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Particle size dependence of the microsegregation and microstructure in the atomized Ni-based superalloy powders:Theoretical and experimental study

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Journal of Materials Science & Technology 2024年第4期171卷 54-65页

作者： Jikang Li Mingsheng Yang Yunfei Cai Yuanyuan Zhang Qingshuai Feng Jiantao liu tong liu Key Laboratory of Aerospace Materials and Performance(Ministry of Education)School of Materials Science and Engineering Beihang UniversityBeijing 100191China Central Iron and Steel Research Institute Beijing 100081China

The microstructure and microsegregation of atomized powder,which depend on their sizes,are of great importance to the mechanical properties of the consolidated bulk ***,it is necessary to reveal the relationship between particle size and powder *** effects of particle size on the so-lidification characterization of the atomized Ni-based superalloy powders were studied via finite element *** on the simulations,a model was developed to predict the microsegregation and mi-crostructure of atomized powders with different sizes and study the influence of thermal history on the powder attributes during the atomization *** radiation heat transfer and temperature gradi-ent within the rapid solidification alloy powders were taken into account in this *** validating the accuracy of the model,the predictions of the present model were compared with the microsegregation and microstructure of the specific size powder close to the screen mesh *** results showed that mi-crostructure depended primarily on the temperature gradient within the powder,while the solidification rate had a more significant effect on the *** model predicted microstructure features in agreement with the experiment,and for microsegregation,the deviations of prediction for most ele-ments were less than 10%.This work provides a new model to precisely predict the microsegregation and microstructure of the atomized alloy powders and sets a foundation to control the powder features for various engineering applications.

关键词： Particle size Solidification microstructure Microsegregation Numerical simulation

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Predicted Critical State Based on Invariance of the Lyapunov Exponent in Dual Spaces

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Chinese Physics Letters 2024年第1期41卷 68-76页

作者：刘通夏旭 Department of Applied Physics School of ScienceNanjing University of Posts and TelecommunicationsNanjing 210003China Academy of Mathematics and System Sciences Chinese Academy of SciencesBeijing 100190China

Critical states in disordered systems,fascinating and subtle eigenstates,have attracted a lot of research ***,the nature of critical states is difficult to describe quantitatively,and in general,it cannot predict a system that hosts the critical *** propose an explicit criterion whereby the Lyapunov exponent of the critical state should be 0 simultaneously in dual spaces,namely the Lyapunov exponent remains invariant under the Fourier *** this criterion,we can exactly predict a one-dimensional quasiperiodic model which is not of self-duality,but hosts a large number of critical ***,we perform numerical verification of the theoretical prediction and display the self-similarity of the critical *** to computational complexity,calculations are not performed for higher dimensional ***,since the description of extended and localized states by the Lyapunov exponent is universal and dimensionless,utilizing the Lyapunov exponent of dual spaces to describe critical states should also be ***,we conjecture that some kind of connection exists between the invariance of the Lyapunov exponent and conformal invariance,which can promote the research of critical phenomena.

关键词： state exponent critical

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Ash removal from inferior coal via ammonium fluoride roasting and simultaneous yield of white carbon black

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International Journal of Mining Science and Technology 2024年第2期34卷 261-279页

作者： Xuqin Duan Shuaiyu Lu Yuxiao Fu Jiazhe Zhang tong liu Jian Ma School of Civil and Resource Engineering University of Science&Technology BeijingBeijing 100083China State Key Laboratory for Efficient Mining of Metal Mines University of Science&Technology BeijingBeijing 100083China China Coal Processing and Utilizaiton Association Beijing 100013China

The quality upgrading and deashing of inferior coal by chemical method still faces great *** dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial *** paper systematically investigates the ash reduction and desilicification of two typical inferior coal utilizing ammonium fluoride roasting *** the optimal conditions,for fat coal and gas coal,the deashing rates are 69.02%and 54.13%,and the desilicification rates are 92.64%and 90.27%,*** molar dosage of ammonium fluoride remains consistent for both coals;however,the gas coal,characterized by a lower ash and silica content(less than half that of the fat coal),achieves optimum deashing effect at a reduced time and *** majority of silicon in coal transforms into gaseous ammonium fluorosilicate,subsequently preparing nanoscale amorphous silica with a purity of 99.90%through ammonia *** of the fluorine in deashed coal are assigned in inorganic minerals,suggesting the possibility of further fluorine and ash removal via *** research provides a green and facile route to deash inferior coal and produce nano-scale white carbon black simultaneously.

