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Experiments on self-excited oscillation in a thin-walled collapsible tube

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Acta Mechanica Sinica 2015年第6期31卷 817-826页

作者： Hai-Jun Wu Lai-Bing jia xie-Zhen Yin Department of Modern Mechanics University of Science and Technology of China Department of Naval Architecture and Marine Engineering University of Strathclyde

Self-excited oscillation in a collapsible tube is an important phenomenon in physiology. An experimental approach on self-excited oscillation in a thin-walled collapsi- ble tube is developed by using a high transmittance and low Young＇s modulus silicone rubber tube. The elastic tube is manufactured by the method of centrifugal casting in our laboratory. An optical method for recording the evolution of the cross-sectional areas at a certain position along the longitudinal direction of the tube is developed based on the technology of refractive index matching. With the transparent tube, the tube law is measured under the static no-flow condition. The cross section at the middle position of the tube transfers from a quasi-circular configuration to an ellipse, and then to a dumbell-shape as the chamber pressure is increased. During the self-excited oscillation, two periodic self-excited oscillating states and one transitional oscillating state are identified. They all belong to the LU mode. These different oscillating states are related to the initial cross-sectional shape of the tube caused by the difference of the downstream transmural pressure.

关键词： Collapsible tube Refractive index matching ·Cross-sectional area measurement· Self-excited oscillatingstates LU mode

Analysis of Early-Warning Threshold for Metro Construction Collapse Risk Based on D-S Evidence Theory and Rough Set

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Wuhan University Journal of Natural Sciences 2017年第6期22卷 510-516页

作者： xie Yi LIU jia School of Traffic and Transportation Changsha University of Science and Technology Changsha 410076 Hunan China Wuhan Engineering Consulting Bureau Wuhan 430014 Hubei China School of Information and Safety Zhongnan University of Economics and Law Wuhan 430073 Hubei China

The existing early-warning system in metro construction are generally based on traditional single-sensor data and simple analytic model, which makes it difficult to deal with the complex and comprehensive environment in metro construction. In this paper, the framework of early-warning threshold for metro construction collapse risk based on D-S evidence theory and rough set is built. By combining the primary data fusion collected based on rough set with the secondary data fusion which is based on D-S evidence theory, the integration of multiple information in metro construction is realized and the risk assessment methods are optimized. A case trial based on Hangzhou metro construction collapse accident is also carried out to exemplify the framework. The empirical analysis guarantees the completeness and independence of the prediction information, and realizes the dynamic prediction of the variation trend of metro construction collapse risk.

关键词： metro construction collapse risk early-warning D-S evidence theory rough set

The essential functions of mitochondrial dynamics in immune cells

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Cellular & Molecular Immunology 2020年第7期17卷 712-721页

作者： jia-Huan xie Yi-Yuan Li Jin Jin MOE Laboratory of Biosystem Homeostasis and Protection and Life Sciences Institute Zhejiang UniversityHangzhou 310058China Key Laboratory for Developmental Genes and Human Disease Ministry of EducationInstitute of Life SciencesJiangsu Province High-Tech Key Laboratory for Biomedical ResearchSoutheast UniversityNanjing 210096China Sir Run Run Shaw Hospital College of Medicine Zhejiang UniversityHangzhou 310016China

Mitochondria are highly mobile organelles due to fission,fusion,transport,and mitophagy,and these processes are known as mitochondrial *** dynamics play an important role in energy production,cell division,cell differentiation,and cell *** the past decade,numerous studies have revealed the importance of mitochondrial metabolism in immunity,and mitochondrial dynamics are essential for immune responses mediated by various cell *** this review,we mainly discuss the role of mitochondrial dynamics in activation,differentiation,cytokine production,and the activity of related pathways in immune cells,particularly T cells,B cells,and other cells involved in the innate immune response.

