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Investigation on the laser ablation of SiC ceramics using micro-Raman mapping technique

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Journal of Advanced Ceramics 2016年第3期5卷 253-261页

作者： Chaoli FU Yong YANG Zhengren HUANG Guiling LIU Hui ZHANG Fang JIANG yuquan WEI Structural Ceramic Engineering Research Center Shanghai Institute of CeramicsChinese Academy of Sciences 1295 Dingxi Road Shanghai 200050 China College of Environmental and Chemical Engineering Shanghai University 99 Shangda RoadShanghai 200444 China Structural Ceramic Engineering Research Center Shanghai Institute of CeramicsChinese Academy of Sciences 1295 Dingxi Road Shanghai 200050 China

Research on the laser ablation behavior of SiC ceramics has great significance for the improvement of their anti-laser ability as high-performance mirrors in space and lasers, or the laser surface micro-machining technology as electronic components in micro-electron mechanical systems (MEMS). In this work, the laser ablation of SiC ceramics has been performed by using laser pulses of 12 ns duration at 1064 nm. The laser induced damage threshold (LIDT) below 0.1 J/cm(2) was obtained by 1-on-1 mode and its damage morphology appeared in the form of 'burning crater' with a clear boundary. Micro-Raman mapping technique was first introduced in our study on the laser ablation mechanisms of SiC surface by identifying physical and chemical changes between uninjured and laser-ablated areas. It has been concluded that during the ablation process, SiC surface mainly underwent decomposition to the elemental Si and C, accompanied by some transformation of crystal orientation. The oxidation of SiC also took place but only in small amount on the edges of target region, while there was no hint of SiO2 in the center with higher energy density, maybe because of deficiency of O-2 atmosphere in the ablated area, elimination of SiO2 by carbon at 1505 degrees C, or evaporating at 2230 degrees C.

关键词： silicon carbide (SiC) laser ablation micro-Raman mapping technique decomposition oxidation

Ultrafast Time-Resolved Optical Kerr Effect in Phthalocyanine Langmuir-Blodegett Film

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Chinese Physics Letters 1994年第7期11卷 457-460页

作者： YUAN Ping XIA Zongju ZOU Yinghua QIU Ling SHEN Jifeng SHEN yuquan XU Huijun Department of Physics Mesoscopic Physics Laboratory(MPL)Peking UniversityBeijing 100871 Institute of Photographic Chemistry Academia SinicaBeijing 100101

The resonant optical Kerr effect in the Langmuir-Blodegett film of 2,9,16,23-tetra heptadecylamido substituted vanadyl phthalocyanine was measured with femtosecond laser pulses to determine the relaxation time,and mea... 详细信息

关键词： nonlinearity relaxation phthalocyanine

Effects of different C/N ratios on the maturity and microbial quantity of composting with sesame meal and rice straw biochar

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Biochar 2021年第4期3卷 557-564页

作者： Yabin Zhan yuquan Wei Zeyu Zhang A-ke Zhang Yongbin Li Ji Li College of Resources and Environmental Science China Agricultural UniversityYuanmingyuan West Road No.2HaidianBeijing 100193China Organic Recycling Research Institute(Suzhou)of China Agricultural University SuzhouChina

The purpose of this paper was to study the effects of different C/N ratios on the maturity and microbial quantity of com-posting with sesame meal and rice straw *** straw was calcined into biochar as raw materials composting with sesame meal for 30 days,referring to Chenfu Agricultural Book in Sōuthern Song Dynasty(1127-1279 A.D.).Sesame meal was used to adjust the C/N ratio of compost,and three treatments were designed in the experiment,which were C/N ratios of 15,20 and 30,*** results showed that C/N ratio of 20 was beneficial for promoting the temperature rise,the removal of water,the degradation of organic carbon,and the decrease of microbial *** C/N ratio of 20 was beneficial to the compost maturity(T value was 0.47,final GI was 99.67%).The results of Pearson correlation analysis showed that C/N ratio was positively correlated with moisture content,total organic carbon and negatively correlated with germination index,indicating that high C/N ratio was beneficial to water removal and total organic carbon ***,we suggest that the suitable C/N ratio of rice straw biochar and sesame meal is *** the same time,we have proved that the composting method in Southern Song Dynasty is feasible,which is of great significance to understand the development of composting in China.

