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TDD-net: a tiny defect detection network for printed circuit boards

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CAAI Transactions on Intelligence Technology 2019年第2期4卷 110-116页

作者： Runwei Ding Linhui Dai Guangpeng Li Hong Liu Key Laboratory of Machine Perception Peking University Shenzhen Graduate School People’s Republic of China shenzhen skyworth-rgb electronic CO. Ltd. People’s Republic of China

Tiny defect detection (TDD) which aims to perform the quality control of printed circuit boards (PCBs) is a basic and essential task in the production of most electronic products. Though significant progress has been made in PCB defect detection, traditional methods are still difficult to cope with the complex and diverse PCBs. To deal with these problems, this article proposes a tiny defect detection network (TDD-Net) to improve performance for PCB defect detection. In this method, the inherent multi-scale and pyramidal hierarchies of deep convolutional networks are exploited to construct feature pyramids. Compared with existing approaches, the TDD-Net has three novel changes. First, reasonable anchors are designed by using k-means clustering. Second, TDD-Net strengthens the relationship of feature maps from different levels and benefits from low-level structural information, which is suitable for tiny defect detection. Finally, considering the small and imbalance dataset, online hard example mining is adopted in the whole training phase in order to improve the quality of region-of-interest (ROI) proposals and make more effective use of data information. Quantitative results on the PCB defect dataset show that the proposed method has better portability and can achieve 98.90% mAP, which outperforms the state-of-arts. The code will be publicly available.

关键词： TDD PCBs TDD-Net

All-day solar power generation enabled by photo/thermoelectric conversion and thermal energy storage

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Science China Chemistry 2025年

作者： Zijian Liu Chengzhi Chen Junda Liu Qi Sun Bingchen Huo Chunyu Du Guangming Chen College of Materials Science and Engineering Shenzhen University

Thermoelectric materials hold promises for direct conversion of heat into electricity, making them viable power sources for electronic devices. However, their practical applications in diverse outdoor environment are hindered by limited and discontinuous electricity output. In this study, we propose an all-day solar power generator to achieve highly efficient and continuous electricity generation by harnessing the synergistic effects of photoelectric-thermoelectric conversion and latent thermal energy storage. The all-day solar power generator exhibits an average open-circuit voltage of 6.8 m V during daylight and a remaining 0.9 mV during nighttime. Importantly, the all-day solar power generator achieves dependable outdoor power supply for communication transmission in diverse environmental scenarios. Our research opens a new way for highly efficient and sustainable power generation.

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An Efficient Boron Source Activation Strategy for the Low‑Temperature Synthesis of Boron Nitride Nanotubes

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Nano-Micro Letters 2025年第1期17卷 548-558页

作者： Ying Wang Kai Zhang Liping Ding Liyun Wu Songfeng E Qian He Nanyang Wang Hui Zuo Zhengyang Zhou Feng Ding Yue Hu Jin Zhang Yagang Yao National Laboratory of Solid State Microstructures College of Engineering and Applied SciencesJiangsu Key Laboratory of Artificial Functional Materialsand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093People’s Republic of China School of electronic Information and Artificial Intelligence Shaanxi University of Science&TechnologyXian 710000People’s Republic of China College of Bioresources Chemical and Materials Engineering Shaanxi University of Science&TechnologyXian 710000People’s Republic of China Key Laboratory of Carbon Materials of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325000People’s Republic of China shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518000People’s Republic of China College of Chemical and Molecular Engineering Peking UniversityBeijing 100871People’s Republic of China

Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their *** primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid *** this study,we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO–B *** approach can be adopted to form various low-melting-point AM–Mg–B–O growth *** growth systems have improved catalytic capability and reactivity even under low-temperature conditions,facilitating the synthesis of BNNTs at temperatures as low as 850℃.In addition,molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN *** findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs.

关键词： Boron nitride nanotubes Low-temperature Boron activation Density functional theory

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Nanoimprint lithography-assisted block copolymer self-assembly for hyperfine fabrication of magnetic patterns based on L10-FePt nanoparticles

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Science China Chemistry 2025年

作者： Jie Zhang Yi Chen Guijun Li Zelin Sun Zhengong Meng Wai-Yeung Wong Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy The Hong Kong Polytechnic University The Hong Kong Polytechnic University shenzhen Research Institute Division of Integrative Systems and Design and Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology School of Flexible electronics (Future Technology) and Institute of Advanced Materials (IAM) Nanjing Tech University

L10-FePt-type bit-patterned media has provided a promising alternative for ultrahigh-density magnetic recording systems in the current digital era, but rapid fabrication of magnetic patterns with hyperfine bit islands is still challenging, especially with the target for miniaturization and scalable production simultaneously. Herein, Fe,Pt-containing block copolymers were utilized as single-source precursors for solution-processable patterning and subsequent generation of the demanding magnetic FePt dots by in situ pyrolysis. High-throughput nanoimprint lithography was initially employed to fabricate the predefined bit cells precisely,and then the intrinsic self-assembly of phase-separated block copolymers further drove the formation of accurate bit *** from the synergistic effect of top-down lithographic approach and bottom-up self-assembly, the customizable patterns could be achieved for large-scale mass production in targeted areas, but high-density isolated dots could also be accurately aligned along the patterned features after subsequent self-assembly. This reliable strategy would provide a good avenue to precisely construct ultrahigh-density magnetic data storage devices.

