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Theory of small-scale self-focusing of spatially partially coherent beams and its implications for high-power laser systems

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High Power Laser science and engineering 2024年第3期12卷 84-89页

作者： Ruifeng Wang Xiaoqi zhang Yanli zhang Fanglun Yang Jianhao Tang Ziang Chen Jianqiang zhu Key Laboratory of High Power Laser and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghaiChina Center of materials science and Optoelectronics engineering University of Chinese Academy of SciencesBeijingChina

Based on the paraxial wave equation,this study extends the theory of small-scale self-focusing(SSSF)from coherent beams to spatially partially coherent beams(PCBs)and derives a general theoretical equation that reveals the underlying physics of the reduction in the B-integral of spatially *** the analysis of the simulations,the formula for the modulational instability(MI)gain coefficient of the SSSF of spatially PCBs is obtained by introducing a decrease factor into the formula of the MI gain coefficient of the SSSF of coherent *** decrease can be equated to a drop in the injected light intensity or an increase in the critical *** to this formula,the reference value of the spatial coherence of spatially PCBs is given,offering guidance to overcome the output power limitation of the high-power laser driver due to SSSF.

关键词： B-integral complex screen method nonlinearity small-scale self-focusing spatially partially coherent beams

Improving mechanical properties and high-temperature oxidation of press hardened steel by adding Cr and Si

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International Journal of Minerals,Metallurgy and materials 2024年第8期31卷 1865-1875页

作者： Rong zhu Yonggang Yang Baozhong zhang Borui zhang Lei Li Yanxin Wu Zhenli Mi National engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing 102206China Manufacturing Management Department Ningbo Iron&Steel Co.Ltd.Ningbo 315800China Hunan Valin Lianyuan Iron and Steel Co. Ltd.Loudi 417009China

This work investigated the effect of Cr and Si on the mechanical properties and oxidation resistance of press hardened *** indicated that the microstructure of the Cr-Si micro-alloyed press hardened steel consisted of lath martensite,M_(23)C_(6)carbides,and retained *** retained austenite and carbides are responsible for the increase in elongation of the micro-alloyed *** addition,after oxidation at 930℃for 5 min,the thickness of the oxide scales on the Cr-Si micro-alloyed press hardened steel is less than 5μm,much thinner than 45.50μm-thick oxide scales on *** oxide scales of the Cr-Si micro-alloyed steel are composed of Fe_(2)O_(3),Fe_(3)O_(4),mixed spinel oxide(FeCr_(2)O_(4)and Fe_(2)SiO_(4)),and amorphous SiO_(2).Adding Cr and Si significantly reduces the thickness of the oxide scales and prevents the generation of the FeO *** to the increase of spinel FeCr_(2)O_(4)and Fe_(2)SiO_(4)phase in the inner oxide scale and the amorphous SiO_(2)close to the substrate,the oxidation resistance of the Cr-Si micro-alloyed press hardened steel is improved.

关键词： Cr-Si micro-alloyed press hardened steel mechanical properties oxidation resistance amorphous SiO_(2)

In^(3+)-doped Sr_(2)Fe_(1.5)Mo_(0.5)O_(6−δ)cathode with improved performance for an intermediate-temperature solid oxide fuel cell

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Nano Research 2024年第1期17卷 407-415页

作者： Yumei Ma Lijie zhang Kang zhu Binze zhang Ranran Peng Changrong Xia Ling Huang State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources College of ChemistryXinjiang UniversityUrumqi 830046China Department of materials science and engineering University of Science and Technology of ChinaHefei 230026China

Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic *** this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR *** a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal *** addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.

关键词： solid oxide fuel cell cathode In3+doping oxygen reduction reaction(ORR) Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)

An efficient CuZr-based metallic glasses electrode material for electrocatalytic degradation of azo dyes

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Journal of Environmental sciences 2024年第2期136卷 537-546页

作者： Zhiwang Deng Bowen Zhao Songtao Li Zhengkun Li Shiming zhang Kewei zhang Zhengwang zhu Taiyuan university of science and Technology School of materials science and engineeringTaiyuan 030024China Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Chinese Academy of sciences Key Laboratory of Nuclear materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Qingdao Yunlu Advanced materials Technology Co. Ltd.Qingdao 266232China

