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Efficient Identification of water conveyance tunnels siltation based on ensemble deep learning

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Frontiers of Structural and Civil Engineering 2022年第5期16卷 564-575页

作者： Xinbin WU Junjie Li linlin WANG Faculty of Infrastructure Engineering Dalian University of TechnologyDalian 116024China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China

The inspection of water conveyance tunnels plays an important role in water diversion projects.Siltation is an essential factor threatening the safety of water conveyance tunnels.Accurate and efficient identification of such siltation can reduce risks and enhance safety and reliability of these projects.The remotely operated vehicle(ROV)can detect such siltation.However,it needs to improve its intelligent recognition of image data it obtains.This paper introduces the idea of ensemble deep learning.Based on the VGG16 network,a compact convolutional neural network(CNN)is designed as a primary learner,called Silt-net,which is used to identify the siltation images.At the same time,the fully-connected network is applied as the meta-learner,and stacking ensemble learning is combined with the outputs of the primary classifiers to obtain satisfactory classification results.Finally,several evaluation metrics are used to measure the performance of the proposed method.The experimental results on the siltation dataset show that the classification accuracy of the proposed method reaches 97.2%,which is far better than the accuracy of other classifiers.Furthermore,the proposed method can weigh the accuracy and model complexity on a platform with limited computing resources.

关键词： water conveyance tunnels siltation images remotely operated vehicles deep learning ensemble learning computer vision

Recent progress on sulfide infrared nonlinear optical materials with large SHG response and wide band gap

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Chinese Journal of Structural Chemistry 2023年第1期42卷 22-29页

作者： linan Wang Qi Sun Junjie Li Research Center for Crystal Materials CAS Key Laboratory of Functional Materials and Devices for Special EnvironmentsXinjiang Technical Institute of Physics&ChemistryCASUrumqi830011China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China

As the core device of all-solid-state laser,infrared(IR)nonlinear optical(NLO)material plays a critical role in exploring new coherent lights by frequency conversion technologies,which are widely used in noninvasive medical diagnostics,spectroscopy,environmental monitoring and long-distance laser communication.To satisfy the growing demand of current laser technology in IR regions,high performance NLO materials with large second-harmonic generation(SHG)response,high laser-induced damage threshold(liDT)and wide transparency range are highly expected.Recently,numerous efforts and advances have been achieved in sulfide system.This review highlights the progress of high-performance sulfide IR NLO materials with a good balance between strong SHG response(≥1.0×AgGaS_(2))and wide band gap(≥3.0 eV)since 2018.The chemical synthesis,crystal structure,optical properties and structure-property relationship of 13 high performance metal sulfide IR NLO materials are summarized and reviewed in detail.Finally,the potential opportunities and challenges in IR NLO materials are discussed.

关键词： Infrared NLO material s Sulfide Structure-property relationship Optical property

Fault diagnosis for gearboxes based on Fourier decomposition method and resonance demodulation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第5期24卷 404-418页

作者： Shuiguang TONG Zilong FU Zheming TONG Junjie Li Feiyun CONG State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China School of Mechanical Engineering Zhejiang UniversityHangzhou 310027China

Condition monitoring and fault diagnosis of gearboxes play an important role in the maintenance of mechanical systems.The vibration signal of gearboxes is characterized by complex spectral structure and strong time variability,which brings challenges to fault feature extraction.To address this issue,a new demodulation technique,based on the Fourier decomposition method and resonance demodulation,is proposed to extract fault-related information.First,the Fourier decomposition method decomposes the vibration signal into Fourier intrinsic band functions(FIBFs)adaptively in the frequency domain.Then,the original signal is segmented into short-time vectors to construct double-row matrices and the maximum singular value ratio method is employed to estimate the resonance frequency.Then,the resonance frequency is used as a criterion to guide the selection of the most relevant FIBF for demodulation analysis.Finally,for the optimal FIBF,envelope demodulation is conducted to identify the fault characteristic frequency.The main contributions are that the proposed method describes how to obtain the resonance frequency effectively and how to select the optimal FIBF after decomposition in order to extract the fault characteristic frequency.Both numerical and experimental studies are conducted to investigate the performance of the proposed method.It is demonstrated that the proposed method can effectively demodulate the fault information from the original signal.

