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A quantitative research on the level of disturbance to secondary signal ports of electronic voltage transformers under the operation of gas‐insulated switchgear

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High Voltage 2022年第1期7卷 165-175页

作者： Qi Wang chao Fu Fanwu chu Yue Tong Xiaozhou Wang Guoxiong Ye Xiong Wu Power Industry Electrical Equipment Quality Inspection and Testing Center China Electric Power Research InstituteWuhanChina

The collectors of electronic transformers has the problem of electromagnetic in-compatibility under the operation of disconnecting switches,which limits their wide application in smart *** evaluate the maximum level of disturbance that collectors are able to withstand in the stochastic process of switching operation,this work in-troduces a quantitative approach based on limited test measurements,which can quantify the level of disturbance in the signal acquisition ports of electronic voltage transformers(EVT)in different gas‐insulated switchgears(GIS).Based on large numbers of experi-mental statistical data of the true type simulation experimental platform,the Spearman rank correlation coefficient is used to prove that the amplitude of the disturbance voltage pulse at the secondary side port and the breakdown voltage between the primary side fracture approximately satisfy a linear ***,the quantile regression model is used to quantify and verify the maximum disturbance level of the secondary side ***,a solution is proposed to tackle the difficulty in obtaining the breakdown voltage at breaks in the GIS substation field applicatvion,under which the quantified maximum disturbance voltage deviation of secondary ports is only−4.34%by *** research work can further explore the practical value of the measured data in a few tests under GIS substation field conditions and provide references for the sub-sequent revision of EVT‐related standards.

关键词： disturbance operation electronic

Construction of upconversion fluoride/attapulgite nanocomposite for visible-light-driven photocatalytic nitrogen fixation

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Frontiers of Materials Science 2020年第4期14卷 469-480页

作者： Xuhua YE Xiangyu YAN Xini chu Shixiang ZUO Wenjie LIU Xiazhang LI chao YAO Advanced Catalysis and Green Manufacturing Collaborative Innovation Center Jiangsu Key Laboratory of Advanced Catalytic Materials and TechnologyChangzhou UniversityChangzhou 213164China Department of Materials Science and Engineering University of DelawareNewarkDE 19716USA

Developing photocatalysts with wide spectrum absorption and strong nitrogen activation is critical for nitrogen fixation under mild ***,one-dimensional natural clay attapulgite(ATP)supported YFg:Sm^3+were successfully synthesized via microwave hydrothermal method,and the composites were employed as the catalyst for photocatalytic nitrogen fixation under visible-light *** indicated that the production of ammonia reached as high as 41.2 mg·L^-1 within 3 h when the molar ratio of Sm^3+and the mass fraction of YF3:Sm^3+were *** enhanced fixation performance is mainly due to that the modified ATP fibber with abundant active sites and the doped fluoride with defective vacancy facilitate the adsorption and activation of ***,the upconversion property of YF3:Sm^3+increases the harvesting of visible-light energy,meanwhile the Z-scheme heterostructure built between YF:Sm^3+and modified ATP inhibits the recombination of charge carriers and retains high redox potentials for N2 reduction.

关键词： photocatalysis nitrogen fixation attapulgite upconversion Z-scheme

Microstructure Evolution and Phase Transformation of Ti–6.5Al–2Zr–Mo–V Alloy During Thermohydrogen Treatment

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Acta Metallurgica Sinica(English Letters) 2015年第4期28卷 505-513页

作者： Hong-chao Kou Han-Lei Zhang Yu-Dong chu Dong Huang Hai Nan Jin-Shan Li State Key Laboratory of Solidification Processing Northwestern Polytechnical University Beijing Institute of Aeronautical Materials

Thermohydrogen treatment （THT） is an effective way to refine microstructure and improve the mechanical properties of the titanium alloys. In the current work, as-cast Ti-6.5Al-2Zr-Mo-V alloy was hydrogenated with different hydrogen contents and processed solution aging. Accordingly, the microstructure evolution and phase transformation were analyzed. Results show that during solution aging, eutectoid decomposition occurs and the product is a mixture of coarse primaryα, fine eutectoid product and undecomposed βH. The size of primary α is closely dependent on the hydrogen content, and large primary α can be obtained at medium hydrogen content. Further, the influence of hydrogen content on the growth of primary α phase was revealed. The primary α is much fine, and the eutectoid product is relatively homo- geneous with 0.984 wt% H. After THT, the ultimate strength is beyond 1,100 MPa that has increased by 23.15% compared with that in as-cast state.

