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A method of predicting visual detectability of low-velocity impact damage in composite structures based on logistic regression model

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Chinese Journal of Aeronautics 2021年第1期34卷 296-308页

作者： Fengyang JIANG Zhidong GUAN zengshan li Xiaodong WANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

This paper proposed a new method for quantitative assessment of visual detectability of damage based on logistic regression,using the Probability of Detection(POD)as a *** were performed to establish the massive hit/miss data of visual *** investigations verified the reliability of the *** prediction function concluded comprises more than one flaw size parameters,including the depth and diameter of the *** results show that the depth and diameter of the dents are pivotal for the evaluation of detectability;the type of detection,the detection distance,and the qualifications of personnel are critical external factors to be *** function,with an accuracy rate of nearly 85%,is capable of predicting the visual detection probability of impact damage under various detection environments,which will provide a reference for the damage tolerance design of composite materials and field maintenance in the NonDestructive Testing(NDT)field.

关键词： Composite materials Damage tolerance Machine learning NDT Logistic regression

A method of determining effective elastic properties of honeycomb cores based on equal strain energy

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Chinese Journal of Aeronautics 2017年第2期30卷 766-779页

作者： Qiu Cheng Guan Zhidong Jiang Siyuan li zengshan School of Aeronautic Science and Engineering Beihang University Bejing 100083 China

A computational homogenization technique（CHT） based on the finite element method（FEM） is discussed to predict the effective elastic properties of honeycomb *** need of periodic boundary conditions（BCs） is revealed through the analysis for in-plane and out-of-plane shear moduli of models with different cell *** applying periodic BCs on the representative volume element（RVE）,comparison between the volume-average stress method and the boundary stress method is performed,and a new method based on the equality of strain energy to obtain all non-zero components of the stiffness tensor is *** of finite element（FE） analysis show that the volume-average stress and the boundary stress keep a consistency over different cell geometries and *** strain energy method obtains values that differ from those of the volume-average method for non-diagonal terms in the stiffness *** has been done on numerical results for thin-wall honeycombs and different geometries of angles between oblique and vertical *** inaccuracy of the volume-average method in terms of the strain energy is shown by numerical benchmarks.

关键词： Elastic properties Homogenization Honeycomb Strain energy Unit cells

Experimental investigation on impact performances of GLARE laminates

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Chinese Journal of Aeronautics 2015年第6期28卷 1784-1792页

作者： Chen Qi Guan Zhidong li zengshan Ji Zhaojie Zhuo Yue School of Aeronautic Science and Engineering Beihang University

An experimental investigation was carried out on the damage resistance to a concen- trated quasi-static indentation force and low-velocity impact of four kinds of glass-reinforced aluminum laminates （GLARE for short）. Compared with the experimental results of the CFRP （Carbon Fiber Reinforced Plastics） laminates, the performance of GLARE was determined. By means of concentrated quasi-static indentation force test, typical force displacement response, the maximum contact force and dent depth were received, Through drop-weight low-velocity impact tests, impact force histories, indentation depths （through a new method） and dissipated energy were obtained. The test results show that the force-displacement response of GLARE 4 laminates under the concentrated quasi-static indentation force has an obvious fiat roof and the failure is instantaneous, which are different from CFRP laminates. The indention will be visible once the impact happens. C-scan results find that there is no delamination besides the impact area after both the concentrated quasi-static indentation and low-velocity impact. The dissipated energy approximately equals the impact energy.

