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Design of process parameters for direct squeeze casting

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Journal of University of Science and Technology Beijing 2008年第3期15卷 339-343页

作者： Milan Zhang Shuming Xing Liming Xiao Peiwei bao Wen Liu qiao Xin Semisolid Forming Research Center Beijing Jiaotong University Beijing 100044 China Department of Mathematics lli Normal University Yining 835000 China

On the basis of the analysis of solidification interval and temperature distribution of components manufactured by the squeeze casting method, formulas for calculating the solidification interval and compaction pressure were deduced according to the principal request that the compaction pressure should be equal to or greater than the plastic deformation resistance of the forming component when solidification ended. The solidification interval was proven to be associated with many factors, such as weight of the component, specific heat of the alloy, latent heat, pouring temperature, component temperature at the end of solidification and heat-transfer coefficients. The compaction pressure was related to the strain rate, deformation temperature, and dimension of the de- forming component. The solidification interval and compaction pressure calculated by the formulas deduced in this article were adopted in the production of 45 steel bidirectional chapiter valves, and components with excellent oerformance were manufactured.

关键词： squeeze casting solidification time temperature distribution compaction pressure

Microstructural evolution and mechanical properties of a new Ni-based heat-resistant alloy during aging at 750℃

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Journal of Iron and Steel Research International 2017年第5期24卷 513-519页

作者： Zhong-liang Tian Sen-bao Jiang Zheng-zong Chen Han-sheng bao Zheng-dong Liu Institute for Special Steels Central Iron and Steel Research Institute College of Material Science & Engineering Taiyuan Science & Technology University

Microstructural evolution and mechanical properties of a new candidate Ni-based heat-resistant alloy for advanced ultra-supercritical （A-USC） steam turbine rotors were investigated during aging at 750℃ up to 10000 h. The evolutions of γ＇ particles inside austenitic grain and M_23 C_6 carbides along grain boundaries were characterized according to their morphologies, distributions, and growth kinetics. Mean radius of the γ＇ spherical particles grew from 20.3 to 90.0 nm after aging for 10000 h, and;the corresponding coarse- ning behavior was conformed to the law of Lifschitz-Slyosovd-Wagner （LSW）. The weight fraction of γ＇ particles slightly increased from 10.0 to 12.0 wt. % after aging of long duration at 750 ℃.The Cr-rich M_23C_6 carbides discontinuously precipitated along grain boundaries, while other detrimental phases were not formed during the aging treatment, and hence the strength of grain boundary was enhanced by these discontinuously distributed carbides. The critical size of γ＇ had a direct influence on the maximum hardness of this alloy. Moreover, this alloy presented a good impact toughness for the safety after long time aging at high temperature.

关键词： Aging Precipitation Microstruetural evolution Mechanical property Heat-resistant alloy

Research on the comprehensive performance of PrFeB magnets for synchrotron radiation and free electron laser

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Nuclear Science and Techniques 2019年第8期30卷 12-18页

作者： Yong-Zhou He Xiao-Qing bao Wei Zhang qiao-Gen Zhou The Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China The University of Science and Technology Beijing(USTB) Beijing 100083China

PrFeB magnets, which possess excellent magnetic properties at low temperatures, have important application value as cryogenic permanent magnet undulators for synchrotron radiation sources and free electron lasers. In this research study, several high-performance PrFeB magnets(P42H, P48SH, and P48UH) were prepared, and their performance was comprehensively examined, including evaluations of their magnetic properties,microstructures, uniformity, and stability. Next,their application prospects were analyzed and discussed. In China, the first cryogenic permanent magnet undulators(CPMUs) with P48SH magnets with 18 mm cycle lengths have been developed. When the temperature is 80 K and the gap is 6.0 mm,the magnetic field measurement results of the CPMU showed that the effective magnetic field peak was approximately 0.92 T, yielding an increase of 11.76% relative to operation at 300 K, with an RMS phase error of about 4.99°.

