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Preparation and Characterization of MWCNTs/E44

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Journal of Materials Science & Technology 2006年第1期22卷 117-122页

作者： Yan GAO Zhenjia wang Rui wang Ji liang Luke wang State Key Laboratory of Tribology Department of Mechanical Engineering Tsinghua UniversityBejing 100084China

Epoxy resin was modified by multi-walled carbon nanotubes（MWCNTs）with an in situ *** composite was observed using scanning electron microscopy （SEM）and X-ray diffraction （XRD）,and its abrasive wear resistance and tensile properties were *** results show that the function groups found on the surface of MWCNTs helped to improve the resin＇s crack resistance,and the cracks were found notably reduced in the *** the resin and MWCNTs were bonded physically ,the tensile properties and wear resistance of the composite were improved notably when an optimum amount of MWCNTs were filled in Epilote-44（E44）.When 5wt pct acidified MWCNTs were filled in E44,the elastic modulus ,breaking strength and wear resistance of the composite increase to 226.7%,303.3%and 272.55%（153.29%）,respectively.

关键词： Epoxy resin Multi-walled carbon nanotubes(MWCNTs) Tensile properties Wear resistance

High-order sliding mode attitude controller design for reentry flight

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Journal of Systems Engineering and Electronics 2014年第5期25卷 848-858页

作者： liang wang Yongzhi Sheng Xiangdong Liu School of Automation Beijing Institute of Technology Key Laboratory for Intelligent Control & Decision of Complex Systems Beijing Institute of Technology

A novel high-order sliding mode control strategy is proposed for the attitude control problem of reentry vehicles in the presence of parametric uncertainties and external disturbances, which results in the robust and accurate tracking of the aerodynamic angle commands with the finite time convergence. The proposed control strategy is developed on the basis of integral sliding mode philosophy, which combines conventional sliding mode control and a linear quadratic regulator over a finite time interval with a free-final-state and allows the finite-time establishment of a high-order sliding mode. Firstly, a second-order sliding mode attitude controller is designed in the proposed high-order siding mode control framework. Then, to address the control chattering problem, a virtual control is introduced in the control design and hence a third-order sliding mode attitude controller is developed, leading to the chattering reduction as well as the control accuracy improvement. Finally, simulation examples are given to illustrate the effectiveness of the theoretical results.

关键词： reentry vehicle attitude control high-order sliding mode control integral sliding mode.

Inference for Gompertz distribution under records

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Journal of Systems Engineering and Electronics 2016年第1期27卷 271-278页

作者： liang wang Yimin Shi Weian Yan School of Mathematics and Statistics Xidian University Department of Applied Mathematics Northwestern Polytechnical University School of Mechatronic Engineering East China Jiaotong University

The parameter estimation is considered for the Gompertz distribution under frequensitst and Bayes approaches when records are *** likelihood estimators,exact and approximate confidence intervals are developed for the model parameters,and Bayes estimators of reliability performances are obtained under different losses based on a mixture of continuous and discrete *** investigate the performance of the proposed estimators,a record simulation algorithm is provided and a numerical study is presented by using Monte-Carlo simulation.

关键词： Gompertz model records confidence interval Bayes estimation Monte-Carlo simulation

Exact inference for two exponential populations with competing risks data

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Journal of Systems Engineering and Electronics 2014年第4期25卷 711-720页

作者： Song Mao Yimin Shi liang wang School of Applied Mathematics Northwestern Polytechnical University School of Mathematics Xidian University

In a reliability comparative test, the joint censoring model is usually adopted to evaluate the performances of units with the same facility. However, most researchers ignore the pos- sibility that there is more than one factor for the failure when a test unit fails. To solve this problem, we consider a joint Type-II hybrid censoring model for the analysis of exponential competing failure data. Based on the maximum likelihood theory, we compute the maximum likelihood estimators （MLEs） of parameters and then obtain the condition ensuring MLEs existence for every unknown parameter. Then we derive the conditional exact distributions and corresponding moment properties for parameters by the moment generating function （MGF）. A Monte-Carlo simulation is conducted to compare the performances of different ways. And finally, we conduct a numerical example to illustrate the proposed method.

关键词： joint Type-II hybrid censoring competing causes mo-ment generating function likelihood inference exponential distri-bution.

Effect of magnesium addition on inclusions in H13 die steel

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International Journal of Minerals,Metallurgy and Materials 2014年第11期21卷 1062-1067页

作者： Zheng Wu Jing Li Cheng-bin Shi liang-liang wang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

The effect of magnesium addition on the number, morphology, composition, size, and density of inclusions in H13 die steel was studied. The results show that the total oxygen content in the steel can be significantly decreased to 0.0008wt%. Al2O3 and Mn S inclusions are changed into nearly spherical Mg O·Al2O3 spinel and spherical Mg O·Mg S inclusions, respectively. The number of inclusions larger than 1 μm decreases and the number of inclusions smaller than 1 μm increases with increasing magnesium content. V（N,C） precipitates around Mg O·Al2O3 and Mg O·Mg S inclusions during solidification of liquid steel. The densities of Mg O·Al2O3 spinel inclusions are lower than that of alumina inclusions. With increasing magnesium content in the Mg-containing inclusions, the density of inclusions decreases, leading to the improvement of inclusion removal efficiency.

