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Effect of Room Temperature Ultrasonic Vibration Compression on the Microstructure Evolution and Mechanical Properties of AZ91 Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第7期37卷 1135-1146页

作者： Ziyue Xu Huan Liu Luyao Li Chao Sun Xi Tan Baishan Chen Qiangsheng Dong Yuna Wu Jinghua Jiang Jiang Ma College of Materials Science and Engineering Hohai UniversityNanjing210000China Suzhou Research Institute of Hohai University Suzhou215000China Shenzhen Key laboratory of High Performance Nontraditional Manufacturing College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen518060China Institute of Medical Devices(Suzhou) Southeast UniversitySuzhou215163China Institute for advanced Study Central South UniversityChangsha410083China Jiangsu Key laboratory of advanced Structural Materials and application technology Nanjing Institute of TechnologyNanjing211167China

To investigate the potential of direct ultrasonic vibration on improving the performance of magnesium alloys,this study first employed the ultrasonic vibration compression(UVC)on the solid solution treated AZ91 alloy,and explored its microstructure evolution and mechanical properties under *** only two seconds,the UVC alloys showed large deformation strains of 34.8–54.4%,and sudden increase of sample temperature to 243℃.Microstructure characterizations proved that UVC promoted the formation of abundant shear bands,fine grains,and the bimodal distribution of Mg17Al12 precipitates consisting of submicron particles located within the shear bands and nano-sized ones within the *** to the unique microstructure,the micro-hardness(and nano-hardness)value of UVC alloy was increased by 37.7%(35%)when compared with the solution-treated ***,the nano-modulus of the developed AZ91 alloy was also significantly increased to 62 GPa by statistical nanoindentation tests,which could be ascribed to increased Mg_(17)Al_(12) precipitates and decreased c/a value to some *** general,this work provides a new insight into the design and preparation of high-performance magnesium alloys by UVC at room temperature.

关键词： AZ91 alloys Ultrasonic vibration compression Precipitation Shear bands Mechanical properties

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1.6-μm single-frequency erbium-doped fiber laser based on two cascaded subrings

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Chinese Optics Letters 2024年第4期22卷 77-82页

作者：翟雅琦文瀚陈浩伟陆宝乐白晋涛 State Key laboratory of Energy Photon-technology in Western China International Collaborative Center on Photoelectric Technology and Nano Functional MaterialsInstitute of Photonics&Photon-TechnologyNorthwest UniversityXi’an 710127China Shaanxi Engineering technology Research Center for Solid State Lasers and application Shaanxi Provincial Key Laboratory of Photo-electronic TechnologyNorthwest UniversityXi’an 710127China

We demonstrate a stable narrow linewidth single-frequency erbium-doped fiber laser(EDFL)operating at 1.6μm.A Fabry–Perot fiber Bragg grating and two cascaded subrings are incorporated in the main ring cavity to achieve singlefrequency *** experimentally measured optical signal-to-noise ratio is greater than 73 ***,the linewidth of the EDFL is measured to be about 480 Hz by the self-built short-delayed self-heterodyne interferometry *** laser shows superior stability,with no mode-hopping during the 60-min observation *** proposed EDFL provides a new experimental idea for realizing a single-frequency fiber laser in the L-band.

关键词： erbium-doped fiber laser two cascaded subrings single frequency

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Industry-Oriented Detection Method of PCBA Defects Using Semantic Segmentation Models

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1438-1446页

作者： Yang Li Xiao Wang Zhifan He Ze Wang Ke Cheng Sanchuan Ding Yijing Fan Xiaotao Li Yawen Niu Shanpeng Xiao Zhenqi Hao Bin Gao Huaqiang Wu Department of Internet of Things technology and application China Mobile Research InstituteBeijing 100053China Beijing advanced Innovation Center for Integrated Circuits the School of Integrated CircuitTsinghua UniversityBeijing 100084China SigmaStar technology Limited Xiamen 361199China IEEE

