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Evolution of inclusions in vacuum induction melting of superalloys containing 70%return material

Journal of Iron and Steel Research International 2024年第3期31卷 719-728页

作者： Jin-guo gao shu-lei Yang shu-feng Yang Jing-she Li Wei Liu Meng-jing Zhao An-ren Wang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Metallurgical and Building Materials Business Department China International Engineering Consulting CorporationBeijing 100048China

The variation law of inclusions type and size in the vacuum induction melting process and ingot of Ni-based superalloy containing 70%return material was studied by industrial test sampling,and the mechanism of inclusions formation was analyzed with thermodynamic *** results show that there are mainly two types of composite inclusions in the vacuum induction melting of Ni-based superalloys,which are nitride-and oxide-based composite inclusions,like Al_(2)O_(3)-SiO_(2)-Cr_(2)O_(3),TiN-(Mo,Nb)C,*** type and proportion of inclusions from the center to the edge of the vacuum induction ingot did not change *** number density of inclusions from the center to the edge of the ingot varied less,and the size of inclusions became smaller from the center to the *** addition,thermodynamic calculations show that oxides(M_(2)O_(3))are present in the liquid phase and mainly contain Al,Ti,Cr,Fe and O *** nitride consists mainly of Ti and N and contains small amounts of Cr,C,Nb,and Mo *** is consistent with the results of industrial *** the temperature decreases,the precipitation phases such as M_(2)O_(3),MN,γ,MC,δ,γ'andμphases are gradually precipitated,where oxides and nitrides are present in the liquid *** contents of O and N elements are the main influencing factors for the inclusions content and precipitation temperature;when the nitrogen content is reduced to below 0.0015%,it can make MN precipitate below the liquid-phase line.

关键词： Ni-based superalloy Vacuum induction melting Return material Inclusion Thermodynamic

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Exploring the impact of economic growth and energy consumption on SO2 emissions in China based on the Environmental Kuznets Curve hypothesis

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Petroleum Science 2024年第4期21卷 2892-2900页

作者： Bing-Jie Xu Yi-Fei Shen hui Qiao Zhi gao Faculty of Business City University of Macau Rural Development Institute Chinese Academy of Social Sciences School of Marxism Shenzhen Polytechnic University

This study aims to analysis the influence of economic growth(EG) and energy consumption(EC) on sulfur dioxide emissions(SE) in China. Accordingly, this study explores the link between EG, EC, and SE for 30 provinces in China over the span of 2000-2019. This study also analyzes cross-sectional dependence tests, panel unit root tests, Westerlund panel cointegration tests, Dumitrescu-Hurlin(D-H) causality tests. According to the test results, there is an inverted U-shaped association between EG and SE,and the assumption of the Environmental Kuznets Curve(EKC) is verified. The signs of EG and EC in the fixed effect(FE) and random effect(RE) methods are in line with those in the dynamic ordinary least squares(DOLS), fully modified ordinary least squares(FMOLS) and autoregressive distributed lag(ARDL)estimators. Moreover, the results verified that EC can obviously positive impact the SE. To reduce SE in China, government and policymakers can improve air quality by developing cleaner energy sources and improving energy efficiency. This requires the comprehensive use of policies, regulations, economic incentives, and public participation to promote sustainable development.

关键词： SO 2 emissions Economic growth Energy consumption EKC China

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Role of polarization evolution in the hysteresis effect of Pb-based antiferroelecrtics

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Chinese Chemical Letters 2024年第4期35卷 516-519页

作者： Botao gao He Qi hui Liu Jun Chen Beijing Advanced Innovation Center for Materials Genome Engineering Department of Physical ChemistryUniversity of Science and Technology BeijingBeijing 100083China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 201899China Hainan University Haikou 570228China

The electric field-induced irreversible domain wall motion results in a ferroelectric(FE) hysteresis. In antiferroelectrics(AFEs), the irreversible phase transition is the main reason for the hysteresis effects, which plays an important role in energy storage performance. Compared to the well-demonstrated FE hysteresis,the structural mechanism of the hysteresis in AFE is not well understood. In this work, the underlying correlation between structure and the hysteresis effect is unveiled in Pb(Zr,Sn,Ti)O_(3) AFE system by using in-situ electrical biasing synchrotron X-ray diffraction. It is found that the AFE with a canting dipole configuration, which shows a continuous polarization rotation under the electric field, tends to have a small hysteresis effect. It presents a negligible phase transition, a small axis ratio, and electric field-induced lattice changing, small domain switching. All these features together lead to a slim hysteresis loop and a high energy storage efficiency. These results offer a deep insight into the structure-hysteresis relationship of AFEs and are helpful for the design of energy storage material.

