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Inverse identification of the mechanical parameters of a pipeline hoop and analysis of the effect of preload

Frontiers of Mechanical Engineering 2019年第3期14卷 358-368页

作者： ye gao Wei SUN School of Mechanical Engineering and Automation Northeastern University Shenyang 110819 China Key Laboratory of Vibration and Control of Aero-Propulsion Systems Ministry of Education of China Northeastern University Shenyang 110819 China

To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffiiess and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffiiess and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.

关键词： inverse identification pipeline hoop fiequency response function mechanical parameters preload

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DIMENSIONS OF ATACTIC POLY(α-METHYLSTYRENE)CHAINS WITH SIDE GROUPS

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Chinese Journal of Polymer Science 2006年第1期24卷 87-93页

作者： Hai-zhu Ma gao-xiang ye Department of Physics Zhejiang University Hangzhou 310027 China Department of Physics Zhejiang Education Institute Hangzhou 310012 China

An improved configurational-confomational statistical method is developed and the mean-square radius of gyration for atactic poly（α-methylstyrene）（PαMS） chains is studied, in which the effect of large side groups is considered. The deduced formulas, based on the rotational isomer state theory, are used to investigate the configuration-dependent properties of the atactic polymer chain, and the statistical correlation of the unperturbed polymer chain dimension and structure parameters are calculated. For the fraction of meso dyads Wm= 0.4, the dependence of the radius of gyration Rg and the intrinsic viscosity [η] on the molecule mass M are Rg = 2.63×10^-2 M^0.50 nm and [η] = 7.36 × 10^-2 M^0.497, respectively, which are in agreement with the previous experimental data for the PαMS samples. A small hump is detected in the curve of the characteristic ratio of the unperturbed mean-square radius of gyration versus the chain length for short PαMS chains. The Rg increases linearly with the temperature T, and the effects of the chain length and the tacticity on the temperature coefficient are remarkable. These are quite different from the results for PαMS chains not considering side groups or for the monosubstituted polystyrene chain.

关键词： Side groups Rotational isomeric state Radius of gyration Poly(α-methylstyrene) chain.

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Unperturbed dimensions of atactic poly(dibenzyl itaconate)s

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 991-998页

作者： MA Hai-zhu ye gao-xiang Department of Physics Zhejiang University Hangzhou 310027 China School of Science and Technology Zhejiang Education Institute Hangzhou 310012 China

The unperturbed dimension and temperature character of poly(dibenzyl itaconate)s (PDBzI) are studied by a revised rotational isomeric state (RIS) method. The improved formulas of the mean-square radius of gyration, deduced by the pseudo-stereochemical equilibrium approach, may be used to investigate the configurational-conformational properties of atactic polymers with large side groups [poly(itaconates) for instance]. The calculated results showed that poly(itaconates) have larger dimension of the molecule than other vinyl polymers. Comparison of the dimension between considering and without considering side groups showed that the effect of large side groups on the unperturbed dimension for short-chain polymers is more obvious than that of long-chain polymers and, if the dimension of side groups increases, the effect also increases. The dimension differences of PDBzI between short-chain and long-chain polymers are investigated by the relation of characteristic ratios and temperature coefficients with temperature. Moreover, the dependence between the temperature coefficients and the tacticity of chains shows that the temperature characters of the isotactic, syndiotactic and atactic PDBzI chains have remarkable difference.

关键词： Poly(dibenzyl itaconate)s Mean-square radius of gyration Temperature coefficient Tacticity

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Numerical Study on Characteristics of Supercavitating Flow Around the Variable-Lateral-Force Cavitator

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China Ocean Engineering 2017年第1期31卷 123-129页

作者： HU Xiao gao ye SHI Xiao-tao College of Hydraulic and Environmental Engineering China Three Gorges University Yichang 443008 China Engineering Research Center of Eco-environment in Three Gorges Reservoir Region Ministry of Education China Three Gorges University Yichang 443008 China Department of Aerospace and Building Engineering Harbin Engineering University Harbin 150001 China

A control scheme named the variable-lateral-force cavitator, which is focused on the control of lift force, drag force and lateral forces for underwater supercavity vehicles was proposed, and the supercavitating flow around the cavitator was investigated numerically using the mixture multiphase flow model. It is verified that the forces of pitching, yawing, drag and lift, as well as the supercavity size of the underwater vehicle can be effectively regulated through the movements of the control element of the variable-lateral-force cavitator in the radial and circumferential directions. In addition, if the control element on either side protrudes to a height of 5% of the diameter of the front cavitator, an amount of forces of pitching and yawing equivalent to 30% of the drag force will be produced, and the supercavity section appears concave inwards simultaneously. It is also found that both the drag force and lift force of the variable-lateral-force cavitator decline as the angle of attack increases.