关键词： Titanium alloy Hydrogen Heat treatment Phase transformation Eutectoid decomposition Mechanical property

Remote Sensing Retrieval of Surface Suspended Sediment Concentration in the Yellow River Estuary

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Chinese Geographical Science 2017年第6期27卷 934-947页

作者： ZHAN chao YU Junbao WANG Qing LI Yunzhao ZHOU Di XING Qinghui chu Xiaojing Key Laboratory of Coastal Environmental Processes and Ecological Remediation Yantai Institute of Coastal Zone Research Chinese Academy of Sciences Yantai 264003 China The Institute of Coastal Ecology Ludong University Yantai 264025 China University of Chinese Academy of Sciences Beijing 100049 China

Accurate assessment of surface suspended sediment concentration （SSSC） in estuary is essential to address several important issues： erosion, water pollution, human health risks, etc. In this study, an empirical cubic retrieval model was developed for the retrieval of SSSC from Yellow River Estuary. Based on sediments and seawater collected from the Yellow River and southeastern Laizhou Bay, SSSC conditions were reproduced in the laboratory at increasing concentrations within a range common to field observations. Continu- ous spectrum measurements of the various SSSCs ranging from 1 to 5700 mg/1 were carried out using an AvaField-3 spectrometer. The results indicated the good correlation between water SSSC and spectral reflectance （Rrs） was obtained in the spectral range of 726-900 nm. At SSSC greater than 2700 mg/L, the 740-900 nm spectral range was less susceptible to the effects of spectral reflectance saturation and more suitable for retrieval of high sediment concentrations. The best correlations were obtained for the reflectance ratio of 820 nm to 490 nm. Informed by the correlation between Rrs and SSSC, a retrieval model was developed （R2 = 0.992）. The novel cubic model, which used the ratio of a near-infrared （NIR） band （740-900 nm） to a visible band （400-600 nm） as factors, provided robust quantifica- tion of high SSSC water samples. Two high SSSC centers, with an order of 103 mg/1, were found in the inversion results around the abandoned Diaokou River mouth, the present Yellow River mouth to the abandoned Qingshuigou River mouth. There was little sedi- ment exchange between the two high SSSC centers due to the directions of the residual currents and vertical mixing.

关键词： surface suspended sediment concentration (SSSC) water spectral reflectance cubic model quantitative remote sensinginversion Yellow River Estuary

Ultrafast Dynamics of Polythiophene with Phenyl Vinylene Branches Studied by Femtosecond Fluorescence Spectroscopy in Solution

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Chinese Physics Letters 2011年第11期28卷 228-231页

作者： chu Sai-Sai GAO chao WANG Shu-Feng GONG Qi-Huang State Key Laboratory for Mesoscopic Physics Department of PhysicsPeking UniversityBeijing 100871 Xi’an Modern Chemistry Research Institute Xi’an 710065

Two polythiophene based polymers,poly[(3-[2-[4-(2-ethyl-hexyloxy)-phenyl]-vinyl]-thiophene)-co-thiophene](PT1)and poly(3-[2-[4-(2-ethyl-hexyloxy)-phenyl]-vinyl]-thiophene)(PT2),are synthesized and investigated by static,picosecond fluorescence spectroscopies and the femtosecond up-conversion technique in *** with pristine poly(3-hexylthiophene)(P3HT),PT1 and PT2,in which the main chains are decorated with phenyl vinylene present a‘camel back’structure in the absorption *** vinylene side chains induce a new process of charge transfer,chain twisting motion and defect-induced fluorescence quenching at time scales of 1 ps,10 ps and 150 ps,respectively.

关键词： solution spectra vinyl

Global seaweed farming and processing in the past 20 years

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Food Production, Processing and Nutrition 2022年第1期4卷 289-318页

作者： Lizhu Zhang Wei Liao Yajun Huang Yuxi Wen Yaoyao chu chao Zhao College of Food Science Fujian Agriculture and Forestry UniversityFuzhou 350002China College of Marine Sciences Fujian Agriculture and Forestry UniversityFuzhou 350002China Key Laboratory of Marine Biotechnology of Fujian Province Institute of OceanologyFujian Agriculture and Forestry UniversityFuzhouChina

Seaweed has emerged as one of the most promising resources due to its remarkable adaptability, short development period, and resource sustainability. It is an effective breakthrough to alleviate future resource crises. Algal resources have reached a high stage of growth in the past years due to the increased output and demand for seaweed worldwide. Several aspects global seaweed farming production and processing over the last 20 years are reviewed, such as the latest situation and approaches of seaweed farming. Research progress and production trend of various seaweed application are discussed. Besides, the challenges faced by seaweed farming and processing are also analyzed, and the related countermeasures are proposed, which can provide advice for seaweed farming and processing. The primary products, extraction and application, or waste utilization of seaweed would bring greater benefits with the continuous development and improvement of applications in various fields.

