检索结果-南通市图书馆

Improvement of Microstructure and Mechanical Properties of Rapid Cooling Friction Stir-welded A1050 Pure Aluminum

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 134-141页

作者：许楠 LIU Lutao SONG Qining ZHAO Jianhua bao Yefeng College of Materials Science and Engineering Hohai UniversityChangzhou 213200China

Two-mm thick A1050 pure aluminum plates were successfully joined by conventional and rapid cooling friction stir welding(FSW), respectively. The microstructure and mechanical properties of the welded joints were investigated by electron backscatter diffraction characterization, Vickers hardness measurements, and tensile testing. The results showed that liquid CO_(2) coolant significantly reduced the peak temperature and increased the cooling rate, so the rapidly cooled FSW joint exhibited fine grains with a large number of dislocations. The grain refinement mechanism of the FSW A1050 pure aluminum joint was primarily attributed to the combined effects of continuous dynamic recrystallization, grain subdivision, and geometric dynamic recrystallization. Compared with conventional FSW, the yield strength, ultimate tensile strength, and fracture elongation of rapidly cooled FSW joint were significantly enhanced, and the welding efficiency was increased from 80% to 93%. The enhanced mechanical properties and improved synergy of strength and ductility were obtained due to the increased dislocation density and remarkable grain refinement. The wear of the tool can produce several WC particles retained in the joint, and the contribution of second phase strengthening to the enhanced strength should not be ignored.

关键词： aluminum alloy friction stir welding recrystallization microstructure mechanical properties

Improving the accuracy of precipitation estimates in a typical inland arid area of China using a dynamic Bayesian model averaging approach

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2024年第3期16卷 331-354页

作者： XU Wenjie DING Jianli bao Qingling WANG Jinjie XU Kun College of Geography and Remote Sensing Sciences Xinjiang UniversityUrumqi 830017China Key Laboratory of Smart City and Environment Modelling of Higher Education Institute Xinjiang UniversityUrumqi 830017China

Xinjiang Uygur Autonomous Region is a typical inland arid area in China with a sparse and uneven distribution of meteorological stations,limited access to precipitation data,and significant water *** and integrating precipitation datasets from different sources to accurately characterize precipitation patterns has become a challenge to provide more accurate and alternative precipitation information for the region,which can even improve the performance of hydrological *** study evaluated the applicability of widely used five satellite-based precipitation products(Climate Hazards Group InfraRed Precipitation with Station(CHIRPS),China Meteorological Forcing Dataset(CMFD),Climate Prediction Center morphing method(CMORPH),Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record(PERSIANN-CDR),and Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis(TMPA))and a reanalysis precipitation dataset(ECMWF Reanalysis v5-Land Dataset(ERA5-Land))in Xinjiang using ground-based observational precipitation data from a limited number of meteorological *** on this assessment,we proposed a framework that integrated different precipitation datasets with varying spatial resolutions using a dynamic Bayesian model averaging(DBMA)approach,the expectation-maximization method,and the ordinary Kriging interpolation *** daily precipitation data merged using the DBMA approach exhibited distinct spatiotemporal variability,with an outstanding performance,as indicated by low root mean square error(RMSE=1.40 mm/d)and high Person's correlation coefficient(CC=0.67).Compared with the traditional simple model averaging(SMA)and individual product data,although the DBMA-fused precipitation data were slightly lower than the best precipitation product(CMFD),the overall performance of DBMA was more *** error analysis between DBMA-fused precipitation dataset and the more advanced Inte

关键词： precipitation estimates satellite-based and reanalysis precipitation dynamic Bayesian model averaging streamflow simulation Ebinur Lake Basin Xinjiang

Laser-assisted grinding of RB-SiC composites:Laser ablation behavior and mechanism