关键词： PrFeB magnets Cryogenic permanent magnetundulators Grain boundary diffusion method Freeelectron laser

Effect of annealing time on the exchange coupling interactions and microstruc-ture of nanocomposite Pr_(7.5)Dy_1Fe_(71)Co_(15)Nb_1B_(4.5) ribbons

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Journal of University of Science and Technology Beijing 2007年第6期14卷 547-551页

作者： Xiaoqian bao Yi qiao Xuexu Gao Maocai Zhang Jie Zhu Shouzeng Zhou State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer （VSM）, X-ray diffraction （XRD） and high resolution transmission electron microscopy （HRTEM）. Interaction domains derived from strong exchange coupling interactions between hard and soft magnetic grains were imaged using magnetic force microscopy （MFM）. Maximum remanence, intrinsic coercivity, and maximum energy product values were obtained in the ribbons annealed at 700℃ for 15 min, which were composed of Pr2（Fe, Co）14B, α-（Fe, Co）, and slight Pr2（Fe, CO）17 phases. Although Jr, Hci, and （Bn）max decreased gradually with further increase of annealing time, it is emphasized that comparatively high Jr and Hci and （BH）max were obtained in a wide annealing time period of 15 to 360 min. The shape of initial magnetization curves and hysteresis loops change as a function of annealing time, indicating different magnetization reversal routes, which can be fully explained by the corresponding microstructure.

关键词： nanocomposite magnets exchange coupling interaction microstructure magnetization reversal

Gasification of Organic Waste:Parameters,Mechanism and Prediction with the Machine Learning Approach

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Journal of Renewable Materials 2023年第6期11卷 2771-2786页

作者： Feng Gao liang bao Qin Wang Yibin Research Institute Southwest Jiaotong UniversityYibinChina Office of Domestic Cooperation and Educational Training Management Southwest Jiaotong UniversityChengduChina School of Computer Science and Technology Xidian UniversityXi’anChina Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengduChina

Gasification of organic waste represents one of the most effective valorization pathways for renewable energy and resources recovery,while this process can be affected by multi-factors like temperature,feedstock,and steam content,making the product’s prediction *** the popularization and promotion of artificial intelligence such as machine learning(ML),traditional artificial neural networks have been paid more attention by researchers from the data science field,which provides scientific and engineering communities with flexible and rapid prediction frameworks in the field of organic waste *** this work,critical parameters including temperature,steam ratio,and feedstock during gasification of organic waste were reviewed in three scenarios including steam gasification,air gasification,and oxygen-riched gasification,and the product distribution and involved mechanism were ***,we presented the details of ML methods like regression analysis,artificial neural networks,decision trees,and related methods,which are expected to revolutionize data analysis and modeling of the gasification of organic *** outputs including the syngas yield,composition,and HHVs were discussed with a better understanding of the gasification process and ML *** review focused on the combination of gasification and ML,and it is of immediate significance for the resource and energy utilization of organic waste.

关键词： Gasification organic waste machine learning gas composition

A reaction density functional theory study of solvent effect in the nucleophilic addition reactions in aqueous solution

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Green Energy & Environment 2022年第4期7卷 782-791页

作者： Cheng Cai Weiqiang Tang Chongzhi qiao Bo bao Peng Xie Shuangliang Zhao Honglai Liu State Key Laboratory of Chemical Engineering and School of Chemical Engineering East China University of Science and TechnologyShanghai200237China School of Chemistry and Molecular Engineering East China University of Science and TechnologyShanghai200237China Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology School of Chemistry and Chemical EngineeringGuangxi UniversityNanning530004China

Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular ***,by taking the case study of nucleophilic addition reaction in aqueous solution,we extend the proposed multiscale reaction density functional theory(RxDFT)method to investigate the intrinsic free energy profile and total free energy profile,and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous *** predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP ***,the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous *** addition,we investigate the solvent effect on the reactions occurred near solid-liquid *** is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10A distance to the substrate surface owing to the decrease of hydration free energy at the solid-liquid interface.

