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Accuracy Improvement of Zenith Tropospheric Delay Estimation Based on GPS Precise Point Positioning Algorithm

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Geo-Spatial Information Science 2010年第4期13卷 306-310页

作者： ZHU Qinglin zhao zhenwei LIN Leke wu Zhensen China Research Institute of Radio Wave Propagation 36 West Xianshan Road Qingdao 266107 China School of Science Xidian University 2 South Taida Road Xi'an 710071 China

In the precise point positioning(PPP),some impossible accurately simulated systematic errors still remained in the GPS observations and will inevitably degrade the precision of zenith tropospheric delay(ZTD) *** stochastic models used in the GPS PPP mode are *** this paper,the research results show that the precision of PPP-derived ZTD can be obviously improved through selecting a suitable stochastic model for GPS ***-elevation observations can cover more troposphere information that can improve the estimation of ZTD.A new stochastic model based on satellite low elevation cosine square is *** results show that the stochastic model using satellite elevation-based cosine square function is better than previous stochastic models.

关键词： precise point positioning stochastic model zenith tropospheric delay cosine GPS

Performance Comparison of GA,PSO,and DE Approaches in Estimating Low Atmospheric Refractivity Profiles

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wuhan University Journal of Natural Sciences 2010年第5期15卷 433-439页

作者： WANG Bo wu Zhensen zhao zhenwei School of Science Xidian University Xi'an 710071 Shaanxi China China Research Institute of Radiowave Propagation Qingdao 266107 Shandong China

Particles swarm optimization（PSO） and differential evolution（DE） algorithms based on optimization are employed to estimate low atmospheric refractivity profiles from radar sea *** atmospheric refractivity profiles are modeled as evaporation *** objective functions,which are used to evaluate the fit of simulated and measured power in estimation procedures,are also investigated at different frequencies such as L-,S-,C-and X-frequency at 10 m/s wind *** results show that all the objective functions are multi-peak *** Adjusted Barton Model of radar cross section（RCS） is *** and DE algorithms are compared with genetic algorithm（GA） by 200 Monte Carlo simulation *** results indicate that DE has the best global search ability,and PSO has the highest success *** to the statistical results,PSO algorithm with the population size 30 is the appropriate way for evaporation duct estimation.

关键词： optimization radar refractivity evaporation duct

Effect of water vapor on NH_3–NO/NO_2 SCR performance of fresh and aged MnO_x–NbO_x–CeO_2 catalysts

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Journal of Environmental Sciences 2015年第5期27卷 240-247页

作者： Lei Chen Zhichun Si Xiaodong wu Duan Weng zhenwei wu State Key Lab of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Graduate School at Shenzhen Tsinghua University

A MnOx-NbOx-CeO2 catalyst for low temperature selective catalytic reduction（SCR） of NOx with NH3 was prepared by a sol-gel method, and characterized by NH3-NO/NO2 SCR catalytic activity, NO/NH3 oxidation activity, NOx/NH3 TPD, XRD, BET, H2-TPR and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy（DRIFTS）. The results indicate that the Mn Ox-Nb Ox-CeO2 catalyst shows excellent low temperature NH3-SCR activity in the temperature range of 150-300℃. Water vapor inhibits the low temperature activity of the catalyst in standard SCR due to the inhibition of NOx adsorption. As the NO2 content increases in the feed, water vapor does not affect the activity in NO2 SCR. Meanwhile, water vapor significantly enhances the N2 selectivity of the fresh and the aged catalysts due to its inhibition of the decomposition of NH4NO3 into N2O.

关键词： Water effect MnOx-NbOx-CeO2 catalysts Acid sites Fast SCR reaction NO/NO2 ratio

Novel titanium dioxide ceramics containing bismuth and antimony

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Journal of Materiomics 2017年第2期3卷 112-120页

作者： zhenwei Li Jiagang wu Department of Materials Science Sichuan University610064PR China

