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New Insights into the Aging Embrittlement mechanism of 30Cr2Ni4MoV Steel Containing Si and Mn

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ACTA meTALLURgICA SINICA-ENgLISH LETTERS 2024年第12期37卷 2163-2169页

作者： Zheng, Yongfeng Hu, Xiaofeng jiang, Haichang rong, Lijian Chinese Acad Sci Inst Met Res CAS Key Lab Nucl Mat & Safety Assessment Shenyang 110016 Peoples R China Univ Sci & Technol China Sch Mat Sci & Engn Shenyang 110016 Peoples R China

The aging embrittlement of 30Cr2Ni4MoV steel during service at high temperature has been attributed to the segregation of Si and Mn at grain boundary (gB). We report an alternative mechanism of aging embrittlement of 30Cr2Ni4MoV steel. Using atom probe tomography, it is found that the quenched and tempered (QT) 30Cr2Ni4MoV steel has already contained obvious Si and Mn segregations at gB, which means that the Si and Mn segregations at gB are not sufficient to induce aging embrittlement. It is discovered for the first time in aged 30Cr2Ni4MoV there newly precipitate many g-phases along gB, and Si and Mn segregations at gB of QT30Cr2Ni4MoV steel are the main reason for the precipitation of g-phase. The hard and brittle g-phase helps to promote crack initiation during impact deformation. Subsequently, the cracks can rapidly propagate along gB due to the distribution of g-phase and the segregation of Si and Mn along the gB, which leads to intergranular cracking and low impact energy as for aged 30Cr2Ni4MoV steel.

关键词： 30Cr2Ni4MoV steel Aging embrittlement Si and Mn grain boundary segregation g-phase

Pore-scale visualization on a depressurization-induced CO2 exsolution

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Science Bulletin 2017年第11期62卷 795-803页

作者： Ruina Xu rong Li Feng Huang Peixue jiang Key Laboratory for CO2 Utilization and Reduction Technology of Beijing Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China

The pore-scale behavior of the exsolved CO_2 phase during the depressurization process in CO_2 geological storage was *** reservoir pressure decreases when the injection stops or when a leaking event or fluid extraction *** exsolution characteristics of CO_2 affect the migration and fate of CO_2 in the storage site ***,a micromodel experimental system that can accommodate a large pressure variation provides a physical model with homogeneous porous media to dynamically visualize the nucleation and growth of exsolved CO_2 *** pressure decreased from 9.85 to 3.95 MPa at different temperatures and depressurization rates,and the behavior of CO_2 bubbles was *** the pore-scale,the nuclei became observable when the CO_2 phase density was significantly reduced,and the pressure corresponding to this observation was slightly lower than that of the severe expansion pressure *** lower temperature and faster depressurization rate produced more CO_2 *** exsolved CO_2 bubble preferentially grew into the pore body instead of the *** progress of smaller CO_2 bubbles me.ging into a larger CO_2 bubble was first captured,which validated the existence of the Ostwald ripening *** dispersed CO_2 phase after exsolution shows similarity with the residually trapped CO_*** observation is consistent with the low mobility and high residual trapping ratio of exsolved CO_2 measured in the core-scale measurement,which is considered to be a self-sealing mechanism during depressurization process in CO_2 geological storage.

关键词： Depressurization process CO2 exsolution Ostwald ripening CO2 geological storage

Correlation analysis of PCB and comparison of test-analysis model reduction methods

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Chinese Journal of Aeronautics 2014年第4期27卷 835-845页

作者： Xu Fei Li Chuanri jiang Tongmin rong Shuanglong School of Reliability and Systems Engineering Beihang University

The validity of correlation analysis between finite element model（FEM） and modal test data is strongly affected by three factors, i.e., quality of excitation and measurement points in modal test,FEM reduction methods, and correlation check techniques. A new criterion based on modified mode participation（MMP） for choosing the best excitation point is presented. Comparison between this new criterion and mode participation（MP） criterion is made by using Case 1 with a simple printed circuit board（PCB）. The result indicates that this new criterion produces better results. In Case 2, 35 measurement points are selected to perform modal test and correlation analysis while 9 selected in Case *** equivalent reduction expansion process（SEREP）, modal assurance criteria（MAC）, coordinate modal assurance criteria（CoMAC）, pseudo orthogonality check（POC） and coordinate orthogonality check（CORTHOg） are used to show the error introduced by modal test in Cases 2 and 3. Case 2 shows that additional errors which cannot be identified by using CoMAC can be found by using *** both Cases 2 and 3, guyan reduction, improved reduced system（IRS） method, SEREP and Hybrid reduction are compared for accuracy and robustness. The results suggest that the quality of the reduction process is problem dependent. However, the IRS method is an improvement over the guyan reduction, and the Hybrid reduction is an improvement over the SEREP reduction.

