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10 watt-level tunable narrow linewidth 1.5μm all-fiber amplifier

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High Power Laser Science and Engineering 2018年第2期6卷 149-153页

作者： ni Tang Zhiyue Zhou Zhixian Li Zefeng Wang College of Advanced Interdisciplinary StudiesNational University of Defense TechnologyChangsha 410073China Hunan Provincial Collaborative Innovation Center of High Power Fiber Laser Changsha 410073China Hunan Provincial Key Laboratory of High Energy Laser Technology Changsha 410073China

We report here a high-power, wavelength tunable and narrow linewidth 1.5 μm all-fiber laser amplifier based on a tunable diode laser and Er-Yb co-doped fibers. The laser wavelength can be precisely tuned from 1535 nm to 1580 nm, which covers many absorption lines of mid-infrared laser gases, such as C2 H2, HCN, CO, and HI. The maximum laser power is >11 W, and the linewidth is about 200–300 mHz, which is close to the absorption linewidth of the above-mentioned gases. This work provides a suitable pump source for high-power wavelength tunable mid-infrared fiber gas lasers based on low-loss hollow-core fibers.

关键词： Er-doped fibers fiber amplifier fiber lasers high power narrow linewidth

Two-phase sink vortex suction mechanism and penetration dynamic characteristics in ladle teeming process

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Journal of Iron and Steel Research International 2017年第7期24卷 669-677页

作者： Da-peng Tan Ye-sha ni Li-bin Zhang Key Laboratory of E & m Ministry of Education & Zhejiang ProvinceZhejiang University of Technology

At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten *** address this issue,a twophase fluid mechanical modeling method for ladle teeming was ***,a dynamic model for vortex suction process was built,and the profiles of vortex flow field were ***,based on the level set method（LSm）,a two-phase 3Dinterface coupling model for slag entrapment was ***,in combination with high-order essentially non-oscillatory（ENO）and total variation dim.nishing（TVD）methods,a LSm-based numerical solution method was proposed to obtain the 3Dcoupling evolution regularities in vortex suction *** results show that the vortex with higher kinetic energy can form an expanded sandglass-shape region with larger slag fraction and lower rotating velocity;there is a pressure oscillation phenomenon at the vortex penetration state,which is caused by the energy shock of two-phase vortex penetration coupling.

关键词： Ladle teeming Sink vortex Suction mechanism Two-phase coupling Level set method Pressure oscillation

Influence of topography,soil properties and plant comm.nity on the biomass of Abies georgei *** seedlings in Southeast Tibet

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Journal of mountain Science 2022年第9期19卷 2664-2677页

作者： ZHANG Xin-sheng ZHOU Chen-ni LU Jie Institute of Tibet Plateau Ecology Tibet Agricultural&Animal Husbandry UniversityNyingchi 860000China Key Laboratory of Forest Ecology in Tibet Plateau Tibet Agricultural&Animal Husbandry UniversityMinistry of EducationNyingchi 860000China Linzhi National Forest Ecosystem Observation&Research Station of Tibet Nyingchi 860000China Key Laboratory of Alpine Vegetation Ecological Security in Tibet Nyingchi 86000China

Biomass of seedlings at different developing stages of growth is important information for studying the response of species to site *** objectives of this study was to explore the distribution characteristics of AGB(above-ground biomass)and BGB(below-ground biomass)of Abies georgei *** seedlings of different ages,and investigate the effects of topography(slope aspect,altitude),plant comm.nity characteristics(crown density,species diversity,etc.),and soil properties(soil physical and chemical properties)on the biomass and its *** in five age classes(1–2,3–4,5–6,7–8,and 9–10 years old)were collected by full excavation from 6 elevations(3800 m,3900 m,4000 m,4100 m,4200 m,4300 m)on the north and south slopes of Sejila mountain in Tibet.15seedlings of each age class were investigated at one *** individual effects of seedling age(SA)and the interaction effects of SA,slope aspect(SL),and elevation(EG),namely,SL×EG,SL×SA,EG×SA,and SL×EG×SA,had significant effects on the AGB of the seedlings(pnificantly affected by SA(pmial growth trend with the increase in seedling age,and had an allometric relationship at different elevations,α(allometric exponential)varied from 0.913 to 1.046 in the northern slope,and from 1.004 to 1.268 in the southern *** biomass of seedlings on the northern slope was remarkably affected by stand factors,with a contribution rate of 47.8%,whereas that on the southern slope was considerably affected by soil factors with a contribution rate of 53.2%.The results showed that age was the most important factor affecting seedling *** allometric pattern of seedling biomass was relatively stable,but in a highaltitude habitat,*** *** seedlings increased the input of *** seedling biomass allocation and its influencing factors is useful for evaluating plants’ability to acquire resources and surviv