关键词： supercavitating flow cavitator drag force lateral forces numerical investigation

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A Quaternion Two-Stream R-CNN Network for Pixel-Level Color Image Splicing Localization

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Chinese Journal of Electronics 2021年第6期30卷 1069-1079页

作者： CHEN Beijing JU Xingwang gao ye WANG Jinwei Engineering Research Center of Digital Forensics Ministry of Education Nanjing University of Information Science &Technology School of Computer Nanjing University of Information Science & Technology Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET) Nanjing University of Information Science & Technology

Recently, Zhou et al. designed a twostream faster Region-Convolutional neural networks(RCNN) model RGB-N for color image splicing localization in CVPR2018. However, the RGB-N locates spliced regions only at block-level and ignores the entirety and inherent correlation of three channels. Therefore, an improved quaternion two-stream R-CNN model is proposed to solve these drawbacks: a mask branch combining fully convolutional network and condition random field is added for locating spliced regions at pixel-level; quaternion representation of color images is used to process color spliced images in a holistical way. In addition, feature pyramid network based on quaternion residual network is considered to extract multi-scale features for color spliced images; attention region proposal network is combined with attention mechanism and is designed to pay more attention to the spliced regions; a high-pass filter designed for image splicing detection specifically is adopted to replace steganalysis rich model filter in the RGB-N to obtain noise input for the noise stream. Experimental results on a new synthetic dataset and three standard forgery datasets demonstrate that the proposed method is superior to the existing methods in the abilities of localization, generalization, and robustness.

关键词： quaternion residual network image classification feature extraction image splicing detection convolutional neural nets RGB-N block-level color spliced images steganalysis rich model filter spliced regions noise stream feature pyramid network image segmentation attention region proposal network quaternion two-stream R-CNN network improved quaternion two-stream R-CNN model two-stream faster region-convolutional neural networks image colour analysis quaternion representation fully convolutional network object detection pixel-level color image splicing localization

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The new multistage water adsorption model of Longmaxi Formation shale considering the spatial configuration relationship between organic matter and clay minerals

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Petroleum Science 2022年第5期19卷 1950-1963页

作者： Zhi-ye gao Shu-Ling Xiong Lin Wei State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China Unconventional Petroleum Research Institute China University of PetroleumBeijing102249China School of Energy Resources China University of GeosciencesBeijing100083China

The water adsorption by shale significantly affects shale gas content and its seepage ***,the mechanism of water adsorption by shale is still unclear due to its strong heterogeneity and complicated pore *** relationship between the adsorbed water content at different relative humidities(RHs)and shale compositions,as well as shale pore structure and the spatial configuration relationship between organic matter(OM)and clay minerals,was investigated to clarify the controlling factors and mechanisms of water adsorption by Longmaxi Formation shale from the Southern Sichuan Basin in ***,the water adsorption process could be generally divided into three different stages from 0%RH to 99%***,the Johnston’s clay mine ral interlayer pore structure model(JCM),the Freundlich model(FM)and the Dubinin-Astakhov model(DAM)were tested to fit the three water adsorption stages from low RH to high RH,*** fitting results of the JCM and FM at lower RHs were far from good,while the fitting results of DAM at higher RHs were ***,two revised models(LRHM and MRHM)considering the spatial configuration relationship between OM and clay minerals were proposed for the two stages with lower RHs,and performed better fitting results indicating the pronounced effect of the spatial configuration relationship between OM and clay minerals on the water adsorption process of Longmaxi Formation *** outcomes of this study will contribute to clarifying the water distribution characteristics in the pore network of shale samples with variable water contents.

关键词： Longmaxi formation shale Water content OM-clay complexes Spatial occurrence relationship

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Numerical analysis of added mass and damping of elastic hydrofoils

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Journal of Hydrodynamics 2020年第5期32卷 1009-1023页

作者： Jia-sheng Li ye-gao Qu Hong-xing Hua School of Naval Architecture and Ocean Engineering Huazhong University of Science and TechnologyWuhan 430074China Hubei Provincial Engineering Research Center of Data Techniques and Supporting Software for Ships(DTSSS) Wuhan 430074China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

A numerical model is proposed for analyzing the effects of added mass and damping on the dynamic behaviors of *** coupled fluid-structure interactions(FSIs)of hydrofoils are analyzed by using the 3-D panel method for the fluid and the finite element method for the *** added mass and damping matrices due to the external fluid of the hydrofoil are asymmetric and computational *** computational inefficiencies associated with these asymmetric matrices are overcome by using a modal reduction technique,in which the first several wet mode vectors of the hydrofoil are employed in the analysis of the FSI *** discretized system of equations of motion for the hydrofoil are solved using the Wilson-6 *** present methods are validated by comparing the computed results with those obtained from the finite element *** is found that the stationary flow is sufficient for determining the wet modes of the hydrofoil under the condition of single-phase potential flow and without phase *** the case of relatively large inflow velocity,the added damping of the fluid can significantly affect the structural responses of the hydrofoil.

