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A Single-Event-Transient Hardened Phase Locked Loop for Clock and Data Recovery

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Chinese Journal of Electronics 2024年第2期33卷 353-361页

作者： Hengzhou YUAN Bin LIANG Hao SANG Weixia XU Yang GUO Xi CHEN national university of Defense Technology

A radiation-hardened phase-locked loop is proposed for phase interpolator clock and data recovery purposes. A sensitive node-compressed charge pump and multi-node cross coupling voltage-controlled oscillators are proposed in this phase-locked loop with the goal of achieving good jitter performance and improving anti-SET（SET,single-event transient） capability. The root mean square（RMS） jitter of the phase-locked loop is reduced from 3.7 ps to 2.58 ps at 2 GHz, while the laser threshold is improved from 120 p J to 370 p J compared to the unhardened phaselocked loop. The hardened phase-locked loop also does not lose its lock state from linear energy transfers（LETs） of 3.3 to 37.3 Me V·cm2/mg.

关键词： Charge pumps Voltage-controlled oscillators Energy exchange Noise Lasers Jitter Phase locked loops

Implicit policy constraint for offline reinforcement learning

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CAAI Transactions on Intelligence Technology 2024年第4期9卷 973-981页

作者： Zhiyong Peng Yadong Liu Changlin Han Zongtan Zhou national university of Defense Technology ChangshaChina

Offline reinforcement learning(RL)aims to learn policies entirely from passively collected datasets,making it a data‐driven decision *** of the main challenges in offline RL is the distribution shift problem,which causes the algorithm to visit out‐of‐distribution(OOD)*** distribution shift can be mitigated by constraining the divergence between the target policy and the behaviour ***,this method can overly constrain the target policy and impair the algorithm's performance,as it does not directly distinguish between in‐distribution and OOD *** addition,it is difficult to learn and represent multi‐modal behaviour policy when the datasets are collected by several different behaviour *** overcome these drawbacks,the au-thors address the distribution shift problem by implicit policy constraints with energy‐based models(EBMs)rather than explicitly modelling the behaviour *** EBM is powerful for representing complex multi‐modal distributions as well as the ability to distinguish in‐distribution samples and *** results show that their method significantly outperforms the explicit policy constraint method and other *** addition,the learnt energy model can be used to indicate OOD visits and alert the possible failure.

关键词： artificial intelligence artificial neural network learning(artificial intelligence) planning(artificial intelligence)

Optically levitated micro gyroscopes with an MHz rotational vaterite rotor

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Microsystems & Nanoengineering 2024年第3期10卷 219-227页

作者： Kai Zeng Xiangming Xu Yulie Wu Xuezhong Wu Dingbang Xiao College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China College of Information and Communication National University of Defense TechnologyWuhan 430000China Key Laboratory of Satellite Navigation Technology National University of Defense TechnologyChangsha 410073China

The field of levitated optomechanics has experienced significant advancements in manipulating the translational and rotational dynamics of optically levitated particles and exploring their sensing *** concept of using optically levitated particles as gyroscopes to measure angular motion has long been explored but has not yet been proven either theoretically or *** this study,we present the first rotor gyroscope based on optically levitated high-speed rotating *** gyroscope is composed of a micrometer-size ellipsoidal vaterite particle that is driven to rotate at MHz frequencies in a vacuum *** an external angular velocity is input,the optical axis deviates from its initial position,resulting in changes in the frequency and amplitude of the rotational *** analyzing these changes,the angular velocity of the input can be accurately detected,making it the smallest rotor gyroscope in the *** angular rate bias instability of the gyroscope is measured to be 0.08°/s and can be further improved to as low as 10^(−9)°/h theoretically by cooling the motion and increasing the angular moment of the levitated *** work opens a new application paradigm for levitated optomechanical systems and may pave the way for the development of quantum rotor gyroscopes.

