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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1089-1097页

作者： jianjun xu Hanlin Ding Xin Lin Feng Liu Analytical&Testing Center Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples subjected to IDED under 1050℃ preheating with and without hot isostatic pressing(HIP,1190℃,105 MPa,and 3 h).Results show that the as-deposited sample mainly consisted of epitaxial columnar crystals and inhomogeneously distributed γ’ phases in interdendritic and dendritic core regions.After HIP,grain morphology changed negligibly,whereas the size of the γ’ phase became increasingly even.After further heat treatment(HT,1070℃,2 h + 845℃,24 h),the γ’ phase in the as-deposited and HIPed samples presented a bimodal size distribution,whereas that in the as-deposited sample showed a size that remained uneven.The comparison of tensile properties revealed that the tensile strength and uniform elongation of the HIP + HTed sample increased by 5% and 46%,respectively,due to the synergistic deformation of bimodal γ’phases,especially large cubic γ’ phases.Finally,the relationship between phase transformations and plastic deformations in the IDEDed sample was discussed on the basis of generalized stability theory in terms of the trade-off between thermodynamics and kinetics.

关键词： directed energy deposition Ni-based superalloys high-temperature preheating hot isostatic pressing microstructure tensile properties

Combinatorial Optimization of Physics Parameterization Schemes for Typhoon Simulation Based on a Simple Genetic Algorithm(SGA)

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Journal of Meteorological Research 2024年第1期38卷 10-26页

作者： Zebin LU jianjun xu Zhiqiang CHEN Jinyi YANG Jeremy Cheuk-Hin LEUNG Daosheng xu Banglin ZHANG China Meteorological Administration–Guangdong Ocean University Joint Laboratory for Marine Meteorology South China Sea Institute of Marine MeteorologyGuangdong Ocean UniversityZhanjiang 524088 College of Ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088 Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological AdministrationGuangzhou 510640 Shenzhen Institute of Guangdong Ocean University Shenzhen 518120 College of Atmospheric Science Lanzhou UniversityLanzhou 730000

Each physical process in a numerical weather prediction(NWP)system may have many different parameterization schemes.Early studies have shown that the performance of different physical parameterization schemes varies with the weather situation to be simulated.Thus,it is necessary to select a suitable combination of physical parameterization schemes according to the variation of weather systems.However,it is rather difficult to identify an optimal combination among millions of possible parameterization scheme combinations.This study applied a simple genetic algorithm(SGA)to optimizing the combination of parameterization schemes in NWP models for typhoon forecasting.The feasibility of SGA was verified with the simulation of Typhoon Mujigae(2015)by using the Weather Research and Forecasting(WRF)model and Typhoon Higos(2020)by using the Coupled Ocean–Atmosphere–Wave–Sediment Transport(COAWST)modeling system.The results show that SGA can efficiently obtain the optimal combination of schemes.For Typhoon Mujigae(2015),the optimal combination can be found from the 1,304,576 possible combinations by running only 488 trials.Similar results can be obtained for Typhoon Higos(2020).Compared to the default combination proposed by the COAWST model system,the optimal combination scheme significantly improves the simulation of typhoon track and intensity.This study provides a feasible way to search for the optimal combinations of physical parameterization schemes in WRF and COAWST for more accurate typhoon simulation.This can help provide references for future development of NWP models,and for analyzing the coordination and adaptability of different physical process parameterization schemes under specific weather backgrounds.

关键词： simple genetic algorithm(SGA) combinatorial optimization typhoon forecast numerical weather prediction(NWP)

Multi-decadal Changes of the Impact of El Niño Events on Tibetan Plateau Summer Precipitation

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Journal of Atmospheric Science Research 2024年第1期7卷 90-105页

作者： Weinan Jiang Ning Cao Riga Aze jianjun xu College of Ocean and Meteorology Guangdong Ocean UniversityZhanjiangGuangdong524088China CMA-GDOU Joint Laboratory for Marine Meteorology Guangdong Ocean UniversityZhanjiangGuangdong524088China South China Institute of Marine Meteorology(SIMM) Guangdong Ocean UniversityZhanjiangGuangdong524088China Shenzhen Institute of Guangdong Ocean University ShenzhenGuangdong518108China

