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In situ investigation of atmospheric corrosion behavior of PCB-ENIG under adsorbed thin electrolyte layer

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Transactions of Nonferrous Metals Society of China 2016年第4期26卷 1146-1154页

作者：易盼肖葵丁康康李刚董超芳李晓刚北京科技大学腐蚀与防护中心北京100083 中国船舶重工集团公司第七二五研究所海洋腐蚀与防护国家重点实验室青岛266101 中国科学院宁波材料技术与工程研究所宁波315201

The effects of relative humidity (RH) on a printed circuit board finished with electroless nickel immersion gold (PCB-ENIG) under an adsorbed thin electrolyte layer (ATEL) were investigated in situ via the measurement of cathodic polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to clearly elaborate the corrosion behavior of PCB-ENIG in the atmospheric environment. Results indicated that the cathodic process of PCB-ENIG under ATEL was dominated by the reduction of dissolved oxygen, corrosion products, and H2O. The cathodic current density of PCB-ENIG increased progressively with increasing RH. Moreover, its cathodic current density in the solution was greater than that under ATEL. This result demonstrated that the diffusion process was not the controlling step during the limiting reduction of cathodic oxygen. When the polarization potentials were located in a more negative region, the cathodic polarization current density gradually decreased under 75% and 85% RH. Notably, the anodic process became the controlling step in the extremely thin liquid film during the remainder of the experiment.

关键词： electronic materials adsorbed thin electrolyte layer cathodic polarization curve electrochemical impedance spectroscopy relative humidity

Electrochemical migration behavior and mechanism of PCB-ImAg and PCB-HASL under adsorbed thin liquid films

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Transactions of Nonferrous Metals Society of China 2015年第7期25卷 2446-2457页

作者：丁康康李晓刚肖葵董超芳张凯赵瑞涛北京科技大学腐蚀与防护中心北京100083

The electrochemical migration（ECM） behavior and mechanism of immersion silver processing circuit board（PCB-ImAg）and hot air solder leveling circuit board（PCB-HASL） under the 0.1 mol/L Na2SO4 absorbed thin liquid films with different thicknesses were investigated using stereo microscopy and scanning electron microscopy（SEM）.Meanwhile,the corrosion tendency and kinetics rule of metal plates after bias application were analyzed with the aid of electrochemical impedance spectroscopy（EIS）and scanning Kelvin probe（SKP）.Results showed that under different humidity conditions,the amount of migrating corrosion products of silver for PCB-ImAg was limited,while on PCB-HASL both copper dendrites and precipitates such as sulfate and metal oxides of copper/tin were found under a high humidity condition（exceeding 85%）.SKP results indicated that the cathode plate of two kinds of PCB materials had a higher corrosion tendency after bias *** ECM model involving multi-metal reactions was proposed and the differences of ECM behaviors for two kinds of PCB materials were compared.

关键词： immersion silver processing circuit board(PCB-ImAg) hot air solder leveling circuit board(PCB-HASL) electrochemical migration electrical bias absorbed thin liquid film

AAV-mediated expression of p65shRNA and bone morphogenetic protein 4 synergistically enhances chondrocyte regeneration

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中国组织工程研究 2025年第17期29卷 3537-3547页

作者： Yu Yangyi Song Zhuoyue Lian Qiang ding kang Li Guangheng Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration Division of Adult Joint Reconstruction and Sports MedicineDepartment of Orthopedic SurgeryShenzhen People’s Hospital(The Second Clinical Medical College Jinan UniversityThe First Affiliated HospitalSouthern University of Science and Technology)Shenzhen 518020Guangdong ProvinceChina Department of Orthopedics Zhengzhou Orthopedics HospitalZhengzhou 450000Henan ProvinceChina Department of Orthopedics Shenzhen Pingle Orthopedics HospitalShenzhen 518000Guangdong ProvinceChina