关键词： Algal farming Algal processing Breeding technology Extraction technology

Dynamic characteristics of large permanent magnet direct‐drive generators considering electromagnetic–structural coupling effects

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International Journal of Mechanical System Dynamics 2023年第1期3卷 25-38页

作者： Qinkai Han Xueping Xu Zhihong Zhang Yifeng Yan chao Peng Fulei chu Department of Mechanical Engineering The State Key Laboratory of TribologyTsinghua UniversityBeijingChina School of Instrumentation and Optoelectronic Engineering Research Institute for Frontier ScienceBeihang UniversityBeijingChina Institute of Research Center Xinjiang Goldwind Science and Technology Co.Ltd.XinjiangChina

Dynamic characteristics of large permanent magnet direct‐drive generators(PMDGs)considering electromagnetic–structural coupling effects are analyzed in this *** the conformal mapping method,the scalar magnetic potential of the air gap magnetic field considering the slot effect is *** the basis of the discrete current element and magnetic equivalent circuit model,the local magnetic saturation effect of the stator and rotor is quantitatively simulated and the air gap magnetic field intensity distribution is obtained via numerical simulation.A series of uniformly distributed equivalent electromagnetic springs are introduced to develop an electromagnetic–structural coupling finite element PMDG *** proposed air gap field analysis method is verified by the finite element analysis *** the basis of the test platform for the Goldwind 1.5MW PMDG,both modal and dynamic response tests for the stator/rotor coupling system are conducted,and the results are compared with the natural frequencies,mode shapes,and vibration responses obtained using the numerical *** effects of the air gap length and rotor speed on the natural frequencies of the coupling system are *** proposed model has the potential to accurately evaluate the PMDG vibration energy,avoiding resonance points,and maintaining stable operations of the unit.

关键词： permanent magnet direct‐drive generators dynamic characteristics electromagnetic–structural coupling effects conformal mapping magnetic equivalent circuit model electromagnetic springs

Subgrid-Scale Fluid Statistics along the Inertial Particle Trajectory in Isotropic Turbulence

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Chinese Physics Letters 2012年第9期29卷 93-96页

作者： YI chao LI Jing LIU Zhao-Hui WANG Lin ZHENG chu-Guang State Key Laboratory of Coal Combustion Huazhong University of Science and TechnologyWuhan 430074

Fluctuations of sub-grid scale(SGS)velocity and its influence on the motion of particles are important issues for large eddy simulation(LES)of gas-particle *** obtain the SGS statistics from the direct numerical simulation(DNS)data of homogeneous isotropic turbulent flow,which is filtered by the top filter in physical *** result shows that the SGS kinetic energy seen by particles reach a minimum value when the Stokes number St closes to ***,the turning point shifts towards a larger St as the filter width *** from that observed in DNS,the Lagrangian integral time scale is larger than the Eulerian integral time scale in *** small particles,the Lagrangian timescale of SGS fluid seen by particle is very close to that of the fluid *** particles which are large enough,it approaches the Eulerian timescale of SGS *** the intermediate particles,the predicted curve of SGS fluid timescale seen by particle varies with St and its variation is non-monotonic.

关键词： space. particle filtered

Influence of zinc on electrochemical discharge activity of Mg-6%Al-5%Pb anode

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Journal of Central South University 2012年第1期19卷 9-16页

作者： WANG Nai-guang WANG Ri-chu PENG chao-qun FENG Yan Science and Engineering Central South UniversityChangsha 410083China

Mg-6%Al-5%Pb(mass fraction) anodes with different contents of zinc were prepared by melting and *** electrochemical discharge behavior of these anodes in 3.5% NaCl solutions was investigated by galvanostatic test and electrochemical impedance spectroscopy(EIS).The microstructures and the corroded surfaces of these anodes were studied by scanning electron microscopy(SEM) and emission spectrum analysis(ESA).The phase structures and the corrosion products of the anodes were analyzed by X-ray diffraction(XRD).The results show that zinc promotes the grain refinement of Mg-6%Al-5%Pb anode and makes the average discharge potential of Mg-6%Al-5%Pb anode more negative during galvanostatic ***-6%Al-5%Pb anode with the addition of 1%(mass fraction) zinc has the best electrochemical *** activation mechanism of zinc to Mg-6%Al-5%Pb anode is as follows:The hydrolyzation of dissolved Zn2+ ions reduces the pH value of the solution near the surface of the anode and accelerates the dissolution of Mg(OH)2 film;The precipitated Zn(OH)2 with similar structure as Mg(OH)2 combines with Mg(OH)2 film easily and makes it break down.

关键词： magnesium anode alloying electrochemistry electrochemical discharge activity