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Wind-proof and sand-fixing effects of Artemisia ordosica with different coverages in the Mu Us Sandy Land,northern China

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Journal of Arid Land 2022年第8期14卷 877-893页

作者： PANG Yingjun WU bo JIA Xiaohong xie Shengbo Institute of Desertification Studies Chinese Academy of ForestryBeijing 100091China Institute of Ecological Conservation and Restoration Chinese Academy of ForestryBeijing 100091China Key Laboratory of Desert Ecosystem and Global Change National Forestry and Grassland AdministrationBeijing 100091China Kumtag Desert Ecosystem Research Station National Forestry and Grassland AdministrationDunhuang 736200China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind erosion is a key global environmental problem and has many adverse *** Mu Us Sandy Land of northern China is characterized by an arid climate,where vegetation patches and bare sand patches are usually distributed mosaically,and aeolian activities occur *** plays a significant role in controlling wind *** ordosica is the most dominant native plant species in the Mu Us Sandy *** is urgent to study the wind-proof and sand-fixing effects of Artemisia ordosica in the Mu Us Sandy *** study analyzed the wind-proof and sand-fixing effects of Artemisia ordosica based on the field data of wind regimes,aeolian sediment transport,and surface change of Artemisia ordosica plots with four coverages(denoted as site A,site B,site C,and site D)in the Mu Us Sandy Land during the period from 1 June 2018 to 29 June *** coverages of Artemisia ordosica at site A,site B,site C,and site D were 2%,16%,29%,and 69%,*** annual average wind speeds at 2.0 m height above the ground for site A,site B,site C,and site D were 3.47,2.77,2.21,and 1.97 m/s,*** annual drift potentials were 193.80,69.72,15.05,and 6.73 VU at site A,site B,site C,and site D,*** total horizontal aeolian sediment fluxes during the period from 2-3 June 2018 to 6 June 2019 at site A,site B,site C,and site D were 4633.61,896.80,10.54,and 6.14 kg/m,*** A had the largest surface changes,and the surface changes at site B were significantly weaker than those at site A,whereas the surface changes at site C and site D were *** results indicated that Artemisia ordosica significantly reduced the wind speed,drift potential,aeolian sediment transport,and surface *** higher the coverage of Artemisia ordosica is,the more obvious the effects of wind-proof and *** erosion would be effectively controlled in the Mu Us Sandy Land if the coverage of Artemisia ordosica is greater than 29%.These results provid

关键词： Artemisia ordosica wind-proof sand-fixing wind erosion aeolian sediment flux Mu Us Sandy Land

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Newmark design spectra considering earthquake magnitudes and site categories

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Earthquake Engineering and Engineering Vibration 2016年第3期15卷 519-535页

作者： bo Li Wei-Chau xie M.D.Pandey Department of Civil and Environmental Engineering University of Waterloo

Newmark design spectra have been implemented in many building codes, especially in building codes for critical structures. Previous studies show that Newmark design spectra exhibit lower amplitudes at high frequencies and larger amplitudes at low frequencies in comparison with spectra developed by statistical methods. To resolve this problem, this study considers three suites of ground motions recorded at three types of sites. Using these ground motions, influences of the shear-wave velocity, earthquake magnitudes, source-to-site distances on the ratios of ground motion parameters are studied, and spectrum amplification factors are statistically calculated. Spectral bounds for combinations of three site categories and two cases of earthquake magnitudes are estimated. Site design spectrum coefficients for the three site categories considering earthquake magnitudes are established. The problems of Newmark design spectra could be resolved by using the site design spectrum coefficients to modify the spectral values of Newmark design spectra in the acceleration sensitive, velocity sensitive, and displacement sensitive regions.