BACKGROUND:Adeno-associated virus(AAV)gene therapy has been proven to be reliable and safe for the treatment of osteoarthritis in recent ***,given the complexity of osteoarthritis pathogenesis,single gene manipulation for the treatment of osteoarthritis may not produce satisfactory *** studies have shown that nuclear factorκB could promote the inflammatory pathway in osteoarthritic chondrocytes,and bone morphogenetic protein 4(BMP4)could promote cartilage ***:To test whether combined application of AAV-p65shRNA and AAV-BMP4 will yield the synergistic effect on chondrocytes regeneration and osteoarthritis ***:Viral particles containing AAV-p65-shRNA and AAV-BMP4 were *** efficacy in inhibiting inflammation in chondrocytes and promoting chondrogenesis was assessed in vitro and in vivo by transfecting AAV-p65-shRNA or AAV-BMP4 into *** experiments were divided into five groups:PBS group;osteoarthritis group;AAV-BMP4 group;AAV-p65shRNA group;and BMP4-p65shRNA 1:1 *** were collected at 4,12,and 24 weeks *** staining,including safranin O and Alcian blue,was applied after collecting articular ***,the optimal ratio between the two types of transfected viral particles was further investigated to improve the chondrogenic potential of mixed cells in *** AND CONCLUSION:The combined application of AAV-p65shRNA and AAV-BMP4 together showed a synergistic effect on cartilage regeneration and osteoarthritis *** cells transfected with AAV-p65shRNA and AAV-BMP4 at a 1:1 ratio produced the most extracellular matrix synthesis(P<0.05).In vivo results also revealed that the combination of the two viruses had the highest regenerative potential for osteoarthritic cartilage(P<0.05).In the present study,we also discovered that the combined therapy had the maximum effect when the two viruses were administered in equal *** either p65shRNA or BMP4

关键词： osteoarthritis adeno-associated virus bone morphogenetic protein 4 p65-short hairpin RNA gene therapy short hairpin RNA transforming growth factor-β1 extracellular matrix articular cartilage chondrocytes.

Anti-Noise Performance of the FT Continuous Zoom Analysis Method for Discrete Spectrum

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Chinese Journal of Mechanical Engineering 2010年第6期23卷 774-779页

作者： LINHuibin ding kang XU Chuanyan School of Mechanical and Automotive Engineering South China University of Technology Guangzhou 510640 China Guangdong Key Lab for Automotive Engineering Guangzhou 510640 China

As a discrete spectrum correction method, the Fourier transform （FT） continuous zoom analysis method is widely used in vibration signal analysis, but little effort had been made on this method＇s anti-noise performance. It is widely believed that the analysis accuracy of the method can be substantially improved by increasing the zoom multiple, however, with the zoom multiple increases, the frequency estimation accuracy may decline sometimes in practices. Aiming at the problems above, this paper analyzes the sources of frequency estimation error when a harmonic signal mixed with and without noise is processed using the FT continuous zoom analysis. According to the characteristics that the local maximum of the zoom spectrum may be wrongly selected when the signal is corrupted with noise, the number of wrongly selected spectrum lines is deduced under different signal-to-noise ratio and local zoom multiple, and then the maximum frequency estimation error is given accordingly. The validity of the presented analysis is confirmed by simulations results. The frequency estimation accuracy of this method will not improve any more under the influence of noise, and there is a best zoom multiple, when the zoom multiple is larger than the best zoom multiple; the maximum frequency estimation error will fluctuate back and forth. The best zoom multiple curves under different signal-to-noise ratios given provide a theoretical basis for the choice of the appropriate zoom multiples of the FT continuous zoom analysis method in engineering applications.

关键词： spectrum spectrum correction zoom analysis anti-noise performance

Prescribed time control based on the periodic delayed sliding mode surface without singularities

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Science China(Information Sciences) 2024年第7期67卷 256-270页

作者： Bin ZHOU Yi ding kang-kang ZHANG Guang-Ren DUAN Center for Control Theory and Guidance Technology Harbin Institute of Technology

In this paper, nonsingular prescribed-time control is studied based on periodic delayed sliding mode surfaces. Different from the existing sliding mode control, where either singularity problems may appear or the convergence time depends on the initial state, the proposed sliding mode control approaches can achieve prescribed-time convergence without singularity. The proposed nonsingular sliding mode control approaches can be applied to both second-order and high-order nonlinear systems with prescribed-time convergence. As applications of the proposed sliding mode control approaches, the control of hypersonic vehicle systems is revisited. Numerical simulations on the nonlinear model of the hypersonic vehicle system show the effectiveness of the proposed methods.

关键词： prescribed-time control smooth periodic delayed feedback sliding mode control high-order nonlinear systems hypersonic vehicle systems

Preparation and Arc Breakdown Behavior of Nanocrystalline W-Cu Electrical Contact Materials

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Journal of Materials Science & Technology 2005年第6期21卷 875-878页

作者： Wenge CHEN Zhanying kang Bingjun ding School of Materials Science and Engineering Xi'an University of Technology Xi'an 710048 China Department of Materials Physics Xi'an Jiaotong University Xi'an 710049 China

Nanostructured （NS） W-Cu composite powder was prepared by mechanical alloying （MA）, and nanostructured bulk of W-Cu contact material was fabricated by hot pressed sintering in an electrical vacuum furnace. The microstructure, electric conductivity, hardness, breakdown voltage and arcing time of NS W-Cu alloys were measured and compared to conventional W-Cu alloys prepared by powder metallurgy. The results show that microstructural refinement and uniformity can improve the breakdown behavior, the electric arc stability and the arc extinction ability of nanostructured W-Cu contacts materials. Also, the nanostructured W-Cu contact material shows the characteristic of spreading electric arcs, which is of benefit to electric arc erosion.