关键词： C/N Compost maturity Microbial quantity Rice straw biochar Sesame meal

利用微雨雷达研究一次冷锋云系降水的垂直结构分布及演变特征

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大气科学 2019年第3期43卷 618-633页

作者：崔云扬周毓荃蔡淼南京信息工程大学南京210044 中国气象科学研究院北京100081 中国气象局云雾物理环境重点实验室北京100081

本文利用河北邢台测站Ka波段微雨雷达(MRR)观测到的一次冷锋云系降水过程分析降水的垂直分布及演变特征。将MRR观测结果与天气雷达、地面雨滴谱仪、雨量计观测结果进行对比以检验MRR数据的可靠性。同时将MRR与雨滴谱仪和激光云高仪结合... 详细信息

本文利用河北邢台测站Ka波段微雨雷达(MRR)观测到的一次冷锋云系降水过程分析降水的垂直分布及演变特征。将MRR观测结果与天气雷达、地面雨滴谱仪、雨量计观测结果进行对比以检验MRR数据的可靠性。同时将MRR与雨滴谱仪和激光云高仪结合,研究了不同相对湿度阶段特征量、雨滴谱的平均垂直分布特征和降水特征量随时间、高度的演变特征。结果表明:MRR与雨量计及雨滴谱仪累计雨量结果较为接近,趋势一致。MRR 200 m雨强值与地面雨滴谱仪雨强值偏差最小,平均偏差为0.05 mm h-1,相关系数为0.93。相比雨滴谱仪,MRR观测到的小滴数浓度出现高估,大滴数浓度出现低估,中滴数浓度较为一致。降水在云内和云外受不同微物理过程影响,垂直变化特征不同。降水初期平均反射率和雨强在云底以下明显减小,小滴和中滴平均数浓度明显减小,蒸发作用影响较强。而在其余时间段在云内随高度降低平均反射率和雨强略有增加,小滴平均数浓度变化较小,中滴大滴平均数浓度增加,表明云内有云滴与雨滴间的碰并发生。而在云外低层,随高度降低平均有效直径明显增加,平均雨滴总数浓度明显减小,小滴平均数浓度显著减小,大滴平均数浓度显著增加,表明在云外低层雨滴间的碰并作用较强。

关键词：微雨雷达雨滴谱垂直分布微物理过程

Refill Friction Stir Spot Welding Al Alloy to Copper via Pure Metallurgical Joining Mechanism

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Chinese Journal of Mechanical Engineering 2021年第4期34卷 90-97页

作者： Zhikang Shen yuquan Ding Wei Guo Wentao Hou Xiaochao Liu Haiyan Chen Fenjun Liu Wenya Li Adrian Gerlich School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China Centre for Advance Materials Joining University of WaterlooWaterloo N2L 3G1Canada College of Energy Engineering Yulin UniversityYulin 719000China

The current investigation of refill friction stir spot welding(refill FSSW)Al alloy to copper primarily involved plunging the tool into bottom copper sheet to achieve both metallurgical and mechanical interfacial *** to conventional FSSW and pinless FSSW,weld strength can be significantly improved by using this ***,tool wear is a critical issue during refill *** this study,defect-free Al/copper dissimilar welds were successfully fabricated using refill FSSW by only plunging the tool into top Al alloy ***,two types of continuous and ultra-thin intermetallic compounds(IMCs)layers were identified at the whole Al/copper ***,strong evidence of melting and resolidification was observed in the localized *** peak temperature obtained at the center of Al/copper interface was 591℃,and the heating rate reached up to 916℃/s during the sleeve penetration phase.A softened weld region was produced via refill FSSW process,the hardness profile exhibited a W-shaped appearance along middle thickness of top Al *** weld lap shear load was insensitive to the welding condition,whose scatter was rather *** fracture path exclusively propagated along the IMCs layer of Cu_(9)Al_(4) under the external lap shear loadings,both CuAl_(2) and Cu_(9)Al_(4) were detected on the fractured surface on the copper *** research indicated that acceptable weld strength can be achieved via pure metallurgical joining mechanism,which has significant potential for the industrial applications.

关键词： Refill friction stir spot welding Al alloy Copper Interfacial microstructure Mechanical properties

Ultrafast Optical Response of Phthalocyanine Langmuir-Blodegett Film

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Chinese Physics Letters 1994年第4期11卷 246-249页

The mechanism of 2,9,16,23-tetra-heptadecylamido substituted vanadyl phthalocyanine Langmuir-Blodegett film was studied with femtosecond laser *** ultrafast decay due to phonon-exciton coupling greatly affected by temperature,and exciton-exciton annihilation leading to the recovery of the ground state(T~lops)and an even slower relaxation were observed.