关键词： Concentrated quasi-staticindentation force Delamination GLARE laminate Impact Indentation

Compressive failure analysis of unidirectional carbon/epoxy composite based on micro-mechanical models

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Chinese Journal of Aeronautics 2017年第6期30卷 1907-1918页

作者： Wei SUN Zhidong GUAN zengshan li Mi ZHANG Yongjie HUANG School of Aeronautic Science and Engineering Beihang University Beijing 100083 China

A 2D micro-mechanical model was proposed to study the compressive failure of Uni Directional（UD） carbon/epoxy composite. Considering the initial imperfection and strength distribution of the fiber, the plasticity and ductile damage of the matrix, the failure of T300/914 UD composite under longitudinal compression and in-plane combined loads was simulated by this model. Simulation results show that the longitudinal compressive failure of the UD composite is caused by the plastic yielding of the matrix in kink band, and the fiber initial imperfection is the main reason for it. Under in-plane combined loads, the stress state of the matrix in kink band is changed, which affects the longitudinal compressive failure modes and strength of UD *** failure envelope of r_1–s_（12） and r_1–r_2 are obtained by the micro-mechanical model. Meanwhile,the compressive failure mechanism of the UD composite is analyzed. Numerical results agree well with the experimental data, which verifies the validity of the micro-mechanical model.

关键词： Micro-mechanical model Unidirectional composite Initial imperfection Matrix plasticity Ductile damage Kink band

Buckling and post-buckling behavior of titanium alloy stiffened panels under shear load

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Chinese Journal of Aeronautics 2019年第3期32卷 619-626页

作者： Yuru SU Zhidong GUAN Xin WANG zengshan li Jun GUO Yongjie HUANG School of Aeronautic Science and Engineering Beihang University

Titanium alloy has been increasingly applied in aviation industry due to its superior performance. However, the titanium alloy structures are less studied. This work investigates the structural behavior of Ti6Al4V titanium alloy stiffened panels under in-plane shear load by experiments and numerical analysis. After the shear tests, the buckling instability, the post-buckling process and the failure mechanism of the specimen were obtained. The Finite Element(FE) models were established with the subsequent validation verification. A parametric analysis was implemented to study the influence of stringer thickness and stringer height on the behavior of the stiffened panels. The results show that after the initial local buckling on the skin, the buckling mode jumps several times with the increase of load. The stringers twist when the load reaches a certain level, and finally the structure damages due to the plastic deformation and the global buckling. The shear clip has little effect on the buckling and failure loads. Compared to the relatively large effect on the buckling load, the influence of the stringer thickness and stringer height on the failure load is *** to the parametric analysis, the stringer thickness influences the final buckling mode and failure mode, while the stringer height affects the buckling mode transformation.

关键词： Buckling Finite Element Method(FEM) In-plane shear loading Stiffened panel Stringer height Stringer thickness Titanium alloys

Progress of the RF negative hydrogen ion source for fusion at HUST

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Plasma Science and Technology 2022年第12期24卷 149-156页

作者： Chen ZUO Peng CHEN zengshan li Jinghan YANG Fei SONG Dezhi CHEN State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhan 430074People's Republic of China

Huazhong University of Science and Technology has developed an experimental setup of a radio frequency(RF) driven negative hydrogen ion source,to investigate the physics of production and extraction of the H^(-)ions for neutral beam injection in nuclear fusion *** main design parameters of the ion source are:RF power ≤40 kW;extraction voltage ≤10kV;accelerator voltage ≤20 *** paper gives an overview of the progress of the ion source with particular emphasis on some *** RF driver and source plasma are analyzed and optimized in terms of impedance matching,plasma characteristics and power *** regard to the simulation analysis,a plasma model based on the particle-in-cell method and a beam trajectory model considering beam stripping loss are developed to investigate the plasma and negative ions transport inside the ion ***,a collisional radiative model of H and H2is built for plasma optical diagnosis.

