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Highlights • The coherent structure in the whole channel of the 7-rod bundle lattice was numerical simulated. • The occurrence and the development of the coherent structure were presented. • The performances of three different lattices which had different coherent structures were compared. • The influences of corner channel and wall channel to the coherent structure in little lattice were analyzed. Abstract The generation and development of coherent structure in 7-rod bundle lattice are researched by Unsteady Reynolds-Averaged Navier-Stokes (URANS) method with the Reynolds Stress Model (RSM). The influence of the coherent structure on the flow resistance and heat transfer coefficient is also analyzed. It is revealed that the coherent structure is helpful to improve the performance of lattice. Decreasing the pitch-to-diameter (P/D) or properly changing the shape of rod can contribute to the generation of coherent structure. The flow redistribution caused by corner channel has great influence to the coherent structure. [ABSTRACT FROM AUTHOR]

Increasing nitrogen oxides (NO x ) emissions over the fast developing regions have been of great concern due to their critical associations with the aggravated haze and climate change. However, little geographically specific data exists for estimating spatio-temporal trends of NO x emissions. In order to quantify the spatial and temporal variations of NO x emissions, a spatially explicit approach based on the continuous satellite observations of artificial nighttime stable lights (NSLs) from the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) was developed to estimate NO x emissions from the largest emission source of fossil fuel combustion. The NSL based model was established with three types of data including satellite data of nighttime stable lights, geographical data of administrative boundaries, and provincial energy consumptions in China, where a significant growth of NO x emission has experienced during three policy stages corresponding to the 9 th –11 th Five-Year Plan (FYP, 1995–2010). The estimated national NO x emissions increased by 8.2% per year during the study period, and the total annual NO x emissions in China estimated by the NSL-based model were approximately 4.1%–13.8% higher than the previous estimates. The spatio-temporal variations of NO x emissions at city scale were then evaluated by the Moran's I indices. The global Moran's I indices for measuring spatial agglomerations of China's NO x emission increased by 50.7% during 1995–2010. Although the inland cities have shown larger contribution to the emission growth than the more developed coastal cities since 2005, the High–High clusters of NO x emission located in Beijing-Tianjin-Hebei regions, the Yangtze River Delta, and the Pearl River Delta should still be the major focus of NO x mitigation. Our results indicate that the readily available DMSP/OLS nighttime stable lights based model could be an easily accessible and effective tool for achieving strategic decision making toward NO x reduction. [ABSTRACT FROM AUTHOR]

• A new type of water level intelligent monitoring was proposed. • Based on the SSD, the water level was extracted by the staff gauge recognition. • The method can safely and accurately measure the water level throughout the day. Water levels are essential components for the observation and management of water resources. However, the existing water level monitoring methods either require manpower, which is inefficient, or are restricted to a certain environment. This paper proposes a novel approach that can automatically monitor, recognize and calculate the water level based on deep learning. First, a series of experiments were performed in a physical pool to obtain images from real scenes. Then, the original Single Shot MultiBox Detector (SSD) preprocessing model was trained and optimized. Subsequently, a trained and verified staff gauge detection model was obtained, which was applied to extract the staff gauge information from images. Finally, a 24-hour time series of water level changes was simulated and analyzed using photographic images principle, and the NSE and R2 were 0.98 and 0.99, respectively. These results indicate that the proposed method is more accurate in practice and can provide a relatively accurate and reliable measurement technique. [ABSTRACT FROM AUTHOR]