关键词： relaxation slower annihilation

Lyapunov Exponent Spectrum for Two-Mode Model in Spin-Wave Chaos

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Chinese Physics Letters 1992年第8期9卷 435-437页

作者： HE yuquan CHI Ruidong YU Jinlong Department of Physics Tianjin UniversityTianjin 300072

The results of numerical experiments on the two-mode model for yttrium iron garnet sphere in the parallel-pumping configuration are reported and the complete Lyapunov exponent spectrum is presented.A rather complicated structure of the Lyapunov exponent spectrum can be recognized by the appearance of the associated peak in the Kolmogorov-Sinai entropy and the Lyapunov dimension *** results confirm an important connexion between the effective number of spin-wave modes involved and the Lyapunov dimension of the attractors.

关键词： dimension Lyapunov exponent

Substrate,Hormone,Winnowing,and Stratification Influence the Seed Germination of Ilex asprella(*** Arn.)*** Benth

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Phyton-International Journal of Experimental Botany 2023年第7期92卷 2105-2116页

作者： yuquan Huang Fan Wei QingMa Yang Lin Jinpeng Huang Yanxia Zhu Danfeng Tang Guangxi Key Laboratory of Medicinal Resources Protection and Genetic Improvement Guangxi Botanical Garden of Medicinal PlantsNanning530000China Research and Development Center China Resources Sanjiu Medical&Pharmaceutical Co.Ltd.Shenzhen518000China

Ilex asprella(*** Arn.)*** Benth is one of the most important traditional Chinese medicines in southern *** seeds of Ilex asprella usually have extremely low germination due to their dormancy characteristics,which severely impacts the efficiency of seedling raising and increases labor *** this study,to improve the seed germination of ***,the effects of germination substrate,hormone,winnowing,and stratification treatments on the seed germination of *** were *** results of the germination matrix showed that the highest germination percentage of 45.2%was achieved under the 20℃/10℃day/night temperature and vermiculite germination medium *** results of hormone treatments revealed that 100–400 mg/L of gibberellin(GA)and 50–100 mg/L of salicylic acid(SA)were found to be effective in releasing the dormancy of *** ***,winnowing could effectively eliminate unsaturated seeds and impurities,thus improving the seed germination of ***,warm temperature(15℃)stratification could expand the temperature range of ***’s seed germination,which was beneficial for seed germination of *** and for seed nursery at room temperature in production *** present study obtained a method to break dormancy and increase seed germination in ***,thereby forming a groundwork for improving the efficiency of large-scale planting of ***.

关键词： Ilex asprella seed germination substrate winnowing hormone stratification

Estimation of evapotranspiration from artificial forest in mountainous areas of western Loess Plateau based on HYDRUS-1D model

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Journal of Arid Land 2024年第12期16卷 1664-1685页

作者： LU Rui ZHANG Mingjun ZHANG Yu QIANG yuquan CHE Cunwei SUN Meiling WANG Shengjie College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730070China Key Laboratory of Resource Environment and Sustainable Development of Oasis Gansu ProvinceLanzhou 730070China

Evapotranspiration is the most important expenditure item in the water balance of terrestrial ecosystems,and accurate evapotranspiration modeling is of great significance for hydrological,ecological,agricultural,and water resource *** forests are an important means of vegetation restoration in the western Loess Plateau,and accurate estimates of their evapotranspiration are essential to the management and development of water use strategies for artificial *** study estimated the soil moisture and evapotranspiration based on the HYDRUS-1D model for the artificial Platycladus orientalis(L.)Franco forest in western mountains of Loess Plateau,China from 20 April to 31 October,***,the influence factors were identified by combining the correlation coefficient method and the principal component analysis(PCA)*** results showed that HYDRUS-1D model had strong applicability in portraying hydrological processes in this area and revealed soil water surplus from 20 April to 31 October,*** soil water accumulation was 49.64 mm;the potential evapotranspiration(ET_(p))was 809.67 mm,which was divided into potential evaporation(E_(p);95.07 mm)and potential transpiration(T_(p);714.60 mm);and the actual evapotranspiration(ET_(a))was 580.27 mm,which was divided into actual evaporation(E_(a);68.27 mm)and actual transpiration(T_(a);512.00 mm).From April to October 2023,the ET_(p),E_(p),T_(p),ET_(a),E_(a),and T_(a) first increased and then decreased on both monthly and daily scales,exhibiting a single-peak type *** average ratio of T_(a)/ET_(a) was 0.88,signifying that evapotranspiration mainly stemmed from transpiration in this *** ratio of ET_(a)/ET_(p) was 0.72,indicating that this artificial forest suffered from obvious drought *** ET_(p) was significantly positively correlated with ET_(a),and the R^(2) values on the monthly and daily scales were 0.9696 and 0.9635(P<0.05),***,ET_(a) was significantly

关键词： potential evapotranspiration actual evapotranspiration evaporation transpiration HYDRUS-1D model Loess Plateau soil water content