High-performance energy storage dielectrics have been the key to solve energy problems in the context of energy crisis. Designing multilayered structure is an effective approach to breaking the paradox between...

Abstract. Flash floods have occurred frequently in the urban areas of southern China. An effective process-oriented urban flood inundation model is urgently needed for urban storm-water and emergency management. This study develops an efficient and flexible cellular automaton (CA) model to simulate storm-water runoff and the flood inundation process during extreme storm events. The process of infiltration, inlets discharge and flow dynamics can be simulated with little preprocessing on commonly available basic urban geographic data. In this model, a set of gravitational diverging rules are implemented to govern the water flow in a rectangular template of three cells by three cells of a raster layer. The model is calibrated by one storm event and validated by another in a small urban catchment in Guangzhou of southern China. The depth of accumulated water at the catchment outlet is interpreted from street-monitoring closed-circuit television (CCTV) videos and verified by on-site survey. A good level of agreement between the simulated process and the reality is reached for both storm events. The model reproduces the changing extent and depth of flooded areas at the catchment outlet with an accuracy of 4 cm in water depth. Comparisons with a physically based 2-D model (FloodMap) show that the model is capable of effectively simulating flow dynamics. The high computational efficiency of the CA model can meet the needs of city emergency management.

Poly(vinylidene fluoride)-based (PVDF) composites with high discharged energy density (U e ) have been considered as advanced dielectric materials for pulsed power systems and electrical weapon systems. However, further improvement of the U e of PVDF-based composites with higher breakdown strength (E b ) is of utmost importance. Based on the principle of voltage distribution in the multilayer structure, the multilayer structure (five-layer structure) ceramic/polymer composite films consisting of pristine PVDF layers with high breakdown strength and PVDF layers doped with one-dimensional 0.15SrTiO 3 -0.85Na 0.5 Bi 0.5 TiO 3 (1D SNBT) fibers where the two kinds of layers stacked alternately has been designed and fabricated. Accordingly, a series of analyses of the dielectric properties and energy storage performances are presented, and the related results are tentatively explained by finite element simulation. The energy storage characteristics of the composite films are greatly improved due to the newly designed structure. An excellent U e of 20.82 J cm −3 is achieved at an ultrahigh electric field of 640 MV m −1 with the PVDF layers containing 6 vol % SNBT fibers. Therefore, this work provides a new strategy to design and fabricate advanced polymer-based energy storage materials.

Abstract. Flash floods have occurred frequently and severely in the urban areas of South China. An effective process-oriented urban flood inundation model becomes an urgent demand for urban storm water and emergency management. This study develops an effective and flexible cellular automaton (CA) model to simulate storm water runoff and the flood inundation process during extreme storm events. The process of infiltration, inlets discharge and flow dynamic can be simulated only with little pre-processing on commonly available basic urban geographic data. In this model, a set of gravitational diverging rules are implemented in a cellular automation (CA) model to govern the water flow in a 3 x 3 cell template of a raster layer. The model is calibrated by one storm event and validated by another in a small urban catchment in Guangzhou of Southern China. The depth of accumulated water at the catchment outlet is interpreted from street monitoring sensors and verified by on-site survey. A good level of agreement between the simulated process and the reality is reached for both storm events. The model reproduces the changing extent and depth of flooded areas at the catchment outlet with an accuracy of 4 cm in water depth. Comparisons with a physically-based 2-D model (FloodMap) results show that the model have the capability of simulating flow dynamics. The high computational efficiency of CA model can satisfy the demand of city emergency management. The encouraging results of the simulations demonstrate that the CA-based approach is capable of effectively representing the key processes associated with a storm event and reproducing the process of water accumulation at the catchment outlet for making process-considered city emergency management decisions.