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Microstructure characteristics and mechanical properties of NbMoTiVWSix refractory high-entropy alloys

China Foundry 2022年第6期19卷 495-502页

作者： Qin Xu Qi Wang De-zhi Chen Yi-ang Fu Qing-sheng Shi Ya-jun Yin shu-yan z.ang School of Mechanic and Electrical Engineering Henan University of TechnologyZhengzhou 450001China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science&TechnologyWuhan 430074China Centre of Excellence for Advanced Materials Songshan LakeDongguan 523808GuangdongChina

Refractory high-entropy alloys are considered as potential structural materials for elevated temperature *** obtain refractory high-entropy alloys with high strength,different amounts of Si were added into the NbMoTiVW refractory high-entropy *** effects of Si on the phase constitution,microstructure characteristics and mechanical properties of NbMoTiVWSi_(x) alloys were *** show that when the addition of Si is 0,0.025 and 0.05(molar ratio),the alloys are consisted of primary BCC and secondary BCC in the intergranular *** the addition of Si is increased to 0.075 and 0.1,eutectic structure including silicide phase and secondary BCC phase is *** primary BCC phase shows dendritic morphology,and is refined by adding *** volume fraction of intergranular area is increased from 12.22%to 18.13%when the addition of Si increases from 0 to *** ultimate compressive strength of the NbMoTiVW alloy is improved from 2,242 MPa to 2,532 *** yield strength is also improved by the addition of Si,and the yield strength of NbMoTiVWSi_(0.1) reaches maximum of 2,298 ***,the fracture strain of the alloy is decreased from 15.31%to 12.02%.The fracture mechanism of the alloys is changed from mixed fracture of ductile and quasi-cleavage to cleavage fracture with increasing of *** strengthening of alloys is attributed to the refinement of primary BCC phase,volume fraction increment of secondary BCC phase,and formation of eutectic structure by addition of Si.

关键词： high-entropy alloy second phase microstructure refinement mechanical property strengthening

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Numerical simulation of the three-dimensional flow-path in a ram-rotor

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航空动力学报 2010年第6期25卷 1358-1365页

作者： HAN Ji-ang zHONG Jing-jun yan Hong-ming Marine Engineering College Dalian Maritime UniversityDalian 116026China School of Energy Science and Engineering Harbin institute of TechnologyHarbin 150001China

A kind of three-dimensional flow-path of the ram-rotor was designed in this paper according to the design method of the typical supersonic intake of aircraft and missiles,especially the design method of the compression ramp,the throat and the subsonic *** design Mach number of the flow-path was based on the averaged relative Mach number,regardless of the change of incoming Mach number along radial direction of the ***,the flowfield of the designed flow-path was simulated numerically with computational fluid dynamics software at design *** purpose of simulation was to obtain the details of the flowfield,including the structure of the shock wave system,position of flow separation zone,and so *** performance of the ram-rotor was also *** numerical results show the structure of the shock wave system in the flow-path is similar to that in the supersonic *** improve the overall performance of the ram-rotor,the reasonable compromise between the total pressure ratio and the isentropic adiabatic efficiency should be *** structure optimization of the flow-path and the configuration of the shock wave system have great influence on the performance of the ram-rotor.

关键词： ram-rotor flow-path supersonic intake numerical simulation design point

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Quantile Regression for Thinning-based INAR(1)Models of Time Series of Counts

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Acta Mathematicae Applicatae Sinica 2021年第2期37卷 264-277页

作者： Dan-shu SHENG De-hui Wang Kai yanG zi-ang WU School of Mathematics Jilin UniversityChangchun 130012China School of Economics Liaoning UniversityShenyang 110036China School of Mathematics and Statistics Changchun University of TechnologyChangchun 130012China

In this paper,we develop the quantile regression(QR)estimation for the first-order integer-valued autoregressive(INAR(1))models by defining the smoothing INAR(1)*** method is used to derive the QR estimators for the autoregressive coefficient and the quantile of *** consistency and asymptotic normality of the proposed estimators are *** performances of the proposed estimation procedures are evaluated by Monte Carlo *** results show that the proposed procedures perform well for simulations and a real data application.

