PCB defect detection system based on image processingCai, Li; Li, Jingchuan
doi: 10.1088/1742-6596/2383/1/012077pmid: N/A
Under the background of intelligent manufacturing, the quality inspection of printed circuit board (PCB), as the carrier of electronic products, plays an important role. In view of the shortcomings of existing traditional detections, this paper has put forward a PCB detection method based on machine vision, focusing on image preprocessing algorithm and detection analysis. The median filter algorithm was used to remove the noise in the image. Logarithmic transformation was used to enhance image contrast. Sobel operator was used for edge detection to obtain the geometric center of the defect area. On this basis, the PCB image was registered by template matching method, and the difference between the preprocessed PCB image to be tested and the standard PCB image was calculated to get the difference map. Subsequently, morphological algorithm was used to remove the slight differences and obtain the defect map. In the end, the simulation results have shown that the proposed algorithm has good detection effect and high precision in PCB defect detection.
Study on silencing performance of small hole injection muffler in sealed cabinRen, Yafei; Yang, Dongsheng; Zhao, Jian; Xie, Wen; Du, Guofei; Liu, Guofeng; Huang, Xin
doi: 10.1088/1742-6596/2383/1/012013pmid: N/A
The astronauts need to re pressurize the sealed cabin after returning to the sealed cabin. The noise generated in the process of re pressurization is too large, so a silencer shall be set to reduce the noise in the cabin. Through theoretical analysis, this paper selects the small hole injection muffler, makes theoretical calculation, and determines the specific structural size of the muffler. The test shows that when the cabin pressure rises to 85kpa, the use of the small hole injection silencer can reduce the cabin noise from 85.7db to 66.3db, which meets the medical requirements of astronauts.
Simulation analysis of rolling bearings based on explicit dynamicsZeng, Fan; Liu, Yong-bao; Wang, Qiang; Li, Jun
doi: 10.1088/1742-6596/2383/1/012158pmid: N/A
Based on LS-PrePost software, the three-dimensional display of healthy cylindrical roller bearings was established finite element model for dynamic simulation. Based on the explicit algorithm, the model analyzes the law of bearing stress level with radial outward load under the conditions of friction contact, speed and load, and based on the healthy roller bearing model, simulates the local spalling fault of the outer raceway by setting the unit defect, and analyzes the equivalent force change process when the roller through the fault area. The simulation results are compared with the theoretical calculation results to verify the correctness of the finite element model of the faulty bearings, and provide a certain reference for the fault diagnosis of rolling bearings.
Design and stability analysis of bionic end-effector fingers for yarn tube grippingGuan, Shengqi; Wang, Jingguo; Wang, Xu; Yu, Zijiang; Hao, Zhenhu; Zhang, Libo; Wang, Yingyu; Wang, Junqiang
doi: 10.1088/1742-6596/2383/1/012016pmid: N/A
According to the development demand of automatic yarn tube loading equipment in textile field, a fingertip gripping stability evaluation method is proposed and applied to the end-effector structure design suitable for multi-size yarn tube gripping. Firstly, by studying the human hand mechanism, the tendon type underdrive principle is used to design the rope sheave layout and tendon path of the end-effector finger, and its overall structural design is introduced; secondly, a virtual spring is used to establish an equivalent model of fingertip contact, and the grasping stability is evaluated from the perspective of system potential energy by constructing a stiffness matrix; on this basis, an elliptical curve under geometric constraints is used as the fingertip profile curve, and the release sample is used to Finally, quantitative analysis of gripping stability based on a yarn tube gripping model. The research results lay the foundation for the design of an efficient and reliable yarn tube gripping device. The working principle and design ideas of the bionic end-effector have some implications for the design of robotic end-effectors serving other fields.
Solid-phase preparation of defective carbon supported PtNi alloy electrocatalyst and analysis of its oxygen reduction mechanismWang, Zhaoxi; Chen, Yanli; Yan, Wei; Cheng, Yuanzhuang
doi: 10.1088/1742-6596/2383/1/012133pmid: N/A
In the present work, PtNi-loaded defective carbon (Pt/ZnPPC) was prepared by solid-phase method. Carbon support with specific defect types, such as Zn metal nitrogen carbon (ZnPPC850), N-doped carbon (ZnPPC950) and defective carbon (ZnPPC1050), were selectively obtained by optimizing the pyrolysis temperature to explore the effect of defect types on oxygen reduction reactions (ORR). Electrochemical measurements showed that the half-wave potential of the PtNi metal nanoparticle-loaded ZnPPC1050 catalyst (PtNi-ZnPPC1050) outperformed the commercial JM-Pt/C by 35 mV, and by 45 mV compared to the PtNi-loaded ZnPPC950 catalyst (PtNi-ZnPPC950), suggesting that the defects in the ZnPPC1050 support resulting from the evaporation of N by pyrolysis can interact well with Pt metal electrically, allowing the PtNi nanoparticles to be uniformly distributed. Meanwhile, the defects lead to the carrier containing a large number of active sites making its catalytic performance even much better than the pyridine nitrogen sites in ZnPPC950. The carbon defect structure is loosened and porous with high specific surface area, which can effectively load PtNi nanoparticles and enhance the mass transfer. We obtained a new bimetallic oxygen reduction catalyst loaded with PtNi on defective carbon and elucidated the effect of five-membered ring carbon defect structure and N-doped structure on metal-carrier interaction.