Here,we developed one kind of novel TiO_(2) ceramics with colossal dielectric constant by chemical modifications(Bi^(3+) and Sb^(5+)),and discussed the physical origin for giant dielectric *** of Bi and/or Sb on their microstructure,dielectric properties as well as its frequency and temperature stability were studied in *** was found that their dielectric properties are strongly sensitive to(Bi,Sb)contents,and colossal dielectric permittivity(CP)(10^(4)~10^(5))together with low dielectric loss(~5.7%)can be obtained in a wide composition *** addition,all the ceramics possessed good frequency(10^(2)~10^(6)Hz)and temperature(-150-200℃)stability of dielectric *** addition,the defects caused by the Bi volatilization may be the reason for higher dielectric properties of(Bi_(0.5)Sb_(0.5))_(x)Ti_(1-x)O_(2) ceramics with respect to(A_(0.5)Sb_(0.5))_(x)Ti_(1-x)O_(2)(A=In,Pr,Dy,Sm,Gd,Yb,Ga,Al,Fe or Sc).According to the results of complex impedance and XPS,the electron-pinned defect-dipoles may be suitable to explain the CP phenomenon,and oxygen vacancies-induced by Bi^(3+)&Sb^(5+) substitution for Ti^(4+) should be responsible for conduction *** believe that this profound investigation can benefit the development of TiO_(2) ceramics as a CP material.

关键词： Colossal permittivity TiO_(2) Antimony and Bi Physical mechanism

Worm-like ordered mesoporous carbon from liquefied wood:Morphological manipulation by varying hydrothermal temperature

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Aggregate 2024年第4期5卷 416-425页

作者： Yang Li zhenwei wu Yanhong Liu Kun Zhang Sha Luo wei Li Shouxin Liu Key Laboratory of Bio-based Material Science and Technology of the Ministry of Education Northeast Forestry UniversityHarbinChina Engineering Research Center of Advanced Wooden Materials of the Ministry of Education Northeast Forestry UniversityHarbinChina

The hydrothermal/soft templating method is an effective way to synthesize ordered mesoporous carbon(OMC),yet the mechanism of this strategy is not well ***,a hydrothermal temperature-controlled approach is developed to precisely synthesize OMCs with well-deﬁned morphologies from liqueﬁed wood(LW).As the hydrothermal temperature increases from 130 to 210◦C,the hydrophilicity of the hydrophilic blocks decreases accompanied by the increase of the rel-ative volume of the hydrophobic block,resulting in the packing parameter p of micelles changing from p≤1/3 to 1/3

关键词： hydrothermal temperature-controlled liqueﬁed wood ordered mesoporous carbon

Highly dispersed iron species created on alkali-treated zeolite for ammonia SCR

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Progress in Natural Science:Materials International 2013年第5期23卷 493-500页

作者： Jing Ma Duan Weng Xiaodong wu Zhichun Si zhenwei wu State Key Laboratory of New Ceramics & Fine Processing School of Materials Science and Engineering Yangtze Delta Region Institute of Tsinghua University Advanced materials institute Graduate School at ShenzhenTsinghua University

Alkaline treatment using sodium hydroxide was introduced to obtain a hierarchical pore structure in H-ZSM-5 ***-exchanged zeolite catalysts were prepared by impregnation on the original and alkali-treated zeolites,and were evaluated for NOx reduction by NH3,NO oxidation,and NH3 oxidation *** highly dispersed iron species as active sites can be obtained by controlling the pore structure and particle size of ***,the Fe/ZSM-5 catalyst treated mildly by sodium hydroxide before iron exchange,which contains amounts of highly dispersed Fe species,obtains over80% NOx conversion at a wide temperature range of 250-500℃.

关键词： Fe/ZSM-5 Alkaline treatment Brnsted acidity Iron dispersion NH3-SCR

Analysis of asymmetry of the D_(α)emission spectra under the Zeeman effect in boundary region for D-D experiment on EAST tokamak

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Chinese Physics B 2021年第2期30卷 377-384页

作者： wei Gao Juan Huang Jianxun Su Jing Fu Yingjie Chen wei Gao zhenwei wu EAST Team Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China