关键词： particles rotational angular

Emission wavelength selection via anomalous polarized fluorescence in ZnO-C nanowires

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Nano Research 2024年第5期17卷 4489-4497页

作者： Joon Kiat Kang Kim Yong Lim Chorng Haur Sow Department of Physics National University of SingaporeSingapore 117542Singapore

Defect fluorescence from high aspect ratio semiconductor nanowires typically displays a weak polarization parallel to the nanowire’s long axis due to dielectric mismatch in high aspect ratio ***,anomalous 2.2 eV defect fluorescence distinctly polarized perpendicular to the nanowire is observed and measured from carbon-incorporated zinc oxide *** observations are significant because polarized defect emissions with consistent polarization on a mesoscopic scale are *** a systematic study and comparison of experimental results with density functional theory calculations,an oriented defect complex comprising carbon substituting on an oxygen site and an oxygen vacancy(CO-VO)is deduced to be responsible for the anomalous yellow fluorescence,demonstrating a method for relating atomic-scale defect geometry to mesoscopic *** anomalous emission can appear in both green-and red-fluorescing nanowires grown with different carbon concentrations,verifying the independence and uniqueness of the 2.2 eV *** allows for polarization-dependent emission wavelength selection from a single nanowire.

关键词： anomalous polarization defects fluorescence zinc oxide carbon

Room and cryogenic deformation behavior of AZ61 and AZ61-xCaO(x=0.5,1 wt.%)alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1996-2009页

作者： Umer Masood Chaudry Hafiz Muhammad Rehan Tariq Nooruddin Ansari Soo Yeol Lee Tea-Sung Jun Department of Mechanical Engineering Incheon National UniversityIncheon 22012Republic of Korea Research Institute for Engineering and Technology Incheon National UniversityIncheon 22012Republic of Korea Department of Materials Science&Engineering Chungnam National UniversityDaejeon 34134Republic of Korea

This study investigates the influence of CaO(0.5,1(wt.%))alloying on the microstructural evolution,texture development and deformation behavior of AZ61 magnesium *** uniaxial tension tests at room(RT)and cryogenic(CT,-150℃)temperature were performed to investigate the twinability and dislocation behavior and its consequent effect on flow stress,ductility and strain hardening *** results showed that the AZ61-1CaO exhibited superior strength/ductility synergy at RT with a yield strength(YS)of 223 MPa and a ductility of 23% as compared to AZ61(178 MPa,18.5%)and AZ61-0.5CaO(198 MPa,21%).Similar trend was witnessed for all the samples during CT deformation,where increase in the YS and decrease in ductility were *** Mtex tools based in-grain misorientation axis(IGMA)analysis of RT deformed samples revealed the higher activities of prismatic slip in AZ61-CaO,which led to superior ***,subsequent EBSD analysis of CT deformed samples showed the increased fraction of fine{10-12}tension twins and nucleation of multiple{10-12}twin variants caused by higher local stress concentration at the grain boundaries,which imposed the strengthening by twin-twin ***,the detailed investigations on strengthening contributors showed that the dislocation strengthening has the highest contribution towards strength in all samples.

关键词： Magnesium Twinning Twinning variant EBSD Cryogenic deformation

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Bioinspired sensing-memory-computing integrated vision systems: biomimetic mechanisms, design principles, and applications

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Science China(Information Sciences) 2024年第5期67卷 5-27页

作者： Yujie HUANG Yinlong TAN Yan KANG Yabo CHEN Yuhua TANG Tian JIANG Institute for Quantum Information and State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology College of Advanced Interdisciplinary Studies National University of Defense Technology Institute for Quantum Science and Technology College of ScienceNational University of Defense Technology

With the explosion of sensory data in the Internet of Things(Io T) era, conventional machine vision systems are becoming increasingly difficult to meet the requirements of high efficiency, low energy consumption, and low latency due to their inherent shortcomings of separate sensing, memory, and computing units. Inspired by the retina and neuromorphic computing, the sensing-memory-computing integrated vision system(SMCVS) that features low power consumption, low latency, and high parallelism has been considered a promising technology to surpass the von Neumann architecture and realize strong artificial ***, novel materials like two-dimensional semiconductors and quantum dots with novel optoelectronic performance provide hardware carriers for implementing integrated sensing-memory-computing architectures,attracting considerable attention. This paper reviews the recent research progress in bioinspired vision systems in terms of biomimetic mechanisms, design principles, computational architectures, and ***, the biomimetic mechanisms are illustrated to guide the design of high-performance artificial visual perception systems. Then the research progress of optoelectronic-synapse-based bioinspired vision systems in the device principles and applications including image filtering, color recognition, visual adaptation, and motion detection are summarized. Finally, the challenges and future developing directions of the SMCVS are provided regarding bionic application, architecture design, and device fabrication.

