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Thermodynamic Research on Precipitates in Low Carbon Nb-Microalloyed Steels Produced by Compact Strip Production

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Journal of Materials Science & Technology 2007年第2期23卷 267-272页

作者： Song xiang Guoquan liU yang li Changrong li Andong WANG School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Microalloying element Nb in low carbon steels produced by compact strip production （CSP） process plays an important role in inhibiting recrystallization, decreasing the transformation temperature and grain *** decreasing the rolling temperature, dislocations can be pinned by carbonitrides and the strength is increased. Based on the two sublattice model, with metal atom sublattice and interstitial atom sublattice,a thermodynamic model for carbonitride was established to calculate the equilibrium between matrix and carbonitride. In the steel produced by CSP, the calculation results showed that the starting temperature of precipitation of Ti and Nb are 1340℃ and 1040℃, respectively. In the range of 890-950℃, Nb rapidly precipitated. And the maximum of the atomic fraction of Nb in carbonitride was about 0.68. The morphologies and energy spectrum of the precipitates showed that （NbTi）（CN） precipitated near the dislocations. The experiment results show that Nb rapidly precipitated when the temperature was lower than 970℃, and the atomic fraction of Nb in carbonitride was about 60%-80%. The calculation results are in agreement with the experiment data. Therefore the thermodynamic model can be a useful assistant tool in the research on the precipitates in the low carbon steels produced by CSP.

关键词： Compact strip production Niobium Low carbon microalloyed steels Precipitation Thermodynamic model

Effect of tongue clearance on hydraulic performance of double support vortex pump

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Defence Technology（防务技术） 2019年第4期15卷 645-654页

作者： xiang-yang li Wan-qiang Chen Sheng-dun Zhao Pump Equipment Engineering Research Center of Shaanxi Province Xi'an Aeronautical University Xi'an 710077 China School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China

In order to study influence of tongue clearance on the hydraulic performance of double support vortex pump,three dimensional flow model with symmetric variable size tongue clearance was established by changing section parameter of tongue clearance,and applied to numerically simulate the steady inner flow in a vortex pump based on fixed working conditions and impeller through ANSYS *** numerical results show the influence of tongue channel with two sections(non-uniform and uniform sections)on flow field characteristics in vortex ***,the variation of tongue channel section changes the vortex structure distribution in circumferential flow *** the spiral forward vortex structure in the circumferential direction shifts to large radius side with increasing tongue ***,the circumferential velocity gradient and axial pressure gradient both diminish with the increase of the tongue section,and the inlet/outlet pressure difference and velocity distribution also reduce with increasing tongue channel ***,for vortex pump with non-uniform section of tongue channel,the head diminishes and the efficiency remains constant approximately with the increase of the tongue width,while the head and the efficiency both diminish for uniform section of tongue channel.

关键词： Vortex pump Tongue clearance Non-uniform flow passage Numerical simulation

A physical model study of shale seismic responses and anisotropic inversion

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Petroleum Science 2021年第4期18卷 1059-1068页

作者： Pin-Bo Ding Fei Gong Feng Zhang xiang-yang li State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum(Beijing)Beijing102249China CNPC Key Laboratory of Geophysical Exploration China University of Petroleum(Beijing)Beijing102249China

The seismic responses of the shale properties are critical for shale gas reservoir evaluation and *** has been widely reported that the clay minerals have substantial influences on the seismic wave anisotropy and ***,knowing the seismic responses of the clay-rich shales and estimation of shale elastic properties are significant for the shale gas industry.A physical model containing two groups of shale blocks as the target formations is constructed in *** group S contains six shale blocks with different clay contents,and the group N contains six shale blocks with different *** acquired 2D seismic data is used to analyze the seismic responses of two corresponding seismic *** anisotropic three-term inversion method is applied to one of the seismic inline to estimate the elastic properties the target shale *** inversed attributes can be used to reveal the effects of shale clay *** study shows the substantial significance of using a physical model to observe the seismic responses of shale *** inversion results indicate that the anisotropic three-term inversion method could provide accurate results of elastic properties as well as the P-wave anisotropy parameter for shale formations.