Metallic glasses have received a lot of attention on wastewater treatment due to their unique atomic structure,and the use of metallic glasses as electrodes has produced unexpected electrocatalytic degradation effects for many pollutants through combining with electrochemical ***,it still is a formidable challenge to find a metallic glass electrode material with both efficient and clean for the catalytic degradation of *** this work,the Cu_(55)Zr_(45)metallic glassy ribbons are used as an electrode to degrade azo dyes and show the excellent degradation effect,which can reach 95.6%within 40 *** the degradation process,almost no additives are produced and Cu_(55)Zr_(45)metallic glassy ribbons have excellent effects under different pH ***,it exhibits good stability for degradation efficiency during the 8 cycle degradation tests of the amorphous alloy *** the copper nanoparticles are exposed on the surface of the ribbons,the oxidized copper obtained synergistically produce activated radicals is the primary degradation mechanism,where the auxiliary degradation mechanisms include electron transfer and the promotion of active *** research develops a new type of electrode material for wastewater treatment,and the economy and high efficiency of Cu55Zr45metallic glass endow it the expandable functional applications.

关键词： Metallic glasses Azo dyes Electrocatalytic Degradation Oxidized copper

Coupling between elytra of some beetles: Mechanism, forces and effect of surface texture

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science china(Life sciences) 2008年第10期51卷 894-901页

作者： DAI ZhenDong1, zhang YaFeng1, LIANG XingCai2 & SUN JiuRong1,3 1 Institute for Bio-inspired Structure and Surface engineering, Nanjing university of Aeronautics and Astronautics, Nanjing 210016, china 2 Kunming Institute of Zoology, Chinese Academy of science, Kunming 650223, china 3 college of Life sciences, Peking university, Beijing 100871, china 1. Institute for Bio-inspired Structure and Surface engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China 2. Kunming Institute of Zoology Chinese Academy of Science Kunming 650223 China 3. college of Life sciences Peking University Beijing 100871 China

Lightweight materials, structures and coupling mechanisms are very important for realizing advanced flight vehicles. Here, we obtained the geometric structures and morphologies of the elytra of beetles and ascertained its coupling zone by using the histological section technique and SEM. We set up a three-dimensional motion observing system to monitor the opening and closing behaviour of elytra in beetles and to determine the motion mechanism. We constructed a force measuring system to measure the coupling forces between elytra. The results show that elytra open and close by rotating about a single axle, where the coupling forces may be as high as 160 times its own bodyweight, the elytra coupling with the tenon and mortise mechanism, surface texture and opening angle between elytra heavily influence the coupling forces. These results may provide insights into the design mechanism and structure for future vehicles of flight.

关键词： beetle elytra coupling mechanism elytral morphology surface texture

A Modified Integrated Model of the Internal Structure of Chinese Cultured Pearls

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Journal of Wuhan university of Technology(materials science) 2011年第3期26卷 510-513页

作者：马红艳 Key Laboratory of Nonferrous Metals and New Material Processing Technology Ministry of EducationCollege of Materials Science and EngineeringGuangxi University

Optical and micro-infrared microscope were used to observe the internal structure and mineral composition of high and low quality Chinese seawater and freshwater cultured *** clearly reveal that aragonite and calcite are found in seawater cultured pearls,but vaterite is not *** contrast,vaterite and aragonite are found in freshwater cultured pearls,but calcite is not *** on our analysis and observations of the internal structure of high and low quality cultured pearls,a modified integrated model of the internal structure of Chinese cultured pearls was *** revisions to the previous model focus on significant differences within the prismatic layer of Chinese cultured pearls.

关键词： cultured pearls aragonite vaterite calcite integrated model

Nitrogen Runoff and Leaching Losses During Rice-Wheat Rotations in Taihu Lake Region,china

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Pedosphere 2007年第4期17卷 445-456页

作者： TIAN Yu-Hua YIN Bin YANG Lin-zhang YIN Shi-Xue zhu Zhao-Liang State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences 71 East Beijing Road Nanjing 210008 （China）. Graduate college of the Chinese Academy of sciences Beijing 100049 （China） college of Environmental science and engineering Yangzhou University Yangzhou 225009 （China）

