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Constitutive model of viscoelastic dynamic damage for the material of gas obturator in modular-charge howitzer

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DEFENCE TECHNOLOGY 2024年第9期39卷 203-216页

作者： li, Zhonggang Chen, Longmiao li, yifan Jia, Yufeng Zhang, Quan Nanjing Univ Sci & Technol Sch Mech Engn Nanjing 210094 Peoples R China Shanxi North Machine Bldg Co Ltd Technol Ctr Taiyuan 030009 Peoples R China Kelong New Mat Technol Co Ltd Res & Dev Dept Xianyang 712000 Peoples R China

In order to investigate the mechanical response behavior of the gas obturator of the breech mechanism, made of polychloroprene rubber (PCR), uniaxial compression experiments were carried out by using a universal testing machine and a split Hopkinson pressure bar (SHPB), obtaining stress-strain responses at different temperatures and strain rates. The results revealed that, in comparison to other polymers, the gas obturator material exhibited inconspicuous strain softening and hardening effects; meanwhile, the mechanical response was more affected by the strain rate than by temperature. Subsequently, a succinct viscoelastic damage constitutive model was developed based on the ZWT model, including ten undetermined parameters, formulated with incorporating three parallel components to capture the viscoelastic response at high strain rate and further enhanced by integrating a three-parameter Weibull function to describe the damage. Compared to the ZWT model, the modified model could effectively describe the mechanical response behavior of the gas obturator material at high strain rates. This research laid a theoretical foundation for further investigation into the influence of chamber sealing issues on artillery firing. (c) 2024 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Breech mechanism Gas obturator Polychloroprene rubber Constitutive model Strain rate Damage STRAIN RATES WIDE-RANGE POLYMERS BEHAVIOR PRESSURE

A Fast Startup Crystal Oscillator with Digital SAR-AFC Based Two-Step Injection

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Chinese Journal of Electronics 2024年第5期33卷 1147-1153页

作者： Bo ZHOU yifan li Zuhang WANG School of Integrated Circuits and Electronics Beijing Institute of Technology

Crystal oscillators（XOs） provide a high-precision reference frequency but have a long startup time,which severely increases the average power consumption in duty-cycled *** paper proposes a fully-digital low-cost two-step injection technique,by using a successive approximation register（SAR） based auto frequency control（AFC） loop,to speed up the startup behavior of XOs.A theoretical analysis is carried out to determine the optimum injection time and design low-power *** in a 65 nm CMOS process,the proposed 12 MHz fast startup XO occupies an active area of 0.02 mm2and achieves a startup time less than 35 μ*** XO power consumption in the steady state is 40 μW from a 1.0-V supply,with a startup energy of 17.2 nJ.

关键词： Time-frequency analysis Power demand Power measurement Crystals Time measurement Steady-state Registers Crystal oscillator Two-step injection Successive approximation register Auto frequency control Fully-digital Fast startup ENERGY

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Automated identification of steel weld defects,a convolutional neural network improved machine learning approach

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Frontiers of Structural and Civil Engineering 2024年第2期18卷 294-308页

作者： Zhan SHU Ao WU Yuning SI Hanlin DONG Dejiang WANG yifan li School of Mechanics and Engineering Science Shanghai UniversityShanghai 200444China School of Civil Engineering Shanghai Normal UniversityShanghai 201418China Shanghai PinlanData Technology Co. Ltd.Shanghai 200072China

This paper proposes a machine-learning-based methodology to automatically classify different types of steel weld defects,including lack of the fusion,porosity,slag inclusion,and the qualified(no defects)*** methodology solves the shortcomings of existing detection methods,such as expensive equipment,complicated operation and inability to detect internal *** study first collected percussed data from welded steel members with or without weld ***,three methods,the Mel frequency cepstral coefficients,short-time Fourier transform(STFT),and continuous wavelet transform were implemented and compared to explore the most appropriate features for classification of weld *** and convolutional neural network-enhanced algorithms were used to classify,the extracted ***,experiments were designed and performed to validate the proposed *** showed that STFT achieved higher accuracies(up to 96.63%on average)in the weld status *** convolutional neural network-enhanced support vector machine(SVM)outperformed six other algorithms with an average accuracy of 95.8%.In addition,random forest and SVM were efficient approaches with a balanced trade-off between the accuracies and the computational efforts.