关键词： Mitochondrial dynamics Metabolism T cell B cell Innate immune cell

Ultra low frequency waves observed by Double Star TC-1 in the plasmasphere boundary layer

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Science China(Technological Sciences) 2008年第10期51卷 1685-1694页

作者： xie lun ZHANG Xiaojia PU ZuYin WANG YongFu FU SuiYan ZONG QiuGang Department of Geophysics Peking UniversityBeijing 100871China

The characteristic and properties of ULF waves in the plasmasphere boundary layer during two very quiet periods are present. The ULF waves were detected by Double Star TC-1 when the spacecraft passed through the plasmasphere in an outbound and inbound trajectories, respectively. A clear association between the ULF waves and periodic variations of energetic ions fluxes was observed. The ob-servations showed that the wave frequency was higher inside the plasmasphere than outside. The mechanism generating these ULF waves and possible diagnos-ing of the "classical plasmapause" location with the ULF wave were discussed.

关键词： ULF wave PBL plasmasphere plasmapause DSP TC-1

Diurnal and Seasonal Variations of CO2Fluxes and Their Climate Controlling Factors for a Subtropical Forest in Ningxiang

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Advances in Atmospheric Sciences 2015年第4期32卷 553-564页

作者： jia Binghao xie Zhenghui ZENG Yujin WANG Linying WANG Yuanyuan xie Jinbo xie Zhipeng State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

In this study, the diurnal and seasonal variations of CO2 fluxes in a subtropical mixed evergreen forest in Ningxiang of Hunan Province, part of the East Asian monsoon region, were quantified for the first time. The fluxes were based on eddy covariance measurements from a newly initiated flux tower. The relationship between the CO2 fluxes and climate factors was also analyzed. The results showed that the target ecosystem appeared to be a clear carbon sink in 2013, with integrated net ecosystem CO2exchange（NEE）, ecosystem respiration（RE）, and gross ecosystem productivity（GEP） of-428.8, 1534.8 and1963.6 g C m^-2yr^-1, respectively. The net carbon uptake（i.e. the-NEE）, RE and GEP showed obvious seasonal variability,and were lower in winter and under drought conditions and higher in the growing season. The minimum NEE occurred on12 June（-7.4 g C m^-2d^-1）, due mainly to strong radiation, adequate moisture, and moderate temperature; while a very low net CO2 uptake occurred in August（9 g C m^-2month^-1）, attributable to extreme summer drought. In addition, the NEE and GEP showed obvious diurnal variability that changed with the seasons. In winter, solar radiation and temperature were the main controlling factors for GEP, while the soil water content and vapor pressure deficit were the controlling factors in summer. Furthermore, the daytime NEE was mainly limited by the water-stress effect under dry and warm atmospheric conditions, rather than by the direct temperature-stress effect.

关键词： net ecosystem exchange diurnal and seasonal variations climate controlling factors subtropical mixed forest East Asian monsoon r

Theoretical and experimental study on the inhibition of jet fuel oxidation by diarylamine

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Chinese Journal of Chemical Engineering 2023年第4期56卷 225-232页

作者： Tinghao jia Yunbo Yu Qing Liu Yao Yang Ji-Jun Zou Xiangwen Zhang lun Pan Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311200China Key Laboratory for Green Chemical Technology of the Ministry of Education School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Antioxidants addition is believed as a facile and effective way to improve jet fuel thermal oxidation ***,amine antioxidants,as one of the most important antioxidants,have not received sufficient attention in the field of jet fuel autoxidation ***,the inhibition efficiency and mechanism of decane and exo-tetrahydrodicyclopentadiene(THDCPD)oxidation by di-4-tert-butylphenylamine(diarylamine)was experimentally and theoretically *** results show that diarylamine can significantly inhibit decane oxidation but is less efficient for THDCPD oxidation,which is attributed to the higher energy barrier of retro-carbonyl-ene reaction(rate-determining step)in THDCPD than that in decane during diarylamine ***,the addition of diarylamine will cause undesirable color change after accelerated oxidation and produce slightly more deposits during high-temperature thermal oxidative stress for both decane and *** results provide significant implications for the future design of effective antioxidant additives for high-performance jet fuel.