关键词： Antiferroelectric Hysteresis effect Structure refinement Perovskite In situ synchrotron radiation

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Fe-Induced Electronic Transfer and Structural Evolution of Lotus Pod-Like CoNiFePx@P,N-C Heterostructure for Sustainable Oxygen Evolution

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Energy & Environmental Materials 2024年第3期7卷 186-193页

作者： Xiaojun Zeng Qingqing Zhang Chulong Jin hui Huang Yanfeng gao Advanced Ceramic Materials Research Institute School of Materials Science and EngineeringJingdezhen Ceramic University Singapore Institute of Technology School of Materials Science and Engineering Shanghai University

Transition metal phosphides with metallic properties are a promising candidate for electrocatalytic water oxidation,and developing highly active and stable metal phosphide-based oxygen evolution reaction catalysts is still ***,we present a facile ion exchange and phosphating processes to transform intestine-like CoNiPx@P,N-C into lotus pod-like CoNiFePx@P,N-C heterostructure in which numerous P,N-codoped carboncoated CoNiFePxnanoparticles tightly anchors on the 2D carbon ***,the as-prepared CoNiFePx@P,N-C enables a core-shell structure,high specific surface area,and hierarchical pore structure,which present abundant heterointerfaces and fully exposed active ***,the incorporation of Fe can also induce electron transfer in CoNiPx@P,IM-C,thereby promoting the oxygen evolution ***,CoNiFePx@P,IM-C delivers a low overpotential of 278 mV （vs RHE） at a current density of10 mA cm-1and inherits excellent long-term stability with no observable current density decay after 30 h of chronoamperometry *** work not only highlights heteroatom induction to tune the electronic structure but also provides a facile approach for developing advanced and stable oxygen evolution reaction electrocatalysts with abundant heterointerfaces.

关键词： electronic transfer Fe exchange multi-metal phosphides OER electrocatalysts structural evolution

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Asymptotic normality of error density estimator in stationary and explosive autoregressive models

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 140-158页

作者： WU Shi-peng YANG Wen-zhi gao Min HU shu-he School of Mathematical Sciences&School of Big Data and Statistics Anhui UniversityHefei 230601China School of Statistics Shanxi University of Finance and EconomicsTaiyuan030006China

In this paper,we consider the limit distribution of the error density function estima-tor in the rst-order autoregressive models with negatively associated and positively associated random *** mild regularity assumptions,some asymptotic normality results of the residual density estimator are obtained when the autoregressive models are stationary process and explosive *** order to illustrate these results,some simulations such as con dence intervals and mean integrated square errors are provided in this *** shows that the residual density estimator can replace the density\estimator"which contains errors.

关键词： explosive autoregressive models residual density estimator asymptotic distribution association sequence

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Aggregation-induced delayed electrochemiluminescence of organic dots in aqueous media

Aggregate

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Aggregate 2024年第1期5卷 167-174页

作者： Hang gao Shen-Yu Shi shu-MinWang Qian-Qian Tao hui-Li Ma Jun Hu Hong-Yuan Chen Jing-Juan Xu State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical EngineeringNanjing UniversityNanjingChina Key Laboratory of Flexible Electronics(KLOFE)and Institute of Advanced Materials(IAM) Nanjing Tech UniversityNanjingChina School of Life Science and Health Engineering Jiangnan UniversityWuxiChina