关键词： Biomass allocation Allometric relationship Stand characteristic Soil factors Abies georgei var.smithii seedlings Sejila mountain,Tibet

Two mADS-box proteins,AGL9 and AGL15,recruit the FIS-PRC2 complex to trigger the phase transition from endosperm proliferation to embryo development in Arabidopsis

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molecular Plant 2024年第7期17卷 1110-1128页

作者： Shen Zhang Devasantosh mohanty Adnan muzaffar min ni Department of Plant and microbial Biology University of Minnesota at Twin CitiesSaint PaulMinnesota MN 55108United States of AmericaUSA

Spatiotemporal regulation of gene expression by polycomb repressive complex 2(PRc2)is critical for animal and plant *** Arabidopsis fertilization independent seed(FIS)-PRC2 complex functions specifically during plant reproduction from gametogenesis to seed *** a double fertilization event,triploid endosperm proliferates early,followed by the growth of a diploid embryo,which replaces the endosperm in Arabidopsis and many *** genes critical for endosperm proliferation such as IKkU2 and m.ni3 are activated after *** we report that two mADS-box AGAmOUS-LIKE(AGL)proteins associate with the key endosperm proliferation loci and recruit the FIS-PRC2 repressive complex at 4-5 days after pollination(DAP).Interestingly,AGL9 and AGL15 only accumulate toward the end of endosperm proliferation at 4-5 DAP and promote the deposition of H3K27me3 marks at key endosperm proliferation *** of AGL9 and AGL15 or overexpression of AGL9 or AGL15 significantly influence endosperm proliferation and ***-wide analysis with cleavage Under Targets and tagmentation(CUT&Tag)sequencing and RNA sequencing revealed the landscape of endosperm H3K27me3 marks and gene expression profiles in Col-0 and agl9 ***&Tag qPCR also demonstrated the occupancy of the two mADS-box proteins and FIS-PRC2 on a few representative target *** studies suggest that mADS-box proteins could potentially recruit PRc2 to regulate many other developmental processes in plants or even in fungi and animals.

关键词： AGL9 AGL15 embryo endosperm IKU2 mEDEA m.ni3

Near surface velocity and Q_s structure of the Quaternary sediment in Bohai basin,China

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Earthquake Science 2009年第5期22卷 451-458页

作者： Jiajun Chong Sidao ni mengcheng National Geophysical Observatory University of Science and Technology of China Hefei 230026 China

Heavily populated by Beijing and Tianjin cities, Bohai basin is a seismically active Cenozoic basin suffering from huge lost by devastating earthquakes, such as Tangshan earthquake. The attenuation （Qp and Qs） of the surficial Quaternary sediment has not been studied at natural seismic frequency （1-10 Hz）, which is crucial to earthquake hazards study. Borehole seismic records of micro earthquake provide us a good way to study the velocity and attenuation of the surficial structure （0-500 m）. We found that there are two pulses well separated with simple waveforms on borehole seismic records from the 2006 mw4.9 Wen＇an earthquake sequence. Then we performed waveform modeling with generalized ray theory （GRT） to confirm that the two pulses are direct wave and surface reflected wave, and found that the average vp and Vs of the top 300 m in this region are about 1.8 km/s and 0.42 km/s, leading to high ve/vs ratio of 4.3. We also modeled surface refleeted wave with propagating matrix method to constrain Qs and the near surface velocity structure. Our modeling indicates that Qs is at least 30, or probably up to 100, much larger than the typically assumed extremely low Q（-10）, but consistent with Qs modeling in mississippi embayment. Also, the velocity gradient just beneath the free surface （0-50 m） is very large and velocity increases gradually at larger depth. Our modeling demonstrates the importance of borebole seismic records in resolving shallow velocity and attenuation structure, and hence may help in earthquake hazard simulation.