关键词： Correlation analysis Excitation and measurementpoint Finite element method Modal analysis Model reduction PCB

Effects of Rare Earth,Titanium,and Magnesium Additions on Microstructures and Properties of High-boron medium-carbon Alloy

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Journal of Iron and Steel Research International 2016年第11期23卷 1226-1233页

作者： Xiao-li SHI Ye-hua jiang rong ZHOU Faculty of Materials Science and Engineering Kunming University of Science and Technology

In order to improve the toughness and wear resistance of high-boron medium-carbon alloy （HBMCA）, a novel wear-resistant HBMCA comprising granular borocarbide was obtained by titanium, magnesium, and rare earth modifications. These modifications gave rise to greatly refined as-cast eutectic borocarbide structures and a less interconnected continuous borocarbide network. Heat treatment mostly produced broken and spheriodized borocarbides that tended to exist as isolated particles in modified HBMCA. The heat treated modified HBMCA exhibited enhanced hardness than pristine and impact toughness was improved significantly to 12.5 J/cm^2. In addition, it displayed 2.39 and 1.7 times greater wear resistance than high-speed steel （HSS） and high nickel-chromium alloy steel （Cr25） at high temperature （500℃）, respectively. Here, the modification mechanisms involving Re2O3, TiN, and MgO/ MgS heterogeneous nuclei were discussed.

关键词： modification eutectic borocarbide spheroidization toughness wear resistance

A short note on fitting a single-index model with massive data

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Statistical Theory and Related Fields 2023年第1期7卷 49-60页

作者： rong jiang Yexun Peng Department of Statistics College of ScienceDonghua UniversityShanghaiPeople’s Republic of China

This paper studies the inference problem of index coefficient in single-index models under massive *** of massive dataset is challenging owing to formidable computational costs or memory requirements.A natural method is the averaging divide-and-conquer approach,which splits data into several blocks,obtains the estimators for each block and then aggregates the estimators via ***,there is a restriction on the number of *** overcome this limitation,this paper proposed a computationally efficient method,which only requires an initial estimator and then successively refines the estimator via multiple rounds of *** proposed estimator achieves the optimal convergence rate without any restriction on the number of *** present both theoretical analysis and experiments to explore the property of the proposed method.

关键词： Single-index model massive dataset divide-and-conquer method

A local refinement purely meshless scheme for time fractional nonlinear Schrodinger equation in irregular geometry region

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Chinese Physics B 2021年第2期30卷 164-175页

作者： Tao jiang rong-rong jiang Jin-Jing Huang Jiu Ding Jin-Lian Ren School of Mathematical Sciences Yangzhou UniversityYangzhou 225002China Department of Mathematics University of Southern MississippiHattiesburgMS 39406-5045USA

A local refinement hybrid scheme(LRCSPH-FDM)is proposed to solve the two-dimensional(2D)time fractional nonlinear Schrodinger equation(TF-NLSE)in regularly or irregularly shaped domains,and extends the scheme to predict the quantum mechanical properties governed by the time fractional gross-Pitaevskii equation(TF-gPE)with the rotating Bose-Einstein *** is the first application of the purely meshless method to the TF-NLSE to the author’s *** proposed LRCSPH-FDM(which is based on a local refinement corrected SPH method combined with FDM)is derived by using the finite difference scheme(FDM)to discretize the Caputo TF term,followed by using a corrected smoothed particle hydrodynamics(CSPH)scheme continuously without using the kernel derivative to approximate the spatial ***,the local refinement technique is adopted to reduce the numerical *** numerical simulations,the complex irregular geometry is considered to show the flexibility of the purely meshless particle method and its advantages over the grid-based *** numerical convergence rate and merits of the proposed LRCSPH-FDM are illustrated by solving several 1D/2D(where 1D stands for one-dimensional)analytical TF-NLSEs in a rectangular region(with regular or irregular particle distribution)or in a region with irregular *** proposed method is then used to predict the complex nonlinear dynamic characters of 2D TF-NLSE/TF-gPE in a complex irregular domain,and the results from the posed method are compared with those from the *** the numerical results show that the present method has a good accuracy and flexible application capacity for the TF-NLSE/gPE in regions of a complex shape.

