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Layer-by-layer epitaxy growth of thickness-controllable two-dimensional tungsten disulfide

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Science China(Information Sciences) 2024年第5期67卷 302-310页

作者： Jieyuan LIANG Zixing ZOU Junwu LIANG Di WANG Biao WANG Anshi CHU Jiali YI Cheng ZHANG Lizhen FANG Tian ZHANG Huawei LIU Xiaoli ZHU Dong LI Anlian PAN Key Laboratory for Micro-Nano Physics and Technology of Hunan Province State Key Laboratory of Chemo/Biosensing and Chemometrics Hunan Institute of Optoelectronic IntegrationCollege of Materials Science and Engineering School of Physics and ElectronicsHunan University school of Electronic Information and Electrical engineering Changsha University school of Physics and Telecommunication engineering Yulin Normal University Units Semiconductor Technology Co. Ltd. school of Physics and electronics Hunan Normal University

Bilayer transition metal dichalcogenides（TMDs） balance the high mobility of single layers with the high state density of multilayers and therefore have promising application prospects in high-performance electronics. However, the layer-controlled growth of 2D materials is still confronted with challenges such as poor repeatability between different labs and a limited understanding of the growth mechanism at the atomic scale. Herein, we report a new carbon-assisted chemical vapor deposition process that can realize the growth of WS2sheets with high yield, precise thickness controllability, and repeatability. We show that carbon can act as a reducing agent and catalyst that preferentially reacts with the WO3precursor to form intermediate WO3-xproducts with low-valence state W. The resulting oxycarbide gas has a low surface adsorption energy when deposited on the surface of as-grown WS2, which provides nucleation sites for the subsequent layer of WS2growth and leads to the vertical growth of WS2sheets. The growth mechanism is thoroughly investigated. Electrical transport measurements show that the produced bilayer WS2possesses a high carrier mobility(up to 58 cm2·V-1·s-1) and small subthreshold swing（estimated to be 148 mV/decade）,which are among the best reported results for TMDs produced using CVD.

关键词： WS$_2$ thickness-controlled growth chemical vapor deposition additive carbon

High-efficiency ultra-fast all-optical photonic crystal diode based on the lateral-coupled nonlinear elliptical defect

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Chinese Physics B 2024年第3期33卷 453-458页

作者：李大星刘凯柱余春龙张括刘跃钦冯帅 school of Science Minzu University of ChinaBeijing 100081China Optoelectronics Research Center Minzu University of ChinaBeijing 100081China engineering Research Center of Photonic Design Software Ministry of EducationBeijing 100081China school of Optoelectronic engineering and instrumentation Science Dalian University of TechnologyDalian 116024China

An all-optical Fano-like diode featuring a nonlinear lateral elliptical micro-cavity and a reflecting column in the photonic crystal waveguide is *** asymmetric micro-cavity is constructed by removing one rod and changing the shape of the lateral rod from a circle to an ellipse.A reflecting pillar is also introduced into the waveguide to construct an F-P cavity with the elliptical defect and enhance the asymmetric transmission for the incident light wave transmitting rightwards and leftwards,*** designing the size of the ellipse and optimizing a reflecting rod at a suitable position,a maximum forward light transmittance of-1.14 dB and a minimum backward transmittance of-57.66 dB are achieved at the working wavelength of 1550.47 *** corresponding response time is about 10 ps when the intensity of the pump light beam resonant at 637 nm is 3.97 W/μm2.

关键词： photonic crystal all-optical diode Fano cavity unidirectional transmission

Neural dynamics for improving optimiser in deep learning with noise considered

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CAAI Transactions on Intelligence Technology 2024年第3期9卷 722-737页

作者： Dan Su Predrag S.Stanimirović Ling Bo Han Long Jin school of Information Science and engineering Lanzhou UniversityLanzhouChina Faculty of Sciences and Mathematics University of NišNišSerbia school of electronics and Information engineering Guangdong Ocean UniversityZhanjiangChina

As deep learning evolves,neural network structures become increasingly sophisticated,bringing a series of new optimisation *** example,deep neural networks(DNNs)are vulnerable to a variety of *** neural networks under privacy constraints is a method to alleviate privacy leakage,and one way to do this is to add noise to the ***,the existing optimisers suffer from weak convergence in the presence of increased noise during training,which leads to a low robustness of the *** stabilise and improve the convergence of DNNs,the authors propose a neural dynamics(ND)optimiser,which is inspired by the zeroing neural dynamics originated from zeroing neural *** authors first analyse the relationship be-tween DNNs and control ***,the authors construct the ND optimiser to update network ***,the proposed ND optimiser alleviates the non-convergence problem that may be suffered by adding noise to the gradient from different ***,experiments are conducted on different neural network structures,including ResNet18,ResNet34,Inception-v3,MobileNet,and long and short-term memory *** results using CIFAR,YouTube Faces,and R8 datasets demonstrate that the ND optimiser improves the accuracy and stability of DNNs under noise-free and noise-polluted *** source code is publicly available at https://***/LongJin-lab/ND.