Although nitrogen （N） loss through runoff and leaching from croplands is suspected to contribute to the deterioration of surrounding water systems, there is no conclusive evidence for paddy soils to prove this hypothesis. In this study, field plot experiments were conducted to investigate N losses through runoff and leaching for two consecutive years with 3 N fertilization rates in rice （Oryza sativa L.）-wheat （Triticum aestivum L.） rotations in the Taihu Lake region, china. A water collection system was designed to collect runoff and leachates for both the rice and wheat seasons. Results showed that dissolved N （DN）, rather than particulate N （PN）, was the main form of N loss by runoff. The NO3^--N concentration in runoff was between 0.1 and 43.7 mg L^-1, whereas the NH4^＋-N concentration ranged from below detection limit to 8.5 mg L^-1. Total N （TN） loads by runoff were 1.0-17.9 and 5.2-38.6 kg ha^-1 during rice and wheat seasons, respectively, and the main loss occurred at the early growing stage of the crops. Nitrogen concentrations in leachates during the rice seasons were below 1.0 mg L^-1 and independent of the N application rate, whereas those during the wheat season increased to 8.2 mg L^-1 and were affected by the fertilizer rate. Annual losses of TN through runoff and leaching were 13.7-48.1 kg ha^-1 from the rice-wheat cropping system, accounting for 5.6%-8.3% of the total applied N. It was concluded that reduction in the N fertilization rate, especially when the crop was small in biomass, could lower the N pollution potential for water systems.

关键词： leaching N fertilization rate N loss paddy soil runoff

The Effects of the Geometry of a Current Collector with an Equal Open Ratio on Output Power of a Direct Methanol Fuel Cell

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Energy engineering 2024年第5期121卷 1161-1172页

作者： Yingli zhu Jiachi Xie Mingwei zhu Jun zhang Miaomiao Li Tianjin Key Laboratory of Integrated Design and On-line Monitoring for Light Industry&Food Machinery and Equipment School of Mechanical EngineeringTianjin University of Science&TechnologyTianjin300222China Tianjin college University of Science and Technology BeijingTianjin301830China Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China

The open ratio of a current collector has a great impact on direct methanol fuel cell(DMFC)*** a number of studies have investigated the influence of the open ratio of DMFC current collectors,far too little attention has been given to how geometry(including the shape and feature size of the flow field)affects a current collector with an equal open *** this paper,perforated and parallel current collectors with an equal open ratio of 50%and different feature sizes are designed,and the corresponding experimental results are shown to explain the geometry effects on the output power of the *** results indicate that the optimal feature sizes are between 2 and 2.5 mm for both perforated and parallel flow field in the current collectors with an equal open ratio of 50%.This means that for passive methanol fuel cells,to achieve the highest output power,the optimal feature size of the flow field in both anode and cathode current collectors is between 2 and 2.5 mm under the operating mode of this *** effects of rib and channel position are also investigated,and the results indicate that the optimum pattern depends on the feature sizes of the flow field.

关键词： Direct methanol fuel cell geometry open ratio current collector position

Elemental Compositions of Clinopyroxenes from Southern Okinawa Trough Basalt:Implications for Magmatism and Structural Environment in an Initial Back-Arc Basin

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Journal of Ocean university of china 2024年第3期23卷 643-653页

作者： GUO Kun ZHAI Shikui FAN Di zhang Xia zhang Yu zhu Zhimin Laoshan Laboratory Qingdao 266237China Key Laboratory of Submarine Geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China Key Laboratory of Submarine Geosciences&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China

The major and trace elemental compositions of clinopyroxene from basalt were used to characterize the nature of the primitive magma and structural environment beneath the southern Okinawa Trough(SOT),which is an initial back-arc basin at a continental *** clinopyroxenes in the basalt were augite with variable Mg^(#)contents(73.37-78.22).The regular variations in major oxide contents(i.e.,CaO,FeO,TiO_(2),and Cr)with decreasing Mg#implied that the clinopyroxenes evolved from being enriched in Mg,Ca,and Cr to being enriched in Fe and *** clinopyroxenes had relatively low rare earth element concentrations(7.51×10^(-6) to 12.68×10^(-6))and negative Eu anomalies(δEu=0.67-0.95).The Kd_(cpx) values of clinopyroxenes(0.2-0.26),which were used to examine whether the clinopyroxene was equilibrated with its host basalt,demonstrate that these clinopyroxene phenocrysts were not captured crystals but were instead produced by crystallization differentiation of the *** calculated clinopyroxene crystallization temperatures showed a narrow range of 990-1061℃,and their crystallization pressures ranged from 2.0 to 3.2 *** geochemistry features of these clinopyroxenes indicated that the parent magma belonged to the subalkaline tholeiitic magma series and suggested that the magma experienced crystallization differentiation of olivine,plagioclase,and clinopyroxene,where the crystallization of plagioclase occurred earlier than that of *** with geophysical data,this research on primitive magma and its crystallization differentiation from clinopyroxene indicates that the SOT is in the stage of‘seafloor spreading’and that basaltic rocks produced from tholeiitic magma represent the generation of oceanic crust.

关键词： trace elements clinopyroxenes southern Okinawa Trough seafloor spreading back-arc basin