关键词： negative ion sources radio frequency(RF) particle-in-cell(PIC) beam simulation

Observation on therapeutic efficacy of ursodeoxycholic acid in Chinese patients with primary biliary cirrhosis:a 2-year follow-up study

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Frontiers of Medicine 2013年第2期7卷 255-263页

作者： Jiangyi Zhu Yongquan Shi Xinmin Zhou zengshan li Xiaofeng Huang Zheyi Han Jianhong Wang Ruian Wang Jie Ding Kaichun Wu Ying Han Daiming Fan State Key Laboratory of Cancer Biology Institute of Digestive DiseasesXijing HospitalFourth Military Medical UniversityXi’an 710032China Department of Pathology Xijing HospitalFourth Military Medical UniversityXi’an 710032China

The efficacy of ursodeoxycholic acid(UDCA)on long-term outcome of primary biliary cirrhosis(PBC)has been less documented in Chinese *** aimed to assess the therapeutic effect of UDCA on Chinese patients with *** the present study,67 patients with PBC were treated with UDCA(13–15 mg∙kg^(-1)∙day^(-1))and followed up for 2 years to evaluate the changes of symptoms,laboratory values and histological *** the results indicated,fatigue and pruritus were obviously improved by UDCA,particularly in patients with mild or moderate *** alkaline phosphatase andγ-glutamyl transpetidase levels significantly declined at year 2 comparing to baseline values,with the most profound effects achieved in patients at stage *** levels of alanine aminotransferase and aspartate aminotransferase significantly decreased whereas serum bilirubin and immunoglobulin M levels exhibited no significant *** feature was stable in patients at stages 1–2 but still progressed in patients at stages 3–*** biochemical response of patients at stage 2 was much better than that of patients at stages 3–*** data suggest that,when treated in earlier stage,patients in long-term administration of UDCA can gain favorable results not only on symptoms and biochemical responses but also on *** is also indicated that later histological stage,bad biochemical response and severe symptom may be indicators of poor prognosis for UDCA therapy.

关键词： primary biliary cirrhosis ursodeoxycholic acid Chinese biochemical response therapeutic efficacy

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胃肠胰神经内分泌肿瘤分类及病理学进展

浙江大学学报（医学版） 2016年第1期45卷 10-23页

作者：李增山第四军医大学病理学教研室西京医院病理科西京消化病医院病理科陕西西安710032

胃肠胰神经内分泌肿瘤属于一组少见的异质性肿瘤，其发病率在过去的40年中有较大幅度的上升。对该类肿瘤的不断认识以及内镜和影像技术的发展导致检出率增高可能是其中的重要因素。这类肿瘤具有特定的形态学和免疫表型，从过去的“类癌... 详细信息

胃肠胰神经内分泌肿瘤属于一组少见的异质性肿瘤，其发病率在过去的40年中有较大幅度的上升。对该类肿瘤的不断认识以及内镜和影像技术的发展导致检出率增高可能是其中的重要因素。这类肿瘤具有特定的形态学和免疫表型，从过去的“类癌”到现在的“神经内分泌肿瘤”，其命名及分类经历了较大的变化。目前WHO根据其分化程度、形态学和增殖活性将其分为神经内分泌瘤和神经内分泌癌，但不同解剖部位的肿瘤具有各异的表型和生物学行为，因此具有不同的分期系统，用于提示预后和指导治疗。此外，近年的研究显示不同部位的神经内分泌肿瘤可表达一些特定的分子生物学标志物，这对于研究其生物学特征和转移性病变原发部位的判定有一定的提示意义。在分子生物学机制方面，神经内分泌肿瘤相关的信号转导通路、表观遗传学和肿瘤微环境变化等方面的研究也取得了丰硕的成果。伴随着上述的研究进展，神经内分泌肿瘤的诊治模式也随之发生了较大的变化。本文综述了胃肠胰神经内分泌肿瘤在分类、临床病理特征和分子生物学机制等方面的研究进展。

关键词：胃肠肿瘤/病理学胃肠肿瘤/分类胰腺肿瘤/分类胰腺肿瘤/病理学癌,神经内分泌/病理学癌, 神经内分泌/分类神经内分泌瘤/病理学神经内分泌瘤/分类综述

Ultrastructural Differential Diagnosis of Autoimmune liver Diseases and Other liver Diseases

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Ultrastructural Differential Diagnosis of Autoimmune Liver D...