关键词： Nanostructured materials W-Cu alloy Electrical breakdown Arc

Review of modeling and control strategy of thermostatically controlled loads for virtual energy storage system

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Protection and Control of Modern Power Systems 2019年第1期4卷 309-321页

作者： kang Xie Hongxun Hui Yi ding Electrical Engineering College of Zhejiang University Hangzhou310027China

The increasing penetration of renewable energy sources (RESs) brings more power generation fluctuations into power systems, which puts forward higher requirement on the regulation capacities for maintaining the power balance between supply and demand. In addition to traditional generators for providing regulation capacities, the progressed information and communication technologies enable an alternative method by controlling flexible loads, especially thermostatically controlled loads (TCLs) for regulation services. This paper investigates the modeling and control strategies of aggregated TCLs as the virtual energy storage system (VESS) for demand response. First, TCLs are modeled as VESSs and compared with the traditional energy storage system (ESS) to analyze their characteristic differences. Then, the control strategies of VESS are investigated in microgrid and main grid aspects, respectively. It shows that VESS control strategies can play important roles in frequency regulation and voltage regulation for power systems’ stability. Finally, future research directions of VESS are prospected, including the schedulable potential evaluation, modeling of TCLs, hierarchical control strategies of VESS considering ESSs and RESs and reliability and fast response in frequency control for VESS.

关键词： Thermostatically controlled loads(TCLs) Virtual energy storage system(VESS) Modeling method Control strategy

Coupling mechanism of mathematical models for sediment transport based on characteristic theory

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Science China(Technological Sciences) 2016年第11期59卷 1696-1706页

作者： ding Yun LI ZuiSen ZHONG DeYu kang YanPing State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310008 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Jiangsu Hydraulic Research Institute Nanjing 210017 China

This paper aims to explore the coupling mechanism between flow movement, sediment transport and riverbed evolution in currently widely used mathematical models for sediment transport. Based on characteristic theory, analytic forms of eigenvalues,eigenvectors and characteristic relationships of total-sediment transport model, bed-load transport model and suspenedload transport model were derived, respectively. The singular perturbation technology was implemented to obtain the asymptotic solutions to different families of eigenvalues. The results indicate that, interactions between motion variables were explicitly coupled in the characteristics of total-sediment transport model and bed-load transport model. Further qualitative and quantitative analysis demonstrates that high sediment transport intensity and significant riverbed change will inevitably affect the property of flow movement. In the process of deposition, sediment-laden flow will move faster when sediment transport intensity becomes stronger. In contrast, the wave of flow will propagate at slower speed as erosion intensity becomes *** most existing suspended-load transport models, however, the characteristics are decoupled as the interactions between motion variables cannot be integrally illustrated in eigenvalues, eigenvectors and characteristic relationship.

关键词： coupling mechanism mathematical models sediment transport characteristics eigenvalues

Analysis of energy pile groups subjected to non-uniform thermal loadings

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Underground Space 2023年第2期9卷 91-104页

作者： kang Fei Shi-Jia ding Hong-Yu Qin Department of Civil Engineering Yangzhou UniversityYangzhouJiangsu 225127China College of Science and Engineering Flinders UniversityAdelaide SA5042Australia

Sequentially coupled thermal-stress finite element analyses were performed to investigate the mechanical behaviors of an energy pile group subjected to non-uniform thermal *** group effect was highlighted by comparing the thermo-mechanical responses with those of the single pile *** to the thermal interactions between piles,the group piles’temperatures were higher than that of the isolated single *** only part of the piles served as heat exchangers,i.e.,the pile group was thermal loaded unevenly,there were dif-ferential deformations between the heated and the non-heated *** to the pile-raft-pile interaction,the axial forces of the piles chan-ged *** location of the heated pile had an important influence on the thermally induced axial force,while the effect of the soil’s coefficient of thermal expansion was not *** by the numerical result,a simplified method was proposed to capture the main characteristics of energy pile groups and to facilitate the *** proposed method was developed in the framework of the traditional load transfer approach,and the pile-raft-pile interaction was *** applying different temperature increments to dif-ferent piles,the non-uniform thermal loading was *** proposed method was verified by comparing with the finite element anal-ysis results and the data collected from the literature.

关键词： Energy pile group Non-uniform thermal loading Group effect Thermo-mechanical response