关键词： Inferior coal Deashing treatment Silicon recycling Ammonium fluoride roasting White carbon black

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Investigation of Eccentric PM on High-frequency Vibration in FSCW PM Machine Considering Force Modulation Effect

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Chinese Journal of Electrical Engineering 2024年第2期10卷 59-69页

作者： Jinghua Ji Weizhi Jiang Wenxiang Zhao tong liu School of Electrical and Information Engineering Jiangsu UniversityZhenjiang 212013China

This study investigates the negative influence of an eccentric permanent-magnet(PM)design on high-frequency electromagnetic vibration in fractional-slot concentrated-winding(FSCW)PM ***,an analytical expression for the sideband current harmonics was derived using the double Fourier series expansion ***,the characteristics of the flux-density harmonics are studied from the perspective of the space-time distribution and initial phase *** influence of the eccentric PM design on high-frequency electromagnetic and concentrated forces was studied based on the electromagnetic force modulation ***,an eccentric PM design is not conducive to reducing the 2pth-order high-frequency electromagnetic ***,two FSCW PM machines with conventional and eccentric PM designs are manufactured and tested to verify the theoretical *** results show that the eccentric PM design worsens high-frequency vibrations.

关键词： Eccentric permanent magnet machine sideband current harmonics electromagnetic force modulation effect fractional-slot concentrated-winding high-frequency vibration

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Atomically precise Ru-O-Ru clusters for enhanced water dissociation in alkaline hydrogen evolution

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Nano Research 2024年第8期17卷 6993-7000页

作者： Dong liu Li Xu Sicheng Li Airong Xu Yuanhua Sun tong liu Mengyuan liu Huijuan Wang Xiaokang liu Tao Yao Tao Ding Hefei National Research Center for Physical Sciences at the Microscale School of Nuclear Science and TechnologyKey Laboratory of Precision and Intelligent ChemistryNational Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230029China Experimental Center of Engineering and Materials Science University of Science and Technology of ChinaHefei 230026China

Atomic clusters typically exhibit distinctive electronic structures and physicochemical ***,as the size decreases,their ability to adsorb and dissociate water also diminishes,thereby affecting chemical reactions involving water *** the adsorption and dissociation capabilities of atomic clusters towards water molecules and elucidating the mechanisms underlying their performance enhancement have become important research ***,employing the carrier-anchored strategy,Ru-O-Ru atomic clusters were prepared and displayed excellent activity and durability in the hydrogen evolution ***,the Ru-O-Ru atomic clusters exhibited only 86 mV overpotential at 100 mA·cm−^(2)and superior membrane-electrode-assembly activity than commercial Ru/C *** radiation-based Fourier transform infrared spectroscopic measurements revealed that the modification of oxygen in Ru-O-Ru units promoted the reorientation of water molecules from a H-up orientation to H-down,therefore,enhanced the formation of strong hydrogen-bond network of interfacial water on the surface of Ru-O-Ru clusters,leading to enhanced adsorption and dissociation of water and accelerated Volmer *** findings provide a potential strategy and deep insights for the development of atomic clusters in electrocatalysts.

关键词： hydrogen evolution in-situ Fourier transform infrared(FTIR) Ru catalysts electrocatalysis atomic clusters

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High-efficiency preparation of multifunctional conjugated electrospun graphene doped PVDF/CF yarns for energy harvesting and human movement monitoring in TENG textile

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Nano Research 2024年第5期17卷 4478-4488页

作者： Ting Yang Chengwei Wan Xiaoyu Zhang tong liu Li Niu Jian Fang Yuqing liu College of Textile and Clothing Engineering Soochow UniversitySuzhou 215123China

Portable power is an effective solution to realize self-powered sensors for wearable devices,promoting future sustainable ***-based triboelectric nanogenerators(M-TENGs)have emerged as a promising technology for harvesting biomechanical energy from human motion owing to their advantages,such as simple structure,lightweight design,and efficient energy ***,the poor durability,low adaptability,and un-washability of two-dimensional membrane materials have largely hindered their application in wearable *** this study,we propose a sheath-core polyvinylidene fluoride(PVDF)/graphene(G)-carbon fiber(CF)yarn fabricated via conjugate electrospinning,comprising a commercial CF core and an electrospun graphene-doped PVDF sheath,which improves the fatigue resistance of electrospun nanofiber films under prolonged friction and keeps a high degree of *** resulting electronic textile,woven with the large-scale electrospun PVDF/G-CF yarn,demonstrates a remarkable power density of 25.5 mW·m^(-2).The tight distribution of PVDF/G nanofibers on the textile surface ensures excellent softness,washability,and ***,the electrospun PVDF/G-CF textile exhibits significant potential in pressure sensing,self-powered operation,and motion detection,making it highly suitable for wearable electronics applications.