关键词： Physical model Shale Clay AVO Anisotropy

Investigation of the shock compression behaviors of Al/PTFE composites with experimental and a 3D mesoscale-model

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Defence Technology（防务技术） 2022年第1期18卷 62-71页

作者： xiang-li yang Yong He Yuan He Chuan-ting Wang Jie Zhou Departnentsof Mecharical Engneering Nanjing Uriversity of Science&Technology NanjingJiangsu210094PR China Hubei Aeros pace Flight Vehide Institute Wuhan 430040PR China

The responses of Al/PTIFE reactive materials(RMs)under shock compression were investigated by a single-stage gas gun.A 3D mesoscale-model was established based on micro-computed tomography(micro-CT)slice images and confirmed with experimental *** the high-pressure stage,the com-posites reacted partially,whereas there were no deviations between the partially reacted Hugoniot and the inert simulation *** simulation reveals that the Teflon matrix melting on the high shock *** and decomposition of the PTFE accelerated the diffusion of the ***,the reactions of the Al/PTFE composites are more like a combustion rather than a detonation.

关键词： AI/PTFE reactive materials 3D mesoscale-model Shock-assisted reaction Shock Hugoniot

Comparison of the predictive value of anthropometric indicators for the risk of benign prostatic hyperplasia in southern China

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Asian Journal of Andrology 2023年第2期25卷 265-270页

作者： Meng-Jun Huang Yan-Yi yang Can Chen Rui-xiang Luo Chu-Qi Wen yang li ling-Peng Zeng xiang-yang li Zhuo Yin Department of Urology The Second Xiangya Hospital of Central South UniversityChangsha 410011China Health Management Center The Second Xiangya Hospital of Central South UniversityChangsha 410011China

This study aimed to compare the predictive value of six selected anthropometric indicators for benign prostatic hyperplasia(BPH).Males over 50 years of age who underwent health examinations at the Health Management Center of the Second xiangya Hospital,Central South University(Changsha,China)from June to December 2020 were enrolled in this *** characteristic data were collected,including basic anthropometric indices,lipid parameters,six anthropometric indicators,prostate-specific antigen,and total prostate *** odds ratios(ORs)with 95%confidence intervals(95%CIs)for all anthropometric parameters and BPH were calculated using binary logistic *** assess the diagnostic capability of each indicator for BPH and identify the appropriate cutoff values,receiver operating characteristic(ROC)curves and the related areas under the curves(AUCs)were *** six indicators had diagnostic value for BPH(all P≤0.001).The visceral adiposity index(VAI;AUC:0.797,95%CI:0.759–0.834)had the highest AUC and therefore the highest diagnostic *** was followed by the cardiometabolic index(CMI;AUC:0.792,95%CI:0.753–0.831),lipid accumulation product(LAP;AUC:0.766,95%CI:0.723–0.809),waist-to-hip ratio(WHR;AUC:0.660,95%CI:0.609–0.712),waist-to-height ratio(WHtR;AUC:0.639,95%CI:0.587–0.691),and body mass index(BMI;AUC:0.592,95%CI:0.540–0.643).The sensitivity of CMI was the highest(92.1%),and WHtR had the highest specificity of 94.1%.CMI consistently showed the highest OR in the binary logistic regression ***,WHtR,WHR,VAI,CMI,and LAP all influence the occurrence of BPH in middle-aged and older men(all P≤0.001),and CMI is the best predictor of BPH.

关键词： benign prostate hyperplasia obesity index predictive value risk prediction

Corrosion behavior of low-carbon Cr micro-alloyed steel for grounding grids in simulated acidic soil

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Journal of Iron and Steel Research International 2018年第7期25卷 755-766页

作者： Jian li Hang Su Feng Chai Dong-mei Xue li li xiang-yang li Hui-min Meng Division of Engineering Steel Central Iron and Steel Research Institute Beijing 100081 China Enterprise Management Department China Iron and Steel Research Institute Group Beijing 100081 China Corrosion and Protection Center University of Science and Technology Beijing Beijing 100083 China

To improve the corrosion resistance of steels for grounding grids, a low-carbon Cr micro-alloyed steel was developed （C 1 steel）, and corrosion behavior of Q235 steel and newly developed C1 steel in simulated acidic soil was investigated. The corrosion rate was evaluated with the mass loss measurements, while the corrosion morphology of surface and cross section of rust layer was observed by scanning electron microscopy. The corrosion products were analyzed by energy- dispersive X-ray spectrometry, X-ray diffraction and X-ray photoelectron spectroscopy, and the polarization curve was measured using potentiodynamic polarization method. Results indicated that C 1 steel displayed good corrosion resistance in the simulated acidic soil, of which the corrosion rate was only 30% of that of Q235 steel after corrosion for 360 h. The analysis of rust layer showed that lower carbon content in steel could reduce the tendency of micro cell corrosion and appropriate amount of chromium could improve the corrosion potential of metal matrix. Moreover, the analysis of X-ray photoelectron spectroscopy revealed that the chromium enriched in inner rust layer of C1 steel existed mainly in the form of Fe2CrO4, which facilitated the formation of Cr-goethite and improved the protection of corrosion products.

