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An improved efficient adaptive method for large-scale multiexplosives explosion simulations

Defence technology(防务技术) 2025年第3期45卷 28-47页

作者： Tao Li Cheng Wang Baojun Shi School of Mechanical Engineering Key Laboratory of Advanced Intelligent Protective Equipment TechnologyMinistry of EducationHebei University of TechnologyTianjin300401China State Key Lab of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China

Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of *** utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise results is inefficient in terms of computational *** is particularly evident when large-scale fluid field simulations are conducted with significant differences in computational domain *** this work,a variable-domain-size adaptive mesh enlargement(vAME)method is developed based on the proposed adaptive mesh enlargement(AME)method for modeling multi-explosives explosion *** vAME method reduces the division of numerous empty areas or unnecessary computational domains by adaptively suspending enlargement operation in one or two directions,rather than in all directions as in AME method.A series of numerical tests via AME and vAME with varying nonintegral enlargement ratios and different mesh numbers are simulated to verify the efficiency and order of *** estimate of speedup ratio is analyzed for further efficiency *** large-scale near-ground explosion experiments with single/multiple explosives are performed to analyze the shock wave superposition formed by the incident wave,reflected wave,and Mach ***,the vAME method is employed to validate the accuracy,as well as to investigate the performance of the fluid field and shock wave propagation,considering explosive quantities ranging from 1 to 5 while maintaining a constant total *** results show a satisfactory correlation between the overpressure versus time curves for experiments and numerical *** vAME method yields a competitive efficiency,increasing the computational speed to 3.0 and approximately 120,000 times in comparison to AME and the fully fine mesh method,*** indicates that the vAME method reduces the computational cost with minimal impact on the results for such large-scale high-energy release problems with signi

关键词： Large-scale explosion Shock wave Adaptive method Fluid field simulations Efficient method

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Four directional circular optical phased array for uniform two-dimensional beam steering at visible wavelength

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Optics Express 2025年第7期33卷 15954-15963页

作者： Zhang, Qianhan Lian, Daixin Xu, Zixu Zhao, Shi Chen, Jingye Dai, Daoxin Shi, Yaocheng State Key Laboratory for Extreme Photonics and Instrumentation Center for Optical and Electromagnetic Research International Research Center for Advanced Photonics College of Optical Science and Engineering Zhejiang University Hangzhou310058 China

Optical phased arrays (OPAs), owing to their remarkable capacity for rapid and precise beam steering, have emerged as a pivotal technology in various applications such as augmented reality, free-space optical communication, and optical imaging. In this paper, we present a 64-element two-dimensional (2D) circular OPA operating at a visible wavelength of 632.5 nm. To the best of our knowledge, this is the first time that 2D continuous beam steering with pure phase control has been realized at the visible wavelengths. We propose arrowhead antennas to reduce residual energy while maintaining the integrity of the far-field pattern. Furthermore, a four-directional array arrangement has been introduced to expand the field of view and enhance the uniformity of the side lobe suppression ratio (SLSR) at different azimuth angles. The measurement for the fabricated OPA shows 2D beam steering with an elevation angle of 9° and an azimuth angle of 360° with an SLSR of over 3 dB. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Antenna phased arrays

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Comparative Stability Study of Grid-Following and Grid-Forming Converters in Current Control Timescale 5

Comparative Stability Study of Grid-Following and Grid-Formi...

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5th International Conference on Electrical engineering and Control Technologies, CEECT 2023

作者： Zhou, Yunpeng He, Wei Hu, Jiabing Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan China

ISBN: (纸本)9798350342253

Oscillations in current control (CC) timescale caused by the large-scale integration of voltage-source converters (VSCs) have gained more and more attention from both academy and industry. In view of this problem, a comparative study is conducted to investigate the stability difference between gridfollowing (GFL) and grid-forming (GFM) converters in CC timescale. Firstly, the unified linearized model of GFL and GFM converters is established. Secondly, the impact paths of other control loops on the current control loop are extracted based on the proposed model. Thirdly, the characteristics of the corresponding paths in GFL and GFM converter are studied. By comparing the impact of the corresponding paths on the current control loop, the root cause of the stability difference between GFL and GFM in CC timescale is revealed. All results are verified through time-domain simulations. © 2023 IEEE.