Precipitation on the Tibetan Plateau(TP)has an important effect on the water supply and demand of the downstream population.Involving recent climate change,the multi-decadal variations of the impact of El Niño-Southern Oscillation(ENSO)events on regional climate were observed.In this work,the authors investigated the changes in summer precipitation over TP during 1950-2019.At the multi-decadal scale,the authors found that the inhabiting impact of El Niño events on the TP summer precipitation has strengthened since the late 1970s.The main factor contributing to this phenomenon is the significant amplification in the decadal amplitude of El Niño during 1978-2019 accompanied by a discernible escalation in the frequency of El Niño events.This phenomenon induces anomalous perturbations in sea surface temperatures(SST)within the tropical Indo-Pacific region,consequently weakening the atmospheric vapor transport from the western Pacific to the TP.Additionally,conspicuous anomalies in subsidence motion are observed longitudinally and latitudinally across the TP which significantly contributes to a curtailed supply of atmospheric moisture.These results bear profound implications for the multi-decadal prediction of the TP climate.

关键词： Tibetan plateau Summer precipitation ENSO Multi-decadal changes Climate variability

Diagnostic Study of an Extreme Explosive Cyclone over the Kuroshio/Kuroshio Extension Region

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Journal of Ocean University of China 2024年第3期23卷 605-617页

作者： ZHANG Shuqin LIAO Qinghua LIU Chunlei GAO Xiaoyu LONG Jingchao LI Pengyuan xu jianjun College of Ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088China South China Sea Institute of Marine Meteorology Guangdong Ocean UniversityZhanjiang 524088China CMA-GDOU Joint Laboratory for Marine Meteorology Guangdong Ocean UniversityZhanjiang 524088China Key Laboratory of Climate Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong ProvinceGuangdong Ocean UniversityZhanjiang 524088China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Department of Marine Meteorology Ocean-Atmosphere Interaction and Climate LaboratoryKey Laboratory of Physical OceanographyOcean University of ChinaQingdao 266100China

Explosive cyclones(ECs)occur frequently over the Kuroshio/Kuroshio Extension region.The most rapidly intensified EC over the Kuroshio/Kuroshio Extension region during the 42 years(1979-2020)of cold seasons(October-April)was studied to reveal the variations of the key factors at different explosive-developing stages.This EC had weak low-level baroclinicity,mid-level cyclonic-vorticity advection,and strong low-level water vapor convergence at the initial explosive-developing stage.The low-level baroclinicity and mid-level cyclonic-vorticity advection increased substantially during the maximum-deepening-rate stage.The diagnostic analyses using the Zwack-Okossi equation showed that diabatic heating was the main contributor to the initial rapid intensification of this EC.The cyclonic-vorticity advection and warm-air advection enhanced rapidly in the middle and upper troposphere and contributed to the maximum rapid intensification,whereas the diabatic heating weakened slightly in the mid-low troposphere.The relative contribution of the diabatic heating decreased from the initial explosive-developing stage to the maximum-deepening-rate stage due to the enhancement of other factors(the cyclonic-vorticity advection and warm-air advection).Furthermore,the physical factors contributing to this EC varied with the explosive-developing stage.The non-key factors at the initial explosive-developing stage need attention to forecast the rapid intensification.

关键词： explosive cyclone diabatic heating cyclonic-vorticity advection rapid intensification the Kuroshio/Kuroshio Extension region

Sensitivity of Typhoon Lingling(2019)simulations to horizontal mixing length and planetary boundary layer parameterizations

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Frontiers of Earth Science 2022年第2期16卷 304-322页

作者： Siqi CHEN Feng xu Yu ZHANG Guiling YE jianjun xu Chunlei LIU College of Ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088China South China Sea Institute of Marine Meteorology Zhanjiang 524088China Shenzhen Institute of Guangdong Ocean University Shenzhen 518120China

Forecasting the intensity of typhoons is a difficult problem in numerical weather prediction.It is subject to many factors,among which the selection of physical parameterization schemes for the model is a hot topic of research.In this study,the effects of horizontal mixing length(represented by h_diff)and planetary boundary layer(PBL)schemes were investigated.Six idealized and four operational sensitivity experiments were designed based on simulation of the typhoon Lingling,which occurred over the western Pacific in 2019,using the Hurricane Weather Research and Forecasting model.The results of the idealized experiments showed that,as h_diff was increased,the slope of the typhoon eye area also increased,and its intensity became stronger.On the other hand,the results of the sensitivity experiments indicated that the intensity of the simulated typhoon was sensitive to the choice of PBL scheme,with the forecast bias of the QNSE(Quasi-Normal Scale Elimination)scheme being smaller than that of the GFDL(Geophysical Fluid Dynamics Laboratory)scheme.Angular momentum budget analyses indicated that,when increasing the h_diff,the convergence of angular momentum was larger in the boundary layer,which led to a faster spin-up of the vortex,further increasing the intensity of the typhoon.From the calculated horizontal and vertical vortex spread it was found that,when the h_diff was increased,the corresponding horizontal and vertical diffusion eddies also showed an increasing trend,which was also the reason for the strengthening of the typhoon.Meanwhile,the forecast bias decreased significantly with increasing horizontal mixing length when using the same PBL scheme.

