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A class of estimators of the mean survival time from interval censored data with application to linear regression

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Applied Mathematics(A Journal of Chinese Universities) 2008年第4期23卷 377-390页

作者： zheng zu-kang Dept. of Statist. School of Management Fudan Univ. Shanghai 200433 China

A class of estimators of the mean survival time with interval censored data are studied by unbiased transformation method. The estimators are constructed based on the observations to ensure unbiasedness in the sense that the estimators in a certain class have the same expectation as the mean survival time. The estimators have good properties such as strong consistency （with the rate of O（n^-1/1 （log log n）^1/2）） and asymptotic normality. The application to linear regression is considered and the simulation reports are given.

关键词： interval censored data linear regression

Graduation formula: a new method to construct belief reliability distribution under epistemic uncertainty

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Journal of Systems Engineering and Electronics 2020年第3期31卷 626-633页

作者： zu Tianpei kang Rui WEN Meilin School of Reliability and Systems Engineering Beihang UniversityBeijing 100191China Key Laboratory on Reliability and Environmental Engineering Technology Beijing 100191China

In reliability engineering,the observations of the variables of interest are always limited due to cost or schedule ***,the epistemic uncertainty,which derives from lack of knowledge and information,plays a vital influence on the reliability *** reliability is a new reliability metric that takes the impact of epistemic uncertainty into consideration and belief reliability distribution is fundamental to belief reliability *** paper develops a new method called graduation formula to construct belief reliability distribution with limited *** developed method constructs the belief reliability distribution by determining the corresponding belief degrees of the *** algorithm is designed for the graduation formula as it is a set of transcendental equations,which is difficult to determine the analytical *** developed method and the proposed algorithm are illustrated by two numerical examples to show their efficiency and future application.

关键词： belief reliability belief reliability distribution epistemic uncertainty

Comparison of intraosseous access and central venous catheterization in Chinese adult emergency patients: A prospective, multicenter, and randomized study

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World Journal of Emergency Medicine 2021年第2期12卷 105-110页

作者： Yan-yan Liu Yu-peng Wang Ling-yun zu kang zheng Qing-bian Ma Ya-an zheng Wei Gao Department of Cardiology and Institute of Vascular Medicine Peking University Third HospitalNHC Key Laboratory of Cardiovascular Molecular Biology and Regulatory PeptidesKey Laboratory of Molecular Cardiovascular SciencesMinistry of EducationBeijing Key Laboratory of Cardiovascular Receptors ResearchBeijing 100191China Department of Emergency Medicine Peking University Third HospitalBeijing 100191China

BACKGROUND: It is challenging to establish peripheral intravenous access in adult critically patients. This study aims to compare the success rate of the first attempt, procedure time, operator satisfaction with the used devices, pain score, and complications between intraosseous(IO) access and central venous catheterization(CVC) in critically ill Chinese ***: In this prospective clustered randomized controlled trial, eight hospitals were randomly divided into either the IO group or the CVC group. Patients who needed emergency vascular access were included. From April 1, 2017 to December 31, 2018, each center included 12 patients. We recorded the data mentioned ***: A total of 96 patients were enrolled in the study. There were no statistically significant differences between the two groups regarding sex, age, body mass index, or operator satisfaction with the used devices. The success rates of the first attempt and the procedure time were statistically significant between the IO group and the CVC group(91.7% vs. 50.0%, P<0.001;52.0 seconds vs. 900.0 seconds, P<0.001). During the study, 32 patients were conscious. There was no statistically significant difference between the two groups regarding the pain score associated with insertion. There were statistically significant differences between the two groups regarding the pain score associated with IO or CVC infusion(1.5 vs. 0.0, P=0.044). Complications were not observed in the two ***: IO access is a safe, rapid, and effective technique for gaining vascular access in critically ill adults with inaccessible peripheral veins in the emergency departments.

