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| 1 | Time-domain Spectral Finite Element Method for Wave Propagation Analysis in Structures with Breathing Cracks显示文摘Guided waves are generally considered as a powerful approach for crack detection in structures,which are commonly investigated using the finite element method(FEM).However,the traditional FEM has many disadvantages in solving wave propagation due to the strict requirement of mesh density.To tackle this issue,this paper proposes an efficient time-domain spectral finite element method(SFEM)to analyze wave propagation in cracked structures,in which the breathing crack is modeled by definiiig the spectral gap element.Moreover,novel orthogonal polynomials and Gauss-Lobatto-Legendre quadrature rules are adopted to construct the spectral element.Meanwhile,a separable hard contact is utilized to simulate the breathing behavior.Finally,a comparison of the numerical results between the FEM and the SFEM is conducted to demonstrate the high efficiency and accuracy of the proposed method.Based on the developed SFEM,the nonlinear features of waves and influence of the incident mode are also studied in detail,which provides a helpful guide for a physical understanding of the wave propagation behavior in structures with breathing cracks. | Zexing Yu Chao Xu Fei Du Shancheng Cao Liaiigxian Gu | 2020 | Acta Mechanica Solida Sinica2020,33,6: | 2 |
| 2 | Amorphous NiO_(n)coupled with trace PtO_(x)toward superior electrocatalytic overall water splitting in alkaline seawater media显示文摘Developing corrosion resistance bifunctional electrocatalysts with high activity and stability toward both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),especially electrolysis in seawater,is of prime significance but still pressingly challenging.Herein,in-situ introduced PtO_(x)on the derivative amorphous NiO_(n)is prepared via heat treatment of Ni ZIFL nanosheets on nickel foam under low temperature(PtO_(x)-NiO_(n)/NF).The synthesized PtO_(x)-NiO_(n)/NF possesses suprahydrophilic and aerophilic surface,then in favor of intimate contact between the electrode and electrolyte and release of the generated gas bubbles during the electrocatalysis.As a result,the in-situ PtO_(x)-NiO_(n)/NF electrode presents outstanding bifunctional activity,which only requires extremely low overpotentials of 32 and 240 mV to reach a current density of 10 mA·cm^(-2)for HER and OER,respectively,which exceeds most of the electrocatalysts previously developed and even suppresses commercial Pt/C and RuO_(2)electrodes.As for two-electrode cell organized by PtO_(x)-NiO_(n)/NF,the voltages down to 1.57 and 1.58 V are necessary to drive 10 mA·cm^(-2)with remarkable durability in 1 M KOH and alkaline seawater,respectively,along with remarkable stability.Moreover,a low cell voltage of 1.88 V is needed to achieve 1,000 mA·cm^(-2)toward water-splitting under industrial conditions.This study provides a new idea for designing in-situ amorphous metal oxide bifunctional electrocatalyst with strong Pt–support interaction for overall water splitting. | Wenli Yu Hongru Liu Ying Zhao Yunlei Fu Weiping Xiao Bin Dong Zexing Wu Yongming Chai Lei Wang | 2023 | Nano Research2023,16,5: | 2 |
| 3 | Surface/Interface Engineering of Hierarchical MoO_(2)/MoNi_(4)@Ru/RuO_(2)Heterogeneous Nanosheet Arrays for Alkaline Water Electrolysis with Fast Kinetics显示文摘Realizing the hydrogen economy by water electrolysis is an attractive approach for hydrogen production,while the efficient and stable bifunctional catalysts under high current densities are the bottleneck that limits the half-cell reactions of water splitting.Here,we propose an approach of hydrothermal and thermal annealing methods for robust MoO_(2)/MoNi_(4)@Ru/RuO_(2) heterogeneous cuboid array electrocatalyst with multiplying surface-active sites by depositing a monolayer amount of Ru.Benefiting from abundant MoO_(2)/MoNi_(4)@Ru/RuO_(2)heterointerfaces,MoO_(2)/MoNi_(4)@Ru/RuO_(2) heterogeneous cuboid array electrocatalysts effectively drive the alkaline water splitting with superior hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)performances.The synthesized MoO_(2)/MoNi_(4)@Ru/RuO_(2) has high HER activity,which realizes the working overpotentials of 48 mV at 50 mA·cm^(-2),further achieving overpotentials of 230 mv for industry-level 1000 mA·cm^(-2) in alkaline water electrolysis.Moreover,it also showed an enhanced OER activity than commercial RuO_(2) with a small overpotential of 280 mV at 200 mA·cm^(-2) in alkaline media.When building an electrolyzer with electrodes of(-)MoO_(2)/MoNi_(4)@Ru/RuO_(2)IIMo02/MoNig@Ru/RuO_(2)(+),a cell voltage of 1.63 V and 1.75 V is just required to support the current density of 200 mA·cm^(-2) and 500 mA-cm^(-2) in alkaline water electrolysis,much lower than that of the electrolyzer of(-)Pt/CIIRuO_(2)(+).This work demonstrates that MoO_(2)/MoNig@Ru/RuO_(2) heterogeneous nanosheet arrays are promising candidates for industrial water electrolysis applications,providing a possibility for the exploration of water electrolysis with a large currentdensity. | Qiong Zhang Ruixue Zhang Yingxiu Zhao Tiantian Sun Jianyang Gao Guang-Rui Xu Zexing Wu Yu Yang Lei Wang | 2024 | Chinese Journal of Chemistry2024,42,2: | 0 |
| 4 | Guided wave propagation analysis in stiffened panel using time-domain spectral finite element method显示文摘Stiffened panels have been widely utilized in fuselages and wings as critical load-bearing components. These structures are prone to be damaged under long-term and extreme loads, and their health monitoring has been a common concern. The guided wave-based monitoring method is regarded as an efficient approach to detect the damage in stiffened plates because of its wide monitoring range and high sensitivity to micro-damage. Efficient simulation of wave propagation can theoretically demonstrate the detection mechanism of the method. In this study, a Time-Domain Spectral Finite Element Method(TD-SFEM) is adopted to study the wavefield in stiffened plates,where continuous Absorbing Layers with Increasing Damping(ALID) strategy is proposed to circumvent the disturbance of reflected waves on boundaries. After the convergence analysis, the developed TD-SFEM with ALID is validated by the finite element method first. Then, wave scattering and the influence of the stiffener are investigated in detail by comparing the results with the non-stiffened structure. Finally, the effects of the parameters of the stiffener, such as the height and width, on wave propagation are studied, respectively. The results illustrate that the proposed TDSFEM with ALID is an efficient approach to study the wave propagation in the stiffened plate and can reveal the mechanism of influence of the stiffener. It is found that the height of the stiffener changes the interference of wavefield in the plate, while the effects of the width are mainly in wave scattering and mode conversion. | Zexing YU Chao XU Jiaying SUN Fei DU | 2022 | Chinese Journal of Aeronautics2022,35,10: | 0 |