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第1期37卷 362-376页

作者： Zhigang DONG Wenchao SUN Xintong CAI Feng YANG Yan bao Renke KANG Dongjiang WU Guangyi MA Fangyong NIU Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Laser ablation is an important process during Laser-Assisted Grinding(LAG)of hard and brittle *** realize controllable material removal during laser ablation of RB-SiC composites,ablation experiments under different Laser Energy Density(LAED)and LAG experiments are *** rules and mechanism of physical phase,ablation morphology and crack characteristics caused by laser irradiation are *** forces of LAG and Conventional Grinding(CG)are *** results show that ablation surface changes from slight oxidation to obvious material removal with LAED increasing,and ablation depth increases *** ablation products change from submicron SiO_(2)particles to nanoscale particles and *** LAED promotes SiC decomposition and sublimation,which leads to the increase of C *** SiC phase forms corrugated shape in recast layer and columnar shape in Heat Affected Zone(HAZ)at 56 J/mm^(2).The cold and heat cycle leads to formation of fishbone *** ablation specimen under 30 J/mm^(2),the grinding force can be reduced by a maximum of 39%and brittle damage region is *** material removal and microcrack generated will significantly reduce the hardness and improve machinability,which can promote grinding efficiency.

关键词： RB-SiC Laser Ceramic Composites Grinding

Precipitation Evolution from Plain to Mountains during the July 2023 Extreme Heavy Rainfall Event in North China

在线全文

学校读者我要写书评

暂无评论

Journal of Meteorological Research 2024年第4期38卷 635-651页

作者： Mingxin LI Jisong SUN Feng LI Chong WU Rudi XIA Xinghua bao Jinfang YIN Xudong LIANG State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

North China experienced devastating rainfall from 29 July to 1 August 2023,which caused substantial flooding and *** study analyzed observations from surface rain gauges and S-band dual-polarization radars to reveal the following unique features of the precipitation evolution from the plain to the mountains during this event.(1) The total rainfall was found concentrated along the Taihang Mountains at elevations generally > 200 m,and its spatiotemporal evolution was closely associated with northward-moving low-level jets.(2) Storms propagated northwestward with southeasterly steering winds,producing continuous rainfall along the eastern slopes of the Taihang Mountains owing to mountain blocking,which resulted in the formation of local centers of precipitation ***,most rainfall episodes with an extreme hourly rainfall rate(HRR),corresponding to large horizontal wind shear at low levels,actively occurred in the plain area to the east of the Taihang Mountains.(3) The western portion of the extreme heavy rain belt in the north was mainly caused by long-lasting cumulus–stratus mixed precipitation with HRRmm h~(-1);the eastern portion was dominated by short-duration convective precipitation with HRR > 20 mm h~(-1).The contributions of convective precipitation and cumulus–stratus mixed precipitation to the total rainfall of the southern and middle rain belts were broadly equivalent.(4) The local HRR maxima located at the transition zone from the plain to the mountains were induced by moderate storm-scale convective cells with active warm-rain processes and large number of small-sized rain droplets.(5) During the devastating rainfall event,it was observed that the rainfall peaked at around 1800 local time(LT) every day over the upstream plain area(no diurnal cycle of rainfall was observed in relation to the accumulated rainfall centers over mountain areas).This was attributable to convective activities along the storm propagation path,which was a resu

关键词： extreme rainfall from plain to mountains convective precipitation stratiform precipitation hourly rainfall rate low-level jet diurnal variation

Early changes in corneal densitometry after FS-LASIK combined with accelerated corneal cross-linking for correction of high myopia

在线全文

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2024年第7期17卷 1307-1312页

作者： Qing-bao Wang Hong-Sheng Bi Xiao-Fan Wang Hua Fan Li Li Peng Ji Shandong University of Traditional Chinese Medicine Jinan 250014Shandong ProvinceChina Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine Shandong Clinical Medicine Research CenterJinan 250002Shandong ProvinceChina Shandong Academy of Eye Disease Prevention and Therapy Shandong Provincial Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Therapy of Ocular DiseasesJinan 250002Shandong ProvinceChina

