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中国铸造:英文版 2023年第5期20卷 365-375页

作者： Jia-yan Sun Rong Yin Ye-yuan Hu Yun-xiang Tan Qing-Yan Xu Key Laboratory for Advanced Materials Processing Technology(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Xiaomi AI Lab Beijing100102China

To enhance the accuracy of mechanical simulation in the directional solidification process of turbine blades for heavy-duty gas turbines,a new constitutive model that employs machine learning methods was developed.This model incorporates incremental learning and transfer learning,thus improves the predictive accuracy and generalization performance.To account for the anisotropy of the directionally solidified alloy,a deformation direction parameter is added to the model,enabling prediction of the stress-strain relationship of the alloy under different deformation directions.The predictive capabilities of both models are evaluated using correlation coefficient(R),average relative error(δ),and value of relative error(RE).Compared to the traditional model,the machine learning constitutive model achieves higher prediction accuracy and better generalization performance.This offers a new approach for the establishment of flow constitutive models for other directionally solidified and single-crystal superalloys.

关键词： Ni-based superalloy constitutive model machine learning directional solidification anisotropy

Droplet morphology analysis of drop-on-demand inkjet printing

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China Foundry 2024年第1期21卷 20-28页

作者： Hu-xiang Xia Takechi Kensuke Tajima Shin Kawamura Yoshiumi Qing-Yan Xu Key Laboratory for Advanced Materials Processing Technology(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Toyota Central R&D Labs. Inc.41-1 Yokomichi NagakuteAichi 480-1192Japan Frontier Research Center Toyota Motor Corporation1 Toyota-ChoToyotaAichi 471-8572Japan

As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accuracy of deposition.In this study,the drop-on-demand(DoD)inkjet simulation model was established,and the accuracy of the simulation model was verified by corresponding experiments.The simulation result shows that the velocity of the droplet front and tail,as well as the time to disconnect from the nozzle is mainly affected by density(ρ),viscosity(μ)and surface tension(σ)of droplets.When the liquid filament is about to disconnect from the nozzle,the filament length and filament front velocity are found to have a linear correlation withσ/ρμand ln(ρ/(μσ1/2)).

关键词： microdevice fabrication inkjet printing droplet morphology modeling and simulation

A model for simulation of recrystallization microstructure in single-crystal superalloy

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Rare Metals 2018年第12期37卷 1027-1034页

作者： Run-Nan Wang Qing-Yan Xu Bai-Cheng Liu Key Laboratory for Advanced Materials Processing Technology (MOE) School of Materials Science and Engineering Tsinghua University

In the present investigation, a coupled crystal plasticity finite-element(CPFE) and cellular automaton(CA) model was developed to predict the microstructure of recrystallization in single-crystal(SX) Ni-based superalloy.The quasi-static compressive tests of [001] orientated SX DD6 superalloy were conducted on Gleeble3500 tester to calibrate the CPFE model based on crystal slip kinematics.The simulated stress-strain curve agrees well with the experimental results. Quantitative deformation amount was introduced in the deformed samples of simulation and experiment, and these samples were subsequently subjected to the standard solution heat treatment(SSHT).Results of CA simulation show that the recrystallization(RX) nucleation tends to occur at the third stage of SSHT process due to the high critical temperature of RX nucleation for the samples deformed at room temperature. The inhomogeneous RX grains gradually coarsen and compete to reach more stable status by reducing the system energy.Simulated RX grain density decreases from 7.500 to1.875 mm,agreeing well with the value of 1.920 mmfrom electron backscattered diffraction(EBSD) detection of the experimental sample.

