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The perceptual video coding systems for optimization have been developed on the basis of different attributes of the human visual system. The attention-based coding system is considered as an important part of it. The saliency map method representing the region-of-interest (ROI) from the video signal has become a reliable method due to advances in the computer performance and the visual algorithms. In the present study, we propose a hybrid compression algorithm that uses the deep convolutional neural network to compute the spatial saliency followed by extraction of the temporal saliency from the compressed-domain motion information. The level of uncertainty is calculated to combine to form the video's saliency map. Afterwards, the QP search range is dynamically adjusted in HEVC, and a rate distortion calculation method is proposed to choose the pattern and guide the allocation of bits during the video compression process. Empirical reporting results proved the superiority of the proposed method over the state-of-the-art perceptual coding algorithms in terms of saliency detection and perceptual compression quality. [ABSTRACT FROM AUTHOR]

As a typical marine and underwater infrastructure, the joints stress state of immersed tunnels is complicated due to the differential settlement during operation. Based on the current attitude of the segmental elements, this study takes GZ Tunnel as an example to preliminarily discuss the influence of differential settlement on the mechanical behavior of immersed tunnels through field monitoring, on-site detection and numerical simulation. The result shows that: The differential settlements of immersed tunnels can be divided into longitudinal and transverse, specifically manifested as bending or torsion of elements. The maximum longitudinal settlement and maximum transverse settlement of immersed elements is 108.7 mm and 27.9 mm, respectively. Under the influence of differential settlement in different directions, and the shear keys of the central wall and the sidewall with larger settlements are subjected to greater forces. Numerical simulation shows that the maximum principal stress and minimum principal stress of GZ Tunnel can reach 20.87 MPa and 22.21 MPa, respectively, which is located at the joint between E2 element and the northern buried element. The failure mode of the shear keys is cracking near the inner corners and local concrete crushing. The failure reason can be summarized as the compressive or tensile shear caused by the misalignment and torsion of the elements. The reason of differential settlement of GZ tunnel is caused by construction and long-term operation. In studying underwater facilities such as immersed tunnels under the influence of differential settlement, it is suggested to consider the three-dimensional attitude change of the structure comprehensively. [ABSTRACT FROM AUTHOR]

The water scarcity in China's coal bases is intensifying due to rapid development of modern coal chemical industry and inefficient water utilization. Previous studies on industrial water optimization were predominantly focused on direct water, overlooking the associated indirect water consumptions throughout supply chains. In this study, a water footprint (WF)-based allocation optimization framework is developed to obtain optimal solutions for water resources utilization constrained by quantity of water supply and coal chemical production related limiting factors. The framework comprises a novel WF accounting model especially used for the coal-to-chemical industry and a water allocation optimization model that integrates direct and indirect water consumptions. A typical major large-scale coal base in China was chosen as the study area. Results showed that the cradle-to-gate WF of the various coal-based products ranged from 2.01 m3/t to 70.85 m3/t, in which the internal operational and supply-chain blue WFs were the dominant contributors. Statistical analysis suggested that the volumetric WF of the coal-based products was strongly correlated with both market price and production stage while the variation of WF increased as products were further processed. Optimization result indicated that the maximized economic income of the products under current scenario was 66.23 billion CNY/year in the study area, whereas the overlapping of limited water resources and the insufficiency of downstream production capacity restricted the economic performance by over 20%. In addition, sensitivity analysis was conducted and the results showed that, in order to improve the overall economic income, deployment of more advanced technologies for saving water should be prioritized over that for saving feedstock, while conservation of power was the least preferable. Unlabelled Image • A water footprint (WF)-based allocation optimization framework is developed. • A novel WF method is proposed to assess WF of various coal-to-chemicals. • The total WF of coal-to-chemicals ranges from 2.01 m3/t to 70.85 m3/t. • The maximized local income rises 20% with adequate water and methanol supplies. [ABSTRACT FROM AUTHOR]

We propose a novel hybrid-dimensional model for the Darcy–Forchheimer flow in fractured rigid porous media, with a natural applicability to non-conforming meshes. Motivated by the previous work on the reinterpreted discrete fracture model (RDFM) for Darcy flows, we extend its key idea to non-Darcy flows. Coupling the Darcy's law in the matrix and the Forchheimer's law in the fractures through the introduction of the Dirac- δ functions to characterize the fractures, we derive a relationship between the total flow velocity in the porous media and the fluid velocity in the fractures. With this relation, it is natural to model the Darcy–Forchheimer flow in the whole computational domain by one equation. The local discontinuous Galerkin (LDG) method is applied for numerical discretization of the steady-state single-phase flow problem and a time-marching method is adopted to find the solution of the resulting nonlinear system. Besides, we construct a direct solver for the nonlinear equation of the fluid velocity in fracture to save computational cost. As an application, we discuss a simple transport model coupled with the flow equation. Several numerical experiments validate the performance of the model with its effectiveness on non-conforming meshes. We observe that the Darcy–Forchheimer model effectively reduce the flow rates and make the predictions more realistic in case of excessive fracture velocities. • Construct a hybrid-dimensional Darcy–Forchheimer model in fractured porous media. • The model is applicable on non-conforming meshes. • Two different derivations were provided. • Add pseudo time variable in the numerical scheme. [ABSTRACT FROM AUTHOR]

• Combine the reinterpreted discrete fracture model with contaminant transportation. • The degree of freedom keeps the same as the number of fractures increases. • Construct enriched Galerkin methods to preserve the local mass conservation for the pressure equation. • Design the bound-preserving technique to enforce the physical bounds of the concentration. The discrete fracture model (DFM) has been widely used to simulate fluid flow in fractured porous media. Traditional DFM is considered to be limited on conforming meshes, hence significant difficulty may arise in generating high-quality unstructured meshes due to the complexity of the fracture networks. Recently, Xu and Yang reinterpreted DFM and demonstrated that it can actually be extended to non-conforming meshes without any essential changes. However, the continuous Galerkin (CG) method was applied and the local mass conservation was missing. This paper is a follow-up work, and we apply the interior penalty discontinuous Galerkin (IPDG) method and enriched Galerkin (EG) method for the pressure equation. With the numerical fluxes, the local mass is conservative. As an application, we combine the reinterpreted DFM (RDFM) with the incompressible miscible displacements in porous media. The bound-preserving techniques are applied to the coupled system. We can theoretically guarantee that the concentration is between 0 and 1. Finally, several numerical experiments are given to demonstrate the good performance of the RDFM based on the above two methods on non-conforming meshes and the effectiveness of the bound-preserving technique. [ABSTRACT FROM AUTHOR]