Automated optical inspection(AOI)is a significant process in printed circuit board assembly(PCBA)production lines which aims to detect tiny defects in *** AOI equipment has several deficiencies including low throughput,large computation cost,high latency,and poor flexibility,which limits the efficiency of online PCBA *** this paper,a novel PCBA defect detection method based on a lightweight deep convolution neural network is *** this method,the semantic segmentation model is combined with a rule-based defect recognition algorithm to build up a defect detection *** improve the performance of the model,extensive real PCBA images are collected from production lines as *** optimization methods have been applied in the model according to production demand and enable integration in lightweight computing *** results show that the production line using our method realizes a throughput more than three times higher than traditional *** method can be integrated into a lightweight inference system and pro-mote the flexibility of *** proposed method builds up a general paradigm and excellent example for model design and optimization oriented towards industrial requirements.

关键词： Automated optical inspection(AOI) deep learning defect detection printed circuit board assembly(PCBA) semantic segmentation.

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The mechanisms of enhanced thickness-dependent DC breakdown strength of EP/MWCNTs nanocomposites

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High Voltage 2024年第2期9卷 440-452页

作者： Zhen Li He Gao Longfei Zhang Shouming Wang Ji Liu Shengtao Li Key laboratory of Engineering Dielectrics and Its application Ministry of EducationHarbin University of Science and TechnologyHarbinChina State Key laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

Owing to advanced power electronic and electrical applications developing towards miniaturisation and integration,the thickness-dependent DC breakdown mechanism of epoxy/multiwall-carbon-nanotube nanocomposites is under *** results indicate that the breakdown strength of nanocomposites containing 0.05 wt%multiwall-carbon-nanotubes rises by~18%,and the breakdown strength falls exponentially with increasing *** clarify the microscopic mechanism,a simulation model of DC breakdown,including carriers transport and segmental dynamics,is developed,and the accordant simulation results with experimental results indicate that the thickness-dependent DC breakdown of epoxy/multiwall-carbon-nanotube nanocomposites is determined both by segment chain dynamics and charge *** to the breakdown model analysis,the effects of multiwall-carbon-nanotube on enhanced breakdown strength are caused by the increased amount of deep traps in the interfacial region,while the influence of thickness is attributed to the enlarged segment chain displacement and electric field distortion as the voltage raising time increases.

关键词： strength breakdown nanocomposites

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Identification and functional analysis of CG3526 in spermatogenesis of Drosophila melanogaster

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Insect Science 2024年第1期31卷 79-90页

作者： Qihao Hu Yanhong Xiao Runnan Wei Ting Tang Liang Wen Yuzhen Lu Xiao-Qiang Yu Guangdong Provincial Key laboratory of Insect Developmental Biology and Applied technology Guangzhou Key Laboratory of Insect Development Regulation and Application ResearchInstitute of Insect Science and TechnologySchool of Life SciencesSouth China Normal UniversityGuangzhou510631 China

Spermatogenesis is a critical part of reproduction in insects;however,its molecular mechanism is still largely *** this study,we identified a testis-specific gene CG3526 in Drosophila *** analysis showed that CG3526 contains a zinc binding domain and 2 C2H2 type zinc fingers,and it is clustered to the vertebrate really interesting new gene(RING)family E3 ubiquitin-protein *** CG3526 was knocked down by RNA interference(RNAi),the testis became much smaller in size,and the apical tip exhibited a sharp and thin end instead of the blunt and round shape in the control *** importantly,compared to the control flies,only a few mature sperm were present in the seminal vesicle of C587-Gal4>CG3526 RNAi *** staining of the testis from CG3526 RNAi flies showed that the homeostasis of testis stem cell niche was disrupted,cell distribution in the apical tip was scattered,and the process of spermatogenesis was not ***,we found that the phenotype of CG3526 RNAi flies’testis was similar to that of testis of Stat92E RNAi flies,the expression level of CG3526 was significantly downregulated in the Stat92EF06346 mutant flies,and the promoter activity of CG3526 was upregulated by *** together,our results indicated that CG3526 is a downstream effector gene in the JAK-STAT signaling pathway that plays a key role in the spermatogenesis of Drosophila.

