Influence of construction interfaces on dynamic characteristics of roller compacted concrete dams

To study the influence of construction interfaces on dynamic characteristics of roller compacted concrete dams(RCCDs),mechanical properties of construction interfaces are firstly analyzed. Then, the viscous-spring artificial boundary(VSAB) is adopted to simulate the radiation damping of their infinite foundations, and based on the Marc software, a simplified seismic motion input method is presented by the equivalent nodal loads. Finally, based on the practical engineering of a RCC gravity dam, effects of radiation damping and construction interfaces on the dynamic characteristics of dams are investigated in detail. Analysis results show that dynamic response of the RCC gravity dam significantly reduces about 25% when the radiation damping of infinite foundation is considered. Hot interfaces and the normal cold interfaces have little influence on the dynamic response of the RCC gravity dam.However, nonlinear fracture along the cold interfaces at the dam heel will occur under the designed earthquake if the cold interfaces are combined poorly. Therefore, to avoid the fractures along the construction interfaces under the potential super earthquakes,combination quality of the RCC layers should be significantly ensured.

Analytic model of deformation of construction interfaces of rolled control concrete dam

The construction interfaces of RCCD have a distinct influence on the deformation of dams. The characters and rules on deformation of construction interfaces are studied. The methods simulating the deformation of the interfaces at different stages are proposed. A thickness analytic model and a no-thickness analytic model of construction interfaces are built. These models can reflect the elastic deformation, the attenuation creep deformation, the irreversible creep deformation and the accelerating creep defor- mation of interfaces. The example shows that these proposed models can simulate the deformation of the dam structure objectively. Especially, the results of the thickness analytic model which simulates the gradual changing regularities of interfaces can tally with those of monitoring in situ preferably. The methods proposed and the analytic models can be generalized and applied to general concrete dams, especially to the analysis on deformation rules of fault and interlayer in dam base.

Construction of multiple interfaces and dielectric/magnetic heterostructures in electromagnetic wave absorbers with enhanced absorption performance:A review

The construction of structures with multiple interfaces and dielectric/magnetic heterostructures enables the design of materials with unique physical and chemical properties,which has aroused intensive interest in scientific and technological fields.Especially,for electromagnetic(EM)wave absorption,enhanced interface polarization and improved impedence match with high Snoek's limitation could be achieved by multiple interfaces and dielectric/magnetic heterostructures,respectively,which are benificial to high-efficiency electromagnetic wave absorption(EWA).However,by far,the principles in the design or construction of structures with multiple interfaces and dielectric/magnetic heterostructures,and the relationships between those structures or heterostructures and their EWA performance have not been fully summarized and reviewed.This article aims to provide a timely review on the research progresses of high-efficency EM wave absorbers with multiple interfaces and dielectric/magnetic heterostructures,focusing on various promising EWA materials.Particularly,EM attenuation mechanisms in those structures with multiple interfaces and dielectric/magnetic heterostructures are discussed and generalized.Furthermore,the changllenges and future developments of EM wave absorbers based on those structures are proposed.

In-situ formed NiS/Ni coupled interface for efficient oxygen evolution and hydrogen evolution

High-performance electrocatalysts for water splitting are desired due to the urgent requirement of clean and sustainable hydrogen production.To reduce the energy barrier,herein,we adopt a facile in-situ surface modification strategy to develop a low-cost and efficient electrocatalyst for water splitting.The synthesized mulberry-like NiS/Ni nanoparticles exhibit excellent catalytic performance for water splitting.Small overpotentials of 301 and 161 mV are needed to drive the current density of 10 mA cm^-2 accompanying with remarkably low Tafel slopes of 46 and 74 mV dec^-1 for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER),respectively.Meanwhile,a robust electrochemical stability is demonstrated.Further high-resolution X-ray photoelectron spectroscopy analyses reveal that the intrinsic HER activity improvement is attributed to the electron-enriched S on the strongly coupled NiS and Ni interface,which simultaneously facilitates the important electron transfer,consistent with the electrochemical impedance results.The post characterizations demonstrate that surface reconstructed oxyhydroxide contributes to the OER activity and NiS/Ni is an OER precatalyst.This structure construction with in-situ formation of active interface provides an effective way to design efficient electrocatalysts for energy conversion.