In 2015 campaign,deuterium atomic emission spectra(D_(α))under the Zeeman effect in boundary region had been measured by a high resolution optical spectroscopic multichannel analysis(OSMA)system based on passive spectroscopy during the deuterium plasma discharge on EAST tokamak,and part of the works about the Zeeman effect on D_(α)spectra had already been ***,the asymmetric phenomena of D_(α)emission spectra under the Zeeman effect were observed in process of analyzing the spectral *** understand the asymmetric phenomena and acquire the useful local plasma information,an algorithm was proposed and used to analyze the asymmetry of the emission spectra under the Zeeman effect with all polarization components(πand±σ).In the algorithm,the neutral atoms were considered to follow the Maxwell distribution on EAST,and I+σ=I-σwas considered and *** of the line-averaged spectra along the viewing chord,the emission spectra were considered from two different regions:low-field side(LFS)and high-field side(HFS).Each spectral line was classified into three energy categories(the cold,warm,and hot)based on different atomic production processes in boundary *** viewing angleθ(between the magnetic field B and the viewing chord),magnetic field B at two spectral emission positions(HFS and LFS)and the Doppler shift of all three energy categories of each spectral line were all considered in the *** effect of instrument function was also included *** information of the boundary plasma were acquired,the reason for the asymmetric phenomena was discussed,and the boundary recycling during the discharge were studied in the *** on fitting a statistical data of acquired fitting results,an important conclusion was acquired that the ratio of the spectral line intensity in HFS and LFS was proportional to the square of that of the corresponding magnetic field.

关键词： Zeeman effect deuterium atom spectral lineshape plasma

Observation of deuterium molecule emission spectra under an active feedback control of H-mod plasma divertor detachment experiment on the EAST tokamak

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Chinese Physics B 2019年第12期28卷 231-236页

作者： wei Gao Juan Huang Jichan Xu Liang Wang Jing Zhang Jianxun Su Yingjie Chen wei Gao zhenwei wu Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China

Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puffing neon gas and the strike point splitting phenomenon on divertor target was also clearly observed by divertor probes *** boundary region, many neutral particle processes(atom and molecule) were happened and accompanied by their emission spectra under the detachment discharge. By studying these emission spectra, it is helpful for us to understand the role of atoms and molecules in boundary recycling, which is important for studying the physical mechanism of divertor detachment. For the Fulcher-α system(d(3 p)3Πu±→ a(2 s)3Σg+), D2 emission spectra in the range from 601 nm to 606 nm were observed, identified and fitted in the detachment experiment for the first time on the EAST, and the spectra in the Q(0–0) band(d3Πu-→ a(2 s)3Σg+) in the Q branch of the Fulcher-α system were used for detailed analysis to acquire the boundary region temperature Te(below 5eV), which could not be provided very well by other diagnostics on the EAST. An electronic version deuterium molecular spectral line database was established to identify the spectral lines and a multi-peak fitting program was developed to fit and analyze the observed spectra.

关键词： plasma detachment molecular spectrum deuterium

Defects inducing anomalous exciton kinetics in monolayer WS_(2)

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Nano Research 2022年第2期15卷 1616-1622页

作者： Zhe Li Yan Zeng zhenwei Ou Tianzhu Zhang Rongguang Du Ke wu Quanbing Guo wei Jiang Yuhao Xu Tao Li Tai Min Ti Wang Hongxing Xu School of Physics and Technology Center for Nanoscience and Nanotechnologyand Key Laboratory of Artificial Micro-and Nanostructures of Ministry of EducationWuhan UniversityWuhan 430072China Institute of Microscale Optoelectronics Shenzhen UniversityShenzhen 518060China Center for Spintronics and Quantum System State Key Laboratory for Mechanical Behavior of MaterialsSchool of Materials Science and EngineeringXian Jiaotong UniversityXian 710049China

Two-dimensional(2D)transition metal dichalcogenide(TMD)has emerged as an effective optoelectronics material due to its novel optical *** the role of defects in exciton kinetics is crucial for achieving high-efficiency TMD ***,we observe defects induced anomalous power dependence exciton dynamics and spatial distribution in hexagonal heterogeneous WS_(2).With transient absorption microscopy study,we illustrate that these phenomena originate from the competition between radiative and defect-related non-radiative *** understand the physics behind this,a decay model is introduced with two defect-related channels,which demonstrates that more excitons decay through non-radiative channels in the dark region than the bright *** work reveals the mechanisms of anomalous exciton kinetics by defects and is instrumental for understanding and exploiting excitonic states in emerging 2D semiconductors.

关键词： transition metal dichalcogenides defect exciton dynamics transient absorption microscopy