关键词： Fourier decomposition method Singular value ratio Resonance frequency Envelope demodulation Fault diagnosis

PdPtBi networked nanowires derived from Pd nanosheets as efficient catalysts for ethanol oxidation

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Nano Research 2023年第7期16卷 9125-9131页

作者： Ningkang Qian liang Ji Junjie Li Hui Zhang Deren Yang State Key Laboratory of Silicon Materials and School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou 311200China

Direct ethanol fuel cells(DEFCs)have received increasing attention as one of the most promising energy conversion devices.However,developing catalysts with high activity,long durability and strong anti-poisoning ability for ethanol oxidation is still challenging.Here,using Pd nanosheets as sacrificial templates,we have successfully synthesized PdPtBi networked nanowires(NWs)to improve the activity and stability for ethanol oxidation reaction(EOR)due to the addition of Bi.Density functional theory(DFT)calculations demonstrated the downshift of d-band center of Pd,which is beneficial to suppress CO poisoning and boost reaction kinetics for EOR.Impressively,the PdPtBi networked NWs exhibited the highest activity(11.08 A·mg_(Pd+Pt)^(-1)and 92.52 mA·cm^(-2))with an enhancement of 4.4 and 17.5 times relative to those of Pd/C,respectively and best stability with a 47.2%left versus only a 5.8%left for Pd/C of mass activity after 3,600 s towards EOR.This work deepens the understanding of controllable preparation of networked NWs and provides an effective strategy to design advanced catalysts with high activity and stability.

关键词： trimetallic palladium platinum network nanowire ethanol oxidation

Review on charging model of sand particles due to collisions

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Theoretical & Applied Mechanics Letters 2020年第4期10卷 276-285页

作者： li Xie Junjie Li Yakui liu College of Civil Engineering and Mechanics Lanzhou UniversityLanzhou 730000China Key Laboratory of Western Disaster and Environmental Mechanics Attached on Education Ministry of ChinaLanzhou UniversityLanzhou 730000China

In this paper, the models describing the charge transfer between two sand particles due to collisions are reviewed. By comparing the experimental results and the calculated results by the models carried on an individual particle due to a single collision, it indicates the Mosaic model is more reasonable to describe the collision charging mechanism. The Mosaic model cannot only describe the dependence of the collision charges on the relative collision speed and the particle size, but also reveal the relationship between the collision charges with the environmental temperature, the relative humidity and the material parameters, e.g., the absorption energy. Based on the Mosaic model, the model to describe the charges transfer due to multiple collisions is also developed, which can be used to calculate the charges carried by sand particles due to multiple collisions in the wind blown sand flux.

关键词： Charging model Sand particles Contact electrification

On Ti6Al4V Microsegregation in Electron Beam Additive Manufacturing with Multiphase-Field Simulation Coupled with Thermodynamic Data

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 425-438页

作者： Yujian Wang Shuo Chu Zhijun Wang Junjie Li Jincheng Wang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

Electron beam additive manufacturing is an effective method for the fabrication of complex metallic components.With rapid solidification,the characteristics of microsegregation within the interdendritic region are interesting and important for the subsequent phase transformation and final mechanical properties.However,in view of the microsecond lifetime and the small length scale of the molten pool,experimentally investigating microsegregation is challenging,even with electron probe micro-analysis.In this study,a multiphase-field model coupled with the real thermodynamic data of Ti6Al4V alloy was successfully developed and applied to simulate the rapid solidification of columnarβgrains via electron beam additive manufacturing.The thermal gradient(G)and cooling rate(R)were obtained from a 3D powder-scale multiphysics simulation and provided as inputs to a multiphase-field model.The eff ects of the electron beam process parameters and thermal conditions on the columnarβgrains were investigated.liquid films and droplets were observed to have solute enrichment in the intercellular region.The size of the liquid film increased at a lower scanning speed and energy power.Increasing the scanning speed and energy power refined the columnarβgrains and decreased the liquid film size.The extent of microsegregation considerably increased at lower energy power,whereas the change in scanning speed had little eff ect on the microsegregation.The results also indicate that solute vanadium results in significant solute trapping and microsegregation during the rapid solidification of the Ti6Al4V alloy.