关键词： sensing-memory-computing architecture neuromorphic computing retinomorphic device image recognition visual system

Learnware:small models do big

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Science China(Information Sciences) 2024年第1期67卷 39-50页

作者： Zhi-Hua ZHOU Zhi-Hao TAN national Key Laboratory for Novel Software Technology Nanjing University

There are complaints about current machine learning techniques such as the requirement of a huge amount of training data and proficient training skills,the difficulty of continual learning,the risk of catastrophic forgetting,and the leaking of data privacy/*** research efforts have been focusing on one of those concerned issues separately,paying less attention to the fact that most issues are entangled in *** prevailing big model paradigm,which has achieved impressive results in natural language processing and computer vision applications,has not yet addressed those issues,whereas becoming a serious source of carbon *** article offers an overview of the learnware paradigm,which attempts to enable users not to need to build machine learning models from scratch,with the hope of reusing small models to do things even beyond their original purposes,where the key ingredient is the specification which enables a trained model to be adequately identified to reuse according to the requirement of future users who know nothing about the model in advance.

关键词： artificial intelligence machine learning learnware

Callus proliferation-induced hypoxic microenvironment decreases shoot regeneration competence in Arabidopsis

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Molecular Plant 2024年第3期17卷 395-408页

作者： Dohee Koo Hong Gil Lee Soon Hyung Bae Kyounghee Lee Pil Joon Seo Department of Chemistry Seoul National UniversitySeoul 08826Korea Plant Genomics and Breeding Institute Seoul National UniversitySeoul 08826Korea Research Institute of Basic Sciences Seoul National UniversitySeoul 08826Korea

Plants are aerobic organisms that rely on molecular oxygen for respiratory energy *** conditions,with oxygen levels ranging between 1%and 5%,usually limit aerobic respiration and affect plant growth and ***,we demonstrate that the hypoxic microenvironment induced by active cell proliferation during the two-step plant regeneration process intrinsically represses the regener-ation competence of the callus in Arabidopsis *** showed that hypoxia-repressed plant regener-ation is mediated by the RELATED TO APETALA2.12(RAP2.12)protein,a memberof the Ethylene Response Factor VIl(ERF-Vll)*** found that the hypoxia-activated RAP2.12 protein promotes salicylic acid(SA)biosynthesis and defense responses,thereby inhibiting pluripotency acquisition and de novo shoot regeneration in *** and genetic analyses revealed that RAP2.12 could bind directly to the SALICYLIC ACID INDUCTION DEFICIENT 2(SID2)gene promoter and activate SA biosynthesis,repressing plant regeneration possibly via a PLETHORA(PLT)-dependent ***,the rap2.12 mutant calli exhibits enhanced shoot regeneration,which is impaired by SA *** together,these find-ings uncover that the cell proliferation-dependent hypoxic microenvironment reduces cellular pluripotency and plant regeneration through the RAP2.12-SID2 module.

关键词： callus cell proliferation-induced hypoxia SID2 plant regeneration salicylic acid RAP2.12

Enhanced prediction of anisotropic deformation behavior using machine learning with data augmentation

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Journal of Magnesium and Alloys 2024年第1期12卷 186-196页

作者： Sujeong Byun Jinyeong Yu Seho Cheon Seong Ho Lee Sung Hyuk Park Taekyung Lee School of Mechanical Engineering Pusan National UniversityBusan 46241South Korea School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566South Korea

Mg alloys possess an inherent plastic anisotropy owing to the selective activation of deformation mechanisms depending on the loading *** characteristic results in a diverse range of flow curves that vary with a deformation *** study proposes a novel approach for accurately predicting an anisotropic deformation behavior of wrought Mg alloys using machine learning(ML)with data *** developed model combines four key strategies from data science:learning the entire flow curves,generative adversarial networks(GAN),algorithm-driven hyperparameter tuning,and gated recurrent unit(GRU)*** proposed model,namely GAN-aided GRU,was extensively evaluated for various predictive scenarios,such as interpolation,extrapolation,and a limited dataset *** model exhibited significant predictability and improved generalizability for estimating the anisotropic compressive behavior of ZK60 Mg alloys under 11 annealing conditions and for three loading *** GAN-aided GRU results were superior to those of previous ML models and constitutive *** superior performance was attributed to hyperparameter optimization,GAN-based data augmentation,and the inherent predictivity of the GRU for *** a first attempt to employ ML techniques other than artificial neural networks,this study proposes a novel perspective on predicting the anisotropic deformation behaviors of wrought Mg alloys.

关键词： Plastic anisotropy Compression Annealing Machine learning Data augmentation

维普期刊数据库