关键词： Jet fuel Thermal oxidation stability High-energy-density fuel Diarylamine Antioxidation mechanism

Effect of cooling rate upon the microstructure and mechanical properties of in-situ TiC reinforced high entropy alloy CoCrFeNi

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Journal of Materials Science & Technology 2020年第7期42卷 122-129页

作者： Jifeng Zhang Ting jia Huan Qiu Heguo Zhu Zonghan xie College of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Mechanical Engineering University of AdelaideSA 5005Australia School of Engineering Edith Cowan UniversityWA 6027Australia

Three types of in-situ TiC(5 vol%,10 vol%and 15 vol%)reinforced high entropy alloy CoCrFeNi matrix composites were produced by vacuum induction *** effect of two extreme cooling conditions(i.e.,slow cooling in fu rnace and rapid cooling in copper crucible)upon the microstructure and mechanical properties was *** the case of slow cooling in the furnace,TiC was found to form mostly along the grain boundaries for the 5 vol%*** the increase of TiC reinforcements,fibrous TiC appeared and extended into the matrix,leading to an increase in *** ultimate tensile strength of the composites shows a marked variation with increasing TiC content;that is,425.6 MPa(matrix),372.8 MPa(5 vol%),550.4 MPa(10 vol%)and 334.3 MPa(15 vol%),while the elongation-to-failure(i.e.,ductility)*** fracture pattern was found to transit from the ductile to cleavage fracture,as the TiC content *** the samples cooled rapidly in copper crucible,the TiC particles formed both along the grain boundaries and within the *** the increase of TiC volume fraction,both the hardness and ultimate tensile strength of the resulting composites improved steadily while the elongation-to-failure ***,the fast cooling can be used to drastically improve the strength of in-situ TiC reinforced *** example,for the 15 vol%TiC/CoCrFeNi composite cooled in the copper crucible,the hardness and ultimate tensile strength can reach as high as 595 HV and 941.7 MPa,respectively.

关键词： High entropy alloy matrix composites Cooling rate Microstructure Mechanical properties

GMDH-Based Outlier Detection Model in Classification Problems

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Journal of Systems Science & Complexity 2020年第5期33卷 1516-1532页

作者： xie Ling jia Yanlin XIAO Jin GU Xin HUANG Jing School of Medical Information Engineering Zunyi Medical UniversityZunyi 563006China Business School Sichuan UniversityChengdu 610064China Soft Science Institute Sichuan UniversityChengdu 610064China School of Public Administration Sichuan UniversityChengdu 610064China

In many practical classification problems,datasets would have a portion of outliers,which could greatly affect the performance of the constructed *** order to address this issue,we apply the group method of data handin neural network in outlier *** study builds a GMDH-based outlier detectio *** model first implements feature selection in the training set L using GMDH neural *** a new training set L can be obtained by mapping the selected key feature ***,a linear regression model can be constructed in the set L by ordinary least squares ***,it eliminates a sample from the set L randomly every time,and then rebuilds a linear regression ***,outlier detection is realized by calculating Cook’s distance for each *** different customer classification datasets are used to conduct *** show that GOD model can effectively eliminate outliers,and compared with the five existing outlier detection models,it generally performs significantly *** indicates that eliminating outliers can effectively enhance classification accuracy of the trained classification model.

关键词： Classification problem Cook’s distance feature selection GMDH outlier detection

A posteriori error estimator for eigenvalue problems by mixed finite element method

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Science China Mathematics 2013年第5期56卷 887-900页

作者： jia ShangHui CHEN HongTao xie HeHu School of Applied Mathematics Central University of Finance and Economics School of Mathematical Sciences Xiamen University LSEC NCMISInstitute of Computational MathematicsAcademy of Mathematics and Systems ScienceChinese Academy of Sciences

In this paper,a residual type of a posteriori error estimator for the general second order elliptic eigenpair approximation by the mixed finite element method is derived and analyzed,based on a type of superconvergence result of the eigenfunction *** efficiency and reliability are proved by both theoretical analysis and numerical experiments.

关键词： second order elliptic eigenvalue problem mixed finite element method Raviart-Thomas a pos- teriori error estimate adaptive