关键词： Recrystallization Single crystal Crystal plasticity Cellular automaton Microstructure

Testing Regression Coefficients in High-Dimensional and Sparse Settings

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Acta Mathematica Sinica,English Series 2021年第10期37卷 1513-1532页

作者： Kai xu yan TIAN qing CHENG School of Mathematics and Statistics Anhui Normal UniversityWuhu 241002P.R.China Center for Quantitative Medicine Duke-NUS Medical SchoolNational University of SingaporeSingapore 169856

In the high-dimensional setting,this article considers a canonical testing problem in multivariate analysis,namely testing coefficients in linear regression models.Several tests for highdimensional regression coefficients have been proposed in the recent literature.However,these tests are based on the sum of squares type statistics,that perform well under the dense alternatives and suffer from low power under the sparse alternatives.In order to attack this issue,we introduce a new test statistic which is based on the maximum type statistic and magnifies the sparse signals.The limiting null distribution of the test statistic is shown to be the extreme value distribution of type I and the power of the test is analysed.In particular,it is shown theoretically and numerically that the test is powerful against sparse alternatives.Numerical studies are carried out to examine the numerical performance of the test and to compare it with other tests available in the literature.

关键词： Extreme value distribution high-dimensional linear models maximum-type-test

Simulation of the Dendrite Morphology and Microsegregation in Solidification of Al–Cu–Mg Aluminum Alloys

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 173-181页

作者： Rui Chen Qing-Yan Xu Bai-Cheng Liu Key Laboratory for Advanced Materials Processing Technology Ministry of Education School of Materials Science and Engineering Tsinghua University

Since most typical alloys in industrial applications are multicomponent with three or more components, and various CA models proposed in the past mainly focus on the binary alloys, a two-dimensional modified cellular automaton model allowing for the quantitatively predicting dendrite growth of multicomponent alloys in the low P6clet number regime is presented. The elimination of the mesh-induced anisotropy is achieved by adopting a modified virtual front tracking method. A new efficient method based on the lever rule is applied to calculate the solid fraction increment of the interfacial cells. The thermodynamic data such as liquidus temperature, the partition coefficients, and the slope of liquidus surface, needed for determining the dynamics of dendrite growth, are obtained by coupling with PanEngine. This model is applied to simulate the dendrite morphology and microsegregation of A1-Cu-Mg temary alloy both for single and multi- dendrites growth. The simulated results demonstrate that the difference of the concentration distribution profiles ahead of the dendrite tip for each alloying element mainly results from the different partition coefficients and solute diffusion coefficients. Comparison with the prediction of analytical model is carded out and it reveals the correctness of the model. Consequently, the difference in interdendritic microsegregation behavior of different components is analyzed.

关键词： Cellular automaton Multicomponent Dendrite growth Microsegregation

Effects of Zishen Yutai Pills on in vitro Fertilization-Embryo Transfer Outcomes in Patients with Diminished Ovarian Reserve:A Prospective,Open-Labeled,Randomized and Controlled Study

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Chinese Journal of Integrative Medicine 2023年第4期29卷 291-298页

作者： LI Xiu-fang WANG Zhong-qing xu Hai-yan LIU Hong SHENG yan xu Jin LI Yuan-mei LIAN Fang The First Clinical College Shandong University of Traditional Chinese MedicineJinan 250014China Center for Reproductive Medicine Shandong UniversityJinan 250021China Medical College of Optometry and Ophthalmology Shandong University of Traditional Chinese MedicineJinan 250014China Department of Traditional Chinese Medicine Jinan Golden Time Health Nursing HospitalJinan 250000China Reproductive and Genetic Center of Integrated Traditional and Western Medicine Affiliated Hospital of Shandong University of Traditional ChineseJinan 250011China Medicine

