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SOLVING SYSTEMS OF PHASELESS EQUATIONS VIA RIEMANNIAN OPTIMIZATION WITH OPTIMAL SAMPLING COMPLEXITY

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Journal of Computational Mathematics 2024年第3期42卷 755-783页

作者： Jianfeng Cai ke wei Department of Mathematics Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong SARChina School of Data Science Fudan UniversityShanghaiChina

A Riemannian gradient descent algorithm and a truncated variant are presented to solve systems of phaseless equations|Ax|^(2)=*** algorithms are developed by exploiting the inherent low rank structure of the problem based on the embedded manifold of rank-1 positive semidefinite *** recovery guarantee has been established for the truncated variant,showing that the algorithm is able to achieve successful recovery when the number of equations is proportional to the number of *** key ingredients in the analysis are the restricted well conditioned property and the restricted weak correlation property of the associated truncated linear *** evaluations show that our algorithms are competitive with other state-of-the-art first order nonconvex approaches with provable guarantees.

关键词： Phaseless equations Riemannian gradient descent Manifold of rank-1 and positive semidefinite matrices Optimal sampling complexity

Determination of Water Sorption in Freestanding Epoxy Film by Capacitance Method Using EIS

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Journal of Materials Science & Technology 2006年第1期22卷 108-112页

作者： Yinghua wei Lixin ZHANG wei ke State key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Electrochemical impedance spectra （EIS） technique was adopted to evaluate the water sorption behaviour of an epoxy freestanding film in a 0.5 mol/L sodium chloride solution at 20℃. The methods for obtaining the capacitance data from EIS data were compared. The Brasher-Kingsbury （BK） and corresponding modified version （Modi-BK） models were used to calculate the water uptake in film and the gravimetric results were presented for comparisons. According to the discussion of the discrepancy of water content in film obtained from two models, a new method was proposed to indicate the organic film structure.

关键词： Epoxy Capacitance Water sorption EIS

Photon Radiation Induced by Multiple Parton Rescattering in Deeply Inelastic Scattering

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Chinese Physics Letters 2003年第5期20卷 639-642页

作者： ZHANGBen-wei WANGEn-ke InstituteofParticlePhysics HuazhongNormalUniversityWuhan430079

Photon radiation induced by multiple parton rescattering and corresponding parton energy loss in eA deeply inelastic scattering are investigated by using the generalized factorization of higher twist parton distributions beyond the helicity amplitude approximation. It turns out that the behaviour of the nuclear size dependence of the parton energy loss is different in the photon and gluon radiation cases. The parton energy loss due to photon radiation depends linearly, instead of quadratically, on nuclear size due to gluon radiation.

关键词：粒子物理散射光子辐射能量损失胶子

In Situ Corrosion Monitoring of Mild Steel in a Simulated Tidal Zone without Marine Fouling Attachment by Electrochemical Impedance Spectroscopy

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Journal of Materials Science & Technology 2014年第10期30卷 1043-1050页

作者： Xin Mu Jie wei Junhua Dong wei ke State key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of Sciences

The corrosion behaviors of the isolated short and vertical long scale Q235B steel in a simulated tidal zone were studied by electrochemical impedance spectroscopy （EIS） monitoring and corrosion weight loss calculation in an experimental indoor simulating trough. The results show that the corrosion rate of the isolated short scale Q235B steel in the tidal zone acquired by the EIS agrees with the corrosion weight loss result. The corrosion rates of the short scale steel are in the order of middle tidal zone 〉 the central zone between the middle tidal zone and low tidal zone 〉 high tidal zone 〉 low tidal zone. The fastest corrosion rate in the middle tidal zone is attributed to the longest wet time in a tidal cycle. According to the comparison of corrosion weight loss between the vertical long scale and isolated short scale specimens, the corrosion rate of vertical long scale specimens of Q235B steel is lower than that of the isolated short scale specimens in the tidal zone, but the result is contrary in the immersion zone.

关键词： Laboratory simulation Tidal corrosion Mild steel Electrochemical impedance spectroscopy weight loss

Corrosion of Artificial Aged Magnesium Alloy AZ80 in 3.5 wt pct NaCl Solutions

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Journal of Materials Science & Technology 2007年第3期23卷 353-358页

作者： Rongchang ZENG Enhou HAN wei ke Environmental Corrosion Center Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science Chongqing Institute of Technology Chongqing 400050 China

The corrosion morphologies of aged magnesium alloy AZ80 were investigated by immersion corrosion tests, scanning electron microscopy （SEM）, electrochemical measurement. The T5 heat treatment was carried out in a vacuum furnace, holding for 16 h at 177℃, and then cooling in air. The results showed intergranular corrosion （IGC） occurred as an aged AZ80 sample was immersed in 3.5 wt pct NaCI aqueous solution for 1 h and the narrow path attack progressed predominantly along the bulk β phase in the grain boundaries or took place in the eutectic areas. IGC was attributed to the network distribution of β phase along the grain boundaries, the depleted aluminium in the precipitation areas and the breakdown potential.