关键词： Newmark design spectrum site design spectrum coefficients site conditions

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Preparation of M2O3-CeO2(M=La,Fe,and Al) Compoundoxide Catalyst and Its Degradation Performance

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Journal of Wuhan University of Technology(Materials Science) 2020年第2期35卷 335-341页

作者： LI Youfeng LIN Jinliang xie bo LIU Guoqing School of Chemistry and Chemical Engineering Zunyi Normal CollegeZunyi 563006China School of Chemistry and Chemical En-gineering Hunan University of Science and TechnologyXiangtan 411201China

As one of the most active rare earths,CeO2 has caused extensive concern due to its multifunctional ***2-based compound oxide of M2O3-CeO2(M=La,Fe,and Al)were prepared by coprecipitation and impregnation *** photocatalytic performance of the samples for the degradation methylene blue was studied under UV and visible light *** effects of constituents on the properties of the CeO2-based catalysts were investigated by XRD,TEM,BET,and UV-Vis *** highest degradation of methylene blue under 230W UV light was almost 100%at 50 min by La2O3/Fe2O3-CeO2/γ-Al2O3 catalyst and 99.42%at 50 min by Fe2O3-CeO2/γ-Al2O3 *** methylene blue removal efficiency under indoor natural light reaches 93.81%by La2O3/Fe2O3-CeO2/γ-Al2O3 catalyst and 92.34%by Fe2O3-CeO2/γ-Al2O3 catalyst at 50 *** order of catalytic degradation activity is La2O3/Fe2O3-CeO2/γ-Al2O3>Fe2O3-CeO2/γ-Al2O3>La2O3-CeO2/γ-Al2O3>Al2O3,owing to their structural *** doping of La^3+or Fe3+onto CeO2/γ-Al2O produced much more oxygen vacancies under light irradiation and reduced the energy laps of CeO2 with value of 2.86 ev,which improved the photocatalytic redox performance of the composite oxide.

关键词： CeO2-based compound oxide catalyst degradation catalysis

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Physical design and multi-particle simulations of a compact IH-DTL with KONUS beam dynamics for proton therapy

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Nuclear Science and Techniques 2020年第7期31卷 12-24页

作者： Jian Qiao xiu-Cui xie De-Ming Li Yue-Hu Pu Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of the Chinese Academy of Sciences Beijing 100049China Shanghai APACTRON Particle Equipment Company Ltd. Shanghai 210800China

A compact room-temperature inter-digital H-mode(IH)drift tube linac(DTL)with Kombinierte Null Grad Struktur beam dynamics is proposed in this *** proposed IH-DTL,which operates at 325 MHz,accelerates 18 mA proton particles from 3.0 to 7.0 MeV as part of a proton synchrotron-based therapy *** is composed of two main sections,namely a bunching section(-30°)and accelerating section(0°).There is no transverse focusing element inside the cavity,which increases the acceleration gradient and reduces the cavity length and power *** our physical designs,LORASR code is utilized for beam dynamics design and multi-particle *** synchronous particle energy,injection phase,and acceleration voltage of each gap are optimized carefully to increase transmission efficiency while minimizing beam emittance growth and beam *** total length of the cavity is 0.82 m and the acceleration gradient reaches 4.88 MV/m,resulting in a transmission efficiency of 100%and beam emittance growth less than10%.The details of the specific work undertaken in this study are presented in this paper.

关键词： bunch beam particle

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DEFORMATION INVESTIGATION ON iPP/SiO_2 COMPOSITES: INFLUENCE OF STRETCHING TEMPERATURE AND PARTICLE SIZE ON MORPHOLOGY EVOLUTION AND CRYSTALLINE STRUCTURE OF THIN FILMS

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Chinese Journal of Polymer Science 2013年第2期31卷 275-284页

作者： xiu-qin Zhang Qian Xing Rong-bo Li 王锐 Du-jin Wang Beijing Key Laboratory of Clothing Materials R & D and Assessment Department of Materials Science & Engineering Beijing Institute of Fashion Technology Beijing National Laboratory for Molecular Sciences Key Laboratory of Engineering Plastics Institute of Chemistry Chinese Academy of Sciences

In the present work, structure changes during （SiO2） composites have been investigated systematically stretching of isotactic polypropylene （iPP） and iPP/silicon dioxide The or-form crystal structure of both iPP and iPP/SiO2 composites is destroyed and transforms into the mesophase as the samples are stretched at a low temperature （35℃）, while stretching at high temperatures （90℃ and 120℃） can restrain the appearance of defects and keep the perfection of crystal structure. FTIR results reveal that the stretching temperatures show no obvious difference of the effect on the orientation of pure iPP, however, the orientation of iPP/SiO2 composites is greatly changed by the tensile temperature. In the case of micron-sized SiO2 particles （average particle diameter d 〉 1 μm）, the orientation of the composites is lower than that of pure iPP at all stretching temperatures. The above results suggest that the stretching temperature and the SiO2 particle size have great influence on the structure variation and orientation behavior of iPP/SiO2 composites.