Full utilization of the excited species at both singlet states(1R*)and triplet states(3R*)is crucial to improving electrochemiluminescence(ECL)efficiency but is challenging for organic luminescent ***,an aggregation-induced delayed ECL(AIDECL)active organic dot(OD)containing a benzophenone acceptor and dimethylacridine donor is reported,which shows high ECL efficiency via reverse intersystem crossing(RISC)of non-emissive 3R*to emissive 1R*,overcoming the spin-forbidden radiative decay from 3R*.By introducing dual donor-acceptor pairs into luminophores,it is found that nonradiative pathway could be further suppressed via enhanced intermolecular weak interactions,and multiple spin-up conversion channels could be *** a consequence,the obtained OD enjoys a 6.8-fold higher ECL efficiency relative to the control AIDECL-active ***-crystal studies and theoretical calculations reveal that the enhanced AIDECL behaviors come from the acceleration of both radiative transition and *** work represents a major step towards purely organic,high-efficiency ECL dyes and a direction for the design of next-generation ECL dyes at the molecular level.

关键词： aggregation-induced delayed electrochemiluminescence benzophenone dimethylacridine organic dots reverse intersystem crossing

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Vibration Suppression for Active Magnetic Bearings Using Adaptive Filter with Iterative Search Algorithm

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CES Transactions on Electrical Machines and Systems 2024年第1期8卷 61-71页

作者： Jin-hui Ye Dan Shi Yue-Sheng Qi Jin-hui gao Jian-Xin Shen IEEE Department of Electrical Engineering Zhejiang UniversityHangzhou 310027China CES and IEEE

Active Magnetic Bearing(AMB) is a kind of electromagnetic support that makes the rotor movement frictionless and can suppress rotor vibration by controlling the magnetic force. The most common approach to restrain the rotor vibration in AMBs is to adopt a notch filter or adaptive filter in the AMB controller. However, these methods cannot obtain the precise amplitude and phase of the compensation current. Thus, they are not so effective in terms of suppressing the vibrations of the fundamental and other harmonic orders over the whole speed range. To improve the vibration suppression performance of AMBs,an adaptive filter based on Least Mean Square(LMS) is applied to extract the vibration signals from the rotor displacement signal. An Iterative Search Algorithm(ISA) is proposed in this paper to obtain the corresponding relationship between the compensation current and vibration signals. The ISA is responsible for searching the compensating amplitude and shifting phase online for the LMS filter, enabling the AMB controller to generate the corresponding compensation force for vibration suppression. The results of ISA are recorded to suppress vibration using the Look-Up Table(LUT) in variable speed range. Comprehensive simulations and experimental validations are carried out in fixed and variable speed range, and the results demonstrate that by employing the ISA, vibrations of the fundamental and other harmonic orders are suppressed effectively.

关键词： Active Magnetic Bearing(AMB) Adaptive filter Iterative search algorithm Least mean square(LMS) Vibration suppression

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Characteristics of life-cycle carbon dioxide emissions of arterial highway maintenance and the influencing factors

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Advances in Climate Change Research 2024年第4期15卷 751-765页

作者： Yao WANG Yuan-Qing WANG shu-Juan JI Si-Jia SUN shu-Hong MA Ya-Nan gao Key Laboratory of Transport Industry of Management Control and Cycle Repair Technology for Traffic Network Facilities in Ecological Security Barrier Area Chang'an UniversityXi'an 710064China Guangzhou Aids to Navigation Office Southem Navigation Service CenterMaritime Safety AdministrationGuangzhou 51000China

With the focus of highway development transitioning from construction to maintenance,a comprehensive understanding of the characteristics and influencing factors of carbon dioxide(CO_(2))emissions from highway maintenance activities is crucial for formulating effective strategies to promote the low-carbon development of road ***,the quantitative relationships between CO_(2) emissions from highway maintenance schemes and factors such as pavement deterioration,traffic volume,and road grade remain unclear owing to a lack of compre-hensive,multi-category,and real *** real maintenance data from 340 arterial highway segments in China,this study conducts the life cycle assessment(LCA)to estimate CO_(2) emissions from maintenance activities and examines the primary emission sources among various structural layers and ***,multiple linear regression(MLR)analysis is conducted to investigate the impact of traffic volume,road grade,and pavement deterioration on CO_(2) emissions from maintenance projects,and factors influencing the early-stage degradation of pavement *** results demonstrate that average CO_(2) emissions from heavy rehabilitation projects are 6.97 times higher than those from medium rehabilitation *** from heavy rehabilitation projects exhibit a significantly negative linear relationship with the riding quality index(RQI)before maintenance(p<0.05),and emissions from medium rehabilitation projects show a significant negative linear relationship with the pavement condition index(PCI)before maintenance(p<0.05).Emissions from heavy and medium rehabilitation projects are significantly positively correlated with heavy vehicle traffic volume before maintenance(p<0.05).Moreover,the early-stage degradation of PCI after heavy rehabilitation and RQI after medium rehabilitation exhibit significantly negative linear relationships with their respective in-dicators before maintenance(p<0.05).The early-stage d