关键词： Magnesium alloy AZ80 Intergranular corrosion NaCl solution

Estimating water deficit and its uncertainties in water-scarce area using integrated modeling approach

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Water Science and Engineering 2012年第4期5卷 450-463页

作者： Shou-ke wei Eawag the Swiss Federal Institute of Aquatic Science and Technology Department of Forest Resources Management University of British Columbia Emodlogic Technology Inc.

Accurate assessment of water deficit and related uncertainties in water-scarce areas is strategically important in various fields of water resources management. This study developed a hybrid approach integrating conceptual water balance model and econometric regression to estimate water shortage and its related uncertainties in water-scarce areas. This hybrid approach was used to assess the agricultural water deficit of Beijing, an extremely water-scarce area in China. A predictive model of agricultural water demand was developed using the stepwise multiple regression method, and was validated by comparing the predicted values with observed data. Scenario analysis was employed to investigate the uncertainties of agricultural water shortage and agricultural water demand. This modeling approach can assist water administration in creating sustainable water allocation strategies in water-scarce areas.

关键词： water deficit hybrid model conceptual water balance model stepwise multipleregression method uncertainty Beo'ing

Effects of Cl- Ions on the Corrosion Behaviour of Low Alloy Steel in Deaerated Bicarbonate Solutions

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Journal of Materials Science & Technology 2016年第4期32卷 341-348页

作者： Yunfei Lu Junhua Dong wei ke Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Wuhan the Second Ship Design and Research Institute Wuhan 430064 China

The effect of Cl- ions on corrosion evolution of NiCu low alloy steel during immersion tests （up to 70 days） in deaerated 0.05 mol/L bicarbonate solutions was investigated by in-situ electrochemical mea- surements combined with X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electron probe microanalysis （EPMA） characterisations. The results showed that due to the acceleration of substrate dis- solution in the presence of Cl, corrosion of NiCu low alloy steel underwent only two stages, i.e., a quick oxidation process followed by a final metastable passive state, without the initial slow anodic dissolu- tion as observed in the Cl--free bicarbonate solution. The main components of the formed rust layer in the Cl--free bicarbonate solution were α-FeOOH and Fe3O4, while apart from α-FeOOH, Fe6（OH）12CO3 was found evident instead of Fe3O4 in the Cl-containing solution. Metastable pits were only found in the Cl-containing solution where Cl- accumulated after the immersion test, confirming the attack of Cl on the substrate after penetrating the formed corrosion product layer.

关键词： Low alloy steelCorrosion behaviourCI-Open circuit potentialElectrochemical impedance spectroscopy(EIS)

Corrosion Evolution of Low Alloy Steel in Deaerated Bicarbonate Solutions

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Journal of Materials Science & Technology 2015年第10期31卷 1047-1058页

作者： Yunfei Lu Junhua Dong wei ke Institute of Metal Research Chinese Academy of Sciences

Corrosion evolution during immersion tests （up to 43 days） of NiCu steel in deaerated 0.1 mol/L bicarbonate solutions was investigated by electrochemical measurements, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Results show that NiCu steel transformed from the anodic dissolution in the early stage of immersion to a metastable passive state in the final stage as the open-circuit potential value shifted positively, which was aroused by the precipitation of corrosion products. This process was mainly promoted by the trace amount of oxygen. Simultaneously, dominant cathodic reaction transformed from the hydrogen evolution in early stage to reduction processes of corrosion products in later stages. Possible corrosion processes were discussed with the assistance of a corresponding Pourbaix diagram.

关键词： Low alloy steelCorrosion behaviour Potential Corrosion product film Potentiodynamic polarization Electrochemical impedance spectroscopy(EIS)

Pitch control strategy before the rated power for variable speed wind turbines at high altitudes

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Journal of Hydrodynamics 2019年第2期31卷 379-388页

作者： Ming-wei Ge wei-ming ke Hong-xia Chen School of Renewable Energy North China Electric Power UniversityBeijingl 02206China School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijing 102206China

The wind turbines in the world's highest wind farm with an altitude of over 4 000 m in Naqu county of China were put into operation in *** with the wind turbines at lower altitudes,the rated wind speed of these wind turbines are much larger,and the corresponding tip-speed ratio at the rated power reduces significantly due to the lower air ***,the power coefficient at the point of the rated power is decreased to a rather low *** improve the performance of the wind turbines at very high altitudes,this paper proposes a new pitch control strategy for variable speed wind turbines at the constant-speed phase,especially at the rated-speed phase before the rated power is *** is shown that the new pitch control strategy works very well for the wind farms at very high altitude and with low air density,with the catch of the wind energy enhaneed and the aerodynamic loads significantly reduced.

关键词： Wind turbine pitch control strategy high altitudes