关键词： CG3526 JAK-STAT spermatogenesis STAT92E testis

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Spectrum analysis of interval process model and its application in uncertain vibration analysis

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Science China Technological Sciences 2024年第8期67卷 2549-2564页

作者： LI JinWu JIANG Chao NI BingYu State Key laboratory of advanced Design and Manufacturing technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University

In recent years, the authors have extended the traditional interval method into the time dimension to develop a new mathematical tool called the “interval process model” for quantifying time-varying or dynamic uncertainties. This model employs upper and lower bounds instead of precise probability distributions to quantify uncertainty in a parameter at any given time point. It is anticipated to complement the conventional stochastic process model in the coming years owing to its relatively low dependence on experimental samples and ease of understanding for engineers. Building on our previous work, this paper proposes a spectrum analysis method to describe the frequency domain characteristics of an interval process, further strengthening the theoretical foundation of the interval process model and enhancing its applicability for complex engineering problems. In this approach, we first define the zero midpoint function interval process and its auto/cross-power spectral density(PSD) functions. We also deduce the relationship between the auto-PSD function and the auto-covariance function of the stationary zero midpoint function interval process. Next, the auto/cross-PSD function matrices of a general interval process are defined, followed by the introduction of the concepts of PSD function matrix and cross-PSD function matrix for interval process vectors. The spectrum analysis method is then applied to random vibration problems, leading to the creation of a spectrum-analysis-based interval vibration analysis method that determines the PSD function for the system displacement response under stationary interval process excitations. Finally, the effectiveness of the formulated spectrum-analysis-based interval vibration analysis approach is verified through two numerical examples.

关键词： interval process spectrum analysis power spectral density (PSD) time-varying uncertainty uncertain vibration analysis

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Conjugate Vectors Method Applied to Asymmetrical Fault Analysis of Power Electronized Power Systems

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1536-1549页

作者： Yingbiao Li Xing Liu Jiabing Hu Jianhang Zhu Jianbo Guo State Key laboratory of advanced Electromagnetic technology(Huazhong University of Science and technology) Wuhan 430074China China Electric Power Research Institute Beijing 100192China

With the wide application of power electronized resources(PERs),the amplitude and frequency of voltages show significant time-varying characteristics under asymmetrical *** a result,the traditional phasor model,impedance model,and symmetrical components method based on the constant amplitude and frequency of voltages are facing great ***,a novel asymmetrical fault analysis method based on conjugate vectors is proposed in this paper which can meet the modeling and analysis requirements of the network excited by voltages with time-varying amplitude/***,asymmetrical fault characteristics are *** an application,a faulted phase identification(FPI)strategy is proposed based on the fault *** correctness and superiority of the asymmetrical fault analysis method and FPI strategy are verified in time-domain simulations and a real-time digital simulator.

关键词： Asymmetrical fault characteristics conjugate vectors method dynamic asymmetrical fault analysis time-varying amplitude/frequency

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Low palladium content CeO_(2)/ZnO composite for acetone sensor with sub-second response prepared by ultrasonic method

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Journal of Central South University 2024年第7期31卷 2137-2149页

作者： CHEN Xu-jie XING Qiao-ling TANG Xuan CAI Yong ZHANG Ming Hunan Provincial Key laboratory of Low-dimensional Structural Physics&Devices School of Physics and ElectronicsHunan UniversityChangsha 410082China Changsha Semiconductor technology and application Innovation Research Institute College of Semiconductors(College of Integrated Circuits)Hunan UniversityChangsha 410082China School of Mechanical Engineering and Mechanics Xiangtan UniversityXiangtan 411105China Research Institute of Hunan University in Chongqing Chongqing 401120China Engineering Research Center of advanced Semiconductor technology and application of Ministry of Education&Key laboratory for Micro-/Nano-Optoelectronic Devices of Ministry of Education National Key Laboratory of Power Semiconductor and Integration TechnologyCollege of Semiconductors(College of Integrated Circuits)Hunan UniversityChangsha 410082China