关键词： Intraosseous access Central venous catheterization Success rates Procedure time Pain score

Research on blade tip clearance cavitation and turbulent kinetic energy characteristics of axial flow pump based on the partially-averaged Navier-Stokes model

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Journal of Hydrodynamics 2024年第1期36卷 184-201页

作者： Xiao-qi Jia Shuai-kang Zhang zu-chao Zhu Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech UniversityHangzhou310018China

To reveal the cavitation forms of tip leakage vortex(TLV)of the axial flow pump and the flow mechanism of the flow field,this research adopts the partially-averaged Navier-Stokes(PANS)model to simulate the cavitation values of an axial flow pump,followed by experimental *** experimental result shows that compared with the shear stress transport(SST)k-ωmodel,the PANS model significantly reduces the eddy viscosity of the flow field to make the vortex structure clearer and allow the turbulence scale to be more robustly *** cavitation area within the axial flow pump mainly comprises of TLV cavitation,clearance cavitation and tip leakage flows combined effect of triangular cloud cavitation *** formation and development of cavitation are accompanied by the formation and evolution of vortex,and variations in vortex structure also generate and promote the development of *** addition,an in-depth analysis of the relationship between the turbulent kinetic energy(TKE)transport equation and cavitation patterns was also conducted,finding that the regions with relatively high TKE are mainly distributed around gas/liquid boundaries with serious cavitation and evident gas-liquid *** phenomenon is mainly attributed to the combined effect of the pressure action term,stress diffusion term and TKE production term.

关键词： Cavitation axial flow pump tip leakage vortex(TLV) partially-averaged Navier-Stokes(PANS)model turbulent kinetic energy(TKE)

Softening–melting behavior of mixed burden based on low-magnesium sinter and fluxed pellets

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International Journal of Minerals,Metallurgy and Materials 2021年第4期28卷 621-628页

作者： Gui-lin Wang Jian kang Jian-liang Zhang Yao-zu Wang Zhi-yu Wang zheng-jian Liu Chen-yang Xu School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China School of Chemical Engineering The University of QueenslandSt LuciaQLD 4072Australia Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China Baosteel Zhanjiang Iron and Steel Co. Ltd.Zhanjiang 524072China

A low MgO content in sinter is conducive to reduce the MgO content in blast furnace *** study investigated the effect of MgO content in sinter on the softening–melting behavior of the mixed burden based on fluxed *** the MgO content increased from 1.31 wt% to 1.55 wt%, the melting temperature of sinter increased to 1521℃.Such an increase was due to the formation of the high-meltingpoint slag *** reduction degradation index of sinter with 1.31 wt% MgO content was better than that of *** initial softening temperature of the mixed burden increased from 1104 to 1126℃ as MgO content in sinter increased from 1.31 wt% to 1.55 wt%, and the melting temperature decreased from 1494 to 1460℃.The permeability index(S-value) of mixed burden decreased to 594.46 kPa·℃ under a high MgO content with 1.55 wt%, indicating that the permeability was *** slag phase composition of burden was mainly akermarite(Ca_(2)MgSiO_(7)) when the MgO content in sinter was 1.55 wt%.The melting point of akermarite is 1450℃, which is lower than other phases.

关键词： magnesia softening–melting behavior low-magnesium sinter fluxed pellets slag

Belief reliability:a scientific exploration of reliability engineering

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Journal of Systems Engineering and Electronics 2024年第3期35卷 619-643页

作者： ZHANG Qingyuan LI Xiaoyang zu Tianpei kang Rui International Innovation Institute Beihang UniversityHangzhou 311115China Science and Technology on Reliability and Environmental Engineering Laboratory Beijing 100191China School of Reliability Engineering and Systems Engineering Beihang UniversityBeijing 100191China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

This paper systematically introduces and reviews a scientific exploration of reliability called the belief *** with the origin of reliability engineering,the problems of present theories for reliability engineering are summarized as a query,a dilemma,and a ***,through philosophical reflection,we introduce the theoretical solutions given by belief reliability theory,including scientific principles,basic equations,reliability science experiments,and mathematical *** basic methods and technologies of belief reliability,namely,belief reliability analysis,function-oriented belief reliability design,belief reliability evaluation,and several newly developed methods and technologies are sequentially elaborated and *** on the above investigations,we summarize the significance of belief reliability theory and make some prospects about future research,aiming to promote the development of reliability science and engineering.