关键词： Stability

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engineering Thermoelectric Performance of α-GeTe by Ferroelectric Distortion

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Energy & Environmental Materials 2024年第2期7卷 171-179页

作者： Yuting Fan Chenghao Xie Jun Li Xiangyu Meng Jinchang Sun Jinsong Wu Xinfeng Tang Gangjian Tan State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China International School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

The rhombohedralα-GeTe can be approximated as a slightly distorted rock-salt structure along its[111]direction and possesses superb thermoelectric ***,the role of such a ferroelectric-like structural distortion on its transport properties remains ***,we performed a systematic study on the crystal structure and electronic band structure evolutions of Ge_(1-x)Sn_(x)Te alloys where the degree of ferroelectric distortion is continuously *** is revealed that the band gap is maximized while multiple valence bands are converged at x=0.6,where the ferroelectric distortion is the least but still *** undistorted,the band gap is considerably reduced,and the valence bands are largely separated ***,near the ferro-to-paraelectric phase transition Curie temperature,the lattice thermal conductivity reaches its minima because of significant lattice softening enabled by ferroelectric *** predict a peak ZT value of 2.6 at 673 K inα-GeTe by use of proper dopants which are powerful in suppressing the excess hole concentrations but meanwhile exert little influence on the ferroelectric distortion.

关键词： electronic band structures ferroelectric distortion lattice softening thermoelectric α-GeTe

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Research on an Optimal Design of DSOGI-PLL Based on Complex Power Grid 2

Research on an Optimal Design of DSOGI-PLL Based on Complex ...

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2nd Power Electronics and Power System Conference, PEPSC 2024

作者： Ye, Zhengyang Dai, Yufeng Cao, Tiantian Xu, Jiaxin Wu, Qiong Li, Dayi State Key Laboratory of Advance Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9798350390193

The complexity of modern power systems, attributed to electronic integration and nonlinear loads, intensifies harmonic pollution and power quality problems. Effective management necessitates real-time detection of the grid phase and frequency utilizing PLLs. The dual second-order generalized integrator phase-locked loop (DSOGI-PLL), renowned for its minimal overshoot and delay, lacks adequate filtering capacity in complex grids and is sensitive to DC components. This paper optimizes the SOGI within the traditional DSOGI-PLL, enhancing its resistance to high and low frequency interference. Additionally, a Double Cascade Optimized Sliding Average Filter (DCO-MAF) based on the Moving Average Filter (MAF) is introduced to eliminate grid harmonics with minimal delay, enabling swift and accurate PLL synchronization. Simulation results employing MATLAB/Simulink demonstrate that the optimized design significantly outperforms the traditional DSOGI-PLL in conditions with DC offsets or harmonics, showcasing its robustness and effectiveness. © 2024 IEEE.

关键词： Phase locked loops

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Peak-like three-dimensional CoFe_(2)O_(4)/carbon nanotube decorated bamboo fabrics for simultaneous solar-thermal evaporation of water and photocatalytic degradation of bisphenol A

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Journal of Materials Science & technology 2024年第12期179卷 40-49页

作者： Rui-Jie Pan Jing Wu Jin Qu Tingting Zhang Fan-Zhen Jiao Mang Zhao Meng-Yan Han Xiaofeng Li Zhong-Zhen Yu State Key Laboratory of Organic-Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing 100029China

Catalytic CoFe_(2)O_(4) and solar-thermal carbon nanotube decorated bamboo fabrics(CCBF)are fabricated for integrating efficient solar steam generation from wastewater with catalytic degradation of its organic *** to the numerous porous channels and polar groups of bamboo fabric and the efficient solar-thermal energy conversion of black carbon nanotubes,the porous and hydrophilic CCBF exhibits fast upward transport of water,efficient solar light absorption,and high solar-thermal energy conversion *** decorated CoFe_(2)O_(4) not only enhances the solar-thermal energy conversion efficiency of CCBF but also activates potassium peroxymonosulfate to generate abundant highly active species for catalytic degradation of bisphenol A(BPA).Furthermore,folding the CCBF into a peak-like 3D evaporator can en-hance solar energy utilization,and gain environmental energy for promoting solar-thermal water evapo-ration and catalytic degradation *** 3D CCBF evaporator achieves a water evaporation rate of 2.72 kg m^(-2) h^(-1) under 1-sun ***,100%of the BPA in the seawater can be degraded within 10 *** exceptional high purification efficiency of 27.72 kg m^(-2) h^(-1) is achieved with the 3D evaporator during a long-term treatment of BPA-containing seawater under 1-sun *** work demonstrates efficient purification of seawater/wastewater with both metal ions and organic pollutants by simultaneous solar-thermal evaporation of water and catalytic degradation of organic pollutants.

关键词： Solar-thermal water evaporation Seawater desalination Catalytic degradation Carbon nanotubes CoFe_(2)O_(4)

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Nonlinear Multiscale Modeling of Multi-Machine Power Systems Integrated with Photovoltaics

Nonlinear Multiscale Modeling of Multi-Machine Power Systems...