In practical applications,noble metal doping is often used to prepare high performance gas sensors,but more noble metal doping will lead to higher preparation *** this study,CeO_(2)/ZnO-Pd with low palladium content was prepared by ultrasonic method with fast response and high selectivity for acetone *** the same amount of palladium added,the selectivity coefficient of CeO_(2)/ZnO-Pd is 1.88 times higher than that of the stirred *** with the pure PdO-doped CeO_(2)/ZnO-PdO material,the content of Pd in CeO_(2)/ZnO-PdO is about 30%of that in CeO_(2)/ZnO-PdO,but the selectivity coefficient for acetone is 2.56 times *** CeO_(2)/ZnO-Pd sensor has a higher response(22.54)to 50×10^(−6) acetone at 300℃and the selectivity coefficient is 2.57 times that of the CeO_(2)/ZnO *** sensor has a sub-second response time(0.6 s)and still has a 2.36 response to 330×10^(−9) of *** doping makes Pd particles smaller and increases the contact area with ***,the composition of n-p-n heterojunction and the synergistic effect of Pd/PdO improve the sensor *** shows that ultrasonic Pd doping provides a way to improve the utilization rate of doped metals and prepare highly selective gas sensors.

关键词： low palladium sub-second responce ultrasonic method acetone sensor heterojunction

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A Review on the Security of the Ethereum-Based DeFi Ecosystem

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 69-101页

作者： Yue Xue Dunqiu Fan Shen Su Jialu Fu Ning Hu Wenmao Liu Zhihong Tian Cyberspace Institute of advanced technology Guangzhou UniversityGuanzhou510000China Innovation Center NSFOCUS Inc.Beijing100089China Engineering Research Center of Integration and application of Digital Learning technology Ministry of EducationBeijing100816China

Decentralized finance(DeFi)is a general term for a series of financial products and *** is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary *** them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most ***,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few ***,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security *** that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project *** on that,we further discuss the current solutions and potential directions ofDeFi *** to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.

关键词： Blockchain smart contract decentralized finance DeFi security

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Construction of Cu-Zn Co-doped layered materials for sodium-ion batteries with high cycle stability

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Chinese Chemical Letters 2024年第5期35卷 441-446页

作者： Xiping Dong Xuan Wang Zhixiu Lu Qinhao Shi Zhengyi Yang Xuan Yu Wuliang Feng Xingli Zou Yang Liu Yufeng Zhao Institute for Sustainable Energy&College of Sciences Shanghai UniversityShanghai 200444China Key laboratory for advanced technology in Environmental Protection of Jiangsu Province Yancheng Institute of TechnologyYancheng 224051China State Key laboratory of advanced Special Steel&Shanghai Key laboratory of advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai UniversityShanghai 200444China

Due to its high operational voltage and energy density,P2-type Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2) has become a leading cathode material for sodium-ion batteries(SIBs),which is an ideal option for large-scale energy ***,the practical application of P2-type Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2) is limited by the capacity constraints and unwanted phase transitions,presenting significant challenges to the widespread application of *** address these challenges and optimize the electrochemical properties of the P2 phase cathode material,this study proposes a Cu and Zn co-doped strategy to improve the electrochemical *** incorporation of Cu/Zn can stabilize the P2-phase structure against P2-O2 phase transitions,thus enhancing its electrochemical *** as-obtained P2-type Na0.67[Ni_(0.3)Mn_(0.58)Cu_(0.09)Zn_(0.03)]O_(2) cathode material shows an impressive cycling stability,maintaining 80%capacity retention after 1000 cycles at 2 *** cyclic voltammetry(CV)tests show that the Cu^(2+)/Cu^(3+)redox reaction is also involved in charge compensation during the charge/discharge process.

关键词： Sodium-ion batteries Cathode material Cycle performance Cu/Zn co-doped P2-type Na_(0.67)Ni_(0.3)Mn_(0.7)O_(2)

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