关键词： Soil corrosion Grounding grid Low-carbon steel Cr micro-alloying Corrosion product - Cr-goethite

A rock physics model for the characterization of organic-rich shale from elastic properties

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Petroleum Science 2015年第2期12卷 264-272页

作者： Ying li Zhi-Qi Guo Cai liu xiang-yang li Gang Wang College of Computer Science and Technology Jilin University College of Geo-Exploration Science and Technology Jilin University British Geological Survey CNPC Key Laboratory of Geophysical Prospecting China University of Petroleum

Kerogen content and kerogen porosity play a significant role in elastic properties of organic-rich shales. We construct a rock physics model for organic-rich shales to quantify the effect of kerogen content and kerogen porosity using the Kuster and Toks6z theory and the selfconsistent approximation method. Rock physics modeling results show that with the increase of kerogen content and kerogen-related porosity, the velocity and density of shales decrease, and the effect of kerogen porosity becomes more obvious only for higher kerogen content. We also find that the Poisson＇s ratio of the shale is not sensitive to kerogen porosity for the case of gas saturation. Finally, for the seismic reflection responses of an organic-rich shale layer, forward modeling results indicate the fifth type AVO re- sponses which correspond to a negative intercept and a positive gradient. The absolute values of intercept and gradient increase with kerogen content and kerogen porosity, and present predictable variations associated with velocities and density.

关键词： Rock physics Organic-rich shale Kerogencontent - Kerogen porosity - AVO

Privacy-Preserving Strategyproof Auction Mechanisms for Resource Allocation

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Tsinghua Science and Technology 2017年第2期22卷 119-134页

作者： Yu-E Sun He Huang xiang-yang li yang Du Miaomiao Tian Hongli Xu Mingjun Xiao School of Urban Rail Transportation Soochow University School of Computer Science and Technology Soochow University School of Computer Science and Technology University of Science and Technology of China Suzhou Institute for Advanced Study University of Science and Technology of China School of Computer Science and Technology Anhui University

In recent years, auction theory has been extensively studied and many state-of-the-art solutions have been proposed aiming at allocating scarce resources. However, most of these studies assume that the auctioneer is always trustworthy in the sealed-bid auctions, which is not always true in a more realistic scenario. Besides the privacy-preserving issue, the performance guarantee of social efficiency maximization is also crucial for auction mechanism design. In this paper, we study the auction mechanisms that consider the above two aspects. We discuss two multi-unit auction models： the identical multiple-items auction and the distinct multiple-items *** the problem of determining a multi-unit auction mechanism that can maximize its social efficiency is NPhard, we design a series of nearly optimal multi-unit auction mechanisms for the proposed models. We prove that the proposed auction mechanisms are strategyproof. Moreover, we also prove that the privacy of bid value from each bidder can be preserved in the auction mechanisms. To the best of our knowledge, this is the first work on the strategyproof multi-unit auction mechanisms that simultaneously consider privacy preservation and social efficiency maximization. The extensive simulations show that the proposed mechanisms have low computation and communication overheads.

关键词： approximation mechanism multi-unit auction privacy preserving social efficiency strategyproof

The Spatial Correlation between Crystalline and Amorphous Orientations of Isotactic Polypropylene during Plastic Deformation:An in situ Observation with FTIR Imaging

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Chinese Journal of Polymer Science 2015年第4期33卷 613-620页

作者： Wei Chen xiang-yang li Yan-ping liu Jing li Wei-ming Zhou 陈亮李良彬 National Synchrotron Radiation Lab and College of Nuclear Science and Technology CAS Key Laboratory of Soft Matter ChemistryUniversity of Science and Technology of China

On the basis of research method in FTIR imaging, we made a heterogeneous thin film of isotactic polypropylene （iPP） that contains a few large spherulites （-150 μm） which are surrounded by small spherulites （-15 μm） for tensile testing. The evolution processes of crystalline and amorphous orientations of iPP are monitored with its characteristic peaks at 998 and 973 cm^-1, respectively. By introducing the correlation images, the analysis demonstrates the relationships between the orientation evolutions of crystalline and amorphous phases in a space of 250 μm × 250 μm detecting area. During the plastic deformation, crystalline orientation is higher than amorphous orientation outside the large spherulite, while that is opposite inside the region. In addition, the evolutions of crystalline and amorphous orientations almost keep a positive correlation.

关键词： lsotactic polypropylene FTIR imaging Deformation Orientation evolution.