关键词： yarn-based triboelectric nanogenerator(TENG) graphene polyvinylidene fluoride(PVDF) conjugated-electrospinning multifunctional

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Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

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Nano-Micro Letters 2024年第9期16卷 308-324页

作者： Na Yu Idris Temitope Bello Xi Chen tong liu Zheng Li Yufei Song Meng Ni Department of Building and Real Estate Research Institute for Sustainable Urban Development(RISUD)and Research Institute for Smart Energy(RISE)The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057GuangdongPeople’s Republic of China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyClear Water BayHong KongPeople’s Republic of China

Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode ***-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting ***,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting *** study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen *** D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling *** approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

关键词： Reversible protonic ceramic cells Air electrode Ruddlesden-Popper perovskite Hydration Oxygen reduction reaction

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Hyperbranched polymer hollow-fiber-composite membranes for pervaporation separation of aromatic/aliphatic hydrocarbon mixtures

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Chinese Journal of Chemical Engineering 2024年第5期69卷 13-22页

作者： tong liu Hao Sun Xiangqiong Wang Jie Li Zhanquan Zhang Pei Wu Naixin Wang Quanfu An Beijing Key Laboratory for Green Catalysis and Separation Department of Chemical EngineeringCollege of Materials Science and EngineeringBeijing University of TechnologyBeijing 100124China Petrochemical Research Institute CNPCBeijing 102206China

The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical *** is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing membrane materials with efficient separation performance is still the main task since the membrane should provide chemical stability, high permeation flux, and selectivity. In this study, the hyperbranched polymer(HBP) was deposited on the outer surface of a polyvinylidene fluoride(PVDF)hollow-fiber ultrafiltration membrane by a facile dip-coating method. The dip-coating rate, HBP concentration, and thermal cross-linking temperature were regulated to optimize the membrane *** obtained HBP/PVDF hollow-fiber-composite membrane had a good separation performance for aromatic/aliphatic hydrocarbon mixtures. For the 50%/50%(mass) toluene/n-heptane mixture, the permeation flux of optimized composite membranes could reach 1766 g·m^(-2)·h^(-1), with a separation factor of 4.1 at 60℃. Therefore, the HBP/PVDF hollow-fiber-composite membrane has great application prospects in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures.

关键词： Aromatic/aliphatic hydrocarbons Hyperbranched polymer Pervaporation Hollow fiber membrane Dip-coating

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Strategic Behavior Analysis and Modeling for Resilient Resource Allocation

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Journal of Systems Science and Information 2024年

作者： tong liu Saike HE University of Chinese Academy of Sciences China People's Police University State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of Automation Chines Academy of Sciences

In an era where power systems face increased cyber threats, social media data, especially public sentiment during outages, emerges as a crucial component for devising defense strategies. We present a methodology that integrates sentiment analysis of social media data with advanced reinforcement learning techniques to tackle uncertain load redistribution cyberattacks. This approach first employs VADER and Support Vector Machine(SVM) sentiment analysis on collected social media data, revealing insightful information about power outages and public sentiment. Proximal Policy Optimization(PPO), a state-of-the-art reinforcement learning method, is then applied in the second stage to leverage these insights, manage outage uncertainty, and optimize defense strategies. The efficacy of this methodology is demonstrated on a modified IEEE 6-bus system. The results underscore our approach’s effectiveness in utilizing social media data for a nuanced, targeted response to *** pioneering methodology offers a promising direction for enhancing power grid resilience against cyberattacks and natural disasters, highlighting the value of social media sentiment analysis in power systems security.

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Laser-assisted synthesis of PtPd alloy for efficient ethanol oxidation

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Nano Research 2024年第7期17卷 6032-6037页

作者： Zihang Chen tong liu Huijuan Zhang Beibei Pang Yuanhua Sun Longfei Hu Qiquan Luo Xiaokang liu Linlin Cao Tao Yao School of Nuclear Science and Technology National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230029China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China

The inefficiency of ethanol oxidation reaction(EOR)presents a significant obstacle in harnessing renewable biofuels with high energy density into *** efforts,most Pt-based catalysts still suffer from drawbacks such as poor activity and susceptibility to CO poisoning,particularly in acidic ***,we employed a physical laser-assisted approach to synthetize a PtPd alloy with a 1:1 atomic *** alloy demonstrates remarkable performance in acidic EOR,boasting a high mass activity of 1.86 A·mgPt^(−1)and competitive resistance to *** in situ synchrotron radiation infrared spectroscopy with theoretical calculations,we reveal that the synergic interaction between Pt and Pd enhances both the adsorption of OH*intermediate and the dehydrogenation ability of *** work will prove the feasibility of synthesizing bimetallic alloys by a physical laser-assisted strategy and promote the development of advanced alloy electrocatalysts.

关键词： laser-assisted strategy Pt-based alloy in situ synchrotron radiation infrared spectroscopy ethanol oxidation reaction synergic interaction

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