关键词： Hurricane Weather Research and Forecasting model planetary boundary layer western Pacific typhoon horizontal diffusion

Sandwich ELISA for detecting urinary Survivin in bladder cancer

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Chinese Journal of Cancer Research 2013年第4期25卷 375-381页

作者： xuefeng Li Yaming Wang jianjun xu Qingyun Zhang Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education) Department of Clinical LaboratoryPeking University Cancer Hospital&Institute

Objective： Survivin as a tumor marker in the diagnosis of bladder cancer has not been completely confirmed yet and there are few reports about using Survivin enzyme-linked immunosorbent assay （ELISA） kit to detect the urine of bladder cancer patients. This study aimed to develop a Survivin ELISA and validate its value in the detection of bladder cancer. Methods： Through square matrix titration, different combinations of coating antibody and detecting antibody, a Survivin ELISA was constructed. This assay was evaluated according to intra-assay precision, inter-assay precision and minimum detectable dose （MDD）. Survivin levels were detected and analyzed in 102 bladder cancer patients and 102 healthy people by established ELISA. Then cutoff value was defined according to the analysis of receiver operating characteristic （ROC） curve. The sensitivity and specificity of detection were calculated on the basis of cutoff value to diagnose bladder cancer patients. Furthermore, the value of Survivin expression detected by ELISA among different clinicopathological characteristics of patients was also compared. Results： Through optimization of different conditions, intra-assay precision was 8.39%, inter-assay precision 8.57% and MDD 0.0625 ng/mL in this assay. When the optical density at 450 nm （OD 450 ） was 0.09, it could get the optimized diagnostic cutoff value. According to this value, the sensitivity and specificity of diagnosis in bladder cancer patients were 70.6% and 89.2%, respectively. The associations between patients＇ clinical variables and OD 450 were not significant except tumor numbers in patients. Conclusions： This experiment has preliminarily developed a Survivin ELISA and confirmed Survivin as a biomarker which owned a practical and significant value in the diagnosis of bladder cancer.

关键词： Survivin bladder cancer enzyme-linked immunosorbent assay （ELISA） tumor marker diagnosis

Clinical significance of serum miR-21 in breast cancer compared with CA153 and CEA

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Chinese Journal of Cancer Research 2013年第6期25卷 743-748页

作者： Jianjian Gao Qingyun Zhang jianjun xu Lijuan Guo xuefeng Li Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education) Department of Clinical LaboratoryPeking University Cancer Hospital & Institute

Objective： MicroRNA-21 （miR-21） has been shown to be a key regulator of carcinogenesis. There were few reports about the comparison of serum miR-21 with conventional tumor markers. This study aimed to explore the diagnostic value of circulating miR-21 as a tumor marker in breast cancer （BC） and compare it with CA15 3 and carcinoembryonic antigen （CEA）. Methods： Circulating miR-16 and miR-21 were amplified and quantitatively detected by real-time PCR in 89 BC patients and 55 healthy controls. The levels of CA153 and CEA were measured through assays. Then the sensitivity in diagnosis of BC was compared among miR-21, CA153 and CEA. Results： The level of serum miR-21 was significantly higher in BC patients than controls （P〈0.001）. The sensitivity and specificity of miR-21 were 87.6% and 87.3%, respectively, whereas the sensitivities of CEA and CA153 were only 22.47% and 15.73%. Con^lusions： Compared with CEA and CA153, serum miR-21 has a higher sensitivity in diagnosis of BC. Although not correlated with the status of ER, PR and clinical stages, serum miR-21 may be a potential diagnostic indicator for BC, especially for the early stage.