关键词： deep learning deep neural networks

Properties of radiation defects and threshold energy of displacement in zirconium hydride obtained by new deep-learning potential

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Chinese Physics B 2024年第7期33卷 456-465页

作者：王玺唐孟蒋明璇陈阳春刘智骁邓辉球 school of Physics and electronics Hunan UniversityChangsha 410082China College of Materials Science and engineering Hunan UniversityChangsha 410082China

Zirconium hydride(ZrH_(2)) is an ideal neutron moderator material. However, radiation effect significantly changes its properties, which affect its behavior and the lifespan of the reactor. The threshold energy of displacement is an important quantity of the number of radiation defects produced, which helps us to predict the evolution of radiation defects in ZrH_(2).Molecular dynamics(MD) and ab initio molecular dynamics(AIMD) are two main methods of calculating the threshold energy of displacement. The MD simulations with empirical potentials often cannot accurately depict the transitional states that lattice atoms must surpass to reach an interstitial state. Additionally, the AIMD method is unable to perform largescale calculation, which poses a computational challenge beyond the simulation range of density functional theory. Machine learning potentials are renowned for their high accuracy and efficiency, making them an increasingly preferred choice for molecular dynamics simulations. In this work, we develop an accurate potential energy model for the ZrH_(2) system by using the deep-potential(DP) method. The DP model has a high degree of agreement with first-principles calculations for the typical defect energy and mechanical properties of the ZrH_(2) system, including the basic bulk properties, formation energy of point defects, as well as diffusion behavior of hydrogen and zirconium. By integrating the DP model with Ziegler–Biersack–Littmark(ZBL) potential, we can predict the threshold energy of displacement of zirconium and hydrogen in ε-ZrH_(2).

关键词： zirconium hydride deep learning potential radiation defects molecular dynamics threshold energy of displacement

Efficient unequal error protection for online fountain codes

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Journal of Systems engineering and electronics 2024年第2期35卷 286-293页

作者： SHI Pengcheng WANG Zhenyong LI Dezhi LYU Haibo school of electronics and Information engineering Harbin Institute of TechnologyHarbin 150001China Shenzhen Academy of Aerospace Technology Shenzhen 518057China

In this paper,an efficient unequal error protection(UEP)scheme for online fountain codes is *** the buildup phase,the traversing-selection strategy is proposed to select the most important symbols(MIS).Then,in the completion phase,the weighted-selection strategy is applied to provide low *** performance of the proposed scheme is analyzed and compared with the existing UEP online fountain *** results show that in terms of MIS and the least important symbols(LIS),when the bit error ratio is 10-4,the proposed scheme can achieve 85%and 31.58%overhead reduction,respectively.

关键词： online fountain code random graph unequal error protection(UEP) rateless code

Stochastic Computing Convolutional Neural Network Architecture Reinvented for Highly Efficient Artificial Intelligence Workload on Field-Programmable Gate Array

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Research 2024年第2期2024卷 55-79页

作者： Yang Yang Lee Zaini Abdul Halim Mohd Nadhir Ab Wahab Tarik Adnan Almohamad school of Electrical and Electronic engineering Universiti Sains MalaysiaNibong Tebal 14300 Penang Malaysia school of Computer Sciences Universiti Sains MalaysiaGelugor11800 PenangMalaysia Electrical-electronics engineering Department Faculty of EngineeringKarabuk University78050 KarabukTurkiye

Stochastic computing(SC)has a substantial amount of study on application-specific integrated circuit(ASIC)design for artificial intelligence(AI)edge computing,especially the convolutional neural network(CNN)***,SC has little to no optimization on field-programmable gate array(FPGA).Scaling up the ASIC logic without FPGA-oriented designs is inefficient,while aggregating thousands of bitstreams is still challenging in the conventional *** research has reinvented several FPGA-efficient 8-bit SC CNN computing architectures,i.e.,SC multiplexer multiply-accumulate,multiply-accumulate function generator,and binary rectified linear unit,and successfully scaled and implemented a fully parallel CNN model on Kintex7 *** proposed SC hardware only compromises 0.14%accuracy compared to binary computing on the handwriting Modified National Institute of Standards and Technology classification task and achieved at least 99.72%energy saving per image feedforward and 31?more data throughput than modern *** to SC,early decision termination pushed the performance baseline exponentially with minimum accuracy loss,making SC CNN extremely lucrative for AI edge computing but limited to classification *** SC's inherent noise heavily penalizes CNN regression performance,rendering SC unsuitable for regression tasks.