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2023 IEEE PELS Students and Young Professionals Symposium, SYPS 2023

作者： Wu, Jiaqi Han, Miao Zhan, Meng Huazhong University of Science and Technology School of Electrical and Electronic Engineering State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan China

ISBN: (纸本)9798350307832

Large-scale photovoltaics (PVs) connected to the power grid through power electronic equipment have greatly changed the dynamics of the traditional power systems dominated by synchronous generators (SGs), bringing significant challenges to modeling and analysis of modern power systems. In this paper, a nonlinear model of multi-machine power systems integrated with PVs is established to reveal the multi-timescale transient synchronization characteristics using the singular perturbation technique. The fast subsystem containing the dynamics of the DC voltage control, terminal voltage control, and phase-locked loop, and the slow subsystem containing the dynamics of the rotor swing can effectively reflect the dynamics of multi-machine power systems integrated with PVs within the electromagnetic and electromechanical timescales, respectively. The proposed model provides a clearer physical picture of dynamics in the multi-machine power systems integrated with PVs within the electromagnetic and electromechanical timescales, and serves as the foundational model for further stability analysis. Finally, simulation results verify the validity of the proposed model. © 2023 IEEE.

关键词： Dynamics

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Local chemical ordering and its impact on radiation damage behavior of multi-principal element alloys

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Journal of Materials Science & technology 2023年第4期135卷 13-25页

作者： Leqing Liu Xiongjun Liu Qing Du Hui Wang Yuan Wu Suihe Jiang Zhaoping Lu Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China

Multi-principal element alloys(MPEAs)have attracted much attention as future nuclear materials due to their extraordinary radiation *** this work,we have elucidated the development of local chemical orderings(LCOs)and their influences on radiation damage behavior in the typical CrFeNi MPEA by hybrid-molecular dynamics and Monte Carlo *** was found that considerable LCOs consist-ing of the Cr-Cr and Ni-Fe short-range orders existed in the ordered configuration with optimized system *** modeling the accumulation cascades up to 1000 recoils,we revealed that the size of de-fect clusters and dislocation loops is smaller in the ordered configuration than those in the random one,although the former formed more Frenkel pairs(i.e.,self-interstitials and vacancies).In addition,the dis-tribution of dislocation loops is relatively more dispersed in the ordered configuration,and the stair-rod dislocations related to irradiation swelling are also smaller,implying that the existence of LCOs is con-ducive to enhancing radiation damage *** understand the underlying mechanism,the effects of LCOs on the formation and evolution of defects and radiation resistance were discussed from the aspects of atomic bonding,migration path,and energy of defect diffusion,which provides theoretical guidance for the design of MPEAs with enhanced radiation resistance.

关键词： Multi-principal element alloys Local chemical ordering Radiation damage Dislocation evolution Molecular dynamics simulation

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A Novel Variable Impedance Design Concept of PM Fault Tolerant Machine 26

A Novel Variable Impedance Design Concept of PM Fault Tolera...

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26th International Conference on Electrical Machines and Systems, ICEMS 2023

作者： Wang, Runyu Li, Dawei Fan, Xinggang Qu, Ronghai Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan China

ISBN: (纸本)9798350317589

A novel variable impedance fault tolerant design concept is proposed in this paper for high reliable PM machines. The special fault tolerant ring structure realizes the automatic transformation of the machine from low impedance in healthy operation to ultra-high impedance in fault operation, which effectively suppresses the short-circuit current. First, the design guidelines for fault tolerant ring and the fault tolerance mechanism of variable impedance are introduced. Subsequently, two variable impedance machine topologies with separated and integrated fault tolerant rings are investigated. Finally, the prototypes are fabricated and the experimental results show that the proposed variable impedance topology has a turn-to-turn short-circuit current suppression capability that far exceeds that of the conventional fault tolerant topology. © 2023 IEEE.

关键词： Topology

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General Description of Solid Armatures in electromagnetic Railguns 10

General Description of Solid Armatures in Electromagnetic Ra...

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10th Euro-Asian Pulsed Power Conference, 25th International Conference on High-Power Particle Beams and 20th International Symposium on electromagnetic Launch technology, EAPPC-BEAMS-EML 2024

作者： Chen, Lixue Zhang, Wenhao Li, Lidong Xu, Shengqin State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and Technology Key Laboratory of Pulsed Power Technology Ministry of Education School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9789038661353

Armature, as an important part of the electromagnetic launch system, is a current carrier which converts electric energy into kinetic energy of projectiles, and it often suffers extreme environment in the launch process. Therefore, the performance of launch system is directly affected by the armature whose structure is the fundamental of the application of launch technology. Among various armature types, solid armatures are the most widely used because of some characteristics of them, like high efficiency and low mass. Based on some key functions of solid armatures, three kinds of requirements including current-carrying capacity, mechanical pressure and electromagnetic contact pressure are proposed in this paper. Besides, research progress of material and structure of the solid armature and its optimization is also introduced in this paper. © 2024 Eindhoven University of technology.

关键词： Kinetic energy

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