关键词： iPP/SiO2 composites Stretching Morphology Structure variation.

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High corrosion and wear resistant electroless Ni–P gradient coatings on aviation aluminum alloy parts

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 155-164页

作者： bo Wang Jiawei Li Zhihui xie Gengjie Wang Gang Yu College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410012China Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province/College of Chemistry and Chemical Engineering China West Normal UniversityNanchong 637002China Zhongchuan Machinery Ltd.Co. Aero Engine Corporation of ChinaChangsha 410200China

A Ni–P alloy gradient coating consisting of multiple electroless Ni–P layers with various phosphorus contents was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were used to characterize the different Ni–P coatings’ morphologies, phase structures, elemental compositions, and corrosion protection. The gradient coating showed good adhesion and high corrosion and wear resistance, enabling the application of aluminum alloy in harsh environments. The results showed that the double zinc immersion was vital in obtaining excellent adhesion (81.2 N). The optimal coating was not peeled and shredded even after bending tests with angles higher than 90°and was not corroded visually after 500 h of neutral salt spray test at 35℃. The high corrosion resistance was attributed to the misaligning of these micro defects in the three different nickel alloy layers and the amorphous structure of the high P content in the outer layer. These findings guide the exploration of functional gradient coatings that meet the high application requirement of aluminum alloy parts in complicated and harsh aviation environments.

关键词： aluminum alloy electroless nickel coating corrosion adhesion

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New strategies for asymmetric photocatalysis: asymmetric organocatalytic/photoredox relay catalysis for efficient synthesis of polycyclic compounds containing vicinal amino alcohols

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Science China Chemistry 2024年第3期67卷 945-952页

作者： Jia-Lu Zhang Wen-bo He xiu-Qin Hu Peng-Fei Xu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical EngineeringLanzhou UniversityLanzhou 730000China State Key Laboratory of Veterinary Etiological Biology College of Veterinary MedicineLanzhou UniversityLanzhou Veterinary Research InstituteChinese Academy of Agricultural SciencesLanzhou 730000China MOE Frontiers Science Center for Rare Isotopes Lanzhou UniversityLanzhou 730000China

An asymmetric catalytic strategy in photocatalysis utilizing a chirality-induced approach through an organocatalytic/photoredox relay catalysis strategy is successfully achieved for the rapid construction of polycyclic compounds containing vicinal amino alcohols in a one-pot protocol. This methodology facilitates the efficient synthesis of diverse substituted polycyclic tetrahydroquinoline and benzofuran-derived vicinal amino alcohols, each containing five consecutive chiral centers, with high yields,excellent diastereoselectivities and enantioselectivities(up to 95% yield, >20:1 dr and 98% ee), under mild reaction conditions driven by sequential bifunctional squaramide organocatalyst-catalyzed [4+2] annulation and photocatalyst-catalyzed ketyl radical addition cyclization reaction process. Furthermore, investigations into the stereoselectivity mechanism and high-resolution mass spectrometry(HRMS) experiments on free radical trapping have provided evidence for elucidating the detailed mechanism of chirality-induced processes and chiral intermediate conversions in this procedure.