AIM:To observe the effects of femtosecond laserassisted excimer laser in situ keratomileusis combined with accelerated corneal cross-linking(FS-LASIK Xtra)on corneal densitometry after correcting for high ***:In this prospectively study,130 patients underwent FS-LASIK or FS-LASIK Xtra for high *** right eyes were selected for inclusion in the study,of which 65 cases of 65 eyes in the FS-LASIK group,65 patients with 65 eyes in the FS-LASIK Xtra *** were evaluated for corneal densitometry at 1,3,and 6mo postoperatively using Pentacam Scheimpflug ***:Preoperative differences in corneal densitometry between the FS-LASIK and FS-LASIK Xtra groups in different ranges were not statistically significant(P>0.05).Layer-by-layer analysis revealed statistically significant differences in the anterior(120μm),central,and total layer corneal densitometry between the FS-LASIK and FS-LASIK Xtra groups at 1 and 3mo postoperatively(all Pmm(both Pmm(P0.05).CONCLUSION:There is an increase in internal corneal densitometry during the early postoperative period after FS-LASIK Xtra for correction of high ***,the densitometry values decreased to the level of conventional FS-LASIK at 6mo after surgery,with the most significant changes observed in the superficial central zone.

关键词： femtosecond laser accelerated corneal cross-linking corneal densitometry high myopia femtosecond laser in situ keratomileusis

A seven-crystal spectrometer for high-energy resolution X-ray spectroscopy at Shanghai Synchrotron Radiation Facility

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第9期35卷 82-91页

作者： Bing-bao Mei Liang-Xin Wang Song-Qi Gu Xiao-Zhi Su Shuo Zhang Yao Wei Jing-Yuan Ma Zheng Jiang Fei Song Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201800China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230026China

A Johann-type X-ray spectrometer was successfully developed at the hard X-ray branch(in-vacuum undulator with a 24-mm periodic length)of the energy material beamline(E-line)at the Shanghai Synchrotron Radiation Facility(SSRF).This spectrometer was utilized to implement X-ray emission spectroscopy(XES),high-energy resolution fluorescence-detected X-ray absorption spectroscopy(HERFD-XAS),and resonant inelastic X-ray *** spherically bent crystals were positioned on the respective vertical 500-mm-diameter Rowland circles,adopting an area detector to increase the solid angle to 1.75%of 4πsr,facilitating the study of low-concentrate systems under complex reaction *** under the atmosphere pressure,the spectrometer covers the energy region from 3.5 to 18 keV,with the Bragg angle ranging from 73°to 86°during vertical *** offers a promised energy resolution of sub-eV(XES)and super-eV(HERFD-XAS).Generally,these comprehensive core-level spectroscopy methods based on hard X-rays at the E-line with an extremely high photon flux can meet the crucial requirements of a green energy ***,they provide substantial support for scientific advances in fundamental research.

关键词： X-ray emission spectroscopy High-energy-resolution X-ray spectrometer Johann geometry Energy materials SSRF

Increasing root-lower characteristics improves drought tolerance in cotton cultivars at the seedling stage

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2024年第7期23卷 2242-2254页

作者： Congcong Guo Hongchun Sun Xiaoyuan bao Lingxiao Zhu Yongjiang Zhang Ke Zhang Anchang Li Zhiying Bai Liantao Liu Cundong Li State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Crop Growth Regulation of Hebei Province/College of Agronomy Hebei Agricultural UniversityBaoding 071001China

Drought is an important abiotic stress factor in cotton *** root system architecture(RSA)of cotton shows high plasticity which can alleviate drought-related stress under drought stress(DS)conditions;however,this alleviation is cultivar ***,this study estimated the genetic variability of RSA in cotton under *** the paper-based growth system,we assessed the RSA variability in 80 cotton cultivars at the seedling stage,with 0 and10%polyethylene glycol 6000(PEG6000)as the control(CK)and DS treatment,*** analysis of 23 aboveground and root traits in the 80 cotton cultivars revealed different responses to *** the 10th day after DS treatment,the degree of variation in the RSA traits under DS(5–55%)was greater than that of CK(5–49%).The 80 cultivars were divided into drought-tolerant cultivars(group 1),intermediate drought-tolerant cultivars(group 2),and drought-sensitive cultivars(group 3)based on their comprehensive evaluation values of drought *** DS,the root lengthlower,root area-lower,root volume-lower,and root length density-lower were significantly reduced by 63,71,76,and 4%in the drought-sensitive cultivars compared to ***,the drought-tolerant cultivars maintained their root lengthlower,root area-lower,root volume-lower,and root length density–lower *** to CK,the root diameter(0–2 mm)-lower increased by 21%in group 1 but decreased by 3 and 64%in groups 2 and 3,respectively,under ***,the drought-tolerant cultivars displayed a plastic response under DS that was characterized by an increase in the root-lower *** resistance was positively correlated with the root area-lower and root length ***,the RSA of the different cotton cultivars varied greatly under ***,important root traits,such as the root-lower traits,provide great insights for exploring whether drought-tolerant cotton cultivars can effectively withstand adverse environment