关键词： Bohai basin Quaternary sediment near surface velocity Qs borehole records

mapping soil nutrients via different covariates combinations:theory and an example from morocco

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Ecological Processes 2022年第1期11卷 302-318页

作者： Kingsley John Yassine Bouslihim Isong Abraham Isong Lahcen Hssaini Rachid Razouk Ndiye m.Kebonye prince C.Agyeman Vit Penížek Tereza Zádorová Department of Soil Science and Soil Protection Faculty of AgrobiologyFoodand Natural ResourcesCzech University of Life SciencesKamýcká12916500 PragueCzech Republic National Institute of Agricultural Research RabatMorocco Department of Soil Science University of CalabarCalabarNigeria

Background:mapping of soil nutrients using different covariates was carried out in northern *** study was undertaken in response to the region’s urgent requirement for an updated soil *** aimed to test various covariates combinations for predicting the variability in soil properties using ordinary kriging and kriging with external ***:A total of 1819 soil samples were collected at a depth of 0–40 cm using the 1-km grid sampling *** were screened for their pH,soil organic matter(SOm),potassium(K_(2)O),and phosphorus(P_(2)O_(5))using standard laboratory *** attributes(T)computed using a 30-m resolution digital elevation model,bioclimatic data(C),and vegetation indices(V)were used as covariates in the *** targeted soil property was modeled using covariates separately and then combined(e.g.,pH~T,pH~C,pH~V,and pH~T+C+V).k=tenfold cross-validation was applied to examine the performance of each employed *** statistical parameter RmSE was used to determine the accuracy of different ***:The pH of the area is slightly above the neutral level with a corresponding 7.82%of SOm,290.34 ppm of K_(2)O,and 100.86 ppm of P_(2)O_(5).This was used for all the selected targeted soil *** a result,the studied soil properties showed a linear relationship with the selected ***,SOm,and K 2O presented a moderate spatial autocorrelation,while P2O5 revealed a strong *** cross-validation result revealed that soil pH(RmSE=0.281)and SOm(RmSE=9.505%)were best predicted by climatic variables.P_(2)O_(5)(RmSE=106.511 ppm)produced the best maps with climate,while K_(2)O(RmSE=209.764 ppm)yielded the best map with terrain ***:The findings suggest that a combination of too many environmental covariates might not provide the actual variability of a targeted soil *** demonstrates that specific covariates with close relationships with certain soil properties might perform bet

关键词： Soil mapping Environmental variables Agriculture Soil properties Soil management

Conversion of CO_(2) and H_(2) into propane over InZrO_(x) and SSZ-13 composite catalyst

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Journal of Energy Chemistry 2021年第3期30卷 111-117页

作者： Zhaopeng Liu Youming ni Tantan Sun Wenliang Zhu Zhongmin Liu National Engineering Laboratory for methanol to Olefins Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Dalian National Laboratory for Clean Energy Delian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100049China

Direct converting carbon dioxide into hydrocarbon fuels and value-added chemicals would offer a very attractive approach for efficient utilization of CO_(2) as a carbon ***,olefins,aromatics and gasoline have been successfully synthesized by CO_(2) hydrogenation,highly selective conversion of CO_(2) and H_(2) into C_(2+)hydrocarbon is still challenging due to a high C-C coupling barrier and inhibiting the production of other long-chain ***,we report a composite catalyst made of InZrO_(x) and SSZ-13 molecular sieve(InZrO_(x)+SSZ-13),which exhibits 74.5% propane selectivity at 623 *** 8-mR micropores and the higher strength of the acid for SSZ-13 benefit the formation of *** with pure InO_(x) and m-ZrO_(2) the composite oxide InZrO_(x) containing more oxygen vacancies,exhibits to be more readily reduced by H_(2) and easier to adsorb and desorb CO_(2) within the reaction *** those could be beneficial to the activation and conversion of H_(2) and CO_(2).The catalytic performance of InZrO_(x)+SSZ-13 in CO_(2) hydrogenation provides a potential for production of propane.