关键词： MicroRNA-21 （miR-21） breast cancer （BC） real-time polymerase chain reaction （real-time PCR）

Interannual and Interdecadal Variability of Winter Precipitation over China in Relation to Global Sea Level Pressure Anomalies

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Advances in Atmospheric Sciences 2002年第5期19卷 914-926页

作者： jianjun xu Johnny C.L Chan Department of Physics&Materials Science City University of Hong KongChina Department of Earth&Environmental Science New Mexico Tech801 Leroy PlaceSocorro87801 New MexicoUSA

Based on the method of rotated principal component (RPC) analysis and wavelet transforms, the winter precipitation from 36 stations over China for the period 1881-1993 is examined. The results show that the three leading space-time modes correspond, in sequence, to winter rainfall anomalies over the reaches of the Yangtze River, the bend of the Yellow River, and the northeastern region of China. The three modes exhibit interannual oscillations with quasi-biennial and 8-year periods as well as interdecadal oscillations with 16- and 32-year periods. The interannual oscillation (< 10 years) occurs in phase over the different areas, and its maximum amplitude migrates northward considerably with prominent interdecadal variations. However, the interdecadal oscillations (10-32 years) are out of phase over the different regions, and the amplitude variations have the characteristics of stationary waves. The rainfall anomalies appear to be closely related to the anti-phase changes of mean sea-level pressure (SLP) over the Asian mainland and the North Pacific. When the SLP rises over the North Pacific and decreases over the Asian mainland, the precipitation over East China increases noticeably. The linkage between the rainfall over China and the SLP anomalies apparently results from the strength of the East Asian winter monsoon and its associated temperature and moisture advection.

关键词： wavelet transform winter precipitation China SLP

Relationship between the Tibetan Plateau-tropical Indian Ocean thermal contrast and the South Asian summer monsoon

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Frontiers of Earth Science 2021年第1期15卷 151-166页

作者： Xiaoqing LUO jianjun xu Yu ZHANG Kai LI South China Sea Institute of Marine Meteorology Guangdong Ocean UniversityZhanjiang 524088China College of Ocean and Meteorology Guangdong Ocean UniversityZhanjiang 524088China Maritime College Guangdong Ocean UniversityZhanjiang 524088China

The impact of land-sea thermal contrast on the South Asian summer monsoon(SASM)was investigated by calculating the atmospheric heat sources(AHS)and baroclinic component with ERA5 data for the period 1979-2019.Using diagnostic and statistical methods,it was found that the thermal contrast between the Tibetan Plateau(TP)and the tropical Indian Ocean(TIO)affects the South Asian monsoon circulation through the meridional temperature gradient in the upper troposphere.The seasonal changes of the AHS of the TP and TIO are reversed.In summer,the TP is the strongest at the same latitude whereas the TIO is the weakest,and the thermal contrast is the most obvious.The heat sources of the TP and TIO are located on the north and south side of the strong baroclinic area of the SASM region,respectively,and both of which are dominated by deep convective heating in the upper troposphere.The TP-TIO regional meridional thermal contrast index(QI)based on the AHS,and the SASM index(MI)based on baroclinicity were found to be strongly positively correlated.In years of abnormally high QI,the thermal contrast between the TP and TIO is strong in summer,which warms the upper troposphere over Eurasia and cools it over the TIO.The stronger temperature gradient enhances the baroclinicity in the troposphere,which results in a strengthening of the low-level westerly airflow and the upper-level easterly airflow.The anomalous winds strengthen the South Asian high(SAH),with the warmer center in the upper troposphere,and the enhanced Walker circulation over the equatorial Indian Ocean.Finally,the anomalous circulation leads to much more precipitation over the SASM region.The influence of abnormally low QI is almost the opposite.

关键词： Tibetan Plateau tropical Indian Ocean atmosphere heat sources South Asian summer monsoon atmosphere baroclinic component

An Adaptive Semi-Lagrangian Level-Set Method for Convection-Diffusion Equations on Evolving Interfaces

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Advances in Applied Mathematics and Mechanics 2017年第6期9卷 1364-1382页

作者： Weidong Shi jianjun xu Shi Shu School of Mathematical and Computational Sciences Xiangtan UniversityXiangtanHunan 411105China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China

A new Semi-Lagrangian scheme is proposed to discretize the surface convection-diffusion equation.The other involved equations including the the levelset convection equation,the re-initialization equation and the extension equation are also solved by S-L schemes.The S-L method removes both the CFL condition and the stiffness caused by the surface Laplacian,allowing larger time step than the Eulerian method.The method is extended to the block-structured adaptive mesh.Numerical examples are given to demonstrate the efficiency of the S-L method.

关键词： Convection-diffusion equation semi-Lagrangian method level-set method blockstructured adaptive mesh finite difference method