关键词： Fluid-structure interaction(FSI) hydroelastic response hydrofoil added mass added damping

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Microstructure and phase composition of hypoeutectic Te–Bi alloy as evaporation source for photoelectric cathode

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International Journal of Minerals,Metallurgy and Materials 2018年第5期25卷 584-590页

作者： Bao-guang Wang Wen-hui Yang Hong-ye gao Wen-huai Tian School of Materials Science and Engineering University of Science and Technology Beijing Faculty of Engineering Sciences Kyushu University

A hypoeutectic 60Te–40Bi alloy in mass percent was designed as a tellurium atom evaporation source instead of pure tellurium for an ultraviolet detection *** alloy was prepared by slow solidification at about 10^(-2) K·s^(-1).The microstructure,crystal structure,chemical composition,and crystallographic orientation of each phase in the as-prepared alloy were investigated by optical microscopy,scanning electron microscopy,X-ray diffraction,electron backscatter diffraction,and transmission electron *** experimental results suggest that the as-prepared 60Te–40Bi alloy consists of primary Bi_2Te_3 and eutectic Bi_2Te_3/Te *** primary Bi_2Te_3 phase has the characteristics of faceted *** eutectic Bi_2Te_3 phase is encased by the eutectic Te phase in the eutectic *** purity of the eutectic Te phase reaches 100wt%owing to the slow *** the eutectic phases,the crystallographic orientation relationship between Bi_2Te_3 and Te is confirmed as[0001]_(Bi2 Te3)//[1213]_Te and the direction of Te phase parallel to[1120]_(Bi2 Te3)is deviated by 18°from N(2111)_Te.

关键词： Te–Bi alloy microstructure orientation misfit

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One-pot Synthesis and Crystal Structure of (1S,2R,3S,4R,5S)-1-Phenyl-2,4-dibenzoyl-3,5-difurylhexanol

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Chinese Journal of Structural Chemistry 2006年第6期25卷 699-703页

作者： CHEN Xiang-Ming YIN ye-gao CHEN He-Ru DING Jun Department of Chemistry Shantou University Shantou Guangdong 515063 China

（1S,2R,3S,4R,5S）-1-Phenyl-2,4-dibenzoyl-3,5-difurylhexanol 1 was synthesized by one-pot reaction of hypnone and furfurol in alkali H2O/EtOH solution and structurally defined to contain a chair-formed aliphatic carbo... 详细信息

关键词： substituted cyclohexanol one-pot synthesis crystal structure hydrogen bond

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Endoscopic retrograde cholangiopancreatography and laparoscopic cholecystectomy during the same session:Feasibility and safety

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World Journal of Gastroenterology 2013年第36期19卷 6093-6097页

作者： Jin-Feng Zang Chi Zhang Jun-ye gao Department of Hepatobiliary Surgery Taizhou People’s Hospital the Fifth Affiliated Hospital of Medical School of Nantong University

AIM:To explore the feasibility and safety of endoscopic retrograde cholangiopancreatography and laparoscopic cholecystectomy(LC)performed during the same ***:Between July 2010 and May 2013,156patients with gallstones and common bile duct(CBD)stones were enrolled in this retrospective *** to the sequence of endoscopic procedures and LC,patients were classified into two groups:in group1,patients underwent endoscopic stone extraction and LC during the same session,and in group 2,patients underwent LC at least 3 d after endoscopic stone *** of the endoscopic procedures and LC were compared between the two groups,***:There were 91 patients in group 1 and65 patients in group *** characteristics of the two groups were *** mean duration of the endoscopic procedures was 34.9 min in group 1 and 35.3min in group *** were no significant differences in the success rate of the endoscopic procedures(97.8%for group 1 vs 98.5%for group 2),the total rate of endoscopic complications(4.40%for group 1 vs 4.62%for group 2)and CBD stone clearance rate(96.7%for group 1 vs 96.9%for group 2).Duration of LC was53.6 min in group 1 and 52.8 min in group *** were no significant differences in the overall LC-related morbidity and postoperative hospital ***:Endoscopic stone extraction and LC performed during the same session was feasible and safe in patients with gallstones and concomitant CBD stones.

关键词： Cholecystectomy Laparoscopic Endoscopic Therapy

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