关键词： Life cycle assessment(LCA) Arterial highway Maintenance Emission factor Pavement performance Traffic volume

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Reasonable grazing may balance the conflict between grassland utilization and soil conservation in the semi-arid hilly areas, China

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Journal of Arid Land 2024年第8期16卷 1130-1146页

作者： SUN hui ZHAO Yunge gao Liqian XU Mingxiang College of Forestry Northwest A&F UniversityYangling 712100China College of Soil and Water Conservation Science and Engineering Institute of Soil and Water ConservationNorthwest A&F UniversityYangling 712100China

Soil erosion caused by unsustainable grazing is a major driver of grassland ecosystem degradation in many semi-arid hilly areas in ***,grazing exclusion is considered as an effective method for solving this issue in such ***,some ecological and economic problems,such as slow grassland rejuvenation and limited economic conditions,have become obstacles for the sustainable utilization of grassland ***,we hypothesized that the conflict between grassland use and soil conservation may be balanced by a reasonable grazing *** this study,a two-year grazing fence experiment with five grazing intensity gradients was conducted in a typical grassland of the Loess Plateau in China to evaluate the responses of vegetation characteristics and soil and water losses to grazing *** five grazing intensity gradients were 2.2,3.0,4.2,6.7,and 16.7 goats/hm2,which were represented by G1-G5,respectively,and no grazing was used as *** results showed that a reasonable grazing intensity was conducive to the sustainable utilization of grassland *** biomass under G1-G4 grazing intensity significantly increased by 51.9%,42.1%,36.9%,and 36.7%,respectively,compared with *** addition,vegetation coverage increased by 19.6%under G1 grazing *** diversity showed a single peak trend with increasing grazing *** Shannon-Wiener diversity index under G1-G4 grazing intensities significantly increased by 22.8%,22.5%,13.3%,and 8.3%,respectively,compared with ***,grazing increased the risk of soil *** with control,runoff yields under G1-G5 grazing intensities increased by 1.4,2.6,2.8,4.3,and 3.9 times,respectively,and sediment yields under G1-G5 grazing intensities were 3.0,13.0,20.8,34.3,and 37.7 times greater,respectively,than those under *** result was mainly attributed to a visible decrease in litter biomass after grazing,which decreased by 50.5%,72.6%,79.0%,80.0%

关键词： fence-controlled grazing rehabilitated grassland vegetation community characteristics soil erosion sediment biocrusts Loess Plateau

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Aerodynamic/stealth design of S-duct inlet based on discrete adjoint method

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 725-746页

作者： Jun DENG Ke ZHAO Lin ZHOU Wei ZHANG Bowen shu Jiangtao HUANG Zhenghong gao School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Aerospace Technology Institute of China Aerodynamic Research and Development CenterMianyang 621000Sichuan ProvinceChina

It is a major challenge for the airframe-inlet design of modern combat aircrafts,as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very *** this study,an aerodynamic/stealth optimization design method for an S-duct inlet is *** upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow *** multilevel fast multipole algorithm(MLFMA)is utilized for the stealth adjoint equation.A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth *** the aerodynamic and stealth characteristics of the inlet are effectively ***,the optimization results are analyzed,and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and crosssectional *** S-duct is smoothed,and the cross-sectional area is increased to improve the aerodynamic characteristics,while it is completely opposite for the stealth *** radar cross section(RCS)is reduced by phase cancelation for low frequency *** method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system.

关键词： S-duct inlet aerodynamic/stealth optimization design discrete adjoint upwind scheme multilevel fast multipole algorithm(MLFMA)

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