Objective:To explore the effects of Zishen Yutai Pills(ZYPs)on the quality of oocytes and embryos,as well as pregnancy outcomes in patients with diminished ovarian reserve(DOR)receiving in vitro fertilizationembryo transfer(IVF-ET).The possible mechanisms,involving the regulation of bone morphogenetic protein 15(BMP15)and growth differentiation factor 9(GDF9),were also investigated.Methods:A total of 120 patients with DOR who underwent their IVF-ET cycle were randomly allocated to 2 groups in a 1:1 ratio.The patients in the treatment group(60 cases)received ZYPs from the mid-luteal phase of the former menstrual cycle by using gonadotropin-releasing hormone(Gn RH)antagonist protocol.The patients in the control group(60 cases)received the same protocol but without ZYPs.The primary outcomes were the number of oocytes retrieved and high-quality embryos.Secondary outcomes included other oocyte or embryo indices as well as pregnancy outcomes.Adverse events were assessed by comparison of the incidence of ectopic pregnancy,pregnancy complications,pregnancy loss,and preterm birth.Contents of BMP15 and GDF9 in the follicle fluids(FF)were also quantified with enzymelinked immunosorbent assay.Results:Compared with the control group,the numbers of oocytes retrieved and high-quality embryos were significantly increased in the ZYPs group(both P0.05).The administration of ZYPs did not increase the incidence of adverse events.The expressions of BMP15 and GDF9 in the ZYPs group were significantly up-regulated compared with the control group(both P<0.05).Conclusions:ZYPs exhibited beneficial effects in DOR pa

关键词： Zishen Yutai Pills diminished ovarian reserve in vitro fertilization-embryo transfer oocytes embryos

Association between Serum Uric Acid and the Early Marker of Kidney Function Decline among Chinese Middle-Aged and Older Population:Evidence from the China Health and Retirement Longitudinal Study

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Biomedical and Environmental Sciences 2023年第3期36卷 231-240页

作者： TANG xu xu Lu MENG Ruo Gu DU Yi qing LIU Shi Jun ZHAN Si yan xu Tao Department of Urology Peking University People’s HospitalBeijing 100044China Research Center of Clinical Epidemiology Peking University Third HospitalBeijing 100191China National Institute of Health Data Science Center for Data Science in Health and MedicinePeking UniversityBeijing 100191China Department of Epidemiology and Biostatistics School of Public HealthPeking UniversityBeijing 100191China Center for Intelligent Public Health Institute for Artificial IntelligencePeking UniversityBeijing 100191China

Objective To evaluate the association between serum uric acid(SUA)and kidney function decline.Methods Data was obtained from the China Health and Retirement Longitudinal Study on the Chinese middle-aged and older population for analysis.The kidney function decline was defined as an annual estimated glomerular filtration rate(e GFR)decrease by>3 mL/min per 1.73 m^(2).Multivariable logistic regression was applied to determine the association between SUA and kidney function decline.The shape of the association was investigated by restricted cubic splines.Results A total of 7,346 participants were included,of which 1,004 individuals(13.67%)developed kidney function decline during the follow-up of 4 years.A significant dose-response relation was recorded between SUA and the kidney function decline(OR 1.14,95%CI 1.03-1.27),as the risk of kidney function decline increased by 14%per 1 mg/d L increase in SUA.In the subgroup analyses,such a relation was only recorded among women(OR 1.22,95%CI 1.03-1.45),those aged5 mg/dL was associated with a significantly higher risk of kidney function decline.Conclusion The SUA level was associated with kidney function decline.An elevation of SUA should therefore be addressed to prevent possible kidney impairment and dysfunction.

关键词： Uric acid Glomerular filtration rate Kidney function decline

Hierarchically wood-derived integrated electrode with tunable superhydrophilic/superaerophobic surface for efficient urea electrolysis

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Journal of Energy Chemistry 2023年第1期76卷 566-575,I0014页

作者： Yu Liao Songlin Deng yan qing Han xu Cuihua Tian Yiqiang Wu College of Materials Science and Engineering Central South University of Forestry and TechnologyChangsha 410004HunanChina

Conferring surfaces with superhydrophilic/superaerophobic characteristics is desirable for synthesizing efficient gas reaction catalysts.However,complicated procedures,high costs,and poor interfaces hinder commercialization.Here,an integrated electrode with tunable wettability derived from a hierarchically porous wood scaffold was well designed for urea oxidation reaction(UOR).Interestingly,the outer surface of the wood lumen was optimized to the preferred wettability via stoichiometry to promote electrolyte permeation and gas escape.This catalyst exhibits outstanding activity and durability for UOR in alkaline media,requiring only a potential of 1.36 V(vs.RHE)to deliver 10 m A cm^(-2)and maintain its activity without significant decay for 60 h.These experiments and theoretical calculations demonstrate that the nickel(oxy)hydroxide layer formed through surface reconstruction of nickel nanoparticles improves the active sites and intrinsic activity.Moreover,the superwetting properties of the electrode promote mass transfer by guaranteeing substantial contact with the electrolyte and accelerating the separation of gaseous products during electrocatalysis.These findings provide the understanding needed to manipulate the surface wettability through rational design and fabrication of efficient electrocatalysts for gas-evolving processes.