关键词： Ti6Al4V alloy Microsegregation Electron beam additive manufacturing Multiphase-field model

Resilience-oriented Restoration Strategy by Offshore Wind Power Considering Risk

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CSEE Journal of Power and Energy Systems 2023年第6期9卷 2052-2065页

作者： junjie Rong Ming Zhou Gengyin li the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

Global climate changes have created intense naturaldisasters such as typhoons, which may cause serious damage topower systems. As an emerging renewable energy resource, offshore wind power has great potential in power systems resilienceenhancement with its rapid start-up capability and developmentof anti-typhoon technology. In this paper, a restoration strategyby offshore wind power considering risk is proposed to speedup the restoration process and enhance system resilience. Specifically, a failure risk model of an individual wind turbine andthen the whole wind farm is built for predicting severe weather’simpact, with focus on failure probability. Further, a quantificationmodel of resilience enhancement and risk cost, based on customerinterruption cost assessment method, is introduced. Then, a twostage optimized decision-making model is proposed to solve thescheme of offshore wind power and conventional power unitsin load restoration process. Case studies are undertaken on amodified IEEE RTS-79 system and results indicate the proposedrestoration strategy can shorten duration of restoration andreduce customers’ economic losses meanwhile ensuring systemsafety.

关键词： Load restoration offshore wind power optimized decision-making resilience enhancement risk

Platinum is essential in neoadjuvant treatment of triple-negative breast cancer: a network meta-analysis

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Cancer Biology & Medicine 2022年第5期19卷 742-754页

作者： Junjie Li li Chen Wei Tan Fang Qi Yang Zhang Zhonghua Wang Zhimin Shao Key Laboratory of Breast Cancer in Shanghai Department of Breast SurgeryFudan University Shanghai Cancer CenterShanghai 200032China Department of Oncology Shanghai Medical CollegeFudan UniversityShanghai 200032China Nottingham Clinical Trials Unit University of NottinghamNottingham NG72RDUK Academic Department Systematic Review Solutions LtdShanghai 201400China

Objective:This study aimed to assess the efficacy and safety of various neoadjuvant regimens for patients diagnosed with early-stage or locally advanced triple-negative breast cancer(TNBC).Methods:Medline,EMBASE,Cochrane library,and Web of Science were searched in May 2020 to identify randomized controlled trials(RCTs).Bayesian network meta-analysis(NMA)was performed(Registration:PROSPERO CRD42020223012).Results:A total of 35 RCTs involving 8,424 participants were reviewed,of which 22 RCTs with 5,203 patients were included in this NMA focusing on pathologic complete response(pCR).An anthracycline-taxane-based(AT)regimen combined with a platinum(ATPt)[odds ratio(OR)=2.04,95%credible interval(CrI):1.69,2.48]regimen,and a docetaxel regimen combined with a carboplatin(TCb;OR=2.16,95%CrI:1.20,3.91)regimen improved pCR beyond that with AT only.AT and ATPt combined with targeted therapy[including bevacizumab(Bev),veliparib,atezolizumab,or pembrolizumab]also improved pCR.Five RCTs included in this NMA reported serious adverse events(SAEs)or grade≥3 AEs.TCb was associated with fewer grade≥3 AEs than was AT(OR=0.66,95%CrI:0.23,1.72)alone.In contrast,ATPt,AT+Bev,ATPt+Bev,ATPt+veliparib,and ATPt+pembrolizumab were associated with more SAEs than was AT alone.Conclusions:In patients with TNBC,platinum-based neoadjuvant regimens ATPt and TCb increase pCR beyond that with AT alone,but TCb appears to be better tolerated than either AT or ATPt.Platinum-based regimens combined with targeted therapies(Bev,PARPi,and PD-1/PD-L1 inhibitor)also improve the pCR rate beyond that with AT alone,but this benefit is accompanied by greater toxicity.

关键词： Breast cancer triple negative neoadjuvant network meta-analysis

Water-oxygen interaction on marcasite(101)surface:DFT calculation

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International Journal of Mining Science and Technology 2022年第1期32卷 191-199页

作者： junjie Zhang Yuqiong li Jianhua Chen School of Resources Environment and MaterialsGuangxi UniversityNanning 530004China Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials Guangxi UniversityNanning 530004China

Marcasite(FeS2)is widespread in nature,its oxidation plays a vital role in acid mine drainage,mineral resource recovery,and photoelectric material applications.In this paper,the oxidation mechanism of marcasite has been studied for the first time using density functional theory(DFT).It is found that,unlike the oxidation of pyrite,the oxidation of marcasite merely occurs at surface S atoms.Under the coexistence of water and oxygen,S atoms around surface Fe atoms are replaced by O atoms.The surface S sites are initially oxidized to form S==O bonds,and continue to adsorb oxygen to gradually generate SO3^2-,SO4^2-species,and eventually FeSO4.In this process,H2O molecules participate in neither oxidation nor dissociation,and they are adsorbed on surface Fe sites in the form of molecules,i.e.,all O atoms in SO4^2-derive from oxygen rather than water molecules.

关键词： Marcasite Surface oxidation Adsorption Density functional theory