关键词： Reaction density functional theory Nucleophilic addition Solvent effect Charge models

Chronic Kidney Disease Induces Cognitive Impairment in the Early Stage

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Current Medical Science 2023年第5期43卷 988-997页

作者： Yu WANG Kai CHEN Zi-xuan qiao Xiao-rong bao Department of Nephrology Jinshan HospitalFudan UniversityShanghai 201508China

Objective Previous research indicates a link between cognitive impairment and chronic kidney disease(CKD),but the underlying factors are not fully *** study aimed to investigate the progression of CKD-induced cognitive impairment and the involvement of cognition-related proteins by developing early-and late-stage CKD models in Sprague-Dawley *** The Morris water maze test and the step-down passive avoidance task were performed to evaluate the cognitive abilities of the rats at 24 weeks after *** examinations were conducted to examine renal and hippocampal ***-time PCR,Western blotting analysis,and immunohistochemical staining were carried out to determine the hippocampal expression of brain-derived neurotrophic factor(BDNF),choline acetyltransferase(ChAT),and synaptophysin(SYP).Results Compared with the control rats,the rats with early-stage CKD exhibited mild renal damage,while those with late-stage CKD showed significantly increased serum creatinine levels as well as apparent renal and brain *** rats with early-stage CKD also demonstrated significantly impaired learning abilities and memory compared with the control rats,with further deterioration observed in the rats with late-stage ***,we observed a significant downregulation of cognition-related proteins in the hippocampus of rats with early-stage CKD,which was further exacerbated with declining renal function as well as worsening brain and renal damage in rats with late-stage *** These results suggest the importance of early screening to identify CKD-induced cognitive dysfunction *** addition,the downregulation of cognition-related proteins may play a role in the progression of cognitive dysfunction.

关键词： chronic kidney disease cognitive impairment Morris water maze test brain-derived neurotrophic factor choline acetyltransferase synaptophysin

An adaptive finite-difference method for seismic traveltime modeling based on 3D eikonal equation

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Petroleum Science 2024年第1期21卷 195-205页

作者： bao-Ping qiao Qing-Qing Li Wei-Guang He Dan Zhao Qu-Bo Wu CNNC Beijing Research Institute of Uranium Geology Beijing 100029China National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580ShangdongChina SINOPEC Geophysical Research Institute Nanjing211103JiangsuChina

3D eikonal equation is a partial differential equation for the calculation of first-arrival traveltimes and has been widely applied in many scopes such as ray tracing,source localization,reflection migration,seismic monitoring and tomographic *** recent years,many advanced methods have been developed to solve the 3D eikonal equation in heterogeneous ***,there are still challenges for the stable and accurate calculation of first-arrival traveltimes in 3D strongly inhomogeneous *** this paper,we propose an adaptive finite-difference(AFD)method to numerically solve the 3D eikonal *** novel method makes full use of the advantages of different local operators characterizing different seismic wave types to calculate factors and traveltimes,and then the most accurate factor and traveltime are adaptively selected for the convergent updating based on the Fermat *** with global fast sweeping describing seismic waves propagating along eight directions in 3D media,our novel method can achieve the robust calculation of first-arrival traveltimes with high precision at grid points either near source point or far away from source point even in a velocity model with large and sharp *** numerical examples show the good performance of the AFD method,which will be beneficial to many scientific applications.

关键词： 3D eikonal equation Accurate traveltimes Global fast sweeping 3D inhomogeneous media Adaptive finite-difference method

Effects of Sulphate-reducing Bacteria on Corrosion Behaviour of 2205 Duplex Stainless Steel

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Journal of Iron and Steel Research International 2014年第4期21卷 444-450页

作者： Cheng-hao liang Hua WANG Nai-bao HUANG Transportation Equipments and Ocean Engineering College Dalian Maritime University School of Chemical Engineering Dalian University of Technology

The effects of sulphate-reducing bacteria （SRB） on the 2205 duplex stainless steel in the sea water and oil industry environments were studied by electrochemical impedance spectroscopy （EIS）, potentiodynamic polarization and microorganism analysis. The results showed that the detected SRB was the non-spore bacillus of about 0.8μm×（1.8--2.2）μm in size and the content of S was about 7. 59% in the corrosion products. SRB contributed to the corrosion evolution which caused the corrosion failure of 2205 duplex stainless steel pipe in the liquid hydrocarbon cooler. During the corrosion process, the produced H2S could significantly influence the anodic process and finally accelerate the corrosion. SEM observation indicated that the distribution of SRB on the surface of 2205 duplex stainless steel was nonuniform. X ray photoelectron spectroscopy analysis revealed that the surface film was composed of Cr2O3, MoO3 , FeS, FeS2, Fe（OH）2 and FeO after immersing the sample in the SRB medium for 14 d.

关键词： 2205 duplex stainless steel sulphate-reducing bacteria sea water corrosion electrochemistry