transportation and coastal sediment concentration, and results demonstrate that the flow field and sediment field in the study area has changed dramatically because of the projects. Flow velocity and sediment concentration of feature points in the study area respectively decrease by 78.3% and 75.6% at most.

One of the major problems in the liquid insulation is the particle contamination, which can seriously degrade the withstand voltage of the insulation. The movement of conducting particles under operation voltage can generate incipient discharges that can lead to the complete failure of the insulation system during operation. The partial-discharge characteristics of the free spherical conducting particle in the quasiuniform electric field were studied in this paper in order to better explain the partial-discharge (PD) measurement signals for particle movement and implications for insulation diagnostics in power transformers. The phase-resolved partial-discharge (PRPD) pattern was measured and the PD inception voltage, PD charges, and PD frequency were studied under different applied voltages. The influence of oil aging degree to particle PD characteristics was also studied in this paper. It is observed that the PD pattern is different in a different particle motion stage and the number of particles has a significant influence on PD frequency and a slight influence on PD pattern. The particle is inactive in severely aged transformer oil. The PD charges and PD frequency (pulses number per half ac cycle) reduce with the aging degree of the oil sample.

Tidal current power generation system extracts energy by transferring the kinetic energy of tidal movement to the motion of power turbines. The long coastline of China contains abundant tidal energy, but not all coastal area worth exploiting. It is generally considered that a mean spring peak tidal current of at least 2 m/s is required for tidal current power exploitation. Thus we choose to evaluate the tidal kinetic energy of East China Sea coastal area where 95 waterways contained, accounting for 78.6% of China's tidal kinetic energy. Considering the interaction between the Yangtze Estuary and Hangzhou Bay, a high resolution model with unstructured 3D grid system FVCOM (finite volume coastal ocean model) has been applied to simulate tidal motion in the Yangtze Estuary-Hangzhou Bay. The numerical results of the refined model has been validated with: (a) measured tidal currents data after harmonic analysis; (b) measured tide level hydrograph and velocity which were observed by China's coastal physical oceanography and marine meteorological special investigation on the East China Sea during August, 2014. It is also noticed that the area where power density larger than 10 kW/m2 are mainly distributed over North Port of Yangtze Estuary and north of Hangzhou Bay, and the maximal value of the possible maximum velocity of the tidal current reaches 3.0–3.5 m/s at Hangzhou Bay.

The interval tunnel between the Ximen station and the Drum Tower station of Ningbo metro line 1 goes through the national reserve cultural relics of Tianning tower. This interval tunnel is constructed by shield method. To ensure the safety of the Tianning tower, the impact of shield construction on the tower should be evaluated. Two kinds of finite element model (FEM) software are used in the safety assessment to analyze the additional deformation of the Tianning tower caused by shield construction. In order to reduce the differential settlement and incline of the tower, the isolation piles protection is considered to use as a protection method. For the different calculation schemes of pile location, pile length and pile diameter, the protective effect is analyzed and the measures are proposed.