关键词： Caputo fractional derivative nonlinear Schrodinger/gross-Pitaevskii equation corrected smoothed particle hydrodynamics irregularly domain

Peripheral blood RNA biomarkers can predict lesion severity in degenerative cervical myelopathy

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Neural Regeneration Research 2025年第6期20卷 1764-1775页

作者： Zhenzhong Zheng Jialin Chen Jinghong Xu Bin jiang Lei Li Yawei Li Yuliang Dai Bing Wang Department of Spine Surgery The Second Xiangya Hospital of Central South UniversityChangshaHunan ProvinceChina

Degenerative cervical myelopathy is a common cause of spinal cord injury,with longer symptom duration and higher myelopathy severity indicating a worse *** numerous studies have investigated serological biomarkers for acute spinal cord injury,few studies have explored such biomarkers for diagnosing degenerative cervical *** study involved 30 patients with degenerative cervical myelopathy(51.3±7.3 years old,12 women and 18 men),seven healthy controls(25.7±1.7 years old,one woman and six men),and nine patients with cervical spondylotic radiculopathy(51.9±8.6 years old,three women and six men).Analysis of blood samples from the three groups showed clear differences in transcriptomic *** analysis identified 128 differentially expressed genes that were enriched in patients with neurological *** least absolute shrinkage and selection operator analysis,we constructed a five-gene model(TBCD,TPM2,PNKD,EIF4g2,and AP5Z1)to diagnose degenerative cervical myelopathy with an accuracy of 93.5%.One-gene models(TCAP and SDHA)identified mild and severe degenerative cervical myelopathy with accuracies of 83.3%and 76.7%,*** of two immune cell types(memory B cells and memory-activated CD4^(+)T cells)predicted levels of lesions in degenerative cervical myelopathy with 80%*** results suggest that peripheral blood RNA biomarkers could be used to predict lesion severity in degenerative cervical myelopathy.

关键词： biomarkers candidate genes degenerative cervical myelopathy gene expression analysis immune cell types neurological disabilities peripheral blood RNA profiles spinal cord injury

Epidemic spreading on scale-free networks with diversity of node anti-attack abilities

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The Journal of China Universities of Posts and Telecommunications 2010年第1期17卷 73-76,126页

作者： SONg Yu-rong jiang guo-ping Center for Control and Intelligence Technology Nanjing University of Posts and Telecommunications Nanjing 210003 China College of Automation Nanjing University of Posts and Telecommunications Nanjing 210003 China

In this article, a modified susceptible-infected-removed （SIR） model is proposed to study the influence of diversity of node anti-attack abilities on the threshold of propagation in scale-free networks. In particular, a vulnerability function related to node degree is introduced into the model to describe the diversity of a node anti-attack ability. Analytical results are derived using the mean-field theory and it is observed that the diversity of anti-attack of nodes in scale-free networks can increase effectively the threshold of epidemic propagation. The simulation results agree with the analytical results. The results show that the vulnerability functions can help adopt appropriate immunization strategies.

关键词： epidemic spreading scale-free network SIR model anti-attack vulnerability function

Effects of Interannual Salinity Variability on the Barrier Layer in the Western-Central Equatorial Pacific:A Diagnostic Analysis from Argo

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Advances in Atmospheric Sciences 2014年第3期31卷 532-542页

作者： ZHENg Fei ZHANg rong-Hua ZHU jiang International Center for Climate and Environment Science Institute of Atmospheric Physics Chinese Academy of Sciences Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Earth System Science Interdisciplinary Center University of MarylandCollege ParkMaryland 20740USA

ABSTRACT In this paper, interannual variations in the barrier layer thickness （BLT） are analyzed using Argo three-dimensional temperature and salinity data, with a locus on the effects of interannually varying salinity on the evolution of the El Nifio Southern Oscillation （ENSO）. The interannually varying BLT exhibits a zonal seesaw pattern across the equatorial Pacific during ENSO cycles. This phenomenon has been attributed to two different physical processes. During E1 Nifio （La Nifia）, the barrier layer （BL） is anomalously thin （thick） west of about 160°E, and thick （thin） to the east. In the western equatorial Pacific （the western part： 130°-160°E）, interannual variations of the BLT indicate a lead of one year relative to those of the ENSO onset. The interannual variations of the BLT can be largely attributed to the interannual temperature variability, through its dominant effect on the isothermal layer depth （ILD）. However, in the central equatorial Pacific （the eastern part： 160~E- 170~W）, interannual variations of the BL almost synchronously vary with ENSO, with a lead of about two months relative to those of the local SST. In this region, the interannual variations of the BL are significantly affected by the interannually varying salinity, mainly through its modulation effect on the mixed layer depth （MLD）. As evaluated by a onedimensional boundary layer ocean model, the BL around the dateline induced by interannual salinity anomalies can significantly affect the temperature fields in the upper ocean, indicating a positive feedback that acts to enhance ENSO.

关键词： barrier layer salinity effect ENSO Argo