关键词： enantioselective photocatalysis asymmetric organocatalytic/photocatalysis relay catalysis five consecutive chiral centers chirality-induced strategy chirality vicinal amino alcohols

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A secure rational quantum state sharing protocol

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Science China(Information Sciences) 2018年第2期61卷 204-215页

作者： Zhao DOU Gang XU xiu-bo CHEN Xin LIU Yi-Xian YANG Information Security Center State Key Laboratory of Networking and Switching TechnologyBeijing University of Posts and Telecommunications School of Software Engineering Beijing University of Posts and Telecommunications School of Information Engineering Inner Mongolia University of Science and Technology School of Computer Science Shaanxi Normal University Gui Zhou University Guizhou Provincial Key Laboratory of Public Big Data

A novel rational protocol to share two arbitrary qubits among multiple parties is investigated in this paper. First, the protocol is presented, which is learned from Li et al.’s protocol. Second, the utility,security, correctness, fairness, Nash equilibrium, and Pareto optimality of our scheme are discussed in detail,where the utility, correctness, and fairness of rational quantum state sharing protocols are creatively given because the agent who recovers the state plays a different and more important role. Another important point is that assumptions about our protocol are more practical and suitable than existing protocols.

关键词： rational quantum state sharing Nash equilibrium secure correct

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Hydrothermal Synthesis and Luminescent Properties of Flowerlike Zn_2GeO_4 and Mn^(2+)-Doped Zn_2GeO_4 Hierarchical Architectures

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Chemical Research in Chinese Universities 2012年第5期28卷 764-767页

作者： LI bo SONG Shu-yan SUN xiu-juan PENG Jing WANG bo XING Yan College of Chemistry Northeast Normal UniversityChangchun 130024P.R.China State Key Laboratory of Rare Earth Resource Utilizations Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022P.R.China

Three-dimensional（3D） flowerlike hierarchical Zn2GeO4 and Mn2＋-doped Zn2GeO4 microstructures have been prepared by a facile hydrothermal approach. X-Ray diffraction（XRD）, field emission scanning electron micro-scopy（FESEM）, transmission electron microscopy（TEM） and photoluminescence（PL） spectrometry were employed to characterize the samples. Such flowerlike hierarchical Zn2GeO4 microstructures with an average diameter of 3―4 μm were found to be constructed by abundant single crystalline nanorods of about 90 nm in diameter. The luminescent properties of Zn2GeO4：xMn phosphors with different contents of Mn2＋ as an activator were investigated. The Mn2＋-doped samples showed green luminescence corresponding to the d-d transition of Mn2＋ under the irradiation of UV light. The red shift（from 531 nm to 538 nm） in λem with increasing Mn2＋ content was observed in the luminescent spectra, which should be attributed to a weak crystal field because of the substitution of Zn2＋ by Mn2＋ at a distorted tetrahedral lattice site.

关键词： Zinc orthogermanate Hierarchical architecture Luminescent property

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Maximum Power Point Tracking Technology for PV Systems: Current Status and Perspectives

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Energy Engineering 2024年第8期121卷 2009-2022页

作者： bo Yang Rui xie Zhengxun Guo Faculty of Electric Power Engineering Kunming University of Science and TechnologyKunming650500China Intelligent Electric Power Grid Key Laboratory of Sichuan Province Chengdu610065China Foshan Graduate School of Innovation Northeastern UniversityFoshan528311China College of Information Science and Engineering Northeastern UniversityShenyang110819China

Maximum power point tracking(MPPT)technology plays a key role in improving the energy conversion efficiency of photovoltaic(PV)systems,especially when multiple local maximum power points(LMPPs)occur under partial shading conditions(PSC).It is necessary to modify the operating point efficiently and accurately with the help of MPPT technology to maximize the collected *** though a lot of research has been carried out and impressive progress achieved for MPPT technology,it still faces some challenges and ***,the mathematical model established for PV cells is not precise ***,the existing algorithms are often optimized for specific conditions and lack comprehensive adaptability to the actual operating ***,a single algorithm may not be able to give full play to its *** the end,the selection criteria for choosing the suitable MPPT algorithm/converter combination to achieve better performance in a given scenario is very ***,this paper systematically discusses the current research status and challenges faced by PV MPPT technology around the three aspects of MPPT models,algorithms,and hardware *** in-depth thinking and discussion,it also puts forward positive perspectives on future development,and five forward-looking solutions to improve the performance of PV systems MPPT are suggested.

关键词： PV systems MPPT partial shading condition DC-DC converter

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