关键词： die steel inclusions magnesium deoxidation thermodynamics

Detached-eddy simulation of supersonic flow past a spike-tipped blunt nose

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Chinese Journal of Aeronautics 2018年第9期31卷 1815-1821页

作者： Yuan XUE liang wang Song FU School of Aerospace Engineering Tsinghua University

Space vehicle in atmosphere travels mostly at supersonic speed and generates a very strong bow shockwave around its blunt nose. Oblique shock and conical separated flow zone generated by a forward disk-tip spike significantly reduce the drag by reducing the high pressure area on the blunt nose. This study employs improved delayed detached eddy simulation to investigate the characteristic flow structures around a spike-tipped blunt nose at Mach number of 3 and Reynolds number（based on the blunt-body diameter） of 2.72x10;. The calculated time-averaged quantities agree well with experimental data. Characteristic frequencies in different flow regions are extracted using fast Fourier transform. It is found that two distinct instability modes exist: oscillation mode and pulsation mode. The former is related to the foreshock/turbulence interaction with nondimensional frequency at around 0.004. The latter corresponds to the interaction between turbulence and shock structures around the blunt nose, with a typical coherent structure shedding frequency at 0.092.

关键词： Detached-eddy simulation Drag reduction Oscillation mode Pulsation mode Spike-tipped blunt vehicle Supersonic flow

Dependence Rayleigh competing risks model with generalized censored data

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Journal of Systems Engineering and Electronics 2020年第4期31卷 852-858页

作者： wang liang MA Jin’ge SHI Yimin School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an 710049China School of Mathematics Yunnan Normal UniversityKunming 650500China School of Mathematics and Statistics Xidian UniversityXi’an 710071China Department of Applied Mathematics Northwestern Polytechnical UniversityXi’an 710072China

The inference for the dependent competing risks model is studied and the dependent structure of failure causes is modeled by a Marshall-Olkin bivariate Rayleigh distribution. Under generalized progressive hybrid censoring(GPHC), maximum likelihood estimates are established and the confidence intervals are constructed based on the asymptotic theory. Bayesian estimates and the highest posterior density credible intervals are obtained by using Gibbs sampling. Simulation and a real life electrical appliances data set are used for practical illustration.

关键词： dependence competing risks bivariate distribution generalized progressive hybrid censoring(GPHC) likelihood estimation Bayesian analysis

Separation/Extraction/Detection of Chloramphenicol Using Binary Small Molecule Alcohol-Salt Aqueous Two-phase System Coupled with High-performance Liquid Chromatography

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Chemical Research in Chinese Universities 2019年第2期35卷 209-215页

作者： GUO Donggang NI liang wang liang SHAO Li School of the Environment and Safety Engineering School of Chemistry and Chemical EngineeringJiangsu UniversityZhenjiang 212013R R. China Key Laboratory of Preparation and Application of Environmental Friendly Materials Jilin Normal UniversityMinistry of EducationChangchun 130103P. RChina

A green and sensitive sample separation and purification method coupled with high-perfomiance liquid chromatography(HPLC)was developed for the analysis of chioramphenicol(CAP).One element small molecule alcohol-salt aqueous two-phase system(ATPS)can't effectively adjust the polarity of the system,but binary small molecule alcohol-salt ATPS can adjust the polarity and improve the extraction efficiency of antibiotics.A binary aqueous two-phase system based on 1-propanol+2-propanol and NaH2PO4 system was formed and applied to the separation and purification of trace CAP in real *** influence factors on partition behaviors of CAP were discussed,including the types and mass of salts,the volume ratio of alcohol,the pH,temperature and the standing *** optimal condition was found at pH=5.0,2.5 g of NaH2PO4,3.0 mL of 1-propanol and 2-propanol(volume ratio 1:1)and 30℃by using response surface *** this optimal condition,the extraction efficiency of CAP reached 98.91%,and partition coefficient of CAP was 17.31.

关键词： Binary small molecule alcohol aqueous two-phase system Partition behavior Chloramphenicol Extraction efficiency

Crucial role of Anxa2 in cancer progression:highlights on its novel regulatory mechanism

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Cancer Biology & Medicine 2019年第4期16卷 671-687页

作者： Tong wang Zhiyong wang Ruifang Niu liang wang Second Department of Breast Tumor Tianjin Medical University Cancer Institute and HospitalNational Clinical Research Center for CancerKey Laboratory of Breast Cancer Prevention and TherapyMinistry of EducationKey Laboratory of Cancer Prevention and Therapy TianjinTianjin's Clinical Research Center for CancerTianjin 300060China Public Laboratory Tianjin Medical University Cancer Institute and HospitalNational Clinical Research Center for CancerKey Laboratory of Breast Cancer Prevention and TherapyMinistry of EducationKey Laboratory of Cancer Prevention and TherapyTianjinTianjin's Clinical Research Center for CancerTianjin 300060China Modern Distance Education College Nankai UniversityTianjin 300071China

Anxa2 is the most studied member of the calcium-mediated phospholipid-binding protein family annexins and is a biomarker in *** this review,we listed clinical findings and confirmed the value of Anxa2 in early diagnosis and prognostic prediction due to its overexpression and adverse effect on the outcome in most ***2 plays a pivotal role in cancer cell proliferation,migration,invasion,metastasis,and treatment *** understanding of its cancer-promoting function might make it an ideal target for cancer ***,we systematically summarized the mechanism of Anxa2 in regulating epithelialmesenchymal transition(EMT),cytoskeleton dynamicity,cell cycle,apoptosis,angiogenesis,and immunology by using various tumor *** data emphasize the potential of Anxa2 for targeted intervention in *** Anxa2 expression,neutralizing the cell surface Anxa2,or inhibiting its activation,such as through Tyr23 phosphorylation,could be considered based on the regulatory mechanism of Anxa2 in tumor progression.

关键词： Anxa2 cancer diagnosis prognosis metastasis treatment resistance