关键词： CO_(2)hydrogenation InZrO_(x)+SSZ-13 Propane Oxygen vacancies Acid strength

Serrated chip characteristics and formation mechanism in high-speed machining of selective laser melted Ti6Al4V alloys

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Science China(Technological Sciences) 2023年第5期66卷 1435-1450页

作者： LIU DeJian WANG YouQiang ni ChenBing ZHU LiDa ZHENG ZhongPeng School of mechanical and Automotive Engineering Qingdao University of TechnologyQingdao266520China Key Lab of Industrial Fluid Energy Conservation and Pollution Control Ministry of EducationQingdao266520China School of mechanical Engineering and Automation Northeastern UniversityShenyang110819China School of mechanical Engineering Tsinghua UniversityBeijing100084China

Serrated chips,consisting of extremely uneven plastic deformation,are a prominent feature of high-speed machining of difficultto-machine *** paper focuses on the evolution of chip form,chip morphology features(chip free surface,tool-chip contact surface,and chip edge),and chip segment parameters in subsequent high-speed(vc=50 and 150 m min-1)machining of selective laser melted(SLmed)Ti6Al4V alloys,which are significantly different from conventional Ti6Al4V alloy in microstructure,mechanical properties and *** effect of laser beam scanning schemes(0°,67.5°,and 90°),machined surfaces(top and front),and cutting speeds on serrated chip characteristics of SLmed Ti6Al4Valloys was *** on the Johnson-Cook constitutive model of SLmed Ti6Al4Valloys,an orthogonal cutting model was developed to better understand the effect of physical-mechanical properties on the shear localization,which dominates the formation mechanism of serrated chips in post-machining of SLmed Ti6Al4V *** results showed that the critical cutting speed(CCS)for chip serration of SLmed Ti6Al4V alloy is lower than that for serrated chips of conventional Ti6Al4V alloy,and the serrated profile of SLmed Ti6Al4V chips was more regular and ***,due to anisotropic microstructure and mechanical properties of SLmed Ti6Al4Valloys,the serration degree of chips produced on the top surfaces of SLmed Ti6Al4Valloys is more prominent than that of chips generated on the front *** addition,because of the poor deformation coordination and high plastic flow stresses of needle-like martensiteα′,the plastic flow and grain distortion in the adiabatic shear band(ASB)of SLmed Ti6Al4V chips are significantly smaller than those in the ASB of conventional Ti6Al4V with equiaxed grains.

关键词： serrated chips selective laser melted Ti6Al4V alloys high-speed machining chip characteristics anisotropic properties

ABRUPT DEFLECTED SUPERCRITICAL WATER FLOW IN SLOPED CHANNELS

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Journal of Hydrodynamics 2008年第3期20卷 293-298页

作者： LIU Ya-kun ni Han-gen State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024China

The effect of the bottom slope on abrupt deflected supercritical water flow was experimentally and theoretically studied. model tests were conducted in a flume of 1.2 m wide and 2.6 m long with sloped bottom at an angle 35.54°, its length of deflector was 0.2 m and the deflection angles were 15° and 30°. An approximate method for calculating the shock wave angle and depth ratio of the abrupt deflected supercritical water flow was suggested, and a correction coefficient for the hydrodynamic pressure was introduced to generalize the momentum equation in the direction perpendicular to the shock front. It must be noticed that in the sloped channel the shock wave angle and the depth ratio are no longer constant as those in the horizontal channels, but slowly change along the shock front. The calculated results are in good agreement with measured data.

关键词： shock wave abrupt deflection of supercritical water flow slopping channel