Transient Force-Magnetic Coupling Simulation Research on Pipeline Stress ConcentrationSu, Zhengda; Xin, Jiaxing; Zhang, Qingbao; Chen, Jinzhong; Guo, Yanbao
doi: 10.1088/1742-6596/2383/1/012151pmid: N/A
The stress concentration of oil and gas pipelines will produce corrosion cracks and axial fatigue cracks under the action of long-term and repeated internal pressure, and will rapidly expand under fluctuating internal pressure, resulting in serious pipeline accidents. In order to effectively detect the stress concentration of oil and gas pipelines, a stress concentration detection technology of unsaturated local magnetization pipeline is proposed. This paper introduces the theoretical basis of local pipeline stress concentration detection, establishes a two-dimensional finite element model of pipeline stress concentration transient force-magnetic coupling, and analyzes the influence of excitation source position, sensor lift-off value, and stress concentration value on the response signal. The simulation results show that the corresponding signal Bxof the stress concentration changes more obviously than Byand the signal is regular, Bxhas a good two-stage linear positive correlation with the stress concentration value. The above research provides technical support for the development of pipeline on-line stress concentration detection probe.
Effects of Deflection Mode on Flared-Maneuver Performance of Unpowered Heavy Airdrop SystemWu, Yutong; Yang, Dongyu
doi: 10.1088/1742-6596/2383/1/012020pmid: N/A
For the landing process of a large-scale airdrop system, flared-maneuver is a common approach to decelerate to prevent huge impacts while touching down. A 6-DOF model of parafoil-load system is used to investigate the effects of different deflection modes on airdrop system’s landing performance. By numerical simulation, three main factors, distance of deflection, rate of deflection and the pattern of rate changing, are discussed according to the results. The conclusion derived is of some significance in assisting control and design of landing procedure of such unpowered heavy airdrop systems.
Preparation of CMAS, LZS glass-ceramics and study of the glass ceramics anti-corrosion properties in liquid leadbismuth eutectic at 500°CWan, Yi; Luo, Lin; Jiang, Zhizhong; Liu, Jing; Wei, Jie; Xiao, Zunqi
doi: 10.1088/1742-6596/2383/1/012109pmid: N/A
Liquid lead-bismuth eutectic (LBE) was an important candidate material for the fourth generation reactor coolant. Its high temperature and heavy metal corrosion conditions put forward higher requirements for the corrosion resistance of reactor structural materials. As a new kind of special material, glass-ceramic material, which possesses the excellent properties of glass and ceramics, has good mechanical property, wear-resisting property and corrosion resistance. The LBE corrosion behavior of glass-ceramics at typical operating temperatures of nuclear reactors was investigated. The lead bismuth corrosion test was carried out under the condition of oxygen saturation at 500°C for 500h. The lead bismuth corrosion resistance of the two glass ceramic samples in static LBE was analyzed by means of scanning electron microscope (SEM) and X-ray diffraction (XRD). After 500 h corrosion in oxygen saturated liquid LBE at 500°C, there was no obvious corrosion on the surface of CMAS glass ceramics. Its dense microstructure and stable phase composition effectively prevented the penetration of Pb and Bi elements, and had good resistance to corrosion; The surface of LZS glass ceramics was covered with a layer of loose and porous compounds, and the thickness of the corrosion zone was 10 μm, which occurred a certain degree of lead-bismuth corrosion, and its corrosion resistance was poor. The results showed that under the same corrosion conditions, no lead bismuth corrosion behavior was found on the surface of CaO-MgO-Al2O3-SiO2 (CMAS) glass-ceramic, while there was a corrosion layer with a thickness of about 10 μm on the surface of Li2O-ZnO-SiO2 (LZS) glass-ceramic, indicating that the lead bismuth corrosion resistance of CMAS glass ceramics was significantly better than that of LZS glass ceramics.