关键词： INAR(1)process quantile regression parameter estimation jittering

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A multiobjective evolutionary optimization method based critical rainfall thresholds for debris flows initiation

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Journal of Mountain Science 2020年第8期17卷 1860-1873页

作者： yan yan z.ang Yu HU Wang GUO Xiao-jun MA Chao Wang zi-ang z.ang Qun Key Laboratory of High-Speed Railway Engineering MOE/School of Civil EngineeringSouthwest Jiao tong UniversityChengdu 610031China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Key Laboratory of Mountain Surface Process and Hazards/Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083China Sichuan Institute of Land and Space Ecological Restoration and Geological Hazard Prevention Chengdu 610081China

At present,most researches on the critical rainfall threshold of debris flow initiation use a linear model obtained through *** relatively weak fault tolerance,this method not only ignores nonlinear effects but also is susceptible to singular noise samples,which makes it difficult to characterize the true quantization relationship of the rainfall ***,the early warning threshold determined by statistical parameters is susceptible to negative samples(samples where no debris flow has occurred),which leads to uncertainty in the reliability of the early warning results by the regression *** overcome the above limitations,this study develops a data-driven multiobjective evolutionary optimization method that combines an artificial neural network(ANN)and a multiobjective evolutionary optimization implemented by particle swarm optimization(PSO).Firstly,the Pareto optimality method is used to represent the nonlinear and conflicting critical thresholds for the rainfall intensity I and the rainfall duration *** ANN is used to construct a dual-target(dual-task)predictive surrogate model,and then a PSO-based multiobjective evolutionary optimization algorithm is applied to train the ANN and stochastically search the trained ANN for obtaining the Pareto front of the I-D surrogate prediction model,which is intended to overcome the limitations of the existing linear regression-based threshold ***,a double early warning curve model that can effectively control the false alarm rate and negative alarm rate of hazard warnings are proposed based on the decision space and target space *** study provides theoretical guidance for the early warning and forecasting of debris flows and has strong applicability.

关键词： Debris flow Critical rainfall thresholds Multiobjective evolutionary optimization Artificial neural network Pareto optimality

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Refining constitutive relation by integration of finite element simulations and Gleeble experiments

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Journal of Materials Science & Technology 2019年第6期35卷 1039-1043页

作者： D.J. Yu D.S. Xu H. W ang z.B. zhao G.z. Wei R. yang College of Sciences Northeastern University Shenyang 110004 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Thermo-mechanical coupled finite element calculations were carried out to simulate the Gleeble compression of the samples of a titanium alloy(Ti60), and the results are analyzed and compared with the actual compression tests conducted on a Gleeble 3800 thermo-mechanical simulator. The changes in temperature, stress and strain distribution in the samples and the source of error on the constitutive relations from Gleeble hot compression test were analyzed in detail. Both simulations and experiments showed that the temperature distribution in the specimen is not uniform during hot compression, resulting in significant deformation inhomogeneity and non-ignorable error in the flow stress strain relation,invalidating the uniform strain assumption commonly assumed when extracting the constitutive relation from Gleeble tests. Based on the finite element simulations with iterative corrections, we propose a scheme to refine the constitutive relations from Gleeble tests.

关键词： Titanium alloy Constitutive relation Finite element Compression Temperature distribution

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Gradient Structured Copper by Rotationally Accelerated Shot Peening

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Journal of Materials Science & Technology 2017年第7期33卷 758-761页

作者： X.Wang Y.S.Li Q.z.ang Y.H.zhao Y.T.zhu Nano Structural Materials Center School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China Department of Materials Science and Engineering North Carolina State University Raleigh NC 27695 USA

A new technology-rotationally accelerated shot peening（RASP）, was developed to prepare gradient structured materials. By using centrifugal acceleration principle and large steel balls, the RASP technology can produce much higher impact energy compared to conventional shot peening. As a proof-of-concept demonstration, the RASP was utilized to refine the surface layer in pure copper（Cu） with an average grain size of 85 nm. The grain size increases largely from surface downwards the bulk, forming an800 ？m thick gradient-structured surface layer and consequently a micro-hardness gradient. The difference between the RASP technology and other established techniques in preparing gradient structured materials is discussed. The RASP technology exhibits a promoting future for large-scale manufacturing of gradient materials.

关键词： Microstructure Rotationally accelerated shot peening Gradient structure Hardness Copper

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Haploidentical hematopoietic stem cell transplantation for pediatric patients with chronic active Epstein-Barr virus infection:a retrospective analysis of a single center

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World Journal of Pediatrics 2021年第6期17卷 626-636页

作者： yan-Hui Luo Jun yang ang Wei© Guang-Hua zhu Bin Wang Rui z.ang Chen-Guang Jia yan yan Kai Wang Sidan Li Xuan zhou Mao-Quan Qin Tian-You Wang Beijing Key Laboratory of Pediatric Hematology Oncology National Key Discipline of Pediatrics(Capital Medical University)Key Laboratory of Major Diseases in ChildrenMinistry of EducationHematology Oncology CenterDepartment of Hematology and OncologyBeijing Children's HospitalCapital Medical UniversityNational Center for Children’s HealthNanlishi Road No.56Beijing 100045China

