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Coupled phase‐field modeling of domain and fracture evolution in anisotropic ferroelectric ceramics
摘要： The contribution presents a material model for the simulation of domain and fracture evolution in ferroelectric ceramics. Ferroelectric domains and cracks are modeled by using a phase field. While for the modeling of the ferroelectric domains we consider the vectorial electric polarization as order parameter, the modeling of cracks is based on a scalar damage variable. In the present contribution, we discuss the evolution of domains and cracks in an anisotropic ferroelectric solid.
关键词： domain evolution,ferroelectric ceramics,fracture evolution,phase-field modeling,anisotropy
更新于2025-09-16 10:30:52
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Research on Self-Organizing Evolution Level of Chinaa??s Photovoltaic Industry Chain System
摘要： According to the self‐organizing theory, we first constructed an index system of the self‐organizing evolution level of China?s photovoltaic (PV) industry chain system from two aspects: of development level and synergy level. Furthermore, according to the relevant data of China?s PV industry, the self‐organizing evolution level of the system from 2008 to 2017 was measured and evaluated by using the system evolution level measurement model and cloud model. Finally, the GM (1, 1) model was used to predict the self‐organizing evolution level of the system from 2018 to 2022. The results show that the overall self‐organizing evolution level of China?s PV industry chain system shows a rising trend in the ten years from 2008 to 2017, gradually transitioning from a low evolution level to a relatively low evolution level, with the evolution level declining in 2012 and 2015. It is expected that the self‐organizing evolution level will continue to maintain a stable and orderly growth trend in the next five years, entering a medium evolution level stage from 2021. If the current evolution speed can be maintained, it is expected to reach a self‐organizing evolution state in the next 20 years or so.
关键词： evolution level,self‐organizing evolution,PV industry chain
更新于2025-09-16 10:30:52
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Modeling of thermal behavior and microstructure evolution during laser cladding of AlSi10Mg alloys
摘要： An improved three-dimensional finite element model has been proposed for studying the thermal behavior and microstructure evolution during laser cladding of AlSi10Mg alloys. Different material properties between AlSi10Mg powders and AlSi10Mg alloys are distinguished from the experiment and theoretical calculation to provide more reliable material parameters for simulation. In order to investigate the melting and solidification process during the formation of cladding layers, a temperature selection judgment mechanism is established to simulate the evolution of AlSi10Mg powders from the powder state to melting state and alloy state. In addition, to simulate the complex thermal behavior associated with powder particles and the voids between particles, a simplified exponential attenuation model is used for correcting the heat source. A complex asymmetric heat source considering about the different material properties and laser absorptivity on both sides of the remelting zone is used for multi-track cladding process. By simulating the temperature distribution of molten pool, the improved FEM could be used to predict the geometric shape of cladding layers (ignoring the effect of melting flow) and the temperature history. The simulation results show that the heat tends to diffuse to the unmelted powder owing to the asymmetric heat source during multi-track cladding, which leads to the asymmetry of cladding layers along the width direction. Based on the results of the temperature field simulations and the solidification characteristics of AlSi10Mg powders, the temperature gradient (G), solidification growth rate (R), cooling rate (G*R) and G/R are investigated to predict the morphology and size of the solidification microstructure under different laser scanning parameters. The scanning speed mainly determines the cooling rate during the laser cladding process, which results in different microstructures. Higher scanning speed leads to higher cooling rate, corresponding to a finer microstructure. Coarse dendrites are generated at the bottom of the molten pool, while finer dendrites are formed at the top.
关键词： Simulation,Microstructure evolution,AlSi10Mg alloy,Laser cladding,Thermal behavior
更新于2025-09-16 10:30:52
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Ultrafast fabrication of Cu oxide micro/nano-structures via laser ablation to promote oxygen evolution reaction
摘要： Despite the tremendous efforts on the preparation of efficient oxygen evolution reaction (OER) electrocatalysts, it is still a challenge to fabricate stable OER electrocatalysts with good performance on a large scale in a simple, fast, green, and environment-friendly way. Herein, we report a simple way via femtosecond laser ablation to fabricate Cu oxide micro/nano-structures on Cu foams by fine-tuning of the laser parameters. The present method is ultrafast, non-contact, high efficiency, easy control, sustainable, and environment-friendly. The fabricated catalysts exhibit remarkable OER activity and excellent durability in 1 M KOH.