关键词： cotton root system architecture drought stress cultivars variability root-lower

Two-year longitudinal change in choroidal and retinal thickness in school-aged myopic children:exploratory analysis of clinical trials for myopia progression

在线全文

学校读者我要写书评

暂无评论

Eye and Vision 2024年第4期10卷 1-10页

作者： Meiping Xu Xinping Yu Minghui Wan Kemi Feng Junxiao Zhang Meixiao Shen BjÖrn Drobe Hao Chen Jia Qu Jinhua bao Eye Hospital and School of Ophthalmology and Optometry Wenzhou Medical UniversityWenzhouZhejiangChina National Clinical Research Center for Ocular Diseases WenzhouZhejiangChina. WEiRC WMU-Essilor International Research CenterWenzhouZhejiangChina R&D Vision Sciences AMERA EssilorInternationalSingaporeSingapore

Background:With increasing axial length(AL)and myopia progression,the micro-structure of the retina and choroid gradually *** study describes the longitudinal changes in retinal and choroidal thickness in school-aged children with myopia and explores the relationship between changes in choroidal thickness and myopia ***:An exploratory analysis of a randomized trial was ***(n=168,aged 7 to 12 years)with myopia from-0.75 diopter(D)to-4.00 D were enrolled in this prospective longitudinal *** refraction,AL,retinal and choroidal thicknesses were measured at baseline and at 1-and 2-year follow-ups."Rapid progression myopia"was defined as increasing in myopia>1.00 D and'"stable progression myopia"was≤1.00 D during the 2-year *** affecting the changes in choroidal thickness were analysed using linear mixed ***:AL significantly increased by 0.67±0.24 mm with a myopic shift of-1.50±0.64 D over the 2 *** overall retinal thickness increased from 251.12±15.91μm at baseline to 253.47±15.74μm at the 2-year followup(F=23.785,Pmm,P=0.002)and sex(β=-17.258,P=0.001).Choroidal thickness continued to decrease in subjects with rapid progression(F=92.06,P<0.001)but not in those with steady progression(F=2.23,P=0.119).Conclusion:Significant choroidal thinning was observed and was associated with rapid progression and *** findings indicate a need to understand the role of the choroid in eye growth and myopia ***/Precis:The macular choroidal thickness of myopic children is relevant to different degrees of myopic progression in this 2-year longitudinal *** findings suggest that control of choroidal thickness might work to regulate human ocular growth.

关键词： Axial length Choroidal thickness Children Myopia Spectral-domain optical coherence tomography

可卡因暴露通过miR-30C-5P/苹果酸酶1/活性氧通路升高血压和加强主动脉僵硬度

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中华高血压杂志 2018年第4期26卷 368-368页

作者：刘莉叶鹏 Zhu W Wang H Wei J Sartor GC bao mm Pierce CT Wahlestedt CR Dykxhoorn DM Dong C

滥用可卡因可增加心血管病死亡和发病风险,然而,其中潜在的分子机制仍然未知。通过可卡因滥用小鼠模型,Zhu等发现重复注射可卡因可导致小鼠血压升高和主动脉僵硬度增加（主动脉中活性氧水平同时升高）,这种现象类似于人类高血压中观察... 详细信息

滥用可卡因可增加心血管病死亡和发病风险,然而,其中潜在的分子机制仍然未知。通过可卡因滥用小鼠模型,Zhu等发现重复注射可卡因可导致小鼠血压升高和主动脉僵硬度增加（主动脉中活性氧水平同时升高）,这种现象类似于人类高血压中观察到的现象。

关键词：主动脉僵硬度可卡因滥用升高血压活性氧果酸酶通路小鼠模型发病风险