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LD-pumped 6 W cw Tm^3＋-Doped Silica Double-Cladding Fibre Laser

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Chinese Physics Letters 2008年第3期25卷 957-959页

作者：杜戈果黎大军张敏闫培光陈立成周耀华阮双琛 shenzhen Key Laboratory of Laser Engineering College of Electronic Science and Technology Shenzhen University Shenzhen 518060

We report a thulium-doped silica fibre laser that generates a maximum cw output power of 6 W in a 2 μm wavelength range when cladding-pumped by a laser diode （LD） operating at approximately 791 nm at room temperature. The slope efficiency with respect to the launched pump power is 50% and 38.4%, with and without an output coupler mirror, respectively. The corresponding thresholds are 2.8 W and 4.8 W, respectively. The beam qualities Mx^2 and My^2 are 1.26 and 1.32, respectively. The experimental results are also analysed.

关键词： supernova explosion proto-neutron star shock wave

Q-Switched Thulium-Doped Domestic Silica Fiber Laser

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Chinese Physics Letters 2011年第4期28卷 112-114页

作者： HU Hui DU Ge-Guo YAN Pei-Guang ZHAO Jun-Qing GUO Chun-Yu RUAN Shuang-Chen shenzhen Key Laboratory of Laser Engineering College of Electronic Science and TechnologyShenzhen UniversityShenzhen 518060

We report a cladding-pumped Tm^(3+)-doped domestic silica fiber laser operated at 2pm and actively Q-switched with an acousto-optic *** trains are obtained as pumped by a 785nm laser *** maximum average output power is *** power up to 4.2kW and pulse energy up to 840μJ are obtained with the pulse duration of 200ns produced at a repetition rate of 1 *** laser performance is studied under different repetition rates and pump ***,we give some discussion.

关键词： pumped laser pulse

A Switchable Multi-wavelength Erbium-Doped Photonic Crystal Fiber Laser with Linear Cavity Configuration

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Chinese Physics Letters 2012年第12期29卷 86-88页

作者： ZHENG Wan-Jun CHENG Jian-Qun RUAN Shuang-Chen ZHANG Min LIU Wen-Li YANG Xi ZHANG Ying-Ying shenzhen Key Laboratory of Laser Engineering College of Electronic Science and TechnologyShenzhen UniversityShenzhen 518060

A switchable multi-wavelength erbium-doped photonic crystal fiber laser with a linear cavity configuration based on a Sagnac loop mirror is proposed and demonstrated *** laser is based on saturated spectral hole burning and the polarization hole burning effects can be switched among single-wavelength,dual-wavelength,triple-wavelength and quadruple-wavelength outputs at room *** wavelength period of the output spectrum is easily varied by using polarization maintaining fibers of different *** proposed fiber laser has a signal-to-noise ratio of higher than 30 dB and achieves a low threshold power of 37 *** power fluctuations of the lasing lines are less than 0.54 dB,1.7 dB and 2.9 dB when the laser operates at single-wavelength,dual-wavelength and triple-wavelength for one hour.

关键词： polarization Erbium switched

A Wide-Band Thulium-Doped Silica Fibre Amplifier

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Chinese Physics Letters 2006年第12期23卷 3291-3293页

作者：杜戈果黎大军李宏伟麦炳梁游杰顺阮双琛 shenzhen Key Laboratory of Laser Engineering College of Electronic Science and Technology Shenzhen University Shenzhen 518060

We investigate a silica-based thulium-doped fibre amplifier, which is a promising candidate for an amplifying device in the S band, in detail using a single wavelength upconversion pumping scheme centred at 1064nm. Our experimental results show that in terms of gain and noise figure, the bi-directional pumping scheme is the best one in the three pumping schemes, named forward, backward and hi-directional pumping schemes. The amplifier has a gain not only in the S band, but also in the C band, even in the L band. The gain is above 3dB from 1525nm to 1580nm with a peak of ***.

关键词： 1.47 MU-M RAMAN AMPLIFIER

Real-time,continuous-wave terahertz imaging by a pyroelectric camera

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Chinese Optics Letters 2008年第1期6卷 29-31页

作者：杨珺阮双琛张敏 College of electronic Science and Technology Shenzhen University

Real-time, continuous-wave terahertz （THz） imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.

关键词： Cameras Light sources Lighting Optically pumped lasers Pyroelectricity

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