关键词： steel weld machine learning convolutional neural network weld defect detection classification task percussion

Style-conditioned music generation with Transformer-GANs

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Frontiers of Information Technology & Electronic Engineering 2024年第1期25卷 106-120页

作者： Weining WANG Jiahui li yifan li Xiaofen XING School of Electronic and Information Engineering South China University of TechnologyGuangzhou 510600China

Recently,various algorithms have been developed for generating appealing ***,the style control in the generation process has been somewhat *** style refers to the representative and unique appearance presented by a musical work,and it is one of the most salient qualities of *** this paper,we propose an innovative music generation algorithm capable of creating a complete musical composition from scratch based on a specified target style.A style-conditioned linear Transformer and a style-conditioned patch discriminator are introduced in the *** style-conditioned linear Transformer models musical instrument digital interface(MIDI)event sequences and emphasizes the role of style ***,the style-conditioned patch discriminator applies an adversarial learning mechanism with two innovative loss functions to enhance the modeling of music ***,we establish a discriminative metric for the first time,enabling the evaluation of the generated music’s consistency concerning music *** objective and subjective evaluations of our experimental results indicate that our method’s performance with regard to music production is better than the performances encountered in the case of music production with the use of state-of-the-art methods in available public datasets.

关键词： Music generation Style-conditioned Transformer Music emotion

In-doping collaboratively controlling back interface and bulk defects to achieve efficient flexible CZTSSe solar cells

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Journal of Energy Chemistry 2024年第2期89卷 10-17,I0002页

作者： Quanzhen Sun yifan li Caixia Zhang Shunli Du Weihao Xie Jionghua Wu Qiao Zheng Hui Deng Shuying Cheng Institute of Micro-Nano Devices and Solar Cells College of Physics and Information EngineeringFuzhou UniversityFuzhou 350108FujianChina Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108FujianChina Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering Changzhou 213164JiangsuChina

Focusing on the low open circuit voltage(V_(OC))and fill factor(FF)in flexible Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells,indium(In)ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible *** results show that In doping effectively inhibits the formation of secondary phase(Cu(S,Se)_(2))and *** studies demonstrate that the barrier height at the back interface is decreased and the deep level defects(Cu_(Sn)defects)in CZTSSe bulk are ***,the carrier concentration is increased and the V_(OC) deficit(V_(OC,def))is decreased significantly due to In ***,the flexible CZTSSe solar cell with 10.01%power conversion efficiency(PCE)has been *** synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.

关键词： Flexible solar cells Cu_(2)ZnSn(S,Se)_(4) Back interface Deep level defects Barrier height

Rapid Phase Ambiguity Elimination Methods for DOA Estimator via Hybrid Massive MIMO Receive Array

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Chinese Journal of Electronics 2024年第1期33卷 175-184页

作者： Xichao ZHAN Zhongwen SUN Feng SHU Yiwen CHEN Xin CHENG Yuanyuan WU Qi ZHANG yifan li Peng ZHANG School of Information and Communication Engineering Hainan University School of Electronic and Optical Engineering Nanjing University of Science and Technology

For a sub-connected hybrid multiple-input multiple-output(MIMO) receiver with K subarrays and N antennas, there exists a challenging problem of how to rapidly remove phase ambiguity in only single time-slot. A direction of arrival(DOA) estimator of maximizing received power(Max-RP) is proposed to find the maximum value of K-subarray output powers, where each subarray is in charge of one sector, and the center angle of the sector corresponding to the maximum output is the estimated true DOA. To make an enhancement on precision, Max-RP plus quadratic interpolation(Max-RP-QI) method is designed. In the proposed Max-RP-QI, a quadratic interpolation scheme is adopted to interpolate the three DOA values corresponding to the largest three receive powers of *** achieve the Cramer Rao lower bound, a Root-MUSIC plus Max-RP-QI scheme is developed. Simulation results show that the proposed three methods eliminate the phase ambiguity during one time-slot and also show low computational complexities. The proposed Root-MUSIC plus Max-RP-QI scheme can reach the Cramer Rao lower bound,and the proposed Max-RP and Max-RP-QI are still some performance losses 2–4 d B compared to the Cramer Rao lower bound.

关键词： Phased arrays Interpolation Wireless sensor networks Direction-of-arrival estimation Simulation Receiving antennas Massive MIMO

Exploring the role of iron in Fe_(5)Ni_(4)S_(8)toward oxygen evolution through modulation of electronic orbital occupancy

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Journal of Energy Chemistry 2024年第5期92卷 52-62页

作者： Zhengyan Du Zeshuo Meng Haoteng Sun yifan li Chao Jiang Yaxin li Xiaoying Hu Yi Cui Shansheng Yu Hongwei Tian Key Laboratory of Automobile Materials of MOE School of Materials Science and EngineeringJilin UniversityChangchun 130012JilinChina College of Science and Laboratory of Materials Design and Quantum Simulation Changchun UniversityChangchun 130022JilinChina i-lab Vacuum Interconnected Nanotech Workstation(Nano-X)Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123JiangsuChina Department of Chemistry Brown UniversityRI 02912United States

Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial ***,Fe leaching occurs during the reaction due to thermodynamic instability,which has resulted in conflicting reports within the literature regarding its *** clarify this point,we propose a strategy consisting of modulating the electronic orbital occupancy to suppress the extensive loss of Fe atoms during the OER *** calculations,in-situ X-ray photoelectron spectroscopy,molecular dynamics simulations,and a series of characterization showed that the stable presence of Fe not only accelerates the electron transfer process but also optimizes the reaction barriers of the oxygen evolution intermediates,promoting the phase transition of Fe_(5)Ni_(4)S_(8)to highly active catalytic *** modulated Fe_(5)Ni_(4)S_(8)-based pre-catalysts exhibit improved OER activity and long-term *** study provides a novel perspective for understanding the role of Fe in the OER process.

关键词： Oxygenevolution Fe_(5)Ni_(4)S_(8) Electronic orbital occupancy modulation Reconstruction dynamics

Constitutive model of viscoelastic dynamic damage for the material of gas obturator in modular-charge howitzer

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Defence Technology 2024年第09期 203-216页

作者： Zhonggang li Longmiao Chen yifan li Yufeng Jia Quan Zhang School of Mechanical Engineering Nanjing University of Science and Technology Technology Center Shanxi North Machine-building Co. Ltd. Research and Development Department Kelong New Material Technology Co. Ltd.

In order to investigate the mechanical response behavior of the gas obturator of the breech mechanism,made of polychloroprene rubber(PCR), uniaxial compression experiments were carried out by using a universal testing machine and a split Hopkinson pressure bar(SHPB), obtaining stress-strain responses at different temperatures and strain rates. The results revealed that, in comparison to other polymers, the gas obturator material exhibited inconspicuous strain softening and hardening effects; meanwhile, the mechanical response was more affected by the strain rate than by temperature. Subsequently, a succinct viscoelastic damage constitutive model was developed based on the ZWT model, including ten undetermined parameters, formulated with incorporating three parallel components to capture the viscoelastic response at high strain rate and further enhanced by integrating a three-parameter Weibull function to describe the damage. Compared to the ZWT model, the modified model could effectively describe the mechanical response behavior of the gas obturator material at high strain rates. This research laid a theoretical foundation for further investigation into the influence of chamber sealing issues on artillery firing.

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The Roadmap of 2D Materials and Devices Toward Chips

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Nano-Micro Letters 2024年第6期16卷 343-438页

作者： Anhan liu Xiaowei Zhang Ziyu liu Yuning li Xueyang Peng Xin li Yue Qin Chen Hu Yanqing Qiu Han Jiang Yang Wang yifan li Jun Tang Jun liu Hao Guo Tao Deng Songang Peng He Tian Tian‑ling Ren School of Integrated Circuits and Beijing National Research Center for Information Science and Technology(BNRist) Tsinghua UniversityBeijing 100049People’s Republic of China School of Microelectronics Fudan UniversityShanghai 200433People’s Republic of China State Key Laboratory of Dynamic Measurement Technology Shanxi Province Key Laboratory of Quantum Sensing and Precision MeasurementNorth University of ChinaTaiyuan 030051People’s Republic of China High‑Frequency High‑Voltage Device and Integrated Circuits R&D Center Institute of MicroelectronicsChinese Academy of SciencesBeijing 100029People’s Republic of China School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044People’s Republic of China School of Integrated Circuits University of Chinese Academy of SciencesBeijing 100049People’s Republic of China IMECAS-HKUST-Joint Laboratory of Microelectronics Beijing 100029People’s Republic of China

Due to the constraints imposed by physical effects and performance degra certain limitations in sustaining the advancement of Moore’s ***-dimensional(2D)materials have emerged as highly promising candidates for the post-Moore era,offering significant potential in domains such as integrated circuits and next-generation ***,in this review,the progress of 2D semiconductors in process engineering and various electronic applications are summarized.A careful introduction of material synthesis,transistor engineering focused on device configuration,dielectric engineering,contact engineering,and material integration are given *** 2D transistors for certain electronic applications including digital and analog circuits,heterogeneous integration chips,and sensing circuits are ***,several promising applications(artificial intelligence chips and quantum chips)based on specific mechanism devices are ***,the challenges for 2D materials encountered in achieving circuit-level or system-level applications are analyzed,and potential development pathways or roadmaps are further speculated and outlooked.

关键词： Two-dimensional materials Roadmap Integrated circuits Post-Moore era