关键词： belief reliability performance margin reliability experiment chance measure uncertainty

Microstructure and Properties of Micro-Alloyed Mg-2.0Nd-0.2Sr by Heat Treatment and Extrusion

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Acta Metallurgica Sinica(English Letters) 2023年第2期36卷 323-334页

作者： Zhenzhen Gui Fan Jiang Zhixin kang Fan Zhang zu Li Jianhui Zhang School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou510006China Joint Institute of Guangzhou University and Institute of Corrosion Science and Technology Guangzhou UniversityGuangzhou510006China Guangdong Key Laboratory for Advanced Metallic Materials Processing School of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhou510640China

Magnesium(Mg)and its alloys have broad application prospects in the fields such as biomedical materials and automobile manufacturing.A micro-alloyed Mg-2.0Nd-0.2Sr(wt.%)magnesium alloy is designed and obtained through semicontinuous *** evolution of microstructures and tensile properties are investigated with different heat treatments and extrusion *** grain sizes decrease significantly after extrusion,thus changing the fracture mode during the tensile testing *** ultimate tensile strength(UTS),yield strength(YS)and elongation(EL)of the properly processed extrusion alloy(referred to as MNS-E2)reach to 247 MPa,228 MPa and 24%,*** dramatical improvement of mechanical properties results from the refined grains and interactions between dislocations and *** nanoparticle bands blocking the slippage and movement of dislocations are also found in the MNS-E2 *** above causes combined result in an integrated effect of grain boundary strengthening,dislocation strengthening,precipitation strengthening and nanoparticle band *** contribution of strengthening mechanisms of MNS-E2 alloy consists of grain boundary with around 96 MPa,dislocations with around 3.4 MPa,precipitation strengthening with around 45 MPa and the nanoparticle band with around 18 MPa,respectively.

关键词： Mg-Nd-Sr alloy Hot extrusion Mechanical properties Strengthening mechanisms

Three-dimensional contrast-enhanced MR angiography in diagnosis of portal vein involvement by hepatic tumors

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World Journal of Gastroenterology 2003年第5期9卷 1114-1118页

作者： JiangLin kang-RongZhou zu-WangChen Jian-HuaWang Zhi-QuanWu JiaFan DepartmentofRadiology AffiliatedZhongshanHospitalFudanUniversityShanghai200032China InstituteofLiverCancer AffiliatedZhongshanHospitalFudanUniversityShanghai200032China

AIM: To assess the accuracy of three-dimensional contrastenhanced magnetic resonance angiography (3D CE MRA) in evaluation of the portal vein involvement in patients with hepatic ***: 3D CE MlRA was performed in 62 patients with hepatic tumors to assess the patency of the main, right and left portal veins before hepatic surgery. A total of 186 veins were examined for encasement, occlusion and tumor thrombosis. The results of 3D CE NRA diagnosis were then correlated with the surgical-pathological and intra-operative sonographic ***: 3D CE MRA correctly detected 48 of 49 involved and 135 of 137 noninvolved portal veins with the sensitivity of 98 %, specificity of 99 %, positive predictive value of 96 % and negative predictive value of 99 %.CONCLUSION: 3D CE NRA is accurate in evaluation of the portal vein involvement in patients with hepatic tumors.

关键词：肝肿瘤肝入口血管三维增强扫描核磁共振影像学诊断肿瘤侵袭

Reaction behavior of MgO refractory with high-Mn and high-Al steel

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Journal of Iron and Steel Research International 2024年第6期31卷 1389-1398页

作者： Ling-zhong Kong Lin zu Jie Yang Xi-min Zang Xin Yang Ming kang School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina

To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were *** effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were *** was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al_(2)O_(3) spinel and(Mn,Mg)O solid *** formation mechanism of the spinel and solid solution is as *** Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al_(2)O_(3) spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al_(2)O_(3) ***,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid *** addition,only(Mn,Mg)O·Al_(2)O_(3) spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.

关键词： High-Mn high-Al steel MgO refractory Reaction behavior Spinel