关键词： Water splitting,Laser ablation,Metal oxides,Oxygen evolution reaction
更新于2025-09-16 10:30:52
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Plasmonic Au nanoparticle-decorated Bi2Se3 nanoflowers with outstanding electrocatalytic performance for hydrogen evolution
摘要： Hydrogen production from water splitting through electrocatalytic or photoelectrochemical route shows great potential for renewable energy conversion. Herein, the plasmon-enhanced photoelectrical nanocatalysts (NCs) have been successfully developed by Au nanoparticle-decorated Bi2Se3 nanoflowers (Au@Bi2Se3 NFs) as catalysts for hydrogen evolution reaction (HER), leading to a more than 3-fold increase of current under excitation of Au localized surface plasmon resonance (LSPR) and affording a markedly decreased overpotential of 375 mV at a current density of 10 mA cm?2. The HER enhancement can be largely attributed to effective electron-charge separation and the increase of carrier density in Bi2Se3 induced by the injection of hot electrons of Au nanoparticles. Meanwhile, Bi2Se3 nanoflowers (NFs), a kind of topological insulators, possess gapless edges on boundary and show metallic character on surface, providing a path for the flow of electrons in the electrocatalytic system. This study opens up a new avenue towards the design of higher energy conversion catalytic water splitting systems with the assistance of light energy, which could increase of HER catalysis efficiency by plasmonic excitation.
关键词： Hydrogen evolution reaction,Plasmonic,Bi2Se3,Au
更新于2025-09-16 10:30:52
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Adiabatic Vlasov theory of ultrastrong femtosecond laser pulse propagation in plasma. The scaling of ultrarelativistic quasi-stationary states: spikes, peakons, and bubbles
摘要： The interaction of an ultrashort (femtosecond), pancake-shaped laser pulse with underdense unmagnetized plasma is studied analytically and numerically in a regime with ultrarelativistic electron jitter velocities. The adiabatic evolution of the quasistationary electron distribution function is resolved by following particles along their nonlinear trajectories in phase space. It is estimated that under typical laser-plasma accelerator conditions, the quasistationary distribution is established after the pulse has penetrated ≈1 mm into the plasma. The main particle effect is found to be the beam loading associated with the electrons reflected from the maxima of the effective potential, a fraction of which can also be entrapped in the time dependent potential minima. Owing to the relativistic mass increase, their participation in the plasma dynamics is reduced. The number density of reflected particles is exponentially small for nonrelativistic electron temperatures, but at the wavebreak, it can become comparable to the density of the background plasma if the temperature of electrons exceeds several percent of their rest energy m0c2. Numerical calculations in the presence of beam loading and in the strong intensity regime, based on the three-time scale approximation[Jovanovic′ et al., Phys. Plasmas 22, 043110.1 (2015)], reveal the creation of a bubble in the electron density, along with the steepening and the breaking of the nonlinear Langmuir wake that occurs simultaneously with the creation of a sharp spike in the distribution function and a peak in the electron density, located at the position of the wavebreak.
关键词： plasma,beam loading,ultrarelativistic electron jitter velocities,ultrashort laser pulse,wavebreak,adiabatic evolution
更新于2025-09-16 10:30:52
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Parameters Identification of Photovoltaic Models Using a Multi-Strategy Success-History-Based Adaptive Differential Evolution
摘要： Parameters identi?cation of photovoltaic (PV) models based on measured current-voltage characteristics curves is signi?cant for the simulation, evaluation and control of PV systems. To accurately and reliably identify the parameters of different PV models, a novel optimization algorithm, multi-strategy success-history based adaptive differential evolution with linear population size reduction (MLSHADE), is proposed. MLSHADE mainly divides evolutionary process into two phases during every generation. According to the de?nition of class probability variable, the population individuals of ?rst phase are assigned to different two populations for exploration and exploitation, respectively. The novelty of MLSHADE algorithm lies primarily in three improvements: (i) a new weighted mutation strategy is used to enrich the population diversity of later iterations for differential evolution population in the ?rst phase; (ii) inferior solutions search (ISS) technique is presented to avoid falling into local optimum for covariance matrix adaptation evolution strategy population in the ?rst phase; and (iii) Eigen Gaussian random walk strategy is proposed to help maintain effectively the balance between the global exploration and local exploitation abilities in the second phase. The experiments on CEC 2018 test suite illustrate that the proposed MLSHADE exerts the better performances against the stat-of-the-art algorithms in terms of accuracy, reliability and time consumption. The proposed MLSHADE is used to solve the parameters identi?cation problems of different PV models including single diode, double diode, and PV module. Comprehensive experiment results and analyses indicate that MLSHADE can obtain a highly competitive performance compared with other state-of-the-art algorithms, especially in terms of accuracy and reliability.