Background This study aimed to evaluate the feasibility and clinical effect of haploidentical hematopoietic stem cell transplantation(haplo-HSCT)for the treatment of pediatric patients with chronic active Epstein-Barr virus infection(CAEBV).Methods Children with CAEBV who did not have matched donors and underwent haplo-HSCT in Beijing Children's Hospital,Capital Medical University,from October 2016 to June 2020 were analyzed *** relating to the clinical manifestations,engraftment,and prognosis of the children were extracted from medical *** Twenty-five patients,including 16 males and 9 females,with an onset age of 5.0±2.6 years and a transplantation age of 6.9±2.9 years,were enrolled irnhis *** mean time from diagnosis to transplantation was 3.8(2.0-40.2)*** mean observation time was 19.0±12.0 *** patients received the reduced intensity conditioning regimen,and the remaining patients all received the modified myeloablative conditioning *** the end of the follow-up,23 patients were characterized by disease-free survival(DFS),22 were characterized by event-free survival(EFS).and two *** of the patients died of thrombotic microangiopathy(TMA),and another died of graft versus host disease(GVHD);this patient discontinued the treatment for economic *** 3-year overall survival(OS)rate was estimated to be 92.0%±5.4%,and the 3-year EFS rate was estimated to be 87.4%±6.8%.All active patients survived after HSCT *** GVHD degrees 1-3 were observed in ten patients(40.0%),and degree IV was observed in six(24.0%),who were all cured except for one *** GVHD was observed in nine(36.0%),and most of these cases were *** incidence of TMA and veno-occlusive disease(VOD)was 28.0%and 4.0%.Conclusions Haploidentical hematopoietic stem cell transplantation is safe and effective in the treatment of pediatric CAEBV and can be used as an alternative therapy without matched donors or emergency tr

关键词： Chronic active Epstein-Barr virus infection Haploidentical hematopoietic stem cell transplantation Prognosis Graft versus host diseases Thrombotic microangiopathy

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Precise asymptotics in the law of the logarithm for random fields in Hilbert space

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Journal of zhejiang University-Science A(Applied Physics & Engineering) 2007年第4期8卷 651-659页

作者： FU Ke-ang z.ang Li-xin Department of Mathematics Zhejiang University Hangzhou 310027 China

Consider the positive d-dimensional lattice z^d（d≥2） with partial ordering ≤, let {XK; K∈z＋^d} be i.i.d, random variables taking values in a real separable Hilbert space （H, ｜｜·｜｜） with mean zero and covariance operator ∑ and set partial sums SN =∑K≤nXK,K,N∈z＋^d. Under some moment conditions, we obtain the precise asymptotics of a kind of weighted infinite series for partial sums SN as ε↓ by using the truncation and approximation methods. The results are related to the convergence rates of the law of the logarithm in Hilbert space, and they also extend the results of （Gut and Spataru, 2003）.

关键词： The law of the logarithm Random field Hilbert space. Tail probabilitv. Truncation method

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A Self-normalized Law of the Iterated Logarithm for the Geometrically Weighted Random Series

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Acta Mathematica Sinica,English Series 2016年第3期32卷 384-392页

作者： Ke ang FU Wei HUang School of Statistics and Mathematics Zhejiang Gongshang University Department of Mathematics Zhejiang University

Let {X, Xn; n ≥ 0} be a sequence of independent and identically distributed random variables with EX=0, and assume that EX^2I（｜X｜ ≤ x） is slowly varying as x →∞, i.e., X is in the domain of attraction of the normal law. In this paper, a self-normalized law of the iterated logarithm for the geometrically weighted random series Σ~∞（n=0）β~nXn（0 〈 β 〈 1） is obtained, under some minimal conditions.

关键词： Domain of attraction of the normal law geometrically weighted series law of the iteratedlogarithm self-normalization slowly varying

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A weak invariance principle for self-normalized products of sums of mixing sequences

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Applied Mathematics(A Journal of Chinese Universities) 2008年第2期23卷 183-189页

作者： FU Ke-ang HUang Wei Dept. of Math. Zhejiang Univ. Hangzhou 310027 China

Let variables in the {X, Xn, n ≥ 1} be a sequence of strictly stationary φ-mixing positive random domain of attraction of the normal law. Under some suitable conditions the principle for self-normalized products of ... 详细信息

关键词： self-normalized product domain of attraction of the normal law φ-mixing Wiener process.

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