关键词： Integrated electrode Wood scaffold Superhydrophilic/Superaerophobic surface Urea oxidation reaction

Twin model-based fault detection and tolerance approach for in-core self-powered neutron detectors

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Nuclear Science and Techniques 2023年第8期34卷 86-99页

作者： Jing Chen yan-Zhen Lu Hao Jiang Wei-qing Lin Yong xu College of Electrical Engineering and Automation Fuzhou UniversityFuzhou 350108China The Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China Fujian Fuqing Nuclear Power Co. Ltd.Fujian 350318China

The in-core self-powered neutron detector(SPND)acts as a key measuring device for the monitoring of parameters and evaluation of the operating conditions of nuclear reactors.Prompt detection and tolerance of faulty SPNDs are indispensable for reliable reactor management.To completely extract the correlated state information of SPNDs,we constructed a twin model based on a generalized regression neural network(GRNN)that represents the common relationships among overall signals.Faulty SPNDs were determined because of the functional concordance of the twin model and real monitoring sys-tems,which calculated the error probability distribution between the model outputs and real values.Fault detection follows a tolerance phase to reinforce the stability of the twin model in the case of massive failures.A weighted K-nearest neighbor model was employed to reasonably reconstruct the values of the faulty signals and guarantee data purity.The experimental evaluation of the proposed method showed promising results,with excellent output consistency and high detection accuracy for both single-and multiple-point faulty SPNDs.For unexpected excessive failures,the proposed tolerance approach can efficiently repair fault behaviors and enhance the prediction performance of the twin model.

关键词： Self-powered neutron detector Twin model Fault detection Fault tolerance Generalized regression neural network Nuclear power plant

Modeling of aluminum-silicon irregular eutectic growth by cellular automaton model

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China Foundry 2016年第2期13卷 114-122页

作者： Rui Chen Qing-Yan Xu Bai-cheng Liu School of Materials Science and Engineering Tsinghua University Key Laboratory of Advanced Materials Processing Technology MOE

Due to the extensive application of Al-Si alloys in the automotive and aerospace industries as structural components, an understanding of their microstructural formation, such as dendrite and(Al+Si) eutectic, is of great importance to control the desirable microstructure, so as to modify the performance of castings. Since previous major themes of microstructural simulation are dendrite and regular eutectic growth, few efforts have been paid to simulate the irregular eutectic growth. Therefore, a multiphase cellular automaton(CA) model is developed and applied to simulate the time-dependent Al-Si irregular eutectic growth. Prior to model establishment, related experiments were carried out to investigate the influence of cooling rate and Sr modification on the growth of eutectic Si. This CA model incorporates several aspects, including growth algorithms and nucleation criterion, to achieve the competitive and cooperative growth mechanism for nonfaceted-faceted Al-Si irregular eutectic. The growth kinetics considers thermal undercooling, constitutional undercooling, and curvature undercooling, as well as the anisotropic characteristic of eutectic Si growth. The capturing rule takes into account the effects of modification on the silicon growth behaviors.The simulated results indicate that for unmodified alloy, the higher eutectic undercooling results in the higher eutectic growth velocity, and a more refined eutectic microstructure as well as narrower eutectic lamellar spacing. For modified alloy, the eutectic silicon tends to be obvious fibrous morphology and the morphology of eutectic Si is determined by both chemical modifier and cooling rate. The predicted microstructure of Al-7Si alloy under different solidification conditions shows that this proposed model can successfully reproduce both dendrite and eutectic microstructures.

关键词： Al-Si alloys irregular eutectic growth cellular automaton modification numerical simulation