关键词： Differential evolution operator,numerical optimization,parameters identi?cation of photovoltaic,multi-strategy LSHADE
更新于2025-09-16 10:30:52
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Pulsed Laser Deposition of Nanostructured MoS3/np-Mo//WO3?y Hybrid Catalyst for Enhanced (Photo) Electrochemical Hydrogen Evolution
摘要： Pulsed laser ablation of MoS2 and WO3 targets at appropriate pressures of background gas (Ar, air) were used for the preparation of new hybrid nanostructured catalytic ?lms for hydrogen production in an acid solution. The ?lms consisted of a nanostructured WO3?y underlayer that was covered with composite MoS3/np-Mo nanocatalyst. The use of dry air with pressures of 40 and 80 Pa allowed the formation of porous WO3?y ?lms with cauli?ower- and web-like morphology, respectively. The ablation of the MoS2 target in Ar gas at a pressure of 16 Pa resulted in the formation of amorphous MoS3 ?lms and spherical Mo nanoparticles. The hybrid MoS3/np-Mo//WO3?y ?lms deposited on transparent conducting substrates possessed the enhanced (photo)electrocatalytic performance in comparison with that of any pristine one (MoS3/np-Mo or WO3?y ?lms) with the same loading. Modeling by the kinetic Monte Carlo method indicated that the change in morphology of the deposited WO3?y ?lms could be caused by the transition of ballistic deposition to di?usion limited aggregation of structural units (atoms/clusters) under background gas pressure growth. The factors and mechanisms contributing to the enhancement of the electrocatalytic activity of hybrid nanostructured ?lms and facilitating the e?ective photo-activation of hydrogen evolution in these ?lms are considered.
关键词： pulsed laser deposition,tungsten oxides,transition metal chalcogenides,nanocatalysts,hydrogen evolution reaction,background gas
更新于2025-09-16 10:30:52
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Surface morphology evolution during pulsed selective laser melting: Numerical and experimental investigations
摘要： A novel physical model for the selective laser melting (SLM) was proposed, providing insights into the surface morphology evolution in the pulsed SLM process. Both Marangoni effect and recoil pressure, which were the prevailing driving forces for the melt flow, were incorporated in the model. It was found that the melt track was characterized by regular fish scale patterns in pulsed remelting process, due to the periodic variation of the molten pool, while the melt track exhibited with a smooth surface under a continuous laser mode. The effect of the exposure time on the surface morphology was also investigated during pulsed SLM process. It was shown that the longer exposure time could produce greater recoil pressure and sufficient molten liquid, leading to a more congested fish scale patterns. The surface defects such as distortions and breakups were strongly associated with the distribution characteristics of the powders. The partially melted particles which attached to the melt flow were the main reasons to the formation of distortions. And the formation the breakups could be attributed to the local lacking of the powders. The simulated results were in good agreement with the experimental results.
关键词： Surface morphology,Surface defects,Pulsed selective laser melting,Exposure time,Molten pool evolution
更新于2025-09-16 10:30:52
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Atomistic kinetic Monte Carloa??Embedded atom method simulation on growth and morphology of Cua??Zna??Sn precursor of Cu <sub/>2</sub> ZnSnS <sub/>4</sub> solar cells
摘要： An atomistic kinetic Monte Carlo coupled with the embedded-atom method is used to simulate film growth and morphology evolution of a Cu–Zn–Sn precursor of Cu2ZnSnS4 solar cells by single-step electrodeposition. The deposition and diffusion events of three different metallic atoms are described by the simulation. Moreover, the multibody Cu–Zn–Sn potential is used to calculate diffusion barrier energy. The effects of process factors, including temperature and electrode potential, on the cross-section morphology and surface roughness are explored, while keeping the elemental composition ratios constant. The lowest roughness with the smoothest morphology is obtained at the optimal parameters. The distribution and transformation behaviors of cluster sizes are investigated to describe the alloy film growth process. Furthermore, the comparison between deposition events and diffusion events reveals that deposition events depend primarily on individual deposition rates of different metallic atoms, but diffusion events are mainly dependent on the interaction of metallic atoms. The film morphology evolution is visualized by three-dimensional configuration with increasing numbers of atoms, which suggests a competing mechanism between nucleation and growth of the thin film alloy.
关键词： Cu–Zn–Sn precursor,film growth,Cu2ZnSnS4 solar cells,electrodeposition,atomistic kinetic Monte Carlo,morphology evolution,embedded-atom method
更新于2025-09-16 10:30:52