关键词： hardware Highly rendering

Vehicle Head and Tail Recognition Algorithm for Lightweight DCDSNet

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Computers, Materials & Continua 2024年第9期80卷 4451-4473页

作者： Chao Wang Kaijie Zhang Xiaoyong Yu Dejun Li Wei Xie Xinqiao Wang school of Informatics and engineering Suzhou UniversitySuzhou234000China school of Informatics and engineering Suzhou Vocational College of Civil AviationSuzhou234122China Institute of Machine Learning and Systems Biology School of Electronics and Information EngineeringTongji UniversityShanghai201804China

In the model of the vehicle recognition algorithm implemented by the convolutional neural network,the model needs to compute and store a lot of *** many parameters occupy a lot of computational resources making it difficult to run on computers with poor ***,obtaining more efficient feature information of target image or video with better accuracy on computers with limited arithmetic power becomes the main goal of this *** this paper,a lightweight densely connected,and deeply separable convolutional network(DCDSNet)algorithmis proposed to achieve this *** Geometry Group(VGG)model is improved by utilizing the convolution instead of the fully connected module,the deeply separable convolution module,and the densely connected network module,with the first two modules reducing the parameters and the third module allowing the algorithm to have more features in a limited number of *** algorithm achieves better results in the mine vehicle recognition *** show that the recognition accuracy is improved by 4.41% compared to VGG19 and the amount of parameters is reduced by 71% compared to VGG19.

关键词： VGGNet vehicle head and tail recognition densely connected depthwise separable convolutional

All-optical suppression on the impact of Sun outage in laser satellite communication systems by using a nonlinear semiconductor optical amplifier

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Chinese Optics Letters 2024年第2期22卷 76-80页

作者：李晓亮刘荣科范峰 school of electronics and Information engineering Beihang UniversityBeijing 100191China Beijing Research Institute of Telemetry Beijing 100094China

We introduce an all-optical approach,optical parametric amplification(OPA)processor to suppress the impact of Sun outage in laser satellite communication systems,which is implemented by only one nonlinear semiconductor optical amplifier driven by both electrical and optical *** optimized OPA processor,with a current of 539 mA and a pump-to-signal ratio of 16 dB,could significantly improve the signal quality by 3.5 dB in experiments for the elevation angle of Sun radiation of 0 *** signal quality improvement is observed in the whole range of the elevation angle,confirming the effectiveness of the proposed OPA processor in the field of Sun radiation mitigation.

关键词： nonlinear optics Sun outage laser satellite communication

Ultra-high sensitivity fiber optic microphone with corrugated graphene-oxide diaphragm for voice recognition

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Nano Research 2024年第8期17卷 7593-7602页

作者： Yang Liu Cheng Li Lingxiao Yu Zhengwei Wu Shangchun Fan Ruitao Lv school of instrumentation and Optoelectronic engineering Beihang UniversityBeijing 100191China Shenzhen Institute of Beihang University Shenzhen 518063China Key Laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100190China

To avoid interference from unexpected background noises and obtain high fidelity voice signal,acoustic sensors with high sensitivity,flat frequency response,and high signal-to-noise ratio(SNR)are urgently needed for voice ***(GO)has received extensive attention due to its advantages of controllable thickness and high fracture ***,low mechanical sensitivity(SM)introduced by undesirable initial stress limits the performance of GO material in the field of voice *** alleviate the aforementioned issue,GO diaphragm with annular corrugations is *** means of the reusable copper mold machined by picosecond laser,the fabrication and transfer of corrugated GO diaphragm are realized,thus achieving a Fabry–Perot(F–P)acoustic *** from the structural advantage of the corrugated GO diaphragm,our F–P acoustic sensor exhibits high S_(M)(43.70 nm/Pa@17 kHz),flat frequency response(−3.2 to 3.7 dB within 300–3500 Hz),and high SNR(76.66 dB@1 kHz).In addition,further acoustic measurements also demonstrate other merits,including an excellent frequency detection resolution(0.01 Hz)and high time stability(output relative variation less than 6.7% for 90 min).Given the merits presented before,the fabricated F–P acoustic sensor with corrugated GO diaphragm can serve as a high-fidelity platform for acoustic detection and voice *** conjunction with the deep residual learning framework,high recognition accuracy of 98.4%is achieved by training and testing the data recorded by the fabricated F–P acoustic sensor.

关键词： corrugated graphene-oxide(GO)diaphragm Fabry-Perot(F-P)acoustic sensor mechanical sensitivity voice recognition